Johanna Knapp, University of Vienna
GLSMs, CYs, and LocalizationGauged linear sigma models (GLSMs) can be used to study Calabi-Yaus and their moduli spaces. Recent results in supersymmetric localization have made it possible to compute exact, i.e. fully quantum corrected, quantities that are relevant in string compactifications directly in the GLSM. After a review of the general framework, I will present some recent applications, with focus on the sphere and hemisphere partition function of the GLSM.
Nikta Fakhri, MIT
Thermodynamics of active matterCellular structures constantly consume and dissipate energy on a variety of spatiotemporal scales in order to function. While progress has been made in elucidating their organizing principles, much of their thermodynamics remains unknown. In this talk, I will address the question: why measure dissipation in such nonequilibrium systems? I will show that by measuring a multi-scale irreversibility (time-reversal asymmetry) one can extract model-independent estimates of the time-scales of energy dissipation based on time series data collected in an experimental biological system. I further demonstrate that the irreversibility measure maintains a monotonic relationship with the underlying biological nonequilibrium activity. The basic idea of estimating irreversibility for various levels of coarse-graining is quite general; we expect it to lead to important inferences whenever there is a well-defined notion of dissipative scale.
Lulu Qian, The Department of Bioengineering, Caltech
Algorithmic and Architectural Foundations for Programmable Molecular Machines: DNA Robots, Information-processing Circuits, and Reconfigurable NanostructuresThe primary focus of my lab is to help establish the algorithmic and architectural foundations for artificial molecular machines, through rationally designed and synthesized nucleic-acid systems that exhibit programmable behaviors. We aim to better understand how complex network behaviors arise from simple molecular building blocks, to establish forward engineering principles for information processing with molecules, to precisely manipulate matter at the nanoscale and embed control within biochemical environments, and eventually, to create artificial molecular machines that approach the complexity and sophistication of the natural ones and are fully programmable by humans.
In this talk, I will discuss our recent contributions in three areas: molecular robots, information-processing circuits, and reconfigurable DNA nanostructures.
First, we developed molecular robots that autonomously and collectively perform a sophisticated mechanical task: exploring the surface of a DNA nanostructure, picking up multiple types of cargo molecules and sorting each type to a designated location (Thubagere et al., Science, 2017). This work exploits random walks for energy-efficient mechanical behaviors, demonstrates the importance of simple algorithms and modular building blocks, and provokes further development of general-purpose molecular robotics.
Second, we created biochemical circuits that can classify highly complex and noisy molecular information, based on the similarity to a set of memories stored in DNA-based artificial neural networks (Cherry et al., Nature, 2018). This work shows how competition between molecules can be used to process complex information, establishes the record for how much intelligence can be built into artificial molecular machines, and paves the way for programming molecules to learn from their environment.
Finally, we invented a hierarchical and recursive strategy that allows DNA nanostructures with increasing sizes and arbitrary patterns to be created using a small and constant set of unique DNA strands (Tikhomirov et al., Nature, 2017). Subsequently, we discovered a simple yet powerful mechanism that controls the dynamic interactions between complex DNA nanostructures. Utilizing this mechanism, we demonstrated information-based autonomous reconfiguration in systems of interacting DNA nanostructures (Petersen et al., Nature Communications, 2018). Together, the two approaches provide significantly advanced structural components for building artificial molecular machines.
I hope to illuminate an ever-more-promising future for molecular sciences, empowered by the advances in DNA nanotechnology and molecular programming – a field that has its roots in physics, computer science, and engineering, and is anticipated to revolutionize the methods in many othe
Eric Klein, PhD, Rutgers University-Camden
Adaptation to phosphate-limitation in Caulobacter crescentusBacteria are constantly encountering new environmental conditions that require a variety of adaptations including metabolism, gene expression, and cellular morphology. In our model organism, Caulobacter crescentus, adaptation to phosphate limitation includes the dramatic elongation of its polar stalk appendage. Recent work from our lab has shown that stalk elongation and adaptation to phosphate starvation involves changes in membrane composition, peptidoglycan organization, and sugar metabolism. Importantly, our findings have implications for other bacterial species related to pathogenesis and cell growth.
Thomas Muir: Princeton University
Painting Chromatin with Synthetic Protien Chemistry
Emil Yuzbashyan, Rutgers University
Integrable time-dependent HamiltoniansIn the emerging field of coherent many-body dynamics, we seek to understand the behavior of an isolated quantum many-body system driven far from equilibrium by changing its Hamiltonian in time. In this talk, I will identify a general class of many-body and matrix Hamiltonians for which this problem is exactly solvable. In particular, I will outline a way to make the parameters (e.g., the interaction strength) of certain quantum integrable models time-dependent without breaking their integrability.
Interesting many-body models that emerge from this approach include a superconductor with the interaction strength inversely proportional to time, a Floquet BCS superconductor, and the problem of molecular production in an atomic Fermi gas swept through a Feshbach resonance as well as various models of multi-level Landau-Zener tunneling. I will solve the non-stationary Schrodinger equation exactly for all these models and discuss some interesting physics that emerges at large times.
The heart of crumpling
or how to (in)crease your coreBring your food to eat at 12:00
Bring a tidbit to tell
The story begins at 12:15
William Unruh, University of British Columbia
Experimental Measurement of the Hawking emission (?)Hawking's discovery 45 years ago that black holes, instead of ever growing sinks of energy, emitted radiation and very slowly shrank in size and mass, was one of the most surprising discoveries of physics in the 20th century. Of course physics in an experimental or at least observational science. But small enough black holes to see this effect are rare.
However analogies exist in which one could hope to see this effect, namely flowing fluids where the velocity of flow exceeds the velocity of sound. While
the classical correlate of this has been measured for surface waves in water, recently the quantum effect has also been measured for sound waves in a BEC. I will review the Hawking effect, the measurement in water and these new measurements where one can claim to have seen at least some of the quantum effects of the Hawking process.
Bernhard Breit, Albert-Ludwigs - University Freiburg
Rhodium-Catalyzed Addition of Pronucleophiles to Alkynes and Allenes: An Atom-Efficient Alternative to the Tsuji-Trost Reaction
IME Distinguished Colloquium Series - Rohit KarnikProfessor Rohit Karnik from Massachusetts Institute of Technology will speak as part of the IME Distinguished Colloquium Series.
Event will be followed by a reception from 5 pm to 6 pm at ERC in IME’s 2nd floor lounge/atrium area
Oskar Hallatschek, UC Berkeley
The role of jackpot events in the dynamics of evolutionLuria and Delbrück discovered that mutations that occur early during a growth process lead to exceptionally large mutant clones. These mutational “jackpot” events are thought to dominate the genetic diversity of growing cellular populations, including biofilms, solid tumors and developing embryos. In my talk I show that jackpot events can be generated not only when mutations arise early but also when they occur at favourable locations, which exacerbates their role in adaptation and disease. I will also consider the impact of recurrent jackpot events, which lead to a bias favoring alleles that happen to be present in the majority of the population. I argue that this peculiar rich-get-richer phenomenon is a general feature of evolution driven by rare events.
Zeger Hens, The Department of Inorganic & Physical Chemistry, Ghent University
Stimulated Emission by Colloidal Quantum DotsReducing the size of materials down to a few nanometer is a powerful approach to control material properties by design. A case in point are semiconductors, where size quantization leads to a size- and shape-dependent band gap once crystal dimensions become comparable or smaller than the exciton Bohr radius; an observation first made almost 40 years ago.
This talk explores the opportunities size reduction brings for creating new optical gain materials. Using free carrier gain in bulk semiconductors as a reference, we discuss 4 different model systems, each exemplifying a different mechanism to attain net stimulated emission.
First, we focus on large perovskite nanocrystals. This example helps introducing the experimental methods we use to characterize gain materials and shows that weakly confined semiconductors have gain characteristics highly similar to the corresponding bulk material. Next, we highlight the impact of size quantization using stimulated emission by CdSe/CdS quantum dots as a second example, which is introduced as a unique model system of band-edge gain by quantum dots. Interestingly, we show that tweaking the core and shell dimensions provides unique possibilities to tune the optical gain characteristics of these materials.
Building on the conditions that yield the lowest gain thresholds in CdSe/CdS quantum dots, we discuss two possibilities to overcome intrinsic limitations of band-edge gain. First, we turn to two-dimensional colloidal nanoplatelets, were we show that stimulated emission through excitonic molecules leads to a combination of low gain thresholds and high gain coefficients. Finally, we propose transitions involving localized band-gap states, exemplified by HgTe quantum dots, as a way to achieve nearly thresholdless gain by colloidal semiconductor nanocrystals. We conclude this presentation by a short outlook on the prospects and challenges on using colloidal quantum dots as a gain material for microlasers. Host(s): Philippe Guyot-Sionnest, 2-7461; Emailemail@example.com & Dmitri Talapin, 4-2607; Email - firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or via email at email@example.com.
Monika Scholz, PhD, Princeton
Reading the mind of the worm: Brain-wide neural dynamics predict behavior in C. elegansHow does a nervous system control animal behavior? While models of behavior and neural computation exist, investigating the connection experimentally is challenging in even the simplest organisms. It is only recently that tools have become available to image the behavior and neural dynamics simultaneously in the roundworm C. elegans. Its small nervous system with only 302 neurons and stereotyped behaviors allow us to probe how well simple models perform in predicting behavior from neural dynamics alone. We use a suite of microscopy tools and a calcium-sensitive fluorescent protein to image the activity of a large number of neurons in the animals brain during locomotion. Using a linear model, we predict forward and backward velocity as well as turns and turn direction from neural activity. Using our model and the animals neural activity, we can predict the worms posture for up to 10 seconds. I will discuss the implications for understanding how neural networks encode information and how this information could be used in coordinating complex motor tasks.
Richa Batra, Creative Machines Lab, Columbia University
Particle Robotics: Statistical Mechanics of Loosely Coupled Robotic ComponentsTraditional robots typically consist of highly-engineered modules, each performing specialized roles to complete
complex tasks. While these robots are accomplishing functions of increasing complexity with greater precision,
they frequently struggle when presented with novel environments, or the failure of a single component. This talk
will explore robotic systems inspired by biology and nature, in which adaptable and resilient behaviors are
achieved by combining and coordinating relatively simple components. Like atoms forming crystals, cells
contracting muscle tissue, or ants foraging for food, complexity can arise from relatively simpleparts.
The robotic system presented, called particle robotics, exploit statistical mechanics of loosely coupled components. This
talk will mainly focus on a particle robot where each component, or particle, is only capable of uniform volumetric oscillations.
The oscillations of the individual particles can be phase-modulated by a global signal. Despite the amorphous
configurations and lack of direct control, we find that we are able to coordinate the overall behavior of the robot. We
demonstrate the scalability and resilience of such robots, both to noisy components and to component failure. In addition,
particle robots comprising components that exhibit different individual behaviors will be presented. The particle robotics
paradigm presented here suggests that large-scale, amorphous robotic systems can exhibit deterministic behavior even
when composed of simple stochastic component.
Floyd Romesberg, The Scripps Research Institute
A Semi-Synthetic Organism that Stores and Retrieves Increased Genetic Information
Zhihao Zhuang, University of Delaware
Chemical Approaches for Investigating Protein DeubiquitinationThe human ubiquitin proteasome system is involved in many cellular processes, including protein quality control, epigenetic regulation, DNA damage repair and tolerance. Many cellular events are regulated through reversible protein ubiquitination. Deubiquitinases (DUBs) as an important class of enzymes in the ubiquitin proteasome system have been associated with various human diseases including cancer, neurological disorders, and viral infection. DUBs are emerging as promising targets for pharmacological intervention and major efforts targeting DUBs for drug discovery are underway. I will discuss the development of a series of novel DUB probes for elucidating the ubiquitin chain linkage and target protein specificity of DUBs. We also developed cell-permeable DUB probes that allow profiling of DUB activities in intact cells. Using the newly developed probes and chemical proteomics approaches, exciting new findings on the DUB specificity and catalysis were obtained. Our efforts led to much needed tools and approaches for understanding the complex biology of protein ubiquitination and will drive the drug discovery efforts targeting the many DUBs in humans.
Luca Grandi, University of Chicago
Christof Sparr, University of Basel
Cataltic Cascade Reactions Inspired by Polyketide Biosynthesis
Semyon Klevtsov, University of Cologne
Geometric responses of Quantum Hall statesOne way to understand the Quantum Hall effect is to consider QH wave functions on Riemann surfaces. Electromagnetic and gravitational responses correspond to varying metric and magnetic field and
quantized coefficients are encoded in Chern classes on associated parameter (moduli) spaces. We report on our recent work and discuss various questions arising in this approach.
Greg Bewley, Cornell University
The structure of turbulence and of granular bedsMy work centers on turbulence, both its intrinsic properties and its role in various environmental settings. Over a bed of sand, it lifts and transports the grains. Left to itself, the turbulence slowly dissipates and disappears. In the first part of my talk, I will introduce experiments motivated by the question of how quickly turbulence consumes kinetic energy. Surprisingly we do not generally know how to predict the consumption rate, though the process underlies general turbulence phenomena and modeling. What we found is that the rate is invariant with respect to changes in the intensity of the turbulence, so long as the flow is slow relative to the speed of sound. I will introduce a new experiment in which we observe how the picture changes when the flow is no longer so slow. In the second part of my talk, I describe an experiment motivated by the question of how turbulence deforms granular beds. The experiments reveal a new mechanism that produces bedforms, a mechanism associated with fluctuating pressure gradients generated in a fluid-saturated particle bed by a plate oscillating in the water above it.
David Weiss, The Department of Physics, Penn State University
Quantum Computing with Neutral AtomsI will present our approach to making a quantum computer
using atoms in a 3D optical lattice. I will focus on our recent
demonstration of perfect lattice filling in 4x4x3 and 5x5x2 arrays,
which involved an experimental realization of Maxwell's demon. I will
also describe how we have accomplished high fidelity single qubit gates
(0.997) and high fidelity lossless state detection (0.9994).ost: Cheng Chin, 2-7192 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Nan Hao, PhD. UCSD
Systems biology of single-cell aging
Brian M. Stoltz, California Institute of Technology
Complex Natural Products as a Driving Force for Discovery in Organic Chemistry
Nicholas Meanwell, Bristol-Myers Squibb
Inhibitors of HIV-1 Maturation
Ronak Soni, Stanford University
Scalar Asymptotic Charges and Dual Large Gauge TransformationsIn recent years soft factorization theorems in scattering amplitudes have been reinterpreted as conservation laws of asymptotic charges. In gauge, gravity, and higher spin theories the asymptotic charges can be understood as canonical generators of large gauge symmetries. Such a symmetry interpretation has been so far missing for scalar soft theorems. We remedy this situation by treating the massless scalar field in terms of a dual two-form gauge field. We show that the asymptotic charges associated to the scalar soft theorem can be understood as generators of large gauge transformations of the dual two-form field. The dual picture introduces two new puzzles: the charges have very unexpected Poisson brackets with the fields, and the monopole term does not always have a dual gauge transformation interpretation. We find analogs of these two properties in the Kramers-Wannier duality on a finite lattice, indicating that the free scalar theory has new edge modes at infinity that canonically commute with all the bulk degrees of freedom.
Arvind Murugan, University of Chicago
Materials that learn from examplesWe usually design materials to target desired behaviors defined in a top-down manner. Learning theory offers an alternative where desired behaviors are defined by a list of examples. In learning, a material changes as it physically experiences such examples. We then test the material to see if it has the “correct” response to novel conditions never seen before (‘generalization’). Can real materials ‘learn’ from their history in this manner? We study the physical requirements for such information processing in terms of disorder, non-equilibrium driving and non-linearities using theory and experiments in disordered sheets, elastic networks, and molecular self-assembly.
Muhittin Mungan, University of Bonn
Cyclic Annealing, Random Maps & MemoriesDisordered magnets, martensitic mixed crystals, and glassy solids can be irreversibly deformed by subjecting them to external deformation. The
deformation produces a smooth, reversible response punctuated by abrupt
relaxation ``glitches". Under appropriate repeated forward and reverse
deformation producing multiple glitches, a strict repetition of a single
sequence of microscopic configurations often emerges. It turns out that
the athermal evolution of the system configuration from glitch to glitch
can be described as a pair of maps that map states into one-another. One
map U controls forward deformation; a second map D controls reverse
deformation. The disorder of the system renders these maps random. We
will first consider iterations of a given sequence of forward and
reverse maps. Such maps necessarily produces a convergence to a fixed
cyclic repetition of states covering multiple glitches. Using numerical
sampling, we characterize the convergence properties of four types of
random maps implementing successive physical restrictions. These maps
show only the most qualitative resemblance to annealing simulations.
However, they suggest further properties needed for a realistic mapping
scheme. Formulating the irreversible part of the dynamics in terms of a
pair of maps (U,D) allows one to understand phenomena such as
return-point memory entirely in terms of the properties of these maps.
After briefly reviewing these types of features, we discuss how such a
formulation can help us in understanding the formation of memory in
matter. This is ongoing joint work with T. Witten, M.Terzi, I. Regev,
K. Dahmen and S. Sastry. Host: Thomas Witten, 2-0947 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
IME Distinguished Colloquium Series - Alberto SalleoProfessor Alberto Salleo from Stanford University will speak as part of the IME Distinguished Colloquium Series.
Event will be followed by a reception from 5 pm to 6 pm at ERC in IME’s 2nd floor lounge/atrium area
Hana El-Samad, University of California, San Francisco
Biological control: The versatile ways in which cells use feedback loopsIn 1939, Walter Cannon wrote in his book The Wisdom of the Body: “The living being is an agency of such sort that each disturbing influence induces by itself the calling forth of compensatory activity to neutralize or repair the disturbances”. Since this remarkable statement that postulates the use of feedback control to support life, we have come to appreciate that the use of feedback loops is ubiquitous at every level of biological organization, from the gene to the ecosystem. In this talk, we introduce a technology to study feedback operation in endogenous biological systems. We also discuss some recent progress in building feedback control systems with biological molecules that can modulate the operation of cellular pathways
Monica Allen, The Department of Physics, University of California-San Diego
Visualization of Topological States of Matter Using Microwave Impedance MicroscopyA main thrust of condensed matter physics concerns the discovery of new electronic states in emerging materials. One example is the rapidly expanding class of topological materials, which are posited to enable realization of non-abelian particles and topological quantum computing. In this talk, I will discuss how exotic phenomena can arise from the interplay of ferromagnetism and topology. We employ microwave impedance microscopy (MIM), which characterizes the local complex conductivity of a material, to directly image chiral edge modes and phase transitions in a magnetic topological insulator. Finally, I will outline how MIM could be used in the future to visualize and manipulate Majorana modes, an emerging platform for quantum information processing.Host: David Schuster at 2-7191 or David.Schuster@uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org
Raymond Kapral, University of Toronto
Molecular Machines and Synthetic Motors: Active Motion on NanoscalesMolecular machines or motors in the cell operate under nonequilibrium
conditions and extract chemical energy from their surroundings to perform a
variety of transport and other biological functions. Synthetic nanomotors
without moving parts also operate under nonequilibrium conditions using
chemical energy to move in solution, and can transport cargo and perform
other functions. The operations of these tiny motors differ markedly from
their macroscopic counterparts. The mechanisms that lead to the directed
motion of chemically-powered motors, as well as some of their potential
applications, will be discussed. Since both molecular machines and synthetic
motors must respect the basic laws of dynamics while functioning under
nonequilibrium conditions, there are similarities between how these very
different nanomotors function. Systems containing many synthetic motors can
display collective behavior leading to active self-assembly, swarming and
other collective states that differ from those in systems at equilibrium, and
these new structures will also be described.
Guanyu Zhu, IBM T.J. Watson Research Center
Universal logical gate sets with constant-depth circuits for topological and hyperbolic quantum codesA fundamental question in the theory of quantum computation is to understand the ultimate space-time resource costs for performing a universal set of logical quantum gates to arbitrary precision. To date, common approaches for implementing a universal logical gate set, such as schemes utilizing magic state distillation, require a substantial space-time overhead.
In this work, we show that braids and Dehn twists, which generate the mapping class group of a generic high genus surface and correspond to logical gates on encoded qubits in arbitrary topological codes, can be performed through a constant depth circuit acting on the physical qubits. In particular, the circuit depth is independent of code distance d and system size. The constant depth circuit is composed of a local quantum circuit, which implements a local geometry deformation, and a permutation of qubits, separated by a distance of O(d). The permutation can be implemented by moving qubits or as a constant depth circuit using long-range SWAP operations (with a range set by d) on immobile qubits. Our results apply to both the abelian stabilizer codes (such as the surface code), and also to non-abelian Turaev-Viro codes.
When applied to anyon braiding or Dehn twists in the Fibonacci Turaev-Viro code based on the Levin-Wen model, our results demonstrate that a universal logical gate set can be implemented on encoded qubits in O(1) time through a constant depth unitary quantum circuit, and without increasing the asymptotic scaling of the space overhead. Our results for Dehn twists can be extended to the context of hyperbolic Turaev-Viro codes as well, which have constant space overhead (constant rate encoding). This implies the possibility of achieving a space-time overhead of O(d/log d), which is optimal to date for generic logical circuits.
These discoveries can greatly reduce the space and time overhead of fault-tolerant quantum computation, and in particular, significantly reduce the number of physical qubits per logical qubits. From a conceptual perspective, our results reveal a deep connection between the geometry of quantum many-body states and the complexity of quantum circuits. Our scheme also demonstrates at a fundamental level the significant advantage of long-range connectivity in quantum architectures for implementing fault-tolerant quantum computation.
Ramón Latorre, PhD, University of Valparaíso, Chile
Calcium- and voltage-activated (BK) channel: gating & modulation by auxiliary subunits
Thomas Snaddon, Indiana University
Enantioselective Chemical Synthesis Methods via Cooperative Catalysis
Maciej Koch-Janusz, ETH, Zurich
Information Theory, Machine Learning and the Renormalization GroupPhysical systems differing in their microscopic details often display strikingly similar behaviour when probed at macroscopic scales. Those universal properties, largely determining their physical characteristics, are revealed by the renormalization group (RG) procedure, which systematically retains ‘slow’ degrees of freedom and integrates out the rest. We demonstrate a machine-learning algorithmbased on a model-independent, information-theoretic characterization of real-space RG, capable of identifying the relevant degrees of freedom and executing RG steps iteratively without any prior knowledge about the system. We apply it to classical statistical physics problems in 1 and 2D: we demonstrate RG flow and extract critical exponents. We also prove results about optimality of the procedure.
Jennifer Dionne, PhD, Stanford University
Inside Out: Visualizing chemical transformations & light-matter interactions with nanometer-scale resolutionIn Pixar’s Inside Out, Joy proclaims, “Do you ever look at someone and wonder, what’s going on inside?” My group asks the same question about materials whose function plays a critical role in energy and biologically-relevant processes. This presentation will describe new techniques that enable in situ visualization of chemical transformations and light-matter interactions with nanometer-scale resolution. We focus in particular on i) ion-induced phase transitions; ii) optical forces on enantiomers; and iii) nanomechanical forces using unique electron, atomic, and optical microscopies. First, we explore nanomaterial phase transitions induced by solute intercalation, to understand and improve materials for energy and information storage applications. As a model system, we investigate hydrogen intercalation in palladium nanocrystals. Using environmental electron microscopy and spectroscopy, we monitor this reaction with sub-2-nm spatial resolution and millisecond time resolution. Particles of different sizes, shapes, and crystallinities exhibit distinct thermodynamic and kinetic properties, highlighting several important design principles for next-generation storage devices. Then, we investigate optical tweezers that enable selective optical trapping of nanoscale enantiomers, with the ultimate goal of improving pharmaceutical and agrochemical efficacy. These tweezers are based on plasmonic apertures that, when illuminated with circularly polarized light, result in distinct forces on enantiomers. In particular, one enantiomer is repelled from the tweezer while the other is attracted. Using atomic force microcopy, we map such chiral optical forces with pico-Newton force sensitivity and 2 nm lateral spatial resolution, showing distinct force distributions in all three dimensions for each enantiomer. Finally, we present new nanomaterials for efficient and force-sensitive upconversion. These optical force probes exhibit reversible changes in their emitted color with applied nano- to micro-Newton forces. We show how these nanoparticles provide a platform for understanding intra-cellular mechanical signaling in vivo, using C. elegans as a model organism.
William A. Tisdale, MIT
Excitons, Entropy, and Nonequilibrium Transport in Semiconductor NanomaterialsStructure, surface chemistry, and energetic disorder can dramatically affect excited state dynamics in low-dimensional systems. Using a combination of ultrafast laser spectroscopy, time-resolved optical microscopy, and kinetic modeling, I will show how these effects manifest in assemblies of colloidal quantum dots (QD) and atomically thin 2D semiconductors, which are promising components of next-generation photovoltaic and lighting technologies. In particular, I will demonstrate the counterintuitive role of entropy in the nonequilibrium population dynamics of excitons and charge carriers in nanoscale systems.
Xiangfeng Duan, UCLA
Van der Waals Integration Before and Beyong 2D MaterialsThe heterogeneous integration of dissimilar materials is a long pursuit of material science community and has defined the material foundation for modern electronics and optoelectronics. The current material integration strategy such as chemical epitaxial growth usually involves strong chemical bonds and is typically limited to materials with strict structure match and processing compatibility. Van der Waals (vdW) integration, in which pre-fabricated building blocks are physically assembled together through weak vdW interactions, offers an alternative bond-free material strategy without lattice and processing limitations, as exemplified by 2D vdW heterostructures. In this talk I will discuss the development, challenges and opportunities of this emerging approach, generalizing it for flexible integration of diverse material systems beyond 2D, and prospect its potential for creating artificial heterostructures or superlattices beyond the reach of existing materials.
Frank Graziani, Lawrence Livermore National Laboratory
High Energy Density Physics and Modeling of Extreme States of MatterHigh energy density physics (HEDP) is the study of matter at extreme conditions where energy densities are in excess of 10^12 ergs/cc or equivalently, pressures are in excess of 1 Mbar. HEDP spans a wide range of phenomena, from the deep interiors of the giant planets to the hot plasmas typical of stellar interiors. Matter in the HEDP regime can involve some combination of the following phenomena, collective effects, electron degeneracy, radiation, atomic kinetics, strong particle-particle correlations, non-equilibrium and hybrid quantum-classical behavior. In this overview, I will explain why HEDP is an intellectually challenging and exciting research area that impacts basic science, energy, and national security. I discuss the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) which uses the concept of inertial confinement fusion (ICF) to create conditions where pressures far exceed 1 Mbar. The remainder of the talk is devoted to an important component of executing experiments at NIF or any other HEDP facility-simulation. I discuss the spectrum of computational approaches HEDP scientists use to model their experiments. I discuss the strengths and weaknesses of the various computational approaches and briefly touch on two recent advances that may hold promise to enhancing the current weaknesses. The talk ends with a discussion of the High Energy Density Sciences Center, which is an outreach organization at LLNL that is building a HEDP community through interactions of LLNL scientists with academic collaborators.
John Briggs PhD, LMB-MRC
How to assemble a retrovirus: the view from cryo-electron microscopy
Richard Schrock, MIT
Recent Advances in Olefin Metathesis with Molybdenum CatalystsMolybdenum imido catalysts that are asymmetric at the metal, Mo(NR)(CHR')(X)(Y), where X and Y are different monoanionic ligands (e.g., a sterically demanding terphenoxide and a chloride or pyrrolide), have led to dramatic improvements in olefin metathesis chemistry in the last two years. Advances include the synthesis of monoaryloxide (X) chloride (Y) imido catalysts, kinetically E-selective macrocyclic ring-closing metathesis catalysts, stereoselective (Z or E) olefin metathesis reactions that use electron-poor olefins (ClCH=CHCl, CF3CH=CHCF3, BrCH=CHF, NCCH=CHCN), and ROMP reactions that yield cis,syndiotactic-A-alt-B copolymers from enantiomerically pure monomers. Mo=CHX complexes where X = Cl, Br, CF3, phosphonium, or CN have now been structurally characterized. The latest results concern the synthesis of the first catalytically active molybdenum oxo alkylidene complexes through addition of water to alkylidyne complexes. Other findings will be discussed as time permits.
Jennifer Lin, IAS
Entanglement in gauge theories and gravityIn this talk I’ll review how to define entanglement entropy in lattice gauge theories, and explain why an analogy between EE in emergent gauge theories and in AdS/CFT suggests that the entropy of a black hole is related to a measure on the gauge group in the bulk. I’ll then provide an explicit example of this in Jackiw-Teitelboim gravity.
Jennifer Roizen, Duke University
Alcohol and Amine Derivatives Guide Position-Selective C–H Functionalization ReactionsFree radical reactions represent an important and versatile class of chemical transformations. Nitrogen-centered radical applications remain underexplored due to the lack of convenient methods for their generation. Recent advances have improved access to nitrogen-centered radicals through photoredox-mediated oxidation of two such directing groups: amides and sulfonamides. Guided by this approach, we hypothesized that alcohols, masked as sulfamate esters, and amines, masked as sulfamides, could engage in photoredox-mediated oxidation to furnish nitrogen-centered radicals that could guide C–H functionalization reactions.
Moreover, our directed technology has been inspired by one of the most reliable and powerful known reactions to guide C–H functionalization reactions: the Hofmann–Löffler–Freytag (HLF) reaction, which uses amines or amides as directing groups. Like many of the most robust radical-mediated technologies to direct the activation of tertiary and secondary centers, the HLF reaction is guided through 1,5-hydrogen-atom transfer (HAT) processes, which proceeds through a kinetically-favorable six-membered ring transition state. By contrast, few reports describe 1,6-HAT with a traceless linker, such as an alcohol masked as a sulfamate ester or an amine masked as a sulfamide, and there are no general strategies to enable masked alcohols or amines to direct functionalization of aliphatic -C(sp3)–H centers. This talk will outline this novel strategy to harness alcohols and amines to replace C–H bonds at -C(sp3)–H centers, which are not generally accessible to directed functionalization. We will demonstrate that C–H abstraction can be robustly coupled with varied functionalization reactions. This talk will highlight the first generalizable synthetic strategy to functionalize -C(sp3)–H bonds based on masked alcohols or amines, to push the boundaries of organic chemistry at a fundamental level and benefits drug discovery.
Jane Wang, Cornell University
Insect Flight: from Newton’s law to Neurons
Insects are the first evolved to fly, and to fly is not to fall. How does an insect fly, why does it fly so well, and how can we infer its ‘thoughts’ from its flight dynamics? We have been seeking mechanistic explanations of the complex movement of insect flight. Starting from the Navier-Stokes equations governing the unsteady aerodynamics of flapping flight, we worked to build a theoretical framework for computing flight. This has led to new interpretations and predictions of the functions of an insect’s internal machinery that orchestrate its flight. I will discuss our recent computational and experimental studies of the balancing act of insets: how a dragonfly recovers from falling upside-down and how a fly balances in air. In each case, the physics of flight informs us about the neural feedback circuitries underlying their fast reflexes.
Thomas V. Magee, Senior Research Director at Pfizer
Discovery of Ketohexokinase (KHK) Inhibitor PF-06835919 for the Treatment of Fatty Liver and Metabolic Disease: From Fragments to Clinical Candidate
Amy Weeks, University of California, San Francisco
New Chemoenzymatic Tools for Dissecting Proteolytic Signaling PathwaysProteolysis is a key post-translational modification that regulates a wide array of biological processes in human health and disease, including viral infection, cancer progression, organismal development, and neurodegeneration. However, few tools are available to identify proteolysis sites with single amino acid resolution. We have developed next-generation enzymatic tools that enable unbiased capture and sequencing of neo-N termini generated by proteolytic cleavage. These probes are based on subtiligase, a rationally designed variant of the serine protease subtilisin, which catalyzes a ligation reaction between a peptide ester and the N-terminal amine of a peptide or protein. We characterized ligation efficiency for >25,000 enzyme-substrate pairs, leading to the identification of a panel of subtiligase variants that enhance sequence coverage of the cellular N terminome. We have also developed a strategy for spatially-restricted N-terminal tagging that enables global analysis of proteolytic cleavage events at the plasma membrane. Using this technique, we have sequenced proteolytic cleavage sites in >500 human membrane proteins. By combining plasma membrane-targeted subtiligase with pharmacological protease inhibitor treatment, we have begun to define the proteases responsible for specific cleavage events. In combination with its ease of use, the high specificity and resolution of live-cell, subtiligase-catalyzed proteolysis mapping provide a powerful tool for dissecting proteolytic signaling pathways.
Xiang Cheng, University of Minnesota
From Flocking Birds to Swarming Bacteria: A Study of the Dynamics of Active FluidsActive fluids are a novel class of non-equilibrium complex fluids with examples across a wide range of biological and physical systems such as flocking animals, swarming microorganisms, vibrated granular rods, and suspensions of synthetic colloidal swimmers. Different from familiar non-equilibrium systems where free energy is injected from boundaries, an active fluid is a dispersion of large numbers of self-propelled units, which convert the ambient/internal free energy and maintain non-equilibrium steady states at microscopic scales. Due to this distinct feature, active fluids exhibit fascinating and unusual behaviors unseen in conventional complex fluids. Here, combining high-speed confocal microscopy, holographic imaging, rheological measurements and biochemical engineering, we experimentally investigate the dynamics of active fluids. In particular, we use E. coli suspensions as our model system and illustrate three unique properties of active fluids, i.e., (i) abnormal rheology, (ii) enhanced diffusion of passive tracers and (iii) emergence of collective swarming. Using theoretical tools of fluid mechanics and statistical mechanics, we develop a quantitative understanding of these interesting behaviors. Our study illustrates the general organizing principles of active fluids that can be exploited for designing “smart” fluids with controllable fluid properties. Our results also shed new light on fundamental transport processes in microbiological systems.
Arjun Yodh, The Department of Physics & Astronomy
Soft Matter Potpourri
Istvan Racz, University of Warsaw
On the use of evolutionary methods in spaces of Euclidean signatureTwo examples of physical interest will be presented. Both, contrary to the folklore, demonstrate that evolutionary methods may also play significant role in spaces of Euclidean signature. First, the propagation of the constraints is considered. It is shown that once a clear separation of the `evolutionary’ and constraint equations is done, the subsidiary equations satisfied by the constraint expressions form a first order symmetric hyperbolic system regardless whether the ambient Einsteinian space is of Lorentzian or Euclidean signature. Second, the constraints of Einstein's theory of gravity are considered. Since the seminal observations of Lichnerowicz and York these equations are usually referred to as a semilinear elliptic system. It will be shown that–according to the choice of the dependent variables–the constraints may have different characters. In particular, they may take the form of either a parabolic-hyperbolic or a strongly hyperbolic system. Some of the recent developments related to these alternative choices will also be discussed.
Jessica McIver, Caltech
Gravitational wave astrophysics: a new era of discoveryFuture gravitational wave observations will provide exciting new insight into key open questions in astrophysics, including the distribution of stellar remnants in the Universe, the evolution of compact binary systems, galaxy formation, the expansion of the Universe, and the explosion mechanism of core-collapse supernovae. I will highlight major outstanding challenges in gravitational wave astrophysics, including extracting transient signals from the noisy data of present and future detectors. I will present new data science techniques to address these challenges and enable future multi-messenger discoveries. I will discuss how the rapidly developing field of gravitational wave astrophysics will shape our understanding of the Universe, including the growing global interferometer network, the next generation of terrestrial interferometers, and the Laser Interferometer Space Antenna (LISA).
Daniel Jafferis, Harvard University
Stringy ER=EPRI will discuss how the correspondence between an entangled state of black holes and the ER wormhole spacetime can be understood as a string duality. In a pure NS background, it is a worldsheet duality involving a condensate of entangled strings. A main ingredient is the Lorentzian prescription for euclidean time winding vertex operators in angular quantization.
Marc Kamionkowski, Johns Hopkins University
Heretical hypotheses in the hunt for dark matterWe have known for a reasonable fraction of a century that most of the matter in the Universe is dark, and for several decades that it cannot be baryonic. The nature of this dark matter has, however, been elusive. The prevailing weakly-interacting massive particle (WIMP) hypothesis that have long been theorists preferred guess faces considerable pressure from an array of null searches, and this has led theorists to consider previously unpalatable alternatives. I will discuss the rise, and possible fall, of an idea that connected LIGO’s discovery of black-hole binaries to dark matter. I will also discuss recent ideas (motivated in part by an intriguing recent experimental result) that involve particles with enhanced couplings to ordinary matter.
Greg Voth, Wesleyan University
A new view of the dynamics of turbulence from measurements of rotations of particles with complex shapesNon-spherical particles in turbulent flows are important in a wide range of problems including ice crystals in clouds, fibers in paper-making, marine plankton, and additives for turbulent drag reduction. We have developed experimental methods for precise tracking of the position and orientation of non-spherical particles in intense 3D turbulence. Using 3D printed particles, we can fabricate a wide range of shapes and explore how particle orientation and rotation are affected by particle shape. We find particles are strongly aligned by the turbulence. A simple picture in which particles are aligned by the fluid stretching they experience explains many of the key observations about how particles align and rotate. This same picture sheds new light on some old problems about how vorticity aligns with the strain rate tensor in turbulent flows. It has also allowed us to create a fascinating particle shape which we call a chiral dipole that shows a preferential rotation direction in isotropic turbulent flow.
Kenneth Schweizer, The Department of Chemistry, University of Illinois at Urbana - Champaign
Activated Dynamics in Glass Forming Colloidal, Molecular and Polymeric Liquids: From Structural Relaxation to Functional MaterialsUnderstanding the spectacular slowing down of relaxation and mass transport in glass-forming liquids over 14 or more decades in time remains a grand scientific challenge. Moreover, many advanced materials employ viscous liquids, gels or amorphous solids in applications such as separation membranes, barrier coatings, ion-conductors and functional nanocomposites. I will present an overview of our work the past 5 years on developing a predictive, microscopic, force-based theory for activated relaxation that spans the Arrhenius, dynamic crossover and deeply supercooled regimes of colloidal, molecular and polymeric systems. The theory is based on density fluctuations as the slow variable and the trajectory-level concept of a dynamic free energy that controls intermittent motion. The irreversible re-arrangement event is of a mixed local-nonlocal character involving large amplitude hopping on the cage scale coupled to longer range collective elastic distortion of the surrounding liquid. Connections between thermodynamics, structure, dynamic elasticity and slow relaxation emerge naturally. Chemical complexity is treated based on a physically motivated coarse-graining idea that identifies a small number of key molecular parameters. Quantitative, no-fit-parameter comparisons with experiment will be presented. Generalization to the materials science problem of penetrant diffusion (gas, aromatic molecules) in polymer liquids and glasses, inspired by ideas from interstitial and polaron transport in solids, will also be discussed. Ongoing related theoretical extensions include quiescent and nonequilibrium relaxation and mechanics in attractive glass and gel-forming polymers, colloids and hybrid nanocomposite systems, large dynamical gradients in thin films, emergent anisotropic entanglement constraints and rheology of (bio)polymers, and active matter. Host: Suri Vaikuntanathan at 2-7256 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Ibrahim Cisse, Physics, MIT,
Super-resolution imaging of transcription in live mammalian cells
Kadanoff seminar: Zohar Nussinov, Washington University in St. Louis
Thermalization bounds, long range correlations, and a universal collapse of the viscosities of supercooled liquidsWe will derive bounds on the equilibration times in open and closed systems. For open systems, we will find that thermalization times cannot, typically, be shorter than Planck's constant divided by the temperature; a more general (and accurate) relation involving the heat capacities will be explained. For closed systems, the inequalities that we will obtain suggest that non-adiabatically driven systems may display long range correlations. We will explain how these long range correlations appear in certain soluble models in general spatial dimensions and relate these correlations to the geometry of state manifolds. We will describe how experimental measurements of equilibrated systems may be used to infer the properties of eigenstates of many body Hamiltonians. We will then piece these results together to predict the viscosity and relaxation times of supercooled liquids and glasses. These predictions will be compared to the viscosities and dielectric relaxation times of glass formers of all known types. The comparison shows that the viscosities/relaxation times of all known supercooled liquids collapse onto a universal curve with only one (nearly uniform) liquid dependent parameter over 16 decades. The collapsed universal curve is that predicted by the theory.
Jim Sethna, Cornell University
Sloppy models, differential geometry, and the space of model predictions
Models of systems biology, climate change, ecology, complex instruments, and macroeconomics have parameters that are hard or impossible to measure directly. If we fit these unknown parameters, fiddling with them until they agree with past experiments, how much can we trust their predictions? We have found that predictions can be made despite huge uncertainties in the parameters – many parameter combinations are mostly unimportant to the collective behavior. We will use ideas and methods from differential geometry and approximation theory to explain sloppiness as a ‘hyper-ribbon’ structure of the manifold of possible model predictions. We show that physics theories are also sloppy – that sloppiness may be the underlying reason why the world is comprehensible. We will present new methods for visualizing this model manifold for probabilistic systems – such as the space of possible universes as measured by the cosmic microwave background radiation.
Andrei Starinets, University of Oxford
Analytic structure of hydrodynamic expansions at large finite couplingTransport properties of liquids and gases in the regime of weak
coupling can be determined from relevant kinetic equations for
particles or quasiparticles, with transport coefficients typically
proportional to the minimal eigenvalue of the linearized kinetic
operator. At strong coupling, the same physical quantities can in
principle be found from dual gravity, where quasinormal spectra enter
as eigenvalues of the linearized Einstein's equations. We discuss the
problem of interpolating between strong and weak coupling using the
results from higher derivative gravity. We also consider the analytic
structure of all-order hydrodynamic expansions arising from the
associated complex analytic spectral curves and discuss how it is
related to the phenomenon of level crossing in quasinormal spectra of
dual black branes.
Jörn Dunkel, MIT
Wrinkles and spaghettiBuckling and fracture are ubiquitous phenomena that, despite having been studied for centuries, still pose many interesting conceptual and practical challenges. In this talk, I will summarize recent experimental and theoretical work that aims to understand the role of curvature and torsion in wrinkling and fragmentation processes. First, we will show how changes in curvature can induce phase transitions  and topological defects  in the wrinkling patterns on curved elastic surfaces. In the second part, we will revisit an observation by Feynman who noted that spaghetti appears to fragment into at least three (but hardly ever two) pieces when placed under large bending stresses. Using a combination of experiments, simulations and analytical scaling arguments, we will demonstrate how twist can be used to control binary fracture of brittle elastic rods .
 Nature Materials 14, 337 (2015)  PRL 116: 104301 (2016)  PNAS 115: 8665 (2018)
Wei Xiong, The Department of Chemistry, University California-San Diego
Molecular Polaritons – Janus Particles of Photon and MoleculesMolecular vibrational polaritons, half-light, half-matter hybrid quasiparticles, are studied using ultrafast, coherent 2D IR spectroscopy1. Molecular vibrational-polaritons are anticipated to produce new opportunities in the photonic and molecular phenomena. Many of these developments hinge on fundamental understanding of physical properties of molecular vibrational polaritons. Using 2D IR spectroscopy to study vibrational-polaritons, we obtained results that challenge and advance both polariton and spectroscopy fields. These results invoke new developments in theory for the spectroscopy, discover observation of new nonlinear optical effects and unexpected responses from hidden dark states. We expect these results to have significant implications in novel infrared photonic devices, lasing, molecular quantum simulation, as well as new chemistry by tailoring potential energy landscapes.
1.Xiang, B. et al. Two-dimensional infrared spectroscopy of vibrational polaritons. Proc. Natl. Acad. Sci. 115, 4845–4850 (2018) Host: Prof. Andre Tokmakoff, 2-7696 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email to firstname.lastname@example.org.
Adam Willard, MIT
The Statistical Mechanics of Hydrogen Bonding at the Liquid Water InterfaceThe dielectric properties of liquid water are determined in large part by the orientational fluctuations of dipolar water molecules. Near a liquid water-vapor interface these orientational fluctuations are constrained and anisotropic, leading to dielectric properties that differ significantly from their bulk values. These differences are fundamental to interface-selective chemical and physical processes but they are generally difficult to predict. We attempt to understand these differences by considering the statistical mechanics of hydrogen bonding at the liquid water interface. Using a mean-field model, we demonstrate that three-body hydrogen bond defects that are stabilized at the interface contribute significantly to determine the interfacial dielectric properties. We utilize this mean field model to study the properties of hydrophilic interfaces and then adapt this perspective to the development of an order parameter that can be used to mapping the dynamic hydration properties of proteins.
Dima Abanin, University of Geneva
New quantum many-body states enabled by erodicity breakdownThe experimental advances in synthetic quantum systems, such as ultracold atoms, have enabled researchers to probe quantum thermalization and its breakdown. Thermalization occurs in ergodic systems and “erases” quantum information contained in the initial many-body states. Therefore, to create long-lived quantum states, it is of particular interest to find mechanisms of thermalization breakdown. One way of suppressing thermalization is by introducing strong quenched disorder, which induces many-body localization (MBL) . MBL systems exhibit a new kind of emergent robust integrability and a wealth of novel dynamical phenomena. Surprisingly, MBL systems may also avoid heating under periodic driving, which opens up the possibility of having stable, Floquet-MBL phases with unusual properties. I will discuss one example of such a phase – a two-dimensional Anomalous Floquet Insulator, characterized by fully localized bulk states and chiral, thermalizing edge states .
Further, I will argue that MBL may not be the only way to break ergodicity. I will propose another mechanism, “quantum many-body scarring”, which bears a similarity to the well-known phenomenon of quantum scars in few-body chaos, and leads to a weaker form of ergodicity breaking in a many-body system of Rydberg atoms . Quantum scarring gives rise to a set of non-thermal many-body wave functions immersed in the thermalizing background; when the system is initialized in the physical states which have a high overlap with the non-thermal states, it exhibits many-body revivals and lack of thermalization, which have been observed in a recent experiment .
Cathy Drennan, HHMI / MIT
Shake, Rattle, & Roll: Capturing Snapshots of Metalloproteins in ActionsMetalloproteins, or proteins that utilize metals to perform their functions, are responsible for a wide range of activities such as the conversion of greenhouse gas carbon dioxide into cellular biomass. To carry out their functions, these proteins often need to be flexible and assume different conformational states, with units of the protein swinging back and forth to enable reactants to bind the protein or products to leave. In this talk, the conformational gymnastics involved in ribonucleotide reduction are considered. Ribonucleotide reductases (RNRs) are metalloenzymes that convert ribonucleotides (the building blocks of RNA) to deoxyribonucleotides (the building blocks of DNA). RNRs are targets for cancer chemotherapies and have been proposed to be candidates for antimicrobial therapies. In this talk, I will describe how my lab has employed biophysical methods to interrogate how RNRs shake, rattle, and roll to accomplish their critical cellular function.
Special Seminar (Particle Phenomenology): Rafaello Tito D'Agnolo, IAS
Naturalness in the SkyTwo questions have driven particle physics in the past decades and have a significance that goes beyond the domain of particle physics itself. One surrounds the nature of electroweak symmetry breaking, the other the microscopic origin of dark matter. Both have answers that seem inevitable in their simplicity, but are challenged by experimental results and contain hidden assumptions. I will present new theoretical perspectives on both questions, unveiling unexpected connections with experiment and a clear path to move forward in our understanding. Intriguingly our original expectations might be almost inverted, with dark matter more easily detectable by Earth-based accelerator experiments and electroweak symmetry breaking leaving an imprint in the Cosmic Microwave Background.
Dancing nano-particles in a strobe lightPrelude 12:00
Vidya Madhavan, University of Illinois at Urbana–Champaign
Signatures of Dispersing 1D Majorana Channels in an Iron-based SuperconductorDirac discovered that every fundamental particle must also have an anti-particle which has the opposite charge. When particles and anti-particles meet, they annihilate each other, releasing energy. A Majorana fermion is a special type of fundamental particle which is its own antiparticle. The possible realization of these exotic Majorana fermions as quasiparticle excitations in condensed matter physics has created much excitement. Most recent studies have focused on Majorana bound states which can serve as topological qubits. More generally, akin to elementary particles, Majorana fermions can propagate and display linear dispersion. These excitations have not yet been directly observed, and can also be used for quantum information processing. This talk is focused on our recent work in realizing dispersing Majorana modes. I will describe the conditions under which such states can be realized in condensed matter systems and what their signatures are. Finally, I will describe our scanning tunneling experiments of domain walls in the superconductor FeSe0.45Te0.55, which might potentially be first realization of dispersing Majorana states in 1D.
Particle Phenomenology Seminar: Masha Baryakhtar
Searching for New Physics with Light and Gravitational WavesTheories beyond the Standard Model often include new, light, feebly interacting particles whose discovery requires novel search strategies. The QCD axion elegantly solves the strong-CP problem of the Standard Model; axion-like-particles, dark photons, and other ultralight bosons can also appear, and are natural dark matter candidates. First, I will discuss my experimental proposal based on photonic materials, in which bosonic dark matter can efficiently convert to detectable single photons. A prototype experiment is underway, and current experimental techniques promise to reach significant new dark matter parameter space in the 0.1 − 10 eV range.
Second, I will show how the process of superradiance, combined with gravitational wave measurements, turns black holes into nature's laboratories for new ultralight boson searches. When a bosonic particle's Compton wavelength is comparable to the horizon size of a black hole, superradiance converts energy and angular momentum from the black hole into exponentially growing `hydrogenic' bound states of bosons. I will present constraints on axions and dark photons from black hole spin measurements, and discuss how these systems may source up to thousands of monochromatic gravitational wave signals, enabling LIGO to discover new particles.
Andrej Košmrlj, Princeton University
Phase separation in multicomponent liquid mixturesMulticomponent systems are ubiquitous in nature and industry. While the physics of binary and ternary liquid mixtures is well-understood, the thermodynamic and kinetic properties of N-component mixtures with N>3 have remained relatively unexplored. Inspired by recent examples of intracellular phase separation, we investigate equilibrium phase behavior and morphology of N-component liquid mixtures within the Flory-Huggins theory of regular solutions. In order to determine the number of coexisting phases and their compositions, we developed a new algorithm for constructing complete phase diagrams, based on numerical convexification of the discretized free energy landscape. Together with a Cahn-Hilliard approach for kinetics, we employ this method to study mixtures with N=4 and 5 components. In this talk I will discuss both the coarsening behavior of such systems, as well as the resulting morphologies in 3D. I will also mention how the number of coexisting phases and their compositions can be extracted with Principal Component Analysis (PCA) and K-Means clustering algorithms. Finally, I will discuss how one can reverse engineer the interaction parameters and volume fractions of components in order to achieve a range of desired packing structures, such as nested "Russian dolls" and encapsulated Janus droplets.
Emily Weiss - The Department of Chemistry, Northwestern University
Regio- and Diastereoselective Triplet-Initiated Intermolecular [2+2] Cycloadditions Photocatalyzed by Visible-light-Absorbing Quantum DotsTetrasubstituted cyclobutyl structures are precursors to, or core components of, many important bioactive molecules, including prospective drugs. Light-driven [2+2] cycloaddition is the most direct strategy for construction of these structures. Synthetic applications of [2 + 2] photocycloadditions demand high selectivity, not only for specific coupling products, but also for particular stereo- and regioisomers of those products. Achieving selectivities for (i) a particular regioisomer of the coupled product, (ii) a particular diastereomer of the coupled product, and (iii) homo- vs. hetero-coupling within a mixture of reactive olefins still remains a challenge. Here, we discuss the use of colloidal CdSe quantum dots (QDs) as visible light absorbers, triplet exciton donors, and scaffolds to drive homo- (photodimerization) and hetero- (cross coupling) intermolecular [2+2] photocycloadditions of 4-vinylbenzoic acid derivatives, with >90%, switchable regioselectivity and up to 98% diastereoselectivity for the previously minor syn-head-to-head (HH) or syn-head-to-tail (HT) configurations of the adducts. The diasteromeric ratios (d.r.) we achieve are a factor of 5 - 10 higher than those reported with all other triplet sensitizers. Furthermore, the size-tunable triplet energy of the QD enables regioselective hetero-intermolecular couplings through selective sensitization of only one of the reagent olefins. This is the first example of chemistry driven by triplet-triplet energy transfer from a QD. Host: Rachael Farber via email at email@example.com . If you need assistance, please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org
Tania Baker, Department of Biology, Massachusetts Institute of Technology
AAA+ Unfoldase Motors: Regulators of the Proteome as Activators and Destroyer of Protein Function
Particle Phenomenology Seminar: Zhen Liu
A pathway to the next discoveryThe discovery of the Higgs boson at CERN LHC marks the triumph of 50 years of endeavor of high energy physics. The Higgs discovery is only possible with a joint force between experimentalists and theorists in a phenomenological approach. The phenomenological approach and the Higgs boson itself light the pathway towards the next discovery. In this seminar, I will present my recent work that changes the perspective of the LHC main detectors in searches for a challenging class of new physics signals--long-lived particles (LLPs). The new physics signals are well-motivated by broad categories of new physics models, such as supersymmetry and hidden sector models. I will first identify the advantages of the LHC in comparison with other satellite experiments and then present our novel proposals with new triggers and analysis strategies to fully realize such strength, in close connection with the upcoming detector upgrades with precision timing and high granularity detectors. If time permits, I will briefly discuss a few attempts to probe new physics through novel table-top and non-collider experiments along this path. Finally, I will conclude with a broader picture of the pathway to the next discovery.
Kharasch Mini Symposium2:15 pm - Todd Hyster (Princeton) https://www.hysterlab.com/
2:50 pm - Ellen Sletten (UCLA) http://sletten.chem.ucla.edu/
3:25 pm - Mingji Dai (Purdue) http://www.chem.purdue.edu/dai/
4:00 pm - Coffee Break
4:15 pm - Carolyn Bertozzi (Stanford) https://bertozzigroup.stanford.edu/
Hannes Pichler, Harvard
From many-body physics to quantum information with atomic and photonic systemsQuantum many-body systems have unique properties that give rise to fascinating phenomena and potential applications, ranging from exotic phases of matter to new paradigms for information processing and communication. Novel technological developments in quantum optical systems allow to realize and study complex quantum many-body systems in a controlled way. In this talk I want to discuss examples that highlight how the tools available to control quantum optical system can be employed to bring abstract theoretical concepts to the laboratory, but also pose new theoretical challenges in describing such systems. To this end I will first discuss the physics of arrays of individually trapped Rydberg atoms  and the associated quantum many-body phenomena. This includes the equilibrium quantum phase diagram in 1D and the universal quantum critical behavior of the various accessible quantum phase transitions, as well as novel non-equilibrium phenomena such as quantum many-body scars. Moreover I show how these systems can be used to naturally encode combinatorial optimization problems and realize quantum annealers . In the second part of this talk I focus on atom-photon interfaces and present a novel way to create highly entangled states of photons by sequentially generating and correlating photons using a single quantum emitter in a waveguide QED setting. I show that employing novel concepts, such as delayed quantum feedback dramatically expands the class of achievable photonic quantum states and allows to generate states that are universal resources for quantum computation with minimal experimental resources .
Special Seminar (Particle Phenomenology): Andrea Thamm, CERN
Beyond the Standard Model: Beyond the LHCAfter an introduction to the Standard Model (SM) of Particle Physics and the Large Hadron Collider, I discuss some open questions in the SM, focussing in particular on the hierarchy problem and dark matter. I then describe three theoretical directions which address these open problems: heavy new physics, light new physics and models of dark matter. I discuss their motivations, basic setup and the role future colliders could play in their discovery.
Peggy Mason, University of Chicago
Empathy: The good, the bad, and the uglyBoth the benefits of empathy and the exceptional human qualities needed to exhibit empathy are widely touted in popular culture. Yet rats appear to act out of other-oriented concern, a putative rat analog of empathy, by releasing a fellow rat that is trapped in a tube. This finding shows that empathically driven helping is not restricted to humans and is a process that occurs in other mammals including rats. Empathic helping is proximally driven by the reinforcing consequences of the act of helping which is rewarding so that helping “feels good.” Nonetheless, empathic helping requires both emotional caring and the ability to down-regulate one’s own emotions. Thus, empathic helping is resource-depleting and can be personally costly. This ultimately drives the selective application of empathic helping to in-group members. Finally, rats appear to be more reinforced by releasing a trapped rat than by seeing a trapped rat receive help, suggesting that the act of helping is more rewarding than is the relief of distress. The dissociation between active helping and help received suggests that those who take actions intended to help may be receiving a reward that may be incommensurate with the help that is in fact received. This can lead individuals to falsely perceive their actions as helpful; Such falsehoods can be counterproductive in the context of medicine, leading physicians who actively treat patients to consider a problem resolved when it is not.
Kadanoff Special Seminar: Gil Young Cho, Postech
Many-Body Invariants for Multipoles in Higher-Order Topological InsulatorsWe propose many-body invariants for multipoles in higher-order
topological insulators by generalizing Resta's pioneering work on
polarization. The many-body invariants are designed to measure
multipolar charge distribution in a crystalline unit cell, and they
match the localized corner charge originating from the multipoles. We
provide analytic arguments and numerical proof for the invariants.
Furthermore, we show that the many-body invariants faithfully measure
the physical multipole moments even when the nested Wilson loop
approaches fail to do so.
Nichole Yunger Halpern, Harvard
Quantum steampunk: Quantum information meets thermodynamicsThermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, and out-ofequilibrium. Nineteenth-century thermodynamics requires updating for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Quantum information theory describes how we can use nonclassical phenomena (entanglement, uncertainty, discreteness, etc.) to process information in ways impossible with classical hardware. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization?) and suggests new technologies (e.g., quantum engines). I will overview how quantum information theory can modernize thermodynamics for quantum-information-processing technologies, then will focus on thermalization in quantum many-body systems. I call this combination quantum steampunk, after the steampunk genre of literature, art, and cinema that juxtaposes futuristic technologies with 19th-century settings.
Bryan Dickinson, University of Chicago
Synthetic Biology Approaches to Study and Exploit RNA RegulationRNA controls information flow through the central dogma and provides unique opportunities for manipulating cells. However, both fundamental understanding and potential translational applications are impeded by a lack of methods to study and exploit the regulation of RNA. Here, I will present three vignettes on our recent protein engineering and molecular evolution efforts focused on understanding and controlling RNA. First, I will show how our engineered RNA polymerase-based biosensors can be exploited as a new method to harness rapid molecular evolution to solve problems in molecular recognition. Second, I will unveil a new evolution system for creating reverse transcriptases that encode RNA modifications in mutations, which allow us to catalog the precise locations of a poorly-understood RNA methylation modification in mammalian cells. Finally, I will present CRISPR/Cas-inspired RNA targeting system (CIRTS), a new protein engineering strategy for constructing programmable RNA regulatory systems, built entirely from human protein parts. Collectively, our technology development focused around RNA regulation will continue to shed light on how mammalian cells function at a fundamental level, while also opening up new opportunities in molecular evolution and epitranscriptomic biotechnology development.
Particle Phenomenology Seminar: Simon Knapen
Searching for whispers from beyond the standard modelSearches for high energy signatures from beyond the standard model physics have advanced greatly, but a lot of ground remains to be covered for soft, low energy signals. At the LHC, searches for long-lived particles are such an example, as qualitative gains are possible by making full use of the LHCb cavern in the phase II upgrade. In the context of dark matter direct detection, future single-phonon detectors will be sensitive to dark matter with a mass as low as roughly 10 keV. In this regime, the conventional nuclear recoil picture no longer applies and new theoretical tools are needed to correctly compute the scattering rate. I will discuss the prospects for detector concepts based on superfluid helium and polar material targets, where in the latter case we find a large daily modulation of the scattering rate.
Arthur Barnard, Stanford University
New tools for probing classical and quantum nanomaterialsIn this seminar, I will discuss two domains of condensed matter physics elucidated by new tools: thermal motion in nanomechanical structures and quantum electron transport in 2D materials. By picking up individual carbon nanotubes and coupling them with electrostatic gates and optical cavities, we directly read-out non-equilibrium dynamics and observe real-time Brownian motion. We reveal surprising spectral dynamics obscured by existing measurement techniques, shedding light on the physics behind the unexpectedly low quality-factor in room temperature carbon nanotube resonators. In the second part of this seminar, I will explain how we control the flow of electrons in graphene. Drawing from intuitions in ballistic transport and light optics, we produce collimated electron beams to quantitatively study angularly dependent phenomena such as Klein tunneling, and elucidate how electrons start to behave like a fluid as they interact more strongly with each other. Using scanning gate microscopy, we image how electrons can follow non-circular cyclotron orbits in graphene-based superlattices.
Gurol Suel, University of California San Diego
The resilience & dichotomy of bacterial existence
Jennifer Lippincott-Schwartz, HHMI
Peering Into Cells with New Imaging TechnologiesPowerful new ways to image the internal structures and complex dynamics of cells are revolutionizing cell biology and bio-medical research. In this talk, I will focus on how emerging fluorescent technologies are increasing spatio-temporal resolution dramatically, permitting simultaneous multispectral imaging of multiple cellular components. Using these tools, it is now possible to begin constructing an “organelle interactome” describing the interrelationships of different cellular organelles as they carry out critical functions. The same tools are also revealing new properties of the cell’s largest organelle, the endoplasmic reticulum, and how disruptions of its normal function due to genetic mutations may contribute to important diseases. Results from these and other technologies that significantly increase spatial resolution in 3-D, including focused ion beam scanning electron microscopy, will be presented.
Hoi Chun Po, MIT
Symmetry shortcuts to topological materialsThe discovery of topological insulators unveiled a new class of quantum materials whose physical properties are crucially determined by the interplay between symmetries and topology. In this talk, I will discuss how this discovery points to a natural revision of the paradigm of symmetry analysis of weakly correlated materials. Within this new framework, we further develop a general theory for the diagnosis and classification of topological crystalline materials. Our theory integrates theoretical insights originating from the formal classification of topological phases with conventional first-principles calculations, which enables us to efficiently identify thousands of topological materials candidates scattered across the 230 space groups.
A surface-grafted polymer brush that can flip a nematic fluid, then flip it back.Let us dine 12:00
Let us opine 12:15
Pablo Jarillo-Herrero, Massachusetts Institute of Technology
Magic Angle Graphene: a New Platform for Strongly Correlated PhysicsThe understanding of strongly-correlated quantum matter has challenged physicists for decades. Such difficulties have stimulated new research paradigms, such as ultra-cold atom lattices for simulating quantum materials. In this talk I will present a new platform to investigate strongly correlatedphysics, based on graphene moiré superlattices. In particular, I will show that when two graphene sheets are twisted by an angle close to the theoretically predicted ‘magic angle’, the resulting flat band structure near the Dirac point gives rise to a strongly-correlated electronic system. These flat bands exhibit half-filling insulating phases at zero magnetic field, which we show to be a correlated insulator arising from electrons localized in the moiré superlattice. Moreover, upon doping, we find electrically tunable superconductivity in this system, with many characteristics similar to high-temperature cuprates superconductivity. These unique properties of magic-angle twisted bilayer graphene open up a new playground for exotic many-body quantum phases in a 2D platform made of pure carbon and without magnetic field. The easy accessibility of the flat bands, the electrical tunability, and the bandwidth tunability though twist angle may pave the way towards more exotic correlated systems, such as quantum spin liquids or correlated topological insulators.
Shenshen Wang, Physics & Astronomy, UCLA
Discovering generalist solutions in rough & changing landscapesEvolving systems, be it an antibody repertoire in the face of mutating pathogens or a microbial population exposed to varied antibiotics, respond to ever changing environments through a constant search for adaptive solutions in high-dimensional fitness landscapes. Generalists are robust performers in varied environmental conditions. For better (induction of broad antibody response) or worse (emergence of multi-drug resistance), it is important to be able to discover these adaptive solutions efficiently. Yet, whether and when environmental changes can grant evolutionary advantage to generalists in the long run remains elusive. We introduce a generic landscape framework to study the evolutionary discovery of generalist solutions in slowly changing environments. We show that alternation between rugged fitness landscapes can enhance the propensity to evolve fit generalists, if the landscapes’ topography balances a tradeoff between prevalence, fitness and accessibility, thus demonstrating a general route toward favoring or avoiding generalists via a proper choice of alternating environments. This has important implications for speeding up the generation of broadly neutralizing antibodies or preventing microbes from evolving multi-drug resistance.
Shmuel Rubinstein, Harvard
The physics of crushing and smashing: Cascades and cataclysmic changeMany of the big problems we are facing involve far from equilibrium systems that entail a cataclysmic change. Climate, turbulence and earthquakes, developmental biology, evolution and even aging and death. These phenomena are rare (sometimes occurring only once) and are entirely irreversible. While understanding the physics of such irreversible processes is of both fundamental and practical importance, these problems also pose unique challenges. These challenges, as they manifest in turbulence, were beautifully portrayed by Richardson:
“Big whirls have little whirls that feed on their velocity, and little whirls have lesser whirls and so on to viscosity” Lewis Fry Richardson (1922)
In his short verse, Richardson captures the essence of the turbulent cascade—the conveyance of kinetic energy across scales that underlies the universal dynamics of turbulent flows. Indeed, such conveyance of important physical quantities (energy, stress, frustration and even information) down and up a vast range of scales underlines the dynamics of many systems. The same applies to how a multi-contact frictional interface will form and break or how correlated defect structures determine the strength of a space-rocket, how an intricate network of creases will form when we crumple a thin sheet or when soda can is smashed. The challenge in understanding these systems is in capturing the events as they occur, keeping up with the dynamics on all scales and at all times. Here, I will review our work on several key irreversible system and introduce the new tools we developed to address their unique evolution and discuss the interesting physics we learned.
Andrew Potter, Honeywell
Entanglement dynamics and topology in driven systemsDramatic advances in AMO systems and ultra-fast optics have assembled a powerful toolbox for coherently and time-dependently manipulating quantum many-body systems, raising enticing prospects for engineering phases of quantum materials and developing quantum information processing technology. However, conventional wisdom dictates that driven many-body systems should follow the principles of eigenstate thermalization, behaving chaotically and rapidly scrambling stored quantum information.
Surprisingly, this trend can be thwarted by artificially disordering isolated systems to selectively freeze dissipative processes that cause thermalization while enabling long-lived quantum coherent dynamics -- a phenomena dubbed many-body localization (MBL). Driving MBL systems enables new non-equilibrium "phases" of matter with stable dynamical quantum properties that are not possible in equilibrium. This talk will describe how developing new tools to characterize the topology and dynamics of quantum entanglement in MBL systems has enabled substantial progress towards systematically classifying these dynamical phases, understanding their signatures, and designing experimental realizations.
Special Seminar (Particle Phenomenology): Prateek Agrawal
Axions at the discovery frontierThe next decade will push the boundary of our understanding of fundamental physics in a number of directions, potentially culminating in new discoveries. I will describe how new theoretical insights are pushing this discovery frontier forward. After a broad overview, I will focus on recent progress in axion physics. Axions are compelling candidates for new physics, and traditional axion models predict a relatively narrow target for experiments. I will present novel mechanisms in cosmology and quantum field theory that broaden this parameter space significantly, motivating new experiments. Such an extension of our search strategy may prove crucial to the discovery of axions.
Edbert Sie, Stanford
How to Control Quantum Materials with LightA primary goal of modern condensed matter physics is to discover novel quantum phases of matter and engineer their properties. However, conventional approaches using material synthesis or static electromagnetic fields have enabled only a limited exploration of the phase space and associated symmetries at thermal equilibrium. In this talk, I will discuss how we use light to manipulate the space-time symmetries in materials and discover new quantum phenomena that were previously inaccessible. First, I will show that breaking time-reversal symmetry with light enables us to lift the pseudospin degeneracy in monolayer WS2 and selectively tune their energy levels. Here we can completely disentangle the fundamental light-matter interaction into two previously inseparable quantum processes known as the optical Stark effect and the Bloch-Siegert shift. Second, I will show that manipulating inversion symmetry with light allows us to induce topological phase transitions in the Weyl semimetal WTe2 through strain-tuning the lattice. The induced atomic displacements were crystallographically measured using relativistic electron diffraction at sub-picometer length scale and sub-picosecond time scale. These results offer nonequilibrium pathways for designing tunable quantum properties towards terahertz electronics, quantum information, and energy conversion technologies.
Odd elasticity: soft engines from active solidsFood eaten 12:00
Thoughts spoken 12:15
Dominic Else, MIT
Topological phases of matter with spatial symmetriesA topological phase is a phase of matter characterized by a non-trivial long-wavelength pattern of quantum entanglement in the ground state of a strongly interacting quantum many-body system. I will describe a very general approach to understand such phases in the presence of spatial symmetries such as translation, rotation and reflection (such phases are often referred to as "crystalline topological phases"). There are several complementary ways to think about this approach, one of which is based on a systematization of the notion of gauging a spatial symmetry; I will also outline a more concrete geometrical picture in terms of "defect networks". Finally, I will show how this new understanding of crystalline topological phases allows for the unification and generalization of results such as the Lieb-Schultz-Mattis theorem for quantum spin systems, which can be reinterpreted as a kind of UV-IR anomaly matching in the presence of a spatial symmetry.
Special Seminar (Particle Phenomenology): Yue Zhang
New Dark Matter Signals in Neutrino DetectorsUnderstanding the nature of dark matter is a question lying at the heart of particle physics and cosmology. I will discuss the potential leading role of using our current and near future neutrino experiments in search for a class of dark matter candidates, and a number of associated new signals. With the new generation of neutrino detectors in the coming decade, many ideas can be tested. The complementarity with the other approaches will also be discussed in this talk.
Eric Spanton, UC Santa Barbara
Fractional Chern insulators in graphene heterostructuresGraphene is a highly tunable platform for studying the effects of electron-electron interactions in two dimensions. Encapsulation with a 2D dielectric (hexagonal boron nitride, hBN), and more recently the use of single-crystal graphite top and bottom gates have decreased the electronic disorder to a level suitable for the to study fragile and exotic strongly correlated states. Additionally, control of twist angle between closely-matched crystal lattices allows for unique control of electronic properties, leading to the “Hofstadter butterfly” and more recently unconventional superconductivity. I will describe the first experimental observation of a class of states in nearly aligned hBN/graphene heterostructures called fractional Chern insulators, a close relative of the fractional quantum Hall effect. In graphene, fractional Chern insulators arise in the presence of electron-electron interactions, high magnetic fields, and a long wavelength ‘moire’ superlattice formed by close alignment between hBN and graphene lattices. Twist angle between graphene and hBN, electron density and perpendicular electric field tune the underlying single-particle bands to realize different types of fractional Chern insulators. The realization of fractional Chern insulators opens the door for the study of novel topological phase transitions and exotic defect states.
Margaret Gardel, University of Chicago
Controlling the Shape of Cells within TissueMature epithelial tissues have distinct cellular architecture, which is maintained despite externally applied forces, wounding, and cell division or death. Here we investigate how a model tissue develops and maintains cellular structure by quantifying single cell dynamics and cell shape in newly formed monolayers of MDCK cells. Cells initially aggregate through a process resembling wound healing into a confluent monolayer with elongated cells that remain motile. After formation, individual monolayers evolve over time to reach a similar final state with more hexagonal cell shapes and arrested dynamics, resembling mature epithelial tissues. By quantifying cell trajectories, we observe glassy dynamics controlled by cell shape, which have been previously predicted by vertex models. On substrates of different stiffness, monolayers form and evolve with different cell number density but the same relationship between cell shape and speed suggesting that the dynamics are density independent. We find when inhibiting several regulators of the actin cytoskeleton that cell speed and shape remain correlated but the correlation is shifted toward more elongated cell shapes. The magnitude of this shift differs for each inhibitor but velocity correlation length decreases proportionately to the change in final cell shape. We show that these results can be recapitulated in vertex models which incorporate polarization coupling between neighboring cells. Our results demonstrate that multicellular coordination of cell motility plays an important role in regulation of cell shape and determination of final tissue structure.
Ke Xu, Department of Chemistry, University of California-Berkeley
Multifunctional & Multidimensional Super-resolution MicroscopyRecent advances in super-resolution fluorescence microscopy have led to ~10 nm spatial resolution and exciting new biology. We are developing new approaches to advance beyond the structural (shape) information offered by existing super-resolution methods, and reveal multidimensional information of intracellular functional parameters, including chemical polarity, diffusivity, and reactivity, with nanoscale resolution and single-molecule sensitivity. By adding remarkably rich functional dimensions to the already powerful super-resolution microscopy, we thus open up new ways to reveal fascinating local heterogeneities in live cells. Host: Bozhi Tian, 2-8749 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Ryo Nakano, Nagoya University
Study on Olefin Polymerization Toward Utilization of Carbon DioxideAlthough carbon dioxide has attracted broad interest as a renewable carbon feedstock, its favorable nature as a carbon source is inextricably linked to its inherent inertness. Therefore, to overcome the endothermic penalty of carbon-dioxide incorporation, a transformation of carbon dioxide under mild conditions requires a thermodynamic driving force from coupling partners. In this context, copolymerization of carbon dioxide and olefin, which is the largest class of organic chemicals produced today, will be a suitable reaction exploiting the prospective features of carbon dioxide as a C1 bulk feedstock.
From a theoretical consideration on the thermodynamics of olefin/carbon dioxide copolymerization, stepwise and direct copolymerization were investigated. The stepwise approach was successfully demonstrated in butadiene/carbon dioxide copolymerization via a lactone intermediate, as the first example to prepare high-molecular-weight copolymer starting from a bulk alkene and carbon dioxide. For further expansion of the scope of olefins toward monoenes, namely ethylene and propylene, palladium catalyst bearing an NHC-based bidentate ligand (IzQO) was designed rationally. While the CO2/monoene copolymerization was not accomplished, the palladium/IzQO complexes exhibited unique catalytic activities for propylene/polar monomer copolymerization and ethylene/1,1-disubstituted olefin copolymerization.
Why do my flying lego blocks spin and make hinges?Eatin' time 12:00
Thinkin' time 12:15
Reina Maruyama, Yale University
Testing DAMA's Long-standing Claim for Dark Matter DetectionAstrophysical observations give overwhelming evidence for the existence of dark matter. Several theoretical particles have been proposed as dark matter candidates, including weakly interacting massive particles (WIMPs), axions, and more recently their much lighter counterparts, however there has not yet been a definitive detection of dark matter. One group, the DAMA collaboration, has asserted for years that they observe a dark matter-induced annual modulation signal in their NaI(Tl)-based detectors. Their observations seem to be inconsistent with those from other direct detection dark matter experiments under most assumptions of dark matter. In this talk I will describe the current status of the debate and the world-wide experimental effort to test this extraordinary claim. I will report the recent results from the COSINE-100 experiment and our progress toward resolving the current stalemate in the field.
Andrew Feguson, Institute for Molecular Engineering, The Univeristy of Chicago
Machine Learning Collective Variable Discovery in Colloidal Assembly and Protein FoldingData-driven modeling and machine learning have opened new paradigms and opportunities in the understanding and design of soft and biological materials. The automated discovery of emergent collective variables within high-dimensional computational and experimental data sets provides a means
to understand and predict materials behavior and engineer properties and function. I will describe our recent work in the use of two machine learning techniques for collective variable discovery within molecular simulation – nonlinear manifold learning using diffusion maps, and nonlinear dimensionality reduction using autoencoding neural networks (“autoencoders”). First, I will describe our applications of graph matching and diffusion maps to determine low-dimensional assembly landscapes for self-assembling patchy colloids. These landscapes connect colloid architecture and prevailing conditions with
emergent assembly behavior, and we use them to perform inverse building block design by rationally sculpting the landscape to engineer the stability and accessibility of desired aggregates. Second, I will describe our use of autoencoders to perform automated discovery of collective variables in proteinfolding. We interleave deep learning variable discovery and enhanced sampling directly within the discovered variables to perform simultaneous on-the-fly variable discovery and accelerated sampling of protein folding funnels.Host: Suri Vaikuntunathan, 2-7256 or via email to email@example.com. Persons with a disability who need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Su-Yang Xu, MIT
Topology and Geometry in Quantum MaterialsFinding new phases of matter and understanding their physics are primary goals of condensed matter physics. Advances in quantum physics can in turn breed novel technologies, benefiting our society. Topological states are new phases of matter characterized by a nonzero topological invariant. They can support protected surface/edge states, realize elusive particles, and respond to electric and magnetic fields in unconventional ways. On a more fundamental level, topological physics arise from the geometric properties of the quantum wavefunction, i.e., quantum geometry, which include Berry curvature, Berry connection, quantum metric, etc.
First, I will describe how we search for material platforms that support new topology and quantum geometry. In particular, I will focus on our theoretical predictions and experimental observations of the first Weyl fermion semimetal state in TaAs and later the topological chiral crystal state in RhSi. Second, I will describe nonlinear optoelectronic and transport measurements that can probe Berry curvature and interaction in a symmetry-sensitive way. Specifically, I will show how we use mid-infrared photocurrents to probe the chirality of Weyl fermions and other Berry curvature physics in 3D and 2D topological materials. I will also show our photocurrent detection of a novel electronic instability, the gyrotropic order, in the correlated semimetal TiSe2, and how we use circularly polarized light to manipulate such order via quantum geometrical responses. In the final part, I show how current works suggest ample new exciting possibilities to discover fundamental physics in topological condensed matter physics, which also offers pathways to quantum sensing, information and computation technologies.
Marc-André Légaré, University of Würzburg
Main-Group Metallomimetics: Strategies for Metal-Free Catalysis and Small-Molecule ActivationThe importance of transition metals (TMs) in modern catalysis cannot be overstated. TM-based catalysts enable processes that are of tremendous human and economic importance; they have innumerable applications in many industrial sectors. However, the toxicity, price and natural scarcity of many elements that are used in TM catalysis fuel an interest for the development of metal-free catalysts based on the main-group elements.
However, contrary to many catalytically-active TM complexes, classical main-group compounds do not possess the combination of empty and filled orbitals that is crucial for the complex electronic processes involved in the elemental steps of catalytic cycles. The development of catalysts based on the p-block elements thus requires the design and application of unique strategies. In this seminar, I will present two approaches for the metallomimetic application of boron compounds to small-molecule activation, to reduction processes, and to organic functionalization reactions. I will discuss systems that involve the combination of single and multiple active sites in order to mimic the electronic environment of TM complexes. Similarities and differences in the reactivity of main-group compounds and TM complexes will also be highlighted.
Katharine Diehl, Princeton University
Illuminating Epigenetic Mechanisms in Cancer with Designer ChromatinIn the eukaryotic cell, the genome is packaged in a nucleoprotein complex known as chromatin. Histones comprise the protein component of chromatin and serve as a hot bed for post-translational modifications (PTMs) that dynamically modulate local chromatin state to control DNA transcription, replication, and repair. Importantly, cancer cells depend on altered epigenetic landscapes to drive genomic instability and aberrant gene expression. In order to precisely target epigenetic misregulation in disease, it is critical to elucidate the mechanistic basis of how specific chromatin states are established and maintained. This talk will discuss how synthetic access to defined chromatin substrates enables the discovery of mechanisms by which histone PTMs modulate the genome. In the first part, a DNA-barcoded mononucleosome library was used to profile the activity of crucial DNA damage sensor enzymes (PARP1/2), uncovering new regulatory features in the DNA damage response. In the second part, designer chromatin substrates were used to investigate an oncogenic histone mutant, revealing details of how this mutation leads to deleterious epigenetic reprogramming. These efforts demonstrate how protein chemistry can be integrated with biochemical, biophysical, and genetic tools to facilitate analysis of the physicochemical principles underlying epigenetic dysregulation.
winner take all: from neural networks to nucleationGala reception 12:00
Gala discussion 12:15
Paola Ruggiero (SISSA and INFN)
Conformal field theory for inhomogeneous systems: the example of a breathing Tonks-Girardeau gasConformal field theory (CFT) has been extremely
successful in describing universal effects in critical one-dimensional
(1D) systems, in situations in which the bulk is uniform. However, in
many experimental contexts, such as quantum gases in trapping
potentials and in several out-of-equilibrium situations, systems are
strongly inhomogeneous. Recently it was shown that the CFT methods can
be extended to deal with such 1D situations: the system's
inhomogeneity gets reabsorbed in the parameters of the theory, such as
the metric, resulting in a CFT in curved space. Here in particular we
make use of CFT in curved spacetime to deal with the
out-of-equilibrium situation generated by a frequency quench in a
Tonks-Girardeau gas in a harmonic trap. We show compatibility with
known exact result and use this new method to compute new quantities,
not explicitly known by means of other methods, such as the dynamical
fermionic propagator and the one particle density matrix at different
Sebastian Huber, Department of Physics, ETH Zürich
Axial Magnetic Fields in Weyl SystemsWhile acoustic or elastic waves can easily be forced into behaving like electrons on a lattice, it is much harder to find analogies to the physics induced by a magnetic field. In my talk I will show how one can achieve exactly this by using phonons that are described by the relativistic Weyl equation. We engineer an acoustic crystal, where the low energy physics around a chosen frequency resembles the one of a Weyl particle in a magnetic field. We observe the resulting chiral Landau levels and I will present theoretical studies of non-local orbits in the presence of this synthetic magnetic field. Host: Vincenzo Vitelli, 4-8829 or via email to email@example.com. Persons with a disability who need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Dianne J. Xiao, Stanford UniversityHydrocarbons are cheap and abundant feedstocks readily derived from both fossil fuels and emerging renewable resources. Despite their abundance, hydrocarbons have limited applications in chemical synthesis due to the inertness of C–H bonds towards both homolytic and heterolytic bond cleavage. I will share two very different approaches to the selective functionalization of simple hydrocarbons that address these challenges. First, I will highlight a bio-inspired approach to achieve selective alkane hydroxylation using iron-based metal–organic frameworks. The critical influence of both primary and secondary coordination sphere elements on catalyst reactivity, selectivity, and stability will be detailed. Second, I will describe the identification and characterization of a simple heterogeneous base catalyst that converts aromatic hydrocarbons, CO2, and methanol into the corresponding aromatic esters at elevated temperatures. The transformation occurs via a two-step, semi-continuous cycle, and represents the first hydrocarbon CO2 insertion process that does not consume any energy-intensive stoichiometric reagents
Chiara Daraio, Caltech
Tunable, On-chip Phononic Devices Operating at MHz FrequenciesNanoelectromechanical systems (NEMS) that operate in the megahertz (MHz) regime allow energy transducibility between different physical domains. For example, they convert optical or electrical signals into mechanical motions and vice versa. This coupling of different physical quantities leads to frequency-tunable NEMS resonators via electromechanical non-linearities. In this talk, I will describe one- and two-dimensional, non-linear, nanoelectromechanical lattices (NEML) with active control of the frequency band dispersion in the radio-frequency domain (10–30 MHz). Our NEMLs consist of a periodic arrangement of mechanically coupled, free-standing nanomembranes with circular clamped boundaries. This design forms a flexural phononic crystal with a wide and well-defined bandgap. The application of a d.c. gate voltage creates voltage-dependent on-site potentials, which can significantly shift the frequency bands of the device. Additionally, I will discuss the experimental realization of topological nanoelectromechanical metamaterials with protected edge states. These on-chip integrated acoustic components could be used in unidirectional waveguides and compact delay lines for high-frequency signal-processing applications.
Prof. Sean T. Roberts, Department of Chemistry, University of Texas-Austin
Manipulating Energy and Spin for Photon Up- and Down-conversionThe negligible spin-orbit coupling in many organic molecules creates opportunities to alter the energy of excited electrons by manipulating their spin. In particular, molecules with a large exchange splitting have garnered interest due to their potential to undergo singlet fission (SF), a process where a molecule in a high-energy spin-singlet state shares its energy with a neighbor, placing both in a low-energy spin-triplet state. When incorporated into photovoltaic and photocatalytic systems, SF can offset losses from carrier thermalization, which account for ~50% of the energy dissipated by these technologies. Likewise, compounds that undergo SF’s inverse, triplet fusion (TF), can be paired with infrared absorbers to create structures that upconvert infrared into visible light. In this presentation, I will review our group’s efforts to create organic:inorganic structures that use SF and TF for improved light harvesting and photon upconversion. Host: Andrei Tokmakoff, 4-7696 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Joaquín Rodríguez-López, University of Illinois at Urbana-Champaign
Elucidating Electrochemical Energy Materials Through Versatile ElectrochemistryIn this seminar, I will discuss how new polymeric and low-dimensional materials, as well as an expanded electroanalytical toolbox for understanding interfaces, are allowing us to discover new synergies at the nano and mesoscale for emerging battery technologies. I will describe in detail one system where nano-scale heterogeneity has an impact on macro-scale performance: novel redox active polymers (RAPs) for size-selective flow batteries. Highly soluble RAPs are new players in redox flow technologies, and as part of our collaboration with the Joint Center for Research Energy Storage (JCESR), we are exploring the opportunities that macromolecular design offers for tuning their electrochemical performance. These investigations span across several areas of knowledge, from the interrogation of individual polymer particles, to the elucidation of new redox polyelectrolyte dynamics, and to the evaluation of flow battery performance. Finally, I will describe how we have applied insightful interfacial design and analysis to better understand other energy technologies such as ion batteries and electrocatalysts. Fundamental pursuit of electrode design principles have led us to investigate intercalation processes in low dimensional materials, and the use of ultra-thin electrodes for creating new charge transfer strategies on hetero-structures.
C. Rose Kennedy, Princeton University
Leveraging Mechanistic Insight to Enable Catalyst-Controlled Chemo-, Regio- & Stereoselective C–C Bond FormationMechanistic elucidation provides potent tools for enabling the design of efficient and selective catalytic transformations. Examples of mechanism-guided method development, drawing from the complementary strengths of ion-pairing organocatalysis and organometallic chemistry to achieve selective C–C bond formation, are described.
In the former case, combined experimental and computational analyses delineating the mechanisms of representative amido-thiourea-catalyzed transformations are discussed. Insights from these studies enabled (i) the rational design of linked bis-thioureas that impart enhanced efficiency for enantioselective anion-abstraction catalysis and (ii) the introduction of a synergistic ion-binding strategy for asymmetric catalysis of transformations involving electronically diffuse transition structures.
In the latter case, iron complexes bearing redox-active ligands are explored as catalysts for hydrovinylation and cycloaddition reactions proceeding through the intermediacy of metallacycles. Mechanistically informed ligand designs are leveraged to control metallacycle formation and fate to upgrade olefinic coupling partners with control of chemo-, regio-, and diastereoselectivity. Applications of the resulting cycloadducts for the synthesis of fuels, polymers, and fine chemicals are discussed.
Physics with A Bang! Holiday Lecture and JFI Open HouseStudents, families, teachers and especially the curious are invited to attend our annual Holiday Lecture and Open House. See fast, loud, surprising and beautiful physics demos performed by Profs. Heinrich Jaeger and Sidney Nagel. Talk to scientists about their latest discoveries. Participate in hands-on activities related to their research.
Saturday, December 8th, 2018
Kersten Physics Teaching Center
5720 S. Ellis Ave., Chicago, IL
Lecture repeated at 11am and 2pm
Open House and Demo Alley from 12pm-4pm
Lab Tours in the afternoon
Doors for the Lectures open 30 minutes before each show. Please note: there will be no online registrations, and will be a first to arrive, first ticketed event. We do not guarantee availibility of seating, but shows will also be streamed live to alternate venues. Those needing special assistance, please send an email to email@example.com.
Junichiro Yamaguchi, Waseda University
Making Bonds by Breaking Bonds: An Unconventional Approach to Making Molecules
Abigail Vieregg, University of Chicago
Discovering the Highest Energy Astrophysical Neutrinos Using a Radio Phased ArrayUltra-high energy neutrino astronomy sits at the boundary between particle physics and astrophysics. The detection of high energy neutrinos is an important step toward understanding the most energetic cosmic accelerators and would enable tests of fundamental physics at energy scales that cannot easily be achieved on Earth. IceCube has detected astrophysical neutrinos at lower energies, but the best limit to date on the flux of ultra-high energy neutrinos comes from the ANITA experiment, a NASA balloon-borne radio telescope designed to detect coherent radio Cherenkov emission from cosmogenic ultra-high energy neutrinos. The future of high energy neutrino detection lies with ground-based radio arrays, which would represent a large leap in sensitivity. I will discuss the demonstrated performance of a new radio phased array design that we have implemented on the ARA experiment at the South Pole and on the new BEACON experiment on White Mountain in California. The radio phased array has improved sensitivity to high energy cosmic particles and will push the energy threshold for radio detection down to overlap with the energy range probed by IceCube.
Katlyn K. Meier, Stanford University
Spectroscopic Characterization of Unique Iron and Copper Active Sites in Biology
Diana Qiu, University of California, Berkeley
Excitons in Flatland: Exploring and Manipulating Many-body Effects on the Optical Excitations in Quasi-2D MaterialsSince the isolation of graphene in 2004, atomically-thin quasi-two-dimensional (quasi-2D) materials have proven to be an exciting platform for both applications in novel devices and exploring fundamental phenomena arising in low dimensions. This interesting low-dimensional behavior is a consequence of the combined effects of quantum confinement and stronger electron-electron correlations due to reduced screening. In this talk, I will discuss how the low-energy optical excitations (excitons) in quasi-2D materials, such as monolayer transition metal dichalcogenides and few-layer black phosphorus, differ from typical bulk materials. In particular, quasi-2D materials are host to a wide-variety of strongly-bound excitons with unusual excitation spectra and massless dispersion. The presence of these excitons can greatly enhance both linear and nonlinear response compared to bulk materials, making them ideal candidates for applications in optoelectronics, energy harvesting, and energy conversion. Moreover, due to enhanced correlations and environmental sensitivity, the electronic and optical properties of these materials can be easily tuned. I will discuss how substrate engineering, stacking of different layers, and the introduction or removal of defects can be used to tune the band gaps and optical selection rules in quasi-2D materials.
Lou Charkoudian, Haverford College
Capturing Transient Interactions of Proteins Involved in Natural Product BiosynthesisHow do microorganisms produce chemically diverse and structurally complex molecules? How can humans harness this technology to better human health and the environment? These questions inspire our lab to study acyl carrier proteins (ACPs), which serve as central hubs in polyketide and fatty acid biosynthetic pathways. ACPs are notoriously challenging to study because the fast motions of the ACP phosphopantetheine (Ppant) arm make its conformational dynamics difficult to capture using traditional spectroscopic approaches. In this talk, I will present how the synthetic modification of the terminal thiol of the ACP Ppant arm can transform the ACP reactive site into a vibrational spectroscopic probe that can report on mechanistically-relevant movements of the ACP. I will share stories about how we leverage Ppant probes to resolve conformational dynamics on the picosecond time scale and visualize ACP complex formation with functional catalytic partners. We anticipate that these methods will be valuable in future structural and biosynthetic engineering studies because our approach is generalizable, practical, and scalable. Our studies combine concepts and techniques spanning biochemistry, organic chemistry, bioinformatics, and physical chemistry, and therefore I hope this talk will be of interest to a broad audience.
David Lubensky, University of Michigan
Organ size, inflationary embryology, and the statistical physics of tissue growthOne of the enduring mysteries of biology is how organs know to stop growing at the correct size and how those sizes are coordinated so that the animal retains the correct proportions. Here, we discuss several studies that in different ways address the precision with which organ size can be controlled. We first show that there are severe limits to the coordination of the sizes of left and right organs (like the left and right wings of a fruit fly) by chemical signals, suggesting that organ size is set primarily autonomously. We then consider the noisy dynamics of the growth of individuals tissues in the presence of various feedback laws. We find that only certain forms of mechanical feedback can specify a unique organ size. We also show that, even in the simplest, homogeneous case, stochastic growth of an elastic tissue has unexpectedly rich behavior: For example, it exhibits power law correlation functions, reminiscent of those seen in cosmological models, and soft modes that allow for diffusive growth of labelled clones of cells.
Weixin Tang, Harvard University
From Peptide Antibiotics to CRISPR-mediated Synthetic Memories: Tools from the Microbial Arsenal
Prof. Christophe Delerue, IEMN- CNRS, Paris
Localized Surface Plasmon Resonance in Doped Semiconductor NanocrystalsNanocrystals of heavily-doped semiconductors have recently emerged as very promising materials for plasmonics. In contrast to nanocrystals of noble metals, their Localized Surface Plasmon Resonance (LSPR) can be easily tuned in energy by controlling the carrier concentration through doping. In addition, due to the low concentration of carriers compared to metals, the LSPR can be
extended to infrared and near-infrared ranges. Recent experimental studies have demonstrated the existence of LSPR in doped nanocrystals of Si and different types of oxides (ZnO, SnO2, In2O3). However, the physics of the LSPR in these nanocrystals is not totally understood. In the first part of my talk, I will give of general overview of the field of doped semiconductor nanocrystal
plasmonics. In the second part, I will review theoretical studies that we have performed in order to address fundamental issues which are still highly debated. The evolution with doping concentration of the optical processes from single-electron to many-electron transitions will be described. The conditions required for the emergence of collective modes will be discussed. The results of atomistic calculations will be compared with those of more classical approaches. The role of the quantum confinement and the influence of the dopant potential and location will be discussed. The intrinsic mechanisms at the origin of plasmon damping in doped nanocrystals will be analyzed. The results confirm that doped nanocrystals are very promising for the development of IR plasmonics.Host: Philippe Guyot-Sionnest,2-7161 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Srimoyee Sen, University of Washington
Anyonic particle-vortex statistics and the nature of dense QCDI discuss the recent theoretical observation of Z_3 -valued particle-vortex braiding phases in high density QCD and its implications for higgs-confinement complementarity. As a consequence of the braiding phases, certain mesonic and baryonic excitations, in the presence of a superfluid vortex, have orbital angular momentum quantized in units of 1/3. Such non-local topological features can distinguish phases whose realizations of global symmetries, as probed by local order parameters, are identical. If Z_3 braiding phases and angular momentum fractionalization are absent in lower density hadronic matter, as is widely expected, then the quark matter and hadronic matter regimes of dense QCD must be separated by at least one phase transition
Mark Levin, Harvard University
Catalytic Manipulation of Reactivity and Selectivity at High-Valent NucleiThis presentation will examine aspects of reactivity and selectivity discovered through the exploration of the chemistry of high-valent nuclei [Au(III), Pt(IV), and I(III)]. The first part concerns two examples wherein transition metals are examined as substrates for catalytic reactions rather than in their traditional role as catalysts. Operating from this perspective, supramolecular catalysis of C(sp3)-C(sp3) reductive elimination and organoborane catalyzed C(sp3)-CF3 reductive elimination will be discussed, with the latter applied to [18F]-radiotrifluoromethylation. The second section will continue the focus on fluorination through the development of a new aryliodine catalyst for enantioselective olefin difluorination, exploring structural features that improve catalyst robustness and selectivity and enabling the preparation of chiral fluorinated building blocks.
Brad P. Carrow, Princeton University
Leveraging Polarizability and Electrophilicity in Catalysts for Challenging Coupling ReactionsA general approach by our group for the development of new catalytic synthetic methods that occur with higher efficiency and selectivity, use simpler reagents, and proceed with lower energy demand involves new ancillary ligand design coupled with fundamental studies of how metal-ligand bonding dictates catalytic reactivity. In this context, the presentation will focus on our recent efforts to discover new phosphorus- and sulfur-based ligands and associated metal catalysts that manifest special properties from seemingly "weak" interactions, for instance London dispersion. Two case studies will be discussed that exemplify such effects and emphasize many lessons yet to be learned about how structure controls reactivity in synthetic catalysts. In one case, a new transmetalation mechanism can be triggered in reactions of low-coordinate Pd complexes possessing polarizable diamondoid substituents, which enables smooth coupling catalysis even with historically unstable organoboron reagents. Studies of oxidative dehydrogenative coupling reactions will also showcase evidence for a C−H bond activation mechanism, termed electrophilic CMD or "eCMD", which has characteristics distinct from established SEAr and concerted metalation-deprotonation (CMD) pathways for C−H functionalization. Transition state analyses suggest this reaction pathway could be a general class of C−H activation manifested by many other transition metal catalysts, and selection rules have been identified for predicting what catalyst structures manifest either classic CMD or eCMD, which occur with unique substrate preferences and selectivity.
Junqi Li, Yale University
From Automated Small Molecule Synthesis to Understanding Chiral Phosporic Acid CatalysisEfforts to discover and optimize new small molecule function are often impeded by limitations in synthetic access to small molecules. This is because small molecule syntheses typically employ strategies and purification methods that are highly customized for each target. Furthermore, the molecular interactions between the catalyst and substrate are often not understood in catalyst-controlled selective reactions, thus impeding the design of new and more selective catalysts. In this seminar, an iterative cross-coupling strategy that enables the systematized and automated synthesis of different types of small molecules will be presented. The second part of the talk will discuss enantio- and site-selective reactions catalyzed by chiral phosphoric acids with a focus on understanding key catalyst-substrate interactions.
Regge limit in Holographic Conformal Field TheoriesWe will discuss the Regge limit of correlators in holographic CFTs and its
physical implications. Examples include constraints on the three-point couplings of the stress tensor
and the relation between heavy states in CFT and black holes in dual gravity.
More Than Pretty PicturesGraphics, images and figures — visual representations of scientific data and concepts — are critical components of science and engineering research. They communicate in ways that words cannot. They can clarify or strengthen an argument and spur interest into the research process.
But it is important to remember that a visual representation of a scientific concept or data is a re-presentation and not the thing itself –– some interpretation or translation is always involved. Just as writing a journal article, one must carefully plan what to “say,” and in what order to “say it.” The process of making a visual representation requires you to clarify your thinking and improve your ability to communicate with others.
In this talk, I will show my own approach to creating depictions in science and engineering—the successes and failures. Included will be a discussion about how far can we go when “enhancing” science images.
Wheland Lecture: Professor Jack W. Szostak, Harvard University
The Surprising Chemistry of Nonenzymatic RNA ReplicationThe RNA genomes of the first cells are thought to have emerged from the nonenzymatic replication of short RNA strands. We have recently found that the template-directed reaction of a primer with activated nucleotide substrates proceeds through an unexpected covalent intermediate. Our kinetic and crystallographic studies have provided insight into the mechanism of this key reaction, and to improvements in RNA copying chemistry that are both more prebiotically plausible and more accurate, efficient, and general.
Prof. Zahra Fakhraai, Department of Chemistry, University of Pennsylvania
Understanding Glass Transition Through Interfacial PropertiesFree surfaces and interfaces can affect properties of glassy systems over length scales that can be much longer than the intermolecular interaction potential. A fundamental understanding of the magnitude and length scale of these effects can allow us to understand the glass transition phenomenon and engineer nano-scaled materials with unique properties. In this presentation I show two examples of such effects and their use in producing thermally and kinetically stable glass materials. Extensive research in the past two decades has shown that the free surface of glasses, in particular for polymeric and organic glasses, have dramatically faster dynamics, resulting in strong reduction in their glass transition temperature, Tg, in ultra-thin films. We have recently shown that the surface dynamics can be faster by as much as eight orders of magnitude resulting in an apparent glass to liquid transition in molecular glass films as thick as 30 nm. The details of the thickness-dependent relaxation dynamics in thin films can elucidate properties of bulk glass that are key in verifying glass transition models. The enhanced mobility over such a large length scale can also help produce stable glasses with unique molecular packing upon physical vapor deposition.
In another example, we demonstrated that polymers’ thermal stability can be significantly improved in highly confined geometries. Capillary rise infiltration (CaRI) is used to load randomly closed-packed films of nanoparticles with various polymers. By changing the NP diameter, polymer can be confined in length scales as small as 2-3 nm. Under these conditions, entropic and enthalpic effects induced by interfaces play the dominant role in stabilizing the polymer, leading to higher Tg, higher viscosity, and improved resistance to burning and thermal degradation. We discuss the role of various parameters in achieving these thermally stable states. Host: Julia Murphy, firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Yichen Hu, University of Pennsylvania
On the Brink of FractionalizationSystems of strongly interacting particles can give rise to topological phases beyond non-interacting limit. Although unique features of strongly interacting topological phases, such as fractionalization of quantum degrees of freedom, have important applications in quantum information processing, these topological phases are still far from experimental realizations. In this talk, by presenting constructions of two strongly interacting topological phases, I will argue the key mechanism of their realizations is to add interactions near topological phase transitions. I will first introduce a model of interacting Majorana fermions that describes a superconducting phase with Fibonacci topological order. Then I will show that a correlated fluid of electrons and holes, dubbed fractional excitonic insulator phase, can exhibit a fractional quantum Hall effect at zero magnetic field. I will present physical evidence and conjecture that this phase can be realized in a higher angular momentum excitonic paired system in the presence of interactions.
Ethan Garner, PhD, Molecular and Cellular Biology, Center for Systems Biology, Harvard
Quantitating the motions of filaments gives insight into how bacteria grow as rods & control their rate of growthProf. Garner is hosted by Ed Munro and Sean Crosson
Wheland Lecture: Professor Jack W. Szostak, Harvard University
The Origin of Cellular LifeTo understand the origin of life on Earth, and to evaluate the potential for life on exoplanets, we must understand the pathways that lead from chemistry to biology. Recent experiments suggest that a chemically rich environment that provides the building blocks of membranes, nucleic acids and peptides, along with sources of chemical energy, could result in the emergence of replicating, evolving cells. I will discuss physical mechanisms that enable the growth and division of model protocells, the possible nature of primordial RNA, and the chemistry of its replication.
Emily Sprague-Klein, Northwestern University
Hot Electrons & Transient Molecular Dynamics in Plasmonic NanomaterialsExcitation of localized surface plasmon resonances yield non-equilibrium carrier populations that can then be harnessed to drive site-specific chemical processes at the nanoscale. We demonstrate the first direct detection of the molecular anion radical generated from plasmon-driven electron transfer in tightly confined sub-nanometer gaps under intense visible light irradiation. The energetics of these transient hot electron chemical processes are catalogued in a range of polypyridyl complexes in corroboration with open-shell density functional theory. Techniques for the observation of molecule-surface structural dynamics with high temporal and spatial resolution are discussed. The findings have broad applicability towards designing organic-inorganic hybrid microelectronics and nanoscale chemical reactors for surface redox reactions on the subnanometer scale. Host: Sarah King, 4-3809 or via email to firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Tania Baker, Department of Biology, Massachusetts Institute of Technology
Glueing together Modular flows with free fermionse revisit the calculation of multi-interval modular Hamiltonians for free fermions using a Euclidean path integral approach. We show how the multi-interval modular flow is obtained by glueing together the single interval modular flows. Our methods are based on a derivation of the non-local field theory describing the reduced density matrix, and makes manifest it's non-local conformal symmetry and $U(1)$ Kacs-Moody symmetry. We will show how the non local conformal symmetry provides a simple calculation of the entanglement entropy.
Gregory R. Bowman, PhD, Washington University
Identifying & Exploiting Protein Shape-shiftingA protein is a dynamic shape-shifter whose function is determined by the set of different structures it adopts. Unfortunately, it is often impossible to experimentally characterize most of these structures with the atomic resolution one would like in order to gain mechanistic insight or design drugs and mutations. The Bowman lab is combining enhanced sampling methods, such as Markov state models (MSMs), with biophysical experiments to overcome this limitation. Using this integrative approach, we are coming to a better understanding of how allosteric signals are transmitted between distant parts of a protein. We are also uncovering cryptic pockets that are absent in available experimental structures and provide new targets for drug development. To test our insights, we are designing and experimentally characterizing small molecules and mutations that exert allosteric control over distant functional sites. Examples of ongoing projects include (1) understanding how mutations give rise to antibiotic resistance, (2) designing allosteric drugs to combat antibiotic resistant infections, (3) understanding allosteric networks in G proteins and designing allosteric anti-cancer drugs, and (4) understanding and interfering with the mechanisms of Ebola infection.
Professor Matthew Bogyo, Stanford University
Chemical Tools for Identification and Imaging of Hydrolases Involved in the Pathogenesis of Cancer and Infectious DiseaseHydrolases are enzymes that often play pathogenic roles in many common human diseases such as cancer, asthma, arthritis, atherosclerosis and infection by pathogens. Therefore, tools that can be used to dynamically monitor their activity can be used as diagnostic agents, as imaging contrast agents and for the identification of novel enzymes and drug leads. In this presentation, I will describe our efforts to design and synthesize small molecule probes that produce a fluorescent signal upon binding to a hydrolase target. In the first part of the presentation, I will discuss probes targeting the cysteine cathepsins and their application to real-time fluorescence guided tumor resection and other diagnostic imaging applications. In the second half of the presentation, I will present our efforts to identify novel hydrolases in the pathogenic bacteria Staphylococcus aureus that could be targeted to enable both treatment and non-invasive imaging of disease progression.
Professor Oren Petel, Department of Mechanical and Aerospace, Engineering Carleton University
Impact Injury Evaluation and Mitigation Strategies Using X-ray ImagingBrain trauma from impact and/or blast and the resulting neurodegeneration has been linked to devastating health outcomes. While the use of helmets by athletes or soldiers can serve to drastically reduced the incidence of severe focal brain injuries, there continues to be a concerning level of incidence. While acute exposure to an injurious event can be detrimental to head health, there is building evidence suggesting that repeated low‐level exposure events are similarly of concern. Current helmet testing standards for impact events focus on the rigid‐body kinematics of head motion in the hope that they can be correlated to metrics of importance in leading injury mechanisms. These approaches typically use state‐of‐the‐art computational models that attempt to link these kinematic measures back to tissue strains and deformation profiles. Despite model validation against the same sets of cadaveric impact data, models predict vastly different strain profiles within tissue. In this presentation, I will provide an overview of our broad injury biomechanics research program at Carleton. This research program makes use of a state‐of‐the‐art X‐ray facility, designed by my research group, to achieve continuous X‐ray imaging speeds of 10,000 fps to investigate the dynamic response of cadaveric specimens, head models, and ex vivo tissue specimens as well as models for understanding impact mitigation using cellular materials and design strategies. Host: Heinrich Jaeger, 2-6074 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Alex Turzillo, Caltech
Free and Interacting Short-Range Entangled Phases of Fermions: Beyond the Ten-Fold WayIt is well-known that sufficiently strong interactions can destabilize some SPT phases of free fermions, while others remain stable even in the presence of interactions. It is also known that certain interacting phases cannot be realized by free fermions. In this talk, we will study both of these phenomena in low dimensions and determine the map from free to interacting SPT phases for an arbitrary unitary symmetry. We will also describe how to compute invariants characterizing interacting phases for free band Hamiltonians with symmetry (in any dimension) using only representation theory.
Closs Lecture: Professor Lewis Rothberg, University of Rochester
What You Don't See Can Hurt You: The Dark Matter Problem in Luminescent Conjugated PolymersHigh luminescence yields in solution bode well for easily processed conjugated polymers as the emissive species in photopumped film lasers, biological tags and display technology. The luminescence efficiency in the solid state, however, is often found to be low even when the polymer is doped dilutely into inert hosts. Our recent research involves trying to systematically vary morphology at the single chain level to illustrate the interplay between energy transfer amongst chromophores and aggregation of chromophores in determining the photophysics. We find dramatic variations in behavior as the polymer morphology evolves from extended to collapsed. In the intermediate case, we observe surprising and instructive phenomena that cannot be explained in the context of previous literature models. For example, we show that it is possible to greatly increase photoluminescence by deliberate selective photooxidation of low energy but poorly emitting chromophores. Consequences of this finding include intense luminescence spikes in single chain spectroscopy and the ability to post-process some bulk polymer samples to improve their luminescence efficiency. A revised model of the photophysics accounts for these phenomena and explains the failure of luminescence to scale with molecular weight, an observation fondly labeled “the dark matter problem” by Ivan Scheblykin.
Prof. Frederico Toschi, The Department of Applied Physics, Eindhoven University of Technology (ATU/e)
Genetic Competition in Weakly Compressible Turbulent FlowsThe genetic competition for biological species living in marine environments can be severely influenced by fluid advection. Very often, in oceans and in lakes, cell generation times are precisely in the inertial range of eddy turnover times and therefore the influence of turbulence must be properly taken into account. We employ both an off-lattice agent-based simulation as well as an on-site density-based model to describe two competing populations in one and in two spatial dimensions under the influence of advecting (turbulent) velocity fields. The novel on-site density-based model allows to accurately and efficiently describe the dynamics of the population and the genetics of large number of individuals, making this the ideal tool to study populations in two dimensions. We find that the presence of compressible turbulent velocity fields can have a very strong effect on genetic competitions. In particular, even in regimes where the overall population structure is approximately unaltered, the flow can significantly diminish the effect of a selective advantage on fixation probabilities. We explain this effect in terms of the enhanced survival of organisms born at the sources in the flow and the influence of Fisher genetic waves. We find for both cases that even in a regime where the overall population structure is approximately unaltered, the flow can significantly diminish the effect of a selective advantage on fixation probabilities. We understand this effect in terms of the enhanced survival of organisms born at sources in the flow and of the influence of Fisher genetic waves. Host: Vincenzo Vitelli, 2-7206 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Giorgio Gratta, Stanford University
Measuring gravity at short distances and other fun tricks with levitated microspheres
Chen-Te Ma, National Taiwan University
Bell’s Inequality, Generalized Concurrence and Quantum EntanglementWe demonstrate an alternative evaluation of quantum entanglement by measuring maximum violation of Bell's inequality without performing a partial trace operation in an n-qubit system by bridging maximum violation of Bell's inequality and a generalized concurrence of a pure state. This proposal is realized when one subsystem only contains one qubit and a quantum state is a linear combination of two product states. Finally, a relation of the generalized concurrence of a pure state and the maximum violation of Bell's inequality is also demonstrated in a 2n-qubit state.
Naturalizing SUSY with the Relaxion and the Inflaton
Oni Basu, University of Chicago
Single-cell Transcriptomics and Biology using MicrofluidicsThe basic units of biological structure and function are cells, which exhibit wide variation in regard to both type and state. We assess such variation by simultaneously profiling the transcriptomes of thousands of single mammalian cells (Drop-seq) or nuclei (DroNc-seq), using high-throughput emulsion microfluidics and DNA barcodes. These are accomplished by (a) encapsulating and lysing one cell/nuclei per emulsion droplet, and (b) barcoding RNA contents from each cell/nuclei using unique DNA-barcoded micro-beads, (c) performing Next-Gen Sequencing.
We are using these droplet-based techniques to profile cell types comprising complex tissues in a variety of tissue-types such as the heart and solid tumors in mouse models and human primary tissue. Besides, we are using Drop-seq and DroNc-seq to profile cell-states, particularly cellular heterogeneity in development and differentiation processes using a combination of cell lines, mouse embryonic tissue, in vitro culture, and human induced pluripotent stem cells.
We also develop custom microfluidic devices to study phenotypic responses of cells to different environmental stimuli including physical, bio-chemical and pathogenic stimuli; I will provide some examples to illustrate some applications.
The Tuesday JFI Seminar - Prof. Aashish Clerk, IME, The University of Chicago
Driven-dissipative Quantum Phenomena: from Synthetic Non-reciprocity to New Kinds of TopologyIn this talk, I’ll give an introduction to theory work in my group focused on understanding and exploiting driven-dissipative quantum phenomena in engineered quantum systems. I’ll start by discussing work showing how engineered dissipation can make almost any kind of interaction between two subsystems non-reciprocal (i.e. uni-direcitonal). This is provides a systematic approach for designing quantum systems with one-way interactions, with applications ranging from new kinds of quantum measurement devices to unusual many-body effects. In the second part of the talk, I’ll focus on work exploring how two-photon (parametric) driving can be used to realize new kinds of topological bosonic systems. While these systems have Hamiltonians analogous to topological superconductors, their physics is remarkably distinct from their fermionic partners. Among other things, I’ll discuss the surprising properties of a bosonic version of the Kitaev-Majorana chain, and how these ideas could be realized with superconducting quantum circuits. Host: Timothy Berkelbach, 4-9879 or via email at berkelbach@uchicago. Persons with a disability who may need assistance please contact Brenda Thomas 2-7156 or by email to firstname.lastname@example.org.
Hart Goldman, Illinois
Dirac Composite Fermions and Emergent Reflection Symmetry about Even Denominator Filling FractionsMotivated by the appearance of a “reflection symmetry” in transport experiments and the absence of statistical periodicity in relativistic quantum field theories, we propose a series of relativistic composite fermion theories for the compressible states appearing at filling fractions 1/2n in quantum Hall systems. These theories consist of electrically neutral Dirac fermions attached to 2n flux quanta via an emergent Chern-Simons gauge field. While not possessing an explicit particle-hole symmetry, these theories reproduce the known Jain sequence states proximate to filling 1/2n, and we show that such states can be related by the observed reflection symmetry, at least at mean field level. We further argue that the lowest Landau level limit requires that the Dirac fermions be tuned to criticality, whether or not this symmetry extends to the compressible states themselves
Zhen Gu, PhD, UCLA
Leverage Physiology for Bioresponsive Drug DeliverySpurred by recent advances in materials chemistry, molecular pharmaceutics & nanobiotechnology, stimuli-responsive “smart” systems offer opportunities for precisely delivering drugs in dose-, spatial- & temporal-controlled manners. In this talk, I will discuss our ongoing efforts in developing physiological signal-triggered bio-responsive drug delivery systems. I will first present the glucose-responsive synthetic systems for biomimetic delivery of insulin for diabetes treatment. Bio-responsive microneedle patches and vesicle fusion-mediated synthetic beta cells will be emphasized.
I will further discuss the local & targeted delivery of immunomodulatory therapeutics for enhanced cancer therapy. Our latest study utilizing platelets and injectable gels for targeted/local delivery of immune checkpoint inhibitors will be specifically introduced.
Mulliken Lecture: Professor Peter Rossky, Rice University
Translating the Message in Spectroscopic Probes of Conjugated Molecular MaterialsOver recent decades, there have been a steadily increasing number of studies on electronically conjugated materials for use in solar photovoltaic cells, organic transistors, and fluorescent probes. Progress in using semiconducting polymers has been limited by a fundamental lack of knowledge at the nanoscale underlying variations in electro-optical behavior. Hence, in contrast to familiar silicon-based technology, there is a dearth of principles to drive the bottom-up design of material building blocks.
Experiments probe such materials by their response to light, i.e., spectroscopically. The challenge is to interpret the observations in molecular terms. Computational modeling based on the physics of atomistic details and explicit electronic structure is ideally suited to enabling this connection of spectra to structure, since the connection in modeling is unambiguous while the experiment provides a strong constraint on the validity of the model. In this presentation, I will discuss examples of conjugated molecular material systems studied by theoretical, modeling, and experimental approaches that elucidate both atomistic and electronic structure and dynamics in a way inaccessible to either theory or experiment alone. Examples from the area of conjugated polymers and also from biosensors based on GFP will be presented.
Professor David Sarlah, University of Illinois at Urbana-Champaign
Dearomative Functionalization Strategies and Synthesis of Anticancer Natural Products"Small complex molecules are highly desired in all areas of chemistry, but they are also often difficult to access. Selective transformations of aromatic compounds could provide a more direct route to such desirable targets; however, the many challenges associated with dearomative functionalization have left these types of reactions widely underdeveloped. Our group has been developing new strategies that bridge the gap between dearomatization functionalization and alkene chemistry. In pursuit of this goal, we have developed dearomative functionalizations using small molecules – arenophiles – that enable reactions of isolated alkenes in aromatic substrates. Thus, well-established olefin reactions, such as dihydroxylation and reduction, can now be more directly applied to arenes. Additionally, arenophiles in combination with transition metal catalysis provide unique platform and enable the rapid access to a diverse range of products that are both challenging to synthesize via existing methods and complementary to those acquired through biological or chemical dearomative processes. Finally, using this methodology we have recently completed the synthesis of several complex anticancer natural products.
Transient driving that kinetically converts a foe into a friendbody food 12:00
brain food 12:15
Helen Quinn, SLAC
Science, Engineering and Art as well –why it is hard to teach science wellwill reflect on what we know about teaching science for k-12 students and for undergraduates, how we know it, and what it tells us about good teaching. To teach well you must engineer the right learning conditions with careful design goals for what is to be learned, you must understand both the subject area you wish to teach and something of what research on learning tells us about critical aspects of learning that area (this is known as pedagogical content knowledge or content knowledge for teaching) and then you must be a skilled improvisational performance artist to pull off the lessons as intended, responding to the needs of students who enter your classroom with a wide range of prior knowledge, engaging them all as active participants in the learning.
This talk is based on work I have been doing in the area of science education since my retirement in 2010 from physics research, summarizing what I have learned in the process. Illinois and approximately 30 other states have adopted new science standards based on the NAS study “A Framework for k-12 science education” that I led. This study tried to capture the learning about learning from science education research as well as to shift the goals for what needs to be learned. I will discuss how it, together with research studies focused on teaching physics or other sciences at the undergraduate level, suggests changes in undergraduate teaching approaches as well.
IME Distinguished Colloquium Series - Shanhui Fan, Stanford
Concepts of Nanophotonics and Energy ApplicationsLight, or electromagnetic waves, represent one of the most important carriers of heat and energy. New capabilities to manipulate light, as enabled by new classes of electromagnetic structures such as photonic crystals, metamaterials and plasmonic systems, therefore have significant implications for energy applications. In this talk, we will discuss some of these implications, illustrated by examples of our own recent works ranging from radiative cooling to dynamic wireless power transfer.
Event will be followed by a reception from 5 pm to 6 pm at ERC in IME’s 2nd floor lounge/atrium area
Brad Marston, Brown University
Topological Origin of Equatorial WavesTopology sheds new light on the emergence of unidirectional edge waves in a variety of physical systems, from condensed matter to artificial lattices. Waves observed in geophysical flows are also robust to perturbations, which suggests a role for topology. We show a topological origin for two celebrated equatorially trapped waves known as Kelvin and Yanai modes, due to the Earth’s rotation that breaks time-reversal symmetry. The non-trivial structure of the bulk Poincaré wave modes encoded through the first Chern number of value 2 guarantees existence for these waves. The invariant demonstrates that ocean and atmospheric waves share fundamental properties with topological insulators, and that topology plays an unexpected role in the Earth climate system.
1st Tuesday Colloquium - Prof. Mark D. Ediger, University of Wisconsin-Madison
Exploring the Limits of Amorphous Packing with Ultrastable GlassesGlasses formed by cooling a liquid inherit both their structure and their limited stability from the liquid state. In contrast, glasses prepared by vapor deposition can avoid both of these limitations. By utilizing the high mobility present near the free surface of many organic glasses, vapor deposition can build glasses with low enthalpy, high density, and high thermal stability. Based upon their position on the potential energy landscape, these materials approach “ideal glass” packing that otherwise could only be achieved by annealing a liquid-cooled glass for thousands or millions of years. Vapor deposition of organic semiconductors produces glasses with improved properties for organic electronics, including the ability to produce anisotropic glasses with a wide range of structures. Remarkably, this “anti-epitaxy” process uses the free surface structure as its template, rather than the substrate structure. Recent work has shown that optimizing vapor deposition can produce organic light emitting diodes (OLEDs) that are more efficient and have extended lifetimes. Host: Thomas Witten, 2-2-0948 or via email to email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Andy LiWang, PhD, Quantitative and Systems Biol, UC Merced
Can proteins tell time?Circadian clocks arose in organisms as an adaptation to the rotation of the earth. These clocks produce involuntary anticipation of sunrise and sunset by generating a succession of biochemical phases. In this talk, the mechanism of a model system, that of cyanobacteria, will be described. Briefly, it depends on phosphorylation, long-range allostery, dynamics, and protein metamorphosis. Because a simple mixture of clock proteins and ATP generate a persistent macroscopic rhythm, the mechanism of the clock can be studied in real time as it ticks. Now, signal transduction pathways have been reconstituted with the oscillator so that rhythmic transmission of clock signals can be studied in vitro.
Luca Delacretaz, Stanford University
Bounds on transport and thermalization from positivity
Professor Daniel G. Nocera, Harvard University
Food and Fuel from Sunlight, Air and Water
Naama Barkai, PhD, Molec Genetics and Physics, Weizmann
Robustness & scaling in embryonic developmentNaama Barkai, PhD, Departments of Molecular Genetics and of Physics of Complex Systems, Weizmann Institute of Science is the 2018-19 Frederick Seitz Lecturer in Interdisciplinary Science.
Informal reception will follow Dr. Barkai's presentation in the lobby of the KCBD
Professor Peter G. Wolynes, Rice University
Energy Landscape Theory: From Folding Proteins to Folding ChromosomesThe statistical mechanics of energy landscapes has resolved the paradoxes of how information-bearing matter can assemble itself spontaneously. I will explain how our current understanding of protein folding landscapes not only leads to successful schemes for predicting protein structure from sequence but also has given quantitative insight into how folding and function shape molecular evolution. While protein folding is, in the main, thermodynamically controlled and not kinetically limited, longer structures in the cell can assemble in a kinetically controlled, nonequilibrium fashion. Nevertheless, I will show how energy landscape theory provides tools for extracting from low resolution experimental structural methods and kinetic information about the structure and cooperative dynamics of chromosomes.'
Transient driving that kinetically converts a foe into a friendEat 12:00
Marcos Santander, The University of Alabama
Exploring the high-energy sky with neutrinos and gamma raysIn 2013 the IceCube neutrino observatory, a cubic-kilometer particle detector deployed deep within the South Pole glacier, announced the first detection of an astrophysical flux of high-energy neutrinos in the TeV-PeV range. This breakthrough discovery has prompted a wide-ranging observational effort aimed at identifying the sources of the neutrino flux by combining IceCube measurements with observations spanning the entire electromagnetic spectrum. Gamma rays in particular provide a powerful tool to search for neutrino source counterparts as both particles are produced in high-energy hadronic interactions. The detection and study of neutrino sources would not only signify the start of a new form of astronomy, but could also solve long-standing questions in high-energy astrophysics such as the origin of high-energy cosmic rays. This talk will introduce the IceCube detector, summarize recent results from multi-messenger searches of neutrino sources and present an overview of current and future gamma-ray follow-up observations, especially with the Cherenkov Telescope Array, a ground-based facility for very-high-energy gamma-ray astronomy currently under construction.
Saebyeok Jeong, Stony Brook
Opers, surface defects, and Yang-Yang functionalIn this talk, I will introduce a gauge theoretical derivation of a correspondence which relates quantization of integrable system to symplectic geometry . First, I will briefly review how the Hitchin integrable systems are associated with the class S theories. The Hitchin moduli space is identified with the moduli space of flat connecitons, with a distinctive Lagrangian submanifold of opers. It is suggested that the holomorphic functions on the space of opers are the (off-shell) spectra of the quantum Hitchin Hamiltonians . Moreover, the conjecture in  states that the generating function for the space of opers is equal to the effective twisted superpotential of the class S theory on the two-dimensional omega-background. I will show a gauge theoretical derivation of the correspondence. The derivation involves the following key ingredients:
1) Use half-BPS codimension-two (surface) defects in the class S theories to construct the opers and their solutions.
2) Analytically continue the surface defects partition functions to build connection formulas of the solutions.
3) Construct a Darboux coordinate system relevant to the correspondence.
4) Compute the monodromies of opers from 2) and compare with the expressions from 3) The direct comparison establishes the desired identity.
Timothy C. Berkelbach, University of Chicago
Stochastic Quantum ChemistryExact many-particle quantum mechanics has a prohibitive cost that grows exponentially with the size of the system. Most modern quantum chemistry is built on approximations that result in more tractable algorithms with polynomial scaling, but which qualitatively fail for many important problems. I will describe an alternative approach that uses stochastic techniques to circumvent this prohibitive cost (i.e. a flavor of quantum Monte Carlo). In particular, this approach is based on a very general and recently-developed framework for stochastic linear algebra called "fast randomized iteration", due to Lim and Weare. I will describe the FRI algorithm, its application to challenging problems in quantum chemistry, and its advantages over similar techniques.
The Tuesday JFI Seminar - Prof. Christos Panagopoulos, Nanyang Techenilogical University, Singapore
Tunable Room Temparature SkyrmionsThe electric field experienced by a travelling electron translates, in its rest frame, to a magnetic field proportional to its velocity – a relativistic effect which is notable in crystalline lattices with heavy atoms. The Zeeman interaction between the electron spin and this effective magnetic field is equivalent to the coupling of the electronic spin and momentum degrees of freedom, known as spin-orbit coupling (SOC). Importantly, SOC effects are greatly enhanced in reduced dimensions: inversion symmetry is broken at the surface or interface, and the resultant electric field couples to the spin of itinerant electrons. Host: Timothy Berkelbach, 4-9879 or via email to email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
The states induced by engineering SOC and inversion symmetry breaking in magnetic materials open a broad perspective, with impact in the technology of spin topology. For example, in conventional ferromagnets the exchange interaction aligns spins and the anisotropy determines energetically preferred orientations. Meanwhile, the interaction generated by SOC and broken inversion symmetry induces a relative tilt between neighbouring spins. Magnetic skyrmions – finite-size two-dimensional (2D) ’whirls’ of electron spin – form due to the competition between these ‘winding’ & ‘aligning’ exchange interactions.
Skyrmions have several compelling attributes as prototype memory elements, namely their (1) nontrivial spin topology, protecting them from disorder and thermal fluctuations, (2) small size and self-organization into dense lattices and (3) particle-like dynamics, manipulation and addressability. Using a novel materials architecture we developed recently, I will address quantifiable insights towards understanding skyrmion stability and dynamics, and directions for exploiting their properties in nanoscale devices at room temperature.
Yizhi You, Princeton Center for Theoretical Physics
Fracton phase of matter: Lattice models, gauge theories and realizationsFracton phase of matter shares many features of topological order, including long-range entangled ground states and non-trivial braiding statistics. At the same time, fracton phase contains subextensive ground-state degeneracy and the restricted mobility of quasiparticle which exclude itself from the TQFT paradigm. In this talk, I start from several fracton lattice models and demonstrate their relation with gauged subsystem symmetric SPT phase. Further, I will present a theoretical framework for higher Chern-Simons theory in 3D which realizes a deconfined U(1) fracton phase. In the end, I propose an experiment platform for realizing diverse fracton stabilizer codes based on interacting nanowires, which enables us to fabricate a zoology of fracton states and thus provides a powerful novel avenue to the realization of stable quantum memory and fault-tolerant quantum computing.
Professor Daniel Palanker, Department Ophthamology & Hansen Experimental Physics Laboratory, Stanford University
Photovoltaic Restoration of Sight in Retinal DegenerationRetinal degenerative diseases lead to blindness due to loss of the “image capturing” photoreceptors, while neurons in the “image-processing” inner retinal layers are relatively well preserved. Information can be reintroduced into the visual system using electrical stimulation of the surviving inner retinal neurons. Some electronic retinal prosthetic systems have been already approved for clinical use, but they provide low resolution and involve very difficult implantation procedures. We developed a photovoltaic subretinal prosthesis which converts light into pulsed electric current, stimulating the nearby inner retinal neurons. Visual information is projected onto the retina from video goggles using pulsed near- infrared (~880nm) light. This design avoids the use of bulky electronics and wiring, thereby greatly reducing the surgical complexity. Optical activation of the photovoltaic pixels allows scaling the implants to thousands of electrodes.
In preclinical studies, we found that prosthetic vision with subretinal implants preserves many features of natural vision, including flicker fusion at high
frequencies (>20 Hz), adaptation to static images, center-surround organization and non-linear summation of subunits in receptive fields, providing high spatial resolution. Initial results of the clinical trial with our implants (PRIMA, Pixium Vision) having 100µm pixels, as well as preclinical measurements, confirm that spatial resolution of prosthetic vision can reach the sampling density limit. For a broad acceptance of this technology by millions of patients who lost central vision due to age-related macular degeneration, visual acuity should exceed 20/100, which requires pixels smaller than 25µm. I will describe the fundamental limitations in electro-neural interfaces and 3-dimensional configurations which should enable such a high spatial resolution. Ease of implantation of these wireless modules, combined with high resolution opens the door to highly functional restoration of sight.
Host: Bozhi Tian, 2-8749 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Professor Matthew Kanan, Stanford University
Re-sourcing ChemicalsThis talk will describe our recent efforts to turn CO2 into a carbon source for commodity chemicals. Our goal is to develop scalable processes in which the use of CO2 affords a clear chemical advantage over conventional fossil fuel–based routes. I will first describe new carboxylation chemistry to generate (di)-carboxylic acids that have high-volume applications. Conventional carboxylation methodology relies on extremely energy-intensive reagents. We have found systems in which simple carbonate salts deprotonate un-activated C–H bonds, generating carbon-centered nucleophiles that react with CO2 to form C–C bonds. As one application, we used this chemistry to develop a high-yielding route from inedible biomass to furan-2,5-dicarboxylic acid (FDCA), a monomer that is currently being pursued as a replacement for terephthalic acid in polyester synthesis. To generalize this strategy, we have recently developed nanostructured carbonates that can perform hydrocarbon C–H insertion. In a two-step cycles, these materials convert arenes, CO2, and alcohols into aromatic esters with no use of stoichiometric reagents or generation of waste products. In the second part of my talk, I will describe our work on electrochemical systems for generating C2 feedstock chemicals. We have pioneered the use of grain boundaries to create metastable active surfaces for CO2 and CO reduction and recently elucidated a structural model to explain grain boundary effects. I will discuss the prospects for exploiting grain boundary effects in electrosynthesis and the design of prototype reactors that provide high synthesis rates and concentrated product streams.
Professor Jiaoyang Jiang, University of Wisconsin-Madison
Specificity, Function and Regulation of Protein O-GIcNAc ModificationThe N-acetylglucosamine (O-GlcNAc) modification is an essential glycosylation that has been identified on over 1,000 proteins. It dynamically modulates protein functions and regulates numerous biological processes in physiology and disease. O-GlcNAc modification is added by O-GlcNAc transferase (OGT) and removed by O-GlcNAcase (OGA). Despite recent progress, challenges remain to decipher the biological roles of O-GlcNAc modification and its regulation by OGT and OGA on a broad range of substrates that lack an apparent sequence motif. In this talk, I will present our recently developed structural biology and chemical biology approaches to start revealing the specificity, function and regulation of O-GlcNAc modification.
William Irvine, University of Chicago
Spinning Top-ologyGeometry, topology and broken symmetry play a powerful role in determining the physics of materials. In this colloquium I will talk of activated materials and fluids built out of mechanically spinning components and show how the subtle interplay of structure, time-reversal and parity leads to `odd' solid and fluid mechanics. In particular I will discuss a simple kind of active meta-material – coupled gyroscopes – that naturally encodes non-trivial topology in its vibrational spectrum. In particular, I will show how topology can emerge not only in ordered gyro materials but also their amorphous counterparts. We will then foray into activated colloidal gyro fluids and see how breaking symmetry under parity leads to chiral surface states and odd instabilities driven by viscous forces. We will use these chiral waves as a tool to observe the presence of odd (or Hall) viscosity in our chiral fluid.
Professor Marc Fontecave, Collège de France
FeS Clusters and Thiolation Reactions: Lessons from tRNA- and Protein-modifying EnzymesLiving cells are full of molecules containing sulfur atoms, for example biotin, lipoic acid, thiamin but also a variety of nucleosides within transfer RNAs and inorganic cofactors such as iron-sulfur (FeS) clusters. However, how these compounds are biosynthesized and how sulfur atoms are incorporated into organic substrates are still open fascinating questions. The discovery that important enzymes involved in thiolation reactions are FeS enzymes belonging to the Radical-SAM (S-Adenosyl-Methionine) enzyme superfamily, such as biotin synthase or lipoate synthase, has suggested a novel function for FeS clusters. It is proposed that they serve, in these enzymes, as a sulfur storage system from which sulfur atoms can be delivered to activated substrates during thiolation. The chemistry of Radical-SAM enzymes in the specific context of these reactions will thus be presented. However, other results, in particular from our laboratory, have challenged this theory since we have shown, during our functional and structural characterization of tRNA- and protein-sulfurating FeS enzymes (methylthiotransferases and thiolases) that thiolation can occur without mobilization of the sulfur atoms of the FeS clusters. Here we discuss these alternative mechanisms.
Pedro Saenz, MIT
Spin lattices of walking dropletsUnderstanding the self-organization principles and collective dynamics of non-equilibrium matter remains a major challenge despite considerable progress over the last decade. In this talk, I will introduce a hydrodynamic analog system that allows us to investigate simultaneously the wave-mediated self-propulsion and interactions of effective spin degrees of freedom. Millimetric liquid droplets can walk across the surface of a vibrating fluid bath, self-propelled through a resonant interaction with their own guiding wave fields. A walking droplet, or ‘walker', may be trapped by a submerged circular well at the bottom of the fluid bath, leading to a clockwise or counter-clockwise angular motion centered at the well. When a collection of such wells is arranged in a 1D or 2D lattice geometry, a thin fluid layer between wells enables wave-mediated interactions between neighboring walkers. Through experiments and mathematical modeling, we demonstrate the spontaneous emergence of coherent droplet rotation dynamics for different types of lattices. For sufficiently strong pair-coupling, wave interactions between neighboring droplets may induce local spin flips leading to ferromagnetic or antiferromagnetic order. Transitions between these two forms of order can be controlled by tuning the lattice parameters. More generally, our results reveal a number of surprising parallels between the collective spin dynamics of wave-driven droplets and known phases of classical condensed matter systems. This suggests that our hydrodynamic analog system can be used to explore universal aspects of active matter and wave-mediated particle interactions, including spin-wave propagation and topologically protected dynamics far from equilibrium.
Barry Bradlyn, UIUC
Wilson Loops, Wyckoff Positions, and Wannier Functions: New Developments in Stable and Fragile TopologyThe interplay of topology and geometry has been -- and continues to be -- a rich area of study for condensed matter physics. Recently, we have realized that spatial symmetries allow for the stabilization of topological phases much more exotic than those that can be found with time-reversal symmetry alone. Examples include topological crystalline insulators, "hourglass Fermion" phases, and Dirac and double-Weyl semimetals. In this talk, I will review recent developments in the theory of band representations which highlight the role of Wannier functions and holonomy in explaining the origins of topological crystalline behavior. I will show how this relates to several new ideas, such as symmetry indicators, topological phases with high co-dimension boundary states, and the "fragile" topology of isolated groups of bands. Finally, I will discuss how non-symmorphic symmetries can protect novel topological surface states, which can be diagnosed through the holonomy of Bloch functions.
MRSEC Surface Metrology Workshop
in cooperation with Olympus
8:30 AM : Breakfast
9:00 AM: Introduction to LEXT OLS5000 Laser Confocal Microscope, Guangnan Meng, PhD
10:00 AM: Coffee Break
10:15 AM: MRSEC Student Talks: Applications
11:30 AM: A Few Things You Need to Know About Surface Roughness: Guangnan Meng, PhD
12:15 PM: Lunch (registration required)
1:00 PM - 5:00 PM: Sample Demonstrations and Discussions
Please register online for free lunch and sample demos
Prof. Michael Grünwald, Department of Chemistry, University of Utah
Orientational Order in Self-Assembled Nanocrystal SuperlatticesSelf-assembly of nanocrystals into functional materials requires precise control over nanoparticle interactions in solution, which are dominated by organic ligands that densely cover the surface of nanocrystals. In this talk, I will present a computational study of ligand effects in the self-assembly of small, non-spherical nanocrystals. We focus on nanocrystals with cuboctahedral and truncated octahedral shape and determine their self-assembly behavior as a function of ligand length and solvent quality. Our model, which is based on a coarse-grained description of ligands and a schematic representation of solvent effects, reproduces the experimentally observed superstructures, including recently observed superlattices with partial and short-ranged orientational alignment of nanocrystals. We show that small differences in nanoparticle shape, ligand length and coverage, and solvent conditions, can lead to markedly different self-assembled superstructures due to subtle changes in the free energetics of ligand interactions. Our results help explain the large variety of different reported superlattices self-assembled from seemingly similar particles and can serve as a guide for the targeted self-assembly of nanocrystal superstructures. Host: Suri Vaikuntanathan, 2-7256 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Professor Marc Fontecave, Collège de France
Carbon Dioxide to Fuels: from Enzymes to Bioinspired Catalysts
Yuhai Tu, PhD, IBM
Nonequilibrium physics in biochemical oscillationsA central problem in systems biology is how living systems manage to perform precise functions (development, replication, signaling, etc.) by using inherently noisy biochemical networks. What are the molecular mechanisms for control? What are the design principles for the underlying biochemical networks? What are the energy costs for regulation? In this talk, we will present some recent results to address these general questions in biochemical oscillatory systems. We will discuss the molecular mechanism and energy cost for enhancing the accuracy and synchronization of biochemical oscillators ; and the design principles for oscillatory biochemical networks to achieve both high entrainability and low phase fluctuations .
 “The free-energy cost of accurate biochemical oscillations”, Y. Cao, H. Wang, Q. Ouyang, and Yuhai Tu, Nature Physics, 11, 772, 2015.
 “Design principles for enhancing phase sensitivity and suppressing phase fluctuations simultaneously in biochemical oscillatory systems”, C. Fei, Y. Cao, Q. Ouyang, and Yuhai Tu, Nature Communications, doi:10.1038/s41467-018-03826-4, 2018.
Chemistry Colloquium: Professor Naoto Chatani, Osaka University
Development of New Catalytic Reactions Involving the Activation of Traditionally Inert BondsOrganic molecules contain a variety of chemical bonds. Organic synthesis involves the cleavage of a chemical bond and the formation of a new chemical bond. However, not all of the chemical bonds in organic molecules have been used in organic synthesis. Thus, organic synthesis is heavily dependent on the reactivity of chemical bonds. If so-called unreactive bonds were to be used directly in organic synthesis, new possibilities for developing new synthetic methodologies would arise. We have utilized, not only the activation of C-H bonds, but also the activation of unreactive single bonds, such as C-C, C-O, C-N, and C-F bonds, and the activation of C-C triple bonds and C-O double bonds, in our quest to develop new types of transformations that will lead to further diversification in the field of organic synthesis.
Professor Michael J. Hatridge, Department of Physics, University of Pittsburgh
Qubit Measurement with Two-Mode Squeezed LightHigh fidelity qubit measurement is essential for scalable, fault-tolerant quantum computing. In superconducting circuits, qubit readout with fidelity above 99% has been achieved by using a quantum-limited parametric amplifier such as the Josephson Parametric Converter (JPC) as the first stage amplifier. However, the Signal-to-Noise Ratio (SNR) of such readout is fundamentally limited by quantum fluctuations in the coherent readout pulse. Alternatively, readout with squeezed light can be used to reduce fluctuation along certain quadratures and thus improve the SNR. In this talk, we demonstrate a readout scheme with two-mode squeezed light both produced and amplified by JPCs in an interferometer unbalanced by a transmon qubit/cavity. This configuration has been predicted to improve the SNR compared to readout with both coherent states and single-mode squeezed light. We have demonstrated a 50% improvement in SNR compared to coherent state readout, and find that the system actual works best when when we deliberately break the path for signals in the system, so that only the fluctuations passing through it interfere. We'll also discuss the prospects for placing qubits on both arms of the interferometer and performing measurements which generate remote entanglement between them.
Inorganic/Organic Seminar: Professor Hemamala Karunadasa, Stanford University
Between the Sheets: The Molecular Chemistry of Hybrid PerovskitesThe tools of synthetic chemistry allow us to tune molecules with a level of precision not yet accessible with inorganic solids. We have investigated hybrid perovskites that couple organic small molecules with the optical and electronic diversity of extended inorganic solids. I will share our current understanding of these materials, whose technologically relevant properties are highly amenable to synthetic design.
The 3D lead-iodide perovskites have recently been identified as low-cost absorbers for high-efficiency solar cells. Although the efficiencies of devices with perovskite absorbers have risen at an impressive rate, the materials’ intrinsic instability and toxicity may impede their commercialization. I will discuss methods developed by our group to address these problems. The 2D hybrid perovskites have dramatically different properties from their 3D congeners. We discovered that some 2D perovskites emit broadband white light (similar to sunlight) when excited by UV light. I will discuss how these materials, which do not contain extrinsic dopants or obvious emissive sites, could emit every color of visible light. Although the organic molecules in hybrid perovskites have mostly played a templating role, we have investigated their role in engendering reactivity. I will describe reactions that occur between the inorganic sheets, which allow these nonporous solids to capture small molecules.
Can a large packing be assembled from smaller ones ?Eat 12
Answer revealed 12:15
Jean Dalibard, Collège de France
Exploring Flatland with cold atomsThe physics of many-body systems strongly depends on their dimensionality. For example, in a two-dimensional world, most standard phase transitions towards an ordered state of matter like crystals or magnets would not occur because of the increased role of fluctuations. However, non-conventional phase transitions can still take place, as understood by Kosterlitz and Thouless (2016 Nobel prize). In this talk I will present some important features of Flatland physics explored with cold atomic gases, such as the existence of a superfluid transition that occurs in the absence of Bose-Einstein condensation. I will also discuss out-of-equilibrium properties of these atomic 2D gases, in connection with the so-called Kibble-Zurek mechanism.
IME Distinguished Colloquium Series - Prashant KamatProfessor Prashant Kamat from University of Notre Dame will speak as part of the IME Distinguished Colloquium Series.
Event will be followed by a reception from 5 pm to 6 pm at ERC in IME’s 2nd floor lounge/atrium area
Peizhi Du, Maryland University
Hybird seesaw leptogenesis and TeV singletsThe appealing feature of inverse seesaw models is that the neutrino mass emerges from the exchange of TeV scale singlets with sizable Yukawa couplings, which can be tested at colliders. However, the tiny Majorana mass splitting between TeV singlets is left unexplained. Moreover, we argue that these models suffer from a structural limitation that prevents a successful thermal leptogenesis if Yukawa couplings are unsuppressed. In this talk, I will introduce a hybrid seesaw model, where we replace the mass splitting with a coupling to a high scale seesaw module including a TeV scalar. I will show that this structure achieves the goal of filling both the above gaps with couplings of order unity. The necessary structure automatically arises embedding the seesaw mechanism in composite Higgs models. Our hybrid seesaw models have an interesting interplay between high scale and TeV scale physics in leptogenesis and enlarges the range of allowed high scale singlet masses.
Andrew Ferguson, University of Chicago
Machine learning design of self-assembling colloidal crystals and inference of protein folding funnelsData-driven modeling and machine learning have opened new paradigms and opportunities in the understanding and design of soft and biological materials. Colloidal particles with tunable anisotropic surface interactions are of technological interest in fabricating responsive actuators, biomimetic encapsulants, and photonic crystals with omnidirectional band gaps. In the first part of this talk, I will describe our applications of nonlinear manifold learning to determine low-dimensional assembly landscapes for self-assembling patchy colloids. These landscapes connect colloid architecture and prevailing conditions with emergent assembly behavior, and enable inverse building block design by rational sculpting of the landscape to engineer the stability and accessibility of desired aggregates. Rational engineering of structural and functional polymers and proteins requires an understanding of the underlying free energy landscapes dictating thermodynamic stability and kinetic folding pathways. In the second part of this talk, I will describe an approach integrating ideas from dynamical systems theory and nonlinear manifold learning to reconstruct multidimensional protein folding funnels from the time evolution of single experimentally-measurable observables.
Lee Lecture: Professor Susumu Kitagawa, Kyoto University
Chemistry and Application of Soft Porous PCP/MOFe have found unique porous properties of PCPs/MOFs, which possess flexible or dynamic porous frameworks, reversibly responding to external stimuli, not only chemical but also physical. They were developed in an effort to realize dynamic porous and collective functionality not found in conventional materials. Their compositions of metal ions and organic molecules have achieved diversity in the electronic states. That is, the spatial and electronic structures can be altered, realizing magnetic and dielectric properties as well as oxidation− reduction functions. Besides normal storage, such MOFs have vast potential for separation with an extremely high selectivity, high-efficiency storage, and catalysis, as well as sensing and actuator functions. For these reasons, many studies investigate these materials. In this lecture, I discuss porous materials with capabilities that exceed current ones and the future research direction.
Jessica M.J. Swanson, The University of Chicago
Unraveling Multistep Kinetic Mechanisms Behind Coupled Ion Exchange: A Case Study on Cl-/H+ Exchangein ClC AntiportersUnderstanding complex mechanisms such as transmembrane ion exchange by proteins in molecular, thermodynamic, and kinetic detail remains a significant challenge. In this talk, I will present a new approach to integrate experimental and simulation data to fully characterize Cl–/H+ exchange in ClC antiporters. Rate coefficients are first calculated with reactive and polarizable molecular dynamics simulations and then optimized within a coupled kinetic (Markov state) model to reproduce experimental data. This produces a set of solutions that not only predict new properties but also reveal insight into the series of transitions that define the mechanism, the molecular origin of the unusual 2.2:1 Cl–/H+ stoichiometry, and the influence of protein orientation. I will explain how the consistent exchange ratio is a consequence of kinetic coupling and how the lack of large protein conformational changes suggests a more facile evolutionary connection between chloride channels and more evolved antiporters. Finally, I will discuss how an ensemble of different stochastic exchange pathways, as opposed to a single series of distinct transitions, culminates in the macroscopic observables and thereby helps to explain the underlying molecular mechanism.
Lee Lecture: Professor Susumu Kitagawa, Kyoto University
Porous Coordination Polymers/Metal Organic FrameworksPermanent porosity for coordination networks in solids was discovered and demonstrated with gas sorption experiments (1997), whose materials are now known as porous coordination polymers (PCPs) or metal-organic frameworks (MOFs). They are an emerging class of microporous solids combining the modularity of inorganic structural building units (nodes) with organic ligands (linkers) that can be tailored through organic synthesis. This particular combination of designability and the structural porosity of MOFs has led to explosive growth in their application to gas storage/separation, catalysis, ion conductivity, chemical sensing, and drug delivery systems. To date, MOFs are classified as a new category of porous materials, as opposed to the conventional classifications of inorganic and carbon materials. Researchers in the world synthesized a wide variety of MOFs and developed the comprehensive structural chemistry. We have developed the chemistry of coordination space, focusing on functionalities, and discovered flexible MOFs (soft porous crystals) which to date are another dimension of porous materials.
MOFs have been extensively researched in both academia and industry. Industrial syntheses are rapidly advancing. Researchers in both academia and industry are producing MOFs materials for use in purification, storage, transportation, and conversion, vital to addressing energy and environmental issues and contributing to human welfare.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Dr. Christa Flühmann, Department of Physics, ETH Zurich
An Encoded Qubit in a Trapped-ion OscillatorI will present recent experiments demonstrating a qubit encoded in the harmonic motion of a single trapped 40Ca+ ion . The usage of the oscillator allows to study a logical qubit with a single quantum system, while in contrast commonly used error-correction schemes are based on arrays of many physical qubits. The approximate logical code states are formed from a periodically spaced superposition of displaced squeezed components, which has theoretically been shown to have optimal performance for a large set of errors [2, 3]. Our first time demonstration of these qubits is based on coupling the ion motional oscillator to an internal state ancillary qubit, which we can subsequently readout. This indirect readout of the oscillator via the ancillary qubit we have previously interpreted as a modular position or momentum measurement and explored the relations between sequences of these measurements . Such sequences allow us to create the logical codes states as well as measure their spatial and momentum probability densities, revealing the non-local features simultaneously present in both densities. Using the modular measurements we further implement logical state readout in the Pauli basis which we demonstrate on the six cardinal states of the Bloch sphere for which we reach an average square fidelity of 87.3 ± 0.7%. We implement the logical Pauli gates by displacements of the oscillator and realize arbitrary single qubit operations by modifying the modular measurements slightly. We analyze the performance of a universal single logical qubit gate set by performing process tomography, for Pauli gates we reach process fidelities of ≈ 97%, while for continuous rotations we achieve fidelities of ≈ 89%.
MRSEC Lunch 'n Learn Workshop
HORIBA Duetta Fluorescence and Absorbance SpectrometerCome see the worlds’ fastest 2 in 1 Fluorescence and Absorbance Spectrometer
A Game Changing Spectrometer Concept
• UV-Vis-NIR Fluorescence Detection Wavelength Range from 250 to 1,100 nm
• Full 3-D Fluorescence EEM Acquisition in Less Than One Second
• Best in Class Fluorescence Sensitivity Specification of 6,000:1 RMS for Water Raman
• Automatic Correction for Primary
and Secondary Inner Filter Effects (IFE)
• High Fidelity Molecular Fingerprinting with Unique A-TEEMTM
(Absorbance-Transmittance Excitation Emission Matrix) Technology
• Millisecond CCD Detection of Entire Fluorescence Spectrum
Equity, Diversity and Inclusion
Paul Oehlmann, Virgina Tech
Gauged Superconformal matter from exotic F-theory fibrationsWe consider 6 dimensional supergravity theories coupled to gauged superconformal matter. The physics is extracted from F-theory on smooth torus fibered Calabi-Yau threefolds. The superconformal matter resides at points in the base of the fibration that are either smooth, in the case of (1,0) superconformal matter, or orbifold singularities in the (2,0) case.
Smoothness of the the full geometry implies exotic fiber behavior over those points
such as non-flat and multiple fibers that we analyze in detail. The topology of those
fibers and the full geometry allows an interpretation for the superconformal matter which
can be verified by analyzing their deformation spaces.
Shinsei Ryu, University of Chicago
Topology and entanglement detected by partial transposeQuantum many-body systems exhibit very rich phenomena unexpected from their classical counterparts. In this talk, I will focus on a quantum information theoretical operation -- partial transpose -- which is useful in detecting quantum entanglement. I will describe how partial transpose can be used to detect topology and entanglement in quantum many-body systems, ranging from topological phases of condensed matter to systems which have holographic dual descriptions. In particular, I will describe the constructions of topological invariants using partial transpose, and possible holographic dual objects corresponding to entanglement negativity, which is an quantum entanglement measure constructed by using partial transpose.
Omrie Ovdat, Technion
Vacancies in Graphene: Dirac Physics and Fractional Vacuum ChargesSignificant interest has lately been devoted to the study of vacancies in graphene obtained by removing a neutral carbon atom. The presence of a single vacancy has interesting and unexpected consequences. It leads to the occurrence of a stable charge of order unity localized at the vacancy site and interacting with other charges of the conductor by means of an Coulomb potential. It also breaks the symmetry between the two triangular graphene sublattices hence inducing zero energy states at the Dirac point. These features have been noticed, however, their precise underlying mechanism and its relation to Dirac physics, if any, are yet to be investigated. Here we show the fractional and pseudo-scalar nature of this stable vacancy charge originating from the vacuum and insensitive to screening effects. A continuous Dirac model is presented which relates zero modes to vacuum fractional charge and to parity symmetry breaking. This relation, constitutes an Index theorem and is achieved by using particular chiral boundary conditions, which map the vacancy problem onto edge state physics and link zero energy states to topological features of the bulk alike the Hall effect or physics of kinks, vortices and monopoles. Vacancies in graphene thus allow to realize prominent features of $2+1$ quantum electrodynamics, e.g., charge fractionalization and parity breaking, but without coupling to a gauge field.This essential difference makes vacancy physics relatively easy to implement and an interesting playground for topological charge switching.
JFI Tuesday Seminar - Prof. Jean Dalibard - College de France
Topological Protection in Quantum GasesHow can one classify the states of matter? Beyond well-known
arguments based on geometrical symmetries, the application of concepts
originating from topology is currently leading to fascinating
developments. These concepts were initially proposed in condensed matter
physics in order to describe the Quantum Hall effect, and they are now
spreading over many fields of research, notably in atomic physics and
optics. In this lecture, I will present some robust properties that
characterize topological matter formed with atomic gases, which persist
when one modifies the system parameters or add some disorder. I will
also explain how these concepts can lead to novel devices that take
advantage of topological robustness. Host: Cheng Chin, 2-7192 or via email to email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Nathan Seiberg, IAS
Recent advances in 2+1d QFTWe will review recent developments in the study of quantum field theory in 2+1 dimensions. Newly discovered subtleties in the analysis of the short distance behavior of these theories have uncovered surprising properties. They help motivate a rich web of conjectures about the long distance behavior of these systems. These conjectures describe new phases and new phase transitions between them. Also, in many cases these transitions have several different dual descriptions. These new developments were motivated by ideas in high energy physics, string theory, and condensed matter physics. And they have potential applications in these fields.
Chemistry Colloquium: Professor Masaru Kuno, University of Notre Dame
Single Semiconductor Nanostructure Extinction SpectroscopyThere has been thirty years of emission-based single particle microscopy and spectroscopy since Moerner’s seminal single molecule study. While highly successful in revealing the properties of matter hidden by ensemble averages, the limits of emission-based microscopies have now become apparent. To address recognized future needs and, in particular, the need to go beyond fluorescent specimens, single particle extinction techniques have been developed. Motivating this has been the desire to acquire information about the electronic structure of nanoscale materials difficult to obtain otherwise using either ensemble or emission-based single particle measurements. Circumstances where single particle extinction measurements offer superior alternatives to traditional microscopies/spectroscopies include situations where the material of interest is non-emissive or where current syntheses yield ensembles with large size and/or compositional distributions that hide the underlying spectral response of a material. Most relevant, though, are cases where information about the underlying electronic structure of a material -something directly encoded in its absorption- is less forthcoming and is at best inferred indirectly using emission-based approaches.
This talk describes the inherent problems associated with measuring the extinction of low dimensional semiconductors. It simultaneously describes the fundamental operating principles of two common extinction techniques while highlighting their achievements. It then reviews what exactly we have learned about the fundamental physics of CdSe, a model semiconductor nanosystem. The talk ends by describing the future development of new single particle extinction methodologies such as infrared photothermal heterodyne imaging.
Inorganic/Organic Seminar: Professor Keary Mark Engle, The Scripps Research Institute
Catalytic Methods for Selective Functionalization of C–C π-BondsVicinal (1,2-disubstituted) functional group motifs are ubiquitous in structurally complex small molecules that are of academic and industrial importance, including many widely used pharmaceutical agents. Many such functional group combinations, however, remain exceptionally challenging to synthesize. The goal of research in the Engle lab is to develop a general catalytic platform for alkene and alkyne difunctionalization to introduce a diverse array of functional groups at each of the two carbon atoms in a programmable fashion. Our central hypothesis is that is that coordination of a π-Lewis acidic metal, such as palladium(II), to the alkene will promote nucleophilic attack and that the resultant organometallic species can be trapped with an electrophile to furnish the desired 1,2-difunctionalized product. In the overall net transformation, one of the two new functional groups is introduced in the form of a nucleophile, and the other in the form of an electrophile. Directing groups are used to control the regiochemical course of the reaction and stabilize key alkylmetal intermediates. These concepts have been used to expand the synthetic toolkit to include new retrosynthetic disconnections, including “homo-Michael” addition and β,γ-vicinal dicarbofunctionalization of alkenyl carbonyl compounds.
David Schimitz, University of Chicago
Neutrino Physics at Long and Short Baselines: The DUNE and SBN Experiments at FermilabThe study of neutrinos over the past 60 years has revealed an incredible amount about the Standard Model of elementary particles, despite neutrinos being one of the most challenging areas of exploration in particle physics. This combination, a seeming contradiction, motivates continued experimental effort at a grand scale to reveal the neutrinos’ further secrets. One of the global centers of neutrino physics research is at Fermilab, forty miles west of campus, which hosts the future Deep Underground Neutrino Experiment, DUNE, and the ongoing Short-Baseline Neutrino experiment, SBN. In this talk, I will review some of the biggest past discoveries in neutrino physics and preview the exciting future ahead with these new experiments at unprecedented scales and with world-leading reach for new discoveries.
Xiao Chen, KITP, UC Santa Barbara
Operator dynamics and quantum chaos: an approach from Brownian circuitOperator scrambling is a crucial ingredient of quantum chaos. Specifically, in the quantum chaotic system, a simple operator can become increasingly complicated under unitary time evolution. This can be diagnosed by various measures such as square of the commutator (out-of-time-ordered correlator), operator entanglement entropy etc. In this talk, we discuss operator dynamics in three representative models: a 2-local spin model with all-to-all interaction, a chaotic spin chain with long-range interactions, and the quantum linear map. In the first two examples, we explore the operator dynamics by using the quantum Brownian circuit approach and transform the operator spreading into a classical stochastic problem. Although the speeds of scrambling are quite different, a simple operator can eventually approach a "highly entangled" operator with operator entanglement entropy taking a volume law value (close to the Page value). Meanwhile, the spectrum of the operator reduced density matrix develops a universal spectral correlation which can be characterized by the Wishart random matrix ensemble. In contrast, in the third example (the quantum linear map), although the square of commutator can increase exponentially with time, a simple operator does not scramble but performs chaotic motion in the operator basis space determined by the classical linear map. We show that once we modify the quantum linear map such that operator can mix in the operator basis, the operator entanglement entropy can grow and eventually saturate to its Page value, thus making it a truly quantum chaotic model.
Special Seminar: Professor Li Deng, Brandeis University / Westlake University
Activation of Nucleophiles for Asymmetric Reaction with Organic MoleculesOrganic molecule-mediated selective catalysis (i.e. selective organocatalysis) has evolved into a generally applicable, powerful strategy for asymmetric synthesis over the past few years. This lecture will present synthetic and mechanistic studies focusing on the development of weak-bonding organocatalysis directed towards the activation of nucleophiles for realizing asymmetric transformations of synthetic importance.
Marija Vucelja, University of Virginia
Adaptation of a bacterial population and the adaptive immune system of bacteria with CRISPRThe CRISPR (clustered regularly interspaced short palindromic repeats) mechanism allows bacteria to defend adaptively against phages and other invading genomic material. The CRISPR machinery acquires short genomic sequences from the "invaders" and in this way builds up a memory of past infections. With a new encounter of an invading sequence, this memory is accessed, and in a successful outcome, the invader is neutralized. I will introduce a population dynamics model where immunity can be both acquired and lost. I will describe the predictions of this model and suggest experiments.
Adaptation, where a population evolves increasing _x000C_fitness in a fixed environment is often thought of as a hill climbing process on a _x000C_fitness landscape. With a fi_x000C_nite genome, such a process eventually leads the population to a _x000C_fitness peak, at which point _x000C_fitness can no longer increase through individual beneficial mutations. Instead, the ruggedness of typical landscapes due to epistasis between genes or DNA sites suggests that the accumulation of multiple mutations can allow the population to continue increasing in _x000C_fitness. By using a spin-glass type model for the _x000C_fitness function that takes into account microscopic epistasis, we _x000C_find that hopping between metastable states can mechanistically and robustly give rise to a slow, logarithmic average _x000C_fitness trajectory.
IME Distinguished Colloquium Series - Arup ChakrabortyProfessor Arup Chakraborty from Massachusetts Institute of Technology will kick off the IME Distinguished Colloquium Series with an hour-long talk.
1st Tuesday Colloquium - Prof. David DeMille, Yale University
Diatomic Molecules as Quantum ToolsOur group is pursuing a wide range of physics goals, by applying techniques of modern atomic physics to the more complex system of diatomic molecules. For example, we use the strong electric field inside a polar molecule to amplify the observable effect from an electric dipole moment (EDM) of the electron, a CP-violating effect predicted in many extensions to the Standard Model of particle physics. We recently set a new upper limit on the electron EDM, placing severe bounds on many models of new physics at the TeV energy scale. In parallel, our group has developed the first methods for laser cooling and trapping of molecules. These techniques will enable interesting new frontiers in quantum many-body physics and quantum chemistry, as well as next-generation EDM searches. Host: Cheng Chin, 2-7192 or via email to email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Tobias Walther, PhD, Harvard
The Phase of Fat: Mechanisms & Physiology of Lipid Storage
Stuck Inside a Protein With the Deformation Blues AgainNoon is when we eat and laugh and talk
12:15 is when the subject is revealed
Dr. Quentin Ficheux, Ecole Normale Superieure
Dynamics of a Qubit while Simultaneously Monitoring its Relaxation and DephasingMeasuring a spin-1/2 along one direction projectively maximally randomizes the outcome of a following measurement along a perpendicular direction. Here, using either projective or weak measurements, we explore the dynamics of a superconducting qubit for which we measure simultaneously the three components x, y and z of the Bloch vector.
The x and y components are obtained by measuring the two quadratures of the fluorescence field emitted by the qubit. Conversely the z component is accessed by probing an off-resonant cavity dispersively coupled to the qubit. The frequency of the cavity depends on the energy of the qubit and the strength of this last measurement can be tuned from weak to strong in situ by varying the power of the probe.
In this experiment, the tracked system state diffuses inside the Bloch sphere and performs a random walk whose steps obey specific rules revealing the backaction of incompatible quantum measurements. The associated quantum trajectories follow a variety of dynamics ranging from diffusion to Zeno blockade. Their peculiar dynamics highlight the non trivial interplay between the backaction of the two aforementioned incompatible measurements.
Frontiers of Molecular EngineeringJoin us in Chicago to discover how molecular engineering approaches are driving significant breakthroughs across a broad range of research disciplines and applications, from batteries to biotechnology, and learn of the key challenges for the future. Attendees will be exposed to the current state of the art across diverse areas of research, with an emphasis on the development of an interdisciplinary approach.
This two-day symposium is supported by Molecular Systems Design & Engineering, The Institution of Chemical Engineers (IChemE), the National Science Foundation (NSF), and the Institute for Molecular Engineering at the University of Chicago.
The programme will feature invited speakers plus a poster session.
Topics will include:
Energy storage and conversion
Computational material design
Capture and separations technologies
Assembly of soft and biological materials
Machine learning and data science in material design
Lorenz Eberhardt, ETH
Holography on AdS3xS3xS3xS1 and stringy AdS3 spectraThe purpose of the talk is twofold. I will first report on progress made on the problem of finding a holographic dual of the large N=4 background AdS3xS3xS3xS1. I will discuss the BPS spectrum of the background in detail, both from a string theory and a supergravity point of view. This allows us to make a proposal for the CFT dual, at least for specific values of the fluxes.
In a second part of the talk, I will discuss the string theory spectrum on AdS3 backgrounds away from the pure NS-NS flux point, where a WZW description of the worldsheet theory exists. The theory with R-R flux can be described in the hybrid formalism by a sigma-model on a supergroup coupled to ghosts. I will explain how to solve this sigma-model in the plane-wave limit and reproduce the plane-wave spectrum from the hybrid formalism
Professor Yoon-Young Kim, Seoul National University
Total Longitudinal-Transverse Mode Conversion through Anisotropic Elastic MetamaterialsProfessor Yan Yoon’s research is focused on elastic metamaterials and mechanics-based design and optimization. His research has been recognized with many awards including, most recent awards, Seoul National University Award for Academic Excellence (2017), KSCM (Korean Society for Computational Mechanics) Computational Mechanics Award (2017), APACM (Asian-Pacific Association for Computational Mechanics) Award for Computational Mechanics (2016), and ASSMO (Asian Society for Structural and Multidisciplinary Optimization) Award (2016). He has also given a number of keynote/plenary lectures in international conferences, including recent plenary lectures at the World Congress of Computational Mechanics (2016), World Congress of Structural and Multidisciplinary Optimization (2017) and the International Conference on Emerging Technologies in Mechanical Engineering (2018).
Elastic waves in solids carry both longitudinal and transverse waves. The particle motions in the longitudinal and transvere modes take place along the parallel and perpendicular directions to the direction of propagation, respectively. Their propagation speeds are also different due to the difference in their impedances. Therefore, no longitudinal (transverse) mode can be totally converted to the transverse (longitudional) mode unless the wave propagation direction is allowed to alter. Here, we show that the unidirectional total mode conversion from the longitudinal mode to the transvese mode (and vise versa) is possible if our elaborately designed anisotropic metamaterial converter is used. As a critical application of the discovered phenomenon of total mode conversion that is enabled by a metamaterial, we will present new-generation ‘ultrasonic non-invasive flow sensors’ that clamp to the outside of a fluid-flowing pipe. We will show how the new sensors can overcome the technical limiations of currently available flow sensors.
Prof. Yoon led the National Creative Research Initiatives Centers designated by the Korean Ministry of Science and Technology from 2002 to 2011. He was the President of the KSME (Korean Society of Mechanical Engineers) and is the President of the KSCM (Korean Society for Computational Mechanics). He is also a Vice-President of the ISSMO (International Society of Structural and Multidisciplinary Optimization) and the President of the ASSMO (Asian Society of Structural and Multidisciplinary Optimization). He (has) served as editors in several international journals. He is a member of KAST (Korean Academy of Science and Technology) and a member of NAEK (National Academy of Engineering), Korea. He also works as advisory professors for Samsung Electronics, Samsung Advanced Institute of Technology, and SEMES. He also (has) served as an international board member of KTH (Royal Institute of Technology, Sweden), an external review member of University of Tokyo, RACE, and a foreign review member of Beijing Institute of Technology, the Mechanics Program.
David McGady, Niels Bohr International Academy
Path integrals, finite temperature, and latticesSurprisingly, partition functions for some model systems in statistical mechanics are invariant under formally reflecting the sign of temperature, T: +T -> -T. We call this T-reflection invariance. Clearly, partition functions for generic statistical systems cannot be invariant under T-reflection. However, in this talk we focus on finite-temperature path integrals and give a general picture for why finite-temperature path integrals in quantum field theory *should* behave well under T-reflection. We probe this general picture in the context of the harmonic oscillators (in one-dimension) and in conformal field theories on the two-torus (in two-dimensions) and in the mathematics of modular forms. We find that the relevant path integrals are often invariant only up to overall T-independent phases, which could be naturally interpreted as new anomalies under large coordinate transforms.
Special Seminar: Professor Thomas Teets, University of Houston
Synthetic Strategies to Optimize Photophysical and Photoredox Properties of Organometallic ComplexesThis talk describes complementary synthetic approaches to control and enhance the excited-state properties of organometallic complexes. Bis-cyclometalated iridium complexes have emerged as champion compounds in a number of applications requiring efficient phosphorescence and excited-state redox chemistry. Outstanding challenges include the design of compounds with efficient, stable blue luminescence, and overcoming the typically poor photoluminescence quantum yields of red to near-infrared-emitting complexes. Our efforts have resulted in new designs for robust blue-emitting complexes, using strongly σ-donating acyclic diaminocarbene supporting ligands. These complexes are prepared by unconventional routes relying on the electrophilic reactivity of coordinated isocyanides. In a separate effort, we have employed nitrogen-containing, π-donating ancillary ligands in the development of new bis-cyclometalated iridium complexes which are efficient red and near-infrared phosphors or potent photoreductants. And finally, a more recent thrust in our group has produced a modular self-assembly strategy to prepare multi-chromophore arrays featuring cyclometalated iridium, providing easy access to a class of supramolecular constructs which are rich platforms for studying fundamental aspects of excited-state dynamics and may function as ratiometric environmental sensors.
Anomalous subdiffusion of highly-charged, membrane-covered nanoparticlesmunch bites: 12:00
Crunch bytes: 12:15
Mind the gap: Fluctuations as a mechanism for thickness selectionEat at noon. Talk at 12:15
My simulated discontinuous shear thickening---a first-order transition?Eat: noon
Closs Lecture: Professor Jin-Quan Yu, The Scripps Research Institute
Enantioselective and Remote C-H Activation Reactions
Professor Yu Zhao, National University of Singapore
Catalytic Enantioselective Redox-Neutral Processes for Efficient Chemical SynthesisThe development of economical and selective catalytic processes is essential for the promotion of sustainable chemical synthesis. My research group at National University of Singapore focuses our efforts on the development of catalytic enantioselective redox-neutral transformations to access valuable chiral building blocks in organic synthesis. Such methods have the significant advantage of circumventing the redundant oxidation/reduction steps to reduce waste production in chemical synthesis. In particular, the stereo-convergent preparation of chiral amines and N-heterocycles from readily available racemic alcohols through borrowing hydrogen, and new processes of enantioselective isomerization of alkenyl alcohols will be discussed in details.
Bacteria communication on a glowing film?Eat: 12:00
We learn from papers, but what can paper learn?Meet, eat 12:00
Brainy meat 12:15
NAMBU,FANO AND MY FIRST MARCH MEETING ABSTRACT
by regular participant James E. ClarkBring food at 12:00
Talk begins at 12:15
Tuan Tran, Nanyang Technological University
Critical conditions for jumping of electrowetting dropletsA droplet resting on a solid surface stretches further with an applied electric field. Turning off the field, the droplet pulls back to its initial state and may jump up from the surface against gravitational force. In this study, we ask and attempt to answer a simple question: What is the condition for such droplets to detach from the surface? We found that the key factors of jumping condition include the friction and pinning effect at the contact line. The friction at the contact line is responsible for most of the viscous dissipation, while contact line pinning acts as an energy barrier to prevent detachment. We propose a simplified model capturing these effects in the jumping condition and provide an experimental validation to the model. The results highlight the crucial role of contact line dynamics in dynamical wetting phenomena.
Dr. Abhinendra Singh, City College of New York
Towards a General Constitutive Model of Dense Frictional SuspensionsThe mechanism of shear thickening in dense suspensions has been shown to be consistent with a transition from lubricated rheology, where close interactions between suspended particles take place through a thin liquid film, to a frictional rheology, wherein particles experience frictional contacts. Particle simulations that led to this concept have been successful in quantitatively reproducing the non-Newtonian shear behavior of discontinuous shear thickening suspensions .
As a step towards developing a constitutive model for such materials, we extend the method presented by Wyart-Cates  for lubricated and frictional rheologies that is applicable to both shear and normal stresses for non-colloidal suspensions and demonstrate the agreement between such a model and the simulation results . Through this approach we develop a flow-state map of this material.
The challenge of extension of this framework for constitutive modeling of colloidal suspensions remains. In order to guide the efforts to tackle this challenge, we examine the role of cohesive forces on the shear rheology of colloidal suspensions. This is achieved through the inclusion of interparticle repulsive and cohesive forces in addition to hydrodynamic and frictional forces that have been present in our particle simulations . These simulations at low to intermediate strength of cohesion show yield stress at low stress, followed by shear thinning and eventual shear thickening at high values of stress. For high strength of cohesion shear thickening is obscured. Including the details about yield stress and shear thinning, an extension to the shear thickening model to cohesive non-Brownian dense frictional suspension is proposed.
cell networks that won't make your skin crawlBring food 12:00
Eun-Gook Moon, KAIST, Korea
Topological defects and phase transitions in 2D correlated systemsThe Landau paradigm of phase transitions is one of the backbones in critical phenomena. With a Z2 symmetry, it describes the Ising universality class whose central charge is one half (c = 1/2) in two spatial dimensions (2D). Motivated by recent experiments in strongly correlated systems, which show possibilities beyond the Landau paradigm, we propose an exotic universality class of a Z2symmetry breaking transition with c=1. We argue that controlling topological defects may realize the exotic class. In addition to novel critical exponents, we find that the onset of an order parameter may be super-linear in contrast to the sub-linear onset of the Ising class. We argue that a super-linear onset of a Z2 order parameter without breaking a bigger symmetry than Z2 is evidence of exotic phenomena, and our results are applied to recent experiments in phase transitions at pseudo-gap temperatures. If time allows, we discuss topological phase transitions in Kitaev quanatum spin liquids and their signals
Professor Kazuaki Ishihara, Nagoya University
Rational Design of High Performance Catalysts on Acid-Base Combination Chemistry
You CAN teach an old foam new tricks
come and see how12:00 the seance, with eating
12:15 the main event
2018 Science@theInterface Symposium
Microscopy: Advances and ApplicationsSession 1
10:30-11:30 Joerg Bewersdorf, PhD, Yale University
3D and Multicolor Live-cell Super-resolution Microscopy for Cell Biological Research
11:30-12:00 Marco Allodi, PhD, University of Chicago
Optical Resonance Imaging: an Optical Analog to MRI for Widefield Ultrafast Imaging
12:45-1:45 Sara Abrahamsson, PhD, University of California, Santa Cruz
Multi-Focus SIM development for studying transcription and chromatin dynamics
1:45-2:45 Aydogan Ozcan, PhD, University of California, Los Angeles
Deep Learning-enabled Computational Imaging
3:00- 3:30 Xiaolei Wang, PhD, University of Chicago
3D single insulin granule tracking reveals anisotropic dynamics in Beta cells
3:30-4:30 Fei Chen, PhD, Broad Institute
From cells to tissues: Tools for understanding in situ tissue organization
JFI Presents - "Women in Chemistry" -Francesca Serra, John Hopkins University
Liquid Crystals for Self-AssemblySoft materials are a promising tool to explore controllable energy landscapes. Liquid crystals, in particular, combine reconfigurability, unique optical properties and the possibility of directing their self-assembly via the bounding surfaces. These fluids with long-range orientational order possess elastic energy and can generate topological defects, two useful tools for assembly. I will show two examples of interplay between liquid crystal confinement and control of assembly. In one setting, microparticles can be precisely directed to desired locations by modulating the orientation of nematic liquid crystals using topography. An undulated boundary generates small elastic distortions in liquid crystals that can precisely direct the motion of colloidal particles and induce a transformation of the topological defect associated to the particle. In my second example, an array of topological defects in nematic liquid crystals is generated by applying an electric field and it is made regular by appropriate patterning of the electrodes. The defect array can thus form a square lattice of defects, regular over several millimeters, and ideal to create tunable optical gratings. For further information please contact the Host, Sara Zinn via email at email@example.com. Persons who has a disability and may need assistance please contact Brenda Thomas at 2-7156 or firstname.lastname@example.org. Hosted by Women in Chemistry (WIC)
Funded in Part by Student Government
Stephanie Palmer, The University of Chicago
Driving creepy repulsive flow
(with movies)Eat 12:00 (before movies)
Prof. Zhi Ping (Gordon) Xu, University of Queensland
Tailoring Inorganic Nanoparticles for Efficient Cancer Therapy and ImagingI will first introduce two types of inorganic nanoparticles, i.e. layered double hydroxide (LDH) and lipid-coated calcium phosphate (LCP) nanoparticles, and then demonstrate their high potential as the drug/gene delivery platforms. I will present a few examples to show efficient co-delivery of functional small interfering RNA (siRNA) and anti-cancer drug to cancer cells for the synergic inhibition. I will also talk about our recent results for target delivery of siRNA to treat cancers.
In the second part, I will present our recent research using clay nanoparticles as vaccine adjuvants to promote higher and long-term immune responses against cancer and bacteria. We have noted that LDH is able to readily load model antigen ovalbumin (OVA) and the toll-like receptor ligand CpG together, promote higher levels of specific antibodies, and modulate the immune response from Th2 bias towards the preferred polarity Th1 for anti-cancer purpose. We have found that LDH and hectorite (HEC) nanoparticles as adjuvants to promote stronger and long-lasting immune responses against the infectious bacteria.
In the final part, I will demonstrate the capability of inorganic nanoparticles as positron emission tomography (PET) and magnetic resonance imaging (MRI) contrast agents for cancer imaging and detection.
Andrei Tokmakoff, University of Chicago
The Ultrafast Structural Dynamics of Protons in Liquid WaterAs omnipresent as liquid water is, we still struggle to understand its chemistry at a molecular scale. It is not just a solvent but its rapidly
changing network of hydrogen bonds shapes and changes solutes within it. The conceptual and technical challenges of studying such problems are nowhere more apparent than when investigating the transport of an excess proton in water, since it is only distinguishable as an excess charge imbedded in the liquid. Proton transfer in water has long been attributed to a sequential displacement of protons along a chain of hydrogen bonds, but there is little experimental evidence to describe the solvation structure of this charge defect and how it changes in charge transfer. I will describe research being performed to visualize the molecular dynamics of excess protons in liquid water using new techniques in ultrafast 2D IR spectroscopy.
Raghu Mahajan, IAS, Princeton
The Conformal Bootstrap at Finite Temperature
Dr. Reatha Clark King
Distinguished Alumna LectureDr. Reatha Clark King received her early education in a one-room schoolhouse at Mt. Zion Baptist Church. After graduating as valedictorian of Moultrie High School for Negro Youth, she attended Clark College in Atlanta on scholarship, where she earned a double BS in chemistry and mathematics. A Woodrow Wilson Fellowship brought her to the University of Chicago for her MS in Chemistry, which she obtained in 1960. She remained for her PhD under Ole Kleppa, graduating in 1963 with a thesis titled “Contributions to the Thermochemistry of the Laves Phases.” Dr. King then became the first female African American research chemist at the National Bureau of Standards, where she won the Meritorious Publication Award for a paper on fluoride flame calorimetry. In 1968, Dr. King joined York College (CUNY) as a faculty member, eventually becoming associate dean for the Division of Natural Science and Mathematics and associate dean for academic affairs. She earned an MBA from Columbia College during a sabbatical. In 1977, Dr. King became president of Metropolitan State University in Minneapolis. Her eleven-year tenure in this position is remembered for substantial expansion of the college, as well as increased recruitment of women and minorities. Following a stellar career in research and academia, Dr. King spent the next fourteen years in industry as vice president of General Mills Corporation and President/Executive Director of General Mills Foundation. She has served on the boards of several corporations and nonprofit organizations, including Exxon Mobil, H. B. Fuller, Wells Fargo, Allina Health Systems, and American Council on Education, and has been a trustee of Clark Atlanta University, Carleton College, and the University of Chicago. She has received many awards, including the Defender of Democracy Award from the Martin Luther King, Jr. National Memorial Project Foundation, National Association of Corporate Directors Director of the Year, Exceptional Black Scientist Award from CIBA-GEIGY, International Citizen Award from the International Leadership Institute, Louis W. Hill, Jr. Fellowship in Philanthropy, and Ebony Magazine’s Top 50 Black Executives in Corporate America. She has been inducted into the Delta Sigma Theta sorority for public service and recognized with 14 honorary doctorate degrees.
Thomas Faulkner, The University of Illinois, Urbana-Champaign
Why is negative energy density bad, and how does quantum information constrain itNegative energy density can arise naturally in Quantum Field Theory, the theoretical framework with which we describe fundamental particle physics and the matter which makes up our universe. However too much negative energy density can lead to pathologies when considering the dynamics of spacetime in which this matter resides. This dynamics is governed by Einstein’s equations which relates such energy densities to the curvature of spacetime. In this talk I will discuss conjectured bounds on negative energy density and sketch very recent general proofs of these bounds. The methods we use combine causality considerations with concepts taken from the study of quantum information.
The Tuesday JFI Seminar - Prof. Yan Yu, Department of Chemistry, Indiana University
Spatially Organizing Biointerfaces to Interrogate Immune FunctionsThe immune system functions on the basis of intricately organized chemical reactions and physical forces. Examples range from the engulfment of invading bacteria that relies on a fine balance of competing mechanical forces, to the activation of T-lymphocytes that requires collective interactions between thousands of receptors at the junction between cells. Owing to the complexity of these processes, understanding immune functions using traditional biological tools is highly challenging. In this talk, I will present my group’s research progress towards designing unique biointerfaces to enable the quantitative understanding and manipulation of immune functions. Our research so far has capitalized on Janus particles, which, like the two-faced Roman god Janus, are made chemically, biologically, optically or magnetically asymmetric. We developed Janus particle-based toolsets for measuring cell dynamics in multi-dimensions beyond translational motion and for spatiotemporally controlling cell functions. Using these methods, we uncovered new dynamics and mechanisms in immune processes, from phagocytosis to intracellular trafficking, which would otherwise be difficult to access with traditional means. For further information please contact Brenda Thomas at 773-702-7156 or via email at email@example.com. You may also contact the Host, Bozhi Tian at 773-702-8749 or via email to firstname.lastname@example.org.
The Academic Job Market
MRSEC presents: A Mini WorkshopPresentation: 10:00 a.m. - 10:45 a.m.
Faculty Panel: 10:45 a.m. - 11:30 a.m.
Grayson L. Jackson, University of Minnesota
Nanoconfined Water and Water-mediated Ion Transport in Model Membrane MaterialsThe ill-defined pore morphologies and connectivities of conventional membrane materials have hampered a clear understanding of the relationship between pore geometry, pore interfacial chemistry, and ultimate membrane performance. Derived from the self-assembly of ionic amphiphiles in concentrated aqueous media, lyotropic liquid crystals (LLCs) are a well-defined materials platform for uncovering these fundamental membrane structure-property relationships due to their monodisperse, sub-3 nm pores decorated with amphiphile headgroup chemical functionalities (Figure 1). Beyond fundamental studies, network (N) phase LLCs are coveted for membrane applications by virtue of their co-continuous aqueous and hydrocarbon domains, yet their non-constant mean curvature interfaces limit their thermodynamic stabilities. In this presentation, I will describe our efforts to understand how pore diameter and interfacial curvature (concave or convex) affects H+ transport in LLCs formed by sulfonate amphiphiles, which unexpectedly reveal that convex nanopores have significantly higher H+ conductivities. Complementary quasielastic neutron scattering (QENS) studies of the confined water dynamics in LLCs with convex nanopores indicate that water diffusion depends sensitively on nanopore geometry and interfacial esults suggest that proton exchange membranes (PEMs) with convex nanopores may exhibit enhanced performances.
Christopher Uyeda, Purdue University
Catalysis at Metal–Metal BondsThe discovery of new catalysts is central to the pursuit of more efficient and sustainable processes in organic synthesis. Whereas mononuclear transition metal complexes have been widely utilized in reaction methodology, the scope of both stoichiometric and catalytic processes for complexes of higher nuclearity is comparatively limited. In principle, multinuclear complexes might engage in unprecedented modes of reactivity by binding substrates or engaging in redox processes that span multiple metal centers. New classes of catalysts that can capitalize on these cooperativity effects have the potential to exhibit activity or selectivity profiles that complement or surpass existing mononuclear systems.
Our group has been developing new platforms that support coordinatively unsaturated and reactive metal–metal bonds. In pursuit of this goal, we have developed a naphthyridine–diimine ligand that was used to prepare dinuclear complexes of mid-to-late first-row transition metals. The redox-active nature of these ligands imparts rich redox chemistry to these complexes, enabling an array of multielectron oxidation and reduction reactions. The applications of these complexes to catalytic processes relevant to organic synthesis will be presented.
Persons with a disability may call (773) 702-0388 in advance for assistance.
Rudolf Grimm, The University of Innsbruck
Impurities in an ultracold Fermi sea: Quasiparticles, phase separation, and moreImpurity physics has emerged as a new branch of research in the field of atomic quantum gases. A central feature is the wide tunability of interactions between the impurities and the surrounding medium. By using magnetically controlled Feshbach resonances, regimes of strong interactions can be reached, which reveal intriguing many-body physics. After a general introduction into the field, I will present our experiments on fermionic and bosonic potassium impurities immersed in a deeply degenerate Fermi sea of lithium atoms. For fermionic impurities, we study the spectrum of quasiparticle excitations and the regime where the Fermi-liquid picture breaks down. Moreover, we observe the formation dynamics of quasiparticles in real time. For bosonic impurities, we observe small-sized Bose-Einstein condensates and, for strong repulsive interactions, their phase separation from the Fermi sea. If time permits, I will also introduce a new quantum gas mixture (dysprosium and potassium) with great prospects for future research on fermionic quantum gases.
Charles M. Lieber, Harvard University
Nanoelectronic Tools for Brain ScienceNanoscale materials enable unique opportunities at the interface between the physical and life sciences, for example, by integrating nanoelectronic devices with cells and/or tissue to make possible bidirectional communication at the length scales relevant to biological function. In this presentation, I will overview a new paradigm for seamlessly merging nanoelectronic arrays and circuits with the brain in three-dimensions (3D). First, the design consideration of matching structural, mechanical and topological characteristics of neural probes and brain tissue will be discussed, thus leading to the new concept of tissue-like mesh electronics. Second, quantitative time-dependent histology studies demonstrating the absence of a tissue immune response on at least a year time-scale, as well as interpenetration of neurons and neurofilaments through the open mesh electronics structures will be presented. Third, uniquely, stable electrophysiology data demonstrating the capability to track and stably record from the will describe several current directions of research, including studies that push the limits of the mesh design paradigm and work focused on fundamental brain science problems, including aging and vision. Finally, the opportunities for future developments will be discussed.
Louise Berben, University of California, Davis
Redox Chemistry of Al(III) Metal-Ligand ComplexesIn this talk I will describe the chemistry of Group 13 metal complexes with redox-active ligands. The synthesis and characterisation of iminopyridine and bis(imino)pyridine complexes of Al(III), Ga(III) and In(III) will be described along with a presentation of their structural and electronic properties. Bis(ligand) complexes of Al, Ga and In are each shown to undergo five reversible electron transfer events and each of the charge states have been structurally characterized. Using techniques including EPR and NIR spectroscopy, we characterized the mixed-valent states for each complex and characterize them as Class III, fully delocalized (Al), and Class II/III (Ga and In). The lowered electronic coupling in complexes of the heavier Group 13 elements arises from involvement of a three-state MV system where the unpaired electron spends more time on the Group 13 ion. The reactivity of the Al complexes will also be discussed in detail, including the mechanisms for ligand-based proton transfer that mediate the activation of polar bonds such as those in alcohols and amines. Dehydrogenation reactions are initiated by the bond activation reactions and these include the conversion of formic acid into CO2 and H2 and the conversion of benzylamine into imine with loss of H2 and NH3. Ligand-based proton and electron transfer is also promoted by various redox active ligands supported by Al. Control of the electrocatalytic mechanism for H2 evolution, based on ligand design, will be described.
Niall M. Mangan, Northwestern University
Identification of Hybrid Dynamical Systems via Clustering and Sparse RegressionInferring the structure and dynamical interactions of complex systems is critical to understanding and controlling their behavior. Hybrid systems are challenging to identify because the parameters and equation structure may change across multiple dynamical regimes. Key examples include varying transmission rates in epidemiological problems and legged locomotion. Many current methods focus on inferring a model for the system and detecting switching points in a time-centric framework. One can reframe the problem by clustering in data-driven coordinates, such that similar dynamical behavior is close together, and then use the sparse identification of nonlinear dynamics (SINDy) method to identify different dynamical regimes. I will discuss model selection using SINDy and information criteria. I will then demonstrate the success of the method hybrid-SINDy on a spring-mass model and a simple infectious disease model with time-dependent transmission rates. I will also investigate robustness to noise and cluster-size.
Debanjan Chowdhury, MIT
Towards a universal description of non-Fermi liquid metals with critical Fermi surfacesNumerous strongly correlated materials display non-Fermi liquid properties over a broad range of temperatures. One of the remarkable features observed in many of these systems is the apparent universality of the phenomenology, in spite of the completely distinct microscopic details. Inspired by the rich phenomenology of such non-Fermi liquids, I will construct examples of translationally invariant solvable models of metals, composed of lattices of Sachdev-Ye-Kitaev dots with identical local interactions. These models display crossovers as a function of temperature into regimes with local quantum criticality and non-Fermi liquid behavior. I will show the existence of sharply defined critical Fermi-surfaces in the non-Fermi liquid regime, that give rise to quantum oscillations in the magnetization as a function of an external magnetic field, in the absence of quasiparticle excitations. I will discuss the implications of these results for fundamental bounds on relaxation rates and speculate on possible coarse grained descriptions of a class of intermediate scale non-fermi liquid behavior in generic correlated metals.
Stefano di Talia, PhD, Duke Medical Center
Cell cycle synchronization in development and regeneration
Valeria Molinero, Univesity of Utah
ce formation in the atmosphere: a molecular perspectiveCrystallization of water in clouds is critical for precipitation and to determine the radiative properties of the atmosphere. Despite decades of research, there are still significant uncertainties in the prediction of the rates of ice nucleation, and about what is the structure of the ice crystals that form under different atmospheric conditions. In this presentation I will discuss our work using molecular simulations and theory to elucidate the microscopic pathways of ice formation, the structure and interfaces of atmospheric ices, and the role of soluble molecules, surfaces, and pores on controlling the rates and mechanisms of ice nucleation.
Harry Gray, Caltech
Living with OxygenHigh-valent iron-oxos are intermediates in biological reactions critical to life on earth, notably including oxygen reduction to water by cytochrome oxidase and steroid oxygenation by cytochrome p450. Jay winkler and i recently discovered that oxygenases and other enzymes that require oxygen for function have chains of tryptophans and tyrosines that extend from active-site regions to protein surfaces. We think it likely that hole tunneling through these trp/tyr chains protects redox enzymes from oxidative destruction.
Sergei Moroz, Technical University Munich
Effective field theory of a vortex lattice in a bosonic superfluidUsing boson-vortex duality, we formulate a low-energy effective theory of a two-dimensional vortex lattice in a bosonic Galilean-invariant compressible superfluid. The excitation spectrum contains a gapped Kohn mode and an elliptically polarized Tkachenko mode that has quadratic dispersion relation at low momenta. External rotation breaks parity and time-reversal symmetries and gives rise to Hall responses. We extract the particle number current and stress tensor linear responses and investigate the relations between them that follow from Galilean symmetry. We argue that elementary particles and vortices do not couple to the spin connection which suggests that the Hall viscosity at zero frequency and momentum vanishes in a vortex lattice.
Mark Lautens, University of Toronto
Improving Efficiency Through Catalytic and Multicatalytic ReactionsOxidative addition and reductive elimination are two fundamental steps common to many different catalytic reactions. Insertion into C-X bonds is particularly prevalent as one of the first steps in a catalytic cycle.
We have been exploring the synthetic potential associated with reversible oxidative addition into carbon-halogen bond and recently developed a palladium catalyzed carboiodination reaction.1 This lecture will describe the scope and limitations of the reaction including recent work that has expanded the scope. 2-3
We have also been exploring the value of combining catalysts and substrates in a multicomponent multicatalyst strategy (MC)2R.4 Recent advances will be presented.
C-H Functionalization remains one of the most active areas of research in organic chemistry.5 We will present our recent advances in this field.
What stops my heavy fluid film from from falling?12:00 time to eat
12:15 time to ponder
Michel Devoret, Yale University
Catching and Reversing a Quantum Jump Mid-flightThe basic phenomenon of quantum jumps between two states of a system driven by a deterministic force while undergoing continuous monitoring is exploited in precision quantum measurements and plays a key role in our fundamental understanding of open quantum systems. Quantum jumps are emblematic of the special nature of randomness in quantum theory. Although it had been argued in the past that their nature is discontinuous, modern measurement theory stipulates that the state of the system evolves continuously during a jump. Even more remakable, in the case of a system possessing at least 3 states, it was shown theoretically that it is possible i) to obtain an advance warning that the jump is about to occur, and consequently ii) to reverse it if was initiated by a coherent drive. We have successfully implemented the indirect QND measurement of a superconducting artificial atom transition from its ground state G to a dark state D by monitoring the occupancy of an auxiliary bright level B connected to G by a Rabi drive. By conditioning the tomography and manipulation of the G-D manifold on the non-occupancy of the B level for a deterministic duration, we catch and even reverse the jump (1). Our experimental results, in agreement with the predictions of quantum trajectories theory with essentially no adjustable parameters, supports the point of view that a single system under continuous, efficient observation can have a time-dependent wavefunction inferred from the record of previous measurements.  Z. Minev, S.O. Mundhada, S. Shankar, P. Reinhold, R. Guttierez, R.J. Schoelkopf, M. Mirrahimi, H. Carmichael, M.H. Devoret (2017).
Professor Michael L. Neidig, University of Rochester
Intermediates and Mechanism in Iron-Catalyzed Cross-CouplingDespite the increasing development of iron-based catalysts for organic synthesis, a detailed molecular level understanding of these systems has remained largely elusive. This limitation is in stark contrast to palladium chemistry, where detailed studies of active catalyst structure and mechanism have provided the foundation for the continued design and development of catalysts with novel and/or improved catalytic performance. The use of an experimental approach combining advanced inorganic spectroscopies (Mössbauer, magnetic circular dichroism, electron paramagnetic resonance), density functional theory studies, synthesis and kinetic analyses enables the direct evaluation of the active iron species and insight into the mechanisms of catalysis in iron-catalyzed reactions in organic synthesis, including iron-catalyzed cross-coupling. Previous studies from our group using this approach have established the active iron species in iron-bisphosphine catalyzed cross-coupling of mesityl Grignard reagents and primary alkyl halides1 as well as phenyl nucleophiles and secondary alkyl halides.2 Of particular interest are iron-catalyzed cross-couplings with simple ferric salts where we have previously reported the isolation and characterization of [MgCl(THF)5][FeMe4], an intermediate in the reduction pathway of simple ferric salts with methylmagnesium bromide.3 This presentation will focus on recent studies, including the isolation, characterization and reactivity of iron-ate species of relevance to cross-coupling such as [MgCl(THF)5][Fe8Me12],4 as well as recent developments in systems combining iron salts and ligand additives.
Douglas Tobias, University of California - Irvine
Protein Hydration WaterProteins present rough, chemically heterogeneous and dynamic surfaces to their surrounding solvent, which for many proteins is primarily aqueous. Roughly a monolayer of water, the so-called "hydration water", is perturbed structurally and dynamically by interaction with a protein molecule. I will present results from experimental and molecular dynamics simulation studies that exemplify the anomalous properties of protein hydration water and reveal differences in the behavior of water near folded soluble proteins, intrinsically disordered proteins, and membrane proteins. Hydration water is crucial for protein function. I will also present both experimental and simulation results that elucidate the mechanism by which functionally important protein motions are coupled to water dynamics. Finally, I will discuss teh nature and range of protein-water collective fluctuations, and the similarities and differences between the dynamics of protein-confined water at ambient temperature and bulk water at low temperature.
Ariel Amir, Harvard
From single-cell variability and correlations across lineages to the population growthCells of all domains of life must coordinate their cell cycle meticulously in order for protein levels, cell size and DNA replication to be appropriately regulated and to be able to prevent stochastic fluctuations from accumulating over time. These control mechanisms will lead to correlations in various cellular traits across the lineage tree (notably, size and generation times). I will present a recent model we developed for understanding cellular homeostasis and characterizing these correlations and fluctuations. I will discuss the implications of these correlated fluctuations on the population growth. In contrast to the dogma, we find that variability may be detrimental to the population growth, suggesting that evolution would tend to suppress it.
The Tuesday JFI Seminar - CLOSS LECTURE - Prof. Lauren Webb, Department of Chemistry, University of Texas-Austin
Electrostatic and Electrodynamic Fields in Lipid Bilayer MembranesLipid bilayer membranes are complex, dynamic, and functional structures composed of a wide diversity of lipids, proteins, small molecules, and water organized in heterogeneous domains through noncovalent interactions. The structure and motion of these molecules generate large electric fields within the interior of the membrane that are critical to membrane structure and function. Here, we describe how vibrational spectroscopy of unnatural nitrile chromophores places throughout the membrane structure is used to measure electrostatic fields in peptides intercalated in free-standing lipid bilayer membranes of increasing chemical complexity. In combination with electrodynamics simulations, these experiments highlight how common small molecules such as cholesterol dramatically affect membrane structure and dynamics through large changes to membrane electric fields.For further information please contact Brenda Thomas at 773-702-7156 or by email at email@example.com. You may also contact the Host,Sara Massey at firstname.lastname@example.org.
Robert G. Roeder, PhD, Rockefeller University
Mechanisms underlying the cooperative functions of transcriptional coactivators
Lee Lecture: Professor Peidong Yang, University of California Berkeley
CO2 + H2O + Sunlight = Chemical Fuels + O2Solar-to-chemical (STC) production using a fully integrated system is an attractive goal, but to-date there has yet to be a system that can demonstrate the required efficiency, durability, or be manufactured at a reasonable cost. One can learn a great deal from the natural photosynthesis where the conversion of carbon dioxide and water to carbohydrates is routinely carried out at a highly coordinated system level. There are several key features worth mentioning in these systems: spatial and directional arrangement of the light-harvesting components, charge separation and transport, as well as the desired chemical conversion at catalytic sites in compartmentalized spaces. In order to design an efficient artificial photosynthetic materials system, at the level of the individual components: better catalysts need to be developed, new light-absorbing semiconductor materials will need to be discovered, architectures will need to be designed for effective capture and conversion of sunlight, and more importantly, processes need to be developed for the efficient coupling and integration of the components into a complete artificial photosynthetic system. In this talk I will begin by discussing the challenges associated with fixing CO2 through traditional chemical catalytic means, contrasted with the advantages and strategies that biology employs through enzymatic catalysts to produce more complex molecules at higher selectivity and efficiency. I then discuss a number of different photosynthetic biohybrid systems (PBS) architectures from the last few years, and the numerous strategies to interface biotic and abiotic components. Each demonstrates the advantages of PBSs in converting sunlight, H2O and CO2 into food, fuels, pharmaceuticals, and materials. Finally, I will outline the future of this field, opportunities for improvement, and its role in sustainable living here on Earth, and beyond.
Persons with a disability may call (773) 795-5843 in advance for assistance
Lee Lecture: Professor Peidong Yang, University of California Berkeley
Semiconductor Nanowire Building Blocks: From Flux Line Pinning to Artificial PhotosynthesisSemiconductor nanowires, by definition, typically have nanoscale cross-sectional dimensions, with lengths spanning from hundreds of nanometers to millimeters. These subwavelength structures represent a new class of semiconductor materials for investigating light generation, propagation, detection, amplification, and modulation. After more than two decade of research, nanowires can now be synthesized and assembled with specific compositions, heterojunctions, and architectures. This has led to a host of nanowire photonic and electronic devices, including photodetectors, chemical and gas sensors, waveguides, LEDs, microcavity lasers, and nonlinear optical converters. Nanowires also represent an important class of nanostructure building blocks for photovoltaics as well as direct solar-to-fuel conversion because of their high surface area, tunable bandgap, and efficient charge transport and collection. In this talk, I will present a brief history of nanowire research for the past two decades and highlights several recent examples in our lab using semiconductor nanowires and their heterostructures for photonic and energy applications.
Bertrand Halperin, Harvard University
What's going on at v=5/2?Recentexperiments have cast doubt on our understanding of the even-denominatorfractional quantized Hall state with quantum number ν=5/2, which was first observed in1987, in GaAs. Based on numerical calculations, it has long been believed thatthe ground state should be topologically equivalent to either the “Pfaffian”wave function, proposed by Moore and Read, or its particle-hole conjugate, the“Anti-Pfaffian”. Though the two states have many common features, and they haveexactly the same energy in a model that ignores perturbations that break theparticle-hole symmetry of a spin-polarized half-filled Landau level, they aretopologically distinct. In particular,their chiral central charge K, whichdetermines the quantized thermal conductance of their edge states, should havedifferent values, viz., K=7/2 and K=3/2, respectively. Recent measurements designed to distinguishbetween these two possibilities point, instead, to a value K=5/2. I shall review somerecent attempts to understand this situation, as well as speculations aboutother even-denominator quantized Hall states observed in various materials.
SPECIAL JFI Seminar- CLOSS LECTURE - Prof. David Liu, Department of Chemistry & Chemical Biology
Base Editing: Chemistry on a Target Nucleotide in the Genome of Living CellsPoint mutations represent the majority of known human genetic variants associated with disease but are difficult to correct cleanly and efficiently using standard genome editing methods. In this lecture I will describe the development, application, and evolution of base editing, a novel approach to genome editing that directly converts a target base pair to another base pair in living cells without requiring DNA backbone cleavage or donor DNA templates. Through a combination of protein engineering and protein evolution, we recently developed two classes of base editors (BE4 and ABE) that together enable all four types of transition mutations (C to T, T to C, A to G, and G to A) to be efficiently and cleanly installed at target positions in genomic DNA. The four transition mutations collectively account for most known human pathogenic point mutations. Base editing has been successfully performed in a wide range of organisms including bacteria, fungi, plants, fish, frogs, mammals, and even human embryos. We have recently expanded the scope of base editing by enhancing its efficiency, product purity, targeting scope, and DNA specificity. We also show that base editing can function in vivo in post-mitotic somatic cells that do not support efficient homology-directed repair. Finally, we have used our phage-assisted continuous evolution (PACE) system to rapidly evolve Cas9 and base editor variants (xCas9, xCas9-BE3, and xCas9-ABE) with both broadened PAM compatibility and higher DNA specificity. Base editing can be used to correct pathogenic point mutations, introduce disease-suppressing mutations, and create cell and animal models of human disease. Host: Chang Liu via email at email@example.com. Persons with a disability who may need assistace please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org
Shouheng Sun, Brown University
Synthetic Tuning of Nanoparticles to Achieve High Efficiency in ElectrocatalysisDeveloping highly efficient catalysts is crucial for building practical electrochemical devices for energy conversions and for fuel generation. Here we present a new strategy to control Pt-alloy nanoparticle (NP) catalytic efficiency in acid for highly efficient electrochemical reduction or oxidation reactions.
Using FePt as a model system, we have demonstrated that solid solution structured A1-FePt NPs can be converted to chemically ordered tetragonal L10-FePt NPs. These L10-FePt NPs are not only magnetically hard but also chemically robust against Fe leaching in acid. The fully ordered core/shell L10-FePt/Pt NPs show much enhanced catalysis for not only oxygen reduction reaction (ORR) in 0.1 M HClO4, but also hydrogen evolution reaction (HER) in 0.5 M H2SO4. The concept has been successfully extended to other alloy NP systems. For example, the core/shell L10-CoPt/Pt NPs show even higher activity than the L10-FePt/Pt for ORR, surpassing DOE 2020 targets in both activity and durability. Interestingly, by doping a small percentage of Au into the L10-MPt/Pt, the L10-MPt/PtAu NPs become highly efficient in catalyzing electrochemical oxidation of formic acid, methanol or ethanol without noticeable CO poisoning on the Pt surface. Our studies demonstrate a reliable way of tuning NP core/shell structure to enhance shell catalysis for important energy conversion reactions.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Daniel McKinsey, The University of California, Berkeley
Probing Sub-GeV Dark Matter with Superfluid HeliumI will describe a dark matter detection technology that will be sensitive to nuclear recoils of sub-GeV dark matter, using superfluid helium as a target. I will briefly review the state of the field of direct dark matter detection, describe motivations to search for sub-GeV dark matter particles and then explain the merits of superfluid helium as a detector material. These include good kinematic matching to low mass dark matter, excellent intrinsic radiopurity, and its unique ability to be cooled down as a liquid to milli-Kelvin temperatures. We propose to read out the recoil signals by calorimetry based on transition edge sensor readout. Calorimeters submerged in the liquid will measure prompt scintillation photons with near-100% efficiency, while the long-lived rotons and phonon excitations will be detected by quantum evaporation of helium atoms from the liquid surface, into vacuum, and then onto a calorimeter array. The binding energy from helium absorption to the calorimeter surface allows for the amplification of these quantum evaporation signals, allowing sub-eV recoil energy thresholds. Taking into account the relevant backgrounds and detector discrimination power based on the light:heat ratio, sensitivity projections show that a small detector (~kg scale) can already explore new parameter space.
Daniel Mindiola, University of Pennsylvania
Titanium-Carbon Multiple Bonds and Their Roles in the Catalytic Dehydrogenation of Volatile Alkanes and Methane Olefination
Entrapment into orderly growth¿Coming soon? Come at noon! to eat.
Suchitra Sebastian, The University of Cambridge
The Emergent Fundamental – Exotic Collective Phenomena in Correlated Materialsn the quest to understand our universe, complex materials comprising billions of interacting electrons provide new insight akin to probing alternative universes. Where elementary excitations are considered the fundamental fabric of our universe, we find exotic phenomena defined by novel collective excitations to emerge in correlated electron systems, offering a glimpse of the new fundamental. I will discuss experimental tools by which we can discover and understand such unconventional phases of matter, in particular by fine-tuning materials universes under extreme conditions such as applied pressure and high applied magnetic fields. I will explore examples from my work on materials families such as copper oxide high temperature superconductors, and dual metal-insulating rare earth systems, which display strikingly unusual emergent physical properties requiring new paradigms of understanding.
Ralf Riedinger, University of Vienna
Optical Quantum Control of Mechanical OscillatorsMechanical memory elements, directly coupled to photons at designed telecom wavelengths, possess many advantageous features as nodes for large area quantum networks. While impressive experiments like ground state cooling and phonon lasing have recently been demonstrated, genuine non-Gaussian optical quantum control thus far remains elusive. In this talk, I will discuss how the non-linearity of single photon detection can be employed to create non-trivial quantum states. I present recent experimental results on the optical generation of single phonon Fock states and remote entanglement of two massive mechanical oscillators, using silicon optomechanical crystals. Our work introduces mechanical memory elements based in silicon photonics as a new resource for future quantum information systems.
Leigh Orf, University of Wisconsin
Simulating and visualizing the most devastating thunderstormsTornadoes are among nature's most destructive forces. The most violent, long-lived tornadoes form within supercell thunderstorms. In this seminar, results from simulations of tornado-producing supercell thunderstorms at ultra-high resolution will be presented, as well as the technical challenges involved in conducting, analyzing and visualizing such simulations.
In a control simulation, tornado formation occurs in concert with processes not clearly seen in previous supercell simulations. Visualizations of model fields presented at very high temporal resolution (up to 1/6 of a second, the model time step) will be presented. These animations reveal a fascinating combination of processes that lead to the formation of a long lived very violent tornado that persists for well over an hour. In order to facilitate the saving and visualizing of large amounts of model data, a file system was developed that utilizes the HDF file format and ZFP lossy file compressio! n, and th is file system and associated middleware, dubbed LOFS, will be also described.
Unsupervised Machine Learning on the Rigetti Quantum ComputerThe fourth tutorial in the Quantum Computing Tutorial Series
Nicholas Melosh, PhD, Materials Science & Engineering, Stanford
Engineering Inorganic-Biological Interfaces: Nanofluidic Cell Access & Massively Parallel Brain-Machine Interfaces
Delia Milliron, University of Texas at Austin
Surface Depletion in Conducting Metal Oxide NanocrystalsSynthetic control over colloidal metal oxide nanocrystals has advanced so that aliovalent dopants can be introduced, producing degenerately doped semiconductors, such as indium tin oxide (ITO), with metal-like optical properties. The localized surface plasmon resonance (LSPR) absorption of these nanocrystals lies in the infrared range, while their large bandgap makes them transparent to visible light. Since the LSPR absorption can be modulated electrochemically, applications including smart windows that dynamically control solar heat gain can be envisioned. I will discuss how the depletion of electron density near the surface of the conducting nanocrystals controls the extent of modulation achievable; material parameters such as dopant concentration and nanocrystal size can be tuned to achieve desirable dynamic response. Depletion also creates a barrier to electron transport between nanocrystals in a thin film. Orders of magnitude enhancement in conductivity of transparent conductive thin films is demonstrated by tuning dopant spatial distribution and nanocrystal surface chemistry to minimize depletion.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Katherine A. Schreiber, Purdue University
Hydrostatic Pressure Studies of the Second Landau Level of a Two-Dimensional Electron SystemThe fractional quantum Hallstates are important phases of the two dimensional electron system in galliumarsenide, known for displaying perfect quantization of the Hall resistance. Ofparticular interest are the ν = 5/2 and ν = 7/2 quantum Hall states, predictedto host non-Abelian statistics. However, these states are not yet wellunderstood because they are so fragile, so new and refined experimentaltechniques are required to learn more about them. Hydrostatic pressure appliedto a semiconductor system changes the band structure, so we may use it tochange the energy scales influencing the quantum Hall states. Motivatedtherefore to probe the ν = 5/2 and ν = 7/2 quantum Hall states, we appliedpressure up to 30 kbar to our GaAs sample. Excitingly, we observed apressure-induced phase transition at ν = 5/2 and ν = 7/2 from fractionalquantum Hall state to nematic phase, a spontaneously broken rotational symmetryphase displaying significant resistance anisotropy. This was the first time atransition from a fractional quantum Hall state to nematic phase was observedat ν = 5/2 and ν = 7/2 in a two-dimensional electron system in the absence ofan external symmetry breaking field. The transition appears to be a quantumphase transition that occurs at the same critical magnetic field for both the ν= 5/2 and ν = 7/2 states, suggesting that electron-electron interactions play adominant role as a mechanism for this transition.
Chi Wu, The Chinese University of Hong Kong
Anti-biofouling: How a polymer brush repels proteins and our novel integrated designGrafting a layer of chains on a surface to form a polymer brush has been considered as an effective approach to make it anti-biofouling (less protein adsorption). The anti-biofouling property has been qualitatively attributed to the hydration of such a polymer brush with a layer of immobile water molecules and the steric effect; namely, the adsorption decreases monotonically as the polymer grafting density (σ) increases. However, there is no quantitative and satisfactory explanation why the adsorption starts to increase when σ is sufficiently high and why polyethylene glycol (PEG) still remains as one of the best to repel proteins. We have looked the captioned question from another angle: the entropic elasticity instead of the protein-surface interaction, i.e., the enthalpy change.
Considering that each grafted chain is confined inside a cylindrical “pore/tube” made of its neighboring chains, as shown in the right figure, we found its optimal length by minimizing its free energy (A) that contains the exclude volume interaction and the chain elasticity (both of them have an entropic nature) [1, 2]; estimated how A depends on σ and the chain length (L); and calculated its thermal energy-agitated chain conformation fluctuation that slows down the adsorption kinetically. After comparing A with the thermal energy, we are able to predict how both L and affect the protein repelling and explain why PEG performs better than others. Our predictions are surprisingly and quantitatively comparable with those literature results [3, 4].
We will also illustrate how to develop some novel anti-biofouling coatings for shipyard/marine applications by using an integrated design that combines different existing strategies; namely, the self-polishing, the self-structure and the self-generated soft and dynamic surface [5, 6].
Ming-Yu Ngai, Stony Brook University
Development of Novel Chemical Tools for Accessing Unexplored Chemical SpacesSynthetic methodologies that allow access to new chemical spaces are of paramount importance to modern drug discovery. Fluorine-containing compounds represent a unique c2hemical space that has caused a fundamental paradigm change in life science research over the past 50 years. There is a significant gap, however, between the needs of the chemical industry and the current methodological efficiency of incorporating fluorinated moieties into organic compounds. To bridge this gap, one of our research programs aims to develop novel reagents and general transformations for the synthesis of fluorinated compounds. In this lecture, I will present our recent efforts to establish mild and operationally simple reactions for the installation of understudied trifluoromethoxy (OCF3) group and polyfluoroalkoxy (ORf) groups into organic molecules. These groups are appealing as they can often enhance molecular efficacy by increasing metabolic stability, promoting binding affinity with targets, and improving cellular membrane permeability of the parent compounds. Nevertheless, due to the lack of general synthetic methods for the introduction of these fluorinated groups, their potential has not been fully exploited in pharmaceutical, agrochemical, and materials applications. Thus, we hope that our research program will allow access to and study of unexplored chemical spaces to aid the discovery and development of new drugs, biocompatible materials, bio-probes, and imaging agents.
Lena F. Kourkoutis, Cornell University
New frontiers in cryo-electron microscopy: From Probing Low Temperature Electronic Phases to Processes at Liquid/Solid InterfacesScanning transmission electron microscopy techniques have enables direct visualization and quantification of the structure, chemistry and bonding of interfaces, reconstructions, and defects. So far, most efforts in the physical sciences have focused on room temperature measurements where atomic resolution spectroscopic mapping has been demonstrated. For many materials, including those that exhibit electronic and structural phase transitions below room temperature and systems that involve liquid/solid interfaces, measurements at low temperature are required. Operating close to liquid nitrogen temperature gives access to a range of emergent electronic states in solid materials and allows us to study processes at liquid/solid interfaces immobilized by rapid freezing.
In this talk, I will discuss our approach to study two processes at the anode-electrolyte interface in lithium metal batteries (LMBs), uneven deposition of lithium metal leading to dendrite growth and the breakdown of electrolyte to form a “solid-electrolyte interphase” (SEI) layer, processes which result in capacity fade and safety hazards. By combining cryo-electron microscopy with cryo-FIB lift out, we provide nanoscale compositional information about intact SEI layers in cycled LMBs and track local bonding states at interfaces, leading to new insights into SEI and dendrite formation (Figure right).
We further demonstrate sub-Å resolution imaging of crystalline solids at cryogenic temperature, and map the nature and evolution of incommensurate charge order in a manganites. We measure picometer-scale displacive modulations of the cations, distinct from existing manganite charge-order models, and reveal temperature-dependent phase inhomogeneities in the modulations, such as shear deformations and topological defects. At temperatures well below T c phase coherence emerges (Figure left). Using cryo- STEM, the role of the lattice in a variety of low temperature electronic phases can now be quantified with high resolution and precision.
IME Distinguished Colloquium Series: Ronald Germain
Combining Imaging and Cell-based Systems Analysis to Develop a Deep Understanding of ImmunityRecent advances in genomic, flow cytometric, and imaging technologies have increasingly emphasized highly multiplexed examination of biological systems at the single cell level. Our dynamic and static imaging methods, including newly devised highly multiplex 3D methods, have begun to provide a comprehensive spatiotemporal understanding of immune system operation in situ. A key theme that has emerged from this work is the role of fine grained levels of tissue organization in producing efficient adaptive immune responses from an inherently inefficient, sparse system. Our studies have also revealed that several paradigmatic views of cell behavior are not accurate when examined in vivo, while studies of innate immune myeloid cells have provided new insights into regulation of inflammatory tissue damage. At the system biology level, RNA-seq as well as mass-spectrometric examination of cell state (CyTOF analysis) have led to the putative definition of an increasingly large number of cell subsets, approaching the ‘snowflake’ paradigm of every cell being unique. In this lecture, I will discuss some of the key issues pertaining to the origin of variation in RNA and protein expression among what appear to be members of a single cell subset (e.g., TCR transgenic, naïve, resting CD8+ T cells), how such variation affects cellular responses to stimulation, and how predictable, functional biology emerges in an organism with cells, especially rare members of the adaptive immune system, occupying diverse microstates at any given time. Issues to be discussed include: (i) whether cells respond in an ‘instantaneous’ manner dependent on momentary microstate or integrate signals over time as the state changes to decrease the heterogeneity of response, (ii) whether clustering algorithms applied to RNA-seq data reveal stable differentiated subsets of cells or transient fluctuation in sets of co-regulated genes, and (iii) whether individual cells with multiple receptors whose expression varies in time respond with full integration of multiple signals or if biology emerges from the sum of distinct behaviors of individual cells.
This research was supported by the Intramural Research Program of NIAID, NIH.
Ray Moellering, University of Chicago
Integrated Chemical Proteomic Platforms to Probe Metabolic Signaling Across Scales of Space, Time and ReactivityBiological systems are inherently heterogeneous, both at the molecular level (e.g., encoded proteins existing in distinct posttranslational modification states) and the cellular level (e.g., organization of biomolecules to distinct regions of a cell or distinct cells within a tissue). To understand regulatory mechanisms in these systems under normal or diseased states, we must be able to probe biomolecular function in native environments across scales of space and time. Existing proteomic platforms provide quantitative snapshots of the proteins present in a biological sample, yet these methods typically require homogenization of samples, signal-averaging over thousands-to-millions of cells, and provide no information on protein function. Therefore, innovation in the development chemical probes and technology platforms is needed to study protein activity within complex native environments. In the first part of this talk I will describe the development of new chemical probes and complimentary proteomic technologies to enable quantitative measurements in the proteome in native biological contexts – ranging from subcellular complexes, single cells, primary tissues to live animals. In the second half of this talk I will describe the integration of these platforms to discover new roles for reactive endogenous metabolites as intracellular signals in normal and diseased biological states, as well as the potential to regulate these signals for therapeutic benefit. Both halves of the talk will emphasize the role of these integrated chemical proteomic platforms as a discovery engine to identify novel targets for diagnostic and therapeutic development in human disease.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Ned Wingreen, Princeton
Magic numbers in protein phase transitionsBiologists have recently come to appreciate that eukaryotic cells are home to a multiplicity of non-membrane bound compartments, many of which form and dissolve as needed for the cell to function. These dynamical "condensates" enable many central cellular functions – from ribosome assembly, to RNA regulation and storage, to signaling and metabolism. While it is clear that these compartments represent a type of separated phase, what controls their formation, how specific biological components are included or excluded, and how these structures influence physiological and biochemical processes remain largely mysterious. I will discuss recent experiments on phase separated condensates both in vitro and in vivo, and will present theoretical results that highlight a novel “magic number” effect relevant to the formation and control of two-component phase separated condensates.
Phillip L. Geissler, PhD, Chemistry, UC Berkeley
Driven to distraction: Nonequilibrium fates in biomolecular self-assembly
Bloch Lecture: Dr. Carl Decicco, Bristol-Myers Squibb
Innovation in Drug Discovery and Promising New MedicinesDeveloping medicines is a complex process. Recent advances in drug discovery have led to transformational new drugs in cardiovascular disease, hepatitis C, Auto-immunity and the exciting and rapidly advancing field of Immuno-oncology. As we investigate new compounds, we are building off of a growing body of evidence that has accumulated over time, illuminating pathways of disease and providing insight into the optimal drug targets. These breakthroughs are leading to transformational new therapies that are having a profound impact on the lives patients and their families. This lecture will focus on important contributions to medicine from the BMS laboratories.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Zlatka Minev, Department of Applied Physics, Yale University
To Catch and Reverse a Quantum Jump Mid-FlightA quantum system driven by a weak deterministic force while under strong continuous energy measurement exhibits quantum jumps between its energy levels. This celebrated phenomenon is emblematic of the special nature of randomness in quantum physics. The times at which the jumps occur are reputed to be fundamentally unpredictable. However, certain classical phenomena, like tsunamis, while unpredictable in the long term, may possess a degree of predictability in the short term, and in some cases it may be possible to prevent a disaster by detecting an advance warning signal. Can there be, despite the indeterminism of quantum physics, a possibility to know if a quantum jump is about to occur or not? In this paper, we answer this question affirmatively by experimentally demonstrating that the completed jump from the ground to an excited state of a superconducting artificial atom can be tracked, as it follows its predictable "flight," by monitoring the population of an auxiliary level coupled to the ground state. Furthermore, we show that the completed jump is continuous, deterministic, and coherent. Exploiting this coherence, we catch and reverse a quantum jump mid-flight, thus preventing its completion. This real-time intervention is based on a particular lull period in the population of the auxiliary level, which serves as our advance warning signal. Our results, which agree with theoretical predictions essentially without adjustable parameters, support the modern quantum trajectory theory and provide new ground for the exploration of real-time intervention techniques in the control of quantum systems, such as early detection of error syndromes.
Eric Bergshoeff, University of Goettingen
Newton-Cartan Gravity in ActionIn the first part of this talk I will give a short review of the frame-independent formulation of Newtonian gravity, called Newton-Cartan Gravity, and explain why there is a renewed interest into non-relativistic gravity in general. In the second part I will discuss, as a particular application, a recent proposal for an Effective Field Theory describing a massive spin-2 mode (the so-called GMP mode) in the Fractional Quantum Hall Effect.
Timothy Newhouse, Yale
Total Synthesis of Neurologically Active Terpenoid Natural ProductsThis talk will describe the total synthesis of neurologically active terpenoid natural products using novel strategies and methodologies for step-efficient syntheses. Methodological developments in the area of allyl-palladium catalysis will be described in detail that have allowed for alpha,beta-dehydrogenation of a variety of carbonyl compounds. Unique strategies and key retrosynthetic disconnections are guided by computational investigation.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Cooperative swirling within cell coloniesWe eat our food at noon
We watch swirling at 12:15
Martin Zwierlein, Massachusetts Institute of Technology
Strongly Interacting Fermi Gases under the MicroscopeStrongly interacting fermions govern the physics of e.g. high-temperature superconductors, nuclear matter and neutron stars. The interplay of the Pauli principle with strong interactions can give rise to exotic properties that we do not even understand at a qualitative level. In recent years, ultracold Fermi gases of atoms have emerged as a pristine platform for the creation and study of strongly interacting systems of fermions. Near Feshbach resonances, such gases display superfluidity at 17% of the Fermi temperature. Scaled to the density of electrons in solids, this corresponds to superfluidity far above room temperature. Confined in optical lattices, fermionic atoms realize the Fermi-Hubbard model, believed to capture the essence of cuprate high-temperature superconductors. In recent experiments on two-dimensional Fermi gases under a microscope, we observe metallic, Mott insulating and band insulating states with single-site, single-atom resolution. The microscope allows for the site-resolved detection of charge and spin correlations, and for a direct measurement of the transport properties of the Fermi-Hubbard model.
Martin van Hecke, Leiden Institute of Physics
Sequential Mechanical MetamaterialsOrdered sequences of motions govern the morphological transitions of a wide variety of natural and man-made systems, while the ability to interpret time-ordered signals underlies future smart materials that can be (re)programmed and process information. After a short introduction to mechanical metamaterials, we introduce here two novel classes of mechanical metamaterials, that can (1) exhibit sequential output and (2) are sensitive to sequential input. To obtain metamaterials that translate a global uniform compression into a precise multistep pathway of reconfigurations, we combine strongly nonlinear mechanical elements with a multimodal hierarchical structure, and demonstrate multi-step reconfigurations of digitally manufactured metamaterials. To obtain metamaterials that are sensitive to a sequence of mechanical inputs, we introduce the notion of non-commuting metamaterials. Our work aims to establish generic principles for infusing metamaterials with sequential input and output.
The Tuesday JFI Seminar - CLOSS LECTURE - Prof. Garnet Chan, Department of Chemistry, Princeton University
Recent Progress in Quantum ChemistryI will review some of the recent progress made in my group in quantum chemistry methodology and its applications across a variety of problem areas, including metalloenzyme electronic structure, the precision modeling of materials, and the theory of high temperature superconductivity. If time permits, I will also discuss some recent ideas in the areas of quantum dynamics and quantum algorithms on quantum computers.For further information please contact Brenda Thomas at 773-702-7156 or by email at email@example.com. You may also contact the Host, Polina Navotnaya at firstname.lastname@example.org
Harkins Lecture: Xiaowei Zhuang, Howard Hughes Medical Institute, Harvard University
Illuminating Biology at the Nanoscale and Systems Scale by ImagingDissecting the inner workings of a cell requires imaging methods with molecular specificity, molecular-scale resolution, and dynamic imaging capability such that molecular interactions inside the cell can be directly visualized. However, the diffraction-limited resolution of light microscopy is substantially larger than molecular length scales in cells, making many sub-cellular structures difficult to resolve. Another major challenge in imaging is the low throughput in the number of molecular species that can be simultaneously imaged, while genomic-scale throughput is desired for investigating systems level questions. In this talk, I will describe two imaging methods that overcome these challenges and their biological applications. I will first describe STORM, a super-resolution imaging method that overcomes the diffraction limit. This approach allows multicolor and three-dimensional imaging of living cells with nanometer-scale resolution. I will present both technological advances and biological applications of STORM, with focus on recent biological discoveries enabled by STORM. I will then describe MERFISH, a single-cell transcriptome and chromosome imaging method that allows numerous RNA species and genomic loci to be imaged in individual cells. This approach enables mapping of the spatial organization of the transcriptome and genome inside cells and distinct cell types in complex tissues.
Persons with a disability may call (773) 795-5843 in advance for assistance.
K.C. Nicolaou, Rice University
The Art and Science of Organic Synthesis and its Impact on Biology and MedicineThis lecture will cover advancements in chemical synthesis and their applications to biomedical research. A number of examples of total syntheses featuring cascade reactions and other novel strategies and methods will be presented. The impact of the synthetic strategies and technologies developed in these endeavors on biology and medicine through analogue design, synthesis and biological investigations will also be discussed.
As I Lie Dying: A nanoparticle spins towards its demise
It's not as sad as it sounds…Eat 12:00
Geoff Coates, Cornell University
In Pursuit of the Perfect PlasticSociety depends on polymeric materials more now than at any other time in history. Although synthetic polymers are indispensable in a diverse array of applications, ranging from commodity packaging and structural materials to technologically complex biomedical and electronic devices, their synthesis and disposal pose important environmental challenges. The focus of our research is the development of sustainable routes to polymers that have reduced environmental impact. This lecture will focus on our research to transition from fossil fuels to renewable resources for polymer synthesis, as well as the development of polymeric materials designed to bring positive benefits to the environment.
Rama Ranganathan, The University of Chicago
William Dichtel, Northwestern University
Rapid Sequestration of Organic Micropollutants From Water Using Porous Cyclodextrin PolymersOrganic micropollutants, such as pesticides and pharmaceuticals, have raised concerns about negative effects on ecosystems and human health. These compounds are introduced into water resources by human activities, and current wastewater treatment processes do not remove them. Activated carbons are the most widespread adsorbents used to remove organic pollutants from water, but they have several deficiencies, including poor removal of relatively hydrophilic micropollutants, inferior performance in the presence of naturally occurring organic matter, and energy intensive regeneration processes. β-cyclodextrin, an inexpensive, sustainably produced derivative of glucose, encapsulates micropollutants in water. We link β-cyclodextrin into permanently porous polymers that bind micropollutants with adsorption rate constants 15 to 200 times greater than competing adsorbent materials. The polymers bind pollutants with high affinity, yet can be easily regenerated and reused. We also recently modified our original polymer design to target perfluorinated compounds such as PFOA, which are environmentally persistent associated with negative effects at trace concentrations.
Alfred Crosby, University of Massachusetts Amherst
Materials Mechanics for Impulsive MovementNature provides amazing examples of high velocity, high acceleration, impulsive movements that can be repeated numerous times over the course of an organism’s lifetime. Synthetic, or engineered, devices, on the other hand, are often challenged to achieve comparable performance across a wide range of size scales. Common to nature’s examples, including mantis shrimp and trap-jaw ants, is the integration of three essential components for elasticity-assisted movement: an actuator, spring, and latch. Elasticity-assisted motion has been utilized for thousands of years to amplify the power of natural or synthetic actuators; however, the scaling physics of these multi-component systems, especially in light of materials design, have not been widely considered. Here, we discuss our group’s efforts, within a multi-university collaborative team, to lay a foundation for understanding the role that materials properties and structure play in the performance of impulsive systems in nature with an eye toward aiding the development of engineered devices that can overcome current limitations. We first discuss the mechanics of elastic recoil and a set of systematic experiments on a resilin-like synthetic material. The results from this study leads to a common framework for describing the roles of geometry and materials properties for controlling duration, velocity, and acceleration. We then introduce recent advances of using mesoscale polymers, which build upon previously introduced concepts from our group, to develop high rate, large strain, microscale actuators. Collectively, these examples highlight the integrative approach of our group and how we use bio-inspired materials mechanics to inspire new technologies and provide fundamental insight.
Sriram Kosuri, UCLA
Synthetic Approaches to Understanding BiologyI will discuss three projects in our lab where we develop new technologies to allow for the construction and functional testing of large libraries of reporters to explore (1) human genetic variation and splicing, (2) structure/function of antibacterial gene target homologs, and (3) human G-protein coupled receptors.
Susan Marqusee MD/PhD, UCBerkeley
Watching protein folding on & off the ribosome
Mulliken Lecture: Professor John P. Perdew, Temple University
The SCAN Density Functional: Predictive Power of 17 Exact ConstraintsKohn-Sham density functional theory in principle predicts the exact ground-state energy and electron density of a many-electron system via the solution of self-consistent one-electron Schrödinger equations. Only the exchange-correlation energy as a functional of the density needs to be approximated. For materials discovery, the approximations need to be computationally efficient, predictive, and usefully accurate. The SCAN (strongly constrained and appropriately normed) meta-generalized gradient approximation was constructed to satisfy all 17 known exact constraints that a semi-local functional can satisfy (compared to 11 for the PBE GGA). SCAN is further fitted to appropriate norms, non-bonded systems for which a semi-local functional can be accurate for exchange and correlation separately. SCAN recognizes and provides different GGA-like descriptions for covalent single bonds, metallic bonds, and van der Waals (vdW) bonds. Here I will review the functional itself, along with its long-range vdW extension SCAN+rVV10. I will also review applications to properties of diversely-bonded systems, including ferroelectricity, density and structure of liquid water, crystal structure stability, surface properties of transition metals, and critical pressures for structural phase transitions of semiconductors. The accuracy of SCAN is often comparable to or better than that of a hybrid functional, at lower computational cost and without any fitting to bonded systems.
Jian Kang, National High Magnetic Field
Interplay between nematicity and superconductivity in tron-based superconductorsTheiron-based high-Tc superconductors exhibit several remarkable features,including the multi-orbital character and the ubiquity of the nematic phase. One consequence of the multi-orbital Fermi surface isthat the spin-fluctuation mediated pairing interactions are sensitive to theorbital spectral weight at the Fermi surface, leading to several differentpossible gap structures, such as nodeless s±, nodal s±, and d-wave. Focused on the orbital order induced in the nematic phase,I will discuss how the nematic order can manipulate the properties of SC. Ourcalculation shows that not only Tc is enhanced, but moreimportantly, the gap structure becomes a mixture of nearly degenerate s andd-wave states by increasing the external strain. This mixture of s and d wavepairing channels has been recently found in the superconducting phase of thebulk FeSe, when SC occurs deeply insider the nematic phase.
Poul Nissen, PhD, Aarhus University, Denmark
Structure and dynamics of P-type ATPaseActive transport plays a major role in cells. In brain, Na,K-ATPase activity alone accounts for an estimated 40-70% of ATP hydrolysis. Also Ca2+-ATPases of the same P-type ATPase family contribute critically to ion homeostasis in all cell types. These activities are fundamental to life, and malfunction is linked to a range of disorders such as neurological and cardiovascular diseases. Using primarily membrane protein crystallography combined with biochemical and electrophysiological studies, single-molecule FRET, molecular dynamics simulations, modelling, & in vivo models, we have contributed to our growing insight into the mechanistic concepts and functional cycle of the mammalian Na,K-ATPase and Ca2+-ATPase ion pumps. Recently we have also initiated cryoEM studies supported by a large Danish-Swedish cryoEM network, and defined rationales for new X-ray and neutron scattering studies based on the emerging facilities at the MAX IV synchrotron and European Spallation Source in Lund and the European XFEL and Petra3 X-ray sources in Hamburg. Hosted by Benoit Roux and Eduardo Perozo
Wesley A. Chalifoux, University of Nevada
Alkyne Annulations: A Toolkit for Accessing Chemical Diversity from Terpenoids to Conjugated MaterialsReadily available alkyne-containing compounds are attractive as high-energy starting materials that allow an efficient, step- and atom-economical synthesis of a host of useful chemical products. Alkynes and polyynes can be used as linchpins in multicomponent and tandem reactions to provide rapid access to biologically pertinent terpenoid scaffolds. The alkyne functional group also allows for the facile synthesis of novel nanographenes and contorted – even chiral – polycyclic aromatics. Alkynes even allow for a mild, non-oxidative (non-Scholl) bottom-up synthesis of atomically precise graphene nanoribbons (GNRs). Synthetic achievements in both of these areas (terpenoid scaffolds and carbon-rich materials) will be presented in this seminar.
Transient structured fluctuations in a two-dimensional liquid with shouldered pair interactionEat and Kibbitz: 12:00
Heather Knutson, California Institute of Technology
Seeking Clues to Explain the Diverse Architectures of Exoplanetary SystemsOver the past two decades ongoing surveys have detected thousands of new planetary systems around nearby stars. These systems include apparently single gas giant planets on short period orbits, closely packed systems of up to 5-6 “mini-Neptunes”, and solar-system-like architectures with either one small planet or no planets interior to 0.5 AU. Despite our success in cataloguing the diverse properties of these systems, we are still struggling to develop narratives that can explain their divergent evolutionary paths. In my talk I will describe two promising new avenues of investigation, including constraints on the compositions of short-period planets and statistical studies of the frequency of outer gas giant and stellar companions in these systems. Taken together, these observations provide important clues that can be used to determine whether or not the observed population of short period exoplanets formed in situ or migrated in from farther out in the disk.
Professor Hisashi Yamamoto, Professor and Director of Molecular Catalyst Research Center, Chubu University; Arthur Holly Compton Distinguished Professor Emeritus, The University of Chicago; Professor of Emeritus, Nagoya University
From Lewis Acid Catalyst to Catalytic Peptide SynthesisCatalytic peptide synthesis is the long-standing problems for chemical synthesis. One of the most difficult problems for previous synthesis is that the required activated carboxylic acid which caused 1) the racemization of the product and 2) the equimolar usage of the activated ester unit results significant amounts of side products. These issues result difficult to purify the product from by-products.
Generally, Lewis acid catalyst interacts the basic site of molecule and activates another functional group nearby the activated site. Because of the activation by Lewis acid catalyst, even simple methyl ester is able to be used for the reaction. This activation process will avoid any racemization path since the coordination of Lewis acid to the methyl ester may not be attacked by the amide oxygen intramoleculaly. For the basic site (anchor) of the molecules, we are able to use hydroxyl group or equivalents, such as hydroxyl amine, oxime, or BOC protecting amino groups. Lewis acid catalyst can be used various metal alkoxides such as Ta or Nb alkoxides with 1-10 mol% loading. Generally, the amidation proceeds without using any solvent from room temperature up to 80oC in quantitative yields.
With this simple procedure in hand, we are able to introduce the new amino acid unit to the polypeptide chain in two steps with high yields. The proposed process has huge potential for future drug industry.
Thomas Cech, PhD, Chemistry and Biochemistry, University of Colorado Boulder, HHMI
Shedding some Light on the Dark Matter of the Genomic UniverseIn all of life on Earth, information flows from DNA to RNA to Protein. Thus, RNA has a role as a message, transmitting the information encoded in our chromosomal DNA. LncRNAs (long noncoding RNAs) have long been the “dark matter” of the genome, but they also have active roles in biology, even acting as enzymes (ribozymes). Another lncRNA is found in the telomerase RNP, which extends the DNA at chromosome ends and thereby contributes to genome stability. Finally, the binding of lncRNAs to PRC2 helps regulate epigenetic silencing of gene expression.
Ward Lopes, NVIDIA
A Careers-in-science discussion with a UChicago AlumnusWard Lopes is a Sr. Research Scientist who works on display research. His main research interests are applications of dynamic, computer generated holography and holographic optical elements in virtual-, augmented-, and mixed-reality. Prior 2015, Ward focused on self-assembly processes in soft condensed matter and applications of holography in optical micromanipulation and microscopy. Ward has publications on a variety of topics from nano-scale self-assembly and nanotechnology, bio-physics, holographic optical trapping, laser physics, to measurement techniques in the geosciences. Prior to joining NVIDIA, Ward was a physics professor at Williams College and at Mount Holyoke college, and was the Director of Product Research at Arryx, Inc. While at Arryx, he was awarded the R&D 100 Award by R&D Magazine for the 100 “most technologically significant products introduced into the marketplace” for the BioRyx200 system (a holographic optical trapping system).
Michael Shelley, NYU Courant, Flatiron Institute
Active Mechanics in the CellMany fundamental phenomena in eukaryotic cells -- nuclear migration, spindle positioning, chromosome segregation -- involve the interaction of often transitory structures with boundaries and fluids. I will discuss the interaction of theory and simulation with experimental measurements of active processes within the cell. This includes understanding the force transduction mechanisms underlying nuclear migration, spindle positioning and oscillations, as well as how active displacement domains of chromatin might be forming in the interphase nucleus.
The Tuesday JFI Seminar - Prof. Sriram Ramaswamy, Indian Institute of Science
Active Soft Matter and Other StoriesActive Matter was formulated to incorporate living materials into the capacious fold of condensed-matter and statistical physics. My talk will discuss the successes of this approach on scales from micrometres to kilometres in living and artificial systems; relate active-matter problems to more familiar nonequilibrium phenomena such as sedimentation; and highlight our recent work on (in)stability, defects, flocking and collective trapping, especially in artificial realisations of collective motility.
For further information please contact Brenda Thomas at 773-702-7156 or via email at email@example.com. You may also contact the Host, Suri Vaikuntanathun at 773-702-7256 or by email at firstname.lastname@example.org.
Aron Pinczuk, Columbia University
Experimental studies of magnetoroton modes of fractional Quantum hall fluidsQuantum Hall phases are archetypes of the remarkable many-electron physics that emerges in electron fluids under conditions of greatly reduced dimensionality.
Magnetoroton modes are characteristic low-energy excitations that manifest underlying fundamental interactions in fractional quantum Hall fluids.
Inelastic light scattering methods at very low temperatures are experimental venues to study low-lying excitations of quantum Hall fluids. Of particular interest are the
excitation modes that demonstrate novel quantum liquid behavior and that offer insights on unexpected collective responses. Besides magnetorotons, low-lying spin wave modes that probe rotational invariance of spin are of interest here.
This presentation considers inelastic light scattering studies of low-lying excitations that probe intriguing physics of quantum Hall fluids. Early results in the partially populated lowest Landau level, at filling factors n=1/2 and n=1/3, will be reviewed. More recent results considered are observations of excitations of the electron fluids that reside in the partially populated second Landau level (filling factors n=5/2 and n=7/3).
Lucy Colwell, Department of Chemistry, University of Cambridge
Using Evolutionary Sequence Variation to Build Predictive Models of Protein Structure and FunctionThe evolutionary trajectory of a protein through sequence space is constrained by its function. Collections of sequence homologs record the outcomes of millions of evolutionary experiments in which the protein evolves according to these constraints. The explosive growth in the number of available protein sequences raises the possibility of using the natural variation present in homologous protein sequences to infer these constraints and thus identify residues that control different protein phenotypes. Because in many cases phenotypic changes are controlled by more than one amino acid, the mutations that separate one phenotype from another may not be independent, requiring us to understand the correlation structure of the data. We show that models constrained by the statistics of the multiple sequence alignment are capable of predicting key aspects of protein function. These include (i) the inference of residue pair interactions that are accurate enough to predict all atom 3D structural models; and predictions of (ii) binding interactions between different proteins and (iii) binding between protein receptors and their target ligands.
The challenge is to distinguish true interactions from the noisy and under-sampled set of observed correlations in a large multiple sequence alignment. Current methods ignore the phylogenetic relationships between sequences, potentially corrupting the identification of covarying positions. Here, we use random matrix theory to demonstrate the existence of a power law tail that distinguishes the spectrum of covariance caused by phylogeny from that caused by phenotypic interactions. The power law is essentially independent of the phylogenetic tree topology, depending on just two parameters - the sequence length, and the average branch length of the tree. We demonstrate that these power law tails are ubiquitous in the large protein sequence alignments used to predict contacts in 3D structure, as predicted by our theory, and confirm that truncating the corresponding eigenvectors improves contact prediction. Finally, I will discuss current efforts to further enhance these methods using recent advances in deep learning. Persons with disability who may need assistance please contact Brenda Thomas at 773-702-7156 or by at email@example.com or Host: Stephanie Palmer, 773-702-0771 or via email at firstname.lastname@example.org
Sylvia T. Ceyer, Massachusetts Institute of Technology
Delving Below and Beyond the SurfaceCatalytic surface reactions depend not only on adsorbed species but also on absorbed species. Experiments that document the distinctive reactivity of a H atom embedded in the bulk of a Ni metal catalyst are described. In particular, a H atom emerging from the bulk onto the surface is transiently more energetic by about 24 kcal/mol compared to a H atom adsorbed on the surface. Consequently, it is the reactive species in hydrogenation of adsorbed ethylene and acetylene, respectively, while a H atom adsorbed on the Ni surface is not reactive. These results demonstrate that bulk H is not solely a source of surface bound H in catalytic hydrogenation as proposed 60 years ago, but rather, a reactant with a distinctive chemistry of its own.
In cases where the surface is a reactant rather than a catalyst, a scattering approach has shown two likely origins for the factor of 103 to 104 high etching rate of Si by XeF2 than by F2: significant vibrational excitation of the Si lattice upon initial collision of the massive XeF2, prior to abstraction of the first F atom by Si, and second, the gas phase dissociation of the XeF abstraction product that produces a small fraction of F atoms that are aimed back at the Si surface. This study is a possible example of collisional energy transfer to a surface playing a critical role in the probability of a molecule-surface reaction and is the first documentation of dissociation of a product of a surface reaction in the gas phase.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Kharasch Lecture: Professor Stephen Buchwald, MIT
Palladium-Based Methodology in Imaging and BioconjugationWe have started to apply methodology related to Pd-catalyzed C-N coupling to the preparation of isotopically labelled compounds for the purposes of imaging (cf. J. Am. Chem. Soc. 2017, 139, 7152). Additionally, we are working in a variety of areas dealing with the functionalization of biomolecules including peptides, proteins and antibodies (Nature, 2015, 526, 687, Org. Lett. 2017, 19, 4263).
This lecture will describe: 1) Our work on the preparation of 11C-labelled small molecules and peptides. 2) The development of technology for the functionalization of peptides and proteins. 3) A new method for the synthesis of stapled peptides. 4) Applications to the preparation of antibody drug conjugates.
How sound makes turtles and trees in mid-airCome with food at noon
Get ready to fly at 12:15
Michael Brenner, Harvard University
The quest to observe the Turbulent Cascade in real time
Novartis Lecture: Professor Shannon S. Stahl, University of Wisconsin-Madison
Practical Aerobic and Electrochemical Oxidation ReactionsResearch in the Stahl lab targets the discovery, development, and mechanistic understanding of new catalysts and catalytic processes, especially related to oxidation reactions. As the most abundant and environmentally benign oxidant available, molecular oxygen is the quintessential oxidant, but controlling its reactivity to achieve selective oxidation of organic molecules presents considerable fundamental and practical challenges. Until recently, aerobic oxidation reactions were virtually never used in process-scale synthesis of fine chemicals, agrochemicals or pharmaceuticals, and they were rarely used in laboratory syntheses. This talk will present a general catalytic strategy for aerobic oxidation reactions, inspired by oxidase enzymes, that is designed to enable widespread use of O2 as an oxidant in chemical synthesis. Fundamental and practical advances in this area will be presented, including highlights of industrial collaborations that have played an important role in these efforts. The "oxidase" approach to aerobic oxidation reactions is conceptually similar to electrochemical redox reactions. Both reaction classes feature the coupling of two independent half-reactions. The aerobic oxidation reactions employ a single catalyst site for both steps, while the electrochemical half-reactions take place at independent electrodes. The relationship between these reactions will be presented, together with recent examples of electrosynthetic oxidation reactions that we have developed.
Novartis Lecture: Professor Tianning Diao, New York University
Strategies for Promoting Nickel-Catalyzed Alkene FunctionalizationNi catalysts have recently emerged as appealing tools in organic synthesis, allowing access to new reactivity in cross-coupling and opening up new avenues in synthesis. Despite the growing use of Ni catalysts, mechanistic understanding of Ni-catalyzed reactions is inadequate, partly due to complex radical intermediates that complicate mechanistic studies. Our group explores the unique reactivity of Ni catalysts from a fundamental perspective, combining mechanistic approaches with method development. I will present three strategies to tame the reactivity of Ni catalysts. Redox-active ligands stabilize Ni(I) and Ni(III) intermediates and allow classic two-electron transformations to take place on a Ni(I)/Ni(III) platform. In addition, we explored Ni-initiated radical formation from alkyl halides to reductively functionalize alkenes. Finally, we show that dinuclear Ni complexes can react cooperatively, facilitating two-electron redox processes by accepting/donating one electron at each metal center.
Novartis Lecture: Professor Mikhail G. Shapiro, California Institute of Technology
Molecular Engineering for Non-Invasive Imaging and Control of Cellular FunctionThe study of biological function in intact organisms and the development of targeted cellular therapeutics necessitate methods to image and control cellular function in vivo. Technologies such as fluorescent proteins and optogenetics serve this purpose in small, translucent specimens, but are limited by the poor penetration of light into deeper tissues. In contrast, most non-invasive techniques such as ultrasound and magnetic resonance imaging – while based on energy forms that penetrate tissue effectively – are not effectively coupled to cellular function. Our work attempts to bridge this gap by engineering biomolecules with the appropriate physical properties to interact with magnetic fields and sound waves. In this talk, I will describe our recent development of biomolecular reporters and actuators for ultrasound. The reporters are based on a unique class of gas-filled protein nanostructures from buoyant photosynthetic microbes. These proteins produce nonlinear scattering of sound waves, enabling their detection with ultrasound. I will describe our recent progress in understanding the biophysical and acoustic properties of these biomolecules, engineering their mechanics and targeting at the genetic level, developing methods to enhance their detection in vivo and expressing them heterologously as acoustic reporter genes. Our actuators are based on temperature-dependent transcriptional repressors, which provide switch-like control of bacterial gene expression in response to small changes in temperature. We have genetically tuned these repressors to activate at thresholds within the biomedically relevant range of 32ºC to 46ºC, and constructed genetic logic circuits to connect thermal signals to various cellular functions. This allows us to use focused ultrasound to remote-control engineered bacteria in vivo.
Novartis Lecture: Dr. Katsumasa Nakajima, Novartis Institutes for BioMedical Research
Building an Arsenal of Small Molecule DGAT1 Inhibitors to Battle Metabolic SyndromeObesity is characterized as excess accumulation of body fat (triglyceride) and contributes to a diagnosis of metabolic syndrome, which is associated with increased risk of cardiovascular disease and diabetes. To battle metabolic syndrome, we initiated a drug discovery program targeting diacylglycerol acyltransferases 1 (DGAT1) which catalyzes the final committed step of triglyceride synthesis. After screening using recombinant human DGAT1 enzyme, diamide and benzimidazole classes of DGAT1 inhibitors were discovered. The diamide compounds were potent DGAT1 inhibitors in vitro but initially lacked suitable molecular properties to inhibit DGAT1 in vivo. Introduction of an aromatic ring as the amide N substituent was found effective to produce an orally bioavailable molecule that potently inhibits DGAT1 in vivo from this series. The benzimidazole series required first optimization of in vitro potency by adding amide and propionic acid groups to the core structure, though these groups kept the molecule from being effectively absorbed in vivo after oral administration. Conversion of the amide to oxadiazole as amide bioisostere and dimethylation at ɑ position in the propionic acid successfully addressed the issue, providing another potent, orally bioavailable DGAT1 inhibitor. This compound demonstrated chronic efficacy by reducing body weight gain in a diet induced obese dog model and was advanced to the clinical investigation along with pradigastat, aminopyridine class of DGAT1 inhibitor that was also developed in our group.
IME Distinguished Colloquium Series: Demetri Psaltis, EPFL
Benjamin B. Machta, Princeton University
When and why is a simpler model better?Science is filled with toy models: abstractions of complicated systems that ignore microscopic details even when they are known. For a special class of models in physics, the renormalization group rigorously justifies the use of effective theories containing just a small number of relevant parameters. This philosophy seems to apply more broadly, even when the renormalization group cannot be used. But why? In this talk I will discuss an information theory approach to answering this question, or at least towards quantifying it. I will first review that typical models are sloppy, defined by a hierarchy in parameter importance. I will argue that sloppiness is both necessary and sufficient for a microscopic system to be amenable to description by a simpler effective theory. I will then show how renormalizable models become sloppy as their data is coarse-grained. Finally I will discuss our recent efforts to use the structure of these models to choose simpler effective theories automatically.
Kharasch Lecture: Professor Stephen Buchwald, MIT
Asymmetric Hydrofunctionalization Processes for Organic SynthesisThe availability of a general method for the catalytic conversion of olefins into enantiomerically enriched amines has eluded chemists for decades. We have recently developed a simple copper-catalyzed technique to effect such a transformation. This lecture will describe our progress, applications of our methodology as well as our current view of the mechanism of the hydroamination process. In addition, we will describe our progress in developing new catalytic processes for carbon-carbon bond formation that utilize alkyl copper intermediates.
The JFI First Tuesday Colloquium - Prof. Ignacio Franco, Department of Chemistry, University of Rochester
Stark Control of ElectronsA general goal in our quest to control matter and energy is the design of strategies to control electronic properties and electron dynamics using coherent laser sources. In addition to its interest at a fundamental level, lasers permit manipulation on an ultrafast timescale opening the way to control the ability of matter to chemically react, conduct charge, absorb light, or other properties, in a femto to attosecond timescale.
In this talk, I will summarize our efforts to understand electronic decoherence processes in molecules that are deleterious to interference-based scenarios for the laser control. In addition, I will discuss how, through Stark effects, non-resonant light of intermediate intensity (non-perturbative but non-ionizing) can be used to generate “laser-dressed” molecules and materials with non-equilibrium properties that can be very different from those observed by matter near thermodynamics equilibrium. In particular, I will discuss how Stark effects can be employed to turn transparent nanomaterials into broadband absorbers, and to generate currents in nanoscale junctions.For further information please contact Brenda Thomas at 773-702-7156 or via email at email@example.com. You may also contact the Host: Timothy Berkelbach 773- 834-9879 or by email at firstname.lastname@example.org.
Thomas T. Perkins, PhD, JILA & University of Colorado Boulder
Probing the equilibrium folding dynamicsof individual bacteriorhodopsin molecules with 1-μs resolution
Kharasch Lecture: Professor Stephen Buchwald, MIT
Palladium-Catalyzed Carbon-Heteroatom Bond-Forming Reactions for Organic SynthesisCross-coupling methodology is an indispensable part of the everyday repertoire of synthetic organic chemists. Among the many possibilities, we have focused a great deal of attention on the Pd-catalyzed formation of C-N bonds (Chem. Rev., 2016, 116, 12564); a mechanistic pathway for this transformation is shown below. This methodology has been widely utilized throughout academia and industry.
Crucial to our success in the development of new and more generally applicable methods has been our discovery and use of biaryl monodentate phosphine ligands. These have been licensed for manufacture on large scale to eight companies and are available, in many cases, on very large scale (100's of Kg produced). This methodology has been widely utilized throughout academia and industry.
The history of our work up to the most recent developments will be discussed.
Jiehang Zhang, University of Maryland
Engineered Quantum Spin Systems: Out-of EquilibriumQuantum mechanics prescribes exponential scaling of the Hilbert space dimension in many-body systems, which presents both challenges and new opportunities for understanding strongly correlated matter, especially since novel custom-built systems are now available. I will describe such efforts on engineering quantum systems atom by atom, precisely controlling them with laser-driven interactions, and increasing the system size up to a regime where the capabilities of classical computers are challenged.
I will focus on the platform of trapped atomic ions, where a combination of excellent coherence time and high-fidelity measurements has enabled many applications, ranging from simulating condensed matter physics, to quantum computation. We represent spin qubits with electronic levels of ions in a Coulomb crystal, and entangle them through tailored laser pulses. I will present recent experiments using these systems to study dynamical phase with individual resolution for more than 50 spins, as well as non-equilibrium driven matter. I then conclude with future prospects.
Jennifer Cano, Princeton University
Topological Quantum ChemistryThe past decade's apparent success in predicting and experimentally discovering distinct classes of topological insulators (TIs) and semimetals masks a fundamental shortcoming: out of 200,000 stoichiometric compounds extant in material databases, only several hundred of them are topologically nontrivial. Are TIs that esoteric, or does this reflect a fundamental problem with the current piecemeal approach to finding them? To address this, we propose a new and complete electronic band theory that highlights the link between topology and local chemical bonding, and combines this with the conventional band theory of electrons. We classify the possible band structures for all 230 crystal symmetry groups that arise from local atomic orbitals, and show which are topologically nontrivial. We show how our topological band theory sheds new light on known TIs, and demonstrate the power of our method to predict new TIs.
Dr. Jordan Meier, National Cancer Insitute
Illuminating Acetylation's Dark Matter with ChemoproteomicsA paradox of modern acetylation biology is that the while number of sites of acetylation has climbed rapidly, the number of enzymes thought to catalyze this process has stayed relatively constant. Here we describe the utility of chemical proteomic methods to discover and characterize novel mechanisms of acetylation in endogenous cellular contexts. Our studies highlight an expanded landscape of regulatory acetylation in gene expression control, as well as new strategies to investigate the metabolic regulation and small molecule inhibition of acetyltransferases in cells.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Fred Chong, The University of Chicago
Scaling up Quantum ComputersQuantum computing is at an inflection point, where 50-qubit (quantum bit) machines have been built, 100-qubit machines are just around the corner, and even 1000-qubit machines are perhaps only a few years away. These machines have the potential to fundamentally change our concept of what is computable and demonstrate practical applications in areas such as quantum chemistry, optimization, and quantum simulation.
Yet a significant resource gap remains between practical quantum algorithms and near-term machines. Programming, compilation and control will play a key role in increasing the efficiency of algorithms and machines to close this gap.
I will outline the grand research challenges in closing this gap, including programming language design, software and hardware verification, defining and perforating abstraction boundaries, cross-layer optimization, managing parallelism and communication, mapping and scheduling computations, reducing control complexity, machine-specific optimizations, and many more. I will also describe the resources and infrastructure available for tackling these challenges.
Ken Kamrin, MIT
Modeling flowing granular material as a continuum: Surprising complexity meets surprising simplicityGranular materials are common in everyday life but are historically difficult to model. This has direct real-world ramifications owing to the prominent role granular media play in multiple industries and in terrain dynamics. One can attempt to track every grain with discrete particle methods, but realistic systems are often too large for this approach and a continuum model is desired. However, granular media display unusual behaviors that complicate the continuum treatment: they can behave like solid, flow like liquid, or separate into a “gas”, and the rheology of the flowing state displays remarkable subtleties.
To address these challenges, in this talk we develop a family of continuum models and numerical solvers, which permit quantitative modeling capabilities for general problems and certain reduced-order approaches for problems of intrusion, impact, driving, and locomotion in grains. To calculate flows in general cases, a rather significant nonlocal effect is evident, which is well-described with our recent nonlocal model accounting for grain cooperativity within the rheology. On the other hand, to model just intrusion forces on submerged objects, we will show, and explain why, many of the experimentally observed results can be captured from a much simpler tension-free frictional plasticity model. This approach gives way to some surprisingly simple general tools, including the granular Resistive Force Theory, and a broad set of scaling laws inherent to the problem of granular locomotion. These scalings are validated experimentally and in discrete particle simulations suggesting a new down-scaled paradigm for granular locomotive design, on earth and beyond, to be used much like scaling laws in fluid mechanics. We close with ongoing efforts expanding into wet granular flows, multi-scale approaches, and self-optimizing wheels for off-road traction.
Seppe Kuehn, University of Illinois at Urbana-Champaign
Constraints on eco-evolutionary dynamics in bacterial communitiesCan we predict evolutionary and ecological dynamics in microbial communities? I argue that understanding constraints on biological systems provides a path forward to build predictive models. I present two vignettes which illustrate the power of elucidating constraints. First, we ask how constraints on phenotypic variation can be exploited to predict evolution. We select Escherichia coli simultaneously for motility and growth and find that a trade-off between these phenotypes constrains adaptation. Using genetic engineering, high- throughput phenotyping and modeling we show that the genetic capacity of an organism to vary traits can qualitatively depend on its environment, which in turn alters its evolutionary trajectory [eLife, 2017]. Our results suggest that knowledge of phenotypic constraints and genetic architecture can provide a route to predicting evolutionary dynamics. Second, in nature microbial populations are subjected to nutrient fluctuations but we know little about how communities respond to these fluctuations. Using automated long-term single cell imaging and custom continuous-culture devices we subject bacterial populations to nutrient fluctuations on multiple timescales._x000B_We find populations recover faster from large, frequent fluctuations. Our observation is explained by a model that captures constraints on the rate at which populations transition from planktonic and aggregated lifestyles.
Epistasis: the link between protein sequence and function
A new approach shows promiseEpstasis is the observed statistical correlation of mutations affecting a given protein.
A new approach shows promise
Come at noon to eat and talk
Discussion launch time 12:15
Bill Archer, Los Alamos Laboratory
Computing in the Los Alamos Weapons Program
Los Alamos has continuously been on the forefront of scientific computing since it helped found the field. This talk will explore the rich history of computing in the Los Alamos weapons program. The current status of computing will be discussed, as will the expectations for the near future.
March Meeting rehash: moiré graphene superconductivity, etc.I hope you can make it to the baglunch tomorrow. If you went to the March meeting, I hope you'll bring your favorite tidbit to tell us about. One dramatic announcement was the report of superconductivity in a bilayer of graphene. How does that work?? Come with your daffiest ideas.
12:00 would be a great time to show up with your food if you don't want to miss anything
12:15 ---you won't miss too much.
Aleksandra Vojvodic, University of Pennsylvania
Computationally predicting chemistry of transition-metal compound materialsFueling the planet with energy, chemicals and food are central challenges of the 21st century. Most materials we see in our everyday life have seen at one point or another a catalyst material of a complex nature. I will demonstrate how we today can computationally predict new catalyst materials through a careful analysis of the surface chemistry at the atomic-scale level enabled by access to advanced computational approaches.
I will present our studies on electrochemical water splitting including both of its subreactions: the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Computationally we have identified a new highly active two-dimensional (2D) transition-metal carbide HER catalyst and transition-metal oxide OER catalysts that have been experimentally synthesized, characterized and tested. The OER catalysts belong to the perovskite group of oxide materials or are oxides based on earth abundant metal elements. I will also share our recent insights on the reactivity and activity of metal-supported thin layers, nanoparticles of oxides and heterostructured oxide systems. Finally, I will discuss our recent findings on oxygen incorporation chemistry into non-stoichiometric oxides.
Gediminas Juzeliūnas, Vilnius University, Lithuania
Synthetic spin-orbit coupling for ultracold atomsCurrently there is a great deal of activities in studying the spin-orbit coupling (SOC) for ultracold atoms. One of the challenges is to experimentally produce a two-dimensional (2D) SOC of the Rashba type, as well as a 3D Weyl SOC for the center of mass motion of ultracold atoms . In particular, it was proposed that the 2D and 3D SOC can be generated by laser-dressing atomic internal states  or using a periodic sequence of magnetic gradient pulses . Here we shall review these activities and also talk about the omnidirectional Spin-Hall effect  which can manifest for Weyl spin-orbit coupled ultracold atoms. We shall also discuss another way of creating the 2D SOC using ultracold atoms confined in bilayer structures [4-5]. An interplay between the inter-layer tunneling, intra-layer Raman coupling and intra-layer atom-atom interaction gives rise to an effective 2D SOC providing diverse ground-state configurations for bilayer Bose-Einstein condensates (BEC)  and degenerate Fermi gases .
Roy Beck-Barkai , Tel-Aviv University
From kB to kB: Universal and efficient entropy estimation using a compression algorithmEntropy and free-energy estimation are key in thermodynamic characterization of simulated systems ranging from spin models through polymers, colloids, protein structure, and drug-design. Current techniques suffer from being model specific, requiring abundant computation resources and simulation at conditions far from the studied realization. In this talk, I will present a novel universal scheme to calculate entropy using lossless compression algorithms and validate it on simulated systems of increasing complexity. Our results show accurate entropy values compared to benchmark calculations while being computationally effective. In molecular-dynamics simulations of protein folding, we exhibit unmatched detection capability of the folded states by measuring previously undetectable entropy fluctuations along the simulation timeline. Such entropy evaluation opens a new window onto the dynamics of complex systems and allows efficient free-energy calculations.
The Tuesday JFI Seminar - Lutz Maibum, Department of Chemistry, University of Washington
Spatial Organization of Complex Lipid Bilayers: Emergent Order Across Multiple ScalesCellular membranes are bilayers made of a large number of different types of phospholipids, sterols, and proteins. Their spatial organization is of fundamental importance for a large number of elementary biological processes including cell signaling and membrane trafficking. It has become clear that phospholipids and sterols contribute significantly to the lateral structure of such membranes. The order that emerges from their interactions spans multiple length scales, which necessitates the use of a wide range of models to study membrane organization with computational methods. In this talk I present our principal discoveries of membrane structure across multiple scales, including new aspects of the condensing effect of cholesterol, the rich phase behavior of multicomponent bilayers, and the effect of membrane fluctuations on protein interactions.
Charles M. Lieber, Harvard University
Nanoelectronic Tools for Brain Science
Peter Schauss, Princeton University
Quantum gas microscopy of many-body dynamics in Fermi-Hubbard and Ising systemsThe ability to probe and manipulate cold atoms in optical lattices at the atomic level using quantum gas microscopes enables quantitative studies of quantum many-body dynamics. While there are many well-developed theoretical tools to study many-body quantum systems in equilibrium, gaining insight into dynamics is challenging with available techniques. Approximate methods need to be benchmarked, creating an urgent need for measurements in experimental model systems. In this talk, I will discuss two such measurements.
First, I will present a study that probes the relaxation of density modulations in the doped Fermi-Hubbard model. This leads to a hydrodynamic description that allows us to determine the conductivity. We observe bad metallic behavior that we compare to predictions from finite-temperature Lanczos calculations and dynamical mean field theory.
Second, I introduce a new platform to study the 2D quantum Ising model. Via optical coupling of atoms in an optical lattice to a low-lying Rydberg state, we observe quench dynamics in the resulting Ising model and prepare states with antiferromagnetic correlations.
Chang-Tse Hsieh, IPMU
Symmetry-protected critical phases, generalized Lieb-Schultz-Mattis theorem, and global anomalies in (1+1) dimensionsThe robustness of gaplessness in the presence of symmetries is one of the characteristics of the edge states of one-dimensional symmetry-protected topological (SPT) phases. These edge states, as the symmetries are realized in an on-site manner, can not exist alone and must arise on the boundary of one-higher dimensional SPT phases. This situation can, however, be circumvented for a 1d system with non-on-site symmetries, such as lattice translation symmetry, in the case that a nontrivial 2d bulk is absent. In this talk, I will discuss the quantum criticality in purely 1d lattice systems that is protected by translation symmetry together with some other on-site symmetries, from the perspective of ('t Hooft) anomaly matching. Examples include the charged fermions and SU(N) spin chains. The Lieb-Schultz-Mattis theorem, in the framework of field theory, is also re-derived and generalized.
Future of Particle Physics: LHC and beyond
Particle physics entered a new era after the discovery of the Higgs boson. The Standard Model has left open many important questions, such as the origin of electroweak scale and identity of the dark matter. Searching for answers to these questions will be the main goal for particle physics in the decades to come. I will review the status of theoretical ideas and experimental searches for new physics, with focus on recent developments. I will also offer my perspective on possible future directions, including the next steps in the searches at the LHC, as well as other on-going and future experiments.
Sean M. Gibbons, PhD, MIT
Individual-specific eco-evolutionary dynamics in the human gut microbiomeDr. Gibbons will be hosted by BPHYS first-years, Vil Zsolnay and Elizabeth White.
JR Schmidt, University of Wisconsin-Madison
Physics-based force fields for next-generation accuracy and transability in molecular simulationsI will present a general methodology for generating accurate and transferable "physics-based" ab initio force fields for use in “next generation” molecular dynamics simulations. These force field models incorporate explicit terms to account for the dominant forces in (non-reactive) intermolecular interactions: exchange repulsion, electrostatics, polarization, and dispersion. This approach opens exciting possibilities for modeling chemical systems for which little or no experimental data exists. I will present a variety of applications, including those involving metal-organic framework materials, organic liquids, ionic liquids. The transferable nature of the force field models allows for their utilization for a wide variety of chemical systems. Building on that work, I will also present a number of recent developments that enable a significant increase in the accuracy of ab initio force fields via new approaches for modeling short-range Pauli repulsion and for capturing the local anisotropy of inter-atomic interactions (e.g. in the vicinity of a "lone pair"). These latter advances open up the possibility for even higher accuracy and transferability in a wide variety molecular simulation contexts.
Anatoly Dymarsky, University of Kentucky
Defining thermalization timeThe conventional picture of how an isolated chaotic system thermalizes suggests that starting from a out of equilibrium state, the system reaches the equilibrium within Thouless time - the time necessary for the slowest (diffusive) mode to propagate across the whole system. Once that happened the system is expected to be fully ergodic i.e. its behavior should be independent of the initial conditions. It is in this regime a quantum system is expected to be described by a random matrix theory. Accordingly Thouless energy is usually associated with the energy scale of applicability of the random matrix description. In this talk we show that the conventional picture is too naive. By introducing a new characteristic of quantum systems which is sensitive to thermalization time, we show that the energy scale at which Eigenstate Thermalization Hypothesis ansatz reduces to the random matrix theory is parametrically different from the Thouless scale.
From LEGO to Active Fluids
This colloquium offers a gentle introduction to the physics of topological materials using vivid mechanical demonstrations. The distinctive property of topological materials is the existence of states and excitations that are robust (or protected) against structural deformations, changes in material parameters or imperfections. We concentrate on two examples of topologically protected states: the folding motions of origami-like structures and sound propagation in active fluids composed of self-propelled particles. In both cases we trace the mathematical origin of physical robustness to elegant notions of topology.
Dr. Tanay Roy, Tata Institute of Fundamental Research
Multi-mode Superconducting Circuits for Building Programmable Multi-qubit Quantum ProcessorsQuantum processors are capable of providing enormous speedup to certain problems by exploiting classically inaccessible paths. A vast majority of the small-scale quantum processors demonstrated so far in solid-state systems rely on the nearest-neighbor coupling. The limited connectivity and native gates restricted between two qubits hinder efficient implementation of many quantum algorithms. In this talk, I will introduce the “trimon” , a longitudinally coupled three-qubit system based on a multi-mode superconducting circuit. I will first describe how we can achieve universal programmability by utilizing elementary controlled-controlled-rotations and all-to-all connectivity. Reconstruction of the density matrix for an arbitrary three-qubit state is accomplished using a joint readout scheme. I will then discuss the performance of the single-pulse generalized Toffoli gates and the preparation of different two- and three-qubit entangled states. Another unique feature of this system is the ability to implement error-free CCZ gate  which simplifies the construction of various quantum oracles. I will demonstrate these capabilities by executing various quantum algorithms like Deutsch-Jozsa, Bernstein-Vazirani, Grover, quantum Fourier transform etc. on the three-qubit processor. Finally, I will discuss the possibility of building larger quantum processors using these longitudinally coupled multi-qubit systems.
IME Distinguished Colloquium Series: Jeff Snyder, Northwestern University
Dislocation strain as the mechanism of phonon scattering at grain boundariesFor 50 years, we have commonly been using Casimir’s theory that describes the scattering of heat-carrying lattice vibrations (phonons) on the sample boundaries to also describe the reduction of thermal conductivity due to grain boundaries. In the frequency-independent Casimir model, phonons simply cannot travel across the boundaries, which is not the case in grain boundaries. This and a growing body of experimental and computational evidence shows that the modification of the Casimir model is necessary for grain boundaries. In this talk I will discuss our analysis of phonon scattering that controls the thermal conductivity of many common thermoelectric materials. We find that the grain boundary dislocation strain model can substitute for the Casimir model. More importantly, the two models can be distinguished at low temperature in fine-grained materials such that experimental evidence supports the grain boundary dislocation strain model. In this way, we suggest that grain boundaries themselves are best conceptualized as a collection of dislocations. Since strain and grain boundary structures can vary, we should be able to engineer grain boundaries or grain complexions (including extrinsic atoms) to disrupt phonon transport without harming electron transport.
Michelle Driscoll, Northwestern University
Mind the gap: a cascade of instabilities created by rotating beads near a floorDoes a rotating bead always spin in place? Not if that bead is near a surface: rolling leads to translational motion, as well as very strong flows around the bead, even quite far away. These flows strongly couple the motion of nearby microrollers (rotating beads), which leads to a rich variety of collective effects. Using experiments in tandem with large-scale 3D simulations, we have shown that driving a compact group of microrollers leads to a new kind of flow instability, whose wavelength is controlled not by the driving torque or the fluid viscosity, but a geometric parameter: the microroller's distance above the container floor. Furthermore, under the right conditions, stable, compact clusters we term "critters" can emerge from the unstable interface. Our simulations and experiments suggest that these critters are a stable state of the system, move much faster than individual rollers, and quickly respond to a changing drive. We believe that critters are unique in that they are clusters which form only with hydrodynamic interactions; no interparticle potentials are needed to create these structures. Furthermore, as compact, self-assembled structures which can easily be remotely guided, critters may offer a promising tool for microscopic transport.
Video Rate Atomic Force Microscopy Workshop
MRSEC and Asylum Research (Oxford Instruments)This informative free workshop will include lectures and hands-on demonstrations for researchers who want to better understand how AFM can capture dynamic processes at the nanoscale. Topics will specifically cover video-rate AFM and the latest innovations for electrochemistry and nanomechanics / mechanobiology applications. The workshop is ideal for those that have AFM experience, as well as those who would like to learn more about incorporating AFM into their research. Registration is free, however, due to limited seating, all attendees must register.
Bozhi Tian - Department of Chemistry - The University of Chicago
Physical Biology and Material Dynamics at Hard/Soft InterfacesAlthough there are numerous studies on either hard or soft materials, our understanding of the fundamentals at hard/soft interfaces has been limited. As different types of energy (such as electrostatic, mechanical, thermal, and chemical energies) display diverse scaling behaviors and can converge, an appropriate selection of the length scale is critical for promoting new scientific discoveries across these interfaces. My group integrates material science with biophysics to study several hard/soft interfaces. We synthesize new materials and probe interfacial dynamics, with particular focus at the sub-micrometer and sub-cellular length scales. Our unique and extensive contributions have: (1) enabled non-genetic, freestanding, and semiconductor-based biological modulation; (2) revealed new dynamic aspects of liquid alloy droplets in semiconductor synthesis; and (3) exploited the dynamic behaviors of minerals or granular materials in polymeric matrices.
Toshikaze Kariyado, National Institute for Materials Science, Tsukuba
Designing Topological States in Graphene with Nano HolesGapping out Dirac cones in honeycomb lattice model has been playing key roles in finding new topological phases of matter, like Haldane’s seminal work on quantum anomalous Hall effect (QAHE) or Kane-Mele’s work on quantum spin Hall effect (QSHE). Note, however, that QAHE and QSHE require magnetism (time-reversal symmetry breaking) or spin-orbit coupling (SOC), respectively. A possible and magnetism/SOC free method to have finite gap in graphene is to introduce regularly aligned holes into a graphene sheet . (Or, to make graphene antidot lattice, aka graphene nanomesh.) Here, we analyze the electronic structures of graphene nanomeshes in terms of topology . Interestingly, it is found that a nanomesh where holes form triangular lattice and a nanomesh where holes form honeycomb lattice are topologically distinct with each other. The topological nontriviality is confirmed by explicitly calculating interface tates between the two regions of triangular and honeycomb nanomeshes, whose band structure has counterpropagating nature resembling to the one for helical edge states in QSH states. In addition to the interface state, we also diagnose the topology of the system by symmetry of the wave function, i.e., by a topological crystalline insulator viewpoint. It is demonstrated that the parity
index against 2D spatial inversion is a key quantity to detect topology in our system.
Chad M. Rienstra, University of Illinois Urbana-Champaign
Molecular Fibrils and Sponges: Insights into Parkinson's Disease and Antifungal Drugs from NMR SpectroscopyMy research addresses fundamental questions about molecular structure and function of non-crystalline solids utilizing magic-angle spinning solid-state NMR spectroscopy along with a range of other chemical and biophysical methods. In this seminar, I will describe our recent results reporting the first high-resolution structure of full length alpha-synuclein fibrils, the protein most abundant in Lewy bodies and implicated in Parkinson’s disease propagation, and the mode of action of the antifungal drug amphotericin B, which binds and extracts sterols from lipid bilayers.
Vedika Khemani, Harvard University
Sihong Wang, Postdoctoral Fellow, Department of Chemical Engineering, Stanford University
Merging Electronics with Living Systems: From Intrinsically Stretchable Materials and Devices to Mechanical Energy HarvestingThe vast amount of biological mysteries and biomedical challenges faced by human provide a prominent drive for seamlessly merging electronics with biological living systems (e.g. human bodies) to achieve long-term stable functions. Towards this trend, the main bottlenecks are the huge mechanical mismatch between the current form of rigid electronics and the soft biological tissues, as well as the limited lifetimes of the battery-based power supplies.
In this talk, I will first describe a new form of electronics with skin-like softness and stretchability, which is built upon a new class of intrinsically stretchable polymer materials and a new set of fabrication technology. As the core material basis, intrinsically stretchable polymer semiconductors have been developed through the physical engineering of polymer chain dynamics and crystallization based on the nanoconfinement effect. This fundamentally-new and universally-applicable methodology enables conjugated polymers to possess both high electrical-performance and extraordinary stretchability. Then, proceeding towards building electronics with this new class of polymer materials, the first polymer-friendly manufacturing process has been designed for large-scale intrinsically stretchable transistor arrays—the core device building-blocks for electronics. As a whole, these renovations in the material basis and technology foundation have led to the realization of circuit-level functionalities for the processing of biological signals, with unprecedented mechanical deformability and skin conformability. In the second part of the talk, I will introduce the invention and development of triboelectric nanogenerators as a new technology for mechanical energy harvesting, which provides a solution for sustainably powering electronics. The discussion will span from the establishment of basic operation mechanisms, the design strategies of material and device structure towards high energy conversion efficiency, to the hybridization with Li-ion batteries for effective energy storage. Equipping electronics with human-like form-factors and biomechanically-driven power supplies has opened a new paradigm for wearable and implantable bio-electronic tools for biological studies, personal healthcare, medical diagnosis and therapeutics.
Pedro Lopes, Sherbrooke
Signatures of the chiral anomaly in phonon dynamicsThe past decade of condensed matter physics has put a great weight in the importance of topological phenomena. Our particular interest here are Weyl semi-metals. Differently from its gapped insulating and superconducting topological cousins, the low-energy physics of Weyl semi-metals is not restricted to its surface, with bulk electronic properties being governed by linearly dispersing bands. An effective 3+1D Lorentz symmetry thus develops in these materials, settling Weyl semi-metals as prime candidates for comparative and analogue high-energy physics studies. In this context, we consider the phenomenon of the chiral anomaly, which in the high-energy context controls the decay rates of neutral pions into photons. In condensed matter, this phenomenon is traditionally understood to give rise to novel electronic transport phenomenology, whose verification, however, has been seen with controversy in the literature. To avoid such controversies, we present in this talk a detour from transport phenomena and show that optical properties of lattice oscillations carry singular signatures of the chiral anomaly. These come about by means of a novel type of polariton effect and are restricted only to certain classes of lattice oscillations in mirror symmetry broken Weyl semi-metals. Our proposed signatures of the condensed matter chiral anomaly then provide a robust alternative to transport while simultaneously constraining the systems to be studied, helping guide experimental efforts."
Peng Liu, University of Pittsburgh
Computational Studies of Functionalization of C-H, C-C Bonds and Olefins
Hui Cao, Yale University
Mesoscopic OpticsRandom scattering of light, e.g., in paint, cloud and biological tissue, is a common process of both fundamental interest and practical relevance. The interference of multiply scattered waves leads to remarkable phenomena in mesoscopic physics such as Anderson localization and universal conductance fluctuations. In applications, optical scattering is the main obstacle to imaging or sending information through turbid media. Recent developments of adaptive wavefront shaping in optics enabled imaging and focusing of light through opaque samples. By selective coupling to high or low transmission eigenchannels, we varied the transmission of a laser beam through a highly scattering system by two orders of magnitude, and drastically changed the energy density distribution inside the system. Furthermore, we utilized the multiple scattering of light in a random structure to realize a chip-scale spectrometer. The speckle pattern is used as a fingerprint to recover an arbitrary spectrum. Such a spectrometer has good spectral resolution and wide frequency range of operation.
Xiaoyuan (Shawn) Chen, National Institute of Biomedical Imaging and Bioengineering
Cancer NanotheranosticsTheranostics (Rx/Dx) aims to develop molecular diagnostic tests and targeted therapeutics with the goals of individualizing treatment by targeting therapy to an individual's specific disease subtype and genetic profile. It can be diagnosis followed by therapy to stratify patients who will likely respond to a given treatment; it can also be therapy followed by diagnosis to monitor early response to treatment and predict treatment efficacy; it is also possible that diagnostics and therapeutics are co-developed (nanotheranostics). This talk will give examples of how to assemble both inorganic and organic/polymeric materials for multimodality cancer imaging and drug/gene delivery.
Ivan I Smalyukh, University of Colorado Boulder
Topological Solitons and Other Knots in Soft MatterTopologically nontrivial fields and vortices frequently arise in classical and quantum field theories, plasmas, optics, cosmology, hard condensed matter and atomic systems. On the other hand, soft matter systems, such as colloids and liquid crystals, offer the complexity in degrees of freedom and symmetries that allow for probing topologically analogous phenomena on experimentally accessible scales. In my lecture, I will discuss how surfaces of colloidal knots and handlebodies interact with the liquid crystalline molecular alignment fields and how topological knot solitons can emerge as static field configurations within the chiral colloidal ferromagnets [1-5]. I will show how such synergistic combinations of topology and self-assembly paradigms can emerge as an exciting scientific frontier of topological soft matter.
The Tuesday JFI Seminar - Prof. Tzahi Cohen-Karni, Departments of Biomedical Engineering and Material Science & Engineering, Carnegie Mellon University
Multiscale Topological Design of Biological Interfaces to Novel NanomaterialsMy research team efforts focus on developing a new class of nanoscale materials and novel strategies for the investigation of biological entities at multiple length scales, from the molecular level to complex cellular networks. Our highly flexible bottom-up nanomaterials synthesis capabilities allow us to form unique hybrid-nanomaterials. Recently, we have demonstrated highly controlled synthesis of 3D out-of-plane single- to few-layer fuzzy graphene (3DFG) on a Si nanowire (SiNW) mesh template. By varying graphene growth conditions, we control the size, density, and electrical properties of the NW templated 3DFG (NT-3DFG). This flexible synthesis inspires formation of complex hybrid-nanomaterials with tailored optical and electrical properties to be used in future applications such as bio-sensing, and energy conversion and storage.
Our current efforts target the limits of cell-nanodevices interfaces using nanosensor based array assembled in 3D with subcellular spatial resolution (<5μm) and μsec temporal resolution. Our approach enables simultaneous multiplexed electrical measurements to directly monitor the development of electrical activities of microscale tissues (μtissues, ca. 100-400μm) which are engineered from induced pluripotent stem cell (iPS) derived cardiomyocytes or pancreatic islets isolated from mice. In summary, the exceptional synthetic control and flexible assembly of nanomaterials provide powerful tools for fundamental studies and applications in life science, and open up the potential to seamlessly merge either nanomaterials-based platforms or unique nanosensor geometries and topologies with cells, fusing nonliving and living systems together.Host: Bozhi Tian, 2-8749 or via email to email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Itamar Kimchi (MIT)
Valence Bond Entanglement in Random Quantum MagnetsSeveral longstanding problems in quantum magnetism concern quenched disorder. I will discuss the role of random exchange energies in spin-1/2 magnets where magnetic frustration promotes the formation of entangled valence bonds. With weak disorder we find that the destruction of a valence-bond solid phase leads inevitably to the nucleation of topological defects carrying spin-1/2 moments. This renormalizes the lattice into a strongly random network of defect spins which yields interesting low-energy excitations. With stronger disorder we find a related instability for a short-ranged valence bond glass. Motivated by these results we conjecture Lieb-Schultz-Mattis-type restrictions on ground states for disordered magnets with spin-1/2 per statistical unit cell. We apply this theoretical study to interpret experimental results on various spin-liquid-candidate magnets including YbMgGaO4 and H3LiIr2O6. Specific heat, susceptibility, thermal conductivity and dynamical structure factor, as well as their behavior in a magnetic field, are predicted and compare favorably with existing measurements. In particular I will show how recent observations of data collapse in T/H can be understood in terms of scaling laws derived from the theory.
Organizer: Kadanoff Center seminars
Oleg Gang, Columbia University
Programmable Nano-Systems: Form Designed Architectures to Controllable ProcessesOur ability to organize diverse type of nanoscale objects into the desired organizations is often a limiting factor in creating targeted nanomaterial. DNA provides powerful means for interaction encoding, and much progress was achieved recently by the field in ability to tailor DNA structures. However, it is challenging to prescribe the architecture or behavior of the entire nanoscale system as well as translate the advances of DNA assembly into material design. Our research explores novel concepts for creating targeted static and dynamic nano-architectures by bridging DNA-encoded nano-objects with structural plasticity and programmability of DNA macromolecular structures. Through establishing assembly approaches and revealing the phenomena that govern systems with DNA-encoded interactions, we develop methods for fabrication of well-defined three-dimensional lattices, two-dimensional membranes and finite-sized clusters from the multiple types of the nano-components. Our recent progress demonstrates strategy for organizing such nano-components as nanoparticles and proteins into ordered 3D arrays with engineered crystallographic symmetries, and clusters with prescribed architectures. These methods are also use to control a system dynamic behavior: structural transformation, specific triggering of desired configurations and molecular amplification. The applications of the DNA-based assembly platform for creation of optical and biomedical materials will be also discussed.
Dr. Benjamin Chapman, JILA-University of Colorado
Widely Tunable On-chip Microwave Circulator for Superconducting Quantum CircuitsThis talk discusses the design and performance of a superconducting on-chip replacement technology for ferrite circulators. The device breaks Lorentz reciprocity--the symmetry, in an electrical network under exchange of source and detector--with sequential applications of frequency conversion and delay. As frequency and time are Fourier duals, translations in these quantities do not generally commute. A signal's port of entry may therefore be encoded in the time-ordering of the frequency conversion and delay operations. Design goals for the device are set for integration with superconducting quantum circuits, where the circulator enables the routing of propagating electromagnetic signals that encode the states of quantum systems. Given the current status of quantum error-correction and architectures for quantum information processing with superconducting circuits, such as scalable non-reciprocal devices will likely be necessary for construction of a superconducting quantum computer intended to be more than a proof-of-principle.
Greg Bentsen, Stanford University
Can We Make a Black Hole in the Lab?The holographic principle tells us that certain gravitational systems, like black holes in AdS, are equivalent to conventional quantum many-body systems in one fewer dimension. A tantalizing possibility raised by this duality is the prospect of engineering artificial gravitational systems in the laboratory using controllable quantum-mechanical degrees of freedom such as cold atoms or trapped ions. Microscopic models of black holes, however, typically involve a number of exotic features, such as random infinite-range all-to-all couplings and strong chaotic behavior that are difficult to implement in experimental setups. In particular, since black holes are the fastest scramblers in nature, any quantum system that purports to contain an artificial black hole must scramble information at or near the Maldacena-Shenker-Stanford chaos bound. These are formidable challenges, but I will show in this talk how we are making progress toward being able to both simulate and measure systems that exhibit some of these characteristic features in the laboratory. While we are still a long way from being able to look behind event horizons or see artificial Hawking radiation, these preliminary efforts point favorably toward implementations of artificial gravity in the future, and in the meantime should prove useful for experimental studies of exotic many-body dynamics, closed-system thermalization, and quantum chaos.
Professor Alison Fout, University of Illinois at Urbana-Champaign
Ligand Influences on Base Metals for Multi-Electron TransformationsMulti-electron transformations featuring base metals are both particularly challenging and interesting. A series multi-dentate ligand frameworks containing both hydrogen bond donating and accepting moieties in the secondary coordination sphere have been synthesized and reactivity will be described. These transformations feature the reduction of inorganic oxyanions which have long been touted for their inertness since these species are generally considered to be non-complexing anions, poor nucleophiles and kinetically inert to oxidation and reduction. Likewise, using a strong-field bis(carbene) ligand platform we have been able to demonstrate two-electron redox reactions on both cobalt and nickel complexes to access relatively rare organometallic species that are capable of a variety of catalytic transformations.
How can more ions in a liquid give less ionic screening?Bring food at noon
Hear puzzle at 12:15
Paul McEuen, Cornell University
The Future of SmallFifty years ago, the Nobel Prize-winning physicist Richard Feynman claimed that a revolution was underway where information, computers, and machines would be shrunk to impossibly small dimensions. History has proven him mostly right: Moore’s law has brought Feynman’s dreams to fruition in the realms of data and computing, giving us cell phones, the internet, and artificial intelligence. But the third leg of Feynman’s dream, the miniaturization of machines, is only just getting underway. Can we create functional, intelligent machines at the smallest scales? And if so, how? In this talk, I’ll take a look at some of the approaches being explored, including our group’s forays into combining electronics, paper arts, and functional 2D materials to create a new generation of smart, active nanomachines.
Joaquin Rodriguez-Lopez, University of Illinois
Titrating Reactive Intermediates at Operating Water-Splitting Photoanodes: Elucidating Spatial, Temporal, and Chemical HeterogeneitieChemical transformation at the semiconductor/electrolyte interface for processes in energy, water remediation, and catalysis is enabled by the complex interplay of photogenerated charge carriers and surface chemical intermediates. I will describe unique electroanalytical tools developed in my laboratory for quantifying chemical processes and intermediates on water oxidation (photo)anodes with high temporal and spatial resolution, as well as chemical specificity. Our powerful toolset is based on scanning electrochemical microscopy (SECM). Using a combination of product collection modes (O2, H2O2), redox mediator-based measurements, and transient redox titrations we are gaining quantitative insight into the role of local perturbations in conditioning, controlling and encoding reactivity on photoelectrochemical interfaces. My discussion will include the inspection of electrode processes on wide-bandgap and solar photoelectrodes, as well as in nano-patterned surfaces and electrocatalysts. New in situ methods capable of approaching the surface dynamics of operating photocatalysts are required to provide a new leap in the design of photochemical interfaces for important processes in water environmental and energy applications.
Paul McEuen, Cornell University
Listening to a thermal guitar: Hearing (and seeing) the vibrations of a carbon nanotubeCarbon nanotubes reside at the boundary of macroscopic mechanics and polymer physics. They can be made into guitar-string resonators and operated in vacuum, yet they are flexible enough that thermal fluctuations completely alter their properties. Here we show that individual carbon nanotubes can be picked up and strained with micron-sized tweezers, allowing us to study these novel fluctuating strings in a variety of new ways. Experiments include recording the “sound” of the thermal vibrations of a nanotube and “seeing” its real-time motion with light. We find many surprising results, including strong coupling between vibrational modes and very long intrinsic dissipation times, as well as many unresolved mysteries. These results open the door to the science of thermally-fluctuating strings in the underdamped limit, with many opportunities for theory, computation, and experiment.
Boris Spivak, University of Washington
Anomalous metals-failed superconductorsThe observation of metallic ground states in a variety of two-dimensional electronic systems poses a fundamental challenge for the theory of electron fluids. I willl analyze evidence for the existence of a regime, which we call the anomalous metal regime," in diverse 2D superconducting systems driven through a quantum superconductor to metal transition by tuning physical parameters such as the magnetic field,the gate voltage in the case of systems with a MOSFET geometry, or the degree of disorder. The principal phenomenological observation is that inthe anomalous metal,as a function of decreasing temperature, the resistivity first drops as if the system were approaching a superconducting ground state, but then saturates at low temperatures toa value that can be orders of magnitude smaller than the Drude value. The anomalous
metal also shows a giant positive magneto-resistance. Thus, it behaves as if it were a failed superconductor." This behavior is observed in a broad range of parameters. We moreover exhibit, by theoretical solution of a model of superconducting grains embedded in a metallic matrix, that as a matter of principle such anomalous metallic behavior can occur in the neighborhood of a quantum superconductor-metal transition. However,
we also argue that the robustness and ubiquitous nature of the observed phenomena are dicult to reconcile with any existing theoretical treatment, and speculate about the character of a more fundamental theoretical framework.
Marcos González-Gaitán, PhD, University of Geneva
Asymmetric signaling endosomes in asymmetric divisionSandwiches at 11:45; remember to bring a cup for coffee or tea.
Professor William Shih, Harvard University
DNA-origami BarrelsDNA origami, in which a long scaffold strand is assembled with a large number of short staple strands into parallel arrays of double helices, has proven a powerful method for custom nanofabrication. Although diverse shapes in 2D are possible, the single-layer rectangle has proven the most popular, as it features fast and robust folding and modular design of staple strands for simple abstraction to a regular pixel surface. Here we introduce a barrel architecture, built as stacked rings of double helices, that retains these appealing features, while extending construction into 3D. We demonstrate hierarchical assembly of a 100 megadalton barrel that is ~90 nm in diameter and ~270 nm in height, and that provides a rhombic-lattice canvas of a thousand pixels each, with a pitch of 9 nm, on its inner and outer surfaces. Complex patterns rendered on these surfaces were resolved using up to twelve rounds of exchange PAINT super-resolution fluorescence microscopy. We envision these structures as versatile nanoscale pegboards for applications requiring complex 3D arrangements of matter.
Persons with a disability may call (773)795-5843 in advance for assistance.
Rifts in Rafts: the fracture of monolayers on fluid interfacesEat 12:00
Nadya Mason, The University of Illinois at Urbana-Champaign
In Proximity to Novel Physics: Topological Insulators coupled to Superconductors
Topological insulators (TI’s) are materials that are insulators in their interiors, but have unique conducting states on their surfaces. They have attracted significant interest as fundamentally new electronic phases having potential applications from dissipationless interconnects to quantum computing. In particular, coupling the surface state of a TI to an s-wave superconductor is predicted to produce the long-sought Majorana quasiparticle excitations, which could play a role in solid-state implementations of a quantum computer. A requisite step in the search for Majorana fermions is to understand the nature and origin of the supercurrent generated between superconducting contacts and a TI. In this talk, I will discuss TI-superconductor junctions, focusing on transport measurements taken as the chemical potential is moved from the bulk bands into the band gap, or through the true topological regime characterized by the presence of only surface currents.
Eric Hudson, University of California, Los Angeles
Zen and the Art of Atomic PhysicsIn the Ten Bulls tradition, the fifth stage of Zen is reached when the practitioner has caught and tamed the wild bull. This is roughly the state of atomic physics. The atom has been tamed. It can be prepared in a single quantum state, its evolution coherently controlled, and its entanglement generated at will. As such, many new quantum-assisted technologies and fundamental physics measurements have resulted and a quantum revolution is well underway that promises to touch almost every aspect of our lives. By the seventh stage of Zen, the Bull has transcended and is no more. This again may be paralleled in atomic physics as the atom is being replaced with richer quantum systems such as molecules, whose internal degrees of freedom provide new oppurtunities for quantum science and technology.
In this talk, I will briefly review the science and technology that have come from atom taming and then discuss our efforts to tame other bulls: polar molecular ions and atomic nuclei.
Haim Diamant, Tel Aviv University
Hyperuniform dynamic structures of forced colloidsSeveral materials have been found in recent years to exhibit "hyperuniformity", their constituent particles being distributed in a disordered but correlated configurations such that density fluctuations are strongly suppressed. Examples are sheared suspensions and emulsions, and random jammed packings of particles. In those systems the hyperuniform structure appears as a static absorbing state. Suppression of density fluctuations appears also in thermodynamic and dynamic systems which sample many spatial configurations. Examples are electrolytes and suspensions of forced colloids. We relate the statistical hyperuniformity in these systems to conservation laws and long-range interactions. We demonstrate in detail the suppression of density and velocity fluctuations in forced suspensions of asymmetric objects. In this case we have identified the basic mechanism leading to hyperuniformity. We argue that for certain object shapes the same mechanism can act in the opposite direction, destabilizing the dynamics.
The 1st Tuesday JFI Colloquium - CLOSS LECTURE - Prof. Jonathan A. Rogers, Department of Chemistry, Simpson/Querrey Institute - Northwestern University
Materials for Bioresorbable ElectronicsA remarkable feature of modern integrated circuit technology is its ability to operate in a stable fashion, with almost perfect reliability, without physical or chemical change. Recently developed classes of electronic materials create an opportunity to engineer the opposite outcome, in the form of devices that can dissolve in water to yield completely benign end products. The enabled applications include zero-impact environmental monitors, 'green' consumer electronics and temporary biomedical implants - none of which is possible with technologies that exist today. This talk describes foundational concepts in chemistry, materials science and assembly processes for bioresorbable electronics in 2D and 3D architectures, the latter enabled by approaches that draw inspiration from the ancient arts of kirigami and origami. Wireless sensors of intracranial temperature, pressure and electrophysiology designed for use in treatment of traumatic brain injury and nerve stimulators as ‘electronic medicines’ for accelerated neuroregeneration provide application examples.For further information please contact Brenda Thomas at 773-702-7156 or by email at email@example.com. You may also contact the Host, Valerii Sharapov at 773-610-7726 or via email to firstname.lastname@example.org.
Etienne Caron, ETH Zurich
Decoding cancer antigenomes by SWATH-MS for effective immunotherapiesOver the past years at ETH-Zurich, Switzerland, I have contributed to the development of an innovative mass spectrometry (MS) technology, known as SWATH-MS, which enables robust quantitative measurements of proteins and MHC-associated peptides across large sample cohorts. During this seminar, I will show how a similar technology has been successfully deployed to demonstrate that tumor-specific neoantigens do exist as physical molecules in cancer and represent key targets of T cells in response to checkpoint immunotherapy. In addition, I will show how SWATH-MS permits quantification of protein interaction dynamics in primary T cells. Finally, I will present my long-term vision and how to take MS technology towards highly precise and efficient cancer immunotherapies.
Dr. Monika Aidelsburger, Ludwig-Maximilians-Universität München
Floquet engineering with ultracold atoms in optical latticesFloquet engineering is an important tool for the engineering of novel band structures with interesting properties that go beyond those offered by static systems. Recently, Floquet systems have enabled the generation of Bloch bands with non-trivial topological properties, such as the Hofstadter and Haldane model. This led to the observation of chiral Meissner currents and the first Chern-number measurements with charge-neutral atoms.
Besides this success studies of many-body phases in driven systems remains experimentally challenging in particular due to the interplay between periodic driving and interactions. In a driven system energy is not conserved which can lead to severe heating. In order to find stable parameter regimes for the generation of driven many-body phases it is essential to develop a deeper understanding of the underlying processes.
In this talk, I briefly review recent experimental advances in the generation of topological band structures in the non-interacting regime using Floquet engineering and present first studies of interacting atoms in driven 1D lattices.
Professor Ian Tonks, University of Minnesota - Twin Cities
Ti-Catalyzed Nitrene Transfer Reactions: Harnessing the TiII/TiIV Redox Couple for New Organic MethodsTitanium is an ideal metal for green and sustainable catalysis—it is the 2nd most earth-abundant transition metal, and the byproducts of Ti reactions (TiO2) are nontoxic. However, a significant challenge of utilizing early transition metals for catalytic redox processes is that they typically do not undergo facile oxidation state changes because of the thermodynamic stability of their high oxidation states. We have recently discovered that Ti imidos (LnTi=NR) can catalyze oxidative nitrene transfer reactions from diazenes via a TiII/TiIV redox couple, and are using this new mode of reactivity to develop a large suite of practical synthetic methods. In this talk, our latest synthetic and mechanistic discoveries related to Ti nitrene transfer catalysis will be discussed, including new synthetic methods for the modular, selective construction of pyrroles via [2+2+1] cycloaddition of alkynes with Ti nitrenes and alkynes, as well as new methods for catalytic oxidative carboamination of other unsaturated organics by Ti nitrenes.
Molecular motors force themselves into "stacks"; does this help?Bring food at noon.
Story time starts at 12:15
Dan Holz, The University of Chicago
GW170817: Hearing and seeing a binary neutron star mergerWith the discovery of GW170817 in gravitational waves, and the discovery of an associated short gamma-ray burst, and the discovery of an associated optical afterglow, we have finally entered the era of gravitational-wave multi-messenger astronomy. I will discuss LIGO/Virgo's detection of this binary coalescence, and explore some of the scientific implications, including confirmation of the kilonova model and implications for the origin of gold and platinum in the universe, tests of general relativity, and the first standard siren measurement of the Hubble constant. GW170817 represents a momentous development in gravitational-wave astronomy, and the birth of gravitational-wave cosmology.
IME Distinguished Colloquium Series: Naomi Halas, Rice University
Plasmonics: from noble metals to sustainabilityMetallic nanoparticles, used since antiquity to impart intense and vibrant color into materials, have more recently become a central tool in the nanoscale manipulation of light. This interest has led to a virtual explosion of new types of metal-based nanoparticles and nanostructures of various shapes and compositions, and has given rise to new strategies to harvest, control, and manipulate light based on metallic nanostructures and their properties. As one begins to assemble metallic nanoparticles into useful building blocks, a striking parallel between the plasmons- the collective electronic oscillations- of these structures and wave functions of simple quantum systems is universally observed. Clusters of metallic nanoparticles behave like coupled oscillators, introducing effects characteristic of systems as diverse as radio frequency transmitters and coupled pendulums into light-driven nanoscale structures. Plasmons decay by producing hot electrons, a property appearing to be highly useful in applications ranging from photodetection to photocatalysis. In particular, new “antenna-reactor” photocatalysts can be designed by combining plasmonic nanoparticles with directly adjacent catalytic particles or materials, rendering the heterocomplexes photocatalytic. While our scientific foundation for the field of Plasmonics has been built on nanoparticles consisting of noble and coinage metals, more recently we have begun to question whether the same, or similar, plasmonic properties can also be realized in more sustainable materials. Aluminum, the most abundant metal on our planet, can support high-quality plasmonic properties across the visible region of the spectrum, enabling practical large-area and cost-effective plasmonic applications such as flat-panel displays, robust colorimetric sensors, and selective ethylene synthesis. Graphene is an outstanding active plasmonic material, however, it can be tuned from the infrared into the visible region of the spectrum only by miniaturization to the true molecular limit. Sustainable plasmonic materials allow us to envision entirely new applications, for example, direct solar distillation that can provide drinkable water, entirely independent of grid-based electrical power.
Jens Eggers , University of Bristol
Pair creation, motion, and annihilation of topological defects in 2D nematicsWe present a novel framework for the study of disclinations in two-dimensional active nematic liquid crystals, and topological defects in general. The order tensor formalism is used to calculate exact multi-particle solutions of the linearized static equations inside a planar uniformly aligned state, so that the total charge has to vanish. Topological charge conservation then requires that there is always an equal number of $q=1/2$ and $q=-1/2$ charges. Starting from a set of hydrodynamic equations, we derive a low-dimensional dynamical system for the parameters of the static solutions, which describes the motion of a half-disclination pair, or of several pairs. Within this formalism, we model defect production and annihilation, as observed in experiments. Our dynamics also provide an estimate for the critical density at which production and annihilation rates are balanced.
The Tuesday JFI Seminar - Prof. Michael Hagan, Department of Physics and Quantative Biology, Brandeis University
Unexpected Ordered Phases in Active MatterActive matter describes systems whose constituent elements consume energy to generate motion, and are thus intrinsically far-from equilibrium. I will describe computer simulations of two recently developed active matter systems. (1) Self-propelled colloids with repulsive interactions and no aligning interactions are a minimal model active matter system. We and others have shown that, even when particles experience only repulsive interactions, this system undergoes a phase coexistence that mimics the equilibrium phase separation of attractive colloids. I will present a simple kinetic theory that describes the dynamics of phase separation, resulting in a framework analogous to equilibrium classical nucleation theory. (2) Active nematics are liquid crystals which are driven out of equilibrium by energy-dissipating active stresses. The ordered nematic state is unstable to the proliferation of topological defects, which undergo birth, streaming dynamics, and annihilation to yield a seemingly chaotic dynamical steady-state. In this talk, I will show that order emerges from this chaos, in the form of heretofore unknown broken-symmetry phases in which the topological defects themselves undergo orientational ordering. Time permitting, I will also show that active nematics are remarkable insensitive to topological constraints even under high confinement
Professor Anna Mapp, University of Michigan
From Fuzzy to Function in Gene ActivationWithin the chemical space of protein-protein interactions (PPIs), transient, modest affinity PPIs play a central role in a variety of cellular functions, including protein folding and transcription. Dysregulation of this class of PPIs is at the heart of diseases ranging from cancer to neurodegenerative disorders. For example, in several types of AML, leukemogenesis is dependent upon the loss of one transcriptional activator-coactivator interaction (MLL-p300) and the maintenance or amplification of a second (cMyb-p300). Despite their importance and their prevalence, such transient and modest affinity PPIs are often classified as ‘undruggable’, with few successful strategies for small molecule modulator discovery. A significant challenge has been that the binding partners often have significant disorder and are thus difficult to characterize structurally alone or in complex. A strategy for the identification of chemical co-chaperones that capture particular conformations of transcriptional coactivators and in doing so selectively modulate the assembly of transcriptional activator-coactivator complexes in vitro and in cells will be described.
Professor David J. Michaelis, Brigham Young University
Synthetic Applications of Enzyme-Inspired CatalystsOur research program is focused on using nature as an inspiration for the development of novel catalytic tools for organic synthesis. In the active site of enzymes, multiple metal centers often cooperate to lower the barrier to oxidative and reductive processes, thus enabling efficient catalysis in very challenging organic transformations. Our group is designing and developing heterobimetallic catalysts where metal-metal interactions and cooperativity can lead to enhanced catalysis and novel transformations. Our efforts have led to the development of Pd–Ti and Pt–Ti catalysts that display exceptional reactivity in allylic amination and cycloisomerization reactions respectively. This seminar will describe our current efforts to develop chiral Ti–M complexes for enantioselective catalysis and heterobimetallic M–Ni complexes for nickel catalysis applications. In separate pursuits, we have also developed peptide-based multifunctional catalysts that enable enzyme-like cooperative catalysis. The small peptide scaffold brings multiple non-natural catalysts into close proximity, enabling faster catalyst turnover, novel selectivity based on substrate binding and proximity, and the development of novel two-catalyst transformations. The development and use of these catalysts to achieve novel reaction rates and selectivity and for new reaction discovery will also be presented.
how curved creases turn flat sheets topologicalBring food at noon.
Story time starts at 12:15
Jia Liu, Shriram Center for Bioengineering and Chemical Engineering, Department of Chemical Engineering, Stanford University
Soft bioelectronics for tissue and organ interfaces: from tissue-like electronics to genetically-targeted biosynthetic electrodesRapid progress in soft materials and electronics has blurred the distinction between man-made devices and biological systems. Seamless integration of electronic devices with living systems could contribute substantially to basic biology as well as to clinical diagnostics and therapeutics through tissue-electronics interfaces. In this presentation, I will first introduce a syringe-injectable tissue-like mesh electronics for merging soft nanoelectronic arrays and circuits with the brain in three-dimension (3D). The injectable mesh electronics has micrometer feature size and effective bending stiffness values similar to neural tissues. These unprecedented features lead to the gliosis-free and 3D interpenetrated electronics-neuron network, enabling the chronically stable neuron activity recording at single-neuron resolution in behaving animals. Second, I will describe a fully stretchable electronic sensor array through the development of multiple chemically-orthogonal and intrinsically stretchable polymeric electronic materials. The fully stretchable sensor array has modulus similar to biological tissues, allowing an intimate mechanical coupling with heart for a stable and anatomically precise electrophysiological recording. Its application for high-throughput and high-density mapping of 3D cardiac arrhythmogenic activities on the porcine model with a chronic atrial fibrillation will be discussed. Third, I will present a fundamentally new approach for a direct formation of electrical connections with genetically-targeted cells. This approach is accomplished through the convergence of genome engineering, in situ enzymatic reaction and polymer chemistry. These genetically-targeted electrodes are inherently assembled to the subcellular-specific region of neurons throughout the intact functional neural tissue and in stem cell-derived human brain organoids. Importantly, this system also enables the cellular-resolution tuning of local neuronal activity and bridging of brain regions to external devices for the targeted recording. Finally, I will briefly discuss the prospects for future advances in soft bioelectronics to overcome challenges in neuroscience and cardiology through the development of “cyborg animals” with single-cell resolution and cell-type specificity.
Alberto Fernandez-Nieves, Georgia Tech
Fire-ant fluids: expansion, mechanics and wavesMotivated by classic thermodynamic experiments with dilute fluids, we explore the free and constrained expansion of fire-ant aggregations. In the latter case, we confine the ants to 2D vertical columns; hence, as the ants expand, they do work against the gravitational field. Surprisingly, we often observe the spontaneous generation of density waves; these propagate at a speed that depends on both the width and the amplitude of the wave, and occur cyclically. We also perform experiments in horizontal cells and find that the ants exhibit activity cycles, where the density homogeneity and mechanical properties of the aggregation change with activity. We believe that these cycles together with the large ant densities in our vertical columns are responsible for the generation of the observed waves. Finally, since the average ant density is larger at the bottom of the vertical column than a the top, we follow our temptation and attempt at interpreting the results in lieu of sedimentation equilibrium to seek for an equation of state. Despite our results are still highly preliminary, they provide interesting phenomenology that could perhaps be seen in active systems other than fire-ant aggregations.
Prof. Anders Niklasson, Los Alamos National Laboratory, Theoretical Division
Next Generation Quantum Based Molecular DynamicsQuantum based molecular dynamics (QMD) simulations provide a highly powerful, but computationally expensive, multidisciplinary tool to predict, understand and design materials and processes directly from the first principles of quantum physics. QMD simulations ideally represent an almost universal approach to study a wide range of problems in chemistry, molecular biology and materials science. Merging QMD with future extreme-scale computing holds the promise of a major paradigm shift in computer-driven science. Unfortunately, this potentially revolutionary opportunity will never be realized without a radical re-design of established QMD simulation schemes to overcome a number of interconnected fundamental problems. Over the last decade we have worked on the development of a new generation QMD that avoids several computational bottlenecks and obstacles inherent to previous methods. For the first time, QMD simulation is now emerging as a practically feasible approach in simulations of +100,000 atoms — representing a competitive alternative to classical polarizable force field models. I will present the background and the underlying theoretical framework as well as future challenges and opportunities.
Po-Chun Hsu, Postdoctoral Researcher, Department of Mechanical Engineering, Stanford University
Light- and Heat-Managing Nanomaterials for Personal Health and Energy EfficiencyIn this talk, I will present several nanomaterials that can manage photons and heat transfer to enhance building energy efficiency and personal health in an unconventionally effective way. The first part introduces the concept of personal thermal management. Personal thermal management focuses on controlling the temperature around the human body rather than the whole space, so it can provide the same thermal comfort with lower energy demand and shorter turnaround time. For passive personal thermal management, i.e., no additional energy input, the key parameter is the heat transfer coefficient of the clothing. Thermal radiation, as the dominant heat transfer pathways for the indoor scenario, is an extremely effective yet less explored tuning knob. I will demonstrate infrared-reflective metallic nanowires textile for heating and infrared-transparent nanoporous polyethylene (nanoPE) for cooling, both of which achieve superior heating/cooling properties than traditional textiles. The nanoPE textile is further used to fabricate the dual-mode textile that can switch between heating and cooling modes by reversing the textile. This interesting dual-modality can expand the wearers’ adaptability to ambient temperature fluctuation to maintain thermal comfort and potentially prevent cardiovascular and respiratory diseases. The second part introduces transparent electrodes and electrochromic windows. The transparent electrode is the key component for many optoelectronic devices, including photovoltaic cells, touchscreen displays, and smart windows. Transparent electrodes with both high optical transparency and low electrical resistance will greatly benefit the device performances. For building energy efficiency, smart windows are capable of changing its color to control solar heat gain by applying only a few volts of electricity, and the energy demand for indoor temperature control can be reduced. I will introduce metal nanofiber transparent electrodes with the superior electrical and optical properties and durability which can achieve electrochromic windows with high switching speed, mechanical bendability, and long cycle life. Fabricated by electrospinning and various metallization techniques, the metal nanofibers are infinitely long and well-connected and have minimal wire-to-wire junction resistance.
Professor Hanadi Sleiman, McGill University
DNA Nanostructures for Cellular Delivery of TherapeuticsDNA nanotechnology can assemble materials on the nanoscale with exceptional predictability and programmability. In a sense, this field has reduced the self-assembly space into a simple ‘language’ composed of four letters (A, T, G, C). Nature, on the other hand, relies on many more supramolecular interactions or ‘languages’ to build its functional structures. Over the last 50 years, supramolecular chemistry has taken advantage of these interactions to assemble materials with highly diverse structures and functions.
This talk will describe our efforts to merge the field of supramolecular chemistry with DNA nanotechnology. This approach results in new motifs and functionalities that are unavailable with base-pairing alone. Starting from a minimum number of DNA components, we create 3D-DNA host structures, such as cages, nanotubes and micelles, that are promising for targeted drug delivery. These can encapsulate and selectively release drugs and materials, and accomplish anisotropic 3D-organization. We find that they resist nuclease degradation, silence gene expression to a significantly greater extent than their component oligonucleotides and have a favorable in vivo distribution profile. We designed a DNA cube that recognizes a cancer-specific gene product, unzips and releases drug cargo as a result, thus acting as a conditional drug delivery vehicle, as well as DNA structures that bind to plasma proteins with low nanomolar affinities.
We will also describe a method to ‘print’ DNA patterns onto other materials, thus beginning to address the issue of scalability for DNA nanotechnology. Finally, we will discuss the ability of small molecules to reprogram the assembly of DNA, away from Watson-Crick base-pairing and into new motifs.
Persons with a disability may call (773) 795-5843 in advance for assistance.
Fengcheng Wu, Argonne National Lab
Theory on nematic odd-parity superconductivityTopological superconductors represent a paradigmatic system where topological effects and many-body interactions can have an interesting interplay. Various recent experiments have indicated that superconductivity in CuxBi2Se3 and related materials is nematic with rotational symmetry breaking. This nematic superconductivity is consistent with an odd-parity pairing. Therefore, CuxBi2Se3 is a strong candidate for time-reversal invariant topological superconductor. In this talk, I will discuss our theoretical work on nematic odd-parity superconductivity, including pairing mechanism, Majorana zero modes and disorder effects. I will present a model in which odd-parity phonon fluctuations provide the pairing mechanism, and discuss the competition among nematic, chiral and s-wave pairing channels. A topological superconductor is characterized by Majorana zero modes on boundaries. I will show that a nematic superconductor supports a special defect, namely the nematic vortex, which also binds a Kramers pair of Majorana modes. Finally, I will briefly discuss robustness of the nematic odd-parity superconductivity against disorder.'
The Tuesday JFI Seminar - Prof. Tzahi Cohen-Karni, Departments of Biomedical Engineering and Material Science & Engineering, Carnegie Mellon University
MultiscaleTopological Design of Biological Interfaces to Novel NanomaterialsMy research team efforts focus on developing a new class of nanoscale materials and novel strategies for the investigation of biological entities at multiple length scales, from the molecular level to complex cellular networks. Our highly flexible bottom-up nanomaterials synthesis capabilities allow us to form unique hybrid-nanomaterials. Recently, we have demonstrated highly controlled synthesis of 3D out-of-plane single- to few-layer fuzzy graphene (3DFG) on a Si nanowire (SiNW) mesh template. By varying graphene growth conditions, we control the size, density, and electrical properties of the NW templated 3DFG (NT-3DFG). This flexible synthesis inspires formation of complex hybrid-nanomaterials with tailored optical and electrical properties to be used in future applications such as bio-sensing, and energy conversion and storage.
Our current efforts target the limits of cell-nanodevices interfaces using nanosensor based array assembled in 3D with subcellular spatial resolution (<5μm) and μsec temporal resolution. Our approach enables simultaneous multiplexed electrical measurements to directly monitor the development of electrical activities of microscale tissues (μtissues, ca. 100-400μm) which are engineered from induced pluripotent stem cell (iPS) derived cardiomyocytes or pancreatic islets isolated from mice.
In summary, the exceptional synthetic control and flexible assembly of nanomaterials provide powerful tools for fundamental studies and applications in life science, and open up the potential to seamlessly merge either nanomaterials-based platforms or unique nanosensor geometries and topologies with cells, fusing nonliving and living systems together.
Noisy internal model of the noisy external worldBring lunch at noon
We hear the story at 12:15
Tanya Zelevinsky, Columbia University
Physics and Chemistry with Diatomic Molecules Near Absolute ZeroSimple molecules can be manipulated near absolute zero with quantum optical techniques that were originally developed for atomic gases. Molecules, however, present us with profoundly distinctive properties that arise from their internal complexity and a higher density of states. They can be sensitive to different aspects of fundamental physical laws than atoms are. Here we show how a combination of molecular spectroscopy in the style of optical atomic clocks and modern quantum chemistry explain some bizarre properties of loosely bound molecules, shed light on the quantum aspects of the most basic chemical reactions, and promise to advance table-top fundamental physics in new directions.
Shuolong Yang, Cornell University
Interfacial Engineering of Quantum MaterialsQuantum materials are fascinating platforms where macroscopic quantum phenomena occur. As a prominent example, superconductors conduct electricity with no dissipation at low temperatures, holding great promise to address global energy challenges. It is of tremendous scientific and technological interest to enhance superconducting transition temperatures. In this talk, I will elucidate the principles of interfacial engineering and co-operative interactions through studies of bulk superconductors, and demonstrate how I implement these concepts in fabricating an iron selenide/strontium titanate interfacial superconductor.
Valeria Molinero, Professor, Department of Chemistry, The University of Utah
Molecular Recognition of Ice by Proteins: from Ice Nucleation to AntifreezeBacteria, insects and fish that thrive at subfreezing temperatures produce proteins that bind to ice and manage its formation and growth. Ice binding proteins include antifreeze proteins and ice-nucleating proteins. The latter are the most efficient ice nucleators found in Nature. Many questions remain on how do these proteins recognize or nucleate ice, what drives their selectivity and binding to ice, and how does the size and aggregation of the proteins modulate their function. In this presentation, I will discuss our recent work addressing these questions using molecular simulations and theory, with particular focus on elucidating what intermolecular interactions and chemical motifs make these proteins so efficient at their function, to resolve the apparent paradox that the same structures can promote and prevent ice formation, and to draw general principles that can be used for the design of synthetic alternatives for control of ice formation and recrystallization.
Dr. Ariel Furst, University of California, Berkeley
Electrochemical BiosensorsElectrochemistry is an exceptionally powerful tool to form chemical bonds and monitor chemical and biological interactions. Electrochemical biosensors afford unparalleled specificity and selectivity to monitor analytes in complex solutions. By improving the chemistry used to assemble biomolecules on electrode surfaces, the selectivity and sensitivity of these devices has been significantly improved. Superior fabrication methods have led to direct electrochemical detection of DNMT1, a cancer biomarker, from human tissue samples. Electrochemical devices have also been made to pattern non-adherent cells and detect endocrine disrupting compounds. By combining improved chemistries for biomolecule modification with unique signal amplification strategies, we have successfully detected targets from complex biological solutions.
James Evans, University of Chicago
Social Limits to UnderstandingI provide an overview of my research tracing several ways in which social connection between scientists, engineers and citizens shape the limits of what a population can collectively know. This includes empirical demonstrations of how centralized networks decrease the truth value of collective certainty in biomedicine, how large teams shrink the search space of science and technology, and how flocking correlates investigations and limits the size of future understanding. I then explore how the complex system of science, technology and society generates productive social disconnection to accelerate advance through maintaining crossable boundaries between disciplines, ideologies, and the ways in which recombination are valued. To explore this last point, I model scientific discovery and technological invention as involved in the complex combination of contents including problems, methods and physical entities, which bridge contexts such as journals, subfields and conferences from which scientists and inventors drawn them. We can model the normal growth of ideas in articles and inventions by representing them as complex combinations of scientific and technical contents and contexts with a high-dimensional stochastic block model, which predicts more than 95% of new patents and articles in biomedicine and physics. The inverse probability of published papers and patents under this model--unlikely combinations of contents across contexts--predicts nearly 50% of the likelihood of revolutionary success, measured by outsized citations and major awards. I discuss the implication of these findings for science policy and practice.
Mary N. Teruel, PhD, Stanford
Control of mammalian cell differentiation by feedback & noiseMammalian tissue size is maintained by slow replacement of damaged, de-differentiating, and dying cells. For adipocytes, key regulators of glucose and lipid metabolism, the renewal rate is only 10% per year1. We used computational modeling, quantitative mass spectrometry, and single-cell microscopy to show that cell-to-cell variability, or noise, in protein abundance acts within a network of more than six positive feedbacks to permit pre-adipocytes to differentiate at very low rates. This reconciles two fundamental opposing requirements: high cell-to-cell signal variability so that differentiation rates can be kept very low and low signal variability to prevent differentiated cells from de-differentiating. Higher eukaryotes can thus control low rates of near irreversible cell fate decisions through a balancing act between noise and ultra-high feedback connectivity2,3.
We have since explored how the differentiation network functions in the physiological context where hormone inputs are known to oscillate. Intriguingly, we found that a circadian signaling code is critical for restricting the rate of fat cell differentiation. Dysregulation of the circadian pattern of glucocorticoid oscillations by irregular feeding and sleep cycles, by long-term hormone treatment, or during metabolic diseases, have all been shown to cause obesity. By using live, single-cell imaging of the key adipogenic transcription factors CEBPB and PPARG, endogenously tagged with fluorescent proteins, we show that pulsatile circadian hormone stimuli are rejected by the adipocyte differentiation control system, leading to very low adipocyte differentiation rates4. In striking contrast, equally strong persistent signals trigger maximal differentiation. We identify a network that combines fast and slow positive feedback loops as a unique regulatory motif that selectively suppresses differentiation for circadian pulse patterns. Together, our study provides a molecular mechanism for why stress, Cushing's disease, and other conditions for which glucocorticoid secretion loses its pulsatility can lead to obesity. Furthermore, given the ubiquitous nature of oscillating hormone secretion in mammals, the filtering mechanism we uncovered may represent a general temporal control principle for differentiation.
Nick Bultinck, Princeton University
Tensor network trial wave functions for topological phasesThe construction of trial wave functions has proven itself to be very useful for understanding strongly interacting quantum many-body systems. Two famous examples of such trial wave functions are the resonating valence bond state proposed
by Anderson and the Laughlin wave function, which have provided an (intuitive) understanding of respectively spin liquids and fractional Quantum Hall states. Tensor network states are another, more recent, class of such trial wave functions which are based on entanglement properties of local, gapped systems. In this talk I will discuss the use of tensor network states for topological phases, and what we can learn from this approach. I will consider one- and two-dimensional systems, consisting of both spins and fermions. The focus will be on the different connections that can be made using tensor networks, such as connecting theory to numerics, and physical properties to ground state entanglement.
Juan Mendoza, Postdoctoral Fellow, Department of Molecular & Cellular Physiology, Stanford University
Enhancing the therapeutic potential of cytokines through protein engineeringThe interferon (IFN) superfamily of cytokines are an essential part of the innate immune system providing protection against the spread of viral infections and cancerous growths. There are three families of IFNs, type I-III, each with distinct ligand-receptor systems. This presentation will report on efforts to elucidate the structure-functional relationships of IFN induced signaling and to enhance IFN functions. For these efforts, a protein engineering approach has been applied to rapidly evolve IFNs and visualize the three-dimensional shapes of interferon cytokines bound to their cellular receptors. These results provide new insight to cytokine signaling and new opportunities for developing promising molecules for basic research and clinical use.The interferon (IFN) superfamily of cytokines are an essential part of the innate immune system providing protection against the spread of viral infections and cancerous growths. There are three families of IFNs, type I-III, each with distinct ligand-receptor systems. This presentation will report on efforts to elucidate the structure-functional relationships of IFN induced signaling and to enhance IFN functions. For these efforts, a protein engineering approach has been applied to rapidly evolve IFNs and visualize the three-dimensional shapes of interferon cytokines bound to their cellular receptors. These results provide new insight to cytokine signaling and new opportunities for developing promising molecules for basic research and clinical use.
acoustic propulsion: when the whistle pulls the trainBring lunch at noon
We hear the story at 12:15
Jing Yan, Burroughs Wellcome Fellow, Princeton University
Building a home the V. cholerae way: biophysics of bacterial biofilmsBiofilms are surface-associated bacterial communities embedded in an extracellular matrix. Bacterial biofilms can cause chronic infections and they clog pipes and filters in industry. Investigations to date have primarily focused on the genetic and regulatory features driving biofilm formation. In this seminar, I will discuss how I have used Vibrio cholerae as a model biofilm former to reveal the biophysical and biomechanical principles underlying biofilm formation. I will present a new technology to image living, growing bacterial biofilms at single-cell resolution. I will use this imaging technique to investigate how cell growth, cell-cell adhesion, and cell-surface adhesion, collectively, determine the global biofilm architecture. I will show how matrix production drives biofilm expansion and excludes cheater cells. Finally, I will discuss efforts to measure the material properties of biofilms. I will show how understanding biofilms as living materials enabled the development of methods for their removal.
Marvin Cohen, The University of California Berkeley
A Hundred Years of Modeling SolidsSince the focus when modeling solids and more generally in condensed matter physics (CMP) is on energies, physical sizes, and time scales that are not extremely big or extremely small, but somewhere we loosely call the “middle”, it can be argued that this characteristic of CMP allows it to have many links to other branches of physics and more generally other areas of science and engineering since many of them also focus on similar size scales. In addition, the domain of CMP includes both applied and fundamental components. Although I will focus mainly on the latter with emphasis on “modeling solids” which gave rise to many intellectual and conceptual contributions to basic science, I will mention some applied aspects. I plan to describe some research involving the electronic structure of materials, semiconductors, superconductors, and nanoscience. I’ll begin with a discussion of the development of these areas over the past hundred years, and then I’ll discuss some current achievements and discoveries.
Dr. Alison Wendlandt, Harvard University
Mechanism-guided Development of Selective Catalytic Organic ReactionsMechanistic study is presented as a central tool in the development of new, selective catalytic reactions. Two case studies are discussed. The first study highlights the development of quinone-based catalysts for the aerobic dehydrogenation of N-heterocycles. Inspired by quinone cofactors found in amine oxidase enzymes, this work identifies a new, abiological mechanism for substrate oxidation that proves critical for good catalytic efficiency and broad reaction scope. The second study highlights an enantioselective unimolecular substitution (SN1) reaction for the construction of quaternary stereogenic centers. A dual catalyst system is identified which is capable of generating – and controlling – highly electrophilic tertiary cations as reactive intermediates. Detailed mechanistic analysis supports a stepwise, stereoablative substitution pathway.
Dr. Monirosadat (Sanaz) Sadati, IME, The University of Chicago
Liquid Crystals for Responsive Materials DesignBring food and talk at noon. Seminar begins at 12:15. The alignment of liquid crystal molecules is exquisitely sensitive to molecular and chemical interfacial binding events; these events can be amplified over relatively long distances, thereby providing the basis for a wide range of applications, from display technologies and optical devices to biosensors. A molecular-level understanding of the structure of liquid crystal interfaces is therefore central to such technologies. In this seminar, I will present a detailed view of the molecular organization of synthetic nematic and smectic liquid crystalline materials at interfaces, which we have generated through the combined use of synchrotron X-ray reflectivity measurements and molecular simulations. I will then discuss some of the unique responses of synthetic nematic liquid crystalline materials to the interfacial self-assembly of biological amphiphiles or the aggregation of proteins, and explain how such responses can be used to detect complex assembly processes, such as the very early stages of amyloid fibril formation. A second part of this seminar will discuss how more complex liquid crystalline behaviors and morphologies can be arrived at by introducing chiral molecules. More specifically, I will focus on the Blue phases of liquid crystals, which consist of liquid, highly ordered lattice structures that are stabilized by networks of line defects. These structures can reflect light in a highly selective manner, and are therefore of interest for optical applications. Unfortunately, they are only stable in a very narrow temperature range. I will explain how the coupling of chirality, geometrical confinement, mechanical deformation and polymerization of defect structures can enable the engineering of new morphologies that are stable over a much wider range of conditions. I will conclude by discussing some of the potential uses of these materials, along with some of the questions and challenges that remain to be addressed.
Jason Cantor Postdoctoral Fellow, Whitehead Institute for Biomedical Research
Environmental Impact on Human Cellular MetabolismWe recently developed a new culture medium to reflect the polar metabolite composition of human plasma (human plasma-like medium; HPLM) and demonstrated that, relative to conventional media, it extensively alters the metabolic landscape of cultured cells. Through the use of HPLM, we also discovered an unforeseen example of metabolic regulation that would have been difficult to identify otherwise using existing model systems, and moreover, that influences the potency of a classic chemotherapeutic. Together with additional tools and methods we have developed, as well as with various strategies in functional genomics and metabolomics among others, we will continue our efforts to better understand how environmental factors impact the metabolic regulation and requirements of cancer and immune cells.
Heinrich Jaeger, University of Chicago
The plot thickens: From discontinuous shear thickening to shear jammingOver the last few years dense suspensions of hard particles in a simple liquid have become a model system in the soft condensed matter, granular materials, and rheology communities for the investigation of strongly non-Newtonian behavior. A key aspect underlying the recent surge of activity has been the realization that in addition to hydrodynamic interactions direct frictional contact between particles can occur. In fact, friction forces were found to be essential in order to explain some of the most striking phenomena observed in dense suspensions, such as an abrupt, essentially discontinuous onset of shear thickening, whereby the viscosity can jump up by over an order of magnitude as a critical shear rate is exceeded. So far, however, practically all theoretical models and simulations that include friction have treated it as a phenomenological parameter without considering its molecular origin. Furthermore, most models treated a situation in which shear is applied continuously, under steady-state conditions. This prevented these approaches from capturing the remarkable dynamic phenomena observed in dense suspensions, most notably the propagating jamming fronts associated with the transition from a merely shear-thickened to a solid-like jammed state. Thus, despite much recent progress, there remain fundamental questions both at the nano-scale, about the nature of the frictional interactions, and at the macro-scale, about the relation between steady-state and transient dynamic phenomena.
I will discuss recent experiments from our group that address these questions, focusing on the differences between discontinuous shear thickening (DST) and shear jamming (SJ). These experiments show how particle surface chemistry can play a central role in creating conditions that allow for SJ. We find the system’s ability to form interparticle hydrogen bonds when sheared into contact elicits SJ. We demonstrate this with charge stabilized polymer microspheres and non-spherical cornstarch particles, controlling hydrogen bond formation with solvents. The propensity for SJ is quantified by tensile tests and can be linked directly to an enhancement of the effective frictional interactions between particles, as measured by AFM and also observed by mapping out the steady-state rheology as a function of packing fraction.
Dr. Yiwen Chu, Department of Applied Physics, Yale University
Quantum Acoustics with Superconducting QubitsThe ability to engineer and manipulate different types of quantum mechanical objects allows us to take advantage of their unique properties and create useful hybrid technologies. Thus far, complex quantum states and exquisite quantum control have been demonstrated in systems ranging from trapped ions to superconducting resonators. Recently, there have been many efforts to extend these demonstrations to the motion of complex, macroscopic objects. These mechanical objects have important applications as quantum memories or transducers for measuring and connecting different types of quantum systems. In particular, there have been a few experiments that couple motion to nonlinear quantum objects such as superconducting qubits. This opens up the possibility of creating, storing, and manipulating non-Gaussian quantum states in mechanical degrees of freedom. However, before sophisticated quantum control of mechanical motion can be achieved, we must realize systems with long coherence times while maintaining a sufficient interaction strength. These systems should be implemented in a simple and robust manner that allows for increasing complexity and scalability in the future.
In this talk, I will describe our recent experiments demonstrating a high frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction. Our device requires only simple fabrication methods, extends coherence times to many microseconds, and provides controllable access to a multitude of phonon modes. We use this system to demonstrate basic quantum operations on the coupled qubit-phonon system. I will also briefly describe our current efforts to further improve our electromechanical device, which will hopefully allow for advanced quantum protocols analogous to what has been shown in optical and microwave resonators, resulting in a novel resource for implementing hybrid quantum technologies.
Jen Haizhen Wang, Research Fellow, Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School
Cyclin D-CDK4/6 kinase in cancer cell survival and immune surveillanceCyclin D-CDK4/6 are components of the core cell cycle machinery that drives cell proliferation. Inhibitors of CDK4/6 are currently in clinical trials for several cancer types with promising results. We show that cyclin D3-CDK6 plays pro-survival function via phosphorylation and inhibition the catalytic activities of 6-phosphofructokinase (PFKP) and pyruvate kinase M2 (PKM2). Inhibition of cyclin D3-CDK6 in tumor cells activates PFKP and PKM2 to reduce pentose phosphate pathway and serine pathway flows, thereby depleting anti-oxidants NADPH and glutathione to cause tumor cell apoptosis. We propose that measuring the levels of cyclin D3-CDK6 in human cancers might help to identify tumor subsets that undergo cell death and tumor regression upon CDK4/6-inhibition. On the other hand, we report that cyclin D-CDK4 negatively regulates PD-L1 stability through phosphorylating and stabilizing its upstream E3 ligase adaptor protein SPOP. Inhibition of cyclin D-CDK4 upregulates PD-L1 protein levels in tumor cells to generate immune evasion effect. We also show that combining CDK4/6 inhibitor with PD-1 blockade enhances anti-tumor therapeutic efficacy in mouse models. This study provides the molecular basis for combination therapy of CDK4/6 inhibitor and PD-1/PD-L1 blockade for human cancers.
Marco Allodi PhD, Department of Chemistry, University of Chicago
Visualizing Chemical Dynamics Across Nanoscale Interfaces
Dr. Ryan Hadt, Argonne National Laboratory,
Structure/Function Correlations Over Heterogeneous Catalysis and Bioinorganic ChemistryThis talk covers recent combinations of spectroscopy and theory to develop relationships between molecular structure and function within specific areas of heterogeneous catalysis and bioinorganic chemistry as well as areas of their intersection. Focus within heterogeneous catalysis is on the formation, characterization and reactivity of high-valent intermediates involved in the chemistries of alternative fuel (e.g., the oxygen evolution reaction and the conversion of methane to methanol). The characterization of these intermediates allows for a direct correlation between active sites in heterogeneous catalysis and bioinorganic chemistry. Additional focus within bioinorganic chemistry is on demonstrating, understanding and quantifying entatic states (in the electronic ground state) and their contributions to controlling the function of electron transfer active sites. These concepts are further extended to the reactivity of transition metal excited states (e.g., copper photosensitizers). Lastly, the nature of the entatic state is defined in detail for cytochrome c, with emphasis on understanding the protein contribution to the active site Fe–S(Met) bond strength and how the energetics of the local protein fold allow for bifunctionality in energy transduction (electron transfer) and apoptosis (lipid peroxidation).
Neuroanatomy: opportunities and questions when everything can be measuredBring your lunch at Noon
Main event at 12:15
Jon Simon, The University of Chicago
Exploring Matter Made of Light
I will survey ongoing work in my group to make matter from light. We have realized a variety of materials including some that exist in the natural world and others that exist only in the theorists’ minds. I will focus upon the particular challenge of exploring photonic topological matter, beginning with a brief tutorial on the fractional quantum Hall effect to motivate the properties we will need to “teach” our photons to have: I will then describe (1) how we induce photons to collide with one another, thereby realizing a photon “box” that can only hold one photon at a time; and (2) how we create an artificial magnetic field that induces photons to move in cyclotron orbits. In our quest to make photons behave as materials we will discover that their differences from electrons lead to surprises. Among these, that we have accidentally trapped our photons on the surface of a cone. We will thus conclude with a brief exploration of the first topological matter in curved space.
IME Distinguished Colloquium Series: Rachel Segalman, UC Santa Barbara
Professor Tohru Fukuyama, Nagoya University
Synthetic Studies on TetrodotoxinTetrodotoxin (TTX) is one of the most famous marine natural products, which is found most notably in the liver and ovary of puffer fish. It is the toxin responsible for the fatal food poisoning caused by improperly cooked puffer fish in Japan. This compound also serves as an important biochemical tool in neurophysiology since it exhibits neurotoxicity by selectively blocking sodium channels of excitable cell membranes. Despite its relatively small molecular size, TTX possesses eight contiguous stereogenic centers in its polyfunctionalized dioxaadamantane skeleton including an orthoester and a guanidine moieties. This fascinating molecule has been a popular target for many synthetic chemists although only a few successful total syntheses have been reported to date. We initiated our synthetic studies on TTX in the hope of identifying the exact location of sodium channels where TTX blocks. Recent progress of our approach will be discussed in the lecture.
Lea Nienhaus, Massachusetts Institute of Technology
From Imaging Excitons at the Nanoscale to Emerging Device ApplicationsUnderstanding light-induced processes in materials is critical for tailoring their optical and electronic properties to applications in chemical conversion, light harvesting, or energy transfer. Nanomaterials are prime candidates to study light-matter interactions on both the single-particle and the ensemble level. However, they are prone to defects which can be detrimental to their function in optoelectronic devices. Furthermore, many optoelectronic and photocatalytic systems are based on hybrid interfaces combining both inorganic and organic materials. The exact energy transfer mechanism at these hybrid interfaces is often obscure, particularly when both the macroscopic donor and acceptor materials consist of many separately interacting moieties. Here, I describe the detailed photophysics of a PbS nanocrystal-based light-harvesting device, and further demonstrate a technique for single-particle visualization of absorption in various nanomaterials.
I present exchange-mediated spin-triplet exciton transfer from semiconducting PbS nanocrystals to the triplet state of the organic molecule rubrene. Diffusion-mediated triplet-triplet annihilation in rubrene generates higher-energy emissive spin-singlet states, and shows promise in sub-bandgap sensitization of silicon. We combine transient photoluminescence spectroscopy with a kinetic model to unravel the underlying photophysics of the relevant energy transfer processes occurring in the upconverting device.
To further investigate light-harvesting at the nanoscale, I employ single molecule absorption detected by scanning tunneling microscopy. This technique is based on a change in the local density of states upon absorption, and thus visualizes the localized excitation. Taking advantage of Stark shifts caused by the electric field in the STM, different energy levels can be shifted into resonance with the excitation wavelength.
Focus on Scholarly Communication
Presented by the Royal Society of Chemistry and the University of Chicago Department of Chemistry"Meet the editor" event, hosted by Dmitri Talapin
Masahiko Yamada, Solid State Physics (ISSP), University of Tokyo
Crystalline spin-orbital liquids with an emergent SU(4) symmetry
Dr. Sarah King, Fritz Haber Institute of the Max Planck Society
Tracing the Dynamics of Interfacial Electronic Excited States from Femtoseconds to SecondsInterfacial electronic states determine the energy level alignment, charge transfer, and reactivity between two materials or phases of matter. For many interfaces and materials the excited states are more crucial to the functionality of the interface than the ground electronic states, such as in batteries, solar cells, or heterogeneous catalysts. A complete understanding of interfacial excited states requires knowledge of their lifetimes, dynamics, and reactivity on the relevant timescales, ranging from femtoseconds to seconds. I will discuss my work on two exemplary cases of the dynamics of interfacial electronic states: the formation of a small polaron at the dimethyl sulfoxide (DMSO)/metal interface and the reactivity of an electronic state at the amorphous solid water/vacuum interface, both investigated using time- and angle-resolved two-photon photoemission. DMSO is a common solvent used in battery electrolytes, and the experiments show a small polaron is formed on an ultrafast timescale via dynamic localization from a delocalized electronic state near the metal interface. Such insights are relevant for understanding the mechanism of electron localization at electrolyte/electrode interfaces. At the amorphous solid water/vacuum interface, a surface-bound electron that is formed via the conduction band of water is observed with a lifetime of tens of seconds. This electron undergoes a two-electron reaction with water, splitting water and producing hydroxide anions on the vacuum interface, with relevance to astrochemistry. These two different interfaces demonstrate how an understanding of excited state dynamics provides a unique insight into material interfaces and properties.
Physics with A Bang! Holiday Lecture and JFI Open HouseStudents, families, teachers and especially the curious are invited to attend our annual Holiday Lecture and Open House. See fast, loud, surprising and beautiful physics demos performed by Profs. Heinrich Jaeger and Sidney Nagel. Talk to scientists about their latest discoveries. Participate in hands-on activities related to their research.
Saturday, December 9th, 2017
Kersten Physics Teaching Center
5720 S. Ellis Ave., Chicago, IL
Lecture repeated at 11am and 2pm
Open House and Demo Alley from 12pm-4pm
Lab Tours in the afternoon
View the Live Stream of the 11am Show
View the Live Stream of the 2pm Show
See archived shows on our YouTube Channel
Doors for the Lectures open 30 minutes before each show. Admission to this event is free. Please note: there will be no online registrations, and will be a first to arrive, first ticketed event. We do not guarantee availibility of seating, but shows will also be streamed live to alternate venues.
This event is sponsored by the James Franck Institute, the Department of Physics, the Office of the Executive Vice President for Research, Innovation and National Laboratories, and the Materials Research Science & Engineering Center. The organizer of the Open House is Cheng Chin.
Professor Lutz H. Gade, Universität Heidelberg
Enantioselective Catalysis with 3D Transition Metal Complexes: Chiral Pincers as Stereodirecting LigandsKey challenges in the development of catalysts based on first row ("3d") transition metals include the substitutional lability of the open shell species involved, the changes of spin states in the individual reaction steps as well as the potential competition of single electron transfer steps. Most reaction sequences involve almost exclusively paramagnetic catalysts and catalytic intermediates. These properties render mechanistic studies challenging and also require care in the design of stereodirecting ligands.
Recently, we developed a new class of chiral pincer (“boxmi”) ligands which have been used in a variety of enantioselective transformations including alkylations of β-ketoesters and their subsequent cyclization to spirolactones, as well as the trifluoromethylation and azidation of β-ketoesters as well as oxindoles. Their iron(II) and manganese(II) complexes match the activity and selectivity of the most efficient noble metal catalysts for the hydrosilylation or hydroboration of ketones (Figure 1).
Figure 1. Highly active and enantioselective iron hydrosilylation catalyst for ketones.
The focus of the lecture will be the elucidation of the catalytic reaction mechanisms and the identification and characterization of the (frequently) paramagnetic species involved.
We acknowledge Funding by the Deutsche Forschungsgemeinschaft (DFG SFB 623 &
Ga 488/9-1&2), the Fonds der Chem. Industrie and the Alexander von Humboldt-Stiftung.
 Q.-H. Deng, H. Wadepohl, Lutz H. Gade, Chem. Eur. J. 2011, 17, 14922; Q.-H. Deng, R. L. Melen, L. H. Gade, Acc. Chem. Res. 2014, 47, 3162.
 Q.-H. Deng, H. Wadepohl, L. H. Gade, J. Am. Chem. Soc. 2012, 134, 2946; Q.-H. Deng, H. Wadepohl, L. H. Gade, J. Am. Chem. Soc. 2012, 134, 10769; Q.-H. Deng, T. Bleith, H. Wadepohl, L. H. Gade, J. Am. Chem. Soc. 2013, 135, 5356; T. Bleith, Q.-H. Deng, H. Wadepohl, L. H. Gade, Angew. Chem. Int. Ed. 2016, 55, 7852.
 T. Bleith, H. Wadepohl, L. H. Gade, J. Am. Chem. Soc. 2015, 137, 2456; T. Bleith, L. H. Gade, J. Am. Chem. Soc. 2016, 138, 4972; V. Vasilenko, C. K. Blasius, H. Wadepohl, L. H. Gade, Angew. Chem. Int. Ed. 2017, 56, 8393.
Julia Widom, University of Michigan
Structure and Dynamics of Nucleic Acids by Nonlinear Spectroscopy and Single-Molecule MicroscopyNucleic acids play central roles in many aspects of biology, acting as genetic material, catalysts, regulatory signals and more, and advances in optical spectroscopy and microscopy have provided significant insight into these biological functions. I will first present my work utilizing two-dimensional fluorescence spectroscopy (2DFS) to investigate the local conformations of nucleic acids. I initially used 2DFS to determine the solution conformation of a dinucleotide of the fluorescent nucleic acid base analogue 2-aminopurine, and it is now being extended to more complex DNA systems. I will then present ongoing work in which I am using single-molecule fluorescence microscopy to study the conformational dynamics of RNA in transcription and splicing complexes. I will focus on my work on riboswitches, which are RNAs that regulate bacterial gene expression in response to environmental cues. In the cell, RNA folds during its transcription by RNA polymerase (RNAP), and certain riboswitches function primarily by regulating the outcome of transcription. I investigated the interplay between riboswitch folding and transcription, finding that interactions between a riboswitch and RNAP concurrently aid in folding of the nascent riboswitch and stabilization of a paused state of RNAP. The discovery of this cross-coupling highlights the necessity of performing detailed biophysical studies of RNAs in their native biological contexts, which is a central goal of the research I plan to pursue as an independent investigator.
IME Distinguished Colloquium Series: Jay Gambetta, IBM
Ilya Nemenman, Emory University
Playing Newton: Learning equations of motion from dataArguably, science' goal of understanding nature can be formulated as inferring mathematical laws that govern natural systems from experimental data. With the fast growth of power of modern computers and of artificial intelligence algorithms, there has been a recent surge in attempts to automate this goal and to design, to some extent, an “artificial scientist.” I will discuss this emerging field, but will focus primarily on our own approach to it. I will introduce an algorithm that we have recently developed, which allows one to infer the underlying dynamical equations behind a noisy time series, even if the dynamics are nonlinear, and only a few of the relevant variables are measured. I will illustrate the method on applications to toy problems, including inferring the iconic Newton’s law of universal gravitation, as well as a few biochemical reaction networks. I will end with applications to experimental biological data: modeling the landscape of possible ! behaviora l states underlying reflexive escape from pain in a roundworm and (if time permits) modeling insulin secretion in pancreatic beta cells.
Dr. Amanda Cook, ETH Zürich
Mechanistic Studies of Catalytic Reactions in Solution and on Surfaces: C-H Functionalization and Hydroamination ReactionsUnderstanding the mechanisms of reactions is fundamental to both homogeneous and heterogeneous catalysis. The acetoxylation of arenes, borylation of methane, and hydroamination of alkynes reactions were studied, resulting in insights into catalyst reactivity and selectivity. In the acetoxylation of arenes, [(Pyridine)Pd(OAc)2]2 was found to be a highly active catalyst, and the mechanism of the reaction was determined. For methane borylation, the challenge of product selectivity was studied, and it was found that the catalyst [(Cp*)RuCl2]2 was not only the most selective, but indeed prefers methane as the substrate. The final reaction studied, the hydroamination of alkynes, was shown to be catalyzed by silica-supported Zn(II) ions, which was synthesized using a Surface Organometallic Chemistry approach. Through developing these catalysts, physical organic chemistry methods were used to understand their reactivity and selectivity, furthering our knowledge of both homogeneous and heterogeneous catalysis.
Chong Liu, Materials Science and Engineering, Stanford University
Materials Design and Electrochemical Methods for Water-Energy Nexus: From Water Purification to Resource MiningWater, resource, and energy are the foundation for the sustainable future. Applications in water-energy nexus require the control of phenomena that span enormous length scales. Materials design with precise atomic compositions and tailored microstructures as well as kinetics manipulation are the keys to achieve high performance. In this talk, I will first introduce the alternating current electrochemical method for resource mining from water. This method combined with surface functionalized electrodes can extract targeted resource species with extremely high capacity and selectivity. This method is successfully demonstrated for uranium extraction from seawater and heavy metals recovery from wastewater. It opens an eco-friendly route of mining from earth water system with minimal impact on the environment. Moreover, freshwater security is another focus of sustainability that is of paramount importance to public health, especially for developing areas with limited energy supply and insufficient infrastructures. By synthesizing nanomaterials with optimized physical properties and morphologies, we achieved rapid and efficient bacteria and viruses inactivation through photocatalysis and also enabled a new method based on electroporation.
Eugene Demler, Harvard
Stressed soft matter: softening, hardening and yielding soft solids.Time-dependent and process-dependent properties of soft jammed solids like gelled networks, compressed emulsions or colloidal glasses, stem from stress heterogeneities frozen-in during solidification and their coupling with an imposed deformation. I’ll discuss recent novel insights gained through numerical simulations of statistical microscopic models that suggest how to control the persistence of flow inhomogeneities upon yielding, and provide new cues to design softening, hardening and brittleness in soft solids.
Scott J. Miller, Yale University
Searching for Selective Catalytic Reactions in Complex Molecular EnvironmentsThis lecture will describe recent developments in our efforts to develop low-molecular weight catalysts for asymmetric reactions. Over time, our view of asymmetry has ebbed and flowed, with foci on enantioselectivity, site-selectivity and chemoselectivity. In most of our current work, we are studying issues of enantioselectivity as a prelude to extrapolation of catalysis concepts to more complex stereochemical settings where multiple issues are presented in a singular substrate. Moreover, we continuously examine an interplay between screening of catalyst libraries and more hypothesis-driven experiments that emerge from screening results. Some of the mechanistic paradigms, and their associated ambiguities, will figure strongly in the lecture.
Odd viscosity in chiral active fluidsEat chiral active food: 12:00
Hear about chiral active fluids: 12:15
Bettina Hoerlin and Gino Segrè
Enrico Fermi: The Pope of PhysicsEnrico Fermi has been called the last scientist who knew all of physics, having attained the heights of the profession as a theorist and experimentalist. Unique in numerous ways, this 20th century physicist was entirely self-taught; the breadth and depth of his research remain unparalleled. Fermi’s 1938 Nobel Prize was picked up en route in his flight from fascist Italy with his Jewish wife and children to a new life in America. In 1942 he became the lead scientist in the University of Chicago experiment that produced the first self-sustaining nuclear chain reaction, a key precursor to building the atomic bomb. His role in the success of the Manhattan Project was critical.
This lecture combines Fermi’s personal life with his scientific contributions and illustrates how he was shaped by history and how he, in turn, shaped history. Legendarily apolitical, Fermi was reluctantly involved in American political decision making during the war and afterwards. The many challenges he faced, including the tensions between politics and science, are still relevant today.
Lydia Kisley, University of Illinois at Urbana - Champaign
Proteins in Nanoporous Hydrogels: Adsorption, Diffusion, and FoldingProteins within nanoporous hydrogels have important biotechnological applications in pharmaceutical purification, tissue engineering, water treatment, biosensors, and medical implants. Yet, oftentimes proteins that are functional in solution lose activity when in contact with soft nanostructured materials due to perturbations in the folded state, conformation, diffusion, and adsorption dynamics of the protein by the material. We have developed several unique nanoscale fluorescent spectroscopies to image the heterogeneity of protein dynamics within hydrogels. First, we resolve adsorption kinetics of proteins to charged ligands within hydrogels used in pharmaceutical separations using location-based super resolution imaging to demonstrate the importance of the spatial charge distribution of the ligands. Next, we show the heterogeneity of the nanoscale pore size of the hydrogels can influence the diffusion of analytes within the pores using an in situ correlation-based super resolution imaging technique. Finally, we use fluorescence resonance energy transfer imaging combined with temperature jump perturbations to show that noncovalent interactions of the protein with the polymer surface are more important than confinement for determining the folding and stability of the protein within hydrogels. Overall, in situ observations of proteins in hydrogels using fluorescent spectroscopies can inform and inspire soft nanomaterial design to improve the performance, shelf life, and cost of the next generation of biomaterials.
Vern Schramm, Albert Einstein College of Medicine
Transition State Analogues as Drug CandidatesOur focus is on understanding enzymatic transition states. The approach is to use intrinsic kinetic isotope effects combined with computational chemistry to determine electrostatic potential maps of enzymatic transition states. Knowledge of these transition states provides chemical insights and permits the design of stable molecules as transition state mimics. Synthetic chemistry collaborators in New Zealand produce the transition state mimics. The design of transition state mimics has led to the most powerful inhibitors for over a dozen enzymes. One focus for enzyme inhibitor design is the family of N-ribosyltransferases. Three transition state analogues designed for the N-ribosyltransferases have entered clinical trials and others are in earlier stages of development. One of these was recently approved for use in relapsed or resistant peripheral T cell lymphoma in Japan. Comparison of target-drug interaction in vitro and in vivo provides insights for the action of tight-binding drug candidates. Research focus on transition states includes investigation of the fast protein motions that contribute to transition state formation. We use isotopically heavy enzymes and computational chemistry to establish the connection between fast dynamic protein motion and bond breaking at the transition state.
Emanuela Del Gado, Georgetown University
Stressed soft matter: softening, hardening and yielding soft solids.Time-dependent and process-dependent properties of soft jammed solids like gelled networks, compressed emulsions or colloidal glasses, stem from stress heterogeneities frozen-in during solidification and their coupling with an imposed deformation. I’ll discuss recent novel insights gained through numerical simulations of statistical microscopic models that suggest how to control the persistence of flow inhomogeneities upon yielding, and provide new cues to design softening, hardening and brittleness in soft solids.
The Tuesday JFI Seminar - Prof. John Parkhill, Department of Chemistry & Biochemistry, Notre Dame
Quantum dynamics with Statistical Effects and Statistical Models of Quantum EffectsThe capability of electronic structure to calculate the wavefunctions, and even dynamics of large systems has improved dramatically. This has put electronic structure into an uncomfortable regime where statistical effects become as important as the correlation problem. I will discuss our efforts to describe mixed-state electronic dynamics with density matrix equations of motion, and the applications of those theories to ultrafast experiments. Realtime mean field theories such as RT-TDDFT and RT-TDHF dominate applications because of the speed required to access picosecond timescales. Yet TDHF and TDDFT are not accurate enough to properly model resonant driving, which is only one ingredient in ultrafast spectroscopy. In this talk I discuss a simple density-matrix equation of motion implemented as an approximation to RT-TDDFT, which excites properly on resonance. Based on this foundation I compare the non-equilibrium steady states of the correct DFT and a Markovian bath model, with essentially exact results coming from HEOM showing that TDDFT can be used to study driven ultrafast dynamics. I then discuss self-consistency in correlated corrections to TDDFT which have low cost and can be applied to large systems. Statistical sampling of molecular geometries has become an equally important issue, although empirical density functionals, which are the most practical tools for exploring geometries, make an ambiguous mixture of quantum physics and statistical modeling. I will demonstrate purely statistical models of molecular structure, and show that in the near future it is likely that purely empirical models of the PES will have several appealing advantages over empirical hybrids. of quantum mechanical models with statistics.For further information please contact Brenda Thomas at 773-702-7156 or by email at email@example.com. You may also contact the Host, David Mazziotti at 773-834-1762 or via email at firstname.lastname@example.org.
Mark Spencer Rudner, Niels Bohr Instituet
Quantized magnetization density and the topology of anomalous Floquet insulatorsPeriodic driving can be used to induce a wide array of interesting phenomena in quantum many-body systems. In addition to providing means to induce artificial gauge fields or to realize familiar effective Hamiltonians, periodic driving opens a wide new world of intrinsically non-equilibrium quantum phases. Intriguingly, the topological classification of periodically-driven systems is more rich than that in equilibrium, allowing for a variety of "anomalous Floquet insulator" phases which feature characteristic patterns of nontrivial micromotion within each driving period. In this talk I will give an introduction to the unique features of topology in periodically-driven systems, and discuss the new quantized observables that can be used to detect them. In particular, I will focus on a two-dimensional system that features chiral edge states even though all bulk bands have vanishing Chern numbers and may be fully localized by disorder. This phase features a quantized orbital magnetization density in any filled region, which serves as a bulk topological order parameter for the phase (and applies in both interacting and non-interacting systems). I will discuss a proposal for how to measure the magnetization in a system of cold atoms in an optical lattice. Due to its chiral edge states, which are not localized by disorder, this phase provides an interesting platform for studying the interplay between thermalization and many-body localization.
Sigrid Nachtergaele PhD, University of Chicago
Uncovering the cellular functions of mRNA methylationSandwiches at 11:45; remember to bring a cup for coffee/tea.
AJ Boydston Associate Professor, Department of Chemistry University of Washington
Integrated Synthesis, Design, Additive Manufacturing, and Mechanoresponsive MaterialsFor this seminar, I hope to discuss two research thrusts from my program: Additive Manufacturing with Mechanoresponsive Materials, and Metal-Free Ring-Opening Metathesis Polymerization. Our research team focuses on the chemistry of additive manufacturing with emphasis on: 1) incorporation of functional materials, particularly those that respond via conversion of mechanical force into chemical reactivity; 2) expansion of the materials space available for AM; and 3) selective multi-material printing from “all-in-one” mixed-resin vats. As representative examples, we will discuss melt-material extrusion of custom mechanochromic filaments, novel formulations that enable inexpensive and efficient access to elastomeric components via vat photopolymerization, and progress toward parallel photo-radical/photo-cationic printing mechanisms for production of graded materials. Our longer-term research objectives center on the ability to integrate mechanoresponsive materials (molecular- to nanoscale), property gradation or heterogeneity (nano- to microscale), and object geometry (micro- to mesoscale) to answer key scientific questions about the interplay between mechanics (and dynamics) of lattice structures and chemo-mechanical coupling. A major synthetic effort of my program centers on the development of photoredox-mediated, metal-free methods for polymer synthesis. Recently, we discovered that visible light photoredox catalysis is a viable approach for conducting ring-opening metathesis polymerization (ROMP) of strained cycloalkenes. This divergence from metal-mediated polymerizations introduces a new mechanistic theme for ROMP with unique synthetic outcomes. We will present our fundamental studies on the mechanism of this polymerization and updates on our applications-oriented research toward commercialization.
Michael Pretko, UC Boulder
Higher Rank Quantum Spin Liquids: From Fractons to Mach’s PrincipleQuantum spin liquids are phases of matter exhibiting a variety of interesting properties, such as fractionalization and long-range quantum entanglement. These exotic phases possess a natural description in the language of gauge theory. While most spin liquids studied to date have been described by familiar vector gauge fields, there exists a broader class of stable spin liquid phases described by higher rank tensor gauge fields. In this talk, I will discuss the physics of three-dimensional spin liquids described by symmetric tensor gauge theories. Such theories are notable for their “subdimensional” gauge charges, which are forced to exist in lower-dimensional subspaces instead of propagating freely in three-dimensional space. In some cases, the charges will be fully immobile, in a manifestation of the “fracton” phenomenon. I will review the basic physics of subdimensional particles and their coupling to tensor gauge fields. As an illustrative example, I will discuss rank 2 spin liquids which exhibit the basic properties of emergent gravity. In particular, I will discuss how the fracton phenomenon can be understood as a direct consequence of Mach’s principle.
Sang Ouk Kim KAIST Chair Professor, Department of Materials Science & Engineering, KAIST
Liquid Crystalline Graphene Oxide Nanoscale Assembly for Functional StructuresGraphene Oxide Liquid Crystal (GOLC) is a newly emerging graphene based material, which exhibits nematic type colloidal liquid crystallinity with orientational ordering of graphene oxide flakes in good solvents, including water. Since our first discovery of GOLC in aqueous dispersion, this interesting mesophase has been utilized for many different application fields, such as liquid crystalline graphene fiber spinning, graphene membrane/film production, prototype liquid crystal display and so on. Interestingly, GOLC also allow us a valuable opportunity for the highly ordered molecular scale assembly of functional nanoscale structures. This presentation will introduce our current status of GOLC research particularly focusing on the nanoscale assembly of functional nanostructures. Besides, relevant research works associated to the nanoscale assembly and chemical modification of various nanoscale materials will be presented.
Andreas Trautner, University of Bonn
CP violation caused by another symmetryUnderstanding the origin of CP violation offers a new starting point to address the Standard Model flavor and strong CP puzzles.
Group theoretically, the physical CP transformation of the SM is a special outer automorphism ("symmetry of symmetry") of the theory
and I will explain what that means in detail.
Equipped with this, we can understand that beyond the Standard Model, there can be other outer automorphisms beyond the usual C,P or T transformations.
On the other hand, certain classes of symmetries do preclude the existence of CP transformations altogether in which
case CP is violated by calculable ("geometrical") phases. I will explain this based on two explicit example models:
In a special three Higgs doublet model the presence of outer automorphisms beyond CP allows for a super simple calculation of VEVs, a reduction of
the size of the parameter space by a factor of 24, anticipating the boundaries of the RGE flow and most interestingly,
the prediction of quantized CP violating phases. A second explicit example is a "Scalar-QCD" type of model in which the SU(3) gauge group is spontaneously broken to the small discrete subgroup T7.
In this case CP violation originates with quantized phases while the theta angle is protected at 0.
Abigail Knight, PhD, Arnold O. Beckman Postdoctoral Fellow, UCSB
Bioinspired Metal-Coordinating MaterialsCoordination of metal ions is critical to the structure and function of a variety of natural materials and allows a diverse array of capabilities currently unavailable to synthetic structures. This talk will highlight efforts towards mimicking two capabilities of natural materials: (1) the selective coordination of metal ions and (2) implementing metal ions to induce a morphological shift in self-assembled materials. Selective coordination is critical to the function of a variety of natural proteins, yet synthetic ligands with this capability are rare despite applications in heavy metal remediation, therapeutics, and recycling. A combinatorial platform implementing N-substituted glycine oligomers, or peptoids, was designed to identify motifs capable of chelating low concentrations of various metal ions in complex sample media. Amphiphilic marine siderophores have a more unique capability to undergo a morphological shift upon metal coordination. Inspired by these structures, coordinating peptide polymer amphiphiles were designed that undergo self-assembly directed by coordination geometry, adding to the toolbox of stimuli responsive materials.
Professor Jay Groves, University of California, Berkeley
Signal Transduction on Membrane SurfacesMost intracellular signal transduction reactions take place on the membrane surface. The membrane provides much more than just a surface environment on which signaling molecules are concentrated. There is a growing realization that multiple physical and chemical mechanisms allow the membrane to actively participate in the signaling reactions. Using a combination of single molecule imaging and spectroscopic techniques, my research seeks to directly resolve the actual mechanics of signaling reactions on membrane surfaces both in reconstituted systems and in living cells. These observations are revealing new insights into cellular signaling processes as well as some unexpected functional behaviors of proteins on the membrane surface.
Gil Rafael, Caltech
Topological frequency conversion in strongly driven quantum systemsWhen a small quantum system is subject to multiple periodic drives, it may realize multidimensional topological phases. In my talk, I will explain how to make such constructions, and show how a spin-1/2 particle driven by two elliptically-polarized light beams could realize the Bernevig-Hughes-Zhang model of 2 topological insulators. The observable consequence of such construction is quantized pumping of energy between the two drive sources.
Yuval Elhanati, Princeton University
Probabilistic Inference of the Adaptive Immune SystemThe adaptive immune system can recognize many different threats by maintaining a large diversity of cells with different membrane receptors. We study the complex stochastic processes that generate and shape this ensemble of immune receptors using probabilistic models. These models can be inferred from high throughput sequence data using statistical algorithms. Specifically, we can use a technique based on transfer matrices formulation to learn the probabilistic properties of the generation process. We can then model also selection effects on the generated cells using maximum likelihood methods. Our methods allow us to characterize and study the diversity of the distribution beyond the sample data itself, disentangling and uncovering the details of the biological processes shaping it. We find universality - different individuals, humans and mice separately, have very similar underlying processes shaping the repertoire. This universality in turn acts as a baseline for further study of the system under perturbations such as infections or vaccination. Eventually we plan to harvest the statistical power of the models to diagnose and help plan treatments to clinical conditions from infections to cancer.
Professor Preston Snee, University of Illinois at Chicago
Transient X-Ray Absorption of Semiconductor Quantum Dots Reveals New Charge Transport Phenomenon
Elizabeth R Chen, mathe·magician
« having a ball » part II: spherical parking¿¿ what is more FUN than
playing with beach ball & projector markers ??
¡¡ doing actual math with them, of course !!
this continues the Atrium talk from Thursday
JOIN US for hands·on exploration of spherical parking
bring your lunch
Eric Isaacs, University of Chicago
CP-1: The 'Big Bang' of Big ScienceChicago Pile-1 marked a milestone in science -- and, indeed, in human history. But beyond the scientific impact of that first human-made self-sustaining nuclear chain reaction, CP-1 forever changed the way scientists and institutions work together, creating a new interdisciplinary model that reshaped the University's approach to scientific research and led directly to the founding of the National Laboratories and today's big science initiatives.
Evan Miller, University of California, Berkeley
Electrophysiology: Unplugged. New Chemical Tools to Watch Cell PhysiologyThis presentation will describe progress towards the use of voltage-sensitive fluorescent dyes to measure changes in cellular and neuronal membrane potential. The Miller lab is developing new methods for voltage imaging that rely on photoinduced electron transfer (PeT) as a voltage-sensing trigger to achieve fast, sensitive, and non-disruptive optical measurements of membrane potential. I will discuss recent progress on new, long-wavelength voltage indicators for use in neuronal systems, progress towards genetically targeting these indicators to defined cells, and new methods to explore the physiology non-excitable cells.
Hod Lipson, Columbia University
Uncovering lurking order in time-series dataFrom automatic speech recognition to discovering unusual stars, underlying almost all automated discovery tasks is the ability to compare and contrast data streams with each other, to identify connections and spot outliers. Despite the prevalence of data, however, automated methods are not keeping pace. A key bottleneck is that most data comparison algorithms today either rely on a human expert to specify what ‘features’ of the data are relevant for comparison, or require copious amounts of data for machine learning. Data Smashing is a new principle for estimating the similarity between the sources of arbitrary data streams, using neither domain knowledge nor learning. We demonstrate the application of this principle to the analysis of data from a number of real-world challenging problems, including the disambiguation of electro-encephalograph patterns pertaining to epileptic seizures, detection of anomalous cardiac activity from heart sound recordings and classification of astronomical objects from raw photometry. In all these cases and without access to any domain knowledge, performance is on a par with the accuracy achieved by specialized algorithms and heuristics devised by domain experts. Work done with Ishanu Chattopadhyay.
The Tuesday JFI Seminar - Erez Berg, Department of Physics, University of Chicago
Bad Metals and Bad Insulators: A View from the Large-N limitIn normal metals, the electron's mean free path is much larger than its wavelength, allowing a semiclassical treatment of transport. Conversely, whenever scattering is so strong that the mean free path becomes comparable to the electron's wavelength, the concept of a quasiparticle becomes ill defined, and a new theoretical framework is needed. I will introduce a family of lattice models for interacting electrons that can be solved exactly in the limit of a large number of interacting electron flavors and/or phonon modes. Depending on details, these models exhibit either "resistivity saturation" at high temperatures to a value of the order of the quantum of resistance, or "bad metallic behavior" where the resistivity grows without bound with increasing temperature. Translationally invariant higher-dimensional generalizations of the Sachdev-Ye-Kitaev model can capture a variety of phenomena arising purely from electron-electron interactions, including local criticality, non-Fermi liquid, and marginal Fermi liquid behavior. I will describe the implications of these results for the problem of non-quasiparticle transport at large, local quantum criticality, and the relation between transport and the development of quantum chaos.
Timothy White Air Force Research Laboratory; Materials and Manufacturing Directorate
Pixelated Polymers: Directing the Self-Assembly of Liquid Crystalline ElastomersLiquid crystalline materials are pervasive in modern society. It has been long-known that liquid crystalline materials in polymeric forms also exhibit exceptional characteristics in high performance applications such as transparent armor or bulletproof vests. A specific class of liquid crystalline polymeric materials referred to as liquid crystalline elastomers were predicted by de Gennes to have exceptional promise as artificial muscles, owing to the unique assimilation of anisotropy and elasticity. Subsequent experimental studies have confirmed the salient features of these materials, with respect to other forms of stimuli-responsive soft matter, are actuation cycles of up to 400% as well “soft elasticity” (stretch at minimal stress). In this presentation, I will summarize our recent efforts in developing materials chemistry amenable to directed self-assembly. Enabled by these chemistries and processing methods, we have prepared liquid crystal elastomers with distinctive actuation and mechanical properties. Notably, these materials are homogenous in composition (lacking material/material interfaces). Relevance of this work to implementations in aerospace and commercial applications will be discussed.
James Shorter PhD, University of Pennsylvania
Reversing aberrant phase transitions of RNA-binding proteins connected to ALS and FTDRNA-binding proteins (RBPs) with prion-like domains (PrLDs) phase transition to functional liquids, which can mature into aberrant hydrogels composed of pathological fibrils that underpin fatal neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Several nuclear RBPs with PrLDs including TDP-43, FUS, hnRNPA1, and hnRNPA2 mislocalize to cytoplasmic inclusions in ALS and FTD and mutations in their PrLDs can accelerate fibrillization and cause disease. Here, I will discuss our latest endeavors to uncover and engineer therapeutic protein disaggregases to reverse these aberrant phase transitions and restore functional RBPs to the nucleus to counter ALS and FTD disease phenotypes.
Mercouri G. Kanatzidis, Northwestern University
3D and 2D Halide Perovskites: Poor Man's High Performance SemiconductorsThree-(3D) and two-dimensional (2D) layered halide perovskites are highly promising candidates for optoelectronic applications, and this has sparked new investigations of these materials from the synthetic, physicochemical and applications point of view. The 3D versions of these compounds adopt the three-dimensional ABX3 perovskite structure, which consists of a network of corner-sharing BX6 octahedra, where the B atom is a divalent metal cation (typically Ge2+, Sn2+ or Pb2+) and X is a monovalent anion (typically Cl−, Br−, I−); the A cation is selected to balance the total charge and it can be a Cs+ or a small molecular species. Such perovskites afford several important features including excellent optical properties that are tunable by controlling the chemical compositions, they exhibit ambipolar charge transport with high mobilities. Another class of materials gaining significance are the two-dimensional (2D) perovskites -a blend of perovskites with layered crystal structure- (Ruddlesden-Popper type) offer a greater synthetic versatility and allow for more specialized device implementation due to the directional nature of the crystal structure. A remarkable advantage of the 2D perovskites is that their functionality can be easily tuned by incorporating a wide array of organic cations into the 2D framework, in contrast to the 3D analogues which have limited scope for structural engineering. We also present the new homologous series, (C(NH2)3)(CH3NH3)nPbnI3n+1 (n = 1, 2, 3), of layered 2D perovskites which is different from Ruddlesden-Popper type. Structural characterization by single-crystal X-ray diffraction reveals that these compounds adopt an unprecedented structure type which is stabilized by the alternating ordering of the guanidinium and methylammonium cations in the interlayer space (ACI). The these 2D perovskites combine structural characteristics from both Dion-Jacobson (DJ) and Ruddlesden-Popper (RP) structure archetypes. Compared to the more common Ruddlesden-Popper (RP) 2D perovskites, the perovskites we describe here have a different stacking motif and adopt a higher crystal symmetry.
Jennifer Stockdill, Wayne State University
Strategies and Methods for the Synthesis of Neuroactive Disulfide-Linked Peptides
Chiral fluids, surface waves, and the inherent instability of odd viscosity fluidsWarm up: 12:00 bring lunch
OK GO: 12:15
IME Distinguished Colloquium Series: Uli Weisner, Cornell University
Molecular Engineering of Functional Hybrid NanomaterialsGlobal problems including energy conversion and storage, clean water and human health require increasingly complex, multi-component and functional materials with unprecedented control over composition, structure, and order down to the nanoscale. This talk will give examples for the rational design of novel functional hybrid nanomaterials inspired by biological examples. Discussion will include formation of self-assembled hybrid nanoparticles as well as polymer-nanoparticle self-assembly derived synthetic porous materials with amorphous, polycrystalline, and epitaxially grown single-crystal structures. Experiments will be compared to theoretical predictions to provide physical insights into formation principles. The aim of the described work is to understand the underlying fundamental chemical, thermodynamic and kinetic formation principles enabling generalization of results over a wide class of materials systems. Examples will cover the formation of hierarchical structures at equilibrium as well as via processes far away from equilibrium. Targeted applications of the prepared systems will include the development of ultrasmall fluorescent hybrid probes for nanomedicine (“C dots”), nanostructured hybrids for energy conversion and storage devices, self-assembled asymmetric ultrafiltration membranes, as well as the formation of first self-assembled superconductors.
MRSEC / KRUSS Surface Science Seminar
Surface Chemistry Measurements, Applications, and Instrumentation9:00 AM - 9:10 AM Welcome and Introduction
9:10 AM - 10:10 AM Contact Angle/Liquid-Solid Interface/Surface Free Energy, Dr. Raymond Sanedrin, KRUSS Scientific Instruments, Inc.
10:15 AM – 10:30 AM DSA Droplet Drying : Analysis of Water Adhesion to Flexible Mesh, Kelliann Koehler, Tian Group
10:35 AM – 11:35 AM Surface/ Interfacial Tension Liquid-Air Interface by Mark McCarthy, KRUSS Scientific Instruments, Inc.
11:40 AM – 11:55 AM Scaling puzzles of forced wetting, Mengfei He, Nagel Group
11:55 AM – 12:00 PM Questions? (ALL)
12:00 PM – 1:00 PM Lunch Break
1:05 PM – 1:35 PM Foam Analysis/Bubble Structure/Liquid Content, Mr. Art Kasson, KRUSS Scientific Instruments, Inc.
1:45 PM – 5:00 PM Demos K100, DSA100, MSA, SDT
Rodney Ewing, Stanford University
Projecting Risk into the Future: Failure of a Geologic Repository and the Sinking of the TitanicOver one hundred years ago, the “unsinkable” RMS Titanic struck an iceberg in the North Atlantic and sank on its maiden voyage from Southampton, UK, to New York City. This “accident” and others, such as the tragedy at Fukushima Daiichi, can provide insight into the challenges that face the geologic disposal of radioactive waste. In this presentation, I reflect on the essential differences between analyzing the failure of engineered structures vs. a “failed” geologic repository. Perhaps, the most important difference is that for most countries there will only be a single repository, and we will never “see” that repository “in operation,” as the operational phase of a geologic repository comes long after it has been filled with waste and sealed. The time-scales considered for the geologic disposal of radioactive waste place special demands on the analysis of how engineered and geologic systems might fail. As scientists and engineers, we should reflect on the sobering reality of how difficult it is to project the future behavior of a geologic repository over extended spatial and temporal scales that stretch over tens of kilometers and out to a hundreds of thousands of years. I will offer a few short observations on the state of the U.S. nuclear waste management program and ideas for moving forward.
Jiwoong Park, University of Chicago
3D Circuitry and Folding with 2D CrystalsTwo thousand years ago, the mass-manufacturing of paper simplified all aspects of information technology: generation, processing, communication, delivery and storage. Similarly powerful changes have been seen in the last century through the development of integrated circuits based on silicon. Monolayers of 2D crystals provide an ideal material platform for realizing these integrated circuits thin and free-standing, which were the key advantages of paper over other medium two thousand years ago. Once realized, these atomically thin circuits will be foldable and actuatable, which will further increase the device density and functionality, allowing them to be used tether-free (or wirelessly) in environments not previously accessible to conventional circuits, such as water, air or in space. In this talk, we will discuss our recent progresses toward building atomically-thin integrated circuits using wafer-scale 2D crystals. In order for this, we developed a series of a! pproaches that are scalable, precise, and modular. We developed wafer-scale synthesis of three atom thick semiconductors, reported a wafer-scale patterning method for one-atom-thick lateral heterojunctions, and showed how atomically thin films and devices can be vertically stacked to form more complicated 3D circuitry. Then we will discuss our most recent efforts to turn these 2D circuits into 3D structures.
The Tuesday JFI Seminar - Prof. Jiangping Hu, Institute of Physics, Chinese Academy of Science
Genes of Unconventional High Temperature SuperconductorsIn the past, both cuprates and iron-based high temperature superconductors (High Tc) were discovered accidentally. Lacking of successful predictions on new high Tc is one of major obstacles to reach a consensus on unconventional high Tc mechanism.
In this talk, we address the key question related to these two special materials: Why are Cu and Fe special? We answer this question by suggesting a common electronic gene behind these two families of materials. The common electronic gene explains their rareness as unconventional high Tc superconductors and can guide us to search for new high Tc materials. We extend this idea to predict possible unconventional high Tc superconductors. Verifying the prediction can convincingly establish high Tc superconducting mechanism and pave a way to design new high Tc superconductors. Host; Cheng Chin, 2-7192 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Michael R. Wasielewski, Northwestern University
Singlet Fission in Organic Semiconductors: A Path to Enhanced Solar Cell Efficiencies
Yang Qin, University of New Mexico
Design, Preparation and Application of Organic/Inorganic Hybrid MaterialsIn this presentation, I will describe our research efforts in developing bottom-up approaches toward organic/inorganic hybrid materials with tailor-designed chemical structures, controlled nanomorphologies and specifically targeted functions. First, a versatile toolbox employing supramolecular chemistry that is capable of precisely nanostructuring multi-component hybrid materials through self-assembly processes is described. Specifically, we show that well-defined conjugated polymer (CP)/fullerene core-shell composite nanofibers (NFs) can be obtained through cooperation of orthogonal non-covalent interactions including block copolymer (BCP) self-assembly, CP crystallization, fullerene aggregation and hydrogen bonding interactions. Organic photovoltaic (OPV) devices applying these NFs display improved controllability of morphologies at both macroscopic and microscopic levels, as well as enhanced efficiencies and stability, over their conventional bulk heterojunction (BHJ) counterparts. Secondly, I discuss the design and synthesis of a new class of Pt-containing small molecules possessing unusual "roller-wheel" shaped geometry, leading to improved crystallinity and inter-molecular interaction, as well as higher OPV performance than previously reported Pt-containing CPs. Lastly, our recent efforts in controlling nanomorphologies of metal-organic frameworks (MOFs) will be discussed. By using a templated growth mechanism, well-defined one-dimensional MOF nanotubes and nanorods could be obtained by simply varying the reactant concentrations. Interestingly, single crystalline MOF nanowires could be obtained by using a template with smaller pore dimensions, revealing useful information on the MOF growth mechanisms under spatially confined environment.
Coordinated Dance of levitating particles in a thermal cellad-hoc discussion: 12:00
the dance begins: 12:15
Chin-Tu Chen, University of Chicago
"Atoms for Peace" in Medicine and BiologyCP-1’s impact on biomedicine has been far-reaching and long-lasting, including the direct benefits of enabling fundamental biomedical research and also of saving numerous human lives. Man-made radioisotopes, produced either by nuclear reactors or particle accelerators, have been widely used for both diagnosis and treatment of major health abnormalities such as cancers, cardiovascular diseases, brain and behavior disorders, diabetes, tissue and organ injuries, etc. Radiation related technologies, many originated from nuclear physics, high-energy physics, etc., have also helped advance the development of multiple generations of biomedical imaging and therapy instruments with increasingly more and better functionalities over the last eight decades. These radiation related R&D have led to earlier and more accurate diagnosis of diseases and more efficient and effective treatments of patients, resulting in substantial saving in both human lives and societal resources.
One of the spin-offs from the CP-1 is the establishment of the Argonne Cancer Research Hospital (ACRH) at The University of Chicago in 1953 - renamed later as the Franklin McLean Memorial Research Institute (FMI) in 1970s - for research on the peaceful use of atomic and nuclear energy in medicine and biology. Early researchers at the ACRH/FMI had pioneered the development of new imaging and therapeutic radiotracers including the first clinical use of Tc-99m to detect brain tumor and more effective production of I-125 for both research and clinical uses, designing and developing novel approaches in radiation therapy and chemotherapy for treating cancer, identification of chromosomal translocation as the cause of leukemia and other cancers, discovery of erythropoietin (EPO) and development of its purification methods, etc. These and other UChicago research contributions are representative of a much broader scope of the impact of PC-1 on medicine and biology in general, which has been actively continuing and expanding into the future.
Paramjit S. Arora, New York University
Protein Domain Mimics as Modulators of Protein-Protein InteractionsProtein−protein interactions (PPIs) are ubiquitous in biological systems and often misregulated in disease. As such, specific PPI modulators are desirable to unravel complex PPI pathways and expand the number of druggable targets available for therapeutic intervention. However, the large size and relative flatness of PPI interfaces make them challenging molecular targets. This presentation will describe our systematic approach using secondary and tertiary protein domain mimics (PDMs) to specifically modulate PPIs. Our strategy focuses on mimicry of regular secondary and tertiary structure elements from one of the PPI partners to inspire rational PDM design. Current applications of the overall approach to develop small molecule cancer therapeutics will be discussed.
The Tuesday JFI Seminar - Dr. Kin Chung Fong, Raytheon BBN Technologies
Looking for Relativistic Hydrodynamics in Solid State PhysicsInteractions between the Dirac fermions in graphene can lead to
new collective behavior described by hydrodynamics. By listening
to the Johnson noise of the electrons, we are able to probe
simultaneously the thermal and electrical transport of the Dirac fluid
and observe how it departs from Fermi liquid physics. At high
temperature near the neutrality point, we find a strong
enhancement of the thermal conductivity and breakdown of
Wiedemann-Franz law in graphene. This is attributed to the non-
degenerate electrons and holes forming a strongly coupled Dirac
fluid. We shall take an outlook on the hydrodynamic physics
experiments in solid state systems. Ref: Science 351, 1058 (2016)
For further information contact: Host: Dam Thanh Son, 773-834-9032. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or via email to email@example.com.
Xiao Wang, Stanford University
RNA-Centered Perspective of Gene Expression in Time and Space
Professor Noah Burns, Stanford University
Synthesis and Study of Unusual Lipids
Making Majoranas in Silicon: twisting electrons for quantum information on the cheapfeed body: 12:00
feed mind: 12:15
Robert (Bo) Jacobs, Hiroshima Peace Institute and Hiroshima City University
The Fallout of Chicago Pile-1
The critically important Chicago Pile-1 experiment midwifed both nuclear energy and nuclear weaponry into our world. Few single experiments have shaped human society with the depth of the first controlled nuclear chain reaction. This talk outlines the social impacts of both nuclear weapons and nuclear power during the last 75 years. Beyond this survey, it examines the discourse of human competence that belies both nuclear technologies and facilitates beliefs that we can control apocalyptic weaponry, and safely manage high-level nuclear waste for thousands of generations.
Tom Witten, University of Chicago
How asymmetric colloidal particles create hyperuniform dispersionsHyperuniformity of a many-body system means anomalously small density fluctuations. In an ordinary liquid or solution the mean-squared fluctuations E(N - E(N))^2 of particle number N in a given region are proportional to the average particle number E(N). By contrast, in a hyperuniform system E(N - E(N))^2/E(N) goes to 0 as N goes to infinity. The classic example is the one-component plasma, a gas of charged particles with a uniform neutralizing background charge. Recently granular materials and periodically sheared colloidal dispersions were shown to be hyperuniform. We investigate the question of uniformity in a dilute colloidal dispersion in which particles are settling under gravity. When the particles are of generic shapes, their asymmetry strongly affects their interaction via the coupling between orientation, drag and fluid velocity gradients. Two isolated objects generally separate over time. In one regime hyperuniform and anisotropic behav! ior of th e density correlation function probed by light scattering is inevitable.
 S.Torquato, Rev. Mod. Phys, vol.82, 2633-2640 (2010).
 D. Hexner and D. Levine, Phys. Rev. Lett., vol.114, 110602 (2015).
The Tuesday JFI Seminar - Prof. Sabre Kais, Department of Chemistry, Purdue University
Near Term Applications of Quantum Simulation and Quantum Computing DevicesThe exact solution of the Schrödinger equation for atoms, molecules and extended systems continues to be a “Holy Grail” problem for the field of atomic and molecular physics since inception. Recently, breakthroughs have been made in the development of hardware-efficient quantum optimizers and coherent Ising machines capable of simulating hundreds of interacting spins through an Ising-type Hamiltonian. One of the most vital questions associated with these new devices is: “Can these machines be used to perform electronic structure calculations?” In this talk I will discuss the possibility of mapping the electronic structure Hamiltonian to an Ising type Hamiltonian and present the simulation results of the transformed Ising Hamiltonian for small molecules such as H2, He2, HeH+, LiH and H2O. Future directions for scaling up the simulations to larger systems will be also discussed.For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may also contact the Host, David Mazziotti at 773-834-1762 or via email at email@example.com.
IME Distinguished Speakers in Technology & Industry: Darlene Solomon, Agilent Technologies
A View into the "Century of Biology" and AgilentTechnology leadership based on a culture of innovation, contribution and sustained R&D investment has been at the core of Agilent's success through decades of market and technology waves. Today, biology is the field where science and understanding are most rapidly changing. This talk will highlight key megatrends in this 'century of biology', Agilent's transition from being a predominantly electronics and semiconductor company into one fully-focused on the life science and diagnostics industries, and some of the technology contributions underway at Agilent that will underlie tomorrow's breakthroughs.
Professor Sukbok Chang, KAIST
Development of Direct C-H Amination Reactions
George S. Sheppard, ABBVIE
The discovery of BET Bromodomain Inhibitor ABBV-075
Shubhayu Chatterjee, Harvard University
Intertwining topological order and discrete broken symmetries in the hole-doped cuprates via quantum fluctuating antiferromagnetismThe enigmatic pseudogap metal phase of the hole-doped cuprate superconductors has two seemingly unrelated characteristics: (i) a gap in the electronic spectrum along the axes of the square lattice Brillouin zone, and (ii) the presence of discrete broken symmetries (like rotation, inversion or time-reversal). In a normal metal with full translational symmetry, a gap in the electron spectrum in the anti-nodal region cannot be explained by such broken symmetries. We propose a resolution to this puzzle by intertwining topological order with broken symmetries in the pseudogap metal. We show that the required flavors of topological order, corresponding to precisely the broken symmetries observed in the cuprates, arise naturally in a SU(2) gauge theory of quantum fluctuations of magnetically ordered phases that lie proximate to the Néel phase. We explore how alternative descriptions of fluctuating Néel antiferromagnets, in terms of the semiclassical O(3) non-linear σ model, and the CP1 model, also naturally lead to the same phases. If time permits, we will also discuss comparisons between the gauge theory and recent numerical (DMFT and QMC) results on the two-dimensional Hubbard model.
Professor Xavier Roy, Columbia University
Molecular Clusters: Building Blocks for Nanoelectronics and Material Design
Two shades of forced wettingEat: high noon
Talk: high 12:15
Melissa Franklin, Harvard University
Dear Maria, Oh My, How Particle Physics has ChangedThis talk will in effect be a letter to Maria Goeppert-Mayer and other pioneering women particle physicists, describing both a brief history of the particle accelerators that have made remarkable discoveries in particle physics possible and the slow turn of experimentalists attention from the discovery of the building blocks of matter to the study of the universe with nothing in it, the so-called vacuum.
Juan De Pablo, University of Chicago, IME
Emerging Insights into Directed Assembly: Taking Examples from Nature to Design Synthetic ProcessesThere is considerable interest in controlling the assembly of polymeric material in order to create highly ordered materials for applications. Such materials are often trapped in metastable, non-equilibrium states, and the processes through which they assemble become an important aspect of the materials design strategy. An example is provided by di-block copolymer directed self-assembly, where a decade of work has shown that, through careful choice of process variables, it is possible to create ordered structures whose degree of perfection meets the constraints of commercial semiconductor manufacturing. As impactful as that work has been, it has focused on relatively simple materials – neutral polymers, consisting of two or at most three blocks. Furthermore, the samples that have been produced have been limited to relatively thin films, and the assembly has been carried out on ideal, two-dimensional substrates. The question that arises now is whether one can tra! nslate th ose achievements to polymeric materials having a richer sequence, to monomers that include charges, to three-dimensional substrates, or to active systems that are in a permanent non-equilibrium state. Building on discoveries from the biophysics literature, this presentation will review recent work from our group and others that explains how nature has evolved to (1) direct the assembly of nucleic acids into intricate, fully three-dimensional macroscopic functional materials that are not only active, but also responsive to external cues, and (2) to direct the assembly of polymeric actin and tubulin filaments into liquid crystalline phases, where the interplay between elasticity and activity can be used to manipulate the dynamics of the system. The results presented in this talk will then be used to discuss how one might design a new generation of synthetic active systems capable of performing specific, engineered functions.
Professor Christophe Coperet, ETH Zurich, Wheland Lecture
Surface Coordination Chemistry
The Tuesday JFI Seminar - Prof. Wassem Bakr, Department of Physics, Princeton University
Site-Resolved Microscopy of Ultracold Fermi-Hubbard Systems in new RegimesThe ability to probe and manipulate ultracold fermions in optical lattices at the atomic level using quantum gas microscopes has enabled quantitative studies of Fermi-Hubbard models in a temperature regime that is challenging for state-of-the-art numerical simulations. Experiments have focused on spin-balanced gases of repulsively interacting atoms with the hope of elucidating phenomena in high-temperature superconductors. In this talk, I will present experiments that explore the Hubbard model in two new regimes: repulsive gases with spin-imbalance and attractive spin-balanced gases. In the first regime, we observe canted antiferromagnetism at half-filling, with stronger correlations in the direction orthogonal to the magnetization. Away from half-filling, the polarization of the gas exhibits non-monotonic behavior with doping, resembling the behavior of the magnetic susceptibility of the cuprates. The attractive Hubbard model studied in the second set of experiments is the simplest theoretical model for studying pairing and superconductivity of fermions in a lattice. Our measurements on the normal state reveal checkerboard charge-density wave correlations close to half-filling. The charge-density-wave correlations are a sensitive thermometer in the low temperature regime relevant for future studies of inhomogeneous superfluid phases in spin-imbalanced attractive gases.For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may also contact the Host, Jonathan Simon at 773-702-9661 or via email to email@example.com.
Professor Christophe Coperet, ETH Zurich, Wheland Lecture
NMR Chemical Shifts: Beyond Numbers and How to Use them to Decode the Reactivity of Organometallic Compounds
Professor Christophe Coperet, ETH Zurich, Wheland Lecture
Molecular Understanding and Controlled Functionalization of Surfaces Towards Single-Site Catalysts and Beyond
blob of self-confining turbulence12:00 staging: bring lunch
12:15 execution: launch
Carlo Rubbia, Nobel Prize in Physics 1984
Nigel Goldenfeld, University of Illinois
The life and death of turbulenceHow do fluids become turbulent as their flow velocity is increased? During the last ten years, exquisite experiments, numerical simulations and pure theory have uncovered a remarkable series of connections between transitional turbulence, phase transitions and renormalization group theory, high energy hadron scattering, the statistics of extreme events, and even population biology. In this talk, I will outline how these developments and strange connections imply that a fluid at the boundary between turbulence and laminar flow behaves precisely like an ecosystem at the verge of extinction, a prediction that is supported by recent experiments.
The Tuesday JFI Seminar - Prof. Philip Kim, Department of Chemistry, Harvard University
Materials in 2-dimension and Beyond: Platform for Novel Electronics and OptoelectronicsHeterogeneous interfaces between two dissimilar materials are an essential building block for modern semiconductor devices. The 2-dimensional (2D) van der Waals (vdW) materials and their heterostructures provide a new opportunity to realize atomically sharp interfaces in the ultimate quantum limit for the electronic and optoelectronic processes. By assembling atomic layers of vdW materials, such as hexa boronitride, transition metal chalcogenide and graphene, we can construct atomically thin novel quantum structures. Unlike conventional semiconductor heterostructures, charge transport in of the devices is found to critically depend on the interlayer charge transport, electron-hole recombination process mediated by tunneling across the interface. We demonstrate the enhanced electronic optoelectronic performances in the vdW heterostructures, tuned by applying gate voltages, suggesting that these a few atom thick interfaces may provide a fundamental platform to realize novel physical phenomena. In this presentation, we will discuss several recent development of electronic and optoelectronic properties discovered in the van der Waals heterostructures, including hydrodynamic charge flows, cross-Andreev reflection across the quantum Hall edges states, and interlayer exciton formation and manipulations. For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may also contact the Host, Jiwoong Park at 773-834-3179 or via email at email@example.com.
Tracy M. Handel, PhD, Dept. of Pharmacology, School of Medicine, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego.
Structure, Activation & Inhibition of Chemokine Receptors
Professor Dale L. Boger, Stiegliitz Lecture
Redesign of Vancomycin for Resistant Bacteria
Dr. Cynthia J. Jenks, Argonne National Laboratory
A Quasi-Walk Along the Surfaces of Quasicrystals and Argonne InterfacesFor ages, scientists considered a crystal to be a solid with a repetitive internal structure. This notion was dismantled when quasiperiodic materials were discovered. Much has been learned about these fascinating intermetallic materials since their discovery and their subtleties are even more complex than imagined early on. In this talk, the growth, structure and stability characteristics of quasicrystalline materials will be discussed. Emphasis will be on their surfaces, known to have unusual characteristics, and of which scanning probe microscopies have produced some spectacular images and local probes of composition and structure, particularly low-energy ion scattering, show interesting findings. In addition, the talk will highlight ongoing research in the chemical sciences at Argonne National Laboratory and opportunities for collaborations.
Barbara Jacak, UC Berkeley and Lawrence Berkeley National Lab
Nuclear Physics: Then and Now
IME Distinguished Colloquium Series: Jens Norskov, Stanford University
A Molecular View of Heterogeneous CatalysisThis lecture will outline a theory of heterogeneous catalysis that allows a detailed understanding of elementary chemical processes at transition metal surfaces and singles out the most important parameters determining catalytic activity and selectivity. It will be shown how scaling relations allow the identification of descriptors of catalytic activity and how they can be used to construct activity and selectivity maps for both thermal and electro-catalytic processes. The maps can be used to define catalyst design rules and examples of their use will be given.
Manu Prakash, Stanford University
Life in flatland: Toy models and systems to explore origins of behavior in non-neuronal ensemblesDiverse multi-cellular animals encode a breathtaking diversity of natural behaviors. Non local interactions in traditional nervous systems make the study of underlying origins of behavior in animals difficult (and fascinating). It is a well known fact that simple dynamical systems can also encode perplexing complexity with purely local update rules. In this talk, using a variety of toy models and systems, we will explore how complex behavior can arise in non-neuronal ensembles; or in short "how do animals with no brains (neurons), decide, compute or think?
The Tuesday JFI Seminar - Dr. Sho Yaida, Department of Chemistry, Duke University
Novel Phase Transition within Amorphous SolidsGlassy materials are omnipresent in everyday life from windows to plastics to piles of sand. Yet our understanding of both their (equilibrium) liquid and (out-of-equilibrium) solid phases lags far behind that of crystalline counterparts. Recent advances are rapidly changing the ways in which we understand these common-yet-physically-enigmatic materials. This talk overviews one such advance -- the discovery of the Gardner phase transition from normal to marginally-stable glasses. Our work in particular indicates that such a transition, first found in abstract infinite-dimensional models, can survive down to the three-dimensional world. This transition reinforces the overriding role of rugged free-energy landscapes that dictate physics of glassy systems, with tangible consequences on jamming, yielding, and beyond.
For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may also contact the Host, Arvind Murugan at 773-834-3146 or via email at email@example.com.
Manu Prakash, PhD, Bioengineering, Stanford University
Life in flatland: Emergent origins of behavior in non-neuronal systemsDiverse multi-cellular animals encode a breathtaking diversity of natural behaviors. Non local interactions in traditional nervous systems make the study of underlying origins of behavior in animals difficult (and fascinating). It is a well-known fact that simple dynamical systems can also encode perplexing complexity with purely local update rules. In this talk, using a variety of toy models and systems, we will explore how complex behavior can arise in non-neuronal ensembles; or in short "how do animals with no brains (neurons), decide, compute or think?”.
Professor Bryan Dickinson, University of Chicago
Molecular Imaging and Evolutionary Approaches to Probe and Control Biology
IME Special Seminar: Antoine Georges
Quantum Materials: Bridging Physical Mechanisms, Simple Models and Realistic ComputationsQuantum Materials display competing phases with fascinating physical properties, which result from the multiple degrees of freedom in presence (charge, spin, orbital, lattice) and from strong electronic correlations. In this talk, I will show how computational methods aimed at the quantum many-body problem can be combined with realistic electronic structure methods in order to shed light on these physical properties, help identify relevant mechanisms and formulate simple effective models. This will be mostly illustrated by rare-earth nickelates, a family of materials displaying a metal-insulator transition which can be controlled by strain, gating or light, pulses.
The Tuesday JFI Seminar - Suri Vaikuntanathan, Department of Chemistry, University of Chicago
Non-equilibrium Pathways for Self Assembly and OrganizationNonequilibrium forces can drive specific and novel pathways to modulate self-assembly and organization. The close connection between energy dissipation and organization is particularly apparent in biology. Indeed, it has been demonstrated that nonequilibrium forces are crucial for the functioning of biochemical processes responsible for error correction, adaptation and timing of events in the cell cycle. However, unlike the behavior and characteristics of equilibrium systems, where no energy is dissipated, general principles governing fluctuations about a steady state or the steady state itself in far-from-equilibrium conditions are just being discovered. In my talk, I describe how tools from non-equilibrium statistical mechanics can be used to direct self assembly far-from-equilibrium, engineer novel spatiotemporal correlations in active liquids, and finally support properties such as ultra sensitivity in non-equilibrium biochemical networks. These results provide a framework for uncovering fundamental design principles of organization in non-equilibrium chemical and biological processes.
For further information please contact Brenda Thomas at 773-702-7156 or by email at firstname.lastname@example.org. You may contact the Host, Aaron Dinner at 773-702-2330 or via email to email@example.com.
Polina Anikeeva, PhD, MatSci and Eng, MIT
Probing Neural Function with Electronic, Optical & Magnetic MaterialsMammalian nervous system contains billions of neurons that exchange electrical, chemical and mechanical signals. Our ability to study this complexity is limited by the lack of technologies available for interrogating neural circuits across their diverse signaling modalities without inducing a foreign-body reaction. My talk will describe neural interface strategies pursued in my group aimed at mimicking the materials properties and transduction mechanisms of the nervous system. Specifically, I will discuss (1) Fiber-based probes for multifunctional interfaces with the brain and spinal cord circuits; (2) Magnetic nanotransducers for minimally invasive neural stimulation; and (3) Active scaffolds for neural tissue engineering and interrogation.
Fiber-drawing methods can be applied to create multifunctional polymer-based probes capable of simultaneous electrical, optical, and chemical probing of neural tissues in freely moving subjects. Similar engineering principles enable ultra-flexible miniature fiber-probes with geometries inspired by nerves, which permit simultaneous optical excitation and recording of neural activity in the spinal cord allowing for optical control of lower limb movement. Furthermore, fiber-based fabrication can be extended to design of scaffolds that direct neural growth and activity facilitating repair of damaged nerves.
Molecular mechanisms of action potential firing inspire the development of materials-based strategies for direct manipulation of ion transport across neuronal membranes. For example, hysteretic heat dissipation by magnetic nanomaterials can be used to remotely trigger activity of neurons expressing heat-sensitive ion channels. Since the alternating magnetic fields in the low radiofrequency range interact minimally with the biological tissues, the magnetic nanoparticles injected into the brain can act as transducers of wireless magnetothermal deep brain stimulation. Similarly, local hysteretic heating allows magnetic nanoparticles to disrupt protein aggregates associated with neurodegenerative disorders.
Professor Yossi Weizmann, University of Chicago
Synthetic Nucleic Acid Topology and Colloidal LEGO-Like Nanoparticles for Biological and Plasmonic Applications
Frederick A. Heberle, PhD, Biology & Soft Matter Oak Ridge National Laboratory
Lipid organization in complex biomimetic membranes: Insight from Scattering & SimulationThe 3-dimensional architecture of biological membranes has functional consequences for living cells. In the outer leaflet of the plasma membrane, lipids are thought to organize into ordered yet fluid domains, with diverse evidence supporting participation of these “rafts” in membrane processes including protein sorting and signaling. Cells also actively maintain an asymmetric distribution of different lipid types between the plasma membrane’s inner and outer leaflets, resulting in transmembrane differences in fluidity and charge density. Despite intense interest, the fundamental mechanisms controlling raft size and morphology, as well as coupling between leaflets of different composition, remain elusive. The precise determination of phase-separated and asymmetric bilayer structure is a crucial step toward a deeper understanding of these mechanisms. To this end, small-angle neutron and X-ray scattering are powerful biophysical tools for interrogating both lateral and transverse bilayer structure with sub-nanometer resolution. Molecular dynamics simulations probe further still, providing a glimpse of membrane organization with atomic detail. In this talk, I will describe new approaches for combining experimental and computational data to obtain a detailed structural picture of complex biomimetic membranes.
IME Seminar: Aaron Streets, University of California, Berkeley
Imaging and Sequencing Single CellsQuantitative cellular imaging with coherent Raman microscopy reveals morphological characteristics and chemical composition at the single-cell level. Meanwhile recent advances in high-throughput sequencing have enabled whole-transcriptome profiling of gene expression in single cells. Both measurements can uncover heterogeneity in cellular populations that would otherwise be obscured in ensemble measurement. Furthermore both imaging and gene expression profiling can be used to quantify cell state during differentiation. However, in order to infer the relationship between gene expression and morphological phenotypes, it is necessary to image and sequence the same single cell. We use a microfluidic platform to couple imaging and RNA sequencing of single cells and present recent developments on how to analyze large, multimodal, single-cell datasets.
Baruch Kanner, Hebrew University, Hadassah Medical School
Gating and Ion-Coupling by GAT-1, a GABA transporter from the Brain
Chiral waves from spinning tops: topology without long range order12:00 time to eat
12:15 time to listen and help
IME Seminar: Robert Seidel
Valence-Photoelectron and Auger-Emission Spectroscopy at the Solid-Liquid Interface
Special Seminar: Professor Yunho Lee, Department of Chemistry, KAIST
Small Molecule Activation of the Nickel Pincer Complexes
Kwang Seob Jeong, Department of Chemistry, Korea University
Magnetic Property of Colloidal Nanocrystals with Electrons in the Conduction BandThis seminar presents results on the magnetic property of the colloidal quantum dot with controlled electron doping and in the absence of any heterogeneous metal impurity, and its correlation with the optical property. Depending on the number of electrons, the magnetism can be switched from diamagnetism to paramagnetism, and vice versa. Furthermore, the intraband transition created by a cation exchange method, and the ultrafast intraband Auger process induced by multiphoton mid-IR irradiation will be discussed as well.
Simulating ricochet off of sand: Surprising behavior at low speed.Come at noon with food and conversations
Topic of the day at 12:15.
Special Seminar: Professor Alex Travesset, Iowa State University and Ames Laboratory
Geometry, Topology, and Nanoparticle Superlattice Structure
When the Hall effect throws you a curveEat: 12:00
Swerve with the curve: 12:15
Who choreographed my cell clusters?Eat: 12:00
solve mystery: 12:15
Molecular Tetris: Vapor Depositing to Enhanced Stabilitynoon: eat food
12:15 let the games begin.
IME Special Seminar: Phillip Szuromi, Senior Editor, Science
Scientific Publishing from the InsideI will give a brief overview of the mission of AAAS and the Science family of journals. I will then discuss how the review process works at Science, and how this has changed (and not changed) from the print to the internet era. Finally I will offer some thoughts on what we are looking for in a submission to help potential authors gauge the suitability of a submission.
Aaron Hoskins, PhD, Uwisc
Spliceosome Function and Structure
Molecular TherapeuticsCynthia Burrows, PhD
University of Utah
The Epigenetics of Guanine in G-Quadruplexes
Tarun Kapoor, PhD
Chemical Approaches to Dissect the Diverse Functions of Proteins in the AAA+ Superfamily
Jon Clardy, PhD
Harvard Medical School
Chemical Ecology and Molecular Therapeutics
Jason Gestwicki, PhD
University of California, San Francisco
Targeting Protein-Protein Interactions in Chaperone Networks
Nathanael Gray, PhD
Harvard Medical School
New Chemical Approaches to Drugging Oncogenic
Hening Lin, MD
Sirtuins and Novel PTMs in Cell Signaling and Cancer
Philip Cole, PhD
Johns Hopkins School of Medicine
Targeting Lysine Reversible Modifications with Designed Small Molecules
Prof. Liqiang Mai - State Key Laboratory of Advanced Technology for Materials Synthesis & Processing Wuhan University of TechnologyOne-dimensional nanomaterials can offer large surface area, facile strain relaxation upon cycling and efficient electron transport pathway to achieve high electrochemical performance. Hence, nanowires have attracted increasing interest in energy related fields. We designed the single nanowire electrochemical device for in situ probing the direct relationship between electrical transport, structure, and electrochemical properties of the single nanowire electrode to understand intrinsic reason of capacity fading. The results show that during the electrochemical reaction, conductivity of the nanowire electrode decreased, which limits the cycle life of the devices.1 We have fabricated hierarchical MnMoO4/CoMoO4 heterostructured nanowires by combining "oriented attachment" and "self-assembly".2 The asymmetric supercapacitors based on the hierarchical heterostructured nanowires show a high specific capacitance and good reversibility with a cycling efficiency of 98% after 1,000 cycles. Then, we designed the general synthesis of complex nanotubes by gradient electrospinning, including Li3V2(PO4)3, Na0.7Fe0.7Mn0.3O2 and Co3O4 mesoporous nanotubes, which exhibit ultrastable electrochemical performance when used in lithium-ion batteries, sodium-ion batteries and supercapacitors, respectively.3 In addition, we have successfully fabricated a field-tuned hydrogen evolution reaction (HER) device with an individual MoS2 nanosheet to explore the impact of field effect on catalysis.4 We also constructed a new-type carbon coated K0.7Fe0.5Mn0.5O2 interconnected nanowires through a simply electrospinning method. The interconnected nanowires exhibit a discharge capacity of 101 mAh g-1 after 60 cycles, when measured as a cathode for K-ion batteries.5 Our work presented here can inspire new thought in constructing novel one-dimensional structures and accelerate the development of energy storage applications.
Prof. Shaul Mukamel, Department of Chemistry & Department of Physics and Astronomy
Catching Conical Intersections in the Act; Ultrafast Multidimensional Spectroscopy with X-ray pulses and Quantum LightABSTRACT: Multidimensional spectroscopy uses sequences of optical pulses to study dynamical processes in complex molecules through correlation plots involving several time delay periods. Extensions of these techniques to the x-ray regime will be discussed. Ultrafast nonlinear x-ray spectroscopy is made possible by newly developed free electron laser and high harmonic generation sources. The attosecond duration of X-ray pulses and the atomic selectivity of core X-ray excitations offer a uniquely high spatial and temporal resolution. Stimulated Raman detection of an X-ray probe may be used to monitor the phase and dynamics of the nonequilibrium valence electronic state wavepackets created by e.g. photoexcitation, photoionization and Auger processes. Conical intersections (CoIn) dominate the pathways and outcomes of virtually all photophysical and photochemical molecular processes. Despite extensive experimental and theoretical effort CoIns have not been directly observed yet and the experimental evidence is being inferred from fast reaction rates and some vibrational signatures. Novel ultrafast X ray probes for these processes will be presented. Short X-ray pulses can directly detect the passage through a CoIn with the adequate temporal and spectral sensitivity. The technique is based on a coherent Raman process that employs a composite femtosecond/attosecond X-ray pulse to directly detect the electronic coherences (rather than populations) that are generated as the system passes through the CoIn. Diffraction of X- ray pulses can be used to image the transition charge densities associated with the electronic coherence.
Using the quantum nature of light in spectroscopy will be discussed. Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby manipulating the photophysical and photochemical reaction pathways. The photonic vacuum state of a localized cavity mode can be strongly mixed with the molecular degrees of freedom to create hybrid field- matter states known as polaritons. Simulations of the non-adiabatic avoided crossing of sodium fluoride in a cavity which incorporate the quantized cavity field into the nuclear wave packet dynamics will be presented. Numerical results show how the branching ratio between the covalent and ionic dissociation channels can be strongly manipulated by the optical cavity. Host: Norbert Scherer, 2-7069 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Yoav Lahini, Harvard University
Non-Monotonic Aging and Memory Retention in Disordered Mechanical SystemsI will describe the observation of slow relaxations, aging and memory effects - hallmarks of glassy dynamics – in the mechanical response of two disordered systems: thin sheets crumpled into a ball and elastic foams. In particular, I’ll report the observation of a non-monotonic aging response that can last many hours. I will then describe ongoing experiments that exploit the macroscopic nature of these systems to try and uncover the underlying mechanisms. The experimental results are in good agreement with a phenomenological framework recently used to describe observations of monotonic aging in several glassy systems. This suggests not only a general mechanism, but also that the non-monotonic behavior may be generic and that a-thermal, macroscopic systems can exhibit glassy behaviors.
The Tuesday JFI Seminar - Alan Aspuru-Guzik, Department of Chemistry & Chemical Biology, Harvard University
Billions and Billions of MoleculesMany of the challenges of the twenty-first century are related to molecular processes such as the generation and storage of clean energy, water purification and desalination. These transformations require a next generation of more efficient, chemically stable, and non-toxic materials. Chemical space, the space of all possible synthesizable molecules,is practicallyinfinite and promises to have relevant candidate functional molecules to address these
challenges. One of the main goals of my research group is to develop understanding and tools for the exploration chemical space in order to accelerate the discovery of organic materials. Our design cycle is sped up by the constant interaction of theoreticians and experimentalists, the use of high-throughput computational techniques,machine learning, and the development of specialized big data tools. We have had recent successes in theoretically predicting and experimentally confirming in record times top performers in the areas of organic electronics, organic flow batteries and organic lightemitting diodes. In this talk, I will discuss what I consider are the key factors related with a successful high-performance screening approach as illustrated by these three different applications. I will end by discussing the future prospects and challenges associated with developing appropriate metrics for the cartography of chemical space. Polina Navotnaya, 2-6066 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Jaeger Fest Symposium
The World in a Grain of SandThe central theme of this symposium is the emergent collective behavior of many interacting particles and the way this behavior manifests across leng scales: from the self-assembly of nanoparticles to the formation of planets.
Jaeger Fest Symposium
MRSEC Tutorials for graduate students and postdocsThe central theme of this symposium is the emergent collective behavior of many interacting particles and the way this behavior manifests across leng scales: from the self-assembly of nanoparticles to the formation of planets.
Jacob Bean, University of ChicagoHost: Mel Shochet
IME Distinguished Colloquium Series: Daniel Loss
Spin Qubits in Semiconductors: An Overview and OutlookThis talk will provide an overview of spin qubits in semiconducting nanostructures such as quantum dots and nanowires for electron and hole spins from a theorist's point of view. Despite enormous experimental efforts in many labs worldwide over the last twenty years, progress has been slow due to many challenges posed by complex material issues and the related many-body physics limiting the coherence of spin qubits. Nevertheless, the field has evolved steadily, in theory and experiment, and there is a strong belief in the community that the ultimate goal of building a powerful quantum computer most likely will be reached with spin qubits in semiconductor material which have the advantage of being inherently small and fast: In principle, it is possible to fit a billion spin qubits on a square centimeter and have them function at a clock speed of GHz. I will mention recent development and challenges for implementing surface code structures, in particular for Si or Ge hole-spin qubits in combination with superconducting striplines. If time permits, I will mention some recent theoretical ideas on hybrid systems which aim at combining topological qubits, such as Majorana fermions and parafermions, with spin qubits.
Cary Forest, Department of Physics, University of Wisconsin
Energy Transformation between Forms in the Big Red Plasma BallAstrophysical plasma are often characterized by quasi-stationary magnetized plasmas which both pressure dominated and flow dominated, and yet still behave as ideal plasmas with fluid and magnetic Reynolds numbers being large so that magnetic fields are frozen into the flowing, often turbulent plasma. The Big Red Plasma Ball is a flexible user facility designed to study a range of astrophysically relevant plasma processes in this unique regime, and to explore novel geometries and flows that mimic astrophysical systems. A multi-cusp magnetic bucket constructed from strong samarium cobalt permanent magnets now confines a 10 m3, fully ionized, magnetic-field-free plasma in a spherical geometry. Plasma parameters of Te ~5 to 20 eV and densities of ~1011 to 5 x 1012 cm-3 provide an ideal testbed for a range of astrophysical experiments, including self-exciting dynamos, plasma accretion via the magneto-rotational instability [MRI], collisionless magnetic reconnection, jet stability, stellar winds and more. This talk will describe the unique capabilities of BRPB, along with several experiments, in both operating and planning stages, that illustrate its possibilities. References: 1. C.B. Forest et al., J. Plasma Phys. 81, 345810501 (2015). 2. C. Cooper et al., Phys. Plasmas, 21, 013505 (2015).
The Tuesday JFI Seminar - Matteo Cargnello, Chemical Engineering Department, Stanford University
Tackling Big Challenges Using Tiny CrystalsABSTRACT: The understanding that fossil fuels are not endless and that their extensive use is causing irreversible climate changes prompted us to realize that we are in urgent need of sustainable energy generation processes, energy vectors, and solutions to reduce pollution and greenhouse gas emissions. Despite replacing fossil fuels while maintaining or improving the current standards of living with a growing population is one of the biggest challenges that we have to face, the solution might lie in tiny pieces of matter: nanocrystals. Nanocrystals have been known for a long time but it is only recently that we have been able to better study and control their properties. The advent of nanotechnology and its associated tools allowed indeed to manipulate the composition, size, shape, functionalization and assembly of nanocrystals and to create nanoarchitectures and macroscopic devices with novel properties and unrivaled performance. In this talk, the use of uniform and tailored nanocrystals for energy and environmental applications will be presented, with emphasis on how to precisely control the nanostructures to understand and exploit interactions between well defined building blocks. Applications include hydrogen generation through photocatalysis, reduction of methane emissions, pollution control, and fundamental understanding of reaction mechanisms. It is expected that advancements in the preparation and use of these tiny crystals can bring immense benefit for making big challenges more approachable. Host: Dmitri Talapin, 4-2607 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Closs Lecture-Martyn Poliakoff, University of Nottingham
Andrew Ferguson, PhD, UIUC Materials Science and Engineering Department
Machine learning in soft and biological materials: Engineering self-assembling colloids and viral phase behaviorData-driven modeling and machine learning have opened new paradigms and opportunities in the understanding and design of soft and biological materials. Colloidal particles with tunable anisotropic surface interactions are of technological interest in fabricating soft responsive actuators, biomimetic polyhedral encapsulants, and substrates for high-density information storage. In the first part of this talk, I will describe our applications of nonlinear manifold learning to determine low-dimensional "assembly landscapes" from computer simulations and experimental particle tracking data for self-assembling patchy colloids. These landscapes connect colloid architecture and prevailing conditions with emergent assembly behavior, informing how to engineer the stability and accessibility of desired aggregates. Empirical models of viral fitness present a means to rationally design antiviral therapeutics by revealing vulnerabilities within the viral proteome. In the second part of this talk, I will discuss the translation of clinical sequence databases into spin glass models of viral fitness that reveal an interesting connection with statistical thermodynamics in which a data-driven fitness model of HIV admits an "error catastrophe" – mutational meltdown of the viral quasispecies induced by an elevated mutation rate – isomorphic to a first order phase transition. Our work informs new antiviral control strategies and provides a rationale for why HIV can live on the precipice of the error catastrophe with impunity.
Erez Berg, University of ChicagoHost: Philippe Guyot-Sionnest
Sophie Martin, PhD, University of Lausanne
How to mate once and only once: Yeast gamete fusion rapidly reconstitutes a bi-partite transcription factor to block re-fertilization
Stuart Rowan, The University of Chicago
Using Dynamic Chemistry to Access Stimuli-Responsive and Adaptive MaterialsThe dynamic bond can be defined as any class of bond that selectively undergoes reversible breaking and reformation, usually under equilibrium conditions. The incorporation of dynamic bonds (which can be either covalent or non-covalent) allows access to structurally dynamic polymers. Such polymers can exhibit macroscopic responses upon exposure to an environmental stimulus, on account of a rearrangement of the polymeric architecture. In such systems, the nature of the dynamic bond not only dictates which stimulus the material will be responsive to but also plays a role in the response itself. Thus, such a design concept represents a molecular level approach to the development of new stimuli-responsive materials. We have been interested in the potential of such systems to access new material platforms and have developed a range of new mechanically stable, structurally dynamic polymer films that change their properties in response to a given stimulus, such as temperature, light or specific chemicals. Such adaptive materials have been targeted toward applications that include healable plastics, responsive liquid crystalline polymers, chemical sensors, thermally responsive hydrogels, shape memory materials and mechanically dynamic biomedical implants. Our latest results in this area will be discussed.
The Tuesday JFI Seminar - Mohammad Hafezi, Joint Quantum Institute, University of Maryland
Topological Photonics: From Classical to QuantumThere are tremendous efforts underway to better understand systems with topological features --- global properties that are not discernible locally. The best-known examples are quantum Hall effects in electronic systems, where insensitivity to local properties manifests itself as conductance through edge states that are insensitive to defects and disorder. In this talk, I demonstrate how similar physics can be observed for photons; specifically, how various quantum Hall Hamiltonians can be simulated in an optical platform. I review the observation of topological photonic edge states using silicon-on-insulator technology, measurement of the associated topological invariants and our recent advances in studying the quantum transport of such structures. Furthermore, the addition of optical nonlinearity to this system provides a platform to implement fractional quantum Hall states of photons and anyonic states that have not yet been observed. More generally, the application of these ideas can lead to the development of optical devices with topological protection for classical and quantum information processing.
Stephen J. Lippard: Massachusetts Institute of Technology
Understanding and Improving Platinum Anticancer Drugs
Dmitri Feldman, Brown University
Particle-hole symmetry without particle-hole symmetry in the quantum Hall effect at ν = 5/2Numerical results suggest that the quantum Hall effect at the filling factor 5/2 is described by the Pfaffian or anti-Pfaffian state in the absence of disorder and Landau level mixing. Those states are incompatible with the observed transport properties of GaAs heterostructures, where disorder and Landau level mixing are strong. We show that the recent proposal of a PH-Pfaffian topological order by D. T. Son is consistent with all experiments. The absence of the particle-hole symmetry at the filling factor 5/2 is not an obstacle to the existence of the PH-Pfaffian order since the order is robust to symmetry breaking
Anthony Hyman, PhD, MPI Molecular Cell Biology and Genetics, Dresden
Biomolecular condensates: Organizers of cellular biochemistry
Danna Freedman:Northwestern University
Applying Inorganic Chemistry to Challenges in Physics
the faster you run, the less you rememberEat 12:00 noon
Joe Incandela, University of California,Santa Barbara/CERN
Zachariasen Lecture: "From the Higgs to dark matter: the search for the underlying code of our universe"
Lee Lecture: Professor Matthew Rosseinsky, University of Liverpool
Beyond the unit cell: control of function by local structure and dynamics from fuel cell electrodes to metal-organic frameworks
Luca Delacretaz, Stanford University
Transport with translational order and bad metalsI will present a hydrodynamic theory of weakly disordered electronic systems with fluctuating or static translational order, such as charge/spin density waves or Wigner crystals. This hydrodynamic approach leads to universal expressions for low frequency ac conductivities and viscosities. I will argue that similar ac conductivities are observed experimentally in a variety of bad metals, and conjecture that such materials have short range fluctuating charge order.
Jeremy England, MIT
Emergent Fine-tuning to Environment in a Complex Chemical reactionThe equilibrium steady state of an undriven mixture of reacting chemical species is uniquely determined by the free energy. Once external environmental drives are introduced, however, steady-state concentrations may deviate from these equilibrium values via sustained absorption and dissipation of work. From a physical standpoint, the living cell is a particularly intriguing example of such a nonequilibrium system, because the environmental work sources that power it are relatively difficult to access – only the proper orchestration of many distinct catalytic actors leads to a collective behavior that is competent to harvest and exploit available metabolites. Here, we study the dynamics of an in silico chemical network with random connectivity in a driven environment that only makes strong chemical forcing available to rare combinations of concentrations of different molecular species. We find that the long-time dynamics of such systems biased towards the spontaneous extremization of forcing, so that the molecular composition converges on states that exhibit exquisite fine-tuning to available work sources.
Lee Lecture: Prof. Matthew Rosseinsky, University of Liverpool
Design of Advanced Materials?
Lukasz Fidkowski, Stony Brook University
Chiral phases in Floquet quantum systems
Alex Miller: University of North Carolina at Chapel Hill
Cation-Responsive Pincer-Crown Ether Complexes for Tunable Catalysis
1st Annual UChicago MRSEC SymposiumLearn about ongoing work in the Materials Research Center!
Explore new collaborations & research directions!
GCIS 3rd Floor Atrium
11:30am -1:30pm: Lunch and Poster Session
1:30pm - 3:00pm: IRG 1 – Dynamics of Soft Interfaces
& IRG 2 – Active Materials
3:00pm - 3:15pm: Coffee Break
3:15pm-4:45pm: IRG 3 – Engineering Quantum Materials & Seed Research – “Multifunctional Interfaces of Different Dimensionality” & “Multifunctional Porous Materials”
4:45pm: Wine and Cheese
Lisa Manning, Syracuse University
Jamming in biological tissuesHost: Sid Nagel
Philip Nelson, University of Pennsylvania
Old and new news about single-photon sensitivity in human visionOne often hears that human vision is “sensitive to single photons,” when in fact the faintest flash of light that can reliably be reported by human subjects is closer to 100 photons. Nevertheless, there is a sense in which the familiar claim is true. Experiments conducted long after the seminal work of Hecht, Shlaer, and Pirenne now allow a more precise, and in some ways even more remarkable, conclusion to be drawn about our visual apparatus. A simple model that incorporates both old news (response of single rod cells) and newer news (loss at the first synapse) can account in detail for both old and new psychophysical data.
The 2nd Tuesday JFI Colloquium - Eric Borguet - Department of Chemistry, Temple UniversityInterfacial water structure, which can be probed by vibrational sum-frequency generation (vSFG) spectroscopy, is key to many processes. Time-resolved vSFG shows that in the absence of surface charge (pH 2), water at silica surfaces exhibits significantly slower OH stretch vibrational relaxation (~600 fs) compared to bulk water. However, at charged silica surfaces (e.g., pH 6), bulk-like fast dynamics (~200 fs) are observed at low ionic strength. This decelerates to ~600 fs, with the addition of NaCl. In parallel, vSFG results demonstrated that silica interfacial water structure is most sensitive to cations at pH=6-8. Consequently, it is unclear whether the observed slowing of the vibrational dynamics is due to the reduction in Debye length, or because of changes in the local hydrogen bonding environment caused by the electrolyte and how this might depend on the identity of the ions. Additional spectroscopic and time-resolved vSFG experiments on aqueous Al2O3 interfaces shed light on the ongoing debate on the role of ions in interfacial water structure and whether the observed behavior is specific to silica/water interfaces or can be generalized to other systems. Philippe Guyot-Sionnest, 2-7461 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Snir Gazit, University of California at Berkeley
Charged fermions coupled to Ising gauge fields: Symmetry breaking, confinement, and emergent Dirac fermions.Lattice gauge theories are ubiquitous in physics, describing a wide range of phenomena from quark confinement to quantum materials. At finite fermion density, gauge theories are notoriously hard to analyze due to the fermion sign problem. Here, we investigate the Ising gauge theory in 2+1 dimensions, a problem of great interest in condensed matter, and show that it is free of the sign problem at arbitrary fermion density. At generic filling, we find that gauge fluctuations mediate pairing leading to a transition between a deconfined BCS state to a confined BEC. At half-filling, a π-flux phase is generated spontaneously with emergent Dirac fermions. The deconfined Dirac phase, with a vanishing Fermi surface volume, is a non-trivial example of violation of Luttinger's theorem due to fractionalization. At strong coupling, we find a single continuous transition between the deconfined Dirac phase and the confined BEC, in contrast to the expected split transition.
Kharasch Memorial Lecture - Sir Shankar Balasubramanian, University of Cambridge
How large is the natural DNA alphabet?
Peter Littlewood, University of Chicago
Physics of SustainabilityHost: Mel Shochet
Daniel Scolnic, University of Chicago
Measuring the size of the Universe with Standard CandleAstrophysicists use standard candles, objects which have roughly the same luminosity, to infer distances to far-away parts of the universe. Standard candles of variable stars called ‘cepheids’ were used to discover the expanding universe, and standard candles of exploding stars called ‘supernovae’ were used to discover the accelerating universe. Together, these two standard candles can be used to measure the size of the universe. Interestingly, this measurement of the size of the universe recovered conflicts with measurements of the size of the universe from extrapolations of data from the Cosmic Microwave Background. I will go over how we make our measurement, from soup to nuts, and discuss how we can be confident in the accuracy of our values. I will then discuss different ways too explain the tension we see in the different sets of measurements, and possible new physics that may be on the horizon.
The 1st Tuesday JFI Colloquium - Benjamin Lev, Department of Physics and Applied Physics - Stanford University
New Tools for Exploring Nonequilibrium Quantum Many-Body PhysicsABSTRACT: The simulation of quantum systems using ultracold atomic gases—quantum simulation—may be viewed as the creation of novel quantum systems in their own right rather than the simulation of well-known models. Often these systems possess collective properties impossible to observe in the solid state. In particular, these gaseous systems provide unique testbeds for emergent physics, especially that out of equilibrium. We present two novel avenues of inquiry into quantum nonequilibrium physics: the creation of dissipative quantum spin glasses and quantum neural networks using atoms coupled to the photonic modes of a confocal optical resonator and the study of nonequilibrium quench dynamics in highly magnetic and strongly interacting gases. Besides investigating long-unresolved issues in statistical mechanics (i.e., the order of spin glasses and thermalization in closed quantum systems), the experimental directions discussed point to novel neuromorphic computational architectures relying on driven-dissipative quantum dynamics.Host: Jonathan Simon, 2-9661 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Kharasch Memorial Lecture - Sir Shankar Balasubramanian, University of Cambridge
Decoding human genomes on a population scale
Dominic Else, University of California, Santa Barbara
Floquet Time Crystals: How time-translation symmetry protects phases of matterA "Floquet time crystal" is a phase of matter in a periodically driven (Floquet) system which spontaneously breaks discrete time-translation symmetry. They are an entirely new "non-thermal" phase of matter which cannot exist in undriven systems. In this talk, I will discuss the recent theoretical prediction and experimental observation of Floquet time crystals. Time-translation symmetry occupies a special role in physics, since its generator is the Hamiltonian itself. Nevertheless, the theoretical formulation of time crystals turns out to be *almost* the same as for other symmetry-breaking phases of matter. I will also consider phases of matter in which the discrete time-translation symmetry is not spontaneously broken but nevertheless protects non-trivial phases, which are the analogs of "symmetry-protected topological" and "symmetry-enriched topological" phases for other symmetries.
Jingyuan Chen, Stanford University
Exact Bose-Fermi Duality on 3D Euclidean LatticeRecently a conjectured Bose-Fermi duality in 3 spacetime dimensions has drawn much interest from both high energy and condensed matter communities. We prove this duality by constructing an exact duality on lattice and showing our exact duality reduces to the conjectured duality in the continuum limit. All steps are analytic, exact, and simple.
Qiu Wang, Duke University
Leveraging Chemistry for Biology and Therapy: – New amination strategies to access biologically important molecules
Cameron Reed, Alma College
The Manhattan Project: A Look at the Physics"Host: Henry Frisch
Andrew Kruse, PhD, Harvard Medical School
New approaches to investigate G protein-coupled receptor function
Lenka Zdeborova, CNRS & CEA, Saclay, France
Statistical physics approach to compressed sensing and generalized linear regressionBayesian inference and statistical physics are formally closely related. Therefore methodology and concepts developed in statistical physics to understand disordered materials such as glasses and spin glasses can be elevated to analyze models of in statistical inference. We will present this approach in a rather general setting that covers analysis of compressed sensing, generalized linear regression, and the perceptron - a kind of a single layer neural network. At the one hand, this approach leads to the approximate message passing algorithm that is gaining its place among other widely used regression and classification algorithms. At the other hand, the related analyses leads to identification of phase transitions in the performance of Bayes-optimal estimators. We will discuss relation between these phase transitions and algorithmic hardness, and in the case of compressed sensing we will show how this understanding leads to a design of optimal measurement protocols.
Based partly on "Statistical-physics-based reconstruction in compressed sensing" PRX 2012 and reviewed in "Statistical physics of inference: Thresholds and algorithms" Advances of Physics 2016.
Andy Borovik:University of California, Irvine
Synthetic Chemistry as a Window into Biology
JFI Seminar - Prof. David Cobden, Department of Physics, Washington University
"Electronic Phases and Phase Transitions in Van der Waals Monolayers"ABSTRACT: Atomically thin materials can host many kinds of electronic phases, some unique to the 2D limit. Our observations indicate the realization of a quantum spin Hall state, an excitonic insulator, superconductivity, and ferro- and antiferromagnetism in van der Waals monolayers. Unlike 3D solids, monolayers are amenable to surface probes and can be doped by electrostatic gating. We are thus investigating ways to induce transitions between these phases electrostatically. In WTe2 monolayers at low temperatures we observe a transition between a two-dimensional topological insulator and a bulk conducting phase as a function of gate voltage, representing a gate-controlled quantum phase transition.Host: Jiwoong Park, 4-3179 or via email to firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Cenke Xu, University of California, Santa Barbar
self-dual quantum critical points in 2+1 dimensions
Jennifer M. Heemstra: University of Utah
Harnessing Nucleic Acid Molecular Recognition and Self-Assembly for Biosensing and Biomolecular Imaging
Two dynamical interfaces walk into an IRG…
a recap of tuesday's idea session12:00 Eat real food
12:15 digest bloblets
Zoran Hadzibabic, University of Cambridge
Quantum gas in a boxHost: Cheng Chin
Anette Hosoi, MIT
Hydrodynamics of Hairy SurfacesFlexible slender structures in flow are everywhere. While a great deal is known about individual flexible fibers interacting with fluids, considerably less work has been done on fiber ensembles, such as fur or hair, in flow. These hairy surfaces are abundant in nature and perform multiple functions from thermal regulation to water harvesting to sensing. Motivated by these biological systems, we consider two examples of hairy surfaces interacting with flow: (1) air entrainment in the fur of diving mammals and (2) symmetry breaking in hairy micro-channels.
In the first example, we take inspiration from semi-aquatic mammals (such as fur seals, otters, and beavers) which have specially adapted fur that serves as an effective insulator both above and below water. Many of these animals have evolved pelts that naturally entrap air when they dive. This air: (1) provides additional insulation under water, (2) provides added buoyancy, and (3) facilitates water shedding when the animals resurface. In this study we investigate diving conditions and fur properties which amplify air entrainment in fur. In the second example, we consider a fundamental component in hydraulic systems, the flow rectifier. One of the simplest ways to generate asymmetry in these devices is with a ball valve in which flow is completely obstructed in one direction and free to flow in the other. In this work we seek a variation that: (1) allows the designer to modulate the relative resistances in the rectifier and (2) can be achieved with solid state components (i.e. no moving parts).
The Tuesday JFI Seminar - Monika Schleier-Smith, Department of Physics, Stanford University
"Echoes of Entanglement: from Quantum Metrology to Scrambling"ABSTRACT: In the quest to approach the fundamental Heisenberg Limit in precision measurements, central challenges are the generation and detection of highly entangled states. I will describe how both of these challenges can be mitigated by “echo spectroscopy,” a technique inspired by the Loschmidt echo, a paradigmatic probe of chaos. A key ingredient is to effectively reverse the flow of time in an interacting many-body system by switching the sign of the Hamiltonian. I will describe progress towards engineering spin models with non-local, switchable-sign interactions using cold atoms strongly coupled to light an optical cavity. Intriguingly, similar non-local interactions feature in models for understanding fundamental bounds on chaos and information scrambling derived from the study of black holes, opening prospects for investigating these bounds in the laboratory.Host: Jonathan Simon, 2-9661 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Viviana Gradinaru, PhD, CALTECH
Optogenetic, tissue clearing, and viral vector approaches to understand and influence whole-animal physiology and behaviorWe develop & employ optogenetics, tissue clearing and viral vectors to gain new insights on circuits underlying locomotion, reward & sleep. I will discuss how bidirectional manipulation of mesopontine cholinergic cell bodies exerted opposing effects on locomotor behavior & reinforcement learning & how these effects were separable via limiting photostimulation to PPN cholinergic terminals in the ventral substantia nigra pars compacta or to the ventral tegmental area, respectively (Xiao et al, Neuron, '16). Genetically encoded tools that can be used to visualize, monitor, and modulate mammalian neurons are revolutionizing neuroscience. However, use of genetic tools in non-transgenic animals is often hindered by the lack of vectors capable of safe, efficient & specific delivery to the desired cellular targets. To begin to address these challenges, we have developed an in vivo Cre-based selection platform (CREATE) for identifying adeno-associated viruses (AAVs) that more efficiently transduce genetically defined cell populations (Deverman et al, Nature Biotechnology, '16). As a first test of the CREATE platform, we selected for viruses that transduced the brain after intravascular delivery and found a novel vector, AAV-PHP.B, that transduces most neuronal types and glia across the brain. We also demonstrate how whole-body tissue clearing can facilitate transduction maps of systemically delivered genes (Yang et al, Cell, '14; Treweek et al, Nature Protocols, '16) and how non-invasive delivery vectors can be used to achieve dense to sparse labeling to enable morphology tracing (unpublished). Since CNS disorders are notoriously challenging due to the restrictive nature of the blood brain barrier, the recombinant vectors engineered to overcome this barrier can enable potential future use of exciting advances in gene editing via the CRISPR-Cas, RNA interference and gene replacement strategies to restore diseased CNS circuits. In addition to control of neuronal activity we need feedback on how exactly the tissue is responding to modulation. We have worked on two related topics: optical voltage sensors and imaging of single molecule RNA in cleared tissue. We used directed evolution of opsins to make them better at reporting action potentials (Flytzanis et al, Nature Communications, '14). Changes in RNA transcripts can also report on activity history of brain circuits. Preserving spatial relationships while accessing the transcriptome of selected cells is a crucial feature for advancing many biological areas, from dev bio to neuroscience. We recently reported on methods for multi-color, multi-RNA, imaging in deep tissues. By using single-molecule hybridization chain reaction (smHCR), PACT tissue hydrogel embedding and clearing and light-sheet microscopy we detected single-molecule mRNAs in ~mm-thick brain tissue samples (Shah et al, Development, '16) and by rRNA labeling we mapped the identity & growth rate of pathogens in clinical samples (DePas et al,'16).
Closs Lecture-Professor Mostafa El-Sayed, Georgia Institute of Technology
Photothermal Therapy of Cancer in Cells and in Different Animals Using Gold Nano-Rods: A Progress Report
Roger Melko, Perimeter Institute
Machine Learning the Many-Body ProblemCondensed matter physics is the study of the collective behavior of infinitely complex assemblies of electrons, nuclei, magnetic moments, atoms or qubits. This complexity is reminiscent of the “curse of dimensionality” commonly encountered in machine learning. Despite this curse, the machine learning community has developed techniques with remarkable abilities to classify, characterize and interpret complex sets of data, such as images and natural language recordings. Here, we show that modern architectures for supervised learning, such as fully-connected and convolutional neural networks, can identify phases and phase transitions in a variety of condensed matter Hamiltonians. Readily programmable through open-source software libraries, neural networks can be trained to detect multiple types of order parameter, as well as highly non-trivial states with no conventional order, directly from raw state configurations sampled with standard Monte Carlo. Further, Monte Carlo configurations can be used to train a stochastic variant of a neural network, called a Restricted Boltzmann Machine (RBM), for use in unsupervised learning applications. We show how RBMs, once trained, can be sampled much like a physical Hamiltonian to produce configurations useful for estimating physical observables. Finally, we explore the representational power of quantum and classical RBMs, their role in deep learning, and its possible relationship to the renormalization group.
John Jewett: University of Arizona
Viral muses to inspire chemistry
Bloblets in your cells: what is their mission?12:00 Eat real food
12:15 digest bloblets
Steve Kivelson, Stanford University
Intertwined Order in Highly Correlated Electron FluidsHost: Paul Wiegmann
Minjung Ryu, PhD, Purdue
Language, Culture, and Learning: Implications for Interdisciplinary Research
Jonathan Simon, University of Chicago
Exploring Landau Levels in Curved SpaceI will present recent work realizing topological phases of photons, both in curved space, and in lattices. The talk will focus on our recent exploration of Landau levels on a conical surface, generated using a non-planar (twisted) optical resonator to induce a synthetic magnetic field for optical photons, and employed to validate the famous Wen-Zee action. I will then discuss recent results demonstrating strong photon-photon interactions mediated by resonator Rydberg-electromagnetically induced transparency (EIT), and techniques we are developing to assemble topological few-body states both photon-by-photon, and through microscopic devices engineered for photon thermalization. I will conclude with our recent observation of time-resolved helical edge dynamics in Z_2 topological circuit lattices, and a T-broken extension in the microwave domain using arrays of 3D cavities and circuit quantum electrodynamics techniques. This work showcases the unique possibilities for Hamiltonian engineering and control in the photonic sector, a provides a taste of upcoming breakthroughs in engineering quantum materials from photons.
The Tuesday JFI Seminar - Elisabeth Guazzelli, Aix Marseille Univ, CNRS, IUSTI, Marseille, France
Rheology of Dense Suspensions of Non-Colloidal ParticlesABSTRACT: Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids (e.g. yield-stress fluids) that we will also address. Host: Heinrich Jaeger, 2-6074 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance contact Brenda Thomas at 2-7156 or by email at email@example.com.
Matthew Lapa, UIUC
Electromagnetic response and anomalies in bosonic symmetry-protected topological phasesSymmetry-protected topological (SPT) phases, gapped phases of matter protected by the symmetry of a group G and possessing interesting boundary states, have been the focus of intense investigation for the past several years. While much is known about the classification and properties of these phases, especially in low dimensions, it is still a challenge to understand the physical properties which characterize a given (interacting) SPT phase in a general dimension. In this talk I will explain how a field-theoretic description of bosonic SPT phases in terms of nonlinear sigma models (NLSMs) can be combined with the theory of gauged Wess-Zumino actions to study the electromagnetic response and anomalies of some bosonic SPT phases with U(1) symmetry in all dimensions. In particular, I will present a calculation of the topological part of the electromagnetic response of bosonic integer quantum Hall (BIQH) states in odd spacetime dimensions and bosonic topological insulator (BTI) states in even spacetime dimensions. In addition, I will argue that the boundary of the BTI state exhibits a global anomaly similar to the parity anomaly of Dirac fermions in odd spacetime dimensions. This argument can be made precise for the boundary theory of the BTI state in two spacetime dimensions. If time allows, I will explain how the connection between gauged Wess-Zumino actions and equivariant cohomology can be used to prove that these results are robust against smooth, symmetry-preserving deformations of the target space of the NLSM used to describe these states.
Gregory T. Tietjen, PhD, Yale
A biophysical approach to engineering vascular targeted nanomedicine
Ribhu Kaul, University of Kentucky
Quantum phase transitions in square lattice SU(N) and SO(N) magnetsI will discuss the phases and phase transitions in some simple SU(N) and SO(N) quantum spin models, studied both using ideas from quantum field theory and with large scale numerical simulations.
James Morken, Boston College
New Strategies in Organic Synthesis Enabled by Catalytic Reactions of Organoboron Reagents
The 1st Tuesday JFI Colloquium - Mark G. Raizen - Department of Physics, University of Texas at Austin
From Maxwell’s Demon to Einstein’s Speed DemonABSTRACT: In this talk, I will describe two historical thought experiments in statistical mechanics and their experimental realization. Maxwell’s Demon was proposed by James Clerk Maxwell in 1871 as a way to reduce the entropy of gas-phase particles by means of an “intelligent creature with deft hands.” We have realized this thought experiment with a self-acting one-way wall for atoms, as originally suggested by Maxwell. This construction has been used to cool atoms, and for efficient isotope separation which will have important medical applications. In 1907, Albert Einstein predicted that Brownian motion should be ballistic on very short time scales, rather than diffusive. Einstein concluded that this instantaneous velocity would be impossible to measure in practice, a prediction that held for over 100 years. We have realized such a ‘speed demon’ by measuring the motion of micrometer beads held in optical tweezers, and have resolved the instantaneous velocity of a Brownian particle in air and in liquid. This system can be used to study the onset of irreversibility, the “arrow of time.”Host(s):Cheng Chin, 2-7192 or via email to firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Wolfgang Ketterle, MIT
New forms of matter with ultracold atoms: synthetic gauge fields and supersolidityHosts: Cheng Chin
Yimon Aye, Cornell
Stay On Target: Deconvoluting Mixed Redox Messages through Precision Redox Targeting
The Tuesday JFI Seminar - James F. Cahoon, Department of Chemistry, University of North Carolina - Chapel Hill
From Nanowires to Nanoplatelets: Designing Semiconductor Morphology so Form Follows FunctionSemiconductors are used in a vast array of modern technologies, including solar cells that convert sunlight into electricity and microprocessors that drive computers. They can be used to direct the flow of energy in devices or to convert energy from one form to another. These functions are enabled by the specific choice of material and composition. Shape, however, is another fundamental characteristic that can be used to encode functionality. Here, I will describe my group’s efforts to usenanometer-scale morphology as a strategy to encode novel photovoltaic, electronic, and optical properties in materials created by bottom-up methods. We chemically synthesize nanostructures, such as metal oxide particles and group IV nanowires, with precise morphology and composition, and we evaluate their physical properties using nanofabrication, spectroscopic, electrochemical, and computational methods. For instance, I will describe a strategy to create silicon nanowires with lithographic-like patterns, enabling applications ranging from photonic crystals to non-volatile memory. In addition, I will outline our efforts to design wide-bandgap photocathode materials for integration in solar fuels devices. The results yield insights into the synthesis, structure-function relationships, and technological applications of designed, bottom-up semiconductor nanomaterials. Host: Bozhi Tian; Contact him at 2-8749 or via email at firstname.lastname@example.org. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at email@example.com.
Wheland Lecture - John P. Maier: University of Basel
Electronic Spectroscopy of C60+ and its Identification in Interstellar Space
The 2nd Tuesday JFI Colloquium - Hui Zhai, Tsinghua University, Institute for Advanced Study
Closs Lecture - Christopher Chang, University of California, Berkeley
Transition Metal Signaling in the Brain and Beyond
Moh El-Naggar, PhD, Depts of Physics and Astronomy, of Biological Sciences, and of Chemistry, University of Southern California
Far, Fast, & Surprising: Extracellular Electron Transport in Microbial Redox ChainsThe stepwise movement of electrons within and between molecules dictates all biological energy conversion strategies, including respiration and photosynthesis. With such a universal role across all domains of life, the fundamentals of ET and its precise impact on bioenergetics have received considerable attention, and the broad mechanisms allowing ET over small length scales in biomolecules are now well appreciated.
In what has become an established pattern, however, our planet’s oldest and most versatile organisms are now challenging our current state of knowledge. With the discovery of bacterial nanowires and multicellular bacterial cables, the length scales of microbial ET observations have jumped by 7 orders of magnitude, from nanometers to centimeters, during the last decade alone! This talk will take stock of where we are and where we are heading as we come to grips with the basic mechanisms and immense implications of microbial long-distance electron transport. We will focus on the biophysical and structural basis of long-distance, fast, extracellular electron transport by metal-reducing bacteria. These remarkable organisms have evolved direct charge transfer mechanisms to solid surfaces outside the cells, allowing them to use abundant minerals as electron acceptors for respiration, instead of oxygen or other soluble oxidants that would normally diffuse inside cells. From an environmental perspective, these microbes are major players in global elemental cycles. From a technological perspective, microbial extracellular electron transport is heavily pursued for interfacing redox reactions to electrodes in multiple renewable energy technologies.
But how can an organism transfer electrons to a surface many cell lengths away? What molecules mediate this transport? And, from a physics standpoint, what are the relevant length, time, and energy scales? We will describe new experimental and computational approaches that revealed how bacteria organize heme networks on outer cell membranes, and along the quasi-one-dimensional filaments known as bacterial nanowires, to facilitate long-range charge transport. Using correlated electron cryo-tomography and in vivo fluorescent microscopy, we are gaining new insight into the localization patterns of multiheme cytochromes along nanowires as well as the morphology and the formation mechanism of these structures. In addition, we will examine the fundamental limits of extracellular electron transport, down to microbial energy acquisition by single cells. These findings are shedding light on one of the earliest forms of respiration on Earth while unraveling surprising biotic-abiotic interactions.