Annual reports from years 1, 2, 3, 4,
5, 6, 7, 8, 9, 10
Our plan for the second year of this project was to double the pace of exchange visits compared to the first year. We have achieved this goal, with four Chilean visitors and five University of Chicago exchange students, together with a senior Chilean visitor.
2004 initial Chicago student exchange
Our Chicago-to-Chile program began with a single student, a graduating senior named Jordan Weil. Working with Prof. Enrique Cerda and with Raul Labbe of the University of Santiago, he developed a way to see gravity-driven draping of a rotating thin sheet without the perturbing effects of air. This work is being prepared for publication. The images show three examples with the draped structure highlighted using a laser beam directed onto the sample.
Melo visit
In November, 2004 the project hosted a 2-day visit from Professor Francisco Melo of the University of Santiago, one of our partner institutions. Melo presented his group's impressive work on granular flow, crumpling and wrinkling in two lectures.
2005 Chilean students
In January we received four Chilean students. They each spent 8 to 10 weeks working in research groups in the department. Last year's Chilean exchange students helped in the recuiting of these students, as did Enrique Cerda, our faculty partner at the University of Santiago.
Cristobal Ariata, a masters student in physics at the University of Chile worked in Ka Yee Lee's group under postdoc Eva Chi. Cristobal studied the insertion of a tri-block copolymer, P188, into lipid monolayers. P188 has been used clinically as a synthetic surfactant that seals cell membranes damaged by disease or trama. Cristobal examined the effect of gangliosides (another component of cell membranes besides phospholipids) on P188 insertion into lipid monolayers. he did a comparative study of P188 insertion as a funtion of increasing ganglioside concentration in monolayer. Cristobal presented his results to the group before he left. Dr. Chi was very pleased with the data he collected. Prof. Lee is hopeful that his results will be incorporated into a publication in the future. Cristobal returned to his masters-degree studies in March.
Loreto Barcos, an undergraduate physics student at the University of Santiago worked in the laboratory of Prof. Sidney Nagel. Her project was a followup to a recent discovery of this research group: the splashing of a liquid drop hitting a surface depends on the presence of an atmosphere. Loreto worked with PhD student Lei Xu, using high-speed video to investigate the effect of environmental conditions needed for the splashing instability to occur. Lei told me that she learned well and began a useful study on the effect of surface roughness, including the use of atomic force microscopy to characterize the roughness. Lei has continued this study, which is intended for publication. Loreto's findings are well summarized in her final report.
Maria-Luisa Cordero is a masters student at the University of Chile. Her supervisor was Dr. Peter Eng, a collaborator of Prof. Heinrich Jaeger at Argonne National Lab. Working with Chicago PhD students Eric Corwin and John Royer, Maria participated in a striking discovery about sand jets. A sand jet is formed when a heavy projectile penetrates into loose sand. The mechanism for formation of these dramatic jets has attracted great recent interest. Using fast x-ray radiography at Argonne's Advanced Photon Source, the group discovered previously unsuspected internal in the jets: the jets are hollow. Maria's role was to measure the different images and assemble them into a montage in order to obtain a comprehensive picture of the phenomenon in space and time. This work has been submitted for publication to either Science or Nature. Maria has written a clear final report on her work.
Victor Romero is an advanced undergraduate student at the University of Santiago. He worked with postdoc Ward Lopes in Prof. Jaeger's group. He used spin-coating, vapor deposition and atomic force microscopy to investigate the dewetting patterns of gold layers on patterned diblock polymer surfaces. He investigated several processing parameters in order to influence the droplet morphology in favor of a continuous wire morphology seen in silver. His work ruled out an extensive parameter space as a condition for the wire-forming morphology. His careful report is expected to be very valuable in the group's ongoing work on controlling these growth morphologies.
2005 Chicago students
The number of Chicago students working in Chile this summer increased dramatically over last year. This increase was aided by an active program of information and recruiting. Prof. Melo's visit in November included a meeting with prospective students. We invited last year's Chicago exchange student Jordan Weil to return and give a talk about his positive experience in Chile. In March and April several Chicago undergraduates expressed an interest in going to Chile. Our Chilean partners organized a web page with a menu of prospective projects. We introduced each Chicago student to his/her prospective supervisor in a remote video meeting. The five students are currently in Chile doing their projects. These are described individually below.
Colin McFaul, a graduating physics major, is working with Prof. Nicolas Mujica. His project concerns the experimental study of acoustic interactions in two-phase media. He is studying the collective behavior of solid particles or gas bubbles immersed in liquid, which will be forced by acoustic waves. The sound is intense enough that the radiation pressure is not negligible. He will infer the interactions induced between the particles by the sound.
Matthew O"Meara, an entering third-year physics major is working with Prof. Mujica on oscillons. These are localized vibration modes of a liquid surface excited by strong but uniform shaking of the liquid. The aim of the project is to study theoretically and experimentally the complex dynamics observed by these particle-type solutions, like bouncing, rotation, translation, and spatio-temporal chaos.
Joe Bolte is a graduating senior. He is working with Prof. Felipe Barra at the University of Chile on a recent prediction about thermodynamic fluctuations. This prediction, called the Jarzinski theorem, predicts transient energy flows between a system and its environment. Bolte is investigating how these flows occur in the context of well-known numerical models.
Nathan Krapf is a graduating physics major. He is working with a postdoc named Valerie Vidal in Francisco Melo's group. They are studying the mechanical basis for an intriguing geophysical effect. Bursting bubbles of lava may emit resonant sounds as they burst. Melo and Vidal have devised a small-scale model which reproduces this phenomenon using viscoelastic liquids. Nathan is studying the viscoelastic conditions needed for the effect to occur.
Carolyn Brown is an entering third-year physics major. She is working with Prof. Sergio Rica at the University of Chile. Her work concerns the nonlinear interaction of vibrational modes in a stretched wire experimentally and numerically. These interactions are important in determining the sonority of musical instruments. They will focus on the flux of energy from the dominant vibrational mode to others via eg nonzero bending stiffness in the wire.
