Levich Institute Seminar Announcement, 10/25/2011
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Jeff Urbach
Department of Physics
"Mechanics of Biopolymer Networks"
Networks of relatively stiff filaments are responsible for many of the mechanical properties of cells and tissues, as well as many important synthetic materials. Unlike conventional gels, these materials are not well described by existing continuum theories based on the physics of flexible polymers. The mechanics of many biopolymer networks is strikingly nonlinear – the gels stiffen when subjected to applied shear. I will describe theoretical models for strain stiffening, and present recent experimental results showing that the nonlinear behavior is strongly dependent on the gel thickness, even at sizes that would normally be considered macroscopic. I will also present results from direct imaging of network rearrangements that provide some evidence for the mechanisms of strain stiffening. Finally, I will discuss the interaction between mechanical properties and cell motility, specifically in the context of axons extending from nerve cells.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
Prof. Urbach completed his B.A. in Physics at Amherst College (1985), his Ph.D. at Stanford University (1993), and a Postdoctoral Fellowship at the University of Texas at Austin (1993-1996). He joined the Physics Department at Georgetown University as an Assistant Professor in 1996 and was promoted to Professor of Physics in 2006. He served as chair of the Physics Department in 2001-02 and again from 2003-07, and is currently co-Director of the Program on Science in the Public Interest. In 2009-10, he served as a AAAS Science and Technology Policy Fellow at the Department of Energy.
RECENT RESEARCH INTERESTS:
Soft condensed matter physics, biophysics