Western Illinois University: Macomb Campus
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Department of Physics
Physics Colloquium February 9
Jan 25, 2012
Speaker: Dr. Haskell Taub
Date: February 9, 2012 (Thursday)
Time: 4 PM
Room: 205 Currens Hall
Study of water diffusion on single-supported bilayer lipid membranes by neutron scattering
Neutron scattering and molecular dynamics simulations have been used to elucidate the diffusion of water molecules associated with single bilayer lipid membranes supported on a silicon substrate. This system serves as a physicist's model of biological membranes that surround all living cells. Knowledge of the water motion is important for understanding the membrane function. We first characterize the structure of our supported membranes as a function of temperature using Atomic Force Microscopy. We then perform high-energy-resolution quasielastic neutron scattering experiments at the NIST Center for Neutron Research and the Spallation Neutron Source at Oak Ridge National Laboratory on similarly prepared samples. By varying both membrane temperature and level of hydration, we find evidence of three different types of water motion: bulk-like, confined, and bound. The motion of bulk-like and confined water molecules is fast compared to those bound to the head groups of the lipid molecules, which move on the same nanosecond time scale as the molecular center of mass.
About the speaker:
Dr. Taub is currently a member of the Department of Physics and Astronomy at the University of Missouri, Columbia. He received his B.S. from Stanford, his Ph. D. from Cornell and did postdoc work at New York University. While working at Brookhaven National Laboratory, Dr. Taub was introduced to neutron scattering research and has since been conducting experiments to study the structure, phase transitions, and dynamics of adsorbed films. Currently, he is directing a large NSF-funded project aimed at training the next generation of scientists and engineers in neutron scattering research.