November 23, 2014
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Date:23SundayNovember 2014Lecture
TBA
More information Time 11:00Location Sussman Family Building for Environmental SciencesLecturer Gretchen Keppel-Aleks
Atmospheric, Oceanic and Space SciencesOrganizer Department of Earth and Planetary SciencesContact -
Date:23SundayNovember 2014Lecture
Unraveling and eliminating dissipation mechanisms in contacts of polymer-bearing surfaces
More information Time 11:00Location Perlman Chemical Sciences BuildingLecturer Dr. Sissi de Beer
1Jülich Supercomputer Centre, Institute for Advanced Simulation, FZ Jülich, Jülich, Germany 2Materials Science and Technology of Polymers and the Mesa+ Institute, University of Twente, the NetherlandsOrganizer Department of Molecular Chemistry and Materials ScienceContact Details Show full text description of Polymer brushes are well known to lubricate high-pressure co...» Polymer brushes are well known to lubricate high-pressure contacts, while they can sustain high normal loads and maintain low friction at the interface. Depending on the contact-geometry, direction of motion and brush characteristics, different dissipation channels dominate the friction forces. I will discuss the relative importance of the dissipation channels for realistic, rough contacts and show via molecular dynamics simulations and atomic force microscopy measurements that, by using an asymmetric contact of two immiscible polymer brush systems, interdigitation can be eliminated. For such immiscible polymer brush systems, we find that friction upon sliding is a few orders of magnitude lower than for symmetric miscible contacts. Moreover, wear of the coating is strongly reduced.
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Date:23SundayNovember 2014Lecture
Proteasomes as substrate trappers
More information Time 13:00Location Arthur and Rochelle Belfer Building for Biomedical ResearchLecturer Asaf Biran
Yosef Shaul's group, Dept. of Molecular Genetics, WISOrganizer Department of Molecular GeneticsContact -
Date:23SundayNovember 2014Lecture
Collective excitations of hydrodynamically coupled driven colloidal particles
More information Time 14:15Location Edna and K.B. Weissman Building of Physical SciencesLecturer Yael Roichman
Tel Aviv UniversityOrganizer Department of Physics of Complex SystemsContact Abstract Show full text abstract about A single colloidal particle trapped in an optical vortex exp...» A single colloidal particle trapped in an optical vortex experiences two optical forces: a gradient force confining it to motion along a finite width ring of light, and radiation pressure driving it along the perimeter of the ring. As a result, the particle rotates, at constant angular velocity with thermal fluctuations. When a second particle is introduces to the vortex trap the two particles pair due to a pseudo-potential caused by the interplay between hydrodynamic interactions and the curvature of the particles’ trajectory. We study the collective excitations of many colloidal particles driven in an optical vortex trap. We find that even though the system is overdamped, hydrodynamic interactions due to driving give rise to non-decaying excitations with characteristic dispersion relations. The collective excitations of the colloidal ring reflect fluctuations of particle pairs rather than those of single particles.