List of Events



MRSEC SEMINARS-EVENTS

MRSEC Seminars are normally held at 4:00 p.m.  in Abelson 229, unless otherwise noted.
Find  Abelson-Bass-Yalem building on the  interactive map.
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Wednesday, May 6, 2015

Time: 9:30 am
Location: Abelson 307, Brandeis University
MRSEC Executive Committee Meeting








Thursday, May 7, 2015

Time: 4 pm
Location: Abelson 229, Brandeis University
MRSEC Seminar
Speaker: Wesley Wong, Children's Hospital Harvard 
Title: Mechanical Force in Nanoscale Biology: From hemostasis to single-molecule centrifugation
Abstract: Mechanical force plays a critical role in regulating many aspects of biological function and structure, particularly at the nanoscale. My research group develops and applies new methods in single-molecule manipulation to understand the force-dependent dynamics of the relevant interactions.  In this talk, I will present three projects that we are pursuing. Firstly, I will discuss our investigations of von Willebrand Factor, a key blood clotting protein. Using optical tweezers, we have shown that hemostatic activity is largely regulated by physiological forces acting on a single-molecule mechanical switch, and we are continuing these studies using single-molecule hydrodynamic traps, computer simulations, and high-throughput single-molecule manipulation. In the second part of the talk, I will present a technique that we have developed for performing massively parallel single-molecule force measurements using centrifugal force. Lastly, I will discuss some nanoscale tools that we are developing, using DNA self-assembly, to characterize biomolecular interactions.
Host: S. Fraden


Thursday, May 14, 2015

Time: 4 pm
Location: Abelson 229, Brandeis University
MRSEC Seminar
Speaker: Jeff Morris, Department of Chemical Engineering at City College of New York
Title: Frictional interactions in viscous suspensions: Abrupt shear thickening and flow-induced jamming
Abstract: Particles suspended in a Newtonian fluid raise the viscosity, and there is generally also a shear rate dependence of the suspension rheology. In particular, pronounced shear thickening is one of the phenomena observed at large solid volume fraction. In recent work [1, 2], we have considered through a simulation study the minimum set of components to reproduce experimentally observed shear thickening behaviors, including the extremely abrupt or “discontinuous shear thickening” (DST). We have found frictional contact forces to be of essential importance. The viscosity divergence at a maximum packing volume fraction has been a well known behavior in suspension rheology, as is reflected in many empirical laws for the viscosity (e.g. Krieger-Dougherty). This divergence can be identified with the jamming transition, as it is known in granular physics. Friction can affect this divergence, and in particular the maximum packing fraction is reduced if particles are frictional. It turns out that shear thickening is a direct consequence of this shift: as the shear rate increases, friction is increasingly mobilized as more contacts form, leading to a transition from a mostly frictionless to a mostly frictional rheology. This result is significant because the emphasis has shifted from lubrication hydrodynamics and detailed microscopic interactions to geometry and steric constraints close to the jamming transition. An overview of the results of the frictional-viscous model of sheared suspensions and its predictions will be given. The same basic mechanism explains shear thickening in both non-Brownian and Brownian (colloidal) suspensions. We will consider the model in comparison with other simulations and with experimental data reported in the literature. Recent work has shown that an S-shaped curve which accesses points that a rate-controlled flow missed can be access when the flow is stress controlled, and this can be driven to jamming conditions.
Host: B. Chakraborty






Thursday, June 18, 2015

Time: 4 pm
Location: Abelson 229, Brandeis University
MRSEC Seminar
Speaker: Jin-Gyu Park, Harvard 
Title: TBA
Abstract: TBA
Host: S. Fraden





Thursday, July 9, 2015

Time: 4 pm
Location: Abelson 229, Brandeis University
MRSEC Seminar
Speaker: Nikta Fakhri, MIT
Title: TBA
Abstract: TBA
Host: S. Fraden


Thursday, July 16, 2015

Time: 4 pm
Location: Abelson 229, Brandeis University
MRSEC Seminar
Speaker: Matthew Webber, MIT
Title: TBA
Abstract: TBA
Host: S. Fraden