Simultaneous measurements of viscoelasticity and electrical conductivity are performed to study the dynamic characteristics of structures formed in a highly concentrated electrorheological suspension under a dc electric field of 1.8 kV/mm. Small amplitude oscillatory shear measurements reveal that there is no direct correlationbetween theelasticmodulusand theelectrical conductivity of the suspe...

A dynamical phase transition from reversible to irreversible behavior occurs when particle suspensions are subjected to uniform oscillatory shear, even in the Stokes flow limit. We consider a more general situation with nonuniform strain (e.g., oscillatory channel flow), which is observed to exhibit markedly different dynamics. The onset of irreversibility is delayed, and occurs simultaneously ...

In animal and in-vitro models, increased oscillatory shear stress characterized by increased retrograde shear-rate (SR) is associated with acutely decreased endothelial cell function. While previous research suggests a possible detrimental role of elevated retrograde SR on endothelial-function in the brachial artery in humans, little research has been conducted examining arteries in the leg. Ex...

Ferrofluids are colloidal suspensions of magnetic nanoparticles that exhibit normal liquid behavior in the absence of magnetic fields but respond to imposed magnetic fields by changing their viscosity without loss of fluidity. The response of ferrofluids to constant shear and magnetic fields has received a lot of attention, but the response of ferrofluids to oscillatory shear remains largely un...

Hard sphere colloidal particles are a basic model system for general research into phase behavior, ordering and out-equilibrium glass transitions. Experimentally it has been shown that oscillatory shearing of a monodisperse hard sphere glass, produces two different crystal orientations; a Face Centered Cubic (FCC) crystal with the close packed direction parallel to shear at high strains and an ...

We study a simple model of shear banding in which the flow-induced phase is destabilized by coupling between flow and microstructure (wormlike micellar length). By varying the strength of instability and the applied shear rate, we find a rich variety of oscillatory and chaotic shear banded flows. At low shear and weak instability, the induced phase pulsates next to one wall of the flow cell. Fo...

Nonlinear mechanical properties play an important role in numerous biological functions, for instance the locomotion strategy used by terrestrial gastropods. We discuss the progress made toward bioinspired snail-like locomotion and the pursuit of an engineered fluid that imitates the nonlinear viscoelastic properties of native gastropod pedal mucus. The rheological behavior of native pedal mucu...

Glutathione (GSH) is the major source of intracellular sulfhydryl groups. Oxidized GSH (GSSG) can be recycled to GSH by the GSH reductase or exported from the cell. The mechanism by which GSSG is exported and the consequence of its export from endothelial cells has not been defined previously. We found that human endothelial cells express the multidrug resistance protein-1 (MRP1) and use this a...