The pressure of suspensions of self-propelled objects is studied theoretically and by simulation of spherical active Brownian particles (ABPs). We show that for certain geometries, the mechanical pressure as force/area of confined systems can be equally expressed by bulk properties, which implies the existence of a nonequilibrium equation of state. Exploiting the virial theorem, we derive expre...

The problem of calculating the electric polarizability tensor alpha(e) of objects of arbitrary shape has been reformulated in terms of path integration and implemented computationally. The method simultaneously yields the electrostatic capacity C and the equilibrium charge density. These functionals of particle shape are important in many materials science applications, including the conductivi...

Adding a nonadsorbing polymer to passive colloids induces an attraction between the particles via the "depletion" mechanism. High enough polymer concentrations lead to phase separation. We combine experiments, theory, and simulations to demonstrate that using active colloids (such as motile bacteria) dramatically changes the physics of such mixtures. First, significantly stronger interparticle ...

Concentrated particulate suspensions under vibrations can support stable, localized, vertically oriented free surfaces. The most robust of these structures are persistent holes: deep and stable depressions of the interface. Using a reduced model of the hydrodynamics we show that a rheology with hysteresis can lead to motion opposite to the time-averaged applied force. Moreover, we show experime...

The rheological properties of suspensions of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) microgels are investigated in the swollen and collapsed states using oscillatory and long-time creep measurements. In the swollen state with repulsive interparticle interaction, the zero shear viscosity and quasi-plateau modulus are solely governed by the effective volume fraction (φeff) and are ...

We report on rheometry measurements to characterize the critical behavior in two model shear thickening suspensions: cornstarch in water and glass spheres in oil. The slope of the shear thickening part of the viscosity curve is found to increase dramatically with packing fraction and diverge at a critical packing fraction phi(c). The magnitude of the viscosity and the yield stress are also foun...

The Journal of Physical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Photoredox reactions at semiconductor particles incorporated into clays. Cadmium sulfide and zinc sulfide + cadmium sulfide mixtures in colloidal montmorillonite suspensions O. Enea, and Allen J. Bard J. Phys. Chem., 1986, 90 (2), 301-306 • DOI: 10.1021/j100274a020 D...

The viscosity of a suspension of swimming bacteria is investigated analytically and numerically. We propose a simple model that allows for efficient computation for a large number of bacteria. Our calculations show that long-range hydrodynamic interactions, intrinsic to self-locomoting objects in a viscous fluid, result in a dramatic reduction of the effective viscosity. In agreement with exper...

The Journal of Physical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Photochemistry of tris(2,2'-bipyridyl)(ruthenium(II) in colloidal clay suspensions Pushpito K. Ghosh, and Allen J. Bard J. Phys. Chem., 1984, 88 (23), 5519-5526• DOI: 10.1021/j150667a012 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on Feb...

The shear rheology of dense colloidal and granular suspensions is strongly nonlinear, as these materials exhibit shear-thinning and shear-thickening, depending on multiple physical parameters. We numerically study the rheology of a simple model of soft repulsive particles at large densities, and show that nonlinear flow curves reminiscent of experiments on real suspensions can be obtained. By u...