4,218 research outputs found
Bulk and wetting phenomena in a colloidal mixture of hard spheres and platelets
Density functional theory is used to study binary colloidal fluids consisting
of hard spheres and thin platelets in their bulk and near a planar hard wall.
This system exhibits liquid-liquid coexistence of a phase that is rich in
spheres (poor in platelets) and a phase that is poor in spheres (rich in
platelets). For the mixture near a planar hard wall, we find that the phase
rich in spheres wets the wall completely upon approaching the liquid demixing
binodal from the sphere-poor phase, provided the concentration of the platelets
is smaller than a threshold value which marks a first-order wetting transition
at coexistence. No layering transitions are found in contrast to recent studies
on binary mixtures of spheres and non-adsorbing polymers or thin hard rods.Comment: 6 pages, 4 figure
Role of Metastable States in Phase Ordering Dynamics
We show that the rate of separation of two phases of different densities
(e.g. gas and solid) can be radically altered by the presence of a metastable
intermediate phase (e.g. liquid). Within a Cahn-Hilliard theory we study the
growth in one dimension of a solid droplet from a supersaturated gas. A moving
interface between solid and gas phases (say) can, for sufficient (transient)
supersaturation, unbind into two interfaces separated by a slab of metastable
liquid phase. We investigate the criteria for unbinding, and show that it may
strongly impede the growth of the solid phase.Comment: 4 pages, Latex, Revtex, epsf. Updated two reference
Radio Astronomy
Contains reports on one research project.National Aeronautics and Space Administration (Contract NAS5-21980
A cluster mode-coupling approach to weak gelation in attractive colloids
Mode-coupling theory (MCT) predicts arrest of colloids in terms of their
volume fraction, and the range and depth of the interparticle attraction. We
discuss how effective values of these parameters evolve under cluster
aggregation. We argue that weak gelation in colloids can be idealized as a
two-stage ergodicity breaking: first at short scales (approximated by the bare
MCT) and then at larger scales (governed by MCT applied to clusters). The
competition between arrest and phase separation is considered in relation to
recent experiments. We predict a long-lived `semi-ergodic' phase of mobile
clusters, showing logarithmic relaxation close to the gel line.Comment: 4 pages, 3 figure
Radio Astronomy
Contains reports on two research projecst.California Institute of Technology Contract 952568Sloan Fund for Basic Research (M.I. T. Grant 241
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