Porous crystals in charged sphere suspensions by aggregate-driven phase separation.

The kinetics of phase transition processes often governs the resulting material microstructure. Using optical microscopy, we here investigate the formation and stabilization of a porous crystalline microstructure forming in low-salt suspensions of charged colloidal spheres containing aggregates comprising some 5-10 of these colloids. We observe the transformation of an initially crystalline colloidal solid with homogeneously incorporated aggregates to individual, compositionally refined crystallites of perforated morphology coexisting with an aggregate-enriched fluid phase filling the holes and separating individual crystallites.

Microstructural diversity, nucleation paths, and phase behavior in binary mixtures of charged colloidal spheres.

We study low-salt, binary aqueous suspensions of charged colloidal spheres of size ratio Γ = 0.57, number densities below the eutectic number density n, and number fractions of p = 1.00-0.

Long-term use of gabapentin for musculoskeletal disease and trauma in three cats.

Gabapentin has been widely used in human medicine to control acute and chronic pain. Although the exact mechanism of action has yet to be determined, its use in veterinary medicine is increasing. The clinical use of gabapentin for analgesia in cats has been reported in review articles and one case report.

Melting and freezing lines for a mixture of charged colloidal spheres with spindle-type phase diagram.

We have measured the phase behavior of a binary mixture of like-charged colloidal spheres with a size ratio of Γ=0.9 and a charge ratio of Λ=0.96 as a function of particle number density n and composition p.

Communications: Complete description of re-entrant phase behavior in a charge variable colloidal model system.

In titration experiments with NaOH, we have determined the full phase diagram of charged colloidal spheres in dependence on the particle density n, the particle effective charge Z(eff) and the concentration of screening electrolyte c using microscopy, light and ultrasmall angle x-ray scattering (USAXS). For sufficiently large n, the system crystallizes upon increasing Z(eff) at constant c and melts upon increasing c at only slightly altered Z(eff). In contrast to earlier work, equilibrium phase boundaries are consistent with a universal melting line prediction from computer simulation, if the elasticity effective charge is used.

Phase behaviour of deionized binary mixtures of charged colloidal spheres.

We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios Γ and charge ratios Λ are varied over a wide range. Unlike the case for hard spheres, the long-ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorphous solids to particle concentrations considerably larger than the freezing concentration.

Phase behavior of a de-ionized binary mixture of charged spheres in the presence of gravity.

We report on the phase behavior of an aqueous binary charged sphere suspension under exhaustively de-ionized conditions as a function of number fraction of small particles p and total number density n. The mixture of size ratio Gamma=0.557 displays a complex phase diagram.