Biomedical subjects

Ji-Ming Jiang

Publications and source records attributed to Ji-Ming Jiang.

3 recordsLinked to original sources

PubMed2005

Distribution of colloidal particles in a spherical cavity.

The spatial distribution of colloidal particles in a confined space is frequently a key issue to many phenomena of practical significance. This problem is investigated by considering the distribution of colloidal particles in a spherical cavity under the conditions of relatively large cavities, low cavity and colloidal particles potentials, and low monovalent electrolyte and colloidal concentrations. The analytical expression for the particle-cavity pair interaction energy is derived under various surface conditions. The results obtained are used to evaluate the direct correlation functions in the hypernetted chain approximation employed for the resolution of an Ornstein-Zernike equation. For a fixed particle number concentration at the center of a cavity, we make the following conclusions: (i) the spatial distribution of particles increases in an oscillatory manner with the distance away from the cavity surface, (ii) increasing the particle-cavity pair interaction energy has the effect of reducing the free space of particles inside a cavity, and (iii) the greater the pair interaction energy between two particles, the higher the average concentration of particles.

Journal Article↗

PubMed2005

Derivation of analytical expressions for the electrical potential distribution in lipid structures.

The electrical potential inside a lipid structure, which is described by a modified Poisson-Boltzmann equation in the literature (Borukhov et al. Electrochim. Acta 2000, 46, 221), is solved, taking into account the effects of ionic sizes. Here, a micelle comprises an ionic surfactant layer and an aqueous core; the dissociation of the former yields a charged surface. The governing equation, which was solved numerically in a previous study for spherical geometry (Hsu et al. J. Phys. Chem. B 2003, 107, 14429), is solved analytically in this study for planar, cylindrical, and spherical geometries. The analytical results obtained are readily applicable for the evaluation of the spatial distributions of counterions inside a lipid structure. We show that if the linear size of a reverse micelle is fixed, the degree of dissociation of the surfactant layer follows the order planar > cylindrical > spherical.

Computer Simulation↗

PubMed2004

Electrical potential in a cylindrical double layer: a functional theory approach.

Employing an iterative method in functional theory, the electrical potential distribution for the case of a cylindrical surface is solved. Although the analytical result derived is of an iterative nature, the second-order solution is found to be sufficiently accurate under conditions of practical significance. For the case of constant surface potential, the radius and the surface potential of a cylindrical surface can be estimated based on the extreme of the electrical potential distribution. The effects of the key parameters, including the number and the valence of the ions on a surface, the length of a particle, the relative permittivity of the liquid phase, the temperature, and the concentration of electrolyte on the surface potential, are examined. The general behavior of these effects is similar to that for a spherical surface, except that the surface potential of a cylindrical surface is independent of the electrolyte concentration. The present approach is also applicable to the case where a cylindrical surface remains at a constant charge density.

Journal Article↗