Preparation of ethylcellulose/polystyrene composite microcapsules of two-phase structure and permeability of the microcapsule membranes towards phenobarbital

Further studies on membrane transport with time delay

A theory of cell membrane transport with a time delay which predicts under certain conditions overshoot or oscillatory permeation (Ohshima and Kondo, Biophys. Chem. 33 (1989) 303), is extended with the introduction of a parameter expressing a fraction of solutes inside the cell interior that suffer time delay. It is found that criterion for oscillation depends strongly on this parameter. Results will also be presented for the case of an exponential-type distribution of the delay time.

Membrane transport equations with a time delay. A model for overshoot and oscillatory permeation

Membrane transport equations with a time delay are proposed and their analytic solution is derived. This solution is found to exhibit under certain conditions overshoot and oscillatory permeation.

Periodic characteristics of composite membrane permeability

The permeability of the microcapsule membrane is one of the important characteristics in evaluating the function of microcapsule. In order to specify the mechanism of the oscillatory permeation of electrolytes through composite membranes, we derived a solution to the equation for the transport phenomena through the membrane composed of different patches arranged in a parallel array of two different elements. This solution was applied to the experimental data for the transport process of phenobarbital through ethylcellulose/polystyrene microcapsule which has a patch work-like two-phase structure and exhibits an oscillatory permeation. The values of dispersivities for mass and ionic diffusion flows deduced from the experimental data of Ohara et al. (1985) are 4.0 x 10(-4) and 6.0 x 10(-13) cm2/sec respectively for the membrane thickness of 3.5 x 10(-4) cm.