AIM To examine the in-vitro transport route of tetramethylpyrazine (TMP) across porcine buccal mucosa and to investigate the effects of drug concentration, pH in donor chamber, and 1-octanol/buffer partition coefficient on transbuccal permeation. METHODS In-vitro permeation of TMP through porcine buccal mucosa was studied by using in-line flow through diffusion cells at 37 . The permeability ...

In this study, a time-dependent 2D axisymmetric model of a multilayer hollow fiber composite membrane for gas separation is proposed. In spite of the common multilayer membranes, which a dense layer coated on a porous support layer and subjected into the feed stream, here, the porous support is exposed to the feed gas. In this regard, the governing equations of species transport are developed f...

In copper heap leaching structures, the ore is leached by an acidic solution. After dissolving the ore mineral, the heap is drained off in the acidic solution using a drainage system (consisting of a network of perforated polyethylene pipes and gravelly drainage layers) and is, then, transferred to the leaching plant for copper extraction where the copper is extracted and the remaining solution...

This Communication describes a method to obtain the permeability product (permeability coefficient normalized by vascular dimensions) from time-lapse intensity data for which the introduction of labeled solute into the vasculature does not occur at a sharply defined time. This method has an error of ~10% across a wide range of filling times and noise levels, and is particularly well-suited for ...

The two parameters usually invoked when discussing transport across membranes are the "diffusion permeability coefficient" and the "hydrodynamic permeability coefficient." In this study the magnitude of these two coefficients is established experimentally for collodion membranes of differing porosities. The hydrodynamic permeability is predominant while convergence of the two permeabilities ten...

The permeability of human red cell membrane to 90 different molecules has been measured. These solutes cover a wide spectrum of nonelectrolytes with varying chemical structure, chain length, lipid solubility, chemical reactive group, ability to form hydrogen bonds, and other properties. In general, the present study suggests that the permeability of red cell membrane to a large solute is determ...

One the one hand, capillary permeability to water is a well-defined concept in microvascular physiology, and linearly relates the net convective or diffusive mass fluxes (by unit area) to the differences in pressure or concentration, respectively, that drive them through the vessel wall. On the other hand, the permeability coefficient is a central parameter introduced when modeling diffusible t...

Determination of the permeability coefficient is crucial for the solution of several geotechnical engineering problems such as modeling of underground flow, determination of the hydraulic properties of leachate water in waste disposal areas, calculation of the compressibility, and so on. Constant head permeability test, which is usually performed for the determination of the permeability, is ea...