2014 Recent R.M.N. and quasi-elastic neutron scattering experiments on smectics A have given comparable values for the self-diffusion coefficients D~ (diffusion normal to the layers) and D~, in spite of the possible occurence of a permeation process which would lead to much lower values for D ~. It is shown that there is no permeation in a self-diffusion experiment, and therefore that the Einst...

This paper considers permeation through microporous or nanoporous inorganic membranes under the influence of an applied pressure gradient. In general membrane permeation may be considered as a diffusive process, driven by the gradient of chemical potential (which depends on both composition and pressure). The relative importance of these two factors varies greatly for different types of system....

The aim of this study was to evaluate the transdermal permeation of alniditan by electroporation and to compare with iontophoretic delivery. The influence of the electrical parameters of electroporation was investigated in vitro using a factorial design study. The transdermal flux of alniditan was enhanced by two orders of magnitude by application of high voltage electrical pulses. The electric...

A lightweight, compact gas standards generator for permeation tubes is described. This system provides reliable temperature control during periods of intermittent power and is ideal for field measurements. A eutectic alloy with a high heat of fusion is used as a phase change material. This thermal source allows the system to maintain a constant permeation tube temperature of 46.6 °C for over 5 ...

In the past decade, many strategies have been developed to enhance oral drug delivery. Different techniques were investigated, amongst those the use of permeation enhancers such surfactants and biodegradable polymers were studied more extensively. Chitosan and its derivatives have been studied as permeation enhancer. The aim of the current study was to develop a nanoparticulate system based on ...

Microporous hydroxy-sodalite zeolite membranes with different morphologies were synthesized via secondary growth technique with vacuum seeding on tubular α-Al2O3 supports at two different synthesis conditions (i.e. two different routes). Microstructures of the synthesized membranes were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM) and si...

The present study prepares alkali lignin (AL) via acidification of black liquor, obtained from a pulp and paper factory. The average molecular weight of AL (equal to 2,530 g/mol) has been determined with gel permeation chromatography. AL has been modified by ethylene glycol, while lignin nanoparticles (LN) has been prepared through acid precipitation technology, their size being assessed by mea...

We hypothesized that modulation of the effective charge density of the endothelial surface layer (ESL) results in altered arterial barrier properties to transport of anionic solutes. Rat mesenteric small arteries (diameter approximately 190 microm) were isolated, cannulated, perfused, and superfused with MOPS-buffered physiological salt solutions. MOPS-solutions were of normal ionic strength (1...

We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (P...

The ion permeation process, driven by a membrane potential through an outer membrane protein, OmpF porin of Escherichia coli, was simulated by molecular dynamics. A Na+ ion, initially placed in the solvent region at the outer side of the porin channel, moved along the electric field passing through the porin channel in a 1.3 nsec simulation; the permeation rate was consistent with the experimen...