Permeation tubes are convenient analyte sources for generating standard gas mixtures (containing, in particular, volatile organic compounds) used in the calibration of analytical instruments. For small permeation rates, corresponding to trace levels of analytes, the calibration of permeation tubes is time-consuming. The use of thermogravimetry as a means to measure rapidly the weight loss at co...

objective (s): transdermal preparations for testosterone are becoming popular because of their unique advantages such as avoidance of first-pass effect, convenience, improved bioavailability, and reduction of systemic side effects. a novel testosterone transdermal delivery system (tdds) was developed using a palm oil base called hamintm (a commercial product) and tested using in vitro and in vi...

in this work, a more accurate prediction of liquid evaporation flux has been achieved. the statistical rate theory approach, which is recently introduced by ward and fang and exact estimation of vapor pressure in the layer adjacent to the liquid–vapor interface have  been used for prediction of this flux. firstly, the existence of an equilibrium layer adjacent to the liquid-vapor interface is c...

By using molecular dynamics simulation, the dynamic behaviors of particle permeation through a four-helix-bundle model channel are studied. The interior cavity of the four-helix-bundle provides the "routes" for particle permeation. The main structural properties of the model channel are similar to those that appear in natural four-helix-bundle proteins. It is found that the interior structure o...

A slurry process was employed to develop advanced environmental barrier coatings (EBCs) for SiC based composites. Yb2Si2O7 and mullite (3 Al2O3?2 SiO2) were chosen as the base materials bond coat enable temperatures beyond melting point of current silicon (1414 °C). Various sintering aids, such mullite, Yb2Si2O7, Al2O3, enabled at 1500 °C – 1550 °C. used top provide water vapor recession resist...

The difficulty in characterizing ion conduction through membrane channels at the level of individual permeation events has made it challenging to elucidate the mechanistic principles underpinning this fundamental physiological process. Using long, all-atom simulations enabled by special-purpose hardware, we studied K(+) permeation across the KV1.2/2.1 voltage-gated potassium channel. At experim...

Preformulation studies on transdermal dosage forms involve liberal use of animal skin for assessing the permeation characteristics of drugs, influence of permeation enhancers, optimizing the formulation variables etc. The restricted availability of animal skin due to concerns regarding prevention of cruelty to animals has generated considerable interest in developing polymeric films for use as ...