Transients have utmost importance in the lifetime and performance degradation of PEM fuel cells. Recent studies show that cyclic transients can induce hygro-thermal fatigue. In particular, the amount of water in the membrane varies significantly during transients, and determines the ionic conductivity and the structural properties of the membrane. In this work, we present three-dimensional time...

different solvent extracts of a red algae, hypnea flagelliformis,and two brown algae, cystoseira myrica and sargassum boveanum, collected from the persian gulf coast were subjected to different bioassays including: 1,1-diphenyl-2-picrylhydrazyl (dpph) free radical scavenging assay, antibacterial and antifungal activity by thin layer chromatography (tlc)-bioautography, agar disc diffusion (add) ...

in the present study, a new gas diffusion electrode (gde) (based on pt/nafion membrane) is fabricated. the electrochemical results show that the new gde has the highest electrochemical activity toward the oxygen reduction reaction (orr) among the three electrodes. the sem and xrd findings show that a platinum layer can be attached to nafion membrane closely and firmly with a strong peak corresp...

1. Introduction 1. Introduction Information on mass transport in polycrystalline zeolite membranes is necessary for a theoretical estimation of the membrane performances. Zeolite membranes are usually prepared as thin layer of an assembly of small zeolite crystals including many intercrystalline regions. Thus, the intercrystal region would influence their individual diffusion properties, which ...

This study was performed to design bilayer regioselective floating tablets of atenolol and lovastatin to give immediate release of lovastatin and sustained release of atenolol. Bilayer floating tablets comprised two layers, i.e immediate release and controlled release layers. The immediate release layer comprised sodium starch glycollate as a super disintegrant and the sustained release layer c...

Air sampling based on diffusion of target molecules from the atmospheric gas phase to passive sampling media (PSMs) is currently modeled using the two-film approach. Originally developed to describe chemical exchange between air and water, it assumes a uniform chemical distribution in the bulk phases on either side of the interfacial films. Although such an assumption may be satisfied when mode...

A new fabrication technique is employed to convert a metallic foil into a porous structure with an array of micron size pores. The motivation stems from the need to develop a more efficient and controllable gas diffusion medium for fuel cell applications. The influence of mask shape, mask width and etching time was investigated experimentally. A correlation to predict trench width with etching ...