A new covalently bound ceramide from human stratum corneum -omega-hydroxyacylphytosphingosine

The outermost layer of the skin, the stratum corneum, consists of non-viable keratin-filled cells, or corneocytes, embedded in a matrix of lipids. The boundary of the cells consists of cross-linked proteins with covalently bound lipids on the outer surface. The spaces between cells are filled with a mixture of ceramides, cholesterol and fatty acids. The stratum corneum provides a protective barrier against water loss through the skin and limits the penetration of potentially harmful substances from the environment. Among the covalently bound lipids on the corneocyte surface are omega-hydroxyacylsphingosine and omega-hydroxyacyl-6-hydroxysphingosine. The previously suspected presence of omega-hydroxyacylphytosphingosine is confirmed in this report through its specific isolation and characterization based on chromatographic behaviour and proton magnetic resonance spectral data.     

Hydroxylamine as a Source for Nitric Oxide in Metal‐Free 2,2,6,6‐ Tetramethylpiperidine N‐Oxyl Radical (TEMPO) Catalyzed Aerobic Oxidation of Alcohols

The communication reports on the metal‐free 2,2,6,6‐tetramethylpiperidine N‐oxyl radical (TEMPO) catalyzed aerobic oxidation of various alcohols to aldehydes and ketones. A novel catalyst system that uses 1–4 mol% of TEMPO in combination with 4–6 mol% of aqueous hydroxylamine is introduced. No other additives are necessary and corrosive by‐products are not formed during oxidation. Nitric oxide which is important for the catalytic cycle is generated in situ by reaction of the hydroxylamine with TEMPO. A catalytic cycle for the overall oxidation process is suggested.     

Wire rod coating process of gas diffusion layers fabrication for proton exchange membrane fuel cells

Gas diffusion layers (GDLs) were fabricated using non-woven carbon paper as a macro-porous layer substrate developed by Hollingsworth & Vose Company. A commercially viable coating process was developed using wire rod for coating micro-porous layer by a single pass. The thickness as well as carbon loading in the micro-porous layer was controlled by selecting appropriate wire thickness of the wire rod. Slurry compositions with solid loading as high as 10 wt.% using nano-chain and nano-fiber type carbons were developed using dispersion agents to provide cohesive and homogenous micro-porous layer without any mud-cracking. The surface morphology, wetting characteristics and pore size distribution of the wire rod coated GDLs were examined using FESEM, Goniometer and Hg porosimetry, respectively. The GDLs were evaluated in single cell PEMFC under various operating conditions (temperature and RH) using hydrogen and air as reactants. It was observed that the wire rod coated micro-porous layer with 10 wt.% nano-fibrous carbon based GDLs showed the highest fuel cell performance at 85 °C using H₂ and air at 50% RH, compared to all other compositions.