Density functional theory studies of Cu-zeolite de-NOx catalysts

Summary Recent progress in the modelling of exchanged Cu sites and their interactions with small molecules, based on DFT cluster calculations, is briefly reviewed.     

0.27-dB/km attenuation achieved by MSP preform process [opticalfibers]

Mechanically shaped preforms (MSP) have been demonstrated to combine economic non-CVD (chemical vapor deposition) processing and low loss, with a published value of 0.63 dB/km and a size of 30 fkm/preform. Improved processing is proposed which results in a minimum loss of 0.27 dB/km at 1550 nm. Preforms capable of yielding 150 fkm have been produced. Reboiling during preform stretching and fiber pulling is identified as the last remaining problem of the process     

Synthesis and degradation of hyaluronate by synovia from patients with rheumatoid arthritis

OBJECTIVE: Hyaluronate degradation was analyzed in cultures of healthy tissue and tissue obtained from patients with rheumatoid arthritis. METHODS: Arthritic and healthy synovial tissues were incubated in culture with [3H]glucosamine. Labelled hyaluronate was extracted and its size determined by gel filtration. The production of low molecular weight hyaluronate was analyzed by pulse-chase experiments. Radical production was measured by a cytochrome C reduction assay. RESULTS: Healthy tissues and some arthritic tissues that did not contain significant amounts of granulocytes produced high molecular weight hyaluronate. In contrast, arthritic tissue infiltrated with granulocytes released low molecular weight hyaluronate. Pulse-chase experiments suggested that hyaluronate was degraded in these arthritic tissues. Exogenous hyaluronate was degraded only by intact tissue, but not by cells in culture obtained from synovial membranes of synovial fluids. Hyaluronate degradation was accompanied by massive oxygen radical production. Radical scavengers protected hyaluronate from degradation in synovial tissue. Some protection was achieved by superoxide and catalase or by methionine and complete protection by the iron chelators diethyltriaminepentacetic acid or deferoxamine mesylate. CONCLUSION: Degradation of hyaluronate in arthritic synovial tissue may be inhibited in tissue culture by radical scavengers.     

The effects of L-deprenyl treatment, alone and combined with GM1 ganglioside, on striatal dopamine content and substantia nigra pars compacta neurons

A novel amperometric HPLC detection method for the cyanobacterial (blue-green algal) peptide toxins microcystin-LR, -YR and -RR was developed. Purified microcystins and cyanobacterial extracts were chromatographed using an internal surface reversed-phase column with acetate- and phosphate-based mobile phase systems. Electrochemical oxidation reactions at 1.20 V vs. Ag/AgCl (glassy carbon working electrode) were show to originate in arginine and tyrosine residues of microcystins.