In this ‘feasibility study’ the influence of roasting on the sulfur speciation in Mexican coffee beans was investigated by sulfur K-XANES spectroscopy. Spectra of green and slightly roasted beans could be fitted to a linear combination of ‘standard’ reference spectra for biological samples, whereas longer roasting obviously involves formation of additional sulfur compounds in considerable amounts.

要約:システインパースルフィドなどの活性イオウ分 子種は,チオール基に過剰にイオウ原子が付加したポ リスルフィド構造を有する化合物であり,通常のチ オール化合物に比べ,高い求核性と抗酸化活性を有し ている.近年,ポリスルフィドは,システインやグル タチオンなどの低分子チオール化合物だけでなく,タ ンパク質中のシステイン残基にも多く存在し,細胞内 の様々なタンパク質がポリスルフィド化されているこ とが明らかになってきた.タンパク質中のシステイン チオール基は,活性酸素や親電子物質によりもたらさ れる酸化ストレスのセンサーとして重要な役割を果た していることが知られており,ポリスルフィド化はタ ンパク質機能制御を介したレドックスシグナル伝達メ カニズムとして,細胞機能制御に関与することが予想 される.しかしながら,複雑な化学特性を有するポリ スルフィドは検出が難しいことから,生体内におけ...

The disulfates of unconjugated, and glycineand taurine-conjugated bile acids have been synthesized. Cholic acid derivatives appropriately protected were sulfated with sulfur trioxidetriethylamine complex in pyridine in the usual manner. Subsequent hydrolysis and/or sodium borohydride reduction provided the desired disulfates of cholates in satisfactory yields. Dihydroxy: lated bile acid disulfa...

i Work was performed to determine the possible effectiveness of sulfur-containing fuel additives as contrail suppressents. Such suppression would require production of significant levels of sulfur trioxide, a known suppressent, in the exhaust. A model combustor capable of simulating turbojet operation at 40,000 feet was designed and built, and a gas sampling and analysis procedure developed for...

We present fully reactive interatomic potentials for systems containing gold, sulfur, carbon, and hydrogen, employing the ReaxFF formalism. The potential is designed especially for simulating gold-thiol systems and has been used for studying cluster deposition on self-assembled monolayers. Additionally, a large number of density functional theory calculations are reported, including molecules c...

/ Petroleum asphaltenes are defined as the n-pentane or n-heptane insoluble but toluene soluble fraction of crude oils or petroleum residua. This operational definition is a consequence of the extremely complex structure of asphaltenes which consist of thousands of compounds containing highly aromatic cores, long chain aliphatic groups, heteroatoms (sulfur, nitrogen, and oxygen) as well as trac...

stabilizer such as cane sugar to liquid lime-sulfur and evaporating to dryncss. Self-boiled lime-sulfur is made by utilizing the heat of hydration or slaking of quicklime, CaO, to carry on the reactions with sulfur. Ammonium polysulfide and sodium polysulfide are made by passing hydrogen Sulfide gas, H.^S, into ammonium or sodium hydroxide containing excess sulfur. It is supposed that the chemi...

Polysulfides formed through the breakdown of elemental sulfur or other sulfur compounds were found to be reduced to H(2)S by the hyperthermophilic archaebacterium Pyrococcus furiosus during growth. Metabolism of polysulfides by the organism was dissimilatory, as no incorporation of S-labeled elemental sulfur was detected. However, [S]cysteine and [S]methionine were incorporated into cellular pr...

A comparison of four selective detectors for analysis of single-digit ppb level sulfur is described. A dynamic blending system is used for point of use preparation of low level gaseous mixtures of eight sulfur compounds including H 2 S, COS, CS 2 and selected mercaptans in helium, ethylene, propylene, and carbon dioxide. The criteria to consider for selecting the best detector for an applicatio...

The enhanced inertness of the new 5973 inert MSD improves analysis of trace level volatile sulfur compounds. When operated in scan or selected ion monitoring mode, excellent sensitivity, selectivity, and peak symmetry are obtained for active compounds. Eight volatile sulfur species are used to demonstrate these attributes in a variety of hydrocarbon matrices. The system is well suited for the c...