(n.) A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.
Example Sentences:
(1) The hypothesis that proteins are critical targets in free radical mediated cytolysis was tested using U937 mononuclear phagocytes as targets and iron together with hydrogen peroxide to generate radicals.
(2) It has been conformed that catalase from bovine liver eliminates only the pro R hydrogen atom from ethanol.
(3) We investigated the possible contribution made by oropharyngeal microfloral fermentation of ingested carbohydrate to the generation of the early, transient exhaled breath hydrogen rise seen after carbohydrate ingestion.
(4) Hydrogen isotope effects on these mutants indicate that MotA catalyzes proton transfer.
(5) Excessive accumulation of hydrogen ions in the brain may play a pivotal role in initiating the necrosis seen in infarction and following hyperglycemic augmentation of ischemic brain damage.
(6) Studies were conducted in isolated, buffer-perfused rat lungs to determine if prostaglandin (PG) E1 attenuated pulmonary edema provoked by hydrogen peroxide (H2O2).
(7) All N and O atoms except N(3) and O(4') participate in a three-dimensional hydrogen-bonding system.
(8) Both adiphenine.HCl and proadifen.HCl form more stable complexes, suggesting that hydrogen bonding to the carbonyl oxygen by the hydroxyl-group on the rim of the CD ring could be an important contributor to the complexation.
(9) Control mutant S38N has stability essentially the same as that of wild-type lysozyme but hydrogen bonding similar to that of the stabilizing mutant S38D.
(10) High intensity ultrasound also enhances the heterogeneous catalysis of alkene hydrogenation by Ni powders.
(11) An atmosphere of hydrogen eliminates this inhibition in the hydrogenase-containing T. foetus but not in E. invadens which lacks the enzyme.
(12) Vanadate-dependent oxidation of either pyridine nucleotide was inhibited by the addition of either superoxide dismutase or catalase, indicating that both superoxide and hydrogen peroxide may be intermediates in the process.
(13) Our findings suggest that (a) the inclusion of a liquid meal provides a reproducible method of measuring orocaecal transit using the lactulose hydrogen breath test, (b) rapid small bowel transit in thyrotoxicosis may be one factor in the diarrhoea which is a feature of the disease and (c) if altered gut transit is the cause of sluggish bowel habit in hypothyroidism, delay in the colon, and not small bowel, is likely to be responsible.
(14) Stepwise hydrogenation of metal tetradehydrocorrin salts (10 double bonds) yields a series of macrocycles containing 9, 8, 7, 6 and 5 double bonds and conditions necessary to obtain corrins have been established.
(15) For dipeptides containing the amino terminal residues glycine, alanine and phenylalanine, abstraction of the hydrogen from the carbon adjacent to the peptide nitrogen was the major process leading to the spin-adducts.
(16) (7) The first-order radical transformation rates are independent of the (initial) concentration of N3 or peptide and unaffected by urea (as a modifier of hydrogen bond structures).
(17) Intermolecular contacts occur in both oligomers in the minor groove: in the B form through twisted guanine-guanine hydrogen bonding, and in the Z form through base-base stacking and the water network.
(18) Equilibrium-partitioning measurements indicate that the relative affinities of different probes for PC-rich vesicles, in competition with HODMA or DOTAP vesicles, increase with increasing hydrogen-bonding capacity of the probe headgroup in the order PC less than N,N-dimethyl PE less than N-methyl PE less than PE approximately phosphatidyl-2-amino-1-propanol.
(19) When tissue metabolism was irreversibly inhibited by exposure to formaldehyde, hydrogen ion concentration and pCO2 were significantly decreased in the mucosal side of the chamber compared with the viable gall bladder.
(20) Based on the refined atomic coordinates of the tRNAphe in the orthorhombic crystal, on the recent advances in the distance dependence of the ring-current magnetic field effects and on the adopted values for the isolated hydrogen-bonded NH resonances, a computed spectrum consisting of 23 protons was constructed.
Mercaptan
Definition:
(n.) Any one of series of compounds, hydrosulphides of alcohol radicals, in composition resembling the alcohols, but containing sulphur in place of oxygen, and hence called also the sulphur alcohols. In general, they are colorless liquids having a strong, repulsive, garlic odor. The name is specifically applied to ethyl mercaptan, C2H5SH. So called from its avidity for mercury, and other metals.
Example Sentences:
(1) Sodium dodecyl sulfate-polyacrylamide gel analyses of these cross-linked nuclear receptor complexes labeled with the covalently attaching ligand [3H]tamoxifen aziridine reveal a species of about 130,000 mol wt, while the noncross-linked or the cross-linked but mercaptan-cleaved receptor is 65,000 mol wt.
(2) Linear distortion of the mercaptan (polysulfide) rubber base that takes place during setting is a cause of this problem.
(3) Three dialysis membranes, including a polyacrilonitrile membrane, a polycarbonate membrane and a cuprophan membrane coated with charcoal, have been compared with cuprophan in order to assess their ability to clear from aqueous solution and plasma, substances thought to be of pathogenetic importance in hepatic coma (ammonia, short chain fatty acids and mercaptans), some protein bound (glycocholate and bromsulphthalein) and some middle molecular weight molecules (ethylenediaminetetracetic acid, cyanocobalamin and inulin).
(4) A single and chronic inhalation exposure to a complex of chemical substances being part of hydrogen sulphide-containing natural gas (hydrogen sulphide, hydrocarbon, mercaptan, sulphur dioxide) results in a decline in humoral indicators of non-specific body resistance.
(5) A series of alkylthiocolchcines (methyl, ethyl, n-butyl, n-hexy, n-octyl, and pinanyl) was prepared from colchicine by treatment with the appropriate alkyl mercaptan and p-toluenesulfonic acid.
(6) Varieties of thioalkyl-containing quinone and hydroquinone analogues of quinocarcin (1a) were prepared effectively, by addition of mercaptan to 3a-c, which were derived from 1a via DX-52-1 (1b).
(7) Nine of these compounds, hydrogen sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide, methyl acetate, ethyl acetate, heptadiene, methanol, and ethanol, were found on chicken spoiled at both 2 and 10 degrees C. xylene, benzaldehyde, and 2,3-dithiahexane were detected only in samples stored at 2 degrees C and methyl thiolacetate, 2-butanone, and ethyl propionate were associated with 10 degrees C spoilage.
(8) Silicone and polyether materials exhibited perceptibly less permanent deformation than mercaptan materials ten minutes after mixing.
(9) Nucleophilic opening of the chiral epoxide with dodecyl mercaptan gave optically active 1-S-dodecyl-3-O-trityl-1-thio-glycerol, which was used to synthesize 1-S-dodecyl-2-O-decanoyl-thio-sn-glycero-3-phosphocholine.
(10) To induce increased tissue levels of ammonia, mercaptans and fatty acids which are found in HE due to FHF, carefully predetermined doses of urease, dimethyldisulphide and octanoic acid were administered.
(11) The structures of mercaptan and sodium borohydride reaction products of neocarzinostatin chromophore A (NCS Chrom A) are compared.
(12) Metabolic ethyl mercaptan is sufficiently bound to be undetectable by the methods used without hydrolysis.
(13) This system has been shown to be capable of catalyzing the desired reactions with endogenous toxins such as phenols and mercaptans in vitro, and phenols in rabbits in vivo.
(14) P-site cross-linking was more sensitive to mercaptan quenching (50% at 0.5 mM) than was that at the A site (50% at greater than 2.0 mM) but both were partially shielded from solvent.
(15) The drug, only under acidic conditions, reacted with a stoichiometric amount of ethyl mercaptan (or beta-mercaptoethanol) to produce regio-isomers of N-sulfenylated omeprazole sulfide (5-methoxy-2[[(4-methoxy-3,5- dimethyl-2-pyridinyl)methyl]thio]-1- or 3-(ethylthio)benzimidazole).
(16) from L-methionine, the production of large amounts of both dimethyl disulfide and methyl mercaptan was found to be a characteristic of the genus.
(17) The hemolytic action of commercially available nonionic surfactants and synthesized polyoxyethylene fatty acids and mercaptans on human erythrocytes was measured.
(18) Running of gas-cylinder buses (GCB) fueled with liquefied propane-butane mixture added with ethyl mercaptan odorant leads to undesirable medical and social consequences.
(19) 2-hydroxyethyl-mercaptan an ingredient used in mammalian cell culture, inhibited antibody production in trout cells.
(20) 2-Cyano-6-alkylthio- and 6-phenylthiopyrazines were prepared from 2-cyano-6-chloropyrazine (CCP) in the reaction with mercaptans.