(n.) A gaseous compound of carbon and hydrogen, in the proportion of two atoms of the former to two of the latter. It is a colorless gas, with a peculiar, unpleasant odor, and is produced for use as an illuminating gas in a number of ways, but chiefly by the action of water on calcium carbide. Its light is very brilliant.
Example Sentences:
(1) Optimum rates of acetylene reduction in short-term assays occurred at 20% O2 (0.2 atm (1 atm = 101.325 kPa] in the gas phase.
(2) On siratro, CIAT899 induced nodules that were ineffective in acetylene reduction, whereas the EPS-deficient mutants induced effective nodules.
(3) It is suggested that acetylene reduction assays may not be accurately applied to samples containing methane oxidizing bacteria.
(4) Biological nitrogen fixation, as determined by acetylene reduction, occurs in Lake Erie.
(5) Some of the thiophenes and their acetylenic derivatives possess extremely potent phototoxic activities toward membrane-containing viruses.
(6) The efficiencies of the different positional isomers in supporting cell proliferation varied from essentially 0 cells per fmol for the 2-5 and 13-17 isomers to high values when the acetylenic bond was near the center of the chain: e.g.
(7) If the cultures were grown in media with NH4+, NO3-, urea, glutamine or asparagine, hydrogen photoevolution by the cells and acetylene reduction started after the lag-phase and proceeded at a low rate.
(8) Under suitable growth conditions the acetylenic acids are catabolized and partly reused via acetate for de novo synthesis of fatty acids.
(9) 2-Ethynyl-4,5-diphenylthiazoles were synthesized by the palladium catalyst cross-coupling reaction of 2-iodo-4,5-diphenylthiazole with monosubstituted acetylenes.
(10) The conditions which are necessary for the synthesis and function of this system were studied in whole cells by using acetylene reduction as a sensitive assay for the presence of the N(2)-fixing system.
(11) However, in culture under aerobic conditions, large, phase-bright vesicles are formed in HFPCcI3 within 20 h following removal of NH+4 from the culture medium and reach peak numbers within 72 to 96 h. In vivo acetylene reduction activity parallels vesicle formation.
(12) Vesicles permeabilized by freeze-thaw or detergents showed increased rates of acetylene reduction due to increased permeability of dithionite.
(13) After 30 minutes at this new driving force, four timed acetylene samples were again collected.
(14) 3-(1,2,3-Triazol-1-yl)methylcephalosporins have been prepared by the direct cycloaddition of acetylene to 3-azidomethylcephalosporins, which were obtained by nucleophilic substitution of 3-chloromethylcephalosporins with sodium azide in N,N-dimethylformamide.
(15) Biological dinitrogen fixation in mangrove communities of the Tampa Bay region of South Florida was investigated using the acetylene reduction technique.
(16) Nitrate reductase (nar) A, B and E mutants of Escherichia coli with plasmids carrying Klebsiella pneumoniae nitrogen fixation (nif) genes reduced acetylene independently of added molybdate, but nar D mutants showed pleiotropic dependence on the concentration of added molybdate for expression of both nar and nif.
(17) Two important side reactions of this procedure are known: the formation of the isomeric beta-ethynyl derivative and the formation of a dimeric product with acetylene bridge.
(18) Acetylene-reducing activity of purified nitrogenase from Klebsiella pneumoniae was studied over a range of ATP and Mg(2+) concentrations at 15 degrees C, pH7.8.
(19) The reconstituted acid mixture is injected into the graphite tube atomizer for analysis of Cu and Cd and aspirated into the air--acetylene flame for measurement of Zn.
(20) The 19-acetylenic testosterone, a confirmed metabolite from primate studies, was 25% as efficient as MDL 18,962 for aromatase inactivation, while 6 beta-hydroxy- and 6-oxo analogs were 11% and 5%, respectively as efficient as their parent compound.
Ethene
Definition:
(n.) Ethylene; olefiant gas.
Example Sentences:
(1) The proposed assay should be useful for in vitro metabolic studies of 1,2-dihaloethanes and mustards and has potential application for similar studies of monohalogenated ethanes, ethanols, and ethenes.
(2) A total of nine chlorinated ethanes and ethenes were circulated over lithium hydroxide in a laboratory scale closed system simulator.
(3) The level of adducts from ethene, determined as N-(2-hydroxyethyl)valine, was also higher in mice from diet S than in animals fed diet C, when all treatment groups were considered.
(4) About equimolar concentrations of bleomycin and FeCl3 resulted in optimal ethene formation.
(5) Halogenated ethenes are oxidatively metabolized by cytochrome P-450 to intermediates which inactivate cytochrome P-450 by destroying heme and to epoxides which may react with cellular macromolecules or decompose to other products.
(6) Previous mixed-culture studies have demonstrated that complete dechlorination to ethene is possible, although the final dechlorination step from vinyl chloride to ethene is rate limiting, with significant levels of vinyl chloride typically persisting.
(7) The results demonstrate a raised level of hydroxyethylation of N-terminal valine of Hb of smokers that is quantitatively compatible with ethene in the smoke being the source.
(8) Lipid peroxidation and metabolism of intestinal bacteria, giving rise to ethene, precursor of ethylene oxide, are thus indicated to be sources of observed background hydroxyethylations.
(9) The bioconversions with the three most promising ethene-utilizers (M26, M90C, M93A) were scaled-up to yield essentially optically pure (enantiomeric excess = 93%) S-(+)-phenyl glycidyl ether.
(10) This figure is compatible with a metabolic conversion of 3% (1-10%) of the inhaled ethene to ethylene oxide.
(11) KMBA was converted to ethene by dithranol under aerobic conditions, whereas ethene formation was negligible in the absence of oxygen.
(12) Ethene formation depended on oxygen, NADPH, FeCl3 and the enzyme.
(13) The limitations of Fluosol DA led to fluorocarbons under investigation such as F dimethyl bicyclononanes, F methyladamantane, bis (F-butyl) ethene or F-octylbromide.
(14) Eighteen newly isolated ethene- and propene-utilizing bacteria were screened for the ability to produce phenyl glycidyl ether, a common precursor for the synthesis of beta blockers, from phenyl allyl ether.
(15) O2- - and .OH-scavengers such as rutin, catechin, dimethyl sulfoxide, mannitol, ethanol, sodium salicylate and propyl gallate as well as catalase and superoxide dismutase inhibited ethene formation.
(16) Because the singlet oxygen (1O2) sensitizer, rose bengale, showed enlarged production of ethene when irradiated in the presence of KMBA, experiments were performed in the dark in order to avoid 1O2 production by dithranol.
(17) Efforts to measure adducts originating from ethene in environmental tobacco smoke and urban air show, however, that the resolving power of the methods used for identifying unknown risk factors must be increased.
(18) The detection limit was one pmol ethene or ethane per five mL air sample; the within-run precision (CV) of analysis was 2.1 percent at an ethane concentration of 16 pmol per five mL sample.
(19) For unknown reasons, uninduced mice varied strongly in the extent to which they converted ethene to epoxide.
(20) A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions.