(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.
Welding
Definition:
(p. pr. & vb. n.) of Weld
Example Sentences:
(1) Tests were undertaken to study resistance to tears in laser welded dental metal alloys.
(2) The possibility of contaminating the breathing air zone with hazardous substances in manual and semi-automated welding increases with the intensity of their formation in the arc zone.
(3) Laser repair has not been widely accepted both because the effect of laser irradiation on intact nerves is not well documented, and the anastomotic strength of the weld has been inferior to suture repair.
(4) The highest combined exposure (10-fold allowable value) was that of welders of steel coated with the zinc layer, using the metal active gas welding.
(5) The concentrations of 17 trace elements (e.g., copper, cobalt, iron, manganese, chromium, silicon and magnesium) were determined in whole blood samples of 81 persons working with different welding methods on stainless steel or aluminium and 68 nonwelders.
(6) These figures represent a participation rate of 37.1% in welders and 36.7% in non-welding subjects.
(7) Weak welds occurred with no thermal damage obtained at lower irradiances: stronger welds with thermal damage confined to the weld site occurred at higher irradiances.
(8) The results support the hypothesis that mild steel welding and to a lesser extent stainless steel welding with tungsten inert gas is associated with reduced semen quality at exposure in the range of the Danish process specific threshold limit values of welding.
(9) Low-level exposure to hexavalent chromium associated with TIG stainless steel and mild steel welding do not appear to be a major hazard for human spermatogenesis.
(10) Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision.
(11) The occurrence of reduced birthweight, preterm delivery, infant mortality, and congenital malformation was not increased among children at risk from paternal welding exposure in comparison with children not at risk.
(12) The goal of future research should be to make the procedure less operator-dependent (dye enhanced or automated welding).
(13) When nacreous shell produced by the marine oyster Pinctada maxima, used as a biomaterial in oral surgery, is implanted in human bone, new bone formation occurs, resulting in a tight welding of the bone to the nacre [16].
(14) Tensile strength, 0.2% proof stress, and percentage elongation of the welded bars were measured and compared with the corresponding values for the titanium bars as delivered and with those of brazed type-3 gold alloy bars of similar dimensions.
(15) It was proved in experiment that endothelium formation is more adequate in a vascular microsuture formed by laser welding than in the formed by the traditional thread method.
(16) 23.2% of patients with pneumoconiosis caused by electric-welding aerosol showed regress of pneumoconiosis in afterdust period.
(17) Results indicated that excellent welds can be obtained with very little loss of strength and ductility in the area of the weld joint.
(18) Dizziness, headaches, and weakness occurred among three men after short-term hydrocarbon exposure during improper welding procedures in a closed container.
(19) In periods of reconstruction of chemical enterprises, hazardous compounds concentrations may exceed MAC, they are also characterized by contamination of the skin with toxic substances, welding aerosols discharge into the working zone, and microclimate distabilization.
(20) A limited investigation was carried out of the use of glass and ceramic fibre products used as protection against welding 'batter' and oxyacetylene welding flame.