The near ubiquitous distribution of nifH genes in sediments sampled from 14 high-temperature (48.0-89.0°C) and acidic (pH 1.90-5.02) geothermal springs in Yellowstone National Park suggested a role for the biological reduction of dinitrogen (N(2)) to ammonia (NH(3)) (e.g. nitrogen fixation or diazotrophy) in these environments. nifH genes from these environments formed three unique phylotypes t...

Acetylene hydratase is a tungsten-dependent enzyme that catalyzes the nonredox hydration of acetylene to acetaldehyde. Density functional theory calculations are used to elucidate the reaction mechanism of this enzyme with a large model of the active site devised on the basis of the native X-ray crystal structure. Based on the calculations, we propose a new mechanism in which the acetylene subs...

The following acetylenic substrates have been shown to mediate NADPH-dependent loss of cytochrome P450 on incubation with hepatic microsomes from phenobarbital-pretreated rats: 1-ethynylcyclohexanol, 1ethynylcyclopentanol, 3-methyl-1-pentyn-3-01, norethisterone, (1-methoxycyclohexyl)acetylene, 3-(2,4-dichlorophenoxy)-1-propyne, 3-(4-nitrophenoxy)-l-propyne, 3-phenoxy-l-propyne, 4-phenyl-l-butyn...

Previous investigations have demonstrated that the roles of fuel stream dilution (FSD) and air stream dilution (ASD) in suppressing CO2-diluted methane flames are strongly influenced by the level of partial premixing. Herein, we compare this influence for both counterflow and coflow laminar non-premixed and partially premixed flames (PPFs) established with various fuels, including methane, ethy...

We report, for the first time, quadrupole mass spectrometry of neutral and positive ionic hydrocarbon species measured at the rf-biased substrate electrode of an inductively coupled plasma for acetylene rich C2H2 : Ar mixtures under various bias, frequency and pressure conditions. It has been observed that, irrespective of initial gas mixture, the resultant plasma is dominated by argon neutrals...

We investigated the accuracy and the sensitivity of a modification of the acetylene inhalation technique for the determination of lung tissue volume (Vt) during various grades of hemodynamic pulmonary edema in 23 dogs. After base-line acetylene measurements were obtained, intravascular driving force (pulmonary wedge pressure minus intravascular colloid osmotic pressure) was varied between -8 a...

Recently it was reported that infrared CO2 CW laser irradiation of acetylene flow can produce continuous layer shell-shaped carbon nanoparticles (SCNP) directly from the gas when the laser power exceeds some critical value [Choi et al., 2004]. The transition process is distinguished by the blazing light emission in visible, indicating high electronic excitations in reacting molecules. It is rem...

Hydrogen production via plasma methane pyrolysis is investigated using a microwave torch (MPT) and gliding arc plasmatron (GAP). The performance of the two sources in terms conversion, product spectrum, energy efficiency compared. physical chemical properties produced carbon particles are conversion higher GAP than MPT. In MPT amorphous spherical volume source. stops after acetylene. acetylene ...

Complexes of dibenzo-18-crown-6 (DB18C6, host) with water, ammonia, methanol, and acetylene (guest) in supersonic jets have been characterized by laser induced fluorescence (LIF), UV-UV hole-burning (UV-UV HB), and IR-UV double resonance (IR-UV DR) spectroscopy. Firstly, we reinvestigated the conformation of bare DB18C6 (species m1 and m2) and the structure of DB18C6-H(2)O (species a) [R. Kusak...