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Thermal conductivity of simple molecular substances at crystal-liquid phase transition

Atoms in very high Rydberg states, 100 approx-lt n approx-lt 1100, are used to investigate electron-molecule interactions at electron energies extending down to a few microelectronvolts. At such energies the cross section for electron capture by CCl_4 is observed to vary inversely with electron velocity, indicative of an s-wave process. Studies with the polar target CH_3Cl suggest that dipole-supported states may be important in inelastic electron-polar molecule scattering at very low electron energies.

HCN polymers characterized by solid state NMR: Chains and sheets formed in the neat liquid

By the example of CH2Cl2, CF2Cl2, CHF2Cl, C2F6, C2H6, SF6 and C6H12 we have investigated the isobaric thermal conductivity jump at crystal-liquid phase transition. It is shown that the reduction in the thermal conductivity at melting derives from the degree of orientational ordering of the crystals at pre-melting point.

2009-01-01

UK PubMed Central (United Kingdom)

Hydrogen cyanide polymerizes readily under a variety of conditions and significant prebiotic roles have been suggested for these polymers due to the abundance of HCN in universe. However, the structures...Full Text Available

2009-04-07

Abundances of Jupiter's Trace Hydrocarbons From Voyager and Cassini

Ammoxidation of methanol to produce hydrogen cyanide

The flybys of Jupiter by the Voyager spacecraft in 1979, and over two decades later by Cassini in 2000, have provided us with unique datasets from two different epochs, allowing the investigation of seasonal change in the atmosphere. In this paper we model zonal averages of thermal infrared spectra from the two instruments, Voyager 1 IRIS and Cassini CIRS, to retrieve the vertical and meridional profiles of temperature, and the abundances of the two minor hydrocarbons, acetylene (C2H2) and ethane (C2H6). The spatial variation of these gases is controlled by both chemistry and dynamics, and therefore their observed distribution gives us an insight into both processes. We find that the two gases paint quite different pictures of seasonal change. Whilst the 2-D cross-section of C2H6 abundance is slightly increased and more ...

2010-01-01

Heterogeneous radiolysis of HCN adsorbed on a solid surface

Promoted antimony phosphate oxide complexes are excellent catalysts for the ammoxidation of methanol to HCN especially at high methanol throughputs.

1985-04-16

Glycine metabolism by Pseudomonas aeruginosa: hydrogen cyanide biosynthesis

Hydrogen cyanide is a key molecule for chemical evolution studies because, when it is exposed to different sources of energy, it forms various compounds of biological importance. To understand the role of minerals in chemical evolution, a series of experiments was performed. First, the adsorption capacity of HCN on different surface minerals was studied; the results show that HCN is readily adsorbed onto the solids proposed (zeolite, serpentine, dolomite, and sodium montmorillonite), in particular zeolite and montmorillonite. Second, the radiolysis of HCN adsorbed on olivine (as an example of a mineral surface) was also followed; it was found that the rate of HCN decomposition by gamma irradiation is enhanced in the presence of the solid. The third series of studies show that organic material was produced in high abundance from HCN at high radiation doses. The radiolytic products ...

2010-07-01

Science.gov (United States)

Hydrogen cyanide (HCN) production by Pseudomonas aeruginosa in a synthetic medium is stimulated by the presence of glycine. Methionine enhances this stimulation but will not substitute for glycine as a stimulator of cyanogenesis. Threonine and phenylalanine are effective substitutes for glycine in the stimulation of HCN production. Glycine, threonine, and serine are good radioisotope precursors of HCN, but methionine and phenylalanine are not. Cell extracts of P. aeruginosa convert (/sup 14/C)threonine to (/sup 14/C)glycine. H14CN is produced with low dilution of label from either (1-/sup 14/C)glycine or (2-/sup 14/C)glycine, indicating a randomization of label either in the primary or secondary metabolism of glycine. When whole cells were fed (1,2-/sup 14/C)glycine, cyanide and bicarbonate were the only radioactive extracellular products observed.

1977-05-01

A study of the photoionisation dynamics of chloromethane and iodomethane

Luminous HC3N line emission in NGC4418 - buried AGN or nascent starburst?

Angle resolved valence shell photoelectron spectra of chloromethane and iodomethane have been recorded using synchrotron radiation in the photon energy range 14-120eV. These have allowed photoelectron angular distributions and branching ratios to be determined not only for the main bands associated with the single-hole states but also for the satellite structure due to many-electron effects. The continuum multiple scattering approach has been used to calculate photoelectron asymmetry parameters and branching ratios for the valence orbitals of CH_3Cl and CH_3I, and also for the I 4d subshell. A comparison between the experimental data and the theoretical predictions has enabled the influence of Cooper minima, shape resonances and intershell coupling to be assessed. The asymmetry parameters and branching ratio for the spin-orbit split components of the CH_3I"+X-bar "2E state have been measured and exhibit a spectral behaviour ...

2006-08-01

Syntheses of all singly labeled (/sup 15/N)adenines: mass spectral fragmentation of adenine

IRAM 30m observations reveal that the deeply obscured IR-luminous galaxy NGC4418 has a rich molecular chemistry - including unusually luminous HC3N line emission. We furthermore detect: ortho-H2CO 2-1, 3-2; CN 1-0, 2-1; HCO+, 1-0. 3-2, HCN 3-2, HNC 1-0, 3-2 (and tentatively OCS 12-11). The HCN, HCO+, H2CO and CN line emission can be fitted to densities of n=5 x 10E4 - 10E5 cm-3 and gas temperatures Tk=80-150 K. Both HNC and HC3N are, however, significantly more excited than the other species which requires higher gas densities - or radiative excitation through e.g. mid-IR pumping. The HCN line intensity is fainter than that of HCO+ and HNC for the 3-2 transition, in contrast to previous findings for the 1-0 lines where the HCN emission is the most luminous. We tentatively suggest that the observed molecular line emission is consistent with a young starburst, where the emission can be understood as ...

2007-01-01

Science.gov (United States)

Syntheses of all five of the singly labeled (/sup 15/N)adenines are now provided. The presence or absence of two-bond /sup 15/N-/sup 1/H spin couplings in their /sup 1/H NMR spectra confirm the location of the isotope in each case. The fragmentation patterns in their mass spectra are indicative of the sequential losses of HCN units and of CH/sub 2/N/sub 2/ from adenine upon electron impact.

1981-07-01

Changes of the electron density distribution during MHD activity in CHS

Synthesis of N-(3-azido-4-chlorophenyl)-N'-["3H-methyl] thiourea, an efficient photoaffinity probe for the urea carrier

Density oscillations induced by MHD activities were observed in NBI heated plasmas on CHS by using an HCN laser interferometer. The accompanied changes of the density profiles were also observed. The oscillations are composition of m=0 sawteeth like crash and m=2 sinusoidal oscillations as a post courser of the crash. Possible models of the oscillation structure are examined in order to explain experimental data of the interferometer. Rotating plasma core, which is hollow profile and keeps constant elongation of the flux surface can explain amplitude and phase distribution of the sinusoidal oscillation. (author)

2000-09-01

Corrosion of gold bridgewire in electronic components

Starting from commercial 4-chloro-3-nitroaniline, through a 5 step synthesis, 3-azido-4-chlorophenylisothiocyanate was prepared and reacted with ["3H]-methylamine. The latter was obtained by three methods: (i) ["3H]-LiA1T_4 reduction of benzylcarbamate gave rise to ["3H]-methylamine (S.A.: > 70 Ci/mmol). (ii) Catalytic reduction of HCN with "3H_2 lead to ["3H]-CH_3NH_2 (S.A.: 0.7 Ci/mmol). (III) Schmidt rearrangement of ["3H]-sodium acetate gave ["3H]-CH_3NH_2 (S.A.: 29 Ci/mmol). (author).

NO formation in the burnout region of a partially premixed methane-air flame with upstream heat loss

Accelerated aging tests on gold bridgewired detonator assemblies to determine compatibility of the Au and Pd-In-Sn solder with the organic explosive, PENT, have revealed an unusual corrosion process. These tests, conducted at 74/sup 0/C and 54/sup 0/C indicated a preferential attack of the gold. A matrix of corrosion test units was established to study this corrosion problem with accelerating temperatures up to 100/sup 0/C. Scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and x-ray diffraction techniques were used to determine the extent of the corrosion and identify the corrosion products. Results indicate the preferential attack of the gold was due to HCN formed by decomposition of the explosive powder (PETN) at high temperatures. Other associated reactions were also observed including subsequent attack of the solder by the gold corrosion product and degradation of the plastic header.

1986-01-01

The Local Environment of the FUor-like Objects AR 6A and 6B

Measurements of temperature and NO concentration in laminar, partially premixed methane-air flames stabilized on a ceramic burner in coflow are reported. The NO concentration and temperature were determined by laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Upstream heat loss to the burner was varied by changing the exit velocity of the fuel-air mixture at a constant equivalence ratio of 1,3; this alters the structure of the flame from an axisymmetric Bunsen-type to a strongly stabilized flat flame. To facilitate analysis of the results, a method is derived for separating the effects of dilution from those of chemical reaction based on the relation between the measured temperature and the local mixture fraction, including the effects of upstream heat loss. Using this method, the amount of NO formed during burnout of the hot, fuel-rich combustion products can be ascertained. In the Bunsen-type flame, it is seen that {approximately}40 ppm ...

1999-09-01

Modeling and Analysis of K-Tier Downlink Heterogeneous Cellular Networks

We present new 12CO J=3-2 and HCN J=3-2 molecular line maps of the region surrounding the young star AR 6 using the 15 metre James Clerk Maxwell Telescope. AR 6 was previously found to be a double source with both components exhibiting several characteristics of FU Orionis (FUor) eruptive variable stars. Our data indicates that AR 6, like FU Orionis itself, does not possess a CO outflow and likewise, does not show evidence for large amounts of molecular g as in its circumstellar environment. We conclude that from the near-IR to the sub-mm, AR 6 is similar to FU Orionis in several respects. We interpret the lack of significant dust and molecular gas in the circumstellar environment of AR 6, together with the large near-IR thermal excess, as evidence that the sources have exhausted their natal envelopes, that they have at least small hot circumstellar disks, and that they are more evolved than Class I protostars. This, in itself, suggests that, since FUor eruptions ...

2008-01-01

High Velocity Molecular Outflows In Massive Cluster Forming Region G10.6-0.4

Cellular networks are in a major transition from a carefully planned set of large tower-mounted base-stations (BSs) to an irregular deployment of heterogeneous infrastructure elements that often additionally includes micro, pico, and femtocells, as well as distributed antennas. In this paper, we develop a tractable, flexible, and accurate model for a downlink heterogeneous cellular network (HCN) consisting of K tiers of randomly located BSs, where each tier may differ in terms of average transmit power, supported data rate and BS density. Assuming a mobile user connects to the strongest candidate BS, the resulting Signal-to-Interference-plus-Noise-Ratio (SINR) is greater than 1 when in coverage, Rayleigh fading, we derive an expression for the probability of coverage (equivalently outage) over the entire network under both open and closed access, which assumes a strikingly simple closed-form in the high SINR regime and is accurate down to -4 dB even under weaker ...

2011-01-01

Combustion of chemical substances. Fire characteristics and smoke gas components in large-scale experiments

We report the arcsecond resolution SMA observations of the $^{12}$CO (2-1) transition in the massive cluster forming region G10.6-0.4. In these observations, the high velocity $^{12}$CO emission is resolved into individual outflow systems, which have a typical size scale of a few arcseconds. These molecular outflows are energetic, and are interacting with the ambient molecular gas. By inspecting the shock signatures traced by CH$_{3}$OH, SiO, and HCN emissions, we suggest that abundant star formation activities are distributed over the entire 0.5 pc scale dense molecular envelope. The star formation efficiency over one global free-fall timescale (of the 0.5 pc molecular envelope, $\\sim$10$^{5}$ years) is about a few percent. The total energy feedback of these high velocity outflows is higher than 10$^{47}$ erg, which is comparable to the total kinetic energy in the rotational motion of the dense molecular envelope. From order-of-magnitude estimations, we suggest ...

2010-01-01

Heavy fuel oil combustion in a cylindrical laboratory furnace: measurements and modeling

This report describes the combustion experiments performed using the SP Industry Calorimeter. In addition to measuring parameters such as heat release rate (HRR), mass loss rate, effective heat of combustion and smoke obscuration, considerable effort was put into the characterisation of the smoke gases in order to obtain a basis for evaluations of the toxic potency of the smoke. The materials studied were Nylon 66, polypropene, polystyrene (with and without fire retardant, respectively), PVC and chlorobenzene. A total of 19 large-scale, well ventilated combustions were carried out. The mass of sample burned ranged from 20 kg to 125 kg in an experiment. A procedure was designed for cleaning the smoke gas duct between experiments and was found to be effective. Measurements were carried out for the amounts of O{sub 2}, CO{sub 2}, CO, NO{sub x}, THC (unburned hydrocarbons), HCN, HCl, NH{sub 3} and individual organic compounds in the smoke. Adsorbents were used for the ...

1995-12-31

A model for the devolatilization of a coal particle sufficiently large to be controlled by heat transfer

The finite-volume based commercial CFD-code Fluent was used to simulate the reacting flow in a heavy fuel oil fired laboratory furnace. Both the standard {kappa}-{epsilon} turbulence model and the Reynolds stress model (RSM) were tested. The combustion model was based on the conserved scalar (mixture fraction) and prescribed probability density function approach. The heavy fuel oil droplet trajectories were predicted by solving the momentum equations for the droplets using the Lagrangian treatment. The soot distribution in the furnace was calculated by solving a transport equation for the soot mass fraction. Simple expressions for the soot formation and oxidation rates were employed. The radiation heat transfer equation was solved using the finite volume method. The formation of thermal NO from molecular nitrogen was modeled according to the extended Zeldovich mechanism. Fuel-based NO was modeled assuming that all the nitrogen in the fuel is released as hydrogen cyanide ...

2005-03-01

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