Production Of HD Research Articles

Interaction of ammonia and hydrogen with tungsten at elevated temperature studied by gas flow through a capillary

The interaction of ammonia and hydrogen (H2 and D2) was studied by flowing pure gas or gas mixture through a hot tungsten capillary. The composition of the gas after passing the capillary was analyzed by mass spectrometry as a function of capillary temperature. Specific temperatures were identified where changes in mass spectra take place indicating thermal decomposition and isotope exchange channels. Measurements with pure ammonia and deuterium provided new data for the thermal decomposition of these molecules on hot tungsten. Ammonia gets effectively decomposed at around 900 K in the tungsten capillary, and only 7% of ammonia survives through the capillary at temperatures above 1100 K. By studying the production and desorption of HD in ammonia and deuterium mixture, the authors show that D2 molecules can get adsorbed on tungsten dissociatively only at temperatures above 1300 K in the presence of nitrogen or ammonia fragments. An adsorption barrier of 0.17 eV is determined for this case. A comparison of ...

고지방 식이가 C57/BL6생쥐의 복강대식세포 면역능력에 미치는 영향

본 연구는 5주간의 고지방 식이(45% 지방)가 복강 대식세포의 면역 반응에 미치는 효과를 분석하였다. C57BL/6 마우스(4주령, N=16)를 2집단으로 나누어 고지방 식이집단(HD, N=8)은 45% 지방 함량 고지방식이를 정상 식이집단(ND, N=8)은 정상식이(10% 지방)를 5주간 실시하였다. 복강 대식세포는 복강세척법을 이용하여 획득하였으며, LPS (lipopolysaccharide, <TEX>$1{\mu}g/ml$</TEX>, 24시간)를 이용하여 배양하였다. 체중은 고지방식이 후 유의하게 증가하였으며, LPS 처치 후 HD그룹의 산화질소, IL-<TEX>$1{\beta}$</TEX> 및 IFN-<TEX>${\gamma}$</TEX> 생성량은 ND그룹에 비하여 유의하게 낮았다. 그러나 두 집단에서 TNF-<TEX>${\alpha}$</TEX>와 IL-12의 생성량은 유의한 변화가 없었다. 이러한 결과는 비만 시 대식세포의 식균작용, 산화질소, IL-<TEX>$1{\beta}$</TEX> 및 IFN-<TEX>${\gamma}$</TEX> 생성량이 낮아짐에 따라 면역반응과 항원자극 감수성이 저하되는 것으로 사료된다. This study was to investigate the effect of high-fat diet on macrophage immunocompetence in C57BL/6 mice. C57BL/6 male mice (4 weeks aged, n=16) were divided into two groups. HD groups fed high-fat diet (45% of fat) and ND groups fed chow diet (10% of fat). Peritoneal macrophages were obtained from each mouse intra-peritoneal by sterile lavage method. Macrophage were stimulated with <TEX>$1{\mu}g/ml$</TEX> of lipopolysaccharide (LPS) for 24 hr. Body weight was significantly increased by high-fat diet. Macrophage phagocytosis of HD was significantly lower than that of ND. After 24 hr of LPS stimulation, NO, IL-<TEX>$1{\beta}$</TEX> and IFN-<TEX>${\gamma}$</TEX> production of HD were significantly lower than those of ND. There were no significant differences in the production of TNF-<TEX>${\alpha}$</TEX> and IL-12 between HD and ND. These findings suggest that high fat diet-induced obesity is associated with decreased Immunocompetence and antigen-stimulated sensitivity of peritoneal macrophage, and lower production of NO, IL-<TEX>$1{\beta}$</TEX> and IFN-<TEX>${\gamma}$</TEX> may contribute to these changes.

In-Line Calibration of Raman Systems for Analysis of Gas Mixtures of Hydrogen Isotopologues with Sub-Percent Accuracy

Highly accurate, in-line, and real-time composition measurements of gases are mandatory in many processing applications. The quantitative analysis of mixtures of hydrogen isotopologues (H2, D2, T2, HD, HT, and DT) is of high importance in such fields as DT fusion, neutrino mass measurements using tritium β-decay or photonuclear experiments where HD targets are used. Raman spectroscopy is a favorable method for these tasks. In this publication we present a method for the in-line calibration of Raman systems for the nonradioactive hydrogen isotopologues. It is based on precise volumetric gas mixing of the homonuclear species H2/D2 and a controlled catalytic production of the heteronuclear species HD. Systematic effects like spurious exchange reactions with wall materials and others are considered with care during the procedure. A detailed discussion of statistical and systematic uncertainties is presented which finally yields a calibration accuracy of better than 0.4%.

High efficiency preparation of bioactive human α-defensin 6 in Escherichia coli Origami(DE3)pLysS by soluble fusion expression

Human alpha-defensin 6 (HD(6)), a small cysteine-rich cationic peptide specially expressed in epithelial cells of digestive tract, may play a crucial role in mucosal immunity. This is the first report on efficient production of bioactive HD(6) through a gene-engineering approach in Escherichia coli. The recombinant plasmid pET32a-omHD(6) was primarily constructed by inserting a PCR fragment encoding mature HD(6) peptide (mHD(6)) preceded by an enterokinase recognition sequence into the expression vector pET32a(+), in frame with the upstream thioredoxin (TrxA) gene. Under optimized expression conditions, a high percentage (>60%) of soluble TrxA-omHD(6) fusion protein was obtained with a yield of about 1.69 g/l, and the theoretical productivity of recombinant mHD(6) (rmHD(6)) reached 0.38 g/l. A feasible three-step purification strategy involving nickel-sepharose chromatography, enterokinase-cleavage and cation exchange chromatography was developed to purify rmHD(6), followed by characteristic identifications by Western blot, mass spectrometry and sequencing. About 102 mg/l of rmHD(6) with its intact N-terminal amino acid sequence was finally achieved. The in vitro experiments showed that rmHD(6) possesses high potency to inhibit herpes simplex virus-2 infection. This work settles substantial foundation for further functional study of HD(6).

HD and H2formation in low-metallicity dusty gas clouds at high redshift

Context. HD and H-2 molecules play important roles in the cooling of primordial and very metal-poor gas at high redshift. Aims. Grain surface and gas phase formation of HD and H-2 are investigated to assess the importance of trace amounts of dust, 10(-5)-10(-3) Z(circle dot), in the production of HD and H-2. Methods. We consider carbonaceous and silicate grains and include both physisorption and chemisorption, tunneling, and realistic grain surface barriers. We find that, for a collapsing gas cloud environment with coupled chemical and thermal balance, dust abundances as small as 10(-5) solar lead to a strong boost in the H-2 formation rate due to surface reactions. As a result of this enhancement in H-2, HD is formed more efficiently in the gas phase through the D+ + H-2 reaction. Direct formation of HD on dust grains cannot compete well with this gas phase process for dust temperatures below 150 K. We also derive up-to-date analytic fitting formulae for the grain surface formation of H-2 an HD, including the different binding energies of H and D. Results. Grain surface reactions are crucial to the availability of H-2 and HD in very metal-poor environments. Above metallicities of 10(-5) solar, the grain surface route dominates the formation of H-2, which in turn drives the formation of HD in the gas phase. At dust temperatures above 150 K, laboratory experiments and theoretical modeling suggest that H-2 formation on grains is suppressed while HD formation on grains is not.

Toxicity Assessment of Thiodiglycol

Sulfur mustard (HD) undergoes hydrolysis to form various products such as thiodiglycol (TG) in biological and environmental systems. TG is a precursor in the production of HD and it is also considered as a "Schedule 2" compound (dual-use chemicals with low to moderate commercial use and high-risk precursors). Several toxicological studies on TG were conducted to assess environmental and health effects. The oral LD(50) values were >5000 mg/kg in rats. It was a mild skin and moderate ocular irritant and was not a skin sensitizer in animals. It was not mutagenic in Ames Salmonella, Escherichia coli, mouse lymphoma, and in vivo mouse micronucleus assays, but it induced chromosomal aberrations in Chinese hamster ovarian (CHO) cells. A 90-day oral subchronic toxicity study with neat TG at doses of 0, 50, 500, and 5000 mg/kg/day (5 days/week) in Sprague-Dawley rats results show that there are no treatment-related changes in food consumption, hematology, and clinical chemistry in rats of either sex. The body weights of both sexes were significantly lower than controls at 5000 mg/kg/day. Significant changes were also noted in both sexes in absolute weights of kidneys, kidney to body weight ratios, and kidney to brain weight ratios, in the high-dose group. The no-observed-adverse-effect level (NOAEL) for oral toxicity was 500 mg/kg/day. The developmental toxicity conducted at 0, 430, 1290, and 3870 mg/kg by oral gavage showed maternal toxicity in dams receiving 3870 mg/kg. TG was not a developmental toxicant. The NOAEL for the developmental toxicity in rats was 1290 mg/kg. The provisional oral reference dose (RfD) of 0.4 mg/kg/day was calculated for health risk assessments. The fate of TG in the environment and soil showed biological formation of thiodiglycalic acid with formation of an intermediate ((2-hydroxyethyl)thio)acetic acid. It was slowly biodegraded under anaerobic conditions. It was not toxic to bluegill sunfish at 1000 mg/L and its metabolism and environmental and biochemical effects are summarized.

Application of the END Theory to the H + D2 → HD + D Reaction

We investigate time-delay effects in the formation of HD products when H projectiles collide with D2 targets with a collision energy of 1.64 eV in the center-of-mass frame using the electron−nuclear dynamics (END) approach. Trajectories having target orientations within a 60° cone measured about the D−D bond are those that lead to the production of HD. In the impact-parameter regions that correspond to the formation of HD, we note a large change in the scattering angle of the HD product within a localized narrow region as a function of impact parameter. Calculated classical and semiclassical differential reaction cross sections are presented and compared to available experimental data. Finally, a coherent-state study of the vibrational modes for the product HD is presented.

Enhanced production of HD and D2molecules on small dust grains in diffuse clouds

Motivated by recent observations of deuterated molecules in the interstellar medium, we examine the production of HD and D 2 molecules on dust grain surfaces. A mechanism for the enhanced production of these deuterated molecules is studied. This mechanism applies on grain surfaces on which D atoms stick more strongly than H atoms, under conditions of low flux and within a suitable range of temperatures. It is shown that under these conditions the production rates of HD and D 2 are greatly enhanced (versus the H 2 production rate) compared with the expected rates based on the adsorption of gas-phase atomic abundances of D and H. The enhancement in the formation rate of HD is comparable to the enhancement due to gas-phase ion-molecule reactions in diffuse clouds.

開発機械 大型ダンプトラックＨＤ９８５‐３の開発

The production of KOMATSU HD 785-3, 78 ton class dump truck was started in 1988.About 500 units of HD 785-3 were shipped to miners or constructors all of the world, but not only in domestic market. The reputation of this truck is high production and good reliability.Recently, many customers of 78 ton class dump truck desire to upgrade their trucks in 100 ton class for more productivity.KOMATSU HD 985-3 which has the larger size tires is developed with aim of the first truck in 100 ton class to meet the requirements raised at the meetings with the customers.

Quasiclassical state to state reaction cross sections for D+H2(v=0, j=0)→HD(v′,j′)+H. Formation and characteristics of short-lived collision complexes

State resolved total and differential reaction cross sections, as well as reaction probabilities, have been calculated by the quasiclassical trajectory (QCT) method for the D+H2(v=0, j=0)→HD(v′,j′)+H reaction on the Liu–Siegbahn–Truhlar–Horowitz potential energy surface in the collision energy range 0.30–1.25 eV. Thus a detailed comparison with existing fully converged quantum mechanical (QM) calculations has been performed. The general agreement between both sets of results is good with some differences. QCT integral reaction cross sections for the production of HD(v′=0) are lower than the corresponding QM ones by 10%–15% for collision energies higher than 0.6 eV, and the energy dependence of the QCT reaction probability with a total angular momentum J equal to zero shows no structure when summed over all j′ states (contrary to the QM case). The differential cross sections for the lowest j′ values show, when represented as a function of energy, a ‘‘ridge’’ feature similar to the one found in exact QM calculations and attributed to a broad resonance. The analysis of the trajectories leading to low j′ shows progressively longer collision times as the scattering angle decreases. The longest-lived trajectories, related to the formation of short-lived complexes, cause local maxima in the differential cross section at the lowest scattering angles for each energy. These local maxima are the origin of the ridge. The lifetime of the classical short-lived complexes is estimated to be 15–35 fs, clearly larger than the lifetimes obtained from the width of the ridge feature, when interpreted as a quantum mechanical resonance.

Mass spectrometric studies of trimethylindium pyrolysis

The homogeneous decomposition of trimethylindium (TMIn) in an atmospheric pressure flow tube apparatus was studied with a time-of-flight mass spectrometer in He, D 2, and H 2 carriers. Rate constants following the expressions log k gHe( s −1)= 17.9− 54.0( kcal/mol) 2.303RT , log k gD2( s −1)= 13.4−39.8( >kcal/mol) 2.303RT , and log k gH2( s −1)= 15.0−42.6( kcal/mol) 2.303RT were determined for the three carriers. The rate constant for pyrolysis in He is comparable to that found previously for pyrolysis in a radical scavenger; consequently, TMIn predominantly decomposes by homolytic fission in He, and not by radical attack by methyl groups on the TMIn. The pyrolysis of TMIn is enhanced in D 2 and H 2 carriers, where the principal products are CH 3D and C 2H 6, and CH 4 and C 2H 6, respectively. The ratio of the products (CH 3D or CH 4) C 2H 6 in the H 2 and D 2 carriers monotically decreases with increasing temperature. TMIn pyrolysis in a 1:1 D 2:H 2 carrier shows a very low production of HD due to isotopic randomization by H and D radicals. Both the enhanced pyrolysis in H 2 and D 2, and the gas phase mass balance of carbon at all temperatures, is attributed to radical attack by H or D on TMIn. With numerical modelling techniques a novel reaction mechanism involving a short-lived hypervalent DTMIn species was tested.

Inhibition of nitrogenase-catalyzed NH3 formation by H2.

We have investigated the inhibition by H2 (D2) of NH3 formation by nitrogenase from Klebsiella pneumoniae and have confirmed that the inhibition is competitive vs. N2. D2 inhibits NH3 formation by diverting nitrogenase from production of NH3 to production of HD (one electron per HD). By careful exclusion of N2 from the reaction mixture, we have been able to place an upper limit on N2-independent HD formation by nitrogenase, under 1 atm of D2, at 1% of the total electron flux. Formation of NH3 and formation of HD were inhibited identically by CO. We observed that as the ratio of dinitrogenase to dinitrogenase reductase is increased, the ratio of HD formed to NH3 formed rises, and D2 becomes a stronger inhibitor of N2 reduction. This may be caused in part by an accompanying increase that is observed in the Km of nitrogenase for N2. We propose a model for D2 inhibition of NH3 formation in which D2 and N2 complete for the same form of nitrogenase. According to our proposal, when N2 reacts with nitrogenase, either N2 reduction proceeds to completion if H2 (D2) is absent or, if D2 already is bound to nitrogenase, N2 reduction is aborted and two molecules of HD are produced at the net expense of one electron per HD. Key consequences of the model are that it predicts that H2 (D2) is a competitive inhibitor of NH3 formation and that the apparent Km (N2) for formation of HD and NH3 may differ.

The role of surface irregularities (steps, kinks) and point defects on the chemical reactivity of solid surfaces

Abstract The role of surface defects on the chemical reactivity of single crystal surfaces is illustrated here with three examples. In the first example we show how the presence of monatomic steps, on an otherwise flat Pt(111) surface, alters the chemisorption and dissociation of H. It was found by use of a mixed molecular beam of H2+D2that the production of HD depends on the angle of incidence of the beam with respect to the step edges being larger when the incident direction is perpendicular to the open side of the step edges. In the second example, we show how the kinetics of oxide growth in a Ni(100) crystal is affected by the presence of defects induced by ion bombardment of the surface. We have found that the initial rate of oxygen incorporation following the chemisorption stage is directly proportional to the dose of Ar ions used to produce the damage. In the annealed, un-bombarded Ni(100) surface, the incorporation of of oxygen stops after a surface oxide layer is completed. In the third example w...

Type I supernovae, R Coronae Borealis stars, and the Crab Nebula

view Abstract Citations (59) References (56) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Type I supernovae, R Coronae Borealis stars, and the Crab Nebula. Wheeler, J. C. Abstract Present observations and theory point to Type I supernovae (SN I) as being old disk-population helium-rich red supergiants at the time of outburst. There is a class of stars which correspond to these specifications, the hydrogen-deficient carbon (Hd C) stars, the best known subclass of which are the R Coronae Borealis variables; hence these stars may be SN I progenitors. Within present rather large uncertainties the rate of production of Hd C stars is consistent with the rate of Type I supernovae in the Galaxy. Paczynski's (1971) suggestion that R Coronae Borealis stars are mixed, completely hydrogen-depleted stars of 1-2 solar masses may call for extended main-sequence lifetimes, which in turn would explain how stars with masses greater than the Chandrasekhar mass are only now evolving to explosive end points in elliptical galaxies. The Crab Nebula, being helium-rich, metal-poor, and apparently of only moderate mass, may also be related to this class of event. Publication: The Astrophysical Journal Pub Date: October 1978 DOI: 10.1086/156484 Bibcode: 1978ApJ...225..212W Keywords: Carbon Stars; Crab Nebula; R Coronae Borealis Stars; Supergiant Stars; Supernovae; Variable Stars; Abundance; Elliptical Galaxies; Red Giant Stars; Stellar Evolution; Stellar Mass; Astrophysics; Crab Nebula; R CrB Stars:Supernovae full text sources ADS | data products SIMBAD (6)

Molecular beam study of the H2–D2 exchange reaction on stepped platinum crystal surfaces: Dependence on reactant angle of incidence

The exchange reaction H2+D2→2HD was studied as a function of the angle of incidence (polar and azimuthal) of the beam of reactants on two stepped platinum surfaces, the Pt(S) -[6(111) × (111)] and Pt(S) -[5(111) × (111)]. The reaction probability was found to depend markedly on the direction of approach of the reactants to the step structure. The production of HD is highest when the reactants strike the open side of the step structure, decreasing by approximately a factor of 2 when the inner corner of the step is shadowed. These variations are intimately related to the geometry of the stepped surfaces and cannot be attributed to an activation energy barrier for adsorption. The observed dependence can be accounted for in a simple model, assigning different activities for H–H bond breaking to the step and terrace sites. For the best fit with the experimental data we find that the activity of a step site is seven times that of a terrace site at normal incidence.

Variation of Surface Reaction Probability with Reactant Angle of Incidence: A Molecular Beam Study of the Asymmetry of Stepped Platinum Crystal Surfaces for H-H Bond Breaking

A molecular beam of H/sub 2/ and D/sub 2/ was used to investigate the angular dependence of the reaction probability for H/sub 2/-D/sub 2/ exchange (H/sub 2/ + D/sub 2/ ..-->.. 2HD) on the Pt(111) and Pt(S ) -(6(111) x (111)) surfaces. On the stepped surface, a marked increase in the production of HD is observed when the beam of reactants strikes the open side of the step structure. The Pt(111) surface exhibits a smooth decrease in HD production from normal incidence to grazing angles.

Kinetics of the Homogeneous Exchange Reaction: NH3 +D2→NH2D +HD. Single-Pulse Shock-Tube Studies

The homogeneous exchange reaction between ammonia and deuterium was studied in a single-pulse shock tube over a wide range of compositions and initial pressures within the 1150–1450°K temperature range. The rate of production of HD in the early stages of the reaction, in the composition range 0.67–4% NH3 and 0.67–4% D2 in argon is given by d[HD]/dt = kb[Ar]0.38[NH3]0.61[D2]1.01, where kb = 1013.0 ± 0.3exp[−(37.2 ± 1.0) × 103/RT]cc mole−1·sec−1. The contribution of a chain mechanism to the exchange process was ruled out. A mechanism based on vibrational excitation of the deuterium molecule to a critical vibration level as a slow step prior to the atom switching step is proposed.

The relationship between nitrogen fixation and the production of HD from D2 by cell-free extracts of soya-bean nodule bacteroids.

1. Cell-free extracts prepared from soya-bean nodule bacteroids produced HD from D(2) in the presence of dithionite, an ATP-generating system and nitrogen. 2. Crude extracts of bacteroids or of Azotobacter vinelandii showed some background D(2) exchange when any one of these was omitted. 3. Partial purification of bacteroid extracts diminished this background activity and gave increased D(2) exchange and nitrogen fixation. 4. Although increasing pN(2) stimulated both reactions, the apparent K(m) (N(2)) for nitrogen fixation was much higher than the apparent K(m) (N(2)) for D(2) exchange when partially purified bacteroid extracts were used. 5. Carbon monoxide was a competitive inhibitor of nitrogen fixation by partially purified bacteroid extracts, but D(2) exchange was inhibited in a non-competitive fashion. 6. These results are discussed in relation to the possible existence of enzyme-bound intermediates of nitrogen fixation.

CHARGE TRANSFER IN THE RADIOLYSIS OF BINARY HYDROCARBON MIXTURES

The radiolysis of dilute solutions of ethane-dε, propane-d8, and n-butane-d10 in liquid hydrocarbons at 195 °K results in the production of D2 and HD in amounts which are determined by the relative ionization potentials of solvent and solute. Solvents of higher ionization potential enhance the production of D2 and HD from deuterated solutes of lower ionization potential. When the ionization potentials are in the reverse order the yields are diminished. This solute–solvent interaction, which is ionic in nature, is a general phenomenon in the radiolysis of mixtures of saturated hydrocarbons in the liquid phase and is consistent with charge transfer between solvent and solute.

Vacuum-Ultraviolet Photolysis of Ethane at High Temperature

The rates of production of HD in the photolysis of C2H6+C2D6 at 1470 and 1236 Å at temperatures sufficiently high to eliminate internal scavenging have been used as a measure of the relative importance of molecular elimination and atomic elimination processes. This, together with complete product analysis including isotopic determinations, gives the following relative weights for the primary processes 1470 Å1236 ÅC2H6*→H2+C2H4†1.001.00C2H6*→2H+C2H40.150.88C2H6*→CH4+CH20.020.50.The probability of dissociation of C2H4† into H2 and C2H2 increases relative to collisional stabilization by a factor of about 2 when the energy of the exciting photon is increased from 1470 to 1236 Å.