Methanol synthesis from carbon dioxide at atmospheric pressure over Cu/ZnO catalyst. Role of methoxide species formed on ZnO support

Methanol synthesis from CO₂ and H₂ was carried out over a Cu/ZnO catalyst (Cu/Zn = 3/7) at atmospheric pressure, and the surface species formed were analyzed by diffuse reflectance FT-IR spectroscopy and temperature programmed desorption method. Two types of formate species and zinc methoxide were formed in the course of the reaction. Zinc methoxide was readily hydrolyzed to methanol. H₂O formed through the reverse water gas shift reaction was suggested to be involved in the hydrolysis of zinc methoxide.     

Many-Body Analysis of the Hess-Fairbank Effect in One-Dimensional Bose-Einstein Condensates with Attractive Interactions

No Heading In terms of the many-body energy spectrum obtained by a diagonalization of Hamiltonian, we discuss the Hess-Fiarbank effect in an attractive Bose-Einstein condensate on a one-dimensional ring. Depending on the strength of interaction and the rotational frequency of the container, there exist two characteristic features in the spectrum. We argue that the existence of a regime of a huge number of low-lying levels causes the smearing of the plateau of the quantized circulation in contrast to conventional superfluids with repulsive interaction.PACS numbers: 03.75.Hh, 03.75Lm     

Adsorption of carbon dioxide in plasma polymers prepared from silicon compounds and carbon dioxide separation membrane

Summary Three silicon compounds, dimethyldimethoxysilane (DMDMOS), decamethylcyclopentasiloxane (DMCPS), and 1,1,3,3-tetramethyldisiloxane (TMDSO), were plasma-polymerized, and the solubility coefficient and the permeation coefficient of carbon dioxide and nitrogen gas were determined. The permeation properties of the deposited films were discussed. The plasma polymers formed from DMDMOS, DMCPS, and TMDSO showed preferential solubility for carbon dioxide. The solubility coefficient of carbon dioxide was closely related to the concentration of Si-(O-)₄ moieties in the plasma polymers. However, these plasma polymers showed no selective permeation of carbon dioxide. The diffusion process rather than the solution process controlled the permeation of carbon dioxide across the plasma polymers. Plasma polymers formed from silicon compounds, if the polymers are less cross-linked, are expected to be a good material for CO₂-selective membrane.     

Investigation of BWR LOCA at ROSA-III — Effect of break configuration on system transients

The ROSA-III test facility is a volumetrically scaled ( ) BWR/6 system with an electrically heated core to study the thermal-hydraulic response during a postulated loss-of-coolant accident (LOCA).Six loss-of-coolant experiments with a break area of 15%, 50% or 200% at the main recirculation pump inlet line were conducted at the ROSA-III test facility with a high pressure core spray failure. A sharp-edged orifice or a long throat nozzle was used as a break plane. It was found in the experiments that the break flow differences between the orifice and the nozzle break configurations with the same flow area were observed only in the subcooled break flow region. Subcooled break flow rate through the orifice was much larger than that through the nozzle. The break configuration difference had little influence on the other system responses, especially on the peak cladding temperature. The applicability of the test results to a BWR/6 has been confirmed through analyses of the 15% break ROSA-III LOCA experiments and BWR/6 LOCAs by using RELAP4/MOD6/U4/J3 code. The experimental results of the ROSA-III LOCA experiments were calculated well by the code, and the same trends were calculated in the BWR analyses.     

Electron spin resonance study of defects in CVD-grown 3C-SiC irradiated with 2MeV protons

Electron spin resonance (ESR) was used to study defects induced by 2MeV-proton irradiation in cubic silicon carbide (3C-SiC) epitaxially grown on Si substrates by chemical vapor deposition. A new ESR signal labeled T5 was observed at temperatures lower than ≈100 K in Al doped, p-type 3C-SiC epilayers irradiated. The T5 signal has anisotropic g-values of g₁ = 2.0020 ± 0.0001, g₂ = 2.0007 ± 0.0001,and g₃ = 1.9951 ± 0.0001. The principal axes of the g-tensor were found to be along the 〈100〉 directions, indicating that the T5 center has D₂ symmetry. Isochronal annealing of the irradiated epilayers showed that the T5 center was annealed at temperatures around 150° C. A tentative model is discussed for the T5 center.     

High magnesium concentration inhibits ligand-stimulated calcium influx and hormone secretion in rat pituitary lactotropes with involvement of intracellular free magnesium

The effects of extracellular magnesium concentration ([Mg2+]ex) on thyrotropin-releasing hormone (TRH)-stimulated intracellular free calcium mobilization and prolactin secretion were investigated concomitantly with measurement of the intracellular free magnesium concentration ([Mg2+]i). TRH-stimulated intracellular free calcium mobilization was significantly inhibited when the medium was replaced by high Mg2+ medium ([Mg2+]ex = 10 mM) in normal Ca2+ medium. The inhibitory effects of high Mg2+ became apparent concomitantly with an increase in [Mg2+]i from 0.7 to 1.3 mM. High Mg2+ significantly inhibited TRH-induced PRL secretion in a dose-dependent manner in normal Ca2+ medium. TRH-stimulated inositol triphosphate (IP3) production was rather augmented by the replacement with high Mg2+ medium. In summary, high Mg2+ inhibits Ca2+ influx stimulated by TRH in the rat pituitary lactotropes, possibly with the involvement of [Mg2+]i increase. These results have general importance in relation to high Mg(2+)-induced suppression of the biological functions of cells.     

Equilibrium state and crystal growth of (BEDT-TTF)2I3

The equilibrium state and crystal growth of (BEDT-TTF)₂I₃ were investigated. Measurements of the temperature dependence of solubility and analyses of the components in the solution were carried out. The analysis of the solution showed that the crystals decompose into neutral BEDT-TTF and I₂ molecules. As to the polymorphism, it was clarified that the -form is more stable than the -form in the temperature region between 0 and 50 °C. Using these information, we succeed in growing single crystals form BEDT-TTF and I₂ and in control of the crystallizing polymorph. The polymorphic behavior was explained in terms of supersaturation as a driving force of crystal growth.     

Theoretical conformational analysis of tetrapeptide Ac-Cys-Pro-Gly-Cys-NHMe with disulfide linkage

Theoretical conformational analysis was carried out for the acyclic and cyclic tetrapeptides Ac-Cys-Pro-Gly-Cys-NHMe using ECEPP and optimization procedure for investigating the conformational preference of peptides having disulfide linkage. Calculated results indicate that cyclic Ac-Cys-Pro-Gly-Cys-NHMe forms compactly fold conformations with type II β-bend at the Pro-Gly portion, and also show fairly good agreement with experimental results of the NMR spectroscopy for the tetrapeptides having Cys-Pro-Gly-Cys sequence. Received: 26 August 1996/Revised version: 18 September 1996/Accepted: 23 September 1996     

Theoretical conformational analysis of tetrapeptide Ac-Cys-Pro-D-Ala-Cys-NHMe with Disulfide Linkage

Summary. Theoretical conformational analysis was carried out for the acyclic and cyclic tetrapeptides Ac-Cys-Pro-d-Ala-Cys-NHMe using ECEPP and optimization procedure for investigating the conformational preference of peptides having disulfide linkage. Calculated results indicate that cyclic Ac-Cys-Pro-d-Ala-Cys-NHMe forms compactly fold conformations with type II β-bend at the Pro-d-Ala protion, and also show fairly good agreement with experimental results of the NMR spectroscopy for the tetrapeptides having Cys-Pro-d-Ala-Cys sequence. Received: 23 March 1997/Revised: 25 June 1997/Accepted: 4 July 1997     

Surface chlorination of polypropylene film by CHCI3 plasma

Polypropylene films were treated with the CHCI₃ plasma, and their chemical composition was analyzed with XPS and ART IR spectroscopy. The CHCI₃ plasma irradiation made polypropylene films hydrophilic. The advancing contact angle decreases from 95° for the untreated to about 73° for the CHCI₃ plasma-treated films. In the CHCI₃ plasma irradiation, the chlorination occurs, and C? Cl, C? Cl₂, and C? Cl₃ units are formed in the polypropylene films. Simultaneously with the chlorination, unsaturated units (C?C and conjugated C?C units) are formed from dehydrogen chlorination of the chlorinated products, but the oxygen incorporation into the films is low. The CHCI₃ plasma is preferred in chlorination of polypropylene films to the CCl₄ plasma. © 1994 John Wiley & Sons, Inc.