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The influence of intermolecular hydrogen bonding on some physical constants is clearly shown by comparing some thermal data for simple oxamides and thiooxamides.

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Abstract  

The thermally induced structural transformation of a hydrogen-bonded crystal formed from an amphoteric molecule of 6-[2-methoxy-4-(pyridylazo)phenoxy]hexanoic acid MeO was studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction measurement (XRD). Crystal form of the hydrogen-bonded crystal was measured by single crystal four circle diffractometer (Mo-Kα radiation). As a result, the crystal of MeO was stabilized by many C–H⋅⋅⋅O hydrogen bonds, and the C–H⋅⋅⋅O hydrogen bonds were broken by thermal energy reversibly. After transformation the supramolecular architecture was composed of supramolecular polymer including free-rotation pentamethylene main chains.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Jones, A. Sharratt, S. Jackson, R. Griffiths, L. Gladden, F. Robertson, and G. Webb

Abstract  

Details of a novel temperature-programmed reduction technique are described, which allowed nickel oxide/silica catalysts to be reduced with [3H]-hydrogen. In addition to obtaining characteristic reduction profiles for the catalysts it was possible to study hydrogen isotope exchange over the catalysts during the reduction process.

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Low-energy photons produced by the Compton scattering from hydrogen increase the background in the lower-energy region of the gamma-ray spectrum. This results in an increase in the detection limit for trace elements. In multiple photon detection prompt gamma-ray analysis (MPGA), only those elements that simultaneously emit two or more prompt gamma-rays, which have cascade relation and are emitted within a short interval, can be measured. Therefore, the influence of hydrogen can be reduced. In this study, standard polymer and food samples are measured. The hydrogen background is reduced in MPGA.

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The concentrations of hydrogen peroxide formed in the coolant due to radiolysis were studied during THOR operation at 1 MW. The relation between doses and hydrogen peroxide formation in a neutron-gamma mixed field was investigated. The initial concentration was 2.3×10–5 g/ml at the beginning of reactor operation, and then it was increased rather rapidly at the first 9 h. The increasing rate was slowed down till the end of 30 h operation. The maximum concentration of hydrogen peroxide was found to be 4.7×10–5 g/ml, and its decrease followed the exponential curve.

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The fractionation factor of tritium between water and biomoleculeswhich are structured by hydrogen bridges, is found to be around 2. In additionto an intramolecular accumulation, an extra-molecular one is found to be about1.4 in the hydration sheets. During growth of plants (maize), the growth incrementof tritium in non-exchangeable organically bound tritium (OBT) is about 2.4times (140% larger than) the growth increment of hydrogen. The intrinsic growthrate of tritium is about 20 percent larger than that of hydrogen. Tritiumbound in water overtakes its kinetic delay in photosynthetic or metabolicreactions according to the larger mass by the fast established thermodynamicisotope effect of proton-triton exchange.

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Abstract  

The kinetics of the liquid-phase hydrogenation of cinnamyl alcohol over Ir/Al2O3 catalyst (d ≈ 7 nm) was investigated in toluene under mild conditions (T = 25–95 °C, hydrogen pressure = 3–8 bar and cinnamyl alcohol concentration = 0.0075–0.375 M). The kinetic results could be successfully modeled based on the assumption that the Langmuir–Hinshelwood surface reaction between competitively adsorbed cinnamyl alcohol and hydrogen is the rate determining step. The model predicts that cinnamyl alcohol requires two metallic sites to adsorb on with an adsorption constant of 1.4 M−1. The apparent activation energy of the reaction was experimentally determined to be ~26 kJ mol−1.

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Abstract  

The first report is described on the activity, selectivity and diastereoselectivity of magnesium oxide as a catalyst in the liquid and vapor phase modes (LP and VP) of catalytic transfer hydrogenation of 4-t-butylcyclohexanone (t-BuONE) using secondary alcohols as hydrogen donors. An exceptionally high diastereoselectivity (>98%) to trans-4-t-butylcyclohexanol (trans-t-BuOL) in the LP mode of reaction, with almost all hydrogen donors used with MgO, has been observed. This is ascribed to the predominance of the axial attack on the ketone molecule and the reaction irreversibility.

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Abstract  

This paper reports the study of hydrogen and carbon monoxide produced by radiation degradation of N, N-dimethylhydroxylamine (DMHA). The results show that when the concentration of DMHA is between 0.1M–0.5M and the dose is between 10–1000 kGy, the volume fraction of hydrogen is very high and increases with the dose. The volume fraction of hydrogen is little dependent on the concentration of DMHA at lower dose but increases with increasing concentration of DMHA at higher dose. The volume fraction of carbon monoxide is very low.

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Abstract  

The diffusion behavior of hydrogen in the oxide films of zircaloy-4 specimens containing different size of Zr(Fe,Cr)2 precipitates was examined. In the case of the specimen containing fine precipitates, hydrogen diffused uniformly through the zirconium oxide phase. The diffusion coefficient was 2·10−21 m2·s−1 at room temperature and 6·10−19 m2·s−1 at 673 K. The transport rate of hydrogen in the oxide film of the specimen containing coarse precipitates was significantly higher than that of the specimen containing fine ones at both room temperature and 673 K.

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