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121.
Ni boracite crystals with the general formula Ni3B7I1—x(OH)xO13 have been prepared by hydrothermal synthesis. The experimental conditions are given along with some characteristics of the crystals obtained. 相似文献
122.
123.
Samuel Noirault Eric Quarez Yves Piffard Olivier Joubert 《Solid State Ionics》2009,180(20-22):1157-1163
Ba2(In1 − xMx)2O5 − y / 2(OH)y□1 − y / 2 (y ≤ 2; M = Sc3+ 0 ≤ x < 0.5 and M = Y3+ 0 ≤ x < 0.35) compounds were prepared by reacting Ba2(In1 − xMx)2O5 phases with water vapor. This reaction is reversible. Analyses of the hydration process by TG and XRD studies show that the thermal stability of hydrated phases increases when x increases and that the incorporation of water is not a single-phase reaction inducing either a crystal system or space group modification. Fully hydrated (y = 2) and dehydrated (y = 0) samples have been stabilized at room temperature and characterized for all compositions. In wet air, all phases show a proton contribution to the total conductivity at temperatures between 350 and 600 °C. At a given temperature, proton conductivity increases with the substitution ratio and reaches at 350 °C, 5.4 10− 3 S cm− 1 for Ba2(In0.65Sc0.35)2O4.2□0.2(OH)1.6. 相似文献
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126.
Boulet B Joubert L Cote G Bouvier-Capely C Cossonnet C Adamo C 《The journal of physical chemistry. A》2006,110(17):5782-5791
An experimental and theoretical study on the conformational behavior of the 1,3,5-OMe-2,4,6-OCH(2)CONHOH-p-tert-butylcalix[6]arene has been carried out. In particular, semiempirical (AM1) and density functional theory (DFT) calculations have been performed in order to identify the possible conformers. The obtained results show that the cone structure is the most stable conformer at any level of theory, even if significant differences have been obtained for the other species. The inclusion of solvent effect, through a continuum model, also points out the relevant role played by the solvent in the stabilization of the cone structure in solution. These latter results have been confirmed by NMR experiments, which clearly show the presence of only the cone conformer in a polar solvent, such as DMSO. Finally, (1)H and (13)C NMR spectra on model systems, i.e., two successive phenol rings (Ar(1)-CH(2)-Ar(2)), have been computed at the DFT level and compared with the experimental spectra of the complete molecule. The results show an overall good agreement with the experimental data, thus leading to an unambiguous assignment of the experimental spectra. 相似文献
127.
Joubert J Fleurat-Lessard P Delbecq F Sautet P 《The journal of physical chemistry. B》2006,110(14):7392-7395
The knowledge of the properties of gamma-alumina is of great importance in order to control its surface for numerous applications. We investigate the kinetic behavior of the hydrated alumina (110) surface toward water desorption: the minimum energy path is presented for successive desorption steps starting from the completely hydrated surface toward the dehydrated one. It appears that water desorption is a non activated process. A kinetic model is proposed based on an extension of the Eyring theory. This model is a useful tool to understand the evolution of water coverage during the pretreatment of alumina. It is then used to model temperature programmed desorption experiments for various heating rates. The shape of the desorption curve is qualitatively reproduced, and the differences between theory and experiments are discussed. 相似文献
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129.
Let G = (V, E) be a graph. A set S í V{S \subseteq V} is a total restrained dominating set if every vertex is adjacent to a vertex in S and every vertex of V − S is adjacent to a vertex in V − S. The total restrained domination number of G, denoted by γ
tr
(G), is the smallest cardinality of a total restrained dominating set of G. We show that if δ ≥ 3, then γ
tr
(G) ≤ n − δ − 2 provided G is not one of several forbidden graphs. Furthermore, we show that if G is r − regular, where 4 ≤ r ≤ n − 3, then γ
tr
(G) ≤ n − diam(G) − r + 1. 相似文献
130.