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101.
The nonstoichiometric composition of was measured by means of thermogravimetry in the range of and . The compositional deviation from stoichiometry, , in the hyperstoichiometric Cr2O3+x phase was observed to be smaller than 2 × 10?4, irrespective of temperatures, provided that the hyperstoichiometric Cr2O3+x exists. The existence of the hypostoichiometric Cr2O3?x phase was first established in this study in the region of low oxygen partial pressure below 10?5 Pa. From the oxygen partial pressure dependence of in Cr2O3?x, the defect structure was discussed with the neutral chromium interstitials in the composition near stoichiometry and with the triply charged ones far from stoichiometry. The partial molar enthalpy and entropy of oxygen of Cr2O3?x showed the complex compositional dependences, suggesting the change of the type of the predominant defect. 相似文献
102.
The heat capacity of U3O8−z with various O/U ratios was measured in the range from 250 to 750 K, and λ-type heat capacity anomalies were found in each sample. The transition temperatures were 487 and 573 K for UO2.663, 490 and 576 K for UO2.656 and 508, 562 and 618 K for UO2.640. The entropy changes of the transitions were 0.44 and 0.39 J K−1mol−1 for UO2.663, 0.58 and 0.47 J K−1mol−1 for UO2.656 and 0.62, 0.51 and 0.25 J K−1mol−1 for UO2.640, increasing as O/U decreases. The enthalpy change due to the transition varied linearly with the transition temperature except for UO2.640, showing the presence of the same mechanism of phase transition among the samples with various O/U ratios. The mechanism of the phase transition was discussed on the assumption that the transition is originated from the order-disorder rearrangement of U5+ and U6+ with a consequent displacement of atoms, similarly to the case of U4O9−y. 相似文献
103.
The vapor pressures over nonstoichiometric NbO2 ± x(s) (1.972?2.037) were measured by mass-spectrometric method in the temperature range 1958–2326 K. The congruently vaporizing composition in the NbO2 ± x phase was determined to be stoichiometric NbO2.000 from the composition dependence of the total vapor pressures. The partial pressures of oxygen were calculated as a function of temperature and O/Nb composition from the partial pressures of the gaseous species NbO2(g) and NbO(g) over nonstoichiometric NbO2 ± x, from which the partial molar enthalpies and entropies of oxygen were calculated as a function of O/Nb composition. The composition dependence of the partial molar enthalpy and entropy obtained suggested the existence of some kind of short-range ordering in the nonstoichiometric NbO2 ± x(s) phase. The enthalpies of formation of nonstoichiometric NbO2 ± x(s) were also determined as a function of composition by combining the partial molar enthalpies of oxygen with the enthalpy of formation of stoichiometric NbO2.00(s). The phase diagram around NbO2 ± x at high temperatures was determined from the vaporization study. 相似文献
104.
Okabayashi A Wakai S Kanao T Sugio T Kamimura K 《Journal of Bioscience and Bioengineering》2005,100(6):644-652
Four acidophilic bacteria (YARDs1-4) were isolated from an acid rock drainage (ARD) from Yanahara mine, Okayama prefecture, Japan. The physiological and 16S rDNA sequence analyses revealed that YARD1 was closely affiliated with Acidithiobacillus ferrooxidans, YARD2 was an Acidiphilium-like bacterium, and YARD3 and YARD4 were sulfur-oxidizing bacteria with a relatively close relationship to A. ferrooxidans in the phylogenetic analysis. A molecular approach based on the construction of a 16S rDNA clone library was used to investigate the microbial population of the ARD. Small-subunit rRNA genes were PCR amplified, subsequently cloned and screened for variation by a restriction fragment length polymorphism (RFLP) analysis. A total of 284 clones were grouped into 133 operational taxonomic units (OTUs) by the RFLP analysis. Among them, an OTU showing the same RFLP pattern as those of the isolates from the ARD was not detected. The phylogenetic analysis based on the 16S rDNA sequences from 10 major OTUs and their close relatives revealed that 4 OTUs containing 32.1% of the total clones were loosely affiliated with Verrucomicrobia, 2 OTUs containing 6.6% of the total clones were loosely affiliated with Chloribi, and other OTUs were affiliated with Actinobacteria, Nitrospirae, and beta-Proteobacteria. 相似文献
105.
Male Fischer 344 rats were subcutaneously injected with azoxymethane (AOM) twice weekly at a dose of 15 mg/kg and were fed with freeze-dried (FD) samples of beer brewed without hops (non-hops beer), beer with hops at 4 times the amount of regular lager beer (x 4-hops beer), and isomerized hop extract (IHE) for the whole experimental period (I/PI) or for the post-initiation period (PI) only. Feeding FD beer samples at a dose of 1% significantly decreased the number of aberrant cryp foci (ACF) in the PI protocol over five weeks.x4-hops beer showed stronger inhibitory effects on the development of the numbers of aberrant crypts per focus and large ACF with four or more crypts than non-hops beer. Feeding IHE to rats at a dose of 0.01% or 0.05% in either the I/PI or PI experiment significantly reduced the numbers of ACF. Prostaglandin E2 (PGE2) levels in colonic mucosa of AOM-treated rats were significantly reduced by feeding of IHE. PGE2 production induced by lipopolysaccharide/interferon-gamma (LPS/IFN-gamma) in RAW264.7 cells was also reduced by treatment with IHE and isohumulone in a dose-dependent manner. These observations suggest that isohumulones show chemopreventive effects on ACF formation in rat colon by inhibiting the production of PGE2. 相似文献
106.
107.
The deposition of chlorophyll-a monolayers onto an SnO2 optically transparent electrode was studied in relation to the deposition ratio. The values of the deposition ratio, which were approximately 0.95 for the upward movement and very small but non-zero for the downward movement, suggest that the multilayers prepared are Z-type films containing a small fraction of the Y-type component corresponding to the non-zero value. This is consistent with the photo- electrochemical behaviour of the pigmented electrodes which is markedly dependent on the deposition ratios, indicating structural inhomogeneity or imperfection of the multilayers. 相似文献
108.
The high temperature transition in U4O9 has been studied by electrical conductivity measurements and X-ray diffraction. From the electrical conductivity measurements, a similar variation of log σ with reciprocal temperature to that in the transition range near room temperature is observed in the temperature range from about 300 to 800°C. Like the low temperature transition, a small lattice contraction is also observed in that temperature range by means of X-ray diffractometry, and the transition temperature increases from 530 to 620°C with increasing O/U ratio. After the transition the intensity of superlattice reflections increases, but that of superlattice reflections disappears. The mechanism of this high temperature transition is considered to be a second-order transition of the order—disorder type based on the configurational change of U4+ and U5+ with the shift of some portions of the lattice oxygen atoms from the lattice sites to the interstitial positions. The phase diagram of U4O9 is presented on the basis of the electrical conductivity and X-ray data. 相似文献
109.
110.