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121.
122.
Sn(II)1.2(Nb(V)1.6Sn(IV)0.4)O6 pyrochlore precursor was oxidized at temperature of the range 573–973 K in 1% O2/Ar and O2 gases for various periods of time. Two kinds of novel metastable phases with a composition of Sn(IV)0.6(Nb(V)0.8Sn(IV)0.2)O3.6 could be synthesized. Further, the other novel metastable phase with the same composition was found as a phase contained. One of the metastable phases was the cubic κ-CeZrO4 related-type possessing the fluorite-related structure, which was formed by the cation diffusionless insertion of the oxygen atom into original oxygen vacant site of the pyrochlore-type structure. Another was an orthorhombic α-PbO2 related-type possessing a cation ordered arrangement unlike a well known NiWO4 structure. The other was the rutile related-type possessing a cation ordered arrangement. Appearance of the two latter metastable phases could be attributed to the displacement of the oxygen stacking in the κ-CeZrO4 related-type phase without cation redistributions. The appearance mechanisms were analogous to the well known transformations for AX2 compounds among rutile-type, α-PbO2-type, and fluorite-type phases under high pressure and its release. The dependence of the appearance of these novel metastable phases on oxygen partial pressure and temperature has been discussed in terms of the driving forces and energy barriers for reactions.  相似文献   
123.
A new method based on the Coanda effect for self oscillation of a circular jet bounded by rectangular enclosure is suggested. The experiments in both air and water reveal regions of stable oscillation wherein relationships are obtained between the Strouhal number and the shape factor of the channel. This oscillation method can also be used to mix different liquids in a vessel. For such applications, an improvement of mixing by oscillation is shown by means of a residual concentration diagram for a salt solution.  相似文献   
124.
Data mining using experimental data and information generated from theoretical calculations is proposed to study dye-sensitized solar cells, which are complex systems. This method led to new knowledge about the influence of imidazole derivatives as additives in an electrolytic solution on the cell performance. It was found that the solar energy conversion efficiency is strongly correlated to the Mulliken charge of the carbon atom at position 4 in the imidazole group. This result indicates that data mining assisted by theoretical calculations should facilitate the rate that cell performance is improved.  相似文献   
125.
Simulation of high speed deformation of copper single crystals   总被引:1,自引:0,他引:1  
Plastic deformation of copper single crystals was simulated by molecular dynamics using an embedded atom potential. The time step of molecular dynamics is on the order of 1 fs which corresponds to ultra high speed deformation. This paper reports the results of tension, bending, and compression tests. On notched tension surfaces, Heidenreich-Shockley partial dislocations formed near the tip of the notch as expected. In the absence of notch, creation of dislocations was quite difficult under tension. On compression surfaces, partial dislocations were generated near the wrinkle of the possibly redundant slip plane.  相似文献   
126.
To induce degradabilities in polymers in response to environmental conditions, the end-modification reactions of poly(α-methylstyrene) derivatives were carried out. When diphenylphosphine chloride was used as a modifier for the living end of para-substituted PMS, the coupling efficiency was ca. 50%. 2-Phenylallyl halide derivatives such as 2-phenylallyl bromide, 2-(4-tolyl)allyl bromide, and α-trifluoromethylstyrene were found to be suitable end-modification agents. For example, ω-2-phenylallyl PMS was prepared with almost quantitative functionality by the reaction of the living PMS with 2-phenylallyl bromide. In a similar way, ω-3,3-difluoro-2-phenylallyl and ω-2-(4-tolyl)allyl PMS derivatives were synthesized. Based on thermogravimetric analysis, onset of the degradation temperature of the end-modified PMS derivatives decreased in the following order: ω-hydrogen- > ω-3,3-difluoro-2-phenylallyl- > ω-2-phenylallyl- > ω-2-(4-tolyl)allyl-PMS. Actually, the onset temperature of ω-2-(4-tolyl)allyl-PMS derivatives was 50°C lower than that of ω-H-PMS derivatives. These results indicate that the active species is produced effectively at the end unsaturated bond, which initiates the depolymerization of the polymer at rather low temperatures. Ionic degradation of these polymers was also investigated using butyllithium as an anionic initiator and methanesulfonic acid as a cationic initiator. Tendencies similar to the thermal degradation were observed. Therefore, it is concluded that a 2-phenylallyl substituent at the end of the PMS chain induces effective degradation through several mechanisms such as radical, anionic and cationic depolymerization reactions.  相似文献   
127.
Cytosolic sulfotransferases, which consist of at least three gene families, play a major role in activation and detoxification of both endogenous and exogenous chemicals. We recently purified a rabbit sulfotransferase, AST-RB2, showing high activities to both hydroxysteroids and amines. To characterize this enzyme, a rabbit cDNA library was screened using anti-AST-RB2 antibodies. The isolated cDNA was judged to encode AST-RB2 (ST2A8) based on the amino acid sequences of peptide fragments obtained from purified AST-RB2. The cDNA showed high similarity to other mammalian hydroxysteroid sulfotransferases (ST2) at the amino acid level (58-68%), but low similarity to aryl sulfotransferases (ST1) (less than 37%). The protein expressed in Escherichia coli catalyzed sulfation of typical ST2 substrates. Therefore, ST2A8 was judged to belong to the ST2 family from both its primary structure and substrate specificity. The ST2A8 protein expressed in E. coli clearly differed from rat ST2A1 and ST2A2 on its localization (cytosol/insoluble fraction ratio). ST2A8 had no activity to lithocholate, but showed the highest catalysis on dehydroepiandrosterone and testosterone among the four forms (ST2A1, ST2A2, ST2A3, and ST2A8), indicating a clear difference between ST2A forms in substrate specificity to endogenous chemicals.  相似文献   
128.
Crack-free and highly transparent KTiOPO4 (KTP) thin films were synthesized by the sol-gel method using a homogeneous precursor solution prepared from ("BuO)2-P(O)(OH), Ti(OEt)4, and KOEt in EtOH. Precipitated powders from the solution crystallized directly to KTP above 550°C. Polycrystalline KTP thin films were obtained at 600°C on various substrates. On NdAlO3(100) substrates, KTP films with (101) and (240) preferred orientations were formed at 600°C. KTP films on glass substrates showed a refractive index of 1.75 and an absorption edge of 350 nm. KTP films exhibited the second harmonic generation of the 532 nm light on irradiaton with 1064 nm light.  相似文献   
129.
130.
Consumption of energy was analysed on a Kori-tofu plant which processed 6 tons of soybeans per day, involving 13 operations such as wetmilling, extraction-denaturation of soy protein, coagulation, compression, freezing, thawing, drying and waste-water treatment. Total energy consumption per 1 kg of the dry Kori-tofu was 27·1 MJ of fuel energy (27·9 MJ of exergy) plus 8·3 MJ of electrical energy. Energy-intensive operations were the extraction-denaturation of soy protein and the drying for thermal energy, and the refrigeration and the waste-water treatment for electrical energy. The extraction-denaturation of soy protein consumed twice as much thermal energy as the drying. The waste-water treatment consumed more electrical energy than the whole manufacturing process. Points for energy conservation are discussed.  相似文献   
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