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排序方式: 共有489条查询结果,搜索用时 31 毫秒
31.
Behavior of pseudo-fission products (Ba, Sr, and Zr) as oxides in UO2 has been investigated by means of high-temperature X-ray diffraction and microprobe analysis. Two identifiable compounds were formed as reaction products in the mixed oxides which initially consisted of UO2, BaO, SrO, and ZrO2 powder. These compounds were present and were identified crystallographically as (Ba, Sr) ZrO3 and (Ba, Sr)UO3 after heat treatment of the powders at 1500°C for 30 min. Both compounds are isostructural with perovskite, CaTiO3, and the lattice parameters of both (Ba, Sr)ZrO3 and (Ba, Sr)UO3 decrease with increasing content of Sr. (Ba, Sr)UO3 is decomposed almost completely at 1800°C while (Ba, Sr) ZrO3 is stable up to 2000°C. The behavior of Ba, Sr, and Zr in fuel under irradiation is discussed. 相似文献
32.
Sulfospinels AB2S4 (A=Mg, Mn, B=Tm, Yb) were treated at 1000°C and 55 kbar for 1h. The X-ray powder diffractions were completely indexed by assuming that the products were isostructural with Th3P4. The results of density measurements showed a good agreement with those calculated from the X-ray data. No magnetic ordering was observed in temperatures down to 77K. 相似文献
33.
Koizumi H Yamamoto T Maki A Yamashita Y Sato H Kawaguchi H Ichikawa N 《Applied optics》2003,42(16):3054-3062
We will briefly review the present status of optical topography and then discuss the method of improving practicality, i.e., the signal-to-noise (S/N) ratio and the spatial resolution in observations of higher-order brain functions. The optimum wavelength pair improved the S/N ratio sixfold for deoxyhemoglobin, and new configurations of light irradiation and detection positions doubled the spatial resolution. We also report on developing application fields of optical topography. This modality will bridge the gap between natural sciences, neuroscience, and pedagogy, and show actual real-time brain activity. 相似文献
34.
Takano Y Koizumi M Takarada R Kamimura MT Czerminski R Koike T 《Journal of molecular graphics & modelling》2003,22(2):105-114
We have investigated a new approach to efficiently find a novel inhibitor against a serine protease (i.e. an activated coagulation factor X, FXa) by using de novo design programs and the X-ray crystal structure of the target enzyme. FXa is a coagulant enzyme that generates thrombin (a serine protease) and participates in both intrinsic and extrinsic coagulation pathways. We adopted multiple copy simultaneous search (MCSS) and CAVEAT linker search techniques, which disclosed a novel FXa inhibitor (T01312) consisting of two binding moieties (the benzamidinyl and adamantyl groups) and a linker unit (the carboxybenzylamine group). The inhibitory activity of T01312 against FXa was determined to be a small K(i)-value of 48nM, which is two orders of magnitude smaller than that against thrombin. An X-ray crystal analysis of T01312 complexed with trypsin (an analogue of FXa) and docking studies of T01312 with trypsin and FXa showed that: (i) the benzamidinyl group is a predominant binding moiety in the anionic pocket (S1 site) with an asparatic acid residue; (ii) a hydrophobic pocket (S4 site) is the binding site of the adamantyl group; (iii) the carboxylate group of the linker contributes to the selectivity for FXa against thrombin. Thus, the combination of the knowledge of the X-ray crystal structure of the target molecule with MCSS and CAVEAT linker search techniques proved to be an effective hit-finding method that does not require the screening of huge compound libraries. 相似文献
35.
The effects of shape and size on the residual stress on the surfaces of silicon nitride/Invar alloy joints have been examined by means of the strain gauge method. The highest residual stress perpendicular to the interface appeared near the corners in the rectangular bond face joint. It was tensile in the silicon nitride and compressive in the Invar alloy. The highest tensile stress in the rectangular bond face joint was larger than that in the circle bond face joint. The larger the diameter of the cylindrical joint used, the larger was the tensile stress induced. The residual stress parallel to the interface was compressive in silicon nitride while that in the Invar alloy was tensile. 相似文献
36.
K. Itatani K. Koizumi F. S. Howell A. Kishioka M. Kinoshita 《Journal of Materials Science》1989,24(7):2603-2609
The agglomeration process of MgO powder derived from Mg (OH)2 was investigated at fixed temperatures of 600, 800, 900 and 1200° C; these temperatures were chosen as representative of four regions, i.e. below 600° C, 650 to 850° C, 850 to 1050°C and 1050 to 1200° C previously reported. At 600° C, coherent crystallites coalesced within the heating time of 60 min; on further heating till 300 min, the primary particles which consisted of crystallites grew rapidly. The original Mg (OH)2 framework or pseudomorphs, composed of minute crystallites and primary particles, still remained in the powder. At 800° C, the pseudomorphs had disintegrated into fragments. The crystallite growth and primary particle growth were accelerated with increasing the heating times beyond 60 min. At 900° C, a further fragmentation of agglomerates occurred with increasing the heating times; the crystallite and primary particle growth in fragments brought about the pore coalescence. At 1200° C, the crystallite and primary particle growth proceeded with the coarsening of pores; on heating beyond 240 min, the crystallites and primary particles grew rapidly due to the entrapment of pores within them. 相似文献
37.
38.
Shiro Koizumi 《Electrical Engineering (Archiv fur Elektrotechnik)》1939,33(3):171-188
Ohne ZusammenfassungEs sei mir gestattet, Herrn Dr. K. Kurokawa, Professor an der Universität Waseda, meinen herzlichsten Dank auszusprechen für das warme und fördernde Interesse an der vorliegenden Arbeit. 相似文献
39.
40.
Chemical deintercalation was investigated on α-NaFeO2 using bromine as oxidizing agent. The product had a composition about Na0.9FeO2 keeping the host layer structure as it was. The crystal lattice was hexagonal and the lattice parameters were , . Mössbauer spectrum showed the presence of Fe4+ in the product. Electrical resistivity was higher than 108Ωcm at room temperature. Na0.9FeO2 decomposed to a mixture of α-NaFeO2 and Fe3O4-like ferromagnetic materials above 130°C. 相似文献