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土成, 昭弘 ; 保木井, 利之 ; 下林, 修 ; 金岡, 千嘉男
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In a permeable MgO ceramic containing TiO_2 and Al_2O_3 as matrix MgO ・ Al_2O_3-2MgO・TiO_2 solid solutions were detected
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and no Al_2O_3・TiO_2 was observed. Therefore, the solid state reaction among MgO, TiO_2 and Al_2O_3 with excess MgO was studied at various firing temperatures. The formation mechanism of MgO・Al_2O_3-2MgO・TiO_2 solid solutions was studied from the results of interface reactions between MgO-TiO_2 and MgO-Al_2O_3. MgO・Al_2O_3-2MgO・TiO_2 solid solutions were detected at 1573-1673 K and increased with the firing temperature. 2MgO・TiO_2 was formed in the system MgO-TiO_2, but was not produced in the system MgO-TiO_2-Al_2O_3, because the amount of Mg diffusion at the interface of aggregate and matrix additives was not enough due to the large aggregate size of MgO. MgO・Al_2O_3 and 2MgO・TiO_2 formed at the interface between MgO-TiO_2 and MgO-Al_2O_3 decreased with the firing time at 1873 K. On the other hand, MgO・Al_2O_3-2MgO・TiO_2 solid solutions increased. Mg was recognized in the matrix without addition of MgO as a matrix. Al diffused in the layer of MgO-TiO_2, in opposition Ti diffused in the layer of MgO-Al_2O_3 by EPMA analysis. From the above results, the formation mechanism of a MgO・Al_2O_3-2MgO・TiO_2 solid solution was proposed; (1) Mg diffusion at the interface of MgO aggregate and matrix additives, (2) formation of MgO・TiO_2 and MgO・Al_2O_3, (3) formation of 2MgO・TiO_2 due to the reaction with MgO・TiO_2 and MgO, (4) reaction of the solid solution with MgO・Al_2O_3 and 2MgO・TiO_2. In the reactions between MgO・TiO2 and MgO-Al_2O_3 the product layer of MgO・Al_2O_3-2MgO・TiO_2 solid solution increased as the firing time increased. The diffusion coefficient of Mg was about 4.8×10^<-7>(cm^2/s), in a good agreement with that of Mg which was reported.
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谷野, 淳
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飯島, 隆広 ; 水野, 元博 ; 須原, 正彦 ; 遠藤, 一央
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金沢大学大学院自然科学研究科物質情報解析<br />A method using the 2H-NMR spectra was shown to be useful to study the solid state physics in d
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iamagnetic and paramagnetic compounds and in crystals having a modulated structure. The spectra and T1 of NMR in solids were measured for [M(H2O)6][AB6] crystals to investigate the static and dynamic structure of H2O and [M(H2O)6]2+ as well as the dynamics of the electron spin in the paramagnetic M2+ ion. The physical properties of [M(H2O)6] [AB6] were found to be as follows: (1) The spin-lattice relaxations of the electron spin of M2+ in [M(H2O)6] [SiF6] (M2+ = Fe 2+ , Co2+ , Ni2+) are dominated by the Orbach process, the Orbach process, and the Raman process, respectively. The spin-lattice relaxation of the electron spin of Cu2+ in [Cu(H 2O)6][PtCl6] is caused by jumping between the Jahn-Teller configurations. (2) In [Cu(H2O)6] [PtCl 6], H2O and [Cu(H2O)6]2+ undergo 180° flips and jumping between the different Jahn-Teller configurations, respectively. A weakening of the hydrogen bond O-H⋯Cl upon deuteration results in a lowering of the transition temperature. (3) In [M(H2O)6][SiF6], H2O and [M(H 2O)6]2+ undergo 180° flips and reorientation about the C3, axis, respectively. The order-disorder transition is closely related to a freezing of this reorientation. (4) By elongation of [M(H2O)6]2+ along the C 3 axis, the mobility becomes higher. (5) The disorder of [Fe(H 2O)6]2+ in the high-temperature phase of [Fe(H2O)6][SiF6] is dynamic. Rotational modulation of [Mg(H2O)6]2+ along the C 3 axis exists in the incommensurate phase of [Mg(H2O) 6] [SiF6].
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加野, 軒作 ; 植竹, 厚子 ; 清水, 栄 ; 新田, 啓一 ; 山本, 譲
概要:
Metabolism of 6-methyl-2-thiouracil was studied in rats by using ^<14>C-labeled compound. Following the oral administration of 6-methyl-2-thiouracil [2-^<14>C] (490 mg/kg), the about 68% of the administered radioactivity was excreted in
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urine, 27% in feces, and 1.2% in respiratory CO_2 within 72 hr. After oral ingestion of the radioactive compound, radioactive substances excreted in urine after 48 hr were 6-methyl-2-thiouracil, 6-methyl-uracil, 6-methyl-2-methylthiouracil, 6-methyl-4-oxo-pyrimidine, 2-amino-6-methyl-4-oxopyrimidine, and urea which were present in about 46.2,9.1,1.6,1.8,0.2,and 0.8% of total radioactivity in the urine, respectively. In in vitro tests using rat liver slices, radioactivity was also detected in 5,6-dihydro-6-methyluracil along with the above metabolites.
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Ialnazov, Dimiter
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早川, 和一
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