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971.
972.
973.
974.
Oda Y Owa T Sato T Boucher B Daniels S Yamanaka H Shinohara Y Yokoi A Kuromitsu J Nagasu T 《Analytical chemistry》2003,75(9):2159-2165
975.
Yasuhiro Awakura Tetsuji Hirato Akihiko Kagawa Yoshiyasu Yamada Hiroshi Majima 《Metallurgical and Materials Transactions B》1991,22(5):569-574
The kinetics of malachite dissolution in aqueous ethylenediaminetetraacetate (EDTA) solution has been investigated in the
temperature range of 298 to 318 K. The dissolution rate of malachite determined under the present set of experimental conditions
was found to be independent of agitation speed. The dissolution rate increased with increasing EDTA concentration, but leveled
off at higher concentrations. At constant EDTA concentration, an increase in dissolution rate was detected at higher temperatures.
A dissolution mechanism involving Langmuir-type EDTA adsorption was proposed, in which the dissolution rate of malachite is
controlled by the removal of Cu(II)-EDTA complex from the malachite lattice. The proposed mechanism can explain the dependency
of the dissolution rate on EDTA concentration. The activation energies determined at pHs 5, 7.5, and 10 were found to be 51.4,
50.2, and 57.5 kJ mol−1, respectively. The calculated enthalpy changes of EDTA adsorption equilibrium were −43.2, −35.2, and −45.0 kJ mol−1 for pHs 5, 7.5, and 10, respectively. These values are in agreement with the proposed mechanism.
Formerly Graduate Student, Department of Metallurgy, Kyoto University, is
Formerly Professor, is Professor Emeritus, Department of Metallurgy, Kyoto University. 相似文献
976.
The activities of water, α(H2O), in the solution system of H2SO4-CuSO4-H2O were determined by an isopiestic method and those in the solution system of HCl-CuCl2-H2O by a transpiration method, both at 298 K. The activities of H2SO4 and H+ in the solution system of H2SO4-CuSO4-H2O were also determined at 298 K by the emf method. The water activities in both systems obeyed the Zdanovskii rule relatively
well. The α(H2O) experimentally determined in the sulfate system showed a satisfactory agreement with those calculated from the Robinson-Bower
equation, assuming the complete dissociations of H2SO4 and CuSO4, whereas a good agreement between the calculated and experimentally determined α(H2O) for the chloride system was obtained when the formation of Cu(II) chloro-complexes was taken into consideration. The mean
activity coefficients, γ±, of solutes, including H2SO4, HC1, and CuCl2 in these solution systems, were calculated at 298 K by the McKay-Perring method using the activity data. The γ±(H2SO4) values in the solution system of H2SO4-CuSO4-H2O were in good agreement with those determined by the emf method. On the other hand, the γ±(CuSO4) were calculated at the same temperature based upon the Gibbs-Duhem equation using both measured α(H2O) and calculated γ±(H2SO4) values, because of solubility limitations. 相似文献
978.
Hideo Hosono Yasuhiro Sakai Marcelo Fasano Yoshihiro Abe 《Journal of the American Ceramic Society》1990,73(8):2536-2538
Monolithic porous ceramics composed of TiO2 (67 mol%) and SiO2 (33 mol%) were prepared via casting a melt in the Na2 O-CaO-TiO2 -P2 O5 -SiO2 system and subsequent acid leaching of the resultant ceramics which are constituted of NaCaPO4 , TiO2 , and amorphous SiO2 . The median pore diameter and specific surface area of the resulting porous ceramics are approximately 1 μm and 40 m2 , respectively. Amorphous silica surrounds the submicrometer-sized particles of TiO2 acting as a binder and retaining monolithic forms. No significant shrinkage in the pore size occurred upon heating up to 1000°C. 相似文献
979.
Feng-Gang Lin Yuji Takao Yasuhiro Shimizu Makoto Egashira 《Journal of the American Ceramic Society》1995,78(9):2301-2306
Current ( I )-voltage ( V ) characteristics of porous ZnO varistors with different Bi2 O3 content have been investigated in air as well as in H2 -air mixtures in the temperature range room temperature (RT)-600°C. The I-V characteristics measured at RT remained unchanged in the presence of H2 , but the breakdown voltage clearly shifted to a lower electric field in the temperature range 400–600°C. The breakdown voltage decreased with increasing H2 concentration in air. The optimum amount of Bi2 O3 for the largest decrease was found to be 1.0 mol%. Thus, ZnO varistors can be used as a new type of H2 sensor. The results presented in this study also suggest the important role of excess oxygen ions existing at the ZnO-ZnO grain boundaries in developing the Schottky barrier as well as in the H2 -sensing mechanism of the varistors. 相似文献
980.
To clarify the causal relationship between spontaneous recanalization of the occluded cerebral artery and development of hemorrhagic infarction, 15 patients with internal carotid or middle cerebral arterial axis occlusion were submitted to consecutive lumbar punctures and follow-up cerebral angiography. Consequently, six of seven recanalized patients had sanguineous cerebrospinal fluid (CSF) on the second or third day after ictus, while only one of eight non-recanalized patients had bloody CSF. It was strongly suggested that recanalization might have an initimate relationship with the development of hemorrhagic infarction. 相似文献