排序方式: 共有32条查询结果,搜索用时 15 毫秒
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Tubular SiO2 -glass membranes with thin, dense SiO2 layers on porous glass supports were prepared via sputtering, using the novel sputtering apparatus for tubular supports. This apparatus had a holder for tubular supports and a rotation mechanism. The sputtering conditions of the membranes were investigated. A support temperature of 573 K was determined to be the best among the temperatures that were selected in our experiments. Scanning electron microscopy observations showed that the membrane surfaces became smooth as the sputtering time increased and had no cracks. The permeances of helium, nitrogen, and CO2 were measured at a temperature of 373 K. The permeances for the membranes were on the order of 10-9 molm-2 s-1 Pa-1 (10-5 cm3 (STP)cm-2 s-1 (cm Hg)-1 ). The ratio of the permeances of helium to nitrogen was similar to the theoretical Knudsen value. These values were much lower than the values that were expected from the dense SiO2 glass. This phenomenon was considered to be attributable to the presence of microcracks during the sputtering deposition. 相似文献
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Silica/poly(butylene succinate-co-adipate) organic–inorganic hybrid biodegradable materials were prepared by the sol–gel method.
Fourier-transform infrared spectroscopy (FT-IR) and Thermogravimetry/differential thermal analysis (TG/DTA) indicated that
the inorganic (SiO2, C6H5SiO3/2) and organic (PBSA) components were well dispersed in the hybrid material. Heat resistant test shows that the hybrid material
was both heat resistant and flexible. The presence of phenyl groups and siloxane network was responsible for the flexibility
and heat resistance. 相似文献
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Koichi Shigeno Yuto Kuraoka Tadashi Asakawa Hirotaka Fujimori 《Journal of the American Ceramic Society》2021,104(5):2017-2029
Densely sintered alumina is produced with a 5 wt% addition of a CuO-TiO2-Nb2O5-Ag2O sintering aid under a firing temperature of only 835°C with a prolonged holding time of 96 hours. The sintered material exhibits a thermal conductivity of 20 W/mK, which is significantly greater than that of conventional low-temperature co-fired ceramic (LTCC) materials (~2-7 W/mK). Additionally, suitable dielectric characteristics are observed, such as a relative dielectric constant εr of 11.3, quality factor–resonant frequency product Q × f of 4700 GHz, and temperature coefficient of resonant frequency τf of −87 ppm/K. The low-temperature densification is revealed to occur mainly in the solid state, before liquid phase formation. Lattice constant measurements, transmission electron microscopy, and energy dispersive spectroscopy reveal an increase in unit cell volume upon densification and the incorporation of Cu2+ and Ti4+ ions into the alumina lattice, which promotes densification. The diffusion speeds of Cu2+ and Ti4+ ions are indirectly affected by Nb and Ag atoms by lowering the additive melting temperature. Therefore, sintering additives with low melting points and elements that incorporate into the lattice of the base material are effective for low-temperature sintering of aluminum-based oxides. 相似文献
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Tomoko Akai Koji Kuraoka Danping Chen Yoshihiro Yamamoto Tatsuya Shirakami Kazuyori Urabe Tetsuo Yazawa 《Journal of the American Ceramic Society》2005,88(10):2962-2965
The leaching behavior of Na from soda–lime–silicate glass was investigated by preparing glass powders with average particle diameters of 53 and 19 μm, and leaching in HNO3 at 90°−140°C. A new theoretical equation for Na leaching from a spherical particle is proposed based on the assumption that a rate-determining process is the three-dimensional self-diffusion of Na in glass. The diffusion constant ( D ) of Na in glass was obtained by fitting the experimental data to a theoretical equation. The values of D and activation energy obtained are comparable to those obtained in other studies on larger particles. 相似文献
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Novel inorganic–organic membranes that contained Ag+ ions as olefin carriers were prepared using sol–gel and dip-coating processes. The permeance of the membranes for nitrogen, helium, ethane (C2 H6 ), and ethene (C2 H4 ) were evaluated using the single-gas permeation method at temperatures of 298, 373, and 423 K. The results showed that the selectivity of the membranes to C2 H4 against C2 H6 increased as the measurement temperature increased, because the decomplexation rate of C2 H4 molecules from Ag+ sites is enhanced by increases in the temperature. Fourier transform infrared spectrophotometry of the hybrid membranes and the performance of the membranes at 373 and 423 K indicated that poly( N -vinylpyrrolidone) (PVP) had a role in increasing the flexibility of the inorganic network and also served as a mediation agent to fix Ag+ ions in the polymer segments, because of the coordination interaction between the Ag+ ions and the PVP. 相似文献
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R Fujiwara T Komori Y Noda T Kuraoka H Shibata K Shizuya S Miyahara M Ohmori J Nomura MM Yokoyama 《Canadian Metallurgical Quarterly》1998,5(6):318-322
The aim of this study was to determine the effects of the long-term application of various fragrances on the suppression of immune response induced by high-pressure stress in mice. The immune response was analyzed based on plaque-forming cell (PFC) count, using mice sensitized with sheep red blood cells. The decreased PFC involving thymic involution induced by high-pressure stress in mice was restored by exposing the stressed mice to tuberose, lemon, oakmoss and labdanum for 24 h following exposure to stress. The decreased PFC and thymic involution from stress were restored by exposure to lemon and oakmoss, but not to tuberose and labdanum when the mice were exposed to those fragrances continuously for 3 weeks before the stress was given, followed by exposure to the same fragrances for 24 h after the stress. The decreased PFC and thymic involution from stress were restored by exposure to lemon and labdanum for 24 h after the stress, but not to tuberose over 3 weeks before the stress was given. These data suggest that the neuroimmunomodulatory effects of fragrances may be affected by tolerance depending on the kinds of fragrances in the case of a long-term application. 相似文献