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1.
2.
Photoinduced Formation of Small Gold Particles in Silica Gels 总被引:2,自引:0,他引:2
AuCl− 4 ions in sol-gel-derived silica gels (Au/silica gels) were photoreduced by ultraviolet light irradiation at room temperature. In the presence of ethylene glycol in the silica gels, small Au particles were effectively formed by the irradiation. When the storage temperature of the gels was increased in the dark after the irradiation, the surface plas-mon resonance absorption peak of the Au particles was shifted to longer wavelengths, indicating that the Au particles became large. At a storage temperature below 9°C, Au particles could not be observed in the silica gels. The apparent activation energy of Au particle formation was estimated to be 17. 3 kcal·tmol−1 . 相似文献
3.
Yoshihiro Iida Toshikatsu Tsuyuki Takao Mashima Takeo Takashima Kunito Okuyama 《亚洲传热研究》2002,31(1):28-41
This paper presents a series of experimental results on a passive augmentation technique of boiling heat transfer by supplying solid particles in liquid. A cylindrical heater 0.88 mm in diameter is placed in saturated water, in which a lot of mobile particles exist, and the nucleate and film boiling heat transfer characteristics are measured. Particle materials used were alumina, glass, and porous alumina, and the diameter ranged from 0.3 mm to 2.5 mm. Particles are fluidized by the occurrence of boiling without any additive power, and the heat transfer is augmented. The maximum augmentation ratio obtained in this experiment reaches about ten times the heat transfer coefficient obtained in liquid alone. The augmentation ratio is mainly affected by the particle material, diameter, and the height of the particle bed set at no boiling condition. The augmentation mechanism is discussed on the basis of the experimental results. © 2001 Scripta Technica, Heat Trans Asian Res, 31(1): 28–41, 2002 相似文献
4.
Masami Ikeda Susumu Fukumoto Hiroshi Takao Shinya Ohtsuka Eiichi Haginomori Masayuki Hikita 《Electrical Engineering in Japan》2002,141(4):16-24
This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043 相似文献
5.
Theoretical analysis based on the calculation of phase diagrams was employed for Fe-Si-Co and Fe-Si-Al ordering systems to
clarify the necessity for the occurrence of phase separation in Fe-base ternary ordering systems. The free energy of Fe-base
ternary ordering alloys where B2 and D03 ordered structures are formed is evaluated statistically using a pairwise interaction approximation up to second nearest
neighbours, taking into account not only the atomic interaction but also the magnetic interaction, based on the Bragg-Williams-Gorsky
model. The calculated phase diagrams are consistent with the experimentally obtained ones. The phase diagram calculation in
this work is useful to predict the equilibrium states of the ternary ordering systems. The phase separation in ordering alloys
is caused by the contribution of excess free energies due to ordering. The influences of ferromagnetism on the two-phase regions
are also demonstrated. 相似文献
6.
Shingo Hirano Akio Kawabata Masaru Yoshinaka Ken Hirota Osamu Yamaguchi 《Journal of the American Ceramic Society》1995,78(5):1414-1416
A compound denoted as (Ce0.75 Zr0.25 )O2 (Ce, ZrO8 ) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C. 相似文献
7.
N Nishioka T Kawabata KH Minagawa M Nakamura A Oshima Y Mochizuki 《Canadian Metallurgical Quarterly》1996,43(6):434-445
The purpose of this study was to evaluate the short-term effect of a smoking prevention program for Japanese elementary school-children in the fifth and sixth grades. The program was developed with concepts found in the Know Your Body Program and the conclusions of a National Cancer Institute-convened Expert Advisory Panel, and focused on teaching about the short-term effects of smoking and on resistance to social pressures to smoke. The study was conducted with a quasi-experimental design. An intervention group (52 boys and 54 girls) received three sessions for both the fifth grade in 1992 and the sixth grade in 1993. Moreover, the intervention group received a pre-test before the first session and a post-test after the third session in each grade. A comparison group (102 boys and 91 girls) received the same tests at the same time as the intervention group, but did not receive any program on smoking prevention. The short-term effect of the program were evaluated using the results of the pre-test in the fifth grade and of the post-test in the sixth grade in both groups. The results were as follows: 1) Remarkable short-term effects of the intervention were seen in respect to awareness of the importance of not smoking in girls, and also in the knowledge of the short-term effects of smoking in both sexes. 2) The intervention was not effective with respect to intention to smoke at the age of 20 and self-efficacy of refusing to smoke in both sexes. 3) The short-term effects were not clear in the smoking behavior in both sexes because the rates of ever smokers and of monthly smokers were almost the same for two years between the intervention group and the comparison group. 4) The smoking behaviors of children, their parents and their best friends had little influence on the results of the post-test in the sixth grade. 相似文献
8.
The objectives of this paper are to quantify the effect of Marangini convection on the absorption performance for the ammonia–water absorption process, and to visualize Marangoni convection that is induced by adding a heat transfer additive, n-octanol. A real-time single-wavelength holographic interferometer is used for the visualization using a He–Ne gas laser. The interface temperature is always the highest due to the absorption heat release near the interface. It was found that the thermal boundary layer (TBL) increased faster than the diffusion boundary layer (DBL), and the DBL thickness increased by adding the heat transfer additive. At 5 s after absorption started, the DBL thickness for 5 mass% NH3 without and with the heat transfer additive was 3.0 and 4.5 mm, respectively. Marangoni convection was observed near the interface only in the cases with heat transfer additive. The Marangoni convection was very strong just after the absorption started and it weakened as time elapsed. It was concluded that the absorption performance could be improved by increasing the absorption driving potential (xvb−xvi) and by increasing the heat transfer additive concentration. The absorption heat transfer was enhanced as high as 3.0–4.6 times by adding the heat transfer additive that generated Marangoni convection. 相似文献
9.
10.
J Tsutsui K Kadomatsu S Matsubara A Nakagawara M Hamanoue S Takao H Shimazu Y Ohi T Muramatsu 《Canadian Metallurgical Quarterly》1993,53(6):1281-1285
Midkine (MK) and heparin-binding growth-associated molecule/pleiotrophin form a new family of heparin-binding growth/differentiation factors. We studied MK gene expression in human tumors. In normal human reference tissues, MK was highly expressed in the mucosal tissue of the small intestine, moderately in the thyroid, weakly in the tissues of the lung, colon, stomach, kidney, and spleen, and not at all in the liver. All of 6 surgically removed specimens of Wilms' tumor highly expressed MK. Also, a moderate to intense level of MK expression was noted in the majority of surgically removed hepatocellular carcinomas. The MK mRNA level was analyzed in a number of cultured and nude mice-transplanted lines of human tumors. In stomach, colon, pancreatic, lung, and esophageal carcinomas, a moderate to high level of MK expression was found in the majority of them. These results suggest an important role of MK in the development and/or biological behavior of tumors and raised a possibility to use MK as a diagnostic marker. Heparin-binding growth associated molecule/pleiotrophin mRNA was low or scarcely detectable in samples analyzed thus far except for significant levels of the expression that were observed in PA-1 teratocarcinoma cells and in some surgical specimens of Wilms' tumor. 相似文献