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排序方式: 共有810条查询结果,搜索用时 728 毫秒
91.
Jun Yoshikawa Yuji Katsuda Naohito Yamada Chikashi Ihara Masaaki Masuda Hiroaki Sakai 《Journal of the American Ceramic Society》2005,88(12):3501-3506
The phase composition, microstructure, and electrical resistivity of hot-pressed AlN ceramics with 0–4.8 wt% Sm2 O3 additive were investigated. The phase composition was approximately consistent with that estimated from the Sm2 O3 –Al2 O3 phase diagram using the amount of added Sm2 O3 and oxygen content of the AlN raw material. When sintered at more than 1800°C, the AlN ceramics with 1.0–2.9 wt% Sm2 O3 additive contained an Sm-β-alumina phase wetting the grain boundaries, and their electrical resistivity considerably decreased to 1010 –1012 Ω·cm. This resistivity decrease was caused by the continuity of the Sm-β-alumina phase with a resistivity lower than that of bulk AlN. 相似文献
92.
Masaaki Takehisa Sueo Machi Hiromasa Watanabe Takashi Ueno Seiichi Takahashi Ryoji Tsuchiya Kanji Otaguro Isao Motoda Yoshio Takasaka Kazukiyo Miyanaga Waichiro Kawakami Kouichi Yamaguchi Takanobu Sugo Hayato Nakajima Terutaka Watanabe Chuhei Hinachi 《应用聚合物科学杂志》1979,24(3):853-864
Radiation-induced bulk polymerization of ethylene was carried out with use of a pilot plant with a 10 liter reactor at pressures of 225–400 kg/cm2, temperatures of 30–95°C, ethylene feed rates of 5–28 kg/hr, and dose rate of 3.8 × 105 rad/hr. Characteristics of the process are mild polymerization conditions and capability of producing medium density polyethylene in powder form. The spacetime yield and molecular weight of polymer were in the range of 3.5 to 13.1 g/liter hr and 2.2 × 104 to 14 × 104, respectively. The space-time yield increased with mean residence time and 2.4 powders of pressure, and decreased with temperature. Molecular weight changed similarly with the reaction conditions. These results were consistent with those of the bench plant experiment and the scale effect was small. Polymer deposit to the reactor wall limited a period of continuous operation of the plant. The amount of deposited polymer was increased with the square of reaction time. The rate of polymer deposit was proportional to polymer concentration and to the cube of pressure. The polymer deposit cannot be solved in the bulk process. 相似文献
93.
Masaaki Nagatsu Takaaki Yoshida Marcel Mesko Akihisa Ogino Takafumi Matsuda Takayuki Tanaka Hirokazu Tatsuoka Kenji Murakami 《Carbon》2006,44(15):3336-3341
The use of graphene layer encapsulated catalytic metal particles for the growth of narrower multi-walled carbon nanotubes (MWCNTs) has been studied using plasma-enhanced chemical vapor deposition and conventional thermal CVD. Ni–C or Fe–C composite nanoclusters were fabricated using the dc arc discharge technique with metal–graphite composite electrodes carrying a current of 100–200 A in a stainless-steel chamber filled with He and CH4 mixture gas at 27 kPa. Nano-sized grains with diameters less than 10 nm were fabricated and deposited on a Si substrate, and were used as a catalyst for MWCNT growth. Structural analyses of the composite nanoclusters and MWCNTs were carried out using transmission electron microscopy. The results show that the diameters of the MWCNTs were reduced from 50–100 nm for a conventional Ni thin film-evaporated Si substrate to a minimum of roughly 2–4 nm in the present study. 相似文献
94.
Hideto Matsuyama Kazuhiro Ohga Taisuke Maki Masaaki Tearamoto Shuji Nakatsuka 《应用聚合物科学杂志》2003,89(14):3951-3955
Microporous cellulose acetate membranes were prepared by a thermally induced phase separation (TIPS) process. Two kinds of cellulose acetate with acetyl content of 51 and 55 mol % and two kinds of diluents, such as 2‐methyl‐2,4‐pentandiol and 2‐ethyl‐1,3‐hexanediol, were used. In all polymer‐diluent systems, cloud points were observed, which indicated that liquid–liquid phase separation occurred during the TIPS process. The growth of droplets formed after the phase separation was followed using three cooling conditions. The obtained pore structure was isotropic, that is, the pore size did not vary across the membrane. In addition, no macrovoids were formed. These pore structures were in contrast with those usually obtained by the immersion precipitation method. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3951–3955, 2003 相似文献
95.
Mahmuda Akter Md. Mostafizur Rahman A. K. M. Atique Ullah Md. Tajuddin Sikder Toshiyuki Hosokawa Takeshi Saito Masaaki Kurasaki 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(4):1483-1493
Silver nanoparticles (AgNPs) were successfully synthesized from the reduction of Ag+ using AgNO3 solution as a precursor and Brassica rapa var. japonica leaf extract as a reducing and capping agent. This study was aimed at synthesis of AgNPs, exhibiting less toxicity with high antibacterial activity. The characterization of AgNPs was carried out using UV–Vis spectrometry, energy dispersive X-ray spectrometry, fourier transform infrared spectrometry, field emission scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry, and transmission electron microscopy analyses. The analyses data revealed the successful synthesis of nano-crystalline Ag possessing more stability than commercial AgNPs. The cytotoxicity of Brassica AgNPs was compared with commercial AgNPs using in vitro PC12 cell model. Commercial AgNPs reduced cell viability to 23% (control 97%) and increased lactate dehydrogenase activity at a concentration of 3 ppm, whereas, Brassica AgNPs did not show any effects on both of the cytotoxicity parameters up to a concentration level of 10 ppm in PC12 cells. Moreover, Brassica AgNPs exhibited antibacterial activity in terms of zone of inhibition against E. coli (11.1?±?0.5 mm) and Enterobacter sp. (15?±?0.5 mm) which was higher than some previously reported green-synthesised AgNPs. Thus, this finding can be a matter of interest for the production and safe use of green-AgNPs in consumer products. 相似文献
96.
First, the single scattering model is briefly described. Next, the hybrid model is explained, which takes into consideration a part of the discrete energy loss processes. The Vriens or the Gryzinski cross section is used for core electron ionizations, and the Moller cross section for free electron excitations. The model is applied to the calculations of the energy distribution of transmitted electrons through a thin film and the depth distribution of generated x-rays. From comparisons among the calculated results with and without energy straggling and experimental data, it is found that the Gryzinski cross section shows the best result. 相似文献
97.
近年来,超高强度薄钢板越来越多地用于汽车车身部件,以提高汽车冲撞安全性和减轻车身重量,从而减少气体排放,保护环境。为适应这种需求.神户制钢已开发出几种980MPa级冷轧薄钢板。介绍了新开发的两种980MPa级冷轧薄钢板的特点:由于延展性和拉伸凸缘性的良好匹配而具有优良的成形性,同时还具有包括焊接性和化成处理性在内的良好的应用性能。 相似文献
98.
Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by the yeast strains of the genus Pseudozyma. These show not only the excellent surface-active properties but also versatile biochemical actions. In course of MEL production from soybean oil by P. shanxiensis, new extracellular glycolipids (more hydrophilic than the previously reported MELs) were found in the culture medium. As a result of the structural characterization, the glycolipids were identified as a mixture of 4-O-[(2', 4'-di-O-acetyl-3'-O-alka(e)noyl)-beta-D-mannopyranosyl]-D-erythritol and 4-O-[(4'-O-acetyl-3'-O-alka(e)noyl-2'-O-butanoyl)-beta-D-mannopyranosyl]-D-erythritol. Interestingly, the new MELs possessed a much shorter chain (C(2) or C(4)) at the C-2' position of the mannose moiety compared to the MELs hitherto reported, which mainly possess a medium-chain acid (C(10)) at the position. They would thus show higher hydrophilicity and/or water-solubility, and expand the development of the environmentally advanced yeast biosurfactants. 相似文献
99.
Morita T Konishi M Fukuoka T Imura T Kitamoto D 《Journal of Bioscience and Bioengineering》2007,104(1):78-81
Microbial conversion of glycerol into functional bio-based materials was investigated, aiming to facilitate the utilization of waste glycerol. A basidiomycete yeast, Pseudozyma antarctica JCM 10317, efficiently produced mannosylerythritol lipids (MELs) as glycolipid biosurfactants from glycerol. The amount of MEL yield reached 16.3 g l(-1) by intermittent feeding of glycerol. 相似文献
100.
Toshiyuki Nagata Kentaro Minami Masatatsu Yamamoto Tsubasa Hiraki Masashi Idogawa Katsumi Fujimoto Shun Kageyama Kazuhiro Tabata Kohichi Kawahara Kazuhiro Ueda Ryuji Ikeda Yukio Kato Masaaki Komatsu Akihide Tanimoto Tatsuhiko Furukawa Masami Sato 《International journal of molecular sciences》2021,22(21)