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排序方式: 共有1193条查询结果,搜索用时 15 毫秒
981.
Weiwu Chen Yoshiaki Kinemuchi Koji Watari Takuya Tamura Kenji Miwa 《Journal of the American Ceramic Society》2006,89(1):381-384
The properties of polycrystalline ceramics are strongly influenced by their crystallographic texture. In this study, highly grain-oriented tungsten bronze structure ferroelectric ceramics, Sr0.5 Ba0.5 Nb2 O6 , were successfully fabricated by magnetic alignment and gelcasting techniques using only the conventional solid-state-synthesized starting powder. Spherical Sr0.5 Ba0.5 Nb2 O6 particles were aligned according to their anisotropic magnetic property in 40 vol% slurry in a 10 T magnetic field, and then in situ locked by polymerization via a gelcasting technique for 30 min. A 〈00 l 〉-axis orientation perpendicular to the magnetic field direction ( B ) was obviously observed in the green compact and sintered sample. The sintered Sr0.5 Ba0.5 Nb2 O6 sample contained equiaxial grains and reached 98% theoretical density. Compared with the sample with randomly oriented grains, the magnetically aligned sample showed an enhanced with dielectric constant in the ⊥ B direction (1100 versus 750 at room temperature and 4300 versus 2800 at Curie temperature). This new method is readily applicable to other ceramics with tungsten bronze structure, and is expected to facilitate mass preparation of large and dense grain-oriented ceramic materials. 相似文献
982.
Weiwu Chen Yoshiaki Kinemuchi Koji Watari Takuya Tamura Kenji Miwa 《Journal of the American Ceramic Society》2006,89(8):2645-2648
In the current work, we reported a potential approach to obtain thick ceramic films with controllable grain orientation based on magnetic alignment and polymerization techniques. The slurry containing 40 vol% Bi4 Ti2.96 Nb0.04 O12 (BINT) ceramic powder, monomer, initiator, and catalyst was drop coated on a Pt substrate and then moved into a vertical 10 T magnetic field. In 1–2 min, the ceramic particles were aligned by a strong magnetic force in slurry and then in situ locked by polymerization on the substrate. After sintering at 1000°C, a BINT ceramic film (50–80 μm in thickness) with a highly a / b plane orientation was obtained. Theoretically, the grain orientation in the films can be easily controlled by adjusting the magnetic field direction. This approach is readily applicable to other materials with a non-cubic structure and is expected to facilitate the fast preparation of grain-oriented thick films. 相似文献
983.
Co, Ni and Mn K-edge XAFS investigation of LiCo1/3Ni1/3Mn1/3O2 as alternative cathode material to commercially used LiCoO2 in lithium rechargeable battery has been performed. Parameters of a local atomic structure such as radii of metal-oxygen and metal-metal coordination shells and disorder in those shells have been determined. It has been found that the radius of the first coordination shell (metal-oxygen) as well as a local disorder in the second shell (metal-metal) around each of the 3d-metals are in a good agreement with obtained for superlattice model of [√3 × √3] R30° type in triangular lattice of sites by first principle calculation. Other parameters of the local atomic structure around Co, Ni and Mn atoms do not provide evidence for presence of superstructure in LiCo1/3Ni1/3Mn1/3O2. 相似文献
984.
Shun‐ichi Nakano Kazumi Kakugawa Tetsuhiro Nemoto Yasumasa Hamada 《Advanced Synthesis \u0026amp; Catalysis》2014,356(9):2088-2096
We have succeeded in the highly diastereoselective synthesis of cyclobutane‐fused multi‐cyclic compounds using a scandium‐catalyzed cascade cyclization. Using 3–10 mol% of scandium(III) triflate [Sc(OTf)3], various cyclobutane‐fused tetrahydroquinoline derivatives as well as its chromane, thiochromane, and tetrahydronaphthalene analogues were obtained in good to excellent yields. Derivatizations of the reaction products, as well as the plausible reaction mechanism, are also discussed.
985.
Satoshi Koyanagi Toshio Murakami Toshihiro Maeda Kenjirou Kawatsu Hiroshi Okamura Yoshiaki Oda Yoshinobu Miyatsu Keishin Sugawara Hiroshi Mizokami 《Journal of Bioscience and Bioengineering》2010,110(5):597-601
A WHO position paper states that allergen immunotherapy is an effective treatment for allergic diseases, and well characterized allergens should be used in immunotherapy. The house dust mite is a major cause of allergic disease. However, the biological activity of the mite extracts currently used cannot be clearly determined, since these extracts contain various impurities. The use of recombinant allergens can avoid this problem. However, there remains a risk of contamination by other impurities, such as host cell-derived proteins (HCPs). Advanced purification techniques are thus required to remove these contaminants. C8/119S is a mutant of the major house dust mite allergen Der f 2, and is expressed and accumulated as an inclusion body in Escherichia coli. The C8/119S was refolded and purified through three column chromatography steps. Using this method, we could obtain about 2 g of the purified C8/119S in one purification batch. This amount is equivalent to 100,000 of the maintenance doses required for immunotherapy based on the WHO position paper. The purity of the C8/119S was 99% or more. The antigenicity of HCPs in the C8/119S was examined by passive cutaneous anaphylaxis assays. When the C8/119S was administered at 40 μg/kg, no local anaphylaxis was observed. C8/119S was thus highly purified with an extremely low level of impurities, and our procedure was shown to be an effective advanced production-scale purification process for this Der f 2 mutant. In this study, we established an advanced purification processes for C8/119S, then characterized the purified C8/119S and evaluated its purity. 相似文献
986.
To develop a selective medium for the isolation of anaerobic gram-positive cocci from marine animals, agar media containing various drugs were examined using strains of Streptococcus sp., Vibrio spp. and Pseudomonas sp. On MAGPC medium, a modified BL agar with 0·3% β-phenylethyl alcohol, the anaerobic Streptococcus sp. grew well whereas other bacterial strains were inhibited. As compared with other four agar media, the MAGPC medium could efficiently isolate anaerobic gram-positive cocci from marine animals. 相似文献
987.
Katsushi Fujii Shinichiro Nakamura Masakazu Sugiyama Kentaroh Watanabe Behgol Bagheri Yoshiaki Nakano 《International Journal of Hydrogen Energy》2013
Energy storage is a key technology for establishing a stand-alone renewable energy system. Current energy-storage technologies are, however, not suitable for such an energy system because the technologies are cost ineffective and achieve low energy-conversion efficiency. The most realistic and expected technology is hydrogen generation from water splitting by an electrochemical cell directly connected with photovoltaic cell. In this study, a simple concept is proposed for generating hydrogen from water splitting by using a direct-electrically-connected polymer electrolyte electrochemical cell and a separately-located concentrated photovoltaic cell, named a “concentrated photovoltaic electrochemical cell (CPEC)”. The CPEC operates stably and achieves relatively high-energy conversion efficiency from light to hydrogen of over 12%. The conditions are comparison with those of the electrochemical cell connected with a polycrystalline Si solar cell. 相似文献
988.
Hossain MI Morioka K Shikha FH Itoh Y 《Journal of the science of food and agriculture》2011,91(2):247-252
BACKGROUND: The physical attribute of heat‐induced gel texture is highly dependent on the microstructure of the gel. In this study the microstructures of walleye pollack surimi gels preheated at various temperatures with and without inhibitors (ethylenediamine‐N,N,N′,N′‐tetraacetic acid, iodoacetamide and leupeptin) were observed with a natural scanning electron microscope. RESULTS: Without inhibitors, gels preheated at 30 °C showed a fine and uniform network structure together with the highest polymerisation of myosin heavy chain (MHC) and the highest gel strength. At 60 °C, gels exhibited a broken, disrupted and loose cluster‐like structure together with the highest degradation of MHC and the lowest gel strength. Under the inhibition of polymerisation and degradation of MHC a fine network was observed up to 40 °C during preheating. However, after a second step of heating at 80 °C the microstructures were disrupted and resembled each other regardless of the preheating temperature. CONCLUSION: Heat‐induced gel formation is related to the polymerisation and degradation of MHC and the microstructure of the gel during preheating. Gelation occurred during setting even under the inhibitory condition, and the formation of covalent bonding by transglutaminase is not essential to the formation of a three‐dimensional network during setting but is essential to the gel strength enhancement effect of setting by subsequent heating at 80 °C. Copyright © 2010 Society of Chemical Industry 相似文献
989.
990.
Chika Ohira Hidetoshi Fujii Yoshiaki Morisada 《Journal of Materials Engineering and Performance》2014,23(5):1561-1567
The surface tension of molten Sn-Ag alloys was measured using a specially developed high-accuracy sessile drop apparatus. In this apparatus, a molten sample is dropped onto a R-Al2O3 substrate in order to prevent any reaction between the sample and substrate during the heating process. The droplet shape was recorded from two perpendicular directions to confirm its symmetry. The oxygen partial pressure ( $ {P_{{{\text{O}}_2}}} $ ) was controlled by a Mg furnace to a value of about 10?16 to 10?15 Pa. The sample compositions used were Sn-20Ag, Sn-50Ag, and Sn-80Ag (at.%) and were alloyed from pure Sn (99.999%) and Ag (99.99%) in the dropping tube. The accuracy of the experimental results was confirmed by an extremely small scatter. The measured temperature dependence of the surface tension of the molten Sn-50Ag (at.%) alloy indicated a characteristic curve that changed from positive to negative with increasing temperature. Furthermore, the surface tension of the molten Sn-20Ag (at.%) alloy has a temperature dependence that changes from flat to negative, while the Sn-80Ag (at.%) alloy has a negative temperature dependence across the whole temperature range. Based on a theoretical discussion using Butler’s equation, these temperature dependencies can be determined by negative straight lines when assuming the surface composition. 相似文献