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排序方式: 共有916条查询结果,搜索用时 15 毫秒
21.
Nguyen Chi Trung Ngo Hironari Sugiyama Buddhika Amila Kumara Sodige Juan Paulo Wiff Satoru Yamanaka Yoonho Kim Tsuneo Suzuki Masaaki Baba Masatoshi Takeda Noboru Yamada Koichi Niihara Tadachika Nakayama 《Journal of the American Ceramic Society》2023,106(1):201-212
The energy-harvesting ability of the lead-free ferroelectric Ba(Zr,Ti)O3 was investigated and greatly enhanced using the Kim novel electrothermodynamic cycle for low-temperature application. Ba(Zr,Ti)O3 was synthesized with a Zr:Ti ratio of 10:90 (BZT10) by hot-press sintering, which exhibited a mix relaxor-ferroelectric behavior. For power generation using the Kim cycle with low and high temperatures of TL = 25°C, TH = 120°C, the most optimized temperature pattern occurred for a heating time of 12.5 s and a cooling time of 22.5 s. Under these conditions, the electric field increased during the novel isodisplacement process, and the displacement variation in the isoelectric step reached the highest value and maximized the BZT10 cycle loop area. Applying these conditions while lowering TL to 20°C, an energy density ND = 504 mJ/cm3 was achieved. This value is the highest obtained energy density in a practical test for lead-free ferroelectric bulk material in the BaTiO3 family. 相似文献
22.
YoonKeun Chae JinWon Park Shinsuke Mori Masaaki Suzuki 《Korean Journal of Chemical Engineering》2013,30(1):62-66
The photocatalytic characteristics of partially reduced TiO2 (TiO2?x ) by plasma treatment and plasma-heated treatment were investigated in the visible-light region. For the visible-light photocatalytic activity of TiO2?x , plasmaheated treatment shows stronger than plasma treatment significantly. The TiO2?x by plasma-heated treatment shows broader red-shifted absorption bands than one by plasma treatment in the visible-light region. The surface color of TiO2?x by plasma treatment and plasma-heated treatment changed from white to sky blue, and to navy, respectively. After exposure to air, the surface color of TiO2?x changed from sky blue to white for plasma treatment and from navy to beige for plasma-heated treatment. 相似文献
23.
Park JH Dias CA Lee SB Valentini SR Sokabe M Fraser CS Park MH 《Protein engineering, design & selection : PEDS》2011,24(3):301-309
Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein that contains the polyamine-modified lysine, hypusine [N(ε)-(4-amino-2-hydroxybutyl)lysine]. Hypusine occurs only in eukaryotes and certain archaea, but not in eubacteria. It is formed post-translationally by two consecutive enzymatic reactions catalyzed by deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). Hypusine modification is essential for the activity of eIF5A and for eukaryotic cell proliferation. eIF5A binds to the ribosome and stimulates translation in a hypusine-dependent manner, but its mode of action in translation is not well understood. Since quantities of highly pure hypusine-modified eIF5A is desired for structural studies as well as for determination of its binding sites on the ribosome, we have used a polycistronic vector, pST39, to express eIF5A alone, or to co-express human eIF5A-1 with DHS or with both DHS and DOHH in Escherichia coli cells, to engineer recombinant proteins, unmodified eIF5A, deoxyhypusine- or hypusine-modified eIF5A. We have accomplished production of three different forms of recombinant eIF5A in high quantity and purity. The recombinant hypusine-modified eIF5A was as active in methionyl-puromycin synthesis as the native, eIF5A (hypusine form) purified from mammalian tissue. The recombinant eIF5A proteins will be useful tools in future structure/function and the mechanism studies in translation. 相似文献
24.
Meng-Liang Lin Kenji Hara Yasuhiro Okubo Masaaki Yanagi Hironobu Nambu Atsushi Fukuoka 《Catalysis communications》2011,12(13):1228-1230
The olefin epoxidation is one of the most important reactions in chemical industry. Metal oxide supports often cause drawbacks in catalytic activity and selectivity, which has been overcome by introducing hydrophobic organic groups onto the oxide supports. The present study utilizes ordered mesoporous carbon (CMK-3 and CMK-1) as structurally defined hydrophobic catalyst support. Well-dispersed tantalum oxides supported on the ordered mesoporous carbon were prepared. Their application in catalytic epoxidation of cyclooctene demonstrates that the tantalum oxide catalysts on the ordered mesoporous carbon supports show higher performances than those of the catalysts supported on activated carbon and ordered mesoporous silica SBA-15. 相似文献
25.
Toshihiro Nagao Yuji Shimada Yoshie Yamauchi-Sato Takaya Yamamoto Masaaki Kasai Kentaro Tsutsumi Akio Sugihara Yoshio Tominaga 《Journal of the American Oil Chemists' Society》2002,79(3):303-308
A commercial product of CLA contains almost equal amounts of cis-9,trans-11 (c9,t11)-CLA and trans-10,cis-12 (t10,c12)-CLA. We attempted to enrich the two isomers by a two-step selective esterification using Candida rugosa lipase that acted on c9,t11-CLA more strongly than on t10,c12-CLA. An FFA mixture containing CLA isomers was esterified with an equimolar amount of lauryl alcohol in a mixture of 20%
water and the lipase. When the esterification of total FA reached 50%, two isomers were fractionated in a good yield: t10,c12-CLA was enriched in FFA, and c9,t11-CLA was recovered in lauryl esters. The FFA were esterified again to enrich t10,c12-CLA. At 27.3% esterification of total FA, the t10,c12-CLA content in FFA increased to 64.8 wt% with 89.3% recovery: The ratio of the content of t10,c12-CLA to that of two isomers was 95.9%. Lauryl esters obtained by the single esterification were employed for enrichment
of c9,t11-CLA. After the esters were hydrolyzed, the resulting FFA were esterified again with lauryl alcohol. At 62.0% esterification
of total FA, the c9,t11-CLA content in lauryl esters increased to 73.3 wt% with 79.4% recovery: The ratio of the content of c9,t11-CLA to that of two isomers was 95.6%. In a 600-g-scale purification, molecular distillation was effective in separating
the reaction mixture into lauryl alcohol, FFA, and lauryl ester fractions. 相似文献
26.
Preparation, Structure, and Properties of Thermally and Mechanically Improved Aluminum Titanate Ceramics Doped with Alkali Feldspar 总被引:3,自引:0,他引:3
Masahide Takahashi Masahiro Fukuda Masaaki Fukuda Hisato Fukuda Toshinobu Yoko 《Journal of the American Ceramic Society》2002,85(12):3025-3030
Aluminum titanate (AT) ceramic materials doped with alkali feldspar ((Na0.6 K0.4 )AlSi3 O8 ) have been prepared. These ceramics exhibited high sinterability, large resistance to thermal decomposition, and large flexure strength. The existence of liquid-phase feldspar at sintering temperatures promoted the formation of AT ceramics as the sintering agent. It was considered that silicon ions substituting for aluminum ions at the surface of AT crystal grains lowered the surface energy and hindered the diffusion of Ti4+ and Al3+ , giving rise to the large resistance to thermal decomposition. As a result, doping with alkali feldspar was found to effectively improve the mechanical and thermal properties of AT ceramics. 相似文献
27.
Yuji Tatemoto Yoshiyuki Bando Koji Oyama Keiji Yasuda Masaaki Nakamura Yasuhiro Sugimura Masahito Shibata 《Drying Technology》2001,19(7):1287-1303
The effects of operational conditions on the drying performance in closed superheated steam drying were examined theoretically and experimentally. The vapor generated from the sample was circulated in the drying chamber. In the theoretical analysis, the replacement of air with vapor in drying chamber and the convective vapor transfer in sample were considered. At the start of drying, the drying chamber was filled with air. As the drying proceeded, the air was replaced with the vapor generated from sample. The calculated results explained the characteristics of experimental data. The pore diameter of sample had little effect on the drying characteristics. During the internal evaporation period, the evaporation occurred in the narrow zone, which moved from the surface to the bottom of sample. The convective vapor transfer in sample had a significant influence on the drying performance. The excess increments in temperature and velocity of drying gas hardly contributed to shortening the drying time. 相似文献
28.
Yuji Tatemoto Yoshiyuki Bando Keiji Yasuda Yoshitaka Senda Masaaki Nakamura 《Drying Technology》2001,19(7):1305-1318
The drying characteristics of porous material in fluidized bed were examined theoretically and experimentally. The brick ball was used as the sample and immersed in the fluidized bed. The glass beads were used as the fluidizing particles and the particle diameters were changed. When the pore diameter of sample was relatively large, the fluidizing particles were adhered on the sample surface. In the theoretical analysis, the heat and mass transfers in adhered particle layer were considered. The fluidizing particles were adhered on the sample surface during the earlier period of drying. The sample temperature largely decreased when the mass of adhered particle decreased. The calculated results are in good agreement with experimental data. The diameter of fluidizing particle had a small effect on the drying time. The excess increments in drying gas temperature hardly contributed to shortening the drying time. 相似文献
29.
Hiroshi Kominami Masaaki Kohno Yukino Matsunaga Yoshiya Kera 《Journal of the American Ceramic Society》2001,84(5):1178-1180
Silica-modified titanium oxide (S-TiO2 ) powders that have an anatase structure were synthesized via the thermal decomposition of mixtures of titanium(IV) isopropoxide (TIP) and tetramethyl orthosilicate (TMOS) in toluene at 300°C. These S-TiO2 materials had high rutile-transformation temperatures and maintained large surface areas at elevated temperatures (550°–1000°C). For example, the product that was prepared from a 9:1 TIP:TMOS mixture transformed to rutile at ∼1100°C and possessed a surface area of 160 m2 /g, even after calcination at 800°C for 1 h. 相似文献
30.
Seong-Jai Cho Yun-Cheol Lee Kyung-Jin Yoon Jong-Jip Kim Jun-Hee Hahn Hyun-Min Park Masaaki Yanagisawa 《Journal of the American Ceramic Society》2001,84(5):1143-1147
By classification, two powder portions, one consisting of coarse particles and the other consisting of fine particles, were separated from a MgO-doped (1000 ppm) commercial-purity Al2 O3 powder. Examinations of microstructure evolution during hot pressing showed that extensive abnormal grain growth occurred for the coarse portion. For the fine portion, although there was an indication that grain-size distribution deviated from normal distribution on prolonged hot pressing, such extensive abnormal grain growth did not occur. Extensive abnormal grain growth also occurred when the coarse portion was mixed into a high-purity powder that exhibited no abnormal grain growth alone. Chemical analyses revealed that the coarse portion contained the higher concentration of impurities but lower concentration of magnesium than the fine portion. It was discussed that particle aggregates in the coarse portion might have been responsible for the higher concentration of impurities but lower concentration of magnesium and, thus, for the extensive abnormal grain growth. 相似文献