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排序方式: 共有2294条查询结果,搜索用时 15 毫秒
61.
Koji Mori Masuo Kaji Kotohiko Sekoguchi Manabu Sakane Masao Nakazatomi Hideo Shimizu 《亚洲传热研究》1996,25(8):499-510
Time-series information on both the cross-sectional mean liquid holdup along a tube axis and the gas-liquid phase distribution along a tube diameter was obtained by means of supermultiple cross-sectional mean liquid holdup probes (S-CHOP) and semi-supermultiple point-electrode probes (SS-PEP) for vertical downward gas-liquid two-phase flow. Typical time-spatial behavior charts of interface and gas-liquid interfacial profiles are presented. Close inspection of these results reveals that a huge wave and a disturbance wave appear in downward two-phase flow as well as upward flow. It was clarified that the huge wave flow region covers a wide range of superficial gas velocities. Wave velocity, wave width and maximum liquid holdup of individual waves were examined by wave-vein analysis. Histograms of these flow parameters were also studied. It was found that there exist distinct differences in wave width between the huge wave and the disturbance wave. © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(8): 499–510, 1996 相似文献
62.
63.
The viscoelastic properties of soybean curd (tofu) as affected by soymilk concentration and type of coagulant 总被引:1,自引:0,他引:1
Yongqiang Cheng Naoto Shimizu & Toshinori Kimura 《International Journal of Food Science & Technology》2005,40(4):385-390
The viscoelastic properties of different types of tofu were investigated. Soymilk concentrations were 5, 6, 7, 8 and 9%. Coagulants used were 30 mm CaSO4 or 30 mm glucono‐delta‐lactone (GDL). As the concentration of soymilk was increased viscosity and handling difficulties increased. A high concentration of soymilk in tofu gave a high break stress and produced hard tofu. The four‐element Burgers model fitted the creep behaviour and both viscous and elastic parameters could be acquired from model analysis, reflecting changes in elasticity and viscosity of tofu. The constant viscous parameter in the model increased with increasing soymilk concentration. The viscous parameters of viscoelastic materials like tofu gel, obtained from small deformation tests, seemed to correlate, to some extent, with the break stress obtained from large deformation tests. For hard tofu production increasing the soymilk concentration within a certain range and the partial replacement of calcium sulphate coagulant by GDL could be effective options. 相似文献
64.
The regulatory mechanism for poly-3-hydroxybutyrate (PHB) biosynthesis in recombinant Escherichia coli is markedly different from that of Ralstonia eutropha (formerly, Alcaligenes eutrophus) since the former efficiently synthesizes PHB during growth without any nutrient limitation. To analyze how the central metabolic pathways should be balanced with pathways necessary for cell growth and PHB formation, a stoichiometric model was developed to predict the theoretical maximum PHB production capacity for different metabolic variants. Flux analysis results illustrated the importance of the availability of acetyl-CoA and NADPH for achieving the maximum yield of PHB. In order to examine whether the increased availability of the above substances can enhance PHB synthesis in recombinant E. coli, both genetic and environmental perturbations were attempted. Several E. coli K12 derivatives, namely, HMS174, TA3516 (pta-/ack-), and DF11 (pgi-), were transformed with a plasmid which contains the native phb operon. The fermentation characteristics of these recombinant strains were studied and compared. In this study we examined the effects of intracellular acetyl-CoA accumulation, which may promote PHB synthesis in vivo, by perturbations induced from attenuation of acetate kinase and phosphotransacetylase (TA3516, blocked in the acetate pathway) and by cultivation of E. coli HMS174 on gluconate; it can convert gluconate to acetyl-CoA at a higher rate. The effects of intracellular accumulation of NADPH were investigated by introducing a perturbation induced from attenuation of phosphoglucose isomerase, which redirects the carbon flow to the pentose-phosphate (PP) pathway. Results from the analyses of these perturbations indicate that intracellular buildup of acetyl-CoA may not be able to promote PHB synthesis in vivo. On the other hand, since the biosynthesis of PHB in the pgi- mutant strain can utilize the NADPH overproduced through the PP pathway, the growth of the pgi- mutant on glucose was recovered, indicating that the overproduction of NADPH might be able to enhance PHB synthesis. 相似文献
65.
The extraction equilibria of In3+, Ga3, and Zn2+ with bis(4‐ethylcyclohexyl)phosphoric acid (D4ECHPA), bis(4‐cyclohexylcyclohexyl)phosphoric acid (D4DCHPA), and bis(2‐ethylhexyl)phosphoric acid (D2EHPA) were investigated in acidic aqueous sulfate media. The order of extractability of metal ions is D4DCHPA > D2EHPA > D4ECHPA, which corresponds to the lipophilicity (log P) of the extractants. The separation factors, β(In/Ga) and β(Ga/Zn), of D4ECHPA and D4DCHPA are greater or comparable than that of D2EHPA, because of the steric hindrance of the bulky cyclohexyl groups. In3+ can be therefore separated from simulated liquor containing a high concentration of Zn2+ by D4DCHPA. 相似文献
66.
This paper demonstrates two simple ways to increase 5-hydroxymethylfurfural (HMF) yield (selectivity) in fructose dehydration with various solid acid catalysts. One is a water removal from the reaction mixture by a mild evacuation at 0.97 × 105 Pa; it increases HMF yield for various catalysts (heteropoly acid, zeolite, and acidic resin). The removal of water suppresses two undesired reactions: the hydrolysis of HMF to levulinic acid and the reaction of partially dehydrated intermediates to condensation products. The other method is a decrease in the particle (bead) size of the resin (Amberlyst-15). The crushed and sieved Amberlyst-15 powder in a size of 0.15–0.053 mm shows 100% HMF yield at high fructose concentration (50 wt.% in DMSO), which is to our knowledge the highest yield to date. Near-infrared spectroscopic characterization of adsorbed water suggests that the enhanced yield can be caused by an improved removal of adsorbed water in a small-size resin particle. 相似文献
67.
Regiospecific analysis by ethanolysis of oil with immobilized <Emphasis Type="Italic">Candida antarctica</Emphasis> lipase 总被引:1,自引:1,他引:1
Shimada Y Ogawa J Watanabe Y Nagao T Kawashima A Kobayashi T Shimizu S 《Lipids》2003,38(12):1281-1286
A mixture of oil/ethanol (1∶3, w/w) was shaken at 30°C with 4% immobilized Candida antarctica lipase by weight of the reaction mixture. The reaction regiospecifically converted FA at the 1- and 3-positions to FA ethyl
esters, and the lipase acted on C14−C24 FA to a similar degree. The content of 2-MAG reached a maximum after 4 h; the content was 28–29 mol% based on the total amount
of FA in the reaction mixture at 59–69% ethanolysis. Only 2-MAG were present in the reaction mixture during the first 4 h,
and 1(3)-MAG were detected after 7 h. After removal of ethanol from the 4-h reaction mixture by evaporation, 2-MAG were fractionated
by silica gel column chromatography. The contents of FA in the 2-MAG obtained by ethanolysis of several oils coincided well
with FA compositions at the 2-position, which was analyzed by Grignard degradation. It was shown that ethanolysis of oil with
C. antarctica lipase can be applied to analysis of FA composition at the 2-position in TAG. 相似文献
68.
Tetsuro Hori Naoki Fukuoka Tetsuya Masuda Yasuo Miyake Hiroyuki Yoshida Akihiko Fujii Yo Shimizu Masanori Ozaki 《Solar Energy Materials & Solar Cells》2011,95(11):3087-3092
Bulk heterojunction solar cells utilizing soluble phthalocyanine derivative, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) have been investigated. The active layer was fabricated by spin-coating the mixed solution of C6PcH2 and 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM). The photovoltaic properties of the solar cell with bulk heterojunction of C6PcH2 and PCBM demonstrated the strong dependence of active layer thickness, and the optimized active layer thickness was clarified to be 120 nm. By inserting MoO3 hole transport buffer layer between the positive electrode and active layer, the FF and energy conversion efficiency were improved to be 0.50 and 3.2%, respectively. The tandem organic thin-film solar cell has also been studied by utilizing active layer materials of C6PcH2 and poly(3-hexylthiophene) and the interlayer of LiF/Al/MoO3 structure, and a high Voc of 1.27 V has been achieved. 相似文献
69.
Wada M Kawabata H Yoshizumi A Kataoka M Nakamori S Yasohara Y Kizaki N Hasegawa J Shimizu S 《Journal of Bioscience and Bioengineering》1999,87(2):144-148
Multiple ethyl 4-chloro-3-oxobutanoate (COBE)-reducing enzymes were isolated from a cell-free extract of Candida magnoliae. A NADPH-dependent COBE-reducing enzyme, distinct from the carbonyl reductase and aldehyde reductase previously reported, was purified to homogeneity using five steps, including polyethylene glycol treatment. The relative molecular mass of the enzyme was estimated to be 86,000 on high performance gel-permeation chromatography and 29,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme catalyzed the reduction of COBE to the corresponding (S)-alcohol with a 51% enantiomeric excess. The substrate specificity of the enzyme was different from those of the other COBE-reducing enzymes of the same strain. The partial amino acid sequences of the enzyme showed that it belongs to the short chain alcohol dehydrogenase/reductase (SDR) family. This is the first report of multiple COBE-reducing enzymes with various stereoselectivities occurring in the same strain but belonging to different (super)families. 相似文献
70.