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591.
Low-Temperature Synthesis of Aluminum Silicon Carbide Using Ultrafine Aluminum Carbide and Silicon Carbide Powders 总被引:1,自引:0,他引:1
Minoru Hasegawa Kiyoshi Itatani Mamoru Aizawa F. Scott Howell Akira Kishioka 《Journal of the American Ceramic Society》1996,79(1):275-278
The conditions for preparing α-aluminum silicon carbide (α-Al4 SiC4 ) were examined by heating stoichiometric mixtures of ultrafine A14 C3 and SiC powders with sizes of <0.1 μm at and below 1600°C. The starting A14 C3 powder was obtained by the pyrolysis of trimiethylaluminum; the starting SiC powders were obtained by the pyrolyses of triethylsilane (3ES), tetraethylsilane (4ES), and hexamethyldisilane (6MDS). The reactivity of SiC with Al4 C3 to form α-Al4 SiC4 varies according to the kind of starting alkylsilane: 3ES > 4ES > 6MDS. The reaction of 3ES-derived SiC with A14 C3 produced α-Al4 SiC4 at temperatures as low as 1400°C for 240 min, regardless of the presence of A14 C3 (trace). Only α-Al4 SiC4 was formed at and above 1500°C for 60 min; the crystal growth was appreciable. 相似文献
592.
Akiko Kawashima Yuji Shimada Toshihiro Nagao Akihiro Ohara Tsugio Matsuhisa Akio Sugihara Yoshio Tominaga 《Journal of the American Oil Chemists' Society》2002,79(9):871-877
γ-Linolenic acid (GLA) has the physiological functions of modulating immune and inflammatory responses. We produced structured
TAG rich in 1,3-dicapryloyl-2-γ-linolenoyl glycerol (CGC) from GLA-rich oil (GLA45 oil; GLA content, 45.4 wt%), which was
prepared by hydrolysis of borage oil with Candida rugosa lipase having weak activity on GLA. A mixture of GLA45 oil/caprylic acid (CA) (1∶2, w/w) was continuously fed into a fixed-bed
bioreactor (18×180 mm) packed with 15 g immobilized Rhizopus oryzae lipase at 30°C, and a flow rate of 4 g/h. The acidolysis proceeded efficiently, and a significant decrease of lipase activity
was not observed in full-time operation for 1 mon. GLA45 oil contained 10.2 mol% MAG and 27.2 mol% DAG. However, the reaction
converted the partial acylglycerols to structured TAG and tricaprylin and produced 44.5 mol% CGC based on the content of total
acylglycerols. Not only FFA in the reaction mixture but also part of the tricaprylin and partial acylglycerols were removed
by molecular distillation. The distillation resulted in an increase of the CGC content in the purified product to 52.6 mol%.
The results showed that CGC-rich structured TAG can efficiently be produced by a two-step process comprising selective hydrolysis
of borage oil using C. rugosa lipase (first step) and acidolysis of the resulting GLA-rich oil with CA using immobilized R. oryzae lipase (second step). 相似文献
593.
Contents of plasticizers in cap-sealing for bottled food and their migration into food 总被引:1,自引:0,他引:1
Tsumura Y Kaihara A Ishimitsu S Yoshii K Tonogai Y 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(6):377-384
Plasticizers in cap-sealing for bottled foods were analyzed. Twenty-three domestic samples and 80 imported samples, a total of 103 samples, were tested. Among them, 93 contained chloride, and 62 contained di(2-ethylhexyl) phthalate (DEHP), diisodecyl phthalate, O-acetyl tributyl citrate, diacetyllauroyl glycerol, di(2-ethylhexyl) adipate, diisononyl phthalate or dicyclohexyl phthalate. Twelve samples with DEHP-containing caps were further tested for plasticizer levels in the foods. Higher DEHP was detected in oily and fluid food specimens. However, the intake of plasticizers calculated based on usual food consumption did not exceed the tolerable daily intake level in any of the cases. A food sample containing the highest level of DEHP was stored under various conditions, and DEHP that migrated from the cap-sealing into the food was determined. Shaking the bottles increased migration of DEHP into foods. 相似文献
594.
Ishikawa F Oishi M Kimura K Yasui A Saito K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(3):150-155
A method for the determination of 12 synthetic food dyes (Amaranth, Erythrosine, Allura Red AC, New Coccine, Phloxine, Rose Bengal, Acid Red, Tartrazine, Sunset Yellow FCF, Fast Green FCF, Brilliant Blue FCF, Indigo Carmine) in food was developed using capillary electrophoresis (CE) with photodiode array detection. The dyes were extracted with water and 0.5% ammonia-ethanol (1:1) mixture, and cleaned up using solid-phase extraction (Sep-Pak Plus tC18). The dyes were eluted with methanol from the cartridge. The dyes were separated by CE on a bubble cell fused-silica capillary (72 cm to the detector, 75 microm i.d.) using 20% acetonitrile in a mixture of 10 mmol/L potassium phosphate, monobasic and 5 mmol/L sodium carbonate (pH 10.0) as the running buffer. Identifications of the dyes were performed on the basis of the migration time and the absorbance spectrum of each peak. The coefficients of variation of the migration times and the peak areas were 0.28-0.62% and 1.84-4.30%, respectively (n = 5). The identification limits using the absorbance spectra of the dyes were 10 microg/mL for Brilliant Blue FCF and Fast Green FCF, and 5 microg/mL for the other 10 dyes. The recoveries of the 12 dyes from pickles, soft drinks and candies at the level of 10 microg/g were 70.0-101.5%. The method was applied to the analysis of dyes in foods. The dyes detected by CE were in agreement with those detected by paper chromatography. 相似文献
595.
C Schmedt K Saijo T Niidome R Kühn S Aizawa A Tarakhovsky 《Canadian Metallurgical Quarterly》1998,394(6696):901-904
The development and function of alphabetaT lymphocytes depend on signals derived from pre-T and alphabetaT cell receptors (preTCR and alphabetaTCR) (reviewed in refs 1, 2). The engagement of these receptors leads to the activation of Lck and Fyn, which are protein tyrosine kinases (PTKs) of the Src family. It remains unclear to what extent the activation of Src-family PTKs can direct the differentiation steps triggered by preTCR and alphabetaTCR. Here we show that the inactivation of the negative regulator of Src-family PTKs, carboxy-terminal Src kinase (Csk), in immature thymocytes abrogates the requirement for preTCR, alphabetaTCR and major histocompatibility complex (MHC) class II for the development of CD4+ 8+ double-positive and CD4+ single-positive thymocytes as well as peripheral CD4 alphabetaT-lineage cells. These data show that Csk and its substrates are required to establish preTCR/alphabetaTCR-mediated control over the development of alphabetaT cells. 相似文献
596.
597.
Sawada Anju Ishiguro Akiko Inada Yoshihiko Suzuki Michiro Sato Noriaki Komatsubara Takemi 《Journal of Low Temperature Physics》1995,101(3-4):645-650
The ac magnetic susceptibility of UPd2Al3 in the superconducting state has been measured to test of the existence of the Fulde, Ferrell, Larkin and Ovchinnikov (FFLO) state. A dip in the susceptibility has been observed in the vicinity of the upper critical field and the temperature range from zero to Tc. This dip is very sensitive to the amplitude of the ac magnetic field. The anomaly is explained by the increase of the flux pinning effect. Recent theories suggest that the pinning force becomes stronger in the FFLO state, and the existence of the nonuniform state due to the order parameter mixing in a d-wave superconductor is possible near Tc. 相似文献
598.
The new aspects of molecular conductors are reviewed. The origin of the two-dimensionality of the system is interpreted on the basis of the simple tight-binding band examinations. The charge distribution rule which emerges in these systems is described in relation to the multi-dimensionality of these complexes. 相似文献
599.
Y Kuriyama M Nakano Y Kawanishi O Iwase S Aizawa K Toyama 《Canadian Metallurgical Quarterly》1995,9(12):2123-2126
In order to analyze systemic immune surveillance in patients with B cell non-Hodgkin's lymphomas (B-NHL), we investigated circulating lymphocytes using two-color flow cytometry. The proportions of CD3-CD56+ natural killer (NK) cells and CD8++(bright) S6F1++ killer-effector T cells corresponding to activated cytotoxic T lymphocytes (aCTL) were studied in the peripheral blood of 26 patients with indolent lymphoma (IL) and 24 with aggressive lymphoma (AL). The AL patients with both limited disease and advanced disease had an increased proportion of NK cells. However, this feature was not evident in IL patients with either limited or advanced disease. In contrast, an increased proportion of aCTL was observed only in IL patients with advanced disease. These findings indicate that IL may differ from AL in terms of immune surveillance against neoplastic B cells. 相似文献
600.
In order to search for the origin of vascular lesion from the hydrodynamic point of view, the viscous flows in a constricted
channel and in a channel with a branch are studied numerically. The results obtained show the importance of the temporal variation
of shearing stress on the wall. 相似文献