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41.
A new processing system for the extrusion of microcellular polymer sheets is presented. Specifically, the detailed design of a shaping and cell growth control system is discussed in the context of an overall extrusion system design with particular emphasis on the system level functional requirements of cell nucleation, cell growth, and shaping. The principle of the basic extrusion system design is to shape a nucleated polymer/gas solution flow under pressure and accurate temperature control. In this way, the initial cell growth is controlled so as to prevent degradation of the nucleated cell density during shaping. Two foaming die designs for satisfying the initial shaping and cell growth requirements are presented. Critical experiments are then presented which verified the concept of shaping a nucleated polymer/gas solution. Moreover, these experiments demonstrated the feasibility of the overall microcellular polymer sheet extrusion system design. 相似文献
42.
Sung-Joon Lee Sang-Ho Yoo Myo-Jung Kim Jung-Wan Kim Ho-Moon Seok Kwan-Hwa Park 《Starch - St?rke》1995,47(4):127-134
A branched oligosaccharides (BOS) mixture was produced from liquefied starch solution using a maltogenic amylase of Bacillus licheniformis (BLMA). The BOS mixture was produced by both α-1,4-bond hydrolyzing and α-1,6-transglycosylation activities of BLMA, and it contained 58.3% of various branched oligosaccharides. Small branched oligosaccharides such as isomaltose, isopanose, and panose were identified in the mixture by various analyses including high performance ion-chromatography (HPIC). Major branched DP4 and DP5 molecules in the mixture were determined as 62-O-α-maltosylmaltose, 63-O-α-maltosyl-maltotriose and 62-O-α-maltotriosyl-maltose, respectively. Time course study of BOS production suggested that the hydrolysis and transglycosylation reactions catalyzed by BLMA were coupled. BLMA was likely to transfer a sugar moiety hydrolyzed from a non-reducing end of maltooligosaccharide, mainly maltose, to another moiety of sugar via the formation of α-1,6-linkage. Immobilization of BLMA was attempted as an effort to achieve a continuous process for BOS production. the immobilized enzyme showed improved thermal stability and slight loss of enzyme activity was observed during repeated usage. 相似文献
43.
In the current study, we investigated the biotransformation of monosodium glutamate (MSG) to gamma-aminobutyric acid (GABA) by the growing and resting cells from an isolated bacterial strain, Lactobacillus brevis. This strain is a high GABA-producing strain that was identified and isolated from natural kimchi. We gathered the experiment results by design of response surface methodology (RSM) for optimum condition for GABA production and results indicated the optimum culture temperature (35°C) and culture time (58 h). Using resting cells from the same culture batch in the substrate-containing buffer, approximately 3.98 g/l of GABA was produced at a conversion rate of 65.6%. GABA-treated mice showed significantly increased sleep duration compared to that of a control group (p < 0.05) in the pentobarbital-induced sleep test using a hypnotic dose. These results suggest that biotransformed GABA could potentially be used a novel nutraceutical supplement for sleep. 相似文献
44.
The inhibitory effects of lipid accumulation on ethanol extract from stem bark of Japanese horse chestnut (JHC) were evaluated. Exposure to JHC extract (10–100 μg/mL) for a 72 h incubation period did not alter cell viability compared to the untreated control. JHC extract, with concentrations of 25, 50, and 100 μg/mL, inhibited lipid accumulation in 3T3-L1 adipocytes in a dose dependent manner. The expression of PPARγ and C/EBPα, important adpogenic key markers was significantly reduced when JHC extract was added to cells for 8 days compared with the untreated control group. These results suggest that JHC extract might be a potential therapeutic agent as a natural anti-obesity material. 相似文献
45.
目的探讨应用覆膜支架介入治疗颈动脉破裂并假性动脉瘤.方法4例肿瘤所致颈动脉破裂并假性动脉瘤形成的患者,均出现颈部或口腔危及生命的出血,采用Seldinger方法,选用自膨式聚四氟乙烯覆膜支架治疗.结果4例成功施行血管内介入治疗,其中颈总动脉中段1例,颈动脉球2例,颈总动脉远段1例.共置入覆膜支架6枚.术后假性动脉瘤腔被隔绝,颈动脉通畅,患者的临床症状明显改善,无神经功能障碍.1例患者11 d后支架下缘颈总动脉与原瘤腔相通,再次置入覆膜支架,2个月的随访无再出血.1例患者经钢圈栓塞、放置覆膜支架及裸支架瘤腔 相似文献
46.
Young Cheol Ryu Tae Gun Kim Guem-Seok Seo Jin Hwan Park Cha Soo Suh Seong-Soo Park Seong-Soo Hong Gun Dae Lee 《Journal of Industrial and Engineering Chemistry》2008,14(2):213-218
The TiO2/substrate pearlescent pigments were prepared by the hydrolysis of TiOCl2 on the substrate followed by a calcinations process. The natural mica (muscovite), synthetic mica (fluorophlogopite) and -alumina flake were selected as the substrates for pearlescent pigments. The effect of substrate on the anatase to rutile (A–R) phase transformation of TiO2 was studied. The A–R phase transformation of TiO2 during the preparation of pearlescent pigments and their proportion in the TiO2 layer have been analyzed by XRD measurements. The phase compositions of TiO2 layer in each pearlescent pigment are quite different depending on the substrates. The TiO2 layer deposited on -alumina has higher rutile fraction than those on the natural and synthetic mica. The XPS analysis showed that the cations originally present in the substrates diffused into the TiO2 layer. The TiO2 layer deposited on -alumina contains Al, while those on the natural and synthetic mica substrates contain Si and K in addition to Al. The metal cations diffusing from the substrate into TiO2 layer might retard the A–R phase transformation of TiO2. The suppressing effect on the A–R transformation of TiO2 by mixed cations seems to be much stronger than that of single cation, resulting in relatively higher rutile fraction in the case of TiO2 layer deposited on -alumina. 相似文献
47.
Low-temperature mechanical behaviors have been investigated for the constituent materials of superconducting radio frequency cavities. Test materials consist of small grain Nb, single crystal Nb, large grain Nb (bicrystal), Ti45Nb-Nb weld joint (e-beam welded), and Ti-316L bimetal joint (explosion welded). The strength of all test metals displayed strong temperature dependence and the Ti-316L bimetal showed the highest strength and lowest ductility among the test materials. The fracture toughness of the small grain Nb metals decreased with decreasing test temperature and reached the lower shelf values (30-40 MPa √m) at or above 173 K. The Ti45Nb base and Ti45Nb-Nb weld metals showed much higher fracture toughness than the small grain Nb. An extrapolation and comparison with existing data showed that the fracture toughness of the small grain Nb metals at 4 K was expected to be similar to those at 173 and 77 K. The results from optical photography at a low magnification and fractography by a scanning electron microscope were consistent with corresponding mechanical properties. 相似文献
48.
49.
Jeong Ji-Seong Song Min-Ho Lee Sang-Ho Kim Mihye Baek Nakhoon Yoo Kwan-Hee 《The Journal of supercomputing》2019,75(8):4505-4518
The Journal of Supercomputing - This paper presents a web-based three-dimensional (3D) navigation system for a spinal disease ontology using a 3D virtual human spine. The 3D navigation system... 相似文献
50.
Intelligent Service Robotics - In this study, the goal is to efficiently and actively search for a target object in a previously unknown large-scale environment. To this end, we develop a... 相似文献