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81.
Kojima Hiroomi Kinoshita Yasuaki Hikita Mitsuaki Tabuchi Toyoji 《Electronics letters》1980,16(12):445-446
Velocity and propagation loss of surface shear waves are measured on free-space and metallised surfaces of LiNbO3 crystals along the x-axis of rotated Y-cut plates as a function of rotation about the x-axis between 35° and 70°. The coupling factor obtained from the velocities is 0.20 for a 35° rotated Y-cut plate and 0.09 for a 70° plate. The coupling factor changes linearly with the rotation angle. The propagation losses over the whole range measured here are less than 5 dB/cm on both free-space and on metallised surfaces. These losses are fairly low and very favourable for fabricating s.a.w. filters. 相似文献
82.
83.
The electrochemical oxidation of a high surface area carbon black (1000 m2/g) was investigated in 96% H3PO4 at 135°C. The total anodic current, the amount of CO2 evolved and the oxygen content of the carbon were all measured as a function of time and potential. Two anodic processes occurred: the formation of a surface oxide and the evolution of CO2. Both decreased with time but at different rates so that CO2 evolution eventually became the major reaction. Various mechanisms to define the corrosion processes are discussed. 相似文献
84.
A comprehensive econometric model was developed to evaluate potential impacts of recombinant bovine somatotropin (rbST) approval in Japan. Three novel features of the analyses include 1) investigation of impact of rbST on herd-size structure, 2) determination of economic feasibilities of rbST adoption by herd size, and 3) evaluation of policies to mitigate negative effects of rbST approval. Simulation analysis was conducted over a 10-yr projected period assuming rbST was approved in Japan in 2001. Nine hypothetical scenarios were simulated to examine sensitivity of simulation results. Simulation results indicate that rbST approval would accelerate structural change in Japan's dairy industry toward fewer, larger farms. Negative effects of rbST on farm income are projected to be more severe for smaller farms, because of higher costs, lower profit-earning ability, lower milk yields, and lower adoption rates of rbST. Larger farms benefit from rbST adoption if milk demand is maintained. However, if concerns about rbST induce significant milk demand decreases, even the largest farms' income and cow numbers will decrease. Thus, Japan's dairy industry could be caught in a double downward spiral of declining milk prices and production. Assuming rbST is approved, small farms would benefit by using the technology, but they fare best if rbST is not approved. Two policies could be effective in mitigating possible farm income losses. First, lost farm income can be offset if dairy cooperatives can exercise greater market power to control fluid milk marketings. Second, because generic milk advertising has positive effects on both milk demand and farm income, increasing check-off rates to fund more advertising could ease farm income losses. 相似文献
85.
86.
Ingestion of plasmalogen markedly increased plasmalogen levels of blood plasma in rats 总被引:1,自引:0,他引:1
Plasmalogens, a subclass of phospholipids, are widely distributed in human and animals, and are taken into the body as food.
However, no data exist on the intestinal absorption or fate of ingested plasmalogen. Here, we determined whether dietary plasmalogen
is absorbed and whether blood and tissue concentrations increased in normal male Wistar rats by using four separate experiments.
Phospholipids containing more than 20 wt% of plasmalogen extracted from the bovine brain were incorporated into test diets
(10–15 wt%). In experiment 1, we estimated the absorption rate by measuring the plasmalogen vinyl ether bonds remaining in
the alimentary tract of rats after the ingestion of 2 g of test diet containing 91 μmol plasmalogen. The absorption rate of
plasmalogen was nearly 80 mol% after 4 h, comparable to the total phospholipid content in the test diet. In experiment 2,
we observed no degradation of the plasmalogen vinyl ether bonds under in vitro conditions simulating those of the stomach and small intestinal lumen. In experiment 3 we confirmed a comparable absorption
(36 mol%) by using a closed loop of the upper small intestine in anesthetized rats 90 min after injecting a 10 wt% brain phospholipid
emulsion. Feeding a test diet containing 10 wt% brain phospholipids for 7 d increased plasmalogen concentration threefold
in blood plasma and by 25% in the liver; however, no increases were seen in blood cells, skeletal muscle, brain, lungs, kidneys,
or adipose tissue (experiment 4). We concluded that dietary plasmalogen is absorbed from the intestine and contributes to
a large increase in plasmalogen levels in blood plasma. 相似文献
87.
A. Maeda K. Kinoshita Y. Inoue H. Kitano T. Nishizaki T. Sato K. Shibata N. Kobayashi 《Journal of Low Temperature Physics》2003,131(5-6):969-973
We investigated the microwave surface impedance in Zn doped YBa2Cu3O
y
. For low Zn concentrations, crossover frequency
p
and viscosity of vortex do not change significantly (at maximum, factor of 2). This is in sharp contrast to the dramatic change in the zero-field quasiparticle scattering time. The robust nature of viscosity on the impurity doping suggests that the quasiparticle scattering time in the vortex core is determined by a different mechanism from that outside the core. 相似文献
88.
Effects of steroid hormones on vascular functions 总被引:6,自引:0,他引:6
The purpose of this review is to present reported findings of effects of steroids on vascular function and to discuss the biological significance in vascular physiology and pathology. Steroid hormones play various roles in vascular functions through the specific receptor localized in the endothelium and underlying vascular smooth muscle cells (VSMCs). Estrogen replacement therapy in postmenopausal women is in general associated with a reduction in mortality from cardiovascular disease and the beneficial effects of estrogens are caused by modulation of lipid metabolism, expression of leukocyte adhesion molecules, and migration of VSMCs in the vascular wall. Estrogens also play a role as vasodilators through an increment in nitric oxide (NO) production in endothelium or modulation of calcium homeostasis in VSMCs. Some progestin molecules partially oppose the effects of estrogens on vascular functions, but striking differences exist among the types of molecules. Testosterone shows a vasorelaxant response, but detailed actions of androgens on vascular functions remain unknown. Glucocorticoids act on vasoconstriction through reduced prostacyclin production, increased alpha-adrenoceptor numbers, and inhibition of NO synthase, while mineralocorticoids induce hypertrophy and hyperplasia of VSMCs and perivascular fibrosis and cause peripheral vascular resistance, in addition to changes in vascular electrocyte permeability. Some rapid actions of steroids are mediated by "nongenomic" responses in vascular tissues. Recent studies have also demonstrated that steroid-producing or -metabolizing enzymes are expressed in the vascular wall, suggesting the local regulation of steroids in the vascular system. Thus, steroid hormones greatly influence vascular functions and an understanding of the mechanisms may provide new means to prevent vascular diseases. 相似文献
89.
中国液态锂铅包层材料研究进展 总被引:2,自引:0,他引:2
黄群英 李春京 李艳芬 刘少军 宋勇 彭蕾 章毛连 朱志强 高胜 郭智慧 王永亮 吴宜灿 周新贵 万发荣 单以银 郁金南 朱升云 张品源 杨建锋 李合琴 巨新 室贺健夫 长坂琢也 大贯惣明 FDS团队 《原子能科学技术》2007,41(Z1):397-406
液态锂铅包层是国际上普遍关注和最有发展潜力的聚变堆包层概念设计之一,而包层材料是液态锂铅包层的核心问题之一.目前,液态锂铅包层普遍选用低活化铁素体/马氏体钢(RAFM钢)作为结构材料,液态锂铅作为中子倍增剂及氚增殖剂.另外,部分设计采用了耐高温、电绝缘流道插件作为功能材料,以降低磁流体动力学效应及提高冷却剂出口温度(高于700℃).为适应液态包层的发展需求,中国科学院等离子体物理研究所FDS团队联合国内外相关研究单位,进行了具有中国自主知识产权的中国低活化马氏体钢(CLAM钢)及液态锂铅包层功能材料研发,并开展了锂铅热对流及强迫对流回路的设计、研制及腐蚀实验研究,以研究液态金属锂铅的流动特性及其与结构和功能材料的相容性.同时建立了聚变堆材料数据库平台,为促进中国聚变堆液态包层及材料技术的研究和发展提供数据支持. 相似文献
90.
Shuji Fukahori Hideaki Ichiura Takuya Kitaoka Hiroo Tanaka Hiroyuki Wariishi 《Journal of Materials Science》2007,42(15):6087-6092
Titanium dioxide (TiO2) powder-containing sheet composites, called TiO2 sheet, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO2 powders were homogeneously scattered over the fiber-mix networks tailored within the catalyst sheet. Under UV irradiation,
the TiO2 paper could decompose p-hydroxyacetophenone (p-HAP), although the degradation efficiency by the TiO2 sheet was lower than that by the TiO2 powder. Scanning electron microscopy revealed that coverage of the TiO2 particles inside the sheet by alumina binder which was used to improve the sheet strength caused the deterioration of the
photocatalytic performance. Internal addition of alumina binder made the TiO2 sheet porous and such a TiO2 sheet exhibited high photocatalytic performance equivalent to that of TiO2 powder. The porous structure of TiO2 sheet might contribute to effective transport of p-HAP to the surface of TiO2 particles inside the sheet, resulting in high degradation performance. In addition, TiO2 sheet prepared using TiO2 sol showed higher photocatalytic efficiency than TiO2 powder and it was indicated that the porous sheet structure might provide suitable conditions for TiO2 catalysis for photodecomposition. 相似文献