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排序方式: 共有436条查询结果,搜索用时 15 毫秒
81.
Shinya Takata Tomo Ogura Eiichi Ide Toshiaki Morita Akio Hirose 《Journal of Electronic Materials》2013,42(3):507-515
The effects of reducing solvents on the bonding process using silver oxide paste in a copper joint were investigated. Three solvent types were tested: diethylene glycol (DEG), triethylene glycol (TEG), and polyethylene glycol (PEG). The strength of the joints was assessed by fracturing, which occurred at the interface of the copper oxide layer and the copper substrate in DEG and TEG samples and at the bonded interface in the PEG sample. Analysis of the samples revealed that, in the DEG and TEG samples, the copper substrate was oxidized during the bonding process, which compromised the shear strength of the joints. In contrast, the PEG sample exhibited nonuniform sintering of the silver layer while retaining good shear strength. It was found that the combination of DEG and PEG produced optimum shear strength in the copper joint, as PEG suppressed the growth of copper oxide and DEG promoted the formation of a dense sintered silver layer. The bonding strength achieved was higher than that of the gold-to-gold joint made using standard Pb-5Sn solder. 相似文献
82.
83.
In this paper, an adaptive simulated annealing genetic algorithm is proposed to solve generation expansion planning of Turkey's power system. Least‐cost planning is a challenging optimization problem due to its large‐scale, long‐term, nonlinear, and discrete nature of power generation unit size. Genetic algorithms have been successfully applied during the past decade, but they show some limitations in large‐scale problems. In this study, simulated annealing is used instead of mutation operator to improve the genetic algorithm. The improved algorithm is applied to the power generation system with seven types of generating units and a 20‐year planning horizon. The planning horizon is divided into four equal periods. The new algorithm provides approximately 6.6 billion US$ (3.2%) cheaper solution than GA and also shows faster convergence. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
84.
Oxidation of low density lipoprotein (LDL) has been recognized as playing an important role in the initiation and progression of atherosclerosis. In this study, the effects of aged garlic extract and one of its major compounds, S-allylcysteine, on oxidized LDL-induced cell injury were studied. Pulmonary artery endothelial cells were pre-incubated with the garlic extract (1, 2.5 and 5 mg mL-1) or S-allylcysteine (0.1, 1, 10 and 20 mM) at 37 degrees C and 5% CO2 for 24 h, washed, and then exposed to 0.1 mg mL-1 oxidized LDL for 24 h. Lactate dehydrogenase release as an index of membrane damage, methylthiazol tetrazolium assay for cell viability and thiobarbituric acid reactive substances indicating lipid peroxidation were determined. Preincubation of endothelial cells with the extract or S-allylcysteine significantly prevented membrane damage, loss of cell viability and lipid peroxidation. The data indicate that these compounds can protect vascular endothelial cells from injury caused by oxidized LDL, and suggest that they may be useful for prevention of atherosclerosis. 相似文献
85.
Patients with rheumatoid arthritis (RA) develop both periarticular and generalized osteoporosis. Periarticular osteopenia in appendicular bones occurs early in the course of RA and is one of the earliest radiological signs of RA. An uncoupled state in bone resorption-formation linkage, contributes to the development of periarticular osteopenia and it might be mediated through an increased productions of cytokines and prostaglandins by synovium and bone marrow. Accordingly, early suppression of rheumatoid synovitis is necessary for the prevention of periarticular osteopenia. Generalized osteoporosis is also common in RA and leads to increased risk of fractures. Generalized osteoporosis considered to be multifactorial and factors contributing to lumbar osteoporosis might be different from those to loss of appendicular bones, such as femur and radius. Corticosteroids and menopausal state are important risk factors for lumbar osteoporosis. Rheumatoid activity and reduced physical activity are also important determinants. According to the previous studies, however, the influence of functional impairment is more prominent in the femoral BMD compared to spinal BMD. In addition to control of RA and maintenance of physical activity, hormone replacement therapy (HRT) and bisphosphonate are possible agents for the treatment of osteoporosis in RA patients, especially postmenopausal women. 相似文献
86.
T Yamakawa H Nagoshi A Takahashi R Fukumura S Takahashi M Nomura H Isobe K Ide T Ayabe S Shimizu 《Canadian Metallurgical Quarterly》1995,36(10):1175-1181
A 55-year-old patient with multiple myeloma (IgG-lambda) diagnosed in November 1988 was admitted because of bone pain throughout the body. After plasmapheresis and several courses of chemotherapy, a massive tumor of the left thoracic wall involving the rib appeared. Radiotherapy was performed to ameliorate the severe chest pain, after which myelomatous pleural effusion appeared on the left side. The serum, urine and pleural effusion revealed increased activity of amylase of the salivary type. Amylase activity was also detected in the supernatant of myeloma cells cultured from pleural effusion. We reviewed 12 cases of ectopic amylase-producing multiple myeloma. All the cases except one have been reported from Japan, and hyperamylasemia in these cases was detected at diagnosis or during course of the illness. Moreover, cytogenetic analysis of myeloma cells of previous reports revealed structural abnormalities including chromosome 1, near the amylase gene locus. This case also showed t (1; 10) (q 21?; q 26) by examination of 8 metaphase derived from bone marrow. These observations suggested that ectopic amylase production was induced by irradiation to the plasmacytoma of thoracic wall. 相似文献
87.
88.
89.
T Ide 《Canadian Metallurgical Quarterly》1997,24(11):1600-1605
Human normal somatic cells and tissues have undetectable or very weak telomerase activity and shorten telomere size at each cell division resulting in a limited proliferative life span. Human germ tissues and most tumor tissues have telomerase activity and maintain telomere size during cell proliferation resulting in unlimited growth. Telomerase is expected to be a new target for cancer chemotherapy. Cultured tumor cells are shown to die after losing telomerase activity. 相似文献
90.
Reaction sintering of an Fe-6 Wt Pct B-48 Wt Pct Mo alloy in the presence of liquid phases 总被引:14,自引:0,他引:14
The mechanism of liquid phase sintering of an Fe-6 wt pct B-48 wt pct Mo alloy was investigated by means of thermal dilatometry,
differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). A fine composite microstructure
of Mo2FeB2 and ferrite was produced from powders of Fe, Mo, and FeB by a reaction sintering process involving two liquid phases. The
hard phase Mo2FeB2 is produced in the compact prior to liquid formation initially by the reaction 2Mo+2FeB=Mo2FeB2+Fe and later by the reaction 2Mo+2Fe2B=Mo2FeB2+ 3Fe. Above 1365K, considerable densification results from the initial stage rearrangement of the solid phases (austenite
and Mo2FeB2) coexisting with the first formed liquid phase (L1). Another liquid (L2) which forms above 1415K, where Mo2FeB2 is the only coexisting solid phase, is required for complete densification. L2, having a high solubility for Mo2FeB2, provides for solution/reprecipitation processes which characterize the intermediate stage of liquid phase sintering. The
effective separation of the initial and intermediate stages by L1 and L2 is considered essential for the control of the sintered microstructure of the ternary alloy.
Teiichi Ando, formerly with the Technical Research Laboratory, Toyo Kohan Co., Ltd., is with the Department of Materials Science
and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139. 相似文献