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61.
Before use of cardiovascular surgical techniques and procedures in humans, many experiments, e.g., hypothermic circulatory arrest and cardiopulmonary bypass using the heart-lung machine, have been performed in the dog. As a consequence experimental canine cardiovascular surgery is highly developed. This has not resulted in the routine performance of open heart surgery in veterinary medicine, probably because of the high costs. Cardiovascular surgery in the dog is generally limited to interventions not depending on hypothermic circulatory arrest or cardiopulmonary bypass. The clinical cardiovascular surgery in dogs can be divided into routine and more specialized interventions. The first category includes correction of peritoneopericardial diaphragmatic hernia, pericardial fenestration in dogs with pericardial effusion, treatment of persistent right aortic arch, and patent ductus closure. The specialized interventions include dilation of pulmonic and aortic stenoses and pacemaker implantation. The diagnosis and surgical treatment of such diseases is described. New developments in cardiovascular surgical treatment that can be expected include catheter techniques for occlusion of shunts and dilations using balloons, because the financial costs of these procedures are not prohibitive.  相似文献   
62.
We used KO mice lacking either TNF receptor 1 (TNFR-1) or receptor 2 (TNFR-2) to determine whether signaling at the start of liver regeneration after partial hepatectomy (PH) involves only one or both TNF receptors and to analyze in more detail the abnormalities caused by lack of TNFR-1 receptor, which is required for the initiation of liver regeneration. Lack of TNFR-2 had little effect on NF-kappaB and STAT3 binding, and no effect in interleukin-6 production after PH, but caused a delay in AP-1 and C/EBP binding and in the expression of c-jun and c-myc messenger RNA (mRNA). In contrast to mice lacking TNFR-1, which had deficient hepatocyte DNA synthesis and massive lipid accumulation in hepatocytes, TNFR-2 KO mice had normal liver structure and similar levels of hepatocyte DNA replication as those of wild type mice. We conclude that TNFR-1, but not TNFR-2, is necessary for liver regeneration, and that NF-kappaB and STAT3 binding are activated by signals transduced by TNFR-1. Inhibition of AP-1 and C/EBP binding and in the expression of c-jun and c-myc mRNA in the first 4 hours after PH, as well as the apparent lack of Fos in AP-1 complexes, had no effect on the timing or extent of DNA replication.  相似文献   
63.
Stationary projectors mainly used in system applications have recently gained a wider application range, including general presentations in halls and large conference rooms and being used, for example, in digital signage and for monitoring purposes. Consequently, they are required to meet new market demands for durability, reliability, and flexibility in installation in addition to their conventional basic performance such as especially high brightness. To achieve especially high brightness, a new optical system with two lamps is proposed; the profile of the cover glass that prevents the glass from scattering is made aspherical, the profile of the beam‐combining mirror is improved with its position optimized, and the size of the incident plane of the integrator rod is made larger (1.1 times). These measures resulted in an optical system of an even higher efficiency with 7000 lm, which is the highest in its class (according to a June 2010 investigation). Also, the arrangement of two parallel lamps completely eliminated the effect of heat passing from one lamp to the other, which helped secure durability, reliability, and flexibility in installation. Furthermore, the combined use of the unique non‐telecentric optical system, adopted from the conventional single‐lamp model, helps maintain the class‐highest contrast ratio.1,2  相似文献   
64.
Measurements of the thermal conductivities of the frozen layer of aqueous binary solutions have been performed using the transient hot-wire method. Solutions of ethylene glycol and sodium chloride were utilized as the testing fluids, and they were frozen up in the test section in which the platinum wires 40 m in diameter and 170 mm in length were strung. Measurements were carried out under equilibrium at a variety of both the initial concentration of the solution and the temperature of the frozen layer. The expressions of the thermal conductivity of the frozen layer were determined. It was found that the thermal conductivity of the dendritic ice layer was favorably assessed with the Lichteneker's model by introducing the solid fraction under an assumption of the equililbrium within the range of parameters examined.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.  相似文献   
65.
The fenestrated endotheliocyte of peritubular and glomerular capillaries in rat and mouse kidneys were observed with SEM and TEM. In the glomerular capillary, so-called "pored-domes" were found not only at the fenestrated areolae but also at the nuclear region of the endotheliocyte. At the region between filtration surface and nuclear region, they accumulated to construct a sponge-like structure. The endotheliocyte of peritubular capillary also showed small "pored-domes". The size and morphology of the pores in the "pored-domes" of glomerular and peritubular capillaries were similar to those of areolae fenestratae of the respective capillary. Based on the findings, we assumed that pored-domes and the sponge-like structure are the reservoir for the fenestrated area of the endotheliocyte to accommodate the rapid expansion of capillary lumen.  相似文献   
66.
采用家电行业常用的人工加速光老化实验方法,对目前空调面板常用的白色ABS材料进行了光老化研究,一方面比较了色母料和改性料方案的耐光老化性能,另一方面比较了常用光老化试验方法严酷程度.研究表明:改性料方案耐光老化性能优于色母料;采用氙灯光老化(X)、紫外光老化UVA(ZA)和紫外光老化UVB(ZB)等三种常用试验方法时,实验样品对光老化的响应程度依次为:UVB(ZB)测试>UVA(ZA)测试>氙灯(X)测试.  相似文献   
67.
Alzheimer’s disease (AD) is an age-related and progressive neurodegenerative disorder. It is widely accepted that AD is mainly caused by the accumulation of extracellular amyloid β (Aβ) and intracellular neurofibrillary tau tangles. Aβ begins to accumulate years before the onset of cognitive impairment, suggesting that the benefit of currently available interventions would be greater if they were initiated in the early phases of AD. To understand the mechanisms of AD pathogenesis, various transgenic mouse models with an accelerated accumulation of Aβ and tau tangles have been developed. However, none of these models exhibit all pathologies present in human AD. To overcome these undesirable phenotypes, APP knock-in mice, which were presented with touchscreen-based tasks, were developed to better evaluate the efficacy of candidate therapeutics in mouse models of early-stage AD. This review assesses several AD mouse models from the aspect of biomarkers and cognitive impairment and discusses their potential as tools to provide novel AD therapeutic approaches.  相似文献   
68.
Based on the discussion that there should be a micromechanism that causes a macroscopic slip of mono-crystal copper, molecular dynamics simulations with the analytical displacement feld around a crack tip have been carried out. The result of the simulation shows that macroscopic shear slip in an f.c.c. mono-crystal copper occurs as discrete time events. This is because cross-slips occur in many places in a material such that a macroscopic shear slip is blocked until some critical state of deformation. A macroscopic shear slip then occurs suddenly at the critical state in which the area of disordered atomic arrangement has stretched from one end of a crystal to the other end. The reason why macroscopic shear slips occur in the directions of the slip planes of a crystal is attributed to the fact that the areas of disordered atomic arrangement develop only along those directions.  相似文献   
69.
For the purpose of estimating the reaction mechanism of the direct ethoxylation of a fatty ester in the presence of an Al-Mg composite oxide catalyst, a labeled fatty methyl ester C11H23CO18OCH3 containing 18O isotope was synthesized and directly ethoxylated. The product was evaluated by gas chromatography-mass spectrometry (GC-MS). The GC-MS spectra showed that the 18O isotope label was present only in the methoxy group at the molecular end of the ethoxylated fatty methyl ester. This supports the reaction mechanism of coordination anionic polymerization where the bond between the acyl and methoxy groups of the fatty methyl ester molecule was broken, caused by the bifunctional effect of the acid-base active sites; an intermediate chemisorption species was formed; and then ethylene oxide was addition-polymerized sequentially, in parallel.  相似文献   
70.
The performance of poly-β-naphthalene sulfonate condensate superplasticizer (BNS) as a dispersant for cement in concrete is affected severely by slight differences in the characteristics of the cement. In order to be able to predict these effects, a model for estimating the fluidity of cement paste containing BNS is proposed. This model is based on an assumption that the fluidity of cement paste is proportional to the BNS adsorption amount per surface area of hydrated cement (Ad/Hy). BNS is known to show two types of sorption on hydrated cement: one is the bulk absorption into initial hydrates and the other one is the superficial adsorption onto hydrates. Only the superficially adsorbed BNS is expected to work as a dispersant. By assuming a competitive Langmuir-type adsorption on hydrates between BNS and SO42−, a simple method to estimate Ad/Hy is developed, with the concentrations of BNS and SO42− as the only two independent parameters. The resulting estimates of Ad/Hy show a good correlation with paste flow and its change with elapsed time for a broad range of cements. The SO42− concentration in the aqueous phase of the cement paste just after the beginning of the mixing is known to affect the performance of BNS as a dispersant. By using the proposed model to discriminate between the superficial adsorption and bulk absorption of BNS, this phenomenon is explained quantitatively.  相似文献   
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