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51.
52.
During clot retraction, platelets interact with fibrin resulting in marked reduction of clot volume. Altered fibrin structure has been reported to affect clot retraction as measured by serum expression. This study was performed to test whether such altered retraction was the result of increased resistance to network collapse or due to decreased force development by platelets. Altered fibrin structure was documented as variation of fibre mass/length ratios (mu) and shifts in clot elastic modulus. The force developed by platelets during clotting was measured directly. Increasing the fibrinogen concentration led to thinner fibre formation (decreased mu), and a linear increase in gel elastic modulus. Over a fibrinogen concentration range of 100 to 400 mg/dl, force development was minimally affected. Force development and clot elastic modulus increased in a linear fashion with increasing platelet concentration. Increasing the calcium concentration from 5 to 20 mM caused a 160% increase in fibrin fibre size (mu), and a 52% decline in clot modulus. Force developed at 1200 s declined by 17%. At 15 mg/ml, dextran and hydroxyethyl starch (HES) also increased mu, and decreased clot modulus; however, both agents markedly reduced force development. Increasing ionic strength or the addition of IgG decreased mu and increased gel elastic modulus. Force development increased modestly with increased ionic strength, did not change with addition of IgG in saline and declined with addition of IgG in maltose. This study indicates that force development is primarily dependent on platelet function while clot modulus depends on both fibrin structure and platelet function.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
53.
Restoration of motor function in the hand is difficult in brachial plexus injuries in which the C5, 6, 7 and 8 roots are involved, because there are insufficient motors available for transfer to restore the extensors of the fingers and wrist. We have used extensor digitorum tenodesis in 11 cases and found it effective and simple.  相似文献   
54.
The oxidation behavior of chromium and the corrosion behavior of austenitic stainless steel in boiling nitric acid solution containing highly concentrated nitrates were investigated using UV-visible spectroscopic measurements, Raman spectral measurements, immersion tests, and potentiodynamic polarization measurements. The oxidation rate measurement of chromium from Cr(III) to Cr(VI) was performed by 1 M boiling nitric acid solution containing each highly concentrated nitrates: Al(NO3)3, Nd(NO3)3, Ca(NO3)2, Mg(NO3)2, and NaNO3 as a simulant of uranium nitrate in uranium concentrator in reprocessing plants. As a result, the rate of chromium oxidation was different depending on the added nitrates even at the same nitric acid concentration. In addition, the oxidation rate of chromium was increased with increasing the calculated partial pressure of nitric acid in consideration of the hydration of cation of nitrates. Furthermore, the corrosion rate of type 310 stainless steel was accelerated by the solution having a high chromium oxidation rate containing nitrates. These results indicated that the acceleration of the corrosion rate in the solutions depending on the oxidation rate of chromium, and the rate is affected by the salt-effect of nitrates.  相似文献   
55.
为查明水力压裂实验所产生的人工裂隙网络区域的地应力场和局部构造特征,分析了1995~1996年在Soultz 干热岩(HDR)地热田水力压裂实验中获得的声发射数据,通过倒频谱解析法,检出近接型相似微地震对,对其进行时间-倒频率分析,结合时间-倒频率-倒频谱表示图,判断出了P波的到达时间间隔,最后标定出近接型相似微地震对的相对震源坐标,判断出人工裂隙网局部的裂隙进展方向.  相似文献   
56.
Heterotrophic marine protists known as thraustochytrids can synthesize polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA). The biosynthetic pathways of PUFAs in thraustochytrids are poorly understood, however. In this study, we attempted to reveal the enzymes involved in DHA synthesis in thraustochytrids. Nine thraustochytrid strains representing 3 genera (Aurantiochytrium, Schizochytrium, and Thraustochytrium) were used for PCR-based detection of the genes encoding Δ5-elongase and Δ4-desaturase and for fatty acid analysis. The degenerate primers were designed to amplify the Δ5-elongase and Δ4-desaturase genes, and the partial sequences of the enzymes were obtained from the genera Thraustochytrium and Schizochytrium. These fragments were identical to those of known Δ5-elongase and Δ4-desaturase. Neither Δ5-elongase nor Δ4-desaturase was detected in the strains belonging to the genus Aurantiochytrium, however, suggesting that this group likely synthesizes DHA not via the elongation/desaturation pathway but via an alternate pathway such as the polyketide synthase pathway. The fatty acid profiles of thraustochytrids were consistent with the presence of genes involved in PUFA biosynthesis in thraustochytrid genera. Thus, our findings suggest that two biosynthetic pathways for PUFAs exist in these organisms.  相似文献   
57.
58.
The key issue in this paper is estimating speed of a human. Compared with previous researches on walking speed estimation, we predict the walking intention before gait action. Our proposed hypothesis is that a composite force index is linearly correlated with the intended walking speed. We did two experiments to test the hypothesis. One gives a regression test indicating the intended walking speed has strong linear correlation with the proposed force index; the other tests the linearity by statistical analysis, guaranteeing the tolerance of individual difference. According to the regression and statistics analyses, we built a treadmill-style locomotion interface. Compared with the normal cases of treadmill control, the tested subject does not have to follow the speed of treadmill, but can actively change the speed of treadmill by his/her feet. The designed locomotion interface is applied in a virtual market system. Here the subject walks in a virtual market street with the desired speed. The stereo display based on virtual reality and the ambient sounds of the environment make the subject to have an immersed sense. The layout of shops in the virtual market system is in Japanese style, making the subjects experience much more realistic.  相似文献   
59.
This paper proposed an algorithm on simultaneous position estimation and calibration of omnidirectional camera parameters for a group of multiple mobile robots. It is aimed at developing of exploration and information gathering robotic system in unknown environment. Here, each mobile robot is not possible to know its own position. It can only estimate its own position by using the measurement value including white noise acquired by two omnidirectional cameras mounted on it. Each mobile robot is able to obtain the distance to those robots observed from the images of two omnidirectional cameras while making calibration during moving but not in advance. Simulation of three robots moving straightly shows the effectiveness of the proposed algorithm.  相似文献   
60.
Polystyrene-b-poly(methyl acrylate) (PS-b-PMA) block copolymer with PS volume fraction of 25.2 vol% was synthesized by atom transfer radical polymerization. Non-pretreated silicon wafers were used as the substrates to prepare perpendicular oriented PS cylinders in PMA matrix via solvent annealing which could induce the transformation of spheres to vertically oriented and hexagonally packed cylinders. The spherical microdomains were formed after the evaporation of solvents from the solutions of the block copolymer in selective solvents mixed from methanol, acetone and dichloromethane. The thickness of films could be as thick as 1000 nm, which were much thicker than usual cases and the cylinders came from the directional coalescence of the spheres, thus any pre-treatments of the substrates were not required for perpendicular orientation. The structures were characterized by small angle X-ray scattering (SAXS), transmission electron microscope (TEM), atom force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS).  相似文献   
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