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81.
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Electron beam melting of vanadium at total dynamic pressures of less than 10?9 has been shown to reduce the oxygen content. Internal friction analyses and chemical analyses show good agreement. The purification is attributed to the metallic vapor envelope around the molten zone which may have the effect of reducing the partial pressure of oxygen below 10?13 adjacent to the molten metal and also to the vaporization of VO molecules from the surface of the molten zone. Three stages of work hardening have been shown to exist in vanadium. However, a small interstitial concentration is required to observe stage II. Optical microscope examination reveals that secondary slip lines appear as stage II proceeds. The maximum rate of work hardening of 14 kg per sq mm is in good agreement with the rate of work hardening observed in other bcc metals. 相似文献
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Yudong Tian Yuqiong Liu Kristi R. Arsenault Ali Behrangi 《International journal of remote sensing》2013,34(13):4940-4951
Current satellite-based remote-sensing approaches are largely incapable of estimating precipitation over snow cover. This note reports a proof-of-concept study of a new satellite-based approach to the estimation of precipitation over snow-covered surfaces. The method is based on the principle that precipitation can be inferred from the changes in the snow water equivalent of the snowpack. Using satellite-based snow water equivalent measurements, we derived daily precipitation amounts for the northern hemisphere for three snow-accumulation seasons, and evaluated these against independent reference datasets. The new precipitation estimates captured realistic-looking storm events over largely un-instrumented regions. However, the data are noisy and, on a seasonal scale, the amount of precipitation is believed to be underestimated. Nevertheless, current uncertainty in snow measurements, albeit large (50–100%), is still lower than direct precipitation measurements over snow (100–140%) and therefore this approach is still useful. The method will become more feasible as the quality of remotely sensed snow measurements improves. 相似文献
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D Mack J Riedewald H Rohde T Magnus HH Feucht HA Elsner R Laufs ME Rupp 《Canadian Metallurgical Quarterly》1999,67(2):1004-1008
Hemagglutination of erythrocytes is a common property of Staphylococcus epidermidis strains, which is related to adherence and biofilm formation and may be essential for the pathogenesis of biomaterial-associated infections caused by S. epidermidis. In three independent biofilm-producing, hemagglutination-positive S. epidermidis isolates, interruption of the icaADBC operon essential for polysaccharide intercellular adhesin (PIA) synthesis by Tn917 insertions led to a hemagglutination-negative phenotype. An immunoglobulin G fraction of antiserum to PIA greatly reduced hemagglutination. Purified PIA led to a 64-fold decrease of hemagglutination titers of these strains; however, it did not mediate hemagglutination by itself. These observations define PIA as the hemagglutinin of S. epidermidis or at least as its major functional component. 相似文献
88.
The primary acquired lactase deficiency of the adult is known to cause various disturbances in the gastrointestinal tract while extraintestinal symptoms are unusual. Here we report on a histologically proven chronic eczema requiring corticosteroid treatment for several months. It was obviously induced by a concomitant lactose intolerance since the introduction of a lactose-free diet led to a complete disappearance of the eczema and allowed the discontinuation of the corticosteroid treatment. As far as we know, this is the first case report of an eczema caused by a lactose intolerance. 相似文献
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HH Al-Sa'doni IL Megson S Bisland AR Butler FW Flitney 《Canadian Metallurgical Quarterly》1997,121(6):1047-1050
1. A study has been made of the effect of neocuproine, a specific Cu(I) chelator, on vasodilator responses of rat isolated perfused tail artery to two nitrosothiols: S-nitroso-N-acetyl-D,L-penicillamine (SNAP) and S-nitroso-glutathione (GSNO). 2. Bolus injections (10 microl) of SNAP or GSNO (10(-7)-10(-3) M) were delivered into the lumen of perfused vessels pre-contracted with sufficient phenylephrine (1-7 microM) to develop pressures of 100-120 mmHg. Two kinds of experiment were made: SNAP and GSNO were either (a) pre-mixed with neocuproine (10(-4) M) and then injected into arteries; or (b) vessels were continuously perfused with neocuproine (10(-5) M) and then injected with either pure SNAP or GSNO. 3. In each case, neocuproine significantly attenuated vasodilator responses to both nitrosothiols, although the nature of the inhibitory effect differed in the two types of experiment. We conclude that the ability of exogenous nitrosothiols to relax vascular smooth muscle in our ex vivo model is dependent upon a Cu(I) catalyzed process. Evidence is presented which suggests that a similar Cu(I)-dependent mechanism is responsible for the release of NO from endogenous nitrosothiols and that this process may assist in maintaining vasodilator tone in vivo. 相似文献