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51.
In the case of a hypothetical severe accident in a nuclear power plant, interactions of gaseous RuO4 with reactor containment building surfaces (stainless steel and epoxy paint) could possibly lead to a black Ru-containing deposit on these surfaces. Some scenarios include the possibility of formation of highly radiotoxic RuO4(g) by the interactions of these deposits with the oxidizing medium induced by air radiolysis, in the reactor containment building, and consequently dispersion of this species. Therefore, the accurate determination of the chemical nature of ruthenium in the deposits is of the high importance for safety studies. An experiment was designed to model the interactions of RuO4(g) with samples of stainless steel and of steel covered with epoxy paint. Then, these deposits have been carefully characterised by scanning electron microscopy (SEM/EDS), electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). The analysis by XPS of Ru deposits formed by interaction of RuO4(g), revealed that the ruthenium is likely to be in the IV oxidation state, as the shapes of the Ru 3d core levels are very similar with those observed on the RuO2·xH2O reference powder sample. The analysis of O 1s peaks indicates a large component attributed to the hydroxyl functional groups. From these results, it was concluded that Ru was present on the surface of the deposits as an oxyhydroxide of Ru(IV). It has also to be pointed out that the presence of “pure” RuO2, or of a thin layer of RuO3 or Ru2O5, coming from the decomposition of RuO4 on the surface of samples of stainless steel and epoxy paint, could be ruled out. These findings will be used for further investigations of the possible revolatilisation phenomena induced by ozone. 相似文献
52.
This study was aimed at providing new insights on the proteomic response of bacterial spores to ultrasound. Data-independent-acquisition method was used to quantify the proteome change of Bacillus cereus spores after ultrasound treatment (200 W). This study revealed that 2485 proteins were extracted from Bacillus cereus spores, most of them were related to metabolism. After ultrasound treatment, the expression of 340 proteins were significantly changed (the fold change ≥ 2 and p < 0.05), of which 207 proteins were significantly down-regulated. KEGG pathway analysis showed that differentially expressed proteins mainly distributed in metabolism pathway, cell process pathway and genetic information processing pathway after ultrasound treatment. Furthermore, this study analyzed the differentially expressed proteins in significant enrichment pathways. In particular, the expression of key proteins in the phosphorylation reaction of spores was significantly decreased after ultrasound treatment. Thus, ATP synthesis rate decreased and the phosphorylation reaction inhibited. Also, the decrease of the expression of key proteins related to the tricarboxylic acid cycle led to the decrease of nutrients metabolism of spores. Ultrasound treatment induced the down-regulation of fatty acid synthetase expression and promoted fatty acid metabolism at the same time. The content of fatty acids decreased in spores consequently. 相似文献
53.
汽车碰撞砼护拦过程的数值模拟 总被引:2,自引:0,他引:2
将汽车与砼护拦简化为刚体,给出了描述碰撞过程中车辆三维空间运动的Euler-Lagrange方程-微分代数方程组,采用半显式外插方法求解上述方程组。数值计算得出的车辆各方向上的最大平均加速度、最大侧倾角、最大俯仰角、车轮沿护拦面的最大爬升值及车辆脱离护拦时的弹出角等结果是从乘员风险和车辆轨迹等多角全面评估砼护拦的安全性能的重要依据。针对美国NewJercy型砼护拦的实际算例与文献结果吻合较好。 相似文献
54.
Elizabeth M. Humston Joshua D. Knowles Andrew McShea Robert E. Synovec 《Journal of chromatography. A》2010,1217(12):1963-1970
Quality control of cacao beans is a significant issue in the chocolate industry. In this report, we describe how moisture damage to cacao beans alters the volatile chemical signature of the beans in a way that can be tracked quantitatively over time. The chemical signature of the beans is monitored via sampling the headspace of the vapor above a given bean sample. Headspace vapor sampled with solid-phase micro-extraction (SPME) was detected and analyzed with comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC × GC–TOFMS). Cacao beans from six geographical origins (Costa Rica, Ghana, Ivory Coast, Venezuela, Ecuador, and Panama) were analyzed. Twenty-nine analytes that change in concentration levels via the time-dependent moisture damage process were measured using chemometric software. Biomarker analytes that were independent of geographical origin were found. Furthermore, prediction algorithms were used to demonstrate that moisture damage could be verified before there were visible signs of mold by analyzing subsets of the 29 analytes. Thus, a quantitative approach to quality screening related to the identification of moisture damage in the absence of visible mold is presented. 相似文献
55.
We discuss models where the Higgs boson of the electroweak standard model plays the role of the inflaton. We focus on the question of the violation of perturbative unitarity due to the coupling of the Higgs boson either to the Ricci scalar or to the Einstein tensor and discuss the background dependence of the unitarity bounds. Our conclusion is that the simplest model which restricts itself to the standard model Higgs boson without introducing further degrees of freedom has a serious problem. However, in the asymptotically safe gravity scenario, the Higgs boson of the standard model could be the inflaton and no physics beyond the standard model is required to explain both inflation and the spontaneous breaking of the electroweak symmetry of the standard model. 相似文献
56.
从“福岛第一核电站事故”看我国核能利用的核安全 总被引:1,自引:0,他引:1
文章简要说明了福岛第一核电站事故的起因、发展和后果,并对核电站全厂断电、反应堆压力容器及安全壳超压、氢爆等导致事故恶化的原因作了分析.文章还就导致福岛核事故的相关因素与我国核电站的安全设计及防范对策进行了分析比较.在吸取福岛核事故的经验教训方面,文章提出了若干值得引发关注的启示,作为我国在建和在役核电站的改进,以及新设计核电站的参考.文章还就我国能源的状况,核能发展的必要性,以及核能发展的方针进行了探讨. 相似文献
57.
分析和评论了2014年美国大学生数学建模竞赛(MCM)A题,以及获得outstanding winner奖的6篇论文。首先对试题进行分析,并结合已有文献指出A题的主要解题思路;然后,通过评述获奖论文,指出学生论文的优点及存在的问题;最后,对今年赛题的某些问题进行讨论。 相似文献
58.
59.
With the finite element method and the limit equilibrium method, a numerical model has been established for examining the
effects of rainfall infiltration on the stability of slopes. This model is able to availably reflect the variations in pore
pressure field in slopes, dead weight of soil, and the softening of soil strength caused by rainfall infiltration. As a case
study, an actual landslide located at the Nongji Jixiao in Chongqing is studied to analyze the effects of rainfall infiltration
on the seepage field and the slope stability. The simulated results show that a deep slope failure is prone to occur when
rainfall infiltration will lead to a remarkable variation in the seepage field, in particular, for large range pore water
pressure increase in slopes.
Supported by the Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KJCX2-SW-L1-4) and the Major State
Basic Research Development Program of China (Grant No. 2002CB412703) 相似文献
60.
Hideaki Asaka Yutaka Kukita Taisuke Yonomoto Yasuo Koizumi Kanji Tasaka 《Experimental Thermal and Fluid Science》1990,3(6):588-596
Three 0.5% cold-leg small-break loss-of-coolant accident (SBLOCA) experiment were conducted at the ROSA-IV Large Scale Test Facility (LSTF) to investigate the effects of break orientation on system thermal-hydraulic responses. In these three experiments, the break hole was located at the side, bottom, and top of the horizontal cold leg, respectively. Although the key phenomena observed in the three experiments were basically the same, the break flow rate was affected by the break orientation when phase stratification occured in the cold leg; the break flow rate was largest for the side break and smallest for the top break. The RELAP5/MOD2 code failed to predict the difference in the break flow rate observed in the experiments. Modification to the break flow calculation models, for both subcooled and two-phase flow discharge conditions, resulted in good agreement between data and predictions. 相似文献