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21.
H. de Groot 《Materialwissenschaft und Werkstofftechnik》2007,38(12):965-968
Ischemia‐reperfusion injury of the bone occurs due to traumatic and non‐traumatic alterations affecting blood supply to the bone. It is likely to occur also upon insertion of an implant. Ischemia‐reperfusion injury of the bone has been studied by interruption of blood supply in situ, in limb replantation/transplantation models, in revascularized bone grafts and non‐vascularized bone fragments, as well as in isolated cultured cells. All cells of the bone are affected, including osteoblasts, osteocytes, osteoclasts, chondrocytes, and bone marrow cells. Critical ischemia times for induction of bone cell death, either in the ischemic period or following reperfusion, are in the range of 3 to 7 h. These critical ischemia times are significantly increased by decreasing the temperature from 37 °C to 0–4 °C. Anoxia is the most likely trigger of cell injury in the ischemic phase. In the reperfusion phase, reactive oxygen species are decisively involved in the injurious process. In general, however, the available information on the mechanism of ischemia‐reperfusion injury of the bone is relatively sparse. On the other hand, there are clear similarities to the mechanisms of ischemia‐reperfusion injury known from other organs, and there is a clear potential for protection against ischemia‐reperfusion injury of the bone. 相似文献
22.
臭氧法水处理在空调冷却水系统中的应用 总被引:4,自引:1,他引:3
探讨了臭氧法杀菌灭藻,缓蚀,阻垢的机理,认为臭氧法可用于空调冷却水处理,并给出在工程设计中的应用方法。 相似文献
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Gradient-corrected density functional theory was used to investigate the adsorption of H2S on Pd(1 1 1) surface. Molecular adsorption was found to be stable with H2S binding preferentially at top sites. In addition, the adsorption of other S moieties (SH and S) was investigated. SH and S were found to be preferentially bind at the bridge and fcc sites, respectively. The reaction pathways and energy profiles for H2S decomposition giving rise to adsorbed S and H were determined. Both H2S(ad) → SH(ad) + H(ad) and SH(ad) → S(ad) + H(ad) reactions were found to have low barriers and high exothermicities. This reveals that the decomposition of H2S on Pd(1 1 1) surface is a facile process. 相似文献
25.
震源延迟叠加技术及应用效果 总被引:2,自引:0,他引:2
延迟叠加爆炸是针对高分辨率和深层地震勘探而提出来的一种激发方式。这种激发方式能在保证地震分辨率的前提下有效提高地震波能量 ,在地震波的入射角范围内 ,有效克服非球形炸药激发引起的地震波传播的方向性。应用弹性波动力学对多级延迟爆炸进行理论研究 ,结合实际试验资料 ,研究了延迟爆炸情况下激发参数对地震波能量、主频、频宽等的影响。从几何地震学出发 ,分析了不同时间激发的地震波在地下空间中的干涉情况 ,对其能量传播的方向性进行了研究。理论分析和试验效果表明 ,延迟叠加震源与相同药量的普通震源相比 ,激发地震波的主频高 ,频带宽 ,增强了下传能量 ,降低了次生干扰 ,在高分辨率和深层地震勘探中具有明显的优势。 相似文献
26.
Flammability ranking of foliage species by factor analysis of physical and chemical pyric properties
In this paper, factor analysis is introduced to evaluate the flammability of 55 foliage species that may be used in China for construction of the fuel break network of forest strips with lower flammability. Six pyric parameters, i.e. air dry moisture content, absolute dry moisture content, ignition point, ash content, caloric value and extractive content, are measured and used as variables for factor analysis. The covariance analysis shows that four principal factors can be extracted to reflect the flammability in different physical and chemical senses. In terms of the contributions of the four factors to the variances and the physical significance of the relevant parameters, the four factors are, respectively, termed as ‘flaming factor,’ ‘air dry factor,’ ‘ash factor’ and ‘absolute dry factor.’ The stability of the factor analysis method is examined by a different number of samples considered, and the variation degrees of the orderings indicate that the method has high reliability to measure the total flammability of foliage species. The results of the flammability evaluation are verified by comparison with the recommended tree species in the Chinese technology standard. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
27.
The Wabash River Integrated Methanol and Power Production from Clean Coal Technologies (IMPPCCT) project is investigating an Early Entrance Coproduction Plant (EECP) concept to evaluate integrated electrical power generation and methanol production from coal and other carbonaceous feedstocks. Research, development and testing (RD&T) that is currently being conducted under the project is evaluating cost effective process systems for removing contaminants, particularly sulfur species, from the generated gas which contains mainly synthesis gas (syngas), CO2 and steam at concentrations acceptable for the methanol synthesis catalyst. The RD&T includes laboratory testing followed by bench-scale and field testing at the SG Solutions Gasification Plant located in West Terre Haute, Indiana. Actual synthesis gas produced by the plant was utilized at system pressure and temperature for bench-scale field testing. 相似文献
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通过田间小区试验,研究了长期不同施肥对田间杂草总密度、优势杂草组成及生物多样性的影响。结果表明:综合施用N、P、K肥,不仅降低了田间杂草的总密度,降低了优势杂草在群落中的比重,而且有利于维持田间杂草的生物多样性;不施用N或P肥,田间杂草的总密度增大,优势杂草的比重也明显增强,但不利于维持田间杂草的生物多样性。所以,平衡施用N、P、K肥,有利于维持农田生态系统中的生物多样性,并能更好地进行杂草控制。 相似文献
30.
H. Launay S. Loridant D.L. Nguyen A.M. Volodin J.L. Dubois J.M.M. Millet 《Catalysis Today》2007,128(3-4):176-182
New vanadium oxide supported on mesoporous silica catalysts for the oxidation of methane to formaldehyde were investigated by infrared and Raman spectroscopies to identify and characterize the molecular structure of the most active and selective catalytic sites. In situ and operando experiments have been conducted in order to understand the redox and hydroxylation/dehydroxylation processes of the vanadium species. (SiO)2VO(OH) species were identified in these catalysts in reaction conditions and shown to undergo a deprotonation at 580 °C under vacuum, leading to a site giving a photoluminescence band at 550 nm attributed to reverse radiative decay from the excited triplet state:
(V4+–O−)* (V5+O2−). An activation mechanism of vanadium monomeric species with electrophilic oxygen species is proposed. 相似文献