热处理作用下碳钢氢腐蚀裂纹愈合规律

对含氢腐蚀裂纹的碳钢进行再热处理后,SEM观察表明,氢蚀裂发生了不同程度的愈合,实验结果表明：长度约为10μm的碳钢氢蚀裂纹完全愈合的热处理条件下是从室温到1000℃热循环5次,共10h,氢蚀裂纹的愈合机制是热扩散,发生氢蚀裂纹愈合的动力是氢蚀气泡或裂纹长大导致的塑性变 能E8。在铁、碳和氢原子扩散都足够快的情况下,氢蚀裂纹愈合的条件是E8大于裂纹愈合所必须克服的表面张力能。     

Phosphonate utilization by the globally important marine diazotroph Trichodesmium

The factors that control the growth and nitrogen fixation rates of marine diazotrophs such as Trichodesmium have been intensively studied because of the role that these processes have in the global cycling of carbon and nitrogen, and in the sequestration of carbon to the deep sea. Because the phosphate concentrations of many ocean gyres are low, the bioavailability of the larger, chemically heterogeneous pool of dissolved organic phosphorus could markedly influence Trichodesmium physiology. Here we describe the induction, by phosphorus stress, of genes from the Trichodesmium erythraeum IMS101 genome that are predicted to encode proteins associated with the high-affinity transport and hydrolysis of phosphonate compounds by a carbon-phosphorus lyase pathway. We show the importance of these genes through expression analyses with T. erythraeum from the Sargasso Sea. Phosphonates are known to be present in oligotrophic marine systems, but have not previously been considered to be bioavailable to marine diazotrophs. The apparent absence of genes encoding a carbon-phosphorus lyase pathway in the other marine cyanobacterial genomes suggests that, relative to other phytoplankton, Trichodesmium is uniquely adapted for scavenging phosphorus from organic sources. This adaptation may help to explain the prevalence of Trichodesmium in low phosphate, oligotrophic systems.     

流化床燃烧工况下N_2O生成机理的试验研究

在一个小型固定床反应器上对流化床煤燃烧温度下Ｎ＿２Ｏ均相和多相生成机理进行了试验研究。研究表明，ＮＨ＿３氧化形成的Ｎ＿２Ｏ量很少，其主要产物是ＮＯ，当增加Ｏ＿２浓度时，Ｎ＿２Ｏ略有增加，在９５０℃左右时，Ｎ＿２Ｏ量最大，而在８８０℃时，ＮＯ量最大。焦炭直接燃烧能形成一定量的Ｎ＿２Ｏ，ＮＯ能在焦炭表面还原成Ｎ＿２Ｏ，氧化性气氛下，焦炭的还原能力降低。最后，对煤焦生成Ｎ＿２Ｏ的多相反应机理进行了讨论。     

急性肝功能衰竭的猪动物模型

目的：建立一个比较接近人类条件的急性肝衰竭模型。用于人工肝脏治疗的疗效和安全性的测试。方法：以右旋半乳糖来制造猪肝衰竭的大型动物模型,分组３组给药,剂量分别为０．５、１和０．７５g/kg。观察其临床表现、生理生化指标和病理改变。结果：３组实验都能引出与人的临床和生化指标变化相伫的肝功能衰竭的表现,以０．７５g/kg组最为理想。结论：以０．７５g/kg的半乳糖胺制造的急性肝功能衰竭的猪动物模型,符合人工肘脏研究对动物模型的要求。     

局部遮挡目标的识别

提出一种局部遮挡目标的识别方法。该方法利用多边形近似方法将目标轮廓分段，抽取目标轮廓每一小段的不变矩作特征，利用动态规划技术在段间距离表中寻找最佳路径，确定所有的匹配对，这些匹配对序列构成了目标与模型的局部匹配，可从局部匹配中计算匹配可信度。该方法简单、有效、抗噪声能力较强，是一种较好的局部目标识别方法。