同步整流技术的特点与分析比较

同步整流技术在低压大电流开关模块电源领域得到了广泛的应用。本文从从器件、电路结构以及工作方式等三个不同的角度,对同步整流技术进行了分析和比较,以便于能够更好的理解和应用同步整流技术。     

米糠浸出油厂糠粞分离的必要性及其工艺探讨

糠粞分离是米糠油制取的重要工序之一。从提高经济效益,保证正常生产,降低残油和溶耗3个方面阐述了糠粞分离的必要性。介绍了风选和筛选两种糠粞分离方法及各自的优缺点。并着重介绍了风力式糠粞分离系统的工艺设计及设计、安装、操作的关键点。     

三峡三期工程帷幕灌浆施工与工艺管理

介绍了长江三峡三期工程坝基帷幕灌浆按照“自上而下分段、小口径钻孔，孔口封闭，孔内循环”的设计要求进行高压灌浆的施工方法，重点是几个典型工艺管理及其实施效果。     

利用扫描电镜研究三维电极主电极表面腐蚀状况

借助扫描电镜（SEM）对不同实验条件下的三维电极主电极表面腐蚀状况进行研究。结果表明，三维电极主极阳极的内侧腐蚀程度远大于其外侧，水样性质、电极材料性质对电极的腐蚀程度有很大的影响，不锈钢做三维电极主电极优于铝、铁电极。为三维电极主电极的选材提供了一定的理论依据。     

Up-regulation of CIR1/CROC1 expression upon cell immortalization and in tumor-derived human cell lines

Inactivation of 5-HT1A and [3H]5-HT binding sites by N-Ethoxycarbonyl-2-ethoxy-1, 2-dihydroquinoline (EEDQ) was studied in regions of rat brain. After exposure to EEDQ (4 mg/kg body wt.) for 7 days, it is observed that the density of 5-HT1 receptor sites was decreased by nearly 20% in both cortex and hippocampus. The decrease, however, in 5-HT1A sites was more significant (70%) in both the regions. The affinity of [3H]5-HT to 5-HT1 sites was decreased significantly in both cortex and hippocampus after exposure to EEDQ, without affecting the Kd of 5-HT1A sites. Displacement studies suggested that EEDQ has high affinity to 5-HT1 sites with a Ki of 42.9+/-2.4 nM. After exposure neither basal nor 5-HT stimulated adenylyl cyclase activity was changed in cortex. The results of this study suggest that EEDQ decreases the density of 5-HT1 and 5-HT1A receptor sites but does not cause functional downregulation of these sites in rat brain.     

Structural evolution of matrix phase for liquid phase sintered 93W-4.9Ni-2.1Fe

The structure of the matrix of a two phase heavy alloy, 93W-4.9Ni-2.1Fe (wt%), was characterized. The matrix phase was not the expected face centred cubic Ni-Fe-W solid solution with a large grain size reported in the literature. Instead, an amorphous phase containing fine grained crystals as well as intermetallic compounds having different compositions were found. The partition of tungsten from the matrix toward the tungsten phase resulted in formation of different phases in the matrix. Under furnace cooling, the matrix phase was composed of an amorphous phase for the matrix phase remote from the tungsten grain-matrix interfaces, and a strained FeNi intermetallic phase near the interfaces. For specimens solution treated at temperatures between 1000–1400 °C followed by water quenching, an intermetallic phase rich in tungsten, (Ni, Fe) W, evolved and surrounded the tungsten grains in clusters. The relative abundance of this intermetallic phase was highest for a solution treatment temperature of 1400 °C, indicating that the formation of this phase was a result of supersaturation of tungsten in the matrix phase and retarded partition of tungsten from the matrix phase to tungsten grains under a rapid cooling condition.     

One-year prevalence of psychiatric disorder in Ontarians 15 to 64 years of age

OBJECTIVE: To present the one-year prevalence of 14 psychiatric disorders in a community sample of Ontarians aged 15 to 64 years. METHOD: Data on psychiatric disorders were collected on 9953 respondents using the University of Michigan revision of the Composite International Diagnostic Interview (UM-CIDI). DSM-III-R criteria were used to define the psychiatric disorders. RESULTS: Almost 1 in 5 Ontarians (18.6%) had one or more of the disorders measured in the survey. Among 15-to 24-year-olds, 1 in 4 was affected. The distribution of individual disorders varied by sex and age. CONCLUSION: Because of the immense burden of suffering associated with psychiatric disorders, clinical and research efforts in this area should receive high priority within the health budget.     

The relationship between denitrifying bacteria and methanogenic bacteria in a mixed culture system of acclimated sludges

The interaction between denitrification and methanogenesis, with methanol functioning as an electron donor, has been examined through usage of a mixed culture system of denitrifying sludge and methanogenic sludge in an anaerobic bioreactor. Competition for methanol between these two kinds of biocommunity could not be observed, whereas methanogenesis was suppressed as long as nitrate and nitrite were made available in the mixed system. The inhibition of methanogenesis in the methanogenic sludge caused by nitrogen oxides was studied. The redox potential (E_h) of the culture was monitored and/or controlled for the sake of characterizing the behavior of the biocommunities. An addition of nitrite elevated the E_h of the culture less than nitrate did. Nitrite addition, however, exerted a stronger inhibitory effect on methanogenesis as compared to nitrate at the same concentration. The influence of redox potential on the methanation of methanol was examined by using a methanogenic sludge in the E_h-stat batch culture. The hypothesis that the inhibitory effect being expressed by the nitrogen oxides is not simply attributed to an elevation of the redox potential of the culture is supported by the experimental results. The toxic effect of the nitrogen oxides themselves could also have possibly contributed significantly.