Changes in oxygen saturation and transcutaneous carbon dioxide and oxygen levels in patients undergoing fibreoptic bronchoscopy

Though women have a lower absolute risk of disease than men at all ages, almost all the risk factors for cardiovascular disease carry the same or higher relative risk for women as for men. Moreover, the attributable risk is higher in older women than in men. Epidemiologic studies show that recent decreases in coronary heart disease mortality are in some cases greater among women than men. Interventional studies show that women appear to have as good or better a response than men to cholesterol-lowering in secondary prevention. Antihypertensive drug therapy is effective in preventing clinical endpoints in elderly women. These observations imply that an overall estimation of cardiovascular risk in women needs careful consideration. Because established therapies appear to be effective in high risk women, postmenopausal and probably also elderly women are important target groups for preventive efforts. The value of prevention for premenopausal women should not be underestimated, but should on the whole be approached through population-based strategies.     

一种新结构硅微机械压阻加速度计

设计、制造并测试了一种新结构硅微机械压阻加速度计.器件结构是悬臂梁-质量块结构的一种变形.比较硬的主悬臂梁提供了一定的机械强度,并且提供了高谐振频率.微梁很细,检测时微梁沿轴向直拉直压.力敏电阻就扩散在微梁上,质量块很小的挠动就能在微梁上产生很大的应力,输出很大的信号.5 V条件下,灵敏度为14.80 mV/g,谐振频率为994 Hz,分别是传统结构压阻加速度计的2.487倍和2.485倍.加速度计用普通的N型硅片制造,为了刻蚀高深宽比的结构,使用了深反应离子刻蚀(DRIE)工艺.     

Coupling of cobalt-carbon bond homolysis and hydrogen atom abstraction in adenosylcobalamin-dependent glutamate mutase

Adenosylcobalamin-dependent glutamate mutase catalyzes an unusual carbon skeleton rearrangement that proceeds through the formation of free radical intermediates generated by the substrate-induced cleavage of the coenzyme cobalt-carbon bond. The reaction was studied at 10 degrees C with various concentrations of L-glutamate and L-threo-3-methylaspartate and with use of stopped-flow spectroscopy to follow the formation of cob(II)alamin. Either substrate induces rapid formation of cob(II)alamin, which accumulates to account for about 25% of the total enzyme species in the steady state when substrate is saturating. Measurements of the rate constant for the formation of cob(II)alamin demonstrate that the enzyme accelerates the rate of homolysis of the cobalt-carbon bond by at least 10(12)-fold. Very large isotope effects on cob(II)alamin formation, of 28 and 35, are observed with deuterated L-glutamate and deuterated L-threo-3-methylaspartate, respectively. This implies a mechanism in which Co-C bond homolysis is kinetically coupled to substrate hydrogen abstraction. Therefore, adenosyl radical can only be formed as a high-energy intermediate only at very low concentrations on the enzyme. The magnitude of the isotope effects suggests that hydrogen tunneling may play an important role catalysis.     

基于相位相关的指纹拼接方法研究

基于指纹图像的旋转、平移、距离等不变特性,从增加指纹图像的有效特征点出发,提出了指纹拼接方法。该方法分为三步：第一步,提出基于中值滤波及局部属性的归一化预处理算法,去除图像噪声和影响相位相关度准确性的频率信息;第二步,图像进行伪极坐标快速傅立叶变换,根据旋转和平移的不变性,利用相位相关对图像进行快速配准;第三步,对配准的指纹图像完成平滑拼接。大量的实验结果证明本方法可以增加有效的指纹图像特征点数量,改善比对效果,计算复杂度较低,可以实现指纹图像的快速拼接。     

热处理工艺对面条刀具使用寿命的影响

根据面条刀具的加工特点及使用状况,选择适当的预备热处理调质工艺———高的回火温度,以获得较低的调质硬度,然后进行离子氮碳共渗,使面条刀具的使用寿命大幅提高,生产应用表明是可行的。     

Enzymatic specificity and hydrolysis pattern of the catalytic domain of the xylanase Xynl from Rhodothermus marinus

We have investigated the morphology and transfection activity of cationic liposome-DNA complexes (CLDC) under conditions relevant to both in vivo and in vitro studies. Moreover we have attempted to establish structure-function relationships relevant for high transfection activities under both conditions. CLDC were composed of dimethyldioctadecylammonium bromide with either 1, 2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) or cholesterol (Chol) interacting either with pre-condensed DNA or with uncondensed plasmid DNA. Furthermore for steric stabilization 1% poly(ethylene glycol)-phospholipid conjugate was added to CLDC containing Chol and plasmid DNA. The in vivo studies were carried out in mice following i.v. injection, and the in vitro studies were performed on SK-BR-3 human breast cancer cells in the presence of media with serum. The morphology of the CLDC, monitored by freeze-fracture electron microscopy, was investigated after mixing with mouse serum or the medium where the cells were kept. The substitution of DOPE with Chol, and the addition of N-[omega-methoxypoly(oxyethylene)-alpha-oxycarbonyl-DSPE+ ++ are producing CLDC which are stabilized with respect to time and serum, and are relatively small (100-300 nm). These stabilized complexes show high expression of a marker gene in mouse lungs reaching expression values up to 10 ng luciferase per mg tissue protein, but relatively low expression in SK-BR-3 cells in vitro. Additionally, some of the complexes containing pre-condensed DNA look like 'map-pin' structures showing heads of the size of liposomes and short, stiff and tapering tails. The in vivo transfection activity of these preparations is highest. Similar complexes containing DOPE rather than Chol as helper lipid precipitate in the presence of serum and especially of cell medium and convert into hexagonal lipid (HII) phase. Such complexes, despite their high transfection activity in vitro, show very little transfection activity in vivo. These comparisons may help us to understand the fundamental difference between in vitro and in vivo activity of CLDC: high in vitro transfection activity seems to be associated with hexagonal lipid precipitates whereas high in vivo activity seems to be related with small, stabilized complexes, which in our case also exhibit some protrusions (map-pin structures).     

三维软件在选矿设计中的应用

目前选矿厂设计以二维平、断面图和三视图为主,已难以满足现代矿山设计、管理和生产的需要,三维图形的理解要比二维图形容易的多,探索三维造型技术在选矿厂设计中的应用具有重要意义. Ｓｏｌｉｄwｏｒｋｓ软件具有灵活的草图绘制和检查功能、强大的特征建立能力和零件与装配的控制功能、装配设计及动态仿真模拟功能以及色彩渲染和动画模拟等二维软件无法比拟的优点. 通过Ｓｏｌｉｄwｏｒｋｓ自底向上或者自顶向下的设计方法设计出选矿厂的各种设备,按照选矿厂设计的布置原则和厂区地理位置将各设备装配在厂区中. 通过选矿厂三维设计,全方位立体展示选矿厂设备设施布置要素,有利于提高设计效率和后期施工.     

混流式水轮机替代电动风机的节能改造

基于循环水系统的实际状况,探讨敞开式冷却塔的抽风用混流式水轮机替代电动风机的可行性,并对水轮机的优点、改造过程、节能效益进行了阐述。     

Management of ventricular arrhythmias: detection, drugs, and devices

OBJECTIVE: To review evaluation and treatment of patients with ventricular arrhythmias, based on recent studies, with an emphasis on randomized controlled trials. DATA SOURCES: MEDLINE search of English-language publications of ventricular arrhythmias and their references from 1966 through April 27, 1998. References to articles were also scanned to broaden the search. STUDY SELECTION: Randomized controlled trials and all large nonrandomized trials of arrhythmias and arrhythmia therapy were reviewed. In addition, studies that led to changes in approach to patients with arrhythmias were reviewed. DATA EXTRACTION: We reviewed articles jointly for pertinent studies and information. DATA SYNTHESIS: The goals of treatment of the patient with ventricular arrhythmias are to suppress symptoms and prevent a fatal event. The steps in providing such therapy include defining the cardiac anatomy, assessing arrhythmia risk through noninvasive or invasive testing, and prescribing treatment based on these results. Patients may be separated into high- and low-risk groups to help identify appropriate treatment. While low-risk groups may benefit from reassurance or medications such as beta-blockers or verapamil, high-risk groups have been more difficult to treat. Recent randomized trials of implantable cardioverter defibrillators for ventricular arrhythmias suggest that they may provide better protection for high-risk patients than do antiarrhythmic medications. CONCLUSIONS: Treatment and understanding of risk from ventricular arrhythmias have advanced substantially in recent years. Classifying patients as being at high or low risk for fatal arrhythmias allows the physician to identify appropriate treatments for the high-risk patient without exposing the low-risk patient to unnecessary treatment-related risks.