Alphafetoprotein,cholinesterases and rapidly adhering cells in the prenatal diagnosis of neural tube defects

Amniotic fluid cholinesterases tested on polyacrylamide gel and rapidly adhering cell analysis were compared in their efficiency at diagnosing fetal neural tube defects in three cases where the alphafetoprotein results were equivocal. While rapidly adhering cells were also equivocal, the cholinesterases consistently gave a clear indication of fetal abnormality.     

兔子宫内膜蛋白等电聚焦电泳载体两性电解质pH范围及比例的选择

兔子宫内膜蛋白是研究早期胚胎发育过程中胚泡附植机制的关键因素之一．为了对子宫内膜蛋白进行有效的分离，本研究探讨了用于等电聚焦电泳的载体两性电解质pH范围及其比例．研究结果表明：在只有pH3～9．5的情况下，蛋白质谱带主要分布于胶条碱性端1／3区域，酸性端无谱带；在载体两性电解质pH3-9．5：pH4～6=1：4的情况下，蛋白质谱带主要分布于胶条碱性端2／3部分；在载体两性电解质以pH3-9．5：pH4～6：pH6—9=1：4：1时，蛋白质谱带分布比较均匀，酸性端也有谱带分布．这说明在作子宫内膜蛋白的等电聚焦电泳时采用pH3～9．5：pH4～6：pH6～9=1：4：1比较理想．     

锆涂覆石墨管-无火焰原子吸收测定环境水样中微量银

用锆盐对石墨炉进行涂覆处理,同时又将其作为基体改进剂,有效提高了测定环境水样中银的灵敏度和分析精度,方法快速简便,检出限为2 8×10-12g,相对标准偏差小于6 2%。     

检测管比色法快速测定水中硫化物

本文介绍的Ｓ２－的检测管比色测定法，以亚甲兰法为基础，显色反应在自制的小检测管内进行。通过与标准色列管进行比较来确定样品中Ｓ２－的含量。方法适用于水中硫化物的快速测定，结果令人满意。     

一种新型流管反应器的设计与表征

介绍了一种用于气溶胶生成机制研究的流管反应器（Jiao-FTR,J-FTR）的设计及表征.借助计算流体力学（CFD）模拟和实验测定,表征了不同进气结构和实验条件下反应器内流场的发展及稳定,移动进气管的喷射效应以及气体和颗粒物在反应器内的平均停留时间.结果表明,预混合段进气方式,主流流量,移动进气管结构及注入流量对J-FTR的流场发展以及气体和颗粒物的停留时间具有较大影响;J-FTR的预混合进气段具有使主流快速过渡为层流的优势,在对称进气条件下,当主流流量不超过8L/min,气流在进入主反应段之前可发展为稳定的层流;当移动进气管使用大内径的直管或径面十字型结构时,可以有效减小或避免移动进气管的喷射效应.以上结果不仅可为使用J-FTR开展大气化学和气溶胶生成机制研究提供重要的实验指导,也可为其他研究者设计FTR,进行流管实验提供借鉴.     

Role of nano-additive blended biodiesel on emission characteristics of the research diesel engine

The current experimental study is aimed to analyze the influence of single-walled Carbon Nano Tubes (CNT) on the emission characteristics of neem biodiesel-fueled (NBD-fueled) diesel engine and the results compared with conventional diesel. Experiments were conducted in a single-cylinder, 4-stroke, diesel engine with an eddy current dynamometer at a constant speed of 1500 rpm. Two samples of CNT are characterized and dispersed into 100% of the NBD in a mass fraction of 50 and 100 ppm using ultrasonicator, and the physicochemical properties were measured. Experimental results indicated that by adding CNT nanoparticles in NBD reduces its NO_x, HC, CO, and smoke emission by 9.2%, 6.7%, 5.9%, and 7.8%, respectively, at all load conditions.     

钢管混凝土柱温度场简化计算方法

钢管混凝土柱是建筑承重结构的重要组成部分,其耐火极限研究尤为重要。温度场计算作为抗火研究的基础,在保证精确度的前提下要做到简单实用,为高效的抗火设计提供有利条件。通过有限元软件ABAQUS模拟构件温度场,分析80种不同工况下圆、方形构件温度场分布特点,并考虑钢管厚度、截面尺寸等因素,提出了钢管及混凝土温度简化计算公式。通过试验数据、模拟数据对公式进行调校验证,结果表明计算精度满足工程设计要求。     

Effects of premixed methane concentration on distribution of flame region and hazard effects in a tube and a tunnel gas explosion

Study of flame distribution laws and the hazard effects in a tunnel gas explosion accident is of great importance for safety issue. However, it has not yet been fully explored. The object of present work is mainly to study the effects of premixed gas concentration on the distribution law of the flame region and the hazard effects involving methane-air explosion in a tube and a tunnel based on experimental and numerical results. The experiments were conducted in a tube with one end closed and the other open. The tube was partially filled with premixed methane-air mixture with six different premixed methane concentrations. Major simulation works were performed in a full-scale tunnel with a length of 1000 m. The first 56 m of the tunnel were occupied by methane–air mixture. Results show that the flame region is always longer than the original gas region in any case. Concentration has significant effects on the flame region distribution and the explosion behaviors. In the tube, peak overpressures and maximum rates of overpressure rise (dp/dt)_max for mixtures with lower and higher concentrations are great lower than that for mixtures close to stoichiometric concentration. Due to the gas diffusion effect, not the stoichiometric mixture but the mixture with a slightly higher concentration of 11% gets the highest peak overpressure and the shock wave speed along the tube. In the full-scale tunnel, for fuel lean and stoichiometric mixture, the maximum peak combustion rates is achieved before arriving at the boundary of the original methane accumulation region, while for fuel rich mixture, the maximum value appears beyond the region. It is also found that the flame region for the case of stoichiometric mixture is the shortest as 72 m since the higher explosion intensity shortens the gas diffusion time. The case for concentration of 13% can reach up to a longest value of 128 m for longer diffusion time and the abundant fuel. The “serious injury and death” zone caused by shock wave may reach up to 3–8 times of the length of the original methane occupied region, which is the widest damage region.     

Prenatal screening and diagnosis of neural tube defects

This review article discusses prenatal screening and diagnosis of neural tube defects (NTD). High detection rates occur in countries operating ultrasound screening programmes because classical two-dimensional ultrasound cranial signs (lemon shaped head, banana cerebellum, ventriculomegaly) are important diagnostic clues to the presence of spina bifida. Careful evaluation of both the spine and a search for other abnormalities is warranted. Important prognostic information for spina bifida relates to the lesion level, with a “watershed” between L3 and L4 marking a very high chance of being wheelchair bound with the higher lesions. Three-dimensional ultrasound using multiplanar views can achieve diagnostic accuracy within one vertebral body in around 80% of patients. There are high rates of pregnancy termination for spina bifida in many European countries, but the use of new imagining techniques allow better prediction of outcome, and consequently a refinement of prenatal counselling. Copyright © 2009 John Wiley & Sons, Ltd.