水中BOD_5快速测定方法研究

生化需氧量是评价水体受有机物污染的相对耗氧指标。此生物氧化全过程进行的时间长,如在20℃培养时,完成此过程需100多天。BOD5标准测定方法采用稀释接种培养法,缺点是测定周期太长(需5天),不能及时反映水质指标,因此人们一直在研究BOD的快速测定方法。文章从BOD的特点研究BOD2和BOD5的关系,摸索了一种BOD5的快速测定方法;根据菲尔甫斯定律,找出了BOD2与BOD5的相关关系,通过BOD2与BOD5的拟合,建立相关方程,推导出BOD5速测公式,根据BOD2的值能够快速测定BOD5的值,缩短了分析周期,符合环境管理的要求。本方法较严密,省时,可供大家研讨。     

关于水中硫化物测定几个影响因素的探讨

本文通过改变实验室温度、显色时间、是否加入乙酸锌-乙酸钠、稀释水的酸碱性等试验条件,探讨硫化物的最佳测定条件。试验结果表明,在温度为18~22℃、稀释水p H在8~10、使用液中加入乙酸锌-乙酸钠时,采用亚甲基蓝分光光度法测定硫化物标准样品,可以得到较准确的测定结果。     

厌氧颗粒污泥流化床的动力学参数测定

介绍了厌氧颗粒污泥流化床反应器的主要动力学参数及其测定方法。通过分批试验测定厌氧动力学系数,以基质代谢平衡方程计算得到颗粒污泥双膜模型中的产甲烷层厚度,进行了颗粒污泥粒径、干密度等的测定和扩散系数的确定。以这些参数为基础的动力学模型计算结果与反应器长期连续运行测定结果相一致,证明了所测参数及其模型的可靠性。      

Determination of polycyclic aromatic hydrocarbonswith supercritical fluid extractionand chromatography (SFE/SFC )

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Development of non-invasive fetal DNA diagnosis from maternal blood

Several attempts have been made to detect and retrieve fetal nucleated cells including nucleated erythrocytes (NRBCs), leukocytes, and trophoblasts in maternal blood. We have recently developed a new method for non-invasive fetal DNA diagnosis from maternal blood. Peripheral blood granulocytes including NRBCs were isolated by a discontinuous density gradient method using Percoll (Pharmasia). NRBCs were found and retrieved at a single cell level using a micromanipulator under a microscope. To determine whether the origin of the NRBCs was maternal or fetal, the NRBCs were analysed by polymerase chain reaction (PCR) amplification to determine the presence of a Y-chromosome-specific repeat sequence in mothers carrying male fetuses. We were successful in predicting fetal sex accurately in 10 out of 11 samples taken from maternal blood. This new technique opens up fetal DNA diagnosis from maternal blood during the first trimester of pregnancy to the whole population because there is no risk to the fetus or the mother.     

Neutrophil and monocyte β2-integrin expression in trisomic fetuses

Flow cytometry was used to measure neutrophil and monocyte β2-integrin expression in fetuses with trisomy 18 (n=7) and trisomy 21 (n=7) at 20–25 weeks' gestation. The values were compared with those of 112 chromosomally normal fetuses. There were no significant differences in β2-integrin expression between normal and aneuploid fetuses. These findings demonstrate that in trisomies 21 and 18, alteration in β2-integrin expression is unlikely to contribute to the pathogenesis of immunological deficiencies that have been observed in these aneuploidies both prenatally and postnatally.     

Cardiac flow after fetal blood sampling in normally grown and growth-retarded fetuses

The objective of this study was to evaluate the effect of fetal blood sampling on cardiac flow velocity waveforms. Flow velocity waveforms were measured from the ascending aorta and pulmonary artery immediately before and after fetal blood sampling in 29 normally grown and 12 growth-retarded fetuses. The latter group was characterized by abnormal Doppler indices in the umbilical artery and middle cerebral artery suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. The flow velocity parameters studied were the peak velocity, the time to peak velocity, and the left and right cardiac output and their ratio. In normally grown fetuses, the peak velocity and right and left cardiac output values increased significantly after fetal blood sampling, while no significant changes were observed in the other indices considered. The gestational age at the time of the procedure was positively related to the amplitude of these changes. In growth-retarded fetuses, fetal blood sampling did not induce any significant increase in cardiac output or peak velocities, while in more than 50 per cent of the fetuses these Doppler indices decreased. The amplitude of the decrease was significantly related to the severity of acidosis in the umbilical vein. In conclusion, the cardiac haemodynamic response to fetal blood sampling differs between normally grown and growth-retarded fetuses. This difference may explain the higher rate of complications occurring in the latter group of fetuses after blood sampling.     

大气中臭氧浓度测定方法研究

臭氧的存在会对产品和材料造成严重的氧化腐蚀。采用仪器以线法和分光光度法2种不同的测定方法,探索了大气中臭氧浓度的变化规律和趋势,通过对测定数据的讨论与研究,分析在海南、江津和拉萨3种典型环境气候条件下臭氧浓度与环境气象因素之间的相关关系,获得了有意义的结论。