Mosaicism or pseudomosaicism: The problem of hypermodal cells in amniotic fluid cell culture

A series of 2029 consecutive amniotic fluid specimens studied for prenatal genetic diagnosis were reviewed and reassessed so as to evaluate the frequency and clinical significance of hypermodal cells in amniotic fluid cell cultures. Hypermodal cells were defined as those with more than 46 chromosomes, and were characterized by an additional structurally normal or structurally abnormal chromosome. Of 2029 specimens, 47 (2.31 per cent) contained a total of 167 hypermodal cells. True fetal mosaicism was detected in three cases (0.14 per cent). All had hypermodal cells in more than one culture flask or colony which contained the same aberrant chromosome complement. In all but one case the babies were normal when only one cell was hypermodal, or when several cells were hypermodal but present in only one colony or one culture vessel. One case had an extra No. 20 chromosome in one cell. Although the child had multiple anomalies, they were not characteristic of trisomy 20, and subsequent chromosomal study on the baby postnatally revealed a 46,XX karyotype. The in situ coverslip technique is recommended as the preferred method for prenatal diagnosis, and it is useful as an aid in differentiating true mosaicism from pseudomosaicism.     

哑铃湾网箱养殖自身污染状况

根据2002年4月、7月、10月和2003年1月对哑铃湾海域网箱养殖区的调查数据，分析该海域网箱养殖自身污染情况。结果表明，网箱养殖增加了水体中N、P的含量，改变了养殖水体中一些化学因子的垂直分布，加速了哑铃湾海域的有机污染和富营养化。随着养殖年限的增加，哑铃湾网箱养殖自身污染日趋严重。     

氨氧化菌混培物在微量NO2气氛下的氨代谢特性

用普通活性污泥经120d富集,得到氨氧化菌混培物,氨氧化菌浓度提高300倍.在NO2/O2混合气氛下进行氨氧化试验,结果表明,无分子氧时,氨氧化菌能以NO2为电子受体氧化氨,并产生NO;加入氧气后,氨氧化速率明显提高,最高速率[33(mol NH4 -N/(g MLSS(h)]发生在混合气体中NO2和O2浓度分别为1.79(mol/L和9.38mmol/L时;在NO2浓度为0.89～1.79(mol/L范围内,O2能够强化基于NO2的氨氧化反应,当NO2浓度增大至6.71(mol/L时,氨氧化速率却降低.部分NO被O2氧化,使得反应器出口气体中NO2浓度高于进口.试验过程中产生约20%氮损失,这与氨氧化和厌氧氨氧化相互耦合产生气态含氮产物(N2、NO、N2O)有关.     

厌氧菌降解四氯乙烯的研究

报道了洳气污泥富集培养物中厌氧菌降解四氯乙烯的特征。研究结果表明，沼气污泥在甲醇、甲酸盐、乙酸盐、乙醇和Ｈ２／ＣＯ２等不同碳源基质中的富集培养物，以利用甲醇为碳源的富信培养物降解四氯乙烯（Ｔｅｔｒａｃｈｌｏｒｏｅ－ｔｈｙｌｅｎｅ，简称ＰＣＥ，下同）活性最高，平均每升培养液每天降解ＰＣＥ１４００ｎｍｏｌ。经对该富集培养物的分离培养，已分离出４株厌氧细菌，其中一株为甲烷八叠球菌，两株为弧菌，一株为杆菌     

哑铃湾网箱养殖可持续容量研究

在相关养殖容量研究的基础上,提出了养殖环境容量和可持续养殖容量的概念和内涵.以哑铃湾网箱养殖为例,建立了考虑时间累积效应后的养殖环境容量和考虑了社会、经济和环境综合效益后的可持续养殖容量计算模型.估算了在10年时段内哑铃湾网箱养殖环境容量和可持续养殖容量.结果表明,哑铃湾网箱养殖最优环境容量为每年4.11万箱,可持续养殖容量为每年3.45万箱.     

绿僵菌液体培养的条件及其对马尾松毛虫的毒力

在不同温度和不同光照条件下对3株金龟子绿僵菌和1株贵州绿僵菌的液体深层培养研究表明，光照对菌丝生长和液生分生孢子产量均无显著影响。但培养温度显著影响菌丝生长和液生分生孢子的产出率，25-28℃为液体深层培养绿僵菌的适宜温度，其中以28℃最佳，对3-4龄马尾松毛虫幼虫的室内毒力测定表明，绿僵菌液生分生孢子的毒力略低于气生分生孢子。     

共生菌B1+B2聚乙烯醇降解酶活性优化研究

从PVA降解酶的角度对本实验室前期实验筛选到的共生菌B1 B2进行了研究.在考察共生菌的基本生长和酶活的关系以及PVA降解酶和氧化酶的关系后,研究了不同的营养条件对PVA降解酶活性的影响.通过对主要营养条件的单因素考察,设计正交实验,优化出影响PVA降解酶活性的最佳主要营养条件为酵母汁0.2gL-1、硝酸铵0.2gL-1、葡萄糖0.5gL-1.采用优化条件进行验证实验,PVA降解酶活性(1.61UmL-1)高于正交实验中的最高酶活(1.56UmL-1),研究结果对发酵生产PVA降解酶和提高该菌在PVA废水处理中的降解性能有一定的价值.图5表3参11     

Analysis of train derailments and collisions to identify leading causes of loss incidents in rail transport of dangerous goods in Canada

The Canadian railway industry has improved safety performance in the last decade as measured by freight loss incidents per billion gross ton-miles. Further improvements in safety performance require a deeper analysis of the leading causes to identify weaknesses in implementing safety systems. In this paper, we classify the causes of railway loss incidents using a Safety Management System (SMS) framework to identify system weaknesses. The role of human factors is further analyzed through the Human Factors Analysis and Classification System (HFACS) approach. For this, we utilized data from 42 main track derailments and collisions involving the transport of dangerous goods in Canada between 2007 and 2018, which have been investigated by the Transportation Safety Board of Canada in detail. Associations between adjacent sub-categories of the HFACS framework are analyzed to identify any interdependency that exists between active and latent errors using a Chi-square test and Kruskal's lambda analysis. Furthermore, we implement the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method and the Analytical Network Process (ANP) to identify causal relationships between different sub-categories of the HFACS framework and calculate the weighted influence of each sub-category on main track derailments and collisions. Finally, a comparison is made between this work and others', which have analyzed human factors in the railway industry. There is good agreement between the results of these studies that highlight the importance of supervisory and organizational factors in the prevention of railway loss incidents. Based on these findings, we make recommendations to reduce railway loss incidents.     

关于海洋环境文化建设与海洋环境保护的若干思考

海洋环境文化是海洋文化和环境文化的一个分支,其建设状况对海洋环境保护影响甚大.本文从引入海洋环境文化的概念入手,探析其内涵及重要性,分析了海洋环境文化与海洋经济的辩证关系,并就海洋环境问题,从海洋环境文化层面剖析原因,提出了海洋环境文化建设的对策思路.