Fe2+抑控煤中α硫酚结构氧化机理及效果

应用Gaussian 03程序,采用密度泛函方法,在B3LYP/6-31G(d,p)水平下,分析Fe~(2+)抑制煤中α位硫酚结构氧化的效果,从而为阻化剂的配制与优选提供数值依据。首先,根据自然键轨道理论分析煤的特征结构C_(10)H_7SH与过渡金属Fe~(2+)形成配合物的成键本质,并结合分子中的原子理论分析其稳定性;然后,分别计算C_(10)H_7SH结构和[FeSH_8CC_(10)]~(2+)配合物吸附O_2的反应过程,得到反应过程所需活化能,以此活化能为指标,表征Fe~(2+)抑控煤中α位硫酚结构氧化的效果。计算结果表明,Fe~(2+)与C_(10)H_7SH结构中的S原子间形成了配位键,根据电子密度拓扑分析得其键能E_(S-Fe)为-128.56 kJ/mol,C_(10)H_7SH结构吸附O_2的反应过程所需活化能为E_C=62.71 kJ/mol,[FeSH_8C_(10)]~(2+)配合物吸附O_2的反应过程所需活化能与其相比增加了35.60 kJ/mol。研究表明,Fe~(2+)对煤中α位硫酚结构氧化具有明显的控制作用。     

Prenatal diagnosis of Fabry's disease by direct analysis of chorionic villi

Six pregnancies of three carriers for X-linked Fabry's disease, were monitored by chromosome and enzyme analysis. Two affected male fetuses were detected by the demonstration of α-galactosidase deficiency in amniotic fluid cells and chorionic villi respectively. The use of chorionic villi enabled a diagnosis within a few hours after sampling in the ninth week of pregnancy whereas the use of amniotic fluid cells in the earlier case required two weeks of culturing after amniocentesis in the 16th week. Four female fetuses were found; heterozygosity was demonstrated in one by analysis of clones in the primary amniotic fluid cell culture.     

Isoelectric focusing pattern of human amniotic fluid α-fetoprotein

Isoelectric focusing (IEF) of amniotic fluid α-fetoprotein (AFP) in thin-layer polyacrylamide gels containing 8 M urea followed by immunoblotting reveals at least nine bands, band I lying next to the cathode. Compared with 298 amniotic fluid samples from normal pregnancies, we found that the density of band V was increased in seven cases of fetal death. In 16 amniotic fluid samples from pregnancies with open neural tube defects (ONTO), band V disappeared or was markedly decreased. In seven cases with elevated AFP and positive acetylcholines-terase (AChE) due to contamination with fetal blood, no difference in pattern was observed compared with samples from normal pregnancies. It is suggested that IEF of AFP and subsequent immunoblotting are an apparently diagnostic test for ONTD and intrauterine fetal death (IUFD).     

Prenatal diagnosis of spina bifida aperta after first-trimester valproate exposure

In the context of a prospective study on the adverse effects of anti-epileptic drugs on fetal outcome, we evaluated our experience with prenatal diagnosis by ultrasonography and α- fetoprotein (AFP) determination in amniotic fluid. We compared these results with AFP values in maternal serum obtained prior to amniocentesis. From November 1985 to July 1990, amniocentesis at 16–18 weeks of gestation was performed in 267 pregnancies of 237 different women using anti-epileptic drugs. Among 92 pregnancies with maternal valproic acid use, five (including one concordantly affected monozygotic twin-pair) were terminated because of a spina bifida aperta, all prenatally diagnosed by AFP determination and acetylcholinesterase electrophoresis in amniotic fluid. The maternal serum AFP level was raised (⩾ 2.5 multiples of the median (MOM) for singleton pregnancies and ⩾ 4.5 MOM for twin pregnancies) in only two of these five affected pregnancies. We emphasize that maternal serum AFP levels may be unreliable for prenatal screening for fetal neural tube defects in women taking valproate and recommend that amniocentesis and fetal ultrasound examination should be offered directly.     

Second organic aerosol formation from the ozonolysis of α-pinene in the presence of dry submicron ammonium sulfate aerosol

An indoor chamber facility is described for investigation of atmospheric aerosol chemistry. Two sets of α-pinene ozonolysis experiments were conducted in the presence of dry ammonium sulfate seed particle: ozone limited experiments and α-pinene limited experiments. The concentration of gas phase and particle phase species was monitored continuously by on-line instruments and recorded automatically by data sampling system. The evolution of size distribution was measured by a scanning mobility particle sizer ...     

酞菁锌改性介孔分子筛催化降解孔雀石绿

以介孔分子筛MCM-41为载体,采用浸渍法将1,4,8,11,15,18,22,25-八环戊氧基酞菁锌(α-CyOPcZn)负载到分子筛上得到了一种新型的催化剂CyOPcZn/MCM-41.并通过氮气吸附、红外光谱扫描及电镜扫描对催化剂的结构进行表征.考察了该催化剂的用量、H2O2浓度对孔雀石绿降解作用的影响.实验结果表明,在模拟可见光照射下,当催化剂用量0.6 g.L-1、H2O2浓度为0.1 mmol.L-1时,60 min后使0.1 mmol.L-1的孔雀石绿水溶液的脱色率达到98.6%,并呈现出一级反应的动力学特征,速率常数k为0.0891 min-1.催化剂重复使用3次后,脱色率可达96%以上.     

不对称还原α-氨基苯乙酮菌种的筛选及转化条件优化

芳香基手性胺醇是许多手性药物合成的重要手性砌块,生物催化不对称还原前手性酮是合成该类醇的重要方法之一.以α-氨基苯乙酮盐酸盐为模型底物从土壤中筛选获得两株能分别高立体选择性催化底物产生R型、S型相应醇的菌株,对映体过量值(e.e.)分别为99%和77%,编号为1403和4802,鉴定菌株所属为镰刀菌属和地霉属.对两株菌培养时期和转化条件的研究表明镰刀菌1403最适生长时间为24 h,最优菌体浓度20 g/L,最优底物浓度5 g/L;地霉4802最适生长时间24 h,最优菌体浓度80 g/L,最优底物浓度3 g/L.底物特异性研究表明,菌株1403和4802均可转化α-氯代苯乙酮、α-溴代苯乙酮、α-羟基苯乙酮和苯乙酮为相应醇,且以α-羟基苯乙酮为底物时,其产物均为S型,e.e.值达99%.     

航运公司安全管理能力聚权分级模型

为了更好对航运公司安全管理工作摸底排查,采取针对性措施监管航运公司安全营运,需要对安全管理能力进行分类分级评价。基于表征航运公司安全管理能力的分级指标体系,建立安全管理能力分级评价模型。基于熵权和变异系数法的赋权方法,利用α系数检验两种客观赋权法的信度,提出聚合权重并建立安全管理能力的物元分级模型。利用多家航运公司数据确定分级指标的权重,对典型公司分级和评分。结果表明,提出的模型能合理反映各公司的安全管理能力,并有利于主管机关进行分类管理,采取针对性措施提高监管效率改善公司安全管理能力。     

Spatiotemporal dynamics in variable population interactions with density-dependent interaction coefficients

In this article, I present a two-patch metapopulation model with locally explicit dynamics to study the effect of spatial heterogeneity and dispersal upon population interactions with variable or conditional outcomes. These are interactions that may be either detrimental or beneficial for each species depending on the balance of the density-dependent costs and benefits involved. The local dynamics respond to density-dependent α-interaction functions that may change sign, thus yielding a diversity of possible local outcomes for the association in terms of type of interaction and in the number of stable solutions. The spatiotemporal model predicts that the fragmentation of space and dispersal between patches may cause further variation in these outcomes. First, the demographic performance of a species in the association is enhanced if migrations cause a proportional increase of individuals of its own species; being so, a victim may become a mutualist or an exploiter, an excluded species may invade, and a good competitor may overcome its own carrying capacity: the ‘enhancement effect of dispersal’; a sort of rescue effect in source-sink dynamics. The underlying mechanisms involve an interplay between density-dependent effects of dispersal per se and the relative local and global average α-interaction functions, which involve costs and benefits at both the local and regional level that may either counteract or reinforce each other; thus, localities and/or populations may change dynamically their sink or source role in the spatial dynamics. A significant insight arises herewith: in the context of variable or conditional interactions the concept of the role of a species does not make strict sense; it becomes a spatiotemporal dynamic quality. Second, regardless of which species disperses, bifurcation of equilibria may occur in those patches that receive the migrating individuals, and annihilation of equilibria in those from where migration leaves; thus, the number of equilibria increases or decreases accordingly.     

聚乙烯副产物聚乙烯蜡的热解及轻质馏分的GC-MS分析

采用高温模拟蒸馏、红外光谱和热重分析等方法对聚乙烯副产物聚乙烯蜡进行了表征。在间歇高压反应釜中对聚乙烯副产物聚乙烯蜡进行了热解,并通过正交实验考察了热解温度、停留时间和初始压力对液相产物收率的影响。利用GC-MS技术对液相产物轻质馏分(低于200℃)进行了分析。结果表明:聚乙烯副产物聚乙烯蜡主要由长链脂肪烃(C_(14)~C_(70))组成;热解发生的温度范围为175~490℃;热解温度和停留时间是影响液相产物收率的主要因素;液相产物轻质馏分的碳数分布在C_9~C_(20),主要为α-烯烃(占比32.79%)和正构烷烃,其中单体烃含量最高的是1-癸烯(占比8.46%),它是制备高级合成润滑油聚α-烯烃的优质原料。