假单胞菌的氯儿茶酚1,2-双加氧酶基因的克隆和表达

 从土壤中分离得到1株降解2,4-二氯酚(2,4-DCP)能力较强的细菌菌株GT241-1,克隆了该菌株的3,5-二氯儿茶酚1,2-双加氧酶基因(dcpB),采用的克隆策略为:用Southern杂交对dcpB进行定位后,构建重组质粒,再用斑点杂交从重组质粒中筛选目的转化子.经序列测定得知dcpB亚克隆片段全长4303bp,其中dcpB基因编码区765bp.核苷酸和推测的氨基酸序列分析表明,dcpB与已在GenBank登记的相关基因有一定的差异.dcpB基因能够在大肠杆菌转化子中成功地表达有生物活性的酶.     

Effects of bifenthrin on Daphnia magna during chronic toxicity test and the recovery test

IntroductionWiththedevelopmentandapplicationofnewpesticide ,insecticidehasgreatlyreducedtheharmofpesttocrops .Bifenthrinisaneffectivepyrethroidinsecticideandacaricideagainstawiderangeofinsectpests ,anditisverypoisonoustomammal,aquatic .Thisinsecticideiswi…     

北京市冬季公共场所室内空气中TSP, PM10, PM2.5和PM1污染研究

在北京市的海淀区、朝阳区、丰台区和昌平区选择了 49个公共场所 (包括办公室、宾馆、图书馆、超市等等 ) ,分别对其室内空气中TSP ,PM10 ,PM2 5 和PM1的浓度进行了测定 ,并且对室内空气中粉尘含量的影响因素进行了分析和探讨 .研究结果表明 ,繁忙的交通状况和建筑施工将明显增加公共场所室内空气中TSP ,PM10 ,PM2 5 和PM1浓度 .频繁的室内清扫有助于降低室内空气中颗粒物的浓度 .在室内空气中 ,PM10 浓度与TSP浓度呈现明显的正向线性相关性 ,而PM2 5 和PM1的浓度与PM10 浓度的相关性较差     

锂离子电池正极材料的回收及再制备

通过湿化学法从废旧锂离子电池中回收得到Li+、Co2+的硝酸溶液,以此为钴源,与Ni(NO3)2.6H2O、Mn(NO3)2按化学计量比混合,用草酸盐共沉淀法制备草酸盐前驱体,然后按Li过量5%加入Li2CO3混合,在空气中于800～950°C煅烧15 h得LiCo1/3Mn1/3Ni1/3O2,研究了煅烧温度对材料结构、形貌以及电化学性能的影响。结果表明,900℃保温15 h制备的LiCo1/3Mn1/3Ni1/3O2正极材料,为理想的(α-NaFeO2层状结构,颗粒为大小均匀的球形,在2.5～4.3 V的电压范围内,以0.1 C的恒定电流进行充放电,其首次充放电比容量分别为194.3和150.9 mAh/g,10次循环之后的容量保持率为89.9%,放电比容量为135.0 mAh/g。     

大鹏湾春季海水理化因素与拟尖刺菱形藻种群密度的灰色系统模型研究

对1990年3月30日－6月25日在大鹏湾盐田海域的海水采样结果，用灰色理论的系统分析方法研究并计算大鹏湾地区海水中的拟尖刺菱形藻与浮游动物数量等15个海水理化因子变化的灰关联度，关联排序结果表明：浮游动物、Fe、浊度、Me、DO、V、Se、酸碱度、盐度和温度对拟尖刺菱形藻的种群增殖态有着较大的影响。进而建立灰色系统模型{GM（1，h )}对拟尖刺菱形藻种群增殖的动态辨识分析。     

Prenatal diagnosis of GM2-gangliosidosis B1 variant

Prenatal diagnosis in a pregnancy at risk for a juvenile B1 variant of GM₂-gangliosidosis was carried out. The biochemical study of the cultured amniocytes and the affected fetal brain is reported. The results obtained show that the sulphated artificial substrate can be used in the diagnosis of B1 variant, but not the neutral one. The accumulation of GM₂-ganglioside in the fetal brain of the B1 juvenile form and an infantile form of GM₂-gangliosidosis (0 variant) was compared.     

Prenatal diagnosis of neurofibromatosis type 1: From flanking rflps to intragenic microsatellite markers

Even though the neurofibromatosis type 1 (NF1) gene was cloned more than 3 years ago, the process of identifying mutations has not been fruitful, and genetic counselling is mainly based on the use of linked markers. Since 1990, we have analysed 130 NF1 families and have performed six prenatal diagnoses. In each case, genetic counselling has relied on linked markers and informativity was achieved in all of them. The use of intragenic microsatellite polymorphisms (IVS27AAAT2.1, IVS27AC28.4, IVS27AC33.1, and IVS38GT53.0) has increased the informativeness in our series of NF1 families to an average of 90 per cent, providing accurate diagnosis and confirmation of the disease status.     

Cu／A1-Ce-PILC在丙烯选择性催化还原NO反应中的失活研究

采用聚合羟基复合阳离子合成交联黏土A1-Ce-PILC，经SO4^2-改性后，以浸渍法制备了铜基交联黏土催化剂Cu／A1-Ce-PILC，并将其应用于C3H6选择性催化还原NO的反应，350℃时NO转化率达到最大值56％，700℃时下降至22％．为探究催化剂高温失活的原因，采用XPS、TPR、TGA、Py-IR和DSC对反应前后催化剂的物化性能进行了表征．结果表明，经过H2预处理活化后活性组分Cu物种以Cu^＋形式存在，而高温反应后Cu物种除以Cu^＋和Cu^2＋ 2种形式存在外，还出现了少量CuO物种；高温反应过程中A1-Ce-PILC上结构羟基和SO4^2-流失导致催化剂表面酸性减弱；此外，还存在表面积炭覆盖了部分活性中心并堵塞了催化剂孔道的现象．这三者的共同影响促进了C3H6深度氧化，抑制了NO还原，从而导致催化剂的失活．     

Enzymatic degradation of poly([R,S] β-hydroxybutyrate)

The synthetic analogue of a bacterially produced polyester, poly(-hydroxybutyrate) (PHB) was synthesized from racemic -butyrolactone using anin situ trimethyl aluminum-water catalyst. The polymer was fractionated into samples differing in molecular weight and isotactic diad content. The latter was closely related to degree of crystallinity. The biodegradation of these fractions were examined by monitoring mass loss over time in the presence of anAlcaligenes faecalis T1 extracellular bacterial poly(-hydroxybutyrate) depolymerase. The fraction with high isotactic diad tacticity content showed little or no degradation over a 50 hour incubation period, whereas the fraction of intermediate isotactic diad content degraded in a continuous steady fashion at a rate that was less than that for bacterial PHB. The low isotactic diad fraction underwent a rapid initial degradation, followed by no further mass loss. The presence of stereoblocks in the polymer structure of the various fractions was an influence on the degree of susceptibility towards degradation and is related to sample crystallinity.     

硝酸甲胺反应过程的安全性研究

用反应量热仪(RC1e)对硝酸溶液与一甲胺溶液在反应过程中的热安定性进行初步研究,分别测试不同反应温度、加料速度和初始硝酸浓度下反应的放热情况。实验结果表明:该中和过程反应迅速,在室温就能进行;与反应温度、加料速度相比,起始硝酸浓度对反应安全性影响最大,且硝酸浓度越高,反应的速度和反应的完全程度也越高。实验还表明:RC1e是研究反应过程中热安定性情况的有效工具,能通过反应过程的热量变化体现反应速率,所得结果对硝酸甲胺的工业化生产具有重要的参考价值。