SMT-PGA封装焊点热疲劳寿命预计模型研究

目的研究SMT-PGA封装焊点热疲劳寿命预计模型。方法运用Engelmaier模型预测SMT-PGA封装焊点的热疲劳寿命,并将Engelmaier模型计算结果与美国马里兰大学CALCE PWA寿命评估软件仿真结果作对比。结果模型计算结果与马里兰大学寿命评估软件仿真结果存在较大差异。结论表明Engelmaier模型中的工程因子F并不是一个固定常数,而是受封装最低稳态温度的影响。     

Early prenatal direct gene diagnosis of cystic fibrosis in a twin pregnancy and subsequent selective termination

We present a case of prenatal diagnosis of cystic fibrosis (CF) in one twin at 11–12 weeks of gestation. The parents had previously had two children, one of whom is alive and healthy and one who died of CF at the age of 2½ months. The parents were both known to be carriers of the ΔF508 mutation. Chorionic villus sampling (CVS) was performed and direct gene analysis showed that one fetus was homozygous for the ΔF508 mutation, while the other fetus did not have the mutation at all. Both fetuses had normal karyotypes. Selective termination was subsequently performed. The pregnancy continued without complications except for mild pre-eclampsia at term. The woman had a Caesarean section. The genetic diagnosis was confirmed after birth.     

烟草头孢霉F2抗氯化汞特性的研究

对抗汞真菌——烟草头孢霉F2的某些抗汞特性进行了研究。结果表明,该菌株在含500mg/L HgCl_2的土豆汁葡萄糖培养基中生长良好,其对HgCl_2的抗性与培养基的起始pH值明显相关。某些巯基化合物可促进该菌的抗汞能力。二价金属阳离子对该菌抗汞能力有不同的效应。在不同的培养基上,该菌对汞的吸收能力不同。在一定的条件下,菌体吸收的汞可释放入无汞培养液和磷酸缓冲液中。经透射电镜和扫描电镜观察表明,该菌分生孢子在萌发前明显膨胀,细胞壁、细胞核及线粒体均有不规则现象出现。     

石杉碱戊和石杉碱己的结构

在石杉［Ｈｕｐｅｒｚｉａｓｅｒｒａｔａ（Ｔｈｕｎｂ．）Ｔｒｅｖ．］中分得了命名为石杉碱成素和已素的２个新生物碱，并用２Ｄ－ＮＭＲ和ＭＳ测定了它们的化学结构．     

微生物絮凝剂产生菌的筛选及相关废水絮凝效果试验

用常规的细菌分高纯化方法从废水、土壤、活性污泥中分离出42株细菌，将单株菌培养于特殊的产絮凝剂液体培养基中，培养物离心后上液对高岭土县液絮凝效果作为指标衡量其絮凝活性及产絮凝剂能力，由此初步获得6株微生物絮凝剂产生菌：Ⅰ－23，Ⅰ－24，Ⅱ－4，Ⅲ－2，Ⅲ－8，Ⅲ-12．其发酵离心上液对造纸黑液、皮革废水、偶氮染料废水、硫化染料废水、电镀废水、彩印制板废水、石油化工废水、造币废水及蓝墨水、碳素墨水等进行的絮凝试验表明，废水固液分离效果良好，CODCr去除率55％～98％，悬浮物、色度、浊度去除率90％以上．     

硅营养缓解水稻幼苗Cd、Cr毒害的生理研究

两系法杂交稻“培杂山青”和常规稻“双桂３６”幼苗经较高浓度的Ｃｄ２＋（ｃ＝９．６～３８．４μｍｏｌ／Ｌ）或Ｃｒ３＋（ｃ＝７．５～２５．０μｍｏｌ／Ｌ）处理可使其叶片光合速率、叶绿素（ａ＋ｂ）含量、叶绿素ａ／ｂ比值、叶片可溶性糖、淀粉及可溶性蛋白质含量降低，而叶片的ＰＯＤ活性提高；低浓度Ｃｄ２＋（ｃ＝４．８μｍｏｌ／Ｌ）和Ｃｒ３＋（ｃ＝２．５μｍｏｌ／Ｌ）处理幼苗对上述生理指标有提高作用，但ＰＯＤ活性稍降低．加Ｓｉ（Ｎａ２ＳｉＯ３）［ｃ（ＳｉＯ２）＝１．３３１ｍｍｏｌ／Ｌ］的Ｃｄ、Ｃｒ处理比不加Ｓｉ的Ｃｄ、Ｃｒ处理的幼苗叶片上述生理指标明显提高，且明显降低其ＰＯＤ活性．说明Ｓｉ在不同程度上起到缓解Ｃｄ、Ｃｒ对水稻幼苗的毒害作用．而ｃ（Ｃｒ３＋）＝２５．０μｍｏｌ／Ｌ是“双桂３６”幼苗的致死浓度     

部分PCDDF水溶解度的定量结构-性质关系

以量子化学PM3算法计算得到的12个量子化学参数作为分子结构描述符，运用偏最小二乘分析，首次建立23种PCDD/F水溶解度（logSw)的定量结构-性质关系模型。PCDD/F的Sw随着其分子量的增大而减少；随着其分子最低未占据轨道能（Eluno)的增大而增大，推测PCDD/F分子与水分子之间存在着电荷转移相互作用。     

Properties of mercuric reductase from a HgCl_2-resistant fungus

ＰｒｏｐｅｒｔｉｅｓｏｆｍｅｒｃｕｒｉｃｒｅｄｕｃｔａｓｅｆｒｏｍａＨｇＣｌ＿２－ｒｅｓｉｓｔａｎｔｆｕｎｇｕｓＷａｎｇＢａｏｊｕｎ；ＬｉＷｅｎｚｈｏｎｇ；ＹａｎｇＨｕｉｆａｎｇＩｎｓｔｉｔｕｔｅｏｆＭｉｃｒｏｂｉｏｌｏｇｙ，ＣｈｉｎｅｓｅＡｃａｄｅ...     

PCDD, PCDF, AND PCB concentrations in human milk from two areas in Finland

Concentrations of 17 toxic 2,3,7,8-chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and of 36 polychlorinated biphenyl congeners (PCBs) were analyzed from 167 randomly sampled human milk samples from Southern (77 samples) and Eastern (90) Finland. The level of PCDD/Fs and PCBs in human milk in Southern Finland was about 25% higher than those from Eastern Finland. The level of PCDD/Fs in human milk in Finland was the same as in Sweden, 30–50 % lower than in milk from Central Europe but about 45% higher than values from Norway or Russia. The PCB concentrations in Southern Finland were at the same level as in the Netherlands, and in Eastern Finland at the same level as in Norway. The levels of PCDD/Fs and PCBs decreased with increasing number of children: the third child was exposed to about 70% of the amount of PCDD/Fs and PCBs as compared with the first child, and the eighth to tenth child to about 20%. The congener patterns of PCDD/Fs and PCBs in Finnish human milk were similar to the countries of Central Europe, however, the levels of penta- and heptachlorinated furans were slightly higher than in milk from other countries.     

BAT and BEP as instruments for reducing emissions of unintentionally produced POPs and development of guidelines under the stockholm convention

The 6th Intergovernmental Negotiating Committee (INC 6), under the Stockholm Convention on POPs, gave an expert group the mandate to develop guidelines for the application and implementation of best available techniques (BAT) and best environmental practices (BEP) for the prevention and reduction of unintentionally produced and emitted POPs, including polychlorinated dibenzodioxins/-furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB). Measures to reduce or eliminate the release of these POPs to the environment can be found in Article 5 of the Convention. BAT and BEP are already being applied as emission reduction instruments in a number of industrialised countries and are elements of other major international treaties, e.g. the UN ECE Protocol on POPs and the Marine Convention's OSPAR and HELCOM, and of the EU Directive for Integrated Pollution Prevention and Control (IPPC Directive). Existing concepts are presented and compared with the requirements of the Stockholm Convention. Consequences, perspectives and questions for the future intersessional work of the above-mentioned Expert Group are discussed.