Beta amyloid gene duplication in Alzheimer's disease and karyotypically normal Down syndrome

With the recently cloned complementary DNA probe, lambda Am4 for the chromosome 21 gene encoding brain amyloid polypeptide (beta amyloid protein) of Alzheimer's disease, leukocyte DNA from three patients with sporadic Alzheimer's disease and two patients with karyotypically normal Down syndrome was found to contain three copies of this gene. Because a small region of chromosome 21 containing the ets-2 gene is duplicated in patients with Alzheimer's disease, as well as in karyotypically normal Down syndrome, duplication of a subsection of the critical segment of chromosome 21 that is duplicated in Down syndrome may be the genetic defect in Alzheimer's disease.     

管道运输企业降本压费的途径

影响管道运输企业经济效益的因素有两个，即管输收入和管输成本。管输收入受管输量和管输价格的影响，当管输量与管输价格一定时，降低成本和压缩费用则成为管道运输企业提高经济效益的主要手段。从做好节能降耗工作和压缩管道维修费用六个方面，阐述了管道运输企业提高经济效益所要进行的工作。     

减缓出口龙眼肉果冻褐变的初步研究

龙眼肉果冻褐变是影响出口龙眼肉果冻品质的很重要因素。主要针对影响出口龙眼肉果冻褐变主要因素展开研究,并由此提出减缓出口龙眼肉果冻褐变的最佳生产工艺配方。首先对杀菌温度、乙二胺四乙酸二钠(EDTA)浓度、维生素C(Vc)浓度、胶液的pH值、糖度等进行单因素试验,从而选择较优水平再进行正交试验。最终确定延缓该果冻褐变的最佳生产工艺配方:Vc浓度0.01%,EDTA浓度0.02%,糖度16°Bé,胶液pH值为3.3。     

降低输油成本之我见

由于东部地区油田的普遍减产，华东输油管道输量逐年下降，部分管道已脱离最佳经济运行区域；与此同时，输油成本却不断增加。根据江苏输油管理处１９９１￣１９９４年的管输运营情况，分析了管道维修费缺口较大的原因、营运费增长过快的因素及折旧费比重大的问题，用大量数据说明了输油管道行业所面临的严峻形势，提出了挖掘企业内部潜力，转变经营方式，摆脱困境的几点意见，①加强对总成本中常规可控部分的管理；②在燃料油和动力     

采用新型保温材料降低能耗

针对石家庄炼油厂化纤工程中压蒸汽管网保温材料的选用，给出了无石棉轻质硅酸镁铝绝热材料的性能参数值及性能特点。对无石棉轻质硅酸镁铝绝热材料和微孔硅酸钙材料的费用投资进行了经济计算对比，指出来用导热系数低、密度小、无腐蚀性、损耗少、价格低、施工条件好的新型保温材料可以降低能耗，节约能源，满足工程要求。     

绵山羊双羔素提高辽宁绒山羊繁殖率的研究

[目的]检验绵山羊双羔素在提高辽宁绒山羊繁殖率方面的作用。[方法]应用绵山羊双羔素(睾酮-3-羧甲基肟·牛血清白蛋白)在辽宁省盖州市、凤城市、瓦房店市、山西省岢岚县和河北省涞水县的绒山羊场和农户家,对1 327只2~6岁的辽宁绒山羊母羊进行免疫注射试验。[结果]试验组产羔率132.93%,对照组产羔率115.77%,试验组与对照组相比产羔率和双羔率均提高17.16%,差异显著(P0.05)。[结论]绵山羊双羔素可以提高辽宁绒山羊的繁殖率。     

Probing the threshold to H atom transfer along a hydrogen-bonded ammonia wire

We characterized the entrance channel, reaction threshold, and mechanism of an excited-state H atom transfer reaction along a unidirectionally hydrogen-bonded "wire" -O-H...NH3...NH3...NH3...N. Excitation of supersonically cooled 7-hydroxyquinoline.(NH3)3 to its vibrationless S1 state produces no reaction, whereas excitation of ammonia-wire vibrations induces H atom transfer with a reaction threshold approximately 200 wave numbers. Further translocation steps along the wire produce the S1 state 7-ketoquinoline.(NH3)3 tautomer. Ab initio calculations show that proton and electron movement along the wire are closely coupled. The rate-controlling S1 state barriers arise from crossings of a pipi* with a Rydberg-type pisigma* state.     

利用降落PCR扩增KS基因

通过优化SDS法提取链霉菌(Streptomyces spiramyceticus)和2株由生物技术与资源利用国家民委——教育部重点实验室分离获得的放线菌D8和D18基因组DNA,同时应用降落PCR和普通PCR扩增酮基合酶基因(ketosynthase,KS)。结果表明,扩增出的特异性条带与目的基因片段长度一致,降落PCR法较普通PCR法扩增KS基因特异性更高。使用普通Taq酶,降落PCR程序能明显提高PCR的特异性,它可用于扩增普通PCR难以扩增的基因片段,或在假阳性难以去除的情况下提高PCR的特异性。