Recent progress in thermoelectric materials

Direct conversion of heat into electricity through advanced thermoelectric(TE)materials has been one of the most attractive solutions to the severe environmental and energy issues facing humanity.In recent years,great progress has been made in improving their dimensionless figure of merit(ZT),which determines the conversion efficiency of TE devices.ZT is related to three‘‘interlocked’’factors—the Seebeck coefficient,electrical conductivity,and thermal conductivity.These three factors are interdependent in bulk TE materials,and altering one changes the other two.The difficulty in simultaneously optimizing them caused TE research to stagnate,until great reductions in thermal conductivity were both theoretically and experimentally proven in nanomaterials in 1993.In this review,we first introduce some TE fundamentals and then review the most recently improvements in ZT in different kinds of inorganic and organic TE materials,which is followed by an investigation of the outlook for new directions in TE technology.     

Kinetic study of the DNA annealing properties of RECQ5β helicase

RecQ family helicases are critical for maintaining genomic integrity. Many RecQ family helicases not only unwind duplex, and other more complicated DNA structures, but also possess, interestingly, DNA annealing (strand pairing) activity. Here, we systematically investigated the DNA annealing properties of RECQ5β by measuring DNA annealing kinetics, equilibrium DNA binding, and kinetics of dissociation from ssDNA. RECQ5β catalyzed DNA annealing most efficiently when the enzyme molecules covered approximately 40%-50% of the DNA strand, in the absence or presence of different nucleotide cofactors (AMPPNP, ATPγS, or ADP) under our buffer conditions. A comparative study with RECQ5β1-662 confirmed that the C-terminal region of RECQ5β was essential for its high DNA annealing activity. These results contribute to our understanding of the mechanism of DNA annealing catalyzed by RecQ family helicases.     

中学政治教学的改革与创新

为适应教育改革的要求,由应试教育向素质教育转变,实施创新教育,促进中学政治教学改革势在必行.本人对此谈几点个人看法.     

关于企业文化的思考

企业文化是企业发展中强大的内在驱动力量，对企业发展具有重要的导向作用和推动作用。它可以沟通员工的思想和情感，凝聚员工的力量，可以使员工围绕企业的共同愿景，树立奋发进取的团队意识。     

沉管法施工粒料桩加固地基应用与分析

文章对设计成桩工艺、质量控制、效果检验等，提出全面的分析判断，对今后应用该法进行软土地基加固，具有良好的借鉴意义。     

GaAs上Ge薄膜的性能研究

用超高真空镀膜机在半绝缘GaAs衬底上蒸镀800nmGe,Ge薄膜在500度以上退火有再结晶过程，退火后由非晶变成多晶，在Ge和GaAs界面处有互扩散，电特性研究表明退火后Ge薄膜呈高浓度p型，可能是由于Ga扩散到Ge中的掺杂或是Ge的缺陷行为所致。     

盾构开挖引起邻近桩基水平位移的简化计算方法

基于盾构开挖侧穿邻近桩基引起桩-土相互作用的实际工况,提出了一种可预测桩基水平变形的简化计算方法. 采用两阶段法获得盾构开挖引起邻近桩基水平位移简化计算方法,第一阶段采用Loganathan公式计算盾构开挖引起邻近桩基轴线处土体自由水平位移场;第二阶段把桩基简化成 Euler-Bernoulli 梁放置在 Vlasov 地基模型上,建立桩基水平位移控制方程,结合桩基两端约束情况,采用差分法获得邻近桩基的水平位移矩阵解. 随后考虑群桩之间的土体遮拦效应,进一步获得邻近群桩的水平变形差分解 . 通过与两个既有工程案例实测以及既有地基模型计算结果对比,验证了本文方法的优越性. 群桩参数分析表明：地层损失率及隧道埋深的增大均会引起邻近群桩水平位移的增大,但桩身产生最大位移处会随着隧道埋深增加而增大;桩隧之间间距的增大会引起邻近群桩水平位移的减小,但其减小速率逐渐变缓.     

盐家深层砂砾岩低品位储量开采价值评价研究

确定了盐家深层砂砾岩低品位储量开发项目的经济评价期、剩余控制储量的累计产量、开发数据、总投资、总成本费用、销售收入、税金及附加和所得税等基础数据;然后依据基础数据,利用净现值法和非风险中性条件下B～S的定价法确定盐家深层砂砾岩低品位储量的全部开采价值;最后给出评价结论,即盐家深层砂砾岩低品位储量的全部开采价值313 393×104元,达到中石化基准收益率要求,具有较高开采价值.     

固体电解质陶瓷在渗氧诱导期的吸氧和放氧行为

根据CaO-ZrO_2陶瓷渗氧实验结果,用数值模拟方法研究了渗氧诱导期固体电解质吸氧(或放氧)的行为,发现用非守常的化学扩散系数计算的渗氧速率曲线与实验结果符合,吸氧流量及达到稳定态渗氧的时间随杂质氧化铁含量增加而增加,不含氧化铁的样品可减小极化并缩短电池电动势的响应时间。     

长钢梁工作面合理支护设计的研究

本文根据4202长钢梁工作面原支护设计下的实测,提出了用支柱的初撑力代替工作阻力设计的思路,通过理论分析和初撑力调压试验,论证了4202工作面只有用初撑力设计才是合理的,为长钢梁工作面的合理支护设计提供了方法。