草酸中多孔阳极氧化铝膜生长动力学和形态结构研究

为分析多孔阳极氧化铝膜形态参数和氧化条件的关系,在恒流条件下对0.3 mol·L-1草酸电解中形成多孔膜的生长动力学进行了研究.采用扫描电子显微镜和氧化膜质量测定方法检验了电流密度、温度和氧化时间对氧化膜生长动力学和氧化膜形态的影响.通过电压-时间曲线研究了氧化膜的电化学特征,并采用一元线性回归模型预测了氧化膜的生长速率.实验结果表明氧化膜的生长速率随电流密度的升高而升高,随温度的升高而下降.氧化膜质量的增长速率也随着电流密度的升高而增大.     

基于扩展的层次有色petri网的组合服务测试用例生成

为了更好地对Web组合服务中各个服务间的交互行为进行测试,提出了一种基于扩展的层次有色petri网的组合服务测试用例生成方法.首先将OWL-S文档映射成为扩展的层次有色petri网,使其中丰富的语义信息、数据流信息和控制流信息模型化.然后利用扩展的层次有色petri网,着重对各服务之间的数据流关系进行分析,找到所有的输出输入定义使用链,并将其扩展成可执行的测试序列,最后将测试序列和测试数据组合,生成测试用例.其中生成的所有测试序列符合全定义一使用路径覆盖标准.     

Three-dimensional atomic-scale structure of size-selected gold nanoclusters

An unambiguous determination of the three-dimensional structure of nanoparticles is challenging. Electron tomography requires a series of images taken for many different specimen orientations. This approach is ideal for stable and stationary structures. But ultrasmall nanoparticles are intrinsically structurally unstable and may interact with the incident electron beam, constraining the electron beam density that can be used and the duration of the observation. Here we use aberration-corrected scanning transmission electron microscopy, coupled with simple imaging simulation, to determine with atomic resolution the size, three-dimensional shape, orientation and atomic arrangement of size-selected gold nanoclusters that are preformed in the gas phase and soft-landed on an amorphous carbon substrate. The structures of gold nanoclusters containing 3096 atoms can be identified with either Ino-decahedral, cuboctahedral or icosahedral geometries. Comparison with theoretical modelling of the system suggests that the structures are consistent with energetic considerations. The discovery that nanoscale gold particles function as active and selective catalysts for a variety of important chemical reactions has provoked much research interest in recent years. We believe that the detailed structure information we provide will help to unravel the role of these nanoclusters in size- and structure-specific catalytic reactions. We note that the technique will be of use in investigations of other supported ultrasmall metal cluster systems.     

NUMB controls p53 tumour suppressor activity

NUMB is a cell fate determinant, which, by asymmetrically partitioning at mitosis, controls cell fate choices by antagonising the activity of the plasma membrane receptor of the NOTCH family. NUMB is also an endocytic protein, and the NOTCH-NUMB counteraction has been linked to this function. There might be, however, additional functions of NUMB, as witnessed by its proposed role as a tumour suppressor in breast cancer. Here we describe a previously unknown function for human NUMB as a regulator of tumour protein p53 (also known as TP53). NUMB enters in a tricomplex with p53 and the E3 ubiquitin ligase HDM2 (also known as MDM2), thereby preventing ubiquitination and degradation of p53. This results in increased p53 protein levels and activity, and in regulation of p53-dependent phenotypes. In breast cancers there is frequent loss of NUMB expression. We show that, in primary breast tumour cells, this event causes decreased p53 levels and increased chemoresistance. In breast cancers, loss of NUMB expression causes increased activity of the receptor NOTCH. Thus, in these cancers, a single event-loss of NUMB expression-determines activation of an oncogene (NOTCH) and attenuation of the p53 tumour suppressor pathway. Biologically, this results in an aggressive tumour phenotype, as witnessed by findings that NUMB-defective breast tumours display poor prognosis. Our results uncover a previously unknown tumour suppressor circuitry.     

TaqMan MGB实时荧光PCR对转基因大豆定量检测的研究

 利用实时荧光定量PCR技术,根据转基因大豆（Roundup Ready^TM）的外源基因35S启动子序列设计引物和TaqMan MGB探针,对大豆粉中Roundup Ready^TM大豆含量进行了定量检测,根据这个检测体系建立了35S启动子Ct值与样品中转基因成分数量之间的标准曲线和线性回归方程(相关系数r²: 0.9942)。本研究设计的方法还可以应用到多组分的食品、饲料等加工产品,检测转基因成分的含量,并可作为转基因食品常规PCR定性检测方法。     

硫酸盐还原菌多相分类系统的研究进展

自硫酸盐还原菌由Beijerinck发现并命名至今,其分类地位一直处于不断的变化之中。近年来,随着一些新种的发现和新的分析方法应用,硫酸盐还原菌分类手段已由传统的形态学分类方法向现代的多相分类法过渡。本文阐述了经典分类法、化学分类法、分子分类法在硫酸盐还原菌分类中的应用,并对它们的优缺点作了简要的评价。     

SiCp/7A04铝基复合材料的高温变形行为

在Gleeble-3500热模拟机上对SiCp/7A04铝基复合材料在应变速率为0.001~1 s-1、变形温度为300~450℃条件下的流变行为进行了研究.结果表明:在实验范围内,SiCp/7A04铝基复合材料热压缩变形时均存在较明显的稳态流变特征;真应力随温度升高而降低,随应变速率的增加而升高;金相组织观察表明,动态再结晶是SiCp/7A04复合材料软化的一个重要机制,变形温度越高,动态再结晶越充分;应变速率越大,再结晶晶粒就越小.可以用包含Arrhenius项的Z参数描述SiCp/7A04复合材料高温变形时的流变行为,其中变形激活能Q=159.87 kJ/mol.     

需求不确定条件下供应链之间的库存竞争策略

在考虑市场需求波动的条件下,从供应链核心企业的角度出发,研究两条供应链之间的库存竞争行为.讨论了当供应链采取集中控制和分散决策时的最优库存策略,比较了不同供应链竞争模式下的均衡库存水平和利润,并运用仿真方法分析需求波动对核心企业利润的影响.研究结果为供应链核心企业在竞争环境下的供应链管理提供了理论依据,有助于提升供应链库存管理水平.     

Exploration of energy conservation MAC protocol of WSNs for ubiquitous environment

According to analyze the facade phenomenon of wire-less sensor networks（WSNs）,this paper proposes a feasible method to state clearly and improve the power control efficiency of wire-less sensor networks（WSNs）. One of the crucial problems for WSNs is the design of medium access control （MAC） protocol. Our method want to adjust the activities of the MAC protocols control to achieve the enery conservation when the wireless communication module of sensor nodes is running, which is the major consumer of energy consumed by sensors energy. The energy efficiency of MAC protocol makes a strong impact on the network performance. To some extent,our research work describes and analyze the sources of energy consumption in MAC layer and simultaneously present an optimal method for the design of MAC protocol. Then we discusses some factors impacting on the performance of MAC protocol and metrics of performance evaluation. Eventually, the coming research direction is summarized.