Phase separation in polymer blends comprising copolymers: 6. Effect of molecular architecture of block copolymers

To study the effect of the molecular architecture of a copolymer on its miscibility with corresponding homopolymers a series of block copolymers of styrene and isoprene with diblock, triblock and four-arm star architectures have been prepared and the morphologies of the blends of the copolymers and polyisoprene with different molecular weights have been examined by electron microscopy. The results show that miscibility varies in the sequence diblock>triblock>four-arm star copolymers. This sequence is in the opposite direction to the variation of the architectural complexity of the block copolymers, i.e. the more complex is molecular architecture, the greater is conformation restriction in microdomain formation and the less is solubility of homopolymer in corresponding domains.     

Study of different effect on foaming process of biodegradable bionolle in supercritical carbon dioxide

Microcellular foaming of biodegradable Bionolle in supercritical CO₂ has been produced. The effects of a series of variable factors, such as saturation temperature, saturation pressure, and depressurization time and step on the foam structures and density, were studied through measurement of density and SEM observation. The experimental results show that higher saturation temperatures lead to an increase in bulk densities; and different depressurization time and step result in different product cell morphology. In addition, at some saturation temperature, the orientation of the cells can be found in the product morphology. XRD experimental results show that the foaming treatment with SC CO₂ increased the crystallinity of Bionolle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2901–2906, 2006     

Isolation and characterization of ganglioside 9-O-acetyl-GD3 from bovine buttermilk

Bovine buttermilk contains a unique ganglioside, 9-O-acetyl-GD₃. In order to isolate large quantities of this ganglioside, a simplified isolation scheme which consists of several ion-exchange and silica gel column chromatographic procedures was devised. The isolated 9-O-acetyl-GD₃ was characterized on the basis of its thin-layer chromatographic behavior, its immunoreactivity with a specific monoclonal antibody, JONES, and by conversion to authentic GD₃ by mild base treatment.     

社会网络的隐私保护研究综述*

某些网站将匿名处理后的社会网络数据公开发布,或者提供给科研机构、大学或者其他组织和个人使用,而这些数据往往侵犯了用户的隐私,但有关社会网络中个人信息安全和隐私保护的研究却处于起步阶段。综述了当前在线社会网络的研究成果,主要就社会网络及其隐私漏洞、信息泄露、再识别攻击、聚集攻击、推理攻击等进行了分析,并对今后的发展提出了预测,为社会网络的科研指出了可行的研究方向。     

DTN中基于服务等级的Push-Pull拥塞控制研究*

提出了一种基于服务等级的拥塞控制机制,通过为后续高优先级业务预留缓存资源的方法来减小容迟网络(DTN)中由于保管传输协议造成节点缓存资源的耗尽而引起的网络拥塞,从而改善服务质量。仿真结果表明,该拥塞控制方法在缓解网络拥塞的同时可以有效改善高优先级业务的传输性能,但其在一定程度上牺牲了低优先级业务的服务质量。     

多维超几何分布的最可能成功数

超几何分布是一种重要的离散型概率分布,本文利用反证法以及比较法求出了三维超几何分布的最可能成功次数,并在此基础上,求出了多维超几何分布的最可能成功次数.     

GM(1,1)模型在虚拟仪器测量过程控制中的应用

虚拟仪器的测量过程控制是保证测量数据有效的重要手段,利用灰色系统GM(1,1)模型对虚拟仪器的测量过程进行控制,由少量数据信息得到未来的预期测量结果,通过与核查标准的测量结果相比较来判别测量过程是否受控.论文给出了测量过程控制判别限、适用灰色系统GM(1,1)模型的条件以及模型精度检验判据.     

E-learning过程中的教师介入

以中介作用理论为依据,以费厄斯坦所划分的教师中介作用的十二项特征为指导,探讨在现代信息技术辅助下大学英语教师如何从学习兴趣、学习动机、学习策略、自我控制等方面介入学生的英语学习,从而使学生成为真正的自主学习者.     

Investigation on film cooling characteristics from a row of converging slot-holes on flat plate

Experimental and numerical researches were conducted to investigate the cooling performance of a single row of consoles (converging slot-hole) on a large-scale flat-plate model. The results show that the coolant flow from a row of consoles shows good lateral uniformity of adiabatic effectiveness, with regions of slightly enhanced cooling occurring between the consoles. For the console cooling geometry, the interaction between coolant jet from inclined console and the mainstream flow results in reasonable vo...     

软件开发教学中知识演化和团队协作工具研究

研究一种能更好支持软件开发过程教学中团队构建和知识获取的工具。以协作式理论为基础,从团队协作的需要入手讨论相关的工具支持。该工具的核心是一个采用分布式架构的能够进行软件建模,并能有效支持冲突消解的电子白板系统,主要采用集中控制的方法对电子白板对象进行控制,以避免用户对白板对象操作的冲突;采用双令牌算法对用户语音发言进行控制,使用户的交流更加自然。该系统能够有效地提高学习者的参与积极性和对知识理解的一致性,能够大大提高软件开发教学的效果。