原位聚合法制备聚苯胺/ 聚乙烯醇导电材料的研究

采用原位聚合方法合成了聚苯胺／聚乙烯醇导电复合材料,研究了反应体系中聚苯胺的质量分数和反应时间对复合材料电导率的影响,并且通过红外光谱和热重分析对其结构和稳定性进行了表征和分析．     

Phylogenetic position of Schnabelia, a genus endemic to China： Evidence from sequences of cpDNA matK gene and nrDNA ITS regions

The chloroplast gene matK and the internal transcribed spacers (ITS) of the nuclear ribosomal DNA from Schnabelia, a genus endemic to China, and 6 genera of Verbenaceae and 13 genera of Lamiaceae were sequenced. The phylogenetic signal and validity outgroups were measured and evaluated by means of the relatively apparent synapomorphy analysis (RASA). Independent and combined phylogenetic analyses for the matK and ITS sequences were performed using the maximum parsimony (MP), neighbor-joining (NJ) and maximum likelihood (ML) methods, indicating that Schnabelia oligophylla and Caryopteris terniflora form a sister-group relationship. The Caryopteris complex is not shown to be a monophyly because Trichostema, C. paniculata and C. forrestii are paraphyletic to the clade containing the remaining members of the complex. A monophyly of Ajugoideae proposed by Cantino et al., including 8 genera in this study, is strongly supported and the closest relatives of Schnabelia are in the Ajugoideae (Lamiaceae), especially near Caryopteris terniflora. The polygenetic analyses also showed that the genera of Lamiaceae and Verbenaceae sampled in this tudy are phylogenetically mixed and the genus Avicennia is distant to other genera of Verbenaceae. RASA and combined analysis can be used as effective approaches to determining the relationships among phylogenetically complex groups.     

Adsorption and catalytic combustion of ARB on CuO-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>

CuO-Fe2O3 composite material with strong magnetism and a large surface area is prepared by the co-precipitate method. Its adsorption properties towards Acid Red B (ARB) and the regeneration by catalytic combastion of organic compounds have been studied. The results show that the prepared CuO-Fe2O3 composite is an excellent adsorbent for ARB adsorption at acid condition. The presence of Cl^- has no effect on ARB adsorption. But the SO4^2- can inhibit ARB adsorption. After being recovered by the magnetic separation method, the adsorbent can be regenerated by catalytic oxidation of absorbate at 300℃ in air atmosphere. The combustion reactions of ARB in the presence or absence of CuO-Fe2O3 are studied by in situ diffuse refieclion FTIR. The results indicate that, in the presence of CuO-Fe2O3, the degradation temperature is significantly lowered by the catalysis of CuO-Fe2O3, and ARB can be oxidized completely without volatile organic compound by-product; in comparison, in the absence of CuO-Fe2O3, the temperature needed for oxidation of ARB is higher and the reaction is incomplete with some N-containing harmful compounds produced. The reusability of CuO-Fe2O3 is also studied in successive seven adsorption-regeneration cycles.     

Single-crystal gallium nitride nanotubes

Since the discovery of carbon nanotubes in 1991 (ref. 1), there have been significant research efforts to synthesize nanometre-scale tubular forms of various solids. The formation of tubular nanostructure generally requires a layered or anisotropic crystal structure. There are reports of nanotubes made from silica, alumina, silicon and metals that do not have a layered crystal structure; they are synthesized by using carbon nanotubes and porous membranes as templates, or by thin-film rolling. These nanotubes, however, are either amorphous, polycrystalline or exist only in ultrahigh vacuum. The growth of single-crystal semiconductor hollow nanotubes would be advantageous in potential nanoscale electronics, optoelectronics and biochemical-sensing applications. Here we report an 'epitaxial casting' approach for the synthesis of single-crystal GaN nanotubes with inner diameters of 30-200 nm and wall thicknesses of 5-50 nm. Hexagonal ZnO nanowires were used as templates for the epitaxial overgrowth of thin GaN layers in a chemical vapour deposition system. The ZnO nanowire templates were subsequently removed by thermal reduction and evaporation, resulting in ordered arrays of GaN nanotubes on the substrates. This templating process should be applicable to many other semiconductor systems.     

LDL-receptor-related proteins in Wnt signal transduction

The Wnt family of secreted signalling molecules are essential in embryo development and tumour formation. The Frizzled (Fz) family of serpentine receptors function as Wnt receptors, but how Fz proteins transduce signalling is not understood. In Drosophila, arrow phenocopies the wingless (DWnt-1) phenotype, and encodes a transmembrane protein that is homologous to two members of the mammalian low-density lipoprotein receptor (LDLR)-related protein (LRP) family, LRP5 and LRP6 (refs 12-15). Here we report that LRP6 functions as a co-receptor for Wnt signal transduction. In Xenopus embryos, LRP6 activated Wnt-Fz signalling, and induced Wnt responsive genes, dorsal axis duplication and neural crest formation. An LRP6 mutant lacking the carboxyl intracellular domain blocked signalling by Wnt or Wnt-Fz, but not by Dishevelled or beta-catenin, and inhibited neural crest development. The extracellular domain of LRP6 bound Wnt-1 and associated with Fz in a Wnt-dependent manner. Our results indicate that LRP6 may be a component of the Wnt receptor complex.     

环境化学污染物与人类健康

中国是经济发展最快的发展中国家之一，一方面快速发展的经济使人民生活不断提高，另一方面环境污染、尤其是环境化学物的严重污染对人体健康带来多种危害，包括呼吸系统疾病、神经系统疾病、肿瘤、出生缺陷等，甚至死亡。毋庸置疑，严重的环境污染可导致受害的众多民众失去健康和劳动能力，甚至丧失生命，是重大的社会问题乃至国际化问题，如著名的英国伦敦烟雾事件、美国洛杉矶汽车尾气事件以及日本新泻的水俣病．     

素超代数上的超对称超双导子

本文给出了超代数上超对称超双导子的定义，并证明：具有非零超对称双导子的非平凡的素超代数一定是可换的．     

PC管桩在宁德车站软基处理中的应用

分析与总结了宁德车站中PC管桩的设计与施工中的重点，提出了PC管桩在实际运用中的一些建议。     

压电陀螺漂移特性的灰色神经网络建模研究

在不同温度和运行时间下,压电陀螺的静态零位漂移和刻度因子变化表现为非线性和多值对应关系,基于时间序列的ARMA模型和直接采用温度单输入的前馈神经网络模型都无法正确描述压电陀螺的这种误差特性。提出一种将温度和时间作为输入,分别同时对应陀螺静态零位和刻度因子输出的三维空间下的单值对应关系,在运用灰色理论对数据进行预处理基础上,采用多输入单输出的RBF神经网络实现了对陀螺漂移特性的描述。仿真实验结果验证了该建模方法的有效性。     

基于观测器的丢包网络控制系统控制器设计

针对网络控制系统的数据包丢失(丢包)问题,提出将网络控制系统中的丢包问题看成是被控对象输入矩阵的切换问题和控制器对象输入矩阵的分别切换问题,进而将网络控制系统看成是由矩阵切换决定的切换律未知的切换系统,将丢包等效为切换系统中子系统之间的切换。采用李雅普诺夫函数方法,对每个由矩阵形式决定的子系统设计了基于观测器的状态反馈控制器。利用线性矩阵不等式(linear matrix inequalities,LMI)的可行解给出了计算状态观测器和控制器的参数化方法。最后通过仿真算例验证了该方法的有效性。