Anion coordination and molecular assembly in C2-substituted thiamine-anion systems: effects of the anion and molecular conformation

The compounds (het)(PtCl6)2H(2)O 1, (het)(HgI4).H2O 2 (het = 2-(alpha-hydroxyethyl)thiamine) and (hpt)(Hg2Br6) 3 (hpt = 2-(alpha-hydroxypropyl)thiamine) have been prepared and structurally characterized by X-ray crystallography in order to study the influence of the anion and molecular conformation on the formation of supramolecular architectures that adsorb anionic species. Both het and hpt molecules adopt the usual S conformation for C2-substituted thiamine but differ from the F conformation for C2-free thiamine derivatives. Two types of characteristic ligand-anion complexation are observed, being of the forms C(6')-H...anion...thiazolium-ring (in 1 and 2) and N(4'1)-H...anion...thiazolium-ring (in 3). The reaction of het with PtCl62- or HgI42- gives a 1-D double-chain in 1, consisting of two hydrogen-bonded het chains, which are cross-linked by anions through hydrogen bonding and anion...aromatic-ring interactions, or a cationic 3-D framework in 2 formed by the stacking of hydrogen-bonded sheets with anion-and-water-filled channels. In the case of 3, hydrogen-bonded hpt dimers and HgBr62- anions form alternate cation-anion columns. A comparison with the cases of C2-free thiamine-anion complexes indicates that the change in molecular conformation results in novel supramolecular assemblies in 1 and 2 and an analogous architecture in 3, which also depends on the nature of the anions.

Electrochemical and spectroscopic study on the interaction of cytochrome c with anionic lipid vesicles

The structure and the electron-transfer of cytochrome c binding on the anionic lipid vesicles were analyzed by electrochemical and various spectroscopic methods. It was found that upon binding to anionic lipid membrane, the formal potential of. cytochrome c shifted 30 mV negatively indicating an eager redox interaction than that in its native state. This is due to the local alteration of the coordination and the heme crevice. The structural Perturbation in which a molten globule-like state is formed during binding to anionic lipid vesicles is more important. This study may help to understand the mechanism of the electron-transfer reactions of cytochrome c at the mitochondrial membrane.

Copolymerization of styrene with butadiene and isoprene using a rare earth catalyst

In the copolymerization of styrene-butadiene and styrene-isoprene, a novel rare earth catalyst system (CF3CO2)(3)Ln/R(3-n)AlH(n)/(CH3)(3)CCH2Br (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; R = Me-, Et-, i-Bu-, and Oct-; n = 0 and 1) has been studied. The 1, 4 unit contents in the copolymers obtained are found to range from 64.4 to 99.6% with St contents of 5.2 to 59.9%, and intrinsic viscosities of 0.1 to 0.5 dl g(-1) measured by i.r., H-1 n.m.r. and C-13 n.m.r. spectra. From the calculated data of linked ratios, a change in the microstructure is induced by the styrene unit, probably adjacent to the butadiene or isoprene unit. An interesting result is that the ratios of styrene unit linked with 1, 2 or 3,4 units in the copolymers are far higher than in copolymers obtained with the nickel catalyst. The experimental results are discussed in terms of rare earth pi-allyl coordination and back-biting mechanism.

机器人及机器人学中的控制问题

机器人已成为进一步实现制造业、非制造业、军事活动以至家庭服务自动化的重要工具.机器人学则是更综合地研究如何使机器或系统具有“思想、感知或动作功能的一门交叉性新学科”.机器人的发展是波浪式的,经历了多次的曲折.目前工业机器人中除装配机器人外,其他点焊、弧焊、喷漆及搬运机器人,由于应用范围限制,以及工业生产装备更新速度和投资规模的影响,市场日趋饱和.以美国为例.制造商订单1984年达到高峰6046台.至1986年下降至5713台,不过对机器人未来市场大都持乐观态度.但进一步开拓市场.有待于推出适用于各种环境作业的各式各样的机器人.日本东京大学教授认为机器人当前处于又一次高潮的前夜(Nightmare),正是需要大力加强研究开发的时期.我国正在着手建立工业机器人产业,这一情况值得我们注意.本文着重从研究角度来介绍当前机器人及机器人学中的控制问题的现状及主要问题.

团队有效性：协作行为与作业特征作用机制研究

Organizations are increasingly turning to team-based structures to contend with the pressure of the increasing global competition, consolidation, innovation and need for diverse skills, expertise, and experiences. This ongoing transformation in the basic organization of work has captured the attention of researcher. And group and team research has become increasingly centered in the fields of organizational psychology and organizational behavior since the 1990s. A great deal empirical studies were conducted; a number of variables contributing to team effectiveness and several IPO models were summarized. But teamwork behaviors, the dynamic and adaptive interactions among team members during the task completion, were still very vague. So were the team task characteristics, an important input variable of the IPO models. The effects of team task characteristics and teamwork behaviors on team effectiveness were explored according to IPO model on the basis of the reviews on previous studies, the Hierarchical Conceptual Structure of Teamwork Behaviors (Rousseau et al.,2006), and the task characteristic theory(Hackman & Oldman, 1975). The questionnaire data from 479 team members and 110 team managers of 22 organizations were analyzed. The results indicate: A. Teamwork behaviors consist of 13 behavioral dimensions: team mission analysis, goal specification, planning, coordination, cooperation, information exchange, performance monitoring, backing-up behaviors, intra-team coaching, collaborative problem solving, team practice innovation, psychological support and integrative conflict management. The hierarchical conceptual structure was partly supported with five variable identified, i.e., preparation of work accomplishment, task-related collaborative behaviors, work assessment behaviors, team adjustment behaviors and the management of team maintenance. The formal four variables are in a sequential way. B. The task characteristic theory at individual level is applicable to the team level. This means that the team task characteristics consist of task variety, identity, significance, feedback, autonomy, interdependence. C. The correlations among task characteristics, teamwork behaviors and outcomes support the IPO model. The regulation of team performance mediated the effects of task meaningfulness and interdependence on team outcomes, with the direct effects of task meaningfulness on the preparation behaviors and the direct effects of interdependence on the task-related collaborative behaviors. The management of team maintenance mediated the effects of autonomy on team cohesion and satisfaction. The regulation of team performance has a direct effect on the team performance and the management of team maintenance. And the management of team maintenance has a direct effect on the team attitude and the regulation of team performance.