Tunable gold catalysts for selective hydrocarbon oxidation under mild conditions

Oxidation is an important method for the synthesis of chemical intermediates in the manufacture of high-tonnage commodities, high-value fine chemicals, agrochemicals and pharmaceuticals: but oxidations are often inefficient. The introduction of catalytic systems using oxygen from air is preferred for 'green' processing. Gold catalysis is now showing potential in selective redox processes, particularly for alcohol oxidation and the direct synthesis of hydrogen peroxide. However, a major challenge that persists is the synthesis of an epoxide by the direct electrophilic addition of oxygen to an alkene. Although ethene is epoxidized efficiently using molecular oxygen with silver catalysts in a large-scale industrial process, this is unique because higher alkenes can only be effectively epoxidized using hydrogen peroxide, hydroperoxides or stoichiometric oxygen donors. Here we show that nanocrystalline gold catalysts can provide tunable active catalysts for the oxidation of alkenes using air, with exceptionally high selectivity to partial oxidation products ( approximately 98%) and significant conversions. Our finding significantly extends the discovery by Haruta that nanocrystalline gold can epoxidize alkenes when hydrogen is used to activate the molecular oxygen; in our case, no sacrificial reductant is needed. We anticipate that our finding will initiate attempts to understand more fully the mechanism of oxygen activation at gold surfaces, which might lead to commercial exploitation of the high redox activity of gold nanocrystals.     

基于碰撞反馈的冗余机器人避障规划算法

针对复杂封闭类管道零件喷涂过程中避障的需求,该文提出了一种基于碰撞反馈的冗余机械臂避障算法,该算法利用投影相交法进行碰撞检测,将碰撞类型分为可规避碰撞及不可规避碰撞两类：针对可规避碰撞,提出了关节权值动态调整算法,通过加强对碰撞关节的运动限制,同时放宽对其他关节的约束,实现自运动优化避障;针对不可规避碰撞,提出了基于\"杠杆原理\"的调整方法,通过调整目标点的姿态实现避障。最后,通过设计关节加速度的优化函数对轨迹进行优化以减少机器人的冲击惯性。通过仿真实验,验证了上述算法的可行性。     

The Rab8 GTPase regulates apical protein localization in intestinal cells

A number of proteins are known to be involved in apical/basolateral transport of proteins in polarized epithelial cells. The small GTP-binding protein Rab8 was thought to regulate basolateral transport in polarized kidney epithelial cells through the AP1B-complex-mediated pathway. However, the role of Rab8 (Rab8A) in cell polarity in vivo remains unknown. Here we show that Rab8 is responsible for the localization of apical proteins in intestinal epithelial cells. We found that apical peptidases and transporters localized to lysosomes in the small intestine of Rab8-deficient mice. Their mislocalization and degradation in lysosomes led to a marked reduction in the absorption rate of nutrients in the small intestine, and ultimately to death. Ultrastructurally, a shortening of apical microvilli, an increased number of enlarged lysosomes, and microvillus inclusions in the enterocytes were also observed. One microvillus inclusion disease patient who shows an identical phenotype to Rab8-deficient mice expresses a reduced amount of RAB8 (RAB8A; NM_005370). Our results demonstrate that Rab8 is necessary for the proper localization of apical proteins and the absorption and digestion of various nutrients in the small intestine.     

引射式压力恢复系统的振动抑制技术

为了提高引射式压力恢复系统振动抑制性能,减小本系统振动对其他系统的影响,分析了系统的振动特性和振型,建立了系统振动力和主振型数学模型,利用时域信号取均方根方法测试了系统3个支座动态振动力,振动力沿气流方向逐渐减小。采用被动控制振动抑制技术,根据振动力设计制作了减振器,研究了橡胶块与金属弹簧并联再加配重以及橡胶块加配重2种减振器模型的减振效果。结果表明:橡胶块与金属弹簧并联、加配重45.2kg的减振器模型减振效果好,当控制点输入加速度为5 g时,减振效果最佳。激励强度大小、弹簧刚度和阻尼等参数的优化能够提高减振器的减振性能。     

数位时代图书馆馆员专业知能发展之研究——以逢甲大学为例

受到资讯媒体新科技影响 ,图书馆读者使用行为已从单一的馆藏利用 ,转为期望图书馆提供更多元化的服务 ;另外在财政紧缩 资源扩增 人力不足等因素下 ,图书馆提供各类型服务的运作模式也受到相当的冲击 ,图书馆为提供以读者为道向的服务 ,必需付出许多努力并改变服务哲学 ,因而图书馆馆员的专业知能发展要不断提升才能因应数位时代的环境改变 ,并提供读者一个优质的资讯服务 ,发挥图书馆LearningResourceCenter学习资源中心的角色 .本研究主要探讨图书馆如何在有限资源下 ,有系统地规划发展馆员专业知能 ,并且利用那一种方法可以最有效率、花费最少成本达到最大的馆员能力提升效果 ,根据文献探讨以及学习行为方法理论 ,提出一个适合发展馆员专业知能的模式 (Approachmodel) ,通过探讨逢甲大学图书馆的两个专案其馆员专业知能转变的历程 ,检视了此发展模式的成效 ,并提出未来该模式可再改进的方向及建议     

基于SIMULINK的Fuzzy-PID控制器设计

设计了一种Fuzzy-PID控制算法，利用MATLAB的SIMULINK进行仿真研究，结果表明，该控制器具有较强的抗干扰能力和鲁棒性，有较好的动、静态控制精度．     

Analysis of the DNA sequence and duplication history of human chromosome 15

Here we present a finished sequence of human chromosome 15, together with a high-quality gene catalogue. As chromosome 15 is one of seven human chromosomes with a high rate of segmental duplication, we have carried out a detailed analysis of the duplication structure of the chromosome. Segmental duplications in chromosome 15 are largely clustered in two regions, on proximal and distal 15q; the proximal region is notable because recombination among the segmental duplications can result in deletions causing Prader-Willi and Angelman syndromes. Sequence analysis shows that the proximal and distal regions of 15q share extensive ancient similarity. Using a simple approach, we have been able to reconstruct many of the events by which the current duplication structure arose. We find that most of the intrachromosomal duplications seem to share a common ancestry. Finally, we demonstrate that some remaining gaps in the genome sequence are probably due to structural polymorphisms between haplotypes; this may explain a significant fraction of the gaps remaining in the human genome.     

建筑用铝合金的疲劳性能试验

作为一种建筑金属材料,铝合金对应力集中和裂纹比较敏感。经过固熔热处理、人工时效、挤压成型等处理后,铝合金构件的疲劳强度相对较低,抗疲劳能力差。为研究6061-T 6和6005-T 5两种典型的铝合金材料的疲劳性能,通过常规试验方法分别对这两组铝合金光滑板试件进行了轴向拉伸疲劳试验。在循环次数为104~2×106时测定了两种材料的S-N曲线。试验结果发现:铝合金的疲劳强度大致与抗拉强度成正比,抗拉强度高的疲劳强度也高。     

基于AHRS反馈的仿人机器人步行稳定控制

以实现仿人机器人步行稳定控制为目的,为克服零力矩点（ZMP）反馈控制算法不能补偿较大冲击干扰以及反射响应方法打断当前步行任务的缺点,以低成本微机电系统（MEMS）传感器及方向余弦矩阵描述的补偿算法构成航姿参考系统。提出了由姿态转角和角速度的线性组合表达的步行稳定性判据,并实现了躯干姿态校正的比例-微分控制器。基于仿人机器人全方位步态规划方法,调整下一步步幅和步频为行为方式,实现了步行稳定控制。样机实验结果表明：在原地踏步和稳定前进等情况下,机器人受到冲击干扰以致倾斜角度达20°时,仍能够不打断全方位步行且有效避免倾覆。     

Optimal Restoration Scheduling of Damaged Networks Under Uncertain Environment by Using Improved Genetic Algorithm

The purpose of this research is to propose an early restoration for lifeline systems after earthquake disasters. The previous researches show that the optimization of the restoration schedule by using genetic algorithm (GA) is powerful. However, those are not considering the uncertain environment after earthquake disasters. The circumstances of the damage at devastated areas are very changeable due to the aftershock, fire disaster and bad weather. In addition, the restoring works may delay by unexpected accidents. Therefore, it is necessary to obtain the restoration schedule which has robustness, because the actual restoring works could not progress smoothly under the uncertain environment. GA considering uncertainty (GACU) can treat various uncertainties involved, but it is difficult to obtain the robust schedule. In this study, an attempt is made to develop a decision support system of the optimal restoration scheduling by using the improved GACU.