A Photoactivated Cu–CeO2 Catalyst with Cu-[O]-Ce Active Species Designed through MOF Crystal Engineering

Fully utilizing solar energy for catalysis requires the integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Herein, a MOF crystal engineering method was developed to controllably synthesize a copper–ceria catalyst with well-dispersed photoactive Cu-[O]-Ce species. Using the preferential oxidation of CO as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and a combinatorial photoactivation strategy for solar energy conversion.     

不同杂环取代(E)-β-Farnesene类似物的合成及生物活性研究

为了寻求新型蚜虫控制剂,以蚜虫报警信息素(E)-β-farnesene(EBF)为先导,引入不同类型的杂环取代EBF结构中不稳定的共轭双键,设计合成了一系列不同杂环取代的EBF类似物.所有化合物结构均通过1H NMR、13C NMR、IR及HRMS确证.对化合物进行了生物活性测试及初步构效关系分析.结果表明,所有化合物均对桃蚜和大豆蚜表现出一定的生物活性,部分化合物的杀虫活性优于先导EBF,酯基的引入则对驱避活性有利.     

Highly dispersed palladium nanoclusters incorporated in amino‐functionalized silica spheres for the selective hydrogenation of succinic acid to γ‐butyrolactone

Highly dispersed palladium nanoclusters incorporated on amino‐functionalized silica sphere surfaces (Pd/SiO₂‐NH₂) were fabricated by a simple one‐pot synthesis utilizing 3‐(2‐aminoethylamino)propyltrimethoxysilane (AAPTS) as coordinating agent. Uniform palladium nanoclusters with an average size of 1.1 nm can be obtained during the co‐condensation of tetraethyl orthosilicate and AAPTS owing to the strong interaction between palladium species and amino groups in AAPTS. The palladium particle size can be controlled by addition of AAPTS and plays a significant role in the catalytic performance. The Pd/SiO₂‐NH₂ catalyst exhibits high catalytic activity for succinic acid hydrogenation with 100% conversion and 94% selectivity towards γ‐butyrolactone using 1,4‐dioxane as solvent at 240°C and 60 bar for 4 h. Moreover, the Pd/SiO₂‐NH₂ catalyst is robust and readily reusable without loss of its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Supramolecular Assembly of TPE-Based Glycoclusters with Dicyanomethylene-4H-pyran (DM) Fluorescent Probes Improve Their Properties for Peroxynitrite Sensing and Cell Imaging

Two red-emitting dicyanomethylene-4H-pyran (DM) based fluorescent probes were designed and used for peroxynitrite (ONOO⁻) detection. Nevertheless, the aggregation-caused quenching effect diminished the fluorescence and restricted their further applications. To overcome this problem, tetraphenylethylene (TPE) based glycoclusters were used to self-assemble with these DM probes to obtain supramolecular water-soluble glyco-dots. This self-assembly strategy enhanced the fluorescence intensity, leading to an enhanced selectivity and activity of the resulting glyco-dot comparing to DM probes alone in PBS buffer. The glyco-dots also exhibited better results during fluorescence sensing of intracellular ONOO⁻ than the probes alone, thereby offering scope for the development of other similar supramolecular glyco-systems for chemical biological studies.     

Significant Acceleration of Photocatalytic CO2 Reduction at the Gas-Liquid Interface of Microdroplets**

Solar-driven CO₂ reduction reaction (CO₂RR) is largely constrained by the sluggish mass transfer and fast combination of photogenerated charge carriers. Herein, we find that the photocatalytic CO₂RR efficiency at the abundant gas-liquid interface provided by microdroplets is two orders of magnitude higher than that of the corresponding bulk phase reaction. Even in the absence of sacrificial agents, the production rates of HCOOH over WO₃ ⋅ 0.33H₂O mediated by microdroplets reaches 2536 μmol h⁻¹ g⁻¹ (vs. 13 μmol h⁻¹ g⁻¹ in bulk phase), which is significantly superior to the previously reported photocatalytic CO₂RR in bulk phase reaction condition. Beyond the efficient delivery of CO₂ to photocatalyst surfaces within microdroplets, we reveal that the strong electric field at the gas-liquid interface of microdroplets essentially promotes the separation of photogenerated electron-hole pairs. This study provides a deep understanding of ultrafast reaction kinetics promoted by the gas-liquid interface of microdroplets and a novel way of addressing the low efficiency of photocatalytic CO₂ reduction to fuel.     

基于波变量补偿的阻抗匹配时延双边遥操作

通信时延是遥操作系统中固有的问题,它会严重影响遥操作的性能,降低系统的稳定性和跟踪性。基于无源理论的波变量法可以保证遥操作系统在任意时延下稳定,是解决时延问题的一个重要方法。然而,波变量法带来的波反射会阻扰有用信号的传输,降低了主从端信号的跟踪性,严重时甚至会导致整个系统振荡。针对这一问题,提出了一种基于波变量补偿的阻抗匹配双边遥操作系统结构,旨在减少波反射,提高操作者的临场感和系统的跟踪性。通过仿真实验,结果表明所提方法能够保证固定时延条件下遥操作系统的稳定性,并具有较好的跟踪性。     

离轴受限圆射流的三维湍流流场分析

利用原始变量,交叉网格的方法,以及采用κ-ε湍流模型,计算了离轴受限射流三维湍流流场,计算结果与用LDV测量结果作了比较,结果是满意的。计算结果提供了这样一个复杂的三维流场的清晰图象,为研究具有离轴射流的预燃室的稳燃机理提供了很多有用的信息,对计算结果作了详细的分析和讨论后,指出这样一个流场的重要三维特征是在θ方向梳线有大角度的扭曲。     

铝合金等离子体淹没氮离子注入层的摩擦学性能研究

用等离子体淹没离子注入技术对ＬＹ１２和ＬＤ１０铝合金表面进行氮离子注入。用俄歇电子能谱分析离子注入层中氮的浓度分布，在此基础上进行了摩擦磨损试验。用扫描电观察和分析磨损表面特征。研究表明：氮离子注入铝合金形成细小，弥散的硬质ＡｌＮ析出相，铝合金表层的显微硬度增加，摩擦系数降低；耐磨性随着注入剂量和电压的增加而提高。磨损机制主要为粘着磨损，随离子注入剂量的增加，粘着磨损趋行减轻。