Pull-in Instability Analysis of Nanoelectromechanical Rectangular Plates Including the Intermolecular,Hydrostatic, and Thermal Actuations Using an Analytical Solution Methodology

The current paper presents a thorough study on the pull-in instability of nanoelectromechanical rectangular plates under intermolecular, hydrostatic, and thermal actuations. Based on the Kirchhoff theory along with Eringen's nonlocal elasticity theory, a nonclassical model is developed. Using the Galerkin method(GM), the governing equation which is a nonlinear partial differential equation(NLPDE) of the fourth order is converted to a nonlinear ordinary differential equation(NLODE) in the time domain. Then, the reduced NLODE is solved analytically by means of the homotopy analysis method. At the end, the effects of model parameters as well as the nonlocal parameter on the deflection, nonlinear frequency, and dynamic pull-in voltage are explored.     

Spherical hollow mesoporous silica supported phosphotungstic acid as a promising catalyst for α-arylstyrenes synthesis via Friedel-Crafts alkenylation

This work presents a scalable approach for preparing spherical hollow mesoporous silica with high surface area/pore volume, serving as outstanding support for supported phosphotungstic acid catalyst with much superior catalytic performance to the one on previously reported spherical mesoporous silica toward diverse transformations, ascribed to the strengthened mass transfer and the enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology.     

An asymptotic Reissner–Mindlin plate model

A mathematical study via variational convergence of a periodic distribution of classical linearly elastic thin plates softly abutted together shows that it is not necessary to use a different continuum model nor to make constitutive symmetry hypothesis as starting points to deduce the Reissner–Mindlin plate model.     

柱面微通道板的制备及其性能研究

针对未来空间天文学应用的超分辨率光谱成像仪器的需求，对低噪声柱面微通道板（MCP）的制备方法及其性能进行了研究. 提出了一种将光学抛光与热成型相结合的新的柱面MCP制备方法，利用不含放射性元素的低噪声MCP玻璃，制备出曲率半径为400mm、尺寸为30mm′46mm、长径比为80:1、通道直径12.5mm、通道间距15mm的柱面MCP，并将其与感应电荷楔条形阳极（WSA）组成光子计数探测器，对其暗计数率、分辨率进行了检测，暗计数率约为0.1counts/cm2×s.     

Structural response of stiffened plates in similitude under a turbulent boundary layer excitation

In structural dynamics, similitude laws usually deal with simple configurations as thin flat plates with point forces. Only recently, few papers have analyzed stiffened shells or stochastic pressure loads.This research activity extends the applicability of some similitude laws, developed for thin flat plates under a turbulent boundary layer load, to ribbed plates forced by the same wall pressure fluctuations.The work addresses the problem of designing a scaled experimental test-article and, successively, of re-modulating the measured data in order to get the structural response of an original (unscaled) configuration.Due to the complexity of the structural domain, the design of a scaled configuration leads to a distorted similitude. Then, a simple approach, to circumvent the distortion effects, is proposed.     

Palladium/graphitic carbon nitride catalyst for selective oxygen transfer in Wacker oxidation

Nanoscaled palladium particles supported on graphitic carbon nitride (Pd⁰/g-C₃N₄) is prepared to improve the oxygen transfer in Wacker oxidation via chemical reduction method. From the analysis of FT-IR, XRD, SEM, TEM, XPS and ICP, Pd⁰ particles are firmly combined with g-C₃N₄ layers, and sub-surface ones occupy most of the components. It is worth mentioning that graphene oxide (GO), which is completely recyclable without further pollution, can be used as a ‘solid weak acid’ taking the place of H₂SO₄ and CF₃COOH. Under the optimization conditions, as many as 46 kinds of olefins are transferred into corresponding products with satisfactory yields, and o-methyl styrene gets the highest yield of 94%. After five times of recycling experiment, the yield of acetophenone only decreases by about 7.0% in the uniform reaction process. In virtue of former research results and molecular electrostatic potential, a possible mechanism is put forward to explain the catalytic process.     

无溶剂热处理固相转化法简易制备沸石咪唑酯骨架材料

设计开发了一种无需溶剂，通过热处理固相转化制备沸石咪唑酯骨架材料（ZIFs）的简易方法.该方法无需溶剂及其它预处理，只需将金属源与有机配体固相混合后于低温（200℃）热处理即可实现多孔晶体材料的制备.所合成材料H-ZIF-67为具有方纳石拓扑结构的纳米晶体，与传统方式合成的ZIFs材料一致.粉末X射线衍射（PXRD）分析结果表明产物的晶体结构与标准ZIFs谱图一致.通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、N₂吸附-脱附分析、热重分析（TGA）和傅里叶变换红外光谱（FTIR）等手段对合成的材料进行了表征，发现H-ZIF-67材料具有与ZIFs材料类似的特性.该方法经济、高效，摒弃了传统方法合成ZIFs材料周期长、处理过程复杂的弊端，为ZIFs材料的量产提供了新思路.     

In Situ Enzyme Immobilization by Covalent Organic Frameworks

Enzyme immobilization is a widely reported method to favor the applicability of enzymes by enhancing their stability and re-usability. Among the various existing solid supports and immobilization strategies, the in situ encapsulation of enzymes within crystalline porous matrices is a powerful tool to design biohybrids with a stable and protected catalytic activity. However, to date, only a few metal–organic frameworks (MOFs) and hydrogen-bonded organic frameworks (HOFs) have been reported. Excitingly, for the first time, Y. Chen and co-workers expanded the in situ bio-encapsulation to a new class of crystalline porous materials, namely covalent organic frameworks (COFs). The enzyme@COF materials not only exhibited high enzyme loading with minimal leaching, high catalytic activity and selectivity, chemical and long-term stability and recyclability but could also be scaled up to a few grams. Undoubtedly, this work opens new striking opportunities for enzymatic immobilization and will stimulate new research on COF-based matrices.     

Single Crystalline,Non-stoichiometric Cocrystals of Hydrogen-Bonded Organic Frameworks

Porous frameworks composed of non-stoichiometrically mixed multicomponent molecules attract much attention from a functional viewpoint. However, their designed preparation and precise structural characterization remain challenging. Herein, we demonstrate that cocrystallization of tetrakis(4-carboxyphenyl)hexahydropyrene and pyrene derivatives ( CP-Hp and CP-Py , respectively) yields non-stoichiometric mixed frameworks through networking via hydrogen bonding. The composition ratio of CP-Hp and CP-Py in the framework was determined by single crystalline X-ray crystallographic analysis, indicating that the mixed frameworks were formed over a wide range of composition ratios. Furthermore, microscopic Raman spectroscopy on the single crystal indicates that the components are not uniformly distributed such as ideal solid solution, but are done gradationally or inhomogeneously.