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.     

稀磁半导体Zn_（1－x）Mn_xSe外延膜的反射和光致发光谱

测量了用热壁外延（ＨＷＥ）生长的不同组分（０≤ｘ≤０．９８）的Ｚｎ１－ｘＭｎｘＳｅ薄膜在温度为３００Ｋ下的反射光谱，用Ｘ射线能借测定样品实际的组分ｘ值，由此获得了其能隙Ｅｇ与组分ｘ的关系：在Ｏ＜Ｘ＜０．２组分范围，Ｅｇ随ｘ的变化显示了反常现象，当Ｘ＞０．２时，能隙Ｅｇ随ｘ线性增大。在室温和低温下测量了样品的光致发光，除观测到Ｍｎ２＋离子内部４Ｔ１→６Ａ１发光峰外，在其低能边观测到一个较宽的发光峰，对结果进行了分析讨论。     

稀磁半导体Cd_（1－x）Fe_xTe的磁光光谱

在７０－３００Ｋ温度范围内测量了组分ｘ为０．０１和０．０４的Ｃｄ１－ｘＦｅｘＴｅ及ＣｄＴｅ的法拉第效应随入射光子能量的变化，首次获得了Ｃｄ１－ｘＦｅｘＴｅ在布里渊区Γ点和Ｌ点的有效ｇ因子及其与温度的关系。给出了Ｆｅ２＋离子与载流子间的ｓｐ－ｄ交换作用常数Ｎ０（β－α）＝（－１．５７±０．０３）ｅＶ。     

DYNAMICAL ANALYSIS OF A SINGLE-SPECIES POPULATION MODEL WITH MIGRATIONS AND HARVEST BETWEEN PATCHES

A single-species population model with migrations and harvest between the protected patch and the unprotected patch is formulated and investigated in this paper. We study the local stability and the global stability of the equilibria. The research points out, under some suitable conditions, the singlespecies population model admits a unique positive equilibrium, which is globally asymptotically stable. We also derive that the trivial solution is globally asymptotically stable when the harvesting rate exceeds the threshold. Further,we discuss the practical effects of the protection zones and the harvest. The main results indicate that the protective zones indeed eliminate the extinction of the species under some cases, and the theoretical threshold of harvest to the practical management of the endangered species is provided as well. To end this contribution and to check the validity of the main results, numerical simulations are separately carried out to illustrate these results.     

Er离子注入GaP,GaAs, InP的二次离子质谱(SIMS)的研究

近年来掺稀土元素的Ⅲ—Ⅴ族化合物研究在基础物理和器件应用方面都越来越引起人们的关注,[1,2]其中又由于Er3+的4I13/2—4I15/2的特征发光波长为1.54μm,恰好对应于石英光纤的低损耗区,且离子注入技术简单易行,因而倍受重视.国际上已报道了不少有关Er注入Ⅲ—Ⅴ族化合物的研究,大多选用较低的注入剂量(约1012～1014Er/cm2),而对较高剂量的注入有待于进一步研究.     

Xylaropyrones B and C,new γ-pyrones from the endophytic fungus Xylaria sp. SC1440

Two new γ-pyrones, xylaropyrones B (1) and C (2), together with three known compounds, xylaropyrone (3), annularin A (4) and annularin C (5), were isolated from solid cultures of the endophytic fungus Xylaria sp. SC1440. The structures of these compounds were determined mainly by analysis of their NMR spectroscopic data. The relative configurations of 1 and 2 were assigned on the basis of J-based configurational analysis, and the absolute configurations were established by experimental and TDDFT calculated ECD spectra. The isolated compounds were evaluated for cytotoxic and tyrosinase inhibitory activity.     

数字图像相关技术在应力应变测量中的发展与最新应用

在现代材料的应力应变测量中,数字图像相关测量法具有非接触、全场性、对实验条件要求低、精度高等优点,是一种有效、实用的应力应变测量方法,被广泛的应用于实验力学及其他学科领域。本文综述了数字图像相关技术在材料应力应变方面的发展;将数字图像相关技术与其它测量技术进行了比较;介绍了数字图像相关技术的系统结构与相关算法、搜索方法;最后列举了数字图像相关技术在材料应力应变中的最新应用和新产品。     

Quantitative investigations on moving chelation boundary within a continuous EDTA-based sample sweeping system in capillary electrophoresis

Recently, the EDTA-based sweeping of metal ion that combines chelate formation and in-line sample pre-concentration was advanced. However, the moving chelation boundary (MCB) existing in the sweeping system has not been investigated for the quantitative illumination of the mechanism of metal ion sweeping yet. In this paper, the model of MCB was developed from the EDTA-based sweeping. The theoretical studies were performed for boundary movements and controllable sweeping of metal ion. The theoretical studies show that the sweeping system contains the MCB boundary and chelate boundary, and the difference between the MCB and chelate boundary velocities plays a key role in the stacking efficiency of metal ion. To demonstrate the validity of the theoretical conclusion, the experiments of continuous EDTA-based sweeping were performed with CE and a home-made apparatus of a large tube. The home-made apparatus consisted of a glass tube used for the run of continuous EDTA-based sweeping and two peristaltic pumps used for the supply of solution. The experimental results were in accordance with the theoretical conclusions above. The developed theory holds evident for significance for the mechanism of controllable stacking of metal ions in EDTA-based sweeping system in CE.     

Accelerating Ethanol Complete Electrooxidation via Introducing Ethylene as the Precursor for the C−C Bond Splitting

The crucial issue restricting the application of direct ethanol fuel cells (DEFCs) is the incomplete and sluggish electrooxidation of ethanol due to the chemically stable C−C bond thereof. Herein, a unique ethylene-mediated pathway with a 100 % C1-selectivity for ethanol oxidation reaction (EOR) is proposed for the first time based on a well-structured Pt/Al₂O₃@TiAl catalyst with cascade active sites. The electrochemical in situ Fourier transform infrared spectroscopy (FTIR) and differential electrochemical mass spectrometry (DEMS) analysis disclose that ethanol is primarily dehydrated on the surface of Al₂O₃@TiAl and the derived ethylene is further oxidized completely on nanostructured Pt. X-ray absorption and density functional theory (DFT) studies disclose the Al component doped in Pt nanocrystals can promote the EOR kinetics by lowering the reaction energy barriers and eliminating the poisonous species. Strikingly, Pt/Al₂O₃@TiAl exhibits a specific activity of 3.83 mA cm⁻²_Pt, 7.4 times higher than that of commercial Pt/C and superior long-term durability.     

Tunable room-temperature phosphorescence and circularly polarized luminescence encoding helical supramolecular polymer

Supramolecular polymers with different functionalities have been continuously developed in the past decade because of their indispensable role in soft materials.However,pure organic supramolecular polymers with stable room temperature phosphorescence(RTP)emission were very rarely reported for the difficulties of synthesis and achieving RTP in solution.Herein,soluble helical supramolecular polymers with circularly polarized room-temperature phosphorescence were developed via a facile hostguest strategy.Through assembly,a transition from pure fluorescence to almost pure RTP emission was achieved.Adjusting the asymmetry of guest could easily control the chiroptical property of supramolecular polymers.This work provides new opportunities for the design and development of intelligent soft functional soft materials.