Facile shape and size-controlled growth of uniform magnetite and hematite nanocrystals with tunable properties

Monodispersed magnetite Fe3O4 and hematite α-Fe2O3 nanocrystals have been grown in co-solvents of alcohol and water. Either the shape or the size of the nanocrystals could be easily controlled. Both the phases and nanostructures have been characterized by powder X-ray diffraction patterns and electron microscopy. The magnetic and catalytic properties of these products were investigated and compared with each other. The obtained results clearly demonstrate that these iron oxide nanocrystals are soft ferromag...     

Synthesis,Bioactivity and Crystal Structure Analysis of Novel Benzo[d]isothiazol-3（2H）-ones

Two compounds,3-oxo-N-o-tolylbenzo[d]isothiazole-2(3H)-carboxamide (1) and N-(2-methoxyphenyl)-3-oxobenzo[d]isothiazole-2(3H)-carboxamide (2),were synthesized from the initial compound benzo[d]isothiazol-3(2H)-one (BIT) and characterized by 1 H NMR,IR and elemental analysis,respectively.The single crystals of compounds 1 and 2 were obtained and determined by X-ray diffraction analysis.The preliminary results of biological activity experiment show that some of the title compounds exhibited a favorable antimicrobial activity.     

Oxygen removal from raw silicon powder by the HF‐ethanol solution etching

Silicon powder is vulnerable to oxidation due to its high surface activity. The as‐prepared Si powder is characterized by X‐ray photoelectron spectroscopy spectra coupled with an oxygen nitrogen analyzer, revealing that oxygen impurities mainly consist of Si oxides but with a small amount of free oxygen. The stable oxide films can deteriorate the properties of sintered materials since they cannot be removed during sintering process. The cleaning of these oxides by a single‐HF solution is not straightforward and efficient due to the large surface tension. To remove the oxygen, a more efficient way with the addition of ethanol to a HF solution has been proposed. The addition of a moderate percent of ethanol can decrease the water contact angle and then improve the cleaning efficiency. Importantly, the resulting Si powder possesses good dispersity, uniformity and fluidity. However, excess hydrofluoric acid suppresses oxide removal. Copyright © 2012 John Wiley & Sons, Ltd.     

采用WDM技术的光纤Bragg光栅传感网络

采用绝对测量原理的波长调制技术,光纤Bragg光栅可组成并行、串行和阵列WDM拓扑结构.分析表明,光纤Bragg光栅网络的工作原理类似于一个多宽带平面镜.利用光谱仪可测量上述光纤Bragg光栅网络的反射谱,其中,光源是宽带为～40nm的掺饵光纤放大器.当网络中的光纤Bragg光栅受扰动后,受扰光栅的反射谱发生相应的变化,即Bragg波长发生相应的偏移.结果表明,当事先确定了光纤光栅的波长调制范围,反射的峰值波长能反应光纤光栅传感网络的信息.值得注意的是～3nm的波长调制范围可满足～100℃和～2000με的参量测量.     

非时齐部分可观察Markov决策规划的最优策略问题

本文讨论了一类非时齐部分可观察Markov决策模型．在不改变状态空间可列性的条件下，把该模型转化为[5]中的一般化折扣模型，从而解决了其最优策略问题，并且得到了该模型的有限阶段逼近算法，其中该算法涉及的状态是可列的．     

碳纳米管负载/促进的Mo-Co加氢脱硫催化剂

 以多壁碳纳米管(CNT)为载体制备了负载型Mo-Co/CNT,并将其用于噻吩HDS反应. 结果表明,在n(C4H4S)/n(H2)= 2.3/97.7, GHSV=2200 ml/(g·h),p=0.1 MPa和T=623 K的条件下,在7.2%(Mo-Co)/CNT催化剂上,噻吩HDS的比反应速率可达到0.64·10-3s-1,分别是9.7%(Mo-Co)/γ-Al2O3和16.9%(Mo-Co)/AC催化剂上的1.68和2.28倍. 对比研究结果表明,用CNT代替γ-Al2O3或AC并不引起催化剂上噻吩HDS反应的表观活化能发生明显变化. 与Mo-Co/γ-Al2O3或Mo-Co/AC催化剂相比,一方面,Mo-Co/CNT催化剂更易在较低温度下还原活化,并导致工作态催化剂表层活性Mo物种(Mo4+)在总Mo量中所占比例明显提高; 另一方面,Mo-Co/CNT催化剂对H2具有更强的吸附和活化能力. 这两个因素对提高催化剂活性都有重要贡献.     

幂群与它的生成群

设г是G上的幂群,即以G的非空子集为元素,在G的子集的运算之下所成的群.P_1,P_2是这样的两个性质 P_1:对任意g∈G,存g∈G,存在A∈г,使得g∈A. P_2:对任意A,B∈г,如果A≠B,则A∩B=φ. 本文得出了群G上的幂群г分别具有性质P_1或P_2的充要条件.     

Fabrication of Graphene-cuprous Oxide Hybrid Paste Electrodes for Capillary Electrophoretic Measurement of Polyhydroxy Compounds

An alkaline mixture containing copper(II) spices, graphene oxide and glucose was heated by far infrared radiations to synthesize graphene-cuprous oxide hybrid. The hybrid was blended with mineral oil and packed into tubes to fabricate paste electrodes. The electrodes were coupled with capillary electrophoresis for the detection of polyhydroxy compounds. The sensitivities of them on the hybrid electrodes were significantly enhanced by taking advantages of graphene and cuprous oxide. The contents of polyhydroxy compounds in tobacco method was determined by the electrodes with satisfactory assay results.     

ZnO-Fe3O4 composite prepared by sol-gel method with H2 deoxidation

Fe doped ZnO powder samples (Fe/Zn=0.05 and 0.1) were prepared by sol-gel method with H₂ deoxidation at 450 ^°C for several hours or just heated in air at the same temperature. It was showed by vibrating sample magnetometer (VSM) that samples heat treated in H₂ could show strong ferromagnetism at room temperature while samples treated in air only show very weak magnetism. XRD using Co kα X-ray revealed that the samples heated in H₂ were not pure phase but like a granular system and the magnetism mainly results from Fe₃O₄ in samples while samples heated in air showed pure ZnO phase. Our work indicated that H₂ deoxidation treatment may be an effective technique to fabricate such magnetic semiconductor-like materials with Curie temperature higher than room temperature.     

A Novel Biomolecular Immobilization Matrix Based on Nanoporous ZnO／Chitosan Composite Film for Amperometric Hydrogen Peroxide Biosensor

The performance of an enzyme electrode often depends on the method of enzyme immobilization when fabricating biosensors1. Therefore, the technique used to immobilize the enzyme is one of the key factors in developing a reliable biosensor. Organic-inorganic composite (or hybrid) materials have emerged in recent years. It combines the physicochemical attributes of components and improves their features. Organic components benefit the formation of defect-free inorganic membranes and make it less …