Effect of oxygen partial pressure on the structure and properties of Cu–Al–O thin films

We have studied the electrical and optical properties of Cu–Al–O films deposited on silicon and quartz substrates by using radio frequency (RF) magnetron sputtering method under varied oxygen partial pressure P_O. The results indicate that P_O plays a critical role in the final phase constitution and microstructure of the films, and thus affects the electrical resistivity and optical transmittance significantly. The electrical resistivity increases with the increase of P_O from 2.4 × 10^?4 mbar to 7.5 × 10^?4 mbar and afterwards it decreases with further increasing P_O up to 1.7 × 10^?3 mbar. The optical transmittance in visible region increases with the increase of P_O and obtains the maximum of 65% when P_O is 1.7 × 10^?3 mbar. The corresponding direct band gap is 3.45 eV.     

Direct electron transfer of glucose oxidase promoted by carbon nanotubes is without value in certain mediator-free applications

We have investigated the direct electron transfer (DET) promoted by carbon nanotubes (CNTs) on an electrode containing immobilized glucose oxidase (GOx) with the aim to develop a third-generation glucose biosensor and a mediator-free glucose biofuel cell anode. GOx was immobilized via chitosan (CS) on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs). Cyclic voltammetric revealed that the GOx on the surface of such an electrode is unable to simultaneously demonstrate DET with the electrode and to retain its catalytic activity towards glucose, although the MWCNTs alone can promote electron transfer between GOx and electrode. This is interpreted in terms of two types of GOx on the surface, the distribution and properties of which are quite different. The first type exhibits DET capability that results from the collaboration of MWCNTs and metal impurities, but is unable to catalyze the oxidation of glucose. The second type maintains its glucose-specific catalytic capability in the presence of a mediator, which can be enhanced by MWCNTs, but cannot undergo DET with the electrode. As a result, the MWCNTs are capable of promoting the electron transfer, but this is without value in some mediator-free applications such as in third-generation glucose biosensors and in mediator-free anodes for glucose biofuel cells.

杆中嵌入薄板的应力波传播行为

采用一维理论分析和二维有限元模拟,研究了杆中嵌入薄板的应力波传播行为.首先根据一维弹性应力波理论,推导了反射波,透射波以及板中应力的表达式.结合算例,分析了薄板厚度对应力波传播的影响,然后采用有限元方法,验证了一维理论分析结果,同时也研究了不同界面处理方式对结果的影响.结果表明板越薄,对应力波传播的影响越小,薄板中应力越能真实地反映杆中的应力状态;在SHPB实验中,嵌入薄片/薄膜传感器测量微弱应力信号是可行的.     

高陡岩质边坡稳定性三维离散元分析

某高陡岩质边坡地质条件复杂、软弱结构面发育、开挖高度大、坡度陡、临空面多,为边坡变形提供了有利的空间,边坡多处出现失稳破坏迹象。通过对边坡工程地质条件调查,岩体结构特征和边坡开挖等影响因素的分析,认为边坡变形主要发生在强风化强卸荷岩体内,受软弱结构面的控制比较明显,表现为结构面组合控制的块体变形失稳破坏模式。采用3DEC数值模拟软件,模拟了边坡开挖后坡体变形特征,数值模拟结果表明,边坡浅表层块体以及控制性块体稳定性差,可能导致边坡产生整体失稳。     

川藏公路茶树山滑坡特征及成因机制分析

通过对川藏公路茶树山滑坡地质环境条件的系统调查研究,分析了滑坡岩土体结构、边界条件、变形特征、影响因素,并结合3DEC数值模拟,对其变形破坏机制进行了深入的探讨。综合分析表明,滑坡位于活动断裂带内,后缘斜坡陡峭,岩体破碎,同时前缘为较厚的松散堆积体斜坡,在地震活动、降雨等影响因素的诱发作用下,滑坡成因机制主要表现为以下3个阶段:(1)倾倒拉裂阶段,滑坡受后缘地形及岩体结构控制作用较为明显,在坡体浅表层一定深度范围内出现较为强烈的倾倒拉裂变形带,产生倾倒-拉裂滑动; (2)蠕滑变形阶段,前缘松散堆积体在强大的自重推力作用下发生蠕滑变形; (3)前部"锁骨段"剪断,整体失稳阶段,滑坡前部锁骨段在自重推力及断层活动的持续影响下,发生剪断,控制后缘倾倒拉裂体稳定性的潜在滑面与前缘松散堆积体体内的剪切滑动面贯通,滑坡整体失稳。     

A NOVEL METAL CHELATE AFFINITY ADSORBENT FOR PROTEIN UPTAKE

1. INTRODUCTION Chitosan is a hydrolyzed derivative of chitin and belongs to a family of linear unbranched polysaccharides which contain large amounts of 1,4-linked-2-amino-2-deoxy-β-D-glucan residues. The presence of free amine groups in chitosan enhances the solubility and reactivity of this polymer. Interest in modifying chitosan by using glutaraldehyde has recently increased. The derivatized polymers have been employed for many applications [1~2], including protein immobilization…     

A NOVEL METAL CHELATE AFFINITY ADSORBENT FOR PROTEIN UPTAKE

In this article,a spherical chitosan gel crosslinked by epichlorohydrin was prepared.It was then loaded with copper ions to produce a metal chelate affinity adsorbent for protein.The uptake of bovine serum albumin(BSA)by the affinity adsorbent was investigated.and the adsorption capacity for BSA as high as 40mg/g-wet beads was observed.The adsorption equilibrium data was well correlated by the Langmuir equation.The adsorption was considerably affected by pH.In additio.The amount of BSA adsorbed onto the beads decreased with the increasing of aqueous phase ionic strength,so adsorbed BAS can be desorbed by adjusting pH orionic strength of the solution.     

环糊精聚合物的高分子效应

环糊精以其独特的包络性能而引人注目, 现已广泛应用于色谱分离、选择性合成的催化剂、食品、医药及农药等多种领域。环糊精聚合物被证实亦具有包络、缓释及催化的能力, 以及较好的机械强度和化学稳定性。目前环糊精聚合物主要应用在色谱分离、空气净化和食品工业等方面。本文综述了环糊精高分子化后所表现出的高分子效应, 为环糊精聚合物的合成和应用提供参考。     

液态低沸点气体的表面张力

利用双毛细管法测定了液氮沸点温度下液氮的表面张力。用非线性方程γ=γ0(1-T/TC)n描述了液态N2、O2、Ar、Xe、H2、Ne、He、F2和Kr的表面张力与温度的关系,并采用一元线性回归的方法拟合了上述各流体的参数γ0和n,准确度高于文献值,说明方程能正确表达表面张力与温度的关系。这些数据有利于对上述低沸点气体进行准确的热力学计算。