液相色谱串联质谱法测定养殖水体中孔雀石绿及其代谢物

研究利用液相色谱-串联质谱(LC-ESI-MS/MS)测定水产品养殖水体中孔雀石绿及其代谢物隐性孔雀石绿的方法.通过一系列实验对样品前处理条件进行了优化研究,养殖水样经乙酸酸化,净化后,采用HPLC-ESI-MS/MS检测分析.在多反应监测模式(MRM)下,外标法定量,定量限均为0.5μg/kg.在0.5～50μg/L...     

主动控制压电旋转悬臂梁的参数振动稳定性分析

在工程实际中旋转机械由于制造和加工误差,装配的不均匀性等原因,往往会脉动运行,这将使得机械系统发生参数振动. 当脉动参数满足一定关系时,这种参数振动将会失稳,进而影响机械结构的正常运转. 本文针对这一问题,引入压电材料对 脉动旋转悬臂梁系统的振动进行控制,研究主动控制悬臂梁系统的参数振动优化设计问题,采用 Hamilton 变分原理与一阶 Galerkin 离散相结合的方法,建立了受速度反馈传感器主动控制的压电旋转悬臂梁的一阶近似线性控制方程. 运用多尺度方法,得到了压电旋转悬臂梁系统在发生1/2亚谐波参数共振时稳定性边界的控制方程,并利用直接分析方法验证了解析摄动解的正确性. 将摄动解中临界阻尼比和轮毂角速度脉动幅值的无量纲参数作为评价系统稳定性能的指标. 通过数值算例,分析了轮毂半径、轮毂角速度平均值和脉动幅值、梁长以及速度传感器的反馈增益系数对系统稳定性区域的影响. 研究结果表明,梁长、轮毂半径、脉动幅值会降低系统稳定性,反馈增益系数可以提高系统稳定性,而轮毂角速度平均值与系统稳定性之间有非单调的关系. 为进一步设计压电旋转机械结构提供了理论依据.      

Three-dimensional elastostatic solutions for transversely isotropic functionally graded material plates containing elastic inclusion

Based on the generalized England-Spencer plate theory, the equilibrium of a transversely isotropic functionally graded plate containing an elastic inclusion is studied. The general solutions of the governing equations are expressed by four analytic functions α(ζ), β(ζ), φ(ζ), and ψ(ζ) when no transverse forces are acting on the surfaces of the plate. Axisymmetric problems of a functionally graded circular plate and an infinite func-tionally graded plate containing a circular hole subject to loads applied on the cylindrical boundaries of the plate are firstly investigated. On this basis, the three-dimensional (3D) elasticity solutions are then obtained for a functionally graded infinite plate containing an elastic circular inclusion. When the material is degenerated into the homogeneous one, the present elasticity solutions are exactly the same as the ones obtained based on the plane stress elasticity, thus validating the present analysis in a certain sense.     

Recent progress in two-photon small molecule fluorescent probes for enzymes

Enzymes are macromolecular biological catalysts which can accelerate chemical reactions in living organisms. Almost all the physiological metabolism activities in the cell need enzymes to sustain life via rapid catalysis. Currently, medical research has proved that abnormal enzyme activity is associated with numerous diseases, such as Parkinson’s disease (PD), Alzheimer's disease (AD) and cancers. On the other hand, early diagnosis of those diseases is of great significance to improve the survival rate and cure rate. In the current diagnostic tools, two-photon fluorescent probes (TPFPs) are developing rapidly due to their unique advantages, such as higher spatial resolution, deeper imaging depth, and lower biotoxicity. Therefore, the design and synthesis of two-photon (TP) small molecule enzymatic probes have broad prospects for early diagnosis and treatment of diseases. As of now, scientists have developed many TP small molecule enzymatic probes. This review aims to summarize the TP small molecule enzymatic probes and expound the reaction mechanism.     

使用AlN/GaN超晶格势垒层生长高Al组分AlGaN/GaN HEMT结构

在蓝宝石衬底上生长了以AlN/GaN超晶格准AlGaN合金作为势垒的HEMT结构材料,并与传统AlGaN合金势垒样品进行了对比.在高Al组分(≥40%)情况下,超晶格势垒样品的表面形貌明显改进,电学性能特别是2DEG面电子浓度也有所改进.对超晶格势垒生长参数进行了初步优化,使得HEMT结构薄层电阻进一步降低,最后获得了251 Ω/□的薄层电阻. 关键词： AlGaN/GaN 结构 AlN/GaN超晶格 二维电子气 高电子迁移率晶体管     

Sodium nitrite catalyzed aerobic oxidative deoximation under mild conditions

A mild, simple process for the effective deoximation of a wide range of ketoximes and aldoximes has been developed, which utilizes available NaNO(2) as the catalyst and molecular oxygen as the green oxidant. Notably Amberlyst-15, which acts as the initiator of NaNO(2), can be reused without regeneration. This environmentally benign protocol could provide a valuable synthetic method for practical applications.     

混合模式硅胶基质毛细管电色谱整体柱的制备及其电色谱性能研究

采用温和条件下的溶胶-凝胶技术,成功制备了阴离子交换-反相混合模式硅胶基质毛细管电色谱整体柱.通过调整反应液中不同前体的比例,优化了整体柱的制备条件.通过扫瞄电镜,对柱床进行了表征和分析.实验发现,所制备的整体柱电渗流的方向和大小可随流动相pH值的改变而改变,在酸性和中性条件下,具有从阴极流向阳极的电渗流;当流动相pH值升至约7.5时,电渗流方向发生了反转(由阳极流向阴极).在优化的实验条件下,用所制备的整体柱对所考察的酸性(中性)化合物实现了快速分离,并获得了高达160,000 N/m的柱效.     

负载型镍金属催化剂上甲烷与二氧化碳重整制合成气

报道了负载型Ｎｉ金属催化剂的表面特征和对ＣＨ４与ＣＯ２重整制合成气的催化性能，反应结果和ＴＰＲ，ＸＲＣ结果表明：Ｎｉ担载量为９．０％的催化剂具有最佳的反应性能，Ｎｉ组分以高散表面化合物形式存在，助剂对催化剂活性的影响随载体和添加方式的不同较大差异，其中少量ＭｇＯ，Ｌａ２Ｏ３对改善催化剂的稳定性和抗积碳能力有十分显著的效果，载体和制备方法对催化剂性能具有明显影响，其中浸渍法制备的Ｎｉ／ＭｇＯ催化剂不     

具有谷胱甘肽过氧化物酶活性的催化抗体的研究Ⅰ．谷胱甘肽特征全抗原的合成、表征及性质

用２，４－二硝基氯苯保护谷胱甘肽的巯基制出半抗原，再通过戊二醛共价反应使其与牛血清白蛋白表面的氨基结合，经超胶ＡｃＡ５４凝胶层析纯化，制备出有较强免疫原性的谷胱甘肽全抗原。用元素分析、红外光谱及核磁共振表征了半抗原的结构。电泳分析得全抗原分子量平均为８７０００道尔顿。光谱分析及圆二色谱研究表明其有较强的可见、紫外及荧光特征吸收，且抗原结构的紧密性增强。     

两亲嵌段共聚物胶束用作医用材料

两亲嵌段共聚物可以在水溶液中自组装形成亲水性链段为外壳、疏水性链段为内核的胶束,这种胶束能够用作药物载体而引起人们极大的关注。本文综述了两亲嵌段共聚物胶束用作医用材料的研究进展,主要内容包括医用两亲嵌段共聚物的种类,胶束化,以及用作诊断试剂载体、药物缓释载体、靶向载体等。两亲嵌段共聚物胶束用作磁共振造影剂载体有利于肿瘤的诊断,用作药物缓释载体可以有效增溶难溶性抗肿瘤药物,延长药物在体内的血液循环时间。此外,通过对胶束表面进行修饰或者施加外场,还可以实现靶向功能。因此,两亲嵌段共聚物胶束在医用材料领域有着广阔的发展前景。