石榴状凝胶微球固定化漆酶的制备、 表征及降解双酚A

采用铜/锌复合金属磷酸盐晶体和海藻酸钙凝胶双重包覆技术对漆酶进行固定化, 制得石榴状Alg@Cu₃/Zn₃(PO₄)₂@Lac的凝胶微球. SEM, EDX和FTIR表征结果表明, 在凝胶微球内部, 漆酶被成功固定于由海藻酸钙凝胶包覆的铜/锌复合金属磷酸盐晶体内, 铜/锌复合金属磷酸盐晶体镶嵌于海藻酸钙凝胶网格的孔隙中而呈石榴状. 以2,2′-联氮双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)为底物, 经酶学性质研究表明, 在无机盐晶体和海藻酸钙凝胶的双重保护下, Alg@Cu₃/Zn₃(PO₄)₂@Lac的耐热性、 耐酸性以及储存稳定性比游离漆酶均有不同程度增强. 将Alg@Cu₃/Zn₃(PO₄)₂@Lac应用于双酚A(BPA)的降解, 采用孔径约1 mm滤网实现快速回收, 经6次循环利用, 对BPA的降解率下降约14%, 显示出比较稳定的重复利用性和便捷的可操作性, 这主要得益于海藻酸钙和铜/锌无机盐晶体对漆酶蛋白分子的双重保护.     

In Silico Design and SAR Study of Dibenzyl Trisulfide Analogues for Improved CYP1A1 Inhibition

Dibenzyl trisulfide (DTS) is a natural compound with potential cancer-preventive properties occurring in Petiveria alliacea L., an ethnomedicinal plant native to the Americas. Previous studies revealed its inhibitory activity toward cytochrome P450 (CYP)1 enzymes, key in the activation of environmental pollutants. Accordingly, the aim of this study was to design novel DTS analogues, aimed at improving not only inhibitory activity, but also specificity toward CYP1A1. This was achieved by targeting interactions with CYP1A1 residues of identified importance. Three-dimensional structures for the novel analogues were subjected to molecular docking with several CYP isoforms, before being ranked in terms of binding affinity to CYP1A1. With three hydrogen bond donors, two hydrogen bond acceptors, a molecular mass of 361 Da, and a log P of 3.72, the most promising DTS analogue obeys Lipinski's rule of five. Following synthesis and in vitro validation of its CYP1A1-inhibitory properties, this compound may be useful in future cancer-preventive approaches.     

Oscillation criteria for higher order nonlinear dynamic equations

In this paper, we will consider the higher‐order functional dynamic equations of the form on an above‐unbounded time scale , where and , . The function is a rd‐continuous function such that . The results extend and improve some known results in the literature on higher order nonlinear dynamic equations.     

Notes on D-optimal designs

The purpose of this paper is to exhibit new infinite families of D-optimal (0, 1)-matrices. We show that Hadamard designs lead to D-optimal matrices of size (j, mj) and (j − 1, mj), for certain integers j ≡ 3 (mod 4) and all positive integers m. For j a power of a prime and j ≡ 1 (mod 4), supplementary difference sets lead to D-optimal matrices of size (j, 2mj) and (j − 1, 2mj), for all positive integers m. We also show that for a given j and d sufficiently large, about half of the entries in each column of a D-optimal matrix are ones. This leads to a new relationship between D-optimality for (0, 1)-matrices and for (±1)-matrices. Known results about D-optimal (±1)-matrices are then used to obtain new D-optimal (0, 1)-matrices.     

Iterative receiver for OFDM systems based on semi-blind channel estimation

In this paper we propose two iterative algorithms of joint channel estimation and symbol detection for Orthogonal Frequency Division Multiplexing （OFDM） systems. In which, superimposed pilot scheme is adopted and an initial Channel State Information （CSI） is obtained by employing a first-order statistic. In each subsequent iteration, we propose two algorithms to update the CSI. The Mean Square Error （MSE） of channel estimation and Bit Error Rate （BER） performance are given and simulation results demonstrate that the iterative algorithm using method B has good performance approaching the ideal condition.     

一种可调精度的A/D转换器设计

现代测控系统对测量信号的处理基本由数字技术完成,A/D转换器的性能对系统具有重要的影响.采用SDM(∑-⊿调制器)实现A/D转换器,省略复杂的数字抽取滤波器,由DSP和CPLD对SDM输出的高速码流处理,实现A/D转换.DSP软件编程可以控制CPLD的计数器,实现可变精度(和速度)的A/D转换.通过对SDM特性分析,得到转换方法及计算公式,最后设计电路实现要求的功能.实验实现了最高16位A/D转换,很好地证明了设计分析的结论.     

基于FPGA的高精度TDI-CCD信号发生器的设计

由于航天相机所使用的TDI-CCD(Time Delay and Integration Charge Coupled Devices)芯片价格昂贵而且极易损坏,提出了一种利用FPGA(Field Pmgrammable Gate Array)和多通道D/A转换器构成的宽频、高精度TDI-CCD信号发生器的原理方案和实现方法。通过对FPGA器件APA075和D/A转换器件DAC2900的配置,得到频率为11MHz的相关双采样形式的模拟TDI-CCD信号,同时通过改进PCB设计和滤波电路,提高了输出信号的精度,降低了噪声。本设计具有可编程、宽频、高精度和低硬件复杂度等特点,目前已成功应用到新一代高分辨率航天相机数据采集系统的研制中。     

ANiN(A=Li,Na,Mg,Ca)的结构、热力学、弹性和电子性质的第一性原理研究

三元过渡金属氮化物ANiN(A=Li,Na,Mg,Ca)是潜在的可充放电池的电极材料.物理性质,比如热稳定性、电子能隙以及弹性稳定性等,对于这些材料的电池应用都是非常重要的.本文使用第一原理方法,对比研究了 ANiN这些材料的结构、动力学、弹性和电子结构性质.对状态方程和声子谱的计算被用来确定体系的稳定结构.对最稳定结...     

天青A-溴酸钾体系催化光度法测定微量甲醛

研究了在H2SO4介质中,微量甲醛对KBrO3氧化天青A有较强的催化作用,建立了催化光度法测定微量甲醛的新方法.方法的线性范围为0.035～0.66 mg/L,检出限为0.016 mg/L.该方法用于米粉、粉丝等食品中甲醛的测定,测定结果的相对标准偏差(RSD)小于5%,加标回收率为98.5%～101.2%.