硫脲类化合物研究概述

硫脲类化合物因其独特的分子结构、良好理化性能以及广泛的生物活性,在各行各业具有广泛的应用。本文主要介绍了硫脲类化合物的概念、分类、合成方法以及应用领域,以便于研究工作者快速了解其发展进程。     

Well-defined polymer precursors synthesized by RAFT polymerization of N,N-dimethylacrylamide/N-acryloxysuccinimide: random and block copolymers

N,N-dimethylacrylamide (DMA) and N-acryloxysuccinimide (NAS) were copolymerized by the reversible addition–fragmentation chain transfer (RAFT) polymerization technique, to obtain random and block copolymer precursors onto which different side-groups may be statistically grafted via the reactive NAS units. These reactive copolymers have interesting applications in various fields such as coatings and paints, water purification and biology. Random poly(DMA-co-NAS) copolymer chains were synthesized with a 75/25 molar ratio, high conversion, an excellent molecular weight (MW) control from 5000 to 130 000 g mol⁻¹, and low polydispersity index (M_w/M_n<1.1). Poly(DMA-b-NAS) block copolymers were synthesized by a two step method, in which a poly(DMA) homopolymer was prepared first and then used as macro-chain transfer agent to polymerize NAS. For example, a poly(DMA-b-NAS) sample was obtained with an average molecular weight of 44 300/7400 g mol⁻¹ corresponding to 447 DMA and 44 NAS units. Such block copolymers had not yet been synthesized by any controlled polymerization technique. They can be used to prepare polymers with exactly the same backbone and an increasing number of different side groups (e.g. hydrophobic, ionic or fluorescent).     

紫外二阶导数光谱法测DTY油剂中烷基酚聚氧乙烯醚含量

介绍了紫外二阶导数光谱法直接测定ＤＴＹ油剂中烷基酚聚氧乙烯醚（ＯＰ）含量的方法，并消除了其它共存物质的干扰。实验表明：该方法线性范围２５～７００ｍｇ／Ｌ，标准偏差０．０９４％，标准加入回收率９９．９％～１０１．７％。     

Estimation of the critical properties of compounds using volume-based thermodynamics

The importance, yet scarcity of the critical constants of thermally unstable fluids warrants the development of reliable methods for the estimation of these essential thermodynamic properties. A thorough investigation undertaken in this study on 1,589 compounds belonging to 83 chemical classes, indicated that the ratio of critical temperature to critical pressure of both low and high molecular weight compounds could be well expressed in terms of their volumetric properties. In addition, two new methodologies are presented for estimating V_c, as well as an indirect approach for prediction of T_c from surface tension data, altogether allowing the calculation of Z_c. Moreover, comparative studies are made with five group contribution methods. It is also demonstrated that by employing the Peng-Robinson EOS, and without prior knowledge of the critical properties, it is possible to calculate various thermophysical properties including P^sat., T_b, , ∆H^vap. , C_p, and even the T_c and P_c themselves.     

改进型LOG算子在偏振片绝对角度中的应用

光学成像系统自身通常都具有一定的偏振效应,严重影响仪器偏振测量精度,而提高仪器中偏振片绝对角度精度能提高偏振定标精度,对校正光学系统自身的偏振特性具有重要的意义。对偏振片直线透光轴Raw图像高精度边缘定位和直线检测是偏振片绝对角度计算的关键步骤。针对传统LOG算子各向同性及虚假边缘与边缘定位精度相矛盾的缺陷,提出改进型一阶导阈值旋转式椭圆对称LOG算子。该算子不仅保留了经典LOG算子的优点,还具有对不同角度的边缘更加有效地进行检测,在保持边缘定位精度下,减少虚假边缘的特点。在处理得到的边缘二值图像上,进行直线检测求出偏振片绝对角度,通过对比分析最小二乘法线性拟合和霍夫变换的直线检测效果,得出霍夫变换能精确计算出偏振片绝对角度。实验证明改进型LOG算子与霍夫变换相结合提高了偏振片绝对角度测量精度,对偏振定标精度具有很大的提高。     

Theoretical investigation on cyclic reciprocal derivative chronopotentiometry: Kinetic study of totally irreversible electrode processes

Theoretical expressions and mathematical analysis in cyclic reciprocal derivative chronopotentiometry (CRDCP) are presented for totally irreversible electrode processes corresponding to the application of symmetrical and unsymmetrical programmed currents. For two successive unsymmetrical programmed currents, the effect of the currents ratio b (b = |I₂(t)/I₁(t)|) on the (dt/dE)–E curves is discussed. The electrochemical behavior of totally irreversible electrode processes has been studied corresponding to the application of the unique unsymmetrical programmed Φ^m(I₀) proposed recently. CRDCP characteristic parameters obtained for totally irreversible electrode processes are different from those of reversible electrode processes. Therefore, a comparison of CRDCP between both mechanisms is presented. Based on the mathematical derivation, alternative methods for kinetic measuring are described. It is prospected that CRDCP is convenient and applicable for studying the reversibility of the electrode processes in form of CRDCP characteristic parameters.     

增产胺合成路线及生物活性述评

主要介绍增产胺（DCPTA）及其几个重要的类似物的合成方法、生物活性，充分表明了增产胺及其类似物是一类可用于多种农作物的高效植物生长调节剂。     

基于分数阶非线性各向异性扩散的图像去雾算法

针对大多数各向异性扩散方程在去雾过程中容易模糊边缘细节的问题,提出一种基于分数阶非线性各向异性扩散的去雾算法。使用从模糊图像中提取的大气光作为各向异性扩散过程中的初始值,通过迭代扩散过程计算精细的大气光传输图。使用分数阶导数的Riemann-Liouville模型,将各向异性扩散过程推广到1~2之间的任何实数阶数,而且在空间域中执行迭代过程使得算法在计算方面能够简单快速的实现。实验结果表明,该算法能够有效地突出去雾图像的细节,而且在多个评价指标上比其他算法都有更优的性能体现。     

基于等效转子电压的双馈感应发电机灭磁控制

针对电网电压故障引起的双馈感应发电机磁链弱阻尼振荡问题,提出一种采用等效转子电压的双馈感应电机灭磁控制策略。分析电网电压故障激起的双馈感应电机定子磁链的暂态过渡过程,建立定子磁链状态方程;通过求解状态方程的特征根和定子磁链的振荡频率及阻尼比,在转子电压前馈补偿项的基础上引入定子磁链的微分反馈项,得到等效转子电压参考值,并研究了其改善磁链欠阻尼特性和加快暂态磁链衰减的机理。最后,双馈感应发电机的仿真结果表明,本文方法可以较好地抑制故障期间的磁链振荡冲击,有利于双馈风电机组故障穿越能力的提高。     

基于解析解的四阶PDE曲面裁剪方法

该文提出了一种可以广泛应用于四阶PDE曲面的裁剪方法。利用PDE的参数域内的曲线在曲面上投影,得到所求裁剪曲面的边界曲线,然后通过边界曲线的导矢与曲面在边界曲线处的法向量得到边界曲线处的跨界导矢,最后以求得的裁剪曲面的边界曲线以及裁剪曲面在边界曲线处的跨界导矢为PDE曲面的边界条件,用四阶的PDE曲面方程求得PDE裁剪曲面。