具有平方衰减项的平方自催化开放系统中的化学波研究

建立了开放系统中伴随平方衰减反应的双分子自催化反应理论模型,给出了系统的动力学分析,在给定初边值下解的估计及存在化学波的必要条件、化学波波速的最小值及平方衰减项对化学波的影响.随着衰减系数的增加,平方衰减项逐步成为系统反应中化学波波形的决定因素.     

Radiation: Waves or particles? A quantized approach to time

A fundamental difficulty in theoretical physics is the dual and apparently incompatible interpretations of radiation as showing both continuous and extensive wave properties but also those of discrete atomic or smaller individual particles. Some of these contradictions are outlined. The explanation offered is of a quantized nature of time; units t_o=h/m_oc² for a particle at rest, and of similar interval unit s_o when in relative motion, with conventional relativistic corrections.

For many purposes this form of quantization replaces the need for a wave concept which then appears as a mathematical approach, chosen to avoid the physical concept of an intrinsicc time for any particle, just as we have for its intrinsic mass, spin and electrical charge. t_o and s_o are directly related to its frequency, energy and mass. The uncertainty principle and interference relations follow directly from this model, without any physical wave concept.     

A NICI-GC-MS Method to Analyze Endosulfan in Biological Samples

Abstract

A mass spectrometric method in the negative ion chemical ionization mode was used to analyze α- and β-endosulfan in biological samples. The selected ion recording technique was employed, monitoring the ions at m/z 35 and 37. Biological samples of animals treated with endosulfan were analyzed. The method is selective and sensitive enough to analyze crude extracts of mouse brain and plasma directly without purification, since the chromatograms were clean     

Fast Marching Method for Calculating Reactive Trajectories for Chemical Reactions

We present a method for computing classical Newtonian trajectories that minimize the path length or transit time from reactant to product. Our approach is based on a generalization of the fast-marching method, which allows us to construct the solution of the Hamilton-Jacobi equation for the action that optimizes the desired quantity. The resulting “reactive paths” can be interpreted as reaction coordinates but, unlike more conventional choices, they contain dynamical information about the chemical system of interest.     

电磁波对化学反应非致热作用的实验研究

微波加快化学反应速度除微波对反应物的加热以外还有非致热的作用，本文用实验证实了电磁波对离子和极性分子的洛仑兹力的作用导致了指前因子和活化能的变化，并提出用电磁作用因子描术电磁波对化学反应作用的大小。     

运用电教媒体进行化学课堂教学改革的尝试

教改的目的是使师生及教学媒体达到最佳组合以取得最佳教学效果。近几年来,我们开展了“目标教学”为主的教改实验,在实施过程中,我们深刻体会到教学过程的最优化是一个关键。因此,在教学过程中我们运用了电教媒体,取得了一定成效。     

A New Chemical Method to Desulfenylate Indol-3-yl Sulfides

Abstract

Desulfenylation of indol-3-yl sulfides liberates the most reactive position of the ring for further transformations. The usual procedure, utilizing Raney Nickel (P. G. Gassman, et. al., J. Am. Chem. SOC. 1974,96, 5495) offers a limited scope due to incompatibility of a number of functional groups towards the reducing agent. Based on our recent mechanistic studies of the acid-catalysed rearrangement of indol-3-yl sulfides to indol-2-yl sulfides (P. Hamel, et. al., Chem. Commun. 1989, 63; J. Org. Chem. 1992, 57, 2694), we have developed a novel, non-reductive desulfenylation method which permits easy access to 3-unsubstituted indoles bearing a wide array of substituents. Thus, 3-indolyl sulfides, readily obtained from appropriate phenylhydrazines (via Fischer indolization) or anilines (Gassman method, vide infra) are smoothly desulfenylated in good yields in trifluoroacetic acid in the presence of an appropriate nucleophilic trapping agent. Thiols proved to be very effective trapping agents and thiosalicylic acid (TSA) is a thiol of choice, being non-volatile and easily separable from reaction products.     

化学平衡解题通用方法探讨*

对于复杂的化学平衡,平衡时刻浓度、分压、物质的量、转化率之间存在错综复杂的关系,给解题带来了很大难度。提出了“列表-设未知数-计算分压-计算平衡常数-求解”的5步解题通用方法,并利用该方法,结合CASIO计算器独特的解题特色,对近几年化学竞赛中出现的2道化学平衡试题进行了剖析。     

A Modified Method for Measuring Cyanide in Biological Specimens

Abstract

The use of cyanide generating substances for medical, home and business applications has necessitated the need for measuring sublethal levels of this substance because of the potential of inadvertent cyanide poisoning. The method we propose provides a means for more accurate recovery at an increased rate of reaction there by making its sensitivity more conducive to the measurement of minute quantities of cyanide.     

Chemical Paradigm vs. Biological Paradigm in the Biological Clock Controversy

Examples of biological rhythmicity mounted in the first half of the twentieth century, but the nature of biological rhythms – whether they were direct responses to rhythmic environmental stimuli or generated internally by biological clocks or oscillators – remained sharply disputed. When Frank A. Brown Jr. observed precise twenty-four-hour rhythms in the colour changes of fiddler crabs that were isolated from changes in environmental lighting that could synchronise them with the daily cycle, he rejected the internal clock as an explanation, owing to his belief that such a biological mechanism must operate chemically and consequently run faster at higher temperatures (Van’t Hoff’s rule), which was not borne out by his experiments. Colin Pittendrigh was committed to the idea that the rhythms were generated by unknown, temperature-compensated mechanisms, without offering any explanation for how this might be accomplished. At the core of their dispute, which was aired publicly from 1954 until Brown’s death in 1983, was a difference in belief: Brown’s fundamental reductionism, which required biological processes to conform to the laws of chemistry, vs. Pittendrigh’s trust in the power of evolution to select for such a temperature compensated biological clock, for which no plausible chemical model then existed.     

一种快速廉价的蛋白质测定方法

蛋白质测定的Ｌｏｗｒｙ法显色反应在３０℃以下通常需３０ｍｉｎ,Ｌａｒｓｏｎ利用加入二硫苏糖醇（ＤＴＴ）使反应快速完成并提高了灵敏度,但存在ＤＴＴ价格昂贵的不足。利用连二亚硫酸钠（保险粉）代替ＤＴＴ,实现了蛋白质含量快速、灵敏、廉价的测定。     

硅表面上构筑具有化学特性的图形的新方法

为了在硅基底上得到不同化学基团修饰的图形,在氢终止硅（111）表面运用光刻技术和光化学反应结合来控制表面成膜反应的位置,并用AFM、XPS、接触角测定等验证了这种方法的可行性.     

Hofmeister效应对生物和化学体系的影响

Hofmeister效应涉及到的问题范围十分广泛,对很多化学、生物体系都有影响。总的说来,Hofmeister效应会影响到溶液的冰点、沸点、黏度、偏摩尔体积、饱和蒸汽压、传导率、pH、表面张力。文章主要介绍了Hofmeister效应的主要影响因素,以及相关理论的建立与完善,并对不同体系中Hofmeister效应的影响进行了描述。     

From Phenotypic Hit to Chemical Probe: Chemical Biology Approaches to Elucidate Small Molecule Action in Complex Biological Systems

Biologically active small molecules have a central role in drug development, and as chemical probes and tool compounds to perturb and elucidate biological processes. Small molecules can be rationally designed for a given target, or a library of molecules can be screened against a target or phenotype of interest. Especially in the case of phenotypic screening approaches, a major challenge is to translate the compound-induced phenotype into a well-defined cellular target and mode of action of the hit compound. There is no “one size fits all” approach, and recent years have seen an increase in available target deconvolution strategies, rooted in organic chemistry, proteomics, and genetics. This review provides an overview of advances in target identification and mechanism of action studies, describes the strengths and weaknesses of the different approaches, and illustrates the need for chemical biologists to integrate and expand the existing tools to increase the probability of evolving screen hits to robust chemical probes.     

数码比色法测定环境及生物样品中的氰化物浓度

在传统氰化物检测方法的基础上,提出了一种新的方法—数码比色法。在一定条件下,苦味酸与氰化物生成黄色化合物,用数码相机对显色溶液拍照,通过数码比色,进行灰度处理,照片的三原色值与氰化物的浓度成线性关系,可以直接分析出其氰化物的浓度。对唾液样品测定,其回收率为98.18%,对照品测定的相对标准偏差RSD为1.5%。研究结果表明,数码比色法具有准确度和精密度都比较理想,方便快速、环境友好等特点。     

简便快速计算线性作图法测定稀的极弱碱

提出了HCl滴定碱的线性方程简化式,应用于测定稀的极弱碱、多元碱、强弱碱混合液及抗酸药碳酸氢钠片的含量,不需要极弱碱的稳定常数KS,即可简便快速计算V-pH数据,作直线确定反应终点,其结果的相对标准偏差和绝对误差分别为0.16%～0.66%和0.090%～0.91%,符合一般化学分析要求     

A Chemical Test for Determining Biological Availability of Aged Chemicals in Soil

Abstract

Aging is one of several processes that are known to affect exposure of chemicals to organisms by decreasing the available fraction of chemical contaminants in soil. This phenomenon has important implications in the assessment of the hazards of chemicals and regulations for soil cleanup. Passive sampling devices (PSDs) are potentially direct chemical indicators for assessing bioavailability of pesticides (and other chemicals). PSDs consist of lipophilic material within a semi-permeable membrane, similar to biological systems. In this study, a pesticide mixture was aged in soil for up to eight months. Earthworms and PSDs were placed in soil and chemical uptake into both was determined over time. Uptake rates into PSDs and maximum concentrations were observed to positively correlate with uptake rates and maximum concentrations in earthworms for both of the soil types studied (sandy loam, silt loam). These results indicate that PSDs may be used as a surrogate for earthworms and provide a chemical technique for assessing the availability of aged chemical residues in soil.