盐湖盐类水溶液298.15K时稀释热和表观摩尔焓的研究

有关溶稀释热方面的研究报导很多,例如等溶液的稀释热均已有文献值．但全是采用分批式量热法研究部分间断浓度范围内的稀释热，数据设有连续性，很不全面．在稀释热理论估算方面，Pitier的半经验溶液理论能比较满意的解决一般浓溶液的稀释热估算问题，但文献只给出了某些多数，没有计算出具体的稀释热数据[6-9]，也没有将实验测定值与理论估算值相比较．基于Debye－Hckel理论推导出的烙极限公式[10-12]在溶液表观摩尔烂的研究中已得到广泛应用．但迄今没有一篇论文比较全面地将实验测定与Pitier理论和Debye－Hhdel极限公式相结合来研究溶…     

电位溶出分析法理论公式的改进处理方法

电位溶出分析法理论研究,国内已有文献报道,文献的理论结论与实验结果吻合,但理论公式的处理尚不十分完善。本文在前人工作基础上,提出电位溶出分析法理论公式的改进处理方法,以期进一步论证该理论的严谨性。设溶出过程中金属M在汞膜中服从Fick’s第二扩散定律,并提出如下初始、边界条件:     

聚苯胺膜电极上计时电流法和计时库仑法理论及其验证

本文推导了聚苯胺膜电极上计时电流法和计时库仑法理论公式，并成功地进行了验证，理论和实验结果相符合，还测定了扩散系数，结果与文献报道相一致。     

Ba(~3D)+N_2O化学发光反应的动态学研究

本文研究了单次碰撞条件下Ba(~3D)+N_2O→BaO~*+N_2反应的动态学特性。由束气实验测出这个反应的化学发光截面是42.2±1.4(?)~2,总碰撞截面是142±11(?)~2。由化学发光光谱分析出反应产物中存在着BaOD~1∑~+→A~1∑~+→X~1∑~+二次电子跃迁过程。通过交叉分子束实验,研究化学发光截面与反应物振动能、碰撞能的关系。结果表明,这个反应的势能面不存在阈能垒,振动能对化学发光截面影响不大,而平动能的增加会使化学发光截面减小。本文采用信息论方法,计算产物态的分支比,并和实验结果进行对比分析。     

纳米粒子参与的鲁米诺化学发光及其分析应用

化学发光的基础理论和分析应用已经有多年的研究历史,但化学发光的研究多局限于分子和离子水平。纳米粒子由于其量子尺寸效应、表面能高以及比表面积大,因而常作为氧化还原反应的催化剂来放大反应信号。近年来,纳米粒子直接或者间接参与的化学发光拓展了化学发光的理论和应用研究范畴,己发现纳米粒子能够作为催化剂、还原剂、微尺度反应平台和能量接受体等参与化学发光反应。本文详细介绍了纳米粒子参与的鲁米诺化学发光体系,并重点评述了部分纳米粒子参与的鲁米诺化学发光与高效液相色谱、毛细管电泳等分离技术联用实例。纳米粒子作为一种新型化学发光响应单元,可提高鲁米诺化学发光反应的效率,对开发新的鲁米诺化学发光反应体系具有重要意义,已有关于金、铂、银、合金、半导体、磁性等纳米粒子参与的鲁米诺化学发光报道。除应用于环境、药品及食品等分析领域外,其在免疫分析方面也表现出巨大的应用潜力。最后,提出了纳米粒子参与鲁米诺化学发光体系研究目前存在的问题,并对其未来的发展方向进行了展望。     

液-固吸附体系中计量置换吸附模型的热力学研究

研究了液-固吸附体系中溶质计量置换吸附过程中的自由能变,推导出了新的表示溶质种类、溶质浓度和溶剂对Gibbs自由能变贡献的数学表达式,并阐明了该表达式中各种参数的物理意义.将用通常方法测定的自由能变分为与溶质吸附和溶剂解吸附有关的两个独立的自由能变,推导出了液-固吸附体系中溶质计量置换吸附模型的两个线性参数β_a和q/Z对绝对温度倒数的线性关系,又将吸附过程中溶质的焓变和熵变分成两个独立的分量.用文献中的实验数据,对本文推导出的公式进行了检验,理论结果与实验结果一致.     

色谱峰EMG模型参数的计算方法

〕根据实验数据比较了计算EMG参数的五种方法。当采样周期较小时,五种方法的计算值吻合;当采样周期较大时,经典的Yau方法误差较大。本研究提出的图解法改进公式,与文献方法比较,测试简单,有较好的拟合精度,而且更能反映EMG参数间的关系。     

基于化学史和实验数据的化学键概念教学

沿循化学键发展史、创设实验和文献情境、分析实验数据,引导学生自主建构化学键的概念及其表征方式。研究结果表明:基于化学史和实验数据的教学不仅能帮助学生充分理解概念的含义,在学生构建概念并解释真实问题的过程中,还能发展学生宏微结合、证据推理、科学探究与社会责任的化学学科核心素养,认识化学研究的创新方法和研究结论的相对合理性。     

聚苯胺修饰电极膜厚度的理论公式及其验证

本文提出了用于计算聚苯胺修饰电极膜厚度的理论公式,它实用于恒电流法和循环扫描伏安法制得的膜,经验证理论和实验相符合.文中还讨论了PANI密度及摩尔体积的计算和化学测定方法.     

聚苯胺修饰电极膜厚度的理论公式及其验证

本文提出了用于计算聚苯胺修饰电极膜厚度的理论公式,它适用于恒电流法和循环扫描伏安法制得的膜,经验证理论和实验相符合.文中还讨论了PANI密度及摩尔体积的计算和电化学测定方法.     

Analytical applications of photoinduced chemiluminescence in flow systems--a review

In this review, the recent evolution and the state of the art of photochemical reactions coupled with chemiluminescence processes are presented. Different chemiluminescence systems have been considered together with suitable photochemical derivatization processes that can affect either the analyte of interest or even the chemiluminogenic reagent, producing some derivatives able to participate more efficiently in the CL reactions and enhancing the CL emission. The on-line integration of the photochemical reactions as well as the coupling of this resulting photoinduced chemiluminescence (PICL) method with dynamic analytical systems, such as flow injection analysis, liquid or gas chromatography and capillary electrophoresis, have been discussed. Important applications of PICL have been proposed in environmental, pharmaceutical and food analysis.     

Analytical and numerical computation of error propagation of model parameters

Linear and nonlinear regression analyses based on the least-squares method play a fundamental role in the evaluation of scientific data. A large number of valuable papers have dealt with various applications of the least-squares method in the chemical literature. They, however, usually contain tremendous formulas for computing the error estimates of the estimated parameters. This paper presents a simple numerical solution based on the well-known simplex method to this problem. Elaborate enzyme kinetic data published earlier have been chosen to test the simplex method extended with error estimation. The capability of the numerical method is demonstrated by the revision of the originally calculated error propagation. Our program might prove useful in handling either chemical or biological data.     

Relationship between Electric Spark Sensitivity of Cyclic Nitramines and Their Molecular Electronic Properties

On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken charges of nitro group, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen; the other contains the lowest unoccupied molecular orbital energy, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen. Using these two types of formulas, we calculate the electric spark sensitivity of these 14 cyclic nitramine molecules, and compare them with the experimental data and previous theoretical values. And our investigations show that the former type of formula is better than the latter on predicting the electric spark sensitivity for cyclic nitramine molecules.     

Predicting key example compounds in competitors' patent applications using structural information alone

In drug discovery programs, predicting key example compounds in competitors' patent applications is important work for scientists working in the same or in related research areas. In general, medicinal chemists are responsible for this work, and they attempt to guess the identity of key compounds based on information provided in patent applications, such as biological data, scale of reaction, and/or optimization of the salt form for a particular compound. However, this is sometimes made difficult by the lack of such information. This paper describes a method for predicting key compounds in competitors' patent applications by using only structural information of example compounds. Based on the assumption that medicinal chemists usually carry out extensive structure--activity relationship (SAR) studies around key compounds, the method identifies compounds located at the centers of densely populated regions in the patent examples' chemical space, as represented by Extended Connectivity Fingerprints (ECFPs). For the validation of the method, a total of 30 patents containing structures of launched drugs were selected to test whether or not the method is able to predict key compounds (the launched drugs). In 17 out of the 30 patents (57%), the method was able to successfully predict the key compounds. The result indicates that our method could provide an alternative approach to predicting key compounds in cases where the conventional medicinal chemist's approach does not work well. This method could also be used as a complement to the traditional medicinal chemist's approach.     

Use of Concentration Pulse Chromatography for Determining Binary Isotherms: Comparison with Statically Determined Binary Isotherms

The characterization of adsorption properties of binary gas mixtures is an important factor in the design of cyclic periodic adsorption processes. Presently, there are a few methods for determining the binary adsorption behaviour. However, most of these methods are very time demanding (static approaches). One dynamic approach for determining the binary adsorption behaviour is by employing the concentration pulse method. Although this experimental method has been shown to reliably reproduce the data obtained with static approaches, the application has been limited to systems where the adsorption capacities are similar. In our previous work, a novel method (HT-CPM) was shown to be capable of handling systems where the adsorption capacity of the heavy component is much greater than the light component.In order to further validate the novel method, HT-CPM, previously published statically determined binary adsorption data have been used to supply the data required for the concentration pulse method (CPM) data reduction techniques. From this data, the HT-CPM was then applied and the resulting data compared. The two other CPM approaches were also applied and these results are shown.Four binary systems were chosen so that a range of heavy/light adsorption capacities was examined. The results show that the HT-CPM was able to produce results that were consistent with the static data taken from the literature. The other data reduction techniques used with the CPM could only produce meaningful data when the adsorption capacities of the heavy and light components were similar.     

Theoretical prediction of the native fluorescence of pharmaceuticals

At present, to search fluorescent compounds or to increase the native fluorescence is an active research line specially and not only with analytical purposes. On some analytical areas and from the early times of applications of fluorescence (mid-fifties) the fluorimeter was defined as the suitable detector for determination of pharmaceuticals and subsequently, this detection mode has been widely applied. Therefore, it is mandatory to develop new strategies to discover or to enhance in a simple way the native fluorescence of organic compounds to increase the number of analytes to be determined by direct fluorescence.In the present paper are studied further applications of a new tool suitable to increase the research in analytical field. Calculations on molecular connectivity and discriminant analysis are applied to a certain number of pharmaceuticals (and some pesticides) on which fluorescence behaviour was observed in an experimental screening or obtained from scientific literature. The screening tests were based on the on-line fluorimetric measurement by using a continuous-flow assembly. The screening comprised pre-selected compounds with different molecular structures. The theoretical predictions agree with the empirical results from the screening test.     

Improved Iterative Version of the Coats-Redfern Method to Evaluate Non-Isothermal Kinetic Parameters

An improved version of the Coats-Redfern method of evaluating non-isothermal kinetic parameters is presented. The Coats-Redfern approximation of the temperature integral is replaced by a third-degree rational approximation, which is much more accurate. The kinetic parameters are evaluated iteratively by linear regression and, besides the correlation coefficient, the F test is suggested as a supplementary statistical criterion for selecting the most probable mechanism function. For applications, both non-isothermal data obtained by theoretical simulation and experimental data taken from the literature for the non-isothermal dehydration of Mg(OH)₂ have been processed.This revised version was published online in November 2005 with corrections to the Cover Date.     

纳米银增敏鲁米诺液相化学发光分析法测定4-乙酰氨基酚的研究

研究发现在碱性条件下,纳米银对鲁米诺-铁氰化钾液相化学发光体系发光信号具有明显的增敏作用,而4-乙酰氨基酚对该体系具有强烈的抑制作用。结合流动注射技术,建立了流动注射化学发光分析法测定对乙酰氨基酚的新方法。该方法测定对乙酰氨基酚的线性范围为9.0×10-12～1.0×10-10g/mL(0.9947)和1.0×10-1...     

Analysis of the cyclic tensile behaviour of an elasto-viscoplastic polyamide

The present paper is concerned with the experimental and theoretical investigation of the progressive accumulation of inelastic deformation observed in cyclic tension tests performed on a particular polyamide. The elastic properties are not strongly affected by the strain rate, but the strain hardening induced by the plastic deformation is rate-dependent. Thus, the material behaviour is elasto-viscoplastic rather than viscoelastic or elasto-plastic. For the polymer studied in this paper, the kinematic hardening is much more significant than the isotropic hardening, and a negative plastic strain rate may occur even with a positive stress. The kinematic hardening is strongly dependent, not only on the accumulated plastic strain, but also on the loading rate. An elasto-viscoplastic mechanical model able to describe the cyclic inelastic behaviour for an arbitrary loading history is proposed. All parameters that arise in the theory are identified experimentally. The preliminary theoretical results concerning the modelling of cyclic load-unload tests are in good agreement with the experiments.