一种新型C60-硫醚衍生物分子在金表面上的自组装

报导了一种新型C60 硫醚分子在金表面上自组装膜的形成,并通过接触角、扫描隧道显微术（STM）、X射线光电子能谱（XPS）、电化学和光电化学手段对其进行表征.高分辩STM形貌图证明,在Au(111)基底上C60基团存在并直观显示出特殊的单层膜结构. XPS分析表明,这一新型C60 硫醚分子是通过金硫键固定在金表面上的,并且在组装过程中存在分子内碳硫键断裂步骤.     

Calculations by the semi-ab initio method SAM1 on some hydrogen-bonded systems

Eleven examples of various types of hydrogen bonding were calculated by the SAM1 method. The results are compared to published ab initio calculation with respect to geometries and interaction energies. This method appears to be less burdened by failures than its predecessors AM1 and PM3, but is still not fully reliable in predicting the characteristics of the test examples.     

社会核算矩阵的建立和平衡——交互熵方法

可计算一般均衡 (CGE)模型的参数估计或校准要求一个一致性的数据 ,而这个一致性的数据集则由社会核算矩阵 SAM(Social Accounting Matrix)所构成 .由于在许多国家特别是发展中国家 ,由于构成SAM的各种数据来源不同可能使这些来源不同的数据不一致 ,因此如何平衡和估计 SAM则是一个困难和关键的问题 .本文用交互熵方法如何建立和平衡 SAM.     

Solution phase electron transfer versus bridge mediated electron transfer across carboxylic acid terminated thiols

Self-assembled monolayers (SAMs) of thiols with carboxylic acid terminal groups were formed on gold substrates. The electron transfer characteristics of redox species on the above SAM-modified electrodes were studied in acid and neutral media with the help of voltammetry under two different conditions: (1) solution phase electron transfer and (2) bridge mediated electron transfer. Two redox systems, viz., [Fe(CN)₆]^4-/3− and Ru[(NH₃)₆]^2+/3+ were chosen for the solution phase study. Investigations of bridge mediated electron transfer were carried out by functionalising the SAM with redox moieties and then studying their redox behaviour. For this study, ferrocene carboxylic acid and 1,4-diamino anthraquinone were used and they were linked to carboxylic acid terminated thiols by covalent linkage. The voltammetric results with mercaptoundecanoic acid SAM demonstrate the difference in behaviour between solution phase and bridge mediated electron transfer processes.     

Biosensors as a tool for the antioxidant status evaluation

Antioxidants are one of the main ingredients that protect food attributes by preventing oxidation that occurs during processing, distribution and end preparation of food. Physiological antioxidant protection involves a variety of chemical system of endogenous and exogenous origin in a multiplicity of pathways. Associate to this, researches have been directed in the development of methods as biosensors that can characterize antioxidants capable of removing harmful radicals in living organisms in an adequate way. Biosensors have represented a broad area of technology useful for environmental, food monitoring, clinical applications and can represent a good alternative method to evaluate the antioxidant status.The demonstration of the highlighted current application of biosensor as a potential tool to evaluate the antioxidant status is the main aim of this review.     

自组装单分子膜及其表征方法

自组装单分子膜的研究是近年来十分活跃的研究领域. 随着膜的应用领域的拓展 ,对膜的表征方法不断提出新的要求.本文综述了自组装单分子膜体系的类型和基底表面的 处理方法,着重从电化学、谱学、显微学以及表面润湿性等方面综述了近几年来自组装单分子膜的表征方法研究进展, 并对其发展前景作了展望.     

Surface composition of alloys

The practical importance of alloy surfaces in catalysis, corrosion andother aspects of materials performance is widely recognized. What is needed now is sufficient knowledge of the relationship between externally controllable factors — alloy composition, temperature, environment — and surface properties — composition, structure, chemical activity — to control materials performance in these applications. Our purpose here is to review progress in determining and predicting the relationship between one surface property, composition, and certain externally controllable variables: overall composition, temperature, environment and physical form.We find that theoretical treatments of metal alloy surface composition now include essentially all significant physical effects and can predict values for most parameters of interest. Though improvements are still possible, the accuracy of predictions is more often limited by uncertainties or absence of the basic data for the calculations (e.g., thermochemical values) than by the models themselves.Alloy surface composition can now be measured well. The first monolayercomposition of large alloy slabs can be determined quantitatively over a wide temperature range in ultra-high vacuum. Difficulties with specimens of practical interest still challenge experimentalists. Among these are supported catalysts, surfaces under chemisorbed layers and composition of layers below the first. Significant progress is being made and we expect the next few years will see success.     

Electroanalysis of dopamine at a gold electrode modified with N-acetylcysteine self-assembled monolayer

Voltammetric behavior of dopamine (DA) on a gold electrode modified with the self-assembled monolayer (SAM) of N-acetylcysteine has been investigated, and one pair of well-defined redox peaks of dopamine is obtained at the SAM modified gold electrode. The oxidation peak current increases linearly with the concentration of dopamine in the range of  mol l⁻¹. The detection limit is 8.0×10⁻⁷ mol l⁻¹. This method will be applicable to the determination of dopamine in injection of dopamine hydrochloride, and the good recovery of dopamine is obtained. Furthermore, The SAM modified gold electrode can resolve well the voltammetric responses of dopamine and ascorbic acid (AA), so it can also be applied to the determination of dopamine in the presence of ascorbic acid.     

FIA Determination of Paracetamol in Pharmaceutical Drugs by Using Gold Electrodes Modified with a 3‐Mercaptopropionic Acid Monolayer

A flow injection analysis (FIA) method for the determination of paracetamol in pharmaceutical drugs using a gold electrode modified with a self‐assembled monolayer (SAM) of 3‐mercaptopropionic acid is described. At optimized experimental conditions the dynamic concentration range was 0.15 to 15.0 mg L^?1 with a detection limit of 0.2 μg mL^?1 (S/N=3). The repeatability of current responses for injections of 10 μmol L^?1 paracetamol was evaluated to be 3.2% (n=30) and the analytical frequency was 180 h^?1. The lifetime of the modified electrode was found to be 15 days. The results obtained by using the proposed amperometric method for paracetamol determination in four different drug samples compared well with those found by spectrophotometry.     

Electrochemical Characterization of the Self‐assembled Monolayer of 6‐Thioguanine on the Mercury Electrode

A self‐assembled monolayer (SAM) of 6‐thioguanine (6TG) was formed on the hanging mercury drop electrode, under open circuit potential, from 6TG solutions. The SAM has been characterized by cyclic voltammetry under both in situ and ex situ conditions and the experimental data reveal that the film is a densely packed structure of chemisorbed (mercury‐thiol) molecules. The presence of this SAM has no influence on the rate of outer‐sphere electrode reactions but strongly inhibits inner‐sphere processes. The electrode reaction involving the Fe(CN) couple appears reversible in a hanging mercury drop electrode coated by the 6TG‐SAM.