硫醇在金电极上的SA单分子层膜的电化学研究

金基底上的硫醇自组装单分子层膜(Self-asembledmonolayers,SAMs)具有良好的稳定性和有序性,因此在基础研究及应用技术等领域都受到了广泛的重视^[1].通过电化学方法测定自组装膜对溶液中电活性物质的异向电子转移的阻碍作用.     

向量自激门限自回归（VSETAR）序列的遍历性

本文主要考虑二维自激门限自回归模型：Ｘ（ｔ）＝Ｉ［Ｘ（ｔ－１）∈Ｒｉ］ＡｉＸ（ｔ－１）＋ε（ｔ），其中Ａｉ（ｉ＝１，２，３，４）为２×２系数矩阵，｛ε（ｔ）｝为二维ｉ．ｉ．ｄ序列。我们得到｛Ｘ（ｔ）｝为遍历的四个充分条件。     

表面活性剂在水溶液中聚集状态的1H NMR研究

表面活性剂在水溶液中的自扩散系数,¹H化学位移和自旋晶格弛豫的NMR测量表明,上述参数随表面活性剂浓度而变化,并在某一浓度开始有转折点.这一转折点恰好对应着各自的临界胶团浓度.表面活性剂分子的不同基团的质子化学位移随其浓度变化幅度的不同提供胶团形成的分子水平描述.     

Effect of pH on the Enantiospecificity of Homocysteine Monolayer on Au(111) for the Redox Reaction of 3,4‐Dihydroxyphenylalanine

The effect of pH on the enantiospecificity of Au (111) electrode modified with L ‐homocysteine was evaluated for the electrochemical redox reaction of 3,4‐dihydroxyphenylalanine (DOPA). Cyclic voltammetric peaks clearly exhibited enantiospecificity at pH 0.6 and 2, whereas no enantiospecificity was observed at pH 3, 4, and 5.5. Scanning tunneling microscopy confirmed the highly ordered (2√3×3√3)R30° structure of L ‐homocysteine at pH 0.6, at which L ‐homocysteine molecules form a dimer through the hydrogen‐bond between carboxy groups (COOH), while a disordered structure was observed at pH 5.5. These results suggest that the dimer formed in the acidic solutions at pH below 3 plays an important role in providing the enantiospecificity to the Au(111) surface.     

Self-broadened half-widths and self-induced line shifts for water vapor transitions in the 3.2-17.76 μm spectral region via complex Robert-Bonamy theory

Water vapor in the Earth’s atmosphere is being studied in the 3.2-17.76 μm spectral region by the atmospheric infrared sounder (AIRS) on Aqua, the troposphere emission spectrometer (TES) and the high-resolution dynamics limb sounder (HIRDLS) on Aura, both part of the NASA EOS mission. However, the lack of sufficient data on spectral parameters will hamper the prospect of accurate retrievals of temperature and concentration profiles. The spectral parameters for thousands of water vapor transitions are required, which are hard to determine by measurements alone. As reported previously [Can. J. Chem. 82 (2004) 1013-1027], of the 10 602 measurements of H₂O self-broadening half-widths only 440 intercomparisons with more than 3 data points have estimated uncertainty less than 10%. In this work, we have employed the mean relative thermal velocity approximation of the complex implementation of Robert-Bonamy formalism to obtain the self-broadened half-widths and self-induced line shifts for 5442 water vapor transitions in the 3.2-17.76 μm region. The calculations are compared with the measurement database and trends in the half-widths and line shifts are studied.     

相对映射的周期点

相对Nielsen周期点理论是讨论形如f:(X,A)→(X,A)映射的周期点个数估计问题,本文对已知的估计量给予统一的处理.利用这种方法,定义了两个新的Nielsen型数, NPn(f;X-A)和NΦn(f;X-A),它们分别是映射f在cl(X-A)中的n周期点和最小周期为n的周期点个数的下界.     

Highly‐Sensitive Determination of 6‐Mercaptopurine and Its Metabolites by Electrochemical Reductive Desorption Measurements

The electrochemical detection of 6‐mercaputopurine (6‐MP), which is one of the most well‐known drugs of antimetabolites, and its analogues was studied. The presented method is based on chemisorption (accumulation)/desorption processes of drugs onto/from the Au electrode surface. Using this method, we succeeded in detecting 6‐MP even in very diluted solution (concentration of 6‐MP: 1×10^?8 M). The lower detection limit of 6‐MP was considerably improved compared with the previous HPLC studies by using our proposed system. Desorptive potentials of 6‐MP‐metabolites and its analogues were different from those of 6‐MP. This provides the possibility of simultaneous detection of 6‐MP and its typical metabolites.     

几种环状多肽的几何构型特征及其自组装的理论研究

运用半经验分子轨道AM₁方法优化了6种环状多肽的结构,并进行了振动分析的确认.通过对它们的能量、结构特征和正则振动模式的分析研究,揭示了这类分子具有能够进行自组装过程的结构特征,详细讨论了取代基对结构和自组装过程的影响.     

溶剂对自组装单分子膜电化学行为的影响

用循环伏安法、交流阻抗分析和STM研究了溶剂对自组装单分子膜电化学行为的影响.讨论了以丙酮、二甲基亚砜、乙醇、二甲基甲酰胺和水为溶剂制备的4-羟基-6-甲基-2-巯基嘧啶(HMMP)自组装单分子膜对抗坏血酸(AA)、多巴胺(DA)的电化学行为.结果表明,不同溶剂下制备的单分子膜对AA和DA的催化氧化表现出截然不同的行为;交流阻抗分析定量得出HMMP(丙酮)/Au电极与HMMP(二甲基亚砜)/Au电极的交换电流密度分别为1.14μA/cm²和2.04μA/cm²,电极表面覆盖度分别为93.2%和96.2%,STM图象显示出以丙酮和二甲基亚砜为溶剂制备的单分子膜具有不同的致密性和有序性.     

树枝状大分子的自组装超薄膜

树枝状化合物因具有三维立体结构、均一的分布和多而密且可修饰性强的外官能团,使之作为结构单元进行自组装形成具有特色的超薄膜。Regen等利用整代聚酰胺－胺型（PAMAM）树状分子的胺端基,将其沉积到用Pt^2 离子活化的表面,重复这一过程即得到多层膜。Crook等首先报道了以共价键结合的树状分子膜,这种膜是将PAMAM树状分子的胺端基与巯基十一烷酸组成的单层膜作用生成酰胺键而形成的。Tsukruk等将表面分别带正负电荷的PAMAM树状分子在硅表面进行层状沉积形成超薄膜。研究显示,以树状分子为结构单元经自组装形成的膜具有潜在的用途前景,如作为化学探感器、多相催化剂、滤光片或光学器件基材等。