Clip[5]arenes: A new family of molecular clips

Here we report the design and syntheses of two new triptycene-based rigid acyclic C-shaped hosts, clip[5]arenes C[5]OH and C[5]ME, and the strong host–guest complexation between C[5]OH and an electron-poor bipyridinium salt, paraquat G. The K_a value for the host–guest complex C[5]OH???G was calculated to be (1.09?±?0.36)??×??10⁵?M^?1 in acetone by using a non-linear curve-fitting method based on the UV–vis absorption titration experiments. Furthermore, based on this new host–guest recognition motif, a novel pseudopolyrotaxane-like supramolecular structure was constructed with C[5]OH threaded on polyviologen polymer VP-10.     

具高耐热性多芳烃结构环氧树脂的研究

综述了近年来具耐热性多芳烃结构环氧树脂的发展概况,包括萘系、蒽系和芘系环氧树脂,着重介绍了其合成途径、反应活性及结构与性能的关系.认为多芳烃结构环氧树脂具有良好的耐热耐湿性,颇具发展潜力.其中,萘系环氧树脂与蒽、芘系环氧树脂相比 ,具有较高的反应活性和耐热性,具有较高的实际应用价值.因此,近年来萘基环氧树脂受到研究人员和厂商的关注,并且一些萘系环氧树脂已经应用于生产.     

Direct Electrochemistry of Hemoglobin and Its Electrocatalysis Based on Hyaluronic Acid and Room Temperature Ionic Liquid

A biocomposite material of hyaluronic acid (HA) and room temperature ionic liquid, 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate (BMIMBF₄) was fabricated and characterized by voltammetry and electrochemical impedance spectroscopy. Hemoglobin (Hb), as a model protein, was immobilized in this biocomposite on glassy carbon electrode to investigate its direct electrochemistry. A pair of well‐defined, quasireversible cyclic voltammetric peaks appeared with the formal potentials (E°′) at ?0.360 V (vs. SCE). The Hb modified electrode exhibited an excellent electrocatalytic activity to the reduction of H₂O₂ with a wide linear range, good selectivity, sensitivity and reproducibility, which had potential application to fabrication the third‐generation biosensor.     

High photocatalytic activity and stability for decomposition of gaseous acetaldehyde on TiO2/Al2O3 composite films coated on foam nickel substrates by sol-gel processes

A set of anatase titanium dioxide (TiO₂) films coated on foam nickel that modified by Al₂O₃ films as transition layer (indicated as TiO₂/Al₂O₃ films) were synthesized via sol-gel route. The bulk and surface properties of the TiO₂/Al₂O₃ films were characterized by thermal gravimetric and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and BET. The photocatalytic activities of TiO₂/Al₂O₃ films were investigated based on the degradation of gaseous acetaldehyde under ultraviolet (UV) irradiation. The foam nickel is a promising substrate material in practical applications because of its excellent hydrodynamic properties for gas passing. The TiO₂/Al₂O₃ composite films showed much higher photocatalytic activity and stability for degradation of gaseous acetaldehyde than the onefold TiO₂ films. The significant enhancement in photocatalytic activity and stability can be ascribed to the coating of Al₂O₃ transition layer, which concentrates the target substances around TiO₂ particles and increases the specific surface area (SSA) of the substrate (the SSAs of bare foam nickel and Al₂O₃ modified foam nickel are 0.12 and 113.7 m²/g, respectively) to provide more sites for TiO₂ loading.     

基于Fourier变换的裂解价差期权定价

本文研究了期货期权和裂解价差期权的定价问题.利用Fourier变换方法,在ASub CIR模型的基础上,获得了单因素期货期权,两因素期货期权以及价差期权价格的表达式,最后用C++和MATLAB计算出期权的价格,解决了利用特征函数展开法计算期权价格时速度较慢且不稳定的问题.     

二氧化碳氧化丙烷制丙烯催化反应的研究铬镁铝复合氧化物催化剂的制备、表面微量吸附量热及催化性能

以共沉淀法合成的铬镁铝类水滑石为前体,制备了一系列不同原子比的铬镁铝复合氧化物,研究了其对二氧化碳氧化丙烷制丙烯反应的催化性能.采用微量吸附量热技术,以CO2和NH3为探针分子定量地表征了样品表面酸碱中心的强度和数量,并与其催化性能进行了关联.结果表明,Cr:Mg:Al原子比为1:1:1的催化剂具有较大的比表面积(94.5m2/g),样品中Mg(Al1.5Cr05)O4物相的含量最多.样品表面存在数量较多强度较强的酸性中心和数量最少强度较弱的碱性中心,对NH3吸附,它的吸附热为145 kJ/mol,吸附覆盖度为3.55μmol/m2;对CO2吸附,它的吸附热为115kJ/mol,吸附覆盖度为0.063μmol/m2.该样品的催化活性最高,在温度为650℃,CO2/C3H8摩尔比为3.6,GHSV(C3H8)为3000 h-1时,C3H8的转化率为22.8%,C3H6的选择性为83.5%,收率为19.1%.     

脉冲熔融-飞行时间质谱法测定Ti-Al合金中Ar

本文以标准气体参考物质为依据绘制Ar校准曲线,利用脉冲熔融-飞行时间质谱法建立准确测定钛铝合金中Ar的方法。程序升温法确定钛铝合金中氩可以在分析功率为2800 W时完全释放。并对比了助熔剂和称样量等分析条件对实验结果的影响,结果表明,采用高纯镍篮,钛铝合金中Ar释放完全。本方法测定值与传统脉冲熔融-热导法测定结果基本一致。     

A modified finite element method for determining equilibrium capillary surfaces of liquids with specified volumes

This paper describes a modified finite element method (MFEM) for determining the static equilibrium shape of the capillary surface of a liquid with a prescribed volume constrained by rigid boundaries with arbitrary shapes. It is assumed that the liquid is in static equilibrium under the influence of surface tension, adhesion, and gravity forces. This problem can be solved by employing the conventional FEM; however, a major difficulty arises due to the presence of the volume (integral) constraint and usually requires the use of the Lagrange multiplier method, the sequential unconstrained minimization technique, or the augmented Lagrange multiplier method. With the MFEM, the space variables defining the equilibrium surfaces (or curves) are expanded in terms of parametric interpolation functions, which are designed such that the boundary conditions and the integral constraint equation are automatically satisfied during each iteration of a direct numerical search process. Hence, there is no need to include Lagrange multipliers and/or penalty factors and the problem can be treated more simply as one involving unconstrained optimization. This investigation indicates that the MFEM is more efficient and reliable than the other methods. Results are presented for several case study problems involving liquid solder drops. Copyright © 2000 John Wiley & Sons, Ltd.     

p-溴甲苯电合成制备p-溴苯甲醛的气相色谱分析

p-溴苯甲醛是重要的有机合成中间体,采用间接电氧化法生产p-溴苯甲醛操作简单,经济效益好且污染少。电合成产物含量的分析对保证生产的正常进行至关重要。芳醛分析常用的方法有2,4-二硝基苯肼重量法和盐酸羟胺滴定法。重量法费时,重现性差,化学滴定法终点突跃不明显。文献报道了采用气相色谱法测定芳醛效果良好。卤代芳醛沸点较高,本文采用高温气化和程序升温分离测定少溴苯甲醛,得到了满意的结果。