1,3,5-均苯三羧酸根金属-有机多重框架结构配合物

综述了近年来1,3,5-均苯三羧酸(H3BTC)与金属配位形成金属配合物的研究进展。对1,3,5-均苯三羧酸根(BTC)作为桥基时的配位特点及其桥联多核配合物的合成方法和结构特点进行了简要介绍,并对今后BTC类超分子网络配合物应用与结构研究的发展方向进行了展望。     

线扫伏安法同时测定5-羟基色氨酸和色氨酸

研究了色氨酸和5-羟基色氨酸在玻璃碳电极上的电化学行为,研究了不同pH、静置时间、扫描速度以及表面活性剂等的影响,探讨了色氨酸和5-羟基色氨酸在玻璃碳电极上的氧化机理,建立了线扫伏安法同时测定色氨酸和5-羟基色氨酸的方法.实验发现,在含3.33×10-4 mol/L十二烷基磺酸钠的0.1mol/L柠檬酸(pH=4.50)介质中,5-羟基色氨酸和色氨酸分别在 0.675V和 1.070V产生一灵敏的氧化峰.对5-羟基色氨酸,相应的氧化峰的峰高与浓度在2.40×10-5 mol/L～8.00×10-4 mol/L范围内呈良好的线性关系,线性相关系数为0.9994;对色氨酸,其氧化峰的峰高与浓度在2.40×10-5 mol/L～6.40×10-4 mol/L浓度范围内呈良好的线性关系,线性相关系数为0.9929.该方法测量2.00×10-4 mol/L色氨酸和5-羟基色氨酸的相对标准偏差分别为3.2%和3.8%(n=10).     

TATB二聚体分子间作用力及其气相几何构型研究

采用对称性匹配微扰理论(SAPT)定量地求得TATB分子间的静电、交换排斥、诱导和色散等分子间作用能项, 从理论上揭示了TATB分子间作用本质; 在此基础上, 阐明了密度泛函在研究TATB二聚体时的适合性问题. 结果表明: (1)在有分子间氢键的TATB二聚体中, 库仑力足以与交换排斥力相抗衡, 起主导作用. (2)含分子间氢键的气相TATB二聚体的合理几何构型为平面型结构, 此结构的产生与色散力无关, 因此不管泛函是否含有近程色散作用, 均应预测到这种强极性的平面型结构. (3)在无分子间氢键的TATB二聚体中, 库仑力难以与交换排斥力相抗衡, 色散作用起到了关键作用; (4)在这种情况下, 未含有近程色散作用的密度泛函不可能给出合理构型. 恰好相反, 含有近程色散作用的密度泛函PBE0却能正确地预测到具有“平行重叠”结构且呈微弱极性的TATB二聚体, 色散力是导致这种构型产生的根本原因. “平行重叠”TATB二聚体是典型的色散体系, 其色散力占绝对主导地位并极有可能起源于两个TATB分子上π电子的相互作用. (5)对于所有TATB二聚体, 色散力或很显著或起主导作用. 由于密度泛函或未含有近程色散, 或只能部分地把近程色散表达出来, 这样使得当前所有密度泛函不可能精确求得这些二聚体的作用能.     

伐地那非衍生物的合成和体内活性评价

首次完成了伐地那非衍生物—2-[2-乙氧基-5-(4-乙基-哌嗪-1-磺酰基)-吡啶]-5-甲基-7-丙基-3H-咪唑[5,1-f]-三 嗪-4-酮(1)的合成, 并且对其进行了家兔阴茎勃起的体内实验, 结果表明该化合物无壮阳作用.     

2-硫代丁基-5-巯基-1，3，4-噻二唑Ag[I]修饰的钼硅酸盐纳米颗粒的制备及摩擦性能

以合成的2-硫代丁基-5-巯基-1,3,4-噻二唑为配体,在醇-水体系中制备了Keggin结构钼硅杂多阴离子有机衍生物的纳米颗粒,以透射电子显微镜、扫描电子显微镜、傅立叶变换红外光谱仪、热分析仪等测试手段对此纳米颗粒的形貌、组成和结构进行了表征,并在机械式四球长时抗磨损试验机上考察了其摩擦学性能．分散型实验结果表明化合物在有机溶剂中分散性能良好,红外光谱表明所合成的纳米颗粒具有杂多酸Keggin骨架结构无机核,透射电镜分析表明颗粒平均粒径约为10nm,热分析娃示分解温度范围为200～300℃．作为新型纳米润滑油添加剂,在最佳添加质量分数为0．05％,负荷300N,摩擦时间30min,转速1450r／min的条件下,与空白相比磨斑直径减小27．9％,摩擦系数减小15．3％．     

M?ssbauer spectroscopy in heterogeneous catalysis: A brief overview and recent study on paramagnetic features detected in catalytic centres of Fe-ZSM-5

A short retrospection is given on the development of M?ssbauer spectroscopy and on the early period of its application to heterogeneous catalysis in Hungary. Besides the historical view, we present results of recent studies of a latest application on a nanosystem. Namely, catalytic centres in Fe-ZSM-5 are studied by in situ spectroscopy, the results are correlated with parallel activity measurements in the decomposition of N₂O. Changes in paramagnetic relaxation features are interpreted as the effects of Fe²⁺/Fe³⁺ interconversions. From the analysis, the dominance of the mononuclear species is suggested at lower temperature (620 K). The dinuclear Fe⁽³⁺⁾ _framework-O-Fe⁽²⁺⁾ _{extra-framework} species play probably more expressed role at higher temperatures (∼ 770 K) in the decompositon of nitrous oxide.     

多级孔ZSM-5分子筛的制备及催化噻吩烷基化性能研究

用不同浓度的Na₂CO₃溶液处理ZSM-5分子筛,采用XRD、XRF、SEM、N₂吸附脱附及NH₃-TPD方法对处理前后的ZSM-5分子筛进行表征,并考察了Na₂CO₃溶液处理对ZSM-5分子筛孔结构、酸性以及噻吩烷基化性能的影响。结果表明,Na₂CO₃溶液处理在保持ZSM-5分子筛微孔骨架结构的同时,增加了ZSM-5分子筛的比表面积、外表面积和介孔体积,并调变了酸性。Na₂CO₃溶液处理提高了ZSM-5分子筛催化剂的噻吩烷基化活性和噻吩选择性。一定反应条件下,随着Na₂CO₃溶液浓度增加,多级孔ZSM-5分子筛的噻吩烷基化性能逐渐提高,而噻吩选择性先增加后下降。当Na₂CO₃溶液浓度为2 mol/L时,分子筛的噻吩转化率和噻吩选择性分别为81.26 %和73.15%。当Na₂CO₃溶液浓度为3 mol/L时,噻吩转化率和选择性分别为90.57 %和72.59%。     

Selective carboxylation of substituted phenols with engineered Escherichia coli whole-cells

Selective carboxylation of substituted phenols is realized in the presence of bicarbonate under ambient pressure by engineered Escherichia coli whole-cells expressing various hydroxybenzoate decarboxylases, leading to their corresponding ortho-hydroxybenzoates. This process may be further developed as an efficient route to upgrade lignin-derived phenolic compounds as valuable building blocks.     

TZAAP-Nafion修饰电极溶出伏安法测定痕量铜

近年来,化学修饰电极以其独特的优越性,在分析测试中具有广阔的应用前景[1-6],因此对于新的修饰剂的研究,以及用修饰电极探讨灵敏度高,选择性好的测定方法具有重要的意义。2[2,3,5-三氮唑偶氮]-5-乙酰基氨基苯酚(2-(2,3,5-triazolylazo)-5-acetam idophenol,简称TZAAP)是一种新合成的有机化合物,其结构式为:由于TZAAP可以和金属离子形成稳定的配合物,在光谱法中可以作为显色剂用于环境及生物样品中微量元素的测定[7,8]。Nafion是一种优良的阳离子交换剂,用作电极修饰材料具有良好的离子交换特性[9]。本文作者制备了TZAAP-Nafion修饰…     

Numerical and Experimental Investigation of the Conjugate Heat Transfer for a High-Pressure Pneumatic Control Valve Assembly

This paper uses heat transfer experiments and computational fluid dynamics (CFD) simulations to investigate the conjugate heat transfer (CHT) in a high-pressure pneumatic control valve assembly. A heat transfer test rig was constructed, and time–temperature histories of five test points placed on the valve assembly’s outer surface were recorded for study validation. The Unsteady Reynolds-Averaged Navier–Stokes (URANS) CFD methods with the standard k-ε turbulence closure equations were adopted in the numerical computations. Polyhedral grids were used; time step and mesh convergence studies were conducted. Simulated and measured temperatures profile comparisons revealed a good agreement. The CHT results obtained from CFD showed huge velocity fields downstream of the valve throat and the vent hole. The airflow through the valve was icy, mainly in the supersonic flow areas. Low temperatures below 273.15 K were recorded on the internal and external walls of the valve assembly. The consistency of the measured data with the numerical results demonstrates the effectiveness of polyhedral grids in exploring the CHT using CFD methods. The local entropy production rate analysis revealed that irreversibility is mainly due to viscous dissipation. The current CHT investigation provides a potential basis for thermostress analysis and optimization.