Organosoluble and transparent polyimides derived from alicyclic dianhydride and aromatic diamines

Organosoluble polyimides were synthesized with the alicyclic dianhydride 1,8‐dimethylbicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet–visible absorption lower than 310–320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5–2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110–119, 2002     

Estimation of diuretic drugs in biological fluids by HPLC

Summary This critical review of different methods proposed for the determination and screening of diuretics is directed mainly, because of its potential application, towards highperformance liquid chromatography.     

两相滴定法研究2-乙基己基膦酸单2-乙基己基酯从盐酸介质中萃取钕(Ⅲ)的动力学

本文利用两相滴定法作为分析手段,用恒界面池搅拌法考察了多种因素对2-乙基己基膦酸单2-乙基己基酯(HEHEHP,HA)从盐酸介质中萃取Nd(Ⅲ)动力学的影响,从实验结果推论出萃取过程为界面化学反应控制型机理。     

氨基苯磺酸和氨基萘磺酸在反相离子对色谱和离子色谱中分离行为的比较

本文考察了氨基苯磺酸和氨基萘磺酸染料中间体在反相离子对色谱和离子色谱中的分离行为，结果表明一些异构体在反相色谱中的保留顺序与离子色谱中的顺序发生颠倒。静电作用力在离子色谱中对保留值的贡献比在反相离子对色谱中对保留值的贡献要大，而疏水作用力在反相离子对色谱中对保留值的贡献却较在离子色谱中对保留值的贡献要大。离子对色谱更有利于有机离子的分离分析。     

Structural Features of Solid Phases and Topology of Phase Diagrams

The paper considers model phase diagrams of binary and ternary systems involving transformations (transitions) of phase equilibria. The relationship between the type of structural solidstate transformation and the type of phase diagram is shown. Topological series of phase diagrams of systems with continuous and limited types of solid solutions are considered, including phase diagrams with polymorphic transitions between intermediate solid phases of variable composition.     

Pressure effects on the phase transition of urea adducts withn-paraffins and polyethylene

The decomposition of urea adducts with hydrocarbons is treated as a first-order phase transition and the pressure dependence is studied up to 0.7 GPa for several kinds of adducts. The thermodynamic quantities at the decomposition of the adduct can be analysed as a sum of those quantities of the component materials. The transition from the orthorhombic to the hexagonal form of the adduct with polyethylene is also investigated by X-ray diffraction and the pressure dependence of the lattice parameters is measured for the adducts. The results are compared with the phase transition in the pure paraffin.     

Effect of Pluronic F127 on the pore structure of macrocellular biodegradable polylactide foams

Thermally induced phase separation technique was utilized to fabricate biodegradable poly(l ‐lactic acid) (PLLA) macrocellular foams which were capable of being applied in tissue engineering. The block copolymer Pluronic F127 composed of (polyethyleneoxide)‐(polypropyleneoxide)‐(polyethyleneoxide) [(PEO)‐(PPO)‐(PEO)] was used as a porogen. Water/dioxane mixtures with different volume ratios were used as solvents. The addition of Pluronic F127 could induce an appearance of large pores (50–200 μm) besides small pores (10–20 μm) or a change from a solid–liquid phase separation to a liquid–liquid phase separation. The role of Pluronic F127 depends on the water/dioxane ratios in the PLLA/dioxane/water system. The X‐ray diffraction patterns and porosity measurement results showed that Pluronic F127 was crystallized and existed on the pore wall. The effect of Pluronic F127 on changing pore structure is attributed to the occurrence of the interaction of the lipophilic PPO blocks in Pluronic F127 with PLLA clews, consequently, this results in PLLA aggregation and early phase separation on cooling. Copyright © 2004 John Wiley & Sons, Ltd.     

Gas Phase Catalysis by Metal Nanoparticles in Nanoporous Alumina Membranes

Nanoporous alumina membranes, loaded with palladium and ruthenium nanoparticles of various size, were used for gas phase hydrogenation of 1, 3‐butadiene and for oxidation of carbon monoxide, respectively. Those membranes contain 10⁹ ‐ 10¹¹ pores per cm², all running perpendicular to the surface. Membrane discs of 20 mm in diameter and only 60 μm thick, incorporated in a reactor in which the reactants can be pumped in a closed circuit through the pores, turned out to very actively catalyze hydrogenation of butadiene (Pd) and oxidation of CO (Ru). The activity of the Pd catalysts depends characteristically on the particles size, the gas flow, and of the educts ratio. As could be expected, larger particles are less active than smaller ones, whereas increasing gas flows in case of hydrogenation accelerates the reactions. Excessive hydrogen reduces selectivity with respect to the various butenes, but favours formation of butane.     

CuCrAl和CuCrZr低温液相合成甲醇催化剂的研究

 用络合共沉淀法制备了CuCrAl和CuCrZr复合氧化物液相合成甲醇催化剂，其比表面分别达到119和116m2／g．在5．0～5．5MPa和383K条件下，分别用间歇式和流动式反应釜考察了催化剂的活性和稳定性．结果表明：CuCrAl和CuCrZr的活性均明显高于CuCr；CuCrAl的活性略高于CuCrZr，但甲酸甲酯（MF）的选择性明显低于CuCrZr；两者在12h内未见活性明显下降．甲醇钠在反应过程中部分转化为甲酸钠和NaOH．CuCrAl和CuCrZr有较高的氢解活性可抑制甲醇钠与MF生成甲酸钠，从而有较低的甲酸钠浓度．但是，Al2O3和ZrO2的酸性有利于甲醇脱水，引起甲醇钠水解生成NaOH．溶剂对CuCr基催化剂的活性和选择性有明显影响．对反应机理进行了讨论．     

高效液相色谱指纹图谱应用于地黄的研究

利用高效液相色谱建立了地黄的色谱指纹图谱。采用反相C1 8柱 (5 μm ,1 5 0mm× 4.6mm) ,流动相甲醇∶水 (V V =5∶95 ) ,检测波长为 2 80nm ,流速 1 .0mL min进行实验。根据相对保留值和相对面积值对色谱指纹图谱进行分析对比研究 ,建立了控制地黄药材质量的新方法。该法为中药样品的鉴定提供了较全面的信息 ,并为HPLC在复杂组分的样品分析领域开拓了新的应用途径。