酒石酸镁对水合草酸钙晶体生长的调控作用

本文在凝胶模拟体系中研究了Mgtart对草酸钙生长、 聚集和晶型、 晶相等的影响, 以期阐明Mgtart防治泌尿系结石形成的可能机理, 为临床医学提供参考.     

钯催化气相氧化羰基化合成碳酸二甲酯

通过催化剂反应性能和反应前后XPS谱图对比，分析了负载型钯催化剂在甲醇气相氧化羰基化合成碳酸二甲酯过程中的失活原因，研究了HCl在维持催化剂活性及失活催化剂再生中的作用．结果表明，氯离子的流失是负载型钯碳催化剂失活的主要原因．由于氯离子的流失，对于PdCl2／AC催化剂，钯很容易从二价变为零价：对于PdCl2-CuCl2／AC催化剂，CuCl2发生变化，失去使钯保持二价氯化物状态的功能．在反应过程中补充HCl可以延长催化剂的寿命，也可以利用HCl对失活催化剂进行再生，但采用HCl不能从根本上解决催化剂失活的问题．     

Cationic Heteroconjugation Constants in the OHN+ and NHO+ Systems in Propylene Carbonate: Dependence on Difference in Basicity

Cationic heteroconjugation equilibria of more than ninety systems consisting of substituted pyridines, their N-oxides, and trimethylamine N-oxide, i. e., in systems with mixed hydrogen bridges of type OHN⁺ (NHO⁺) were studied in propylene carbonate. Both experimental systems without proton transfer, BH⁺/B₁, and those with proton transfer, B₁H⁺/B, were explored. The stability of the mixed hydrogen bridges, OHN⁺ (NHO⁺), is compared with that of the OHC⁺-type bridges. The influence of the difference in basicity of the conjugate base of the proton donor and the proton acceptor on the presence of the proton transfer equilibria, and, consequently, the possibility of determination of the cationic heteroconjugation constant values is discussed.     

Surface modified precipitated calcium carbonates at a high degree of dispersion

Calcium carbonates of different degrees of surface hydrophobicity were obtained when sorbic acid or polyoxyethylene glycol were present during the precipitation. In the presence of trace amounts of divalent cations carbonates with high surface hydrophilicity and improved monodisperse character are obtained. Surface modification of the calcium carbonates by several proadhesive compounds can markedly improve the chemical affinity of the carbonates to polymers. Very effective are isostearoyl titanate and two polyoxyethylene compounds. Precipitated calcium carbonates modified with 2 to 3 percent (wt/wt) of isostearoyl titanate increased the tensile strenght of butadiene-styrene rubber by approximately 100%. Polyurethane is only strengthened when 30 wt/wt of a filler are introduced independently of the type proadhesive compounds. The best strength and hysteresis of polyurethanes are obtained with calcium carbonate modified with 2 percent (wt/wt) of polyoxyethylene glycol.     

Habit modification of calcium carbonate in the presence of malic acid

The ability of malic acid to control calcium carbonate morphology has been investigated by aging calcium chloride solution in the presence of urea in a 90 °C bath. Malic acid favors the formation of calcite. A transition from single block to aggregate with special morphology occurs upon increasing malic acid concentration. The morphological development of CaCO₃ crystal obviously depends on the starting pH. CaCO₃ crystal grows from spindle seed to dumbbell in the pH regime from 7 to 11; while it evolves from spindle seed, through peanut, to sphere at pH=11.5. Both dumbbell and sphere consist of rods that are elongated along c-axis and capped with three smooth, well-defined rhombic {1 0 4} faces. A tentative growth mechanism is proposed based on the fractal model suggested by R. Kniep and S. Busch [Angew. Chem. Int. Ed. Engl. 35 (1996) 2624].     

检测易爆气体的催化发光传感器研究

报道了一种用于定量分析易爆气体混合物丙烷和异丁烷的基于碳酸锶纳米材料的催化发光传感器。基于该传感器在不同温度下对两种气体的灵敏度不同，在320℃和342℃两个工作温度下，两种气体的浓度范围均为1000mL／m^3～10000mL／m^3时，分别建立了混合组分浓度相对催化发光强度的两个线性回归方程。在342℃时，丙烷和异丁烷的检出限（3σ）分别为50mL／m^3和20mL/m^3。可通过解上述两个联立方程式求得未知混合物中两组分的浓度。外来物质甲烷、乙烷、CO、氨气通过传感器时，甲烷和乙烷分别引起5．6％和17．2％的干扰，其它气体不干扰测定。20000mL／m^3的水蒸气不干扰2000mL／m^3丙烷和异丁烷气体的测定。用该法分析了人工合成样品中两种气体的浓度。     

The formation of cation-ligand complexes of tributylammonium cation with diethyl carbonate,ethylene carbonate,propylene carbonate, 4-butyrolactone,ethyl acetate,and cyclopentanone ino-dichlorobenzene at 25°C

The effects of adding millimolar quantities of a series of compounds containing the carbonyl function on the conductances of solutions (0.2 mM) of tri-n-butylammonium picrate ino-dichlorobenzene solvent at 25°C have been measured. Values of the complex formation constants K ₁ ⁺ for 1:1 cation-ligand complexes are derived from these data. The corresponding values of –G ₁ ⁰ at 25°C are (in kcal-mole ^–1 ): 4-butyrolactone, 4.29; propylene carbonate, 3.87; ethylene carbonate, 3.59; cyclopentanone, 3.42; ethyl acetate, 2.84; and diethyl carbonate, 2.78. These results together with earlier results from this laboratory are discussed in terms of the effects of structure on cation-ligand affinity.     

交联助剂对PPC／NBR弹性体结构和性能的影响

研究了马来酸酐（ＭＡ）及异氰脲酸三烯丙酯（ＴＡＩＣ）对聚丙撑碳酸酯／丁腈橡胶共混弹性体结构和性能的影响，发出加入ＭＡ或ＴＡＩＣ能有效地改善交联网络；加入适量ＭＡ能显著改善共混弹性体热氧老化稳定性；加入ＴＡＩＣ使共混弹性体具有优良的高弹特性和力学性能。     

聚合物与草酸钙相互作用的研究进展及其对预防尿路结石的意义

聚合物对泌尿系结石的形成具有抑制和促进双重作用。本文综述了聚合物对尿石矿物草酸钙成核、生长、聚集及其与尿路细胞膜黏附影响的研究进展,讨论了聚合物影响草酸钙晶面和形貌的机理,指出了该领域所面临的问题和将来的发展方向。