Capillary electrochromatographic separation of enantiomers under aqueous mobile phases on a covalently bonded cellulose derivative chiral stationary phase

A chemically bonded cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase (CSP) was prepared by a radical polymerization reaction. The prepared CSP was packed into fused-silica capillaries with inner diameter of 75 microm to perform enantiomer separations in CEC. The electrochromatographic behavior of the CSP was investigated. On the prepared CSP, high EOF could be generated under acidic mobile phases, which represented an advantage for the separation of acidic enantiomers. Several neutral, acidic, and basic enantiomers were resolved on the prepared CSP under aqueous mobile phases. The column efficiencies were between 20,000 and 100,000 plates/m, which were much higher than those of HPLC. In addition, it was observed that the separation of some enantiomers benefited from the adoption of THF as mobile phase modifier.     

Effect of particle size of activated clay on the adsorption of paraquat from aqueous solution

This paper describes the effect of particle size on the process of paraquat adsorption from aqueous solution onto an activated clay surface at 25 degrees C and initial pH 11.0. Measurements of the pore properties of the clay adsorbents with three different particle sizes (0.053-0.074 mm, 0.037-0.053 mm, and <0.037 mm) were carried out. The rates and isotherms of adsorption have been also investigated by batch methods under the controlled conditions. From the experimental results obtained, the adsorption process can be well described with the pseudo-second order model and Freundlich model for adsorption kinetics and adsorption isotherm, respectively. In addition, the effect of the particle size of the clay adsorbent on the adsorption kinetics was found to be of considerable significance; namely, the rate constant (k) of paraquat adsorption by the clay adsorbent decreased with increasing particle size. It was concluded that the pore properties (i.e., surface area and total pore volume) and particle size of the clay adsorbent played a significant role in determining adsorption capacity and adsorption rate, respectively.     

二氰基二硫纶和邻菲罗啉二酮的镍(Ⅱ)、铜(Ⅱ)、锌(Ⅱ)配合物的合成与性质

二氰基二硫纶和邻菲罗啉二酮的镍（Ⅱ）、铜（Ⅱ）、锌（Ⅱ）配合物的合成与性质彭正合＊潘庆才ａ任小明ｂ张克立秦子斌（武汉大学化学系，武汉４３００７２；ａ南京大学配位化学国家重点实验室，南京２１００９３）关键词：二硫纶邻菲罗啉二酮镍铜锌二硫纶（ｄｉｔｈｉｏ...     

Preparation and chiral recognition of a novel chiral stationary phase for high-performance liquid chromatography, based on mono(6A-N-allylamino-6A-deoxy)-perfunctionalized beta-cyclodextrin and covalently bonded silica gel

A novel chiral stationary phase (CSP) was prepared by immobilizing mono(6A-N-allylamino-6A-deoxy)-perphenylcarbamoylated beta-cyclodextrin onto the surface of silica gel via hydrosilylation. The chromatographic properties of this column were tested with a wide range of structurally diverse racemic compounds and drugs under reverse phases. Separation mechanisms involved are also discussed.     

水相中乙醇对胶体泡沫性质的影响

用不同比例的水-乙醇混合物作水相制备了胶体泡沫（CLA）,实验观察并测定了CLA的形态、粒径分布、半衰期、Zeta电位、水相溶液的粘度和水相/油相之间的界面张力等性质.结果表明，水相中加入乙醇会影响CLA的稳定性和粒径大小,但对CLA的Zeta电位影响不大.乙醇对CLA稳定性的影响主要是由于乙醇分子嵌入到界面膜中导致膜的强度变化以及水相粘度发生变化导致CLA粒子间隙的排液过程发生变化.     

Effects of antimony on the surface tension of molten silicon

The effect of antimony concentration (C(Sb)/mass%) on the surface tension of molten silicon has been determined with the sessile drop method in the temperature range from 1693 to 1773 K and in the range of the oxygen partial pressure, Po(2), in an Ar atmosphere from 10(-23) to 10(-21) MPa. The results show that the surface tension of molten silicon decreases with increasing Sb concentration in the range of C(Sb)<0.9 mass%, which indicates positive adsorption of Sb in molten silicon and can be fairly described with the Szyszkowski's equation. The maximum decrease rate of surface tension is about 65 mN m(-1) (mass% C(Sb))(-1), and the temperature coefficient of surface tension, (partial differential sigma/ partial differential T)C(Sb), increases with increasing C(Sb). The evaporation of the systems was only observed between the melting points of antimony (904 K) and silicon (1683 K), and the surface tension presents no dependence on measuring time above the melting point of silicon.     

冀北滦平地区中生代火山岩中单颗粒锆石的稀土元素特征及启示

通过对滦平地区中生代火山岩中锆石的稀土元素分析,表明髫髻山组顶部火山岩样品中锆石δEu的均值为0.49,（Lu/Gd）N的均值为21.87;然而,土城子组顶部层位、底部层位和张家口组底部层位火山岩样品中锆石的δEu均值分别为0.15,0.06和0.09,（Lu/Gd）N的均值分别为14.51,15.66和16.25.反映了土城子组中锆石的稀土元素特征与张家口组中锆石特征的一致性,而与髫髻山组中的锆石有较大的区别,表明土城子组与张家口组中的火山岩有明显的亲缘性和一致性.结合同位素测年结果和锆石的阴极发光特征,可以认为： 该地区的髫髻山组与土城子组之间不仅时间间隔长,而且火山岩的源区也有较大的区别;土城子组与张家口组之间不仅在时间上基本连续,而且火山岩的源区也有明显的一致性;该分析结果暗示了滦平地区的土城子组与张家口组之间不存在时间的间断和大的构造界面,是相同（或相近）地质背景下形成的,即二者之间应不存在构造转换界面和J3-K1界面.研究表明,在壳源岩浆锆石的稀土元素分析中,（Lu/Gd）N,δEu是相对稳定的、有指示意义的两个重要参数;壳源岩浆锆石的∑LREE的值变化范围较大,尤其是La的丰度变化范围较大,所以在锆石的稀土元素分析中,与La相关的各种比值的指示意义并不明显.     

酚酞型聚芳醚砜(Ⅶ):K_2C0_3存在下PP/DCDPS体系聚合反应机理的研究

利用~(13)C-NMR方法研究了弱碱K_2CO_3存在下酚酞成盐反应及其与活性双卤砜亲核缩聚反应过程中的结构特征。对一系列碱性条件下酚酞(PP)与4,4'-二氯二苯砜(DCDPS)的缩聚反应的研究表明任何影响内酯结构酚酞盐生成的因素都会严重阻碍聚合反应的进行。对模型化合物存在下K_2CO_3在极性非质子溶剂中的溶解/解离行为的研究结果表明酚酞类Card。双酚与固体K_2CO_3之间可能存在着一种特殊的络合作用。基于我们系列研究结果,本文中总结提出了弱碱K_2CO_3存在下酚酞的反应机理。     

MnOx在ZrO2上分散状态及对CO氧化的影响

近年，氧化铝载体以其独特性能引起多方面的关注［1］．当将Pt、Rh金属担载在ZrO2上时，在金属和氧化物之间存在着强的相互作用［2，3］，从而提高了CO氧化和NO的还原性能．目前，许多作者曾对ZrO2。负载氧化铜催化剂进行了较系统的研究[4，5]：氧化锰对许多重要的催化反应有广     

Effects of mixed H2O‐CH3CN solvents on the rate of hydrazinolysis of N‐phenylphthalimide: Spectral and kinetic evidence for the occurrence of N‐aminophthalimide on the reaction path

Kinetic study on the cleavage of N‐phenylphthalimide (NPhPT) in the presence of 0.05 M NH₂NH₂ and mixed H₂O‐CH₃CN solvents reveals the occurrence of reaction scheme where A, B, C, C₁, An, E, and F represent NPhPT, o‐CO^?₂C₆H₄CONHC₆H₅, o‐CONHNH₂C₆H₄‐ CONHC₆H₅, N‐aminophthalimide, aniline, o‐CO^?₂C₆H₄CONHNH₂, and o‐CONHNH₂C₆H₄‐CONHNH₂, respectively. But, in the presence of either nonbuffered ?0.20 M NH₂NH₂ hydrazine buffer of pH ～7.30–8.26 with total buffer concentration ([Buf]_T) of >0.02 M, further conversion of F to 2,3‐dihydrophthalazine‐1,4‐dione (DHPD) has been detected depending upon the length of the reaction time (t), the values of [Buf]_T, and pH. It has been shown that the rate of conversion of C₁ to F is much faster than that of C to C₁ which is much faster than that of F to DHPD. The reaction step A → C involves general base (GB) catalysis, while step C → C₁ seems to involve specific base–general acid (GA) and GB‐GB catalysis. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 147–161, 2005