Stable in situ sorting and minimum data movement

In this paper, we describe an algorithm to stably sort an array ofn elements using only a linear number of data movements and constant extra space, albeit in quadratic time. It was not known previously whether such an algorithm existed. When the input contains only a constant number of distinct values, we present a sequence ofin situ stable sorting algorithms makingO(n lg^(k+1) n+kn) comparisons (lg^(K) means lg iteratedk times and lg* the number of times the logarithm must be taken to give a result 0) andO(kn) data movements for any fixed valuek, culminating in one that makesO(n lg*n) comparisons and data movements. Stable versions of quicksort follow from these algorithms.Research supported by Natural Sciences and Engineering Research Council of Canada grant No.A-8237 and the Information Technology Research Centre of Ontario.Supported in part by a Research Initiation Grant from the Virginia Engineering Foundation.     

An STO-3G investigation of barriers to rotation in model systems for aromatic polycarbonates

Non-empirical, STO-3G, and semi-empirical, MNDO, calculations have been performed to investigate the rigid rotation of the phenyl group in phenyl carbonic acid, as a model for Bisphenol A polycarbonate. The MNDO results predict a barrier to rotation of ～55 kcal mole^?1, a factor of ～2 greater than that for the STO-3G computations. Analysis of the relevant orbital energies dictates that the lowest excited state of phenyl carbonic acid is $\text{π → π}{}^1$.     

Bupropion hydrochloride: the development of a chiral separation using an ovomucoid column

The separation of bupropion enantiomers on an ovomucoid stationary phase was investigated. The mobile- and stationary-phase parameters that may influence the separation were identified. The parameters that were studied include: type and concentration of organic modifier, mobile phase pH, ionic strength, type of buffer, and column temperature, as well as the effect that the amount of sample injected had on the separation. The optimized chiral separation baseline-resolved the enantiomers in less than 10 min. Calibration curves for a standard were linear over a range of 0.27-53.0 microg/g (ppm) with a correlation coefficient of 0.999 for both enantiomers. A detection limit of 0.13 microg/g and a quantitation limit of 0.27 microg/g were also found. The system precision of the method was 0.2%.     

A preliminary investigation of the thermal and X-ray induced degradation of cellulose nitrates by FAB/SIMS and 13C NMR

Some surface aspects of the thermal and X-ray induced degradation of a cellulose nitrate have been studied by FAB/SIMS.The pristine material gives peaks at 30 and 46 amu, indicative of NO⁺ and NO₂⁺ originating from the nitrate ester groups. The thermally degraded material indicates these peaks at slightly lower intensities, whereas the X-ray degraded material shows little evidence for their appearance. These data complement recent ESCA data on the same systems.¹The conclusion is that electromagnetic degradation is predominantly a surface effect, whereas thermal degradation is a bulk oriented phenomenon. ¹³C nmr has been used to add further evidence for this last point.     

膜流动电位测试中Ag-AgCl电极的制备及稳定性研究

膜的动电特性研究中,往往采用流动电位方法。该方法中,Ag-Ag Cl测试电极的质量是影响测试准确性的关键要素。本文采用正交试验设计和方差分析,着重考察电解法制备Ag-Ag Cl电极过程中,电流强度(I)、氯化时间(t)、电解质溶液浓度(CHCl)、电极来源(n)、烘烤温度(T)、活化电极溶液浓度(CKCl)等因素对Ag-Ag Cl电极稳定性的影响。得到Ag-Ag Cl电极的最优制备参数为:电流密度3.0m A/cm2,氯化时间50min,盐酸浓度0.1mol·L-1,烘烤温度120℃,活化电极溶液(KCl)浓度0.001mol·L-1;最显著影响因素为电极来源,显著影响因素为氯化时间和烘烤温度。对最优条件组合下制备的AgAg Cl电极,进行了稳定性实验,结果表明:制备的电极具有较好的稳定性,24h内电极电位漂移量小于0.10mv,7天内电极电位漂移量小于0.2mv;在聚偏氟乙烯中空纤维超滤膜流动电位测试中,流动电位与流动压差具有良好的线性和可重复性,回归曲线R20.99,变化规律符合Helmholtz-Smoluehowski公式,可以较好满足膜的流动电位测试要求。     

镁掺杂氧化铈整体式催化剂催化CO2和CH3OH直接合成碳酸二甲酯

采用共沉淀法成功地合成了不同Mg掺杂量的Ce_1-xMg_xO₂(x=0.05、0.10、0.15、0.20)固溶体催化材料,并运用透射电子显微镜(TEM)、X射线衍射(XRD)、氮气吸附-脱附测试、拉曼光谱、X射线光电子能谱(XPS)、CO₂程序升温脱附(CO₂-TPD)等技术对这些材料进行了表征。结果发现,通过调控CeO₂晶格中Mg的含量,可以调控所制备的Ce_1-xMg_xO₂催化材料的粒径、比表面积、表面缺陷等。其中Ce_0.90Mg_0.10O₂展现了最佳的表面性质,具有最小的平均粒径(约5.8 nm),最大的比表面积(约136 m2·g^-1)以及最高的表面氧含量(31.98%)。将Ce_1-xMg_xO₂催化材料涂覆在堇青石蜂窝陶瓷上制成整体催化剂,考察其对CO₂和CH₃OH直接合成碳酸二甲酯的催化性能。在140℃、2.4 MPa、反应2 h的条件下,Ce_0.90Mg_0.10O₂整体催化剂上碳酸二甲酯的收率高达20.21%,催化效果明显优于CeO₂和其余的Ce_1-xMg_xO₂(x=0.05、0.15、0.20)催化材料。