Liquid chromatographic enantioseparation of (RS)‐etodolac using (S)‐levofloxacin and determination of absolute configuration of the diastereomeric derivatives

(RS)‐Etodolac was isolated from commercial tablets and was purified and characterized to be used as racemic standard. A pair of diastereomeric derivatives was synthesized using (S)‐levofloxacin as a chiral derivatizing reagent. The derivatization reaction was carried out under conditions of stirring at room temperature (30°C for 1.5 h) as well as under microwave irradiation; the derivatives obtained by the two methods were compared. Reaction conditions for derivatization were optimized with respect to mole ratio of chiral derivatizing reagent and (RS)‐etodolac. No racemization was observed throughout the study. Separation of diastereomeric derivatives was successful using C₁₈ column and a binary mixture of methanol and triethyl ammonium phosphate buffer of pH 4.5 (80:20, v/v) as mobile phase at a flow rate of 1 mL min^?1 and UV detection at 223 nm. An efficient approach for recognizing chirality and determining the absolute configuration of the diastereomeric derivatives of (RS)‐etodolac is described, which in turn is a measure of the enantiomeric purity of (RS)‐etodolac since the diastereomeric derivatives were separated and isolated using preparative thin‐layer chromatography.     

Analysis of Blind Reconstruction of BCH Codes

In this paper, the theoretical lower-bound on the success probability of blind reconstruction of Bose–Chaudhuri–Hocquenghem (BCH) codes is derived. In particular, the blind reconstruction method of BCH codes based on the consecutive roots of generator polynomials is mainly analyzed because this method shows the best blind reconstruction performance. In order to derive a performance lower-bound, the theoretical analysis of BCH codes on the aspects of blind reconstruction is performed. Furthermore, the analysis results can be applied not only to the binary BCH codes but also to the non-binary BCH codes including Reed–Solomon (RS) codes. By comparing the derived lower-bound with the simulation results, it is confirmed that the success probability of the blind reconstruction of BCH codes based on the consecutive roots of generator polynomials is well bounded by the proposed lower-bound.     

Analytical and semi‐preparative enantioresolution of (RS)‐ketorolac from pharmaceutical formulation and in human plasma by HPLC

An efficient, simple, validated, analytical and semi‐preparative HPLC method has been developed for direct enantioresolution of (RS)‐Ketorolac (Ket) using monochloro‐methylated derivatives of cellulose and amylose, i.e. cellulose (tris‐3‐chloro‐4‐methylphenylcarbamate) and amylose (tris‐5‐chloro‐2‐methylphenylcarbamate) as chiral stationary phases (CSPs) with photo diode array detection at 320 nm. Enantioresolution was carried out in samples of human plasma spiked with (RS)‐Ket under normal and reversed‐phase elution modes with suitable mobile phase compositions. The effect of nature of alcohols (MeOH, EtOH, PrOH and n‐BuOH) and other solvents (MeCN and MeOH) as organic modifiers in the mobile phase was investigated on the separation performance of two CSPs in terms of retention and separation of enantiomers. The best resolution was observed on cellulose‐based CSP using EtOH, while using 2‐PrOH (15%) and amylose‐based CSP obtained the highest retention. Under reversed‐phase elution mode the best enantioseparation was observed using 30% MeCN with ammonium formate buffer. The elution order of enantiomers was ascertained by determining specific rotations. The limit of detection and quantitation values were 5 and 15.5 ng/mL for each enantiomer of (RS)‐Ket, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene – a single atomic layer of graphite – is the newest member in the family of carbon allotropes and has emerged as the “celeb” material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.     

基于触发行为的J、K激励函数的最小化技术

以JK触发器为例,提出了一种基于触发器行为的J、K激励函数的最小化技术.通过其与目前国内教科书中介绍的基于触发器次态函数最小化技术的对比与分析,证明了新的最小化技术是一种更行之有效的求最小化J、K激励函数的方法,对简化时序电路结构具有实用意义.     

主从型D触发器中短路功耗的研究

在对主从型D触发器分析短路功耗的基础上，本文提出了一种使D触发器工作在两个有一定相位差的时钟下以减少D触发器短路功耗的方法，模拟结果证明了该方法的有效性。     

Synthesis of (4R)-Methylnonan-1-ol and (4R,8RS)-Dimethyldecanal from (S)-(+)-3,7-Dimethyl-1,6-octadiene

Optically active (4R,8RS)-dimethyldecanal, an analog of the aggregation pheromone of the flour beetles Tribolium confusum and T. Castaneum, and (4R)-methylnonan-1-ol, the sex pheromone of the yellow mealworm Tenebrio molitor L., are synthesized using ozonolytic transformation of (6R,10)-dimethyl-9-undecen-2-one to (6R)-methyl-9-hydroxynonan-2-one in the key step. The starting compound is available as enantiomerically enriched (ee ~50%) (S)-(+)-3,7-dimethyl-1,6-octadiene.     

Raman light scattering,infrared absorption and neutron scattering studies of the phase transition and reorientational dynamics of H2O ligands and ClO4↙ anions in [Ca(H2O)4](ClO4)2

Vibrational-reorientational dynamics of H₂O ligands and ClO₄^↙ anions in the high-, intermediate- and low-temperature phases of [Ca(H₂O)₄](ClO₄)₂, detected previously by differential scanning calorimetry (DSC) method, were investigated. The following experimental methods were applied to achieve the goal: middle-infrared (FT-MIR), Raman spectroscopy (RS) and inelastic incoherent neutron scattering (IINS). FT-MIR and RS spectra versus temperature show distinct changes in full-width-at-half-maximum (FWHM) of some bands connected with vibrational modes of ClO₄^↙ and [Ca(H₂O)₄]²⁺ ions. It suggests that in the high temperature phase these ions (and also the ligands from complex cation) perform fast (picoseconds correlation time scale, which is characteristic for optical spectroscopy) stochastic reorientational motions, however in the lower temperatures the speed of these motions is slowed down. Moreover, the splitting of some bands accompanying the observed phase transitions. The comparison of the results obtained by these complementary methods was made. Additionally, IR, RS and IINS spectra were calculated by the DFT method and an excellent agreement with the experimental data was obtained using CASTEP plane-wave periodic boundary condition code. The bands were assigned based on analysis of the phonon eigenvectors obtained from CASTEP calculations.     

基于C#的交流异步电机测试与分析系统开发

针对电机出厂前需进行测试分析这一情况,利用C#语言,开发了一套交流异步电机测试与分析系统。首先,介绍了系统总体结构;其次,给出了系统通讯设计,详细说明了西门子S7-1200PLC与上位机的以太网通讯,及与各测试仪表之间的RS485通讯的具体实现方式;然后根据国标GB/T1032-2012,开发了交流异步电机测试与分析系统,给出了系统功能和数据库设计方法;最后通过测试实例,说明了该系统的实用性和有效性。