A general,enantioselective synthesis of 2-substituted thiomorpholines and thiomorpholine 1,1-dioxides

In the course of our drug discovery programs, we had need to access chiral, 2-substituted thiomorpholines and their oxidized congeners, thiomorpholine 1,1-dioxides. Here, we disclose a high-yielding, general protocol for the enantioselective synthesis of C2-functionalized thiomorpholines and thiomorpholine 1,1-dioxides.     

浅谈低压供电系统的几种供电方式

简要介绍了TT系统、TN系统、IT系统3种供电系统的特点及适用范围，并进行了综合比较。     

多孔混凝土水质净化性能

设计制作了多孔混凝土水质净化试验装置,对5种不同粗骨料粒径和空隙率的多孔混凝土进行了水质净化性能试验.附着在多孔混凝土表面的生物体的数量可间接地通过溶解氧(DO)的消耗量来检测.多孔混凝土的水质净化性能可通过总磷(TP)和总氮(TN)的去除量进行评价.试验结果表明:多孔混凝土在水中具有富集营养物质,使生物膜附着生长其上的效应;采用10～20mm粒径的集料所制备的空隙率为25%的多孔混凝土其水质净化效果最佳.     

基于优选波长的复合肥总氮含量可见/近红外光谱分析

利用可见/近红外光谱分析仪得到复合肥的原始光谱,经过MSC和一阶导数预处理后,建立了复合肥中总氮含量的PLS模型,实现了复合肥中总氮含量的快速准确无损测量。通过选取不同范围波长建模,取得了预测决定系数（R²）、预测标准差（S_RMSEP）、相对分析误差（K_RPD）最好的基础波段。在基础波段的基础上,采用优选波长算法,获得了加入波长后的模型的预测决定系数和预测标准差图。通过分析,最终确定加入42个优选波长。实验结果表明,加入优选波长后的模型的预测决定系数由不加优选波长模型的0.760 4提高到了0.991 1,S_RMSEP降低为原来的1/5,K_RPD提高到原来的5倍。     

TOC／TN仪快速测定环境水样中的总氮

采用TOC／TN法测定了环境水样中的总氮。结果表明：其线性范围为0-20mg/L时,具有良好的线性关系,精密度RSD小于2％,对方法的回收率作了试验,所得结果在85．3％—99．1％之间。     

赣南脐橙果园土壤全氮和有机质近红外漫反射光谱检测

选取赣南脐橙果园土壤作为研究对象,探讨在4 000～7 500 cm-1范围内的光谱分析土壤全氮和有机质的可行性。采集的近红外光谱采用多元散射校正、一阶微分、二阶微分、七点平滑等多种预处理对比分析,分别建立了有机质和全氮含量偏最小二乘模型。实验得出全氮预测模型在4 000～7 500 cm-1范围内采用七点平滑(SG)进行预处理模型较为理想,校正集相关系数(r_c)为0.802,校正均方根误差(RMSEC)为2.754,预测集相关系数(r_p)为0.715,预测均方根误差(RMSEP)为3.077;有机质预测模型在4 000～7 500 cm-1范围内采用标准正态变量变换(SNV)预处理模型较为理想,r_c为0.848,RMSEC为0.128,r_p为0.790,RMSEP为0.152。研究表明近红外漫反射光谱可快速用于赣南脐橙果园的土壤中全氮和有机质含量的快速检测。     

Introducing efficient palladium catalyzed cross coupling reaction of tertiary alcohols and aroyl chlorides for the synthesis of highly substituted esters

Esters are chemical compounds with many practical uses. The common type of esterification is called the Fischer esterification. Another one is by the action of acid chlorides on alcohols but not with tertiary alcohols. The stable carbenium ions formed from tertiary alcohols favor elimination and the byproduct, hydrogen chloride prevents ester formation. In this new report, palladium inserted ArCOPdCl species reacts with tertiary alcohols and cross-coupling under microwave heating, minimizes the formation of probable carbenium ion, and promotes successful production of highly substituted esters in good to high yields.     

Total synthesis of violaceimides A–E and consideration of the reported stereochemistry

Here we report the first total synthesis of violaceimides A–E, a family of sulfur-containing metabolites from Aspergillus violaceus, a sponge-associated fungus. A concise, convergent and enantioselective synthesis was developed for all five family members, from a common advanced intermediate. However, while the NMR spectral data matched that of the reported natural products, the optical rotations were of opposite sign. This result prompted the enantioselective synthesis of all four diastereomeric pairs of violaceimide E, and suggests that the stereochemistry might have been misassigned.     

5.4 Properties and applications of cellulose triacetate film

The CTA film can be characterized by e.g. its relatively high moisture regain, significantly low birefringence, and moderate mechanical strength. Having been commercialized more than fifty years ago, it has been widely used as photographic film, protective film for polarizing plate, and optical compensation film for liquid crystal display (LCD). The photographic film application exploits the optical isotropy and unique physical properties of the CTA film. In the application of the CTA film to protective film for polarizing plate, its low in-plane birefringence is of particular importance. In the optical compensation to enhance the viewing angle of LCD, the CTA film, because of its moderate retardation in thickness direction (Rth), serves as an element of compensator as well as a base film. Considering the growth of the LCD market, the demand for CTA film is believed to be further expanding.