Gas chromatography-mass spectrometry analysis of di-n-octyl disulfide in a straight oil metalworking fluid: application of differential permeation and Box-Cox transformation

The aim of this study was to identify and quantify an unknown peak in the chromatogram of a very complex mixture, a straight oil metalworking fluid (MWF). The fraction that permeated through a thin nitrile polymer membrane had less mineral oil background than the original MWF did at the retention time of the unknown peak, thus facilitating identification by total ion current (TIC) gas chromatography-mass spectrometry (GC-MS). The peak proved to be di-n-octyl disulfide (DOD) through retention time and mass spectral comparisons. Quantitation of DOD was by extracted ion chromatogram analysis of the DOD molecular ion (mass-to-charge ratio (m/z) 290), and of the m/z 71 ion for the internal standard, n-triacontane. Linear models of the area ratio (y) of these two ions versus DOD concentration showed a systematic negative bias at low concentrations, a common occurrence in analysis. The linear model of y(0.8) (from Box-Cox power transformation) versus DOD concentration showed negligible bias from the lowest measured standard of 1.51 mg/L to the highest concentration tested at 75.5 mg/L. The intercept did not differ statistically from zero. The concentration of DOD in the MWF was then calculated to be 0.398+/-0.034% (w/w) by the internal standard method, and 0.387+/-0.036% (w/w) by the method of standard additions. These two results were not significantly different at p < or = 0.05. The Box-Cox transformation is therefore recommended when the data for standards are non-linear.     

Copper‐Catalyzed Direct C Arylation of Heterocycles with Aryl Bromides: Discovery of Fluorescent Core Frameworks

A window of opportunity : A general copper‐catalyzed C? H bond‐activation path allows arylation of heterocycles with a wide range of aryl bromides (see scheme). The reaction shows excellent regioselectivity and exhibits good functional group tolerance. The 8‐aryl xanthines exhibit fluorescence in a variety of solvents and show promise as reagents for biological imaging.

     

Facile synthesis of 1-aminoisoquinolines via the tandem reactions of 2-alkynylbenzaldoximes with isothiocyanates

A new, concise, and efficient route for the synthesis of 1-aminoisoquinolines in good to excellent yields is described; this involves the reaction of 2-alkynylbenzaldoximes and isothiocyanates, which is catalyzed by silver triflate in dichloromethane, at room temperature. This transformation involves tandem 6-endo cyclization, [3+2] cycloaddition, and subsequent rearrangement. The simple operational protocol provides a cost-effective, diversity-oriented route to 1-aminoisoquinolines under neutral, mild conditions.     

基于神经网络的车辆抗冲击防护组件优化

随着军用车辆防护要求的不断提高,抗冲击防护组件设计面临越来越多的挑战。为了提供一种高效科学的研究方法,本文中采用V型结构,并应用径向基函数神经网络近似模型和多目标遗传算法对某型车防护组件进行优化设计。以防护组件变形量与总体质量最小为设计目标,利用灵敏度分析筛选出对防护组件防护性能影响较大的设计因子。以径向基函数神经网络构建实验设计样本的近似模型,然后用多目标遗传算法进行数值优化获得防护组件最优方案。最后通过仿真与实验验证,证明优化方案满足设计要求。研究结果可为今后防护组件开发提供设计思路。

     

高活性单分散磺化聚苯乙烯多孔微球用于生物柴油制备研究

采用回流-沉淀聚合法高效制备了单分散交联多孔聚苯乙烯微球，再在温和的条件下对其进行磺化，制备了磺化聚苯乙烯多孔微球.以调控磺化度和酸密度为目标，重点考察了溶剂用量、溶胀时间、氯磺酸用量、磺化温度和磺化时间等影响因素.用5 mL CCl₄溶胀0.5 g交联聚苯乙烯微球，然后加入0.3 mL氯磺酸，在50℃磺化75 min，磺化度和酸密度分别可以达到85.1%和2.611 mmol·g^-1.该磺化聚苯乙烯微球在催化油酸和甲醇酯化合成生物柴油中表现出很高的催化活性，远高于酸性离子交换树脂Ameberlyst-15，接近于均相的浓硫酸体系；且循环使用3次后，催化活性仍可保持初始活性的92%.提供了一种简单、绿色和可控的方法，制备了酸密度可控、稳定性好的单分散磺化聚苯乙烯微球，在工业制备生物柴油领域具有较好的前景.     

阴离子表面活性剂和β-环糊精包结作用

环糊精由于其特殊结构可与众多物质(客体分子)形成包结物,这种包结物在化学理论研究、化工工业、农业及医药等领域有广阔的应用前景[1、2],因而受到人们极大的关注.人们用电导法、核磁技术、表面张力法等研究了环糊精与阴离子表面活性剂的相互作用,但这些方法得出的结果很...     

Self‐Assembly of Amphiphilic Drug–Dye Conjugates into Nanoparticles for Imaging and Chemotherapy

An amphiphilic drug–dye conjugate ( PTX‐Pt‐BDP ) was designed and synthesized with a platinum compound as the hydrophilic head. The precursor of PTX‐Pt‐BDP was obtained under mild conditions by means of a three‐component Passerini reaction. PTX‐Pt‐BDP could self‐assemble into nanoparticles ( PTX‐Pt‐BDP NPs) in aqueous solution via a nanoprecipitation method. The obtained nanoparticles exhibited favorable structural stability in both water and physiological environment. PTX‐Pt‐BDP NPs could be endocytosed by cancer cells as revealed by confocal laser scanning microscopy and exert potent cytotoxicity. This work highlights the potential of nanomedicines from amphiphilic drug–dye conjugates for cancer cell imaging and chemotherapy.     

Pt-Ga/HZSM-5催化剂上丙烷芳构化

考察了Ｐｔ／ＨＺＳＭ－５，Ｇａ／ＨＺＳＭ－５和Ｐｔ－Ｇａ／ＨＺＳＭ－５上的丙烷芳构化反应，其中Ｐｔ－Ｇａ／ＨＺＳＭ－５双组份催化剂上有较高的丙烷反应活性和芳烃选择性，用程序升温还原（ＴＰＲ）和Ｈ２化学吸附法表征催化剂，发现Ｐｔ与Ｇａ的协同相互作用促进了Ｇａ＾３＋的还原，使其峰温向低温移动的７０℃，且双组分催化剂中Ｐｔ的Ｈ２吸附性能大大降低，使催化剂表成乙烯加氢能力降低，从而提高了产物芳烃的选择性，     

在饮水中典型溶解性有机氮酪氨酸氯化生成氯仿的机理分析

饮用水氯化消毒可以有效杀灭细菌, 但同时会产生危害人体健康的消毒副产物(DBP). DBP生成机理研究是有效控制DBP的前提. 溶解性有机氮(DON)是DBP的重要前体物, 选取典型DON-丙氨酸(Ala)、苯丙氨酸(Phe)和酪氨酸(Tyr)作为氯仿(CF)等DBP的前体物, 研究三种氨基酸(AA)的耗氯量和CF产率; 同时考察了Tyr氯化中间产物2,4,6-TCP的氯化特性和CF产率; 采用GC/MS扫描和前线轨道理论验证, 探讨了CF的主要生成路径. 研究发现, 在同等氯化反应条件下, 由于侧链基团的不同, Tyr的耗氯量以及CF产率都明显高于Ala和Phe, 从而说明Tyr确实是一种重要的CF前体物质. CF的主要生成路径为Tyr→ 4-MCP → 2,4-DCP → 2,4,6-TCP → CF. 氯胺消毒工艺可有效控制CF的生成, 并能减少2,4,6-TCP的产生, 但不能确保饮用水的生物安全性. 氯化消毒之前将Tyr等重要前体物去除可能是控制CF等DBP更加有效的措施.     

Synthesis and antibacterial activity of four natural chalcones and their derivatives

Four natural chalcones bearing hydroxyisoprenyl or prenyl groups, named Paratocarpin E (2), Xanthoangelol D (3), Angusticornin A (4) and Kanzonol C (5), were prepared by employing the Claisen-Schmidt condensation as the key step. In an attempt to investigate the effect of the hydroxyisoprenyl group on biological activity, two of their derivatives were also prepared for antibacterial activity research. The synthesized compounds were investigated for their expected antibacterial activities against Gram positive bacteria (Bacillus subtilis, Staphylococcus aureus) as well as Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa). Paratocarpin E (2) was found to be the most potent against two Gram positive bacteria while the majority of the remaining compounds showed promising activity as well. However, all of the compounds were inactive against both Gram-negative bacteria.