Separation of antipyretic analgesics by open tubular capillary electrochromatography with homopolymer coatings

This study developed an open‐tubular capillary electrochromatography protocol for the analysis of antipyretic analgesic drugs, which used a multifunctional homopolymer as coating. A controlled/living radical polymerization strategy was adopted to obtain poly(N‐acryloxysuccinimide) with a tunable chain‐length. The homopolymer coating enhanced the separation performance by contributing to the hydrophobic and hydrogen‐bonding interactions between the analytes and the homopolymer. The effect of polymer chain‐length and buffer pH and concentration on the separation efficiency was evaluated. In this approach, baseline separation of the three test drugs was achieved within 15 min. The repeatability of the prepared homopolymer coating was investigated, with the relative standard deviations < 2.88% observed in intra‐ and interday runs. Good linearity in the 5–800 µM range (R² ≥ 0.998) demonstrates that accurate quantitative analysis of real samples was achieved. Moreover, the proposed assay was used to quantify the three drugs (aminopyrine, 4‐aminoantipyrine, and phenacetin) in urine samples, achieving recovery rates between 92.1 and 108.7%. This promising methodology may be used for the analysis of drugs in real bio‐samples and for the development of unique homopolymer coatings for open‐tubular capillary electrochromatography systems.     

Sustained and Controlled Release of Volatile Precursors for Chemical Vapor Deposition of Graphene at Atmospheric Pressure

Precursors and catalysts play vital roles in chemical reactions. Considerable efforts have been devoted to the investigation of catalysts for graphene growth by chemical vapor deposition in recent years. However, there has been little research on precursors because of a lack of innovation in term of creating a controllable feeding method. Herein, we present a novel sustained and controlled release approach, and develop a convenient, safe, and potentially scalable feeding system with the assistance of matrix materials and a simple portable feeder. As a result, a highly volatile liquid precursor can be fed accurately to grow large-area, uniform graphene films with optimal properties. This feeding approach will further benefit the synthesis of other two-dimensional materials from various precursors.     

A detailed investigation into the one-pot cascade reaction of ethyl 3,9-dimethyl-7-phenyl-6H-dibenzo-[b,d]pyran-6-one-8-carboxylate with phenylhydrazine

Research on Chemical Intermediates - When synthesizing cyclohexane-annulated pyrazolones from a cyclohexonedicarboxylate derivative with phenylhydrazine under the catalysis of sulfuric acid in the...     

A Chemically Soldered Polyoxometalate Single-Molecule Transistor

Polyoxometalates have been proposed in the literature as nanoelectronic components, where they could offer key advantages with their structural versatility and rich electrochemistry. Apart from a few studies on their ensemble behaviour (as monolayers or thin films), this potential remains largely unexplored. We synthesised a pyridyl-capped Anderson–Evans polyoxometalate and used it to fabricate single-molecule junctions, using the organic termini to chemically “solder” a single cluster to two nanoelectrodes. Operating the device in an electrochemical environment allowed us to probe charge transport through different oxidation states of the polyoxometalate, and we report here an efficient three-state transistor behaviour. Conductance data fits a quantum tunnelling mechanism with different charge-transport probabilities through different charge states. Our results show the promise of polyoxometalates in nanoelectronics and give an insight on their single-entity electrochemical behaviour.     

Preparation of pillared layered antimony hydroxide and its flame retardancy in thermoplastic polyurethane

Journal of Thermal Analysis and Calorimetry - In this article, a pillared layered antimony hydroxide (Sb-LH) material has been prepared by the hydrothermal method. X-ray diffraction,...     

三维四翼广义增广Lü系统

增广Lü系统是仅含有两个控制参数的三维混沌系统,可产生一个伪四翼吸引子.利用混沌反控制方法,通过在增广Lü系统中引入一个简单的线性状态控制器,提出了一个新三维混沌系统——广义增广Lü系统.新系统实现了一个真正的具有复合结构的四翼吸引子,它包含了两个镜像对称的子系统.理论分析、数值仿真和电路实验证明了广义增广Lü系统四翼吸引子的存在性,也阐述了广义增广Lü系统有着较增广Lü系统更加丰富的动力学特性. 关键词： 广义增广Lü系统 四翼吸引子 数值仿真 电路实验     

离焦量对空气中激光诱导铜等离子体光谱特性的影响

利用Nd: YAG脉冲激光在空气中烧蚀金属Cu靶,获得等离子体光谱;采用改变离焦量的方法,研究了离焦量的变化对谱线结构及谱线强度的影响;分析了离焦量分别为1mm、0mm和-2mm时,沿靶面法线方向不同空间距离处电子温度的演化规律;并对等离子体光谱的特性和产生机制进行了讨论. 结果表明,谱线结构、谱线强度和等离子体的电子温度都与离焦量的变化密切相关,聚焦点在-2mm处CuⅠ谱线相对强度出现峰值,电子温度数值最大;聚焦点在-0.5mm和-1.0mm附近谱线相对强度遽然降低的现象是由于等离子体的屏蔽效应造成的.