Lab-on-valve (LOV) system coupled to irreversible biamperometric detection for the on-line monitoring of catechol

The analytical performance of lab-on-valve (LOV) system using irreversible biamperometry for the determination of catechol was evaluated. By integrating miniaturized electrochemical flow cell (EFC) designed and processed which is furnished with two identical polarized platinum electrodes, into the LOV unit, the lab-on-valve system combines sampling with analysis, realizing automated on-line analysis for catechol in a closed system. The biamperometric detection system was established to record the relationship between oxidation current and time by coupling the irreversible oxidation of catechol at one pretreated platinum electrode with the irreversible reduction of platinum oxide at the other pretreated platinum electrode. Factors influencing the analytical performance were optimized, including the potential difference (ΔE), buffer solution and pH, and flow variables in the LOV. A linear calibration curve was obtained within the range of 1.0 × 10⁻⁶-5.0 × 10⁻⁴ mol L⁻¹ of catechol with the detection limit (3σ) of 5.09 × 10⁻⁷ mol L⁻¹. The relative standard deviation (R.S.D.) was 2.39% for 11 successive determinations of 1 × 10⁻⁵ mol L⁻¹ catechol and the sample throughput was 35 h⁻¹. Moreover, this proposed method was applied to the analysis of catechol in beer sample, which was testified by high-performance liquid chromatography (HPLC).     

On-resin cyclization and antimicrobial activity of Laterocidin and its analogues

Total synthesis of cyclodecapeptide antibiotics from Bacillus laterosporus, laterocidin and its analogues, was accomplished for the first time by solid-phase peptide synthesis followed by traceless on-resin cyclization of the linear precursors with protection of α-carboxyl group on the Asp residue by Dmab as a temporary blocking group for on-resin head-to-tail cyclization, in which the carboxyl group of side chain of Asp was linked to Rink resin. Single alanine substitution or Asn substitution (Asp¹⁰→Asn¹⁰) demonstrated improvements in antibacterial activity. Of note, d-Phe² and Pro⁴ play an important role in on-resin head-to-tail cyclization and exerting antibacterial activity of Laterocidin.     

可生物降解聚酯P(DHCA-co-LA)的合成与表征

由3,4-二羟基肉桂酸(DHCA)与D,L-乳酸(LA)经熔融缩聚法得到了新型可生物降解聚酯P(DHCA-co-LA),采用傅立叶变换红外(FTIR),核磁共振(1H-NMR)和凝胶渗透色谱(GPC)对该共聚物的组成与相对分子量进行表征,结果表明其结构明确.改变DHCA与LA单体的配比,得到的P(DHCA-co-LA)的分子量和分子量分布在同一数量级.通过差示扫描量热仪(DSC)、紫外(UV)和荧光光谱研究了共聚物的热性能、紫外与荧光性能,结果表明,P(DHCA-co-LA)有明显的玻璃化转变温度(Tg),随LA的投料比从0增加至50 mol%时,其Tg从132.26℃下降至99.12℃;当LA的投料比为20 mol%时,所得到的聚酯型共聚物溶液呈现最强的荧光强度;在紫外光照下,共聚物可进行环加成反应,但交联度总体较低;紫外光照65 min后,在荧光显微镜下观察到交联颗粒形态稳定、有较强的荧光.X-射线衍射(XRD)测定结果显示,由结晶性DHCA和LA共聚形成的P(DHCA-co-LA)为无定形聚合物,有利于生物降解.共聚物在土壤中的降解实验表明,其降解速度随体系中LA含量的增加而减缓.     

Molecularly imprinted photo-sensitive polyglutamic acid nanoparticles for electrochemical sensing of hemoglobin

Microchimica Acta - A voltammetric sensor for hemoglobin (Hb) was prepared from molecularly imprinted polymer nanoparticles (MINPs) via electrophoretic deposition. A photo-sensitive copolymer...     

硫杂蒽酮类光产碱剂的合成及其光化学性能研究

以硫代水杨酸和苯硫乙酸为原料,通过两步法成功合成了一种新型的单组分硫杂蒽酮类光产碱剂。利用核磁氢谱、核磁碳谱和高分辨率质谱对光产碱的结构进行了表征,通过稳态光解及电子自旋共振波谱等对光解产物进行了系统研究。该光产碱剂在400nm附近有较强的吸收,可有效引发巯基-环氧光聚合,其引发活性优于文献报道的高效光产碱体系。     

气相色谱-质谱联用法测定塑料产品中的溴系阻燃剂

溴系阻燃剂是目前全世界范围内使用的主要阻燃剂,常用的有十溴联苯醚、四溴双酚A、四溴双酚A-双(2,3-二溴)丙醚、六溴环十二烷、三溴苯酚、十溴联苯乙烷等。溴系阻燃剂的分解温度大多在200~300℃左右,与各种高聚物的分解温度匹配,因此能在最佳时刻以气相及凝聚相同时起到阻燃作     

Purification of 2,6-Diisopropylnaphthalene by Static Melt Crystallization from a Mixture Containing Diisopropylnaphthalene Isomers

2,6-Diisopropylnaphthalene （2,6-DIPN）, as the precursor of important monomer 2,6-naphthalene dicarboxylic acid, could be produced by the shape-selective isopropylation of naphthalene with propene resulting in an isomeric mixture having different alkylation levels. Since the boiling points of DIPNs were very close and the differences of melting points in-between isomers were quite distinctive, the static melt crystallization was applied to separate and purify 2,6-DIPN from its isomers. 2,6-DIPN with purity ≥99% was produced through a process of three stages： crystallization→sweating→melting. The phase diagram of 2,6-DIPN-2,7-DIPN binary system was plotted to opti- mize the temperature control of crystallization. By repeated crystallization of melts with different concentration levels, the yield of pure 2,6-DIPN could be enhanced to 87%. No solvent was necessary. Keywords 2,6-diisopropylnaphthalene, static melt crystallization, crystallization rate, sweating rate, eutectic temperature     

Au/p-CZT晶体的光致发光以及电学性能研究

对比了CZT晶片经腐蚀与钝化表面处理的PL谱,结果表明NH4F/H2O2作为CZT晶体表面钝化剂,钝化后CZT晶体表面陷阱态密度减小到最低程度,同时减小了与Cd空位复合有关的深能级杂质浓度。用Agilent 4339B高阻仪进行CZT晶片I-V特性测试以及Agilent 4294A高精度阻抗分析仪进行CZT晶片的C-V特性测试,结果表明钝化均能不同程度提高Au/p-CZT接触的势垒高度,减小了漏电流。主要原因是在CZT表面钝化生成的TeO2氧化层增加接触势垒高度,并减小了电荷因隧道效应而穿过氧化层的几率。     

关于有限群的p-超可解性

本文研究了有限群的p-超可解性,利用子群的s-条件置换性及Sylow子群的极大子群对有限群结构的影响,得到了一个群为p-超可解群的一些充分必要条件.