N-3烷基取代嘧啶及其衍生物的合成

在室温条件下,经过三步反应,合成了一系列N-3烷基取代的嘧啶类化合物.该方法具有条件温和、操作简便、反应时间短、产率高等特点.目标产物经过了1HNMR,13C NMR和MS确证表征.     

N掺杂和氧空位对PbTiO3电子结构和导电性的影响研究

用第一性原理计算了P型N掺杂PbTiO3的电子密度差分、能带结构和态密度,讨论了氧空位对N掺杂PbTiO3性能的影响。在PbTiO3中掺杂N杂质后,PbTiO3的价带向高能级发生移动,费米能级进入价带顶部,带隙变窄,N掺杂PbTiO3表现出典型的P型半导体性能。当N掺杂PbTiO3中含有氧空位时,导带发生下移,受主被完全补偿。计算结果与实验数据相吻合。     

基于ZigBee的煤层气录井红外甲烷监测系统设计

针对传统煤层气录井系统中采用老式传感器和有线网络对煤层气甲烷含量进行监测实时性差和精度不高等问题,该文设计一种红外甲烷技术和ZigBee无线传输技术相结合的新型煤层气甲烷监测系统。该系统以MSP430F449单片机和CC2430芯片为核心,采用ZigBee无线通信协议。其可实时采集传输甲烷含量数据,具有稳定性高,拓展能力强,精度高,实用性强等优点。     

气质联用法测定电视外壳中十种多溴二苯醚

建立了电视机外壳样品中10种多溴二苯醚的微波萃取-气质联用测定方法。10种多溴二苯醚的定量峰面积与其浓度在一定范围内成线性关系,检出限从0.08μg/m L到0.60μg/m L。采用索氏萃取法进行方法验证,测试结果的RSD≤2.83,两种方法经t检验无显著性差异。该方法具有简便、快速、试剂消耗量少的优点,可应用于电视机等国推污染控制认证产品塑料材料中多溴二苯醚测定。     

Synthesis and Properties of Poly(Aryl Ether Ketone) Copolymers with Trifluoromethyl‐Substituted Benzene in the Side Chain

The new monomer (4‐(4′‐trifluoromethyl)phenoxyphenyl)hydroquinone (TFPOPH) was synthesized in a three‐step synthesis. A series of poly(aryl ether ketone) copolymers were prepared by the reaction of (4‐(4′‐Trifluoromethyl)phenoxyphenyl)hydroquinone and hydroquinone (HQ) with 4,4′‐difluorobenzophenone (DFB) in the presence of potassium carbonate in tretramethylene sulfone (TMS). Thermal analyses of the fluorinated copolymers showed that the glass transition temperature and 5.0% weight loss temperature are similar with that of PEEK, and the crystallinity decreased with increasing of TFPOPH. For the copolymer synthesized with the molar fraction of TFPOPH in the diphenol monomers (TFPOPH, HQ) being over 0.2, no cold crystallization temperature and melting temperature were detected, indicating that these copolymers are almost amorphous. The crystal structure of the copolymers with the molar fraction of TFPOPH being not higher than 0.2 is rhombic. The solubility in polar aprotic solvents of poly(aryl ether ketone)s copolymers increases and dielectric constant decreases step by step.     

Synthesis of Main‐Chain Liquid‐Crystalline Polyesters Containing Diphenyl Mesogens by Chemo‐Enzymatic Route †

Main‐chain thermotropic liquid‐crystalline polyesters containing rigid biphenyl mesogens and flexible spacers were synthesized by chemo‐enzymatic route. The enzyme‐catalyzed polymerization showed high regio‐ and chemo‐ selectivity, and is environmentally friendly. The resulting polyesters were characterized with ¹H‐NMR, ¹³C‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and polarized light optical microscopy (POM).     

Cloning,Heterologous Expression,and Characterization of the Gene Cluster Required for Gougerotin Biosynthesis

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Highlights? The complete gougerotin biosynthetic gene cluster is cloned ? Heterologous production of gougerotin is accomplished in S. coelicolor M1146 ? Biosynthetic pathway is proposed based on bioinformatics, genetic, and chemical analyses ? Preliminary data support an uncommon enzymatic reaction for peptide bond formation