微波法合成反—丁烯二酸二甲酯

微波法合成反—丁烯二酸二甲酯刘福安，李耀光，徐文国，宋艳秋（吉林大学化学系长春１３００２３）关键词微波辐射，酯化反应，反—丁烯二酸二甲酯，合成反—丁烯二酸二甲酯是一种新型食品防腐剂，具有低毒、高效、广谱抗菌的特点，对霉菌且有特殊抑制作用，其性能优于丙...     

Switchable Enzyme/DNAzyme Cascades by the Reconfiguration of DNA Nanostructures

Mimicking cellular transformations and signal transduction pathways by means of biocatalytic cascades proceeding in organized media is a scientific challenge. We describe two DNA machines that enable the “ON/OFF” switchable activation and deactivation of three‐component biocatalytic cascades. One system consists of a reconfigurable DNA tweezers‐type structure, whereas in the second system the catalytic cascade proceeds on a switchable DNA clamp scaffold. The three‐component catalytic cascades consist of β‐galactosidase (β‐Gal), glucose oxidase (GOx), and the K⁺‐ion‐stabilized hemin‐G‐quadruplex horseradish peroxidase (HRP)‐mimicking DNAzyme. The hemin‐G‐quadruplex‐bridged closed structure of the tweezers or clamp allows the biocatalytic cascades to operate (switched “ON′′), whereas separation of the hemin‐G‐quadruplex by means of 18‐crown‐6‐ether opens the tweezers/clamp structures, thus blocking the catalytic cascade (switched ”OFF“). This study is complemented by two‐component, switchable biocatalytic cascades composed of GOx and hemin‐G‐quadruplex assembled on hairpin‐bridged DNA tweezers or clamp nanostructures.     

聚环卤代苯乙烯-二乙烯苯强酸性阳离子交换树脂的热稳定性

合成了一系列聚邻、间、对位卤代苯乙烯-二乙烯基苯强酸性阳离子交换树脂,研究了树脂在170℃水中的磺酸基热降解规律.结果表明,树脂的热稳定性次序为对氯苯乙烯树脂＞对溴苯乙烯树脂＞对氟苯乙烯树脂;邻氯苯乙烯树脂＞对氯苯乙烯树脂＞间氯苯乙烯树脂;邻氯苯乙烯树脂100h热降解率小于14.0%,降解速率为0.0028%/h,其热稳定性为最好.     

Synthesis of 3‐Aryl‐2,5‐Dihydro‐1‐Benzoxepines from Phenol via Ring‐Closing Metathesis

In this paper, the synthesis of 3‐aryl‐2,5‐dihydro‐1‐benzoxepines is described. While the reaction was started from phenol and based on the sequential reactions such as Claisen rearrangement, O‐alkylation, Wittig reaction, and ring‐closing metathesis (RCM), a series of new 3‐aryl‐1‐benzoxepines were prepared in good overall yields.     

La0.6Pr0.05Fe11.5-xCoxSi1.5合金的磁性和磁热效应

使用电弧炉熔炼法制备La0.6Pr0.05Fe11.5-xCoxSi1.5(x=0,0.1,0.2,0.3,0.4,0.5和0.6)系列合金.XRD分析与SEM成分分析表明该系列合金中除含有少量富镧相(P4/nmm)和α-Fe相外.均由NaZh13型立方结构单相组成.品格常数随着Co含量的增加基本保持不变.磁性测量表明该系列合金的Tc随着Co含母的增加旱线性增加,当x=0.6时,Tc达264 K.合金的升、降温磁化曲线随着Co含量的增加逐渐重合,即表明该系列合金的热滞随着Co含量的增加而减小;利用Maxwell方程计算得出在x=0时,合金在△B=1.5 T的外磁场下-△Sm达到38.4 J·kg-1·K-1.这种磁熵变来源于外磁场引起的一级相变,随着Co含量的增加-△Sm线性减小,这是由于Co含量的增加使合金的磁相变出现由一级相变向二级相变转变.     

关于A_(ai)-B_(bj)型缩聚物网络结构的研究(Ⅰ)——溶胶凝胶分配理论

本文考虑了分子内环化反应对溶胶凝胶分配的影响,用新的方法推导了包含各种反应参数的理论方程。以聚酯为模型化合物的实验结果支持本文所得到的理论结果。     

苯环硝基取代的苯乙烯型强碱阴离子交换树脂的合成及应用

将季铵型阴离子交换树脂(S210)直接硝化,并将其转型为碳酸氢根型应用于催化环氧乙烷(EO)水合反应。对树脂硝化前后的性能进行了考察,结果表明,硝化后树脂(N210)具有较好的热稳定性,在温度75℃、压力1.0MPa、空速1.0h-1、n(H2O):n(EO)=6条件下,催化剂连续运行980h,EO转化率由硝化前的89.8%提高到99.9%,乙二醇(EG)选择性由94.2%提高到95.6%,强碱交换容量损失率降低了51%。     

Self‐Assembly of Gold Nanoparticles/Electroactive Polyelectrolyte Multilayer Films for Tunable Electrocatalysis

This study described fabrication, characterization, and application of multilayer films based on layer‐by‐layer assembly of ferrocene poly(ethylenimine) and gold nanoparticles. Assembly process of the multilayer film was investigated by atomic force microscopy, UV‐visible absorption spectroscopy and electrochemical impedance spectroscopy. The multilayer films exhibited a pair of well‐defined redox peaks as revealed by cyclic voltammetry, as well as bifunctional and fine‐tunable electrocatalysis for oxidation of ascorbic acid and reduction of oxygen. Both the outer layer and layer number had effect on the electrocatalytic response. Electrocatalytic activity of the films could be controlled with assemblies at the nanoscale level by simply adjusting deposition cycles or amount of component in the films.     

Improvement on mixed-potential type ammonia sensor by a Cr2O3 gas-phase catalyst layer

Journal of Solid State Electrochemistry - Mixed-potential type ammonia sensors based on yttria-stabilized zirconia are promising devices in NOx reducing system for high-temperature exhaust....     

反相液相色谱中同系物保留值与常沸点的交点规律

研究指出,反相液相色谱中同系物的容量因子对数lnk'与常沸点的直线关系在不同流动相组成下有一共同交点,此交点规律可用如下交点方程描述: lnk'-lnk_0'=B_1(t_b-t_b~0) 利用最优化求极值法求出九组同系物在三种色谱柱上四类流动相的交点常数。按交点方程预测同系物中所有成员的容量因子,488个数据点的绝对平均误差为2.4%。