An efficient electrochemical disinfection of E. coli and S. aureus in drinking water using ferrocene–PAMAM–multiwalled carbon nanotubes–chitosan nanocomposite modified pyrolytic graphite electrode

This work reported an efficient electrochemical treatment for drinking water disinfection using a pyrolytic graphite electrode modified with ferrocenyl tethered poly(amidoamine) dendrimers–multiwalled carbon nanotubes–chitosan nanocomposite. The influence parameters of electrochemical disinfection of Escherichia coli and Staphylococcus aureus, such as applied potential and sterilization time, were investigated. Further investigation indicated that almost all (99.99 %) of the initial bacteria were killed after applying a low potential of 0.4 V for 10 min. During the electrochemical disinfection process, the oxidized form of ferrocene was formed on electrode, which played a key role in the disinfection towards E. coli and S. aureus. Hence, the proposed method may provide potential application for the disinfection of drinking water.

钯催化芳基乙炔对氧/氮杂苯并降冰片烯开环反应研究

过渡金属催化的碳亲核试剂对氧/氮杂苯并降冰片烯的开环反应是合成氢化萘衍生物的有效方法之一. 在该类反应中, 采用末端炔烃作为碳亲核试剂在反应操作、底物适用范围等多个方面都具有已报道的各种有机金属亲核试剂所不具备的优势. 目前, 对末端炔烃与氧/氮杂苯并降冰片烯的开环反应的研究进展有限, 只有Ni(dppe)Cl₂/ZnCl₂/Zn和手性的Rh两种催化体系被应用到该类反应当中, 但都面临一些不足. 为该类反应开发简单有效的新型催化体系仍然具有重要的意义和价值. 我们通过研究发现: PdCl₂与Xantphos的配合物是芳基乙炔对氧/氮杂苯并降冰片烯亲核开环反应的有效催化剂. 在优化后的反应条件下, 该Pd催化剂具有良好的催化活性和底物适应能力, 能够实现各种取代的芳基乙炔对氧/氮杂苯并降冰片烯的亲核加成, 并以较好的收率生成目标开环产物.     

庚酸甲酯高温燃烧化学动力学机理的系统简化和分析

采用详细化学反应动力学机理的系统简化方法, 对庚酸甲酯高温燃烧化学动力学机理进行了系统简化. 首先采用两步直接关系图法(Directed relation graph method, DRG)和主成分分析(Principle component analysis, PCA)方法对由1087个物种、4592步可逆反应组成的庚酸甲酯燃烧的详细机理进行框架简化, 得到了包含108个物种, 547步基元反应的框架机理. 在此框架机理基础上, 进一步采用计算奇异值摄动法(Computational singular perturbation, CSP)对框架机理进行时间尺度分析, 再选取30个准稳态物种, 采用准稳态近似(Quasi steady state approximation, QSSA)方法构建了包含78个物种、74步总包反应的全局简化机理. 模拟结果表明, 在较宽的参数范围内, 框架机理和全局简化机理均能重现庚酸甲酯高温燃烧时的点火延迟、物种浓度分布和熄火等燃烧特性. 此外, 基于框架机理阐明了庚酸甲酯高温燃烧的反应路径和对点火有重要影响的基元反应. 与详细机理相比, 框架机理保留了良好的精确性和全局性, 可以很好地反映庚酸甲酯的燃烧特性, 有助于对生物柴油的燃烧过程的理解.     

Evaluating a four-directional benzene-centered aliphatic polyamine curing agent for epoxy resins

A four-directional benzene-centered aliphatic polyamine, MXBDP, with high functionality and low volatility, is used to cure epoxy resin (DGEBA). Herein we originally report the isothermal cure kinetics and dynamic mechanical properties of DGEBA/MXBDP. Differential scanning calorimetry confirms that MXDBP is more reactive than commercial linear metaxylenediamine and branched Jeffamine T-403 and the isothermal curing reaction is autocatalytic. The Kamal model is found to be able to well describe the curing rate up to the onset of diffusion control, and the excellent match over the whole conversion range is achieved using the extended Kamal model. Interestingly, the isoconversional kinetic analysis indicates that the effective reaction activation energy (E _α ) changes substantially with conversion, and ultimately decreases to a very small value (<10 kJ mol^?1) because of the diffusion-controlled reaction kinetics. Then, dynamic mechanical analysis reveals that DGEBA/MXBDP exhibits the higher α- and β-relaxation temperatures and the much higher crosslink density than DGEBA/metaxylenediamine. Our experiment results support that MXBDP has the high reactivity and improved thermal resistance in combination with the advantages of the high functionality, low volatility and decreased CO₂ absorption. Therefore, MXBDP may be especially suitable for room temperature-cure epoxy coatings and adhesives.     

双亲聚合物分子印迹自组装胶束电化学传感器研究

结合大分子自组装和分子印迹技术制备了分子印迹聚合物胶束, 并通过电沉积将其固载到电极表面得到分子印迹电化学传感器. 首先以甲基丙烯酸二甲氨基乙酯(DMA)、丙烯酸羟乙酯(HEA)、丙烯酸二异辛酯(EHA)和苯乙烯(St)合成了共聚物poly(DMA-co-HEA-co-EHA-co-St), 在其侧链接枝上双键得到可光交联的双亲共聚物. 以水为沉淀剂诱发该双亲共聚物在含有对乙酰氨基苯酚的溶液中自组装, 得到印迹有对乙酰氨基苯酚的聚合物胶束, 利用动态激光光散射(DLS)和透射电镜(TEM)表征其尺寸和形貌. 最后通过电沉积技术诱导印迹胶束在金电极表面组装, 经紫外光辐照交联后, 洗脱模板分子形成分子印迹膜, 制备了对乙酰氨基苯酚分子印迹传感器, 通过循环伏安法、差分脉冲溶出伏安法研究此印迹传感器的性能. 实验结果表明, 该传感器对对乙酰氨基苯酚具有良好的选择性和灵敏度, 浓度响应线性范围为1×10^{-6 到4×10-3 mol/L, 检测限为3.3×10-7 mol/L.}     

组氨酸、组胺醇和组胺钴(Ⅱ)配合物氧合性能的比较研究

本文用UV-Vis光谱和氧电极法对结构相似的His-Co、Hio-Co、Hit-Co 3组配合物氧合性能进行了对比研究。由配合物光谱随pH变化的A-pH曲线,可知3组配合物均在pH 6.0以后开始发生氧合反应,在pH 6.0～10.0的范围内His-Co有2种氧合物种生成,其他2组配合物均只有1种氧合配合物生成。用等摩尔比法对氧合配合物的组成比进行了测定,得知Co∶His与Co∶Hio的配位比为1∶2,而Co∶Hit为1∶3;在室温水溶液中和pH 7的条件下,用UV-Vis在波长384 nm下分别考察了3组配合物的氧合性能和它们的抗老化能力,结果表明3组配合物在室温水溶液中均可发生氧合反应,但氧合性能有很大差异,His-Co经过110 h累计560次可逆循环,仍然具有5%氧合性能,而Hio、Hit分别经过59次/54 h、5次/10.2 h循环后氧合性能衰减至5%。3组配合物的抗老化能力的大小顺序为:His-Co>>Hio-Co>Hit-Co。研究结果初步说明:三配位原子配体配合物的可逆吸氧性能好于二配位原子配体的配合物,氨基酸配合物优于氨基醇配合物。     

微波处理和溶胶凝胶法共同改性废胶粉及其与天然橡胶复合材料性能的研究

采用微波处理打断废胶粉(WRP)的三维网状结构用来提高WRP在有机溶剂中的溶胀性,然后采用溶胶凝胶法,将微波改性后的WRP浸入正硅酸乙酯中,通过水解反应和缩合反应,在WRP表面原位生成SiO2网络,从而制得改性废胶粉(MWRP).将制得MWRP与天然橡胶(NR)共混,制备了NR/MWRP复合材料,研究了NR/MWRP复合材料的性能.通过热重分析仪、差示扫描量热仪和力学分析表明微波处理最佳时间是20 s.由于微波处理提高了NR与WRP的相容性,原位生成的SiO2粒子起到了补强作用,所以所制备的NR/MWRP复合材料拥有较好的力学性能;随着Si69的加入,抑制了SiO2粒子聚集,提高了SiO2粒子的分散性,从而进一步提高复合材料的力学性能并降低复合材料的Payne效应;在进行频率扫描时,硫化胶的储存模量随频率的增大而增大;硫化胶的温度扫描结果表明,随着温度的升高,复合材料中SiO2粒子聚集程度加剧并且复合材料出现老化的现象.为了提高复合材料的耐老化性能,N,N-间苯撑双马来酰亚胺(BMI)作为一种防老剂加入复合材料中,BMI利用Diels-Aider反应补偿橡胶在老化过程中所损失的交联键并提高NR与WRP的界面相容性,从而提高复合材料的耐老化性能.     

含环糊精链节的拓扑高分子

星形、超支化、树枝状、刷状等具有支化拓扑结构的高分子通常具有不同于直链结构高分子的优异性能。将有客体包合功能的环糊精与其结合构筑环糊精拓扑高分子体系,有望在分子识别、基因传输、药控释放等领域得到应用。本文根据高分子拓扑形态的不同,从星形、超支化、树枝状以及其他拓扑形态环糊精聚合物的合成及自组装构筑等方面进行了总结和评述,并在此基础上展望了基于环糊精的拓扑高分子的研究方向和发展趋势。     

Evaluation of measurement uncertainty in EA–IRMS: for determination of δ 13C value and C-4 plant sugar content in adulterated honey

In this study, the method for determining the stable carbon isotope ratio value was validated. Measurement uncertainty of stable carbon isotope ratio value of whole honey and its extracted protein derived from repeatability, reference gas, reference standards and calibration curve was calculated by applying the “bottom-up” approach according to Eurachem/CITAC guide. The expanded uncertainties for all results ranged from 0.14 to 0.19 ‰, with most of them between 0.15 and 0.16 ‰ (the coverage factor k = 2, the level of confidence p is approximately 95 %). The percentage contribution of each source to the relative combined uncertainty was calculated. The data indicated that calibration curves have more contribution to the relative combined uncertainty than repeatability and reference standards. On the other hand, the measurement uncertainty of C-4 sugar content in honey was estimated. Based on these results, 58 honey samples, such as acacia, chaste, Northeast China black bee, flowers and jujube honey, have been gathered to determine the C-4 plant sugar content adulteration in honey by elemental analyzer with an isotope ratio mass spectrometer. It can be found that all honey samples were not adulterated by C-4 plant sugar.