Fluorescence Properties of Europium and Terbium Triundecylenate-Containing Polymers and Solutions

Europium triundecylenate, Eu(UA)₃, and terbium triundecylenate, Tb(UA)₃, were prepared by the method described in our previous paper. Either Eu(UA)₃ or Tb(UA)₃ was dissolved in methacrylic acid (<20%) and copolymerized as a crosslinker with methyl methacrylate (>80) by bulk polymerization in molds made of two glass plates. The fluorescence spectroscopy of these Eu- or Tb-containing polymers under ultraviolet/visible excitation light was investigated. The fluorescence spectroscopy of solutions of Eu(UA)₃ or Tb(UA)₃ in methacrylic acid was measured and compared with that of the solid-state Eu- or Tb-containing polymers. The fluorescence excitation and emission spectra of the solutions and polymers showed the characteristic features of free Eu³⁺ or Tb³⁺. The lifetime fluorescence of the solutions and polymers with Eu³⁺ are also included.     

A Microwave‐assisted Headspace Solid‐phase Microextraction for Rapid Determination of Synthetic Polycyclic and Nitro‐aromatic Musks in Fish Samples

Rapid solvent‐free microwave‐assisted headspace solid‐phase microextraction (MA‐HS‐SPME) coupled with gas chromatography‐mass spectrometry (GC‐MS) was developed to determine synthetic polycyclic and nitro‐aromatic musks in fish samples. Four commonly used synthetic musks, galaxolide (HHCB), tonalide (AHTN), musk xylene (MX) and musk ketone (MK) were employed in the method development and validation. The parameters (microwave irradiation time, irradiation power, amount of water addition, pH value and addition of NaCl) affecting the extraction efficiency of analytes from fish slurry were systematically investigated and optimized. The best extraction conditions were achieved when the fish sample 2‐g mixed with 4‐mL methanol and 15‐mL deionized water (containing 4 g of NaCl, pH 2.0 in a 40‐mL sample‐vial) was microwave irradiated at 80 watt for 5 min. The limits of quantification (LOQ) were 0.4 to 1.2 ng/g in 2‐g of wet tissue. The precision for these analytes, as indicated by relative standard deviations, were less than 9% for both intra‐ and inter‐day analysis. Accuracy, expressed as the mean extraction recovery, was between 80 to 92%. A standard addition method was used to quantitate these four synthetic musks, and the total concentrations ranged from 2.1 to 23.1 ng/g in various fish samples.     

Synthesis of the Novel Chiral Catalysts by Click Chemistry and Their Application

Novel cinchonine ammonium salt derivatives have been prepared by 1,3‐dipolar cycloaddition. Their chiral catalytic efficacy was investigated in the asymmetric alkylation of N‐diphenylmethyleneglycine t‐butyl ester in the water phase. As the special structure of the catalyst, its asymmetric alkylation catalytic behavior both in organic solvents and in water is satisfactory, which is environmentally friendly.     

Study on Influencing Factors of Chemical Flooding for Heavy Oil

Alkali and alkali/surfactant displacing agents are designed for two kinds of heavy oil. Results of emulsifying capacity, dynamic interfacial tension (IFT) and water-wet core flooding tests show that, although alkaline/surfactant systems exhibit better capacity in emulsification and IFT reduction, oil recovery values of alkaline/surfactant flooding are lower than those of alkaline flooding. Glass-etched micromodel tests further demonstrate that, when alkaline solution penetrates into the oil phase, water streams break into ganglia coating oil film. Water ganglia may be entrapped by narrow throats, consequently presenting a water-oil alternating slug flow. Similar water ganglia also appears in alkaline/surfactant flooding, however, water channeling along the pore surface occurs subsequently, resulting in its relatively lower oil recovery.     

RRKM理论研究N(4S)+CH2X(X=F,Cl)的反应通道

采用RRKM理论和疏松过渡态模型计算了N(4S)+CH2X(X=F,Cl)反应的微正则速率常数和通道分支比.计算结果表明,在较低的内能下(E=280.29 kJ/mol), N(4S)+CH2F的主要产物为NCHF+H,占总产物的59.2%,次要产物为H2CN+F,占37.4%.而N(4S)+CH2Cl反应在E＝267.78 kJ/mol时,主要产物是H2CN+Cl,占90.3%, NCHCl+H只占9.0%.在内能较高的时候(取E=500.00 kJ/mol), N(4S)+CH2F的主要通道并未变化,而N(4S)+CH2Cl的主要通道变为NCHCl+H,比例为51.5%, H2CN+Cl的比例降到40.4%.     

Synthesis and screening of a molecularly imprinted polymer library targeted for penicillin G

A library of molecularly imprinted polymers (MIPs) was synthesized by radical bulk polymerization using the beta-lactam antibiotic penicillin G as the template. Diversity of the library was obtained by combining various functionalized monomers and cross-linkers and by varying the stoichiometry and the concentration of the components in the prepolymerization mixtures. The library was screened for selectivity to penicillin G by a radioligand binding assay and was compared to a corresponding control library. The best MIP candidate, showing the highest selectivity for penicillin G, was prepared from methacrylic acid and trimethylolpropane trimethacrylate as the functionalized monomer and cross-linker, respectively. Cross-reactivity studies with other beta-lactam antibiotics showed a low cross-reactivity of penicillin V (15%), ampicillin (16%), and amoxicillin (19%). Nafcillin and oxacillin showed less cross-reactivity (<1%). Cross-reaction with a cephalosporin antibiotic (cephapirin) and structurally nonrelated antibiotics (chloramphenicol, tetracycline, dapsone, and erythromycin) was less than 0.01%.     

凝胶渗透色谱-气相色谱-离子阱质谱法测定桔梗原药和当归提取物中101种农药残留

建立了凝胶渗透色谱（GPC）-气相色谱-离子阱质谱同时检测桔梗原药和当归提取物中101种农药残留的分析方法。方法采用乙腈超声辅助提取桔梗原药和当归提取物,浓缩提取液至近干后用乙酸乙酯-环己烷（1∶1, v/v）复溶,采用凝胶渗透色谱法（选取40 cm长、内径20 mm的凝胶渗透色谱柱）对样品进行净化,弃去前段含脂类、色素等杂质的流出液,收集17~30 min洗脱液并旋转蒸发浓缩至近干,甲苯1 mL定容上机。选用DB-5MS毛细管色谱柱分离待测物,通过离子阱质谱实现对101种农药残留的高效检测。方法通过优化前处理条件和离子阱二级质谱参数,有效降低了复杂中药基质对待测化合物的干扰,最大限度提高了样品中农药的定量准确性和回收率,101种农药3水平添加的平均回收率为58.3%~108.9%,每个添加水平10次独立重复测定的相对标准偏差为0.4%~16.5%,检出限（LOD）范围为0.2~40.0 μg/kg,可满足当前韩国、日本、欧洲规定的最大残留限量（maximum residue limits, MRLs）要求。方法具有操作简单快速、灵敏度高、重复性好等特点,凝胶渗透色谱技术的应用克服了固相萃取小柱净化容量不足的弊端,离子阱技术的应用可以进一步排除共流出基体杂质的干扰,提高定量和定性的准确性,检测效果优于常用的气相色谱-质谱法,是对中药中同时分析多种农药残留检测方法的有益补充。     

Controllable Preparation of Branched Polyolefins with Various Microstructural Units via Chain-walking Ethylene and Pentene Polymerizations

Chinese Journal of Polymer Science - Branched polyolefins with controllable topology structures were generated from the chain-walking (co)polymerizations of ethylene, 1-pentene (1P) and 2-pentene...