Ion-pairing high-performance liquid chromatography determination of amitrole in apple after solid-phase extraction and precolumn derivatization

A novel method based on solid-phase extraction was studied for the extraction of amitrole (3-amino-1,2,4-triazole), and its residue determination in apples has been developed. The samples were derivatized with 4-chloro-3,5-dinitrobenzotrifluoride (CNBF). The derivatization conditions and the influence of elution composition on the separation were investigated. In pH 9.5 H₃BO₃–Na₂B₄O₇ media, the reaction of amitrole with CNBF was complete at 60°C after 30 min. The separation of derivatized amitrole was achieved at room temperature within 13 min by gradient elution mode with cetyltrimethylammonium bromide in mobile phase as ion-pair reagent. The method correlation coefficient was 0.9996, in concentrations ranging from 1.66 to 415 mg L⁻¹. The calculated recoveries of the proposed method were from 94.17% to 105.67%, and relative standard deviations were 1.57% to 6.44% in the application to the quantitative determination of amitrole in apples. The detection limit of amitrole was 0.10 mg L⁻¹ with a signal-to-noise ratio of 3. Figure Residue determination of amitrole in apple by ion-pairing high-performance liquid chromatography     

新型锂离子电池正极材料Li0.86V0.8O2的水热合成及性质

采用两步反应制备了新型锂离子电池正极材料Li0.86V0.8O2. 该材料具有六方层状结构, 空间群为R3m. 研究了在水热条件下溶液的碱度对于钒酸锂盐形成的影响, 在低碱度的条件下, 前驱体V2O3和LiOH·H2O并未发生反应, 只有在碱度达到2.5 mol/L时, 才能形成单相的Li0.86V0.8O2材料. X射线光电子能谱分析发现, V2p的结合能位于516.4 和523.1 eV, 分别对应于四价钒离子的V2p3/2 和V2p1/2, 这说明在Li0.86V0.8O2中V离子主要价位为+4价. 在电流密度为7.4 mA/g的充放电中, Li0.86V0.8O2初始充电容量达到163 mA·h/g, 首次放电容量也能达到113 mA·h/g, 20次循环后放电容量仍然可以达到80 mA·h/g, 表现出较好的循环性能.     

A-B2型含二苯甲酮的对硝基二苯乙烯类染料的合成、双光子性质与电化学

报道了3',4'-二(对苯甲酰基苯甲氧)基-4-硝基二苯乙烯(C1)的合成与表征. 研究了在不同溶剂中分子的吸收与荧光发射. 分子在可见光区的吸收可以归于生色团对硝基二苯乙烯部分的贡献, 而其在短波长区的吸收主要由二苯甲酮部分提供. 分子在中等极性溶剂中表现出较强的荧光发射. 系统研究了3',4'-二(对苯甲酰基苯甲氧)基-4-硝基二苯乙烯与2',4'-二(对苯甲酰基苯甲氧)基-4-硝基二苯乙烯(C2)两种A-B2型分子的双光子性质与电化学行为. 结果表明, 在800 nm波长的飞秒激光激发下, 两个分子皆表现出明显的上转换荧光发射, 其双光子吸收横截面的大小与二苯甲酮取代位置表现出一定的相关性. 分子结构优化与电化学的研究表明, 两个分子的电子密度分布与前线轨道能量亦与二苯甲酮取代位置表现出一定的相关性.     

Metallic Co4N Porous Nanowire Arrays Activated by Surface Oxidation as Electrocatalysts for the Oxygen Evolution Reaction

Designing highly efficient electrocatalysts for oxygen evolution reaction (OER) plays a key role in the development of various renewable energy storage and conversion devices. In this work, we developed metallic Co₄N porous nanowire arrays directly grown on flexible substrates as highly active OER electrocatalysts for the first time. Benefiting from the collaborative advantages of metallic character, 1D porous nanowire arrays, and unique 3D electrode configuration, surface oxidation activated Co₄N porous nanowire arrays/carbon cloth achieved an extremely small overpotential of 257 mV at a current density of 10 mA cm⁻², and a low Tafel slope of 44 mV dec⁻¹ in an alkaline medium, which is the best OER performance among reported Co‐based electrocatalysts to date. Moreover, in‐depth mechanistic investigations demonstrate the active phases are the metallic Co₄N core inside with a thin cobalt oxides/hydroxides shell during the OER process. Our finding introduces a new concept to explore the design of high‐efficiency OER electrocatalysts.     

PREPARATION AND CHARACTERIZATION OF AFFINITY POLYMER BASIC MICROSPHERES BY SOAP-FREE EMULSION POLYMERIZATION

Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2.2′- azobis(2-methylpropionamidine) dihydrochloride as an initiator.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors were examined.In addition,the optimum polymerization conditions of poly(styrene-co- glycidyl methacrylate) latex microspheres ...     

MICROPHASE SEPARATED STRUCTURES AND PROPERTIES OF PDMS-MDI-PEG COPOLYMER SURFACE

A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS. contact angle system,protein adsorption and platelets adhesion measurements,respectively.It was found that as the molecular weight of PDMS increased,the surface of copolymers had increasing phase separation,while the increase in the molecular weight of PEG decreased the phase separation ext...     

茶叶中有机氯和拟除虫菊酯多种农药残留同时分析的样品前处理研究

建立了茶叶中同时分析12种有机氯和拟除虫菊酯类农药残留的样品提取和固相萃取(SPE)前处理方法.试样在超声条件下用正己烷提取后用自制弗罗里圭(florisil)/石墨化碳复合固相萃取小柱净化,然后采用气相色谱-电子捕获检测器(GC-ECD)测定.研究结果表明,当茶叶中农药加标在4.93～201.00 ng/g范围内时,添加回收率为68.9%～112.2%,相对标准偏差为2.43%～15.8%,方法的检出限范围在2.52～10.59 ng/g.     

ICP-MS测定化肥中有害元素Cr、Cd、As、Pb、Hg的新方法

采用电感耦合等离子体质谱法测定化肥中微量Cr、Cd、As、Pb、Hg元素.样品经微波消解和敞开酸溶,滴加5 ～8滴2%高锰酸钾氧化,低温水浴加热蒸至近干,加甲醇2 mL溶剂化,用水定容至100 mL,进行测定.方法标准加入回收率为67% ～115%,RSD小于15%,误差完全符合GB18877-2002的规定要求,方法简便快速.     

Transgenic Tobacco Expressing <Emphasis Type="Italic">Zephyranthes grandiflora</Emphasis> Agglutinin Confers Enhanced Resistance to Aphids

Plant lectins have been reported as transgenic resistance factors against a variety of insect pests. Herein, homologous analysis demonstrated that Zephyranthes grandiflora agglutinin (ZGA) exhibited high similarity with other monocot mannose-binding lectins (MBLs). Phylogenetic analysis revealed that it had taxonomical relationships with insecticidal MBLs. Subsequently, a plasmid expression vector pBI121 containing zga gene (pBIZGA) was constructed using the zga sequence, under the control of CaMV35S promoter and nos terminator. pBIZGA was then integrated into the genome of Nicotiana tabacum L. Polymerase chain reaction and Southern blot analysis demonstrated that this zga gene was integrated into the plant genome. Western blotting and agglutinating activity analysis also showed that transgenic tobacco plants expressed different levels of ZGA. Carbohydrate inhibition analysis indicated that recombinant ZGA and the native shared the same carbohydrate-binding specificity. Moreover, genetic analysis confirmed Mendelian segregation (3:1) of the transgenic in T1 progenies. In planta bioassays on T0 plants and their progenies indicated that expressed ZGA had an effect on reducing the survivability and fecundity of tobacco aphids (Myzus nicotianae). These findings demonstrate that the novel zga gene of ZGA can be expressed in crop plants susceptible to various sap-sucking insects.     

Application of solid-phase microextraction for the determination of organophosphorus pesticides in textiles by gas chromatography with mass spectrometry

A method based on solid-phase microextraction (SPME) and gas chromatography with mass spectrometry (GC/MS) for the determination of 18 organophosphorus pesticides (OPPs) in textiles is described. Commercially available SPME fibers, 100 μm PDMS and 85 μm PA, were compared and 85 μm PA exhibited better performance to the OPPs. Various parameters affecting SPME, including extraction and desorption time, extraction temperature, salinity and pH, were studied. The optimized conditions were: 35 min extraction at 25 °C, 5% NaSO₄ content, pH 7.0, and 3.5 min desorption in GC injector port at 250 °C. The linear ranges of the SPME-GC/MS method were 0.1-500 μg L⁻¹ for most of the OPPs. The limits of detection (LODs) ranged from 0.01 μg L⁻¹ (for bromophos-ethyl) to 55 μg L⁻¹ (for azinphos-methyl) and the RSDs were between 0.66% and 9.22%. The optimized method was then used to analyze 18 OPPs in textile sample, and the determined recoveries were ranged from 76.7% to 126.8%. Moreover, the distribution coefficients of the OPPs between 85 μm PA fiber and simulative sweat solution (K_pa/s) were determined. The determined K_pa/s of the OPPs correlated well with their octanol-water partition coefficients (r = 0.764 and 0.678) and water solubility (r = −0.892 and −0.863).