Reliable screening of pesticide residues in maternal and umbilical cord sera by gas chromatography-quadrupole time of flight mass spectrometry

The widespread use of pesticides induces heavy adverse effects on human health,especially for the pregnant women and the newborns.In this study,a screening method has been developed for the determination of multi-pesticides in maternal and umbilical cord sera.All pesticides in sera were collected using solid phase extraction(SPE),and analyzed by gas chromatography-quadrupole time of flight mass spectrometry(GC-QTOF MS).To set up the quality criteria,a database of 50 pesticides was created and the accurate masses of 3 up to 5 representative ions with their intensity ratios were included for each pesticide.In addition,a novel"identification points"(IPs)system relying on the accurate MS1 and MS2 spectra was used to interpret the data for each suspected pesticide.The methodology was then applied to a pair of maternal and umbilical cord sera.A total of six pesticide residues were screened out successfully.In conclusion,GC-QTOF MS combined with an accurate mass database seemed to be one of the most efficient tools for systematic pesticide analysis.     

Cu3Mo2O9 nanosheet incorporated with hemoglobin on carbon ionic liquid electrode for the direct electrochemistry and electrocatalysis

In this paper Cu₃Mo₂O₉ nanosheet was prepared by a hydrothermal method and further used to investigate the direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode (CILE) as the substrate electrode. Hb was mixed with Cu₃Mo₂O₉ nanosheet and cast on the CILE surface with chitosan (CTS) as the film-forming material. UV-vis and FT-IR spectroscopic results showed that Hb remained in its native structure in the composite film. Direct electron transfer of Hb on the modified electrode was realized with a pair of well-defined quasi-reversible redox waves that appeared on cyclic voltammograms. The redox peak potential appeared at ?0.252 V (E _pc) and ?0.141 V (E _pa), respectively, with the formal peak potential calculated as ?0.196 V, which was the characteristic of electroactive center of Hb heme Fe(III)/Fe(II). The result could be attributed to the presence of Cu₃Mo₂O₉ nanosheet on the electrode surface that was of benefit for the protein orientation and promoted direct electron transfer between the redox active center of Hb and the substrate electrode. The CTS/Cu₃Mo₂O₉–Hb/CILE showed good electrocatalytic ability in reducing different substrates such as trichloroacetic acid, H₂O₂ and O₂, with wider linear range and lower detection limit, thus exhibiting the potential application of the Cu₃Mo₂O₉ nanosheet in third-generation electrochemical biosensors.     

Bridge‐Localized HOMO‐Binding Character of Divinylanthracene‐Bridged Dinuclear Ruthenium Carbonyl Complexes: Spectroscopic,Spectroelectrochemical, and Computational Studies

The electronic properties of four divinylanthracene‐bridged diruthenium carbonyl complexes [{RuCl(CO)(PMe₃)₃}₂(μ? CH?CHArCH?CH)] (Ar=9,10‐anthracene ( 1 ), 1,5‐anthracene ( 2 ), 2,6‐anthracene ( 3 ), 1,8‐anthracene ( 4 )) obtained by molecular spectroscopic methods (IR, UV/Vis/near‐IR, and EPR spectroscopy) and DFT calculations are reported. IR spectroelectrochemical studies have revealed that these complexes are first oxidized at the noninnocent bridging ligand, which is in line with the very small ν(C?O) wavenumber shift that accompanies this process and also supported by DFT calculations. Because of poor conjugation in complex 1 , except oxidized 1⁺ , the electronic absorption spectra of complexes 2⁺ , 3⁺ , and 4⁺ all display the characteristic near‐IR band envelopes that have been deconvoluted into three Gaussian sub‐bands. Two of the sub‐bands belong mainly to metal‐to‐ligand charge‐transfer (MLCT) transitions according to results from time‐dependent DFT calculations. EPR spectroscopy of chemically generated 1⁺ – 4⁺ proves largely ligand‐centered spin density, again in accordance with IR spectra and DFT calculations results.     

Ligand‐Free Palladium‐Catalyzed Aerobic Oxidative Coupling of Carboxylic Anhydrides with Arylboronic Acids

We report a new, effective and environmentally friendly protocol for selective aerobic oxidative coupling of arylboronic acids with carboxylic anhydrides in the presence of ligand‐free palladium catalyst. The aryl benzoates are obtained in good to excellent yields.     

Polypeptide‐b‐Poly(Phenyl Isocyanide) Hybrid Rod‐Rod Copolymers: One‐Pot Synthesis,Self‐Assembly,and Cell Imaging

Hybrid rod‐rod diblock copolymers, poly(γ‐benzyl L‐glutamate)‐poly(4‐cyano‐benzoic acid 2‐isopropyl‐5‐methyl‐cyclohexyl ester) (PBLG‐PPI), with determined chirality are facilely synthesized through sequential copolymerization of γ‐benzyl‐L‐glutamate N‐carboxyanhydride (BLG‐NCA) and phenyl isocyanide monomers bearing chiral menthyl pendants using a Ni(cod)(bpy) complex as the catalyst in one‐pot. Circular dichroism and absorption spectra reveal that each block of the block copolymers possesses a stable helical conformation with controlled helicity in solution due to the induction of chiral pendants. The two diastereomeric polymers self‐assemble into helical nanofibrils with opposite handedness due to the different chiral induction of the L‐ and D‐menthyl pendants, confirmed by transmission electron micro­scopy (TEM). Deprotection of the benzyl groups of the PBLG segment affords biocompatible amphiphilic diblock copolymers, poly(L‐glutamic acid)‐poly(4‐cyano‐benzoic acid 2‐isopropyl‐5‐methyl‐cyclohexyl ester) (PLGA‐PPI), that can self‐assemble into well‐defined micelles by cosolvent induced aggregation. Very interestingly, a chiral rhodamine chromophores RhB(D) can be selectively encapsulated into the chiral polymeric micelles, which is efficiently internalized into living cells when directly monitored with a confocal microscope. This contribution will be useful for developing novel rod‐rod biocompatible hybrid block copolymers with a controlled helicity, and may also provide unique chiral materials for potential bio‐medical applications.

     

国内外近30年“电化学”主题概念测查研究进展*

梳理了国内外1990-2020年核心期刊文献中对学生电化学主题概念测评的实证研究,主要涵盖学生电化学概念理解水平以及影响因素等方面。据此探讨其对化学教师教学实施以及国内外化学教育实证研究的启示,以期为中学化学教学及后续研究提供有益参考。     

基于深度学习理论的有机合成课程教学改革

有机合成既是有机化学学习中的一个独立构成部分,也是安排于有机化学课程之中的重要学习主题。在目前的有机合成课程教学中,教师的自觉性引导不足,学生容易陷入浅层学习状态,导致教学效果不佳。结合有机化学学科特点,从有机合成课程教学现状出发,围绕深度学习教学设计的四要素——深度学习目标、挑战性学习主题、深度学习活动、持续性评价,以典型的教学片段为例阐述深度学习理论在教学实践中的应用,为相关教学工作提供参考。     

基于深度学习的“实验方案设计”主题式复习教学——以“阿司匹林的制备和提纯”为例

针对实验方案设计题的得分率分析和教学现状,基于课程标准、教材、真题和文献研究,构建“阿司匹林的制备和提纯”深度学习主题模型。通过设计制备和提纯阿司匹林的实验方案,构建实验方案设计的思维模型,并以制备七水合硫酸锌为例内化思维模型,在解决真实、复杂的问题过程中实现核心知识结构化,生成指向深度学习的主题式复习教学流程。     

“四模块”嵌入下的混合式教学设计与实践*——以功能材料专业物理化学基础课程为例

为建设适应新时代要求,突出高阶性、创新性、挑战度的一流本科课程,实现价值引领、能力培养和知识传授的教育教学目标,结合功能材料专业的特点和民族高等院校学生的学情,构建了物理化学基础课程的“四模块、三阶段、两时空、双平台”的混合式教学新模式,重塑了“价值引领模块、基础理论模块、多学科融合模块和虚拟仿真实验模块”的“四模块”内容体系。通过“四模块”嵌入下的混合式教学实践研究,结合学生的课前、课中、课后等学习成绩,多维度评价学习效果,并藉由调查问卷来分析学生对混合式教学的评价,最终研究结果表明学生的个性化自主学习能力有了显著提高、学生运用物理化学理论解决复杂问题的综合能力得到了提升,学生经过刻苦学习获得了素质提高的成就感。     

有机催化吲哚碳环上的不对称Friedel⁃Crafts烷基化反应

将金鸡纳碱衍生物双功能催化剂用于有机催化羟基吲哚与靛红的不对称Friedel-Crafts反应, 筛选出最佳反应条件: 催化剂为5%(摩尔分数)6′-脱甲基奎尼丁(1b), 溶剂为四氢呋喃, 反应温度 0 ℃. 以67%~91%的产率和最高达97%的对映选择性获得了苯环上取代的羟基烷基化产品. 拓宽了该反应的催化剂类型和底物范围.