锂/铌镁催化剂中碳酸锂的熔点与甲烷氧化偶联反应的活化和失活的关系

研究了铌掺杂的Li/MgO甲烷氧化偶联催化剂的反应性质及铌的助剂作用。铌的引入使得该催化剂上甲烷氧化偶联反应的活化温度降低50℃以上, 使此温度降到了催化剂中碳酸锂的熔点附近。试验观察到部分催化剂上甲烷氧化偶联反应的活性曲线在碳酸锂的熔点附近有一转折, 这一转折现象的出现与否及程度取决于制备条件。在碳酸锂的熔点附近, 含有铌的催化剂得到活化, 观察到无稀释气体时的反应引燃现象, 即温度增加几度活性便达到最大值。当在比碳酸锂熔点稍高的温度下且不稀释时反应, 含铌催化剂活性很高但很快失活, 在稍低于此熔点下则不失活, 但活性较低。这些试验结果表明, 含铌催化剂的活化与失活均与催化剂中的碳酸锂的相变化有关。试验还观察到了在稍高于碳酸锂的熔点下做寿命试验时, 甲烷氧化偶联反应的振荡现象。     

铁丝在氧气中燃烧的实验改进

“铁丝在氧气中燃烧”是初中化学教材中证明氧气化学性质的一个演示实验,该实验证明了氧气比较活泼,在一定条件下可以和金属发生剧烈反应。但是与木炭在氧气中燃烧、硫在氧气中燃烧、蜡烛在氧气中燃烧的演示实验相比,铁丝在氧气中燃烧的实验存在着一些不足的地方,针对这些不足,对铁丝在氧气中燃烧的实验进行了改进。1实验存在的问题按照教材要求,铁丝在氧气中燃烧的实验,须将铁丝绕成螺旋状,并在铁丝的末端绑上一根火柴杆,实验时先将火柴杆点燃,待火柴杆将燃尽时,迅速伸入盛满氧气的集气瓶中。这样的操作存在2个问题:第一,火柴燃烧的程度不…     

提高纤维素酶水解效率和降低水解成本

在我国可大量转化乙醇的是纤维质材料.纤维质材料转化乙醇的关键问题是纤维质转化为糖的过程,提高纤维素酶转化效率的方法有:(1)对纤维质材料进行预处理;(2)研究纤维素酶的最适作用条件;(3)纤维素酶的重复利用;(4)合理的发酵工艺等.本文分析了纤维素的结构以及纤维素酶的作用方式,总结了目前研究较多的几种纤维质材料预处理方法,及其对纤维素酶水解率的影响,并对研究纤维素酶的最适作用条件、纤维素酶的重复利用以及合理的发酵工艺进行了综述和分析.     

银镜的实验室制备

在高中化学“烃的衍生物”,“糖类、油脂、蛋白质”2章的教学中,安排了有关银镜反应的演示实验,其目的是通过实验证明含有醛基的有机物具有还原性。按照教材的方法进行实验操作,往往由于水浴的温度掌握不好,制得银镜的效果不理想。为了快速明显地观察到银镜的产生,采用平板玻璃     

2011年国际化学年《高分子通报》征稿启示

2011年是联合国确定的国际化学年,为纪念化学学科所取得的成就以及对人类文明的贡献,2011年化学年的主题是我们的生活,我们的未来。     

CO催化氧化用纳米材料及其最新研究成果

当前,环境问题和能源危机已经威胁到人类的健康和生存。用于环境治理和化学能源合成新概念的纳米催化材料越来越受到人们的关注。催化作为一个特殊的纳米现象,是纳米材料应用领域的一个重要方向,在环境净化、能量转化和新化学品的生产等方面具有广泛的应用前景。早期的一氧化碳(CO)催化氧化研究主要集中在催化剂的制备方法以及制备条件对催化反应的影响等方面。本文针对CO催化氧化这一基础课题,以影响CO催化氧化的关键因素(如金属颗粒的大小,金属与载体之间的相互作用以及载体本身的作用等)为主线,简要概述了近年来CO催化氧化的催化机理及相关催化剂的最新研究进展。同时,结合我们课题组的一些最新研究结果,进一步指出了纳米材料在CO催化氧化方面还存在的一些值得关注的问题,并对未来CO氧化催化剂的研究做出展望,提出一些可行的研究方向。     

漫话饮用水消毒剂

饮用水消毒剂的种类很多,国内大规模工业化生产主要还是用氯气来消毒。饮用水消毒的目的是杀灭水中可能引起霍乱、伤寒、痢疾等疾病的病菌与病毒。随着科学技术的发展和人们生活水平的提高,饮用水消毒剂也在不断发展,安全、高效、经济的消毒剂将成为主流。下面就目前使用或已开     

序言——《高分子通报》创刊20周年回顾

《高分子通报》是1988年10月创刊的。回顾20年来的发展历程,《高分子通报》是在各级领导的关怀下不断成长的,是在我国高分子科学领域的专家、学者的大力支持下发展的,也是在历届编委、编辑艰苦奋斗,辛勤耕耘下不断提高和前进的。早在1981年冬,昆明功能高分子学术会议中就正式提     

羟基甘氨酸溶液性质研究

采用核磁共振等仪器分析与官能团鉴定相配合的方法，对乙醛酸与铵盐反应形 成的羟基甘氨酸进行了研究。确认了羟基甘氨酸的结构，探讨了羟基甘氨酸的水溶 液中的主要存在形式，得出了与普遍接受的羟基甘氨酸在水溶液中不稳定的观点相 悖的结论。并对羟基甘氨酸的溶液稳定性，氨解，水解进行了研究。本结果为乙醛 酸以及羟基甘氨酸在有机合成上的应用提供了依据。     

在血卟啉衍生物光敏体系中DMPO捕集自由基的ESR研究

光照血卟啉衍生物(HPD)用于肿瘤的诊断和治疗已取得很大的成效,对此药理过程的分子机理的探索也开始引起生物和化学工作者的重视.我们的实验表明,在HPD光敏体系中自由基起着重要作用,特别是羟基自由基可能是HPD光致杀伤肿瘤细胞的主要原因.HPD光敏过程所产生的自由基的寿命极短,用化学方法或用一般ESR直接检测非常困难,但可被     

A confirmatory method for the simultaneous extraction,separation, identification and quantification of Tetracycline,Sulphonamide, Trimethoprim and Dapsone residues in muscle by ultra-high-performance liquid chromatography–tandem mass spectrometry according to Commission Decision 2002/657/EC

A rapid confirmatory multi-residue method for the analysis of tetracyclines, sulphonamides, trimethoprim and dapsone by UPLC-MS/MS is described. The method is able to quantify and confirm the following 19 compounds, oxytetracycline, tetracycline, chlortetracycline, doxycycline, sulfadiazine, sulfathiazole, sulfapyridine, trimethoprim, sulfamerazine, sulfamethizole, sulfamethazine, sulfamethoxypyridazine, sulfamonomethoxine, sulfachlorpyridazine, dapsone, sulfamethoxazole, sulfisoxazole, sulfaquinoxaline and sulfadimethoxine. Samples are extracted with 0.1 M EDTA and acetonitrile, which is then evaporated under a stream of nitrogen and reconstituted in water. Following centrifugation and filtering, an aliquot is analysed by UPLC-MS/MS using positive electrospray ionisation and multiple reaction monitoring. The method is deemed rapid as all analytes are extracted by a single extraction technique, with no solid-phase extraction clean up required. Validation is according to Commission Decision 2002/657/EC and was carried out for bovine, porcine, ovine and poultry species. Specificity, recovery, repeatability, reproducibility, CCα and CCβ data is presented.     

Green synthesis of biogenic metal nanoparticles by terrestrial and aquatic phototrophic and heterotrophic eukaryotes and biocompatible agents

The size, shape and controlled dispersity of nanoparticles play a vital role in determining the physical, chemical, optical and electronic properties attributing its applications in environmental, biotechnological and biomedical fields. Various physical and chemical processes have been exploited in the synthesis of several inorganic metal nanoparticles by wet and dry approaches viz., ultraviolet irradiation, aerosol technologies, lithography, laser ablation, ultrasonic fields, and photochemical reduction techniques. However, these methodologies remain expensive and involve the use of hazardous chemicals. Therefore, there is a growing concern for the development of alternative environment friendly and sustainable methods. Increasing awareness towards green chemistry and biological processes has led to a necessity to develop simple, cost-effective and eco-friendly procedures. Phototrophic eukaryotes such as plants, algae, and diatoms and heterotrophic human cell lines and some biocompatible agents have been reported to synthesize greener nanoparticles like cobalt, copper, silver, gold, bimetallic alloys, silica, palladium, platinum, iridium, magnetite and quantum dots. Owing to the diversity and sustainability, the use of phototrophic and heterotrophic eukaryotes and biocompatible agents for the synthesis of nanomaterials is yet to be fully explored. This review describes the recent advancements in the green synthesis and applications of metal nanoparticles by plants, aquatic autotrophs, human cell lines, biocompatible agents and biomolecules.     

伊敏褐煤中微量元素的地球化学特征及其无机-有机亲和性分析

采用脱矿物质、提取腐殖酸等方法结合ICP-MS对伊敏15_上、16_下煤中的32种微量元素的含量及其赋存特征进行了分析。与地壳克拉克值及中国侏罗-白垩纪煤和世界褐煤中微量元素含量相比,伊敏褐煤中微量元素没有明显富集。脱矿物质处理后,Ni明显富集,As略比原煤高,其他微量元素都低于原煤。原煤提取腐殖酸和脱矿物煤提取腐殖酸中Ni、Mo、Cd、Sn、W明显富集,这表明Ni、Mo、Cd、Sn、W和腐殖酸形成了稳定的有机态化合物。原煤提取腐殖酸残煤和脱矿物煤提取腐殖酸残煤中V、Ni、As富集,表明V、Ni、As与煤的大分子结构形成了稳定的有机态化合物。根据微量元素和灰分的相关性系数,把微量元素分为以下几类:无机富集元素Cr、U;亲无机元素Cu、Cd、In、Sn、Ga、Y、Zr、Hf、Bi、Th;偏无机元素Be、Sc、Rb、Sr、Nb、Cs、Ta、Pb;偏有机元素V、As、Tl、Ba、Se;亲有机元素Li、Co、W;有机富集元素Ni、Zn、Mo、Sb。     

Simultaneous Determination of Cadmium,Mercury, Lead,Arsenic, Copper,and Zinc in Human Breast Milk by ICP‐MS/Microwave Digestion

Abstract

An analytical method using microwave digestion and inductively coupled argon plasma-mass spectrometry (ICP‐MS) analysis was developed for the measurement of Cd, Hg, Pb, As, Cu, and Zn in human breast milk. We applied external calibration, internal calibration, and standard addition for reference material and pooled milk analysis. Method performances were defined in terms of detection limits, accuracy, and precision. Accuracy varied between 93% and 105% and precision between 3% and 8%. External calibration and background interferences were checked through a calibrator addition procedure. Our method has shown high accuracy, precision, and sensitivity, as well as linearity within a wide range of values. Our methodology, developed by treatment of reference material and pooled milk samples, was applied for determination of Cu, Zn, As, Cd, Hg, and Pb in 120 human breast milk samples.     

Organic heterocyclic-based colorimetric and fluorimetric chemosensors for the detection of different analytes: a review (from 2015 to 2022)

Heterocyclic organic compounds, also called heterocycles, are any major class of organic compounds having at least one atom other than carbon in the ring. Due to their excellent electronic and structural features, these compounds exhibit a wide range of biological and nonbiological applications. Among these, indole, benzimidazole, benzothiazole, and benzoxazole are versatile organic heterocyclic compounds widely used in different fields. They show a wide range of applications in polymer, coordination chemistry, pharmacy, dyes, food packages, medicine, and industries. These compounds contain heteroatoms like S-, N-, and O-, through which they interact with metal ions, anions, and neutral species, giving measurable analytical signals that can be used as fluorimetric and colorimetric chemosensors for detecting different analytes in biological, agricultural and environmental samples. This review summarizes indole, benzimidazole, benzothiazole, and benzoxazole-based fluorimetric and colorimetric chemosensors for detecting metal ions, anions, and neutral species. Furthermore, the recognition mechanisms have been discussed in detail, which could help researchers to design efficient, highly selective, and sensitive chemosensors to recognize and determine heavy metal cations.     

Antihypertensive activity of indole and indazole analogues: A review

Heterocyclic compounds occupy an important position in chemistry because of their wide range of uses in drug design, photochemistry, agrochemicals, and other fields. Indole and indazole scaffolds are available from natural and synthetic sources, and molecules containing these scaffolds have been shown to have various biological effects, including anti-inflammatory, antibacterial, antiviral, antifungal, analgesic, anticancer, antioxidant, anticonvulsant, antidepressant, and antihypertensive activities. Indole and indazole molecules bind to receptors with high affinity, and thus are useful for the study of bioactive compounds involved in multiple pathways. In this review, we highlight the antihypertensive activity and the mechanisms of action of indole and indazole derivatives. In addition, structure–activity relationship studies of the antihypertensive effect are presented.     

Tools and resources for metabolomics research community: A 2017–2018 update

The scale at which MS‐ and NMR‐based platforms generate metabolomics datasets for both research, core, and clinical facilities to address challenges in the various sciences—ranging from biomedical to agricultural—is underappreciated. Thus, metabolomics efforts spanning microbe, environment, plant, animal, and human systems have led to continual and concomitant growth of in silico resources for analysis and interpretation of these datasets. These software tools, resources, and databases drive the field forward to help keep pace with the amount of data being generated and the sophisticated and diverse analytical platforms that are being used to generate these metabolomics datasets. To address challenges in data preprocessing, metabolite annotation, statistical interrogation, visualization, interpretation, and integration, the metabolomics and informatics research community comes up with hundreds of tools every year. The purpose of the present review is to provide a brief and useful summary of more than 95 metabolomics tools, software, and databases that were either developed or significantly improved during 2017–2018. We hope to see this review help readers, developers, and researchers to obtain informed access to these thorough lists of resources for further improvisation, implementation, and application in due course of time.     

Indole-Containing Natural Products 2019–2022: Isolations,Reappraisals, Syntheses,and Biological Activities

Indole alkaloids represent a large subset of natural products, with more than 4100 known compounds. The majority of these alkaloids are biologically active, with some exhibiting excellent antitumor, antibacterial, antiviral, antifungal, and antiplasmodial activities. Consequently, the natural products of this class have attracted considerable attention as potential leads for novel therapeutics and are routinely isolated, characterized, and profiled to gauge their biological potential. However, data on indole alkaloids, their various structures, and bioactivities are complex due to their diverse sources, such as plants, fungi, bacteria, sponges, tunicates, and bryozoans; thus, isolation methods produce an incredible trove of information. The situation is exacerbated when synthetic derivatives, as well as their structures, bioactivities, and synthetic schemes, are considered. Thus, to make such data comprehensive and inform researchers about the current field’s state, this review summarizes recent reports on novel indole alkaloids. It deals with the isolation and characterization of 250 novel indole alkaloids, a reappraisal of previously reported compounds, and total syntheses of indole alkaloids. In addition, several syntheses and semi-syntheses of indole-containing derivatives and their bioactivities are reported between January 2019 and July 2022.     

Review: Recent Developments in Enzyme-Based Biosensors for Biomedical Analysis

The need for simple, rapid, cost-effective, and portable screening methods has boosted the development of practical biosensors with applications in clinical monitoring, and diagnosis of disease. Compared with traditional analytical methods, enzyme-based bioanalytical devices have several distinct advantages such as high sensitivity and specificity, portability, cost-effectiveness, and the possibilities for miniaturization and mass production. Additionally, they can be developed for point-of-care diagnostic testing. This paper reviews recent advances in the development of enzyme biosensors, design characteristics, performances, and applications with a focus on electrochemical and optical sensors. Recent emerging technologies and innovative biosensing designs, such as nanosensors, paper based-sensors, lab-on-a-chip, biochips, and microfluidic devices are discussed. Specific applications in bioanalysis, clinical diagnosis, and pharmacology are discussed.     

SYNTHESIS, CHARACTERIZATION, THERMAL DEGRADATION AND ELECTROCHEMICAL PROPERTIES OF OLIGO-4-m-TOLYLAZOMETHINEPHENOL

The oxidative polycondensation reaction conditions of 4-m-tolylazomethinephenol （4-TAMP） in the presence of air O2 and NaOCl as oxidants were studied in an aqueous alkaline medium between 50 and 90℃. The structures of the obtained monomer and oligomer were confirmed by FT-IR, UV-Vis, ^1H- and ^13C-NMR and elemental analysis techniques. The physical characterization was made by TG-DTA, size exclusion chromatography （SEC） and solubility tests. At the optimum reaction conditions, the yield of oligo-4-m-tolylazomethinephenol （O-4-TAMP） was found to be 62.50% （for air O2 oxidant） and 90.0% （for NaOCl oxidant）, respectively. According to the SEC analysis, the number-average molecular weight （Mn）, weight-average molecular weight （Mw） and polydispersity index （PDI） values of O-4-TAMP were found to be 2310, 2610 g tool 1 and 1. 13, respectively, using air O2, and 1390, 1710 g mol^-1 and 1.23, using NaOCl, respectively. According to TG-DTA analyses, O-4-TAMP was more stable than 4-TAMP against thermal decomposition. The weight losses of 4-TAMP and O-4-TAMP were found to be 68% and 58% at 1000℃. Electrical conductivity of the O-4-TAMP was measured, showing that the polymer is a typical semiconductor. Electrochemically, the highest occupied molecular orbital （HOMO）, the lowest unoccupied molecular orbital （LUMO） and electrochemical energy gaps （E＇g） for 4-TAMP are -5.96, -3.22 and 2.74 eV, respectively. The HOMO, LUMO and （E＇g） for O-4-TAMP are -5.78, -3.44 and 2.34 eV, respectively. According to UV-Vis measurements, optical band gaps （Eg） of 4-TAMP and O-4-TAMP were found to be 3.45 and 3. 1 0 eV, respectively.