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关键词： antibodies as receptors   gravimetry   molecular spectroscopy   separation techniques  

摘要： Selected current trends in analytical chemistry are discussed and traced back to original work published more than a hundred years ago in the same field. Gravimetric microanalysis has been transformed into a mass-sensitive sensor technology. New developments in molecular spectroscopy are seen in Raman spectroscopy. In the area of chemical sensors, paper-based devices with visual readout (dipsticks, microfluidic pads) celebrate a revival. In "green" applications, the separation of analytes from complicated matrices is often the key to successful analysis. Continuous separation techniques are essential for the 24/7 production of goods with certified quality. Finally, micro- and nanoscale techniques rely on highly selective receptors, and their development is based on detailed understanding of the structure of ligand-receptor complexes.

关键词： Chemometrics   Data science   Big data   Chemical analytical data   Methodology  

摘要： Efficient and reliable analysis of chemical analytical data is a great challenge due to the increase in data size, variety and velocity. New methodologies, approaches and methods are being proposed not only by chemometrics but also by other data scientific communities to extract relevant information from big datasets and provide their value to different applications. Besides common goal of big data analysis, different perspectives and terms on big data are being discussed in scientific literature and public media. The aim of this comprehensive review is to present common trends in the analysis of chemical analytical data across different data scientific fields together with their data type-specific and generic challenges. Firstly, common data science terms used in different data scientific fields are summarized and discussed. Secondly, systematic methodologies to plan and run big data analysis projects are presented together with their steps. Moreover, different analysis aspects like assessing data quality, selecting data preprocessing strategies, data visualization and model validation are considered in more detail. Finally, an overview of standard and new data analysis methods is provided and their suitability for big analytical chemical datasets shortly discussed. (C) 2018 Elsevier B.V. All rights reserved.

关键词： In vitro protein synthesis   Purified components   Cell-free system   Titration  

摘要： Cell-free protein synthesis (CFPS) is a valuable tool for basic and applied research. The Escherichia coli cell lysate-based system is the most widely used for in vitro transcription and translation (TX-TL). To optimize this system and increase target protein production, the present study investigated the contribution of most of the macromolecular components of the TX-TL machinery by means of systematic titration experiments. A 1.9-fold increase in enhanced green fluorescent protein expression was achieved relative to the reference system by single-component supplementation, while a 2.5-fold increase was achieved by adding T7 RNA polymerase, ribosome-recycling factor, translation initial factor (IF) 1, IF2, and elongation factor Tu. A similar enhancement in the production of other proteins was also achieved by supplementation, thereby indicating the broad applicability of this approach. These results provide useful information for further optimization of CFPS and a basis for improving industrial enzyme production by engineering bacterial strains that express specific components of the TX-TL machinery. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Chlorine compounds  

摘要： Advances in microfabrication technology can enable innovative took for isothermal titration calorimetry (ITC), which enables direct, label-free determination of thermodynamic parameters of reaction systems. Currently existing microfabricated ITC devices, however, either do not yet allow quantitative thermodynamic characterization, or are not well suited to ITC characterization of fast chemical reactions. Aiming to address these limitations, we present a microfabrication-based ITC approach that uses a combined in-mixing and post-mixing titration approach for accurate characterization of thermodynamic parameters. By accounting for reaction heat produced both during and after the reagent mixing process, accurate, quantitative ITC measurements are achieved. The ITC device design in this approach features a pair of three-dimensional self-crossing channels that serve both as micromixers and reaction cells. A bismuth-antimony thermopile whose hot and cold junctions are aligned to the centers of the crossing channels, is used for reaction heat detection. The microfabricated ITC device has a low limit of detection of 45 nW, and a short thermal response time of 800 ms. The utility of the device has been demonstrated with quantitative ITC measurements of the model chemical reaction system of 18-Crown-6 and barium chloride. The thermodynamic parameters of the reaction system, including the stoichiometry, equilibrium binding constant, and enthalpy change were obtained and found to be in agreement with widely accepted values in the literature.

关键词： 酸碱中和滴定   测定实验   实验数据处理   中学化学   高考命题   实验仪器   操作步骤   误差分析  

摘要： 酸碱中和滴定是中学化学重要的定量测定实验，当然也是高考命题的热点，这类试题常从酸碱中和滴定原理人手，分别考查实验仪器的选择、实验操作步骤、指示剂的选择、实验误差分析及实验数据处理等。

关键词： HS-AFM   conformational change   GLIC   Cys-loop   ion channel  

摘要： Gloeobacter violaceus ligand-gated ion channel (GLIC), a proton-gated, cation-selective channel, is a prokaryotic homolog of the pentameric Cys-loop receptor ligand-gated ion channel family. Despite large changes in ion conductance, small conformational changes were detected in X-ray structures of detergent-solubilized GLIC at pH 4 (active/desensitized state) and pH 7 (closed state). Here, we used high-speed atomic force microscopy (HS-AFM) combined with a buffer exchange system to perform structural titration experiments to visualize GLIC gating at the single-molecule level under native conditions. Reference-free 2D classification revealed channels in multiple conformational states during pH gating. We find changes of protein-protein interactions so far elusive and conformational dynamics much larger than previously assumed. Asymmetric pentamers populate early stages of activation, which provides evidence for an intermediate preactivated state.

摘要： In order to design a dynamic titration method, we propose a theoretical model harnessing the kinetic properties of the complexation of the titrated species with a titrating photoswitchable reagent. Forced oscillations of illumination are imposed and concentration oscillations of the targeted species are deduced from the equations of chemical kinetics. We determine analytical expressions of the resonance conditions on the control parameters, angular frequency, mean light intensity, and total concentration of the photoswitchable reagent, which optimize the out-of-phase amplitude of concentration oscillations. A user-friendly protocol of dynamic titration is proposed.

关键词： 项目导向   任务驱动   教学法   分析化学   应用  

摘要： ＂项目导向、任务驱动＂教学法职业技能型课程教学中应用较为广泛。本文基于对＂项目导向、任务驱动＂教学法研究,初步探索和实践了该教学法在分析化学课程教学中的应用。包括综合性和实践性的项目任务的设计和以项目任务的组织实施过程为主的教学活动的实施。结果表明,＂项目导向、任务驱动＂教学法在分析化学教学中应用,可以提高学生学习的积极性、主动性,增强学习兴趣和学习信心。学生的沟通协作能力、团队精神和团队意识得以锻炼,班级组织纪律性和凝聚力明显增强,对提高学生自主学习能力、分析和解决实际问题的综合能力以及适应实际工作环境的能力等方面皆有促进作用,使学生既掌握了理论知识,又掌握了实践操作技能,收到良好的教学效果。