Particle formation and surface processes on atmospheric aerosols: A review of applied quantum chemical calculations

Aerosols significantly influence atmospheric processes such as cloud nucleation, heterogeneous chemistry, and heavy-metal transport in the troposphere. The chemical and physical complexity of atmospheric aerosols results in large uncertainties in their climate and health effects. In this article, we review recent advances in scientific understanding of aerosol processes achieved by the application of quantum chemical calculations. In particular, we emphasize recent work in two areas: new particle formation and heterogeneous processes. Details in quantum chemical methods are provided, elaborating on computational models for prenucleation, secondary organic aerosol formation, and aerosol interface phenomena. Modeling of relative humidity effects, aerosol surfaces, and chemical kinetics of reaction pathways is discussed. Because of their relevance, quantum chemical calculations and field and laboratory experiments are compared. In addition to describing the atmospheric relevance of the computational models, this article also presents future challenges in quantum chemical calculations applied to aerosols.     

Chemical tools for functional studies of glycans

In recent years a variety of chemical approaches have been developed for elucidating the molecular basis of biological processes in which glycans participate. The chemical technologies uncovered have greatly influenced the progress of glycomics research programs. This tutorial review highlights recent advances in chemical tools which have been developed and their applications in studies aimed at gaining a better understanding of the roles that glycans play in biological processes.     

超临界甲醇在化学反应中的应用

超临界流体技术在绿色化工过程中的应用范围不断拓宽。由于超临界甲醇具有独特的物理和化学性质,它既是反应介质,也是反应物,因此,超临界甲醇下的化学反应研究得到人们广泛的关注。本文在介绍超临界甲醇独特的物理化学特性的基础上,综述了近年来超临界甲醇体系在有机合成、生物柴油的制备、生物质处理和高聚物的降解等方面的应用研究进展,重点对超临界甲醇下各种反应的影响因素进行了分析讨论。最后,展望了超临界甲醇在甲醇化工中的应用前景。     

New Technologies for the Filmless Manufacture of Printing Forms

The economic reproduction of graphic information was first made possible in the western world by Gutenberg's invention of movable type. In the printing methods of that time, mechanical transfer processes played the major role, while chemical processes were of secondary importance. When Alois Senefelder invented planographic printing (lithoprinting) at the end of the 18th century he called the new process “chemical printing”. Since then, chemistry has attained great importance in the production of printing forms: Thus the manufacture of surface (litho-) printing forms with light required temporary storage materials and image reproduction processes based on chemical reactions. Since the advent of electronic processing of information, however, several former temporary storage media have become obsolete; newer, more sensitive image reproduction processes are increasingly making less use of chemical principles than of the electrical properties of materials.     

Solar energy combined with chemical reactive systems for the production and storage of sustainable energy. A review of thermodynamic principles

This review article deals with thermodynamics and thermochemistry of processes combining solar radiation power with chemical reactions for the production and storage of usable energy.Some of the most promising procedures of such processes discussed in the literature have been selected as representative examples and are analyzed on the basis of their thermodynamic principles rather than reporting on technical details and feasibility studies with respect to economic potentials. The examples studied involve pure gaseous as well as heterogeneous reactive systems where the shift of chemical equilibria at different temperatures is used to gain chemical energy. The majority of examples focusses on different multistep chemical processes for water splitting into H₂ and O₂ which have already been tested on laboratory and semi technical scale.     

Reaction calorimetry for the development of chemical reactions

A new reaction calorimeter is described that has been developed to study chemical reaction processes on a laboratory scale. It provides precise measurements of kinetic and thermal data, of heat transfer data, as well as of the physical properties of the reaction product. The reaction calorimeter is applied successfully in the development of chemical processes, in the evaluation of hazards and risks of chemical synthesis.Working principles and evaluation are described using the example of the nitration of benzaldehyde.     

A possible construction of chemical reaction networks

The chemical reaction networks and the sequence networks represent the pathways of a complex chemical process. In order to study the pathways separately the systematization of the elementary processes included in the possible mechanism is inevitable.This systematization was realized by a special procedure based on linear algebraic methods and enabled us to select the corresponding processes from the possible mechanism. The efficiency of the procedure has been illustrated by its application to the liquid phase oxidation of ethylbenzene and the elementary processes have been selected using a computer program.     

An XAFS investigation of the artefacts caused by sequential extraction analyses of Pb-contaminated soils

The chemical processes that occur during sequential extraction of a highly Pb-contaminated soil sample were investigated using XAFS spectroscopy for the identification of the Pb species in the solid residues after each step. The sequential extraction was performed following the procedure described by Salomons and F?rstner. It was found that during the sequential extraction serious alteration of the chemical binding forms of the Pb occurs. The most important processes underlying the chemical changes are the re-adsorption of solubilized Pb ions by soil matrix components and the precipitation of insoluble Pb species with anions from the extractant.     

化学链技术及其在化石能源转化与二氧化碳捕集领域的应用

化学链是指将某一特定的化学反应通过化学介质的作用分多步反应完成的过程．这一概念早在20世纪初就曾被用于以水蒸气与铁反应制备氢气,并于20世纪中期被提出用于二氧化碳的商业化生产．然而,时至今日,尚无商业化的化学链工艺用于化石燃料的转化．在近年来全球气候变暖及能源危机的急迫形势下,化学链循环过程由于其具有可以将碳基燃料直接转化为可供封存的二氧化碳的独特能力而格外受到关注,人们因而加大了对化学链工艺的研究开发力度．现代化学链工艺逐步克服了早期工艺的缺点,并不断尝试开发以煤或者其他固体燃料作为直接进料的新工艺．现有的各种小试及中试装置操作结果及系统模拟分析表明,化学链循环工艺可以有效地降低二氧化碳分离能耗并提高化石能源转化效率,极具商业化潜力．本文主要介绍目前世界范围内现行的使用化石燃料作为原料的化学链循环工艺,重点总结对比了化学链燃烧和化学链气化两个过程的发展现状,并对化学链循环工艺工业化进程中的机遇和挑战进行了简要的讨论．     

Kinetics of Electrochemical Processes under Conditions of a Slow Chemical Reaction in Solution

The kinetics of electrochemical processes under the conditions of a slow chemical reaction in solution is analyzed in a general form, which admits a change in their limiting stages. The main feature of polarization curves for the electrochemical processes is the existence of two Tafel portions with slopes corresponding to a slow homogeneous chemical reaction (lower portion) and a preceding faster electrochemical stage (upper portion with a higher slope).     

全氟萘烷的化学还原与电化学还原

全氟碳化合物 ( PFCs)是分子中与碳原子相连的氢 (官能团中的除外 )全部被氟原子取代的有机氟化合物 .由于氟元素的电负性最大 ,所以 C— F键的键能很大 ( 4 80～ 5 30 k J/mol) ;PFCs与相应的碳氢化合物相比 ,C— F键的键长 ( 0 .1 3nm)与 C— H键的键长 ( 0 .1 nm)接近 ,而且氟原子的范德华半径( 0 .1 5 nm)与氢原子的范德华半径 ( 0 .1 2 nm)也非常接近 ,所以当碳氢化合物中的氢原子被氟原子取代而形成全氟碳化合物后 ,结构上不会发生太大的变化 [1] ;但是全氟碳化合物的物理化学性质与原来碳氢化合物的物理化学性质有显著差异 ,表…     

Advances and approaches for chemical recycling of plastic waste

The global production and consumption of plastics has increased at an alarming rate over the last few decades. The accumulation of pervasive and persistent waste plastic has concomitantly increased in landfills and the environment. The societal, ecological, and economic problems of plastic waste/pollution demand immediate and decisive action. In 2015, only 9% of plastic waste was successfully recycled in the United States. The major current recycling processes focus on the mechanical recycling of plastic waste; however, even this process is limited by the sorting/pretreatment of plastic waste and degradation of plastics during the process. An alternative to mechanical processes is chemical recycling of plastic waste. Efficient chemical recycling would allow for the production of feedstocks for various uses including fuels and chemical feedstocks to replace petrochemicals. This review focuses on the most recent advances for the chemical recycling of three major polymers found in plastic waste: PET, PE, and PP. Commercial processes for recycling hydrolysable polymers like polyesters or polyamides, polyolefins, or mixed waste streams are also discussed.     

Role of quantum chemical calculations in molecular biophysics with a historical perspective

We discuss how the basic principles of quantum chemistry and quantum mechanics can be and have been applied to a variety of problems in molecular biophysics. First, the historical development of quantum concepts in biophysics is discussed. Next, we describe a series of interesting applications of quantum chemical methods for studying biologically active molecules, molecular structures, and some of the important processes which play a role in living organisms. We discuss the application of quantum chemistry to such processes as energy storage and transformation, and the transmission of genetic information. Quantum chemical approaches are essential to comprehend and understand the molecular nature of these processes. To conclude our work, we present a short discussion of the perspectives of quantum chemical methods in modern biophysics, the field of experimental and theoretical chiral vibrational and electronic spectroscopy.     

Physical chemistry of plasma-solution systems

The basic physical, physicochemical, and chemical processes occurring in the plasma-solution systems are considered. Data on correlation between the emission intensity of electrolyte-cathode glow discharge and the rate of nonequilibrium discharge-induced vaporization of the solution are presented. A mechanism for the appearance of the atomic emission threshold of metal atoms in the plasma zone is proposed. The role of chemically active species generated by ion bombardment in chemical processes occurring in solutions is shown.     

可调变流体与绿色化工过程

介绍了可调变流体特性及其在绿色化工过程中的应用。重点介绍了利用超临界流体(主要是超临界C02)、亚临界水和气体(主要是CO2)膨胀的流体这三类可调变流体进行绿色化工过程设计的特点与途径。     

The need for the historical understanding of nature in physics and chemistry

During the last decades the physico-chemical conception of self-organization of chemical systems has been created. The chemical systems in natural-historical processes do not have any creator: they rise up from irreversible processes by self-organization. The issue of self-organization in physics has led to a new interpretation of the laws of nature. As Ilya Prigogine has shown, they do not express certainties but possibilities and describe a world that must be understood in a historical way. In the new philosophical understanding of nature priority is not ascribed to any single type or level of entity, but to historical processes, to processes of endless generation and change.     

Chemical Modifiers Based on Platinum-Group Metal Compounds in Electrothermal Atomic Absorption Spectrometry

Mechanisms of the action of chemical modifiers based on platinum-group metals have been considered. It has been shown that the efficiency of a chemical modifier is determined mainly by chemical processes occurring at the pyrolysis step. By combining the results obtained using different methods, these processes have been described step-by-step. The systematic study of Pd, Pt, Rh, Ru, and Ir in chloride and sulfate media as chemical modifiers has revealed a correlation between the relative efficiencies and some chemical properties of the modifiers. It has been shown that, in the presence of matrices weakly interacting with platinum-group metals (for example, sodium chloride), the best modifiers are metals that most intensely interact with the analytes (ruthenium and iridium in determining metalloids). However, if the chemical modifier strongly interacts with the sample matrix, the efficiency of the modifier is determined by the interaction processes. For example, in the presence of a sulfate matrix capable of reacting with platinum-group metals, the best modifier is palladium. The correlations found may be useful for the practical application of platinum-group metals as chemical modifiers in the analysis of complex samples by electrothermal atomic absorption spectrometry.     

化学平衡的多重性、稳定性和重现性

利用动力学方法讨论了非理想的化学反应体系中化学平衡态的多重性、稳定性和实验上的可重现性。分析了实验结果(化学平衡态)与初始条件以及其它动力学过程之间的依赖关系,并简略讨论了化学平衡多重性和稳定性问题在某些实际问题和工程设计中的重要性。     

Comparative study of ion kinetic energy,chemical ionisation and field desorption spectra

A comparison of the fragmentation processes operating in the first field free region was made with the fragmentation in the ion source under electron ionisation, chemical ionisation and field desorption conditions for some selected compounds which undergo retro-DielsI-Alder fragmentation in the ion source under electron ionisationconditions. The fragmentation processes which com-ete with retro-Diels-Alder fragmentation under chemical ionisation and field desorption conditions are discussed. The complementary nature of these techniques are illustrated.