Bifunctional Catalyst Control of Alkene Isomerization

The ability to control the formation and chemistry of alkenes is of central importance to organic synthesis in both industry and academia. Progress in using catalysts with bifunctional (heteroaryl)phosphines to control positional and/or geometric selectivity in alkene isomerization and related chemistry is summarized.

     

绿色化学的研究现状及进展

绿色化学又称环境无害化学、环境友好化学、清洁化学,是当今国际化学科学研究的前沿课题,其目的是将现有化工生产技术路线从“先污染,后治理”改为“从源头上根除污染”。绿色化学具有良好的现实经济效益和深远的社会效益,是知识经济时代化学工业发展的必然趋势。介绍了绿色化学的发展现状,并对其发展方向提出了一些见解。     

点击化学在高分子研究中的进展

首先概括了点击化学的概念、特征和类型,然后对其在高分子研究中的进展进行了综述。详细地梳理了点击化学与新型聚合方法的联用以及点击化学在合成功能聚合物和控制聚合物拓扑结构方面的应用与研究。     

新建本科院校环境化学课程教学探讨

环境化学是化学化工类专业的重要专业课,是提高学生环境保护意识和污染治理能力的重要途径,是社会实现可持续发展的关键。文章依据新建本科院校的现状,结合环境化学课程的特点和新建本科院校应用型人才培养的要求,对环境化学课程的教学模式进行了探索。     

工科院校环境专业有机化学的教学探讨

有机化学是环境专业重要基础课程之一。掌握扎实的有机化学基础知识和基本技能是环境专业学生今后进行环境保护特别是有机物污染的控制和改善的关键。文章针对工科院校环境专业学生的特点及有机化学学科特点,结合教师自身教学的经验和体会,从教学过程的薰要三环节即备课—授课-实验着手,对如何提高有机化学课堂教学效果进行了探讨。     

过渡金属醇盐溶胶-凝胶化学进展

介绍过渡金属醇盐 ( TMA)溶胶 -凝胶 ( sol- gel)化学基本知识 ,着重讨论在 TMAsol- gel过程中化学控制方法和分子改性方法 ,并指出其研究的重要意义和前景     

高校化学实验室污染物调查及治理

对高校化学实验室开设实验项目过程中产生的污染物"三废"(废水、废气、废渣)的原因、种类、数量、性质等进行调查统计。统计数据来源于甘肃省某高校的分析化学实验、无机化学实验、有机化学实验、仪器分析实验、环境分析和食品分析等6门实验课所开实验项目,最终分析了污染物产生的原因,提出治理方案,以期加强高校化学实验室的污染控制,推动化学实验室的教学改革,保护环境。     

Reversible control of biomaterial properties for dynamically tuning cell behavior

In the past decade, significant advances in chemistry and manufacturing have enabled the development of increasingly complex and controllable biomaterials. A key innovation is the design of dynamic biomaterials that allow for user-specified, reversible, temporal control over material properties. In this review, we provide an overview of recent advancements in reversible biomaterials, including control of stiffness, chemistry, ligand presentation, and topography. These systems have wide-ranging applications within biomedical engineering, including in vitro disease models and tissue-engineered scaffolds to guide multistep biological processes.     

When Supramolecular Chemistry Meets Chemical Biology: New Strategies to Target Proteins through Host-Guest Interactions

Supramolecular chemistry for targeting proteins is of great interest for the development of novel approaches to recognize, isolate and control proteins. Taking advantage of chemical biology approaches, such as genetic-code expansion and enzyme-mediated ligation, guest recognition elements can be built into proteins of interest, allowing supramolecular control of protein function and regulation. In this viewpoint article, we will discuss the methods, applications, limitations, and future perspectives of supramolecular chemistry for targeting proteins in a site-specific manner.     

Effects of aging on polyimide: A study of bulk and interface chemistry

We are investigating the bulk and interfacial chemistry of polyimide (PI) exposed to heat and relative humidity (RH) stress (85°C/85% RH) over long periods to understand the long-term reliability aspects of PI for microelectronic applications. The PI surface chemistry and the PI–Si interface chemistry was followed with electron spectroscopy for chemical analysis (ESCA). For exposure times greater than 550 h, the PI surface exhibits significant changes in emission structure and atomic concentration. The PI–Si interface indicates little change in the PI chemistry when compared to control samples. The water-contact angle at the PI surface shows no statistically significant change as a function of exposure time. Bulk and surface chemistry were followed with Fourier transform infrared spectroscopy (FTIR) in a grazing incidence reflection configuration. There were measurable differences in FTIR spectra between aged and control samples only for the case of very thin PI layers. These results suggest that for exposure times of less than 1100 h, chemical changes in PI occur primarily at the PI–air interface for samples 1 μm thick and greater. These changes represent a possible rearrangement of the imide structure and may be a form of deimidization of the polymer, but the final state is not polyamic acid. The PI surface chemistry changes observed with ESCA are reversible upon reheating to the cure temperature.     

Surface and interfacial chemistry

Based on a molecular approach combining controlled surface chemistry, advanced spectroscopic methods, in particular solid-state NMR, and computational chemistry, it is possible to develop single-site species and to control the growth of nanoparticles on supports. This allows the generation of highly efficient catalysts combining the advantages of both homogeneous and heterogeneous catalysts and function materials with defined properties.     

Synthesis and functionalization of nanoengineered materials using click chemistry

The synthesis of nanoengineered materials with precise control over material composition, architecture and functionality is integral to advances in diverse fields, including biomedicine. Over the last 10 years, click chemistry has emerged as a prominent and versatile approach to engineer materials with specific properties. Herein, we highlight the application of click chemistry for the synthesis of nanoengineered materials, ranging from ultrathin films to delivery systems such as polymersomes, dendrimers and capsules. In addition, we discuss the use of click chemistry for functionalizing such materials, focusing on modifications aimed at biomedical applications.     

The role of fuel chemistry in dictating nanostructure evolution of soot toward source identification

Abstract

Laser derivatization is proposed as a diagnostic technique toward identifying the sources contributing to combustion produced soot. Fuel chemistry and the resultant oxygen content in nascent soot have been shown to influence the evolution of soot nanostructure upon laser derivatization. This is illustrated using the spectroscopic and microscopic characterization of biodiesel soot, with a systematic variation in fuel chemistry used to generate the soot. Functionalized carbon black is used as the control to independently verify the influence of material chemistry on nanostructure upon laser heat treatment. Results track with those observed for biodiesel soot. Reciprocally, the similarity in soot nanostructure observed after laser heating is tied to the likeness in fuel chemistry of biomass-fueled sources. Understanding the origin of differences or similarities in soot nanostructure upon laser heat treatment can help differentiate sources based on their contribution, thereby aiding in effective air quality control.

Copyright © 2019 American Association for Aerosol Research     

对天然药物化学双语教学质量控制的几点实践

天然药物化学课实行双语教学对提高学生的专业知识和英语水平具有重要的现实意义。通过具体的教学实践,探讨了药学专业天然药物化学双语教学的方法、步骤和措施。为双语教学课程建设质量控制提供参考和借鉴。     

Characterization of titanium alkoxide sol–gel systems designed for anti-icing coatings: I. Chemistry

Recent interest in sol–gel chemistry involving titanium alkoxide precursors has been prompted by the ability to control the morphology of the final TiO₂ structure. The ligands used in these processes are typically sacrificial and are removed once the process is complete. In contrast, the sol–gel chemistry presented here is used to facilitate the slow release of the attached alkoxide ligands: tripropylene glycol (TPG) and glycerol. These compounds are first chemically reacted with titanium isopropoxide (TIP), then are slowly released through subsequent hydrolysis and condensation reactions. TPG and glycerol depress the freezing point of water and this sol–gel chemistry has been incorporated into a coating which has anti-icing properties. This article analyzes the precursor chemistry for various experimental conditions using TGA, FTIR, ¹H NMR, and model calculations.     

Externally stimulated click reactions for macromolecular syntheses

Over the last decade, click chemistry reactions, that are fast, simple to use, easy to purify, versatile, regiospecific, and give high product yields have gained significant importance for synthetic chemistry. The design of these synthetic tools that can be controlled by external stimuli such as microwave, ultrasound, light or electric pulses is a research area with strong interest for modern chemistry. In this contribution, the potential of externally stimulated click reactions in the preparation of various macromolecular structures are discussed along with the selected examples. Considering classical click reactions, external stimulation provides a number of advantages and goals, such as programmable synthesis and precise control over complex and multicomponent systems. Furthermore, these click reactions bring some improvements or overcome existing problems of present click reactions, such as toxicity, irreversible oxidation of catalyst and lack of spatiotemporal control over the reaction initiation. Due to these features, externally stimulated click reactions have various applications in a wide variety of research areas, including materials sciences, polymer chemistry, and pharmaceutical science. The next generation click reactions enable chemists to finally harness available chemical diversity for the sequence-programmable synthesis and modification of macromolecular materials.     

Structural and morphological control of cationic surfactant-templated mesoporous silica

Micelle-templated mesoporous silica materials are rapidly becoming important in many fields of chemistry for hosting reactants or catalysts in confined space. Fine control of the pore size, wall structure, surface functionalization, defects, and morphology is needed for fine-tuning the pores as nanoreactors. We review the physical chemistry of solution silicate species and surfactants in the synthesis of mesoporous silicas. Controls in surfactant packing and liquid crystalline phase transformation can lead to various tailored synthesis strategies. Postsynthesis treatments further make more stable mesoporous materials.     

晶体化学在氧化铜矿物浮选中的应用研究进展

晶体化学是矿物分选的重要理论基础之一,在矿物浮选领域中发挥着重要作用. 本工作总结了晶体化学的研究内容及其在氧化铜矿物浮选中的应用,介绍了氧化铜矿物晶体结构特征、表面特性及可浮性研究现状,综述了晶体化学在氧化铜矿物浮选药剂作用机理研究及浮选条件控制等方面的应用,指出了晶体化学在矿物浮选中的应用研究方向.     

Reticular Chemistry of Multifunctional Metal-Organic Framework Materials

Metal-organic frameworks (MOFs) are crystalline solids constructed by means of reticular chemistry (refers to the connection of molecular building units via strong bonds to make extended structures), which is currently one of the most rapidly expanding platforms for new functional materials. Rational combinations of various building units enable MOFs to show tailorable pore structures. Based on well-established approaches, including the control over pore size and pore chemistry, immobilization of functional sites, post-synthetic modification, and multivariate complex, multifunctional MOFs can be readily synthesized. In this brief review, we summarize and highlight our research progress in MOF chemistry on applications including gas storage, gas separations, optical response, chemical sensing, proton conduction, and molecular recognitions.     

Direct and Indirect Effects of Invasive Plants on Soil Chemistry and Ecosystem Function

Invasive plants have a multitude of impacts on plant communities through their direct and indirect effects on soil chemistry and ecosystem function. For example, plants modify the soil environment through root exudates that affect soil structure, and mobilize and/or chelate nutrients. The long-term impact of litter and root exudates can modify soil nutrient pools, and there is evidence that invasive plant species may alter nutrient cycles differently from native species. The effects of plants on ecosystem biogeochemistry may be caused by differences in leaf tissue nutrient stoichiometry or secondary metabolites, although evidence for the importance of allelochemicals in driving these processes is lacking. Some invasive species may gain a competitive advantage through the release of compounds or combinations of compounds that are unique to the invaded community—the “novel weapons hypothesis.” Invasive plants also can exert profound impact on plant communities indirectly through the herbicides used to control them. Glyphosate, the most widely used herbicide in the world, often is used to help control invasive weeds, and generally is considered to have minimal environmental impacts. Most studies show little to no effect of glyphosate and other herbicides on soil microbial communities. However, herbicide applications can reduce or promote rhizobium nodulation and mycorrhiza formation. Herbicide drift can affect the growth of non-target plants, and glyphosate and other herbicides can impact significantly the secondary chemistry of plants at sublethal doses. In summary, the literature indicates that invasive species can alter the biogeochemistry of ecosystems, that secondary metabolites released by invasive species may play important roles in soil chemistry as well as plant-plant and plant-microbe interactions, and that the herbicides used to control invasive species can impact plant chemistry and ecosystems in ways that have yet to be fully explored.