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Progress in Chemistry 2012, No.10 Previous issue Next issue

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Nonlinear Optical Spectroscopy Studies on Water and Electrolyte Aqueous Solution Interfaces——Specific Ion Effect at Air/ Electrolyte Aqueous Solution Interfaces
Deng Ganghua, Wang Hongfei, Guo Yuan
2012, (10): 1865-1879 |
Published: 24 October 2012
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Abstract
Water and electrolyte aqueous solution interfaces play crucial roles in many processes of physics, chemistry, environment, and biology. People have attempted to understand the structure and dynamics of water and electrolyte aqueous solution interfaces for decades. Recently, both experimental and theoretical studies have proved that larger and more polarizable anions attend to accumulate at the interface and affect the interfacial water hydrogen bonding structure. In this review,we present recent progress of nonlinear optical spectroscopy studies on water and electrolyte aqueous solution interfaces with nonresonant second harmonic generation(SHG) and sum frequency generation vibrational spectroscopy(SFG-VS). First, we addressed the signal source of the nonresonant second harmonic generation of the air/water interface. Analysis of the experimental results showed that the SHG signal of the air/water interface can be treated fully only with dipolar contribution, which lay the foundation of nonresonant second harmonic generation in studying water and electrolyte aqueous solution interfaces. We then utilized the polarization and molecular symmetry analyses to assign the SFG-VS spectra peaks to different interfacial species at the air/water interface. These results provide detailed informations on the orientation, structure, and dynamics of water molecules at the air/water interface. Subsequently, we studied several kinds of electrolyte aqueous solution interfaces by nonresonant SHG and SFG-VS. These results showed that not only the larger and more polarizable Br-anion, but also the smaller and less polarizable Cl-,F- anions are enriched at the air/water interface and increased the interfacial thickness. Furthermore, we also observed the specific Na+, K+ cation effect on the interfacial thickness and interfacial water hydrogen bonging structure. Contents 1 Introduction
2 Basic theory of SHG, SFG and experimental setup
2.1 Basic theory of SHG, SFG
2.2 Experimental setup
3 Interfacial water structure of air/neat water interface
3.1 Source of SHG signal from air/neat water
3.2 Interfacial water structure and motion of the free OH bond
4 Specific ion effect at air/electrolyte aqueous solution interfaces
4.1 Anion effects
4.2 Cation effects
5 Conclusion and Outlook
Review
Development of Energy Upconversion Based on Triplet-Triplet Annihilation
Zhang Xinglin, Yang Huiran, Sun Huibin, Liu Shujuan, Zhao Qiang*, Huang Wei*
2012, (10): 1880-1889 |
Published: 24 October 2012
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Abstract
Energy upconversion based on triplet-triplet annihilation (TTA) has attracted much attention due to its potential applications in different fields, such as photovoltaics, photosynthesis, photocatalysis, bioimaging, etc. It exhibits many merits, such as excitation with non-coherent light sources, low excitation power density, and tunable excitation and emission wavelength simply by independent selection of the sensitizer and the acceptor during the upconversion process. Hence, TTA-based energy upconversion is now an emerging technique which has a promising future. Herein, the principle of TTA-based upconversion and the requirements of the sensitizer and its corresponding acceptor have been discussed. Besides, the examples of the sensitizer molecules, including iridium complexes, palladium complexes, platinum complexes, ruthenium complexes as well as organic molecules, and their corresponding acceptor molecules are summarized. Meanwhile, the existing problems and the direction of future development of TTA-based upconversion have also been outlined in this review. Contents 1 Introduction
2 The principle of TTA based upconversion
3 Requirements for the sensitizer and acceptor molecules
4 Examples of the sensitizer and acceptor molecules
4.1 Iridium complexes as sensitizer and the corresponding acceptors
4.2 Palladium complexes as sensitizer and the corresponding acceptors
4.3 Platinum complexes as sensitizer and the corresponding acceptors
4.4 Ruthenium complexes as sensitizer and the corresponding acceptors
4.5 Organic molecules as sensitizer and the corresponding acceptors
5 Conclusion and outlook
Coarse-Grained Molecular Dynamics Simulation of Surfactants in Aqueous Solution
Chen Jingfei, Hao Jingcheng
2012, (10): 1890-1896 |
Published: 24 October 2012
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Abstract
Molecular dynamics simulation has already become one of the indispensable ways to explore the surfactant aggregates in solution. Recent years, coarse-grained methods can both reproduce thermodynamics and structure properties for surfactant systems and extend time and space scale of simulation for overcoming the shortcoming of mesoscale simulation and atomic-scale simulations, which have become one of the focus in the field of computational chemistry. The latest development of coarse-grained molecular dynamics simulation of surfactants in solution is reviewed briefly in this paper. For each coarse-grained model, the modeling strategy, potential expressions, parameter fitting, and evaluation of force field are introduced in detail, followed by the illustration of validity of coarse-grained force field in surfactant systems. Finally, we also discuss some unresolved critical problems in surfactant coarse-grained models, which would be significant to the further development of coarse-grained simulation in surfactant systems. Contents 1 Introduction
2 Martini coarse grained force field
2.1 Non-bonded interaction
2.2 Bonded interaction
2.3 Simulating surfactant self-assembly with martini force field
3 Shinoda et al. coarse grained force field
4 Other coarse grained methods
5 Conclusion and outlook
Photoelectrocatalytic Reduction of CO2
Zhou Tianchen, He Chuan, Zhang Yanan, Zhao Guohua*
2012, (10): 1897-1905 |
Published: 24 October 2012
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Abstract
Carbon dioxide (CO2) is a main component part of greenhouse gases. Since catalytic reduction of CO2 to hydrocarbon fuels can realize the recyclable utilization of carbon materials, this topic has been intensively looked into. In this article, the recent progress on the conversion of CO2 has been reviewed and discussed in detail by comparing and analyzing the catalytic efficiency and catalytic selectivity of different methods, three of which, photocatalytic reduction, electrocatalytic reduction, and photoelectrocatalytic reduction are covered. The respective catalysis mechanisms of each method,as well as the effects of different catalysts and catalytic systems on reduction of CO2 have been described. According to previous studies in this area, catalytic performance, photo-electric converting,catalytic selectivity, and energy consumption are the primary criteria on evaluating the method of reduction of CO2. On this basis, the advantages and disadvantages of catalysts and methods for reducing CO2 to useable energy are summarized and analyzed. In the last part of the article, prospects and challenges for the further development in this field are presented. Contents 1 Introduction
2 Photocatalytic reduction of CO2
2.1 TiO2-based photo-catalytic system
2.2 Ternary metal oxide photo-catalytic system
2.3 Metal complex photo-catalytic system
3 Electrocatalytic reduction of CO2
3.1 Metal electro-catalytic system
3.2 Metal complex electro-catalytic system
3.3 Ionic liquid electrochemical reaction system
4 Photoelectrocatalytic reduction of CO2
5 Outlook
Catalyst Layer Structure of Membrane Electrode Assemblies in PEMFC
Wang Jiashu, Pan Guoshun, Guo Dan
2012, (10): 1906-1914 |
Published: 24 October 2012
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Abstract
Catalyst layer is the key component of membrane electrode assembly (MEA), which is the heart of polymer electrolyte membrane fuel cell (PEMFC). Catalyst layer can provide sites for the electrochemical reaction, and channels for proton, electron, gas and water. Therefore it affects the cost and properties of PEMFC. This paper reviews recent progress of catalyst layer structure. The important effects of the content of Nafion, the characteristics of solvent and additive on the structures and performances of MEA are introduced. In addition, the progress of hot-press parameters and coating methods of the catalyst layers during the preparation of MEA are also discussed. Contents 1 Introduction
2 Catalyst layer structure research
2.1 The micro porosity of catalyst layer
2.2 The effects of Nafion percentage on catalyst layer
2.3 The effects of solvent on catalyst layer
2.4 The effects of additives on catalyst layer
2.5 Coating methods and hot-pressing parameters
3 Conclusion and outlook
Fluorescent Sensor Arrays
Liu Yuan, Ding Liping*, Cao Yuan, Fang Yu
2012, (10): 1915-1927 |
Published: 24 October 2012
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Abstract
Sensor arrays are developed based on the knowledge of olfactory systems and have become a powerful tool in the field of molecular recognition. Sensor arrays are comprised of a series of sensor elements which generate a specific recognition pattern for each analyte. This advantage provides sensor arrays discriminatory power to identify chemically or structurally similar analytes and even complex mixed samples. Due to the high sensitivity, no need of reference systems, multiple signals, and ability to be visualized, fluorescent sensor arrays have obtained increasing attention in the field of sensor arrays. The present review introduces the advances in the fluorescent sensor arrays which can be classified into solution-based arrays, particle-based arrays and film-based arrays according to the type of the sensor elements utilized. The design strategy and sensing mechanism of fluorescent sensor arrays and their applications in the field of recognition of metal ions, organic chemicals and biomolecules are highlighted. Contents 1 Introduction
2 Solution-based fluorescent sensor arrays
2.1 Small fluorophores as sensor element
2.2 Fluorescent conjugated polymer as sensor element
3 Particle-based fluorescent sensor arrays
3.1 Imprinted fluorescent mesoporous silica as sensor element
3.2 Fluorescent gold nanoparticles as sensor element
3.3 Polyfluorophore DNA-modified PEG-PS beads as sensor element
4 Film-based fluorescent sensor arrays
4.1 Physisorbed film as sensor element
4.2 Chemically-assembled film as sensor element
5 Conclusion and outlook
Ionic Liquids in Pharmaceuticals
Yang Tingting, Gao Guohua*
2012, (10): 1928-1935 |
Published: 24 October 2012
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Abstract
In order to solve the problems associated with the solid form of conventional pharmaceuticals including polymorphic conversion, low solubility, low bioavailability, and the tendency of amorphous forms to spontaneously crystallize, the liquid form pharmaceuticals have attracted much attention. Recent developments of ionic liquids (ionic liquids are loosely defined as salts with melting points below 100℃) might prove beneficial. Ionic liquids exhibit controlled solubility, unique surface activity, high thermostability and enhancement in bioavailability or bioactivity, which make ionic liquids have the advantage of elimination of polymorphism, new delivery options, or having customized pharmaceutical cocktails. In some cases, an active cation and an active anion can be combined to produce a liquid possessing dual functionality. These make ionic liquids have the possibility of being used in the pharmaceutical industry. The aim of this mini-review is to summarize the recent development of ionic liquids as active pharmaceutical ingredients, antimicrobial agents and agriculture chemicals, and discuss the existing problems and the future research of ionic liquids in pharmaceuticals. Contents 1 Introduction
2 Ionic liquids as active pharmaceutical ingredients
3 Ionic liquids as antimicrobial agents
3.1 Antimicrobial activity of imidazolium and pyridinium ionic liquids
3.2 Antimicrobial activity of other kinds of ionic liquids
4 Ionic liquids as agriculture chemicals
5 Conclusion and outlook
Organizing Functional Nanomaterials with DNA Origami
Wang Jinye, Song Chen, Xu Jingkun, Ding Baoquan
2012, (10): 1936-1945 |
Published: 24 October 2012
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Abstract
DNA origami,an efficient self-assembly technique, has shown great potential for applications in biomedicine, biosensing, nanooptoelectronic device and nanophotonics. It has received strong attention from researchers in a wide range of fields. The programmability and three dimensional addressability of DNA origami architectures have been utilized to precisely organize various functional groups, such as metallic nanoparticles, semiconducting nanoparticles,protein molecules and single-wall carbon nanotubes. Meanwhile, DNA origami structures have also been employed to investigate single molecule reactions on them, such as label-free RNA hybridization, formation and break of a chemical bond and distance-dependent multivalent ligand-protein binding. In the present paper, the research progress of organizing functional nanomaterials with DNA origami are reviewed, and the challenges and application prospects are discussed. Contents 1 Introduction
2 Functional groups organized by DNA origami
2.1 Metallic nanoparticles and semiconducting quantum dots self-assembled on DNA origami
2.2 Protein molecules self-assembled on DNA origami
2.3 Single-wall carbon nanotubes self-assembled on DNA origami
3 DNA origami combining with lithography technology
4 DNA origami for single-molecule reaction detection
5 Conclusion and outlook
Adhesive Materials Inspired by Gecko and Mussel
Liu Juan, Yang Qinglin*, Xu Jingjing, Liu Kesong*, Guo Lin, Jiang Lei
2012, (10): 1946-1954 |
Published: 24 October 2012
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Abstract
After four and a half billion year evolution, creatures in nature possess almost perfect structures and properties, exhibiting the harmonization and unification between structure and function. Adhesive materials have a wide variety of practical applications in biomedical sciences, construction industry, and other fields. Inspired by biomaterials (such as gecko, mussel) with the special adhesive property, great effort has been devoted to fabricating bio-inspired adhesive materials. According to the adhesive mechanism, adhesive materials can be classified in two categories, reversible adhesion and permanent adhesion. For the gecko, the reversible adhesion can be attributed to the cooperation of micro/nano hierarchical structures of gecko toes and van der Waal’s force between solid surfaces and keratinous setae. For the mussel, the glue proteins secreted by marine mussels can bind strongly to all inorganic and organic surfaces in aqueous environments. This review summarizes the recent work in biomaterials with special adhesion and the corresponding bio-inspired adhesive materials, with a focus on the gecko and mussel. The research prospects and directions of bio-inspired adhesive materials in the future are also briefly addressed. Contents 1 Introduction
2 Reversible bonding of hierarchical structure
2.1 Adhesion of gecko's feet
2.2 Adhesion of some other animals' feet
2.3 Adhesive surfaces inspired by multi-scale structure
3 Permanent bonding of biomacromolecules
3.1 Underwater adhesion of mussels
3.2 Adhesion of some other aquatic organisms
3.3 Biomimetic adhesive polymers
4 Conclusions and outlook
Silver-Assisted Chemical Etching of Semiconductor Materials
Geng Xuewen, He Chunlin, Xu Shichong, Li Jungang, Zhu Lijuan, Zhao Liancheng
2012, (10): 1955-1965 |
Published: 24 October 2012
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Abstract
Semiconductors with various structural morphologies are widely used in areas of electronics, optoelectronics, photovoltaics, sensors and thermoelectrics. The fabrication of solid-state micro/nanostructures has been motivated by the miniaturization and multi-functionality of microelectronic devices. Although some traditional methods can be used for texturization treatment of semiconductors, their applications are limited to some extent owing to their intrinsic disadvantages. Recently, the technologies of noble metal-assisted chemical etching (MacEtch) of semiconductors to produce micro/nanostructures have been paid much attention due to their relatively simple processes, fast reacting rate, low cost, and applicability for mass production etc. In this review, firstly, the MacEtch mechanisms, reaction phenomena and effect factors (including the depositing methods, distribution, sizes, shape of Ag particles, and the composition of etchants) of Ag-assisted chemical etching of Si semiconductor are discussed in detail. And then the fabrication technologies of various microstructures such as porous Si, Si nanostructures, silicon nanowire arrays, and quasi-ordered micro/nanostructures are introduced to highlight the salient features of MacEtch of Si, and the state-of-the-art MacEtch of other semiconductors such as Ge, Si1-xGex, and GaAs is also summarized. Meantime, the potential applications of the MacEtch of semiconductors in different fields are overviewed. Finally, the current issues are analyzed and the outlook for the further research in this field is proposed. Contents 1 Introduction
2 Mechanism, phenomena, and effect factors of Ag-assisted chemical etching of Si
2.1 Mechanism of Ag-assisted chemical etching of Si
2.2 Effect factors of MacEtch and corresponding morphologies
2.3 Analysis of MacEtch phenomena
3 Ag particles-assisted chemical etching of semic-onductors to produce microstructures
3.1 MacEtch of Si
3.2 MacEtch of Ge
3.3 MacEtch of Si1-xGex
3.4 MacEtch of GaAs
4 Applications of Ag-assisted chemical etching of semiconductors
4.1 Applications of fabrication technologies of microstructures on Si surfaces in solar cells
4.2 Fabrication and applications of metal/semiconductor composite structures
4.3 Fabrication and applications of porous Si/SiNWs composite structures
4.4 Fabrication of hydrophobic and hydrophilic structures
4.5 Secondary MacEtch technologies and their applications
4.6 MacEtch by using dual metals
5 Conclusions and outlook
Myocardial Perfusion Imaging Agents for Positron Emission Tomography
Mou Tiantian, Zhang Xianzhong*
2012, (10): 1966-1973 |
Published: 24 October 2012
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Abstract
Positron emission tomography (PET) provides certain advantages on myocardial perfusion imaging, such as higher resolution, greater sensitivity, lower tissue attenuation, and absolute quantification of myocardial blood flow, etc. Therefore the research on PET myocardial perfusion imaging agents has caused great concern recently. The current PET agents for myocardial perfusion used in clinic are introduced and commented. The advances in 18F and other positron nuclides labeled PET myocardial perfusion imaging agents are reviewed respectively. Several 18F-labeled lipophilic cations and analogues of mitochondrial complex I (MC-Ⅰ) inhibitors as potential myocardial perfusion imaging agents are discussed in detail. Particularly highlighted the 18F -labeled analogues of MC-Ⅰ inhibitors, such as BMS-747158-02 and [18F] FP1OP, which have been made breakthrough progress recently. The biological properties and myocardial uptake mechanism of PET myocardial perfusion imaging agents are also introduced, and their advantages and disadvantages are compared. The trend for developing PET myocardial perfusion imaging agents is proposed in this paper as well. Contents 1 Introduction
2 PET myocardial perfusion agents in clinic
3 18F -labeled PET myocardial perfusion agents
3.1 18F -labeled lipophilic cations
3.2 18F -labeled analogues of MC-Ⅰ inhibitors
4 Other radionuclides labeled PET myocardial perfusion imaging agents
5 Conclusion and outlook
Synthesis of Azaindoles
Wang Zhihui*, Wang Xiao
2012, (10): 1974-1982 |
Published: 24 October 2012
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Abstract
Azaindoles belong to a kind of very important heterocycles, which play a role in material science and drug design and synthesis. Since azaindoles have the different molecular structure compared to indole, many kinds of indole syntheses don’t work so efficiently. Recently, the development of organometallic chemistry has supported the azaindole synthesis with more kinds of starting material and more powerful ways to build up the cyclic structure of azaindoles, so it has made the new possibilities to synthesize azaindoles. We have surveyed the development of azaindole synthesis recently. Several ways for the azaindole synthesis, such as Bartoli synthesis, Fischer indole synthesis, organolithium methods, transition-metal mediated methods and so on, have been introduced. This review summarized the very useful methods to synthesize many kinds of azaindoles (4-azaindole, 5-azaindole, 6-azaindole and 7-azaindole), that will be helpful for the application of azaindole compounds in material science and pharmaceutical synthetic chemistry. Contents 1 Introduction
2 Bartoli synthesis
3 Fischer indole synthesis
4 Organolithium methods
5 Transition-metal mediated methods
5.1 From alkynes to azaindoles
5.2 From alkenes to azaindoles catalyzed by Pd
5.3 From aldehydes, ketones or enol ethers to azaindoles
6 Other ways
7 Conclusion
Synthesis of 1, 2, 3-Triazole Derivatives
Jiang Yubo, Kuang Chunxiang
2012, (10): 1983-1994 |
Published: 24 October 2012
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Abstract
Much attention has been paid to the synthesis of 1,2,3-trizaole derivatives with the development of its wide applications in the fields of medicine, pesticide, and materials. This review describs the synthesis history of the 1,2,3-triazole derivatives and focuses on Cu-catalyzed synthesis of 1,4-disubstitued-1,2,3-triazoles, Ru-catalyzed synthesis of 1,5-disubstitued-1,2,3-triazoles, and other new methods in recent 10 years. Relevant mechanisms and applications of some reactions are also described. Finally, the further work needed to do and the development trends in the field of 1,2,3-triazole derivative synthesis are proposed. Contents 1 Introduction
2 Synthesis of 1,2,3-triazole derivatives
2.1 Huisgen cycloaddition reactions
2.2 Cu-catalyzed Huisgen cycloaddition reactions
2.3 Ru-catalyzed methods
2.4 Metallic acetylide methods
2.5 Organocatalytic methods
2.6 Activated alkynes methods
2.7 Other methods
3 Conclusion and outlook
CO2-Stimuli Responsive Polymers
Feng Anchao, Yan Qiang, Yuan Jinying*
2012, (10): 1995-2003 |
Published: 24 October 2012
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Abstract
CO2-stimuli responsive polymers are a class of newly developed smart stimuli responsive polymers, which usually refers to the polymers possessing reversible changes upon admission and emission of CO2. Since the regulation process only involves CO2 and inert gases, without the introduction of other impurities, there are many potential applications in this field. This article summarized recent research progress on the preparation of CO2-stimuli responsive polymers,followed by the discussion of their self-assembly,classifying in accordance with the CO2-switchable groups,such as primary amine, amide and some specific polymer chains. The development prospect of this research field and its potential applications are also discussed. Contents 1 Introduction
2 Overview of CO2-responsive polymer
2.1 Primary amine/CO2 system
2.2 Amide/CO2 system
2.3 Specific polymer chain /CO2 system
3 Conclusion and outlook
Light-Induced Shape Memory Polymer Materials
Wu Yuanpeng, Lin Yuanhua, Zhou Ying, Zuo Fang, Zheng Zhaohui, Ding Xiaobin
2012, (10): 2004-2010 |
Published: 24 October 2012
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Abstract
The research of shape memory polymer is a hot topic in the field of smart polymers. In recent years, as an important kind of shape memory polymers, the light-induced shape memory polymers have attracted great interest from researchers due to their unique properties. In this article, the progress in light-induced shape memory polymers is reviewed. The unique advantages, memory mechanism, applications and research trend of the shape memory polymers are introduced. In terms of the shape memory mechanism, light-induced shape memory polymers can be divided into two types, one is based on photochemical reactions, the other is based on light-induced heating. The shape memory polymers based on the two memory mechanisms are reviewed in detail. The applications of these materials are also discussed. Finally, the problems in light-induced shape memory polymers are pointed out, and the future development and applications of the polymers are prospected. Contents 1 Introduction
2 Light-induced shape memory polymer materials
2.1 Light-induced chemical reactions
2.2 Light-induced heating
3 Applications of light-induced shape memory polymers
4 Conclusion and outlook
Application of Atomic Force Microscope to Polyolefin Research
Zhao Qiaoling, Ma Zhi*
2012, (10): 2011-2018 |
Published: 24 October 2012
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Abstract
Polyolefin material is universally applied in industry, agriculture, medical, military, daily life and other fields because of its excellent performance and low price. In order to widen the application of polyolefin material, the surface functionalized polyolefin, polyolefin blends with other materials and polyolefin/ nano-inorganic composites were developed and became the focus of this research field. Atomic force microscopy (AFM) is a technology detecting the surface morphology, physical and chemical information of materials through the interaction between an extremely sharp tip and material surface. AFM plays an important role in the above-mentioned research of polyolefin materials. The surface roughness is one of the most important parameters in the surface functionalization of polyolefin material. While, AFM technology is able to provide accurate information about the surface roughness of such functionalized polyolefin material. Because of AFM technology can directly observe the state of component mixing and phase separation, it becomes an important tool to investigate the polyolefin blends with other materials. In addition, AFM is an efficient method to characterize the morphology of micro- and nano-structural material. Thus, AFM finds its application in the crystallization of polyolefin materials. In this paper, the operating principle and modes of AFM are briefly introduced. The applications of AFM in the research of surface roughness, blend phase separation and crystal of polyolefin materials are mainly reviewed. Contents 1 Introduction
2 AFM technology
3 Application of AFM in polyolefin materials
3.1 Polyolefin surface
3.2 Polyolefin blend phase separation
3.3 Polyolefin crystal
4 Conclusion and Outlook
Recent Advances in Derivatization for Chromatographic Determination of Perfluoroalkyl Acids
Shan Guoqiang, Sun Huaihua, Hou Zheng, Zhu Lingyan
2012, (10): 2019-2027 |
Published: 24 October 2012
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Abstract
Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and related perfluoroalkyl acids (PFAAs) are a group of new emerging persistent organic pollutants, leading to concern over their effects on humans and wildlife. Since PFAAs have not ultraviolet or fluorescent chromophores and are hardly volatile, they can not be analyzed by conventional methods such as liquid chromatography with ultraviolet detection (UV) or fluorescent detection (FD) and gas chromatography (GC). Thus, analysis of PFAAs is mostly carried out by liquid chromatography-mass spectrometry (LC/MS), which is very expensive and can not be applied widely. Moreover, LC/MS suffers from matrix interferences and other problems. Thus, it is necessary to develop derivatization techniques for LC or GC chromatographic analysis of PFAAs. The progress in derivatization followed by chromatographic analysis for PFAAs is reviewed in this paper. Then, the advantages and disadvantages, application and significance of these methods are discussed. It is aimed to provide more information for further study. Contents 1 Introduction
2 Chemical derivatization of PFAAs
2.1 Derivatization of PFCAs
2.2 Derivatization of PFOS
3 Derivatization followed by LC analysis
3.1 LC/UV
3.2 LC/FD
4 Derivatization followed by GC analysis
4.1 GC/ECD (or FID)
4.2 GC/MS for PFAAs
4.3 GC/MS for isomers of PFAAs
4.4 GC/MS for precursor compounds of PFAAs
5 Conclusion and outlook
Diversity of the Modes for Calmodulin Binding to Its Targets
Feng Yedan, Wei Qun*
2012, (10): 2028-2039 |
Published: 24 October 2012
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Abstract
Calmodulin (CaM) binds to hundreds of target proteins, and regulates a numerous of Ca2+ signaling involved cellular events. Matched by the extensive and diverse list of targets, CaM varies in the way of interacting with its targets. There were already some reviews published several years ago, but the latest one was published in 2006. Owing to the progress in structure-determining, more and more structures of CaM-target complexes were published, and a lot of new binding modes were discovered during the past 5 to 6 years. One of these newly published complexes was solved by our lab: the complex for CaM binding to the CaM binding domain (CBD) of calcineurin (CN). The crystal structure of CaM-CN-CBD showed an X-shaped dimer, which was not identical with the canonical wrap-around modes. In this article, we discussed more than 30 different CaM-target complexes. These complexes included the complexes reviewed by others several years ago, the CaM-CN-CBD complex solved by our lab, and the other complexes published during the past 5 to 6 years. We divided these complexes into six groups: the canonical wrap-around modes, other wrap-around modes, the extended binding modes, the IQ motif related binding modes, the dimerization binding modes, and the large fragment related binding modes. These diverse binding modes provide a structural basis for the multifunctional feature of CaM, and provide an insight into the binding modes for other CaM-target complexes whose structures are unknown. Contents 1 Introduction
2 General aspects of the modes for calmodulin binding to its targets
3 Canonical wrap-around modes
3.1 Myosin light chain kinases and CaM-dependent protein kinases
3.2 Other complexes for the 1-14 binding modes
4 Other wrap-around modes
4.1 Myristoyl group related binding mode
4.2 Shorter spacing between the two hydrophobic anchors
4.3 Longer spacing between the two hydrophobic anchors
5 Extended binding modes
5.1 Munc13-1 protein
5.2 Sodium/hydrogen exchanger 1
6 IQ motif related binding modes
6.1 Voltage-gated calcium channels
6.2 Myosin Ⅴ and Myosin Ⅵ
6.3 Voltage-gated sodium channels
6.4 Smoothelin-like 1 protein
7 Dimerization binding modes
7.1 Small conductance calcium-activated potassium channel
7.2 Glutamate decarboxylase
7.3 Calcineurin
7.4 Voltage-gated calcium channel 1.2
8 Large fragment related binding modes
8.1 Edema factor
8.2 Death-associated protein kinase
9 Conclusion and outlook
9.1 Mechanisms of the diverse binding modes for CaM-target complexes
9.2 Insights into the binding modes for other CaM-target complexes with unknown structures
Natural Origins, Formation Mechanisms, and Fate of Environmental Perchlorate
Fang Qile, Chen Baoliang*
2012, (10): 2040-2053 |
Published: 24 October 2012
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Abstract
Perchlorate (ClO4-) as an emerging trace pollutant, has caused a great concern about its environmental pollution problems. The natural origin of ClO4- as well as its formation mechanisms is a new research focus. In order to establish new environmental quality standards and safety concentration limits of ClO4-, it is quite important to recognize its natural origins, background concentrations, transport and fate in various environmental media, but few researches were reported in China. In this paper, the background concentration levels of ClO4- in tropospheric and stratospheric aerosol, atmospheric wet deposition (rain and snow), groundwater, seawater, soil and minerals are summarized. The data for ClO4- concentrations in the aerosol were very limited, such as 0.5-5 ppt in the stratospheric aerosol, <1.8 ng/m3 (Japan) and~5.0 ng/m3 (China) in the tropospheric aerosol. The ClO4- concentrations in rain were ND-24 400 ng/L for more than 1 600 samples, and 1-18 ng/L in Arctic snow. The ClO4- concentrations in groundwater were widely investigated in USA, and recently, some data were reported for China, Germany and India, which were mainly pooled in 10-1-102 μg/L for more than 2 100 samples. The reported ClO4- concentrations in sea water were 0.16-6.11 μg/L. As a dominant natural origin, the atmospheric reaction mechanisms (i.e., ozone oxidations, photochemical reactions, and lightning effects) and precursors of ClO4- are highlighted. It is believed that the species of ClO2-/ ClO2 is a critical precursor for the formation of natural ClO4- at the atmosphere. The transport, fate, and biogeochemical cycling of natural ClO4- in the environments are described in details. The isotope tracer approaches for identification of natural source of ClO4- are briefly introduced. The research trends and currently existing problems are prospected. Contents 1 Introduction
2 The natural origins and background concentrations of ClO4-
2.1 Aerosol
2.2 Atmospheric wet deposition
2.3 Groundwater
2.4 Sea water
2.5 Soil (minerals)
3 The precursors and formation mechanisms of natural ClO4-
3.1 Precursors and oxidants
3.2 Reaction mechanisms
4 The transport and fate of natural ClO4-
5 The isotope tracer approaches for identification of natural source of ClO4-
6 Perspectives
Nitrous Oxide Emission and Control in Biological and Chemical Denitrification
Wu Deli*, Fu Minyu, Ma Luming
2012, (10): 2054-2061 |
Published: 24 October 2012
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Abstract
Nitrous oxide (N2O) is considered as a greenhouse gas for a long time, in fact, N2O is also an important propellant in the area of aeronautics and astronautics. More and more attention are attracted to the preparation of N2O in western developed countries. A large amount of N2O could be produced in the process of biological and chemical denitrification, moreover, N2O can be emitted in substantial amounts during nitrogen removal in wastewater treatment. However, limited researches on the collection and utilization of N2O as clean energy are reported in China. In this paper, the pathway of N2O emission in biological nitrogen removal, as well as the mechanisms and influence factors are introduced. In the mean time, the contribution of chemodenitrification in the emission of N2O, especially the role of Fe(Ⅱ), is also discussed. The reutilization of N2O emitted in nitrogen removal process as resources are outlined in the final part of this paper. As the process of chemodenitrification can accumulate a great quantity of N2O more rapidly and more effectively in comparison with biological process, the research in the future should be focused on the mechanisms and influence factors of the production of N2O by chemodenitrificaition. Further research is urgently required in the area of utilization of N2O. Contents 1 Introduction
2 N2O emission in biological nitrogen removal
2.1 N2O emission in denitrification
2.2 N2O emission in nitrification
2.3 Major influence factors on N2O emission in biological nitrogen removal
3 N2O emission in chemodenitrification
3.1 Reduction of nitrate and nitrite by Fe(Ⅱ)
3.2 Decomposition of NH4NO3
3.3 Chemodenitrification of other substances
4 Conclusion and outlook
Technologies of Microalgal Harvesting and Lipid Extraction
Zhang Fang, Cheng Lihua, Xu Xinhua, Zhang Lin, Chen Huanlin
2012, (10): 2062-2072 |
Published: 24 October 2012
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Abstract
Microalgae, with the merits of environmental adaptability, high photosynthetic efficiency and high lipid content, have become one of the most promising raw materials for bio-fuels production, especially for the biodiesel production. In this paper, the advances of technologies in microalgae harvesting and lipid extraction worldwide are reviewed. Firstly, several methods such as flocculation, centrifugation and filtration, as well as their mechanisms and applications for microalgae recovery are introduced. Then, the practical lipid extraction technologies including organic solvents, supercritical and subcritical fluids are evaluated based on their operation conditions and energy consumption. In particular, a novel method of in-situ lipid milking is introduced to allow synchronous culture and lipid extraction of microalgae. Finally, the main problems within the downstream processing of algal oil are summarized and the possible solutions to produce cost-efficient algal biodiesel are proposed. Contents 1 Introduction
2 Algae concentrated and harvesting methods
2.1 Flocculation and sedimentation
2.2 Flocculation and dissolved air flotation
2.3 Centrifugation
2.4 Filtration
3 Algal lipid extraction methods
3.1 Organic solvent extraction
3.2 Supercritical fluid extraction
3.3 Subcritical water extraction
4 In situ lipid milking
4.1 Concept of milking
4.2 Application of milking
4.3 Rules to choose organic solvents for milking establishment
4.4 Mechanism of lipid extraction during milking process
5 Problems and prospects