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Progress in Chemistry 2012, No.08 Previous issue Next issue

In this issue:

Review
Adsorption Mechanism of Macroporous Adsorption Resins
Lou Song, Liu Yongfeng, Bai Qingqing, Di Duolong
2012, 24 (08): 1427-1436 |
Published: 24 August 2012
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Abstract
Macroporous adsorption resins (MARs), which are synthetic porous crosslinked polymer beads, have been developed into a kind of novel functional materials since 1950’. They have widely been used in the fields such as pharmaceutical, chemical, food industries, and wastewater treatment. Besides the traditional research on applications of the commercial MARs in the enrichment process of target compound, some theoretical researches on the adsorption features of MARs are also introduced in this article, including adsorption isotherms, kinetics, driving forces, and interaction models. First, the adsorption isotherm patterns of target compound on MARs are discussed. Second, the diffusion patterns of targets on the surface and internal MARs are illustrated. The relationship between properties of MARs and structures of target compound effects the law of adsorption selection, and the investigation of this relationship is the key problem of theoretical research on separation and adsorption. Moreover, the ultimate purpose of theoretical research on MARs is the establishment and evaluation of adsorption model which could explain the adsorption process objective with a wide range of applications. At last, some suggestions for considering multi-layer adsorption process, adsorption and desorption rates, features of adsorption solution, and physical parameters of MARs into the derivation of model are put forward. Contents 1 Introduction
2 Adsorption isotherms
3 Adsorption kinetcis
4 Interaction forces of adsorption
5 Adsorption model
6 Outlook
Highly Active and Highly Poison Tolerant Anodic Catalysts for Direct Formic Acid Fuel Cells
Lu Xueyi, Liao Shijun, Song Huiyu
2012, 24 (08): 1437-1446 |
Published: 24 August 2012
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Abstract
Formic acid fuel cell is a kind of fuel cell developed in recent years with promising commercial prospects. However, its development and commercialization are restricted by some factors, in which anodic catalyst is recognized as one of the most important factors. In this paper, some significant researches and attempts of promoting catalytic activity and poison tolerance are introduced, including novel preparation approaches, usage of novel supporting materials, as well as the design of multi-component catalyst by doping hetero elements. Concretely, the researches cover synthetic methods such as electrolytic deposition, organic colloid method, impregnation, study of using carbon nanotubes, graphene and complex materials as supports, and relevant work of adding other elements to prepare alloy catalysts and complex catalysts. Furthermore, the future development of formic acid fuel cell is also prospected. Contents 1 Introduction
2 Synthetic technology
2.1 Electrolytic deposition
2.2 Organic colloid method
3 Effect of different supports on catalytic activity
3.1 Carbon nanotube
3.2 Graphene
3.3 Complex materials
4 Addition of other elements
4.1 Pt-based catalysts
4.2 Pd-based catalysts
5 Effect of structures on activity and stability
5.1 Core-shell structure
5.2 Hollow nanosphere structure
5.3 Nanowire stru cture
6 Conclusions and outlook
Nanobubbles on the Immersed Substrates
Li Dayong, Wang Weijie, Zhao Xuezeng
2012, 24 (08): 1447-1455 |
Published: 24 August 2012
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Abstract
Surface nanobubbles is one significant discovery in interfacial physics in recent decade. Scientists have confirmed their existence since the surface nanobubbles were observed by using atomic force microscope (AFM). Studies of nanobubbles' properties and influence factors have been developed deeply because of its potential applications in microelectromechanical system (MEMS), micro biochemical system, hydrodynamics, surface science, etc. The stability (abnormal longevity ) of nanobubbles, however, is still one of open questions. The latest research results of nanobubbles' stability are mainly reviewed in this paper, including line tension theory, dynamic balance theory, impurity theory and Knudsen gas type theory. Additionally, the applications, influences and formation of nanobubbles are sketchily introduced. In the end, we give some suggestions on what still needs to be done to obtain a full understanding of nanobubbles. Contents 1 Introduction
2 Formation and influence factors of nanobubbles
2.1 Formation of nanobubbles
2.2 Influence factors of nanobubbles
3 Stability of nanobubbles
3.1 Line tension theory
3.2 Dynamic balance theory
3.3 Impurity theory
3.4 Knudsen gas type theory
4 Applications of nanobubbles
5 Conclusion and outlook
Polyanion-Type Cathode Materials for Li-Ion Batteries
Wang Fuqing, Chen Jian, Zhang Feng, Yi Baolian
2012, 24 (08): 1456-1465 |
Published: 24 August 2012
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Abstract
Polyanion-type materials are considered as one of the most promising cathode materials for power batteries due to the good safety, low cost and environmental benign of the materials. However, the commercial application of this kind of material is hindered by the poor rate capability and low-temperature performance caused by the low electronic and ionic conductivity of the materials. Recently, the electrochemical performances of the materials have been improved to a certain extend by coating the material particles with carbon or conductive polymer, doping the compounds with foreign metal ions, and preparing the nano-structured materials. And the commercial applications of LiFePO4 in power batteries have been successfully achieved.In this paper, the recent progress on the polyanion-type cathode materials, including silicates and sulfates which have become the research focus again, are reviewed. The crystal structure, synthesis and modification process, electrochemical characteristics, safety of the material, as well as the technical bottlenecks in the actual applications are discussed. The possible approaches to improve the output performance of the materials and the development trends of the polyanion-type cathode materials are also discussed and prospected. Contents 1 Introduction
2 Crystal structure, preparation, and electrochemical characteristic of polyanion-type cathode materials
2.1 Phosphates
2.2 Silicates
2.3 Sulfates
3 Strategies to improve the electrochemical performance of polyanion-type cathode materials
4 Safety of polyanion-type cathode materials
5 Complex/blend cathode materials
6 Conclusion and prospects
Tin-Based Alloy Anode Materials for Lithium Ion Batteries
Chu Daobao, Li Jian, Yuan Ximei, Li Zilong, Wei Xu, Wan Yong
2012, 24 (08): 1466-1476 |
Published: 24 August 2012
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Abstract
Development of high safety, high energy, low cost and long service life Li ion rechargeable batteries is current a tremendous challenge for power battery application. The performance of the battery mainly depends on the nature of anode and cathode materials.Tin-based alloy is an industrially promising anode material for lithium ion batteries due to its high energy capacity and safety characteristics. In this review, the recent progress in Sn-based alloy anode materials for lithium ion batteries are reviewed.The different preparation methods of Sn-based alloy anodes are summarized. This review focuses on the problems in electrochemical properties of the Sn-based alloy anode and their causes, including the effect of loss of active material, SEI film and oxide film formation, aggregation of alloy particles and generation of dead lithium in the process of the intercalation of lithium ions on the charge and discharge performance of the alloy anode. The research trends in improving the electrochemical performance of the Sn-based alloy anode are prospected. Contents 1 Introduction
2 Preparation methods of Sn-based alloy anodes
2.1 Chemical reduction method
2.2 High energy ball milling method
2.3 Electro-deposition method
2.4 Hydrothermal method
2.5 Magnetron sputter plating method
2.6 Plasma reaction method
3 Cause of irreversible capacity and cyclic capacity fade
3.1 Loss of active material in Sn-based alloy anodes
3.2 SEI film and oxide film formation on surface of grain boundary
3.3 Aggregation of alloy particles
3.4 Generation of dead lithium
4 Approaches for improving anode performance
4.1 Multiphase matrix composites
4.2 Porous structure electrodes
4.3 Nano-structure electrodes
4.4 Preparation of thin film
5 Conclusions and outlook
Zinc Oxide for White Light Emitting Diode
Fang Yunxia, Fang Xiaoming, Zhang Zhengguo
2012, 24 (08): 1477-1483 |
Published: 24 August 2012
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Abstract
White light-emitting diodes (WLEDs), a new type of cold solid-state lighting sources, have been considered as “the fourth-generation lighting sources” owing to their advantages of small size, high efficiency, and long lifetime. ZnO is an important semiconductor with excellent optoelectronic and piezoelectric properties, and can be easily prepared into various nanostructures with different morphologies. Besides showing a sharp band-gap emission peak located within the ultra-violet region, ZnO nanostructures exhibit a broad deep band emission that can cover the visible light region between 400 nm and 700 nm, which originates from their intrinsic and/or extrinsic defects, and thus show a potential application in WLEDs. This paper systematically introduces several types of WLEDs configuration composed of ZnO nanostructures, and reviews their performance characteristics and research progress. Since the WLEDs just based on the electroluminescence of ZnO nanostructures need to be applied a high bias, the WLEDs consisting of the heterojunctions prepared by depositing ZnO nanostructures directly on p-type semiconductors (such as GaN) become a hot topics. The preparation methods and the obtained morphologies of ZnO nanostructures have effects on the photoluminescent and electroluminescent spectra of the ZnO nanostructures and thus the performance of the WLEDs. Doping with metal ions or cooperating with other semiconductors can effectively tune the emission spectra of ZnO nanomaterials and thus improve the performance of WLEDs. Moreover, ZnO/polymer heretostructures that combine the excellent properties of ZnO nanostructures with the advantages of polymers show great promise for application in WLEDs. Finally, the problems related to the researches on WLEDs based on ZnO nanostructures and the future developing trends are presented. Contents 1 Introduction
2 WLEDs based on electroluminescence of ZnO nanostructures
3 WLEDs based on electroluminescence of ZnO/polymer heterostructures
4 WLEDs based on photoluminescence of nanosized ZnO
5 Conclusions and outlook
Fabrication of Patterned Inorganic Nanofibers by Electrospinning
Liu Ruilai, Liu Haiqing, Liu Junshao, Jiang Huihua
2012, 24 (08): 1484-1496 |
Published: 24 August 2012
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Abstract
The electrospinning technique has been regarded as the simplest and most effective techniques for massive fabrication of nanomaterials. Various inorganic micro- and nano-fibers have been successfully electrospun in recent years. These fibers can be amorphous, polycrystalline, dense, porous, or hollow. In this review, the fabrication of patterned inorganic nanofibers via electrospinning is presented. After a brief description of the setups for electrospinning, we choose to concentrate on the mechanisms and theoretical models that have been developed for electrospinning. It introduces electrohydrodynamic (EHD) theory that allows the prediction of organic fiber diameter. And the equation was revised in order to be applicable to most inorganic electrospinning systems, as well as have the ability to control the diameter and morphology. It reviews fabrication of aligned nanofibers by using different collectors such as a cylinder collector with high rotating speed, a thin wheel with sharp edge, a pair of split electrodes and the knife-edged counter-electrodes, and fabrication of hollow nanofibers by using sacrificial templates and coaxial electrospinning. At last, it reviews the functional hierarchical structured nanofibers prepared by in situ sol-gel and post-processing methods such as hydrothermal synthesis and chemical vapor deposition. Additionally, the future trends of these interesting patterned inorganic nanofibers, especially the functional hierarchical structured nanofibers are outlooked. Contents 1 Introduction
2 Set-up and principle of electrospinning
3 Preparation of inorganic nanofibers
3.1 Preparation of solution
3.2 Electrospinning of solution
3.3 Calcination of as-spun nanofibers
4 Preparation of patterned inorganic nanofibers
4.1 Aligned nanofibers
4.2 Hollow nanofibers
4.3 Functional hierarchical structured nanofibers
5 Applications of inorganic nanofibers
6 Conclusion and prospects
Recent Progress of Acridine Derivatives with Antitumor Activity
Lang Xuliang, Luan Xudong, Gao Chunmei, Jiang Yuyang
2012, 24 (08): 1497-1505 |
Published: 24 August 2012
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Abstract
Acridines are a series of heterocyclic compounds, which have been received intense interest and used as anti-inflammatory, antibacterial and antitumour agents. This paper reviews some recent progresses in the research of the antitumor activity of acridine derivatives, including as the inhibition of telomerase, topoisomerases Ⅰ and Ⅱ, tubulin, ABCG2/P-gP, protein kinases, etc. The prospects and potential applications of such acridine compounds are outlooked. Contents 1 Introduction
2 Antitumor activity of acridine derivatives
2.1 Telomerase inhibition
2.2 Topoisomerase inhibition
2.3 Tubulin inhibition
2.4 Protein-kinase inhibition
2.5 P-gP and ABCG2 inhibition
3 Conclusion and Prospects
Metal-Organic Framework Materials and Their Applications in Catalysis
Li Qingyuan, Ji Shengfu, Hao Zhimou
2012, 24 (08): 1506-1518 |
Published: 24 August 2012
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Abstract
Metal-organic Framework (MOF) materials, which are synthesized by self-assembling of the metal ions and the organic ligands, are the special crystal materials with porous structure. Because of their diverse structures, tunable cavity and easy functionalization, MOFs have exhibited the attractive prospects in many fields, such as the gas adsorption and separation, the catalysts, the magnetism and the bio-medicine. In order to get comprehensive understanding of the MOFs’ catalytic properties, in this paper, the categories and common synthesis methods of MOF materials are introduced. The catalysis of the MOF materials, especially, the catalysis of the metal active sites and the active organic ligands in the frameworks of the MOF, and the catalytic active components supported in MOFs, are summarized and reviewed. The development trends of MOF materials in the catalytic applications are also prospected. Contents 1 Introduction
2 Categories and syntheses of MOFs materials
2.1 Categories of MOF materials
2.2 Syntheses of MOF materials
3 Applications of MOFs in catalysis
3.1 Catalytic reactions of MOFs with metal active sites
3.2 Catalytic reactions of MOFs with active organic ligands
3.3 Catalytic reactions of MOFs with loading active guests
4 Conclusion and outlook
Ring-Opening Polymerization of ε-Caprolactone Catalyzed by Organocatalyst
Xu Rong, Chen Chunxia
2012, 24 (08): 1519-1525 |
Published: 24 August 2012
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Abstract
Poly(ε-caprolactone) (PCL) is an important class of biocompatible materials, which makes them interesting materials for a range of biomedical and commodity applications, including controlled drug release, tissue engineering, medical implants or environmentally friendly packaging materials. PCL can be prepared through the ring-opening polymerization of ε-caprolactone catalyzed by organic molecules. Compared to traditional metal-catalyzed ROPs, organocatalysis processes can be performed under milder reaction conditions with controlled molar masses and narrow dispersities, furthermore the metal contaminants of the polymer products can be avoided to be removed prior to application as biomedical and pharmaceutical materials. Herein the progress of organocatalysts in the ring-opening polymerization of ε-caprolactone is reviewed according to different means of the activation of the catalysts. The advantages and disadvantages of various catalytic systems are summarized, and development trends and application prospects of organocatalysis for polymerization of ε-caprolactone are also discussed. Contents 1 Introduction
2 Organocatalysts based on electrophilic monomer activation
3 Lewis bases and organocatalysts based on nucleophilic monomer activation
3.1 Organocatalysis by nucleophilic monomer activation
3.2 Organocatalysis by initiator/chain-end activation
4 Synergistic bifunctional organocatalysts and initiator/chain-end activation
5 Conclusion
Application of Frustrated Lewis Pairs in the Activation of Small Molecules
Xu Yingying, Li Zhao, Maxim Borzov, Nie Wanli
2012, 24 (08): 1526-1532 |
Published: 24 August 2012
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Abstract
Recently, frustrated Lewis pairs (FLPs) with unique chemical properties were found to exhibit high activity in catalytic hydrogenation and activation of small molecules. FLPs are now considered as a new prospective type of transition metal free catalysts and this area of chemistry is currently under intense development. This review summarizes the data of the recent achievements in this field. Different aspects concerning the FLPs’ nature, their capability to activate small molecules, possible mechanisms of the dihydrogen activation, along with the known practical applications of FLPs in catalysis are discussed in details. While the driving forces responsible for the reactivity of FLPs in respect to small molecules seem to be rather evident and, actually, present classical electrostatic intermolecular interactions, prior to the first reports on FLPs this brilliantly simple concept has never been utilized in the catalyst design. Since the pioneering work on FLPs in 2006, it is the native elegance of the approach which defines the general productivity of the investigations in this prospective direction. Unfortunately, till now the studies on the FLPs’ chemistry are comparatively few in China. We hope that this contribution could drive more attention of Chinese researchers to this interesting and potent area of modern chemistry. Contents 1 Introduction
2 Structure types of FLPs
3 Researchon activation of small molecules with FLPs
4 Mechanisms of hydrogen activation
5 Application of FLPs as non-metallic catalysts
5.1 Application examples of FLPs in the catalytic hydrogenation
5.2 Application of FLPs in the CO2 transformation
6 Conclusion
Degradation and Conversion of Cellulose in Ionic Liquids
Zhou Lilong, Wu Tinghua, Wu Ying
2012, 24 (08): 1533-1543 |
Published: 24 August 2012
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Abstract
As society’s requirement for resources increasing,biological resources attract widespread attentions. The degradation of cellulose, the most abundant biomass, in the emerging solvents--ionic liquids, becomes a hot topic in chemical research. Dissolving cellulose in ionic liquids is the first step of cellulose’s degradation. So at the beginning of this paper, the current research on dissolution of cellulose in ionic liquids is introduced. As the key step, monosaccharide (glucose and fructose) being converted into 5-HMF (5-hydroxymethyl furfural) in ionic liquids has been researched in recent years. Based on the representative works, it is found that developing an efficient catalyst to convert glucose to 5-HMF still has a long way to go. One-pot conversion of cellulose into 5-HMF in ionic liquids is the most important issue discussed in this article. The review introduces the latest research progress in degradation of cellulose in ionic liquids and the correlative mechanisms. At last, this article points out the shortcoming of the researches and puts forward some possible solutions. Contents 1 Introduction
2 Cellulose dissolves in ionic liquids
2.1 Survey of cellulose’s structure
2.2 Research of cellulose dissolving in ionic liquids
2.3 Mechanism of cellulose dissolving in ionic liquids
2.5 Influence factors of cellulose dissolving in ionic liquids.
3 Research of monosaccharide’s degradation into 5-HMF
3.1 Degradation of fructose to 5-HMF
3.2 Degradation of glucose to 5-HMF
3.3 Mechanism of degradation of glucose to 5-HMF
3.4 Summary
4 Degradation of cellulose in ionic liquids
4.1 Survey of ways to degradation of cellulose
4.2 Metal halides catalysts
4.3 Mineral acids and solid acids catalysts
4.4 Acid-functionalized ionic liquids catalysts
4.5 Summary
5 Conclusions and outlook
Recent Advances in the Determination of Intracellular Contents in Individual Cells Using Microfluidic Devices
Hao Li, Xu Chunxiu, Cheng Heyong, Liu Jinhua, Yin Xuefeng
2012, 24 (08): 1544-1553 |
Published: 24 August 2012
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Abstract
Cells are the fundamental unit of life. Owing to cellular heterogeneity, traditional biochemical assays which analyze cells in bulk often overlook the rich information available when single cells are studied. Accurate and reliable determination of the chemical composition in individual cells would greatly improve the probability of discriminating infected cells from healthy ones and provide a solid foundation on study and development in various fields including biochemistry, medicine, and pathology clinic. Microfluidic chip system for single-cell analysis is now attracting broad interests. The ability of integrating the whole process on one microfluidic chip, including single cell injection, lysis, separation and detection of cellular constituents by chip-based CE, offers a new technical platform for single cell analysis. This article provides a review on recent advances in determining intracellular contents in individual cells using microfluidic devices. Focus areas include on-chip single cell manipulation by means of electroosmotic flow (EOF), pressure-driven flow combined with EOF and optical tweezer (OT) to perform sequentially single cell injection, lysis, separation and detection of cellular constituents by chip-based CE with highly sensitive detection. The approaches on on-chip derivatization are also addressed. Contents 1 Introduction
2 On-chip single cell manipulation by means of electroosmotic flow (EOF)
3 On-chip single cell manipulation by means of pressure-driven flow combined with EOF
4 On-chip single cell manipulation by optical tweezer
5 On-chip cells derivatization
6 Conclusions and outlook
Fluorescent Sensors Based on Graphene Oxide
Zhang Hao, Cui Hua
2012, 24 (08): 1554-1559 |
Published: 24 August 2012
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Abstract
Graphene oxide has great application prospect in many fields due to its unique optical, high surface area, exceptional electronic, thermal and mechanical properties. Taking advantage of the property that graphene oxide can effectively quench the fluorescence of fluorophor including dye, quantum dot and upconversion nanophosphors and various bioanalytical technology, many fluorescent sensors have been developed. In this review, we summarized the principle of fluorescent sensors based on graphene oxide and their application in heavy metallic ion, DNA, protein and small bio-molecule. Moreover, the trends and future perspectives in this research area are also briefly discussed. Contents 1 Introduction
2 Structural characteristic of graphene oxide
3 Application of graphene oxide in fluorescent sensors
3.1 Metal ion fluorescent sensors
3.2 DNA fluorescent sensors
3.3 Protein fluorescent sensors
3.4 Bio-species fluorescent sensors
4 Conclusion and outlook
Improvement of Lower Detection Limit of Ion-Selective Electrodes Based on PVC Membrane
Huang Meirong, Ding Yongbo, Li Xingui
2012, 24 (08): 1560-1571 |
Published: 24 August 2012
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Abstract
Ion-selective electrodes (ISEs) based on polymeric membranes are characterized by small size, portability, low-energy consumption, and low cost, which are attractive features concerning practical applications. However, the lower detection limit is biased by the ion flux through PVC membrane, which limits the further development of ion-selective electrode. Therefore, the principles and attractive strategies to suppress such an ion flux to improve the lower detection limit of PVC membrane-based ion-selective electrodes are elaborated in this article. According to large amounts of data collected, the improvement of the detection limit via optimization of sensing membrane composition, electrode assembly and conditioning, electrode rotation, as well as current-polarized treatment, is quantitatively discussed. Furthermore, the modification regulations for expanding the lower detection limit are systematically summarized. The significant superiority and problems are analyzed. It is pointed out that we have to break the conventional PVC composition formulation via reducing the dosages of plasticizer and ion exchanger in order to largely depress the transmembrane ion flux. External-current application to the electrode is also an effective approach, among which, the best improvement for the lower detection limit can reach up to 5 orders of magnitude. This review reveals the future direction for developing the PVC membrane-based ion-selective electrodes with high performance. Contents 1 Introduction
2 Composition optimization of sensing membrane
2.1 Dosage decrease of plasticizer
2.2 Dosage optimization of ionophore
2.3 Dosage decrease of ion exchanger
2.4 Incorporation of lipophilic silica gel microparticle
3 Thickness increase of sensing membrane
4 Optimization of condition solution
5 Agitating sample solution or rotating electrode
6 Application of external current
7 Conclusion and outlook
Scintillation Proximity Assays in High Throughput Screening
Peng Gang, Liu Bailing, Wang Bin, Li Chenying
2012, 24 (08): 1572-1582 |
Published: 24 August 2012
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Abstract
Originated from a radioimmunoassay method, scintillation proximity assay (SPA) is a homogenous, sensitive, fast and simple scintillant carrier-based platform. This platform can be used to screen lead compounds for drug targets and investigate their biological processes. SPA becomes an important method in high throughput screening (HTS) due to no separation step, easy binding of drug targets and measuring their activities. Because of the diversification and commercialization of radio-labeled molecules and affinity tags, as well as the development of scintillation readers and liquid handling technologies, SPAs have been widely applied in receptor binding, high throughput drug screening, enzyme assay, radioimmunoassay, protein-protein interaction,cell-based assay and so on. This review presents the principle of SPA, discusses the key technologies(includes scintillation carrier, scintillation reader and radiolabel molecule) and analyzes the evaluation system, as well as outlines the assay development and provides some examples in details related to HTS, summarizes the shortcomings and gives some potential outlooks for the future study. Recently, SPA and fluorescence-based screenings have been the hot researches for the high throughput screening drug. The innovations on screening techniques will definitely promote our comprehensive understanding of cellular system biology and dramatically advance the discovery process of leading compounds. Contents 1 Principle of SPA
2 Key elements of SPA
2.1 Choice of scintillation materials
2.2 Choice of scintillation readers
2.3 Choice of radio-label molecules
3 Evaluation factors of SPA
4 Assay developments
5 Applications
5.1 Application of receptor-ligand interactions
5.2 Application of enzyme assays
5.3 Application of HTS drugs
5.4 Application of RIAs
5.5 Application of cell-based assays
6 Shortcomings and outlooks
7 Conclusions
Synchrotron Radiation for the Study of Hydrothermal Formation Mechanisms of Oxide Nanomaterials
Zhou Ying, Lin Yuanhua, Greta R. Patzke
2012, 24 (08): 1583-1591 |
Published: 24 August 2012
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Abstract
Controlled synthesis of oxide nanomaterials is indispensable to enhance their applications. Recently, hydrothermal methods have been widely applied to synthesize oxide nanomaterials. However, hydrothemal reactions are performed in closed reactor systems. Therefore, it is extremely difficult to investigate the dissolution of precursor, the coordination environment of precursor in solution, nucleation and crystallization process, and the involved intermediates. This is the reason that targeted synthesis of oxide nanomaterials has not been achieved. Synchrotron radiation offers notable analytical advantages for structure elucidation, such as high intensity, high brightness, high collimation and wide tunability in energy/wavelength. Based on the design and construction of specialized in situ reactors, synchrotron radiation can be used to investigate the hydrothermal formation process of oxide nanomaterials. In this paper, the design principle of a hydrothermal in situ reactor is introduced. Moreover, the applications of in situ synchrotron X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) and small-angle X-ray scattering (SAXS) to understand the hydrothermal formation mechanisms and reaction kinetics of oxide nanomaterials are critically reviewed. Furthermore, future trends of in situ techniques based on synchrotron radiation are discussed. Contents 1 Introduction
2 Design of in situ cell
3 Applications of synchrotron radiation
3.1 In situ X-ray diffraction
3.2 In situ X-ray absorption spectroscopy
3.3 In situ small angle X-ray scattering
4 Conclusion and outlook
Development of Dummy Template Molecularly Imprinted Techniques in Sample Pretreatment
Xu Zhigang, Liu Zhimin, Yang Baomin, Zi Futing
2012, 24 (08): 1592-1598 |
Published: 24 August 2012
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Abstract
Molecularly imprinted polymers are widely used in complex sample pretreatment. It could eliminate the interference of complicated matrix. It shows high selectivity to its template and good chemical stablity. A dummy template instead of a template molecule to prepare molecularly imprinted polymer could overcome the dissolvability of the template in polymerization solvent. The dummy template molecularly imprinted polymer still shows specific ability to the structure analogous analyte. It could avoid the risk of leakage of template molecule in trace analysis. In this paper, the development of dummy template molecularly imprinted techniques in sample preparation is summarized, including the application of dummy template molecularly imprinted techniques in solid phase extraction, solid phase microextraction, chromatographic solid phase material and matrix solid phase dispersion extraction. The trends of dummy template molecularly imprinted techniques in sample pretreatment are also discussed. Contents 1 Introduction
2 Molecularly imprinted sample pretreatment techniques
3 Dummy template molecularly imprinted sample pretreatment techniques
3.1 Solid phase extraction
3.2 Solid phase microextraction
3.3 Chromatographic solid phase material
3.4 Matrix solid phase dispersion extraction
3.5 Other techniques
4 Conclusions and outlook
Synthesis Gas Production by Chemical-Looping Reforming of Methane Using Lattice Oxygen
Huang Zhen, He Fang, Zhao Kun, Zheng Anqing, Li Haibin, Zhao Zengli
2012, 24 (08): 1599-1609 |
Published: 24 August 2012
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Abstract
Chemical looping reforming (CLR) of methane to obtain synthesis gas using lattice oxygen of oxygen carriers instead of molecular oxygen is a novel technology for producing synthesis gas from methane, which has higher economic benefits and environmental benign. CLR has several advantages, such as, saving oxygen generation equipment, capable of self-heating, suitable hydrogen/carbon ratio, useful by-products and realizing industrialization easily, so, it has been growing interest for researchers at home and aboard. Firstly, the basic concept and characteristics of CLR are introduced, which is partial oxidation of methane through controlling the value of lattice oxygen/fuel, thus, the synthesis gas is produced through the gas-solid reaction between methane and oxygen carriers, and the reduced oxygen carriers are re-oxidized by air or H2O to restore its lattice oxygen. Direct contact between fuel and combustion air is avoided in the CLR. Instead, an oxygen carrier performs the task of bringing O2 from the air to the fuel. In particular, it is summarized for the research progress of monometallic and composite metal oxygen carriers. And the same time, several kinds of typical representative reactor in CLR are discussed, among which interconnected fluidized bed reactor will be most effective for CLR to realize industrialization in the future. Finally, the expand application of CLR and the trends coupled with other technology are prospected. Contents 1 Introduction
2 Concept and characteristic of CLR
3 Oxygen carriers in CLR of methane
3.1 Monometallic oxygen carriers
3.2 Composite metal oxygen carriers
4 Reactor design in CLR of methane
5 Expand application of CLR and the trends coupled with other techniques
6 Conclusion
Preparation and Application of Protein-Functionalized Magnetic Nanoparticles
Huang Tiantian, Fu Yan, Zhang Jinli, Li Wei
2012, 24 (08): 1610-1622 |
Published: 24 August 2012
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Abstract
Protein-functionalized magnetic nanoparticles have received considerable attention in many research areas as new functional composite materials. The stability, loading capacity and the conformation retention of the protein affect the application of the functional particles. The physicochemical properties of the surface not only affect the stability, dispersion and magnetism but also the effective loading of protein. In this paper, the surface modification of magnetic nanoparticles and the protein-functionalized methods are reviewed. Major applications of protein-functionalized magnetic nanoparticles are introduced in the field of enzymatic synthesis, detection analysis of immunoreactions, and biosensors, as well as the future developing prospects. Contents 1 Introduction
2 Preparation of protein-functionalized magnetic nanoparticles
2.1 Adsorption-based immobilization
2.2 Covalent immobilization
3 Application of protein-functionalized magnetic nanoparticles
3.1 Enzymatic synthesis
3.2 Detection analysis
3.3 Biosensors
4 Characterization of proteins immobilized on surfaces
5 Conclusion and outlook