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Krein空间上J-正常算子的可定化性
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作者 陈庆 华梦霞 付本银 《数学年刊(A辑)》 CSCD 北大核心 2013年第5期521-530,共10页
对于Krein空间上J-正常算子的各种可定化性进行了研究.利用可定化J-正常算子的谱函数,给出了临界线的概念,得到了可定化的J-正常算子成为强可定化算子和一致可定化算子的充要条件.
关键词 KREIN空间 J-正常算子 可定化性
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关于Krein空间上J-正常算子可定化性的一个注记
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作者 陈庆 华梦霞 《南阳师范学院学报》 CAS 2011年第6期8-11,共4页
利用可定化J-自伴算子的谱函数,对于Krein空间上J-正常算子N的可定化性与其实部、虚部的可定化性之间的关系做了讨论.指出若N的实部或虚部中有一个为可定化算子(强可定化算子、一致可定化算子),则N是可定化的(强可定化的、一致可定化的)... 利用可定化J-自伴算子的谱函数,对于Krein空间上J-正常算子N的可定化性与其实部、虚部的可定化性之间的关系做了讨论.指出若N的实部或虚部中有一个为可定化算子(强可定化算子、一致可定化算子),则N是可定化的(强可定化的、一致可定化的),且通过例子说明该结论的逆命题并不成立. 展开更多
关键词 KREIN空间 J-正常算子 可定化性
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Effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis 被引量:1
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作者 LEI Si-jia 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2006年第7期580-585,共6页
The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation (6.0% BW/d) were used. Ap... The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation (6.0% BW/d) were used. Apparent digestibility (AD) of dry matter (DMAD), protein (PAD) and protein real digestibility (PRD) were significantly affected by ration level, but not by feeding frequency when the ration level was similar. However, the feeding frequency affected the AD, DMAD, PAD and PRD significantly when the turtles were fed to satiation. The relationship between fecal protein content (Y) and protein intake (At) can be expressed as a quadric equation: Y=-0.1742+0.1476X-0.0003X^2 (r^2=0.876, n=27, F=93.92, P〈0.01). 展开更多
关键词 DIGESTIBILITY Ration level Feeding frequency Juvenile soft-shelled turtle Pelodiscus sinensis
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Consequence Identification for Maloperation in Batch Process 被引量:2
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作者 张玉良 张贝克 +2 位作者 马昕 曹柳林 吴重光 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第12期1347-1359,共13页
Batch processes are important in chemical industry,in which operators usually play a major role and hazards may arise by their inadvertent acts.In this paper,based on hazard and operability study and concept of qualit... Batch processes are important in chemical industry,in which operators usually play a major role and hazards may arise by their inadvertent acts.In this paper,based on hazard and operability study and concept of qualitative simulation,an automatic method for adverse consequence identification for potential maloperation is proposed.The qualitative model for production process is expressed by a novel directed graph.Possible operation deviations from normal operating procedure are identified systematically by using a group of guidewords.The proposed algorithm is used for qualitative simulation of batch processes to identify the effects of maloperations.The method is illustrated with a simple batch process and a batch reaction process.The results show that batch processes can be simulated qualitatively and hazards can be identified for operating procedures including maloperations.After analysis for possible plant maloperations,some measures can be taken to avoid maloperations or reduce losses resulted from maloperations. 展开更多
关键词 maloperation consequence identification batch process hazard and operability study qualitative simulation
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Immobilization of metal-organic molecular cage on g-C3N4 semiconductor for enhancement of photocatalytic H2 generation 被引量:1
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作者 Yuanpu Wang Liang Liu +4 位作者 DongJun Wu Jing Guo Jianying Shi Junmin Liu Chengyong Su 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第8期1198-1204,共7页
A new compound based on immobilizing of Pd6(RuL3)8(BF4)28 (L=2-(pyridin-3-yl)-1H-imidazo [4,5-f][1,10]-phenanthroline) cage (MOC-16) on g-C3N4 was synthesized. Infrared spectrum and powder X-ray diffraction were used ... A new compound based on immobilizing of Pd6(RuL3)8(BF4)28 (L=2-(pyridin-3-yl)-1H-imidazo [4,5-f][1,10]-phenanthroline) cage (MOC-16) on g-C3N4 was synthesized. Infrared spectrum and powder X-ray diffraction were used to characterize structure of hybrid MOC-16/g-C3N4, as well as UV-vis absorption spectrum and X-ray photoelectron spectroscopy were carried out to unveil photocatalytic mechanism. With the introduction of MOC-16, the absorption edge of MOC-16/g-C3N4 in UV-vis spectrum extended apparently to long-wavelength region compared with pristine g-C3N4. H2 evolution yielded with MOC-16/g-C3N4 in aqueous solution containing TEOA was much higher than that with RuL3/g-C3N4, Pd/RuL3/g-C3N4 and mixture of MOC-16 and g-C3N4, showing that the octahedral cage structure with high-efficient electron transfer and the interface interaction between MOC-16 and g-C3N4 were significant for improvement of H2 evolution. 展开更多
关键词 g-C3N4 Metal-organic cage Photocatalytic H2 evolution Visible light Stability
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Effect of Complexation with Hydroxylpropyl-β-Cyclodextrin on Solubility, Dissolution Rate and Chemical Stability of Prostaglandin E1 被引量:2
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作者 GUFu-gen CUIFu-de GAOYong-liang 《Journal of Chinese Pharmaceutical Sciences》 CAS 2004年第3期158-165,共8页
Aim To study the effect of complexation with hydroxylpropyl-β-cyclodextrin(HP-β-CD) on the solubility, dissolution rate and chemical stability of prostaglandin E_1 (PGE_1) ,thereby providing a basis for preparing a ... Aim To study the effect of complexation with hydroxylpropyl-β-cyclodextrin(HP-β-CD) on the solubility, dissolution rate and chemical stability of prostaglandin E_1 (PGE_1) ,thereby providing a basis for preparing a stable solid or aqueous preparation of PGE_1 formulatedwith HP-β-CD. Methods The effect of HP-β-CD on the solubility of PGE_1 was studied by phasesolubility method. The formation of inclusion complexes of PGE_1 with HP-β-CD in the aqueoussolution was confirmed by UV spectra, circular dichroism spectroscopy, and that in the solid stateby IR spectra and X-ray diffractome-try. An solid inclusion complex of PGE_1 with HP-β-CD wasprepared by lyophilization. The dissolution rate and stability of the inclusion complex weredetermined and compared with those of PGE_1 alone. Meanwhile, the stability of PGE_1 aqueoussolutions in the presence of HP-β-CD was studied under different pH conditions. Results Thesolubility of PGE_1 increased linearly with increasing HP-β-CD concentration in various pH bufferedsolutions, showing typical A_L-type phase solubility diagrams. The stability and dissolution rateof the solid inclusion complex of PGE_1 were significantly increased, compared with those of purePGE_1 . The stability of PGE_1 in HP-β-CD solutions was also obviously improved under acidic andbasic conditions, but the stabilizing effect was absent under neutral conditions. Conclusions Thesolubility,dissolution rate and chemical stability of PGE_1 are markedly improved by complexationwith HP-β-CD: It is quite possible to prepare a stable PGE_1 inclusion complex-containing soliddosage forms, but almost impossible to obtain a stable aqueous preparation of PGE_1 formulated withHP-β-CD. 展开更多
关键词 PGE_1 HP-β-CD inclusion complex SOLUBILITY dissolution rate STABILITY
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Correlation of Cooperatively Localized Rearrangement on the "Fluidized Domain" of Polymers to Their Nonexponentially Viscoelastic Behavior and Lifetime at Double Aging Processes II: Estimation of Long-term Mechanical Behavior and Lifetime of Polymeric Materials from Short-time Creep and Stress Relaxation Tests 被引量:1
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作者 金艳 宋名实 +1 位作者 胡桂贤 吴大鸣 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第2期185-194,I0002,共11页
Three kinds of polymeric materials are taken as example for the verification of linear ex-trapolation method from unified master lines with reduced universal equations on creep and stress relaxation tests. The theoret... Three kinds of polymeric materials are taken as example for the verification of linear ex-trapolation method from unified master lines with reduced universal equations on creep and stress relaxation tests. The theoretical values of long-term mechanical behavior and lifetime for a cured epoxide, polypropylene, poly(methyl-methacrylate), and SBR rubber are directly evaluated with the universal equations on reduced creep compliance and reduced stress relax-ation modulus and are compared with their predicted values by the linear extrapolation from the unified master lines of creep and stress relaxation. The results show that the theoretical values of dimensional stability, bearing ability and lifetime are in an excellent agreement with the predicted values, it shows that the linear extrapolation method is more simple and reliable. The dependences of long-term mechanical behaviors and lifetime on the different aging times are discussed. 展开更多
关键词 Physical aging Mechanical aging Dimensional stability Bearing ability Creep and stress relaxation Estimation of aging lifetime
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A Hierarchy of Lax Integrable Lattice Equations, Liouville Integrability and a NewIntegrable Symplectic Map 被引量:6
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作者 XUXi-Xiang ZHANGYu-Feng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第3期321-328,共8页
A discrete matrix spectral problem and the associated hierarchy of Lax integrable lattice equations are presented, and it is shown that the resulting Lax integrable lattice equations are all Liouville integrable discr... A discrete matrix spectral problem and the associated hierarchy of Lax integrable lattice equations are presented, and it is shown that the resulting Lax integrable lattice equations are all Liouville integrable discrete Hamiltonian systems. A new integrable symplectic map is given by binary Bargmann constraint of the resulting hierarchy. Finally, an infinite set of conservation laws is given for the resulting hierarchy. 展开更多
关键词 lattice soliton equation discrete Hamiltonian system Liouville integrability NONLINEARIZATION symplctic map conservation law
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Preparation and properties of pectinase immobilized on chitosan support
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作者 LI Tuo-ping LI Su-hong +3 位作者 WANG Na GUO Mei SUN Jing-yuan LIU Jin-fu 《Journal of Agricultural Science and Technology》 2008年第1期53-57,共5页
Pectinase was immobilized onto chitosan support itsing glutaraldehyde as a coupling agent to obtain high activity and stability of pectinase.x A maximum residual activity of 55% was obtained with 0.4 mg proteirdg chit... Pectinase was immobilized onto chitosan support itsing glutaraldehyde as a coupling agent to obtain high activity and stability of pectinase.x A maximum residual activity of 55% was obtained with 0.4 mg proteirdg chitosan (w/w), 5% (v/v) g/utara/dehyde, and 4℃ for the crosslinking reaction. The optimal pH and temperature for pectinase activity changed from 3.0 and 40℃ to 3.5 and 50℃, respectively, after immobilization The immobilized enzyme exhibited higher stability under varying conditions of pH and temperature and better reusability than the free enzyme. 展开更多
关键词 CHITOSAN GLUTARALDEHYDE IMMOBILIZATION PECTINASE
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Optimization of Routing Considering Uncertainties 被引量:1
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作者 Georgios I. Papatzanakis (1) Apostolos D. Papanikolaou (1) papa@deslab.ntua.gr Shukui Liu (1) 《Journal of Marine Science and Application》 2012年第1期10-17,共8页
A route optimization methodology in the frame of an onboard decision support/guidance system for the ship's master has been developed and is presented in this paper. The method aims at the minimization of the fuel vo... A route optimization methodology in the frame of an onboard decision support/guidance system for the ship's master has been developed and is presented in this paper. The method aims at the minimization of the fuel voyage cost and the risks related to the ship's seakeeping performance expected to be within acceptable limits of voyage duration. Parts of this methodology were implemented by interfacing alternative probability assessment methods, such as Monte Carlo, first order reliability method (FORM) and second order reliability method (SORM), and a 3-D seakeeping code, including a software tool for the calculation of the added resistance in waves of NTUA-SDL. The entire system was integrated within the probabilistic analysis software PROBAN. Two of the main modules for the calculation of added resistance and the probabilistic assessment for the considered seakeeping hazards with respect to exceedance levels of predefined threshold values are herein elaborated and validation studies proved their efficiency in view of their implementation into an on-board optimization system. 展开更多
关键词 AKeywords: routing system operational risk assessment multi-objective optimization epistemic and aleatoryuncertainties
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Identity, Traditions and Lack of Environmental Behaviour
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作者 C. Arcidiacono F. Procentese M.G. Paolillo 《Journal of Environmental Science and Engineering》 2011年第3期365-380,共16页
Place memories (traditions), transmitted through art and the stories of a community, are key elements for the construction of individual and collective identity, connected to specific places. In this regard the auth... Place memories (traditions), transmitted through art and the stories of a community, are key elements for the construction of individual and collective identity, connected to specific places. In this regard the authors examined how the representation of traditions affects place identity and in what ways the cultural heritage of the town might influence environmental forms of behaviour such as plans and projects. To this end the authors investigated the small town of Pagani in southern Italy, which has many ancient cultural traditions linked to specific locations and their rituals such as the festival of Our Lady of the Hens. Our contribution favours a qualitative approach in examining the data gathered and a participative methodology. The statistical analysis of the vocabulary distribution within 83 texts concerning town and its traditions, written by local citizens (52% male and 48% female) of different ages (range: 18-78) revealed a strong place identity. Narrative interviews (14) with key people were then analysed by means of grounded theory. In the perspective of conservation psychology the authors finally focussed on how feelings of impotence and social distrust influence relations between citizens and their local environment. 展开更多
关键词 Traditions place identity place attachment environmental behaviour community trust.
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Traditional Structures Technologies in Tekye-Amir-Chakhmagh
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作者 Hessam Ghamari Mohesn Vafamehr 《Journal of Civil Engineering and Architecture》 2010年第9期47-55,共9页
Iranian traditional architecture can be identified in many of its old famous buildings in the country. The principles and specifications in these buildings show the intelligence of implemented techniques that makes th... Iranian traditional architecture can be identified in many of its old famous buildings in the country. The principles and specifications in these buildings show the intelligence of implemented techniques that makes them to remain stable. Thus, it is important to explore the traditional structures and architectural technologies in order to understand the reasons for this stability toward the new methods in modem architecture. Many of historical buildings in Iran have remained standing after many years and they show the deep wisdom of their architects. The purpose of this article is studying the various aspects of traditional structure and integration between this well-oriented structure and architecture. For reaching this goal, we refer to Tekye-Amir-Chakhmagh in Yazd as our case study, which is one of the most important and noticeable examples of Iranian traditional architecture. By introducing Amir-Chakhmagh Complex, we analyzed the specifications and fundamental elements that played an important role in stability and sustainability of Tekye-Amir-Chakhmagh and thereafter, we assessed the technologies that were used intelligently and intricately in this historical building. In this research, information is collected with field study and library resources. Finally, qualities and characteristics of the structure are studied by drawings and structural analysis and as conclusion, the suggestions and guidelines are presented. 展开更多
关键词 STRUCTURE Iranian architecture LOAD TECHNOLOGY Tekye-Amir-Chakhmagh.
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Large eddy simulation of a 3-D spatially developing turbulent round jet 被引量:2
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作者 ZHANG HuiQiang RONG Yi +1 位作者 WANG Bing WANG XiLin 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第11期2916-2923,共8页
A three-dimensional large eddy simulation (LES) of a spatially developing round jet is carried out in cylindrical coordinates using a dynamic subgrid model with strong inflow instability. Evolutions of large-scale v... A three-dimensional large eddy simulation (LES) of a spatially developing round jet is carried out in cylindrical coordinates using a dynamic subgrid model with strong inflow instability. Evolutions of large-scale vortex structures represented by tangential vortices are obtained and compared with flow visualization. Also presented are three-dimensional spatial evolutions of coherent structure, which are of quasi two-dimensional Kelvin-Helmholtz instability and vortex rings as well as breaking up of the vortex rings with fully three-dimensional characteristics. Predicted results of mean velocity and turbulent intensity agree well with experiments. They are also compared with the results predicted by LES using standard Smagorinsky model and show good self-similarity. Turbulence spectrum of the predicted velocity shows the -5/3 decay for higher wave number, as expected for turbulent round jet flows. In addition, fl-test and y-test are carded out for the instantaneous velocity, showing that the present LES method can successfully predict the hierarchical structure of round jet. 展开更多
关键词 large eddy simulation round jet spatially developing flow large-scale structure hierarchical structure
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Magnetically responsive photonic films with high tunability and stability 被引量:4
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作者 Yongxing Hu Le He Xiaogang Han Mingsheng Wang Yadong Yin 《Nano Research》 SCIE EI CAS CSCD 2015年第2期611-620,共10页
We demonstrate the fabrication of magnetically assembled one-dimensional chain-like photonic nanostructures with significantly high photonic stability. The key lies in the use of agarose hydrogel to prevent coagulatio... We demonstrate the fabrication of magnetically assembled one-dimensional chain-like photonic nanostructures with significantly high photonic stability. The key lies in the use of agarose hydrogel to prevent coagulation of the magnetic assemblies. When exposed to an external magnetic field, negatively charged Fe3O4@SiO2 particles can effectively assemble in the hydrogel matrix into one- dimensional chains with internal periodicity and display a fast, fully reversible, and tunable photonic response to the changes in the external field. The steric hindrance and the hydrogen bonding from the agarose network effectively limit the migration of the Fe304@SiO2 particles and their chain-like assemblies. As a result, the system shows remarkable stability in photonic response under external magnetic fields of large gradients, something which has previously been a challenge. The ability to stabilize the magnetic particle assemblies over a long period represents a major stride toward practical applications of such field- responsive photonic materials. 展开更多
关键词 magnetic field hydrogel REVERSIBLE assembly photonic nanostructures COAGULATION
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Highly active CeO_2 hollow-shell spheres with Al doping 被引量:4
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作者 Zumin Wang Shuaiyu Jiang +5 位作者 Yanhui Li Pengfei Xu Kun Zhao Lingbo Zong Hao Wang Ranbo Yu 《Science China Materials》 SCIE EI CSCD 2017年第7期646-653,共8页
Metal oxide hollow structures are of great inter- est in many current and emerging areas of technology. This paper presents a facile and controlled protocol for the syn- thesis of Al-doped CeO2 hollow-shell spheres (... Metal oxide hollow structures are of great inter- est in many current and emerging areas of technology. This paper presents a facile and controlled protocol for the syn- thesis of Al-doped CeO2 hollow-shell spheres (CHS), where the dopant confers enhanced stability and activity to the ma- terial. These Al-doped CeO2 hollow-shell spheres (ACHS) possess a controllable shell number of up to three, where the sizes of the exterior, middle, and interior spheres were about 250-100 nm,150-50 nm, and 40-10 nm, respectively, and the average shell thickness was -15 nm. The thermal stability of the ACHS structure was enhanced by the homogeneous in- corporation of AI atoms, and more active oxygen species were present compared with those in the non-doped congener. Au NPs supported on ACHS (Au/ACHS) showed superior cat- alytic performance for the reduction of p-nitrophenol. For the same Au NP content, the reaction rate constant (k) of the Au/ACHS was nearly twice that of the non-doped Au/CHS, indicating that AI doping is promising for improving the per- formance of inert or unstable oxides as catalyst supports. 展开更多
关键词 CEO2 hollow structure DOPING CATALYST
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Exponential Stability Analysis of a Markovian Deteriorating System 被引量:1
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作者 Yinghua Shen Yufeng Zhang Aidong Jin 《Journal of Systems Science and Information》 2009年第2期129-140,共12页
The reliability of a complex system passes through a gradual deterioration until at some critical level, the system fails completely. The study of the exponential stability of such a system requires the application of... The reliability of a complex system passes through a gradual deterioration until at some critical level, the system fails completely. The study of the exponential stability of such a system requires the application of functional analysis and, particularly, the theory of linear operators in Banach space to demonstrate the existence of strictly dominant eigenvalue. Through analyzing the variation of the essential spectral radius of semigroups before and after perturbation, it is shown that the dynamic solution of the system converges to the steady-state solution of the system exponentially under certain condition. 展开更多
关键词 strictly dominant eigenvalue CO-SEMIGROUP the essential spectral radius PERTURBATION exponential stability
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Self-assembled multifunctional Fe_(3)O_(4) hierarchical microspheres: high-efficiency lithium-ion battery materials and hydrogenation catalysts 被引量:2
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作者 Konglin Wu Min Ling +7 位作者 Peiyuan Zeng Liang Zhang Tao Wu Pingli Guan Weng-Chon Cheong Zheng Chen Zhen Fang Xianwen Wei 《Science China Materials》 SCIE EI CAS CSCD 2021年第5期1058-1070,共13页
Self-assembled Fe_(3)O_(4)hierarchical microspheres(HMSs) were prepared by a one-pot synchronous reduction–self-assembling (SRSA) hydrothermal method.In this simple and inexpensive synthetic process,only glycerol,wat... Self-assembled Fe_(3)O_(4)hierarchical microspheres(HMSs) were prepared by a one-pot synchronous reduction–self-assembling (SRSA) hydrothermal method.In this simple and inexpensive synthetic process,only glycerol,water,and a single iron source (potassium ferricyanide (K3[Fe(CN)6]))were employed as reactants without additional reductants,surfactants,or additives.The iron source,K3[Fe(CN)6],and glycerol significantly affected the synthesis of Fe_(3)O_(4)HMSs.Fe_(3)O_(4)HMSs with a self-assembled spherical shape readily functioned as high-performance anode materials for lithiumion batteries with a specific capacity of>1000 mA h g^(-1)at0.5 A g^(-1)after 270 cycles.Further charging and discharging results revealed that Fe_(3)O_(4)HMSs displayed good reversible performance (>1000 mA h g^(-1)) and cycling stability (700 cycles) at 0.5 A g^(-1).Furthermore,as multifunctional materials,the as-obtained Fe_(3)O_(4)HMSs also exhibited high saturation magnetization (99.5 emu g^(-1)) at room temperature (25°C) and could be further employed as efficient and magnetically recyclable catalysts for the hydrogenation of nitro compounds. 展开更多
关键词 iron oxide hierarchical structure energy storage material lithium-ion battery hydrogenation catalyst
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PbCrO_4 yellow-pigment nanorods: An efficient and stable visible-light-active photocatalyst for O_2 evolution and photodegradation
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作者 Guo-Qiang Zhang Guoshuai Liu +5 位作者 Yangsen Xu Jianhua Yang Ying Li Xiaojuan Sun Wei Chen Chen-Liang Su 《Science China Materials》 SCIE EI CSCD 2018年第8期1033-1039,共7页
Here, PbCrO4 nanorods, a commonly used and low-cost yellow pigment, was synthesized via a simple pre-cipitation reaction and can serve as a highly efficient oxygen production and photodegradation photocatalyst. The ob... Here, PbCrO4 nanorods, a commonly used and low-cost yellow pigment, was synthesized via a simple pre-cipitation reaction and can serve as a highly efficient oxygen production and photodegradation photocatalyst. The obtained PbCrO4 nanorods exhibit excellent stability and pho-tocatalytic performance for O2 evolution from water. The production rate is approximately 314.0μmol h^-1 g^-1 under visible light, and the quantum efficiency is approximately 2.16% at 420±10 nm and 0.05% at 600±10 nm. In addition, the PhCrO4 shows good degradation performance for methylene blue, methyl blue, methyl orange and phenol under visible-light irradiation. These results indicate that it is potential to fabricate an effective, robust PbCrO4 photocatalyst by trans-forming heavy-metal pollutants Pb(II) and Cr(VI) into a highly efficient O2 evolution and photodegradation material. This strategy which uses pollutant to produce clean energy and degrade contaminants is completely green and environmentally benign, and thus could be a promising way for practical environmental applications. Keywords: 02 evolution, pollutant, PbCrO4 nanorods, visible-light-active, photocatalyst 展开更多
关键词 O2 evolution pollutant PbCrO4 nanorods visible-light-active photocatalyst
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Spectroscopic and electrochemical properties of Cu-dicyandiamide complex
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作者 Kai-Xuan Xu Mei-Hong Guo +2 位作者 Ling-Qing Ren Wei Huang Jian-Jun Sun 《Science China Chemistry》 SCIE EI CAS CSCD 2018年第3期360-367,共8页
Dicyandiamide(DICY) is a common ligand that exhibits low toxicity but can irritate the skin and eyes and cause methemoglobinemia on long-term exposure. Crystalline Cu-dicyandiamide(Cu-DICY) was obtained via facile syn... Dicyandiamide(DICY) is a common ligand that exhibits low toxicity but can irritate the skin and eyes and cause methemoglobinemia on long-term exposure. Crystalline Cu-dicyandiamide(Cu-DICY) was obtained via facile synthesis and its molecular structure and theoretical Raman spectra were simulated by using density functional theory(DFT). The results suggested that the Cu^(2+) coordinates with two H_2 O molecules and two different DICY molecules(an imino DICY and an amino DICY). The stability constants of Cu-DICY were calculated, and the electrochemical properties were studied. Two electrochemical redox processes occur in Cu-DICY in an aqueous solution: a reversible reaction with a formal potential of 0.2 V vs.MSE and an irreversible reaction between –0.4 and –1.2 V vs. MSE. The standard rate constant k0 for the reversible reaction was estimated to be 7.6×10^(-3) cm/s. In addition, based on the reversible reaction of Cu-DICY, square wave voltammetry was used to rapidly determine the concentration of Cu(II) and the detection limit was 66.7 μg/L, which satisfies the detection limit requirements for copper in tap water(2 mg/L) as provided by the World Health Organization. 展开更多
关键词 Cu-dicyandiamide density functional theory Raman spectra square wave voltammetry
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