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Microwave-hydrothermal preparation of a graphene/hierarchy structure MnO_2 composite for a supercapacitor

Particuology 2014年第4期12卷 27-33页

作者： Zhong Chen Jianling Li Yu Chen Yakun Zhang Guofeng Xu Jun Yang Ye Feng State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing30 College Road State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences

Graphene/hierarchy structure manganese dioxide （GN/MnO2） composites were synthesized using a simple microwave-hydrothermal method. The properties of the prepared composites were analyzed using field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and X-ray photoelectron spectroscopy （XPS） measurements. The electrochemical performances of the composites were analyzed using cyclic voltammetry, electrochemical impedance spectrometry （EIS）, and chronopotentiometry. The results showed that GN/MnO2 （10 wt% graphene） displayed a specific capacitance of 244 F/g at a current density of 100 mA/g. An excellent cyclic stability was obtained with a capacity retention of approximately 94.3% after 500 cycles in a 1 mol/L Li2SO4 solution. The improved electrochemical performance is attributed to the hierarchy structure of the manganese dioxide, which can enlarge the interface between the active materials and the electrolyte. The prepa- ration route provides a new approach for hierarchy structure graphene composites; this work could be readily extended to the preparation of other graphene-based composites with different structures for use in energy storage devices.

关键词： Graphene MnO2 Hierarchy structure Supercapacitor

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A multi-scale architecture for multi-scale simulation and its application to gas-solid flows

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Particuology 2014年第4期12卷 160-169页

作者： Bo Li Guofeng Zhou Wei Ge Limin Wang Xiaowei Wang Li Guo Jinghai Li State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences

A multi-scale hardware and software architecture implementing the EMMS （energy-minimization multi-scale） paradigm is proven to be effective in the simulation of a two-dimensional gas-solid suspension. General purpose CPUs are employed for macro-scale control and optimization, and many integrated cores （MlCs） operating in multiple-instruction multiple-data mode are used for a molecular dynamics simulation of the solid particles at the meso-scale. Many cores operating in single-instruction multiple- data mode, such as general purpose graphics processing units （GPGPUs）, are employed for direct numerical simulation of the fluid flow at the micro-scale using the lattice Boltzmann method. This architecture is also expected to be efficient for the multi-scale simulation of other comolex systems.

关键词： General purpose graphics processing unit（GPGPU）Many integrated core （MIC）Meso-science Multiple-instruction multiple-dataSingle-instruction multiple-dataVirtual process engineering

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Visualization investigation of secondary flow on heat transfer deterioration in horizontal heat tube 22

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2014 22nd International Conference on Nuclear engineering, ICONE 2014

作者： Wu, Chao Li, Hui-Xiong Qian, Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

ISBN: (纸本)9780791845905

Mixed convection heat transfer in heated tubes has been studied extensively in the past decades, which is widely used in various industrial fields such as cooling of a nuclear reactor core. The secondary flow, which is induced by buoyancy force, has been found in previous research to have profound influence on the heat transfer difference on circumferential position and occurrence of heat transfer deterioration in horizontal heated channel. Therefore, understanding the secondary flow velocity field has important implications to prevent heat transfer deterioration and ensure the safe operation of nuclear power plants. Numerical methods have been adopted in literature to analyze the complex interaction between secondary flow and heat transfer deterioration. However, to the knowledge of the author, experimental measurement of secondary flow in the radial cross-section of a horizontal tube does not exist.. Copyright © 2014 by ASME.

关键词： Numerical methods

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Flame-front instabilities of outwardly expanding isooctane/ n -butanol blend-air flames at elevated pressures

Flame-front instabilities of outwardly expanding isooctane/ ...

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作者： Zhang, Xinyi Tang, Chenglong Yu, Huibin Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China

Experiments were conducted in a constant volume bomb filled with isooctane/n-butanol blend-air mixtures over a wide range of n-butanol blending ratios, equivalence ratios, and initial pressures. High-speed schlieren photography was used to measure the critical radius for the onset of flame-front instability. Results show that, for a given n-butanol blending ratio, cellular instabilities appear earlier and the critical Peclet number, which represents the onset of instability, is decreased with the increase of the initial pressure and equivalence ratio. Under fuel-rich conditions, the critical Peclet number increases with the increase of the n-butanol blending ratio. Theoretical calculation of the critical Peclet number was also conducted to interpret the effects of n-butanol on the flame-front instabilities of the blends. Results show that, for rich mixture conditions, with the increase of the n-butanol blending ratio, the overall activation energy of the mixtures is decreased and, thus, the thermal-diffusional instabilities are suppressed. While under fuel-lean conditions, the thermal-diffusional instabilities are favored. As a consequence, with an increasing n-butanol blending ratio, the critical Peclet number is expected to be decreased under fuel-lean conditions and increased under fuel-rich conditions. © 2014 American Chemical Society.

关键词： Mixtures

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Influence of phase and microstructure on the rate of hydrochloric acid leaching in pretreated Panzhihua ilmenite

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Particuology 2014年第3期12卷 83-90页

作者： Qingshan Zhu Jianbo Zhang Hongzhong Li State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences

The present study investigated the influence of high temperature oxidation and reduction pretreatments on the leaching rate ofPanzhihua ilmenite. The as-pretreated ilmenite was leached with 20% HCI at 105 ℃, The leaching process was controlled by the phases and microstructures that evolved during the pretreatment processes. The leaching kinetics of pure hematite, ilmenite and pseudobrookite were characterized to clarify the phase effect on the iron-leaching rate; the rate of iron leaching occurs in the following order in the HCI solution： hematite （ferric iron）〉 ilmenite （ferrous iron）〉〉 pseudobrookite （ferric iron）. Therefore, the often-cited notion that ferrous iron dissolves faster in HCl solutions than ferric iron when explaining the pretreatment effects is inaccurate. Moreover, the oxidation pretreatment （at 600-1000 ℃ for 4 h） cannot destroy the dense structure of the Panzhihua ilmenite. Therefore, the influence exerted by the oxidation on the leaching process is primarily determined by the phase change; oxidation at 600 and 700℃ slightly increased the rate of iron leaching because the ilmenite was transformed into hematite, while the oxidation at 900-1000℃ significantly reduced the rate of iron leaching because a pseudobrookite phase formed. The reduction effect was subsequently investigated; the as-oxidized ilmenite was reduced under H2 at 750 ℃ for 30 min. The reduction significantly accelerated the rate of subsequent iron leaching such that nearly all of the iron had dissolved after leaching for 2 h in 20% HCl at 105 ℃. This enhanced iron-leaching rate is mainly attributed to the cracks and holes that formed during the reduction process.

关键词： llmenite Oxidation Reduction Hydrochloric acid leaching

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Erratum to: “engineering molecular dynamics simulation in chemical engineering” [Chem. Eng. Sci. 121 (2015) 200–216]

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Chemical engineering Science 2015年 123卷 674-675页

作者： Ji Xu Xiaoxia Li Chaofeng Hou Limin Wang Guangzheng Zhou Wei Ge Jinghai Li The EMMS Group State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 People׳s Republic of China

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Pool boiling heat transfer enhancement by γ-Al2O3 /FC-72 nanofluids on a smooth surface 15

Pool boiling heat transfer enhancement by γ-Al2O3 /FC-72 na...

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15th International Heat Transfer Conference, IHTC 2014

作者： Kong, Xin Wei, Jinjia Ding, Jie Zhang, Yonghai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong Uniersity Xi'an Shaanxi710049 China

The influence of γ-Al2O3/FC-72 nanofluids on pooling boiling heat transfer with a smooth surface was experimentally investigated. The fluorocarbon surfactant FSO-100 was also used in the experiment. In order to distinguish the effects of surfactant, four groups of contrast tests were designed as follows: base fluids (FC-72), base fluids with nanoparticles (γ-Al2O3+FC-72), base fluids with surfactant (FC-72+FSO-100) and nanofluids with surfactant (γ-Al2O3/FC-72+FSO-100). The results of nanofluids with surfactant showed that the heat transfer performance is enhanced compared with base fluid, but will weaken with the increase of particle concentration. In general, nanofluids can enhance the boiling heat transfer to some extent, and the enhancement is affected by the adjunction of surfactant and the sedimentation of nano-particules. Nanofluids prepared with only nanoparticles were not stable due to nonuniform distribution of the particles. The adjunction of surfactant (without nanoparticules) will lead to a significant deterioration in both heat transfer coefficient and CHF (Critical Heat Flux), but it can keep nanofluids stable and homogeneous to some degree for heat transfer enhancement.

关键词： Nanoparticles

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Isolation and characterization of a crude oil degrading bacteria from formation water:comparative genomic analysis of environmental Ochrobactrum intermedium isolate versus clinical strains

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2015年第10期16卷 865-874页

作者： Lu-jun CHAI Xia-wei JIANG Fan ZHANG Bei-wen ZHENG Fu-chang SHU Zheng-liang WANG Qing-feng CUI Han-ping DONG Zhong-zhi ZHANG Du-jie HOU Yue-hui SHE Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Accumulation Mechanism School of Energy Resources China University of Geosciences State Key Laboratory for Diagnosis and Treatment of Infectious Diseases the First Affiliated HospitalSchool of Medicine Zhejiang University College of Chemistry and Environmental Engineering Yangtze University Institute of Porous Flow & Fluid Mechanics Chinese Academy of Sciences State Key Laboratory of Heavy Oil Processing China University of Petroleum

In this study, we isolated an environmental clone of Ochrobactrum intermedium, strain 2745-2, from the formation water of Changqing oilfield in Shanxi, China, which can degrade crude oil. Strain 2745-2 is aerobic and rod-shaped with optimum growth at 42 ℃ and pH 5.5. We sequenced the genome and found a single chromosome of 4800175 bp, with a G＋C content of 57.63%. Sixty RNAs and 4737 protein-coding genes were identified： many of the genes are responsible for the degradation, emulsification, and metabolizing of crude oil. A comparative genomic analysis with related clinical strains （M86, 229E, and LMG3301T） showed that genes involved in virulence, disease, defense, phages, prophages, transposable elements, plasmids, and antibiotic resistance are also present in strain 2745-2.

关键词： Comparative genome Ochrobactrum intermedium Oil degradation Pathogen

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Preparation and Li^+ storage properties of hierarchical hollow porous carbon spheres

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Particuology 2014年第3期12卷 44-50页

作者： Xiaofeng Wu Wenxiang Tang Kejia Jiao Yunfa Chen State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

Hollow ordered porous carbon spheres （HOPCS） with a hierarchical structure were prepared by templating with hollow ordered mesoporous silica spheres （HOMSS）. Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） showed that HOPCS exhibited a spherical hollow morphology. High-resolution TEM, small angle X-ray diffraction （SAXRD） and N2 sorption measurements confirmed that HOPCS inversely replicated the unconnected hexagonal-stacked pore structure of HOMSS, and possessed ordered porosity. HOPCS exhibited a higher storage capacity for Li^＋ ion battery （LIB） of 527.6 mA h/g, and good cycling performance. A large capacity loss during the first discharge-charge cycle was found attributed to the high content of micropores. The cycling performance was derived from the hierarchical structure.

关键词： Hierarchical structure MCM-41 silica Nanostructured carbon Lithium storage

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Manipulating Dendritic Structures via Diffusion and Reaction

Manipulating Dendritic Structures via Diffusion and Reaction

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The 6th International Conference on Nanoscience and Technology, China 2015 (第六届中国国际纳米科学技术会议)

作者： Tao Yang Yongsheng Han Jinghai Li Center of Mesoscience State Key Laboratory of Multiphase Complex System Institute of Process Engineering Chinese Academy of Science Beijing 100190 China

A dendrite is one of the most aesthetically pleasing structures, with the best-known example being snowflakes. Dendritic structures also include dendrites in alloys, neural systems and structures in nanomaterials. Although the formation of dendrites has been studied for centuries, the practical technique to control their growth is limited. Here we report an attempt to manipulate the growth of dendritic structures via controlling chemical diffusion and reaction.

关键词： Shape control Dendritic structure Silver Diffusion Reaction

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