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Electrochemical performance of cotton stalk based activated carbon electrodes modified by MnO₂ for supercapacitor

MATERIALS technology 2015年第A1期30卷 A2-A7页

作者： Chen, M. D. Wumaie, T. Li, W. L. Song, H. H. Song, R. R. Chinese Acad Sci Xian Inst Opt & Precis Mech State Key Lab Transient Opt & Photon Xian 710119 Peoples R China Xinjiang Inst Engn Urumqi 830023 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Beijing Univ Chem Technol Coll Mat Sci & Engn Adv Carbon Mat Res Lab Beijing 100029 Peoples R China

Cotton stalk based activated carbon (AC) was prepared from Xinjiang, China by H3PO4 as activating reagent. In order to improve electrochemical properties of AC, a series of AC/MnO2 (electrolytic manganese dioxide)/AC composites with different MnO2 contents were prepared. The samples specific surface area and pore distribution were characterised by Brunauer, Emmett and Teller (BET);the structure and morphology were characterised by X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Moreover, the improvements of activated carbon modified by MnO2 were confirmed by the experiment of galvanostatic current charge/discharge, cyclic voltammograms and alternating current impedance tests respectively. The results show that the specific capacitance (169 F g(-1)) of the composite material electrode (the contents of MnO2 is 5%) would be higher in 1.0 mol L-1 Et4NBF4/AN electrolyte at 2.0 A g(-1) than other composite materials, which is 39% higher than the present study. The capacitance was kept more than 99.2% after 500 cycles and still higher than that of activated carbon materials.

关键词： Cotton stalk Activated carbon Electrolytic manganese dioxide Modification Specific capacitance

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Novel silicon allotropes: Stability, mechanical, and electronic properties

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JOURNAL OF APPLIED PHYSICS 2015年第18期118卷

作者： Fan, Qingyang Chai, Changchun Wei, Qun Yan, Haiyan Zhao, Yingbo Yang, Yintang Yu, Xinhai Liu, Yang Xing, Mengjiang Zhang, Junqin Yao, Ronghui Xidian Univ Sch Microelect Key Lab Minist Educ Wide Band Gap Semicond Mat & Devices Xian 710071 Peoples R China Xidian Univ Sch Phys & Optoelect Engn Xian 710071 Peoples R China Baoji Univ Arts & Sci Coll Chem & Chem Engn Baoji 721013 Peoples R China Kunming Univ Sci & Technol Fac Informat Engn & Automat Kunming 650051 Peoples R China

One quasi-direct gap phase (Amm2) and three indirect gap phases (C2/m-16, C2/m-20, and I-4) of silicon allotropes are proposed. The detailed theoretical study on the structure, density of states, elastic properties, sound velocities, and Debye temperature of these four phases is carried out by using first principles calculations. The elastic constants of these four phases are calculated by strain-stress method. The elastic constants and the phonon calculations manifest all novel silicon allotropes in this paper are mechanically and dynamically stable at ambient condition. The B/G values indicate that these four phases of silicon are brittle materials at ambient pressure. The anisotropy properties show that C2/m-20 phase exhibits a larger anisotropy in its elastic modulus, shear elastic anisotropic factors, and several anisotropic indices than others. We have found that the Debye temperature of the four novel silicon allotropes gradually reduces in the order of C2/m-20 > Amm2> C2/m-16> I-4 at ambient pressure. (C) 2015 AIP Publishing LLC.

关键词： Silicon

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Accessory enzymes influence cellulase hydrolysis of the model substrate and the realistic lignocellulosic biomass

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ENZYME AND MICROBIAL technology 2015年 79-80卷 42-48页

作者： Sun, Fubao Fuebiol Hong, Jiapeng Hu, Jinguang Saddler, Jack N. Fang, Xu Zhang, Zhenyu Shen, Song Jiangnan Univ Sch Biotechnol Minist Educ Key Lab Carbohydrate Chem & Biotechnol Wuxi 214122 Peoples R China Jiangnan Univ Sch Biotechnol Minist Educ Key Lab Ind Biotechnol Wuxi 214122 Peoples R China Univ British Columbia Wood Sci Dept Forestry Prod Biotechnol Bioenergy Grp Vancouver BC V6T 1Z4 Canada Shandong Univ State Key Lab Microbial Technol Jinan 250100 Peoples R China

The potential of cellulase enzymes in the developing and ongoing "biorefinery" industry has provided a great motivation to develop an efficient cellulase mixture. Recent work has shown how important the role that the so-called accessory enzymes can play in an effective enzymatic hydrolysis. In this study, three newest Novozymes Cellic CTec cellulase preparations (CTec 1/2/3) were compared to hydrolyze steam pretreated lignocellulosic substrates and model substances at an identical FPA loading. These cellulase preparations were found to display significantly different hydrolytic performances irrelevant with the FPA. And this difference was even observed on the filter paper itself when the FPA based assay was revisited. The analysis of specific enzyme activity in cellulase preparations demonstrated that different accessory enzymes were mainly responsible for the discrepancy of enzymatic hydrolysis between diversified substrates and various cellulases. Such the active role of accessory enzymes present in cellulase preparations was finally verified by supplementation with beta-glucosidase, xylanase and lytic polysaccharide monooxygenases AA9. This paper provides new insights into the role of accessory enzymes, which can further provide a useful reference for the rational customization of cellulase cocktails in order to realize an efficient conversion of natural lignocellulosic substrates. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Accessory enzyme (xylanase and AA9) Cellulase preparations (Cellic (R) CTec1/2/3) Filter paper activity (FPA) Enzymatic hydrolysis Cellulase mixtures/cocktails

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A New Remote Control Microwave Plasma Jet Excited by Surface Waves

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IEEE TRANSACTIONS ON PLASMA SCIENCE 2014年第12期42卷 3942-3948页

作者： Liu, Pei Chen, Ming Chen, Junfeng Guo, Fu Wang, Shengming Chen, Zhaoquan Liu, Minghai Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Engn & Technol Wuhan 430074 Peoples R China Anhui Univ Sci & Technol Coll Elect & Informat Engn Huainan 232001 Peoples R China Univ Informat Technol Mech & Opt St Petersburg 197101 Russia

A 2.45-GHz microwave plasma jet (MPJ) is designed based on the excitation of surface plasmon polaritons located in the discharge tube. The unique structure of internal metal antenna with an adjusting screw-pitch gauge is convenient to control plasma discharge at different locations for various gases (Ar, N-2, O-2, and so on) MPJ can be operated at wide pressure range with low incident power. Regulating the position of the metal antenna and the flow rate, the longest plasma jet of 23 cm is produced at 100 Pa with the operating power of 30 W. As for high pressure, a plasma jet with a length of 7.5 cm is generated 50-cm away from the hole of the waveguide when incident power reaches 50 W. Field analysis is performed using the traditional software, plasma density, electron temperature, and the discharge components are diagnosed analyzed by the Langmuir double probe and spectrograph, respectively. This kind of plasma jet can be achieved for discharge at the desired positions, so it is suitable for the special industrial applications, such as ignition and recombustion for a certain distance.

关键词： Controllable discharge Langmuir double probe microwave plasma jet (MPJ) numerical simulation spectral analysis surface plasmon polaritons (SPPs)

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Hierarchical NiCo₂O₄@NiMoO₄ core-shell hybrid nanowire/nanosheet arrays for high-performance pseudocapacitors

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JOURNAL OF MATERIALS CHEMISTRY A 2015年第27期3卷 14348-14357页

作者： Cheng, Ding Yang, Yefeng Xie, Jinlei Fang, Changjiang Zhang, Guoqing Xiong, Jie Zhejiang Sci Tech Univ Coll Mat & Text Dept Mat Engn Hangzhou 310018 Zhejiang Peoples R China Zhejiang Sci Tech Univ MOE Key Lab Adv Text Mat & Mfg Technol Hangzhou 310018 Zhejiang Peoples R China Zhejiang Sci Tech Univ Qixin Honors Coll Hangzhou 310018 Zhejiang Peoples R China Zhejiang Univ State Key Lab Silicon Mat Hangzhou 310027 Zhejiang Peoples R China

Three-dimensional (3D) hierarchical NiCo2O4@NiMoO4 core-shell nanowire/nanosheet arrays (NWSAs) for high-performance pseudocapacitors are fabricated directly on Ni foam via a two-step approach which involves hydrothermal and calcination processes. The formation of 3D interconnected networks is greatly beneficial for the facile electrolyte penetration and fast electron transport in the hybrid system. The optimized NiCo2O4@NiMoO4 hybrid electrode delivers a much enhanced areal capacitance of 5.80 F cm(-2) at 10 mA cm(-2) with excellent rate capability (83.6% retention for current density increased from 10 to 80 mA cm(-2)) and remarkable cycling stability (81.8% retention over 5000 cycles at a high current density of 50 mA cm(-2)). In addition, an asymmetric supercapacitor (ASC) was assembled by using the optimized NiCo2O4@NiMoO4 NWSAs as a positive electrode and activated carbon as a negative electrode in 2 M KOH electrolyte. The as-fabricated ASC device can achieve a maximum areal capacitance of 1.54 F cm(-2) and a high energy density of 5.64 mW h cm(-3) (21.7 W h kg(-1)). After charging, two ASC devices in series can efficiently power a 5 mm diameter LED and a commercial digital meter. In view of their outstanding electrochemical performance and the cost-effective fabrication process, this unique integrated nanoarchitecture may show great promise as superior pseudocapacitive electrodes for potential applications in energy storage.

关键词： Electrochemical electrodes

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Study on effect of material property on thermal power in induction cooker system with finite element method

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INTERNATIONAL JOURNAL OF APPLIED electromagneticS AND MECHANICS 2014年第1期46卷 35-42页

作者： Qiu, Li Wen, Xibo Li, Hongsheng Li, Tiegang China Three Gorges Univ Coll Elect Engn & New Energy Yichang 443002 Hubei Peoples R China Yalong River Hydropower Dev Co LTD Operating Dept Guandi Hydropower Stn Chengdu Sichuan Peoples R China

The relative permeability and electrical conductivity of the pan material, both of which vary with temperature, play an important role in thermal power of induction cooker system. A series of finite element models, including a variable relative permeability electromagnetic model, a variable electrical conductivity electromagnetic model, and an electromagnetic and thermal coupling model, have been built by ANSYS software to analyze the variation of the thermal power with relative permeability and electrical conductivity in this paper. It is indicated that thermal power increases with the relative permeability increasing, but its growth rate decreases. When the electrical conductivity increases, thermal power increases, reaches a peak value, and then decreases. Considering the variation of the relative permeability and electrical conductivity with pan temperature, the simulation results show that thermal power decreases a lot when the temperature of the material exceeds a definite value due to the low relative permeability in this case. Finally, the induction heating mechanism is clearly understood and the simulation results provide useful guidance for induction cooker design.

关键词： Material property thermal power induction cooker system finite element method

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An Improved Micromechanical Framework for Saturated Concrete Repaired by the Electrochemical Deposition Method considering the Imperfect Bonding

JOURNAL OF ENGINEERING

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JOURNAL OF engineering 2016年第1期2016卷

作者： Chen, Qing Jiang, Zhengwu Zhu, Hehua Ju, J. Woody Yan, Zhiguo Wang, Yaqiong Tongji Univ Key Lab Adv Civil Engn Mat Minist Educ 4800 Caoan Rd Shanghai 201804 Peoples R China Changan Univ Shaanxi Prov Major Lab Highway Bridge & Tunnel Xian 710064 Shaanxi Peoples R China Tongji Univ State Key Lab Disaster Reduct Civil Engn 1239 Siping Rd Shanghai 200092 Peoples R China Tongji Univ Key Lab Geotech & Underground Engn Minist Educ 1239 Siping Rd Shanghai 200092 Peoples R China Univ Calif Los Angeles Dept Civil & Environm Engn Los Angeles CA 90095 USA

The interfaces between the deposition products and concrete are not always well bonded when the electrochemical deposition method (EDM) is adopted to repair the deteriorated concrete. To theoretically illustrate the deposition healing process by micromechanics for saturated concrete considering the imperfect interfaces, an improved micromechanical framework with interfacial transition zone (ITZ) is proposed based on our recent studies. In this extension, the imperfect bonding is characterized by the ITZ, whose effects are calculated by modifying the generalized self-consistent model. Meanwhile, new multilevel homogenization schemes are employed to predict the effective properties of repaired concrete considering the ITZ effects. Moreover, modification procedures are presented to reach the properties of repaired concrete with ITZs in the dry state. To demonstrate the feasibility of the proposed micromechanical model, predictions obtained via the proposed micromechanical model are compared with those of the existing models and the experimental data, including results from extreme states during the EDM healing process. Finally, the influences of ITZ and deposition product on the healing effectiveness of EDM are discussed based on the proposed micromechanical model.

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Serration Dynamics in a Zr-Based Bulk Metallic Glass

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METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE 2015年第6期46A卷 2404-2414页

作者： Wang, Z. Qiao, J. W. Yang, H. J. Liaw, P. K. Huang, C. J. Li, L. F. Taiyuan Univ Technol Lab Appl Phys & Mech Adv Mat Coll Mat Sci & Engn Taiyuan 030024 Peoples R China Taiyuan Univ Technol Key Lab Interface Sci & Engn Adv Mat Minist Educ Taiyuan 030024 Peoples R China Univ Tennessee Dept Mat Sci & Engn Knoxville TN 37996 USA Chinese Acad Sci Tech Inst Phys & Chem Key Lab Cryogen Beijing 100190 Peoples R China

Intermittent or serrated plastic flows have been widely observed in irreversible deformation through shear banding in bulk metallic glasses (BMGs). The strain-rate-dependent plasticity under uniaxial compression at 2 x 10(-3), 2 x 10(-4), and 2 x 10(-5) s(-1) in a Zr-based BMG is investigated. Serration events have a typical time scale at a relatively higher strain rate (2 x 10(-3) s(-1)), while at lower strain rates, there is a lack of typical time scale. During serrations, the stress is falling rapidly, and the amplitude of the stress drop between the neighboring serrations is approximately equal. The stress drop vs time satisfies the exponential decay rule during jerk flows. Due to the serrated flow corresponding to the internal shear process, the free-volume model and stick-slip model are introduced to explain how the shear bands form and propagate and the cooperation of multiple shear bands. The mechanism is explained by relating the atomic-scale deformation with the macroscopic shear-band behavior, offering key ingredients to fundamentally cognize serrations in jerk flows.

关键词： Shear bands

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Longer Microwave Plasma Jet With Different Discharge Performances Originated by Plasma-Surface Interactions

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IEEE TRANSACTIONS ON PLASMA SCIENCE 2014年第10期42卷 2768-2769页

作者： Xia, Guangqing Chen, Zhaoquan Saifutdinov, Almaz Ilgizovich Eliseev, Stepan Hu, Yelin Kudryavtsev, Anatoly A. Dalian Univ Technol State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China Anhui Univ Sci & Technol Coll Elect & Informat Engn Huainan 232001 Anhui Peoples R China Univ Informat Technol Mech & Opt St Petersburg 197101 Russia St Petersburg State Univ Fac Phys St Petersburg 198504 Russia

With an input power of 50 W and a gas pressure of 100 Pa, 2.5 (without metal wire) and 10.5 cm (with a copper wire) long microwave air plasma jets are generated, respectively. When 95% Ar + 5% O-2 is instead of air, the length of the plasma jet is stretched to 15 cm. Furthermore, the length of plasma plume is affected differently by adding the processed materials. These different discharge performances originate from the effect of plasma-surface interactions.

关键词： Discharge performances local surface plasmon polaritons microwave plasma jet plasma-surface interactions

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Numerical Simulation on the Production Mechanism of Surface-Wave Plasmas Sustained along a Metal Rod

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Chinese Physics Letters 2014年第3期31卷 103-106页

作者： ZHU Long-Ji CHEN Zhao-Quan YIN Zhi-Xiang WANG Guo-Dong XIA Guang-Qing HU Ye-Lin ZHENG Xiao-Liang ZHOU Meng-Ran CHEN Ming LIU Ming-Hai College of Electrical and Information Engineering Anhui University of Science and Technology Huainan 232001 State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024

For interpreting the production mechanism of surface-wave plasmas sustained along a metal rod, electromagnetic simulation on the electromagnetic field distributions and particle-in-cell/Monte Carlo collision （PIC/MCC） simulation of the ionization process are present. The results show that the enhanced electric field of surface plasmon polaritons （SPPs） can be excited in the ion sheath layer between the negative-voltage metal rod and the surface-wave plasmas, which is responsible for maintaining the plasma discharge. Moreover, the spatio-temporal evolutions of plasma density and electric fields are simulated by the PIC/MCC model. It is further suggested that the expanded ion sheath layer can extend the length of plasma domain by increasing the plasma absorbed energy from SPPs.

关键词： electromagnetic simulation

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