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Understanding supercapacitors based on nano-hybrid materials with interfacial conjugation

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Progress in Natural Science:Materials International 2013年第3期23卷 245-255页

作者： george Z.chen Department of Chemical and Environmental Engineering and Energy and Sustainability Research DivisionFaculty of EngineeringUniversity of NottinghamNottingham NG7 2RDUK

The recent fast development of supercapacitors,also known scientifically as electrochemical capacitors,has benefited significantly from synthesis,characterisations and electrochemistry of ***,the principle of supercapacitors is explained in terms of performance characteristics and charge storage mechanisms,*** layer(or interfacial) capacitance and *** semiconductor band model is applied to qualitatively account for the pseudo-capacitance in association with rectangular cyclic voltammograms(CVs) and linear galvanostatic charging and discharging plots(gCDs),aiming to differentiate supercapacitors from rechargeable *** invalidity of using peak shaped CVs and non-linear gCDs for capacitance measurement is highlighted.A selective review is given to the nano-hybrid materials between carbon nanotubes and redox active materials such as electronically conducting polymers and transition metal oxides.A new concept,"interfacial conjugation",is introduced to reflect the capacitance enhancement resulting from π-π stacking interactions at the interface between two materials with highly conjugated chemical *** prospects of carbon nanotubes and graphenes for supercapacitor applications are briefly compared and ***,this article can help readers to understand supercapacitors and nano-hybrid materials so that further developments in materials design and synthesis,and device engineering can be more efficient and objective.

关键词： Supercapacitors Carbon nanotubes graphenes Electronically conducting polymers Transition metal oxides Interfacial conjugation

Modeling urban redevelopment:A novel approach using time-series remote sensing data and machine learning

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geography and Sustainability 2024年第2期5卷 211-219页

作者： Li Lin Liping Di chen Zhang Liying guo Haoteng Zhao Didarul Islam Hui Li Ziao Liu gavin Middleton Center for Spatial Information Science and Systems George Mason UniversityFairfaxVA22030USA Department of geography and geoinformation Science George Mason UniversityFairfaxVA22030USA

Accurate mapping and timely monitoring of urban redevelopment are pivotal for urban studies and decisionmakers to foster sustainable urban *** mapping methods heavily depend on field surveys and subjective questionnaires,yielding less objective,reliable,and timely *** advancements in geographic Information Systems(gIS)and remote-sensing technologies have improved the identification and mapping of urban redevelopment through quantitative analysis using satellite-based ***,challenges persist,particularly concerning accuracy and significant temporal *** study introduces a novel approach to modeling urban redevelopment,leveraging machine learning algorithms and remote-sensing *** methodology can facilitate the accurate and timely identification of urban redevelopment *** study’s machine learning model can analyze time-series remote-sensing data to identify spatio-temporal and spectral patterns related to urban *** model is thoroughly evaluated,and the results indicate that it can accurately capture the time-series patterns of urban *** research’s findings are useful for evaluating urban demographic and economic changes,informing policymaking and urban planning,and contributing to sustainable urban *** model can also serve as a foundation for future research on early-stage urban redevelopment detection and evaluation of the causes and impacts of urban redevelopment.

关键词： Urban redevelopment Urban sustainability Remote sensing Time-series analysis Machine learning

Understanding the role of transition metal single-atom electronic structure in oxysulfur radical-mediated oxidative degradation

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Environmental Science and Ecotechnology 2024年第4期20卷 247-258页

作者： guanshu Zhao Jing Ding Jiayi Ren Qingliang Zhao chengliang Mao Kun Wang Jessica Ye Xueqi chen Xianjie Wang Mingce Long State Key Laboratory of Urban Water Resources and Environment School of EnvironmentHarbin Institute of TechnologyHarbin150090China Solar Fuels group Department of ChemistryUniversity of Toronto80 St.George StreetTorontoOntarioM5S 3H6Canada School of Physics Harbin Institute of TechnologyHarbin150001China School of Environmental Science and Engineering Key Laboratory of Thin Film and Microfabrication Technology(Ministry of Education)Shanghai Jiao Tong University800 Dongchuan RoadShanghai200240China

The ubiquity of refractory organic matter in aquatic environments necessitates innovative removal *** radical-based advanced oxidation has emerged as an attractive solution,offering high selectivity,enduring efficacy,and anti-interference *** many technologies,sulfite activation,leveraging its cost-effectiveness and lower toxicity compared to conventional persulfates,stands ***,the activation process often relies on transition metals,suffering from low atom *** we introduce a series of single-atom catalysts(SACs)employing transition metals on g-C_(3)N_(4)substrates,effectively activating sulfite for acetaminophen *** highlight the superior performance of Fe/CN,which demonstrates a degradation rate constant significantly surpassing those of Ni/CN and Cu/*** investigation into the electronic and spin polarization characteristics of these catalysts reveals their critical role in catalytic efficiency,with oxysulfur radical-mediated reactions ***,under visible light,the catalytic activity is enhanced,attributed to an increased generation of oxysulfur radicals and a strengthened electron donation-back donation *** proximity of Fe/CN's d-band center to the Fermi level,alongside its high spin polarization,is shown to improve sulfite adsorption and reduce the HOMO-LUMO gap,thereby accelerating photo-assisted sulfite *** work advances the understanding of SACs in environmental applications and lays the groundwork for future water treatment technologies.

关键词： Single-atom catalysts(SACs) Oxysulfur radical Sulfite activation Spin polarization Electronic structure

Carbon nanotube and conducting polymer composites for supercapacitors

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Progress in Natural Science:Materials International 2008年第7期18卷 777-788页

作者： Daniel Jewell george Z. chen School of Chemical and Environmental and Mining Engineering University of Nottingham University ParkNottingham NG7 2RD UK

Composites of carbon nanotubes and conducting polymers can be prepared via chemical synthesis, electrochemical deposition on pre- formed carbon nanotube electrodes, or by electrochemical co-deposition. The composites combine the large pseudocapacitance of the conducting polymers with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the carbon nanotubes. The electrochemically co-deposited composites are the most homogeneous and show an unusual interaction between the polymer and nanotubes, giving rise to a strengthened electron delocalisation and conjugation along the polymer chains. As a result they exhibit excellent electrochemical charge storage properties and fast charge/discharge switching, making them promising electrode mate- rials for high power supercapacitors.

关键词： Supercapacitor Carbon nanotube Conducting polymer

gOAL: the comprehensive gene ontology analysis layer

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Science China(Information Sciences) 2016年第7期59卷 86-93页

作者： Jong Cheol JEONg george LI Xue-Wen chen Department of Pathology Harvard Medical School Beth Israel Deaconess Medical Center Bioinformatics and Computational Life Sciences Laboratory University of Kansas Department of Computer Science Wayne State University

Homogeneity or heterogeneity of cells is the most fundamental and important features of analyzing biological associations of genes and gene products. Recent bioinformatics technology requires an automated high-throughput analysis application that can handle massively produced data from next generation sequences and dramatically increased size of public proteomic/genomic databases. Although gene ontology(gO) database has been newly spotlighted on its wide coverage of machine-readable terminologies, its complex DB schema and vast amount of applications utilizing gO without deep considerations of gO term relations dilute the actual power of gO-based analysis and resulted in misleading/under estimated outcomes. Meanwhile, our recent studies showed that BSM score, a new way of measuring functional similarity, clearly outperformed existing conventional methods. However, implementing BSM score that requires integrating multiple databases and calculating scoring matrix is not trivial and even difficult for bioinformatics experts; therefore, a web-based graphical user interface(gUI) tool, gene Ontology Analysis Layer(gOAL: http://***/chenlab/goal) is introduced to provide user-friendly gO application powered by state of art functional similarity metric,BSM score.

关键词： gene ontology molecular function functional similarity network-based analysis BSM score

When joggers meet robots:the past,present,and future of research on humanoid robots

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Bio-Design and Manufacturing 2019年第2期2卷 108-118页

作者： george H.Z.Liu Michael Z.Q.chen Yonghua chen Department of Mechanical Engineering The University of Hong KongPokfulamHong KongPeople’s Republic of China School of Automation Nanjing University of Science and TechnologyNanjing 210094JiangsuPeople’s Republic of China

Spawned by fast-paced progress in new materials and integrate circuit technology,the past two decades have witnessed tremendous development of humanoid robots for both scientific and commercial purposes,*** response and daily life *** the root of this trend are the increasing research interests and cooperation opportunities across different laboratories and *** application-driven requirements of high effectiveness and reliability of humanoid robots led intensive research and development in humanoid locomotion and control *** spite of the progress in the area,challenges such as unnatural locomotion control,inefficient multi-motion planning,and relatively slow disturbances recovery set further requirements for the next generation of humanoid ***,the purpose of this work is to review the current development of highly representative bipedal humanoid robots and discuss the potential to move the ideas and models forward from laboratory settings into the real *** this end,we also review the current clinical understanding of the walking and running dynamics to make the robot more human-like.

关键词： Humanoid robot Walking dynamics Dynamic control Bio-inspired gait Robot efficiency Shock absorption

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Efficient and Accurate Numerical Methods Using the Accelerated Spectral Deferred Correction for Solving Fractional Differential Equations

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Numerical Mathematics(Theory,Methods and Applications) 2022年第4期15卷 876-902页

作者： Xuejuan chen Zhiping Mao george Em Karniadakis School of Science Jimei UniversityXiamen 361021China School of Mathematical Sciences Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific ComputingXiamen UniversityXiamenChina Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA

We develop an efficient and accurate spectral deferred correction(SDC)method for fractional differential equations(FDEs)by extending the algorithm in[14]for classical ordinary differential equations(ODEs).Specifically,we discretize the resulted Picard integral equation by the SDC method and accelerate the convergence of the SDC iteration by using the generalized minimal residual algorithm(gMRES).We first derive the correction matrix of the SDC method for FDEs and analyze the convergence region of the SDC *** then present several numerical examples for stiff and non-stiff FDEs including fractional linear and nonlinear ODEs as well as fractional phase field models,demonstrating that the accelerated SDC method is much more efficient than the original SDC method,especially for stiff ***,we resolve the issue of low accuracy arising from the singularity of the solutions by using a geometric mesh,leading to highly accurate solutions compared to uniform mesh solutions at almost the same computational ***,for long-time integration of FDEs,using the geometric mesh leads to great computational savings as the total number of degrees of freedom required is relatively small.

关键词： Stiff problem generalized minimal residual geometric mesh refinement long time evolution fractional phase field models

ANALYSIS OF FREEMIUM BUSINESS MODEL CONSIDERINg NETWORK EXTERNALITIES AND CONSUMER UNCERTAINTY

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Journal of Systems Science and Systems Engineering 2018年第1期27卷 78-105页

作者： Wuhua chen Zhongsheng Hua Zhe george Zhang Wenjie Bi Beedie School of Business Simon Fraser University Burnaby Canada

An emerging business model increasingly used by companies in the online software market is to provide both a free basic version and a paid premium version for a service or a product to customers. Such a setting is often called freemium model. The existence of the free version can reduce the customer uncertainty regarding the evaluation of the commercial software and make use of network effect to improve the firm＇s profit. However, the freemium model may also have the cannibalization effect which can hurt the profit. Hence, the from needs to determine the optimal content for the free version and the optimal price for the premium version to maximize its profit. In this paper, thst, we obtain the optimal decisions of the freemium model and their properties. Second, we compare the freemium model with the traditional charge-for-everything model that all content of the product need to be charged in terms of the profit, customer welfare, and social welfare. The results show that when customer underestimates the value of the software significantly and the true value of the software is high enough, the freemium model can generate higher profit, higher customer welfare, and higher social welfare. Otherwise, the freemium model may not deliver the desired results.

关键词： Freemium pricing network effect customer uncertainty software social welfare

Charge Storage Properties of Aqueous Halide Supercapatteries with Activated Carbon and graphene Nanoplatelets as Active Electrode Materials

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Energy & Environmental Materials 2021年第3期4卷 481-491页

作者： Bamidele Akinwolemiwa Chaohui Wei Qinghua Yang george Z.chen International Doctoral Innovation Centre Faculty of Science and EngineeringThe University of Nottingham Ningbo ChinaNingbo 315100China Department of Chemical and Environmental Engineering Faculty of Science and EngineeringThe University of Nottingham Ningbo ChinaNingbo 315100China Department of Chemical and Environmental Engineering and Advanced Materials Research GroupFaculty of EngineeringThe University of NottinghamNottingham NG72RDUK

Device level performance of aqueous halide supercapatteries fabricated with equal electrode mass of activated carbon or graphene nanoplatelets has been *** was revealed that the surface oxygen groups in the graphitic structures of the nanoplatelets contributed toward a more enhanced charge storage capacity in bromide containing redox ***,the rate performance of the devices could be linked to the effect of the pore size of the carbons on the dynamics of the inactive alkali metal counterion of the redox halide ***,the charge storage performance of aqueous halide supercapatteries with graphene nanoplatelets as the electrode material may be attributed to the combined effect of the porous structure on the dynamics of the non-active cations and a possible interaction of the Br^(-)/(Br_(2)+Br^(-)_(3))redox triple with the surface oxygen groups within the graphitic layer of the ***,it has been shown that the surface groups and microstructure of electrode materials must be critically correlated with the redox electrolytes in the ongoing efforts to commercialize these devices.

关键词： carbon materials device engineering energy efficiency redox electrolyte supercapattery

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