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Friction and wear behaviors of Al_2O_3-13 wt% TiO_2 coatings

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Rare Metals 2013年第1期32卷 87-92页

作者： Lin Lu Zhuang Ma Fu-Chi Wang yan-bo liu National Key Laboratory of Science and Technology on Materials under Shock and Impact School of Materials Science and Engineering Beijing Institute of Technology

Abstract Nanostructured and conventional AlzO3- 13 wt%TiO2 coatings were manufactured by air plasma spray. Friction and wear behaviors of coatings were investigated at room and elevated temperatures using an SRV wear test machine. The nanostructured coating has ＂two regions＂ microstructure, while the conventional coating has typical layered microstructure with obvious interfaces among splats. The coefficient of friction decreases with rising of temperature because of the for- mation of tribo-layer at elevated temperatures. The wear resistance of the nanostructured coatings is higher than that of the conventional coating, and the wear threshold of applied load is 30 N for conventional coating and 40 N for nanostructure coating. The wear resistance difference is related to the ＂two regions＂ microstructure of nanostruc- ture coating, which could blunt or branch the cracks propagation. In our test ranges, the wear rates rising are more sensitive with the applied wear load rising than with the temperature rising.

关键词： A1203-TiO2 Tribo-layer Wear resistance

Experimental observations of ferroelectricity in double pyrochlore Dy2Ru2O7

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Frontiers of physics 2014年第1期9卷 82-89页

作者： Zai-Chun Xu Mei-Feng liu Lin Lin Huimei liu Zhi-bo yan Jun-Ming liu Laboratory of Solid State Microstructures Nanjing University Nanjing 210093 China

Double pyrochlore Dy2Ru207 is synthesized and its magnetism and ferroelectricity below the Ru4＋ spin ordering temperature （NI00 K） are investigated. The ferroelectric transition appears at -18 K, much higher than the Dy3＋ spin ordering point at -1.8 K and lower than the Ru4＋ spin ordering point at -100 K. The measured electric polarization at ,-2 K is as big as 145℃/m2 in the polycrystalline samples. It is argued that the ferroelectricity is possibly ascribed to the electric dipole ordering arising from the collective monopole excitations in the Dy3＋ tetrahedrons in prior to the Dy3＋ spin ordering into spin-ice like state below -1.8 K.

关键词： pyrochlore oxides multiferroics magnetically induced ferroelectricity

A novel graph oversampling framework for node classification in class-imbalanced graphs

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Science China(Information Sciences) 2024年第6期67卷 214-229页

作者： Riting XIA Chunxu ZHANG yan ZHANG Xueyan liu bo yanG Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University College of Artificial Intelligence Jilin University College of Computer Science and Technology Jilin University College of Communication Engineering Jilin University

Graph neural network(GNN) is a promising method to analyze graphs. Most existing GNNs adopt the class-balanced assumption, which cannot deal with class-imbalanced graphs well. The oversampling technique is effective in alleviating class-imbalanced problems. However, most graph oversampling methods generate synthetic minority nodes and their edges after applying GNNs. They ignore the problem that the representations of the original and synthetic minority nodes are dominated by majority nodes caused by aggregating neighbor information through GNN before oversampling. In this paper, we propose a novel graph oversampling framework, termed distribution alignment-based oversampling for node classification in classimbalanced graphs(named Graph-DAO). Our framework generates synthetic minority nodes before GNN to avoid the dominance of majority nodes caused by message passing in GNNs. Additionally, we introduce a distribution alignment method based on the sum-product network to learn more information about minority nodes. To our best knowledge, it is the first to use the sum-product network to solve the class-imbalanced problem in node classification. A large number of experiments on four real datasets show that our method achieves the optimal results on the node classification task for class-imbalanced graphs.

关键词： graph neural network class-imbalanced graphs sum-product network oversampling node classification

The Application of Deep Brain Stimulation for Parkinson’s Disease on the Motor Pathway:A Bibliometric Analysis across 10 Years

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Current Medical Science 2023年第6期43卷 1247-1257页

作者： Yong-tang SONG yan-bo liu Hong-bing XIANG Anne Manyande Zhi-gang HE Medical Association of Hubei Province Wuhan430060China Department of Anesthesiology Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain HealthWuhan Clinical Research Center for Geriatric AnesthesiaTongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China School of Human and Social Sciences University of West LondonLondon0044UK Department of Emergency Medicine Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China Department of Critical Care Medicine Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China

Background and Objective Since its initial report by James Parkinson in 1817,Parkinson’s disease(PD)has remained a central subject of research and clinical *** disease is estimated to affect approximately 1%of adults aged 60 and *** brain stimulation,emerging as an alternative therapy for end-stage cases,has offered a lifeline to numerous *** review aimed to analyze publications pertaining to the impact of deep brain stimulation on the motor pathway in patients with PD over the last *** Data were obtained from the Web of Science Core Collection through the library of Huazhong University of Science and Technology(China).The search strategy encompassed the following keywords:“deep brain stimulation”,“Parkinson’s disease”,“motor pathway”,and“human”,from January 1,2012,to December 1,***,this review visualized the findings using the Citespace *** The results indicated that the United States,the United Kingdom,Germany,and China were the primary contributors to this research *** College London,Capital Medical University,and Maastricht University were the top 3 research institutions in the research *** Foltynie ranked first with 6 publications,and the journals of Brain and Brain Stimulation published the greatest number of relevant *** prevailing research focal points in this domain,as determined by keywords“burst analysis”,“encompassed neuronal activity”,“nucleus”,“hyper direct pathway”,*** This study has provided a new perspective through bibliometric analysis of the deep brain stimulation therapy for treating patients with PD,which can shed light on future research to advance our comprehension of this particular field of study.

关键词： deep brain stimulation Parkinson’s disease motor pathway bibliometric analysis

Switched-capacitor Based Seven-level boost Inverter with a Reduced Number of Devices

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 381-391页

作者： Weijie Lin Jun Zeng bo Fu Zhixing yan Junfeng liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China WISDRI Engineering&Research Incorporation Limited Wuhan 430074China Department of Energy Aalborg UniversityAalborg 9220Denmark School of Automation Science and Engineering South China University of TechnologyGuangzhou 510641China

The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and *** by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this *** proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy *** configuration of topology and operating principles are illustrated in *** natural balance of capacitors and capacitance calculations are deduced as ***,the comparative study is conducted for different types of *** results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power ***,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.

关键词： Multilevel inverters voltage gain natural balance renewable energy generation reduced number of elements

BaCe_(0.8)Fe_(0.1)Ni_(0.1)O_(3−δ)-impregnated Ni-GDC by phase-inversion as an anode of solid oxide fuel cells with on-cell dry methane reforming

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Journal of Advanced Ceramics 2024年第6期13卷 834-841页

作者： yanya liu Jun Luo Cheng Li bo liu Dong yan Jian Li Lichao Jia School of Materials Science and Engineering State Key Laboratory of Materials Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074China

BaCe_(0.8)Fe_(0.1)Ni_(0.1)O_(3−δ)(BCFN)in a perovskite structure is impregnated consecutively by BCFN solution and BCFN suspension into a phase-inversion prepared NiO–Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)scaffold as an anode for solid oxide fuel cells(SOFCs)with on-cell dry reforming of methane(DRM).The whole pore surface of the scaffold is covered by small BCFN particles formed by BCFN solution impregnation;the large pores near the scaffold surface are filled by BCFN aerogels with a high specific surface area produced by BCFN suspension impregnation,which act as a catalytic layer for on-cell *** reduction,the anode consists of a Ni–GDC scaffold and BCFN particles with exsolved FeNi3 *** BCFN-impregnated Ni–GDC anode has higher electrical conductivity,electrochemical activity,and resistance to carbon deposition,with which the cell shows maximum power densities between 1.44 and 0.92 W·cm^(−2) when using H_(2) and between 1.09 and 0.50 W·cm^(−2) when using CO_(2)–CH_(4) at temperatures ranging from 750 to 600℃.A stable performance at 400 mA·cm^(−2) and 700℃is achieved using 45%CO_(2)–45%CH_(4)–10%N_(2) for more than 400 h without carbon deposition,benefiting from the impregnated BCFN aerogel with a high specific surface area and water adsorbability.

关键词： aerogel solid oxide fuel cells(SOFCs) phase-inversion dry reforming of methane(DRM) carbon resistance

Unusual photocarrier and coherent phonon dynamics behaviors of layered PdSe_(2)unveiled by ultrafast spectroscopy of the edge surface

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 143-152页

作者： Tiantian Yun Changfu Huo Jinluo Cheng Zhi-bo liu Xiao-Qing yan Key Laboratory of Weak-Light Nonlinear Photonics Ministry of EducationSchool of PhysicsNankai UniversityTianjin 300071China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China GPL Photonics Laboratory Key Laboratory of Luminescence Science and TechnologyChinese Academy of Sciences&State Key Laboratory of Luminescence Science and ApplicationsChangchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

Layered materials exhibit different electronic and phonon properties along in-plane and out-of-plane directions;existing studies focus on their in-plane behaviors,and the influence of such anisotropies on the dynamics of photocarriers and phonons is ***,we fabricate layered PdSe_(2)crystals with flat edge surfaces and compare the time-resolved ultrafast spectroscopies on their basal and edge *** differences in the transient reflection spectroscopies reveal the inconsistent photocarrier and phonon dynamics behaviors on the two surfaces:the slow hot carrier relaxation process is accelerated and the thermoelasticity-induced longitudinal coherent acoustic phonon oscillation completely vanishes on the edge surface,as compared with the basal *** analysis reveals that the inconsistent hot carrier dynamics originate from the anisotropic properties of low-energy phonons in PdSe_(2),and the absence of phonon oscillation on the edge surface results from the wavevector-limited sensitivity of acoustic B_(1u)***,polarization-dependent spectroscopies indicate the diverse optical anisotropies beyond the in-plane of PdSe_(2).This work provides a new method to explore unique physical properties and modulate the optical anisotropy of layered materials.

关键词： PdSe_(2) ultrafast spectroscopy edge surface carrier dynamics coherent phonon oscillation anisotropy

Tracking Regulatory Mechanism of Trace Fe on Graphene Electromagnetic Wave Absorption

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Nano-Micro Letters 2024年第4期16卷 79-96页

作者： Kaili Zhang Yuhao liu yanan liu Yuefeng yan Guansheng Ma bo Zhong Renchao Che Xiaoxiao Huang School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001People’s Republic of China MIIT Key Laboratory of Advanced Structural‑Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001People’s Republic of China School of Materials Science and Engineering Harbin Institute of Technology at WeihaiWeihai 264209People’s Republic of China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative MaterialsFudan UniversityShanghai 200438People’s Republic of China

Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.

关键词： Reduced graphene oxide Fe nanosheets Dielectric loss Electromagnetic wave absorption

Bio-inspired surface manipulation of halloysite nanotubes for highperformance flame retardant polylactic acid nanocomposites

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Nano Research 2024年第3期17卷 1595-1606页

作者： Yaru Sun Bin Yu yan liu Junbo yan Zixi Xu bo Cheng Fenglei Huang Jun Wang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China National Engineering Research Center of Flame Retardant Materials Beijing Institute of TechnologyBeijing 100081China

High-performance flame-retardant polylactic acid(PLA)bio-composites based on biobased fillers to meet usage requirements represents a promising direction for creating a sustainable *** flame retardant PLA composites have been reported extensively,it still remains a huge challenge to develop mechanically *** flame retardant PLA composites due to plastication effect of organic flame retardants and poor compatibility of organic fillers with the matrix lead to the severe deterioration in mechanical *** this work,a bio-inspired surface manipulation strategy for halloysite nanotubes(HNTs)was proposed via a facile and green self-assembly *** structure and morphology of bio-inspired HNTs(b-HNTs)proved that biomass nanofillers(PA-NA-Fe)grew well both within the lumen and on the surface of *** growth of biomass on the inner and outer surfaces of HNTs was inspired from wooden towards enhancing the interface compatibility and imparting multi-properties to PLA *** mechanical properties(tensile,thermomechanical and anti-impact mechanical),great fire safety(heat release and smoke emission),thermostability and improved electromagnetic interference shielding effectiveness of this well-designed PLA nanocomposite were *** mechanisms of the enhanced performances of the PLA bio-composites by loading b-HNTs were *** work presents a facile and environmentally-friendly bio-inspired modification strategy for HNTs to fabricate high-performance,multi-functional polymer composites,which is also suitable for surface modification of many other nanomaterials,including nanofibers,nanotubes,nanowires,and nanosheets.

关键词： mechanical properties thermostability fire safety electromagnetic interference shielding biomass