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Coexistence of Bipolar and Unipolar Resistive Switching Behavior in Ag/ZnMn_2O_4/p^+-Si Device

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Journal of Wuhan University of Technology(Materials Science) 2018年第6期33卷 1433-1436页

作者： zhang yupei WANG Hua School of Materials Science and Engineering Guilin University of Electronic Technology

ZnMn_2O_4 thin films were deposited by a sol-gel technique onto a p+-Si substrate, and a RRAM device with the Ag/ZnMn_2O_4/p^+-Si structure was fabricated. The microstructure of ZnMn_2O_4 films and the resistive switching behavior of Ag/ZnMn_2O_4/p^+-Si device were investigated. ZnMn_2O_4 thin films had a spinel structure after annealing at 650 °C for 1 h. The Ag/ZnMn_2O_4/p^+-Si device showed unipolar and/or bipolar resistive switching behavior, exhibiting different ION/IOFF ratio and switching endurance properties. In bipolar resistive switching, high-resistance-state(HRS) conduction was dominated by the space-charge-limited conduction mechanism, whereas the filament conduction mechanism dictated the low resistance state(LRS). For unipolar resistive switching, HRS and LRS were controlled by the filament conduction mechanism. For bipolar resistive switching, the conduction process can be explained by the space-charge region of the p-n junction.

关键词： ZnMn2O4 resistive switching behavior bipolar unipolar

Resistive Switching Behavior of Ag/Mg0.2Zn0.8O/ZnMn2O4/p^+-Si Heterostructure Devices for Nonvolatile Memory Applications

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Journal of Wuhan University of Technology(Materials Science) 2017年第1期32卷 29-32页

作者：韦长成王华 XU Jiwen zhang yupei zhang Xiaowen YANG Ling School of Materials Science and Engineering Guilin University of Electrnic TechnologyGuilin 541004China

The Ag/Mg0.2Zn0.8O/ZnMn2O4/p^＋-Si heterostructure devices were fabricated by sol-gel spin coating technique and the resistive switching behavior,conduction mechanism,endurance characteristic,and retention properties were investigated.A distinct bipolar resistive switching behavior of the devices was observed at room *** resistance ratio R_（HRS）/RLRS of high resistance state and low resistance state is as large as four orders of magnitude with a readout voltage of 2.0 *** dominant conduction mechanism of the device is trap-controlled space charge limited current（SCLC）.The devices exhibit good durability under 1×10^3cycles and the degradation is invisible for more than 10^6 s.

关键词： heterostructure Ag/Mg0.2Zn0.8O/ZnMn2O4/p^+-Si devices resistive switching properties

Federated learning-outcome prediction with multi-layer privacy protection

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Frontiers of Computer Science 2024年第6期18卷 186604页

作者： zhang yupei LI Yuxin WANG Yifei WEI Shuangshuang XU Yunan SHANG Xuequn School of Computer Science Northwestern Polytechnical University MIIT Lab of Big Data Storage and Management

Learning-outcome prediction (LOP) is a long-standing and critical problem in educational routes. Many studies have contributed to developing effective models while often suffering from data shortage and low generalization to various institutions due to the privacy-protection issue. To this end, this study proposes a distributed grade prediction model, dubbed FecMap, by exploiting the federated learning (FL) framework that preserves the private data of local clients and communicates with others through a global generalized model. FecMap considers local subspace learning (LSL), which explicitly learns the local features against the global features, and multi-layer privacy protection (MPP), which hierarchically protects the private features, including model-shareable features and not-allowably shared features, to achieve client-specific classifiers of high performance on LOP per institution. FecMap is then achieved in an iteration manner with all datasets distributed on clients by training a local neural network composed of a global part, a local part, and a classification head in clients and averaging the global parts from clients on the server. To evaluate the FecMap model, we collected three higher-educational datasets of student academic records from engineering majors. Experiment results manifest that FecMap benefits from the proposed LSL and MPP and achieves steady performance on the task of LOP, compared with the state-of-the-art models. This study makes a fresh attempt at the use of federated learning in the learning-analytical task, potentially paving the way to facilitating personalized education with privacy protection.

关键词： federated learning local subspace learning hierarchical privacy protection learning outcome prediction privacy-protected representation learning

Fabrication and Properties of Ag/Mg0.2Zn0.8O/La0.67Ca0.33MnO/p^＋-Si Resistive Switching Heterostructure Devices

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Journal of Wuhan University of Technology(Materials Science) 2017年第3期32卷 547-551页

作者：韦长成王华 XU Jiwen zhang yupei CHEN Qisong School of Materials Science and Engineering Guilin University of Electronic Technology Guilin 541004 China

Mg0.2Zn0.8OMZO/La0.67Ca0.33MnOLCMO heterostructure was deposited on p-^＋-Si substrates by sol-gel spin coating technique. The Ag/MZO/LCMO/p-^＋-Si devices exhibit a bipolar, reversible, and remarkable current-voltage characteristic at room temperature. An obvious multilevel resistive switching effect is observed in the devices. The dominant conduction mechanism of the devices is trap-controlled space charge limited current. The resistance ratio of high resistance state and low resistance state of the devices is about six orders of magnitude, and the degradation is invisible in the devices after 250 successive switching cycles. The present results suggest that the Ag/MZO/LCMO/p-^＋-Si devices may be a potential and multilevel candidate for nonvolatile memory application.

关键词： heterostructure Ag/MZO/LCMO/p^+-Si sol-gel resistive switching

Resistance Switching Properties of Ag/Zn Mn_2O_4/p-Si Fabricated by Magnetron Sputtering for Resistance Random Access Memory

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Journal of Wuhan University of Technology(Materials Science) 2015年第6期30卷 1159-1162页

作者：王华 LI Zhida XU Jiwen zhang yupei YANG Ling QIU Wei School of Materials Science and Engineering Guilin University of Electronic Technology

A resistance random access memory（RRAM） with a structure of Ag/ZnMn2O4/p-Si was fabricated by magnetron sputtering method. Reliable and repeated switching of the resistance of ZnMn2O4 fi lms was obtained between two well-defi ned states of high and low resistance with a narrow dispersion and 3V switching voltages. Resistance ratio of the high resistance state and low resistance state was found in the range of around 10^3 orders of magnitude and up to about 10^3 test cycles. The retention time of Ag/ZnMn2O4/p-Si device is longer than 10^6 seconds and the resistance ratio between two states remains higher than 10^3 at room temperature, showing a remarkable reliability performance of the RRAM devices for nonvolatile memory application. The equivalent simulation circuits for HRS（high resistance state） and LRS（low resistance state） were also studied by impedance spectroscopy.

关键词： ZnMn2O4 resistance switching properties RRAM magnetron sputtering

Mechanical Janus lattice with plug-switch orientation

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Theoretical & Applied Mechanics Letters 2024年第1期14卷 23-26页

作者： yupei zhang Jiawei Zhong Zhengcai Zhao Ruiyu Bai Yanqi Yin Yang Yu Bo Li State Key Laboratory for Manufacturing System EngineeringShaanxi Key Laboratory of Intelligent Robots School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China Qian Xuesen Honors College Xi’an Jiaotong UniversityXi’an 710049China

In recent years,materials with asymmetric mechanical response properties(mechanical Janus materials)have been found possess numerous potential applications,*** absorption and vibration *** this study,we propose a novel mechanical Janus lattice whose asymmetric mechanical response can be switched in orientation by a *** finite element analysis and experimental verification,this lattice exhibits asymmetric displacement responses to symmetric ***,with such a plug structure inside,individual lattices can switch the orientation of asymmetry and thus achieve reprogrammable design of a mechanical structure with chained *** reprogrammable asymmetry of this material will offer multiple functions in design of mechanical metamaterials.

关键词： Janus Non-reciprocity Programmability Mechanical metamaterial

Effects of extracts from soothing-liver and invigorating-spleen formulas on the injury induced by oxidative stress in the hepatocytes of rats with non-alcoholic fatty liver disease induced by high-fat diet

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Journal of Traditional Chinese Medicine 2018年第4期38卷 535-547页

作者： Tu Guifang Gong Xiangwen Yang Qinhe Li Yuanyuan Wang Guanlong Liang Yinji zhang yupei Yan Haizhen Lin Chunmei zhang Jinwen School of Chinese Medicine Jinan University

OBJECTIVE:To investigate effects of the extracts from soothing-liver and invigorating-spleen formulas on the injury due to oxidative stress,mediated by the Nuclear factor-like 2(Nrf2)-Antioxidant response element(ARE) pathway,in the hepatocytes of rats with non-alcoholic fatty liver disease(NAFLD) induced by high-fat ***:Soothing-liver and invigorating-spleen formula mixtures were prepared for five groups:normal,model,soothing-liver formula group(SLG),invigorating-spleen formula group(ISG),integrated formula group(IG).The rat model of NAFLD was induced by feeding rats a high-fat diet(HFD).After 16 weeks,the hepatic tissue was examined following Haematoxylin-Eosin(H&E) staining and with Transmission electron microscopy(TEM).Levels of hepatic lipids,serum lipids and hepatic functions were measured using a biochemical *** were isolated from the livers of rats and were identified by cellar immunohistochemistry,cellular immunofluorescence and flow *** expression levels of Nrf2,Kelch-like epichlorohydrin-associated protein 1(Keap-1),haeme oxygenase-1(HO-1) and NAD(P)H:quinone oxidoreductase 1(NQO1) m RNAs were assessed by real-time fluorescence quantitative ***2,Keap-1,HO-1 and NQO1 proteins were measured by Western ***,the levels of oxidative stress factors Superoxide Dismutase(SOD),malonaldehyde(MDA) and Glutathione peroxidase(GSH-Px) in hepatocytes were measured by WST-1,TBA and ***:The H & E and TEM results showed that the NAFLD model rats successfully reproduced typical pathogenetic and histopathological *** liver function and levels of hepatic lipids and serum lipids from the model rats were dramatically *** with the model group,the levels of hepatic lipids,serum lipids and hepatic function in the treatment groups were ameliorated to different *** yields of purified hepatocytes in each rat were 4-5 × *** viability of the isolated hepatocytes was higher than 95%,w

关键词： NAFLD HFD Extract TCM TraditionalChinese Medicine Nuclear factor-like 2 (Nrf2) path-way Antioxidant response element (ARE)

A Composite Ansatz for Calculation of Dynamical Structure Factor

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Chinese Physics Letters 2024年第1期41卷 92-103页

作者：张玉佩莫崇杰张平康炜 HEDPS Center for Applied Physics and Technologyand School of PhysicsPeking UniversityBeijing 100871China Beijing Computational Science Research Center Beijing 100193China Institute of Applied Physics and Computational Mathematics Beijing 100088China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

We propose an ansatz without adjustable parameters for the calculation of a dynamical structure *** ansatz combines the quasi-particle Green’s function,especially the contribution from the renormalization factor,and the exchange-correlation kernel from time-dependent density functional theory together,verified for typical metals and semiconductors from a plasmon excitation regime to the Compton scattering *** has the capability to reconcile both small-angle and large-angle inelastic x-ray scattering(IXS)signals with muchimproved accuracy,which can be used as the theoretical base model,in inversely inferring electronic structures of condensed matter from IXS experimental signals *** may also be used to diagnose thermal parameters,such as temperature and density,of dense plasmas in x-ray Thomson scattering experiments.

关键词： excitation inverse verified

A novel heterologous receptor-binding domain dodecamer universal mRNA vaccine against SARS-CoV-2 variants

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Acta Pharmaceutica Sinica B 2023年第10期13卷 4291-4304页

作者： Shugang Qin Hai Huang Wen Xiao Kepan Chen Xi He Xiaoshan Tang Zhiying Huang yupei zhang Xing Duan Na Fan Qian Zheng Min Wu Guangwen Lu Yuquan Wei Xiawei Wei Xiangrong Song Department of Critical Care Medicine Frontiers Science Center for Disease-related Molecular NetworkState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan UniversityChengdu 610041China

There are currently approximately 4000 mutations in the SARS-CoV-2 S protein gene and emerging SARS-CoV-2 variants continue to spread rapidly *** vaccines with high efficacy and safety urgently need to be developed to prevent SARS-CoV-2 variants ***,we described a novel self-assembling universal mRNA vaccine containing a heterologous receptorbinding domain(HRBD)-based dodecamer(HRBD^(dodecamer))against SARS-CoV-2 variants,including Alpha(B.1.1.7),Beta(B.1.351),Gamma(B.1.***.28.1),Delta(B.1.617.2)and Omicron(B.1.1.529).HRBD containing four heterologous RBD(Delta,Beta,Gamma,and Wild-type)can form a stable dodecameric conformation under T4 trimerization tag(Flodon,FD).The HRBD^(dodecamer)-encoding mRNA was then encapsulated into the newly-constructed LNPs consisting of a novel ionizable lipid(4N4T).The obtained universal mRNA vaccine(4N4T-HRBD^(dodecamer))presented higher efficiency in mRNA transfection and expression than the approved ALC-0315 LNPs,initiating potent immune protection against the immune escape of SARS-CoV-2 caused by evolutionary *** findings demonstrated the first evidence that structure-based antigen design and mRNA delivery carrier optimization may facilitate the development of effective universal mRNA vaccines to tackle SARS-CoV-2 variants pandemic.

关键词： SARS-CoV-2 variants pandemic Universal mRNA vaccines Antigen design Heterologous RBD RBD dodecamer Lipid nanoparticles Ionizable lipids Immune escape