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Multiplicity of solutions for the semilinear subelliptic Dirichlet problem

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Science China Mathematics 2024年第3期67卷 475-504页

作者： Hua Chen Hong-ge Chen Jin-ning Li Xin Liao School of Mathematics and Statistics Wuhan UniversityWuhan 430072China Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

In this paper,we study the semilinear subelliptic equation{−△Xu=f(x,u)+g(x,u)inΩ,u=0 on∂Ω,where△X=−∑m i=1 Xi∗Xi is the self-adjoint Hormander operator associated with the vector fields X=(X_(1),X_(2),...,X_(m))satisfying the Hormander's condition,f(x,u)∈C(Ω×R),g(x,u)is a Carathéodory function onΩ×R,andΩis an open bounded domain in R~n with smooth boundary.Combining the perturbation from the symmetry method with the approaches involving the eigenvalue estimate and the Morse index in estimating the minimax values,we obtain two kinds of existence results for multiple weak solutions to the problem above.Furthermore,we discuss the difference between the eigenvalue estimate approach and the Morse index approach in degenerate situations.Compared with the classical elliptic cases,both approaches here have their own strengths in the degenerate cases.This new phenomenon implies that the results in general degenerate cases would be quite different from the situations in classical elliptic cases.

关键词： degenerate elliptic equations Hormander operators perturbation method Morse index

Copper-Free Click Chemistry-Mediated Assembly of Single Quantum Dot Nanosensor for Accurately Monitoring Locus-Specific m^(6)A in Cancer Cells

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Chinese Journal of Chemistry 2024年第5期42卷 499-504页

作者： Yue-Ying Li ning-ning Zhao Yi-Xuan geng Qian Han Jian-ge Qiu Bing-Hua Jiang Zi-Yue Wang Chun-Yang Zhang Translational Medicine Center The First Affiliated Hospital of Zhengzhou UniversityThe Academy of Medical SciencesHenan Institute of Medical and Pharmaceutical Sciences BGI CollegeZhengzhou UniversityZhengzhouHenan450052 China College of Chemistry Chemical Engineering and Materials ScienceShandong Normal UniversityJinanShandong250014 China School of Chemistry and Chemical Engineering Southeast UniversityNanjingJiangsu211189 China

N6-methyladenosine(m^(6)A)plays an important role in embryogenesis,nuclear export,transcription splicing,and protein translation control.Herein,we demonstrate a copper-free click chemistry-mediated assembly of single quantum dot(QD)nanosensor for accurately monitoring locus-specific m^(6)A in cancer cells.The m^(6)A-sensitive endoribonuclease MazF can digest the unmethylated A-RNA,and the intact m^(6)A-RNA then hybridizes with DNA probes a and b to produce a sandwich hybrid,initiating the click chemistry to generate probe a–b ligation product via first tandem ligation detection reaction(LDR)cycle.Subsequently,DNA probes c and d can hybridize with the probe a–b ligation product to generate the probe c–d ligation product via second LDR cycle.Both LDR cycles can be repeated through denaturation and annealing reaction to generate abundant biotin-/fluorophore-modified probe c–d ligation products that can easily assemble on the QD surface to induce distinct fluorescence resonance energy transfer(FRET)between QD and Cy5.This assay can be homogenously performed without the involvement of copper catalyst,m^(6)A-specific antibody,radioactive labeling,ligase enzyme,enzymatic reverse transcription,and next-generation sequencing.Moreover,it can discriminate even 0.01% m^(6)A level in complex samples and accurately measure cellular m^(6)A-RNA expression,providing a promising avenue for clinical diagnostics and biomedical research.

关键词： RNA methylation Click chemistry Förster resonance energy transfer Biosensor Cancer

Alloy as advanced catalysts for electrocatalysis:From materials design to applications

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Chinese Chemical Letters 2024年第6期35卷 104-122页

作者： Pingfan Zhang Shihuan Hong ning Song Zhonghui Han Fei ge Gang Dai Hongjun Dong Chunmei Li Advanced Chemical Engineering Laboratory of Green Materials and Energy of Jiangsu Province Institute of Green Chemistry and Chemical TechnologySchool of Chemistry and Chemical EngineeringJiangsu UniversityZhenjiang 212013China Daqo Group Co.Ltd. Zhenjiang 212221China Key Laboratory of Groundwater Resources and Environment Ministry of EducationJilin Provincial Key Laboratory of Water Resource and EnvironmentCollege of New Energy and EnvironmentJilin UniversityChangchun 130021China

With the deep integration of electrochemical research with energy,environment,catalysis,and other fields,more and more new electrochemical catalytic reactions have entered our research field.Alloy catalysts have recently emerged as a new type of nanomaterial due to the rapid development of kinetic controlled synthesis technology.These materials offer several advantages over monometallic catalysts,including larger element combinations,complex geometries,bifunctional sites,and reduced use of precious metals.This paper provides a review of alloy electrocatalysts that are designed and prepared specifically for electrocatalytic applications.The use of alloy materials in electrocatalyst design is also discussed,highlighting their widespread application in this field.First,various synthesis methods and synthesis mechanisms are systematically summarized.Following that,by correlating the properties of materials with the structure,relevant strategies toward advanced alloy electrocatalysts including composition regulation,size,morphology,surface engineering,defect engineering,interface engineering and strain engineering are classified.In addition,the important electrocatalytic applications and mechanisms of alloy electrocatalysts are described and summarized.Finally,the current challenges and prospects regarding the development of alloy nanomaterials are proposed.This review serves as a springboard from a fundamental understanding of alloy structural dynamics to design and various applications of electrocatalysts,particularly in energy and environmental sustainability.

关键词： Alloy Nanomaterial Electrocatalyst Materials design Electrocatalysis

DDoS Detection for 6G Internet of Things: Spatial-Temporal Trust Model and New Architecture

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China Communications 2022年第5期19卷 141-149页

作者： Yinglun Ma Xu Chen Wei Feng ning ge Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Beijing 100084China

With the rapid development of the sixth generation(6G)network and Internet of Things(IoT),it has become extremely challenging to efficiently detect and prevent the distributed denial of service(DDoS)attacks originating from IoT devices.In this paper we propose an innovative trust model for IoT devices to prevent potential DDoS attacks by evaluating their trustworthiness,which can be deployed in the access network of 6G IoT.Based on historical communication behaviors,this model combines spatial trust and temporal trust values to comprehensively characterize the normal behavior patterns of IoT devices,thereby effectively distinguishing attack traffic.Experimental results show that the proposed method can efficiently distinguish normal traffic from DDoS traffic.Compared with the benchmark methods,our method has advantages in terms of both accuracy and efficiency in identifying attack flows.

关键词： sixth generation(6G)network internet of things(IoT) trust model distributed denial of service(DDoS)

Deep Learning-Based Symbol Detection for Time-Varying Nonstationary Channels

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China Communications 2022年第3期19卷 158-171页

作者： Xuantao Lyu Wei Feng ning ge Xianbin Wang Research Center of Networks and Communications Peng Cheng LaboratoryShenzhen 518055China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Department of Electrical and Computer Engineering The University of Western OntarioLondonON N6A 5B9Canada

The highly dynamic channel(HDC)in an extremely dynamic environment mainly has fast timevarying nonstationary characteristics.In this article,we focus on the most difficult HDC case,where the channel coherence time is less than the symbol period.To this end,we propose a symbol detector based on a long short-term memory(LSTM)neural network.Taking the sampling sequence of each received symbol as the LSTM unit's input data has the advantage of making full use of received information to obtain better performance.In addition,using the basic expansion model(BEM)as the preprocessing unit significantly reduces the number of neural network parameters.Finally,the simulation part uses the highly dynamic plasma sheath channel(HDPSC)data measured from shock tube experiments.The results show that the proposed BEM-LSTM-based detector has better performance and does not require channel estimation or channel model information.

关键词： highly dynamic channel deep neural network long short-term memory basis expansion model symbol detection

MEC-Empowered Non-Terrestrial Network for 6G Wide-Area Time-Sensitive Internet of Things

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Engineering 2022年第1期8卷 96-107页

作者： Chengxiao Liu Wei Feng Xiaoming Tao ning ge Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China

In the upcoming sixth-generation(6G)era,the demand for constructing a wide-area time-sensitive Internet of Things(IoT)continues to increase.As conventional cellular technologies are difficult to directly use for wide-area time-sensitive IoT,it is beneficial to use non-terrestrial infrastructures,including satellites and unmanned aerial vehicles(UAVs).Thus,we can build a non-terrestrial network(NTN)using a cell-free architecture.Driven by the time-sensitive requirements and uneven distribution of IoT devices,the NTN must be empowered using mobile edge computing(MEC)while providing oasisoriented on-demand coverage for devices.Nevertheless,communication and MEC systems are coupled with each other under the influence of a complex propagation environment in the MEC-empowered NTN,which makes it difficult to coordinate the resources.In this study,we propose a process-oriented framework to design communication and MEC systems in a time-division manner.In this framework,large-scale channel state information(CSI)is used to characterize the complex propagation environment at an affordable cost,where a nonconvex latency minimization problem is formulated.Subsequently,the approximated problem is provided,and it can be decomposed into sub-problems.These sub-problems are then solved iteratively.The simulation results demonstrated the superiority of the proposed process-oriented scheme over other algorithms,implied that the payload deployments of UAVs should be appropriately predesigned to improve the efficiency of using resources,and confirmed that it is advantageous to integrate NTN with MEC for wide-area time-sensitive IoT.

关键词： Cell-free Mobile edge computing Non-terrestrial networks Sixth-generation Wide-area time-sensitive IoT

Secrecy Rate Maximization for 6G Cognitive Satellite-UAV Networks

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China Communications 2023年第1期20卷 246-260页

作者： Chengleyang Lei Wei Feng Yunfei Chen ning ge Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China School of Engineering University of WarwickCoventry CV47ALUnited Kingdom

To cover remote areas where terrestrial cellular networks may not be available,non-terrestrial infrastructures such as satellites and unmanned aerial vehicles(UAVs)can be utilized in the upcoming sixth-generation(6G)era.Considering the spectrum scarcity problem,satellites and UAVs need to share the spectrum to save costs,leading to a cognitive satellite-UAV network.Due to the openness of both satellite links and UAV links,communication security has become a major concern in cognitive satelliteUAV networks.In this paper,we safeguard a cognitive satellite-UAV network from a physical layer security(PLS)perspective.Using only the slowlyvarying large-scale channel state information(CSI),we jointly allocate the transmission power and subchannels to maximize the secrecy sum rate of UAV users.The optimization problem is a mixed integer nonlinear programming(MINLP)problem with coupling constraints.We propose a heuristic algorithm which relaxes the coupling constraints by the penalty method and obtains a sub-optimal low-complexity solution by utilizing random matrix theory,the max-min optimization tool,and the bipartite graph matching algorithm.The simulation results corroborate the superiority of our proposed scheme.

关键词： channel allocation cognitive satellite-UAV network physical layer security power allocation

A549/DDP derived exosomes can affect cisplatin chemosensitivity via transporting CXCR4 to A549 cells

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BIOCELL 2022年第3期46卷 711-720页

作者： MINGMING FANG ning ge JIANFANG LIU YAYUN CUI Department of Radiation Oncology Changzhou Cancer Hospital Affiliated to Soochow UniversityChangzhou213032China Department of Cancer Radiotherapy The First Affiliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of China(Anhui Provincial Cancer Hospital)Hefei230031China Department of Neurology The Affiliated Changzhou No.2 People’s Hospital of Nanjing Medical UniversityChangzhou213001China

The resistance of cancer cells to the anti-cancer drugs is the most important reason that affecting the efficacy of the non-small cell lung cancer(NSCLC)chemotherapy;thus,to explore the underlyingmechanismof drug resistance ofNSCLC medications is urgently needed for improving the therapeutic efficacy of current anti-NSCLC chemotherapies.The aim of the present study is to explore the roles of exosomes in the chemosensitivity of A549 cells and the related mechanism.A549 cells and cisplatin resistant cell line A549/DDP derived exosomes were isolated,and the expressions of CXCR4 were compared.Then,after cisplatin treatment,A549 cells were treated with exosomes,and the proliferation,apoptosis,migration,and invasion of the cells were examined.Finally,the tumorigenic effect of A549/DDP derived exosomes were also evaluated by cisplatin treated xenograft tumor mice models in vivo.We found that A549/DDP derived exosomes increased the proliferation,migration,and invasion,and inhibited the apoptosis and cisplatin sensitivity of A549 cells.CXCR4 was also significantly increased in cells treated with A549/DDP derived exosomes.Furthermore,A549/DDP derived exosomes may also decrease the chemosensitivity of NSCLC cells to cisplatin in vivo.Our data suggested that A549/DDP derived exosomes can affect the chemosensitivity of A549 cells to cisplatin,possibly by transporting CXCR4 to A549 cells.Our data may provide novel evidence for the investigation of drug resistance of NSCLC.

关键词： Exosome Drug resistance CXCR4 NSCLC cells

Detecting While Accessing:A Semi-Supervised Learning-Based Approach for Malicious Traffic Detection in Internet of Things

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China Communications 2023年第4期20卷 302-314页

作者： Yantian Luo Hancun Sun Xu Chen ning ge Wei Feng Jianhua Lu Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Beijing 100084China Unit 91977 of PLA Beijing 100036China

In the upcoming large-scale Internet of Things(Io T),it is increasingly challenging to defend against malicious traffic,due to the heterogeneity of Io T devices and the diversity of Io T communication protocols.In this paper,we propose a semi-supervised learning-based approach to detect malicious traffic at the access side.It overcomes the resource-bottleneck problem of traditional malicious traffic defenders which are deployed at the victim side,and also is free of labeled traffic data in model training.Specifically,we design a coarse-grained behavior model of Io T devices by self-supervised learning with unlabeled traffic data.Then,we fine-tune this model to improve its accuracy in malicious traffic detection by adopting a transfer learning method using a small amount of labeled data.Experimental results show that our method can achieve the accuracy of 99.52%and the F1-score of 99.52%with only 1%of the labeled training data based on the CICDDoS2019 dataset.Moreover,our method outperforms the stateof-the-art supervised learning-based methods in terms of accuracy,precision,recall and F1-score with 1%of the training data.

关键词： malicious traffic detection semi-supervised learning Internet of Things(Io T) Transformer masked behavior model