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Encoding innumerable charge density waves of FeGe into polymorphs of LiFe6Ge6

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science China(Physics,Mechanics & Astronomy) 2024年第9期Mechanics & Astronomy) .卷 130-136页

作者： Yilin Wang School of Emerging Technology University of Science and Technology of China Hefei National laboratory University of Science and Technology of China New Cornerstone science laboratory University of Science and Technology of China

Kagome metals exhibit rich quantum states by the intertwining of lattice,charge,orbital and spin degrees of ***,a novel charge density wave （CDW） ground state was discovered in kagome magnet FeGe and was revealed to be driven by lowering magnetic energy via large ***,based on DFTcalculations,we show that such mechanism will yield infinitely many metastable CDWs in FeGe due to different ways to arrange the Ge1-dimerization in enlarged ***,utilizing these metastable CDWs,innumerable polymorphs of kagome magnet LiFe6Ge6can be stabilized by filling Li atoms in the voids right above/below the dimerized Ge1-sites in the CDW *** polymorphs are very stable due to the presence of magnetic-energy-saving mechanism,in sharp contrast to the non-magnetic “166” kagome *** this way,a one-to-one mapping of the metastable CDWs of FeGe to stable polymorphs of LiFe6Ge6is *** one hand,the fingerprints of these metastable CDWs,i.e.,the induced in-plane atomic distortions and band gaps,are encoded into the corresponding stable polymorphs of LiFe6Ge6,such that further study of their properties becomes *** the other hand,such innumerable polymorphs of LiFe6Ge6offer great degrees of freedom to explore the rich physics of magnetic kagome *** thus reveal a novel connection between the unusually abundant CDWs and structural polymorphism in magnetic kagome materials,and establish a new route to obtain structural polymorphism on top of CDW states.

关键词： kagome magnet unconventional charge density wave structural polymorphism magnetic energy saving

Catalysis by subsurface metal atoms in Al(001) through electron transfer

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National science Review 2024年第4期11卷 12-13页

作者： Bo Sun Ding Ma Beijing National laboratory for Molecular science New Cornerstone Science Laboratory College of Chemistry and Molecular Engineering Peking University

Heterogeneous catalysis plays a crucial role in the chemical industry, which has evolved from the investigation of chemisorption to an electronic structure[1]. Diverse strategies, such as alloying,doping, and confining, have been applied to enhance the catalytic properties of active sites through electronic modulation. The electron transfer between active sites and substrates profoundly influences catalytic activity [2].

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Robust enhancement of valley polarization and quantum yield in composition grading lateral heterostructure of MoS2-WS2 monolayer

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Progress in Natural science:Materials International 2024年第1期34卷 187-193页

作者： Mengke Kang Cheng Zhang Congpu Mu Kun Zhai Tianyu Xue Bochong Wang Fusheng Wen Yingchun Cheng Jianyong Xiang Jun-Feng Dai Anmin Nie Zhongyuan Liu Center for High Pressure science State Key Laboratory of Metastable Materials Science and Technology Yanshan University Shenzhen Institute for Quantum science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen Key laboratory of Quantum science and Engineering

Valley degeneracy can be broken owing to the strong spin-orbit coupling in two-dimensional transition metal dichalcogenides（2D-TMDCs）. Valley-dependent interaction of carriers in TMDCs with different circular polarizations of light offers valley degree-of-freedom besides charge and spin to carry information. Thus, bandgap engineering of 2D-TMDCs plays a critical role in developing practical valleytronic devices. Hereby, we demonstrate a great enhancement in quantum yield as well as polarization of monolayer MoS2achieved by gradually alloying W atoms in MoS2. By appropriately setting a time offset between the evaporation of MoO3and WO3precursors during chemical vapor deposition, a compositionally graded heterostructure of MoS2-WS2monolayer can be readily grown at large scale. Raman and transmission electron microscopy measurements demonstrate that the interface possesses a steep gradient in composition, spanning from MoS2to WS2over a length ～2 μ*** to pure monolayer MoS2, the photoluminescence intensity at the compositionally graded interface of Mo1-xWxS2was observed to increase by a factor of 16 owing to the effective separation of photogenerated carriers by the built-in electric field. Particularly, a remarkably high polarization of 70% at 16 K is demonstrated for the compositionally graded interface of Mo1-xWxS2, which is ～1.4 times larger than that in MoS2and is attributed to the combined effect of the alloyed structure and graded bandgap. Such an engineering scheme with a graded bandgap offers new approach for the development of high-efficiency valleytronics devices.

关键词： Transition metal dichalcognide monolayer Compositionally graded in-plane heterostructure Chemical vapor deposition Valley polarization Quantum yield

A vibration isolator with a controllable quasi-zero stiffness region based on nonlinear force design

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1279-1294页

作者： Xinyu LIAN Bing LIU Huaxia DENG Xinglong GONG CAS Key laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China State Key laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences State Key laboratory of Fire science University of Science and Technology of China

To achieve stability optimization in low-frequency vibration control for precision instruments, this paper presents a quasi-zero stiffness(QZS) vibration isolator with adjustable nonlinear stiffness. Additionally, the stress-magnetism coupling model is established through meticulous theoretical derivation. The controllable QZS interval is constructed via parameter design and magnetic control, effectively segregating the high static stiffness bearing section from the QZS vibration isolation section. Furthermore, a displacement control scheme utilizing a magnetic force is proposed to regulate entry into the QZS working range for the vibration isolation platform. Experimental results demonstrate that the operation within this QZS region reduces the peak-to-peak acceleration signal by approximately 66.7% compared with the operation outside this region, thereby significantly improving the low frequency performance of the QZS vibration isolator.

关键词： 70K20 low frequency nonlinear O328 quasi-zero stiffness (QZS) vibration isolator

Thermal runaway evolution of a 280 Ah lithium-ion battery with LiFePO_(4) as the cathode for different heat transfer modes constructed by mechanical abuse

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Journal of Energy Chemistry 2024年第6期93卷 32-45,I0002页

作者： Zhixiang Cheng Chengdong Wang Wenxin Mei Peng Qin Junyuan Li Qingsong Wang State Key laboratory of Fire science University of Science and Technology of ChinaHefei 230026AnhuiChina

Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway ***,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be *** work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration *** penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also *** results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway *** difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the *** controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.

关键词： Lithium-ion battery safety Micro short-circuit cell Heat transfer modes Internal short circuit Nail-penetration test

维普期刊数据库

Granger causal representation learning for groups of time series

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science China(Information sciences) 2024年第5期67卷 56-68页

作者： Ruichu CAI Yunjin WU Xiaokai HUANG Wei CHEN Tom Z.J.FU Zhifeng HAO School of Computer science Guangdong University of Technology Peng Cheng laboratory College of science Shantou University

Discovering causality from multivariate time series is an important but challenging *** existing methods focus on estimating the Granger causal structures among multivariate time series,while ignoring the prior knowledge of these time series, e.g., the group of the time series. Focusing on discovering the Granger causal structures among groups of time series, we propose a Granger causal representation learning method to solve this problem. First, we use the multiset canonical correlation analysis method to learn the Granger causal representation of each group of time series. Then, we model the Granger causal relationships among the learned Granger causal representations using a recurrent neural network with temporal information. Finally, we formulate the above two stages into one unified optimization problem, which is efficiently solved using the augmented Lagrangian method. We conduct extensive experiments on synthetic and real-world datasets to validate the correctness and effectiveness of the proposed method.

关键词： Granger causal discovery Granger causal representation learning time series data recurrent neural network multiset canonical correlation analysis

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Participant Heterogeneity of Systemic Scleroderma Interventional Trials Worldwide

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International Journal of Dermatology and Venereology 2024年第2期7卷 99-107页

作者： Li-Qing Shi Shi-Hang Zhou Ping-Lang Ruan Bo Zhang Yue Xin Cheng Zhao Xu Yao Jing-Ru Tian Qian-Jin Lu Hospital for skin Diseases(Institute of Dermatology) Chinese Academy of Medical Sciences and Peking Union Medical CollegeNanjingJiangsu 210042China Key laboratory of Basic and Translational Research on Immune-Mediated skin Diseases Chinese Academy of Medical SciencesNanjingJiangsu 210042China Jiangsu Key laboratory of Molecular Biology for skin Diseases and STIs NanjingJiangsu 210042China Department of Dermatology Hunan Key Laboratory of Medical Epigenomicsthe Second Xiangya HospitalCentral South UniversityChangshaHunan 410011China

Objective:Heterogeneity of participants in clinical trials distorts intervention ***,factors associated with participant heterogeneity in randomized clinical trials(RCTs)focusing on systemic sclerosis(SSc)are not *** conducted this systematic review to establish normative standards for future research and help develop management ***:Three databases and 4 registries were searched to identify characteristics of SSc RCTs across different *** of bias was assessed by the Cochrane Collaboration’s tool and logistic regression was performed to calculate crude and adjusted odds ***:In total,261 trials met our inclusion *** quality of SSc RCTs worldwide was relatively poor,with no trend of improvement in recent years,and only 12.2%were ranked as having a low risk of *** with a low risk of bias as well as single-center,single-country,or open-label trials tended to have better participant adherence than trials with a high risk of bias and multiple-center,multiple-country,or double-blind ***,trial registration and primary outcome definition contributed to high *** income was also relevant;participant adherence in high-income countries,but not in upper-and lower-middle-income countries,was significantly altered by different ***:Overall,the risk of bias,national income,and trial design may lead to participant heterogeneity of SSc RCTs and ultimately confound the general clinical utility of the *** with a rigorous design and transparent conduction protocol are crucial for obtaining unbiased data that can serve as a reference and for maintaining the fundamental repeatability of SSc RCTs.

关键词： systemic sclerosis randomized clinical trials heterogeneity participant adherence national income risk of bias

维普期刊数据库

Quantum key distribution over a mimicked dynamic-scattering channel

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science China(Information sciences) 2024年第4期67卷 323-330页

作者： Qi-Hang LU Fang-Xiang WANG Wei CHEN Hai-Yang FU Yin-Jie LU Shuang WANG De-Yong HE Zhen-Qiang YIN Guang-Can GUO Zheng-Fu HAN CAS Key laboratory of Quantum Information University of Science and Technology of China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei National laboratory University of Science and Technology of China

Free-space quantum key distribution(QKD) plays an important role in the global quantum network. However, free space channels suffer from the atmospheric turbulence and scattering effects of haze,fog, and dust, which significantly weaken the performance of QKD or even block the secure quantum ***, we prove the performance of QKD over a dynamic scattering channel can be enhanced significantly using a fast wavefront shaping technique. The system achieves on average 10-dB enhancement of quantum transmission efficiency and establishes a secure quantum link for QKD. Our work demonstrates the feasibility of QKD through free-space dynamic scattering channels and enhances the deployment capability of complex-channel QKD system.

关键词： quantum key distribution free space channel channel turbulence channel scattering wavefront shaping

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Topological magnetoelectric response in ferromagnetic axion insulators

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National science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen Institute for Quantum science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key laboratory for Computational science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological ***,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface ***,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the *** the designed triangular prism geometry,all the surface states are magnetically *** a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in ***,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric *** work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials