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Single crystal growth and characterization of 166-type magnetic kagome metals

Chinese Physics B 2024年第9期33卷 145-150页

作者： Huangyu Wu Jinjin Liu Yongkai Li Peng Zhu Liu Yang Fuhong Chen Deng Hu Zhiwei Wang Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of TechnologyBeijing 100081China Beijing Key laboratory of Nanophotonics and Ultrafine Optoelectronic Systems Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Zhuhai 519000China Material Science Center Yangtze Delta Region Academy of Beijing Institute of TechnologyJiaxing 314011China

Kagome magnets were predicted to be a good platform to investigate correlated topology band structure,Chern quantum phase,and geometrical frustration due to their unique lattice *** we reported single crystal growth of 166-type kagome magnetic materials,including HfMn_(6)Sn_(6),ZrMn_(6)Sn_(6),GdMn_(6)Sn_(6)and GdV_(6)Sn_(6),by using the flux method with Sn as the *** them,HfMn_(6)Sn_(6)and ZrMn_(6)Sn_(6)single crystals were grown for the first time.X-ray diffraction measurements reveal that all four samples crystallize in HfFe6Ge6-type hexagonal structure with space group P6/*** samples show metallic behavior from temperature dependence of resistivity measurements,and the dominant carrier is hole,except for GdV6Sn6 which is electron *** samples have magnetic order with different transition temperatures,HfMn_(6)Sn_(6),ZrMn_(6)Sn_(6)and GdV_(6)Sn_(6)are antiferromagnetic with TN of 541 K,466 K and 4 K respectively,while GdMn_(6)Sn_(6)is ferrimagnetic with the critical temperature of about 470 *** study will enrich the research platform of magnetic kagome materials and help explore the novel quantum phenomena in these interesting *** dataset of specific crystal structure parameters for HfMn_(6)Sn_(6)are available in Science Data Bank,with the link.

关键词： kagome metal single crystal growth crystal structure physical property

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D-band center coordination modulated enzyme-like activity in Fe-Cu dual-metal single-atom nanozymes

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Nano Research 2024年第7期17卷 5872-5883页

作者： Ling Liu Shaofang Zhang Guo Li Yadong Zhe Jiamin Liu Xinxu Zhang Jiahao Wei Xin Sun Yonghui Li Xiao-Dong Zhang Tianjin Key laboratory of Brain Science and Neural Engineering Academy of Medical Engineering and Translational MedicineTianjin UniversityTianjin 300072China Department of Physics and Tianjin Key laboratory of Low Dimensional Materials Physics and Preparing Technology School of SciencesTianjin UniversityTianjin 300350China

After explorations in a diversity of single-atom nanozymes(SAzymes),developing dual-centered SAzymes becomes a promising approach for superior catalytic *** confusing mechanisms including atomic coordination,spatial configuration,and metal–metal atom interaction hinder the development and design of ***,a dual-centered Fe-Cu-N_(x)SAzyme exhibits excellent peroxidase(POD)-and catalase(CAT)-like activities with d-band center(ε_(d))coordination of Fe and Cu in multiple reaction stages,which plays a critical role in the adsorption of H_(2)O_(2)molecule and H_(2)O and O_(2)***,the dband center coordination,which can be represented byε_(d)(Fe)–ε_(d)(Cu)shifts,leads to the competition between one-side and bilateral adsorption,which determines the favorable reaction path with lower energy *** on experimental statistics,simulated formation energies,and reaction barriers,3 configurations,Fe-Cu-N6-I,Fe-Cu-N_(8)-II,and Fe-Cu-N_(8)-III,are modeled and ***,configuration-dependent catalytic selectivity and the competition between one-side and bilateral adsorption can be unveiled by d-band center coordination paradigm *** simulations suggest that the unsymmetrical charge distribution over the three Fe-Cu configurations could tune the adsorption strength compared with the counterparts FeN_(4)and CuN_(4).The present work provides a potential route for optimizing enzyme-like catalysis by designing the dual-or even triple-metal SAzymes,which demonstrates the large space to modulate the metal atomic configuration and interaction.

关键词： single-atom catalysis Fe-Cu dual-metal d-band center coordination enzyme mimicking competitive adsorption mechanisms

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Cyclostratigraphy and paleoclimate analysis of the Lingshui Formation in Changchang Sag,Qiongdongnan Basin,china

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Energy Geoscience 2024年第1期5卷 108-120页

作者： Haizhang Yang Wu Tang Enze Xu Shangfeng Zhang Yaning Wang Min Xu china national Offshore Oil Research Institute Limited Beijing100028China College of Earth Sciences Yangtze River UniversityWuhanHubei430000China

The Qiongdongnan Basin,located in the sea between Hainan Island and the Xisha Islands,is a faulted Cenozoic basin on the northern continental margin of the South china *** Changchang Sag,situated in the eastern part of the central depressional zone in the deepwater area of the Qiongdongnan Basin,exhibits a near EW-striking morphology and represents an important potential target for oil/gas ***,the age of the interface of the Lingshui Formation remains controversial,which hinders a comprehensive understanding of the tectonic evolution and hydrocarbon accumulation pattern in the Changchang *** study focuses on well A,located in the depositional center of the Changchang Sag,and employs cyclostratigraphic analysis to identify cyclic signals of the Milankovitch cycles recorded in the sedimentary *** analysis of natural gamma logging data from this well reveals the presence of 405 kyr long eccentricity cycles,100 kyr short eccentricity cycles,39.3 kyr obliquity cycles,and 20.58 kyr age precession *** employing astronomical tuning,a“floating”astronomical time scale of the Lingshui Formation spanning 5.483 million years(Myr)is *** top interface of the Oligocene in the International Geological Time Scale 2020(GTS2020),with a geological age of 23.03 Ma,is used as the time anchor to establish a high-precision absolute astronomical age framework for the Lingshui *** results indicate that the bottom interface of the first member of the Lingshui Formation is dated at 23.79 Ma,the bottom interface of the second member is dated at 25.08 Ma,and the bottom interface of the third member is dated at 28.51 ***,the average sedimentation rate during this period is estimated to be 9.261 cm/***,paleoclimate and paleoenvironmental reconstructions were carried out through quantitative analysis of spore and pollen assemblages,as well as foraminifera within the Lingshui *** analyses suggest that

关键词： Milankovitch cycle Paleoclimate Qiongdongnan Basin Cyclostratigraphy Astronomical time scale

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Solid-state NMR study of the stability of MOR framework aluminum

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Chinese Journal of Structural Chemistry 2024年第4期43卷 7-14页

作者： Xinzhi Ding Chong Liu Jing Niu Nan Chen Shutao Xu Yingxu Wei Zhongmin Liu national Engineering Research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China State Key laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China University of Chinese Academy of Sciences Beijing 100049China School of Chemistry Dalian University of TechnologyDalian116024China

MOR zeolite has been effectively utilized for dimethyl ether(DME)carbonylation reaction due to its unique pore structure and *** industrial production,the transformation of ammonium type MOR zeolite(NH_(4)-MOR)into proton type MOR zeolite(H-MOR)causes inevitable ***,understanding the influencing factors and dynamic evolution mechanism of zeolite dealumination is *** this work,the stability of framework aluminum was studied by X-ray diffraction(XRD),Fourier transform infrared(FT-IR)spectroscopy,^(29)Si,^(27)Al,^(1)H magic angle spinning nuclear magnetic resonance(MAS NMR),and DME carbonylation performance *** results indicate that extra-framework cation Na^(+)and NH_(4)^(+)could better preserve the aluminum structure of the MOR zeolite framework compared to H^(+),primarily due to the different'attraction'of the framework to ***,the impact of water on the zeolite framework aluminum at high temperature was studied by manipulating the humidity of the calcination atmosphere,revealing the formation of extra-framework six-coordinated aluminum(Al(Ⅵ)-EF)and the mechanism of water influence on the zeolite framework aluminum.

关键词： H-MOR Solid-state NMR H2O Framework aluminum stability Dealumination

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Exceptional electrostrain with minimal hysteresis and superior temperature stability under low electric field in KNN-based lead-free piezoceramics

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Journal of Advanced Ceramics 2024年第3期13卷 364-372页

作者： Huan Liu Yijin Hao Ziqi Yang Tianyi Feng Bin Su Xin Zhang Mengping Xue Bo-Ping Zhang Jing-Feng Li Beijing Municipal Key laboratory of New Energy Materials and Technologies School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China State Key laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Over the past two decades,(K_(0.5)Na_(0.5))NbO_(3)(KNN)-based lead-free piezoelectric ceramics have made significant ***,attaining a high electrostrain with remarkable temperature stability and minimal hysteresis under low electric fields has remained a significant *** address this long-standing issue,we have employed a collaborative approach that combines defect engineering,phase engineering,and relaxation *** LKNNS-6BZH ceramic,when sintered at T_(sint)=1170℃,demonstrates an impressive electrostrain with a d_(33) value of 0.276%and 1379 pm·V^(-1)under 20 kV·cm^(-1),which is comparable to or even surpasses that of other lead-free and Pb(Zr,Ti)O_(3)***,the electrostrain performance of this ceramic remains stable up to a temperature of 125℃,with the lowest hysteresis observed at 9.73%under 40 kV·cm^(-1).These excellent overall performances are attributed to the presence of defect dipoles involving V′_(A)-V∙∙_(O) and B′_(Nb)-V∙∙O,the coexistence of R-O-T multiphase,and the tuning of the trade-off between long-range ordering and local *** work provides a lead-free alternative for piezoelectric actuators and a paradigm for designing piezoelectric materials with outstanding comprehensive performance under low electric fields.

关键词： lead-free piezoelectric ceramics temperature stability electrostrain potassium sodium niobate low hysteresis

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The response of Martian photoelectron boundary to the 2018 global dust storm

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Science china Earth Sciences 2024年第9期67卷 2772-2782页

作者： Yuqi WANG Jun CUI Yong WEI Zhaopeng WU Kai FAN Zhaojin RONG Fei HE Yutian CAO Jiawei GAO Key laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Planetary Environmental and Astrobiological Research laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China

Extensive research efforts have revealed that the Martian dust storms can perturb the upper atmospheric condition and as a consequence,enhance plasma density and photoelectron flux in the ***,previous observational studies of the Martian dust storm impacts have been restricted to regions below 400 km,which limits our understanding of the Martian dust storm effects in the upper ionosphere and ***,based on the suprathermal electron measurements made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution,we identify with an automatic procedure the occurrences of all photoelectron boundary(PEB)crossings at solar zenith angle below 120°(with a dust-free median altitude of about 600 km).Using the dayside PEB as a proxy of the upper ionospheric and magnetospheric condition,we analyze the variations of the PEB altitude during the 2018 global dust storm(GDS)of Mars Year 34(MY34)and compare them with the period in MY33 when there was no global dust *** conclude that the column dust optical depth(CDOD)emerges as one of the main driving factors for PEB altitude variations during the *** analysis implies that the GDS can affect the Martian upper atmosphere and ionosphere over considerable distances and extended time scales.

关键词： Martian global dust storm Martian photoelectron boundary Upper ionosphere

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Supported Atomically Dispersed Pd Catalyzed Direct Alkoxylation and Allylic Alkylation

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Chinese Journal of Chemistry 2024年第7期42卷 719-724页

作者： Ruixuan Qin Ziwen Chen Qingyuan Wu Nanfeng Zheng Pengxin Liu New Cornerstone Science laboratory State Key Laboratory for Physical Chemistry of Solid SurfacesCollaborative Innovation Center of Chemistry for Energy Materialsand National&Local Joint Engineering Research Center of Preparation Technology of NanomaterialsCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamenFujian 361005China Innovation Laboratry for Scences and Technoogies of Energy Materials of Fujan Province(IKKM) Xiamen Fujian 361102China School of Physical Science and Technology Shanghai Tech UniversityShanghai 201210China Fujian Key laboratory of Rare-earth Functional Materials Fujian Shanhai Collaborative Innovation Center of Rare-earth Functional MaterialsLongyanFujian 366300China

A new approach to allylic alkylation is realized using an atomically dispersed palladium catalyst(Pd1/TiO2-EG).Unlike conventional methods that require derivation of substrates and utilization of additives,this method allows for direct allylic alkylation from allylic alcohols,producing H2O as the sole *** catalyst's high efficiency is attributed to the local hydrogen bonding at the or-ganic-inorganic interface(Pd-EG interface),facilitating hydroxyl group activation forη3π-allyl complex *** system demonstrates successful direct C—O and C—C coupling reactions with high selectivity,requiring no *** study highlights the potential of supported atomically dispersed catalysts for greener and more efficient catalysis,meanwhile,offers unique insights into the distinct behavior of atomically dispersed catalysts in comparison to homogeneous or nanoparticle-based catalysts.

关键词： Atomically dispersed catalyst Alkylation C—C coupling Organic-inorganic Interface Hydrogen bond Tsuji-Trost reaction Green catalysis

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Interaction mechanism between BaZrO_(3)/Y_(2)O_(3) refractory and Ti_(2)Ni alloy melts

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Journal of Iron and Steel Research International 2024年第6期31卷 1376-1388页

作者： Xiao Hou Guang-yao Chen Jian Liu Ming-rui Lv Fei-hai Yu Qi-sheng Feng Rong-bin Li Xiong-gang Lu Chong-he Li State Key laboratory of Advanced Special Steel and Shanghai Key laboratory of Advanced Ferromeallurgy and School of Materials Science and Engineering Shanghai UniversityShanghai 200072China Shanghai Special Casting Engineering Technology Research Center Shanghai 201605China Zhejiang Institute of Advanced Materials Shanghai UniversityJiashan 314100ZhejiangChina School of Materials Science and Engineering Shanghai DianJi UniversityShanghai 201306China

The titanium alloys with highly chemical activity require stable crucible refractories that can withstand the erosion of alloy *** phase composition and microstructure are crucial factors that affect the stability of the refractory *** effect of Y_(2)O_(3) on the composition and microstructure of BaZrO_(3) crucible was systematically investigated,and the improved mechanism of the stability of BaZrO_(3)/Y_(2)O_(3) crucible was clarified in comparison with the BaZrO_(3) *** results showed that the erosion layer thickness of the BaZrO_(3)/Y_(2)O_(3) crucible was only 63μm,which was far less than that in the BaZrO_(3) crucible(485μm),and the erosion layer in the BaZrO_(3)/Y_(2)O_(3) crucible also exhibited a higher density than that in the BaZrO_(3) *** the sintering,Y_(2)O_(3) could improve the densification of the BaZrO_(3) crucible due to the solid solution effect between Y_(2)O_(3) and ZrO_(2),which also caused the evaporation of BaO,resulting in the generation of a Y_(2)O_(3)(ZrO_(2))film on the surface of the ***,the Y_(2)O_(3)(ZrO_(2))had higher thermodynamic stability than Y_(2)O_(3),confirming that the BaZrO_(3)/Y_(2)O_(3) crucible with high density exhibited a superior erosion resistance to titanium *** dual-phase structure provides a strategy to design a long-life and stable refractory for melting titanium alloys.

关键词： Barium zirconate Yttrium oxide Dual-phase refractory Titanium alloy Interaction

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Aerodynamic/control integrated optimization method for unpowered high-speed vehicle configuration design

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Chinese Journal of Aeronautics 2024年第7期37卷 153-167页

作者： Xin PAN Linlin WANG Li LI Lulu JIANG Gang CHEN State Key laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China Shannxi Key laboratory for Environment and Control of Flight Vehicle School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China Beijing Institute of Space Long March Vehicle Beijing 100076China AVIC Xi’an Aeronautics Computing Technique Research Institute Xi’an 710068China

The unpowered high-speed vehicle experiences a significant coupling between the disciplines of aerodynamics and control due to its characteristics of high flight speed and extensive maneuverability within large *** conventional aircraft conceptual design process follows a sequential design approach,and there is an artificial separation between the disciplines of aerodynamics and control,neglecting the coupling effects arising from their *** a result,this design process often requires extensive iterations over long periods when applied to high-speed vehicles,and may not be able to effectively achieve the desired design *** enhance the overall performance and design efficiency of high-speed vehicles,this study integrates the concept of Active Control Technology(ACT)from modern aircraft into the philosophy of aerodynamic/control integrated *** integrated optimization strategies,with differences in coupling granularity,have been ***,these strategies are put into action on a biconical vehicle that operates at Mach *** results reveal that the comprehensive performance of the synthesis optimal model derived from the aerodynamic/control integrated optimization strategy is improved by 31.76%and 28.29%respectively compared to the base model under high-speed conditions,demonstrating the feasibility and effectiveness of the method and optimization strategies ***,in comparison to the single-stage strategy,the multi-stage strategy takes into deeper consideration the impact of control *** a result,the control performance of the synthesis opti-mal model derived from the multi-stage strategy improves by 13.99%,whereas the single-stage strategy only achieves a 5.79%*** method enables a fruitful interaction between aerodynamic configuration design and control system design,leading to enhanced overall performance and design ***,it improves the controllability of high-sp

关键词： Aerodynamic/Control Integrated Optimization MDO High-speed vehicle Shape Optimization Controllability

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A survey on model-based reinforcement learning

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Science china(Information Sciences) 2024年第2期67卷 59-84页

作者： Fan-Ming LUO Tian XU Hang LAI Xiong-Hui CHEN Weinan ZHANG Yang YU national Key laboratory for Novel Software Technology Nanjing University Polixir. ai Department of Computer Science and Engineering Shanghai Jiao Tong University

Reinforcement learning(RL) interacts with the environment to solve sequential decision-making problems via a trial-and-error approach. Errors are always undesirable in real-world applications, even though RL excels at playing complex video games that permit several trial-and-error attempts. To improve sample efficiency and thus reduce errors, model-based reinforcement learning(MBRL) is believed to be a promising direction, as it constructs environment models in which trial-and-errors can occur without incurring actual costs. In this survey, we investigate MBRL with a particular focus on the recent advancements in deep RL. There is a generalization error between the learned model of a non-tabular environment and the actual environment. Consequently, it is crucial to analyze the disparity between policy training in the environment model and that in the actual environment, guiding algorithm design for improved model learning, model utilization, and policy training. In addition, we discuss the recent developments of model-based techniques in other forms of RL, such as offline RL, goal-conditioned RL, multi-agent RL, and meta-RL. Furthermore,we discuss the applicability and benefits of MBRL for real-world tasks. Finally, this survey concludes with a discussion of the promising future development prospects for MBRL. We believe that MBRL has great unrealized potential and benefits in real-world applications, and we hope this survey will encourage additional research on MBRL.

关键词： reinforcement learning model-based reinforcement learning planning model learning model learning with reduced error model usage

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