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Room-temperature ferrimagnetism and size-modulated electronic structures in two-dimensional cluster-based metal-organic frameworks

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Science china Chemistry 2024年第4期67卷 1334-1340页

作者： Jing cheng Xingxing Li Jinlong Yang Key Laboratory of Precision and Intelligent Chemistry University of Science and Technology of ChinaHefei 230026China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Cluster-assembled materials have attracted particular attention for their complex hierarchical structures and unique ***,the majority of cluster-based assemblies developed so far are either non-magnetic or only exhibit magnetic ordering with a relatively low Curie temperature,limiting their applications in ***,two-dimensional(2D)cluster-assembled materials with room-temperature magnetism remain highly *** this purpose,based on first principles calculations,we design a series of thermodynamically stable 2D cluster-based metal-organic frameworks(MOFs)Fe_(n)-(pyz)(n=1-6)by utilizing Fenmetal clusters as nodes and nitrogen-containing pyrazine ligands as organic *** 2D cluster-based MOFs exhibit robust ferrimagnetic ordering due to the strong d-p direct exchange interaction between d-electron spin of Fe_(n)(n=1-6)clusters and charge transfer-induced p-electron spin of pyrazine *** particular,the ferrimagnetic Curie temperatures are well above room temperature(up to 836 K).Additionally,altering the size of Fe_(n)clusters in Fe_(n)-(pyz)(n=1-6)MOFs results in diverse functional spintronic properties,including bipolar magnetic semiconductors,half semiconductors and Dirac half ***,these 2D assembled MOFs possess sizable magnetic anisotropy energies,up to 9.16 me V per formula.

关键词： metal-organic framework two-dimensional material half metal bipolar magnetic semiconductor magnet

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“Capture-activation-recapture” mechanism-guided design of double-atom catalysts for electrocatalytic nitrogen reduction

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Journal of Energy Chemistry 2024年第9期96卷 437-447页

作者： cheng He Shiqi Yan Wenxue Zhang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina School of Materials Science and Engineering Chang’an UniversityXi’an 710064ShaanxiChina

Compared with the traditional industrial nitrogen fixation, electrocatalytic methods, especially those utilizing double-atom catalysts containing nonmetals, can give good consideration to the economy and environmental protection. However, the existing “acceptance-donation” mechanism is only applicable to bimetallic catalysts and nonmetallic double-atom catalysts containing boron atoms. Herein, a novel “capture-activation-recapture” mechanism for metal-nonmetal double-atom catalyst is proposed to solve the problem by adjusting the coordination environments of nonmetallic atoms and utilizing the activation effect of metal atoms on nitrogen. Based on this mechanism, the nitrogen reduction reaction (NRR) activity of 48 structures is calculated by density functional theory calculation, and four candidates are selected as outstanding electrocatalytic nitrogen reduction catalysts: Si-Fe@NG (U_(L) = –0.14 V), Si-Co@NG (U_(L)= –0.15 V), Si-Mo@BP1 (U_(L) = 0 V), and Si-Re@BP1 (U_(L) = –0.02 V). The analyses of electronic properties further confirm “capture-activation-recapture” mechanism and suggest that the difference in valence electron distribution between metal and Si atoms triggers the activation of N≡N bonds. In addition, a machine learning approach is utilized to generate an expression and an intrinsic descriptor that considers the coordination environment to predict the limiting potential. This study offers profound insight into the synergistic mechanism of TM and Si for NRR and guidance in the design of novel double-atom nitrogen fixation catalysts.

关键词： "Capture-activation-recapture"mechanism Double-atom catalyst Nitrogen reduction reaction Density functional theory

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Model-driven path planning for robotic plasma cutting of branch pipe with single Y-groove based on pipe-rotating scheme

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Advances in Manufacturing 2024年第1期12卷 94-107页

作者： Yan Liu Qiu Tang Xin-cheng Tian School of Control Science and Engineering Shandong UniversityJinan250061People’s Republic of China Engineering Research Center of Intelligent Unmanned System Ministry of EducationJinan250061People’s Republic of China School of Mechanical and Electronic Engineering Shandong Jianzhu UniversityJinan250101People’s Republic of China

The automatic cutting of intersecting pipes is a challenging task in *** improved automation and accuracy,this paper proposes a model-driven path planning approach for the robotic plasma cutting of a branch pipe with a single ***,it summarizes the intersection forms and introduces a dual-pipe intersection *** on this model,the moving three-plane structure(a description unit of the geometric characteristics of the intersecting curve)is constructed,and a geometric model of the branch pipe with a single Y-groove is ***,a novel mathematical model for plasma radius and taper compensation is ***,the compensation model and groove model are integrated by establishing movable ***,to prevent collisions between the plasma torch and workpiece,the torch height is planned and a branch pipe-rotating scheme is *** the established models and moving frames,the planned path description of cutting robot is provided in this novel *** accuracy of the proposed method is verified by simulations and robotic cutting experiments.

关键词： Automatic groove cutting of intersecting pipes Model-driven robot path planning Plasma beam radius and taper compensation

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Open-Shell Oligomers and Polymers: Theory, Characterization Methods, Molecular Design, and Applications

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chinese Journal of Polymer Science 2024年第4期42卷 417-436页

作者： Xue-Qing Wang cheng Song Ting Lei Key Laboratory of Polymer Chemistry and Physics(Ministry of Education) School of Materials Science and EngineeringPeking UniversityBeijing100871China

Open-shell oligomers and polymers have exhibited intriguing electronic and magnetic properties, making them highly desirable for a wide range of applications, including ambipolar organic field-effect transistors (OFETs), photodetectors, organic thermoelectrics, and spintronics. Although open-shell ground states have been observed in certain small molecules and doped organic semiconductors, the exploration of open-shell ground-state conjugated polymers is still limited, and the strategies for designing these polymers remain obscure. This review aims to briefly introduce the theory and characterization methods of open-shell conjugated polymers, along with an overview of recent progress and applications. The objective is to stimulate further advancements and investigations in this promising area by shedding light on the potential of open-shell conjugated polymers and the challenges that lie ahead.

关键词： Conjugated polymers Open-shell molecules High-spin ground state Donor-acceptor(D-A)polymers Optoelectronic and magnetic properties

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Designing novel adaptive dynamic event-triggered protocols for uncertain multi-agent systems

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Science china(Information Sciences) 2024年第1期67卷 310-311页

作者： Bin cheng Bin HE College of Electronics and Information Engineering Tongji University Frontiers Science Center for Intelligent Autonomous Systems

Multi-agent systems (MASs) have garnered widespread attention and have been investigated by numerous researchers in recent years, primarily due to their broad applications in industry, transportation, agriculture, and astronomy. While studying the cooperative control of MASs, numerous researchers place emphasis on reducing the frequency of communication among neighboring agents.

关键词： Directed graphs

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Evaluating quality of motion for unsupervised video object segmentation

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Optoelectronics Letters 2024年第6期20卷 379-384页

作者： cheng Guanjun SONG Huihui Jiangsu Key Laboratory of Big Data Analysis Technology Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment TechnologyNanjing University of Information Science&TechnologyNanjing 210044China12

Current mainstream unsupervised video object segmentation(UVOS) approaches typically incorporate optical flow as motion information to locate the primary objects in coherent video frames. However, they fuse appearance and motion information without evaluating the quality of the optical flow. When poor-quality optical flow is used for the interaction with the appearance information, it introduces significant noise and leads to a decline in overall performance. To alleviate this issue, we first employ a quality evaluation module(QEM) to evaluate the optical flow. Then, we select high-quality optical flow as motion cues to fuse with the appearance information, which can prevent poor-quality optical flow from diverting the network's attention. Moreover, we design an appearance-guided fusion module(AGFM) to better integrate appearance and motion information. Extensive experiments on several widely utilized datasets, including DAVIS-16, FBMS-59, and You Tube-Objects, demonstrate that the proposed method outperforms existing methods.

关键词： Evaluating quality of motion for unsupervised video object segmentation

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Towards a blood ecosystem approach to dissect systemic diseases

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Science china(Life Sciences) 2024年第7期67卷 1528-1531页

作者： Hong Wang Tao cheng State Key Laboratory of Experimental Hematology Haihe Laboratory of Cell EcosystemNational Clinical Research Center for Blood DiseasesInstitute of Hematology&Blood Diseases HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeTianjin 300020China Tianjin Institutes of Health Science Tianjin 301600China

Systemic diseases,in contrast to localized ailments,exert widespread effects and can impact the entire *** of systemic diseases encompass autoimmune disorders,infectious diseases,metabolic disorders,and chronic conditions like *** diseases often entail intricate interactions among diverse organs,tissues,and physiological systems,influenced by a myriad of factors.

关键词： diseases organs autoimmune

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Wideband Millimeter Wave Antenna with Cavity Backed Slotted Patch and Magneto-Electric Dipole

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chinese Journal of Electronics 2024年第5期33卷 1234-1244页

作者： Yang cheng Yuandan DONG School of Electronic Science and Engineering University of Electronic Science and Technology of China

This paper proposes a wideband cavity-backed slotted patch antenna, loaded with a magneto-electric（ME）-dipole and fed by a microstrip line, for millimeter wave（mm-Wave） applications. The coupled-feed cavitybacked slotted patch antenna is loaded with the ME-dipole. The slotted patch antenna serves as both a radiator and a ground for the ME-dipole. The combination of the ME-dipole antenna and the slotted patch antenna realizes a –10 dB impedance bandwidth covering over 22.86–44.35 GHz（63.9%）. The pattern of the antenna element remains stable throughout this bandwidth. The proposed broadband antenna unit not only realizes single linearly polarized（LP）radiation but also can be designed for dual-LP radiation. The dual-polarized radiation can be achieved by changing the slot of the patch antenna to a crossed slot and altering the ME-dipole antenna to a dual-polarization form. A 2 × 2 dual-polarized array has been designed, fabricated, and tested. A novel dual-polarized feeding network is *** achieve higher isolation, broadband in-phase feed and differential feed are adopted, respectively. A low-loss single to the differential structure is proposed for differential feeding. The simulated isolation of the array is higher than 40 d *** results show that the dual-polarized 2 × 2 array has an overlapping bandwidth of 52.3%(|S11| < –10 dB and |S21| < –30 dB) with a peak gain of 14 dBi. The proposed antenna, featuring a wide overall bandwidth, low cost,and good radiation performance, is well suited for mm-Wave applications.

关键词： Slot antennas Costs Dipole antennas Patch antennas Magnetoelectric effects Broadband communication Broadband antennas Array antenna Dual-polarized antenna Feeding network Magneto-electric dipole Millimeter-wave (mm-Wave) Patch BROAD-BAND POLARIZED ANTENNA ARRAY PLANAR BALUN

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《民法典》自甘风险规则在学校文体活动中的适用困境及其纾解——基于司法裁判文书的实证分析

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中国体育科技 2024年第1期60卷 90-96,F0003页

作者：池骋罗建厦门大学福建厦门361005 四川省犍为县人民法院四川犍为614400

《中华人民共和国民法典》(以下简称《民法典》)首次明确了自甘风险规则的适用,在促进社会文明、鼓励文体产业发展并合理分配由此产生的责任方面实现了中国式科学立法。但在学校开展的文体活动可能产生的伤害事故中,自甘风险规则的4个... 详细信息

《中华人民共和国民法典》(以下简称《民法典》)首次明确了自甘风险规则的适用,在促进社会文明、鼓励文体产业发展并合理分配由此产生的责任方面实现了中国式科学立法。但在学校开展的文体活动可能产生的伤害事故中,自甘风险规则的4个适用要件(主体要件、主观要件、客观要件、消极要件)都存在一定的适用困境与问题。因此,需要对发生在学校视域内的自甘风险相关司法实践进行类型化讨论,并从解释论层面给出尽可能符合立法原意和各方利益需求的纾解答案。此外,学校履行安全保障义务应符合《民法典》的要求,做好证据固定工作,并完善以保险为核心的多元化损害赔偿分担机制。

关键词：自甘风险民法典组织者责任安全保障义务犯规犯规动作意图

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基于离散采样模型的三自由度双旋翼直升机的控制器设计

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系统科学与数学 2024年第9期44卷 2588-2602页

作者：迟楠曾诚贵州理工学院理学院贵阳550003

三自由度纵列式双旋翼直升机模型是动力学系统研究中的一类重要实验对象,也是研究直升机飞行控制技术的平台.文章首先针对非线性三自由度纵列式直升机模型的系统描述,在其标准形描述和一般采样保持条件下,导出了比经典的Euler模型更精... 详细信息

三自由度纵列式双旋翼直升机模型是动力学系统研究中的一类重要实验对象,也是研究直升机飞行控制技术的平台.文章首先针对非线性三自由度纵列式直升机模型的系统描述,在其标准形描述和一般采样保持条件下,导出了比经典的Euler模型更精确的非线性近似离散时间模型,并进一步计算可得出,它们的近似离散模型的局部截断误差和全局截断误差分别为T5和T2,其中T为采样周期.其次,文章对非线性三自由度双旋翼直升机进行了系统辨识及其相应的简单讨论.最后,在导出的近似直升机离散采样模型的基础上,对非线性三自由度双旋翼直升机,文章给出了连续时间输入控制设计和李雅普诺夫再设计两种方法来开展对比研究,并通过实例表明李雅普诺夫再设计可增强系统的控制性能.

关键词：三自由度双旋翼直升机离散采样分析系统辨识采样控制器设计

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