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The breaking of spin symmetry in the single-particle resonances in deformed nuclei

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Nuclear Science and Techniques 2024年第3期35卷 237-245页

作者： Zhen-yu zheng Shou-Wan Chen Quan Liu School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China

The exploration of spin symmetry (SS) in nuclear physics has been instrumental in identifying atomic nucleus *** this study,we solve the Dirac equation from the relativistic mean field (RMF) in complex momentum *** investigated SS and its breaking in single-particle resonant states within deformed nuclei,with a focus on the illustrative *** was the initial discovery of a resonant spin doublet in a deformed nucleus,with the expectation of the SS approaching the continuum *** increasing single-particle energy,the splitting of the resonant spin doublets widened *** escalating splitting implies diminishing adherence to the SS,indicating a departure from the expected behavior as the energy levels *** also analyzed the width of the resonant states,showing that lower orbital angular momentum resonances possess shorter decay times and that SS is preserved within broad resonant doublets,as opposed to narrow resonant *** the radial density of the upper components for the bound-state and resonant-state doublets,it becomes evident that while SS is well-preserved in the bound states,it deteriorates in the resonant *** impact of nuclear deformation (β_(2)) on SS was examined,demonstrating that an increase in β_(2) resulted in higher energy and width splitting in the resonant spin doublets,which is attributed to increased component ***,the sensitivity of spin doublets to various potential parameters such as surface diffuseness (a),radius (R),and depth (Σ0) is discussed,emphasizing the role of these parameters in *** study provides valuable insights into the behavior of spin doublets in deformed nuclei and their interplay with the nuclear structure,thereby advancing our understanding of SS in the resonance state.

关键词： Spin symmetry Resonant states Deformed nuclei Complex-momentum representation

Spherical Confinement Generates Entropic Force to Accelerate Polymer Chain Detachment

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Chinese Journal of Polymer Science 2024年第3期42卷 407-416,I0010页

作者： yu-Shan zheng Jian-Ping Zhou Yan Xu Kai Li Mechanical Engineering Xinjiang UniversityUrumqi 830002China

To understand the dynamic process of polymer detachment, it is necessary to determine the mean detachment time of a single breakable link, which is modeled as a spring. Normally, this time can be viewed as the escape of a Brownian particle from the potential well of the spring. However, as the free dangling length of the polymer chain increases, the conformational entropy of the chain is affected by geometric confinement. It means that the wall exerts a repulsive force on the chain, resulting in accelerated link detachment from a macroscopic perspective. In this work, we investigate the effect of entropy on the detachment rate in the case where the substrate is spherical. We demonstrate that spherical confinement accelerates chain detachment both inside and outside the sphere. An analytical expression for the mean detachment time of breakable links is given, which includes an additional pre-factor that is related to the partition function. Additionally, we analyze the expressions for entropic forces inside the sphere, outside the sphere, and on a flat wall, comparing their magnitudes to explain the difference in mean detachment time.

关键词： Polymer detachment Breakable link Entropic force Mean first passage time

Ballistic performance of spherical fragments penetrating PCrNi3MoV target plates

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Defence Technology（防务技术） 2024年第3期33卷 295-307页

作者： Dou Hong Wenbin Li yu zheng Yiming Li Ning Jiang Kebin Zhang Ministerial Key Laboratory of ZNDY Nanjing University of Science and TechnologyNanjingChina

PCrNi3MoV steel is a medium-carbon,low-alloy quenched and tempered steel that finds its applications in military gun barrels due to the high wear resistance and ablation *** study the penetration and failure modes of PCrNi3MoV plates impacted by tungsten spheres,tungsten spheres of various diameters(5 mm,8 mm,and 10 mm)were used to impact PCrNi3MoV steel plates with thicknesses of 6 mm,9 mm,and 14 *** penetration performance of the spheres was analyzed for different velocities,and the ultimate penetration velocity of the plate was *** was found that the primary failure modes of the PCrNi3MoV plate were compression pitting failure and shear *** the dimensional analysis method,a relationship between the bulge height of the steel plate and the fragment velocity,an equation for the ultimate penetration velocity,and a relationship between the target penetration energy and the fragment velocity were ***,a projectile-target action index was proposed to describe the process of tungsten spheres with different velocities impacting target *** results suggested that under the same thickness of the target plate,a larger-diameter fragment required more kinetic energy to obtain the same ultimate penetration effect as a smaller-diameter *** equations obtained through dimensional analysis predicted values that agreed well with experimental values,indicating that these equations can be applied to engineering applications.

关键词： Impact damage Ultimate penetration velocity Bulge height Target penetration energy Failure modes

Modulation of d-orbital to realize enriched electronic cobalt sites in cobalt sulfide for enhanced hydrogen evolution in electrocatalytic water/seawater splitting

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Rare Metals 2024年第2期43卷 511-521页

作者： Jian-Peng Sun yu zheng Zi-Sheng Zhang Xiang-Chao Meng Zi-Zhen Li Key Laboratory of Marine Chemistry Theory and Technology(Ministry of Education) College of Chemistry and Chemical EngineeringOcean University of ChinaQingdao266100China Shanxi Institute of Energy Taiyuan030600China Department of Chemical and Biological Engineering Faculty of EngineeringUniversity of OttawaOttawaONK1N6 N5Canada

Herein,a novel single-atomic Pt doping and interface-rich CoS/Co(OH)_(2)(Pt-CoS/Co(OH)_(2)/C)electrocatalyst has been successfully *** from precise regulation of d-orbital electronic structure modulation on Co site,Pt-CoS/Co(OH)_(2)/C exhibited remarkable HER activity and high stability for hydrogen evolution in splitting both water(73 mV@10 mA·cm^(−2)) and seawater(87 mV@10 mA·cm^(−2)).Notably,atomic Pt doping was introduced into CoS/Co(OH)_(2),which could produce local unbalanced Coulombic force and significantly increased the number of S vacancies,and then expose abundant Co ***,Co(OH)_(2) in Pt-CoS/Co(OH)_(2)/C could act as the adsorption sites for H_(2)O in hydrogen evolution reaction *** functional theory results also proved that atomic Pt doping,S vacancies and Co(OH)_(2) coupling could result in the formation of enriched electronic Co sites and optimize d_(z2) orbital electronic structure,and then realize the depth upward shift of d-band center and enhance the adsorption of H*on Co sites.

关键词： Electrocatalysts Hydrogen evolution reaction Pt-CoS/Co(OH)_(2) d-band center Electronic structure Water/seawater electrolysis

Risk assessment of oil and gas investment environment in countries along the Belt and Road Initiative

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Petroleum Science 2024年第2期21卷 1429-1443页

作者： Bao-Jun Tang Chang-Jing Ji yu-Xian zheng Kang-Ning Liu Yi-Fei Ma Jun-yu Chen Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing100081China School of Management and Economics Beijing Institute of TechnologyBeijing100081China Collaborative Innovation Center of Electric Vehicles in Beijing BeijingChina Sustainable Development Research Institute for Economy and Society of Beijing BeijingChina Institute of Carbon Neutrality ShanghaiTech UniversityShanghai201210China

With the implementation of the Belt and Road Initiative, China is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of investments, it is of significant importance to research the oil and gas investment environment in these countries for China's overseas investment macro-layout. This paper proposes an indicator system including 27 indicators from 6 dimensions. On this basis, game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights, and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021. Finally, the GM(1,1) model is employed to predict risk values for 2022-2025. In conclusion, oil and gas resources and political factors have the greatest impact on investment environment risk, and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results. The research findings may provide scientific decisionmaking recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.

关键词： Belt and Road Initiative Oil and Gas Investment Risk assessment

Scale dependence of forest fragmentation and its climate sensitivity in a semi-arid mountain:Comparing Landsat,Sentinel and Google Earth data

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Geography and Sustainability 2024年第2期5卷 200-210页

作者： yuyang Xie Jitang Li Tuya Wulan yu zheng Zehao Shen Ministry of Education Key Laboratory for Earth Surface Processes College of Urban and Environmental SciencePeking UniversityBeijing 100871China College of Geographic Sciences Inner Mongolia Normal UniversityHohhot 010022China

Landscape fragmentation is generally viewed as an indicator of environmental stresses or risks,but the fragmentation intensity assessment also depends on the scale of data and the definition of spatial *** study aimed to explore the scale-dependence of forest fragmentation intensity along a moisture gradient in Yinshan Mountain of North China,and to estimate environmental sensitivity of forest fragmentation in this semi-arid *** developed an automatic classification algorithm using simple linear iterative clustering(SLIC)and Gaussian mixture model(GMM),and extracted tree canopy patches from Google Earth images(GEI),with an accuracy of 89.2%in the study *** we convert the tree canopy patches to forest category according to definition of forest that tree density greater than 10%,and compared it with forest categories from global land use datasets,FROM-GLC10 and GlobeLand30,with spatial resolutions of 10 m and 30 m,*** found that the FROM-GLC10 and GlobeLand30 datasets underestimated the forest area in Yinshan Mountain by 16.88%and 21.06%,respectively;and the ratio of open forest(OF,10%40%)areas in the underestimated part was 2:*** underestimations concentrated in warmer and drier areas occupied mostly by large coverage of OFs with severely fragmented *** intensity of canopies positively correlated with spring temperature while negatively correlated with summer precipitation and terrain *** summer precipitation was less than 300 mm or spring temperature higher than 4°C,canopy fragmentation intensity rose drastically,while the forest area percentage kept *** study suggested that the spatial configuration,e.g.,sparseness,is more sensitive to drought stress than area *** highlights the importance of data resolution and proper fragmentation measurements for forest patterns and environmental interpretation,which is the base of reliable ecosyst

关键词： Tree canopy fragmentation Forest coverage Google Earth images Spatial Scale effect Semi-arid mountains

Segmented Linear Regression Trees

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Acta Mathematica Sinica,English Series 2024年

作者： Xiang yu zheng Song Xi CHEN JD Technology Peking University

Tree-based models have been widely applied in both academic and industrial settings due to the natural interpretability, good predictive accuracy, and high scalability. In this paper, we focuses on improving the single-tree method and propose the segmented linear regression trees(SLRT) model that replaces the traditional constant leaf model with linear ones. From the parametric view, SLRT can be employed as a recursive change point detect procedure for segmented linear regression(SLR)models, which is much more efficient and flexible than the traditional grid search method. Along this way, we propose to use the conditional Kendalls τ correlation coefficient to select the underlying change points. From the non-parametric view, we propose an efficient greedy splitting method that selects the splits by analyzing the association between residuals and each candidate split variable. Further, with the SLRT as a single-tree predictor, we propose a linear random forest approach that aggregates the SLRTs by a weighted average. Both simulation and empirical studies showed significant improvements than the CART trees and even the random forest.

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Identifying influential spreaders in complex networks based on density entropy and community structure

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Chinese Physics B 2024年第5期33卷 765-774页

作者：苏湛陈磊艾均郑雨语别娜 School of Optical-Electrical and Computer Engineering University of Shanghai for Science and Technology

In recent years,exploring the relationship between community structure and node centrality in complex networks has gained significant attention from researchers,given its fundamental theoretical significance and practical *** address the impact of network communities on target nodes and effectively identify highly influential nodes with strong propagation capabilities,this paper proposes a novel influential spreaders identification algorithm based on density entropy and community structure(DECS).The proposed method initially integrates a community detection algorithm to obtain the community partition results of the *** then comprehensively considers the internal and external density entropies and degree centrality of the target node to evaluate its *** validation is conducted on eight networks of varying sizes through susceptible–infected–recovered(SIR)propagation experiments and network static attack *** experimental results demonstrate that the proposed method outperforms five other node centrality methods under the same comparative conditions,particularly in terms of information spreading capability,thereby enhancing the accurate identification of critical nodes in networks.

关键词： corrigendum electron impact ionization cross sections carbon monoxide

Protein C deficiency with venous and arterial thromboembolic events

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World Journal of Clinical Cases 2024年第12期12卷 2000-2003页

作者： Nan Zhang Dong-Kun Sun Xu Tian Xin-yu zheng Tong Liu Department of Cardiology Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular DiseaseTianjin Institute of CardiologyThe Second Hospital of Tianjin Medical UniversityTianjin 300211China

Protein C(PC)is a key component of the vitamin K-dependent coagulation *** exerts anticoagulant effects by inactivating factors V and *** or inherited PC deficiency results in a prothrombotic state,with presentations varying from asymptomatic to venous ***,there has been an increasing number of reports linking PC deficiency to arterial thromboembolic events,such as myocardial infarction and ischemic *** editorial focuses on the association between PC deficiency and thromboembolism,which may provide some insights for treatment strategy and scientific research.

关键词： Protein C deficiency Venous thromboembolism Myocardial infarction Editorial Arterial thromboembolism