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Earth and Planetary Physics 2024年第2期8卷 368-374页

作者： LuHuai Jiao Xin Ma YuanNong Zhang TaiFeng Jin Song Fu binbin ni Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The energy spectrum of energetic electrons is a key factor representing the dynamic variations of Earth’s Van Allen radiation *** measurements have indicated that the commonly used Maxwellian and Kappa distributions are inadequate for capturing the realistic spectral distributions of radiation belt *** we adopt the Kappa-type(KT)distribution as the fitting function and perform a statistical analysis to investigate the radiation belt electron flux spectra observed by the Van Allen *** calculating the optimal values of the key KT distribution parameters(i.e.,κandθ2)from the observed spectral shapes,we fit the radiation belt electron fluxes at different L-shells under different geomagnetic *** this manner,we obtain typical values of the KT distribution parameters,which are statistically feasible for modeling the radiation belt electron flux profiles during either geomagnetically quiet or active periods.A comparison of the KT distribution model results with those using the Maxwellian or Kappa distribution reveals the advantage of the KT distribution for studying the overall properties of the radiation belt electron spectral distribution,which has important implications for deepening the current understanding of the radiation belt electron dynamics under evolving geomagnetic conditions.

关键词： radiation belt electron Kappa-type distribution fitting geomagnetic storm

Reasons and promotion strategies of physical activity constraints in obese/ overweight children and adolescents

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Sports Medicine and Health Science 2024年第1期6卷 25-36页

作者： Jiangxi Chen Yinmengke bai Weiguang ni Physical Education College Jilin University130012ChangchunChina

To explore the reasons for low levels of physical activity in obese/overweight children and adolescents and to propose appropriate strategies to promote their physical activity(PA).This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines by searching and analyzing the literature of studies related to physical activity in obese/overweight children and adolescents published between January 2003 and January 2023 in Web of Science,Scopus,and PubMed databases.A total of 31 relevant studies were included for analysis,of which 16 were quantitative and 15 *** to these studies,the PA of obese/overweight children and adolescents is mainly constrained by negative factors:Individual,interpersonal,and *** these factors,low levels of individual motivation and psychological sensitivity and vulnerability,lack of family support,negative social feedback,insufficient protection from government policies,and inadequate support from the built environment are the main reasons that constrain their *** promotion of PA in obese/overweight children and adolescents,who are subject to more constraints at all levels,requires a system of security that involves the government,the community,the school,and the family to address the problems they encounter and enhance the sustainability of engagement in PA.

关键词： Obesity Overweight Children Adolescents Physical activity

Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

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Nano-Micro Letters 2024年第9期16卷 308-324页

作者： Na Yu Idris Temitope bello Xi Chen Tong Liu Zheng Li Yufei Song Meng ni Department of building and Real Estate Research Institute for Sustainable Urban Development(RISUD)and Research Institute for Smart Energy(RISE)The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057GuangdongPeople’s Republic of China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyClear Water BayHong KongPeople’s Republic of China

Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode ***-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting ***,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting *** study introduces a novel A/b-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen *** D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling *** approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

关键词： Reversible protonic ceramic cells Air electrode Ruddlesden-Popper perovskite Hydration Oxygen reduction reaction

Multi-layer hierarchical cellulose nanofibers/carbon nanotubes/vinasse activated carbon composite materials for supercapacitors and electromagnetic interference shielding

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Nano Research 2024年第3期17卷 904-912页

作者： Tianxu Wang Chuanyin Xiong Yongkang Zhang bo Wang Qing Xiong Mengjie Zhao Yonghao ni College of bioresources Chemical&Materials Engineering Shaanxi University of Science and TechnologyXi’an 710021China Department of Chemical and biomedical Engineering The University of MaineOronoME 04469USA University of New brunswick Limerick Pulp&Paper CtrFrederictonNB E3B 5A3Canada

Developing porous self-supporting electrodes with excellent conductivity,good mechanical properties,and high electrochemical activity is crucial for constructing electrode materials with lightweight,ultra-thin,flexible,and high capacitance *** this work,we prepared a cellulose nanofibers(CNFs)/carbon nanotubes(CNTs)/vinasse activated carbon(VAC)(CCV)composite material with a multi-layer hierarchical conductive structure through simple vacuum filtration and *** this composite material,the self-assembly of CNF provides the main skeleton structure of a multi-layer hierarchical *** provides a fast path for the rapid transfer of electrons and is beneficial for the loss of electromagnetic *** provides sufficient double layer *** synergistic effect of the above three endows CCV composite materials with excellent energy storage performance and electromagnetic interference(EMI)shielding *** addition,we endowed the CCV composite with a certain shape and performance by introducing a vitrimer polymer with a dynamic cross-linked network *** summary,thanks to the synergistic effect of various components in the multi-layer hierarchical structure,CCV composite materials exhibit excellent integration performance,especially stable energy storage performance and EMI shielding *** significant properties make CCV composite materials have great application prospects in the fields of energy storage and intelligent EMI shielding.

关键词： self-supporting electrodes multi-layer hierarchical structure supercapacitors electromagnetic interference shielding

Random Terpolymer of Carbon Dioxide,butadiene and Epoxides:Synthesis,Functionalization and Degradability

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Chinese Journal of Chemistry 2024年第14期42卷 1630-1636页

作者： Zi Wang Wuyi Zheng Sicong Yue Kaihao Chen Jun Ling Xufeng ni MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhouZhejiang310058 China Westlake Electronics group Co. Ltd.HangzhouZhejiang310012 China

The utilization of carbon dioxide(CO_(2))as a C1 feedstock is consistently attractive,especially in the preparation of sustainable polymeric *** this contribution,a terpolymer of CO_(2),1,3-butadiene(bD)and epoxide is synthesized by scandium triflate catalyzed cationic ring-opening copolymerization ofα-ethylidene-δ-vinyl-δ-valerolactone(EVL),an intermediate derived from CO_(2)and bD,with *** obtained terpolymer with a CO_(2)content of 22 mol%has a number-average molecular weight(M_(n))up to 7.8 kg/mol and a dispersity(Đ)of *** reactivity ratios of EVL and cyclohexene oxide(CHO)are determined as 0.01 and 1.07,respectively,suggesting random characteristic of the *** preserved C=C double bonds from bD allow for the further modification of the terpolymer by photoinitiated *** yielded networks are fluorescent and *** method offers enhanced versatility to the synthesis and additional functionalization of CO_(2)-based polymers.

关键词： Ring-opening polymerization Copolymerization Carbon dioxide butadiene Scandium triflate Fluorescence

Starting materials, processes and characteristics of bio-based foams: A review

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Journal of bioresources and bioproducts 2024年第2期9卷 160-173页

作者： Xiaohan Wang Jinwon Jang Yanqun Su Jingang Liu Hongjie Zhang Zhibin He Yonghao ni National Engineering Laboratory for Pulp and Paper China National Pulp and Paper Research Institute Co.Ltd.Beijing 100102China Limerick Pulp and Paper Centre and Department of Chemical Engineering University of New BrunswickNew Brunswick E3B 5A3Canada

biofoam products have attracted considerable attention lately because there is a growing demand for green/sustainable *** this end,various biobased foams have either been developed or are currently in development,e.g.,bio-based polyurethanes(PUs),polylactic acid(PLA),starch,and polyhydroxyalkanotates(PHAs).Indeed,significant progress has been made;however,chal-lenges still persist,for example,biobased foam products have poor processability,inferior com-patibility,thermal and strength *** this review,we focus on five biofoam products:namely bio-based PUs,PLA,starch,PHAs,and cellulose biofoam products,along with their prop-erties and performance,as well as their manufacturing *** efforts are still needed to unlock the full potential of these bio-based products and meet the goal of complementing and gradually replacing some of their fossil-based ***,the challenges,as well as arising opportunities of future research directions are discussed.

关键词： biofoam bio-based polyurethanes Polylactic acid Polyhydroxyalkanotate Starch Cellulose Manufacturing process

Development of a DFN-based probabilistic block theory approach for bench face angle design in open pit mining

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Journal of Rock Mechanics and geotechnical Engineering 2024年第8期16卷 3047-3062页

作者： Jianhua Yan Xiansen Xing Zhihai Li Weida ni Liuyuan Zhao Chun Zhu Yuanyuan He School of Earth Sciences and Engineering Hohai UniversityNanjing210098China POWERCHINA Huadong Engineering Corporation Limited Hangzhou311122China Zhejiang Huadong Construction Corporation Limited Hangzhou310004China The Seventh geological brigade of Hubei geological bureau Yichang443000China

In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation *** this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable *** study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks *** proposed approach was applied to a granite mine in ***,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit ***,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each ***,a bench face angle was determined commensurate with an acceptable risk level of *** simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities.

关键词： Open pit mine bench face angle block theory Probabilistic approach Discrete fracture network modeling Fractured rock slope

Formation of free-surface vortex and vortex suppression by rotating stopper-rod at end of tundish casting

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Journal of Iron and Steel Research International 2024年第5期31卷 1104-1116页

作者： Qing Fang Peng Zhao Hua Zhang Wen-hao Zhou gang Yu Jia-hui Wang Hong-wei ni The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan430081HubeiChina

A rotating stopper-rod technique was proposed to suppress the formation of free-surface vortex in the *** large eddy simulation model coupled with volume of fluid model was developed to study the steel–slag–gas three-phase flow *** critical slag entrapment height of the free-surface vortex and mass of residual steel were predicted at different rotating speeds(30,60,90 and 120 r/min)of the rotating *** numerical model was verified by water model *** results showed that by rotating the stopper-rod in the opposite direction of the vortex above the submerged entry nozzle,the formation of vortex can be effectively disturbed and the critical height of the free-surface vortex can be *** for the 2nd strand,when the rotating speeds are 30,60,90 and 120 r/min,the critical height of the free-surface vortex above the 2nd strand is 7.3,4.7,6.3 and 7.4 cm,respectively.A reasonable rotating speed should be 60 r/min,which can reduce about 2 tons of residual *** rotating speeds just can reduce about 1.6 tons of residual steel.

关键词： Tundish Free-surface vortex Stopper-rod Numerical simulation Multiphase flow

Innovative computational tools provide new insights into the polyploid wheat genome

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abIOTECH 2024年第1期5卷 52-70页

作者： Yongming Chen Wenxi Wang Zhengzhao Yang Huiru Peng Zhongfu ni Qixin Sun Weilong guo Frontiers Science Center for Molecular Design breeding Key Laboratory of Crop Heterosis and UtilizationBeijing Key Laboratory of Crop Genetic ImprovementChina Agricultural UniversityBeijing 100193China

bread wheat(Triticum aestivum)is an important crop and serves as a significant source of protein and calories for humans,***,its large and allopolyploid genome poses constraints on genetic *** complex reticulate evolutionary history and the intricacy of genomic resources make the deciphering of the functional genome considerably more ***,we have developed a comprehensive list of versatile computational tools with the integration of statistical models for dissecting the polyploid wheat ***,we summarize the methodological innovations and applications of these tools and databases.A series of step-by-step examples illustrates how these tools can be utilized for dissecting wheat germplasm resources and unveiling functional genes associated with important agronomic ***,we outline future perspectives on new advanced tools and databases,taking into consideration the unique features of bread wheat,to accelerate genomic-assisted wheat breeding.

关键词： Polyploid wheat genome complexity Functional genomics Tool development

Characteristics of the crack tip field in high-speed railway tunnel linings under train-induced aerodynamic shockwaves

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Underground Space 2024年第5期18卷 199-217页

作者： Yi-Kang Liu Yu-Ling Wang E Deng Yi-Qing ni Wei-Chao Yang Wai-Kei Ao School of Civil Engineering Central South UniversityChangsha 410075China National Rail Transit Electrification and Automation Engineering Technology Research Center(Hong Kong branch) The Hong Kong Polytechnic UniversityHong Kong 999077China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China National Engineering Research Center of High-speed Railway Construction Technology Changsha 410075China

High-speed railway tunnels in various countries have continuously reported accidents of vault falling concrete *** the concrete block falling occurs,serious consequences follow,and traffic safety may be *** aerodynamic shockwave evolves from the initial compression wave may be an important inducement causing the tunnel lining cracks to grow and form falling concrete blocks.A joint calculation framework is established based on ANSYS Fluent,AbAQUS,and FRANC3D for calculating the crack tip field under the aerodynamic *** intensification effect of aerodynamic shockwaves in the crack is revealed,and the evolution characteristics of the crack tip field and the influence factors of stress intensity factor(SIF)are *** show that(1)the aerodynamic shockwave intensifies after entering the crack,resulting in more significant pressure in the crack than the input *** maximum pressure of the inclined and longitudinal cracks is higher than the corresponding values of the circumferential crack,respectively.(2)The maximum SIF of the circumferential,inclined,and longitudinal crack appears at 0.5,0.68,and 0.78 times the crack front *** maximum SIF of the circumferential crack is higher than that of the inclined and longitudinal *** possibility of crack growth of the circumferential crack is the highest under aerodynamic shockwaves.(3)The influence of train speed on the SIF of the circumferential crack is more than 40%.When the train speed,crack depth,and crack length change,the change of pressure in the crack is the direct cause of the change of SIF.

关键词： Falling concrete blocks Tunnel lining cracks Aerodynamic shockwave Intensification effect Crack tip field Stress intensity factor