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Strain Gradient Finite Element Formulation of Flexoelectricity in Ferroelectric Material Based on Phase-Field Method

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Acta Mechanica Solida Sinica 2024年第4期37卷 570-579页

作者： Shuai Wang Hengchang Su Min Yi li-hua Shao National Key Laboratory of Strength and Structural Integrity Institute of Solid MechanicsSchool of Aeronautic Science and EngineeringBeihang UniversityBeijing100191People’s Republic of China State Key Laboratory of Mechanics and Control for Aerospace Structures and Institute for Frontier Science and Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China

Flexoelectricity is a two-way coupling effect between the strain gradient and electric field that exists in all dielectrics,regardless of point group ***,the high-order derivatives of displacements involved in the strain gradient pose challenges in solving electromechanical coupling problems incorporating the flexoelectric *** this study,we formulate a phase-field model for ferroelectric materials considering the flexoelectric effect.A four-node quadrilateral element with 20 degrees of freedom is constructed without introducing high-order shape *** microstructure evolution of domains is described by an independent order parameter,namely the spontaneous polarization governed by the time-dependent Ginzburg–Landau *** model is developed based on a thermodynamic framework,in which a set of microforces is introduced to construct the constitutive relation and evolution *** the flexoelectric part of electric enthalpy,the strain gradient is determined by interpolating the mechanical strain at the node via the values of Gaussian integration points in the isoparametric *** model is shown to be capable of reproducing the classic analytical solution of dielectric materials incorporating the flexoelectric *** model is verified by duplicating some typical phenomena in flexoelectricity in cylindrical tubes and truncated pyramids.A comparison is made between the polarization distribution in dielectrics and *** model can reproduce the solution to the boundary value problem of the cylindrical flexoelectric tube,and demonstrate domain twisting at domain walls in ferroelectrics considering the flexoelectric effect.

关键词： Flexoelectricity Phase-field method Ferroelectrics Domain configuration

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The Capture and Catalytic Conversion of CO_(2) by Dendritic Mesoporous Silica-Based Nanoparticles

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Energy & Environmental Materials 2024年第2期7卷 126-151页

作者： Yabin Wang liangzhu huang Songwei li Chuntai liu hua He College of Chemistry and Chemical Engineering Yan'an UniversityYan'an 716000China Institute for Triazine Compounds&Hierarchical Porous Materials Yan'an 716000China National Engineering Research Center for Advanced Polymer Processing Technology Key Laboratory of Materials Processing and Mold(Ministry of Education)Zhengzhou UniversityZhengzhou 450002China

Dendritic mesoporous silica nanoparticles own three-dimensional center-radial channels and hierarchical pores,which endows themselves with super-high specific surface area,extremely large pore volumes,especially accessible internal spaces,and so *** guest species(such as organic groups or metal nanoparticles)could be readily decorated onto the interfaces of the channels and pores,realizing the functionalization of dendritic mesoporous silica nanoparticles for targeted *** adsorbents and catalysts,dendritic mesoporous silica nanoparticles-based materials have experienced nonignorable development in CO_(2)capture and catalytic *** comprehensive review provides a critical survey on this pregnant subject,summarizing the designed construction of novel dendritic mesoporous silica nanoparticles-based materials,the involved chemical reactions(such as CO_(2)methanation,dry reforming of CH_(4)),the value-added chemicals from CO_(2)(such as cyclic carbonates,2-oxazolidinones,quinazoline-2,4(1H,3H)-diones),and so *** adsorptive and catalytic performances have been compared with traditional silica mesoporous materials(such as SBA-15 or MCM-41),and the corresponding reaction mechanisms have been thoroughly *** is sincerely expected that the in-depth discussion could give materials scientists certain inspiration to design brand-new dendritic mesoporous silica nanoparticles-based materials with superior capabilities towards CO_(2)capture,utilization,and storage.

关键词： catalytic conversion CO_(2)adsorption CO_(2)capture dendritic mesoporous silica nanoparticles

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Different mechanisms underlie similar species-area relationships in two tropical archipelagoes

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Plant Diversity 2024年第2期46卷 238-246页

作者： Shengchun li Tieyao tu Shaopeng li Xian Yang Yong Zheng liang-Dong Guo Dianxiang Zhang lin Jiang Key Laboratory of Plant Resources Conservation and Sustainable Utilization South China Botanical GardenChinese Academy of SciencesGuangzhou 510650China ECNU-Alberta Joint Lab for Biodiversity Study Tiantong Forest Ecosystem National Observation and Research StationSchool of Ecological and Environmental SciencesEast China Normal UniversityShanghai 200241China School of Biological Sciences Georgia Institute of TechnologyAtlantaGA 30332USA Jiangxi Academy of Forestry Nanchang 330032China Institute of Eco-Chongming(IEC) Shanghai 202162China State Key Laboratory of Biocontrol School of EcologySun Yat-sen UniversityGuangzhou 510275China School of Geographical Sciences Fujian Normal UniversityFuzhou 350007China State Key Laboratory of Mycology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China

Despite much research in the field of island biogeography,mechanisms regulating insular diversity remain ***,we aim to explore mechanisms underlying plant species-area relationships in two tropical archipelagoes in the South China *** found positive plant species-area relationships for both coral and continental ***,our results showed that different mechanisms contributed to similar plant species-area relationships between the two *** coral islands,soil nutrients and spatial distance among communities played major roles in shaping plant community structure and species *** contrast,the direct effect of island area,and to a lesser extent,soil nutrients determined plant species richness on continental ***,increasing soil nutrients availability(N,P,K)had opposite effects on plant diversity between the two *** summary,the habitat quality effect and dispersal limitation are important for regulating plant diversity on coral islands,whereas the passive sampling effect,and to a lesser extent,the habitat quality effect are important for regulating plant diversity on continental *** generally,our findings indicate that island plant species-area relationships are outcomes of the interplay of both niche and neutral processes,but the driving mechanisms behind these relationships depends on the type of islands.

关键词： Coral and continental islands Plant diversity Soil nutrients Species-area relationships The sampling effect

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Rapid Simultaneous Determination of Four Ganoderic Acids in Ganoderma(Chinese Name:lingzhi)by Direct Infusion-Multiple Reaction Monitoring Cubed

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Journal of Analysis and Testing 2024年第1期8卷 52-62页

作者： Nian Wu Bo Peng Ting li Pengfei tu Shengpeng Wang Bo li Wenjing liu Yuelin Song Modern Research Center for Traditional Chinese Medicine Beijing Research Institute of Chinese MedicineBeijing University of Chinese MedicineBeijing 100029China Amway(China)Botanical Research Center Wuxi 214011China State Key Laboratory of Quality Research in Chinese Medicine Institute of Chinese Medical SciencesUniversity of MacaoTaipa 999078China Amway(Shanghai)Innovation&Science Co. LtdShanghai 201508China School of Pharmacy Henan University of Chinese MedicineZhengzhou 450046China

Attributing to the rapid demand expansion for the edible medicinal materials in the market,the limited throughput of highperformance liquid chromatography-multiple reaction monitoring(HPLC-MRM)cannot fully address the measurement workload for a huge number of testing ***,it is urgent to pursue more efficient approaches for the quality *** of the greater selectivity of MRM cubed(MRM^(3))over MRM,there might be a chance to omit the time-intensive LC *** current study,we attempted to develop a direct infusion(DI)-MRM^(3) program,and the applicability was thereafter assessed through simultaneous determination of four ganoderic acids(GAs)in one of the most famous tonic herbal medicines namely Ganoderma(Chinese name:lingzhi).Primary parameters such as Q1>Q3>QliT ion transitions,collision energy(CE),and excitation energy were optimized by programming online energy-resolved mass spectrometry with authentic compounds.A single DI-MRM measurement merely costed four minutes,and in spite of the wide occurrences of isomers,satisfactory selectivity was *** validation assays demonstrated the method to be sensitive,precise,accurate,and *** quantitative results from DI-MRM^(3) were also justified by conducting LC-MRM measurements in *** differences occurred for the content patterns between the two original sources namely Ganoderma lucidum and ***,and,moreover,either cultivar or harvest time showed dramatical influence on the quantitative features of the four targeted *** importantly,DI-MRM3 is a meaningful analytical option for rapid quantitative analysis of herbal medicines,because of the comparable reliability,nonetheless,less consumptions of both measurement time and solvent,compared with LC-MRM.

关键词： Direct infusion Multiple reaction monitoring cubed High-throughput quantitative analysis Ganoderic acids Ganoderma

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Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

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Petroleum Science 2024年第2期21卷 1275-1289页

作者： Qian li Zi-Jie lin liu Yang Yue Wang Yue li Wei-hua Cai Laboratory of Thermo-Fluid Science and Nuclear Engineering Northeast Electric Power UniversityJilin132000JilinChina School of Energy and Power Engineering Northeast Electric Power UniversityJilin132000JilinChina

The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 *** simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow *** results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were *** calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So hea

关键词： Printed circuit heat exchanger Vaporization Supercritical methane Pseudo-boiling Micro segment analysis

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qGW11a/OsCAT8,encoding an amino acid permease,negatively regulates grain size and weight in rice

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The Crop Journal 2024年第4期12卷 1150-1158页

作者： Peng Gao Feifan Chen Haitang liu Shijun Fan Jierui Zeng Xue Diao Yang liu Wencheng Song Shifu Wang Jing li Xiaobo Zhu Bin tu Weilan Chen Ting li Yuping Wang Bingtian Ma Shigui li hua Yuan Peng Qin State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China Rice Research InstituteSichuan Agricultural UniversityChengdu 611130SichuanChina

Grain size is a key factor influencing grain weight in *** this study,a chromosome segment substitution line(CSSL9-17)was identified,that exhibits a significant reduction in both grain size and weight compared to its donor parent *** investigation identified two quantitative trait loci(QTL)on chromosome 11,designated qGW11a and qGW11b,which contribute to 1000-grain weight with an additive ***_Os11g05690,encoding the amino acid permease OsCAT8,is the target gene of *** of OsCAT8 resulted in decreased grain weight,while OsCAT8 knockout mutants exhibited increased grain *** 287-bp located within the OsCAT8 promoter region of 93-11 negatively regulates its activity,which is subsequently correlated with an increase in grain size and *** results suggest that OsCAT8 functions as a negative regulator of grain size and grain weight in rice.

关键词： Rice Grain size Grain weight QTL OsCAT8

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Role of Vickers ligament in the Pathogenesis of Madelung Deformity

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Current Medical Science 2024年第4期44卷 735-740页

作者： Ge XIONG Wei ZHENG li-hua GONG Department of Hand Surgery Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China Department of Pathology Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China

Objective The Vickers ligament is thought to hinder the growth of palmar ulnar radius by tethering the lunate to the radius,leading to Madelung *** purpose of this study was to clarify the nature of the Vickers ligament and investigate its pathogenesis in Madelung deformities based on our observation of the Vickers *** All 22 patients(33 wrists)with Madelung deformities treated surgically between 2018 and 2022 were *** diagnosis was confirmed radiographically in all *** three-dimensional computed tomography(3D-CT)data of 16 patients(19 wrists)were *** resonance imaging(MRI)data were available for 9 patients(14 wrists).Wrist arthroscopy was used in 4 *** Vickers ligament was resected and submitted for histopathological examination in 8 *** outcomes,3D-CT,MRI,arthroscopy,surgical findings,and histopathology of the Vickers ligament were *** The 3D-CT revealed that the Vickers ligament originated in the metaphysis and formed a metaphyseal defect at the palmar ulnar *** the sequential MR coronal images,the Vickers ligament could be divided into 3 branches,extending to the lunate,triquetrum and ulnar *** and surgical findings revealed that the nature of the Vickers ligament was the stretched palmar ligament of the *** histopathology results revealed ligamentous tissue and fibrocartilaginous metaplasia with a structure similar to that of the triangular fibrocartilage complex(TFCC).Conclusions The Vickers ligament is not a separate aberrant *** nature of the Vickers ligament is a combination of the stretched TFCC ligament(palmar radioulnar ligament,ulnotriquetral ligament and ulnolunate ligament)and radiolunate *** possible pathogenesis of Madelung deformity might be focal early epiphyseal closure at the middle part of the sigmoid notch,which leads to focal growth retardation of the radius and pulls palmar ligaments proximally to for

关键词： Vickers ligament Madelung deformity pathogenesis computed tomography magnetic resonance imaging

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Solidification crack characteristics and sensitivity of peritectic steel

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Journal of Iron and Steel Research International 2024年第7期31卷 1668-1679页

作者： Ya-qiang li Jian-hua liu Zi-ming Wang Ying-ying li Yang He Xiao-wei li Department of Automotive Engineering Hebei Vocational University of Technology and EngineeringXingtai 054000HebeiChina Hebei Special Vehicle Modification Technology Innovation Center Hebei Vocational University of Technology and EngineeringXingtai 054000HebeiChina Institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China School of Petroleum and Natural Gas Engineering Changzhou UniversityChangzhou 213164JiangsuChina

The characteristics and sensitivity of solidification cracks in peritectic steels were investigated using directional solidifi-cation *** cracks were observed in both hypoperitectic steels(12CrlMoV,15CrMo)and hyper-peritectic steel(20CrMo)during solidification at growth velocities of 15,50,and 80 pm/*** the dendritic boundaries,sulphide precipitates were found,promoting crack *** on the statistical analysis of interdendritic cracks in peritectic steels,the area ratio(RA)of interdendritic cracks in a directional solidification structure was proposed to evaluate the crack sensitivity of peritectic ***,the crack sensitivities of peritectic steels(12CrlMoV,15CrMo,and 20CrMo)were tested,evaluated,and compared with the surface crack rates of three types of steels produced from a steel *** results demonstrated that RA was in good agreement with that of the steel plant,and the crack sensitivity of 12CrlMoV steel was the strongest,followed by that of 15CrMo and 20CrMo ***,RA can be used to evaluate the crack sensitivity of peritectic steel.

关键词： Peritectic steel-Directional solidification Growth velocity Dendritic structure Solidification crack Crack sensitivity

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A method for determining the layout of a yaw system based on the Delphi method and the analytic hierarchy process

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Clean Energy 2024年第4期8卷 49-60页

作者： ShuTing lin Lanxing Lu Peng Zhang hua li School of Mechanical Engineering Sichuan UniversityChengdu 610065China

Wind power technology has been widely used due to its characteristics of environmental protection,sustainability and low *** yaw system plays a vital role in improving the energy capture efficiency of a wind ***,the method of layout determination is lacking in the yaw *** solve this problem,a method that combines the Delphi method and the analytic hierarchy process was proposed in this *** evaluation indexes,including transmission efficiency,ratio range,operating temperature range and others,were identified by screening 18 technical indicators using the Delphi ***,the evaluation system of the yaw system was ***,six configuration schemes were ***’scores of schemes were collected according to the evaluation system and the score matrix of evaluation indexes was *** hierarchical model of the evaluation indexes of the yaw system was established and the comprehensive weight was obtained by using the analytic hierarchy pro*** calculating the comprehensive evaluation score,the comprehensive evaluation result was *** 2Z-X(A)negative mechanism,which achieved the highest score of 0.9227,is the optimal scheme.A new method and specific process are provided for *** research gap in the scheme selection method for yaw systems is filled.

关键词： renewable energy generation wind power yaw system Delphi method analytic hierarchy process

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Subgrain-assisted spontaneous grain refinement in rapid solidification of undercooled melts

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Journal of Materials Science & Technology 2024年第7期174卷 234-248页

作者： Jianbao Zhang Dongpeng hua Dexu Cui Xin li Ke hua Yixuan He Haifeng Wang Yuhong Zhao State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China School of Materials Science and Engineering North University of ChinaTaiyuan 030051China

The grain refinement mechanism for rapid solidification of undercooled melts is still an open problem even after 60 years of on-going *** this work,rapid solidification of undercooled Ni and equi-atomic FeCoNiPd melts was studied and spontaneous grain refinement was found at both low and high *** a detailed electron backscattered diffraction analysis,subgrain-induced grain orien-tation scattering and splitting were found to occur along with the transition from coarse dendrites to fine equiaxed grains at low and high undercooling,respectively,indicating that subgrains play an im-portant role during the formation of fine equiaxed *** this basis,a compromise mechanism of subgrain-assisted spontaneous grain refinement was *** the dendrite re-melting induced thermo-mechanical process and fluid flow induced dendrite deformation occur simultaneously during the post-recalescence stage,stress accumulation would be maximum at both low and high undercooling,thus inducing dynamic recrystallization,during which the formation and rotation of subgrains make the grain orientations scattering and even ***,the grain/subgrain size of undercooled FeCoNiPd ascribing to its unique co-segregation behavior keeps almost invariable from low to high undercooling,indicating that the co-segregation strategy would be effective to inhibit grain growth after rapid solidifi-cation and would be useful in practice.

关键词： Rapid solidification Undercooling Spontaneous grain refinement Grain growth High entropy alloy

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