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An improved strain-softening constitutive model of granite considering the effect of crack deformation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1202-1215页

作者： Yapeng Li qiang zhang Qiuxin Gu Peinan Wu Binsong jiang State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou221116China

This paper presents an improved strain-softening constitutive model considering the effect of crack deformation based on the triaxial cyclic loading and unloading test *** improved model assumes that total strain is a combination of plastic,elastic,and crack *** constitutive relationship between the crack strain and the stress was further *** evolutions of mechanical parameters,*** parameters,dilation angle,unloading elastic modulus,and deformation parameters of crack,with the plastic strain and confining pressure were *** the increase in plastic strain,the cohesion,friction angle,dilation angle,and crack Poisson's ratio initially increase and subsequently decrease,and the unloading elastic modulus and the crack elastic modulus nonlinearly *** increasing confining pressure enhances the strength and unloading elastic modulus,and decreases the dilation angle and Poisson's ratio of the *** theoretical triaxial compressive stress-strain curves were compared with the experimental results,and they present a good agreement with each *** improved constitutive model can well reflect the nonlinear mechanical behavior of granite.

关键词： Strain-softening Crack deformation effect Plastic shear strain Constitutive model

Predicting carbon storage of mixed broadleaf forests based on the finite mixture model incorporating stand factors,site quality,and aridity index

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Forest Ecosystems 2024年第3期11卷 276-286页

作者： Yanlin Wang Dongzhi Wang Dongyan zhang qiang Liu Yongning Li College of Forestry Hebei Agricultural UniversityBaoding071001China College of Economics and Management Hebei Agricultural UniversityBaoding071001China

The diameter distribution function(DDF)is a crucial tool for accurately predicting stand carbon storage(CS).The current key issue,however,is how to construct a high-precision DDF based on stand factors,site quality,and aridity index to predict stand CS in multi-species mixed forests with complex *** study used data from70 survey plots for mixed broadleaf Populus davidiana and Betula platyphylla forests in the Mulan Rangeland State Forest,Hebei Province,China,to construct the DDF based on maximum likelihood estimation and finite mixture model(FMM).Ordinary least squares(OLS),linear seemingly unrelated regression(LSUR),and back propagation neural network(BPNN)were used to investigate the influences of stand factors,site quality,and aridity index on the shape and scale parameters of DDF and predicted stand CS of mixed broadleaf *** results showed that FMM accurately described the stand-level diameter distribution of the mixed *** and *** forests;whereas the Weibull function constructed by MLE was more accurate in describing species-level diameter *** combined variable of quadratic mean diameter(Dq),stand basal area(BA),and site quality improved the accuracy of the shape parameter models of FMM;the combined variable of Dq,BA,and De Martonne aridity index improved the accuracy of the scale parameter *** to OLS and LSUR,the BPNN had higher accuracy in the re-parameterization process of ***,LSUR,and BPNN overestimated the CS of *** but underestimated the CS of *** in the large diameter classes(DBH≥18 cm).BPNN accurately estimated stand-and species-level CS,but it was more suitable for estimating stand-level CS compared to species-level CS,thereby providing a scientific basis for the optimization of stand structure and assessment of carbon sequestration capacity in mixed broadleaf forests.

关键词： Weibull function Finite mixture model Linear seemingly unrelated regression Back propagation neural network Carbon storage

Metal–Organic Framework‑Based Photodetectors

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Nano-Micro Letters 2024年第11期16卷 675-703页

作者： Jin‑Biao zhang Yi‑Bo Tian Zhi‑Gang Gu jian zhang State Key Laboratory of Structural Chemistry Structure of MatterFujian Institute of ResearchChinese Academy of SciencesFuzhouFujian 350002People’s Republic of China College of Chemistry and Materials Science Fujian Nornal UniversityFuzhou 350007FujianPeople’s Republic of China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108FujianPeople’s Republic of China University of Chinese Academy of Science Beijing 100049People’s Republic of China

The unique and interesting physical and chemical properties of metal–organic framework(MOF)materials have recently attracted extensive attention in a new generation of photoelectric *** this review,we summarized and discussed the research progress on MOF-based *** methods of preparing MOF-based photodetectors and various types of MOF single crystals and thin film as well as MOF composites are introduced in ***,the photodetectors applications for X-ray,ultraviolet and infrared light,biological detectors,and circularly polarized light photodetectors are ***,summaries and challenges are provided for this important research field.

关键词： Metal-organic frameworks Semiconductor Photodetectors

Enhanced High-Temperature Energy Storage Performance of All-Organic Composite Dielectric via Constructing Fiber-Re in forced Structure

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Energy & Environmental Materials 2024年第2期7卷 299-307页

作者： Mengjia Feng Yu Feng Changhai zhang Tiandong zhang Xu Tong qiang Gao Qingguo Chen Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China

Optimizing the high-temperature energy storage characteristics of energy storage dielectrics is of great significance for the development of pulsed power devices and power control *** a polymer with a higher glass transition temperature(T_(g))as the matrix is one of the effective ways to increase the upper limit of the polymer operating ***,current high-T_(g)polymers have limitations,and it is difficult to meet the demand for high-temperature energy storage dielectrics with only one *** example,polyetherimide has high-energy storage efficiency,but low breakdown strength at high *** has high corona resistance,but low high-temperature energy storage *** this work,combining the advantages of two polymer,a novel high-T_(g)polymer fiber-reinforced microstructure is *** is designed as extremely fine fibers distributed in the composite dielectric,which will facilitate the reduction of high-temperature conductivity loss for *** the same time,due to the high-temperature resistance and corona resistance of polyimide,the high-temperature breakdown strength of the composite dielectric is *** the polyimide content with the best high-temperature energy storage characteristics is determined,molecular semiconductors(ITIC)are blended into the polyimide fibers to further improve the high-temperature ***,excellent high-temperature energy storage properties are *** 0.25 vol%ITIC-polyimide/polyetherimide composite exhibits high-energy density and high discharge efficiency at 150℃(2.9 J cm^(-3),90%)and 180℃(2.16 J cm^(-3),90%).This work provides a scalable design idea for high-performance all-organic high-temperature energy storage dielectrics.

关键词： all-organic energy storage density high-temperature high-temperature breakdown strength

Facile synthesis of high-brightness green-emitting carbon dots with narrow bandwidth towards backlight display

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Chinese Chemical Letters 2024年第5期35卷 277-282页

作者： Rui Cheng Tingting zhang Xin Huang jian Yu State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 210009China

High-performance carbon dots(CDs)allowing the application in high-end display devices are highly desirable and usually limited by the absence of simple and easy synthesis *** this work,we exploited an easy-to-implement strategy for the one-step synthesis of green-emitting CDs(G-CDs)with superb optical *** G-CDs were synthesized using m-phenylenediamine(m-PD)as a single precursor,and the reaction reacted at 180℃for 12 h The resultant G-CDs exhibit high-purity and excitationindependent green fluorescence with the photoluminescence(PL)peak located at 516 nm,full width at half maximum(FWHM)of 46 nm,and PL quantum yield(QY)of∼80%under the 470nm excitation *** G-CDs and corresponding composite film prepared with polyvinyl butyral(G-CDs@PVB)exhibit good PL stability after undergoing long-time storage for one year and 360 h exposure under 460nm blue *** G-CDs@PVB film was used as color-conversion materials in green-emitting light-emitting diode(LED)application,exhibiting a Commission internationale de l’Eclairage(CIE)chromaticity coordinate of(0.21,0.44).The film was also used in CD-based liquid crystal display(CD-LCD)application,achieving a color gamut value of 85%.This work will offer a working basis for the synthesis of high-performance CDs as well as their application in displays.

关键词： Carbon dots One-step synthesis Narrow bandwidth High quantum yield Display

A Beautiful China Initiative Towards the Harmony between Humanity and the Nature

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 33-41页

作者： Changbo Qin qiang Xue Jiawei zhang Lu Lu Shangao Xiong Yang Xiao Xiaojing zhang Jinnan Wang Institute of Strategic Planning Chinese Academy of Environmental PlanningBeijing 100041China The Center for Beautiful China Chinese Academy of Environmental PlanningBeijing 100041China Chinese Academy of Environmental Planning Beijing 100041China

The Beautiful China Initiative(BCI)is a vivid embodiment of the harmonious coexistence between humans and nature during *** the BCI is an effective method for achieving the goals of building a beautiful China,while offering a“Chinese solution”to global sustainable *** article summarizes the progress and main experiences of the BCI,as well as analyzing the primary challenges facing its future ***,five policy recommendations are proposed,which emphasize the importance of top-level design,coordinated planning,and a robust support system in the implementation of the BCI.

关键词： Beautiful China Initiative Ecological civilization Practice Policy suggestion

A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1373-1381页

作者： Xiaorui zhang Min Zou Song Lu Longfei Li Xiaoli Zhuang qiang Feng Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced MetalsUniversity of Science and Technology BeijingBeijing 100083China

A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared,and the evaluation of its high-temperature microstructural stability,oxidation resistance,and mechanical properties was conducted mainly using its cast polycrystalline *** results disclosed that the morphology of theγ′phase remained stable,and the coarsening rate was slow during the long-term aging at 900–1000℃.The activation energy forγ′precipitate coarsening of alloy 9CoNi-Cr was(402±51)kJ/mol,which is higher compared with those of CMSX-4 and some other Ni-based and Co-based ***,there was no indica-tion of the formation of topologically close-packed phases during this *** these factors demonstrated the superior microstructural stability of the *** mass gain of alloy 9CoNi-Cr was 0.6 mg/cm^(2) after oxidation at 1000℃ for 100 h,and the oxidation resistance was comparable to advanced Ni-based superalloys CMSX-4,which can be attributed to the formation of a continuous Al_(2)O_(3) protective ***,the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950℃ is comparable to that of the conventional Ni-based cast superalloy,demonstrating the alloy’s good mechanical properties at high *** is partially because high Cr is bene-ficial in improving theγandγ′phase strengths of alloy 9CoNi-Cr.

关键词： CoNi-based superalloys microstructure coarsening oxidation mechanical properties

Fatigue properties and damage constitutive model of salt rock based on CT scanning

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International Journal of Mining Science and Technology 2024年第2期34卷 245-259页

作者： Junbao Wang Xiao Liu qiang zhang Xinrong Liu Zhanping Song Shijin Feng College of Civil Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Shaanxi Key Lab of Geotechnical and Underground Space Engineering Xi’an 710055China School of Civil Engineering Chongqing UniversityChongqing 400045China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

To investigate the macroscopic fatigue properties and the mesoscopic pore evolution characteristics of salt rock under cyclic loading,fatigue tests under different upper-limit stresses were carried out on salt rock,and the mesoscopic pore structures of salt rock before and after fatigue tests and under different cycle numbers were measured using CT scanning *** on the test results,the effects of the cycle number and the upper-limit stress on the evolution of cracks,pore morphology,pore number,pore volume,pore size,plane porosity,and volume porosity of salt rock were *** failure path of salt rock specimens under cyclic loading was analyzed using the distribution law of plane *** damage variable of salt rock under cyclic loading was defined on basis of the variation of volume porosity with cycle *** order to describe the fatigue deformation behavior of salt rock under cyclic loading,the nonlinear Burgers damage constitutive model was further *** results show that the model established can better reflect the whole development process of fatigue deformation of salt rock under cyclic loading.

关键词： Salt rock Cyclic loading CT scanning Mesoscopic pore evolution Constitutive model

Effects of nutrient limitations on the sinking velocity of Thalassiosira weissflogii

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Acta Oceanologica Sinica 2024年第6期43卷 163-172页

作者： Jie Zhu qiang Hao Wei zhang Yingying Ma jiangning Zeng Ocean College Zhejiang UniversityZhoushan 316000China Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China Key Laboratory of Marine Ecosystem Dynamics Ministry of Natural ResourcesHangzhou 310012China Zhejiang Key Laboratory of Nearshore Engineering Environment and Ecological Security Hangzhou 310012China Tianjin Key Lab of Aqua-Ecology and Aquaculture College of FisheriesTianjin Agricultural UniversityTianjin 300384China

The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic ***,little is known about the effects of different nutrient restrictions on diatom *** this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient *** results showed that the SV of *** under different nutrient limitation conditions varied *** highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/*** the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,***;under conditions with limited nitrate and phosphate concentrations,the SV values of *** significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,*** change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica *** results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure.

关键词： nutrient limitation Thalassiosira weissflogii sinking velocity biochemical component lipid content