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Allometric models for aboveground biomass of six common subtropical shrubs and small trees

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Journal of Forestry Research 2022年第4期33卷 1317-1328页

作者： cheng huang Chun Feng yuhua Ma hua Liu Zhaocheng Wang Shaobo yang Wenjing Wang Songling Fu han y.h.chen College of Forestry and Landscape Architecture Anhui Agricultural University130 Changjiang West RoadHefei 230036AnhuiPeople’s Republic of China Faculty of Natural Resources Management Lakehead University955 Oliver RoadThunder BayON P7B 5E1Canada

The aboveground biomass(AGB)of shrubs and small trees is the main component for the productivity and carbon storage of understory vegetation in subtropical secondary ***,few allometric models exist to accurately evaluate understory *** estimate the AGB of five common shrub(diameter at basehigh)and one small tree species(high,trees’s seedling),206 individuals were harvested and species-specific and multi-species allometric models developed based on four predictors,height(h),stem diameter(D),crown area(Ca),and wood density(ρ).As expected,the six species possessed greater biomass in their stems compared with branches,with the lowest biomass in the ***-specific allometric models that employed stem diameter and the combined variables of D~2h andρDh as predictors accurately estimated the components and total AGB,with R^(2) values from 0.602 and 0.971.A multi-species shrub allometric model revealed that wood density×diameter×height(ρDh)was the best predictor,with R^(2) values ranging from between 0.81 and 0.89 for the components and total AGB,*** results indicated that height(h)and diameter(D)were effective predictors for the models to estimate the AGB of the six species,and the introduction of wood density(ρ)improved their *** optimal models selected in this study could be applied to estimate the biomass of shrubs and small trees in subtropical regions.

关键词： Aboveground biomass Allometric models Shrubs Small trees Subtropical forests

An Initial Analysis of a Strongly Lensed QSO Candidate Identified by LAMOST

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Research in Astronomy and Astrophysics 2023年第10期23卷 349-356页

作者： y.h.chen M.y.Tang h.Shu h.Tu Institute of Astrophysics Chuxiong Normal UniversityChuxiong 675000China School of Physics and Electronical Science Chuxiong Normal UniversityChuxiong 675000China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China Department of Astronomy Yunnan Universityand Key Laboratory of Astroparticle Physics of Yunnan ProvinceKunming 650091China Physics Department&Shanghai Key Lab for Astrophysics Shanghai Normal UniversityShanghai 200234China

From 2011 to 2021,LAMOST has released a total of 76,167 quasar *** try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these *** name,brightness,spectrum,photometry and other information of each QSO will be visually checked *** attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the *** careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial *** A and B are336 apart and they display blue during photometric *** redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less *** the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,hγ,OⅢ,and hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around ***,no galaxies have been found between components A and *** et *** them as binary *** we accidentally find a galaxy group near components A and *** the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed *** estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.

关键词： gravitational lensing:strong (galaxies:)quasars:individual(LAMOST J1606+2900) techniques:imaging spectroscopy

INTERFACIAL DEBONDING OF FRC UNDER CyCLIC LOADING

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 327-330页

作者： Q.J.Zhu y.h.chen J.chen Department of Civil Engineering Hebei Institute of Technology Tangshan 063009 China School of Civil Engineering Beijing Jiaotong University Beijing 100044 ChinaDepartment of Civil Engineering Hebei Institute of Technology Tangshan 063009 China

With the increasingly use of FRC (fiber-reinforced composite) in urban lifelines, me-chanical properties investigation is very important for disaster resistance, especiallythe investigation of fatigue properties. Based on the shear-lag model, an usual com-posite model under cyclic loading is established. According to the Paris formula, therelationship between interfacial fatigue parameters and the number of cycles is ob-tained under the cyclic loading. Interfocial fatigue properties of this model and thegrowth of the interfacial fatigue crack are analyzed. And the Poisson ratio is consid-ered also.

关键词： interfacial debonding fiber matrix cyclic loading crack growth

Mechanical Relaxation of a Ti36.2Zr30.3Cu8.3Fe4Be21.2 Bulk Metallic Glass: Experiments and Theoretical Analysis

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Acta Metallurgica Sinica(English Letters) 2019年第6期32卷 726-732页

作者： J.C.Qiao y.h.chen G.J.Lyu K.K.Song J.M.Pelletier y.yao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China School of Mechanical Electrical and Information EngineeringShandong University(Weihai)Weihai 264209China MATEIS UMR CNRS5510Bat.B.PascalINSA-LyonUniversite de Lyon69621 Villeurbanne CedexFrance

The dynamic mechanical relaxation behavior of Ti36.2Zr30.3Cu8.3Fe4Be21.2 bulk metallic glass with good glass-forming ability was investigated by mechanical *** mechanical relaxation behavior was analyzed in the framework of quasi-point defects *** experimental results demonstrate that the atomic mobility of the metallic glass is closely associated with the correlation factorχ.The physical aging below the glass transition temperature T g shows a non-Debye relaxation behavior,which could be well described by stretched Kohlrausch exponential *** Kohlrausch exponentβaging reflects the dynamic heterogeneities of the metallic *** concentration of"defects"and atomic mobility decrease caused by the in situ successive heating during the mechanical spectroscopy experiments.

关键词： Metallic glasses Mechanical relaxation Physical aging Quasi-point defects

Characteristics of Light Availability Under Forest Canopies and Its Influences on Photosynthesis of Understory Plants

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Forestry Studies in China 2003年第3期5卷 54-62页

作者： han y.h.chen Faculty of Forestry and Forest Environment Lakehead Univerisity955 Oliver RoadThunder BayOntarioCanada P7B 5E1

Available light under forest canopies includes two components, diffuse light and direct light (sunflecks), and is characterized as low and highly dynamic. Understory habitats under different forest types experience different light conditions. Sunflecks as a critical resource for understory plants have great importance on carbon gain of understory plants. Under the light-limiting habitat, understory plants exhibit a high light utilization efficiency attributed by a post-illumination CO2 uptake. Although different species have different photosynthetic responses, shade plants appear to be acclimated to respond more quickly and efficiently to sunflecks. This acclimation includes a faster induction, relatively lower rate of induction loss, lower photosynthetic compensation point, and higher water use efficiency. The process that shade plants harvest light energy is not well known. Studies of photosynthetic responses to sunflecks in natural conditions are rare. Little is known about constraints on sunfleck utilization, which may change seasonally. Extensive field studies in conjunction with laboratory investigations will be needed to further understand potential and actual constraints on sunfleck utilization. Most studies on photosynthetic responses to fluctuating light condition were done in the level of leaves. Fluctuating light utilization on the basis of whole plants and populations presents future challenges to ecologists.

关键词： forest understory light availability sunflecks shade plants photosynthesis light utilization efficiency.

Effects of SiC Nanoparticle Content on the Microstructure and Tensile Mechanical Properties of Ultrafine Grained AA6063-SiC_(np) Nanocomposites Fabricated by Powder Metallurgy

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Journal of Materials Science & Technology 2017年第9期33卷 1023-1030页

作者： X.yao Z.Zhang y.F.Zheng C.Kong M.Z.Quadir J.M.Liang y.h.chen P.Munroe D.L.Zhang State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong University Electron Microscope Unit University of New South Wales School of Materials Science and Engineering University of New South Wales

Ultrafine grained AA6063-SiCnpnanocomposites with 1, 5 and 10 vol.% SiCnphave been fabricated by a novel powder metallurgy process. This process combines high energy ball milling of a mixture of 6063 alloy granules made from machining chips and Si C nanoparticles and thermomechanical powder consolidation by spark plasma sintering and hot extrusion. The microstructure and tensile mechanical properties of the samples were investigated in detail. Increasing the Si C nanoparticle content from 1 to 10 vol.%,the yield strength and ultimate tensile strength increased from 296 and 343 MPa to 545 and 603 MPa respectively, and the elongation to fracture decreased from 10.0%, to 2.3%. As expected, a higher Si C nanoparticle content generates a stronger inhibiting effect to grain growth during the thermomechanical powder consolidation process. Analysis of the contributions of various strengthening mechanisms shows that a higher Si C nanoparticle content leads to a higher contribution from nanoparticle strengthening, but grain boundary strengthening still makes the largest contribution to the strength of the *** the Si C nanoparticle content increased to 10 vol.%, the failure of the nanocomposite was initiated at weakly-bonded interparticle boundaries(IPBs), indicating that with a high flow stress during tensile deformation, the failure of the material is more sensitive to the presence of weakly-bonded IPBs.

关键词： Metal matrix nanocomposite Ultrafine grained material Powder metallurgy Tensile mechanical properties

Biochar-Induced Priming Effects in young and Old Poplar Plantation Soils

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Phyton-International Journal of Experimental Botany 2020年第1期89卷 13-26页

作者： Weiwei Lu yirui Zhang yixian yao yuying Wu han y.h.chen hailin Zhang Jia yu Caiqin Shen Qi Liu honghua Ruan College of Biology and the Environment Co-Innovation Center for Sustainable Forestry in Southern ChinaNanjing Forestry UniversityNanjing210037China Faculty of Natural Resources Management Lakehead UniversityThunder BayONP7B 5E1Canada Department of Plant and Soil Sciences Oklahoma State UniversityStillwaterOK74078USA Advanced Analysis and Testing Center Nanjing Forestry UniversityNanjing210037China State Owned Forest Farm of Dongtai Dongtai224200China College of Forestry Nanjing Forestry UniversityNanjing210037China

The priming effect(PE)induced by biochar provides a basis for evaluating its carbon(C)sequestration potential in soils.A 60 days’laboratory incubation was conducted,which involved the amendment of biochar(1%of soil mass)produced from rice straw at 300℃(B300)and 500℃(B500)to young(y)and old(O)poplar plantation soils,with the aim of studying the responses of biochar-induced PEs to poplar plantation *** incubation included six treatments:y+CK(control),y+B300,y+B500,O+CK,O+B300,and O+*** dioxide(CO_(2))emissions were significantly increased(phe B300 amended soils,while it was decreased in the B500 amended soils compared to the *** primed CO_(2) emissions were 2.35 times higher in the y+B300 than the O+B300 treatments,which was measured to be 18.6 and 5.56 mg C·kg^(-1) with relative PEs of 12.4%and 3.35%,***,there was little difference between the primed CO_(2) emissions in y+B500 and O+B500 treatments,which were measured to be-24.9 and-29.6 mg·C·kg^(-1) with relative PEs of-16.6%and-17.8%,*** organic carbon(DOC)was significantly lower in the young poplar plantation soil than that in the old poplar plantation soil regardless of biochar amendment throughout the incubation,indicating greater C-limit of soil microorganisms in the young poplar plantation *** ^(13)C isotope tracing,neither B300 nor B500 decreased native soil-derived DOC,which indicated that the negative B500-induced PEs were not due to a reduction in the availability of native soil-derived *** conclusion,the response of biochar-induced PEs to poplar plantation age depends on biochar types while soil available C indirectly affects biochar-induced *** studies should focus on how the interactive effects between soil C availability and microbial community impacts biochar-induced PEs.

关键词： Biochar dissolved organic carbon pyrolysis temperature poplar plantation age priming effect

Rational design of AgGaS/ZnS/ZnS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

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Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： h.X.Lu h.Liu Z.Z.Fu y.y.chen h.Q.Dai Z.hu W.L.Zhang R.Q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China yiwu Research Institute of Fudan University YiwuZhejiang 322000China Zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/ZnS/ZnS quantum dots(QDs).In the first step,an inner ZnS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer ZnS shell,thereby facilitating the formation of a thick outer *** the two-step shelling process,the synthesized AgGaS/ZnS/ZnS QDs showed an excellent photoluminescence quantum yield(PLQy)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLQy reported thus far for AgGaS ***,the effect of halogen ions in Zn precursors on the shelling process was *** was proposed that the capacity of halogen ions to coordinate with the QDs influenced the balance between Zn cation diffusion and ZnS shelling ***,the ZnS shelling reaction was dominant when ZnCl_(2)was employed,while Zn cation diffusion was the dominant process under the I^(−)-rich *** work provides insights into the interfacial restructuring during the ZnS shelling and offers a clear map for the tailored synthesis of core/shell QDs.

关键词： AgGaS Quantum dots Photoluminescence Core/shell Alloyed core/shell interface

Conductivity mechanisms of mixed ionic-electronic(MIE) Conductors of M0.6Sr0.4TmXFe1-XO3 Composite(M= LA,PR,BI) For IT-Sofcs

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Conductivity mechanisms of mixed ionic-electronic(MIE) Condu...