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Species divergence in seedling leaf traits and tree growth response to nitrogen and phosphorus additions in an evergreen broadleaved forest of subtropical China

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Journal of Forestry Research 2023年第1期34卷 137-150页

作者： Xuemin Ye Wensheng Bu Xiaofei Hu Bin liu kuan Liang Fusheng Chen Key Laboratory of National Forestry and Grassland Administration On Forest Ecosystem Protection and Restoration of Poyang Lake Watershed Jiangxi Agricultural UniversityNanchang 330045People’s Republic of China Jiangxi Provincial Key Laboratory of Silviculture College of ForestryJiangxi Agricultural UniversityNanchang 330045People’s Republic of China School of Management Nanchang UniversityNanchang 330045People’s Republic of China

Tree competitiveness generally depends on trait plasticity in response to environmental *** effects of nitrogen(N)and phosphorus(P)on leaf trait variability by species is poorly understood,especially in China’s subtropical *** study examined the seedling leaf traits and net primary productivity of all trees>5 cm DBH of two dominant species,Schima superba and Castanopsis carlesii,in an evergreen broadleaved forest fertilized with nitrogen(+N),phosphorus(+P),and nitrogen plus phosphorus(N+P).The effect of N on seedling leaf traits was stronger than P,while fertilization in general was species *** mass per unit area decreased with N for *** seedlings but not for *** N,P,and N/P ratios changed with N addition for both *** four N fractions of carboxylation,bioenergetics,cell wall,and other N metabolites in *** leaves responded significantly to fertilization,while only the cell wall in *** a leaves *** leaf functional traits,including light-saturated photosynthetic rates,water,N,and P use efficiencies,chlorophyll and non structural carbohydrate contents increased with N addition in *** a and by P addition in *** closure at the stand-level increased due to *** biomass and relative growth rate of *** a was not affected by any treatments,while both for *** significantly decreased with N+P ***,nutrient limitation may vary at a small scale among species in a subtropical forest based on their responses of seedling traits and net primary productivity to *** traits are not correlated with the net primary productivity of larger trees except for N fractions,because low light conditions induced by fertilization reduces the proportion of N allocated to photosynthesis in *** addition,acclimation differences of tree species may increase the uncertainty of community succession.

关键词： Ecophysiology Fertilization acclimation N fractions Nutrient limitation Photosynthesis Relative growth rate

Semisolid microstructural evolution of (CNTs+Sip)/AZ91D powder compacts prepared from powders by cold pressing and remelting

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Rare Metals 2020年第6期39卷 733-742页

作者： Pu-Bo Li Wan-Ting Tan Mang-Mang Gao kuan-Guan liu Ningxia Key Laboratory of Photovoltaic Materials Ningxia UniversityYinchuan 750021China

The evolution of semisolid microstructure during partial remelting of(CNTs+Sip)/AZ91 D powder compacts prepared by cold pressing was *** results indicate that rapid grain coarsening is driven by the dissolution of eutecticβphase material during the initial heating period of 0-10 min,so the AZ91 D powders with fine equiaxed grains surrounded by intergranular eutectic phases evolve into compact *** the heating time proceeds,α-Mg particles were gradually separated by liquid due to the phase transformations ofα-Mg+β→L andα-Mg→*** primary particles coarsened rather slowly and the as-received Mg powder evolved into nearly spheroidal particles surrounded by liquid phase after partial *** in situ synthesized Mg2 Sip were distributed homogeneously around the CNTs with maintained structural integrity during partial ***,this microstructural evolution was accompanied by densification through pore *** ideal semisolid ingot suitable for thixoforming can therefore be obtained by partially remelting a(CNTs+Sip)/Mg powder compact.

关键词： Semisolid microstructural evolution Densification Phase transformation Coarsening behavior

Nickel-catalyzed cooperative B-H bond activation for hydroboration of N–heteroarenes, ketones and imines

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Chinese Chemical Letters 2023年第10期34卷 135-139页

作者： Zhuohao Zhao Jianguo liu Chen-Ho tung Wenguang Wang School of Chemistry and Chemical Engineering Shandong UniversityJinan 250100China College of Chemistry Beijing Normal UniversityBeijing 100875China

We report two air-stable nickel(II) half-sandwich complexes,Cp*Ni(1,2-Cy_(2)PC_(6)H_(4)O)(1) and Cp*Ni(1,2-Ph_(2)PC_(6)H4NH)(2),for cooperative B-H bond activation and their applications in catalytic hydroboration of unsaturated organic *** 1 and 2 react with HBpin by adding the B-H bond across the Ni-X bond (X=O or N),giving rise to the 18-electron Ni(II)-H active species,[H1(Bpin)]and[H_(2)(Bpin)].Subtle tuning of the Ni-X pair and the supporting ancillary phosphine have a significant effect on the reactivity and catalytic performance of Cp*Ni(1,2-R_(2)PC_(6)H_(4)X).Unlike[H_(2)(Bpin)],the activation of HBpin in[H1(Bpin)]is reversible,which enables the Ni-O complex to be an effective cooperative catalyst in the hydroboration of N-heteroarenes,and as well as ketones and imines.

关键词： Nickel complex Metal-ligand cooperation B-H activation Hydroboration Metal hydride

Modelling spatial variation in the treatment costs of nonpoint source pollution in mountainous regions of southwest China

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Journal of Mountain Science 2019年第8期16卷 1901-1912页

作者： liu Ju FU Bin ZHANG Cheng-hu WANG Yu-kuan Key Laboratory of Environment Change and Resources Use in Beibu Gulf(Ministry of Education) Key Laboratory of Earth Surface Process and Intelligent SimulationNanning Normal UniversityNanning 530001China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

Non-point source(NPS) pollution is considered to be one of the main threats of the aquatic environment. Mountainous regions are particularly important water sources for urban areas. The various driving factors of NPS pollution such as terrain, precipitation, and vegetation type in mountainous regions show clear spatial heterogeneity. Consequently, the management systems required for NPS pollution in mountainous regions are complex. In this study, we developed a framework to estimate and map the treatment costs for NPS pollution in mountainous regions and applied this method in Baoxing County, a typical mountainous county in Sichuan Province of southwest China. The export levels of total nitrogen(TN) and total phosphorus(TP) in Baoxing County were estimated using the water purification model in InVEST(Itegrated Valuation of Ecosystem Services and Tradeoffs) tool. NPS pollutant treatment costs were calculated based on the level of pollutants exports, water yield, water quality targets, and treatment costs of NPS pollutants per unit mass. The results show that at the watershed level the amounts of TN and TP exported in Baoxing County were below threshold limits. However, at the sub-watershed level, TN and TP excesses of 291.64 and 2.96 tons per year were found, respectively, with mean TN and TP treatment costs of 6.58 US$/hm^2 and 0.35 US$/hm^2. Appraising pollution treatment cost intuitively reflects the overall expenditure in NPS pollution reduction from an economic perspective. This study provides a foundation for the implementation of Payment for Ecosystem Service(PES) and the prevention and control of NPS pollution.

关键词： Nonpoint source pollution Water treatment cost Water purification model InVEST Tool Export coefficient Spatial variation

An Assessment of Changes in Bioclimatic Types in Sichuan Province, 1961-2010

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Journal of Mountain Science 2015年第1期12卷 145-153页

作者： LU Ya-feng liu Yan-Qing XU Pei WANG Yu-kuan liu Yuan Institute of Mountain Hazards and Environment Chinese Academy of Sciences University of Chinese Academy of Sciences Foreign Economic Cooperation Office Ministry of Environmental Protection

Assessing the impact of climate change is important for ecosystem conservation and plant recovery, especially in climate sensitive regions. Various studies suggested that the KSppen classification is an effective method to depict climate change. However, these studies were restricted to large scales or of limited accuracy due to uncertainties in climate model projections. In addition, the impact of elevation on the shift of climate zones, as compared with other factors, is less emphasized. To address these issues we compiled the KSppen Climate Classification （period 1961-2olo） for the study area, Sichuan Province, China. The spatial resolution was selected as x km x x km. Sichuan Province may be characterized by 3 main climate classes and 1o subtypes. The east-west gradient of the climatic regimes in Siehuan is represented by the main climate classes, warm temperate climates （C）, snow climates （D） and polar climates （E）, at which the most abundant class is C. The most abundant subtype is snow climate with dry winter and cool summer （Dwe）. Shifts in K/Sppen climate classes reflect the observed trend of increasing temperature. Finally, the elevation showed an obvious impact on the distribution and the change of climate classes in Siehuan Province. The shift of areas covered by KSppen climate classes increases with elevation.

关键词： Koppen Climate Classification Climatechange Elevation Sichuan

Microstructures and mechanical properties of Cu/Al compound materials during thermal cycle

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Rare Metals 2022年第11期41卷 3911-3918页

作者： Bing Wang Ping liu Xin-kuan liu Zi-Yan Wang Yan-Yan Wang Xiao-Hong Chen Xiao-Zhi liu School of Materials Science and Engineering University of Shanghai for Science and TechnologyShanghai200093China Automobiles Science and Technology(Shanghai)Co. LtdShanghai200433China

Cu/Al compound materials,named as copperclad aluminum bus bars,are widely used in heat dissipation of modern *** thermal cycle tests were conducted at 200,250 and 300℃for different cycle times,*** of thermal cycle temperatures and thermal cycle times on micro structures and mechanical properties of the interface were *** results show that the width of bonding layer and bond strength are significantly affected by thermal cycle temperatures and ***,the variety or the quantity of intermediate compounds is scarcely ***_(2)Cu,Cu_(9) Al_(4)and CuAl were identified on the *** the increase in cycle times,grains of the material grew ***,grains of the interface grew up more apparently than those of Cu and *** knowledge may be applied in the establishment of service condition and quality evaluation of material.

关键词： Copper-clad aluminum bus bars Thermal cycle Interface Bonding Microstructure Intermetallic

Toughening Mechanism of Nanocomposite Physical Hydrogels Fabricated by a Single Gel Network with Dual Crosslinking-- The Roles of the Dual Crosslinking Points

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Chinese Journal of Polymer Science 2017年第1期35卷 25-35页

作者： fu-kuan shi ming zhong li-qin zhang xiao-ying liu 谢续明 Key Laboratory of Advanced Materials (MOE) Department of Chemical Engineering Tsinghua University Beijing 100084 China

A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide）（P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.

关键词： Dual crosslinking single network Nanocomposite physical hydrogel Toughening mechanism

Assessing the impacts of climate change and anthropogenic activities on vegetation in southwest China

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Journal of Mountain Science 2022年第9期19卷 2678-2692页

作者： ZHANG Yu-xin liu Qin WANG Yu-kuan HUANG Jing-han Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China China-Pakistan Joint Research Center on Earth Sciences CAS-HECIslamabad 45320Pakistan Yunnan Provincial Building Materials Science Research and Design Institute Co. LtdKunming 650033China

The topography and geomorphology of southwest China are complex,and the intensity of human activities not *** impact of climate change and anthropogenic activities on vegetation shows temporal and spatial ***,we used normalized difference vegetation index(NDVI)to analyze the impact of climate change and anthropogenic activities on vegetation in four provinces and municipality in the southwest China from 2000 to *** results showed that(1)NDVI increased 0.004–0.005/yr during this *** 57.74%–69.09%of the area with significant changes was found to be primarily affected by anthropogenic activities during all four seasons and the growing season,while 6.05%–10.74%and 5.09%–9.77%of the area was affected by temperature and precipitation,respectively.(2)The impact of temperature and precipitation changes were spatially *** had a positive impact during spring and summer in the northwestern ***,NDVI was positively affected in the southwestern and eastern regions,while the western region was negatively affected by *** temperatures and precipitation had the greatest impact throughout the year.(3)Returning farmland to forests and improving agricultural management demonstrated positive impacts of anthropogenic activities on the vegetation,while areas with significant negative impacts due to anthropogenic activities were located near the provincial capitals of the four provinces and *** study can provide a scientific basis for accurately identifying key ecological protection areas in Southwest China.

关键词： Climate change NDVI Southwest China Vegetation Anthropogenic activities

New Knowledge Network Evaluation Method for Design Rationale Management

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Chinese Journal of Mechanical Engineering 2015年第1期28卷 173-186页

作者： JING Shikai ZHAN Hongfei liu Jihong WANG kuan JIANG Hao ZHOU Jingtao School of Mechanical Engineering Beijing Institute of Technology Shanghai Aircraft Design and Research Institute School of Mechanical Engineering and Automation Beihang University School of Mechanical Engineering Northwestern Polytechnical University

Current design rationale （DR） systems have not demonstrated the value of the approach in practice since little attention is put to the evaluation method of DR knowledge. To systematize knowledge management process for future computer-aided DR applications, a prerequisite is to provide the measure for the DR knowledge. In this paper, a new knowledge network evaluation method for DR management is presented. The method characterizes the DR knowledge value from four perspectives, namely, the design rationale structure scale, association knowledge and reasoning ability, degree of design justification support and degree of knowledge representation conciseness. The DR knowledge comprehensive value is also measured by the proposed method. To validate the proposed method, different style of DR knowledge network and the performance of the proposed measure are discussed. The evaluation method has been applied in two realistic design cases and compared with the structural measures. The research proposes the DR knowledge evaluation method which can provide object metric and selection basis for the DR knowledge reuse during the product design process. In addition, the method is proved to be more effective guidance and support for the application and management of DR knowledge.

关键词： design rationale knowledge reasoning justification support decision support knowledge network evaluation