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Topography modulates effects of nitrogen deposition on microbial resource limitation in a nitrogen-saturated subtropical forest

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Forest Ecosystems 2021年第4期8卷 914-922页

作者： Hao Chen Junjie Tang Xibin Sun Kayan Ma Huaihai Chen Dejun Li state key laboratory of Biocontrol School of EcologySun Yat-sen University510275 GuangzhouChina key laboratory of Agro-ecological Processes in subtropical Region Institute of Subtropical AgricultureChinese Academy of Sciences410125 ChangshaHunanChina Huanjiang Observation and Research Station for Karst Ecosystems Institute of Subtropical AgricultureChinese Academy of Sciences547100 HuanjiangChina

Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N ***,after N limitation is removed,which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial ***,we conducted a two-year N addition experiment under two different topography positions(i.e.a slope and a valley)in a N-saturated subtropical *** enzyme activity was measured,and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource ***:In the valley,two-year N addition changed the activity of all studied enzymes to various *** a result,microbial C limitation was aggravated in the valley,and consequently microbial decomposition of soil labile organic C increased,but microbial P limitation was alleviated due to the stoichiometry *** the slope,however,N addition did not significantly change the activity of the studied enzymes,and did not alter the status of microbial resource ***:These results indicate that C is a more limited element for microbial growth than P after removing N limitation,but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical *** findings provide useful supplements to the N saturation theory.

关键词： Nitrogen deposition Topography Nutrient limitation N saturation Enzyme activity Enzymatic stoichiometry

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Spline Fictitious Boundary Element Alternating Method for Edge Crack Problems with Mixed Boundary Conditions

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Computer Modeling in Engineering & sciences 2018年第9期116卷 407-431页

作者： Z.Xu M.Chen X.M.Fan School of Civil Engineering and Transportation South China University of TechnologyGuangzhouChina state key laboratory of subtropical building Science South China University of TechnologyGuangzhouChina

The alternating method based on the fundamental solutions of the infinite domain containing a crack,namely Muskhelishvili’s solutions,divides the complex structure with a crack into a simple model without crack which can be solved by traditional numerical methods and an infinite domain with a crack which can be solved by Muskhelishvili’s ***,this alternating method cannot be directly applied to the edge crack problems since partial crack surface of Muskhelishvili’s solutions is located outside the computational *** this paper,an improved alternating method,the spline fictitious boundary element alternating method(SFBEAM),based on infinite domain with the combination of spline fictitious boundary element method(SFBEM)and Muskhelishvili’s solutions is proposed to solve the edge crack *** the SFBEM and Muskhelishvili’s solutions are obtained in the framework of infinite domain,no special treatment is needed for solving the problem of edge *** mixed boundary conditions edge crack problems with varies of computational parameters are given to certify the high precision,efficiency and applicability of the proposed method compared with other alternating methods and extend finite element method.

关键词： Spline fictitious boundary element alternating method mixed boundary conditions edge crack problem Muskhelishvili’s solutions stress intensity factor

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Mechanical behavior of segment rebar of shield tunnel in construction stage

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第7期9卷 888-899页

作者： Jun-sheng CHEN Hai-hong MO Department of Civil Engineering South China University of Technology Guang＇zhou 510640 China state key laboratory of subtropical building Science South China University of Technology Guang＇zhou 510640 China

In this paper, a 3D finite element （FE） program ADINA was applied to analyzing a tunnel with 9 segment tings. The loads acting on these segment tings included the squeezing action of tail brush of shield machine under attitude deflection, the jacking forces, the grouting pressure and the soil pressure. The analyses focused on the rebar stress in two statuses：（1） normal construction status without shield machine squeezing; （2） squeezing action induced by shield machine under attitude deflection. The analyses indicated that the rebar stress was evidently affected by the construction loads. In different construction status, the rebar stress ranges from -80 MPa to 50 MPa, and the rebar is in elastic status. Even some cracks appear on segments, the stress of segment rebar is still at a low level. It is helpful to incorporate a certain quantity of steel fiber to improve the anti-crack and shock resistance performance.

关键词： Shield tunnel Construction Segment Rebar Finite element (FE) analysis

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Mechanism of gold nanoparticle induced simultaneously increased PCR efficiency and specificity

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Chinese Science Bulletin 2013年第36期58卷 4593-4601页

作者： LIN Yan LI Jia YAO Jing LIANG Yong ZHANG Jie ZHOU QunFang JIANG GuiBin key laboratory of subtropical Agriculture & Environment of the Ministry of Agriculture Huazhong Agricultural University School of Medicine Jianghan University key laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education Jianghan University state key laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences

Gold nanoparticles(AuNPs)have been reported to induce faster heat transfer of polymerase chain reaction(PCR)solution to enhance PCR *** can also increase the specificity of PCR by functioning analogously to single-stranded DNA binding protein(SSB).However,the simple structure of AuNPs makes it difficult to determine how AuNPs affect PCR efficiency and *** study aimed to elucidate the effect of AuNPs on PCR efficiency by altering the denaturation times and annealing *** addition,comparative study of the effect of AuNPs on PCR inhibition caused by two competitive primers allowed investigation of the mechanisms of AuNP-enhanced PCR ***,heat-treated salmon sperm DNA was used to evaluate whether AuNPs could eliminate the inhibitory PCR effect caused by DNA *** study demonstrated that enhanced thermal conductivity by AuNPs was the main mechanism for increased PCR efficiency and *** promoted efficient double-stranded DNA template unwinding and dissociation between mismatched primers,DNA fragments and template,and enhanced PCR efficiency and specificity ***,this significant finding suggests the future use of AuNP-assisted PCR in different fields,especially in rapid clinical diagnosis and screening by PCR.

关键词：金纳米粒子抑制PCR 诱导机制异性单链DNA DNA模板聚合酶链反应鱼精子DNA

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Experimental and theoretical analysis of loading characteristics of electret filter media for charged particles

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Particuology 2024年第10期93卷 87-98页

作者： Yiqi Cai Rongrong Cai Lizhi Zhang key laboratory of Enhanced Heat Transfer and Energy Conservation of Education Ministry School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou510640China state key laboratory of subtropical building Science South China University of TechnologyGuangzhou510640China

The degradation of filtration performance in electret filter media during usage poses a significant challenge. Pre-charging of aerosols has been identified as an effective method to mitigate this issue. However, the effects of particle charging characteristics on the loading characteristics of electret filters still need a comprehensive understanding. In this study, a needle-cylinder corona charger was employed to pre-charge aerosols, and the particle charge state was determined by multiphysics simulation. The effects of particle charge polarity and charge quantity on the loading performance of the electret filter were quantitatively investigated. The results showed that the particle charge polarity had a negligible impact on the loading performance under the condition of the equivalent particle charge quantity. In addition, the charged particles effectively improved the efficiency degradation during the loading process of electret media, with higher charge quantities resulting in more pronounced improvements. The electrostatic attenuation factor showed a negative exponential correlation with the particle charge quantity. This was attributed to the uneven particle deposition on fiber surface due to the attraction of charged particles by the opposite charges on the electret fibers, which alleviated the effect of electrostatic shielding.

关键词： Electret filter Charged particles Loadingcharacteristic Corona charging Electrostatic screening

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Characterization and Molecular Mapping of a New Virescent Mutant in Rice

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Journal of Genetics and Genomics 2014年第6期41卷 353-356页

作者： Qunyu Zhang Dexing Xue Xiaoyu Li Yunming Long Xianjie Zeng Yaoguang Liu state key laboratory for Conservation and Utilization of subtropical Agro-bioresources College of Life Sciences South China Agricultural University

Plant leaves play a significant role in photosynthesis. Normal chloroplast development is critical for plant growth and yield performance. Defect of the chlorophyll in chloroplasts may cause abnormal leaf colors, such as yellow, white, or stripe. Chloroplasts have their own genomes encoding for about 100 genes that are essential for plastid protein synthesis and photosynthesis （Kanno and Hirai, 1993; Sato et al., 1999）. Moreover, over 3000 proteins encoded by plant nuclear genomes target to the chloroplasts and participate in the chloroplast development and/or photosynthesis. Hitherto, a number of plant genes, which encode for enzymes involved in chlorophyll biosynthetic pathways,

关键词： Characterization and Molecular Mapping of a New Virescent Mutant in Rice

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Spatial Heterogeneity of Soil Mineral Oxide Components in Depression Between Karst Hills,Southwest China

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Chinese Geographical Science 2014年第2期24卷 163-179页

作者： DU Hu WANG Kelin PENG Wanxia ZENG Fuping SONG Tongqing ZHANG Hao LU Shiyang key laboratory of Agro-ecological Processes in subtropical Region Institute of Subtropical AgricultureChinese Academy of Sciences Huanjiang Observation and Research Station for Karst Ecosystem Chinese Academy of Sciences University of Chinese Academy of sciences

In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not *** investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest ***,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field *** results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and *** soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope *** reduction in PCA was not appropriate due to the strong spatial heterogeneity in the *** mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil *** were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil *** oxide components affected species diversity,organic matter and nitrogen levels.

关键词： karst soil mineral oxide component ecosystem principal component analysis(PCA) canonical correlation analysis(CCA)

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Research progress on the cleaning and regeneration of PM_(2.5) filter media

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Particuology 2021年第4期19卷 28-44页

作者： Shunjie Wu Rongrong Cai Lizhi Zhang key laboratory of Enhanced Heat Transfer and Energy Conservation of Education Ministry School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China state key laboratory of subtropical building Science South China University of TechnologyGuangzhou 510640China

Reusable PM_(2.5) filter media and their regeneration techniques have attracted widespread attention and shown significant prospect for application in air *** this study,we reviewed the recent research progress on the cleaning and regeneration of indoor PM_(2.5) filters considering two methods,namely,dry and wet *** principles,application status,and limitations of air back-blow and air pulse-jet dry-cleaning techniques were *** wet-cleaning characteristics and regeneration performance of novel washable PM_(2.5) filters,including superhydrophobic,electrostatically enhanced,metal-organic framework composite,and microchannel monolith filters,were evaluated and *** the structural stability and chemical resistance of the filter media during the cleaning process was determined to be key to filter ***,cleaning and regeneration characteristics should be integrated into the design of high-efficiency and low-resistance filter materials to develop more practical reusable PM_(2.5) filter media.

关键词： Aerosol filtration Reusable filter media Cleaning technique Regeneration

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Huangjing(Polygonati rhizoma)is an emerging crop with great potential to fight chronic and hidden hunger

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Science China(Life sciences) 2021年第9期64卷 1564-1566页

作者： Donghong Chen Zhigang Han Jinping Si state key laboratory of subtropical Silviculture Zhejiang A&F UniversityHangzhou 311300China

According to an annual flagship report produced jointly by the FAO and several other organizations,almost 690 million people,or 8.9 percent of the world’s population,were still suffering from chronic hunger in 2019(F... 详细信息

关键词： jointly suffering fight

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Influence of the Number of Loudspeakers on the Timbre in Horizontal and Mixed-Order Ambisoncis Reproduction

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Sound & Vibration 2019年第3期53卷 97-109页

作者： Haiming Mai Bosun Xie Jianliang Jiang Dan Rao Yang Liu Acoustic laboratory School of Physics and OptoeletronicsSouth China University of TechnologyGuangzhouChina state key laboratory of subtropical building Science South China University of TechnologyGuangzhouChina

Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound *** horizontal and spatial Ambisonics reconstruct horizontal and spatial sound field with certain order of spatial harmonics,*** the Shannon-Nyquist spatial sampling frequency limit for accurately reconstructing sound field and the complexity of system increase with the increasing order of *** on the fact that the horizontal localization resolution of human hearing is higher than vertical resolution,mixed-order Ambisonics(MOA)reconstructs horizontal sound field with higher order spatial harmonics,while reconstructs vertical sound field with lower order spatial harmonics,and thereby reaches a compromise between the perceptual performance and the complexity of *** a given order horizontal Ambisoncis or MOA reproduction,the number of horizontal loudspeakers is flexible,providing that it exceeds some low *** using Moore’s revised loudness model,the present work analyzes the influence of the number of horizontal loudspeakers on timbre both in horizontal Ambisonics and MOA *** binaural loudness level spectra(BLLS)of Ambisoncis reproduction are calculated and then compared with those of target sound *** results indicate that below the Shannon-Nyquist limit of spatial sampling,increasing the number of horizontal loudspeakers influence little on BLLS then *** the limit,however,the BLLS for Ambisoncis reproduction deviate from those of target sound *** extent of deviation depends on both the direction of target sound field and the number of *** the number of horizontal loudspeakers may increase the change of BLLS then timbre in some cases,but reduce the change in some other *** MOA,the influence of the number of horizontal loudspeakers on BLLS and timbre reduces when virtual source departs from horizontal plane to the high or low *** sub

关键词： Ambisonics loudspeaker timbre loudness

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