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Soil-atmosphere interaction in earth structures

Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 35-49页

作者： yujun cui Laboratoire Navier Ecole des Ponts ParisTechFrance

The soil-atmosphere interaction was investigated through laboratory testing,field monitoring and numerical *** the laboratory,the soil water evaporation mechanisms were studied using an environmental chamber equipped with a large number of sensors for controlling both the air parameters and soil *** sand and clay were *** case of sand,a dry layer could be formed during evaporation in the near surface zone where the suction corresponded to the residual volumetric water *** evaporative surface was situated at a depth where the soil temperature was the *** case of clay,soil cracking occurred,changing the evaporative surface from one-dimensional to three-dimensional *** suctionbased evaporation model was adapted to take these phenomena into account by adopting a function of dry layer evolution in the case of sand and by adopting a surface crack ratio and a retative humidity ratio in the case of *** the field,the volumetric water content,and the suction as well as the runoff were monitored for an embankment constructed with lime/cement treated *** appeared that using precipitation data only did not allow a correct description of the variations of volumetric water content and suction inside the soils,the consideration of water evaporation being *** was possible to use a correlation between precipiration and *** hydraulic conductivity was found to be a key parameter controlling the variations of volumetric water content and *** the numerical modelling,a fully coupled thermohydraulic model was developed,allowing analyzing the changes in temperature,volumetric water content and suction of soil,with the upper boundary conditions at the interface between soil and atmosphere determined using meteorological *** between simulations and measurements showed the performance of such numerical approach.

关键词： Environmental chamber Soil water evaporation Suction-based evaporation model Embankment Field monitoring Numerical modeling

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Shiga toxin-producing Escherichia coli O104:H4: An emerging 0important pathogen in food safety

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Chinese Science Bulletin 2013年第14期58卷 1625-1631页

作者： cui yujun LI DongFang YANG RuiFu State Key Laboratory of Pathogen and Biosecurity Beijing Institute of Microbiology and Epidemiology BGI-Shenzhen

In 2011, Shiga toxin-producing Escherichia coli O104 : H4 resulted in a large outbreak of bloody diarrhea and hemolytic uremic syndrome (HUS) in Germany and 15 other countries in Europe and North America. This event raised a serious public health crisis and caused more than two billion US dollars in economic losses. In this review, we describe the classification of E. coli, the Germany outbreak, and the characteristics and epidemical source-tracing of the causative agent. We also discuss the genomics analysis of the outbreak organism and propose an open-source genomics analysis as a new strategy in combating the emerging infectious diseases.

关键词：大肠杆菌志贺毒素病原体食品安全大肠埃希菌公共卫生经济损失流行病学

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Investigation of the hydro-mechanical behaviour of compacted expansive clay

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Frontiers of Structural and Civil Engineering 2010年第2期4卷 154-164页

作者： yujun cui An Ninh TA Anh Minh TANG Yingfa LU Ecole des Ponts ParisTech UR Navier-CERMESParis 77455France The China Three Gorges University Yichang 443002China

The hydro-mechanical behaviour of compacted expansive Romainville clay was *** soil was air-dried,crushed,and passed through a 2 mm sieve before being statically compacted to a dry density of 1.35 Mg/*** mechanical behaviour was investigated by tests in oedometer with controlled suction using the vapor equilibrium technique(suction s=0,9,39,and 110 MPa).The vertical stress was applied in the range of 0-800 *** experimental results are shown as follows:1)wetting-induced swelling was higher at lower vertical stresses;2)the vertical stress under which no swelling occurred during water flooding was estimated at 60 kPa,which can be considered as the swelling pressure of the soil tested;3)the soil compressibility(changes of volume upon stress increases)was strongly influenced by the soil suction:the lower the suction,the higher the *** hydraulic behaviour was investigated using a large-scale infiltration chamber(800mm×1000 mm in section and 1000mm high).The large size of the soil column allowed bttrying the volumetric water content sensors(ThetaProbe)without significantly affecting the water transfer and the soil swelling during *** soil suction was monitored along the soil height(every 100 mm)using various relative humidity sensors and *** the infiltration test,water was kept on the soil surface and changes in suction and volumetric water content were monitored for 338 *** wetting front has reached the bottom of the soil column at the end of the *** data from the simultaneous monitoring of suction and water content were used to determine the water retention curve and the unsaturated hydraulic conductivity using the instantaneous profile *** has been observed that the soil water retention curve depends on the soil depth;that is to be related to the soil depthdependent *** unsaturated hydraulic conductiv-ity was found to be quite low,comprised between 3×10-11m/s(at saturated state)and 10-14

关键词： Romainville clay suction control oedometer test large infiltration task hydro-mechanical behaviour

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Temporal variation of soil carbon stock and its controlling factors over the last two decades on the southern Song-nen Plain,Heilongjiang Province

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Geoscience Frontiers 2010年第1期1卷 125-132页

作者： Xueqi Xia Zhongfang Yang Yan Liao yujun cui Yansheng Li School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China Heilongjiang Institute of Geological Survey Harbin 150036 China

Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.

关键词： The southern Song-nen Plain in Heilongjiang Province Soil carbon pool Spatial and temporal variation Carbon cycle

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A study of soil organic carbon distribution and storage in the Northeast Plain of China

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Geoscience Frontiers 2011年第2期2卷 115-123页

作者： Xiaohuan Xi Zhongfang Yang yujun cui Shumei Sun Chengguang Yu Min Li China Geological Survey Beijing China100037 School of the Earth Sciences and Resources China University of Geosciences Beijing 100083 China Heilongjiang Institute of Geological Survey Harbin 150036 China Jilin Institute of Geological Survey Changchun 130061 China Liaoning Institute of Geological Survey Shenyang 110032 China

Employing the Unit Soil Carbon Amount （USCA） approach, soil carbon storage was calcu- lated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004-2006 （MRGS）. The results indicated that the soil organic carbon （SOC） storage in topsoil （0-0.2 m）, subsoil （0-1 m） and deep soil （0-1.8 m） was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km^2, 12,904.7 t/km^2 and 16,157.5 t/km^2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain （Liaoning）, to the middle （Jilin） and the northern Plain （Heilongjiang） -- particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/kin2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984--1986 （SNSS）, the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt （29.4%）, with an average annual decline of 16.0 Mt （1.73%） over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km^2, 1646.4 t/kin2 and 1300.2 t/km^2, respectively, with an average value of 1389.0 t/km^2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land-use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC.

关键词： Northeast Plain Multi-purpose RegionalGeochemical Survey Second National SoilSurvey SOC storage Distributioncharacteristics

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EXISTENCE OF POSITIVE SOLUTIONS TO BOUNDARY VALUE PROBLEM FOR ONE-DIMENSIONAL p-LAPLACIAN

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Annals of Differential Equations 2014年第2期30卷 137-143页

作者： yujun cui Shu Zhang Dept.of Math. Shandong University of Science and Technology

We study the existence of positive solutions to boundary value problems for one- dimensional p-Laplacian under some conditions about the first eigenvalues correspon- ding to the relevant operators by the fixed point theory. The main difficulties are the computation of fixed point index and the subadditivity for positively 1-homogeneous operator.

关键词： p-Laplacian boundary value problem first eigenvalue fixed point theory

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Genetic and Functional Differences of Escherichia coli Strains from Colorectal Cancer Mucosal Tissues

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Engineering 2022年第9期16卷 210-219页

作者： Yuxiao Chang Xiang Li Lei Ding Chao Yang Zhiyuan Pan Ni Han yujun cui Fachao Zhi Ruifu Yang Hong Gao Yujing Bi State Key Laboratory of Pathogen and Biosecurity Beijing Institute of Microbiology and EpidemiologyBeijing 100071China Beijing Shijitan Hospital Capital Medical UniversityBeijing 100038China Guangdong Provincial Key Laboratory of Gastroenterology Institute of Gastroenterology of Guangdong Province&Department of GastroenterologyNanfang HospitalSouthern Medical UniversityGuangzhou 510515China Shenzhen Center for Disease Control and Prevention Shenzhen 518055China

Colorectal cancer(CRC)is the third leading cancer *** has been widely used to analyze the association between the gut microbiota and CRC based on bacterial genus-or species-level comparisons,providing evidence of dysbiosis in CRC ***,this kind of analysis is unable to provide strain-level information for understanding the individual role of a species in ***,we used culturomics to isolate CRC mucosal samples and selected 158 Escherichia coli strains to reveal their differences in both genomics and functions by means of phylogenetic analysis and inflammatory induction based on cell and animal *** genomic comparison,these strains were divided into five *** representative strains of each phylogroup significantly induced different levels of cytokine secretion by human leukemic monocyte(THP-1 cell)-based Transwell and animal *** bioinformatic analysis revealed different profiles of single-nucleotide polymorphisms,genes,and metabolic pathways in the different phylogroups,which can improve the current understanding of the phenotypic differences between these *** strain differences revealed in both genomics and functions indicate that the microbiota’s function at the strain level should be investigated in order to understand the interacting mechanisms between hosts and gut bacteria.

关键词： Colorectal cancer Gut microbiota Culturomics Escherichia coli Strain level

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Near-Field Spot for Localized Light-Excitation of a Single Fluorescent Molecule

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Photonic Sensors 2020年第4期10卷 364-374页

作者： Muhammad Shemyal NISAR yujun cui Kaitong DANG Liyong JIANG Xiangwei ZHAO State Key Laboratory of Bioelectronics School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China Department of Physics School of ScienceNanjing University of Science and TechnologyNanjing 210094China

Zero-mode waveguides have become important tools for the detection of single *** are still,however,serious challenges because large molecules need to be packed into *** circumvent this problem,we investigate and numerically simulate a novel planar sub-wavelength 3-dimension(3D)structure,which is named as near-field *** enables the detection of a single molecule in highly concentrated *** near-field spot can produce evanescent waves at the dielectric/water interface,which exponentially decay as they travel away from the dielectric/water *** evanescent waves are keys for the detection of fluorescently tagged single molecules.A numerical simulation of the proposed device shows that the performance is comparable with a zero-mode *** degrees-of-freedom,however,can potentially supersede its performance.

关键词： Plasmonics single fluorescence molecule evanescent field zero-mode waveguide

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POSITIVE SOLUTION OF SECOND ORDER SINGULAR BOUNDARY VALUE PROBLEM

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Annals of Differential Equations 2007年第1期23卷 1-7页

作者： cui yujun Zou Yumei Li Hongyu Dept. of Applied Math. Shandong University of Science and Technology Qingdao 266510 Shandong Dept. of Basic Courses Taian Campus SDUST Taian 271000 Shandong

The paper deals with the existence of positive solutions of the singular equation u″ ＋ f（t, u） = 0 with the linear boundary condition. We obtain the existence results of positive solution by means of the cone theo... 详细信息

关键词： singular boundary value problems positive solution fixed point index

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On the thermo-mechanical properties of unsaturated soils

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Journal of Rock Mechanics and Geotechnical Engineering 2010年第2期2卷 143-148页

作者： Yingfa Lu Xinxing Wu yujun cui Key Laboratory of Geological Hazards on Three Gorges Reservoir Area of Ministry of Education China Three Gorges UniversityYichang443002China UR NAVIER/CERMES Ecole des Ponts ParisTechParis77455France

The establishment of energy balance equation is necessary to study the thermo-mechanical properties of unsaturated *** solve this equation,the determination of two fundamental parameters as volumetric specific parameter and thermal conductivity coefficient is *** this paper,the effective thermal conductivity coefficient of dry soil grain is analyzed for soils with different compositions,and the thermo-mechanical properties of porous media with water and gas are studied by considering the soil water retention curve（SWRC）.Different methods,*** average method,self-consistent method,Hashin-Strikman method,are employed to calculate thermal conductivity coefficients,and a new method is proposed to determine the thermo-mechanical *** of the results obtained by different methods shows that the proposed method is in a good agreement with the experimental results and is suitable for describing the main properties of the thermo-mechanical behaviors of *** relationship between the SWRC and the seepage curve is further studied by the natural proportional *** characteristics of the SWRC,its differential coefficient and the seepage curve,are investigated by considering the physico-mechanical mechanism;the limit scopes of the indices of the SWRC and the seepage curve are also given.

关键词： unsaturated soil soil water retention curve(SWRC) seepage curve thermal conductivity coefficient comparative analysis

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