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Transport of antibiotic resistance plasmids in porous media and the influence of surfactants

Peipei Chen, Chaoqi Chen, Xiqing Li

《环境科学与工程前沿（英文）》 2018年 第12卷 第2期 doi: 10.1007/s11783-017-0986-7

摘要： Transport of engineered antibiotic resistance plasmids in porous media has been reported to potentially cause significant spreading of antibiotic resistance in the environment. In this work, transport of an indigenous resistance plasmid pK5 in porous media was investigated through packed column experiments. At identical ionic strengths in CaCl solutions, the breakthroughs of pK5 from soil columns were very close to those from quartz sand columns, indicating that transport of pK5 in quartz sand and soil was similar. A similarity in transport behavior was also found between pK5 and an engineered plasmid pBR322 that has approximately the same number of base pairs as pK5. The influence of surfactants, a major group of constituents in soil solutions, was examined using an engineered plasmid pcDNA3.1(+)/myc-His A. The impact of an anionic surfactant, sodium dodecyl sulfate (SDS), was negligible at concentrations up to 200 mg·L . Cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was found to significantly enhance plasmid adsorption at high concentrations. However, at environmentally relevant concentrations (<1 mg·L ), the effect of this surfactant was also minimal. The negligible impact of surfactants and the similarity between the transport of engineered and indigenous plasmids indicate that under environmentally relevant conditions, indigenous plasmids in soil also have the potential to transport over long distances and lead to the spreading of antibiotic resistance.

关键词： Indigenous plasmid     Transport     Porous media     Surfactants    

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Permeability analysis and seepage process study on crystal layer in melt crystallization with fractal and porousmedia theory

Xiaobin JIANG, Baohong HOU, Yongli WANG, Jingkang WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 435-441 doi: 10.1007/s11705-011-1139-3

摘要： In this paper a porous media seepage model was applied to analyze the permeability and study the seepage process of crystal pillar formed in the preparation of electronic grade phosphoric acid (EGPA). By inspecting the seeping process, the structure parameter of crystal pillar could be obtained. Two basic ideal models (perfectly separated model and perfectly connected model) were presented and a characterized factor was introduced to modify the model. A good simulation result was obtained which met the experiment result well. The relationship between and permeability were also discussed. The characterized factor showed potential application on optimizing process.

关键词： melt crystallization     porous media     fractal     permeability     hyperpure material     simulation    

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Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media

Hongtao WANG, Huayong WU

《环境科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 112-128 doi: 10.1007/s11783-008-0067-z

摘要： The purpose of this study is to present a library of analytical solutions for the three-dimensional contaminant transport in uniform flow field in porous media with the first-order decay, linear sorption, and zero-order production. The library is constructed using Green's function method (GFM) in combination with available solutions. The library covers a wide range of solutions for various conditions. The aquifer can be vertically finite, semi-infinitive or infinitive, and laterally semi-infinitive or infinitive. The geometry of the sources can be of point, line, plane or volumetric body; and the source release can be continuous, instantaneous, or by following a given function over time. Dimensionless forms of the solutions are also proposed. A computer code FlowCAS is developed to calculate the solutions. Calculated results demonstrate the correctness of the presented solutions. The library is widely applicable to solve contaminant transport problems of one- or multiple- dimensions in uniform flow fields.

关键词： solution library     contaminant transport     analytical solution     dispersion and advection     porous media     type curve     Green's function method (GFM)    

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An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porousmedia

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 914-936 doi: 10.1007/s11709-021-0750-8

摘要： Crack growth modeling has always been one of the major challenges in fracture mechanics. Among all numerical methods, the extended finite element method (XFEM) has recently attracted much attention due to its ability to estimate the discontinuous deformation field. However, XFEM modeling does not directly lead to reliable results, and choosing a strategy of implementation is inevitable, especially in porous media. In this study, two prevalent XFEM strategies are evaluated: a) applying reduced Young’s modulus to pores and b) using different partitions to the model and enriching each part individually. We mention the advantages and limitations of each strategy via both analytical and experimental validations. Finally, the crack growth is modeled in a natural porous media (Fontainebleau sandstone). Our investigations proved that although both strategies can identically predict the stress distribution in the sample, the first strategy simulates only the initial crack propagation, while the second strategy could model multiple cracks growths. Both strategies are reliable and highly accurate in calculating the stress intensity factor, but the second strategy can compute a more reliable reaction force. Experimental tests showed that the second strategy is a more accurate strategy in predicting the preferred crack growth path and determining the maximum strength of the sample.

关键词： numerical modeling     extended finite element method     porous media     crack growth     stress intensity factor    

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Maximum entropy based finite element analysis of porous media

Emad NOROUZI, Hesam MOSLEMZADEH, Soheil MOHAMMADI

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 364-379 doi: 10.1007/s11709-018-0470-x

摘要： The maximum entropy theory has been used in a wide variety of physical, mathematical and engineering applications in the past few years. However, its application in numerical methods, especially in developing new shape functions, has attracted much interest in recent years. These shape functions possess the potential for performing better than the conventional basis functions in problems with randomly generated coarse meshes. In this paper, the maximum entropy theory is adopted to spatially discretize the deformation variable of the governing coupled equations of porous media. This is in line with the well-known fact that higher-order shape functions can provide more stable solutions in porous problems. Some of the benchmark problems in deformable porous media are solved with the developed approach and the results are compared with available references.

关键词： maximum entropy FEM     fully coupled multi-phase system     porous media    

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Heat transfer of phase change materials (PCMs) in porous materials

C Y ZHAO, D ZHOU, Z G WU

《能源前沿（英文）》 2011年 第5卷 第2期   页码 174-180 doi: 10.1007/s11708-011-0140-3

摘要： In this paper, the feasibility of using metal foams to enhance the heat transfer capability of phase change materials (PCMs) in low- and high-temperature thermal energy storage systems was assessed. Heat transfer in solid/liquid phase change of porous materials (metal foams and expanded graphite) at low and high temperatures was investigated. Organic commercial paraffin wax and inorganic calcium chloride hydrate were employed as the low-temperature materials, whereas sodium nitrate was used as the high-temperature material in the experiment. Heat transfer characteristics of these PCMs embedded with open-cell metal foams were studied. Composites of paraffin and expanded graphite with a graphite mass ratio of 3%, 6%, and 9% were developed. The heat transfer performances of these composites were tested and compared with metal foams. The results indicate that metal foams have better heat transfer performance due to their continuous inter-connected structures than expanded graphite. However, porous materials can suppress the effects of natural convection in liquid zone, particularly for PCMs with low viscosities, thereby leading to different heat transfer performances at different regimes (solid, solid/liquid, and liquid regions). This implies that porous materials do not always enhance heat transfer in every regime.

关键词： heat transfer     thermal energy storage     phase change materials     natural convection     porous media    

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An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

《能源前沿（英文）》 2010年 第4卷 第4期   页码 507-516 doi: 10.1007/s11708-010-0017-x

摘要： Thermal convection of viscoelastic fluids saturating a horizontal porous layer heated from below is analyzed using a thermal nonequilibrium model to take account of the interphase heat transfer between the fluid and the solid. The viscoelastic character of the flow is considered by a modified Darcy’s law. An autonomous system with five differential equations is deduced by applying the truncated Galerkin expansion to the momentum and heat transfer equations. The effects of interphase heat transfer on the thermal convection of viscoelastic fluids in a porous medium are analyzed and discussed. The results show that the weak interphase heat transfer tends to stabilize the steady convection.

关键词： thermal convection     porous media     viscoelastic fluid     thermal nonequilibrium model    

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多孔介质多相流动在能源转型中的应用

Martin J. Blunt, 林青阳

《工程（英文）》 2022年 第14卷 第7期   页码 10-14 doi: 10.1016/j.eng.2021.08.008

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cerium redox flow battery using computational fluid dynamics: Mathematical and modelling aspects of porousmedia

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 399-409 doi: 10.1007/s11705-020-1934-9

摘要： Description of electrolyte fluid dynamics in the electrode compartments by mathematical models can be a powerful tool in the development of redox flow batteries (RFBs) and other electrochemical reactors. In order to determine their predictive capability, turbulent Reynolds-averaged Navier-Stokes (RANS) and free flow plus porous media (Brinkman) models were applied to compute local fluid velocities taking place in a rectangular channel electrochemical flow cell used as the positive half-cell of a cerium-based RFB for laboratory studies. Two different platinized titanium electrodes were considered, a plate plus a turbulence promoter and an expanded metal mesh. Calculated pressure drop was validated against experimental data obtained with typical cerium electrolytes. It was found that the pressure drop values were better described by the RANS approach, whereas the validity of Brinkman equations was strongly dependent on porosity and permeability values of the porous media.

关键词： CFD simulation     porous media     porous electrode     pressure drop     redox flow battery    

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Quantification of seepage in a multi-layered disconnected river-aquifer system

Jiang LI, Haizhu HU, Xiaomin MAO, Yi LIU

《农业科学与工程前沿（英文）》 2017年 第4卷 第2期   页码 237-245 doi: 10.15302/J-FASE-2017135

摘要： Quantification of seepage in disconnected river-aquifer systems is significant for local water management and groundwater pollution control, especially in areas with water shortage or contamination. The vadose zone under riverbeds usually exhibits a multi-layered structure, particularly when paved with low permeability liners. To evaluate the impact of engineering solutions to seepage under such conditions, we proposed an approach by combining GIS and the minimum flux in saturation layer (MFSL) method. MFSL can calculate the stable seepage rate by assessing the dominant low permeability layers (including but not limited to the liners) in multi-layered disconnected river-aquifer systems. We used MFSL to calculate local seepage rate, and used GIS to extend the results to a regional scale. The reliability of MFSL is discussed by comparing the results with the double ring infiltration test, the numerical simulation by HYDRUS, and the methods of stream package in MODFLOW, including its improved form. A case study was conducted in the Yongding River with river-aquifer seepage calculated under various conditions, including different river water levels (i.e., under the designated water level, drought stage level, flood stage level and flood inundation level) and with/without low permeability liners (i.e., ecological membranes or geomembrane). Results showed that low permeability liners could greatly reduce the seepage rate. However, if an unlined inundation area exists, the seepage rate may increase greatly. The results indicated that the proposed method was reliable and convenient for calculating long-term, large area seepage in disconnected river-aquifer systems especially those paved with liners.

关键词： infiltration     low permeability liner     multi-layered porous media     river-aquifer seepage    

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Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

Chong PANG, Wei TAN, Endian SHA, Yuanqing TAO, Liyan LIU

《化学科学与工程前沿（英文）》 2012年 第6卷 第3期   页码 329-338 doi: 10.1007/s11705-012-1205-5

摘要： The design of two-stage pusher centrifuges have developed rapidly, but a good understanding of the theory behind their practice is a long-standing problem. To better understand centrifugal filter processes, the computational fluid dynamics (CFD) software program FLUENT has been used to model the three-dimensional geometry and to simulate multiphase flows based on Euler-Euler, moving mesh, dynamic mesh and porous media models. The simulation tangential velocities were a little smaller than those for rigid-body motion. In the stable flow region, the radial velocities were in good agreement with the theoretical data. Additionally, solid concentration distribution were obtained and also showed good agreement with the experimental data. These results show that this simulation method could be an effective tool to optimize the design of the two-stage pusher centrifuge.

关键词： two-stage pusher centrifuge     multiphase flow     CFD     dynamic mesh     porous media    

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Simulation of heterogeneous two-phase media using random fields and level sets

George STEFANOU

《结构与土木工程前沿（英文）》 2015年 第9卷 第2期   页码 114-120 doi: 10.1007/s11709-014-0267-5

摘要： The accurate and efficient simulation of random heterogeneous media is important in the framework of modeling and design of complex materials across multiple length scales. It is usually assumed that the morphology of a random microstructure can be described as a non-Gaussian random field that is completely defined by its multivariate distribution. A particular kind of non-Gaussian random fields with great practical importance is that of translation fields resulting from a simple memory-less transformation of an underlying Gaussian field with known second-order statistics. This paper provides a critical examination of existing random field models of heterogeneous two-phase media with emphasis on level-cut random fields which are a special case of translation fields. The case of random level sets, often used to represent the geometry of physical systems, is also examined. Two numerical examples are provided to illustrate the basic features of the different approaches.

关键词： microstructure     random fields     level sets     shape recovery     two-phase media    

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Social media and mobility landscape: Uncovering spatial patterns of urban human mobility with multi source

Yilan Cui, Xing Xie, Yi Liu

《环境科学与工程前沿（英文）》 2018年 第12卷 第5期 doi: 10.1007/s11783-018-1068-1

摘要：

Check-in and survey data are explored to identify personal activity-specific places.

Ways for detecting and moderating sample bias of Weibo check-in data is proposed.

A graphic representation of urban activity intensity in Beijing, China is presented.

The potential application of Weibo check-in data for urban analysis is introduced.

关键词： Social media     Human mobility     Population bias     Sample reconstruction     Data integration    

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Immunogenicity and protective immunity against otitis media caused by pneumococcus in mice of Hib conjugate

null

《医学前沿（英文）》 2016年 第10卷 第4期   页码 490-498 doi: 10.1007/s11684-016-0470-y

摘要：

This study evaluated the immunogenicity and protective immunity of a Hemophilus influenzae b (Hib) polysaccharide conjugate vaccine with the pneumococcal surface adhesin A (PsaA) protein carrier in young mice. The Hib polysaccharide was conjugated with the rPsaA protein carrier, which was produced using recombinant DNA technology. A total of 15 young mice aged 3 weeks to 5 weeks were immunized with the conjugate vaccine, and another 15 young mice of the same age were immunized with the licensed Hib-tetanus toxoid (TT) vaccine. Furthermore, the third group of 15 young mice was inoculated with phosphate buffer saline as control. The immunized mice were inoculated with pneumococcus in the middle ear. Results showed that IgG antibody responses against both the PsaA protein and Hib polysaccharide were observed in the Hib-PsaA group. However, no statistical difference was observed in the titer of IgG against the Hib polysaccharide between Hib-PsaA and Hib-TT groups. The elimination rate of pneumococcus and the inflammation of the middle ear showed the effectiveness of protective immunity against otitis media caused by pneumococcus. Our results suggest that the Hib polysaccharide can be successfully conjugated with rPsaA via amide condensation. This new Hib-PsaA conjugate vaccine can induce both anti-PsaA and anti-Hib immune responses in young mice and elicit effective protection against acute otitis media caused by pneumococcus.

关键词： conjugate vaccine     pneumococcal surface adhesin A     Hemophilus influenzae b     immunogenicity     otitis media    

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标题 作者 时间 类型 操作

Transport of antibiotic resistance plasmids in porous media and the influence of surfactants

Peipei Chen, Chaoqi Chen, Xiqing Li

期刊论文

Permeability analysis and seepage process study on crystal layer in melt crystallization with fractal and porousmedia theory

Xiaobin JIANG, Baohong HOU, Yongli WANG, Jingkang WANG

期刊论文

Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media

Hongtao WANG, Huayong WU

期刊论文

An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porousmedia

期刊论文

Maximum entropy based finite element analysis of porous media

Emad NOROUZI, Hesam MOSLEMZADEH, Soheil MOHAMMADI

期刊论文

Heat transfer of phase change materials (PCMs) in porous materials

C Y ZHAO, D ZHOU, Z G WU

期刊论文

An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

期刊论文

Martin Blunt：Flow in Porous Media in the Energy Transition（2022年10月12日）

2022年10月18日

会议视频

多孔介质多相流动在能源转型中的应用

Martin J. Blunt, 林青阳

期刊论文

cerium redox flow battery using computational fluid dynamics: Mathematical and modelling aspects of porousmedia

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

期刊论文

Quantification of seepage in a multi-layered disconnected river-aquifer system

Jiang LI, Haizhu HU, Xiaomin MAO, Yi LIU

期刊论文

Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

Chong PANG, Wei TAN, Endian SHA, Yuanqing TAO, Liyan LIU

期刊论文

Simulation of heterogeneous two-phase media using random fields and level sets

George STEFANOU

期刊论文

Social media and mobility landscape: Uncovering spatial patterns of urban human mobility with multi source

Yilan Cui, Xing Xie, Yi Liu

期刊论文

Immunogenicity and protective immunity against otitis media caused by pneumococcus in mice of Hib conjugate

null

期刊论文