WorldWideScience

Sample records for open cell foam

  1. Open-celled polyurethane foam

    Science.gov (United States)

    Russell, L. W.

    1970-01-01

    Open-celled polyurethane foam has a density of 8.3 pounds per cubic foot and a compressive strength of 295 to 325 psi. It is useful as a porous spacer in layered insulation and as an insulation material in vacuum tight systems.

  2. Open Cell Metal Foams for Beam Liners?

    CERN Document Server

    Croce, R P; Stabile, A

    2013-01-01

    The possible use of open-cell metal foams for particle accelerator beam liners is considered. Available materials and modeling tools are reviewed, potential pros and cons are pointed out, and a study program is outlined.

  3. Fracture of open- and closed-cell metal foams

    NARCIS (Netherlands)

    Onck, P; van Merkerk, R.; Raaijmakers, A; De Hosson, JTM

    2005-01-01

    Two closed cell aluminium foams and one open cell nickel-chromium foam were subjected to microstructural characterization, in situ fracture tests and fractography. The failure process of the open cell foam was observed to be rather ductile, while that of the closed cell foams was found to be brittle

  4. Fracture of open- and closed-cell metal foams

    NARCIS (Netherlands)

    Onck, P; van Merkerk, R.; Raaijmakers, A; De Hosson, JTM

    2005-01-01

    Two closed cell aluminium foams and one open cell nickel-chromium foam were subjected to microstructural characterization, in situ fracture tests and fractography. The failure process of the open cell foam was observed to be rather ductile, while that of the closed cell foams was found to be

  5. Heat Transfer and Acoustic Properties of Open Cell Aluminum Foams

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The aluminum open cell foams have been prepared by the conventional precision casting method to investigate the thermal and acoustic properties. A water heating system and silencers were organized as a first step for its applications. The temperature increase between the top and bottom of the foam became larger as the cell size increased in the heat transfer measurement. Sound absorption ratio of the close cell foams was 60%-100%,whereas the open cell aluminum foam showed only 10%-20% of sound absorption at low frequency. When the prototype electric water heater manufactured by combining aluminum open cell foam with a heater was heated to 100-400℃, the highest temperature of water was in the range of 16-46℃. This suggests that there could be potential for this type of heater to be used as a commercial electric water heater. Sound silencer made with the aluminum open cell foam was applied to exit of exhaustion side at air pressure line. Sound silencing effect of open-celled aluminum foam showed that the noise level went down by introducing smaller cell size foam.

  6. Deformation behavior of open-cell stainless steel foams

    Energy Technology Data Exchange (ETDEWEB)

    Kaya, A.C., E-mail: a.kaya@campus.tu-berlin.de; Fleck, C.

    2014-10-06

    This study presents the deformation and cell collapse behavior of open-cell stainless steel foams. 316L stainless-steel open-cell foams with two porosities (30 and 45 pores per inch, ppi) were produced with the pressureless powder metallurgical method, and tested in quasi-static compression. As a result of the manufacturing technique, 316L stainless steel open-cell foams have a high amount of microporosity. The deformation behavior was investigated on a macroscopic scale by digital image correlation (DIC) evaluation of light micrographs and on the microscopic scale by in situ loading of cells in the scanning electron microscope. The deformation behavior of the metal foams was highly affected by microstructural features, such as closed pores and their distribution throughout the foam specimen. Moreover, the closed pores made a contribution to the plateau stress of the foams through cell face stretching. Strut buckling and bending are the dominant mechanisms in cell collapse. Although there are edge defects on the struts, the struts have an enormous plastic deformation capability. The cell size of the steel foams had no significant effect on the mechanical properties. Due to the inhomogeneities in the microstructure, the measured plateau stresses of the foams showed about 20% scatter at the same relative density.

  7. Open Cell Conducting Foams for High Synchrotron Radiation Beam Liners

    CERN Document Server

    Petracca, Stefania

    2014-01-01

    The possible use of open-cell conductive foams in high synchrotron radiation particle accelerator beam liners is considered. Available materials and modeling tools are reviewed, potential pros and cons are discussed, and preliminary conclusions are drawn.

  8. Preparation of open-cell metal foams by investment cast

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Metal foams are a new kind of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They can be divided into closed and open cell structures. In this paper the open cell structures,called sponges, were treated. A new technique to manufacture sponges by plaster investment casting was described.Experimental results show that it is essential to make a sound plaster mould by casting plaster slurry into the polyurethane foams and infiltrate the open channels of the baked plaster mold by molten metal. The optimal processes include plaster slurry preparation, plaster mold baking, and molten metal infiltration. The sponge sample with porosity of 97% is presented.

  9. Preparation of open-cell metal foams by investment cast

    Directory of Open Access Journals (Sweden)

    Lucai WANG

    2005-02-01

    Full Text Available Metal foams are a new kind of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They can be divided into closed and open cell structures. In this paper the open cell structures, called sponges, were treated. A new technique to manufacture sponges by plaster investment casting was described. Experimental results show that it is essential to make a sound plaster mould by casting plaster slurry into the polyurethane foams and infiltrate the open channels of the baked plaster mold by molten metal. The optimal processes include plaster slurry preparation, plaster mold baking, and molten metal infiltration. The sponge sample with porosity of 97% is presented.

  10. Acoustic absorption behaviour of an open-celled aluminium foam

    CERN Document Server

    Han Fu Sheng; Zhao Yu Yuan; Gibbs, B

    2003-01-01

    Metal foams, especially close-celled foams, are generally regarded as poor sound absorbers. This paper studies the sound absorption behaviour of the open-celled Al foams manufactured by the infiltration process, and the mechanisms involved. The foams show a significant improvement in sound absorption compared with close-celled Al foams, because of their high flow resistance. The absorption performance can be further enhanced, especially at low frequencies, if the foam panel is backed by an appropriate air gap. Increasing the air-gap depth usually increases both the height and the width of the absorption peak and shifts the peak towards lower frequencies. The foam samples with the smallest pore size exhibit the best absorption capacities when there is no air gap, whereas those with medium pore sizes have the best overall performance when there is an air gap. The typical maximum absorption coefficient, noise reduction coefficient and half-width of the absorption peak are 0.96-0.99, 0.44-0.62 and 1500-3500 Hz, r...

  11. Defects in aluminum foam with superfine open-cell structure

    Institute of Scientific and Technical Information of China (English)

    Wang Fang; Zhang Zhimin; Li Baocheng; Wang Lucai

    2008-01-01

    The infiltration casting process for producing aluminum foam includes three steps: preparing precursor using NaCI particles, infiltrating molten aluminum and cleaning NaCI precursor. Defects occur during the preparation of aluminum foam with superfine open-cell structure, and influence the pore structure and performance of aluminum foam materials. The types of the defect and their forming mechanisms are analyzed in this paper. The defects include point defects and linear metal defects, and are caused by the defects in salt precursor and the insufficient infiltration of molten aluminum into precursor. With the choice of proper precursor preparation method and infiltration process parameters, the complete aluminum foam with superfine pores could be achieved.

  12. Lightweight Hybrid Ablator Incorporating Aerogel-Filled Open-Cell Foam Structural Insulator, Phase II Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In previous work for NASA and DoD, Ultramet developed lightweight open-cell foam insulators composed of a carbon or ceramic structural foam skeleton filled with a...

  13. Lightweight Hybrid Ablator Incorporating Aerogel-Filled Open-Cell Foam Structural Insulator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In previous work for NASA and DoD, Ultramet developed lightweight open-cell foam insulators composed of a carbon or ceramic structural foam skeleton filled with a...

  14. Blood Flow through an Open-Celled Foam

    Science.gov (United States)

    Ortega, Jason; Maitland, Duncan

    2011-11-01

    The Hazen-Dupuit-Darcy (HDD) equation is commonly used in engineering applications to model the pressure gradient of flow through a porous media. One major advantage of this equation is that it simplifies the complex geometric details of the porous media into two coefficients: the permeability, K, and form factor, C. However through this simplification, the flow details within the porous media are no longer accessible, making it difficult to study the phenomena that contribute to changes in K and C due to clotting of blood flow. To obtain a more detailed understanding of blood flow through a porous media, a direct assessment of the complex interstitial geometry and flow is required. In this study, we solve the Navier-Stokes equations for Newtonian and non-Newtonian blood flow through an open-celled foam geometry obtained from a micro-CT scan. The nominal strut size of the foam sample is of O(10e-5) m and the corresponding Reynolds number based upon this length ranges up to O(10). Fitting the pressure gradient vs. Darcy velocity data with the HDD equation demonstrates that both viscous and inertial forces play an important role in the flow through the foam at these Reynolds numbers. Recirculation zones are observed to form in the wake of the pore struts, producing regions of flow characterized by both low shear rates and long fluid residence times, factors of which have been shown in previous studies to promote blood clotting.

  15. Multiscale Analysis of Open-Cell Aluminum Foam for Impact Energy Absorption

    Science.gov (United States)

    Kim, Ji Hoon; Kim, Daeyong; Lee, Myoung-Gyu; Lee, Jong Kook

    2016-09-01

    The energy-absorbing characteristics of crash members in automotive collision play an important role in controlling the amount of damage to the passenger compartment. Aluminum foams have high strength-to-weight ratio and high deformability, thus good crashworthiness is expected while maintaining or even saving weights when foams are implemented in crash members. In order to investigate the effect of the open-cell aluminum foam fillers on impact performance and weight saving, a multiscale framework for evaluating the crashworthiness of aluminum foam-filled members is used. To circumvent the difficulties of mechanical tests on foams, a micromechanical model of the aluminum foam is constructed using the x-ray micro tomography and virtual tests are conducted for the micromechanical model to characterize the behavior of the foam. In the macroscale, the aluminum foam is represented by the crushable foam constitutive model, which is then incorporated into the impact test simulation of the foam-filled crash member. The multiscale foam-filled crash member model was validated for the high-speed impact test, which confirms that the material model characterized by the micromechanical approach represents the behavior of the open-cell foam under impact loading well. Finally, the crash member design for maximizing the energy absorption is discussed by investigating various designs from the foam-only structure to the hollow tube structure. It was found that the foam structure absorbs more energy than the hollow tube or foam-filled structure with the same weight.

  16. Open-cell foams of polyethylene terephthalate/bisphenol a polycarbonate blend

    OpenAIRE

    Gong, Pengjian; Ohshima, Masahiro

    2014-01-01

    Open microcellular foams of polyethylene terephthalate (PET)/polycarbonate (PC) blends were prepared by controlling their foaming behavior at the interface between these two polymers. Interface modification was a crucial factor in governing the foaming behavior and cell morphology of the blend foams: annealing at 280°C, i.e., conducting the transesterification reaction, generates a PET-b-PC copolymer, which lowers the interfacial tension, increases the affinity between PET and PC, and decreas...

  17. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅱ): Sound attenuation

    Institute of Scientific and Technical Information of China (English)

    LU TianJian; M.KEPETS; A.P.DOWLING

    2008-01-01

    Open-celled metal foams fabricated through metal sintering offers novel mechani-cal, thermal and acoustic properties. Previously, polymer foams were used as a means of absorbing acoustic energy. However, the structural applications of these foams are inherently limited. The metal sintering approach provides a cost-effective means for the mass-production of open-cell foams from a range of materials, in-cluding high-temperature steel alloys. The low Reynolds number fluid properties of sintered steel alloy (FeCrAIY) foams were investigated in a previous study. The static flow resistance of the foams was modeled based on s cylinder and s sphere arranged in a periodic lattice at general incidence to the flow, with the resulting predictions correlating well to measurements. The application of the flow resis-tance in an acoustic model is the primary focus of the present study. The predic-tions for the static flow resistance of the sintered foams are first used in a theo-retical model to determine the characteristic impedances, as well as the propaga-tion constants of the foams. Subsequently, the predicted acoustic performance of the foams is compared to experimental results. Finally, the design space for a simple acoustic absorber incorporating sintered foams is examined, with the ef-fects of absorber size, foam selection, and foam spacing explored.

  18. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅱ): Sound attenuation

    Institute of Scientific and Technical Information of China (English)

    M.; KEPETS; A.; P.; DOWLING2

    2008-01-01

    Open-celled metal foams fabricated through metal sintering offers novel mechani- cal, thermal and acoustic properties. Previously, polymer foams were used as a means of absorbing acoustic energy. However, the structural applications of these foams are inherently limited. The metal sintering approach provides a cost-effective means for the mass-production of open-cell foams from a range of materials, in- cluding high-temperature steel alloys. The low Reynolds number fluid properties of sintered steel alloy (FeCrAlY) foams were investigated in a previous study. The static flow resistance of the foams was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow, with the resulting predictions correlating well to measurements. The application of the flow resis- tance in an acoustic model is the primary focus of the present study. The predic- tions for the static flow resistance of the sintered foams are first used in a theo- retical model to determine the characteristic impedances, as well as the propaga- tion constants of the foams. Subsequently, the predicted acoustic performance of the foams is compared to experimental results. Finally, the design space for a simple acoustic absorber incorporating sintered foams is examined, with the ef- fects of absorber size, foam selection, and foam spacing explored.

  19. Numerical Modeling of the Compression Process of Elastic Open-cell Foams

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The random models of open-cell foams that can reflect the actual cell geometrical properties are constructed with the Voronoi technique. The compression process of elastic open-cell foams is simulated with the nonlinear calculation module of finite element analysis program. In order to get the general results applicable to this kind of materials, the dimensionless compressive stress is used and the stress-strain curves of foam models with different geometrical properties are obtained. Then, the influences of open-cell geometrical properties, including the shape of strut cross section, relative density and cell shape irregularity, on the compressive nonlinear mechanical performance are analyzed. In addition, the numerical results are compared with the predicted results of cubic staggering model. Numerical results indicate that the simulated results reflect the compressive process of foams quite well and the geometrical properties of cell have significant influences on the nonlinear mechanical behavior of foams.

  20. Dynamic length-scale characterization and nonequilibrium statistical mechanics of transport in open-cell foams.

    Science.gov (United States)

    Brosten, Tyler R; Codd, Sarah L; Maier, Robert S; Seymour, Joseph D

    2009-11-20

    Nuclear magnetic resonance measurements of scale dependent dynamics in a random solid open-cell foam reveal a characteristic length scale for transport processes in this novel type of porous medium. These measurements and lattice Boltzmann simulations for a model foam structure indicate dynamical behavior analogous to lower porosity consolidated granular porous media, despite extremely high porosity in solid cellular foams. Scaling by the measured characteristic length collapses data for different foam structures as well as consolidated granular media. The nonequilibrium statistical mechanics theory of preasymptotic dispersion, developed for hierarchical porous media, is shown to model the hydrodynamic dispersive transport in a foam structure.

  1. Superhydrophobic and oleophilic open-cell foams from fibrillar blends of polypropylene and polytetrafluoroethylene.

    Science.gov (United States)

    Rizvi, Ali; Chu, Raymond K M; Lee, Jung H; Park, Chul B

    2014-12-10

    Effective removal of oils from water is of global significance for environmental protection. In this study, we investigate the hydrophobicity and oleophilicity of open-cell polymer foams prepared in a continuous and scalable extrusion process. The material used to prepare the open-cell foams is a fibrillar blend of polypropylene (PP) and polytetrafluoroethylene (PTFE). Scanning electron microscopy (SEM) images of the morphology of the PP/PTFE fibrillar blend reveal that the PTFE has a fibrillar morphology in the PP matrix. SEM micrograph of the extruded foam shows the formation of an interconnected open-cell structure. Using nitrogen pycnometry, the open-cell content is estimated to be 97.7%. A typical bulk density of the open-cell foam is measured to be about 0.07 g cm(-3) corresponding to a void fraction of 92%. Thus, a large three-dimensional space is made available for oil storage. A drop of water on the cross-section of the extruded open-cell foam forms a contact angle of 160° suggesting that the open-cell foam exhibits superhydrophobicity. The open-cell foam can selectively absorb various petroleum products, such as octane, gasoline, diesel, kerosene, light crude oil, and heavy crude oil from water and the uptake capacities range from about 5 to 24 g g(-1). The uptake kinetics can be enhanced by exposing the open-cell foam to high intensity ultrasound which increases the surface porosity of the thin, impervious, foam "skin" layer. The reusability of the foam can be improved by using a matrix polymer which demonstrates superior elastic properties and prevents the foams from undergoing a large permanent deformation upon compression to "squeeze out" the oil. For example, when the PP homopolymer matrix is replaced with a PP random copolymer, the permanent deformation for 10 compressive cycles is reduced from about 30% to 10%. To the best of our knowledge, these PP-based open-cell foams outperform PP-based absorbents conventionally used for oil-spill cleanup

  2. Compressive properties of open-cell ceramic foams

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-yan; FU Yi-ming; ZENG Xiao-ming

    2006-01-01

    The compressive experiments of two kinds of ceramic foams were completed. The results show that the behavior of ceramic foams made by organic filling method is anisotropic. The stress-strain responses of ceramic foams made by sponge-replication show isotropy and strain rate dependence. The struts brittle breaking of net structure of this ceramic foam arises at the weakest defects of framework or at the part of framework,which causes the initiation and expanding of cracks. The compressive strength of ceramic foam is dependent on the strut size and relative density of foams.

  3. Characterization of compressive and short beam shear strength of bamboo opened cell foam core sandwich composites

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Paryanto Dwi, E-mail: paryanto-ds@yahoo.com; Sugiman,; Saputra, Yudhi [Department of Mechanical Engineering, Faculty of Engineering, University of Mataram, Mataram, West Nusa Tenggara (Indonesia)

    2016-03-29

    The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.

  4. Characterization of compressive and short beam shear strength of bamboo opened cell foam core sandwich composites

    Science.gov (United States)

    Setyawan, Paryanto Dwi; Sugiman, Saputra, Yudhi

    2016-03-01

    The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.

  5. a Vibrational Model of Open Celled Polyurethane Foam Automotive Seat Cushions

    Science.gov (United States)

    Patten, W. N.; Sha, S.; Mo, C.

    1998-10-01

    A mechanistic model of a seat cushion is developed. The work relates the kinematic motion of the seat to the geometric and constitutive properties of the cellular foam used in the seat. The model includes the influence of pneumatic damping caused by friction between the gas within the open-celled foam and matrix polymer. A continuous shape function is introduced to characterize the piecewise continuous stress-strain characteristic of flexible open-celled foam. After some simplification, a non-linear dynamic automotive seat cushion model is derived, which relies explicitly on the constitutive properties of polyurethane foams and on the geometry of the seat cushion. Experimental and analytical models of the two automotive seats are compared to verify the model. The comparisons indicate that the new model is able to predict the dynamic performance of an automotive seat cushion with fidelity.

  6. Simulation of the densification of real open-celled foam microstructures

    Science.gov (United States)

    Brydon, A. D.; Bardenhagen, S. G.; Miller, E. A.; Seidler, G. T.

    2005-12-01

    Ubiquitous in nature and finding applications in engineering systems, cellular solids are an increasingly important class of materials. Foams are an important subclass of cellular solids with applications as packing materials and energy absorbers due to their unique properties. A better understanding of foam mechanical properties and their dependence on microstructural details would facilitate manufacture of tailored materials and development of constitutive models for their bulk response. Numerical simulation of these materials, while offering great promise toward furthering understanding, has also served to convincingly demonstrate the inherent complexity and associated modeling challenges. The large range of deformations which foams are subjected to in routine engineering applications is a fundamental source of complication in modeling the details of foam deformation on the scale of foam struts. It requires accurate handling of large material deformations and complex contact mechanics, both well established numerical challenges. A further complication is the replication of complex foam microstructure geometry in numerical simulations. Here various advantages of certain particle methods, in particular their compatibility with the determination of three-dimensional geometry via X-ray microtomography, are exploited to simulate the compression of "real" foam microstructures into densification. With attention paid to representative volume element size, predictions are made regarding bulk response, dynamic effects, and deformed microstructural character, for real polymeric, open-cell foams. These predictions include a negative Poisson's ratio in the stress plateau, and increased difficulty in removing residual porosity during densification.

  7. Compressive Properties of Open-Cell Al Hybrid Foams at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Jiaan Liu

    2017-01-01

    Full Text Available Hybrid Ni/Al foams were fabricated by depositing electroless Ni–P (EN coatings on open-cell Al foam substrate to obtain enhanced mechanical properties. The microstructure, chemical components and phases of the hybrid foams were observed and analyzed by scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDS and X-ray diffraction (XRD, respectively. The mechanical properties of the foams were studied by compressive tests at different temperatures. The experiment results show that the coating is mainly composed of Ni and P elements. There was neither defect at the interface nor crack in the coatings, indicating that the EN coatings had fine adhesion to the Al substrate. The compressive strengths and energy absorption capacities of the as-received foam and hybrid foams decrease with the increasing testing temperatures, but the hybrid foams exhibit a lower decrement rate than the as-received foam. This might be attributed to the different failure mechanisms at different testing temperatures, which is conformed by fractography observation.

  8. Different arrangements of simplified models to predict effective thermal conductivity of open-cell foams

    Science.gov (United States)

    Kumar, Prashant; Topin, Frédéric

    2017-08-01

    It is often desirable to predict the effective thermal conductivity (ETC) of a homogenous material like open-cell foams based on its composition, particularly when variations in composition are expected. A combination of five fundamental simplified thermal conductivity bounds and models (series, parallel, Hashin-Shtrikman, effective medium theory, and reciprocity models) is proposed to predict ETC of open-cell foams. Usually, these models use a parameter as the weighted mean to account the proportion of each bound arranged in arithmetic and geometric schemes. Based on ETC data obtained on numerous virtual Kelvin-like foam samples, the dependence of this parameter has been deduced as a function of morphology and phase thermal conductivity ratio. Various effective thermal conductivity correlations are derived based on material properties and foam structure. This is valid for open-cell foams filled with any arbitrary working fluid over a solid conductivity of materials range (λs /λf = 10-30,000) and over a wide range of porosity (0.60 < ɛo < 0.95). Arrangement of series and parallel models together using the simplest models for both, arithmetic and geometric schemes, is found to predict excellent results among all the generic combinations.

  9. Different arrangements of simplified models to predict effective thermal conductivity of open-cell foams

    Science.gov (United States)

    Kumar, Prashant; Topin, Frédéric

    2017-02-01

    It is often desirable to predict the effective thermal conductivity (ETC) of a homogenous material like open-cell foams based on its composition, particularly when variations in composition are expected. A combination of five fundamental simplified thermal conductivity bounds and models (series, parallel, Hashin-Shtrikman, effective medium theory, and reciprocity models) is proposed to predict ETC of open-cell foams. Usually, these models use a parameter as the weighted mean to account the proportion of each bound arranged in arithmetic and geometric schemes. Based on ETC data obtained on numerous virtual Kelvin-like foam samples, the dependence of this parameter has been deduced as a function of morphology and phase thermal conductivity ratio. Various effective thermal conductivity correlations are derived based on material properties and foam structure. This is valid for open-cell foams filled with any arbitrary working fluid over a solid conductivity of materials range (λs /λf = 10-30,000) and over a wide range of porosity (0.60 < &epsilono < 0.95). Arrangement of series and parallel models together using the simplest models for both, arithmetic and geometric schemes, is found to predict excellent results among all the generic combinations.

  10. Preparation of big size open-cell aluminum foam board using infiltration casting

    Institute of Scientific and Technical Information of China (English)

    Wang Lucai; Chen Yuyong; Wang Fang; Wu Jianguo; You Xiaohong

    2008-01-01

    This paper presents an infiltration casting technique for manufacturing big size open-cell aluminum foam boards. The principle and key technologies of infiltration casting are also analyzed. Based on the previous practice of the small size aluminum foam production, the die for preparing big size aluminum foam boards is designed and manufactured. The experiments on aluminum boards of 300 mm×300 mm×(20-75) mm, with the pore size ranging from 1.0 to 3.2 mm and average porosity of 60%, have been performed. The experimental results show that a reliable infiltration process depends critically on the pouring temperature of the molten AI-alloy, the preheated temperature of the mould and salt particles and vacuum. Current research explores the possibility of large-scale manufacturing and application of the aluminum foams.

  11. STATISTICAL ANALYSIS OF THE LOCAL STRUT THICKNESS OF OPEN CELL FOAMS

    Directory of Open Access Journals (Sweden)

    André Liebscher

    2013-03-01

    Full Text Available Open cell foams are formed by an interconnected network of struts whose thickness varies locally. These variations were shown to have an impact on the elastic and thermal properties of the foam. In this paper we quantify the local strut thickness by means of micro computed tomography (µCT imaging. We introduce a skeletonization based topological decomposition of the foam structure into its vertices and struts. This allows to estimate the thickness of individual strut segments by the Euclidean distance transform, where an appropriate correction for struts with nonspherical cross-sectional shape is applied. Conflating these estimates based on the strut lengths results in a strut thickness profile for the entire foam. Polynomial models for the strut thickness profile are investigated by means of a regression analysis.

  12. The microstructural origin of strain hardening in two-dimensional open-cell metal foams

    NARCIS (Netherlands)

    Mangipudi, K. R.; van Buuren, S. W.; Onck, P. R.

    2010-01-01

    This paper aims at elucidating the microstructural origin of strain hardening in open-cell metal foams. We have developed a multiscale model that allows to study the development of plasticity at two length scales: (i) the development of plastic zones inside individual struts (microscopic scale) and

  13. MECHANICAL STRENGTH ENHANCEMENT OF OPEN-CELL ALUMINA FOAMS USING OPTIMUM CONCENTRATION OF DEFLOCCULANT

    Directory of Open Access Journals (Sweden)

    A. Hadi

    2015-06-01

    Full Text Available Open-cell alumina foams were prepared using the appropriate alumina slurry and polyurethane sponge with linear pore density of approximately 14 pores per inch (ppi as a template by the replica method. The rheological studies showed that the optimum solid content for the slurries without deflocculants was 60 wt. %. In order to increase the slurry solid content, Tiron (1,2-dihydroxy-3,5-benzene disulfonic acid disodium salt was used as dispersant. To determine the optimum concentration of dispersant, the viscosity curves of alumina slurries containing different values of Tiron from 0 to 1.2 wt. % (based on dry material weight were studied. The optimum concentration of Tiron obtained for lowest viscosity was 0.8 wt. %. Thus, the solid content in the slurry could be increased from 60 to 66 wt. %. The effect of increase in the slurry solid content and the way it affects the foam structure and the mechanical strength were investigated. Microstructural observations of the foams show a significant reduction in macroscopic and microscopic defects in the foam struts when the slurry solid content is increased. Total porosity of the produced alumina foams prepared using slurries containing 60 and 66 wt. % solid are 83.3 and 80.4 %, respectively, while the compressive strength of the foams has increased from 1.33 to 3.24 MPa.

  14. Thermal and mechanical improvement of aluminum open-cells foams through electrodeposition of copper and graphene

    Directory of Open Access Journals (Sweden)

    Simoncini Alessandro

    2016-01-01

    Full Text Available Thanks to its planar structure, graphene is characterized by unique properties, such as excellent chemical inactivity, high electrical and thermal conductivity, high optical transparency, extraordinary flexibility and high mechanical resistance, which make it suitable in a very wide range of applications. This paper details the state of the art in graphene coating applied to aluminum open-cells foams for the improvement of their mechanical and thermal behavior. Metallic foams are highly porous materials with extremely high convective heat transfer coefficients, thanks to their complex structure of three-dimensional open-cells. Graphene nanoplatelets have been used to improve thermal conductivity of aluminum foams, to make them better suitable during heat transfer in transient state. Also, an improvement of mechanical resistance has been observed. Before electrodeposition, all the samples have been subjected to sandblasting process, to eliminate the oxide layer on the surface, enabling a better adhesion of the coating. Different nanoparticles of graphene have been used. The experimental findings revealed a higher thermal conductivity for aluminum open cells foams electroplated with graphene. Considered the relatively low process costs and the improvements obtainable, these materials are very promising in many technological fields. The topics covered include surface modification, electrochemical plating, thermo-graphic analysis.

  15. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅰ): Static flow resistance

    Institute of Scientific and Technical Information of China (English)

    LU TianJian; M.KEPETS; A.P.DOWLING

    2008-01-01

    Open celled metal foams fabricated through the route of metal sintering are a new class of material that offers novel mechanical and acoustic properties. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys. The mechanical properties of open-celled steel alloy (FeCrAIY) foams have been characterized in previous studies, with focus placed on the influence of processing defects on stiffness and strength. In this work, the low-Reynolds number fluid properties of FeCrAIY foams were investigated both theoretically and experimen-tally. Specifically, the static flow resistance of the sintered foams important for heat transfer, filtration and sound absorption was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow. Experimental measurements were subsequently carried out to validate theoretical predictions, with good agreement achieved.

  16. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    Science.gov (United States)

    Ryan, Shannon; Christiansen, Eric; Lear, Dana

    2009-01-01

    Metallic foams are a relatively new class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic properties. Although incompletely characterized, they offer comparable mechanical performance to traditional spacecraft structural materials (i.e. honeycomb sandwich panels) without detrimental through-thickness channeling cells. There are two competing types of metallic foams: open cell and closed cell. Open cell foams are considered the more promising technology due to their lower weight and higher degree of homogeneity. Leading micrometeoroid and orbital debris shields (MMOD) incorporate thin plates separated by a void space (i.e. Whipple shield). Inclusion of intermediate fabric layers, or multiple bumper plates have led to significant performance enhancements, yet these shields require additional non-ballistic mass for installation (fasteners, supports, etc.) that can consume up to 35% of the total shield weight [1]. Structural panels, such as open cell foam core sandwich panels, that are also capable of providing sufficient MMOD protection, represent a significant potential for increased efficiency in hypervelocity impact shielding from a systems perspective through a reduction in required non-ballistic mass. In this paper, the results of an extensive impact test program on aluminum foam core sandwich panels are reported. The effect of pore density, and core thickness on shielding performance have been evaluated over impact velocities ranging from 2.2 - 9.3 km/s at various angles. A number of additional tests on alternate sandwich panel configurations of comparable-weight have also been performed, including aluminum honeycomb sandwich panels (see Figure 1), Nomex honeycomb core sandwich panels, and 3D aluminum honeycomb sandwich panels. A total of 70 hypervelocity impact tests are reported, from which an empirical ballistic limit equation (BLE) has been derived. The BLE is in the standard form suitable for implementation in

  17. Design of Mechanical Properties of Open-Cell Porous Materials Based on μCT Study of Commercial Foams

    Directory of Open Access Journals (Sweden)

    Skibinski Jakub

    2015-01-01

    Full Text Available In the present paper numerical design of mechanical properties of open-cell porous materials is addressed. A detailed knowledge of mechanisms and parameters determining mechanical properties (i.e. Young’s Modulus, Poisson’s Ratio of foams is essential for applications such as energy absorbers or lightweight construction materials. The foam structures were designed using procedure based on Laguerre-Voronoi tessellations (LVT with micro-computed tomography of commercial foams used as reference. Foam morphology was studied on post-processed computed tomography images and the parameters of LVT structures were compared with commercial materials. Subsequently finite element method (FEM calculations were performed on both types of structures to validate the LVT design algorithm. The results show that the described design procedure can be successfully used for modeling mechanical properties of open-cell foam structures.

  18. Analysis and simulation for tensile behavior of anisotropic open-cell elastic foams

    Institute of Scientific and Technical Information of China (English)

    卢子兴; 刘强; 陈鑫

    2014-01-01

    Based on the elongated Kelvin model, a simplified periodic structural cell is obtained to investigate the tensile behavior of anisotropic open-cell elastic foams due to Kelvin model’s periodicity and symmetry in the whole space. The half-strut element and elastic deflection theory are used to analyze the tensile response as done in the previous studies. This study produces theoretical expressions for the tensile stress-strain curve in the rise and transverse directions. In addition, the theoretical results are examined with finite element simulation using an existing formula. The results indicate that the theoretical analysis agrees with the finite element simulation when the strain is not too high, and the present model is better. At the same time, the anisotropy ratio has a significant effect on the mechanical properties of foams. As the anisotropy ratio increases, the tensile stress is improved in the rising direction but drops in the transverse direction under the same strain.

  19. Influence of pore and strut shape on open cell metal foam bulk properties

    Science.gov (United States)

    Kumar, Prashant; Hugo, Jean-Michel; Topin, Frederic; Vicente, Jerome

    2012-05-01

    The thermo-physical behavior of open-celled metal foams depends on their microscopic structure. An ideal periodic isotropic structure of tetrakaidecahedron shape i.e. Kelvin cell is studied. We have proposed an analytical model in order to obtain geometrical parameters correctly as they have substantial influence on thermal and hydraulic phenomena, where strut geometry is of prime importance. Various relationships between different geometrical parameters and porosities are presented. Consequently, empirical correlations are proposed to determine permeability and inertia coefficient using Ergun like model for computing pressure drop.

  20. Effective Thermal Conductivity of Open Cell Polyurethane Foam Based on the Fractal Theory

    Directory of Open Access Journals (Sweden)

    Kan Ankang

    2013-01-01

    Full Text Available Based on the fractal theory, the geometric structure inside an open cell polyurethane foam, which is widely used as adiabatic material, is illustrated. A simplified cell fractal model is created. In the model, the method of calculating the equivalent thermal conductivity of the porous foam is described and the fractal dimension is calculated. The mathematical formulas for the fractal equivalent thermal conductivity combined with gas and solid phase, for heat radiation equivalent thermal conductivity and for the total thermal conductivity, are deduced. However, the total effective heat flux is the summation of the heat conduction by the solid phase and the gas in pores, the radiation, and the convection between gas and solid phase. Fractal mathematical equation of effective thermal conductivity is derived with fractal dimension and vacancy porosity in the cell body. The calculated results have good agreement with the experimental data, and the difference is less than 5%. The main influencing factors are summarized. The research work is useful for the enhancement of adiabatic performance of foam materials and development of new materials.

  1. Ceramic-like open-celled geopolymer foam as a porous substrate for water treatment catalyst

    Science.gov (United States)

    Kovářík, T.; Křenek, T.; Pola, M.; Rieger, D.; Kadlec, J.; Franče, P.

    2017-02-01

    This paper presents results from experimental study on microstructural and mechanical properties of geopolymer-based foam filters. The process for making porous ceramic-like geopolymer body was experimentally established, consists of (a) geopolymer paste synthesis, (b) ceramic filler incorporation, (c) coating of open-celled polyurethane foam with geopolymer mixture, (d) rapid setting procedure, (e) thermal treatment. Geopolymer paste was based on potassium silicate solution n(SiO2)/n(K2O)=1.6 and powder mixture of calcined kaolin and precipitated silica. Various types of ceramic granular filler (alumina, calcined schistous clay and cordierite) were tested in relation to aggregate gradation design and particle size distribution. The small amplitude oscillatory rheometry in strain controlled regime 0.01% with angular frequency 10 rad/s was applied for determination of rheology behavior of prepared mixtures. Thermal treatment conditions were applied in the temperature range 1100 – 1300 °C. The developed porous ceramic-like foam effectively served as a substrate for highly active nanoparticles of selected Fe+2 spinels. Such new-type of nanocomposite was tested as a heterogeneous catalyst for technological process of advanced oxidative degradation of resistive antibiotics occurring in waste waters.

  2. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    Science.gov (United States)

    Ryan, S.; Ordonez, E.; Christiansen, E. L.; Lear, D. M.

    2010-01-01

    Open cell metallic foam core sandwich panel structures are of interest for application in spacecraft micrometeoroid and orbital debris shields due to their novel form and advantageous structural and thermal performance. Repeated shocking as a result of secondary impacts upon individual foam ligaments during the penetration process acts to raise the thermal state of impacting projectiles ; resulting in fragmentation, melting, and vaporization at lower velocities than with traditional shielding configurations (e.g. Whipple shield). In order to characterize the protective capability of these structures, an extensive experimental campaign was performed by the Johnson Space Center Hypervelocity Impact Technology Facility, the results of which are reported in this paper. Although not capable of competing against the protection levels achievable with leading heavy shields in use on modern high-risk vehicles (i.e. International Space Station modules), metallic foam core sandwich panels are shown to provide a substantial improvement over comparable structural panels and traditional low weight shielding alternatives such as honeycomb sandwich panels and metallic Whipple shields. A ballistic limit equation, generalized in terms of panel geometry, is derived and presented in a form suitable for application in risk assessment codes.

  3. Functional Characterization of Shape Memory CuZnAl Open-Cell Foams by Molten Metal Infiltration

    Science.gov (United States)

    Arnaboldi, S.; Bassani, P.; Passaretti, F.; Redaelli, A.; Tuissi, A.

    2011-07-01

    In the recent years, the research for novel materials with tailored mechanical properties, as well as functional properties, has encouraged the study of porous and cellular materials. Our previous work proposed and reported about the possibility to manufacture open-cell metal foams of CuZnAl shape memory alloy by liquid infiltration in a leachable bed of silica-gel particles. This innovative methodology is based on cheap commercial consumables and a simple technology, focusing on intermediate-density low-cost foams with interesting cost/benefits ratio. Microstructural analyses on foamed specimens showed uniform microstructure of ligaments and a very regular and well reproducible open-cell morphology. Moreover, calorimetric analysis detected a thermo-elastic martensitic transformation in the foamed material. In this study, a CuZnAl shape memory alloy was considered and tested to clarify possible effects of the foaming process on the functional properties of the material. Morphological, calorimetric, and thermo-mechanical analyses were carried out. The results show that it is possible to produce metal foams of CuZnAl shape memory alloy with different functional properties and able to recover mono-axial compressive strains up to 3%.

  4. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅰ): Static flow resistance

    Institute of Scientific and Technical Information of China (English)

    M.; KEPETS; A.; P.; DOWLING

    2008-01-01

    Open celled metal foams fabricated through the route of metal sintering are a new class of material that offers novel mechanical and acoustic properties. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys. The mechanical properties of open-celled steel alloy (FeCrAlY) foams have been characterized in previous studies, with focus placed on the influence of processing defects on stiffness and strength. In this work, the low-Reynolds number fluid properties of FeCrAlY foams were investigated both theoretically and experimen- tally. Specifically, the static flow resistance of the sintered foams important for heat transfer, filtration and sound absorption was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow. Experimental measurements were subsequently carried out to validate theoretical predictions, with good agreement achieved.

  5. A simple expression for the normal spectral emittance of open-cell foams composed of optically thick and smooth struts

    Science.gov (United States)

    Guévelou, Simon; Rousseau, Benoit; Domingues, Gilberto; Vicente, Jérôme

    2017-03-01

    A set of 96 open-cell foams with growing porosities (0.35-0.95) and growing pore nominal diameters (0.4-2.6 mm) was artificially generated to firmly connect their normal spectral emittances to their textural features. This work is strictly focused on foams that are composed of opaque struts with optically smooth surfaces. To compute the normal spectral emittances, a Monte Carlo Ray Tracing code was carefully used through an indirect method based on Kirchhoff's laws. The Monte Carlo Ray Tracing code considers the complex refractive index of the solid phase constituting the struts foams. Particular attention is therefore paid to performing the calculation with absorption indices (0.5-8) that preserve the opacity of each strut. From a thorough analysis of the ray transport within all the foams, where the Representative Elementary Volumes used for computing the homogenized radiative properties were known beforehand, a general and simple law is established that connects the normal spectral emittance, on the one hand, and the open porosity and the complex index of refraction, on the other hand. In the field of the thermal conversion of solar energy, for example, the new law gives relevant insight on the radiative performance of highly porous foams that are virtually coated with materials that are known for possessing an undeniable spectral selectivity when they are shaped as dense samples.

  6. Incorporation of the Pore Size Variation to Modeling of the Elastic Behavior of Metallic Open-Cell Foams

    Directory of Open Access Journals (Sweden)

    Ćwieka K.

    2017-03-01

    Full Text Available In the present paper we present the approach for modeling of the elastic behavior of open-cell metallic foams concerning non-uniform pore size distribution. This approach combines design of foam structures and numerical simulations of compression tests using finite element method (FEM. In the design stage, Laguerre-Voronoi tessellations (LVT were performed on several sets of packed spheres with defined variation of radii, bringing about a set of foam structures with porosity ranging from 74 to 98% and different pore size variation quantified by the coefficient of pore volume variation, CV(V, from 0.5 to 2.1. Each structure was numerically subjected to uni-axial compression test along three directions within the elastic region. Basing on the numerical response, the effective Young’s modulus, Eeff, was calculated for each structure. It is shown that the Eeff is not only dependent on the porosity but also on the pore size variation.

  7. Analysis and simulation of high strain compression of anisotropic open-cell elastic foams

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    By elongating the regular Kelvin model in one direction and keeping unchanged in the other two directions,the anisotropic model was constructed.Then,the simplified periodic structural cell was obtained according to the periodicity and symmetry of the model in the whole space.Using the half-strut element and elastic deflection theory to analyze the mechanical behavior as were adopted in the previous studies,this paper obtained the theoretical expressions for the compressive stress and strain as well as the corresponding curves in the rise and transverse directions.In addition,the theoretical results were examined by the finite element simulation.Results indicated that the theoretical analysis was very close to the finite element simulation when the strain was not too high,which confirmed the validity of theoretical analysis.At the same time,the anisotropy was shown to have a significant effect on the mechanical properties of open-cell foams.As the anisotropy ratio increased,the compressive stress was improved in the rise direction but dropped in the transverse direction under the same strain.

  8. SORPTION OF Ga (III ON FLEXIBLE OPEN CELL POLYURETHANE FOAM OF POLYETHER TYPE IMPREGNATED WITH TRI-N-BUTHYL PHOSPATE

    Directory of Open Access Journals (Sweden)

    Lavinia Tofan

    2007-06-01

    Full Text Available The obtained results concerning the Ga (III ion retention on flexible open cell polyurethane foam of polyether type pretreated with tri-n-butyl phosphate are presented. The influence of solution acidity, phases contact time, Ga (III concentration and solution temperature have been investigated. The parameters of Ga (III batch sorption have been optimized. On the basis of Langmuir isotherms, the sorption constants and the thermodynamic parameters, ∆G, ∆Η and ∆S have been calculated.

  9. A novel technique for making open-cell AI203-ZrO2 ceramic foam with plant seed template

    Institute of Scientific and Technical Information of China (English)

    Yu Jingyuan; Li Qiang; Tang Ji; Sun Xudong; Li Xiaodong

    2010-01-01

    The aim of the present research is to provide a technique for preparing open-cell AI203-ZrO2 ceramic foams with uniform cell size. This technique used plant seeds to array templates and centrifugal slip casting to obtain cell struts with high packing density. Aqueous Al2O3-ZrO2 slurries with up to 50 vol.% solid contents were prepared and the rheological characteristic of the slurries was investigated. Consolidation was performed at an acceleration of 2,860 g for 60 rain. The effect of the characteristic of plant seeds on the drying behavior of Al2O3- ZrO2 green compact was analyzed. The effects of the solid contents of slurries on segregation phenomena ofAl2O3 and ZrO2 particles and green compact uniformity were investigated. The compressive stress-strain curve and deformation behavior of Al2O3-ZrO2 ceramic foams prepared using plant seed template were analyzed. The results showed segregation phenomenon is negligible for highly stable slurry with 50 vol.% solid loading. The prepared cell struts of Al2O3-ZrO2 foams have high green density (61.9% TD), sintered density (99.1% TD) and homogeneous microstructure. When sintered at 1,550 ℃ for 2 h, the cell size of Al2O3-ZrO2 foam is approximately uniform and the diameter is about 1.1 mm. The porosity and compressive strength of sintered products is 66.2% and 5.86 MPa, respectively.

  10. Casting Protocols for the Production of Open Cell Aluminum Foams by the Replication Technique and the Effect on Porosity

    Science.gov (United States)

    Elizondo Luna, Erardo M.; Barari, Farzad; Woolley, Robert; Goodall, Russell

    2014-01-01

    Metal foams are interesting materials from both a fundamental understanding and practical applications point of view. Uses have been proposed, and in many cases validated experimentally, for light weight or impact energy absorbing structures, as high surface area heat exchangers or electrodes, as implants to the body, and many more. Although great progress has been made in understanding their structure-properties relationships, the large number of different processing techniques, each producing material with different characteristics and structure, means that understanding of the individual effects of all aspects of structure is not complete. The replication process, where molten metal is infiltrated between grains of a removable preform material, allows a markedly high degree of control and has been used to good effect to elucidate some of these relationships. Nevertheless, the process has many steps that are dependent on individual “know-how”, and this paper aims to provide a detailed description of all stages of one embodiment of this processing method, using materials and equipment that would be relatively easy to set up in a research environment. The goal of this protocol and its variants is to produce metal foams in an effective and simple way, giving the possibility to tailor the outcome of the samples by modifying certain steps within the process. By following this, open cell aluminum foams with pore sizes of 1–2.36 mm diameter and 61% to 77% porosity can be obtained. PMID:25548938

  11. Dual-energy X-ray micro-CT imaging of hybrid Ni/Al open-cell foam

    Science.gov (United States)

    Fíla, T.; Kumpová, I.; Koudelka, P.; Zlámal, P.; Vavřík, D.; Jiroušek, O.; Jung, A.

    2016-01-01

    In this paper, we employ dual-energy X-ray microfocus tomography (DECT) measurement to develop high-resolution finite element (FE) models that can be used for the numerical assessment of the deformation behaviour of hybrid Ni/Al foam subjected to both quasi-static and dynamic compressive loading. Cubic samples of hybrid Ni/Al open-cell foam with an edge length of [15]mm were investigated by the DECT measurement. The material was prepared using AlSi7Mg0.3 aluminium foam with a mean pore size of [0.85]mm, coated with nanocrystalline nickel (crystallite size of approx. [50]nm) to form a surface layer with a theoretical thickness of [0.075]mm. CT imaging was carried out using state-of-the-art DSCT/DECT X-ray scanner developed at Centre of Excellence Telč. The device consists of a modular orthogonal assembly of two tube-detector imaging pairs, with an independent geometry setting and shared rotational stage mounted on a complex 16-axis CNC positioning system to enable unprecedented measurement variability for highly-detailed tomographical measurements. A sample of the metal foam was simultaneously irradiated using an XWT-240-SE reflection type X-ray tube and an XWT-160-TCHR transmission type X-ray tube. An enhanced dual-source sampling strategy was used for data acquisition. X-ray images were taken using XRD1622 large area GOS scintillator flat panel detectors with an active area of [410 × 410]mm and resolution [2048 × 2048]pixels. Tomographic scanning was performed in 1,200 projections with a 0.3 degree angular step to improve the accuracy of the generated models due to the very complex microstructure and high attenuation of the investigated material. Reconstructed data was processed using a dual-energy algorithm, and was used for the development of a 3D model and voxel model of the foam. The selected parameters of the models were compared with nominal parameters of the actual foam and showed good correlation.

  12. Fabrication and electromagnetic interference shielding performance of open-cell foam of a Cu–Ni alloy integrated with CNTs

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Keju; Zhao, Huihui; Zhang, Jun; Chen, Jia; Dai, Zhendong, E-mail: zddai@nuaa.edu.cn

    2014-08-30

    Highlights: • Cu–Ni alloy open-cell foam integrated with CNTs was used for EMI shielding. • The composite was prepared by electroless, electro-, and electrophoretic deposition. • The main shielding mechanism was multiple reflections and absorptions of microwaves. • The composite had a porous structure, large surface area, and inherent permeability. - Abstract: A lightweight multi-layered electromagnetic interference (EMI) shielding material made of open-cell foam of a Cu–Ni alloy integrated with carbon nanotubes (CNTs) was prepared by electroless copper plating, then nickel electroplating, and finally electrophoretic deposition of CNTs. The foamed Cu–Ni–CNT composite comprises, from inside to outside, Cu, Ni, and CNT layers. Scanning electron microscopy, energy dispersive spectroscopy, and EMI tests were employed to characterize the morphology, composition, and EMI performance of the composite, respectively. The results indicated that the shielding effectiveness (SE) of the composite increased with increasing pore density (indicated as pores per inch (PPI)) and increasing thickness. A specimen with a PPI of 110 and a 1.5-mm thickness had a maximum SE of up to 54.6 dB, and a SE as high as 47.5 dB on average in the 8–12 GHz range. Integrating the inherent superiority of Cu, Ni, and CNTs, the porous structure of the composite can attenuate the incident electromagnetic microwaves by reflecting, scattering, and absorbing them between the metallic skeleton and the CNT layer. The multiple reflections and absorptions make it difficult for the microwaves to escape from the composite before being absorbed, thereby making the composite a potential shielding material.

  13. Microstructure and calorimetric behavior of laser welded open cell foams in CuZnAl shape memory alloy

    Science.gov (United States)

    Biffi, Carlo Alberto; Previtali, Barbara; Tuissi, Ausonio

    Cellular shape memory alloys (SMAs) are very promising smart materials able to combine functional properties of the material with lightness, stiffness, and damping capacity of the cellular structure. Their processing with low modification of the material properties remains an open question. In this work, the laser weldability of CuZnAl SMA in the form of open cell foams was studied. The cellular structure was proved to be successfully welded in lap joint configuration by using a thin plate of the same alloy. Softening was seen in the welded bead in all the investigated ranges of process speed as well as a double stage heat affected zone was identified due to different microstructures; the martensitic transformation was shifted to higher temperatures and the corresponding peaks were sharper with respect to the base material due to the rapid solidification of the material. Anyways, no compositional variations were detected in the joints.

  14. Tuning the spectral emittance of α-SiC open-cell foams up to 1300 K with their macro porosity

    Directory of Open Access Journals (Sweden)

    B. Rousseau

    2016-06-01

    Full Text Available A simple and robust analytical model is used to finely predict the spectral emittance under air up to 1300 K of α-SiC open-cell foams constituted of optically thick struts. The model integrates both the chemical composition and the macro-porosity and is valid only if foams have volumes higher than their Representative Elementary Volumes required for determining their emittance. Infrared emission spectroscopy carried out on a doped silicon carbide single crystal associated to homemade numerical tools based on 3D meshed images (Monte Carlo Ray Tracing code, foam generator make possible to understand the exact role of the cell network in emittance. Finally, one can tune the spectral emittance of α-SiC foams up to 1300 K by simply changing their porosity.

  15. Tuning the spectral emittance of α-SiC open-cell foams up to 1300 K with their macro porosity

    Science.gov (United States)

    Rousseau, B.; Guevelou, S.; Mekeze-Monthe, A.; Vicente, J.; Del Campo, L.; De Sousa Meneses, D.; Echegut, P.; Caliot, C.; Flamant, G.

    2016-06-01

    A simple and robust analytical model is used to finely predict the spectral emittance under air up to 1300 K of α-SiC open-cell foams constituted of optically thick struts. The model integrates both the chemical composition and the macro-porosity and is valid only if foams have volumes higher than their Representative Elementary Volumes required for determining their emittance. Infrared emission spectroscopy carried out on a doped silicon carbide single crystal associated to homemade numerical tools based on 3D meshed images (Monte Carlo Ray Tracing code, foam generator) make possible to understand the exact role of the cell network in emittance. Finally, one can tune the spectral emittance of α-SiC foams up to 1300 K by simply changing their porosity.

  16. Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

    Science.gov (United States)

    Pang, Q.; Hu, Z. L.; Wu, G. H.

    2016-10-01

    Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

  17. Inverse estimation of the elastic and anelastic properties of the porous frame of anisotropic open-cell foams.

    Science.gov (United States)

    Cuenca, Jacques; Göransson, Peter

    2012-08-01

    This paper presents a method for simultaneously identifying both the elastic and anelastic properties of the porous frame of anisotropic open-cell foams. The approach is based on an inverse estimation procedure of the complex stiffness matrix of the frame by performing a model fit of a set of transfer functions of a sample of material subjected to compression excitation in vacuo. The material elastic properties are assumed to have orthotropic symmetry and the anelastic properties are described using a fractional-derivative model within the framework of an augmented Hooke's law. The inverse estimation problem is formulated as a numerical optimization procedure and solved using the globally convergent method of moving asymptotes. To show the feasibility of the approach a numerically generated target material is used here as a benchmark. It is shown that the method provides the full frequency-dependent orthotropic complex stiffness matrix within a reasonable degree of accuracy.

  18. Demonstration of neutron detection utilizing open cell foam and noble gas scintillation

    Energy Technology Data Exchange (ETDEWEB)

    Lavelle, C. M., E-mail: christopher.lavelle@jhuapl.edu; Miller, E. C. [The Johns Hopkins University Applied Physics Laboratory, Asymmetric Operations Department, Laurel, Maryland 20723 (United States); Coplan, M. [Institute for Physical Science and Technology, University of Maryland College Park, Maryland 20142 (United States); Thompson, Alan K.; Vest, Robert E.; Yue, A. T. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Kowler, A. L. [Department of Chemical Physics, University of Maryland, College Park, Maryland 20142 (United States); Koeth, T. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20142 (United States); Al-Sheikhly, M. [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742 (United States); Clark, Charles W. [Institute for Physical Science and Technology, University of Maryland College Park, Maryland 20142 (United States); National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899 (United States)

    2015-03-02

    We present results demonstrating neutron detection via a closely spaced converter structure coupled to low pressure noble gas scintillation instrumented by a single photo-multiplier tube (PMT). The converter is dispersed throughout the gas volume using a reticulated vitreous carbon foam coated with boron carbide (B{sub 4}C). A calibrated cold neutron beam is used to measure the neutron detection properties, using a thin film of enriched {sup 10}B as a reference standard. Monte Carlo computations of the ion energy deposition are discussed, including treatment of the foam random network. Results from this study indicate that the foam shadows a significant portion of the scintillation light from the PMT. The high scintillation yield of Xe appears to overcome the light loss, facilitating neutron detection and presenting interesting opportunities for neutron detector design.

  19. Multi-scale Modelling of Fracture in Open-Cell Metal Foams

    NARCIS (Netherlands)

    Mangipudi, K. R.; Onck, P. R.; Ganghoffer, JF; Pastrone, F

    2010-01-01

    Metal foams possess attractive mechanical properties like high stiffness to weight ratio.When used to build light-weight structures they require a good combination of strength and ductility. They are ductile under compression but rather brittle in tension with a few percent of overall strain to

  20. Unit Cell Analysis of the Superelastic Behavior of Open-Cell Tetrakaidecahedral Shape Memory Alloy Foam under Quasi-Static Loading

    Directory of Open Access Journals (Sweden)

    Guillaume Maîtrejean

    2014-01-01

    Full Text Available Cellular solid materials and, more specifically, foams are increasingly common in many industrial applications due to their attractive characteristics. The tetrakaidecahedral foam microstructure, which can be observed in many types of foams, is studied in the present work in association with shape memory alloys (SMA material. SMA foams are of particular interest as they associate both the shape memory effect and the superelasticity with the characteristics of foam. A Unit Cell Finite Element Method approach is used, an approach that allows accurate predicting of the macroscale response of the foam with a highly reduced numerical effort. The tetrakaidecahedral foam’s responses, both in the elastic and in the superelastic stages, are then extracted and compared with results from the literature. The tetrakaidecahedral geometry is found to be of particular interest when associated with SMA as it takes more advantage of the superelastic property of the material than foams with randomly distributed porosity.

  1. Washcoat Deposition of Ni- and Co-ZrO2 Low Surface Area Powders onto Ceramic Open-Cell Foams: Influence of Slurry Formulation and Rheology

    Directory of Open Access Journals (Sweden)

    Riccardo Balzarotti

    2015-12-01

    Full Text Available The effect of formulations and procedures to deposit thin active layers based on low surface area powders on complex geometry substrates (open-cell foams was experimentally assessed. An acid-free liquid medium based on water, glycerol, and polyvinyl alcohol was used for powder dispersion, while a dip-coating technique was chosen for washcoat deposition on 30 PPI ceramic open-cell foams. The rheological behavior was explained on the bases of both porosity and actual powder density. It was proved that the use of multiple dippings fulfills flexibility requirements for washcoat load management. Multiple depositions with intermediate flash drying steps at 350 °C were carried out. Washcoat loads in the 2.5 to 22 wt. % range were obtained. Pore clogging was seldom observed in a limited extent in samples with high loading (>20 wt. %. Adhesion, evaluated by means of accelerated stress test in ultrasound bath, pointed out good results of all the deposited layers.

  2. Outgassing from Open and Closed Magma Foams

    Directory of Open Access Journals (Sweden)

    Felix W. von Aulock

    2017-06-01

    Full Text Available During magma ascent, bubbles nucleate, grow, coalesce, and form a variably permeable porous network. The reorganization, failing and sealing of bubble walls may contribute to the opening and closing of the volcanic system. In this contribution we cause obsidian to nucleate and grow bubbles to high gas volume fraction at atmospheric pressure by heating samples to 950°C for different times and we image the growth through a furnace. Following the experiment, we imaged the internal pore structure of selected samples in 3D and then dissected for analysis of textures and dissolved water content remnant in the glass. We demonstrate that in these high viscosity systems, during foaming and subsequent foam-maturation, bubbles near a free surface resorb via diffusion to produce an impermeable skin of melt around a foam. The skin thickens non-linearly through time. The water concentrations at the outer and inner skin margins reflect the solubility of water in the melt at the partial pressure of water in atmospheric and water-rich bubble conditions, respectively. In this regime, mass transfer of water out of the system is diffusion limited and the sample shrinks slowly. In a second set of experiments in which we polished off the skin of the foamed samples and placed them back in the furnace to allow open system outgassing, we observe rapid sample contraction and collapse of the connected pore network under surface tension as the system efficiently outgasses. In this regime, mass transfer of water is permeability limited. We conclude that diffusion-driven skin formation can efficiently seal connectivity in foams. When rupture of melt film around gas bubbles (i.e., skin removal occurs, then rapid outgassing and consequent foam collapse modulate gas pressurization in the vesiculated magma. The mechanisms described here are relevant to the evolution of pore network heterogeneity in permeable magmas.

  3. A general methodology for inverse estimation of the elastic and anelastic properties of anisotropic open-cell porous materials—with application to a melamine foam

    Energy Technology Data Exchange (ETDEWEB)

    Cuenca, Jacques, E-mail: jcuenca@kth.se; Van der Kelen, Christophe; Göransson, Peter [Marcus Wallenberg Laboratory for Sound and Vibration Research, Royal Institute of Technology (KTH), Teknikringen 8, SE-10044 Stockholm (Sweden)

    2014-02-28

    This paper proposes an inverse estimation method for the characterisation of the elastic and anelastic properties of the frame of anisotropic open-cell foams used for sound absorption. A model of viscoelasticity based on a fractional differential constitutive equation is used, leading to an augmented Hooke's law in the frequency domain, where the elastic and anelastic phenomena appear as distinctive terms in the stiffness matrix. The parameters of the model are nine orthotropic elastic moduli, three angles of orientation of the material principal directions and three parameters governing the anelastic frequency dependence. The inverse estimation consists in numerically fitting the model on a set of transfer functions extracted from a sample of material. The setup uses a seismic-mass measurement repeated in the three directions of space and is placed in a vacuum chamber in order to remove the air from the pores of the sample. The method allows to reconstruct the full frequency-dependent complex stiffness matrix of the frame of an anisotropic open-cell foam and in particular it provides the frequency of maximum energy dissipation by viscoelastic effects. The characterisation of a melamine foam sample is performed and the relation between the fractional-derivative model and other types of parameterisations of the augmented Hooke's law is discussed.

  4. A novel technique for making open-cell Al2O3-ZrO2 ceramic foam with plant seed template

    Directory of Open Access Journals (Sweden)

    Yu Jingyuan

    2010-08-01

    Full Text Available The aim of the present research is to provide a technique for preparing open-cell Al2O3-ZrO2 ceramic foams with uniform cell size. This technique used plant seeds to array templates and centrifugal slip casting to obtain cell struts with high packing density. Aqueous Al2O3-ZrO2 slurries with up to 50 vol.% solid contents were prepared and the rheological characteristic of the slurries was investigated. Consolidation was performed at an acceleration of 2,860 g for 60 min. The effect of the characteristic of plant seeds on the drying behavior of Al2O3-ZrO2 green compact was analyzed. The effects of the solid contents of slurries on segregation phenomena of Al2O3 and ZrO2 particles and green compact uniformity were investigated. The compressive stress-strain curve and deformation behavior of Al2O3-ZrO2 ceramic foams prepared using plant seed template were analyzed. The results showed segregation phenomenon is negligible for highly stable slurry with 50 vol.% solid loading. The prepared cell struts of Al2O3-ZrO2 foams have high green density (61.9% TD, sintered density (99.1% TD and homogeneous microstructure. When sintered at 1,550 篊 for 2 h, the cell size of Al2O3-ZrO2 foam is approximately uniform and the diameter is about 1.1 mm. The porosity and compressive strength of sintered products is 66.2% and 5.86 MPa, respectively.

  5. Sound absorption property of open-pore aluminum foams

    Institute of Scientific and Technical Information of China (English)

    WANG Lu-cai; WANG Fang; WU Jian-guo; YOU Xiao-hong

    2006-01-01

    The sound absorption property of aluminum foam was studied by testing its sound absorption coefficients using standing wave tube method. The open-pore aluminum foams were prepared by infiltration process, with pore size of 0.5 mm to 3.2 mm and porosity of 54.2% to 77%. The frequency of indicted sound wave was ranging from 125 Hz to 10 kHz. The results show that the average values of sound absorption coefficients are all over 0.4 and the aluminum foam has better sound absorption property, its coefficients is influenced by frequency and pore structure, and reaches the maximum at about 1 kHz, with increasing porosity and decreasing cell diameter the sound absorption coefficient values increase.

  6. Effects of cell size on compressive properties of aluminum foam

    Institute of Scientific and Technical Information of China (English)

    CAO Xiao-qing; WANG Zhi-hua; MA Hong-wei; ZHAO Long-mao; YANG Gui-tong

    2006-01-01

    The effects of cell size on the quasi-static and dynamic compressive properties of open cell aluminum foams produced by infiltrating process were studied experimentally. The quasi-static and dynamic compressive tests were carried out on MTS 810 system and SHPB(split Hopkinson pressure bar) respectively. It is found that the elastic moduli and compressive strengths of the studied aluminum foam are not only dependent on the relative density but also dependent on the cell size of the foam under both quasi-static loading and dynamic loading. The foams studied show a significant strain rate sensitivity, the flow strength can be improved as much as 112%, and the cell size also has a sound influence on the strain rate sensitivity of the foams. The foams of middle cell size exhibit the highest elastic modulus, the highest flow strength and the most significant strain rate sensitivity.

  7. Development of a GUI Based Front End for Open Source CFD Program, OpenFOAM

    Energy Technology Data Exchange (ETDEWEB)

    Han, Samhee; Lee, Youngjin; Kim, Hyongchol; Park, Sunbyung; Kim, Hyunjik [Nuclear Safety Evaluation, Daejeon (Korea, Republic of)

    2013-05-15

    OpenFOAM is sorely lacking in user friendliness as it runs in console mode under Li nux. Run{sub F}OAM was developed to greatly simplify the task of running an OpenFOAM calculation under Windows OS. Run{sub F}OAM was written using Delphi object pascal language, and GLScene package was used for the 3D graphics. Verification of Run{sub F}OAM was carried out by performing some OpenFOAM CFD calculations provided in OpenFOAM package, and these showed that the use of Run{sub F}OAM is simple whilst providing sufficient allowances in user modifications. Run{sub F}oam, a GUI based front end program to simplify running Open Foam CFD cases, has been developed. By incorporating numerous GUI in the program, Run{sub F}oam has demonstrated that running an Open Foam case can be easily accomplished. There is a potential for further development as the Open Foam has the great advantage of being free to develop and to use. There is also a potential to couple or interface the Open Foam with the systems analysis code such as Relap5.

  8. Centrifugal slip casting for preparing open-cell Al2O3 foam%离心成形法制备开孔氧化铝泡沫

    Institute of Scientific and Technical Information of China (English)

    于景媛; 李然; 李强; 李晓东; 孙旭东

    2006-01-01

    Centrifugal slip casting in prefabricated template was used to prepare open-cell Al2O3 foams. Aqueous α- Al2O3 slurries with up to 50% solid contents (volume fraction) were prepared. The sedimentation of slurries during centrifugation was discussed with respect to the hydronamic conditions at large particle concentrations. The effect of solid contents on mass segregation was observed. Segregation phenomena were hindered for slurries with high solid loadings exceeding 50% ( volume fraction). The dried and sintered behaviors of samples were analyzed. The cell struts in green bodies had good particles packing and showed high green density ( 63.4% theory density ). After sintered at 1500 ℃, the cell struts of final products had high sintered density ( 98. 8% theory density) and homogeneous microstructure. The porosity of final products is 75.6%

  9. Brazing open cell reticulated copper foam to stainless steel tubing with vacuum furnace brazed gold/indium alloy plating

    Science.gov (United States)

    Howard, Stanley R.; Korinko, Paul S.

    2008-05-27

    A method of fabricating a heat exchanger includes brush electroplating plated layers for a brazing alloy onto a stainless steel tube in thin layers, over a nickel strike having a 1.3 .mu.m thickness. The resultant Au-18 In composition may be applied as a first layer of indium, 1.47 .mu.m thick, and a second layer of gold, 2.54 .mu.m thick. The order of plating helps control brazing erosion. Excessive amounts of brazing material are avoided by controlling the electroplating process. The reticulated copper foam rings are interference fit to the stainless steel tube, and in contact with the plated layers. The copper foam rings, the plated layers for brazing alloy, and the stainless steel tube are heated and cooled in a vacuum furnace at controlled rates, forming a bond of the copper foam rings to the stainless steel tube that improves heat transfer between the tube and the copper foam.

  10. OpenFOAM: Open source CFD in research and industry

    Directory of Open Access Journals (Sweden)

    Hrvoje Jasak

    2009-12-01

    Full Text Available The current focus of development in industrial Computational Fluid Dynamics (CFD is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in “non-traditional” areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.

  11. Study on Preparation of Polypropylene Open-cell Foam using Polymer Blend%共混法制备聚丙烯开孔泡沫材料的研究

    Institute of Scientific and Technical Information of China (English)

    曹贤武; 何丁; 伍巍; 黄益威; 周南桥

    2011-01-01

    采用高熔体强度聚丙烯(HMSPP)/线性低密度聚乙烯(LLDPE)共混的方法在自制超临界CO2动态发泡模拟机上制备了开孔性泡沫材料.研究了发泡温度和共混体系原料配比对聚丙烯开孔发泡性能的影响.结果表明:LLDPE的加入使HMSPP的结晶性能发生变化,形成分散晶区;发泡温度为140℃时,HMSPP/LLDPE共混体系质量配比为90/10的发泡样品泡孔形貌最好,而当发泡温度为130℃时,质量配比为70/30的共混体系发泡效果更好,形成明显开孔结构;同一发泡温度下,LLDPE用量对发泡效果影响很大;HMSPP/LLDPE质量配比为70/30时,发泡样品开孔率最大.%Open-cell foam was prepared from HMS-PP and LLDPE blend on a self-made dynamic foaming simulation machine. The effect of foaming temperature and HMSPP/LLDPE ratio on the performance of PP open-cell foam was investigated. The results showed that as LLDPE was added in, crystallization of HMSPP was changed and dispersed into small crystal region. When foaming temperature was at 140 ℃, the cell shape of HMSPP/LLDPE (90/10) composite was the best. When foaming temperature was at 130 ℃, foaming performance of HMSPP/LLDPE (70/30) composite was even better, and obvious open-cell structure was observed. The effect of LLDPE concentration on foaming results was significant under same foaming temperature. When ratio of HMSPP/LLDPE was 70/30, the open cell content reached the maximum.

  12. Cells on foam and fiber

    Energy Technology Data Exchange (ETDEWEB)

    Clyde, R. [Clyde Engineering, New Orleans, LA (United States)

    1996-12-31

    Cells grow on high area foam and, when a screen is put around the foam, it is made heavier so it can be fluidized. When foam is rotated in a half full RBC (rotary biological contactor), drops are formed and mass transfer of oxygen to drops is much faster. Most fungi and some mammalian cells need oxygen. Corrugated fibers with holes in the valleys also produce drops. White rot fungus needs oxygen and it degrades many chlorine compounds, azo dyes, PAHs (polycyclic aromatic hydrocarbons), and TNT. Old cardboard boxes are readily available and when buried in soil, oxygen is entrapped. In a lake, the boxes expose high area. Celite entrapped in fibers provides even more area. Fibers have high surface area for immobilizing cells and, when the fibers are rotated, fast reactions occur, converting one chemical to another. Sugar has been fermented to alcohol in 10--15 minutes. Ethanol has high octane and does not need lead. Old cars and trucks still use lead, and high levels have been found in the drinking water of several large cities. Bacteria on fibers can remove lead in a few seconds. When an RBC of plain fiber discs is rotated and a light shone in the tope, the light hits a thin moving film to degrade chlorine compounds and sterilize water. Titania can be fused to the fiberglass discs. Microbes and light remove sulfur from oil. Calcium magnesium acetate is a non-corrosive road deicer. Salt on roads causes millions of dollars damage to bridges and cars.

  13. Study on Compressive Behavior of Open-cell Aluminum Foam by Gypsum Mould Infiltrating Casting%石膏型渗流法制备的开孔泡沫铝的压缩行为研究

    Institute of Scientific and Technical Information of China (English)

    吴进; 程和法; 黄笑梅; 张燕瑰; 胡志君

    2011-01-01

    本文采用可溶石膏型预制块,通过加压渗流的方法制备了泡沫纯铝、泡沫ZL101合金和泡沫ZL102合金,并通过准静态压缩实验研究了3种不同基体材料的泡沫铝的压缩行为及吸能性能.结果表明:通过石膏型渗流法制备的开孔泡沫铝合金的孔隙率可以达到85%~93.5%;泡沫铝基体材料的力学性能对泡沫铝压缩力学性能有重要影响;泡沫ZL101合金能够吸收最多的能量,且在较大的应力、应变范围内对材料起到缓冲保护作用.%The polymeric reticular sponge was choosen as the mother plate to make the soluble gypsum mould,and after that, through infiltrating casting to fabricate three kinds of open-cell aluminum foam, which are pure aluminum foam, ZL101 aluminum alloy foam and ZL102 aluminum alloy foam. The compressive behaviors and energy-absorption capacities of those different kinds of foams were investigated by the quasi-static compression test. The experimental results indicate that the porosity of the aluminum foams made by the gypsum mould infiltrating casting are 85%~93. 5%;The matrix properties have notable effects on the mechanical behaviors of foams;The ZL101 aluminum alloy foam can absorb the most energy and also can protect the materials in the larger ranges of stress and strain.

  14. Cells on foam and fiber

    Energy Technology Data Exchange (ETDEWEB)

    Clyde, R. [Clyde Engineering, New Orleans, LA (United States)

    1995-11-01

    Cells growing on high area foam and when a screen is put around the foam, it is made heavier so it can be fluidized. When foam is rotated in a half full RBC, drops are formed and mass transfer of oxygen to drops in much faster. Most fungi and some mammalian cells need oxygen. Corrugated fibers with holes in the valleys also produce drops. White rot fungus needs oxygen and it degrades many chlorine compounds, azo dyes, and TNT. Old cardboard boxes are readily available and when buried in soil, oxygen is entrapped. In a lake, the boxes expose high area. Fibers have high surface area for immobilizing cells and when the fibers are rotated, fast reactions occur, converting one chemical to another. Sugar has been fermented to alcohol in 10-15 minutes. Ethanol has high octane and does not need lead. Old cars and trucks still use lead and high levels have been found in the drinking water of several large cities. Bacteria on fibers can remove lead in a few seconds. When an RBC of plain fiber discs is rotated and a light shone in the top the light hits a thin moving film to degrade chlorine compounds. Microbes and light remove sulfur from oil. Calcium magnesium acetate is a non corrosive road deicer. Salt on roads causes millions of dollars damage to bridges and cars. An inexpensive reactor has been made for organization studies of mammalian and plant cells. A magnet is near the bottom but not touching and oxygen is put on the top where there is no seal that can leak.

  15. Spacecraft Shielding: An Experimental Comparison Between Open Cell Aluminium Foam Core Sandwich Panel Structures and Whipple Shielding.

    Science.gov (United States)

    Pasini, D. L. S.; Price, M. C.; Burchell, M. J.; Cole, M. J.

    2013-09-01

    Spacecraft shielding is generally provided by metallic plates in a Whipple shield type configuration [1] where possible. However, mission restrictions such as spacecraft payload mass, can prevent the inclusion of a dedicated protective structure for prevention against impact damage from micrometeoroids. Due to this, often the spacecraft's primary structure will act as the de facto shield. This is commonly an aluminium honeycomb backed with either glass fibre reinforced plastic (GFRP) or aluminium faceplates [2]. Such materials are strong, lightweight and relatively cheap due to their abundance used within the aerospace industry. However, these materials do not offer the best protection (per unit weight) against hypervelocity impact damage. A new material for shielding (porous aluminium foam [3]) is suggested for low risk space missions. Previous studies by NASA [4] have been performed to test this new material against hypervelocity impacts using spherical aluminium projectiles. This showed its potential for protection for satellites in Earth orbit, against metallic space debris. Here we demonstrate the material's protective capabilities against micrometeoroids, using soda-lime glass spheres as projectiles to accurately gauge its potential with relation to silicatious materials, such as micrometeoroids and natural solar system debris. This is useful for spacecraft missions beyond Earth orbit where solar system materials are the dominant threat (via hypervelocity impacts) to the spacecraft, rather than manmade debris.

  16. 开孔泡沫金属紧凑式换热器高温力学性能研究%Study on High Temperature Mechanical Properties of Compact Heat Exchanger Based on Open-cell Metal Foam

    Institute of Scientific and Technical Information of China (English)

    周帼彦; 涂善东; 轩福贞; 王正东

    2011-01-01

    Plate-foam heat exchanger is developed on the basis of properties of open-cell metal foam. The short-term mechanical properties and long-term viscoelastic parameters of 316 stainless steel metal foam are measured in uniaxial tension experiments. Based on these parameters and small deflection thin plate theory, the plate-foam structure is simplified as a thin plate supported on the foundation. A computer program based on FORTRAN90 is developed by using the correspondence principle and the numerical inversion of Laplace transform. Then the viscoelastic bending deflection and stress of the plate-foam structure are analyzed. The feasibility and accuracy of the method are verified by a comparison of the analytical results with finite element simulations. The results show that the analytical solution is in good agreement with the numerical results. Furthermore, the effects of the structural parameters of the open-cell metal foam on the viscoelastic bending deflection and stress of the plate-foam structure are investigated. The results show that the relative density has a relatively great influence on the safety of the plate-foam structure.%基于开孔泡沫金属的特性,研发板泡式热交换器,通过单轴拉伸试验获得316不锈钢泡沫金属的短时力学性能和长时粘弹性参数,在此基础上引入小挠度薄板理论,将板泡结构简化作支承于地基上的薄板,基于对应性原理和数值逆变换方法,采用FORTRAN90编制程序,计算板泡结构的粘弹性弯曲变形和粘弹性弯曲应力,并与有限元模拟结果进行对比,验证该分析计算方法用于表征承压板泡式热交换器结构粘弹性行为的可行性与准确性.进而分析开孔泡沫金属结构参数对板泡结构的粘弹性弯曲变形和粘弹性弯曲应力的影响情况,结果表明开孔泡沫金属的孔隙率对板泡结构的安全性影响相对较大.

  17. Validation of OpenFoam for heavy gas dispersion applications

    NARCIS (Netherlands)

    Mack, A.; Spruijt, M.P.N.

    2013-01-01

    In the present paper heavy gas dispersion calculations were performed with OpenFoam. For a windtunnel test case, numerical data was validated with experiments. For a full scale numerical experiment,a code to code comparison was performed with numerical results obtained from Fluent. The validationwas

  18. Effect of Porosity and Cell Size on the Dynamic Compressive Properties of Aluminum Alloy Foams

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The dynamic mechanical properties of open-cell aluminum alloy foams with different relative densities and cell sizeshave been investigated by compressive tests. The strain rates varied from 700 s-1 to 2600 s-1. The experimentalresults showed that the dynamic compressive stress-strain curves exhibited a typical three-stage behavior: elastic,plateau and densification. The dynamic compressive strength of foams is affected not only by the relative densitybut also by the strain rate and cell size. Aluminum alloy foams with higher relative density or smaller cell size aremore sensitive to the strain rate than foams with lower relative density or larger cell size.

  19. Foaming-electrolyte fuel cell

    Science.gov (United States)

    Nanis, L.; Saunders, A. P.

    1970-01-01

    Foam structure feeds fuel gas solution into electrolyte. Fuel gas reacts at static, three-phase interface between fuel gas, electrolyte, and electrode material. The foam forms an electrical contact between main body of electrolyte and the electrode, and aids in removal of by-products of the chemical reaction.

  20. PUFoam : A novel open-source CFD solver for the simulation of polyurethane foams

    Science.gov (United States)

    Karimi, M.; Droghetti, H.; Marchisio, D. L.

    2017-08-01

    In this work a transient three-dimensional mathematical model is formulated and validated for the simulation of polyurethane (PU) foams. The model is based on computational fluid dynamics (CFD) and is coupled with a population balance equation (PBE) to describe the evolution of the gas bubbles/cells within the PU foam. The front face of the expanding foam is monitored on the basis of the volume-of-fluid (VOF) method using a compressible solver available in OpenFOAM version 3.0.1. The solver is additionally supplemented to include the PBE, solved with the quadrature method of moments (QMOM), the polymerization kinetics, an adequate rheological model and a simple model for the foam thermal conductivity. The new solver is labelled as PUFoam and is, for the first time in this work, validated for 12 different mixing-cup experiments. Comparison of the time evolution of the predicted and experimentally measured density and temperature of the PU foam shows the potentials and limitations of the approach.

  1. Sound absorption property of open-pore aluminum foams

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; WANG Lu-cai; WU Jian-guo; YOU Xiao-hong

    2007-01-01

    This paper presents a study on sound absorption property of aluminum foam by evaluating its sound absorption coefficients using standing wave tube method. Experimental results showed that the average values of sound absorption coefficients (over the test frequency range) are all above 0.4, which indicate very good sound absorption property of the aluminum foams. The sound absorption coefficient is affected by frequency and pore structure, and reaches its maximum value at around 1 000 Hz. With the increase of porosity and decrease of cell diameter, the sound absorption coefficient values increase.

  2. Study on the Effect of CaCO 3 on Open-cell Foaming Performance of Polypropylene%成核剂CaCO3对聚丙烯开孔发泡性能影响的研究

    Institute of Scientific and Technical Information of China (English)

    曹贤武; 何丁; 伍巍; 黄益威; 周南桥

    2011-01-01

    将高熔体强度聚丙烯(HMSPP)、线型低密度聚乙烯(LLDPE)、成核剂CaCO3共混后在自制超临界CO2动态发泡模拟机上发泡制备了聚丙烯开孔泡沫材料,研究了CaCO3的粒径和含量对聚丙烯开扎发泡性能的影响.结果表明:2500目CaCO3在HMSPP/LLDPE共混体系中的分散效果比5 000目CaCO3的好.添加2 500目和5 000目CaCO3后,发泡样品的发泡倍率减小,泡孔密度增大,泡孔直径减小,泡孔形貌变得规则,泡孔直径分布变窄,泡孔均匀性增加.添加3%的2500目和5 000目CaCO3时发泡性能最好.在共混体系中添加成核剂CaCO3能够提高发泡样品的开孔性能.%PP open-cell foam was prepared from the blends of high,melt-strength polypropylene ( HM-SPP) , linear low-density polyethylene (LLDPE) and nucleating agent CaCO, on a self-designed dynamic foaming simulation device. The effect of particle size and content of CaCO 3 on PP open-cell foaming performance was investigated. The results showed that 2 500 mesh CaCO3 diffused better than 5 000 mesh CaCO3 in HMSPP/LLDPE blends. As CaCO3 was added, the expansion ratio decreased, cell density increased,' cell diameter decreased, cell shape became regular, distribution of cell diameter became narrow, cell became more uniform. The foaming performance of HMSPP/LLDPE blends with 3% 2 500 mesh or 5 000 mesh CaCO 3 was best. As CaCO3 was added, open-cell performance increased.

  3. Optimising the Parallelisation of OpenFOAM Simulations

    Science.gov (United States)

    2014-06-01

    8GB DDR3-1600 Registered ECC memory Storage: 1TB SATA HDD plus network file system (NFS) server. OS: CentOS 6.5 CFD Software: OpenFOAM 2.2.2 with...E5 2687W – 8 cores per CPU @ 3.1GHz RAM: 16x 32GB DDR3-1333 Registered ECC memory Storage: 1TB SATA HDD plus 3x 3TB SATA HDD in RAID0 OS: Red Hat

  4. plasmaFoam: An OpenFOAM framework for computational plasma physics and chemistry

    Science.gov (United States)

    Venkattraman, Ayyaswamy; Verma, Abhishek Kumar

    2016-09-01

    As emphasized in the 2012 Roadmap for low temperature plasmas (LTP), scientific computing has emerged as an essential tool for the investigation and prediction of the fundamental physical and chemical processes associated with these systems. While several in-house and commercial codes exist, with each having its own advantages and disadvantages, a common framework that can be developed by researchers from all over the world will likely accelerate the impact of computational studies on advances in low-temperature plasma physics and chemistry. In this regard, we present a finite volume computational toolbox to perform high-fidelity simulations of LTP systems. This framework, primarily based on the OpenFOAM solver suite, allows us to enhance our understanding of multiscale plasma phenomenon by performing massively parallel, three-dimensional simulations on unstructured meshes using well-established high performance computing tools that are widely used in the computational fluid dynamics community. In this talk, we will present preliminary results obtained using the OpenFOAM-based solver suite with benchmark three-dimensional simulations of microplasma devices including both dielectric and plasma regions. We will also discuss the future outlook for the solver suite.

  5. Modelling of gas-liquid, two-phase flow in porous media and channels of a PEM water electrolysis cell using the Euler-Euler framework of OpenFOAM

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Kær, Søren Knudsen

    was shown to push the limits of the codes ca-pabilities. In order to improve simulation stability and time, a new model is developed in the open source CFD software OpenFOAM. The customizability of this code not only allows for specific relaxation strategies, it also permits the implementation of various...

  6. Effects of glycosaminoglycan from scallop skirt on foam cell

    Institute of Scientific and Technical Information of China (English)

    Fu-shengSUN; SaiLIU

    2004-01-01

    AIM: To study effects of glycosaminoglycan from scallop skirt (SS-GAG) on NO production, antioxidative enzyme activity,and formation of macrophage-derived and smooth muscle cell-derived foam cell; to study the effects of SS-GAG on VEGF expression, intracellular Ca2~ level, and cytokines secretion of macrophage-derived foam cell. METHODS: Foam-like cells were generated by incubating the U937 cells or porcine artery smooth

  7. OpenFOAM Analysis of CANDU-6 Moderator Flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoung Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chang, Se-Myong [Kunsan National University, Gunsan (Korea, Republic of)

    2015-10-15

    In this study OpenFOAM (Open Field Operation and Manipulation), an open source CFD solver, is used to simulate the three-dimensional moderator flow in calandria tank of CANDU-6 reactor improving the computational efficiency by parallel computing which does not need any proprietary license. A prototype of CANDU-6 reactor is numerically analyzed about three-dimensional moderator flow in calandrian tank with OpenFOAM, an open source CFD code. The horizontal fuel channels in a CANDU-6 reactor (a pressurized heavy water reactor) are submerged in the heavy water (D{sub 2}O) pool which is contained by a cylindrical tank, calandria. Each fuel channel consists of concentric tubes: a Pressure Tube (PT) and a Calandria Tube (CT). And the CO{sub 2} gas is filled between these tubes. Consequently, a heat flux is rapidly transferred to the outer CT so that a film boiling may occur in CT. As a result, it is important to keep the subcooling in the moderator. It is one of the major concerns in the CANDU safety analyses to estimate the local subcooling margin of the moderator inside the calandria tank. Previous experimental studies showed that the film boiling would be unlikely to occur if the local moderator subcooling is sufficient. Therefore, an accurate prediction of the moderator temperature distribution in the calandria tank is needed to confirm the channel integrity. There have been numerous computational efforts to estimate the thermal hydraulics in the calandria tank using CFD codes. Hadaller et al. obtained a tube bank pressure drop model for tube bundle region of the calandria tank and implemented it into the MODTURC{sub C}LAS code. Yoon et al. used the CFX code to develop a CFD model with a porous media approach for the core region. However, it is known that porous media modeling provide only average values of flow velocities and temperatures and do not give any information about local flow variables near tube solid walls, which are necessary to implement accurate heat

  8. Manufacturing of Cast Metal Foams with Irregular Cell Structure

    Directory of Open Access Journals (Sweden)

    Kroupová I.

    2015-06-01

    Full Text Available Metallic foams are materials of which the research is still on-going, with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.. These metallic materials have specific properties, such as large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting technology (infiltration method, which ensures rapid and economically feasible method for production of shaped components. In the experimental part we studied conditions of casting of metallic foams with open pores and irregular cell structure made of ferrous and nonferrous alloys by use of various types of filler material (precursors.

  9. RANS Simulation of Turbulent Diffusive Combustion using Open Foam

    Directory of Open Access Journals (Sweden)

    Luis Felipe Gutiérrez

    2016-01-01

    Full Text Available Schemes to write the flow equations in discreet form, solution solvers, pre and post data processing utilitiesprovidedbyOpenFoamlibraries, areusedtobuildafinitevolumeexecutableforsimulatinga low speed, turbulent and rate controlled diffusive CH4-Air combustion. Unsteady Favre’s averaged turbulent conservation equations (total mass, momentum, energy and species mass fractions, are used to describe the combustion gas dynamics, and to handle turbulence a modified k- ε model is applied. Several global kinetic mechanisms, one step, two and four steps have been considered to describe the oxidation process of CH4 in a free jet type flame. The interaction between chemistry and turbulence, is modeled according to the partially stirred reactor (PaSR concept. To improve convergence and accuracy in solving low speed fluid dynamic equations, a pressure implicit with splitting of operators (PISO technique extended to cover high temperature flows, is utilized. The exponential dependence of the chemical kinetics from temperature, makes stiffs the ODE’s needed to determine source average values with which the species conservation equations are solved. To deal with the stiffness issue, OpenFoam provides numerical schemes that guaranties the stability of the computation. Comparisons between results of numerical simulations and experimental data obtained with the benchmark known as flame “D”, are presented.

  10. Comparison of OpenFOAM and EllipSys3D for neutral atmospheric flow over complex terrain

    DEFF Research Database (Denmark)

    Cavar, Dalibor; Réthoré, Pierre-Elouan; Bechmann, Andreas;

    2016-01-01

    The flow solvers OpenFOAM and EllipSys3D are compared in the case of neutral atmospheric flow over terrain using the test cases of Askervein and Bolund hills. Both solvers are run using the steady-state Reynolds-averaged Navier–Stokes k– turbulence model. One of the main modeling differences...... between the two solvers is the wall-function approach. The Open-FOAM v.1.7.1 uses a Nikuradse’s sand roughness model, while EllipSys3D uses a model based on the atmospheric roughness length. It is found that Nikuradse’s model introduces an error dependent on the near-wall cell height. To mitigate...... this error the near-wall cells should be at least 10 times larger than the surface roughness. It is nonetheless possible to obtain very similar results between EllipSys3D and OpenFOAM v.1.7.1. The more recent OpenFOAM v.2.2.1, which includes the atmospheric roughness length wall-function approach, has also...

  11. Cell Structure Evolution of Aluminum Foams Under Reduced Pressure Foaming

    Science.gov (United States)

    Cao, Zhuokun; Yu, Yang; Li, Min; Luo, Hongjie

    2016-09-01

    Ti-H particles are used to increase the gas content in aluminum melts for reduced pressure foaming. This paper reports on the RPF process of AlCa alloy by adding TiH2, but in smaller amounts compared to traditional process. TiH2 is completely decomposed by stirring the melt, following which reduced pressure is applied. TiH2 is not added as the blowing agent; instead, it is added for increasing the H2 concentration in the liquid AlCa melt. It is shown that pressure change induces further release of hydrogen from Ti phase. It is also found that foam collapse is caused by the fast bubble coalescing during pressure reducing procedure, and the instability of liquid film is related to the significant increase in critical thickness of film rupture. A combination of lower amounts of TiH2, coupled with reduced pressure, is another way of increasing hydrogen content in the liquid aluminum. A key benefit of this process is that it provides time to transfer the molten metal to a mold and then apply the reduced pressure to produce net shape foam parts.

  12. Combination nickel foam expanded nickel screen electrical connection supports for solid oxide fuel cells

    Science.gov (United States)

    Draper, Robert; Prevish, Thomas; Bronson, Angela; George, Raymond A.

    2007-01-02

    A solid oxide fuel assembly is made, wherein rows (14, 25) of fuel cells (17, 19, 21, 27, 29, 31), each having an outer interconnection (20) and an outer electrode (32), are disposed next to each other with corrugated, electrically conducting expanded metal mesh member (22) between each row of cells, the corrugated mesh (22) having top crown portions and bottom portions, where the top crown portion (40) have a top bonded open cell nickel foam (51) which contacts outer interconnections (20) of the fuel cells, said mesh and nickel foam electrically connecting each row of fuel cells, and where there are no more metal felt connections between any fuel cells.

  13. Foam cell formation by particulate matter (PM) exposure: a review.

    Science.gov (United States)

    Cao, Yi; Long, Jimin; Ji, Yuejia; Chen, Gui; Shen, Yuexin; Gong, Yu; Li, Juan

    2016-11-01

    Increasing evidence suggests that exposure of particulate matter (PM) from traffic vehicles, e.g., diesel exhaust particles (DEP), was associated with adverse vascular effects, e.g., acceleration of atherosclerotic plaque progression. By analogy, engineered nanoparticles (NPs) could also induce similar effects. The formation of lipid laden foam cells, derived predominately from macrophages and vascular smooth muscle cells (VSMC), is closely associated with the development of atherosclerosis and adverse vascular effects. We reviewed current studies about particle exposure-induced lipid laden foam cell formation. In vivo studies using animal models have shown that exposure of air pollution by PM promoted lipid accumulation in alveolar macrophages or foam cells in plaques, which was likely associated with pulmonary inflammation or systemic oxidative stress, but not blood lipid profile. In support of these findings, in vitro studies showed that direct exposure of cultured macrophages to DEP or NP exposure, with or without further exposure to external lipids, promoted intracellular lipid accumulation. The mechanisms remained unknown. Although a number studies found increased reactive oxygen species (ROS) or an adaptive response to oxidative stress, the exact role of oxidative stress in mediating particle-induced foam cell formation requires future research. There is currently lack of reports concerning VSMC as a source for foam cells induced by particle exposure. In the future, it is necessary to explore the role of foam cell formation in particle exposure-induced atherosclerosis development. In addition, the formation of VSMC derived foam cells by particle exposure may also need extensive studies.

  14. rhoCentralRfFoam: An OpenFOAM solver for high speed chemically active flows - Simulation of planar detonations -

    Science.gov (United States)

    Gutiérrez Marcantoni, L. F.; Tamagno, J.; Elaskar, S.

    2017-10-01

    A new solver developed within the framework of OpenFOAM 2.3.0, called rhoCentralRfFoam which can be interpreted like an evolution of rhoCentralFoam, is presented. Its use, performing numerical simulations on initiation and propagation of planar detonation waves in combustible mixtures H2-Air and H2-O2-Ar, is described. Unsteady one dimensional (1D) Euler equations coupled with sources to take into account chemical activity, are numerically solved using the Kurganov, Noelle and Petrova second order scheme in a domain discretized with finite volumes. The computational code can work with any number of species and its corresponding reactions, but here it was tested with 13 chemically active species (one species inert), and 33 elementary reactions. A gaseous igniter which acts like a shock-tube driver, and powerful enough to generate a strong shock capable of triggering exothermic chemical reactions in fuel mixtures, is used to start planar detonations. The following main aspects of planar detonations are here, treated: induction time of combustible mixtures cited above and required mesh resolutions; convergence of overdriven detonations to Chapman-Jouguet states; detonation structure (ZND model); and the use of reflected shocks to determine induction times experimentally. The rhoCentralRfFoam code was verified comparing numerical results and it was validated, through analytical results and experimental data.

  15. A Discussion on the Interpretation of the Darcy Equation in Case of Open-Cell Metal Foam Based on Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Sven De Schampheleire

    2016-05-01

    Full Text Available It is long known that for high-velocity fluid flow in porous media, the relation between the pressure drop and the superficial velocity is not linear. Indeed, the classical Darcy law for shear stress dominated flow needs to be extended with a quadratic term, resulting in the empirical Darcy–Forchheimer model. Another approach is to simulate the foam numerically through the volume averaging technique. This leads to a natural separation of the total drag force into the contribution of the shear forces and the contribution of the pressure forces. Both representations of the total drag lead to the same result. The physical correspondence between both approaches is investigated in this work. The contribution of the viscous and pressure forces on the total drag is investigated using direct numerical simulations. Special attention is paid to the dependency on the velocity of these forces. The separation of the drag into its constituent terms on experimental grounds and for the volume average approach is unified. It is shown that the common approach to identify the linear term with the viscous forces and the quadratic term with the pressure forces is not correct.

  16. Signaling events in pathogen-induced macrophage foam cell formation.

    Science.gov (United States)

    Shaik-Dasthagirisaheb, Yazdani B; Mekasha, Samrawit; He, Xianbao; Gibson, Frank C; Ingalls, Robin R

    2016-08-01

    Macrophage foam cell formation is a key event in atherosclerosis. Several triggers induce low-density lipoprotein (LDL) uptake by macrophages to create foam cells, including infections with Porphyromonas gingivalis and Chlamydia pneumoniae, two pathogens that have been linked to atherosclerosis. While gene regulation during foam cell formation has been examined, comparative investigations to identify shared and specific pathogen-elicited molecular events relevant to foam cell formation are not well documented. We infected mouse bone marrow-derived macrophages with P. gingivalis or C. pneumoniae in the presence of LDL to induce foam cell formation, and examined gene expression using an atherosclerosis pathway targeted plate array. We found over 30 genes were significantly induced in response to both pathogens, including PPAR family members that are broadly important in atherosclerosis and matrix remodeling genes that may play a role in plaque development and stability. Six genes mainly involved in lipid transport were significantly downregulated. The response overall was remarkably similar and few genes were regulated in a pathogen-specific manner. Despite very divergent lifestyles, P. gingivalis and C. pneumoniae activate similar gene expression profiles during foam cell formation that may ultimately serve as targets for modulating infection-elicited foam cell burden, and progression of atherosclerosis.

  17. Mixing foams and grains in Hele-Shaw cells

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, A P B; Tufaile, A; Haddad, T A S, E-mail: tufaile@usp.b [Escola de Artes, Ciencias e Humanidades da Universidade de Sao Paulo, R. Arlindo Bettio, 1000, 03828-000, Sao Paulo (Brazil)

    2010-09-01

    We have observed some features of the coexistence of foams and granular materials in Hele-Shaw cells. The most part of the liquid and granular material stays at the bottom of the cell, with only a small quantity of the mixture resting on the froth. The fractal dimensions of the final states of the foams are close to the values obtained from the Random Apollonian Packing model. The disperse structure of the granular material affects the probability distribution of number of sides of the foam bubbles. The nearest neighbor distances between the peaks of the sand piles at the bottom of the cell are close to a lognormal distribution.

  18. Evaluate shock capturing capability with the numerical methods in OpenFOAM

    Directory of Open Access Journals (Sweden)

    Khodadadi Azadboni Reza

    2013-01-01

    Full Text Available Simulations for both multiphase flows and supersonic single phased flows are well known, however the combination is a less investigated area of research, as the two basic approaches of CFD, the pressure and the density based approach, each describe one of the phases in a better way than the other one. In this paper, we systematically investigate the solver quality of the open source CFD code OpenFOAM in handling transonic flow phenomena that typically occur inside the breaking chamber of high voltage circuit breakers, during contact separation. The solver quality is then compared with that of chosen commercial CFD tools. The main advantage of OpenFOAM is that, contrary to most of the commercial simulation tools, it is license fee free and allows access to the source code. This means that complicated multi physics phenomena inside the arcing chamber can be directly modeled into the code by users, which opens an opportunity to remove limitations of commercial CFD tools. Particularly, the shock capturing capability of OpenFOAM will be evaluated for the transonic internal flow which typically occurs in high voltage circuit breakers. Overall, Open-FOAM shows acceptable shock capturing capabilities in the performed verification and validation studies, with the solver quality comparable to some of the tested commercial CFD tools. There is still room for further solver quality improvements in OpenFOAM by implementing better shock capturing schemes such as a density-based flux-difference-splitting scheme or by writing better physical modeling of the shock/boundary layer interaction into the open architecture of OpenFOAM.

  19. On the implicit density based OpenFOAM solver for turbulent compressible flows

    Science.gov (United States)

    Fürst, Jiří

    The contribution deals with the development of coupled implicit density based solver for compressible flows in the framework of open source package OpenFOAM. However the standard distribution of OpenFOAM contains several ready-made segregated solvers for compressible flows, the performance of those solvers is rather week in the case of transonic flows. Therefore we extend the work of Shen [15] and we develop an implicit semi-coupled solver. The main flow field variables are updated using lower-upper symmetric Gauss-Seidel method (LU-SGS) whereas the turbulence model variables are updated using implicit Euler method.

  20. On the implicit density based OpenFOAM solver for turbulent compressible flows

    Directory of Open Access Journals (Sweden)

    Fürst Jiří

    2017-01-01

    Full Text Available The contribution deals with the development of coupled implicit density based solver for compressible flows in the framework of open source package OpenFOAM. However the standard distribution of OpenFOAM contains several ready-made segregated solvers for compressible flows, the performance of those solvers is rather week in the case of transonic flows. Therefore we extend the work of Shen [15] and we develop an implicit semi-coupled solver. The main flow field variables are updated using lower-upper symmetric Gauss-Seidel method (LU-SGS whereas the turbulence model variables are updated using implicit Euler method.

  1. On the implicit density based OpenFOAM solver for turbulent compressible flows

    Science.gov (United States)

    Fürst, Jiří

    2016-11-01

    The contribution deals with the development of coupled implicit density based solver for compressible flows in the framework of open source package OpenFOAM. However the standard distribution of OpenFOAM contains several ready-made segregated solvers for compressible flows, the performance of those solvers is rather week in the case of transonic flows. Therefore we extend the work of Shen [15] and we develop an implicit semi-coupled solver. The main flow field variables are updated using lower-upper symmetric Gauss-Seidel method (LU-SGS) whereas the turbulence model variables are updated using implicit Euler method.

  2. Thermal Conductivity of Foam Glass

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    Due to the increased focus on energy savings and waste recycling foam glass materials have gained increased attention. The production process of foam glass is a potential low-cost recycle option for challenging waste, e.g. CRT glass and industrial waste (fly ash and slags). Foam glass is used...... as thermal insulating material in building and chemical industry. The large volume of gas (porosity 90 – 95%) is the main reason of the low thermal conductivity of the foam glass. If gases with lower thermal conductivity compared to air are entrapped in the glass melt, the derived foam glass will contain...... only closed pores and its overall thermal conductivity will be much lower than that of the foam glass with open pores. In this work we have prepared foam glass using different types of recycled glasses and different kinds of foaming agents. This enabled the formation of foam glasses having gas cells...

  3. Hyperbolic prisms and foams in Hele-Shaw cells

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, A., E-mail: tufaile@usp.br [Soft Matter Laboratory, Escola de Artes, Ciencias e Humanidades, Universidade de Sao Paulo, 03828-000, Sao Paulo (Brazil); Tufaile, A.P.B. [Soft Matter Laboratory, Escola de Artes, Ciencias e Humanidades, Universidade de Sao Paulo, 03828-000, Sao Paulo (Brazil)

    2011-10-03

    The propagation of light in foams creates patterns which are generated due to the reflection and refraction of light. One of these patterns is observed by the formation of multiple mirror images inside liquid bridges in a layer of bubbles in a Hele-Shaw cell. We are presenting the existence of these patterns in foams and their relation with hyperbolic geometry and Sierpinski gaskets using the Poincare disk model. The images obtained from the experiment in foams are compared to the case of hyperbolic optical elements. -- Highlights: → The chaotic scattering of light in foams generating deltoid patterns is based on hyperbolic geometry. → The deltoid patterns are obtained through the Plateau borders in a Hele-Shaw cell. → The Plateau borders act like hyperbolic prism. → Some effects of the refraction and reflection of the light rays were studied using a hyperbolic prism.

  4. Porosity and cell size control in alumina foam preparation by thermo-foaming of powder dispersions in molten sucrose

    Directory of Open Access Journals (Sweden)

    Sujith Vijayan

    2016-09-01

    Full Text Available The foaming characteristics of alumina powder dispersions in molten sucrose have been studied as a function of alumina powder to sucrose weight ratio (WA/S and foaming temperature. The increase in foaming temperature significantly decreases the foaming and foam setting time and increases the foam volume due to an increase in the rate of OH condensation as well as a decrease in the viscosity of the dispersion. Nevertheless, the foam collapses beyond a critical foaming temperature, which depends on the WA/S. The sintering shrinkage depends mainly on the WA/S and marginally on the foaming temperature. The porosity (83.4–94.6 vol.% and cell size (0.55–1.6 mm increase with an increase in foaming temperature (120–170 °C and a decrease in WA/S (0.8–1.6. The drastic decrease in compressive strength and modulus beyond a WA/S of 1.2 is due to the pores generated on the cell walls and struts as a result of particle agglomeration. Gibson and Ashby plots show large deviation with respect to the model constants ‘C’ and ‘n’, especially at higher alumina powder to sucrose weight ratios.

  5. Development of Virtual Blade Model for Modelling Helicopter Rotor Downwash in OpenFOAM

    Science.gov (United States)

    2013-12-01

    13, most OpenFOAM data files are themselves dictionaries containing a set of keyword entries. Dictionaries provide the means for organising entries...14. RELEASE AUTHORITY Chief, Aerospace Division 15. SECONDARY RELEASE STATEMENT OF THIS DOCUMENT Approved for Public release OVERSEAS

  6. Modeling of low-capillary number segmented flows in microchannels using OpenFOAM

    NARCIS (Netherlands)

    Hoang, D.A.; Van Steijn V.; Portela, L.M.; Kreutzer, M.T.; Kleijn, C.R.

    2012-01-01

    Modeling of low-Capillary number segmented flows in microchannels is important for the design of microfluidic devices. We present numerical validations of microfluidic flow simulations using the volume-of-fluid (VOF) method as implemented in OpenFOAM. Two benchmark cases were investigated to ensure

  7. Mesostructural Design and Manufacturing of Open-Pore Metal Foams by Investment Casting

    Directory of Open Access Journals (Sweden)

    Alexander Martin Matz

    2014-01-01

    Full Text Available The present paper describes the manufacturing process of open-pore metal foams by investment casting and the mesostructural/morphological evolution resulting from a new technique of modifying the precursor. By this technique, the precursor is coated with a polymer layer whereby a thickening of the struts occurs. Relative densities in the range of 1.85≤ρrel≤25% of open-pore metal foams can be achieved with high accuracy. The samples investigated have pore densities of ρP=7 ppi, 10 ppi, and 13 ppi. The relevant processing parameters needed for a homogenous formation of the polymer layer are determined for two different coating materials and the resulting open-pore foam’s mesostructure is characterized qualitatively and quantitatively. The alloy used for investment casting open-pore metal foamsis AlZn11. The microstructural evolution of these foams is evaluated as a function of the mesostructure. Differences in the microstructure are observed for foams with low and high relative densities and discussed in terms of cooling subsequent to investment casting.

  8. Modeling of Diesel Fuel Spray Formation and Combustion in OpenFOAM

    Energy Technology Data Exchange (ETDEWEB)

    Koesters, Anne

    2012-07-01

    The formation, ignition, and combustion of fuel sprays are highly complex processes and the available models have various shortcomings. The development and application of multidimensional CFD models, that describe the different phenomena have rapidly increased through the use of commercial and public software (e.g. Star-CD, KIVA, FIRE and OpenFOAM). The general approach to spray modeling is given by the Eulerian-Lagrangian method, where the gas phase is modeled as a continuum and the droplets are tracked in a Lagrangian way. The accuracy and robustness of today's spray models vary substantially and spray penetration simulations and the levels of spray-generated turbulence are dependent on the discretization. The work presented here deals with the prediction of spray formation and combustion with improved models implemented in the free, open source software package OpenFOAM. The VSB2 spray model was implemented and tested under varying ambient conditions. The design criteria of the model were to be unconditionally robust, have a minimal number of tuning parameters, and be implementable in any CFD software package supporting particle tracking. The main difference between the VSB2 spray model and standard spray models is how the interaction between the liquid fuel and hot gas phase is modeled. In the VSB2 spray model, a 'blob' is defined, containing differently sized droplets; instead of a parcel containing equally sized droplets. Another feature is the definition of a bubble surrounding the blob. The blob just interacts with the gas phase in the bubble instead of with the gas phase in the whole grid cell. The idea is to reduce grid dependency. Furthermore, equilibrium between the blob and the bubble is ensured, which makes the model very robust. Results of spray penetration simulations are compared with data obtained from experiments done at Chalmers Univ. of Technology and with experimental data published by Siebers and Naber from Sandia National

  9. Foaming and cell flotation in suspended plant cell cultures and the effect of chemical antifoams.

    Science.gov (United States)

    Wongsamuth, R; Doran, P M

    1994-08-01

    Foam development and stability in Atropa belladonna suspensions were investigated as a function of culture conditions. Foaming was due mainly to properties of the cell-free broth and was correlated with protein content; effects due to presence of cells increased towards the end of batch culture. Highest foam levels were measured 11 days after inoculation. Air flow rate was of major importance in determining foam volume; foam volume and stability were also strongly dependent on pH. Foam flotation of plant cells was very effective. After 30 min foaming, ca. 55% of cells were found in the foam; this increased to ca. 75% after 90 min. Polypropylene glycol 1025 and 2025, Pluronic PE 6100, and Antifoam-C emulsion were tested as chemical antifoams. Polypropylene glycol 1025 and Antifoam C at concentrations up to 600 ppm had no adverse effect on growth in shake flasks; Pluronic PE 6100 has an inhibitory effect at all levels tested. Concentrations of polypropylene glycol 2025 and Pluronic PE 6100 as low as 20 ppm reduced foam volumes by a factor of ca. 10. Addition of antifoam reduced k(L)a values in bubble-column and stirred-tank bioreactors. After operation of a stirred reactor for 2 days using Antifoam C for foam control, cell production was limited by oxygen due to the effect of antifoam on mass transfer. Theoretical analysis showed that maximum cell concentrations and biomass levels decline with increasing reactors working volume due to greater consumption of antifoam to prevent foam overflow. The results indicate that when chemical foam control is used in plant cell cultures, head-space volume and tolerable foam levels must be considered to optimize biomass production. (c) 1994 John Wiley & Sons, Inc.

  10. Correlation between porous texture and cell seeding efficiency of gas foaming and microfluidic foaming scaffolds.

    Science.gov (United States)

    Costantini, Marco; Colosi, Cristina; Mozetic, Pamela; Jaroszewicz, Jakub; Tosato, Alessia; Rainer, Alberto; Trombetta, Marcella; Święszkowski, Wojciech; Dentini, Mariella; Barbetta, Andrea

    2016-05-01

    In the design of scaffolds for tissue engineering applications, morphological parameters such as pore size, shape, and interconnectivity, as well as transport properties, should always be tailored in view of their clinical application. In this work, we demonstrate that a regular and ordered porous texture is fundamental to achieve an even cell distribution within the scaffold under perfusion seeding. To prove our hypothesis, two sets of alginate scaffolds were fabricated using two different technological approaches of the same method: gas-in-liquid foam templating. In the first one, foam was obtained by insufflating argon in a solution of alginate and a surfactant under stirring. In the second one, foam was generated inside a flow-focusing microfluidic device under highly controlled and reproducible conditions. As a result, in the former case the derived scaffold (GF) was characterized by polydispersed pores and interconnects, while in the latter (μFL), the porous structure was highly regular both with respect to the spatial arrangement of pores and interconnects and their monodispersity. Cell seeding within perfusion bioreactors of the two scaffolds revealed that cell population inside μFL scaffolds was quantitatively higher than in GF. Furthermore, seeding efficiency data for μFL samples were characterized by a lower standard deviation, indicating higher reproducibility among replicates. Finally, these results were validated by simulation of local flow velocity (CFD) inside the scaffolds proving that μFL was around one order of magnitude more permeable than GF.

  11. Humidifier for fuel cell using high conductivity carbon foam

    Science.gov (United States)

    Klett, James W.; Stinton, David P.

    2006-12-12

    A method and apparatus of supplying humid air to a fuel cell is disclosed. The extremely high thermal conductivity of some graphite foams lends itself to enhance significantly the ability to humidify supply air for a fuel cell. By utilizing a high conductivity pitch-derived graphite foam, thermal conductivity being as high as 187 W/m.dot.K, the heat from the heat source is more efficiently transferred to the water for evaporation, thus the system does not cool significantly due to the evaporation of the water and, consequently, the air reaches a higher humidity ratio.

  12. Discrete Particle Model for Porous Media Flow using OpenFOAM at Intel Xeon Phi Coprocessors

    Science.gov (United States)

    Shang, Zhi; Nandakumar, Krishnaswamy; Liu, Honggao; Tyagi, Mayank; Lupo, James A.; Thompson, Karten

    2015-11-01

    The discrete particle model (DPM) in OpenFOAM was used to study the turbulent solid particle suspension flows through the porous media of a natural dual-permeability rock. The 2D and 3D pore geometries of the porous media were generated by sphere packing with the radius ratio of 3. The porosity is about 38% same as the natural dual-permeability rock. In the 2D case, the mesh cells reach 5 million with 1 million solid particles and in the 3D case, the mesh cells are above 10 million with 5 million solid particles. The solid particles are distributed by Gaussian distribution from 20 μm to 180 μm with expectation as 100 μm. Through the numerical simulations, not only was the HPC studied using Intel Xeon Phi Coprocessors but also the flow behaviors of large scale solid suspension flows in porous media were studied. The authors would like to thank the support by IPCC@LSU-Intel Parallel Computing Center (LSU # Y1SY1-1) and the HPC resources at Louisiana State University (http://www.hpc.lsu.edu).

  13. Foaming properties of guar foaming albumin

    OpenAIRE

    細見, 典子; Hosomi, Noriko; 原田, 麻子; Harada, Asako; 下山, 亜美; Shimoyama, Ami; 土居, 幸雄; Doi, Yukio

    2009-01-01

    From guar meal we recently isolated an albumin fraction with a high foaming ability, named guar foaming albumin (GFA) . Here, we further characterized the foaming activity, foam stability and surface tension of GFA solutions. Foaming activity and foam stability were estimated by measuring the conductivity of foam using a glass column with a conductivity cell. Surface tension was measured by the drop weight method using a stalagmometer. GFA showed higher foaming activity than casein at any pro...

  14. Parametric model of ventilators simulated in OpenFOAM and Elmer

    Science.gov (United States)

    Čibera, Václav; Matas, Richard; Sedláček, Jan

    2016-03-01

    The main goal of presented work was to develop parametric model of a ventilator for CFD and structural analysis. The whole model was designed and scripted in freely available open source programmes in particular in OpenFOAM and Elmer. The main script, which runs or generates other scripts and further control the course of simulation, was written in bash scripting language in Linux environment. Further, the scripts needed for a mesh generation and running of a simulation were prepared using m4 word pre-processor. The use of m4 allowed comfortable set up of the higher amount of scripts. Consequently, the mesh was generated for fluid and solid part of the ventilator within OpenFOAM. Although OpenFOAM offers also a few tools for structural analysis, the mesh of solid parts was transferred into Elmer mesh format with the aim to perform structural analysis in this software. This submitted paper deals namely with part concerning fluid flow through parametrized geometry with different initial conditions. As an example, two simulations were conducted for the same geometric parameters and mesh but for different angular velocity of ventilator rotation.

  15. Parametric model of ventilators simulated in OpenFOAM and Elmer

    Directory of Open Access Journals (Sweden)

    Čibera Václav

    2016-01-01

    Full Text Available The main goal of presented work was to develop parametric model of a ventilator for CFD and structural analysis. The whole model was designed and scripted in freely available open source programmes in particular in OpenFOAM and Elmer. The main script, which runs or generates other scripts and further control the course of simulation, was written in bash scripting language in Linux environment. Further, the scripts needed for a mesh generation and running of a simulation were prepared using m4 word pre-processor. The use of m4 allowed comfortable set up of the higher amount of scripts. Consequently, the mesh was generated for fluid and solid part of the ventilator within OpenFOAM. Although OpenFOAM offers also a few tools for structural analysis, the mesh of solid parts was transferred into Elmer mesh format with the aim to perform structural analysis in this software. This submitted paper deals namely with part concerning fluid flow through parametrized geometry with different initial conditions. As an example, two simulations were conducted for the same geometric parameters and mesh but for different angular velocity of ventilator rotation.

  16. Simulating transport in and entrainment form nonwoven fibrous, knitted, and opne-cell foam filters

    OpenAIRE

    Golkarfard, V.; Mullins, B; King, A.; Abishek, S.; Kasper, G; Heikamp, W.

    2016-01-01

    The movement and re-entrainment of liquid droplets from three different filter media, namely fibrous, knitted, and open-cell foam was investigated numerically using computational fluid dynamics (CFD). A range of face velocities were considered which resulted in a range of oil transform rates and steady state saturation levels. It will be shown that liquid volume fraction in filters depends on velocity and time. The minimum velocity required for detachment of droplets was also identified. The ...

  17. Novel Elastomeric Closed Cell Foam - Nonwoven Fabric Composite Material (Phase III)

    Science.gov (United States)

    2008-10-01

    AFRL-RX-TY-TR-2009-4577 NOVEL ELASTOMERIC CLOSED CELL FOAM – NONWOVEN FABRIC COMPOSITE MATERIAL (PHASE III) Davis, Stephen C...07-OCT-2009 Novel Elastomeric Closed Cell Foam - Nonwoven Fabric Composite Material (Phase III) FA4819-07-D-0001 62102F 4347 D2 4347D23A Davis...develop novel closed cell foam- nonwoven fabric composites to commercial scale evaluation. Armacell tasks focused on foam optimization for commercial

  18. Open nanoporous morphologies from polymeric blends by carbon dioxide foaming

    NARCIS (Netherlands)

    Krause, B.; Diekmann, K.; van der Vegt, N.F.A.; Wessling, Matthias

    2002-01-01

    We report the formation of open nanoporous polymer films composed of homogeneous polysulfone/polyimide blends. Porosity is introduced by expansion of carbon dioxide-saturated films at elevated temperatures. To interpret details of the porous morphologies in terms of the experimental conditions

  19. Further validation of liquid metal MHD code for unstructured grid based on OpenFOAM

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jingchao; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; He, Qingyun; Ye, Minyou

    2015-11-15

    Highlights: • Specific correction scheme has been adopted to revise the calculating result for non-orthogonal meshes. • The developed MHD code based on OpenFOAM platform has been validated by benchmark cases under uniform and non-uniform magnetic field in round and rectangular ducts. • ALEX experimental results have been used to validate the MHD code based on OpenFOAM. - Abstract: In fusion liquid metal blankets, complex geometries involving contractions, expansions, bends, manifolds are very common. The characteristics of liquid metal flow in these geometries are significant. In order to extend the magnetohydrodynamic (MHD) solver developed on OpenFOAM platform to be applied in the complex geometry, the MHD solver based on unstructured meshes has been implemented. The adoption of non-orthogonal correction techniques in the solver makes it possible to process the non-orthogonal meshes in complex geometries. The present paper focused on the validation of the code under critical conditions. An analytical solution benchmark case and two experimental benchmark cases were conducted to validate the code. Benchmark case I is MHD flow in a circular pipe with arbitrary electric conductivity of the walls in a uniform magnetic field. Benchmark cases II and III are experimental cases of 3D laminar steady MHD flow under fringing magnetic field. In all these cases, the numerical results match well with the benchmark cases.

  20. Crack Initiation and Growth in Rigid Polymeric Closed-Cell Foam Cryogenic Applications

    Science.gov (United States)

    Sayyah, Tarek; Steeve, Brian; Wells, Doug

    2006-01-01

    Cryogenic vessels, such as the Space Shuttle External Tank, are often insulated with closed-cell foam because of its low thermal conductivity. The coefficient of thermal expansion mismatch between the foam and metallic substrate places the foam under a biaxial tension gradient through the foam thickness. The total foam thickness affects the slope of the stress gradient and is considered a significant contributor to the initiation of subsurface cracks. Rigid polymeric foams are brittle in nature and any subsurface cracks tend to propagate a finite distance toward the surface. This presentation investigates the relationship between foam thickness and crack initiation and subsequent crack growth, using linear elastic fracture mechanics, in a rigid polymeric closed-cell foam through analysis and comparison with experimental results.

  1. Fire Resistant Composite Closed Cell Foam and Nonwoven Textiles for Tents and Shelters

    Science.gov (United States)

    2006-01-01

    Shelter Prototype In order to produce sufficient foam, adhesive and coated nonwoven for construction of a small shelter, larger quantities were...AFRL-ML-TY-TR-2006-4571 FIRE RESISTANT COMPOSITE CLOSED CELL FOAM AND NONWOVEN TEXTILES FOR TENTS AND SHELTERS Stephen C. Davis...18 Figure 12. Screening Fire Test of Nonwoven and PVC/NBR Foam Composite

  2. Cell-structure and mechanical properties of closed-cell aluminum foam

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yun(周芸); ZUO Xiao-qing(左孝青); SUN Jia-lin(孙加林); S.R.Nutt

    2004-01-01

    The density, cell size and structure of closed-cell aluminum foam were measured by optical microscopy and image analysis. The properties and the mechanism of compressive deformation that occur in closed-cell aluminum foam were measured and discussed. The results show that the cell size of foam with density of 0.37 mg/m3 is distributed in the range of 0.5 - 4.0 mm. The cell size of foam with density of 0.33 mg/m3 is distributed in the range of 0.5 - 5.0 mm. The cell wall thickness of both types is 0.1 - 0.3 mm. The closed-cell aluminum foam almost belongs to isotropic one, with a variation of ±15% in elastic modulus and yield strength in longitudinal and transverse direction. Under compressive loading, foam materials show inhomogeneous macroscopic deformation. The site of the onset of local plastic deformation depends on the cell structure. The shape of cell is more important than size in determining the yielding susceptibility of the cells. At early stage of deformation,the deformation is localized in narrow bands having width of one cell's diameter, and outside the bands the cell still remains the original shape. The cells within bands experience large permanent deformation. The band normals are usually within 20° of the loading axis.

  3. Novel approach for extinguishing large-scale coal fires using gas-liquid foams in open pit mines.

    Science.gov (United States)

    Lu, Xinxiao; Wang, Deming; Qin, Botao; Tian, Fuchao; Shi, Guangyi; Dong, Shuaijun

    2015-12-01

    Coal fires are a serious threat to the workers' security and safe production in open pit mines. The coal fire source is hidden and innumerable, and the large-area cavity is prevalent in the coal seam after the coal burned, causing the conventional extinguishment technology difficult to work. Foams are considered as an efficient means of fire extinguishment in these large-scale workplaces. A noble foam preparation method is introduced, and an original design of cavitation jet device is proposed to add foaming agent stably. The jet cavitation occurs when the water flow rate and pressure ratio reach specified values. Through self-building foaming system, the high performance foams are produced and then infused into the blast drilling holes at a large flow. Without complicated operation, this system is found to be very suitable for extinguishing large-scale coal fires. Field application shows that foam generation adopting the proposed key technology makes a good fire extinguishment effect. The temperature reduction using foams is 6-7 times higher than water, and CO concentration is reduced from 9.43 to 0.092‰ in the drilling hole. The coal fires are controlled successfully in open pit mines, ensuring the normal production as well as the security of personnel and equipment.

  4. Effect of cell-size on the energy absorption features of closed-cell aluminium foams

    Science.gov (United States)

    Nammi, S. K.; Edwards, G.; Shirvani, H.

    2016-11-01

    The effect of cell-size on the compressive response and energy absorption features of closed-cell aluminium (Al) foam were investigated by finite element method. Micromechanical models were constructed with a repeating unit-cell (RUC) which was sectioned from tetrakaidecahedra structure. Using this RUC, three Al foam models with different cell-sizes (large, medium and small) and all of same density, were built. These three different cell-size pieces of foam occupy the same volume and their domains contained 8, 27 and 64 RUCs respectively. However, the smaller cell-size foam has larger surface area to volume ratio compared to other two. Mechanical behaviour was modelled under uniaxial loading. All three aggregates (3D arrays of RUCs) of different cell-sizes showed an elastic region at the initial stage, then followed by a plateau, and finally, a densification region. The smaller cell size foam exhibited a higher peak-stress and a greater densification strain comparing other two cell-sizes investigated. It was demonstrated that energy absorption capabilities of smaller cell-size foams was higher compared to the larger cell-sizes examined.

  5. Forming foam structures with carbon foam substrates

    Science.gov (United States)

    Landingham, Richard L.; Satcher, Jr., Joe H.; Coronado, Paul R.; Baumann, Theodore F.

    2012-11-06

    The invention provides foams of desired cell sizes formed from metal or ceramic materials that coat the surfaces of carbon foams which are subsequently removed. For example, metal is located over a sol-gel foam monolith. The metal is melted to produce a metal/sol-gel composition. The sol-gel foam monolith is removed, leaving a metal foam.

  6. Development of a Parallel Overset Grid Framework for Moving Body Simulations in OpenFOAM

    Directory of Open Access Journals (Sweden)

    Dominic Chandar

    2015-12-01

    Full Text Available OpenFOAM is an industry-standard Open-Source fluid dynamics code that is used to solve the Navier-Stokes equations for a variety of flow situations. It is currently being used extensively by researchers to study a plethora of physical problems ranging from fundamental fluid dynamics to complex multiphase flows. When it comes to modeling the flow surrounding moving bodies that involve large displacements such as that of ocean risers, sinking of a ship, or the free-flight of an insect, it is cumbersome to utilize a single computational grid and move the body of interest. In this work, we discuss a high-fidelity approach based on overset or overlapping grids which overcomes the necessity of using a single computational grid. The overset library is parallelized using the Message Passing Interface (MPI and Pthreads and is linked dynamically to OpenFOAM. Computational results are presented to demonstrate the potential of this method for simulating problems with large displacements.

  7. Fluid-structure coupling for wind turbine blade analysis using OpenFOAM

    Science.gov (United States)

    Dose, Bastian; Herraez, Ivan; Peinke, Joachim

    2015-11-01

    Modern wind turbine rotor blades are designed increasingly large and flexible. This structural flexibility represents a problem for the field of Computational Fluid Dynamics (CFD), which is used for accurate load calculations and detailed investigations of rotor aerodynamics. As the blade geometries within CFD simulations are considered stiff, the effect of blade deformation caused by aerodynamic loads cannot be captured by the common CFD approach. Coupling the flow solver with a structural solver can overcome this restriction and enables the investigation of flexible wind turbine blades. For this purpose, a new Finite Element (FE) solver was implemented into the open source CFD code OpenFOAM. Using a beam element formulation based on the Geometrically Exact Beam Theory (GEBT), the structural model can capture geometric non-linearities such as large deformations. Coupled with CFD solvers of the OpenFOAM package, the new framework represents a powerful tool for aerodynamic investigations. In this work, we investigated the aerodynamic performance of a state of the art wind turbine. For different wind speeds, aerodynamic key parameters are evaluated and compared for both, rigid and flexible blade geometries. The present work is funded within the framework of the joint project Smart Blades (0325601D) by the German Federal Ministry for Economic Affairs and Energy (BMWi) under decision of the German Federal Parliament.

  8. Numerical simulation of flow around a simplified high-speed train model using OpenFOAM

    Science.gov (United States)

    Ishak, I. A.; Ali, M. S. M.; Shaikh Salim, S. A. Z.

    2016-10-01

    Detailed understanding of flow physics on the flow over a high-speed train (HST) can be accomplished using the vast information obtained from numerical simulation. Accuracy of any simulation in solving and analyzing problems related to fluid flow is important since it measures the reliability of the results. This paper describes a numerical simulation setup for the flow around a simplified model of HST that utilized open source software, OpenFOAM. The simulation results including pressure coefficient, drag coefficient and flow visualization are presented and they agreed well with previously published data. This shows that OpenFOAM software is capable of simulating fluid flows around a simplified HST model. Additionally, the wall functions are implemented in order to minimize the overall number of grid especially near the wall region. This resulted in considerably smaller numbers of mesh resolution used in the current study compared to previous work, which leads to achievement of much reasonable time simulation and consequently reduces the total computational effort without affecting the final outcome.

  9. A method for data handling numerical results in parallel OpenFOAM simulations

    Energy Technology Data Exchange (ETDEWEB)

    Anton, Alin [Faculty of Automatic Control and Computing, Politehnica University of Timişoara, 2" n" d Vasile Pârvan Ave., 300223, TM Timişoara, Romania, alin.anton@cs.upt.ro (Romania); Muntean, Sebastian [Center for Advanced Research in Engineering Science, Romanian Academy – Timişoara Branch, 24" t" h Mihai Viteazu Ave., 300221, TM Timişoara (Romania)

    2015-12-31

    Parallel computational fluid dynamics simulations produce vast amount of numerical result data. This paper introduces a method for reducing the size of the data by replaying the interprocessor traffic. The results are recovered only in certain regions of interest configured by the user. A known test case is used for several mesh partitioning scenarios using the OpenFOAM toolkit{sup ®}[1]. The space savings obtained with classic algorithms remain constant for more than 60 Gb of floating point data. Our method is most efficient on large simulation meshes and is much better suited for compressing large scale simulation results than the regular algorithms.

  10. Fast Response, Open-Celled Porous, Shape Memory Effect Actuators with Integrated Attachments

    Science.gov (United States)

    Jardine, Andrew Peter (Inventor)

    2015-01-01

    This invention relates to the exploitation of porous foam articles exhibiting the Shape Memory Effect as actuators. Each foam article is composed of a plurality of geometric shapes, such that some geometric shapes can fit snugly into or around rigid mating connectors that attach the Shape Memory foam article intimately into the load path between a static structure and a moveable structure. The foam is open-celled, composed of a plurality of interconnected struts whose mean diameter can vary from approximately 50 to 500 microns. Gases and fluids flowing through the foam transfer heat rapidly with the struts, providing rapid Shape Memory Effect transformations. Embodiments of porous foam articles as torsional actuators and approximately planar structures are disposed. Simple, integral connection systems exploiting the ability to supply large loads to a structure, and that can also supply hot and cold gases and fluids to effect rapid actuation are also disposed.

  11. Composite and Nanocomposite Metal Foams

    Directory of Open Access Journals (Sweden)

    Isabel Duarte

    2016-01-01

    Full Text Available Open-cell and closed-cell metal foams have been reinforced with different kinds of micro- and nano-sized reinforcements to enhance their mechanical properties of the metallic matrix. The idea behind this is that the reinforcement will strengthen the matrix of the cell edges and cell walls and provide high strength and stiffness. This manuscript provides an updated overview of the different manufacturing processes of composite and nanocomposite metal foams.

  12. Impaired SIRT1 promotes the migration of vascular smooth muscle cell-derived foam cells.

    Science.gov (United States)

    Zhang, Ming-Jie; Zhou, Yi; Chen, Lei; Wang, Xu; Pi, Yan; Long, Chun-Yan; Sun, Meng-Jiao; Chen, Xue; Gao, Chang-Yue; Li, Jing-Cheng; Zhang, Li-Li

    2016-07-01

    The formation of fat-laden foam cells, contributing to the fatty streaks of the plaques of atheroma, is the critical early process in atherosclerosis. The previous study demonstrated that vascular smooth muscle cells (VSMCs) contain a much larger burden of the excess cholesterol in comparison with monocyte-derived macrophages in human coronary atherosclerosis, as the main origin of foam cells. It is noteworthy that VSMC-derived foam cells are deposited in subintima but not media, where VSMCs normally deposit in. Therefore, migration from media to intima is an indispensable step for a VSMC to accrue neutral lipids and form foam cell. Whether this migration occurs paralleled with or prior to the formation of foam cell is still unclear. Herein, the present study was designed to test the VSMC migratory capability in the process of foam cell formation induced by oxidized low-density lipoprotein (oxLDL). In conclusion, we provide evidence that oxLDL induces the VSMC-derived foam cells formation with increased migration ability and MMP-9 expression, which were partly attributed to the impaired SIRT1 and enhanced nuclear factor-kappa B (NF-κB) activity. As activation of transient receptor potential vanilloid type 1 (TRPV1) has been reported to have anti-atherosclerotic effects, we investigated its role in oxLDL-treated VSMC migration. It is found that activating TRPV1 by capsaicin inhibits VSMC foam cell formation and the accompanied migration through rescuing the SIRT1 and suppressing NF-κB signaling. The present study provides evidence that SIRT1 may be a promising intervention target of atherosclerosis, and raises the prospect of TRPV1 in prevention and treatment of atherosclerosis.

  13. voFoam - A geometrical Volume of Fluid algorithm on arbitrary unstructured meshes with local dynamic adaptive mesh refinement using OpenFOAM

    CERN Document Server

    Maric, Tomislav; Bothe, Dieter

    2013-01-01

    A new parallelized unsplit geometrical Volume of Fluid (VoF) algorithm with support for arbitrary unstructured meshes and dynamic local Adaptive Mesh Refinement (AMR), as well as for two and three dimensional computation is developed. The geometrical VoF algorithm supports arbitrary unstructured meshes in order to enable computations involving flow domains of arbitrary geometrical complexity. The implementation of the method is done within the framework of the OpenFOAM library for Computational Continuum Mechanics (CCM) using the C++ programming language with modern policy based design for high program code modularity. The development of the geometrical VoF algorithm significantly extends the method base of the OpenFOAM library by geometrical volumetric flux computation for two-phase flow simulations. For the volume fraction advection, a novel unsplit geometrical algorithm is developed, which inherently sustains volume conservation utilizing unique Lagrangian discrete trajectories located in the mesh points. ...

  14. HPC realization of a controlled turbulent round jet using OpenFOAM

    CERN Document Server

    Önder, Asim

    2014-01-01

    The present paper investigates high performance computing abilities of OpenFOAM for a low Reynolds number ($Re_D=2000$) axisymmetric jet subject to multiple zero net mass flux (ZNMF) actuators. First, parallel performance of OpenFOAM is tested by performing a scaling study up to $2048$ processors on a supercomputer of Flemish Supercomputer Center(VSC). Then, a method to improve the parallel efficiency is proposed. The method is based on developing a hybrid concept to calculate the statistical moments. This new concept combines ensemble and time averaging in order to allow data sampling in parallel. The motivation is obtaining a reduction in the walltime to collect turbulent statistics which is observed to be the dominating part in the ZNMF controlled jet flow. Employing this parallel statistical averaging approach in combination with regular grid partitioning parallelism, allowed us conducting DNS cases on $P=624$ processors with an overall speed-up of $S_e=540.56$ and a parallel efficiency of $E_e=0.87$. The...

  15. Implementation of a discrete Immersed Boundary Method in OpenFOAM

    CERN Document Server

    Constant, E; Favier, J; Meldi, M; Meliga, P; Serre, E

    2016-01-01

    In this paper, the Immersed Boundary Method (IBM) proposed by Pinelli is implemented for finite volume approximations of incompressible Navier-Stokes equations solutions in the open source toolbox OpenFOAM version 2.2. Solid obstacles are described using a discrete forcing approach for boundary conditions. Unlike traditional approaches encompassing the presence of a solid body using conformal meshes and imposing no-slip boundary conditions on the boundary faces of the mesh, the solid body is here represented on the Eulerian Cartesian mesh through an ad-hoc body force evaluated on a set of Lagrangian markers. The markers can move across the Eulerian mesh, hence allowing for a straightforward analysis of motion or deformation of the body. The IBM method is described and implemented in PisoFOAM, whose Pressure-Implicit Split-Operator (PISO) solver is modified accordingly. The presence of the solid body and the divergence-free of the fluid velocity are imposed simultaneously by sub-iterating between IBM and the p...

  16. Towards full predictions of temperature dynamics in McNary Dam forebay using OpenFOAM

    Directory of Open Access Journals (Sweden)

    Yu-Shi WANG

    2013-07-01

    Full Text Available Hydroelectric facilities impact water temperature; low velocities in a reservoir increase residence time and enhance heat exchange in surface layers. In this study, an unsteady three-dimensional model was developed to predict the temperature dynamics in the McNary Dam forebay. The model is based on the open-source code OpenFOAM. RANS equations with the Boussinesq approximation were used to solve the flow field. A realizable k-ε model that accounts for the production of wind turbulence was developed. Solar radiation and convective heat transfer at the free surface were included. The result of the model was compared with the field data collected on August 18, 2004. Changes in diurnal stratification were adequately predicted by the model. Observed vertical and lateral temperature distributions were accurately captured. Results indicate that the model can be used as a numerical tool to assess structural and operational alternatives to reduce the forebay temperature.

  17. A numerical study on manoeuvrability of wind turbine installation vessel using OpenFOAM

    Directory of Open Access Journals (Sweden)

    Lee Sungwook

    2015-05-01

    Full Text Available In this study, a numerical prediction method on manoeuvrability of Wind Turbine Installation Vessel (WTIV is presented. Planar Motion Mechanism (PMM captive test for the bare hull of WTIV is carried out in the model basin and compared with the numerical results using RANS simulation based on Open-source Field Operation And Manipulation (OpenFOAM calculation to validate the developed method. The manoeuvrability of WTIV with skeg and/or without skeg is investigated using the numerical approach along with the captive model test. In the numerical calculations, the dynamic stability index which indicates the course keeping ability is evaluated and compared for three different hull configurations i.e. bare hull and other two hulls with center skeg and twin skeg. This paper proves that the numerical approach using RANS simulation can be readily applied to estimate the manoeuvrability of WTIV at the initial design stage.

  18. Foam Cushioning

    Science.gov (United States)

    1988-01-01

    One innovation developed by a contractor at Ames Research Center was an open cell polymeric foam material with unusual properties. Intended as padding for aircraft seats the material offered better impact protection against accidents, and also enhanced passenger comfort because it distributed body weight evenly over the entire contact area. Called a slow springback foam, it flows to match the contour of the body pressing against it, and returns to its original shape once the pressure is removed. It has many applications including aircraft cushions and padding, dental stools, and athletic equipment. Now it's used by Dynamic Systems, Inc. for medical applications such as wheel chairs for severely disabled people which allow them to sit for 3-8 hours where they used to be uncomfortable in 15-30 minutes.

  19. Co-doped titanium oxide foam and water disinfection device

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Jian-Ku; Wu, Pinggui; Xie, Rong-Cai

    2016-01-26

    A quaternary oxide foam, comprises an open-cell foam containing (a) a dopant metal, (b) a dopant nonmetal, (c) titanium, and (d) oxygen. The foam has the advantages of a high surface area and a low back pressure during dynamic flow applications. The inactivation of Escherichia coli (E. coli) was demonstrated in a simple photoreactor.

  20. Foam Based Gas Diffusion Electrodes for Reversible Alkaline Electrolysis Cells

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    Alkaline electrolysis cells operated at 250 °C and 40 bar have shown to be able to convert electrical energy into chemical energy in the form of hydrogen at very high efficiencies and power densities. Foam based gas diffusion electrodes and a liquid immobilized electrolyte allow the operation...... of the newly designed electrolysis cell as a fuel cell, but condensation of steam may lead to blocked pores, thereby inhibiting gas diffusion and decreasing the performance of the cell. In the here presented work we present the application of a hydrophobic, porous, and electro-catalytically active layer...... the electrochemical characteristics of the cell. The thickness of the electrolyte matrix was reduced to 200 µm, thereby achieving a serial resistance and area specific resistance as low as 60 mΩ cm2 and 150 mΩ cm2, respectively, at a temperature of 200 °C and 20 bar pressure. A new production method was developed...

  1. On the accuracy of simulations of a 2D boundary layer with RANS models implemented in OpenFoam

    Science.gov (United States)

    Graves, Benjamin J.; Gomez, Sebastian; Poroseva, Svetlana V.

    2013-11-01

    The OpenFoam software is an attractive Computational Fluid Dynamics solver for evaluating new turbulence models due to the open-source nature, and the suite of existing standard model implementations. Before interpreting results obtained with a new model, a baseline for performance of the OpenFoam solver and existing models is required. In the current study we analyze the RANS models in the OpenFoam incompressible solver for two planar (two-dimensional mean flow) benchmark cases generated by the AIAA Turbulence Model Benchmarking Working Group (TMBWG): a zero-pressure-gradient flat plate and a bump-in-channel. The OpenFoam results are compared against both experimental data and simulation results obtained with the NASA CFD codes CFL3D and FUN3D. Sensitivity of simulation results to the grid resolution and model implementation are analyzed. Testing is conducted using the Spalart-Allmaras one-equation model, Wilcox's two-equation k-omega model, and the Launder-Reece-Rodi Reynolds-stress model. Simulations using both wall functions and wall-resolved (low Reynolds number) formulations are considered. The material is based upon work supported by NASA under award NNX12AJ61A.

  2. 二次开模距离对微发泡聚丙烯材料发泡行为的影响%Effect of Twice-open Mold Distance on Micro-foaming Behavior of Polypropylene Material

    Institute of Scientific and Technical Information of China (English)

    龚维; 何颖; 张纯; 朱建华; 何力

    2011-01-01

    采用化学发泡注塑成型技术,在二次开模条件下制备微发泡聚丙烯(P P)材料;通过热力学分析法研究了二次开模距离对PP微发泡材料发泡行为的影响.结果表明:二次开模距离能有效地控制PP材料的发泡过程,二次开模距离越小,体系的发泡过程越容易自发进行.当二次开模距离-=5.3 mm时,体系中的吉布斯自由能小于零,发泡过程不可能自发进行;二次开模距离L=4.3 mm时,PP体系的发泡质量最理想,泡孔平均直径为21.6 μm,泡孔密度为5 63×106个/cm3,能够获得泡孔细小、均匀的徽发泡PP材料.%By taking chemical foaming Injection molding technology, the microcellular foam polypropylene(PP) materials were made under the condition of twice-open mold. The effect of different twice-open mold distance on foaming behavior of PP materials was analyzed by means of thermodynamic analysis. The results show that twice-open mold distance can effectively control foaming process of PP materials, the smaller twice-open mold distance, the easier foaming process of PP materials proceed spontaneously. When twice-open mold distance(L) is 5.3 mm, Gibbs free energy ΔG is below zero, and the foaming process can't proceed spontaneously; when L is 4.3 mm, there is an ideal foaming effect in microcellular foam PP materials, average cell diameter is 21.6 μm, and cell density is 5.63×106 pcs/cm3; and then the micro-foaming PP material with fine and uniform foam cell is obtained.

  3. Analysis on capabilities of density-based solvers within OpenFOAM to distinguish aerothermal variables in diffusion boundary layer

    Institute of Scientific and Technical Information of China (English)

    Shen Chun; Sun Fengxian; Xia Xinlin

    2013-01-01

    Open source field operation and manipulation (OpenFOAM) is one of the most preva-lent open source computational fluid dynamics (CFD) software. It is very convenient for researchers to develop their own codes based on the class library toolbox within OpenFOAM. In recent years, several density-based solvers within OpenFOAM for supersonic/hypersonic compressible flow are coming up. Although the capabilities of these solvers to capture shock wave have already been ver-ified by some researchers, these solvers still need to be validated comprehensively as commercial CFD software. In boundary layer where diffusion is the dominant transportation manner, the con-vective discrete schemes’ capability to capture aerothermal variables, such as temperature and heat flux, is different from each other due to their own numerical dissipative characteristics and from viewpoint of this capability, these compressible solvers within OpenFOAM can be validated further. In this paper, firstly, the organizational architecture of density-based solvers within OpenFOAM is analyzed. Then, from the viewpoint of the capability to capture aerothermal vari-ables, the numerical results of several typical geometrical fields predicted by these solvers are com-pared with both the outcome obtained from the commercial software Fastran and the experimental data. During the computing process, the Roe, AUSM+(Advection Upstream Splitting Method), and HLLC(Harten-Lax-van Leer-Contact) convective discrete schemes of which the spatial accu-racy is 1st and 2nd order are utilized, respectively. The compared results show that the aerothermal variables are in agreement with results generated by Fastran and the experimental data even if the 1st order spatial precision is implemented. Overall, the accuracy of these density-based solvers can meet the requirement of engineering and scientific problems to capture aerothermal variables in diffusion boundary layer.

  4. Foam cells generated by a combination of hyperglycemia and hyperlipemia in rats.

    Science.gov (United States)

    Sano, Jun-ichi; Shirakura, Shiro; Oda, Shoji; Hara, Takuji; Ishihara, Tokuhiro

    2004-12-01

    Diabetes is a major risk factor for atherosclerosis, as well as hyperlipemia. Investigators have suggested that denatured lipoprotein in hyperglycemia transforms macrophages into foam cells, which correlates with the development or progression of atherosclerosis. In the present study, we examined the generation of foam cells in rats caused by a combination of hyperglycemia and hyperlipemia. Streptozotocin-induced diabetic male Wister rats were fed a high cholesterol diet (HCD) containing 1% cholesterol and 0.5% cholic acid to maintain a hyperglycemic and hyperlipemic state. Animals fed the HCD for 8 weeks or longer showed a high incidence of foam cell accumulation in the renal glomerulus, intima of aortic arch, splenic red pulp and marginal zone, liver sinusoid and intestinal lamina propria. The foam cells exhibited positive staining for antimonocyte/macrophage antibody and lipids in all these tissues. Anti-rat apolipoprotein B (apo B) antibody revealed that positive staining existed only in the cytoplasm of glomerular foam cells. These results suggest that the origin of these foam cells can be attributed to lipid-laden macrophages. The generation of foam cells in the hyperglycemia-hyperlipidemia supervening rat model presented in the present study might be a useful tool for investigations of the pathogenesis of foam cells.

  5. Towards numerical simulation of turbulent hydrogen combustion based on flamelet generated manifolds in OpenFOAM

    Science.gov (United States)

    Fancello, A.; Bastiaans, R. J. M.; de Goey, L. P. H.

    2013-10-01

    This work proposes an application of the Flamelet-Generated Manifolds (FGM) technique in the OpenFOAM environment. FGM is a chemical reduced method for combustion modeling. This technique treats the combustion process as the solution of a small amount of controlling variables. Regarding laminar simulation, a progress variable and enthalpy evolution can describe satisfactorily the problem. From a turbulent point of view, FGM can be applied to LES and RANS simulations, where the subgrid chemical terms are described with a β - PDF approach. These approaches apply satisfactorily in relatively simple gases, nevertheless for hydrogen are not more valid, due to preferential diffusion effects and instability of the flame structure. The overall aim of this research is to find technical solution for hydrogen gas turbines design in the next generation of Integrated Gasification Combined Cycle (IGCC) plants.

  6. Comparison of OpenFOAM and EllipSys3D actuator line methods with (NEW) MEXICO results

    DEFF Research Database (Denmark)

    Nathan, J.; Meyer Forsting, Alexander Raul; Troldborg, Niels

    2017-01-01

    such as the MEXICO experiment. Often the verification against other codes were made on a very broad scale. Therefore this study attempts first a validation by comparing two different implementations, namely an adapted version of SOWFA/OpenFOAM and EllipSys3D and also a verification by comparing against experimental...... results from the MEXICO and NEW MEXICO experiments....

  7. Styrene-based shape memory foam: fabrication and mathematical modeling

    Science.gov (United States)

    Yao, Yongtao; Zhou, Tianyang; Qin, Chao; Liu, Yanju; Leng, Jinsong

    2016-10-01

    Shape memory polymer foam is a promising kind of structure in the biomedical and aerospace field. Shape memory styrene foam with uniform and controlled open-cell structure was successfully fabricated using a salt particulate leaching method. Shape recovery capability exists for foam programming in both high-temperature compression and low-temperature compression (Ashby as well as differential micromechanics theory were applied to predict Young’s modulus and the mechanical behavior of SMP styrene foams during the compression process.

  8. Infiltrated carbon foam composites

    Science.gov (United States)

    Lucas, Rick D. (Inventor); Danford, Harry E. (Inventor); Plucinski, Janusz W. (Inventor); Merriman, Douglas J. (Inventor); Blacker, Jesse M. (Inventor)

    2012-01-01

    An infiltrated carbon foam composite and method for making the composite is described. The infiltrated carbon foam composite may include a carbonized carbon aerogel in cells of a carbon foam body and a resin is infiltrated into the carbon foam body filling the cells of the carbon foam body and spaces around the carbonized carbon aerogel. The infiltrated carbon foam composites may be useful for mid-density ablative thermal protection systems.

  9. Tensile property of Al-Si closed-cell aluminum foam

    Institute of Scientific and Technical Information of China (English)

    YU Hai-jun; YAO Guang-chun; LIU Yi-han

    2006-01-01

    Al-Si closed-cell aluminum foams of different densities were prepared by molten body transitional foaming process. The tensile behavior of Al-Si closed-cell aluminum foam was studied and the influence of relative densities on the tensile strength and elastic modulus was also researched. The results show that the fracture surfaces of Al-Si closed-cell aluminum foam display quasi-cleavage fiacture consisting of brittle cleavages and ductile dimples. The tensile strength and elastic modulus are strictly affected by the relative density of Al-Si closed-cell aluminum foam. With increasing relative density, the tensile strength increases and the strain at which the peak strength is measured also increases; in addition, the elastic modulus increases with increasing relative density.

  10. Numerical modelling of closed-cell aluminium foams under shock loading

    Science.gov (United States)

    Kader, M. A.; Islam, M. A.; Hazell, P. J.; Escobedo, J. P.; Saadatfar, M.; Brown, A. D.

    2017-01-01

    The present research numerically investigates shock propagation through closed-cell aluminium foam via flyer-plate impact. The mechanics of foam deformation was elucidated using the finite element (FE) software ABAQUS/explicit. X-ray computed micro-tomography was performed to render a full 3D foam geometry mesh for understanding detailed macrostructural response due to shock propagation. Elastic wave propagation and pore collapse mechanism with time were studied. The free surface velocity of the foam was measured at two different flyer-plate impact velocities to observe the profile of the shock wave with time. Good correlations were observed between experimental data and FE predictions for both test conditions.

  11. Preparation of Desirable Porous Cell Structure Polylactide/Wood Flour Composite Foams Assisted by Chain Extender

    Directory of Open Access Journals (Sweden)

    Youyong Wang

    2017-08-01

    Full Text Available Polylactide (PLA/wood flour composite foam were prepared through a batch foaming process. The effect of the chain extender on the crystallization behavior and dynamic rheological properties of the PLA/wood flour composites were investigated as well as the crystal structure and cell morphology of the composite foams. The incorporation of the chain extender enhanced the complex viscosity and storage modulus of PLA/wood flour composites, indicating the improved melt elasticity. The chain extender also led to a decreased crystallization rate and final crystallinity of PLA/wood flour composites. With an increasing chain extender content, a finer and more uniform cell structure was formed, and the expansion ratio of PLA/wood flour composite foams was much higher than without the chain extender. Compared to the unfoamed composites, the crystallinity of the foamed PLA/wood flour composites was improved and the crystal was loosely packed. However, the new crystalline form was not evident.

  12. Micro-Computed Tomography and Finite Element Method Study of Open-Cell Porous Materials

    Directory of Open Access Journals (Sweden)

    Wejrzanowski Tomasz

    2015-01-01

    Full Text Available In the present paper the characterization of structure and properties of open-cell porous materials by high-resolution x-ray micro-computed tomography (μCT and finite element method (FEM is addressed. The unique properties of open porosity foams make them interesting in a range of applications in science and engineering such as energy absorbers, lightweight construction materials or heat insulators. Consequently, a detailed knowledge of structure as well as mechanical properties (i.e. Young’s Modulus, Poisson’s Ratio of such foams is essential. The resulting pixel size of the μCT was 40 μm, which enabled satisfactory visualization of the complex foam structure and quantitative characterization. Foam morphology was studied on post-processed computed tomography images, while mechanical properties were analyzed with use of the finite element method on numerical model obtained from μCT results.

  13. Comparison between OpenFOAM CFD & BEM theory for variable speed – variable pitch HAWT

    Directory of Open Access Journals (Sweden)

    ElQatary Islam

    2014-01-01

    Full Text Available OpenFoam is used to compare computational fluid dynamics (CFD with blade element momentum theory (BEM for a variable speed - variable pitch HAWT (Horizontal Axis Wind Turbine. The wind turbine is first designed using the BEM to determine the blade chord, twist and operating conditions. The wind turbine blade has an outer diameter of 14 m, uses a NACA 63–415 profile for the entire blade and root to tip twist distribution of 15deg (Figure 3. The RPM varies from 20–75 for freestream velocities varying between 3–10.5 m/s (variable speed and a constant RPM of 78.78 for velocities ranging between 11–25 m/s (variable pitch. OpenFOAM is used to investigate the wind turbine performance at several operating points including cut-in wind speed (3 m/s, rated wind speed (10.5 m/s and in the variable pitch zone. Simulation results show that in the variable-speed operating range, both CFD and BEM compare reasonably well. This agreement can be attributed to the fact that the complex three-dimensional flow around the turbine blades can be split into two radial segments. For radii less than the mid-span, the flow is three-dimensional, whereas for radii greater than the mid-span, the flow is approximately two-dimensional. Since the majority of the power is produced from sections beyond the mid-span, the agreement between CFD and BEM is reasonable. For the variable-pitch operating range the CFD results and BEM deviate considerably. In this case the majority of the power is produced from the inner sections in which the flow is three-dimensional and can no longer be predicted by the BEM. The results show that differences in pitch angles up to 10deg can result to regulate the power for high wind speeds in the variable-pitch operation zone.

  14. Macropinocytosis contributes to the macrophage foam cell formation in RAW264.7 cells

    Institute of Scientific and Technical Information of China (English)

    Wenqi Yao; Ke Li; Kan Liao

    2009-01-01

    The key event in the atherosclerosis development is the lipids uptake by macrophage and the formation of foam cell in subendothelial arterial space. Besides the uptake of modified low-density lipoprotein (LDL) by scavenger receptor-mediated endocytosis, macrophages possess constitutive macropinocytosis, which is capable of taking up a large quantity of solute. Macrophage foam cell formation could be induced in RAW264.7 cells by increasing the serum concentration in the culture medium. Foam cell formation induced by serum could be blocked by phosphoinositide 3-kinase inhibi-tor, LY294002 or wortmannin, which inhibited macro-pinocytosis but not receptor-mediated endocytosis. Further analysis indicated that macropinocytosis took place at the gangliosides-enriched membrane area. Cholesterol depletion by β-methylcyclodextrin-blocked macropinocytosis without affecting scavenger receptor-mediated endocytosis of modified LDLs. These results suggested that macropinocytosis might be one of the important mechanisms for lipid uptake in macrophage. And it made significant contribution to the lipid accumulation and foam cell formation.

  15. Effects of everolimus on macrophage-derived foam cell behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Steven, E-mail: steven.hsu@av.abbott.com [Abbott Vascular, 3200 Lakeside Drive, Santa Clara, CA 95054 (United States); Koren, Eugen; Chan, Yen; Koscec, Mirna; Sheehy, Alexander [Abbott Vascular, 3200 Lakeside Drive, Santa Clara, CA 95054 (United States); Kolodgie, Frank; Virmani, Renu [CVPath Institute, Inc., 19 Firstfield Road, Gaithersburg, MD 20878 (United States); Feder, Debra [Abbott Vascular, 3200 Lakeside Drive, Santa Clara, CA 95054 (United States)

    2014-07-15

    Purpose: The purpose of this study was to investigate the effects of everolimus on foam cell (FC) viability, mRNA levels, and inflammatory cytokine production to better understand its potential inhibitory effects on atheroma progression. Methods and materials: Human THP1 macrophage-derived FC were formed using acetylated LDL (acLDL, 100 μg/mL) for 72 hours, followed by everolimus treatment (10{sup -5}–10{sup -11} M) for 24 hours. FC viability was quantified using fluorescent calcein AM/DAPI staining. FC lysates and media supernatants were analyzed for apoptosis and necrosis using a Cell Death ELISA{sup PLUS} assay. FC lysates and media supernatants were also analyzed for inflammatory cytokine (IL1β, IL8, MCP1, TNFα) mRNA levels and protein expression using quantitative reverse transcription real-time polymerase chain reaction (QPCR) and a Procarta® immunoassay, respectively. mRNA levels of autophagy (MAP1LC3), apoptosis (survivin, clusterin), and matrix degradation (MMP1, MMP9) markers were evaluated by Quantigene® Plex assay and verified with QPCR. Additionally, hypercholesterolemic rabbits received everolimus-eluting stents (EES) for 28 or 60 days. RAM-11 immunohistochemical staining was performed to compare %RAM-11 positive area between stented sections and unstented proximal sections. Statistical significance was calculated using one-way ANOVA (p ≤ 0.05). Results: Calcein AM/DAPI staining showed that FC exposed to everolimus (10{sup -5} M) had significantly decreased viability compared to control. FC apoptosis was significantly increased at a high dose of everolimus (10{sup -5} M), with no necrotic effects at any dose tested. Everolimus did not affect endothelial (HUVEC) and smooth muscle (HCASMC) cell apoptosis or necrosis. Everolimus (10{sup -5} M) significantly increased MAP1LC3, caused an increased trend in clusterin (p = 0.10), and significantly decreased survivin and MMP1 mRNA levels in FC. MCP1 cytokine mRNA levels and secreted protein

  16. TiO2 hierarchical porous film constructed by ultrastable foams as photoanode for quantum dot-sensitized solar cells

    Science.gov (United States)

    Du, Xing; He, Xuan; Zhao, Lei; Chen, Hui; Li, Weixin; Fang, Wei; Zhang, Wanqiu; Wang, Junjie; Chen, Huan

    2016-11-01

    It reported a novel and simple method for the first time to prepare TiO2 hierarchical porous film (THPF) using ultrastable foams as a soft template to construct porous structures. Moreover, dodecanol as one foam component was creatively used as solvent during the synthesis of CdSe quantum dots (QDs) to decrease reaction temperature and simplify precipitation process. The result showed that hierarchical pores in scale of microns introduced by foams were regarded to benefit for high coverage and unimodal distribution of QDs on the surface of THPF to increase the efficiencies of light-harvesting, charge-collection and charge-transfer. The increased efficiencies caused an enhancement in quantum efficiency of the cell and thus remarkably increased the short circuit current density (Jsc). In addition, the decrease of charge recombination resulted in the increase of the open circuit voltage (Voc) as well. The QDSSC based on THPF exhibited about 2-fold higher power conversion efficiency (η = 2.20%, Jsc = 13.82 mA cm-2, Voc = 0.572 V) than that of TiO2 nanoparticles film (TNF) (η = 1.06%, Jsc = 6.70 mA cm-2, Voc = 0.505 V). It provided a basis to use foams both as soft template and carrier to realize simultaneously construction and in-situ sensitization of photoanode in further work.

  17. Biogas biodesulfurization in an anoxic biotrickling filter packed with open-pore polyurethane foam.

    Science.gov (United States)

    Fernández, Maikel; Ramírez, Martín; Gómez, José Manuel; Cantero, Domingo

    2014-01-15

    Biogas biodesulfurization by an anoxic biotrickling filter packed with open pore polyurethane foam at the laboratory scale (packed volume 2.4L) has been studied. The biotrickling system was operated for 620 days with biogas supplied continuously and two nitrate feeding regimes were tested (manual and programmed). Biomass immobilization was carried out under the manual nitrate feeding regime and a study was then carried out on the effects on removal efficiency of the following parameters: nitrate source, H2S inlet load, nitrate concentration, sulfate accumulation, temperature, pH and trickling liquid velocity. The effect of increased H2S inlet load was studied under the programmed nitrate feeding regime. The results show that a removal efficiency of 99% can be obtained when working under the following conditions: inlet loads below 130gSm(-3)h(-1), a programmed nitrate feeding system, temperature of 30°C, sulfate concentration below 33gL(-1), a pH between 7.3 and 7.5, and a trickling liquid velocity higher than 4.6mh(-1).

  18. Microcellular foam injection molding with cellulose nanofibers (CNFs)

    Science.gov (United States)

    Ohshima, Masahiro; Kubota, Masaya; Ishihara, Shota; Hikima, Yuta; Sato, Akihiro; Sekiguchi, Takafumi

    2016-03-01

    Cellulose nanofibers (CNFs) nanocomposites polypropylene foams are prepared by microcellular foam injection molding with core-back operation. The modified CNFs were blended with isotactic-polypropylene (i-PP) at different CNFs weight percentages and foamed to investigate the effect of CNFs on cell morphology. CNFs in i-PP increased the elastic modulus and induced a strain hardening behavior. CNFs also shifted the crystallization temperature of i-PP to higher temperature and enhanced crystallization. With these changes in rheological and thermal properties, CNFs could reduce the cell size and increase the cell density of the foams. By adjusting the core-back timing i.e., foaming temperature, the closed cell and the nano-fibrillated open cellular structure could be produced. The flexural modulus and bending strength of foams were measured by three point flexural tester. The flexural modulus and bending strength were increased as the CNFs content in i-PP was increased at any foam expansion ratio.

  19. CFD RANS Simulations on a Generic Conventional Scale Model Submarine: Comparison between Fluent and OpenFOAM

    Science.gov (United States)

    2015-09-01

    functions have such a small effect on the simulated value for the drag coefficient as the switch to the laminar behaviour at y+ ~ 11 would be...to explain the source of these differences. The modification to the wall functions in OpenFOAM described in Section 6 partially explains the...model currently implemented in Fluent incorporates modifications for low Reynolds number effects, compressibility and shear flow spreading [11]. The

  20. Processing of CuAlMn Shape Memory Foams with Open Spherical Pores by Silica-Gel Beads Infiltration Method

    Science.gov (United States)

    Li, Hua; Yuan, Bin; Gao, Yan

    2016-10-01

    A molten metal infiltration process with amorphous SiO2 (silica-gel) beads as space holders was used to prepare Cu-based shape memory foams in this article. We found that the silica-gel beads with micropores inside expanded when being heated to elevated temperatures and that proper control of the expansion of silica-gel beads helped form necks between the beads with different bonding extent, which had been taken advantage of to have a good control of the foam morphology and porosity, by carefully designing suitable procedures and choosing proper parameters for the process. In addition, we studied in detail the effect of heating temperature, silica-gel bead density, and infiltration pressure of the present process on the morphology and porosity of CuAlMn shape memory foams. By coordinating these three key parameters, CuAlMn shape memory foams with open spherical pores and adjustable porosity from 66 to 85 pct were reliably produced.

  1. Acceleration of the OpenFOAM-based MHD solver using graphics processing units

    Energy Technology Data Exchange (ETDEWEB)

    He, Qingyun; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; Feng, Jingchao

    2015-12-15

    Highlights: • A 3D PISO-MHD was implemented on Kepler-class graphics processing units (GPUs) using CUDA technology. • A consistent and conservative scheme is used in the code which was validated by three basic benchmarks in a rectangular and round ducts. • Parallelized of CPU and GPU acceleration were compared relating to single core CPU in MHD problems and non-MHD problems. • Different preconditions for solving MHD solver were compared and the results showed that AMG method is better for calculations. - Abstract: The pressure-implicit with splitting of operators (PISO) magnetohydrodynamics MHD solver of the couple of Navier–Stokes equations and Maxwell equations was implemented on Kepler-class graphics processing units (GPUs) using the CUDA technology. The solver is developed on open source code OpenFOAM based on consistent and conservative scheme which is suitable for simulating MHD flow under strong magnetic field in fusion liquid metal blanket with structured or unstructured mesh. We verified the validity of the implementation on several standard cases including the benchmark I of Shercliff and Hunt's cases, benchmark II of fully developed circular pipe MHD flow cases and benchmark III of KIT experimental case. Computational performance of the GPU implementation was examined by comparing its double precision run times with those of essentially the same algorithms and meshes. The resulted showed that a GPU (GTX 770) can outperform a server-class 4-core, 8-thread CPU (Intel Core i7-4770k) by a factor of 2 at least.

  2. SediFoam: A general-purpose, open-source CFD-DEM solver for particle-laden flow with emphasis on sediment transport

    Science.gov (United States)

    Sun, Rui; Xiao, Heng

    2016-04-01

    With the growth of available computational resource, CFD-DEM (computational fluid dynamics-discrete element method) becomes an increasingly promising and feasible approach for the study of sediment transport. Several existing CFD-DEM solvers are applied in chemical engineering and mining industry. However, a robust CFD-DEM solver for the simulation of sediment transport is still desirable. In this work, the development of a three-dimensional, massively parallel, and open-source CFD-DEM solver SediFoam is detailed. This solver is built based on open-source solvers OpenFOAM and LAMMPS. OpenFOAM is a CFD toolbox that can perform three-dimensional fluid flow simulations on unstructured meshes; LAMMPS is a massively parallel DEM solver for molecular dynamics. Several validation tests of SediFoam are performed using cases of a wide range of complexities. The results obtained in the present simulations are consistent with those in the literature, which demonstrates the capability of SediFoam for sediment transport applications. In addition to the validation test, the parallel efficiency of SediFoam is studied to test the performance of the code for large-scale and complex simulations. The parallel efficiency tests show that the scalability of SediFoam is satisfactory in the simulations using up to O(107) particles.

  3. Cellular uptake of a dexamethasone palmitate-low density lipoprotein complex by macrophages and foam cells.

    Science.gov (United States)

    Tauchi, Yoshihiko; Chono, Sumio; Morimoto, Kazuhiro

    2003-04-01

    To evaluate the utility of a dexamethasone palmitate (DP)-low density lipoprotein (LDL) complex to transport drug into foam cells, the cellular uptake of DP-LDL complex by macrophages and foam cells was examined. The DP-LDL complex was prepared by incubation with DP and LDL, and the DP-LDL complex and murine macrophages were incubated. No cellular uptake of the DP-LDL complex by macrophages was found until 6 h after the start of incubation, but this gradually increased from 12 to 48 h. On the other hand, the cellular uptake of the oxidized DP-LDL complex was already apparent at 3 h after the start incubation, and then markedly increased until 48 h incubation along with that of the lipid emulsion (LE) containing DP (DP-LE). The cellular uptake of DP-LE by foam cells was significantly lower than that by macrophages. However, the cellular uptake of DP-LDL complex by foam cells was similar to that by macrophages. These findings suggest that the DP-LDL complex is oxidatively modified, and then incorporated into macrophages and foam cells through the scavenger receptor pathway. Since selective delivery of drugs into foam cells in the early stage of atherosclerosis is a useful protocol for antiatherosclerosis treatment, the DP-LDL complex appears to be a potentially useful drug-carrier complex for future antiatherosclerotic therapy.

  4. Cell adhesive ability of a biological foam ceramic with surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yong; Li Xiaoyu; Feng Fan; Lin Yunfeng [West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Liao Yunmao [State Key Laboratory of Oral Diseases, Chengdu 610044 (China); Tian, Weidong [State Key Laboratory of Oral Diseases, Chengdu 610044 (China)], E-mail: drtwd@sina.com; Liu Lei [West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)], E-mail: drliulei@163.com

    2008-11-15

    Biological foam ceramic is a promising material for tissue engineering scaffold because of its biocompatibility, biodegradation and adequate pores measured from micrometer to nanometers. The aim of this study was to evaluate the adhesion and proliferation of adipose-derived stromal cells (ADSCs) on the biological foam ceramic coated with fibronectin. ADSCs were harvested from SD rats and passaged three times prior to seeding onto biological foam surface modified with fibronectin (50 {mu}g/ml). Scaffold without surface modification served as control. To characterize cellular attachment, cells were incubated on the scaffold for 1 h and 3 h and then the cells attached onto the scaffold were counted. The difference of proliferation was appraised using MTT assay at day 1, 3, 5 and 7 before the cells reached confluence. After 7 days of culture, scanning electron microscope (SEM) was chosen to assess cell morphology and attachment of ADSCs on the biological foam ceramic. Attachment of ADSCs on the biological foam ceramic surface modified with fibronectin at 1 h or 3 h was substantially greater than that in control. MTT assay revealed that ADSCs proliferation tendency of the experimental group was nearly parallel to that of control. SEM view showed that ADSCs in the experimental groups connected more tightly and excreted more collagen than that in control. The coating of fibronectin could improve the cell adhesive ability of biological foam ceramics without evident effect on proliferation.

  5. Cytokines, macrophage lipid metabolism and foam cells: implications for cardiovascular disease therapy.

    Science.gov (United States)

    McLaren, James E; Michael, Daryn R; Ashlin, Tim G; Ramji, Dipak P

    2011-10-01

    Cardiovascular disease is the biggest killer globally and the principal contributing factor to the pathology is atherosclerosis; a chronic, inflammatory disorder characterized by lipid and cholesterol accumulation and the development of fibrotic plaques within the walls of large and medium arteries. Macrophages are fundamental to the immune response directed to the site of inflammation and their normal, protective function is harnessed, detrimentally, in atherosclerosis. Macrophages contribute to plaque development by internalizing native and modified lipoproteins to convert them into cholesterol-rich foam cells. Foam cells not only help to bridge the innate and adaptive immune response to atherosclerosis but also accumulate to create fatty streaks, which help shape the architecture of advanced plaques. Foam cell formation involves the disruption of normal macrophage cholesterol metabolism, which is governed by a homeostatic mechanism that controls the uptake, intracellular metabolism, and efflux of cholesterol. It has emerged over the last 20 years that an array of cytokines, including interferon-γ, transforming growth factor-β1, interleukin-1β, and interleukin-10, are able to manipulate these processes. Foam cell targeting, anti-inflammatory therapies, such as agonists of nuclear receptors and statins, are known to regulate the actions of pro- and anti-atherogenic cytokines indirectly of their primary pharmacological function. A clear understanding of macrophage foam cell biology will hopefully enable novel foam cell targeting therapies to be developed for use in the clinical intervention of atherosclerosis.

  6. Design and Optimization of OpenFOAM-based CFD Applications for Modern Hybrid and Heterogeneous HPC Platforms

    KAUST Repository

    AlOnazi, Amani A.

    2014-02-01

    The progress of high performance computing platforms is dramatic, and most of the simulations carried out on these platforms result in improvements on one level, yet expose shortcomings of current CFD packages. Therefore, hardware-aware design and optimizations are crucial towards exploiting modern computing resources. This thesis proposes optimizations aimed at accelerating numerical simulations, which are illus- trated in OpenFOAM solvers. A hybrid MPI and GPGPU parallel conjugate gradient linear solver has been designed and implemented to solve the sparse linear algebraic kernel that derives from two CFD solver: icoFoam, which is an incompressible flow solver, and laplacianFoam, which solves the Poisson equation, for e.g., thermal dif- fusion. A load-balancing step is applied using heterogeneous decomposition, which decomposes the computations taking into account the performance of each comput- ing device and seeking to minimize communication. In addition, we implemented the recently developed pipeline conjugate gradient as an algorithmic improvement, and parallelized it using MPI, GPGPU, and a hybrid technique. While many questions of ultimately attainable per node performance and multi-node scaling remain, the ex- perimental results show that the hybrid implementation of both solvers significantly outperforms state-of-the-art implementations of a widely used open source package.

  7. Evaluation of foaming polypropylene modified with ramified polymer

    OpenAIRE

    Demori,Renan; Azeredo,Ana Paula de; Liberman, Susana Alcira; Mauler,Raquel Santos

    2015-01-01

    Polypropylene foams have great industrial interest because of balanced physical and mechanical properties, recyclability as well as low material cost. During the foaming process, the elongational forces applied to produce the expanded polymer are strong enough to rupture cell walls. As a result, final foam has a high amount of coalesced as well as opened cells which decreases mechanical and also physical properties. To increase melt strength and also avoid the coalescence effect, one of the c...

  8. Damping capacity and compressive characteristic in some aluminum foams

    Institute of Scientific and Technical Information of China (English)

    程和法; 黄笑梅; 魏建宁; 韩福生

    2003-01-01

    The compressive behavior, energy absorption and damping capacity of Al-28% Zn alloy foam, Al-10% Mg alloy foam and commercial pure aluminum foam with open cell were investigated. The Al-28 % Zn alloy foam exhibits the typical deformation behavior of brittle foam in static compression, and a much higher energy absorption capacity than the Al-10%Mg alloy foam and pure aluminum foam to the densification strain. Over a large plastic strain range, the energy absorption efficiency of the Al-28 % Zn alloy foam keeps nearly constant and above 80%. The experiments on the internal friction of the three foams are also conducted on a multifunction internal friction apparatus (MFIFA). The Al-28%Zn alloy foam exhibits a high damping capacity which is three to four times larger than those of the pure aluminum foam and Al-28%Mg alloy foam around room temperature. The mechanism for the high damping capacity of the foamed Al-28%Zn alloy may be associated with the viscous sliding at the interface between the soft phase α and the brittle rich Zn phase η in its base metal during vibration.

  9. Dynamic crushing response of closed-cell aluminium foams during shock loading

    Science.gov (United States)

    Islam, M. A.; Kader, M. A.; Hazell, P. J.; Escobedo-Diaz, J. P.; Brown, A. D.; Appleby-Thomas, G. J.; Saadatfar, M.; Quadir, M. Z.

    2017-01-01

    Understanding the impact response of aluminium foams is essential for assessing their energy absorption capacity under dynamic loading. In this paper, the dynamic compaction behavior of closed-cell aluminium foam (CYMAT ™) has been tested using the plate-impact technique. Post-impacted samples have been examined using optical microscopy to observe the microstructural changes with the objective of elucidating the pore-collapse mechanism.

  10. Effect of TiH2 on preparation of closed-cell aluminum foam and its compressive behavior

    Institute of Scientific and Technical Information of China (English)

    YANG Guo-jun; YU Hai-jun; YAO Guang-chun

    2006-01-01

    The vesicant problem during the process of preparing closed-cell aluminum foam by molten body transitional foaming process was discussed and the effect of granularity and addition of TiH2 on porosity of closed-cell aluminum foam was investigated.The static compressive behavior of closed-cell aluminum foam and the influence of porosity on static compressive property of closed-cell aluminum foam were researched as well. The results show that with increasing granularity of TiH2, the porosity of closed-cell aluminum foam firstly increases and then decreases gradually, the granularity should be controlled in the range of 38-74 μm which can result in higher porosity. The porosity of closed-cell aluminum foam increases with the increasing addition of TiH2,and the addition of TiH2 should be controlled from 1.5% to 2.5% which can result in homogeneous cell and moderate strength of closed-cell aluminum foam. The compressive process of closed-cell aluminum foam obviously displays linear elastic phase, plastic collapse phase, and densification phase, and the compressive strength grows with decreasing porosity.

  11. Monocytes from HIV+ individuals show impaired cholesterol efflux and increased foam cell formation after transendothelial migration

    Science.gov (United States)

    MAISA, Anna; HEARPS, Anna C.; ANGELOVICH, Thomas A.; PEREIRA, Candida F.; ZHOU, Jingling; SHI, Margaret D.Y.; PALMER, Clovis S.; MULLER, William A.; CROWE, Suzanne M.; JAWOROWSKI, Anthony

    2016-01-01

    Design HIV+ individuals have an increased risk of atherosclerosis and cardiovascular disease which is independent of antiretroviral therapy and traditional risk factors. Monocytes play a central role in the development of atherosclerosis, and HIV-related chronic inflammation and monocyte activation may contribute to increased atherosclerosis, but the mechanisms are unknown. Methods Using an in vitro model of atherosclerotic plaque formation, we measured the transendothelial migration of purified monocytes from age-matched HIV+ and uninfected donors and examined their differentiation into foam cells. Cholesterol efflux and the expression of cholesterol metabolism genes were also assessed. Results Monocytes from HIV+ individuals showed increased foam cell formation compared to controls (18.9% vs 0% respectively, p=0.004) and serum from virologically suppressed HIV+ individuals potentiated foam cell formation by monocytes from both uninfected and HIV+ donors. Plasma TNF levels were increased in HIV+ vs control donors (5.9 vs 3.5 pg/ml, p=0.02) and foam cell formation was inhibited by blocking antibodies to TNF receptors, suggesting a direct effect on monocyte differentiation to foam cells. Monocytes from virologically suppressed HIV+ donors showed impaired cholesterol efflux and decreased expression of key genes regulating cholesterol metabolism, including the cholesterol transporter ABCA1 (p=0.02). Conclusions Monocytes from HIV+ individuals show impaired cholesterol efflux and are primed for foam cell formation following trans-endothelial migration. Factors present in HIV+ serum, including elevated TNF levels, further enhance foam cell formation. The pro-atherogenic phenotype of monocytes persists in virologically suppressed HIV+ individuals and may contribute mechanistically to increased atherosclerosis in this population. PMID:26244384

  12. TREM-1 is a positive regulator of TNF-α and IL-8 production in U937 foam cells.

    Science.gov (United States)

    Wang, Yu-Shi; Li, Xiang-Jun; Zhao, Wai-Ou

    2012-05-01

    The purpose of our study was to investigate the expression levels of TREM-1 (triggering receptor expressed on myeloid cells-1) in U937 foam cells and determine whether TREM-1 regulates the production of tumor necrosis factor-alpha and interleukin-8 in these cells. Human U937 cells were incubated with phorbol 12-myristate 13-acetate and then oxidized human low-density lipoprotein to induce foam cell formation. Oil red O staining was used to identify the foam cells. The production of IL-8 and TNF-α by U937 foam cells was assayed by enzyme-linked immunosorbent assay. The expression of TREM-1 mRNA in U937 foam cells was detected by reverse transcription-polymerase chain reaction. Moreover, U937 foam cells were transfected by small interfering RNA using Lipofectamine 2000 to knockdown TREM-1. Western blot was performed to assay protein expression of TREM-1 and ELISA was used to examine the effect of TREM-1 knockdown on IL-8 and TNF-α production. PMA and ox-LDL induced U937 cells to form foam cells. The production of TNF-α and IL-8 was found to be significantly elevated in U937 foam cells, concomitant with a significant up-regulation of TREM-1 mRNA. TREM-1 siRNA was able to partially silence the expression of TREM-1 protein and remarkably inhibited TNF-α and IL-8 production in U937 foam cells, suggesting that TREM-1 is a positive regulator of TNF-α and IL-8 production in U937 foam cells. Our finding that TREM-1 controls the production of IL-8 and TNF-α in U937 foam cells defines a potentially critical role of TREM-1 in the pathogenesis of atherosclerosis and implicates TREM-1 as a potential therapeutic target for the disease.

  13. Aqueous foams and foam films stabilised by surfactants. Gravity-free studies

    Science.gov (United States)

    Langevin, Dominique

    2017-01-01

    There are still many open questions and problems in both fundamental research and practical applications of foams. Despite the fact that foams have been extensively studied, many aspects of foam physics and chemistry still remain unclear. Experiments on foams performed under microgravity allow studying wet foams, such as those obtained early during the foaming process. On Earth, wet foams evolve too quickly due to gravity drainage and only dry foams can be studied. This paper reviews the foam and foam film studies that we have performed in gravity-free conditions. It highlights the importance of surface rheology as well as of confinement effects in foams and foam films behaviour.

  14. Novel TiC/Ti Open Cellular Foams Prepared by a Modified Sponge-coating Method Using High Frequency Induction Heating Process

    Institute of Scientific and Technical Information of China (English)

    Yong Gao; Xingxiang Xu; Zhenming Yang; Junqi Zhang; Chunhai Jiang; Jinsong Zhang

    2013-01-01

    A new kind of open cellular foam material with three dimensionally interconnected TiC/Ti struts was prepared by a two-step sponge-coating and high frequency induction heating process.The microstructure,composition and compression strength of the prepared TiC/Ti foam materials were characterized.It was confirmed that the incorporation of Ti into TiC resulted in an inter-bonded Ti-TiC-Ti layered structure in the struts,which enhanced the plasticity of the composite foam materials.

  15. Dysfunctional HDL from HIV+ individuals promotes monocyte-derived foam cell formation in vitro.

    Science.gov (United States)

    Angelovich, Thomas A; Hearps, Anna C; Oda, Michael N; Borja, Mark S; Huynh, Diana; Homann, Stefanie; Jaworowski, Anthony; Kelesidis, Theodoros

    2017-09-18

    The role of HDL function in HIV-related atherosclerotic cardiovascular disease (CVD) is unclear. HDLs isolated from HIV+ [HIV(+)HDL] and HIV-uninfected individuals (HDL) were assessed for HDL function and ability to promote monocyte-derived foam cell formation (MDFCF) (a key event in HIV-related CVD) ex vivo. Using an established in vitro model of atherogenesis and plasma samples from an established cross-sectional study of virologically-suppressed HIV+ males on stable effective antiretroviral therapy (ART) and with low CVD risk (median age: 42 years; n = 10), we explored the impact of native HDL [HIV(+)HDL] on MDFCF. In this exploratory study we selected HIV-HDL known to be dysfunctional based on two independent measures of impaired HDL function: a) antioxidant (high HDLox) b) ability of HDL to release apoA-I [low HDL-apoA-I exchange (HAE %)]. Five healthy males matched by age and race to the HIV+ group were included. Given that oxidation of HDL leads to abnormal HDL function, we also compared proatherogenic effects of HIV-HDL versus chemically-derived HDLox. The ex vivo atherogenesis assay was performed using lipoproteins (purchased or isolated from plasma using ultracentrifugation) and monocytes purified via negative selection from healthy donors. HIV(+)HDL known to have reduced antioxidant function and rate of HDL/ApoAI exchange promoted MDFCF to a greater extent than HDL (33.0% vs 26.2% foam cells; p = 0.015). HDL oxidized in vitro also enhanced foam cell formation as compared to non-oxidized HDL (p HDL in virologically suppressed HIV+ individuals may potentiate atherosclerosis in HIV infection by promoting monocyte-derived foam cell formation.The role of HDL function in HIV-related atherosclerotic cardiovascular disease is unclear. HDL isolated from HIV+ [HIV(+)HDL] and HIV-uninfected individuals [HIV(-)HDL] were assessed for HDL function and ability to promote foam cell formation ex vivo. HIV(+)HDL known to have reduced antioxidant function and

  16. Supercritical CO2 Foaming of Thermoplastic Materials Derived from Maize: Proof-of-Concept Use in Mammalian Cell Culture Applications

    Science.gov (United States)

    Trujillo-de Santiago, Grissel; Portales-Cabrera, Cynthia Guadalupe; Portillo-Lara, Roberto; Araiz-Hernández, Diana; Del Barone, Maria Cristina; García-López, Erika; Rojas-de Gante, Cecilia; de los Angeles De Santiago-Miramontes, María; Segoviano-Ramírez, Juan Carlos; García-Lara, Silverio; Rodríguez-González, Ciro Ángel; Alvarez, Mario Moisés; Di Maio, Ernesto; Iannace, Salvatore

    2015-01-01

    Background Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds. Methodology/Principal Findings We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively) and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively). Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3) and two different prostate cancer cell lines (22RV1, DU145) attached to and proliferated on zein foams. Conclusions/Significance We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves). Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity) for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein

  17. Supercritical CO2 foaming of thermoplastic materials derived from maize: proof-of-concept use in mammalian cell culture applications.

    Directory of Open Access Journals (Sweden)

    Grissel Trujillo-de Santiago

    Full Text Available Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds.We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively. Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3 and two different prostate cancer cell lines (22RV1, DU145 attached to and proliferated on zein foams.We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves. Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein foams for extended time periods.

  18. Computational investigations and grid refinement study of 3D transient flow in a cylindrical tank using OpenFOAM

    Science.gov (United States)

    Mohd Sakri, F.; Mat Ali, M. S.; Sheikh Salim, S. A. Z.

    2016-10-01

    The study of physic fluid for a liquid draining inside a tank is easily accessible using numerical simulation. However, numerical simulation is expensive when the liquid draining involves the multi-phase problem. Since an accurate numerical simulation can be obtained if a proper method for error estimation is accomplished, this paper provides systematic assessment of error estimation due to grid convergence error using OpenFOAM. OpenFOAM is an open source CFD-toolbox and it is well-known among the researchers and institutions because of its free applications and ready to use. In this study, three types of grid resolution are used: coarse, medium and fine grids. Grid Convergence Index (GCI) is applied to estimate the error due to the grid sensitivity. A monotonic convergence condition is obtained in this study that shows the grid convergence error has been progressively reduced. The fine grid has the GCI value below 1%. The extrapolated value from Richardson Extrapolation is in the range of the GCI obtained.

  19. Comparison of OpenFOAM and EllipSys3D actuator line methods with (NEW) MEXICO results

    Science.gov (United States)

    Nathan, J.; Meyer Forsting, A. R.; Troldborg, N.; Masson, C.

    2017-05-01

    The Actuator Line Method exists for more than a decade and has become a well established choice for simulating wind rotors in computational fluid dynamics. Numerous implementations exist and are used in the wind energy research community. These codes were verified by experimental data such as the MEXICO experiment. Often the verification against other codes were made on a very broad scale. Therefore this study attempts first a validation by comparing two different implementations, namely an adapted version of SOWFA/OpenFOAM and EllipSys3D and also a verification by comparing against experimental results from the MEXICO and NEW MEXICO experiments.

  20. Evaluation of Computational Fluids Dynamics (CFD) code Open FOAM in the study of the pressurized thermal stress of PWR reactors. Comparison with the commercial code Ansys-CFX; Evaluacion del codigo de Dinamica de Fluidos Computacional (CFD) Open FOAM en el estudio del estres termico presurizado de los reactores PWR. Comparacion con el codigo comercial Ansys-CFX

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.; Barrachina, T.; Miro, R.; Verdu Martin, G.; Chiva, S.

    2012-07-01

    In this work is proposed to evaluate the potential of the OpenFOAM code for the simulation of typical fluid flows in reactors PWR, in particular for the study of pressurized thermal stress. Test T1-1 has been simulated , within the OECD ROSA project, with the objective of evaluating the performance of the code OpenFOAM and models of turbulence that has implemented to capture the effect of the thrust forces in the case study.

  1. Human macrophage foam cells degrade atherosclerotic plaques through cathepsin K mediated processes

    DEFF Research Database (Denmark)

    Barascuk, Natasha; Skjøt-Arkil, Helene; Register, Thomas C

    2010-01-01

    BACKGROUND: Proteolytic degradation of Type I Collagen by proteases may play an important role in remodeling of atherosclerotic plaques, contributing to increased risk of plaque rupture.The aim of the current study was to investigate whether human macrophage foam cells degrade the extracellular......-I in areas of intimal hyperplasia and in shoulder regions of advanced plaques. Treatment of human monocytes with M-CSF or M-CSF+LDL generated macrophages and foam cells producing CTX-I when cultured on type I collagen enriched matrix. Circulating levels of CTX-I were not significantly different in women...... with aortic calcifications compared to those without. CONCLUSIONS: Human macrophage foam cells degrade the atherosclerotic plaques though cathepsin K mediated processes, resulting in increase in levels of CTX-I. Serum CTX-I was not elevated in women with aortic calcification, likely due to the contribution...

  2. Doping of carbon foams for use in energy storage devices

    Science.gov (United States)

    Mayer, Steven T.; Pekala, Richard W.; Morrison, Robert L.; Kaschmitter, James L.

    1994-01-01

    A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located therebetween. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery.

  3. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ha Young, E-mail: hayoung@skku.edu [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Kim, Sang Doo [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Baek, Suk-Hwan [Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, Daegu 705-717 (Korea, Republic of); Choi, Joon Hyuk [Department of Pathology, College of Medicine, Yeungnam University, Daegu 705-717 (Korea, Republic of); Cho, Kyung-Hyun [School of Biotechnology, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Zabel, Brian A. [Palo Alto Institute for Research and Education, Veterans Affairs Hospital, Palo Alto, CA 94304 (United States); Bae, Yoe-Sik, E-mail: yoesik@skku.edu [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of)

    2013-03-29

    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  4. SediFoam: A general-purpose, open-source CFD-DEM solver for particle-laden flow with emphasis on sediment transport

    CERN Document Server

    Sun, Rui

    2016-01-01

    With the growth of available computational resource, CFD-DEM (computational fluid dynamics-discrete element method) becomes an increasingly promising and feasible approach for the study of sediment transport. Several existing CFD-DEM solvers are applied in chemical engineering and mining industry. However, a robust CFD-DEM solver for the simulation of sediment transport is still desirable. In this work, the development of a three-dimensional, massively parallel, and open-source CFD-DEM solver SediFoam is detailed. This solver is built based on open-source solvers OpenFOAM and LAMMPS. OpenFOAM is a CFD toolbox that can perform three-dimensional fluid flow simulations on unstructured meshes; LAMMPS is a massively parallel DEM solver for molecular dynamics. Several validation tests of SediFoam are performed using cases of a wide range of complexities. The results obtained in the present simulations are consistent with those in the literature, which demonstrates the capability of SediFoam for sediment transport a...

  5. Foamed Antenna Support for Very Large Apertures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase I program will demonstrate the feasibility of the in-space production of large aperture antenna structures. The use of a novel open cell foam,...

  6. Effects of CpG-ODN on gene expression in formation of foam cells

    Institute of Scientific and Technical Information of China (English)

    Kai LI; Bin WAN; Zhen-lin HU; Ying HE; Xiao-wen HE; Lei JIANG; Shu-han SUN

    2005-01-01

    Aim: To investigate the effects of CpG-oligodeoxynucleotide (CpG-ODN) on the formation of macrophage foam cells and related gene expression. Methods: A gene expression profile was examined by microarray techniques, and mRNA expression was detected by reverse transcriptase polymerase chain reaction (RTPCR). The cholesterol and cholesteryl ester contents of cells were determined by high performance liquid chromatography. Results: CD36, LPL, and Fcγ2b, which were related to lipid metabolism and the formation of macrophage foam cells, were upregulated after CpG-ODN stimulation. The mRNA expression related to the formation of foam cells was confirmed by semiquantitative RT-PCR. Moreover,histochemical analysis confirmed that lipid deposits inside cells increased after CpG-ODN treatment. However, using flow cytometry, we found that CpG-ODN had no effect on the expression of membrane receptors. Conclusion: CpG-ODN up-regulated the expression of genes in macrophage foam cell formation.

  7. The inhibition of macrophage foam cell formation by tetrahydroxystilbene glucoside is driven by suppressing vimentin cytoskeleton.

    Science.gov (United States)

    Yao, Wenjuan; Huang, Lei; Sun, Qinju; Yang, Lifeng; Tang, Lian; Meng, Guoliang; Xu, Xiaole; Zhang, Wei

    2016-10-01

    Macrophage foam cell formation triggered by oxLDL is an important event that occurs during the development of atherosclerosis. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (TSG) exhibits significant anti-atherosclerotic activity. Herein we used U937 cells induced by PMA and oxLDL in vitro to investigate the inhibitory effects of TSG on U937 differentiation and macrophage foam cell formation. TSG pretreatment markedly inhibited cell differentiation induced by PMA, macrophage apoptosis and foam cell formation induced by oxLDL. The inhibition of vimentin expression and cleavage was involved in these inhibitory effects of TSG. The suppression of vimentin by siRNA in U937 significantly inhibited cell differentiation, apoptosis and foam cell formation. Using inhibitors for TGFβR1 and PI3K, we found that vimentin production in U937 cells is regulated by TGFβ/Smad signaling, but not by PI3K-Akt-mTOR signaling. Meanwhile, TSG pretreatment inhibited both the expression of TGFβ1 and the phosphorylation of Smad2 and Smad3, and TSG suppressed the nuclear translocation of Smad4 induced by PMA and oxLDL. Furthermore, TSG attenuated the induced caspase-3 activation and adhesion molecules levels by PMA and oxLDL. PMA and oxLDL increased the co-localization of vimentin with ICAM-1, which was attenuated by pretreatment with TSG. These results suggest that TSG inhibits macrophage foam cell formation through suppressing vimentin expression and cleavage, adhesion molecules expression and vimentin-ICAM-1 co-localization. The interruption of TGFβ/Smad pathway and caspase-3 activation is responsible for the downregulation of TSG on vimentin expression and degradation, respectively.

  8. An in vitro coculture model of transmigrant monocytes and foam cell formation.

    Science.gov (United States)

    Takaku, M; Wada, Y; Jinnouchi, K; Takeya, M; Takahashi, K; Usuda, H; Naito, M; Kurihara, H; Yazaki, Y; Kumazawa, Y; Okimoto, Y; Umetani, M; Noguchi, N; Niki, E; Hamakubo, T; Kodama, T

    1999-10-01

    To analyze in vitro the migration of monocytes to the subendothelial space, their differentiation into macrophages, and the subsequent formation of foam cells in vitro, we have developed a 2-coculture system with rabbit aortic endothelial cells (AECs), aortic smooth muscle cells (SMCs), and a mixture of matrix proteins on polyethylene filters in chemotaxis chambers. AECs were seeded on a mixture of type I and IV collagen with or without various types of serum lipoproteins (method 1) or on matrix proteins secreted by SMCs (method 2). In these coculture systems, rabbit AECs can maintain a well-preserved monolayer for up to 2 weeks. When human CD14-positive monocytes were added to the upper medium of the system, with monocyte chemotactic protein-1 treatment approximately 60% of the monocytes transmigrated within 24 hours and were retained for up to 7 days, whereas without MCP-1 treatment, monocytes transmigrated. On day 1, transmigrant monocytes were negative for immunostaining of type I and II macrophage scavenger receptors but by day 3, became positive for scavenger receptors as well as other macrophage markers. When oxidized low density lipoprotein was added to the matrix layer of the method I coculture, on day 4 transmigrant cells exhibited lipid deposit droplets, and by day 7, they had the appearance of typical foam cells. Some of the transmigrant cells recovered in the lower medium on day 7 also appeared to be foam cells, indicating foam cell motility and escape from the coculture layer through the filter. In summary, this coculture system is a useful in vitro tool to dissect the cellular and molecular events that make up the process of foam cell formation.

  9. Fire resistant resilient foams. [for seat cushions

    Science.gov (United States)

    Gagliani, J.

    1976-01-01

    Primary program objectives were the formulation, screening, optimization and characterization of open-cell, fire resistant, low-smoke emitting, thermally stable, resilient polyimide foams suitable for seat cushions in commercial aircraft and spacecraft. Secondary program objectives were to obtain maximum improvement of the tension, elongation and tear characteristics of the foams, while maintaining the resiliency, thermal stability, low smoke emission and other desirable attributes of these materials.

  10. Development of fine-celled bio-fiber composite foams using physical blowing agents and nano-particles

    Science.gov (United States)

    Guo, Gangjian

    As one of eco-friendly bio-fibers, wood-fiber has been incorporated in plastics to make wood-fiber/plastic composites (WPC) with an increased stiffness, durability and lowered cost. However, these improvements are usually accompanied by loss in the ductility and impact strength of the composites. These shortcomings can be significantly improved by incorporating a fine-cell foam structure in the composites. This thesis presents the development of the foaming technology for the manufacture of fine-cell WPC foams with environmentally benign physical blowing agents (PBAs), and focuses on the elucidation of the fundamental foaming mechanisms and the related issues involved. One critical issue comes from the volatiles evolved from the wood-fiber during high temperature processing. The volatiles, as a blowing agent, can contribute to the foaming process. However, they lead to gross deterioration of the cell structure of WPC foams. The presence of volatiles makes foaming of WPC "a poorly understood black art". With the use of PBAs, a strategy of lowering processing temperature becomes feasible, to suppress the generation of volatiles. A series of PBA-based experiments were designed using a statistical design of experiments (DOE) technique, and were performed to establish the relationship of processing and material variables with the structure of WPC foams. Fundamental foaming behaviors for two different PBAs and two different polymer systems were identified. WPC foams with a fine-cell morphology and a desired density were successfully obtained at the optimized conditions. Another limitation for the wider application of WPC is their flammability. Innovative use of a small amount of nano-clay in WPC significantly improved the flame-retarding property of WPC, and the key issue was to achieve a high degree of exfoliation of nano-particles in the polymer matrix, to achieve a desired flammability reduction. The synergistic effects of nano-particles in foaming of WPC were

  11. Molecular machines open cell membranes

    Science.gov (United States)

    García-López, Víctor; Chen, Fang; Nilewski, Lizanne G.; Duret, Guillaume; Aliyan, Amir; Kolomeisky, Anatoly B.; Robinson, Jacob T.; Wang, Gufeng; Pal, Robert; Tour, James M.

    2017-08-01

    Beyond the more common chemical delivery strategies, several physical techniques are used to open the lipid bilayers of cellular membranes. These include using electric and magnetic fields, temperature, ultrasound or light to introduce compounds into cells, to release molecular species from cells or to selectively induce programmed cell death (apoptosis) or uncontrolled cell death (necrosis). More recently, molecular motors and switches that can change their conformation in a controlled manner in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications. Here we show that molecular machines can drill through cellular bilayers using their molecular-scale actuation, specifically nanomechanical action. Upon physical adsorption of the molecular motors onto lipid bilayers and subsequent activation of the motors using ultraviolet light, holes are drilled in the cell membranes. We designed molecular motors and complementary experimental protocols that use nanomechanical action to induce the diffusion of chemical species out of synthetic vesicles, to enhance the diffusion of traceable molecular machines into and within live cells, to induce necrosis and to introduce chemical species into live cells. We also show that, by using molecular machines that bear short peptide addends, nanomechanical action can selectively target specific cell-surface recognition sites. Beyond the in vitro applications demonstrated here, we expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, near-infrared and radio-frequency activation.

  12. Ni foam cathode enables high volumetric H2 production in a microbial electrolysis cell

    NARCIS (Netherlands)

    Jeremiasse, A.W.; Hamelers, H.V.M.; Saakes, M.; Buisman, C.J.N.

    2010-01-01

    Valuable, “green” H2 can be produced with a microbial electrolysis cell (MEC). To achieve a high volumetric production rate of high purity H2, a continuous flow MEC with an anion exchange membrane, a flow through bioanode and a flow through Ni foam cathode was constructed. At an electrical energy in

  13. Effect of convection on osteoblastic cell growth and function in biodegradable polymer foam scaffolds

    Science.gov (United States)

    Goldstein, A. S.; Juarez, T. M.; Helmke, C. D.; Gustin, M. C.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    2001-01-01

    Culture of seeded osteoblastic cells in three-dimensional osteoconductive scaffolds in vitro is a promising approach to produce an osteoinductive material for repair of bone defects. However, culture of cells in scaffolds sufficiently large to bridge critical-sized defects is a challenge for tissue engineers. Diffusion may not be sufficient to supply nutrients into large scaffolds and consequently cells may grow preferentially at the periphery under static culture conditions. Three alternative culturing schemes that convect media were considered: a spinner flask, a rotary vessel, and a perfusion flow system. Poly(DL-lactic-co-glycolic acid) (PLGA) foam discs (12.7 mm diameter, 6.0 mm thick, 78.8% porous) were seeded with osteoblastic marrow stromal cells and cultured in the presence of dexamethasone and L-ascorbic acid for 7 and 14 days. Cell numbers per foam were found to be similar with all culturing schemes indicating that cell growth could not be enhanced by convection, but histological analysis indicated that the rotary vessel and flow system produced a more uniform distribution of cells throughout the foams. Alkaline phosphatase (ALP) activity per cell was higher with culture in the flow system and spinner flask after 7 days, while no differences in osteocalcin (OC) activity per cell were observed among culturing methods after 14 days in culture. Based on the higher ALP activity and better cell uniformity throughout the cultured foams, the flow system appears to be the superior culturing method, although equally important is the fact that in none of the tests did any of the alternative culturing techniques underperform the static controls. Thus, this study demonstrates that culturing techniques that utilize fluid flow, and in particular the flow perfusion system, improve the properties of the seeded cells over those maintained in static culture.

  14. Study of effects of transport properties of a biodiesel derived from soybean on the mixture process formation using CFD OpenFOAM

    Science.gov (United States)

    Benitez Molina, Adolfo; de La Garza de Leon, Oscar Alejandro; Martinez Martinez, Simon; Sanchez Cruz, Fausto Alejandro

    2015-03-01

    In this work has been studied the effects of the transport properties of biodiesel derived from soybean on the mixing process, using a CFD code OpenFOAM. For this the most relevant properties in this mixing process have been determined: density, viscosity, surface tension and vapor pressure. These fuel properties govern the spray formation however, there are only very limited studies that determined for its subsequent implementation in a CFD code, such as the OpenFOAM code. Such properties were obtained using empirical correlations based on the molecular structure of the fatty acids that compose the biodiesel and applying nonlinear regression are implemented in the programed models used in the OpenFOAM code for a diesel spray simulation. The results achieved in the present study on the one side, have been confirmed how the biodiesel properties affect the mixture process, and on the other side, the obtained coefficients which can be used in the proposed models by the CFD code OpenFOAM for the implementation of this properties as a temperature function without the correlations based on the molecular structure of the fatty acid. Also they thank the CONACYT from Mexican Government for granting the Master degree of Adolfo Benitez.

  15. Quercetin increases macrophage cholesterol efflux to inhibit foam cell formation through activating PPARγ-ABCA1 pathway

    Science.gov (United States)

    Sun, Liqiang; Li, En; Wang, Feng; Wang, Tao; Qin, Zhiping; Niu, Shaohui; Qiu, Chunguang

    2015-01-01

    The accumulation of cholesterol in macrophages could induce the formation of foam cells and increase the risk of developing atherosclerosis. We wonder if quercetin, one of flavonoids with anti-inflammation functions in different cell types, could elevate the development of foam cells formation in atherosclerosis. We treated foam cells derived from oxLDL induced THP-1 cells with quercetin, and evaluated the foam cells formation, cholesterol content and apoptosis of the cells. We found that quercetin induced the expression of ABCA1 in differentiated THP-1 cells, and increased the cholesterol efflux from THP-1 cell derived foam cells. Eventually, cholesterol level and the formation of foam cell derived from THP-1 cells decreased after quercetin treatment. In addition, quercetin activated PPARγ-LXRα pathway to upregulate ABCA1 expression through increasing protein level of PPARγ and its transcriptional activity. Inhibition of PPARγ activity by siRNA knockdown or the addition of chemical inhibitor, GW9662, abolished quercetin induced ABCA1 expression and cholesterol efflux in THP-1 derived macrophages. Our data demonstrated that quercetin increased cholesterol efflux from macrophages through upregulating the expressions of PPARγ and ABCA1. Taken together, increasing uptake of quercetin or quercetin-rich foods would be an effective way to lower the risk of atherosclerosis. PMID:26617799

  16. Assessment of particle-tracking models for dispersed particle-laden flows implemented in OpenFOAM and ANSYS FLUENT

    Directory of Open Access Journals (Sweden)

    Franziska Greifzu

    2016-01-01

    Full Text Available In the present study two benchmark problems for turbulent dispersed particle-laden flow are investigated with computational fluid dynamics (CFD. How the CFD programs OpenFOAM and ANSYS FLUENT model these flows is tested and compared. The numerical results obtained with Lagrangian–Eulerian (LE point-particle (PP models for Reynolds-averaged Navier–Stokes (RANS simulations of the fluid flow in steady state and transient modes are compared with the experimental data available in the literature. The effect of the dispersion model on the particle motion is investigated in particular, as well as the order of coupling between the continuous carrier phase and the dispersed phase. First, a backward-facing step (BFS case is validated. As a second case, the confined bluff body (CBB is used. The simulated fluid flows correspond well with the experimental data for both test cases. The results for the dispersed solid phase reveal a good accordance between the simulation results and the experiments. It seems that particle dispersion is slightly under-predicted when ANSYS FLUENT is used, whereas the applied solver in OpenFOAM overestimates the dispersion somewhat. Only minor differences between the coupling schemes are detected due to the low volume fractions and mass loadings that are investigated. In the BFS test case the importance of the spatial dimension of the numerical model is demonstrated. Even if it is reasonable to assume a two-dimensional fluid flow structure, it is crucial to simulate the turbulent particle-laden flow with a three-dimensional model since the turbulent dispersion of the particles is three-dimensional.

  17. The Role of Foaming Agent and Processing Route in Mechanical Performance of Fabricated Aluminum Foams

    Directory of Open Access Journals (Sweden)

    Alexandra Byakova

    2014-01-01

    Full Text Available The results of this study highlight the role of foaming agent and processing route in influencing the contamination of cell wall material by side products, which, in turn, affects the macroscopic mechanical response of closed-cell Al-foams. Several kinds of Al-foams have been produced with pure Al/Al-alloys by the Alporas like melt process, all performed with and without Ca additive and processed either with conventional TiH2 foaming agent or CaCO3 as an alternative one. Damage behavior of contaminations was believed to affect the micromechanism of foam deformation, favoring either plastic buckling or brittle failure of cell walls. No discrepancy between experimental values of compressive strengths for Al-foams comprising ductile cell wall constituents and those prescribed by theoretical models for closed-cell structure was found while the presence of low ductile and/or brittle eutectic domains and contaminations including particles/layers of Al3Ti, residues of partially reacted TiH2, and Ca bearing compounds, results in reducing the compressive strength to values close to or even below those of open-cell foams of the same relative density.

  18. Design, characterization and modeling of biobased acoustic foams

    Science.gov (United States)

    Ghaffari Mosanenzadeh, Shahrzad

    Polymeric open cell foams are widely used as sound absorbers in sectors such as automobile, aerospace, transportation and building industries, yet there is a need to improve sound absorption of these foams through understanding the relation between cell morphology and acoustic properties of porous material. Due to complicated microscopic structure of open cell foams, investigating the relation between foam morphology and acoustic properties is rather intricate and still an open problem in the field. The focus of this research is to design and develop biobased open cell foams for acoustic applications to replace conventional petrochemical based foams as well as investigating the link between cell morphology and macroscopic properties of open cell porous structures. To achieve these objectives, two industrially produced biomaterials, polylactide (PLA) and polyhydroxyalkanoate (PHA) and their composites were examined and highly porous biobased foams were fabricated by particulate leaching and compression molding. Acoustic absorption capability of these foams was enhanced utilizing the effect of co-continuous blends to form a bimodal porous structure. To tailor mechanical and acoustic properties of biobased foams, blends of PLA and PHA were studied to reach the desired mechanical and viscoelastic properties. To enhance acoustic properties of porous medium for having a broad band absorption effect, cell structure must be appropriately graded. Such porous structures with microstructural gradation are called Functionally Graded Materials (FGM). A novel graded foam structure was designed with superior sound absorption to demonstrate the effect of cell arrangement on performance of acoustic fixtures. Acoustic measurements were performed in a two microphone impedance tube and acoustic theory of Johnson-Champoux-Allard was applied to the fabricated foams to determine micro cellular properties such as tortuosity, viscous and thermal lengths from sound absorption impedance tube

  19. Three-dimensional graphene foam as a biocompatible and conductive scaffold for neural stem cells

    Science.gov (United States)

    Li, Ning; Zhang, Qi; Gao, Song; Song, Qin; Huang, Rong; Wang, Long; Liu, Liwei; Dai, Jianwu; Tang, Mingliang; Cheng, Guosheng

    2013-04-01

    Neural stem cell (NSC) based therapy provides a promising approach for neural regeneration. For the success of NSC clinical application, a scaffold is required to provide three-dimensional (3D) cell growth microenvironments and appropriate synergistic cell guidance cues. Here, we report the first utilization of graphene foam, a 3D porous structure, as a novel scaffold for NSCs in vitro. It was found that three-dimensional graphene foams (3D-GFs) can not only support NSC growth, but also keep cell at an active proliferation state with upregulation of Ki67 expression than that of two-dimensional graphene films. Meanwhile, phenotypic analysis indicated that 3D-GFs can enhance the NSC differentiation towards astrocytes and especially neurons. Furthermore, a good electrical coupling of 3D-GFs with differentiated NSCs for efficient electrical stimulation was observed. Our findings implicate 3D-GFs could offer a powerful platform for NSC research, neural tissue engineering and neural prostheses.

  20. Shock Wave Attenuation Using Foam Obstacles: Does Geometry Matter?

    Directory of Open Access Journals (Sweden)

    Hongjoo Jeon

    2015-06-01

    Full Text Available A shock wave impact study on open and closed cell foam obstacles was completed to assess attenuation effects with respect to different front face geometries of the foam obstacles. Five different types of geometries were investigated, while keeping the mass of the foam obstacle constant. The front face, i.e., the side where the incident shock wave impacts, were cut in geometries with one, two, three or four convergent shapes, and the results were compared to a foam block with a flat front face. Results were obtained by pressure sensors located upstream and downstream of the foam obstacle, in addition to high-speed schlieren photography. Results from the experiments show no significant difference between the five geometries, nor the two types of foam.

  1. Role of formyl peptide receptor 2 on the serum amyloid A-induced macrophage foam cell formation.

    Science.gov (United States)

    Lee, Ha Young; Kim, Sang Doo; Baek, Suk-Hwan; Choi, Joon Hyuk; Bae, Yoe-Sik

    2013-04-05

    Recently we demonstrated that SAA induces macrophage foam cell formation. In this study we show that SAA-induced foam cell formation is inhibited by formyl peptide receptor 2 (FPR2) antagonist WRW(4), as well as by FPR2-targeted siRNA knockdown. SAA-stimulated LOX1 expression was also mediated by FPR2. We also found that SAA-stimulated foam cell formation and LOX1 expression was pertussis toxin-insensitive. In addition, FPR2 is upregulated in peripheral blood mononuclear cells from patients with atherosclerosis. Our findings therefore suggest that SAA stimulates foam cell formation via FPR2 signaling and LOX1 induction, and thus likely contributes to atherogenesis. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. microRNA-150 inhibits the formation of macrophage foam cells through targeting adiponectin receptor 2

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing [Department of Geratory, Linzi District People’s Hospital of Zibo City, Zibo, Shandong (China); Zhang, Suhua, E-mail: drsuhuangzhang@qq.com [Department of HealthCare, Qilu Hospital of Shandong University (Qingdao), Qingdao City, Qingdao (China)

    2016-08-05

    Transformation of macrophages into foam cells plays a critical role in the pathogenesis of atherosclerosis. The aim of this study was to determine the expression and biological roles of microRNA (miR)-150 in the formation of macrophage foam cells and to identify its functional target(s). Exposure to 50 μg/ml oxidized low-density lipoprotein (oxLDL) led to a significant upregulation of miR-150 in THP-1 macrophages. Overexpression of miR-150 inhibited oxLDL-induced lipid accumulation in THP-1 macrophages, while knockdown of miR-150 enhanced lipid accumulation. apoA-I- and HDL-mediated cholesterol efflux was increased by 66% and 43%, respectively, in miR-150-overexpressing macrophages relative to control cells. In contrast, downregulation of miR-150 significantly reduced cholesterol efflux from oxLDL-laden macrophages. Bioinformatic analysis and luciferase reporter assay revealed adiponectin receptor 2 (AdipoR2) as a direct target of miR-150. Small interfering RNA-mediated downregulation of AdipoR2 phenocopied the effects of miR-150 overexpression, reducing lipid accumulation and facilitating cholesterol efflux in oxLDL-treated THP-1 macrophages. Knockdown of AdipoR2 induced the expression of proliferator-activated receptor gamma (PPARγ), liver X receptor alpha (LXRα), ABCA1, and ABCG1. Moreover, pharmacological inhibition of PPARγ or LXRα impaired AdipoR2 silencing-induced upregulation of ABCA1 and ABCG1. Taken together, our results indicate that miR-150 can attenuate oxLDL-induced lipid accumulation in macrophages via promotion of cholesterol efflux. The suppressive effects of miR-150 on macrophage foam cell formation are mediated through targeting of AdipoR2. Delivery of miR-150 may represent a potential approach to prevent macrophage foam cell formation in atherosclerosis. -- Highlights: •miR-150 inhibits macrophage foam cell formation. •miR-150 accelerates cholesterol efflux from oxLDL-laden macrophages. •miR-150 suppresses macrophage foam cell

  3. SIRT6 reduces macrophage foam cell formation by inducing autophagy and cholesterol efflux under ox-LDL condition.

    Science.gov (United States)

    He, Jiangping; Zhang, Guangya; Pang, Qi; Yu, Cong; Xiong, Jie; Zhu, Jing; Chen, Fengling

    2017-03-09

    SIRT6 is a pivotal regulator of lipid metabolism. It is also closely connected to cardiovascular diseases, which are the main cause of death in diabetic patients. We observed a decrease in the expression of SIRT6 and key autophagy effectors (ATG5, LC3B, and LAMP1) in ox-LDL-induced foam cells, a special form of lipid-laden macrophages. In these cells, SIRT6 WT but not SIRT6 H133Y overexpression markedly reduced foam cell formation, as shown by Oil Red O staining, while inducing autophagy flux, as determined by both mRFP-GFP-LC3 labeling and transmission electron microscopy. Silencing the key autophagy initiation gene ATG5, reversed the autophagy-promoting effect of SIRT6 in ox-LDL-treated THP1 cells, as evidenced by an increase in foam cells. Cholesterol efflux assays indicated that SIRT6 overexpression in foam cells promoted cholesterol efflux, increased the levels of ABCA1 and ABCG1, and reduced miR-33 levels. By transfecting miR-33 into cells overexpressing SIRT6, we observed that reduced foam cell formation and autophagy flux induction were largely reversed. These data imply that SIRT6 plays an essential role in protecting against atherosclerosis by reducing foam cell formation through an autophagy-dependent pathway. This article is protected by copyright. All rights reserved.

  4. The Role of Foaming Agent and Processing Route in the Mechanical Performance of Fabricated Aluminum Foams

    Directory of Open Access Journals (Sweden)

    Takashi Nakamura

    2012-05-01

    Full Text Available The results of the present study highlight the role of foaming agent and processing route in influencing the contamination of cell wall material by side products, which, in turn, affect the macroscopic mechanical response of closed-cell Al-foams. Several kinds of Al-foams have been produced with pure Al by the Alporas melt process and powder metallurgical technique, all performed either with conventional TiH2 foaming agent or CaCO3 as an alternative. Mechanical characteristics of contaminating products induced by processing additives, all of which were presented in one or another kind of Al-foam, have been determined in indentation experiments. Damage behavior of these contaminations affects the micro-mechanism of deformation and favors either plastic buckling or brittle failure of the cell walls. It is justified that there is no discrepancy between experimental values of compressive strengths for Al-foams comprising ductile Al + Al4Ca eutectic domains and those prescribed by theoretical models for closed-cell structure. However, the presence of low ductile Al + Al3Ti + Al4Ca eutectic domains and brittle particles/layers of Al3Ti, fine CaCO3/CaO particles, Al2O3 oxide network, and, especially, residues of partially reacted TiH2, results in reducing the compressive strength to values close to or even below those of open-cell foams of the same relative density.

  5. Thermal properties of closed-cell aluminum foam with circular pores

    Directory of Open Access Journals (Sweden)

    Lu Guo-Yun

    2014-01-01

    Full Text Available The thermal property of closed-cell aluminum foam is studied numerically and the effects of the distribution of the circular pore on the thermal property are studied theoretically. When the convection and radiation are ignored, the effects of porosity, cell size, and distribution forms of pore on the apparent thermal conductivity are investigated. Moreover, the effects of air in the pore on the thermal property are analyzed as well. Simulation results show that apparent thermal conductivity linearly increases with the increase of porosity, while the cell size and the distribution have negligible effects on the thermal property. By comparison, thermal conductivity of air has slight effect on thermal property of foamed aluminum in the context of small size pore.

  6. Foam Micromechanics

    Energy Technology Data Exchange (ETDEWEB)

    Kraynik, A.M.; Neilsen, M.K.; Reinelt, D.A.; Warren, W.E.

    1998-11-03

    Foam evokes many different images: waves breaking at the seashore, the head on a pint of Guinness, an elegant dessert, shaving, the comfortable cushion on which you may be seated... From the mundane to the high tech, foams, emulsions, and cellular solids encompass a broad range of materials and applications. Soap suds, mayonnaise, and foamed polymers provide practical motivation and only hint at the variety of materials at issue. Typical of mukiphase materiaIs, the rheoIogy or mechanical behavior of foams is more complicated than that of the constituent phases alone, which may be gas, liquid, or solid. For example, a soap froth exhibits a static shear modulus-a hallmark of an elastic solid-even though it is composed primarily of two Newtonian fluids (water and air), which have no shear modulus. This apparent paradox is easily resolved. Soap froth contains a small amount of surfactant that stabilizes the delicate network of thin liq- uid films against rupture. The soap-film network deforms in response to a macroscopic strain; this increases interracial area and the corresponding sur- face energy, and provides the strain energy of classical elasticity theory [1]. This physical mechanism is easily imagined but very challenging to quantify for a realistic three-dimensional soap froth in view of its complex geome- try. Foam micromechanics addresses the connection between constituent properties, cell-level structure, and macroscopic mechanical behavior. This article is a survey of micromechanics applied to gas-liquid foams, liquid-liquid emulsions, and cellular solids. We will focus on static response where the foam deformation is very slow and rate-dependent phenomena such as viscous flow can be neglected. This includes nonlinear elasticity when deformations are large but reversible. We will also discuss elastic- plastic behavior, which involves yield phenomena. Foam structures based on polyhedra packed to fill space provide a unify- ing geometrical theme. Because a two

  7. PPARy phosphorylation mediated by JNK MAPK: a potential role in macrophage-derived foam cell formation

    Institute of Scientific and Technical Information of China (English)

    Ran YIN; Yu-gang DONG; Hong-lang LI

    2006-01-01

    Aim: To investigate whether oxidized low-density lipoprotein (ox-LDL) modulates peroxisome proliferator-activated receptor γ (PPARγ) activity through phosphorylation in macrophages, and the effect of PPARy phosphorylation on macrophages-derived foam cell formation. Methods: After exposing the cultured THP-1 cells to ox-LDL in the presence or absence of different mitogen-activated protein kinase (MAPK) inhibitors, PPARγ and phosphorylated PPARγ protein levels were detected by Western blot. MAPK activity was analyzed using MAP Kinase Assay Kit. Intracellular cholesterol accumulation was assessed by Oil red O staining and cholesterol oxidase enzymatic method. The Mrna level of PPARγ target gene was determined by reverse transcription-polymerase chain reaction (RT-PCR). Results: ox-LDL evaluated PPARγ phosphorylation status and subsequently decreased PPARγ target gene expression in a dose-dependent manner. Ox-LDL also induced MAPK activation. Treatment of THP-1 cells with c-Jun N-terminal kinase-, but not p38- or extracellular signal-regulated kinase-MAPK inhibitor, significantly suppressed PPARγ phosphorylation induced by ox-LDL, which in turn inhibited foam cell formation. Conclusion: In addition to its ligand-dependent activation, ox-LDL modulates PPARγ activity through phosphorylation, which is mediated by MAPK activation. PPARγ phosphorylation mediated by MAPK facilitates foam cell formation from macrophages exposed to ox-LDL.

  8. Role of VLDL Receptor in the Process of Foam Cell Formation

    Institute of Scientific and Technical Information of China (English)

    屈伸; 吴凡; 田俊; 李映红; 王燕; 王宇哲; 宗义强

    2004-01-01

    Summary: The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β-VLDL or low density lipoprotein (LDL), respectively for 24 h and 48 h, foam cells formation was identified by oil red O staining and cellular contents of triglyceride (TG) and total cholesterol (TC) were determined. The mRNA levels of LDLR, LDLR related protein (LRP)and VLDLR were detected by semi-quantitative RT-PCR. The results demonstrated that VLDL, βVLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or β-VLDL showed markedly increased expression of VLDLR and decreased expression of LDLR, whereas LRP was up-regulated slightly. For identifying the effect of VLDL receptor on cellular lipid accumulation, Idl-A7-VR cells, which expresses VLDLR and trace amount of LRP without functional LDLR, was used to incubate with lipoproteins for further examination. The results elucidated that the uptake of triglyceride-rich lipoprotein mediated by VLDLR plays an important role in accumulation of lipid and the formation of foam cells.

  9. Mitigation of open-air explosions by blast absorbing barriers and foam

    NARCIS (Netherlands)

    Eerden, F. van der; Carton, E.P.

    2012-01-01

    Open-air explosions are inevitable connected to activities from the Ministry of Defense (e.g. large detonations or EOD operations). And also the industry uses open-air explosions for production processes (e.g. explosion welding). This requires the protection of people and buildings relatively close

  10. Mitigation of open-air explosions by blast absorbing barriers and foam

    NARCIS (Netherlands)

    Eerden, F. van der; Carton, E.P.

    2012-01-01

    Open-air explosions are inevitable connected to activities from the Ministry of Defense (e.g. large detonations or EOD operations). And also the industry uses open-air explosions for production processes (e.g. explosion welding). This requires the protection of people and buildings relatively close

  11. Genome-wide analysis of LXRα activation reveals new transcriptional networks in human atherosclerotic foam cells.

    Science.gov (United States)

    Feldmann, Radmila; Fischer, Cornelius; Kodelja, Vitam; Behrens, Sarah; Haas, Stefan; Vingron, Martin; Timmermann, Bernd; Geikowski, Anne; Sauer, Sascha

    2013-04-01

    Increased physiological levels of oxysterols are major risk factors for developing atherosclerosis and cardiovascular disease. Lipid-loaded macrophages, termed foam cells, are important during the early development of atherosclerotic plaques. To pursue the hypothesis that ligand-based modulation of the nuclear receptor LXRα is crucial for cell homeostasis during atherosclerotic processes, we analysed genome-wide the action of LXRα in foam cells and macrophages. By integrating chromatin immunoprecipitation-sequencing (ChIP-seq) and gene expression profile analyses, we generated a highly stringent set of 186 LXRα target genes. Treatment with the nanomolar-binding ligand T0901317 and subsequent auto-regulatory LXRα activation resulted in sequence-dependent sharpening of the genome-binding patterns of LXRα. LXRα-binding loci that correlated with differential gene expression revealed 32 novel target genes with potential beneficial effects, which in part explained the implications of disease-associated genetic variation data. These observations identified highly integrated LXRα ligand-dependent transcriptional networks, including the APOE/C1/C4/C2-gene cluster, which contribute to the reversal of cholesterol efflux and the dampening of inflammation processes in foam cells to prevent atherogenesis.

  12. Gas-foaming calcium phosphate cement scaffold encapsulating human umbilical cord stem cells.

    Science.gov (United States)

    Chen, Wenchuan; Zhou, Hongzhi; Tang, Minghui; Weir, Michael D; Bao, Chongyun; Xu, Hockin H K

    2012-04-01

    Tissue engineering approaches are promising to meet the increasing need for bone regeneration. Calcium phosphate cement (CPC) can be injected and self-set to form a scaffold with excellent osteoconductivity. The objectives of this study were to develop a macroporous CPC-chitosan-fiber construct containing alginate-fibrin microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs) and to investigate hUCMSC release from the degrading microbeads and proliferation inside the porous CPC construct. The hUCMSC-encapsulated microbeads were completely wrapped inside the CPC paste, with the gas-foaming porogen creating macropores in CPC to provide for access to culture media. Increasing the porogen content in CPC significantly increased the cell viability, from 49% of live cells in CPC with 0% porogen to 86% of live cells in CPC with 15% porogen. The alginate-fibrin microbeads started to degrade and release the cells inside CPC at 7 days. The released cells started to proliferate inside the macroporous CPC construct. The live cell number inside CPC increased from 270 cells/mm(2) at 1 day to 350 cells/mm(2) at 21 days. The pore volume fraction of CPC increased from 46.8% to 78.4% using the gas-foaming method, with macropore sizes of approximately 100 to 400 μm. The strength of the CPC-chitosan-fiber scaffold at 15% porogen was 3.8 MPa, which approximated the reported 3.5 MPa for cancellous bone. In conclusion, a novel gas-foaming macroporous CPC construct containing degradable alginate-fibrin microbeads was developed that encapsulated hUCMSCs. The cells had good viability while wrapped inside the porous CPC construct. The degradable microbeads in CPC quickly released the cells, which proliferated over time inside the porous CPC. Self-setting, strong CPC with alginate-fibrin microbeads for stem cell delivery is promising for bone tissue engineering applications.

  13. Growth and by-product profiles of Kluyveromyces marxianus cells immobilized in foamed alginate.

    Science.gov (United States)

    Wilkowska, Agnieszka; Kregiel, Dorota; Guneser, Onur; Karagul Yuceer, Yonca

    2015-01-01

    The aim of this research was to study how the yeast cell immobilization technique influences the growth and fermentation profiles of Kluyveromyces marxianus cultivated on apple/chokeberry and apple/cranberry pomaces. Encapsulation of the cells was performed by droplet formation from a foamed alginate solution. The growth and metabolic profiles were evaluated for both free and immobilized cells. Culture media with fruit waste produced good growth of free as well as immobilized yeast cells. The fermentation profiles of K. marxianus were different with each waste material. The most varied aroma profiles were noted for immobilized yeast cultivated on apple/chokeberry pomace.

  14. In situ gelation for cell immobilization and culture in alginate foam scaffolds.

    Science.gov (United States)

    Andersen, Therese; Markussen, Christine; Dornish, Michael; Heier-Baardson, Helene; Melvik, Jan Egil; Alsberg, Eben; Christensen, Bjørn E

    2014-02-01

    Essential cellular functions are often lost under culture in traditional two-dimensional (2D) systems. Therefore, biologically more realistic three-dimensional (3D) cell culture systems are needed that provide mechanical and biochemical cues which may otherwise be unavailable in 2D. For the present study, an alginate-based hydrogel system was used in which cells in an alginate solution were seeded onto dried alginate foams. A uniform distribution of NIH:3T3 and NHIK 3025 cells entrapped within the foam was achieved by in situ gelation induced by calcium ions integrated in the foam. The seeding efficiency of the cells was about 100% for cells added in a seeding solution containing 0.1-1.0% alginate compared with 18% when seeded without alginate. The NHIK 3025 cells were allowed to proliferate and form multi-cellular structures inside the transparent gel that were later vital stained and evaluated by confocal microscopy. Gels were de-gelled at different time points to isolate the multi-cellular structures and to determine the spheroid growth rate. It was also demonstrated that the mechanical properties of the gel could largely be varied through selection of type and concentration of the applied alginate and by immersing the already gelled disks in solutions providing additional gel-forming ions. Cells can efficiently be incorporated into the gel, and single cells and multi-cellular structures that may be formed inside can be retrieved without influencing cell viability or contaminating the sample with enzymes. The data show that the current system may overcome some limitations of current 3D scaffolds such as cell retrieval and in situ cell staining and imaging.

  15. In Situ Gelation for Cell Immobilization and Culture in Alginate Foam Scaffolds

    Science.gov (United States)

    Markussen, Christine; Dornish, Michael; Heier-Baardson, Helene; Melvik, Jan Egil; Alsberg, Eben; Christensen, Bjørn E.

    2014-01-01

    Essential cellular functions are often lost under culture in traditional two-dimensional (2D) systems. Therefore, biologically more realistic three-dimensional (3D) cell culture systems are needed that provide mechanical and biochemical cues which may otherwise be unavailable in 2D. For the present study, an alginate-based hydrogel system was used in which cells in an alginate solution were seeded onto dried alginate foams. A uniform distribution of NIH:3T3 and NHIK 3025 cells entrapped within the foam was achieved by in situ gelation induced by calcium ions integrated in the foam. The seeding efficiency of the cells was about 100% for cells added in a seeding solution containing 0.1–1.0% alginate compared with 18% when seeded without alginate. The NHIK 3025 cells were allowed to proliferate and form multi-cellular structures inside the transparent gel that were later vital stained and evaluated by confocal microcopy. Gels were de-gelled at different time points to isolate the multi-cellular structures and to determine the spheroid growth rate. It was also demonstrated that the mechanical properties of the gel could largely be varied through selection of type and concentration of the applied alginate and by immersing the already gelled disks in solutions providing additional gel-forming ions. Cells can efficiently be incorporated into the gel, and single cells and multi-cellular structures that may be formed inside can be retrieved without influencing cell viability or contaminating the sample with enzymes. The data show that the current system may overcome some limitations of current 3D scaffolds such as cell retrieval and in situ cell staining and imaging. PMID:24125496

  16. Gap junctional communication between vascular cells. Induction of connexin43 messenger RNA in macrophage foam cells of atherosclerotic lesions.

    OpenAIRE

    Polacek, D.; Lal, R; Volin, M. V.; Davies, P F

    1993-01-01

    The structure and function of blood vessels depend on the ability of vascular cells to receive and transduce signals and to communicate with each other. One means by which vascular cells have been shown to communicate is via gap junctions, specifically connexin43. In atherosclerosis, the normal physical patterns of communication are disrupted by the subendothelial infiltration and accumulation of blood monocytes, which in turn can differentiate into resident foam cells. In this paper we repor...

  17. Shock wave compression behavior of aluminum foam

    Institute of Scientific and Technical Information of China (English)

    程和法; 黄笑梅; 薛国宪; 韩福生

    2003-01-01

    The shock wave compression behavior of the open cell aluminum foam with relative density of 0. 396 was studied through planar impact experiments. Using polyvinylidene fluoride(PVDF) piezoelectric gauge technique, the stress histories and propagation velocities of shock wave in the aluminum foam were measured and analyzed. The results show that the amplitude of shock wave attenuates rapidly with increasing the propagation distance in the aluminum foam, and an exponential equation of the normalized peak stress vs propagation distance of shock wave is established, the attenuation factor in the equation is 0. 286. Furthermore, the Hugoniot relation, νs = 516.85+ 1.27νp,for the aluminum foam is determined by empirical fit to the experimental Hugoniot data.

  18. The influence of polyol type on cell geometry and the thermal stability of polyurethane foams

    Directory of Open Access Journals (Sweden)

    Prendžov Slobodan J.

    2006-01-01

    Full Text Available The aim of this study was to examine the influence of substituting defined amounts of polyol Voranol 3322 by polyol Voranol CP 1055 on the cell geometry and thermal stability of the synthesized flexible polyurethane foams. The influence of the amount of antipyrene on the cell geometry and their thermal stability was also investigated. The following components were used in the synthesis of the polyurethanes: a mixture of two polyols (Voranol 3322 with the hydroxyl number 47 mg KOH/g, mean molecular mass 3400 and Voranol CP 1055 with the hydroxyl number 156 mg KOH/g, mean molecular mass 1000, toluene discarnate as the isocyanate component, a combination of an organic-metallic compound and a tertiary amine as catalysts, surfactant and water as the coreactant. The thermal stability was determined by thermogravimetric analysis (in a nitrogen atmosphere. The cell geometry was analyzed by optical microscopy. Examination of the cell geometry revealed different cell shapes. The form factor as an indicator of cell deviation from spherical shape increased (more round forms were observed with increasing amount of Voranol CP 1055. The TG examination showed that specimens with 6 and 8 g of Voranol 3322 substituted by Voranol CP 1055 completely degraded at 350 °C, while foams with 10 and 12 g of Voranol 3322 substituted by Voranol CP 1055 displayed lower mass loss at higher temperatures and had residual masses of 46 % and 43 % at 600°C respectively. The addition of antipyrene in an amount of 1% (based on the amount of polyol contributed to improved thermal stability, no visible color change of the specimen tested at 210°C for 40 minutes, and to rounder cell forms. Considering the obtained results it can be concluded that an increase in the amount of Voranol CP 1055 yielded more spherically shaped cells and better thermal stability of the synthesized flexible polyurethane foams. The addition of antipyrene improves the thermal stability and the cell geometry.

  19. Thermal Expansion of Three Closed Cell Polymeric Foams at Cryogenic Temperatures

    Science.gov (United States)

    Stokes, Eric

    2006-01-01

    The Space Shuttle External Tank (ET) contains the liquid H2 fuel and liquid oxygen oxidizer and supplies them under pressure to the three space shuttle main engines (SSME) in the orbiter during lift-off and ascent. The ET thermal protection system consists of sprayed-on foam insulation and pre-molded ablator materials. The closed-cell foams are the external coating on the ET and are responsible for minimizing the amount of moisture that condenses out and freezes on the tank from the humid air in Florida while it is on the pad with cryogenic propellant awaiting launch. This effort was part of the overall drive to understand the behavior of these materials under use-conditions. There are four specially-engineered closed-cell foams used on the tank. The thermal expansion (contraction) of three of the polyurethane and polyisocyanurate foams were measured from -423 F (the temperature of liquid hydrogen) to 125 F under atmospheric conditions and under vacuum. One of them, NCFI 24-124, is a mechanically-applied material and covers the main acreage of the tank, accounting for 77 percent of the total foam used. Another, BX-265, is also a mechanically-applied and hand-sprayed material used on the tank's "closeout" areas. PDL 1034 is a hand-poured foam used for filling odd-shaped cavities in the tank, Measurements were made in triplicate in the three primary material directions in the case of the first two materials and the two primary material directions in the case of the last. Task 1 was developing the techniques for getting a uniform heating rate and minimizing axial and radial thermal gradients in the specimens. Temperature measurements were made at four locations in the specimens during this initial development phase of testing. Major challenges that were overcome include developing techniques for transferring the coolant, liquid helium (-452 F), from its storage container to the test facility with a minimal transfer of heat to the coolant and control of the heating

  20. Production of low-density poly (4-methyl-1-pentene) foam via phase inversion from binary solvent/nonsovent systems

    Energy Technology Data Exchange (ETDEWEB)

    Simandl, R.F.; Robinson, D.N.; Bolinger, W.L.; Davis, W.E.

    1991-11-01

    Phase inversion from durene/naphthalene, durene/tmpdo, and durene/hexadecanol binary solvent/nonsolvent systems produced well interconnected, radiographically homogeneous, open-celled poly (4- methyl-1-pentene) or pmp foams. These foams ranged in density from 5 to 50 mg/cm{sup 2}. Foam homogeneity and casting efficiency were dependent on casting scheme, durene quality, solvent-to-nonsolvent ratio, and quench temperature. Foam density tracked linearly with dissolved-polymer content. Homogeneous, ultralow-density (5 to 6 mg/cm{sup 3}) foams were produced by using a 49/51 durene/naphthalene solvent eutectic. Foam hardness or firmness tracked somewhat linearly with foam density. Foams with densities above 20 mg/cm{sup 3} were too fragile to handle without damage.

  1. Effect of pore morphology on cross-property link for close-celled metallic foams

    Science.gov (United States)

    Yang, Xiaohu; Wang, Wenbin; Yan, Leilei; Zhang, Qiancheng; Lu, Tian Jian

    2016-12-01

    We demonstrate a simple cross-property correlation between effective conductivity (both thermal and electrical) and effective elastic modulus for high porosity cellular metallic foams with non-spherical closed cells. A particular solution to the equation of Laplace heat conduction for modelling foam thermal conductivity is extended to account for non-spherical gaseous pores; and this model is further associated with the estimation of effective elastic modulus. The simple cross-property correlation thus obtained shows that both the effective conductivity and modulus significantly decrease with increasing porosity. Non-spherical pores contribute to further reduce the effective conductivity and modulus, due mainly to increased tortuosity and stress concentration caused by enlarged surface area and sharp corners as spherical pores are replaced by non-spherical ones.

  2. Sound absorption and insulation property of closed-cell aluminum foam

    Institute of Scientific and Technical Information of China (English)

    YU Hai-jun; LI Bing; YAO Guang-chun; WANG Xiao-lin; LUO Hong-jie; LIU Yi-han

    2006-01-01

    The closed-cell aluminum foams (specimen p=0.31 g/cm3, diameter of 100 mm, and thickness of 20 mm for sound absorption testing; specimen p=0.51 g/cm3, length of 1 240 mm, width of 1 100 mm, and thickness of 30 mm for sound insulation testing) were prepared by the method of molten body transitional foaming process. Its sound absorption property under frequency of 160-2 000 Hz and the sound insulation property under frequency of 100-4 000 Hz were tested. The sound absorption results show that the sound absorption property is much better under middle frequencies than that under low and high frequencies. The sound absorption coefficient climbs when frequency increases from 160 Hz to 800 Hz and then drops when frequency is increased from 800 Hz to 2 000 Hz. The function of the sound absorption mainly depends on the Helmholtz resonator, the microphone as well as cracks of closed-cell aluminum foam. The sound insulation experiments show that the sound reduction index (R) is small under low frequencies, and large under high frequencies; the weighted sound reduction index (Rw) and the highest sound reduction index (R)can reach around 30.8 dB and 43 dB, respectively.

  3. A new biomimicry marine current turbine:Study of hydrodynamic performan- ce and wake using software OpenFOAM

    Institute of Scientific and Technical Information of China (English)

    Yung-Jeh CHU

    2016-01-01

    Inspired by Dryobalanops aromatica seed, a new biomimicry marine current turbine is proposed. Hydrodynamic perfor- mance and wake properties are two key factors determining whether a new marine current turbine design is practical or not. Thus, a study of hydrodynamic performance and wake of the proposed biomimicry turbine is conducted. The computational fluid dynamics (CFD) software, OpenFOAM is used to generate the required results for the mentioned study. The hydrodynamic performance and wake properties of the proposed biomimicry turbine is compared to two conventional turbines of Bahaj et al. and Pinon et al. re- spectively. The simulation results showed that the proposed biomimicry marine current turbine gives optimum power output with its power coefficient,CP≈0.376 at the tip speed ratio (TSR) of 1.5. Under the same boundary conditions, the maximum torque pro- duced by the proposed biomimicry turbine at zero rotational speed is 38.71 Nm which is 1110% greater than the torque generated by the turbine of Bahaj et al.. The recovery distance for the wake of the biomimicry turbine is predicted to be 10.6% shorter than that of IFREMER-LOMC turbine. The above-mentioned results confirm the potential application of the proposed biomimicry marine curre- nt turbine in the renewable energy industry.

  4. Adding Complex Terrain and Stable Atmospheric Condition Capability to the OpenFOAM-based Flow Solver of the Simulator for On/Offshore Wind Farm Applications (SOWFA): Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Churchfield, M. J.; Sang, L.; Moriarty, P. J.

    2013-09-01

    This paper describes changes made to NREL's OpenFOAM-based wind plant aerodynamics solver such that it can compute the stably stratified atmospheric boundary layer and flow over terrain. Background about the flow solver, the Simulator for Off/Onshore Wind Farm Applications (SOWFA) is given, followed by details of the stable stratification/complex terrain modifications to SOWFA, along with somepreliminary results calculations of a stable atmospheric boundary layer and flow over a simply set of hills.

  5. Application of a drainage film reduces fibroblast ingrowth into large-pored polyurethane foam during negative-pressure wound therapy in an in vitro model.

    Science.gov (United States)

    Wiegand, Cornelia; Springer, Steffen; Abel, Martin; Wesarg, Falko; Ruth, Peter; Hipler, Uta-Christina

    2013-01-01

    Negative-pressure wound therapy (NPWT) is an advantageous treatment option in wound management to promote healing and reduce the risk of complications. NPWT is mainly carried out using open-cell polyurethane (PU) foams that stimulate granulation tissue formation. However, growth of wound bed tissue into foam material, leading to disruption of newly formed tissue upon dressing removal, has been observed. Consequently, it would be of clinical interest to preserve the positive effects of open-cell PU foams while avoiding cellular ingrowth. The study presented analyzed effects of NPWT using large-pored PU foam, fine-pored PU foam, and the combination of large-pored foam with drainage film on human dermal fibroblasts grown in a collagen matrix. The results showed no difference between the dressings in stimulating cellular migration during NPWT. However, when NPWT was applied using a large-pored PU foam, the fibroblasts continued to migrate into the dressing. This led to significant breaches in the cell layers upon removal of the samples after vacuum treatment. In contrast, cell migration stopped at the collagen matrix edge when fine-pored PU foam was used, as well as with the combination of PU foam and drainage film. In conclusion, placing a drainage film between collagen matrix and the large-pored PU foam dressing reduced the ingrowth of cells into the foam significantly. Moreover, positive effects on cellular migration were not affected, and the effect of the foam on tissue surface roughness in vitro was also reduced.

  6. High power density microbial fuel cell with flexible 3D graphene-nickel foam as anode

    Science.gov (United States)

    Wang, Hanyu; Wang, Gongming; Ling, Yichuan; Qian, Fang; Song, Yang; Lu, Xihong; Chen, Shaowei; Tong, Yexiang; Li, Yat

    2013-10-01

    The structure and electrical conductivity of anode play a significant role in the power generation of microbial fuel cells (MFCs). In this study, we developed a three-dimensional (3D) reduced graphene oxide-nickel (denoted as rGO-Ni) foam as an anode for MFC through controlled deposition of rGO sheets onto the nickel foam substrate. The loading amount of rGO sheets and electrode surface area can be controlled by the number of rGO loading cycles. 3D rGO-Ni foam anode provides not only a large accessible surface area for microbial colonization and electron mediators, but also a uniform macro-porous scaffold for effective mass diffusion of the culture medium. Significantly, at a steady state of the power generation, the MFC device with flexible rGO-Ni electrodes produced an optimal volumetric power density of 661 W m-3 calculated based on the volume of anode material, or 27 W m-3 based on the volume of the anode chamber. These values are substantially higher than that of plain nickel foam, and other conventional carbon based electrodes (e.g., carbon cloth, carbon felt, and carbon paper) measured in the same conditions. To our knowledge, this is the highest volumetric power density reported for mL-scale MFC device with a pure strain of Shewanella oneidensis MR-1. We also demonstrated that the MFC device can be operated effectively in a batch-mode at least for a week. These new 3D rGO-Ni electrodes show great promise for improving the power generation of MFC devices.The structure and electrical conductivity of anode play a significant role in the power generation of microbial fuel cells (MFCs). In this study, we developed a three-dimensional (3D) reduced graphene oxide-nickel (denoted as rGO-Ni) foam as an anode for MFC through controlled deposition of rGO sheets onto the nickel foam substrate. The loading amount of rGO sheets and electrode surface area can be controlled by the number of rGO loading cycles. 3D rGO-Ni foam anode provides not only a large accessible

  7. Foaming Behaviour, Structure, and Properties of Polypropylene Nanocomposites Foams

    Directory of Open Access Journals (Sweden)

    M. Antunes

    2010-01-01

    Full Text Available This work presents the preparation and characterization of compression-moulded montmorillonite and carbon nanofibre-polypropylene foams. The influence of these nanofillers on the foaming behaviour was analyzed in terms of the foaming parameters and final cellular structure and morphology of the foams. Both nanofillers induced the formation of a more isometric-like cellular structure in the foams, mainly observed for the MMT-filled nanocomposite foams. Alongside their crystalline characteristics, the nanocomposite foams were also characterized and compared with the unfilled ones regarding their dynamic-mechanical thermal behaviour. The nanocomposite foams showed higher specific storage moduli due to the reinforcement effect of the nanofillers and higher cell density isometric cellular structure. Particularly, the carbon nanofibre foams showed an increasingly higher electrical conductivity with increasing the amount of nanofibres, thus showing promising results as to produce electrically improved lightweight materials for applications such as electrostatic painting.

  8. Synthesis of Foam-Shaped Nanoporous Zeolite Material: A Simple Template-Based Method

    Science.gov (United States)

    Saini, Vipin K.; Pires, Joao

    2012-01-01

    Nanoporous zeolite foam is an interesting crystalline material with an open-cell microcellular structure, similar to polyurethane foam (PUF). The aluminosilicate structure of this material has a large surface area, extended porosity, and mechanical strength. Owing to these properties, this material is suitable for industrial applications such as…

  9. Relationship between Microcellular Foaming Injection Molding Process Parameters and Cell Size

    Institute of Scientific and Technical Information of China (English)

    HU Guang-hong; JIANG Chao-dong; CUI Zhen-shan

    2008-01-01

    In order to study the relationship between the main process parameters and the cell size, the mathematical model of cell growth of microcellular foaming injection process is built. Then numeric simulation is employed as experimental method, and the Taguchi method is used to analyze significance of effect of process parameters on the cell size. At last the process parameters are focused on melt temperature, injection time, mold temperature and pre- filled volume. The significance order from big to small of the effect of each process parameters on cell size is melt temperature, pre-filled volume, injection time, and mold temperature. On the basis of above research, the effect of each process parameter on cell size is further researched.Appropriate reduction of the melt temperature and increase of the we-filled volume can optimize the cell size effectively, while the effects of injection time and mold temperature on cell size are less significant.

  10. Nicotinate-Curcumin Impedes Foam Cell Formation from THP-1 Cells through Restoring Autophagy Flux.

    Science.gov (United States)

    Gu, Hong-Feng; Li, Hai-Zhe; Tang, Ya-Ling; Tang, Xiao-Qing; Zheng, Xi-Long; Liao, Duan-Fang

    2016-01-01

    Our previous studies have indicated that a novel curcumin derivate nicotinate-curcumin (NC) has beneficial effects on the prevention of atherosclerosis, but the precise mechanisms are not fully understood. Given that autophagy regulates lipid metabolism, the present study was designed to investigate whether NC decreases foam cell formation through restoring autophagy flux in oxidized low-density lipoprotein (ox-LDL)-treated THP-1 cells. Our results showed that ox-LDL (100 μg/ml) was accumulated in THP-1 cells and impaired autophagy flux. Ox-LDL-induced impairment of autophagy was enhanced by treatment with the autophagy inhibitor chloroquine (CQ) and rescued by the autophagy inducer rapamycin. The aggregation of ox-LDL was increased by CQ, but decreased by rapamycin. In addition, colocalization of lipid droplets with LC3-II was remarkably reduced in ox-LDL group. In contrast, NC (10 μM) rescued the impaired autophagy flux by significantly increasing level of LC3-II, the number of autophagolysosomes, and the degradation of p62 in ox-LDL-treated THP-1 cells. Inhibition of the PI3K-Akt-mTOR signaling was required for NC-rescued autophagy flux. Notably, our results showed that NC remarkably promoted the colocalization of lipid droplets with autophagolysosomes, increased efflux of cholesterol, and reduced ox-LDL accumulation in THP-1 cells. However, treatment with 3-methyladenine (3-MA) or CQ reduced the protective effects of NC on lipid accumulation. Collectively, the findings suggest that NC decreases lipid accumulation in THP-1 cells through restoring autophagy flux, and further implicate that NC may be a potential therapeutic reagent to reverse atherosclerosis.

  11. Nicotinate-Curcumin Impedes Foam Cell Formation from THP-1 Cells through Restoring Autophagy Flux

    Science.gov (United States)

    Gu, Hong-Feng; Li, Hai-Zhe; Tang, Ya-Ling; Tang, Xiao-Qing; Zheng, Xi-Long; Liao, Duan-Fang

    2016-01-01

    Our previous studies have indicated that a novel curcumin derivate nicotinate-curcumin (NC) has beneficial effects on the prevention of atherosclerosis, but the precise mechanisms are not fully understood. Given that autophagy regulates lipid metabolism, the present study was designed to investigate whether NC decreases foam cell formation through restoring autophagy flux in oxidized low-density lipoprotein (ox-LDL)-treated THP-1 cells. Our results showed that ox-LDL (100 μg/ml) was accumulated in THP-1 cells and impaired autophagy flux. Ox-LDL-induced impairment of autophagy was enhanced by treatment with the autophagy inhibitor chloroquine (CQ) and rescued by the autophagy inducer rapamycin. The aggregation of ox-LDL was increased by CQ, but decreased by rapamycin. In addition, colocalization of lipid droplets with LC3-II was remarkably reduced in ox-LDL group. In contrast, NC (10 μM) rescued the impaired autophagy flux by significantly increasing level of LC3-II, the number of autophagolysosomes, and the degradation of p62 in ox-LDL-treated THP-1 cells. Inhibition of the PI3K-Akt-mTOR signaling was required for NC-rescued autophagy flux. Notably, our results showed that NC remarkably promoted the colocalization of lipid droplets with autophagolysosomes, increased efflux of cholesterol, and reduced ox-LDL accumulation in THP-1 cells. However, treatment with 3-methyladenine (3-MA) or CQ reduced the protective effects of NC on lipid accumulation. Collectively, the findings suggest that NC decreases lipid accumulation in THP-1 cells through restoring autophagy flux, and further implicate that NC may be a potential therapeutic reagent to reverse atherosclerosis. PMID:27128486

  12. Nicotinate-Curcumin Impedes Foam Cell Formation from THP-1 Cells through Restoring Autophagy Flux.

    Directory of Open Access Journals (Sweden)

    Hong-Feng Gu

    Full Text Available Our previous studies have indicated that a novel curcumin derivate nicotinate-curcumin (NC has beneficial effects on the prevention of atherosclerosis, but the precise mechanisms are not fully understood. Given that autophagy regulates lipid metabolism, the present study was designed to investigate whether NC decreases foam cell formation through restoring autophagy flux in oxidized low-density lipoprotein (ox-LDL-treated THP-1 cells. Our results showed that ox-LDL (100 μg/ml was accumulated in THP-1 cells and impaired autophagy flux. Ox-LDL-induced impairment of autophagy was enhanced by treatment with the autophagy inhibitor chloroquine (CQ and rescued by the autophagy inducer rapamycin. The aggregation of ox-LDL was increased by CQ, but decreased by rapamycin. In addition, colocalization of lipid droplets with LC3-II was remarkably reduced in ox-LDL group. In contrast, NC (10 μM rescued the impaired autophagy flux by significantly increasing level of LC3-II, the number of autophagolysosomes, and the degradation of p62 in ox-LDL-treated THP-1 cells. Inhibition of the PI3K-Akt-mTOR signaling was required for NC-rescued autophagy flux. Notably, our results showed that NC remarkably promoted the colocalization of lipid droplets with autophagolysosomes, increased efflux of cholesterol, and reduced ox-LDL accumulation in THP-1 cells. However, treatment with 3-methyladenine (3-MA or CQ reduced the protective effects of NC on lipid accumulation. Collectively, the findings suggest that NC decreases lipid accumulation in THP-1 cells through restoring autophagy flux, and further implicate that NC may be a potential therapeutic reagent to reverse atherosclerosis.

  13. Ex vivo foam cell formation is enhanced in monocytes from older individuals by both extrinsic and intrinsic mechanisms.

    Science.gov (United States)

    Angelovich, Thomas A; Shi, Margaret D Y; Zhou, Jingling; Maisa, Anna; Hearps, Anna C; Jaworowski, Anthony

    2016-07-01

    Aging is the strongest predictor of cardiovascular diseases such as atherosclerosis, which are the leading causes of morbidity and mortality in elderly men. Monocytes play an important role in atherosclerosis by differentiating into foam cells (lipid-laden macrophages) and producing atherogenic proinflammatory cytokines. Monocytes from the elderly have an inflammatory phenotype that may promote atherosclerotic plaque development; here we examined whether they are more atherogenic than those from younger individuals. Using an in vitro model of monocyte transmigration and foam cell formation, monocytes from older men (median age [range]: 75 [58-85] years, n=20) formed foam cells more readily than those of younger men (32 [23-46] years, n=20) (PFoam cell formation was enhanced by soluble factors in serum from older men, but did not correlate with plasma lipid levels. Of the three subsets, intermediate monocytes formed the most foam cells. Therefore, both cellular changes to monocytes and soluble plasma factors in older men primes monocytes for foam cell formation following transendothelial migration, which may contribute to enhanced atherosclerosis in this population.

  14. Development of a Hopkinson Bar Apparatus for Testing Soft Materials: Application to a Closed-Cell Aluminum Foam

    Directory of Open Access Journals (Sweden)

    Marco Peroni

    2016-01-01

    Full Text Available An increasing interest in lightweight metallic foams for automotive, aerospace, and other applications has been observed in recent years. This is mainly due to the weight reduction that can be achieved using foams and for their mechanical energy absorption and acoustic damping capabilities. An accurate knowledge of the mechanical behavior of these materials, especially under dynamic loadings, is thus necessary. Unfortunately, metal foams and in general “soft” materials exhibit a series of peculiarities that make difficult the adoption of standard testing techniques for their high strain-rate characterization. This paper presents an innovative apparatus, where high strain-rate tests of metal foams or other soft materials can be performed by exploiting the operating principle of the Hopkinson bar methods. Using the pre-stress method to generate directly a long compression pulse (compared with traditional SHPB, a displacement of about 20 mm can be applied to the specimen with a single propagating wave, suitable for evaluating the whole stress-strain curve of medium-sized cell foams (pores of about 1–2 mm. The potential of this testing rig is shown in the characterization of a closed-cell aluminum foam, where all the above features are amply demonstrated.

  15. The inhibition of macrophage foam cell formation by 9-cis β-carotene is driven by BCMO1 activity.

    Directory of Open Access Journals (Sweden)

    Noa Zolberg Relevy

    Full Text Available Atherosclerosis is a major cause of morbidity and mortality in developed societies, and begins when activated endothelial cells recruit monocytes and T-cells from the bloodstream into the arterial wall. Macrophages that accumulate cholesterol and other fatty materials are transformed into foam cells. Several epidemiological studies have demonstrated that a diet rich in carotenoids is associated with a reduced risk of heart disease; while previous work in our laboratory has shown that the 9-cis β-carotene rich alga Dunaliella inhibits atherogenesis in mice. The effect of 9-cis β-carotene on macrophage foam cell formation has not yet been investigated. In the present work, we sought to study whether the 9-cis β-carotene isomer, isolated from the alga Dunaliella, can inhibit macrophage foam cell formation upon its conversion to retinoids. The 9-cis β-carotene and Dunaliella lipid extract inhibited foam cell formation in the RAW264.7 cell line, similar to 9-cis retinoic acid. Furthermore, dietary enrichment with the algal powder in mice resulted in carotenoid accumulation in the peritoneal macrophages and in the inhibition of foam cell formation ex-vivo and in-vivo. We also found that the β-carotene cleavage enzyme β-carotene 15,15'-monooxygenase (BCMO1 is expressed and active in macrophages. Finally, 9-cis β-carotene, as well as the Dunaliella extract, activated the nuclear receptor RXR in hepa1-6 cells. These results indicate that dietary carotenoids, such as 9-cis β-carotene, accumulate in macrophages and can be locally cleaved by endogenous BCMO1 to form 9-cis retinoic acid and other retinoids. Subsequently, these retinoids activate the nuclear receptor RXR that, along with additional nuclear receptors, can affect various metabolic pathways, including those involved in foam cell formation and atherosclerosis.

  16. Modeling for Ultrasonic Health Monitoring of Foams with Embedded Sensors

    Science.gov (United States)

    Wang, L.; Rokhlin, S. I.; Rokhlin, Stanislav, I.

    2005-01-01

    In this report analytical and numerical methods are proposed to estimate the effective elastic properties of regular and random open-cell foams. The methods are based on the principle of minimum energy and on structural beam models. The analytical solutions are obtained using symbolic processing software. The microstructure of the random foam is simulated using Voronoi tessellation together with a rate-dependent random close-packing algorithm. The statistics of the geometrical properties of random foams corresponding to different packing fractions have been studied. The effects of the packing fraction on elastic properties of the foams have been investigated by decomposing the compliance into bending and axial compliance components. It is shown that the bending compliance increases and the axial compliance decreases when the packing fraction increases. Keywords: Foam; Elastic properties; Finite element; Randomness

  17. Foam Based Gas Diffusion Electrodes for Reversible Alkaline Electrolysis Cells

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    cell. In the present work we demonstrate the application of hydrophobic, porous, and electro-catalytically active gas diffusion electrodes. PTFE particles and silver nanowires as electro-catalysts were used in the gas diffusion electrodes. Impedance spectroscopy and cyclic voltammetry were performed...

  18. β3-Adrenoceptor activation upregulates apolipoprotein A-I expression in HepG2 cells, which might further promote cholesterol efflux from macrophage foam cells.

    Science.gov (United States)

    Gao, Xia-Qing; Li, Yan-Fang; Jiang, Zhi-Li

    2017-01-01

    The aim of this study was to explore the effects of β3-adrenoceptor (β3-AR) activation on HepG2 cells and its influence on cholesterol efflux from macrophage foam cells. HepG2 cells were cultured and treated with the β3-AR agonist, BRL37344, and antagonist, SR52390A, and the expression of apolipoprotein (Apo) A-I, ApoA-II, ApoB, and β3-AR in the supernatants and cells was determined. The expression of peroxisome proliferator-activated receptor (PPAR) γ and PPARα in the HepG2 cells was also assessed. Next, using the RAW264.7 macrophage foam cell model, we also assessed the influence of the HepG2 cell supernatants on lipid efflux. The cholesterol content of the foam cells was also measured, and the cholesterol efflux from the macrophages was examined by determining (3)H-labeled cholesterol levels. Expression of ATP-binding cassette transporter (ABC) A1 and ABCG1 of the macrophage foam cells was also assessed. β3-AR activation increased ApoA-I expression in both the HepG2 cells and the supernatants; PPARγ expression was upregulated, but PPARα expression was not. Treatment with GW9662 abolished the increased expression of ApoA-I induced by the β3-AR agonist. The HepG2 cell supernatants decreased the lipid accumulation and increased the cholesterol efflux from the macrophage foam cells. ABCA1 expression, but not ABCG1 expression, increased in the macrophage foam cells treated with BRL37344-treated HepG2 cell supernatants. Activation of β3-AR in HepG2 cells upregulates ApoA-I expression, which might further promote cholesterol efflux from macrophage foam cells. PPARγ might be required for the induction of ApoA-I expression.

  19. Human macrophage foam cells degrade atherosclerotic plaques through cathepsin K mediated processes

    Directory of Open Access Journals (Sweden)

    Larsen Lise

    2010-04-01

    Full Text Available Abstract Background Proteolytic degradation of Type I Collagen by proteases may play an important role in remodeling of atherosclerotic plaques, contributing to increased risk of plaque rupture. The aim of the current study was to investigate whether human macrophage foam cells degrade the extracellular matrix (ECM of atherosclerotic plaques by cathepsin K mediated processes. Methods We 1 cultured human macrophages on ECM and measured cathepsin K generated fragments of type I collagen (C-terminal fragments of Type I collagen (CTX-I 2 investigated the presence of CTX-I in human coronary arteries and 3 finally investigated the clinical potential by measuring circulating CTX-I in women with and without radiographic evidence of aortic calcified atherosclerosis. Results Immune-histochemistry of early and advanced lesions of coronary arteries demonstrated co-localization of Cathepsin-K and CTX-I in areas of intimal hyperplasia and in shoulder regions of advanced plaques. Treatment of human monocytes with M-CSF or M-CSF+LDL generated macrophages and foam cells producing CTX-I when cultured on type I collagen enriched matrix. Circulating levels of CTX-I were not significantly different in women with aortic calcifications compared to those without. Conclusions Human macrophage foam cells degrade the atherosclerotic plaques though cathepsin K mediated processes, resulting in increase in levels of CTX-I. Serum CTX-I was not elevated in women with aortic calcification, likely due to the contribution of CTX-I from osteoclastic bone resorption which involves Cathepsin-K. The human macrophage model system may be used to identify important pathway leading to excessive proteolytic plaque remodeling and plaque rupture.

  20. Analysis of the cell walls of ceramic foams by X-ray microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Rodrigo; Appoloni, Carlos Roberto; Marques, Leonardo Carmezini [Universidade Estadual de Londrina (UEL), PR (Brazil)

    2011-07-01

    Full text: Ceramic foams have a wide range of applications (heat exchangers, liquid metal filters, porous electrodes, composite of rocket nozzles, etc.) due its properties, such as high melt temperature, high porosity, low thermal conductivity and low weight. Since the mechanical resistance of this kind of material is linked to its cell walls features, this research analyzed the cell walls thickness of silicon carbide (SiC) ceramic foams by X-ray microtomography. This technique is a powerful non destructive way to analyze the internal structure of any object, generating images (cross sections) by attenuation of the X-ray beam. The analyses of these images allow us to determine the samples structural parameters through specific software. The samples have pore densities of 30, 60 and 100 pore per inch (ppi). A Skyscan-1172 microtomography, operated at 50 kV high tension and 200 {mu}A current was utilized for the measurements. The spatial resolution obtained was 24.8 {mu}m and the measurement time was around 30 minutes for each sample. The analyses show that the cell walls of the 30 ppi sample have micropores. These micropores were observed at same images of 60 ppi cross sections too, but they were not observed at 100 ppi sample. Its probable that the cell walls of 100 ppi sample have micropores smaller than the resolution achieved. (author)

  1. Preparation And Characterization Of Silicon Carbide Foam By Using In-Situ Generated Polyurethane Foam

    Directory of Open Access Journals (Sweden)

    Shalini Saxena

    2015-08-01

    Full Text Available Abstract The open cell silicon carbide SiC foam was prepared using highly crosslinked hybrid organic- inorganic polymer resin matrix. As inorganic polymer polycarbosilane was taken and organic resin was taken as a mixture of epoxy resin and diisocyanates. The resultant highly crosslinked hybrid resin matrix on heating and subsequently on pyrolysis yielded open cell silicon carbide foam. The hybrid resin matrix was characterized by Fourier transform Infrared Spectroscopy FT-IR and thermal properties i.e. Thermogravimetric analysis TGA amp Differential Scanning Calorimetry DSC were also studied. The morphological studies of silicon carbide ceramic foam were carried out using X-ray Spectroscopy XRD amp Scanning Electron Microscopy SEM.

  2. Model fire tests on polyphosphazene rubber and polyvinyl chloride (PVC)/nitrile rubber foams

    Science.gov (United States)

    Widenor, W. M.

    1978-01-01

    A video tape record of model room fire tests was shown, comparing polyphosphazene (P-N) rubber and polyvinyl chloride (PVC)/nitrile rubber closed-cell foams as interior finish thermal insulation under conditions directly translatable to an actual fire situation. Flashover did not occur with the P-N foam and only moderate amounts of low density smoke were formed, whereas with the PVC/nitrile foam, flashover occurred quickly and large volumes of high density smoke were emitted. The P-N foam was produced in a pilot plant under carefully controlled conditions. The PVC/nitrile foam was a commercial product. A major phase of the overall program involved fire tests on P-N open-cell foam cushioning.

  3. Berberine promotes the development of atherosclerosis and foam cell formation by inducing scavenger receptor A expression in macrophage

    Institute of Scientific and Technical Information of China (English)

    Ke Li; Wenqi Yao; Xiudan Zheng; Kan Liao

    2009-01-01

    Berberine is identified to lower the serum cholesterol level in human and hamster through the induction of low density lipoproteins (LDL) receptor in hepatic cells. To evaluate its potential in preventing atherosclerosis, the effect of berberine on atherosclerosis development in apolipoprotein E-deficient (apoE-/-) mice was investigated, in apoE-/-mice, berberine induced in vivo foam cell formation and promoted atherosclerosis development. The foam cell for-mation induced by berberine was also observed in mouse RAW264.7 cells, as well as in mouse and human primary macrophages. By inducing scavenger receptor A (SR-A) expression in macrophages, berberine increased the uptake of modified LDL (DiO-Ac-LDL). Berberine-induced SR-A expression was also observed in macrophage foam cells in vivo and in the cells at atherosclerotic lesion. Analysis in RAW264.7 cells indicated that berberine induced SR-A ex-pression by suppressing PTEN expression, which led to sustained Akt activation. Our results suggest that to evaluate the potential of a cholesterol-reducing compound in alleviating atherosclerosis, its effect on the cells involved in ath-erosclerosis development, such as macrophages, should also be considered. Promotion of foam cell formation could counter-balance the beneficial effect of lowering serum cholesterol.

  4. The Ca2+ Antagonizing Effect of Chinese Cobra Venom Factor on Formation of Macrophage-derived Foam Cells

    Institute of Scientific and Technical Information of China (English)

    谭健苗; 杨向东; 姜志胜; 李亮

    2007-01-01

    Purpose CCVF was isolated from Chinese cobra (Naja naja) venom, its Ca2+ antagonizing effect on formation of macrophage-derived foam cells was explored in these studies. Methods Foam cell models were induced with C57BL/6J mouse peritoneal macrophages incubated in 10mg/L oxidized low density lipoprotein (OLDL), and their intracellular Ca2+ levels influenced both slowly and transiently by CCVF were determined with the technique of Ca2+ fluorescent indicator. Results The intracellular Ca2+ level with the macrophages incubated in 10mg/L OLDL and 10mg/L CCVF was 40.2% of the macrophages incubated in 10mg/L OLDL (P<0.05); While the transient influence of CCVF on the intracellular Ca2+ levels were not significant. Conclusion CCVF exerted a long-lasting antagonizing role on the enhancement of intracellular Ca2+ levels, thus inhibited the formation of macrophage-derived foam cell.

  5. EFFECT OF SPECIMEN ASPECT RATIO ON FATIGUE LIFE OF CLOSED CELL Al-Si-Ca ALLOY FOAM

    Institute of Scientific and Technical Information of China (English)

    Amkee Kim; Ilhyun Kim

    2008-01-01

    Quasi-static and compressive fatigue tests on the closed cell Al-Si-Ca alloy foam specimens with three different aspect ratios were performed.It turned out that the onset of cyclic shortening of foam with a lower aspect ratio took place earlier and the fatigue strength was lower compared with the specimen with a higher aspect ratio,although aU the dimensions of specimen satisfied the seven times the cell size criterion,while the quasi-static stress-strain curves were almost same having same Young's modulus,yield stress and plateau stress.Therefore,the seven times the cell size criterion for the quasi-static compression behavior was not applicable to the fatigue analysis of Al-Si-Ca alloy foam.

  6. Apelin-13 impedes foam cell formation by activating Class III PI3K/Beclin-1-mediated autophagic pathway.

    Science.gov (United States)

    Yao, Feng; Lv, Yun-Cheng; Zhang, Min; Xie, Wei; Tan, Yu-Lin; Gong, Duo; Cheng, Hai-Peng; Liu, Dan; Li, Liang; Liu, Xiao-Yan; Zheng, Xi-Long; Tang, Chao-Ke

    2015-10-30

    Apelin-13, an adipokine, promotes cholesterol efflux in macrophages with antiatherosclerotic effect. Autophagy, an evolutionarily ancient response to cellular stress, has been involved in atherosclerosis. Therefore, the purpose of this study was to investigate whether apelin-13 regulates macrophage foam cell cholesterol metabolism through autophagy, and also explore the underlying mechanisms. Here, we revealed that apelin-13 decreased lipid accumulation in THP-1 derived macrophages through markedly enhancing cholesterol efflux. Our study further demonstrated that apelin-13 induced autophagy via activation of Class III phosphoinositide 3-kinase (PI3K) and Beclin-1. Inhibition of Class III PI3K and Beclin-1 suppressed the stimulatory effects of apelin-13 on autophagy activity. The present study concluded that apelin-13 reduces lipid accumulation of foam cells by activating autophagy via Class III PI3K/Beclin-1 pathway. Therefore, our results provide brand new insight about apelin-13 inhibiting foam cell formation and highlight autophagy as a promising therapeutic target in atherosclerosis.

  7. Development of Iron-based Closed-Cell Foams by Powder Forging and Rolling

    Science.gov (United States)

    Paswan, Dayanand; Mistry, Dhananjay; Sahoo, K. L.; Srivastava, V. C.

    2013-08-01

    In the present investigation, an attempt has been made to develop in situ sandwich Fe-based foams using powder forging and rolling. Several metal carbonates are first studied by thermo gravimetric analysis to find out their suitability to be used as foaming agent for iron-based foams. Barium carbonate is found to be the most promising foaming agent among other suitable options studied such as SrCO3, CaCO3, MgCO3, etc. The effects of process parameters such as precursor composition, sintering temperature, foaming temperature and time, and content of foaming agent have been studied. The microstructural characteristics of the sintered precursor have been studied by means of optical and scanning electron microscopy. It was found that a good pore structure can be obtained using 2-3% C in Fe and 3% BaCO3 as foaming agent and by foaming at around 1350 °C for 3-6 min.

  8. Chronicles of foam films.

    Science.gov (United States)

    Gochev, G; Platikanov, D; Miller, R

    2016-07-01

    The history of the scientific research on foam films, traditionally known as soap films, dates back to as early as the late 17th century when Boyle and Hooke paid special attention to the colours of soap bubbles. Their inspiration was transferred to Newton, who began systematic study of the science of foam films. Over the next centuries, a number of scientists dealt with the open questions of the drainage, stability and thickness of foam films. The significant contributions of Plateau and Gibbs in the middle/late 19th century are particularly recognized. After the "colours" method of Newton, Reinold and Rücker as well as Johhonnot developed optical methods for measuring the thickness of the thinner "non-colour" films (first order black) that are still in use today. At the beginning of the 20th century, various aspects of the foam film science were elucidated by the works of Dewar and Perrin and later by Mysels. Undoubtedly, the introduction of the disjoining pressure by Derjaguin and the manifestation of the DLVO theory in describing the film stability are considered as milestones in the theoretical development of foam films. The study of foam films gained momentum with the introduction of the microscopic foam film methodology by Scheludko and Exerowa, which is widely used today. This historical perspective serves as a guide through the chronological development of knowledge on foam films achieved over several centuries.

  9. A semi-parabolic wake model for large offshore wind farms based on the open source CFD solver OpenFOAM

    Directory of Open Access Journals (Sweden)

    Cabezón D.

    2014-01-01

    Full Text Available Wake effect represents one of the main sources of energy loss and uncertainty when designing offshore wind farms. Traditionally analytical models have been used to optimize and estimate power deficits. However these models have shown to underestimate wake effect and consequently overestimate output power [1, 2]. This means that analytical models can be very helpful at optimizing preliminary layouts but not as accurate as needed for an ultimate fine design. Different techniques can be found in the literature to study wind turbine wakes that include simplified kinematic models and more advanced field models, that solve flow equations with different turbulence closure schemes. See the review papers of Crespo et al. [3], Vermeer et al. [4], and Sanderse et al. [5]. Purely elliptic Computational Fluid Dynamics (CFD models based on the actuator disk technique have been developed during the last years [6–8]. They consider wind turbine rotor as a disk where a distribution of axial forces act over the incoming air. It is a fair approach but it can still be computationally expensive for big wind farms in an operative mode. With this technique still active, an alternative approach inspired on the parabolic wake models [9, 10] is proposed. Wind turbine rotors continue to be represented as actuator disks but now the domain is split into subdomains containing one or more wind turbines. The output of each subdomain is mapped onto the input boundary of the next one until the end of the domain is reached, getting a considerable decrease on computational time, by a factor of order 10. As the model is based on the open source CFD solver OpenFOAM, it can be parallelized to speed-up convergence. The near wake is calculated so no initial wind speed deficit profiles have to be supposed as in totally parabolic models and alternative turbulence models, such as the anisotropic Reynolds Stress Model (RSM can be used. Traditional problems of elliptic models related to

  10. An extension of the open-source porousMultiphaseFoam toolbox dedicated to groundwater flows solving the Richards' equation

    CERN Document Server

    Horgue, Pierre; Guibert, Romain; Debenest, Gérald

    2015-01-01

    In this note, the existing porousMultiphaseFoam toolbox, developed initially for any two-phase flow in porous media is extended to the specific case of the Richards' equation which neglect the pressure gradient of the non-wetting phase. This model is typically used for saturated and unsaturated groundwater flows. A Picard's algorithm is implemented to linearize and solve the Richards' equation developed in the pressure head based form. This new solver of the porousMultiphaseFoam toolbox is named groundwaterFoam. The validation of thesolver is achieved by a comparison between numerical simulations and results obtained from the literature. Finally, a parallel efficiency test is performed on a large unstructured mesh and exhibits a super-linear behavior as observed for the other solvers of the toolbox.

  11. Insulin and glucose play a role in foam cell formation and function

    Directory of Open Access Journals (Sweden)

    Keller Susanna R

    2006-06-01

    Full Text Available Abstract Background Foam cell formation in diabetic patients often occurs in the presence of high insulin and glucose levels. To test whether hyperinsulinemic hyperglycemic conditions affect foam cell differentiation, we examined gene expression, cytokine production, and Akt phosphorylation in human monocyte-derived macrophages incubated with two types of oxidized low density lipoprotein (LDL, minimally modified LDL (mmLDL and extensively oxidized LDL (OxLDL. Methods and results Using Affymetrix GeneChip® arrays, we found that several genes directly related to insulin signaling were changed. The insulin receptor and glucose-6-phosphate dehydrogenase were upregulated by mmLDL and OxLDL, whereas insulin-induced gene 1 was significantly down-regulated. In hyperinsulinemic hyperglycemic conditions, modified LDL upregulated Akt phosphorylation and expression of the insulin-regulated aminopeptidase. The level of proinflammatory cytokines, IL-lβ, IL-12, and IL-6, and of a 5-lipoxygenase eicosanoid, 5-hydroxyeicosatetraenoic acid (5-HETE, was also increased. Conclusion These results suggest that the exposure of macrophages to modified low density lipoproteins in hyperglycemic hyperinsulinemic conditions affects insulin signaling and promotes the release of proinflammatory stimuli, such as cytokines and eicosanoids. These in turn may contribute to the development of insulin resistance.

  12. Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

    Science.gov (United States)

    Herring, Helen M.

    2008-01-01

    Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

  13. Evaluation of Experimental Parameters in the Accelerated Aging of Closed-Cell Foam Insulation

    Energy Technology Data Exchange (ETDEWEB)

    Stovall, Therese K [ORNL; Vanderlan, Michael [ORNL; Atchley, Jerald Allen [ORNL

    2012-12-01

    The thermal conductivity of many closed-cell foam insulation products changes over time as production gases diffuse out of the cell matrix and atmospheric gases diffuse into the cells. Thin slicing has been shown to be an effective means of accelerating this process in such a way as to produce meaningful results. Efforts to produce a more prescriptive version of the ASTM C1303 standard test method led to the ruggedness test described here. This test program included the aging of full size insulation specimens for time periods of five years for direct comparison to the predicted results. Experimental parameters under investigation include: slice thickness, slice origin (at the surface or from the core of the slab), thin slice stack composition, product facings, original product thickness, product density, and product type. The test protocol has been completed and this report provides a detailed evaluation of the impact of the test parameters on the accuracy of the 5-year thermal conductivity prediction.

  14. LFT foam - Lightweight potential for semi-structural components through the use of long-glass-fiber-reinforced thermoplastic foams

    Science.gov (United States)

    Roch, A.; Huber, T.; Henning, F.; Elsner, P.

    2014-05-01

    Investigations on PP-LGF30 foam sandwiches have been carried out using different manufacturing processes: standard injection molding, MuCell® and LFT-D foam. Both chemical and physical blowing agents were applied. Precision mold opening (breathing mold technology) was selected for the foaming process. The integral foam design, which can be conceived as a sandwich structure, helps to save material in the neutral axis area and maintains a distance between load-bearing, unfoamed skin layers. The experiments showed that, at a constant mass per unit area, integral foams have a significantly higher flexural rigidity than compact components, due to their greater area moment of inertia after foaming: with an increase of the wall thickness from 3.6 mm to 4.4 mm compared to compact construction, the flexural rigidity increased by 75 %. With a final wall thickness of 5.8 mm an increase of 300 % was measured. Compared to non-reinforced components that show significant embrittlement during foaming, the energy absorption capacity (impact strength) of LFT foam components remains almost constant.

  15. Zinc oxide nanoparticles induce migration and adhesion of monocytes to endothelial cells and accelerate foam cell formation

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yuka; Tada-Oikawa, Saeko [Graduate School of Regional Innovation Studies, Mie University, Tsu (Japan); Ichihara, Gaku [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya (Japan); Yabata, Masayuki; Izuoka, Kiyora [Graduate School of Regional Innovation Studies, Mie University, Tsu (Japan); Suzuki, Masako; Sakai, Kiyoshi [Nagoya City Public Health Research Institute, Nagoya (Japan); Ichihara, Sahoko, E-mail: saho@gene.mie-u.ac.jp [Graduate School of Regional Innovation Studies, Mie University, Tsu (Japan)

    2014-07-01

    Metal oxide nanoparticles are widely used in industry, cosmetics, and biomedicine. However, the effects of exposure to these nanoparticles on the cardiovascular system remain unknown. The present study investigated the effects of nanosized TiO{sub 2} and ZnO particles on the migration and adhesion of monocytes, which are essential processes in atherosclerogenesis, using an in vitro set-up of human umbilical vein endothelial cells (HUVECs) and human monocytic leukemia cells (THP-1). We also examined the effects of exposure to nanosized metal oxide particles on macrophage cholesterol uptake and foam cell formation. The 16-hour exposure to ZnO particles increased the level of monocyte chemotactic protein-1 (MCP-1) and induced the migration of THP-1 monocyte mediated by increased MCP-1. Exposure to ZnO particles also induced adhesion of THP-1 cells to HUVECs. Moreover, exposure to ZnO particles, but not TiO{sub 2} particles, upregulated the expression of membrane scavenger receptors of modified LDL and increased cholesterol uptake in THP-1 monocytes/macrophages. In the present study, we found that exposure to ZnO particles increased macrophage cholesterol uptake, which was mediated by an upregulation of membrane scavenger receptors of modified LDL. These results suggest that nanosized ZnO particles could potentially enhance atherosclerogenesis and accelerate foam cell formation. - Highlights: • Effects of metal oxide nanoparticles on foam cell formation were investigated. • Exposure to ZnO nanoparticles induced migration and adhesion of monocytes. • Exposure to ZnO nanoparticles increased macrophage cholesterol uptake. • Expression of membrane scavenger receptors of modified LDL was also increased. • These effects were not observed after exposure to TiO{sub 2} nanoparticles.

  16. Mechanical characterization of the role of defects in sintered FeCrAIY foams

    Institute of Scientific and Technical Information of China (English)

    M. Kepets; T. J. Lu; A. P. Dowling

    2007-01-01

    Open celled metal foams fabricated through metal sintering are a new class of material that offers novel mechanical and acoustic properties. Previously, polymer foams have been widely used as a means of absorbing acous-tic energy. However, the structural applications of these foams are limited. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys. In this first part of two-paper series, the mechanical properties of open-celled steel alloy (FeCrAlY) foams were characterized under uniaxial compression and shear loading.Compared to predictions from established models, a signi-ficant knockdown in material properties was observed. This knockdown was attributed to the presence of defects throu-ghout the microstructure that result from the unique fabri-cation process. Further in situ tests were carded out in a SEM (scanning electronic microscope) in order to investigate the effects of defects on the properties of the foams. Typi-cally, the onset of plastic yielding was observed to occur at defect locations within the microstructure. At lower relative densities, ligament bending dominates, with the deformation initializing at defects. At higher relative densities, an additional deformation mechanism associated with mem-brane elements was observed. In the follow-up of this paper,a finite element model will be constructed to quantify the effects of defects on the mechanical performance of the open-cell foam.

  17. Preparation of precursor for stainless steel foam

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiang-yang; LI Shan-ni; LI Jie; LIU Ye-xiang

    2008-01-01

    The effects of polyurethane sponge pretreatment and slurry compositions on the slurry loading in precursor were discussed, and the,performances of stainless steel foams prepared from precursors with different slurry loadings and different particle sizes of the stainless steel powder were also investigated. The experimental results show that the pretreatment of sponge with alkaline solution is effective to reduce the jam of cells in precursor and ensure the slurry to uniformly distribute in sponge, and it is also an effective method for increasing the slurry loading in precursor; the mass fraction of additive A and solid content in slurry greatly affect the slurry loading in precursor, when they are kept in 9%-13% and 52%-75%, respectively, the stainless steel foam may hold excellent 3D open-cell network structure and uniform muscles; the particle size of the stainless steel powder and the slurry loading in precursor have great effects on the bending strength, apparent density and open porosity of stainless steel foam; when the stainless steel powder with particle size of 44 tan and slurry loading of 0.5 g/cm3 in precursor are used, a stainless steel foam can be obtained, which has open porosity of 81.2%, bending strength of about 51.76 MPa and apparent density of about 1.0 g/cm3.

  18. Free cholesterol-induced cytotoxicity a possible contributing factor to macrophage foam cell necrosis in advanced atherosclerotic lesions.

    Science.gov (United States)

    Tabas, I

    1997-10-01

    A major characteristic of advanced atherosclerotic lesions is the necrotic, or lipid, core, which likely plays an important role in the clinical progression of these lesions. Recent data suggest that the necrotic core forms primarily as a consequence of macrophage foam cell necrosis. Lesional macrophages initially accumulate mostly cholesteryl esters, but macrophages in advanced lesions contain large amounts of unesterified, or free, cholesterol (FC). Although there are many theories as to why macrophage foam cells die in advanced lesions, the fact that a high FC:phospholipid (PL) ratio in cellular membranes can be toxic to cells suggests that FC-induced cytotoxicity may contribute to foam cell necrosis. The mechanism of FC cytotoxicity can be explained by disturbances in membrane protein function as a result of "stiffening" of the bilayer and by formation of intracellular FC crystals that can cause physical damage to cellular organelles. Macrophages appear to respond to FC loading by a fascinating adaptive response, namely the induction of PL biosynthesis, which initially keeps the cellular FC:PL ratio below toxic levels. Studies with cultured macrophages have demonstrated that a failure of this adaptive response leads to FC-induced foam cell cytotoxicity and necrosis, and thus a similar series of events in advanced atherosclerotic lesions could provide an explanation for the development of the necrotic core. (Trends Cardiovasc Med 1997;7: 256-263). © 1997, Elsevier Science Inc.

  19. Sound Absorption Characteristics of Aluminum Foams Treated by Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Wei Jin

    2015-11-01

    Full Text Available Open-celled aluminum foams with different pore sizes were fabricated. A plasma electrolytic oxidation (PEO treatment was applied on the aluminum foams to create a layer of ceramic coating. The sound absorption coefficients of the foams were measured by an impedance tube and they were calculated by a transfer function method. The experimental results show that the sound absorption coefficient of the foam increases gradually with the decrease of pore size. Additionally, when the porosity of the foam increases, the sound absorption coefficient also increases. The PEO coating surface is rough and porous, which is beneficial for improvement in sound absorption. After PEO treatment, the maximum sound absorption of the foam is improved to some extent.

  20. Open source bioimage informatics for cell biology.

    Science.gov (United States)

    Swedlow, Jason R; Eliceiri, Kevin W

    2009-11-01

    Significant technical advances in imaging, molecular biology and genomics have fueled a revolution in cell biology, in that the molecular and structural processes of the cell are now visualized and measured routinely. Driving much of this recent development has been the advent of computational tools for the acquisition, visualization, analysis and dissemination of these datasets. These tools collectively make up a new subfield of computational biology called bioimage informatics, which is facilitated by open source approaches. We discuss why open source tools for image informatics in cell biology are needed, some of the key general attributes of what make an open source imaging application successful, and point to opportunities for further operability that should greatly accelerate future cell biology discovery.

  1. Uptake of dexamethasone incorporated into liposomes by macrophages and foam cells and its inhibitory effect on cellular cholesterol ester accumulation.

    Science.gov (United States)

    Chono, Sumio; Morimoto, Kazuhiro

    2006-09-01

    To confirm the efficacy of dexamethasone incorporated into liposomes in the treatment of atherosclerosis, the uptake of dexamethasone-liposomes by macrophages and foam cells and its inhibitory effect on cellular cholesterol ester accumulation in these cells were investigated in-vitro. Dexamethasone-liposomes were prepared with egg yolk phosphatidylcholine, cholesterol and dicetylphosphate in a lipid molar ratio of 7/2/1 by the hydration method. This was adjusted to three different particle sizes to clarify the influence of particle size on the uptake by the macrophages and foam cells, and the inhibitory effect on cellular cholesterol ester accumulation. The distribution of particle sizes of dexamethasone-liposomes were 518.7+/-49.5 nm (L500), 202.2+/-23.1 nm (L200), and 68.6+/-6.5 nm (L70), respectively. For each size, dexamethasone concentration and dexamethasone/lipid molar ratio in dexamethasone-liposome suspension were 1 mg dexamethasone mL-1 and 0.134 mol dexamethasone mol-1 total lipids, respectively. The zeta potential was approximately -70 mV for all sizes. Dexamethasone-liposomes or free dexamethasone were added to the macrophages in the presence of oxidized low density lipoprotein (oxLDL) and foam cells, and then incubated at 37 degrees C. The uptake amount of dexamethasone by the macrophages and foam cells after a 24-h incubation was L500>L200>free dexamethasone>L70. The macrophages in the presence of oxLDL and foam cells were incubated with dexamethasone-liposomes or free dexamethasone for 24 h at 37 degrees C to evaluate the inhibitory effect on the cellular cholesterol ester accumulation. The cellular cholesterol ester level in the macrophages treated with oxLDL was significantly increased compared with that in macrophages without additives. L500, L200 and free dexamethasone significantly inhibited this cholesterol ester accumulation. L500, L200 and free dexamethasone also significantly reduced cellular cholesterol ester accumulation in foam cells. In

  2. NF-kB activity-dependent P-selectin involved in ox-LDL-induced foam cell formation in U937 cell

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi, E-mail: wangyi2004a@126.com [Department of Cardiology, Shanghai First People' s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200080 (China); Wang, Xiang; Sun, Minghui; Zhang, Zhenyu; Cao, Heng; Chen, Xiaoqing [Department of Cardiology, Shanghai First People' s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200080 (China)

    2011-08-05

    Highlights: {yields} Ox-LDL induced foam cell formation in the human U937 promonocytic cell line in a dose- and time-dependent manner. {yields} Ox-LDL induced expression of P-selectin through degradation of IkBa and augment of NF-kB activity and protein level during macrophage-derived foam cell formation. {yields} P-selectin and NF-kB may be identified as pivotal regulators of ox-LDL-induced foam cell formation. {yields} Therapy based on the inhibition of P-selectin and NF-kB may complement conventional treatments to prevent atherosclerosis. -- Abstract: Oxidized low-density lipoprotein (ox-LDL) plays a critical role in regulation of atherosclerosis. However, little is known about the role of Nuclear factor kB (NF-kB) activity-dependent P-selectin in ox-LDL-induced foam cell formation during atherosclerosis. In this study, we first investigated ox-LDL induced foam cell formation in the human U937 promonocytic cell line in a dose- and time-dependent manner. Treatment of U937 cells with ox-LDL increased lipid accumulation as well as intracellular cholesterol content. Next, a comparative analysis of gene expression profiling using cDNA microarray and Real-time-PCR indicated that ox-LDL exposure induced, in three treated groups, an extremely marked increase in the mRNA level of P-selectin. Protein levels of P-selectin and its upstream regulators IkBa and NF-kB showed that NF-kB pathway is involved in the ox-LDL-induced foam cell formation. Finally, overexpression of NF-kB significantly accelerated, whereas, inhibition of NF-kB with siRNA remarkably attenuated ox-LDL-induced macrophage-derived foam cell formation. It was concluded that the activity of NF-kB is augmented during macrophage-derived foam cell formation. Activation of NF-kB increased, whereas, inhibition of NF-kB decreased ox-LDL-induced P-selectin expression and lipid accumulation in macrophages, suggesting ox-LDL induced expression of P-selectin through degradation of IkBa and activation of NF-kB in the

  3. Hypocholesterolemia, foam cell accumulation, but no atherosclerosis in mice lacking ABC-transporter A1 and scavenger receptor BI

    NARCIS (Netherlands)

    Zhao, Ying; Pennings, Marieke; Vrins, Carlos L. J.; Calpe-Berdiel, Laura; Hoekstra, Menno; Kruijt, J. Kar; Ottenhoff, Roelof; Hildebrand, Reeni B.; van der Sluis, Ronald; Jessup, Wendy; Le Goff, Wilfried; Chapman, M. John; Huby, Thierry; Groen, Albert K.; Van Berkel, Theo J. C.; Van Eck, Miranda

    2011-01-01

    High-density lipoprotein (HDL) mediated reverse cholesterol transport (RCT) is regarded to be crucial for prevention of foam cell formation and atherosclerosis. ABC-transporter A1 (ABCA1) and scavenger receptor BI (SR-BI) are involved in the biogenesis of HDL and the selective delivery of HDL choles

  4. Adding complex terrain and stable atmospheric condition capability to the OpenFOAM-based flow solver of the simulator for on/offshore wind farm applications (SOWFA

    Directory of Open Access Journals (Sweden)

    Churchfield Matthew J.

    2014-01-01

    Full Text Available The National Renewable Energy Laboratory's Simulator for On/Offshore Wind Farm Applications contains an OpenFOAM-based flow solver for performing large-eddy simulation of flow through wind plants. The solver computes the atmospheric boundary layer flow and models turbines with actuator lines. Until recently, the solver was limited to flows over flat terrain and could only use the standard Smagorinsky subgrid-scale model. In this work, we present our improvements to the flow solver that enable us to 1 use any OpenFOAM-standard subgrid-scale model and 2 simulate flow over complex terrain. We used the flow solver to compute a stably stratified atmospheric boundary layer using both the standard and the Lagrangian-averaged scale-independent dynamic Smagorinsky models. Surprisingly, the results using the standard Smagorinsky model compare well to other researchers' results of the same case, although it is often said that the standard Smagorinsky model is too dissipative for accurate stable stratification calculations. The scale-independent dynamic subgrid-scale model produced poor results, probably due to the spikes in model constant with values as high as 4.6. We applied a simple bounding of the model constant to remove these spikes, which caused the model to produce results much more in line with other researchers' results. We also computed flow over a simple hilly terrain and performed some basic qualitative analysis to verify the proper operation of the terrain-local surface stress model we employed.

  5. Zirconium oxide ceramic foam: a promising supporting biomaterial for massive production of glial cell line-derived neurotrophic factor.

    Science.gov (United States)

    Liu, Zhong-wei; Li, Wen-qiang; Wang, Jun-kui; Ma, Xian-cang; Liang, Chen; Liu, Peng; Chu, Zheng; Dang, Yong-hui

    2014-12-01

    This study investigated the potential application of a zirconium oxide (ZrO2) ceramic foam culturing system to the production of glial cell line-derived neurotrophic factor (GDNF). Three sets of ZrO2 ceramic foams with different pore densities of 10, 20, and 30 pores per linear inch (PPI) were prepared to support a 3D culturing system. After primary astrocytes were cultured in these systems, production yields of GDNF were evaluated. The biomaterial biocompatibility, cell proliferation and activation of cellular signaling pathways in GDNF synthesis and secretion in the culturing systems were also assessed and compared with a conventional culturing system. In this study, we found that the ZrO2 ceramic foam culturing system was biocompatible, using which the GDNF yields were elevated and sustained by stimulated cell proliferation and activation of signaling pathways in astrocytes cultured in the system. In conclusion, the ZrO2 ceramic foam is promising for the development of a GDNF mass production device for Parkinson's disease treatment.

  6. Effects of Ammonium Phosphate on Structure of Cell and Carb on Layer after Burned of Polyurethane-imide Foams

    Directory of Open Access Journals (Sweden)

    ZHANG Qi

    2017-06-01

    Full Text Available Using ammonium phosphate as flame retardant,polyurethane-imide foams were synthesized via PI pre-polymer method. The effect of APP on the cell structure, thermal stability and carbon layer morphology were analyzed by polarizing microscope,SEM and TGA. The effect of cell structure change on carbon layer morphology was focused and discussed and the formation process of carbon layer was simulated. The results show that cell diameter drops sharply from 690.25μm to 277.83μm, the foam density increases with the increasing addition of APP;the addition of APP makes char yield increased by 30%; the cell wall and peak respectively expand into rod-like and spherical carbon layer, but the cell films burn into holes. Furthermore, the sizes of rod-like and spherical carbon layer increase, but the holes decrease with the increasing addition of APP.

  7. Generation of realistic nonwoven and foam filter geometry and mesh for filtration simulation using open-source tools

    OpenAIRE

    Abishek, S.; Mullins, B; King, A.; Kasper, G; Heikamp, W.

    2016-01-01

    Recovery of liquid aerosols (mists) from industrial processes is typically accomplished through coalescence filtration, employing highly porous nonwoven (fibrous), knitted or foam media which are regarded to potentially provide high collection efficiencies. Highly resolved pore-scale computational fluid dynamics (CFD) analysis of mist filtration processes is increasingly becoming an important tool for design and optimization of such filter media. A key to efficient application-specific optimi...

  8. Differential regulation of macropinocytosis in macrophages by cytokines: implications for foam cell formation and atherosclerosis.

    Science.gov (United States)

    Michael, Daryn R; Ashlin, Tim G; Davies, Charlotte S; Gallagher, Hayley; Stoneman, Thomas W; Buckley, Melanie L; Ramji, Dipak P

    2013-10-01

    A key event during the formation of lipid-rich foam cells during the progression of atherosclerosis is the uptake of modified low-density lipoproteins (LDL) by macrophages in response to atherogenic mediators in the arterial intima. In addition to scavenger receptor-dependent uptake of LDL, macropinocytosis is known to facilitate the uptake of LDL through the constitutive and passive internalization of large quantities of extracellular solute. In this study we confirm the ability of macropinocytosis to facilitate the uptake of modified LDL by human macrophages and show its modulation by TGF-β, IFN-γ, IL-17A and IL-33. Furthermore we show that the TGF-β-mediated inhibition of macropinocytosis is a Smad-2/-3-independent process.

  9. Anti-atherosclerotic potential of gossypetin via inhibiting LDL oxidation and foam cell formation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing-Hsien [School of Nutrition, Chung Shan Medical University, Taichung, Taiwan (China); Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Tsai, Chia-Wen [Department of Nutrition, China Medical University, Taichung, Taiwan (China); Wang, Chi-Ping [Department of Clinical Laboratory, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Lin, Hui-Hsuan, E-mail: linhh@csmu.edu.tw [Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan (China); School of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung, Taiwan (China)

    2013-10-15

    Gossypetin, a flavone originally isolated from Hibiscus species, has been shown to possess antioxidant, antimicrobial, and antimutagenic activities. Here, we investigated the mechanism(s) underlying the anti-atherosclerotic potential of gossypetin. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging activity assay showed that the addition of > 50 μM of gossypetin could scavenge over 50% of DPPH radicals. The inhibitory effects of gossypetin on the lipid and protein oxidation of LDL were defined by thiobarbituric acid reactive substance (TBARS) assay, the relative electrophoretic mobility (REM) of oxidized LDL (ox-LDL), and fragmentation of apoB in the Cu{sup 2+}-induced oxidation of LDL. Gossypetin showed potential in reducing ox-LDL-induced foam cell formation and intracellular lipid accumulation, and uptake ability of macrophages under non-cytotoxic concentrations. Molecular data showed that these influences of gossypetin might be mediated via peroxisome proliferator-activated receptor α (PPARα)/liver-X receptor α (LXRα)/ATP-binding cassette transporter A1 (ABCA1) and PPARγ/scavenger receptor CD36 pathways, as demonstrated by the transfection of PPARα siRNA or PPARγ expression vector. Our data implied that gossypetin regulated the PPAR signals, which in turn led to stimulation of cholesterol removal from macrophages and delay atherosclerosis. These results suggested that gossypetin potentially could be developed as an anti-atherosclerotic agent. - Highlights: • The anti-atherosclerotic effect of gossypetin in vitro was examined. • Gossypetin inhibited LDL oxidation. • Gossypetin showed potential in reducing on the formation of foam cells. • Gossypetin functions against ox-LDL through PPARa activation and PPARγ depression.

  10. High Strength Silicon Carbide Foams and Their Deformation Behavior

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Silicon carbide (SiC) foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 1.3 g/cm3, with corresponding compressive strengths ranging from about 13 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.

  11. Pore-level numerical analysis of the infrared surface temperature of metallic foam

    Science.gov (United States)

    Li, Yang; Xia, Xin-Lin; Sun, Chuang; Tan, He-Ping; Wang, Jing

    2017-10-01

    Open-cell metallic foams are increasingly used in various thermal systems. The temperature distributions are significant for the comprehensive understanding of these foam-based engineering applications. This study aims to numerically investigate the modeling of the infrared surface temperature (IRST) of open-cell metallic foam measured by an infrared camera placed above the sample. Two typical approaches based on Backward Monte Carlo simulation are developed to estimate the IRSTs: the first one, discrete-scale approach (DSA), uses a realistic discrete representation of the foam structure obtained from a computed tomography reconstruction while the second one, continuous-scale approach (CSA), assumes that the foam sample behaves like a continuous homogeneous semi-transparent medium. The radiative properties employed in CSA are directly determined by a ray-tracing process inside the discrete foam representation. The IRSTs for different material properties (material emissivity, specularity parameter) are computed by the two approaches. The results show that local IRSTs can vary according to the local compositions of the foam surface (void and solid). The temperature difference between void and solid areas is gradually attenuated with increasing material emissivity. In addition, the annular void space near to the foam surface behaves like a black cavity for thermal radiation, which is ensued by copious neighboring skeletons. For most of the cases studied, the mean IRSTs computed by the DSA and CSA are close to each other, except when the material emissivity is highly weakened and the sample temperature is extremely high.

  12. Experiments, modeling and simulation of the magnetic behavior of inhomogeneously coated nickel/aluminum hybrid foams

    Energy Technology Data Exchange (ETDEWEB)

    Jung, A., E-mail: anne.jung@mx.uni-saarland.de [Universität des Saarlandes, Institute of Applied Mechanics, Campus A4 2, 66123 Saarbrücken (Germany); Klis, D., E-mail: d.klis@lte.uni-saarland.de [Universität des Saarlandes, Laboratory for Electromagnetic Theory, Campus C6 3, 66123 Saarbrücken (Germany); Goldschmidt, F., E-mail: f.goldschmidt@mx.uni-saarland.de [Universität des Saarlandes, Institute of Applied Mechanics, Campus A4 2, 66123 Saarbrücken (Germany)

    2015-03-15

    Open-cell metal foams are used as lightweight construction elements, energy absorbers or as support for catalytic coatings. Coating of open-cell metal foams is not only used for catalytic applications, but it leads also to tremendous increase in stiffness and energy absorption capacity. A non-line of sight coating technique for complex 3D structures is electrodeposition. Unfortunately, due to the 3D porosity and the related problems in mass transport limitation during the deposition, it is not possible to produce homogeneously coated foams. In the present contribution, we present a semi-non-destructive technique applicable to determine the coating thickness distribution of magnetic coatings by measuring the remanent magnetic field of coated foams. In order to have a closer look at the mass transport mechanism, a numerical model was developed to predict the field scans for different coating thickness distributions in the foams. For long deposition times the deposition reaches a steady state whereas a Helmholtz equation is sufficient to predict the coating thickness distribution. The applied current density could be identified as the main influencing parameter. Based on the developed model, it is possible to improve the electrodeposition process and hence the homogeneity in the coating thickness of coated metal foams. This leads to enhanced mechanical properties of the hybrid foams and contributes to better and resource-efficient energy absorbers and lightweight materials. - Highlights: • Production of hybrid foams by electrodeposition of nickel on open-cell metal foams. • Magnetic field scans for visualization of spatial coating thickness distribution. • Modeling of magnetic fields of inhomogeneously coated hybrid foams. • Investigation of mass transport limitation during coating by a Helmholtz equation. • Increasing coating homogeneity by use of low current densities and deposition rates.

  13. Foaming volume and foam stability

    Science.gov (United States)

    Ross, Sydney

    1947-01-01

    A method of measuring foaming volume is described and investigated to establish the critical factors in its operation. Data on foaming volumes and foam stabilities are given for a series of hydrocarbons and for a range of concentrations of aqueous ethylene-glycol solutions. It is shown that the amount of foam formed depends on the machinery of its production as well as on properties of the liquid, whereas the stability of the foam produced, within specified mechanical limitations, is primarily a function of the liquid.

  14. Impact of the irregular microgeometry of polyurethane foam on the macroscopic acoustic behavior predicted by a unit-cell model.

    Science.gov (United States)

    Doutres, O; Ouisse, M; Atalla, N; Ichchou, M

    2014-10-01

    This paper deals with the prediction of the macroscopic sound absorption behavior of highly porous polyurethane foams using two unit-cell microstructure-based models recently developed by Doutres, Atalla, and Dong [J. Appl. Phys. 110, 064901 (2011); J. Appl. Phys. 113, 054901 (2013)]. In these models, the porous material is idealized as a packing of a tetrakaidecahedra unit-cell representative of the disordered network that constitutes the porous frame. The non-acoustic parameters involved in the classical Johnson-Champoux-Allard model (i.e., porosity, airflow resistivity, tortuosity, etc.) are derived from characteristic properties of the unit-cell and semi-empirical relationships. A global sensitivity analysis is performed on these two models in order to investigate how the variability associated with the measured unit-cell characteristics affects the models outputs. This allows identification of the possible limitations of a unit-cell micro-macro approach due to microstructure irregularity. The sensitivity analysis mainly shows that for moderately and highly reticulated polyurethane foams, the strut length parameter is the key parameter since it greatly impacts three important non-acoustic parameters and causes large uncertainty on the sound absorption coefficient even if its measurement variability is moderate. For foams with a slight inhomogeneity and anisotropy, a micro-macro model associated to cell size measurements should be preferred.

  15. Parameters affect foaming and foam stability during foam drilling

    Institute of Scientific and Technical Information of China (English)

    Hazaea Mohammed; Youhong SUN; Ould El Houssein Yarbana

    2007-01-01

    The authors presented indoor practice experiments of parameters affect on foaming and foam stability. Experiments were carried out and special equipments were used to determine foaming and foam stability; tests were tabulated and charted. The effects of chemical and physical parameters on foaming and foam stability have been conducted.

  16. THE INTERACTION BETWEEN SHOCK WAVES AND FOAM IN A SHOCK TUBE

    Institute of Scientific and Technical Information of China (English)

    施红辉; Kazuhiko Kawai; Motoyuki Itoh; 俞鸿儒; 姜宗林

    2002-01-01

    An experimental study and a numerical simulation were conducted to investigate the mechanical and thermodynamic processes involved in the interaction between shock waves and low density foam. The experiment was done in a stainless shock tube (80 mm in inner diameter, 10 mm in wall thickness and 5 360 mm in length). The velocities of the incident and reflected compression waves in the foam were measured by using piezo-ceramic pressure sensors. The end-wall peak pressure behind the reflected wave in the foam was measured by using a crystal piezoelectric sensor. It is suggested that the high end-wall pressure may be caused by a rapid contact between the foam and the end-wall surface. Both open-cell and closed-cell foams with different length and density were tested. Through comparing the numerical and experimental end-wall pressure, the permeability coefficients α and β are quantitatively determined.

  17. Permeability of Aluminium Foams Produced by Replication Casting

    Directory of Open Access Journals (Sweden)

    Maxim L. Cherny

    2012-12-01

    Full Text Available The replication casting process is used for manufacturing open-pore aluminum foams with advanced performances, such as stability and repeatability of foam structure with porosity over 60%. A simple foam structure model based on the interaction between sodium chloride solid particles poorly wetted by melted aluminum, which leads to the formation of air pockets (or “air collars”, is proposed for the permeability of porous material. The equation for the minimum pore radius of replicated aluminum foam is derived. According to the proposed model, the main assumption of the permeability model consists in a concentration of flow resistance in a circular aperture of radius rmin. The permeability of aluminum open-pore foams is measured using transformer oil as the fluid, changing the fractions of initial sodium chloride. Measured values of minimum pore size are close to theoretically predicted ones regardless of the particle shape. The expression for the permeability of replicated aluminum foam derived on the basis of the “bottleneck” model of porous media agrees well with the experimental data. The obtained data can be applied for commercial filter cells and pneumatic silencers.

  18. Electrical Conductivity of Aluminium Alloy Foams

    Institute of Scientific and Technical Information of China (English)

    凤仪; 郑海务; 朱震刚; 祖方遒

    2002-01-01

    Closed-cell aluminium alloy foams were produced using the powder metallurgical technique. The effect of porosityand cell diameter on the electrical conductivity of foams was investigated and the results were compared with anumber of models. It was found that the percolation theory can be successfully applied to describe the dependenceof the electrical conductivity of aluminium alloy foams on the relative density. The cell diameter has a negligibleeffect on the electrical conductivity of foams.

  19. Heat Treatment of Closed-Cell A356 + 4 wt.%Cu + 2 wt.%Ca Foam and Its Effect on the Foam Mechanical Behavior

    Science.gov (United States)

    Mirbagheri, S. M. H.; Vali, H.; Soltani, H.

    2016-11-01

    In this investigation, aluminum-silicon alloy foam is developed by adding certain amounts of copper and calcium elements in A356 alloy. Addition of 4 wt.%Cu + 2 wt.%Ca to the melt changed bubbles morphology from ellipsoid to spherical by decreasing Reynolds number and increasing Bond number. Compression behavior and energy absorption of the foams are assessed before and after aging. Solid solution treatment and aging lead to the best mechanical properties with 170% enhancement in yield strength and 185% improvement in energy absorption capacity as compared to non-heat-treated foams. The metallographic observations showed that bubbles geometry and structure in the A356 + 4wt.% Cu + 2 wt.%Ca foam are more homogeneous than the A356 foam.

  20. Heat Treatment of Closed-Cell A356 + 4 wt.%Cu + 2 wt.%Ca Foam and Its Effect on the Foam Mechanical Behavior

    Science.gov (United States)

    Mirbagheri, S. M. H.; Vali, H.; Soltani, H.

    2017-01-01

    In this investigation, aluminum-silicon alloy foam is developed by adding certain amounts of copper and calcium elements in A356 alloy. Addition of 4 wt.%Cu + 2 wt.%Ca to the melt changed bubbles morphology from ellipsoid to spherical by decreasing Reynolds number and increasing Bond number. Compression behavior and energy absorption of the foams are assessed before and after aging. Solid solution treatment and aging lead to the best mechanical properties with 170% enhancement in yield strength and 185% improvement in energy absorption capacity as compared to non-heat-treated foams. The metallographic observations showed that bubbles geometry and structure in the A356 + 4wt.% Cu + 2 wt.%Ca foam are more homogeneous than the A356 foam.

  1. Chondrogenesis of human bone marrow mesenchymal stromal cells in highly porous alginate-foams supplemented with chondroitin sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhao [Department of Orthopaedic, Trauma and Reconstructive Surgery, Charité-Universitätsmedizin-Berlin Campus Benjamin Franklin, Berlin (Germany); Nooeaid, Patcharakamon [Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg (Germany); Kohl, Benjamin [Department of Orthopaedic, Trauma and Reconstructive Surgery, Charité-Universitätsmedizin-Berlin Campus Benjamin Franklin, Berlin (Germany); Roether, Judith A.; Schubert, Dirk W. [Institute of Polymer Materials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg (Germany); Meier, Carola [Department of Orthopaedic, Trauma and Reconstructive Surgery, Charité-Universitätsmedizin-Berlin Campus Benjamin Franklin, Berlin (Germany); Boccaccini, Aldo R. [Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg (Germany); Godkin, Owen; Ertel, Wolfgang; Arens, Stephan [Department of Orthopaedic, Trauma and Reconstructive Surgery, Charité-Universitätsmedizin-Berlin Campus Benjamin Franklin, Berlin (Germany); Schulze-Tanzil, Gundula, E-mail: gundula.schulze@pmu.ac.at [Department of Orthopaedic, Trauma and Reconstructive Surgery, Charité-Universitätsmedizin-Berlin Campus Benjamin Franklin, Berlin (Germany); Institute of Anatomy, Paracelsus Medical University, Nuremberg (Germany)

    2015-05-01

    To overcome the limited intrinsic cartilage repair, autologous chondrocyte or bone-marrow-derived mesenchymal stromal cell (BM-MSC) was implanted into cartilage defects. For this purpose suitable biocompatible scaffolds are needed to provide cell retention, chondrogenesis and initial mechanical stability. The present study should indicate whether a recently developed highly porous alginate (Alg) foam scaffold supplemented with chondroitin sulfate (CS) allows the attachment, survival and chondrogenesis of BM-MSCs and articular chondrocytes. The foams were prepared using a freeze-drying method; some of them were supplemented with CS and subsequently characterized for porosity, biodegradation and mechanical profile. BM-MSCs were cultured for 1–2 weeks on the scaffold either under chondrogenic or maintenance conditions. Cell vitality assays, histology, glycosaminoglycan (sGAG) assay, and type II and I collagen immunolabelings were performed to monitor cell growth and extracellular matrix (ECM) synthesis in the scaffolds. Scaffolds had a high porosity ~ 93–95% with a mean pore sizes of 237 ± 48 μm (Alg) and 197 ± 61 μm (Alg/CS). Incorporation of CS increased mechanical strength of the foams providing gradually CS release over 7 days. Most of the cells survived in the scaffolds. BM-MSCs and articular chondrocytes formed rounded clusters within the scaffold pores. The BM-MSCs, irrespective of whether cultured under non/chondrogenic conditions and chondrocytes produced an ECM containing sGAGs, and types II and I collagen. Total collagen and sGAG contents were higher in differentiated BM-MSC cultures supplemented with CS than in CS-free foams after 14 days. The cell cluster formation induced by the scaffolds might stimulate chondrogenesis via initial intense cell–cell contacts. - Highlights: • Alginate foam scaffolds revealed a high porosity and mean pore size of 197–237 μm. • Chondroitin sulfate was released over 14 days by the scaffolds. • Chondrocytes

  2. Cells — An Open Access Journal of Cell Biology

    Directory of Open Access Journals (Sweden)

    Shu-Kun Lin

    2011-01-01

    Full Text Available To expand the open access publishing project of our newly founded company MDPI [1,2] based in Basel, Switzerland, we are in the process of launching new journals. Based on our success in running journals that represent key areas in science and technology, such as Molecules [3], Sensors [4], Energies [5], Viruses [6], Pharmaceuticals [7], Cancers [8] and Toxins [9], we are launching a new journal entitled Cells. It is an open access journal combining cell biology, molecular biology and biophysics, toward an understanding of cell structure, function and interactions. [...

  3. Enhanced rhamnolipids production via efficient foam-control using stop valve as a foam breaker.

    Science.gov (United States)

    Long, Xuwei; Shen, Chong; He, Ni; Zhang, Guoliang; Meng, Qin

    2017-01-01

    In this study, a stop valve was used as a foam breaker for dealing with the massive overflowing foam in rhamnolipid fermentation. As found, a stop valve at its tiny opening could break over 90% of the extremely stable rhamnolipid foam into enriched liquid when foam flows through the sharp gap in valve. The efficient foam-control by the stop valve considerably improved the rhamnolipid fermentation and significantly enhanced the rhamnolipid productivity by 83% compared to the regular fermentation. This efficient foam breaking was mainly achieved by a high shear rate in combination with fast separation of air from the collapsed foam. Altogether, the stop valve possessed a great activity in breaking rhamnolipid foam, and the involving mechanism holds the potential for developing efficient foam breakers for industrial rhamnolipid fermentation.

  4. THE STRUCTURE CONTROL OF ALUMINUM FOAMS PRODUCED BY POWDER COMPACTED FOAMING PROCESS

    Institute of Scientific and Technical Information of China (English)

    X.H. You; F. Wang; L.C. Wang

    2004-01-01

    A new technique, powder compact foaming process for the production of aluminum foams has been studied in this article. According to this method, the aluminum powder is mixed with a powder foaming agent (TiH2). Subsequent to mixing, the powder blend is hot compacted to obtain a dense semi-finished product. Upon heating to temperatures within the range of the melting point, the foaming agent decomposes to evolve gas and the semi-finished product expands into a porous cellular aluminum. Foaming process is the key in this method. Based on experiments, the foaming characteristics were mainly analyzed and discussed. Experiments show that the aluminum-foam with closed pores and a uniform cell structure of high porosity can be obtained using this method by adjusting the foaming parameters: the content of foaming agent and foaming temperature.

  5. Lentiviral vector-mediated siRNA knockdown of SR-PSOX inhibits foam cell formation in vitro

    Institute of Scientific and Technical Information of China (English)

    Li ZHANG; Hou-jia LIU; Tie-jun LI; Yang YANG; Xian-ling GUO; Meng-chao WU; Yao-cheng RUI; Li-xin WEI

    2008-01-01

    Aim: To investigate the expression of scavenger receptor that binds phosphatidylserine and oxidized lipoprotein (SR-PSOX)/CXC chemokine ligand 16 (CXCL16) in the human monocyte-derived cell line THP-1, and the effect of lentiviral vectors for the stable delivery of SR-PSOX/CXCL16 short hairpin RNA on foam cell formation. Methods: A lentiviral expression vector containing enhanced green fluorescence protein (GFP) and SR-PSOX small interfering RNA (siRNA) (Lenti-SR-PSOXsi), or the control siRNA (Lenti-NC) gene was constructed. A human monocyte-derived cell line THP-1 was transfected with a different multiplicity of infection (MOI) of Lenti-SR-PSOXsi or Lenti-NC, and cultured to obtain stably-transfected THP-1KD and THP-1NC cells. After incubation with oxidatively-modified, low-density lipoprotein (Ox-LDL), the expression of SR-PSOX/CXCL16 mRNA was determined by real-time PCR. The expression of the SR-PSOX/CXCL16 protein was detected by flow cytometry analysis. The effect of Lenti-SR-PSOXsi on foam cell formation was assessed by Oil red O-stain analysis. Results: Ox-LDL increased the expres-sion of SR-PSOX/CXCL 16 mRNA in a time- and dose-dependent manner in THP-1 cells. Four days after transfection with Lenti-SR-PSOXsi (MOI: 100), the percent-age of GFP expression cells was over 89.3%. The expression of the SR-PSOX/ CXCL 16 mRNA and protein in THP- 1KD cells significantly decreased compared with the parent cells, even the THP-1KD cells stimulated with 40 mg/L Ox-LDL. Ox-LDL uptake experiments in THP-1- and THP- 1KD-derived macrophages indi-cated that SR-PSOX/CXCL16 deficiency decreased the development of macroph-age-derived foam cell formation. Conclusion: The above data showed that SR-PSOX siRNA delivered by using lentiviral vectors in THP-1 cells was a powerful tool for studying the effect of SR-PSOX, and decreased the expression of the SR-PSOX gene by inhibiting macrophage-derived foam cell formation.

  6. Spin foams

    CERN Document Server

    Engle, Jonathan

    2013-01-01

    The spin foam framework provides a way to define the dynamics of canonical loop quantum gravity in a spacetime covariant way, by using a path integral over histories of quantum states which can be interpreted as `quantum space-times'. This chapter provides a basic introduction to spin foams aimed principally at beginning graduate students and, where possible, at broader audiences.

  7. Jellyfish skin polysaccharides: extraction and inhibitory activity on macrophage-derived foam cell formation.

    Science.gov (United States)

    Zhang, Hai-Lin; Cui, Shao-Hua; Zha, Xue-Qiang; Bansal, Vibha; Xue, Lei; Li, Xiao-Long; Hao, Ran; Pan, Li-Hua; Luo, Jian-Ping

    2014-06-15

    In this work, response surface methodology was used to determine optimum conditions for extraction of polysaccharides from jellyfish skin (JSP). The optimum parameters were found to be raw material to water ratio 1:7.5 (w/v), extraction temperature 100°C and extraction time 4h. Under these conditions, the JSP yield reached 1.007 mg/g. Papain (15 U/mL) in combination with Sevag reagent was beneficial in removing proteins from JSP. After precipitation with ethanol at final concentration of 40%, 60% and 80% in turn, three polysaccharide fractions of JSP1, JSP2 and JSP3 were obtained from JSP, respectively. The three fractions exhibited different physicochemical properties with respect to molecular weight distribution, monosaccharide composition, infrared absorption spectra, and glycosyl bond composition. In addition, JSP3 showed strong inhibitory effects on oxidized low-density lipoprotein (oxLDL) induced conversion of macrophages into foam cells, which possibly attributed to the down-regulation of some atherogenesis-related gene expressions.

  8. Characterization and three-dimensional reconstruction of synthetic bone model foams

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, S. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Vlad, M.D. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Faculty of Medical Bioengineering, “Gr. T. Popa” University of Medicine and Pharmacy, Str. Kogalniceanu 9-13, 700454 Iasi (Romania); López, J. [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain); Navarro, M. [Centre de Biotecnologia Animal i de Teràpia Gènica (CBATEG), Departament de Sanitat i d' Anatomia Animals, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Cerdanyola del Vallès (Spain); Fernández, E., E-mail: enrique.fernandez@upc.edu [Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Division of Biomaterials and Bioengineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, E-08028 Barcelona (Spain)

    2013-08-01

    Sawbones© open-cell foams with different porosity grades are being used as synthetic bone-like models for in vitro mechanical and infiltration experiments. However, a comprehensive characterization of these foams is not available and there is a lack of reliable information about them. For this reason two of these foams (Refs. 1522-505 and -507) have been characterized at the micro architectural level by scanning electron microscopy, computed tomography and image data analysis. BoneJ open software and ImageJ open software were used to obtain the characteristic histomorphometric parameters and the three dimensional virtual models of the foams. The results showed that both foams, while having different macro porosities, appeared undistinguishable at the micro scale. Moreover, the micro structural features resembled those of osteoporotic rather than healthy trabecular bone. It is concluded that Sawbones© foams behave reasonably as synthetic bone-like models. Consequently, their use is recommended for in vitro comparison purposes of both mechanical and infiltration testing performed in real vertebra. Finally, the virtual models obtained, which are available under request, can favour comparisons between future self-similar in vitro experiments and computer simulations. - Highlights: • Sawbones© model foams have been scanned by μ-CT. • Histomorphometric indices and 3D virtual models have been obtained. • The results will be of use to understand biocement vertebra infiltration studies.

  9. CFD analysis for the hydrogen transport in the primary contention of a BWR using the codes OpenFOAM and Gas-Flow; Analisis CFD para el transporte de hidrogeno en la contencion primaria de un reactor BWR usando los codigos OpenFOAM y GasFlow

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez P, D. A.

    2014-07-01

    using a limited number of semi-empirical data, and instead, mathematical relationships are used taking into account the various physical phenomena as well the interactions that occur among them, such as heat transfer between the fluid and the solid walls condensation of water vapor on the walls, the turbulent effects in areas of restricted passage, etc. Taking into account these advantages, this study presents a qualitative and quantitative comparison between the CFD codes OpenFOAM and Gas-Flow related to the transport phenomena of Hydrogen and other gases in the primary containment of a BWR reactor. Gas-Flow is a code of commercial license that is well validated, developed in Germany to analyze the transport of gases in nuclear reactor containments. On the other hand, OpenFOAM is an open source CFD code offering several solvers for different phenomena assessments, in this work, the reacting Foam solver is used because it has a strong similarity to the intended application of Hydrogen transport. In this thesis the results obtained using the reacting Foam solver of OpenFOAM for the calculation of transport of Hydrogen are compared with the results of the Gas-Flow code in order to assess if it is feasible to use the open source code OpenFOAM in the case of Hydrogen transport in primary containment of a BWR reactor. Some differences in the qualitative and quantitative results from both codes were found, the differences (with a maximum error rate of 4%) in the quantitative results were found are small and are considered more than acceptable for this type of analysis, moreover, these differences are mainly attributed to the transport models used, mainly because OpenFOAM uses a homogeneous mixture model and Gas-Flow a heterogeneous one. Implementing appropriate solvers in codes like OpenFOAM has the goal to develop own tools that are applicable to the transport of Hydrogen in the primary containment of a BWR reactor and thus, to gain some independence while not relying on

  10. Physical and Morphological Properties for Foams of Polystyrene/SBR Blends

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myoung Jun; Lee, Yong Bong; Noh, Si Tae [Department of Chemical Engineering, Hanyang University, Ansan (Korea); Hwang, Seok Ho; Lee, Youngchul [Chemical and Bio Technology Team, Korea Institute of Industrial Technology, Chonan (Korea)

    2001-02-01

    In this study, blends of polystyrene(PS) and Styrene-Butadiene-Rubber(SBR) were prepared by mixing in the kneader, and then the foams of blends were prepared by extruding with a foaming agent in a single screw exturder. We investigated the physical properties and morphological behaviors of blended foams by UTM, SEM and Densitmeter. The number of cells in the foamed PS/SBR blends matrix increased as the processing temperature decreased. Also, the structure of cell changed from closed cell structure to open cell structure as SBR fraction increased. In PS/SBR blends, the impact strength was improved by adding SBR, however, the flexural strength was decreased except for the 5 wt% SBR. 9 refs., 7 figs., 1 tabs.

  11. Strain-rate dependence for Ni/Al hybrid foams

    Directory of Open Access Journals (Sweden)

    Jung Anne

    2015-01-01

    Full Text Available Shock absorption often needs stiff but lightweight materials that exhibit a large kinetic energy absorption capability. Open-cell metal foams are artificial structures, which due to their plateau stress, including a strong hysteresis, can in principle absorb large amounts of energy. However, their plateau stress is too low for many applications. In this study, we use highly novel and promising Ni/Al hybrid foams which consist of standard, open-cell aluminium foams, where nanocrystalline nickel is deposited by electrodeposition as coating on the strut surface. The mechanical behaviour of cellular materials, including their behaviour under higher strain-rates, is governed by their microstructure due to the properties of the strut material, pore/strut geometry and mass distribution over the struts. Micro-inertia effects are strongly related to the microstructure. For a conclusive model, the exact real microstructure is needed. In this study a micro-focus computer tomography (μCT system has been used for the analysis of the microstructure of the foam samples and for the development of a microstructural Finite Element (micro-FE mesh. The microstructural FE models have been used to model the mechanical behaviour of the Ni/Al hybrid foams under dynamic loading conditions. The simulations are validated by quasi-static compression tests and dynamic split Hopkinson pressure bar tests.

  12. Effect of Apolipoprotein A-I on ATP Binding Cassette Transporter A1 Degradation and Cholesterol Efflux in THP-1 Macrophage-derived Foam Cells

    Institute of Scientific and Technical Information of China (English)

    Chao-Ke TANG; Chang-Geng RUAN; Yong-Zong YANG; Guo-Hua TANG; Guang-Hui IY; Zuo WANG; Lu-Shan LIU; Shuang WAN; Zhong-Hua YUAN; Xiu-Sheng HE; Jun-Hao YANG

    2004-01-01

    Cholesterol-loaded macrophage foam cells are a central componentof atherosclerotic lesions ATP binding cassette transporter A1(ABCA1),the defective molecule in Tangier disease,mediates the efflux ofphospholipid and cholesterol from cells to apolipoprotein A-I(apoA-I),reversing foam cell formation.This study investigated the effect of apoA-I on ABCA1 degradation and cholesterol efflux in THP-1 macrophagederived foam cells.After exposure of the cultured THP-1 macrophage-derived foam cells to apoA-I for different time,cholesterol efflux,ABCA1 mRNA and protein levels were determined by FJ-2107P type liquid scintillator,RT-PCR and Western blot,respectively.The mean ABCA1 fluorescence intensity on THP-1macrophage-derived foam cells was detected by flow cytometry.Results showed that apoA-I markedly increased ABCAl-mediated cholesterol efflux from THP-1 macrophage-derived foam cells.This was accompanied by an increase in the content of ABCA1.ApoA-I did not alter ABCA 1 mRNA abundance.Significantly,thiol protease inhibitors increased the level ofABCA1 protein and slowed its decay in THP-1macrophage-derived foam cells,whereas none of the proteosome-specific inhibitor lactacystin,other protease inhibitors,or the lysosomal inhibitor NH4Cl showed such effects.The apoA-I-mediated cellular cholesterol efflux was enhanced by thiol protease inhibitors.Our results suggested that thiol protease inhibitors mightprovide an alternative way to upregulate ABCA1 protein.This strategy is especially appealing since it may mimic the stabilizing effect of the natural ligands apoA-I.

  13. OffWindSolver: Wind farm design tool based on actuator line/actuator disk concept in OpenFoam architecture

    Directory of Open Access Journals (Sweden)

    Panjwani Balram

    2014-01-01

    Full Text Available Wind energy is a good alternative to meet the energy requirements in some parts of the world; however the efficiency of wind farm depends on the optimized location of the wind turbines. Therefore a software tool that is capable of predicting the in-situ performance of multiple turbine installations in different operating conditions with reliable accuracy is needed. In present study wind farm layout design tool OffWindSolver is developed within the OpenFoam architecture. Unsteady PisoFoam solver is extended to account for wind turbines, where each turbine is modeled as a sink term in the momentum equation. Turbine modeling is based on actuator line concepts derived from SOWFA code, where each blade of the turbine is represented as a line. The loading on each line/blade of the turbine is estimated using the Blade Element Method (BEM. The inputs for the solver are tabulated airfoil aerodynamic data, dimension and height of the wind turbines, wind magnitude and direction. OffWindSolver is validated for a real wind farm – Lillgrund offshore facility in Sweden/Denmark operated by Vattenfall Vindkraft AB. Because of the scale of the computation, we only examine the effect of wind from one direction at one speed. In the absence of time dependent Marine Atmospheric Boundary Layer (MABL, a log wind profile with surface roughness of 0.04 is used at the inlet. The simulated power production of each turbine is compared to the field data and large-eddy simulation. The overall power of the wind farm is well predicted. The simulation shows the significant decreases of the power for those turbines that were in the wake.

  14. Effect of minoxidil topical foam on frontotemporal and vertex androgenetic alopecia in men: a 104-week open-label clinical trial.

    Science.gov (United States)

    Kanti, V; Hillmann, K; Kottner, J; Stroux, A; Canfield, D; Blume-Peytavi, U

    2016-07-01

    Topical minoxidil formulations have been shown to be effective in treating androgenetic alopecia (AGA) for 12 months. Efficacy and safety in both frontotemporal and vertex regions over longer application periods have not been studied so far. To evaluate the effect of 5% minoxidil topical foam (5% MTF) in the frontotemporal and vertex areas in patients with moderate AGA over 104 weeks. An 80-week, open-label extension phase was performed, following a 24-week randomized, double-blind, placebo-controlled study in men with AGA grade IIIvertex to VI. Group 1 (n = 22) received ongoing 5% MTF for 104 weeks, Group 2 (n = 23) received placebo topical foam (plaTF) until week 24, followed by 5% MTF until week 104 during the extension phase. Frontotemporal and vertex target area non-vellus hair counts (f-TAHC, v-TAHC) and cumulative hair width (f-TAHW, v-TAHW) were assessed at baseline and at weeks 24, 52, 76 and 104. In Group 1, f-TAHW and f-TAHC showed a statistically significant increase from baseline to week 52 and week 76, respectively, returning to values comparable to baseline at week 104. No significant differences were found between baseline and week 104 in v-TAHC in Group 1 as well as f-TAHC, v-TAHC, f-TAHW and v-TAHW values in Group 2. 5% MTF is effective in stabilizing hair density, hair width and scalp coverage in both frontotemporal and vertex areas over an application period of 104 weeks, while showing a good safety and tolerability profile with a low rate of irritant contact dermatitis. © 2015 European Academy of Dermatology and Venereology.

  15. Foam vessel for cryogenic fluid storage

    Science.gov (United States)

    Spear, Jonathan D [San Francisco, CA

    2011-07-05

    Cryogenic storage and separator vessels made of polyolefin foams are disclosed, as are methods of storing and separating cryogenic fluids and fluid mixtures using these vessels. In one embodiment, the polyolefin foams may be cross-linked, closed-cell polyethylene foams with a density of from about 2 pounds per cubic foot to a density of about 4 pounds per cubic foot.

  16. Mesenchymal stem cells alleviate atherosclerosis by elevating number and function of CD4(+)CD25 (+)FOXP3 (+) regulatory T-cells and inhibiting macrophage foam cell formation.

    Science.gov (United States)

    Wang, Zhi Xiao; Wang, Chong Quan; Li, Xiao Yan; Feng, Gao Ke; Zhu, Hong Ling; Ding, Yan; Jiang, Xue Jun

    2015-02-01

    Atherosclerosis is a chronic inflammatory disease characterized by the formation of plaques inside arteries, leading to narrowing and blockage. Potential therapeutic strategies include expanding the population of regulatory T-cells (Tregs) to enhance atheroprotective immunity, and inhibiting the formation of macrophage foam cells. Here, we studied the effect of bone marrow-derived mesenchymal stem cells (BM-MSCs) on atherosclerotic plaque formation in Apolipoprotein E(-/-) (ApoE-KO) mice, and elucidated the underlying mechanism. BM-MSCs isolated from 4 week-old ApoE-KO mice were evaluated by flow cytometry for expression of MSC-specific markers. Thirty eight week-old ApoE-KO mice were randomly divided into three experimental groups (n = 10 per group): 1. MSC group-received BM-MSCs intravenously; 2. Vehicle group-received DMEM; 3. Control group-did not receive any treatment. Administration of MSCs resulted in a marked decrease in the size of atherosclerotic plaques 3 months after treatment. In addition, the number and function of CD4(+)CD25(+)FOXP3(+) regulatory T-cells (Tregs) in cultured splenocytes, and the expression of FOXP3 at both mRNA and protein levels, was significantly increased in the MSC group. In vitro experiments further indicated that the formation of macrophage foam cells was inhibited by treatment with MSCs, accompanied by a significant downregulation in CD36 and scavenger receptor A (SRA). Our findings suggest that MSCs play an atheroprotective role by enhancing the number and function of Tregs and inhibiting the formation of macrophage foam cells. Hence, administration of MSCs to atherosclerotic patients might have significant clinical benefits.

  17. Enhanced hydrogen production in microbial electrolysis cell with 3D self-assembly nickel foam-graphene cathode.

    Science.gov (United States)

    Cai, Weiwei; Liu, Wenzong; Han, Jinglong; Wang, Aijie

    2016-06-15

    In comparison to precious metal catalyst especially Platinum (Pt), nickel foam (NF) owned cheap cost and unique three-dimensional (3D) structure, however, it was scarcely applied as cathode material in microbial electrolysis cell (MEC) as the intrinsic laggard electrochemical activity for hydrogen recovery. In this study, a self-assembly 3D nickel foam-graphene (NF-G) cathode was fabricated by facile hydrothermal approach for hydrogen evolution in MECs. Electrochemical analysis (linear scan voltammetry and electrochemical impedance spectroscopy) revealed the improved electrochemical activity and effective mass diffusion after coating with graphene. NF-G as cathode in MEC showed a significant enhancement in hydrogen production rate compared with nickel foam at a variety of biases. Noticeably, NF-G showed a comparable averaged hydrogen production rate (1.31 ± 0.07 mL H2 mL(-1) reactor d(-1)) to Platinum/carbon (Pt/C) (1.32 ± 0.07 mL H2 mL(-1) reactor d(-1)) at 0.8 V. Profitable energy recovery could be achieved by NF-G cathode at higher applied voltage, which performed the best hydrogen yield of 3.27 ± 0.16 mol H2 mol(-1) acetate at 0.8 V and highest energy efficiency of 185.92 ± 6.48% at 0.6 V.

  18. Evaluation of an antimicrobial silver foam dressing for use with V.A.C. therapy: morphological, mechanical, and antimicrobial properties.

    Science.gov (United States)

    Payne, Joanna L; Ambrosio, Archel M

    2009-04-01

    The V.A.C. Therapy System (KCI, San Antonio, TX) is an integrated wound management system that creates an environment that promotes wound healing. V.A.C. GranuFoam Silver dressing (S-ROCF) is a reticulated, open-celled polyurethane foam having a pore size range of 400-600 microm. The foam is coated with silver to impart antimicrobial properties throughout the dressing. The morphological and key mechanical properties including tensile strength, ultimate elongation, tear strength, and compression resistance of this dressing were compared to the original V.A.C. GranuFoam dressing (ROCF), which is also a reticulated, open-celled polyurethane foam, and were found to be comparable. Furthermore, the antimicrobial property of S-ROCF was evaluated in vitro for efficacy against pathogens commonly found in clinical settings, including Staphylococcus aureus and Pseudomonas aeruginosa. S-ROCF was found to be effective during antimicrobial testing with a 99.99% reduction in colony forming units, and remained effective after 72 h of simulated V.A.C. Therapy. The antimicrobial and mechanical characteristics of the foam were unaffected by aging as demonstrated through an accelerated aging process. The V.A.C. GranuFoam Silver dressing is a specialized antimicrobial dressing for use with the V.A.C. Therapy System that exhibits morphological and mechanical properties comparable to the V.A.C. GranuFoam dressing and provides the added benefit of antimicrobial efficacy.

  19. Air-cathode preparation with activated carbon as catalyst, PTFE as binder and nickel foam as current collector for microbial fuel cells.

    Science.gov (United States)

    Cheng, Shaoan; Wu, Jiancheng

    2013-08-01

    A cathode is a critical factor that limits the practical application of microbial fuel cells (MFCs) in terms of cost and power generation. To develop a cost-effective cathode, we investigate a cathode preparation technique using nickel foam as a current collector, activated carbon as a catalyst and PTFE as a binder. The effects of the type and loading of conductive carbon, the type and loading of activated carbon, and PTFE loading on cathode performance are systematically studied by linear sweep voltammetry (LSV). The nickel foam cathode MFC produces a power density of 1190±50 mW m(-2), comparable with 1320 mW m(-2) from a typical carbon cloth Pt cathode MFC. However, the cost of a nickel foam activated carbon cathode is 1/30 of that of carbon cloth Pt cathode. The results indicate that a nickel foam cathode could be used in scaling up the MFC system.

  20. Combination of spices and herbal extract restores macrophage foam cell migration and abrogates the athero-inflammatory signalling cascade of atherogenesis.

    Science.gov (United States)

    Nimgulkar, Chetan; Ghosh, Sudip; Sankar, Anand B; Uday, Kumar P; Surekha, M V; Madhusudhanachary, P; Annapurna, B R; Raghu, P; Bharatraj, Dinesh Kumar

    2015-09-01

    The trapping of lipid-laden macrophages in the arterial intima is a critical but reversible step in atherogenesis. However, information about possible treatments for this condition is lacking. Here, we hypothesized that combining the polyphenol-rich fractions (PHC) of commonly consumed spices (Allium sativum L (Liliaceae), Zingiber officinale R (Zingiberaceae), Curcuma longa L (Zingiberaceae)) and herbs (Terminalia arjuna (R) W & A (Combretaceae) and Cyperus rotundus L (Cyperaceae)) prevents foam cell formation and atherogenesis. Using an in vitro foam cell formation assay, we found that PHC significantly inhibited lipid-laden macrophage foam cell formation compared to the depleted polyphenol fraction of PHC (F-PHC). We further observed that PHC attenuated the LDL and LPS induced CD36, p-FAK and PPAR-γ protein expression in macrophages and increased their migration. NK-κB-DNA interaction, TNF-α, ROS generation, and MMP9 and MMP2 protein expression were suppressed in PHC-treated macrophages. The anti-atherosclerotic activity of PHC was investigated in a high fat- and cholesterol-fed rabbit model. The inhibition of foam cell deposition within the aortic intima and atheroma formation confirmed the atheroprotective activity of PHC. Therefore, we conclude that the armoury of polyphenols in PHC attenuates the CD36 signalling cascade-mediated foam cell formation, enhances the migration of these cells and prevents atherogenesis.

  1. The effects of composition and sintering temperature on the silica foam fabricated by slurry method

    Science.gov (United States)

    Baharom, Syazwani; Ahmad, Sufizar; Taib, Hariati; Muda, Rizamarhaiza

    2016-07-01

    Reticulated ceramic or open pore ceramic foam is a well-known material which exhibits extremely high porosities, with a significant degree of interconnectivity that makes them desirable in a wide range of applications. There were broad types of ceramic foam fabrication method such as polymeric sponge method, direct foaming, and starch consolidation. In this study, the slurry method has been chosen to fabricate Silica (SiO2) foam. In this process, Polyurethane (PU) foam template was dipped into ceramic slurry and followed by drying and sintering to obtain foam which contains porosity in the range of 50% to 70%. The compositions of SiO2 were varied starting from 55 wt.%, 60 wt.%, 65 wt.% and 70 wt.%. The samples of SiO2 that have been dipped and dried were sintered at 900°C, 1000°C, 1100°C, and 1250°C. The sintered SiO2 ceramic foam samples were characterized to observe their morphology, and physical properties. Thus, the microstructure of the SiO2 ceramic foams samples was examined by Scanning Electron Microscopy (SEM), and Electron Dispersive Spectroscopy (EDS). Meanwhile, the physical properties of the SiO2 ceramic foam samples such as the total porosity (%) and bulk density were determined using Archimedes method. It was found that the density of ceramic foam produced was in the range of 0.25 g/cm3 up to 0.75 g/cm3, whereas the level of porosity percentage was in the range of 61.81% to 82.18% with the size of open pore or window cells were in between 141 µm up to 626 µm.

  2. The effects of composition and sintering temperature on the silica foam fabricated by slurry method

    Energy Technology Data Exchange (ETDEWEB)

    Baharom, Syazwani, E-mail: hd140001@siswa.uthm.edu.my; Ahmad, Sufizar, E-mail: sufizar@uthm.edu.my; Taib, Hariati, E-mail: hariati@uthm.edu.my; Muda, Rizamarhaiza, E-mail: hd130013@siswa.uthm.edu.my [Department of Material and Design Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), 86400 Parit Raja, Batu Pahat, Johor (Malaysia)

    2016-07-19

    Reticulated ceramic or open pore ceramic foam is a well-known material which exhibits extremely high porosities, with a significant degree of interconnectivity that makes them desirable in a wide range of applications. There were broad types of ceramic foam fabrication method such as polymeric sponge method, direct foaming, and starch consolidation. In this study, the slurry method has been chosen to fabricate Silica (SiO{sub 2}) foam. In this process, Polyurethane (PU) foam template was dipped into ceramic slurry and followed by drying and sintering to obtain foam which contains porosity in the range of 50% to 70%. The compositions of SiO{sub 2} were varied starting from 55 wt.%, 60 wt.%, 65 wt.% and 70 wt.%. The samples of SiO{sub 2} that have been dipped and dried were sintered at 900°C, 1000°C, 1100°C, and 1250°C. The sintered SiO{sub 2} ceramic foam samples were characterized to observe their morphology, and physical properties. Thus, the microstructure of the SiO{sub 2} ceramic foams samples was examined by Scanning Electron Microscopy (SEM), and Electron Dispersive Spectroscopy (EDS). Meanwhile, the physical properties of the SiO{sub 2} ceramic foam samples such as the total porosity (%) and bulk density were determined using Archimedes method. It was found that the density of ceramic foam produced was in the range of 0.25 g/cm{sup 3} up to 0.75 g/cm{sup 3}, whereas the level of porosity percentage was in the range of 61.81% to 82.18% with the size of open pore or window cells were in between 141 µm up to 626 µm.

  3. Supercritical Carbon Dioxide Assisted Processing of Silica/PMMA Nanocomposite Foams

    Science.gov (United States)

    Rende, Deniz; Schadler, Linda S.; Ozisik, Rahmi

    2012-02-01

    Polymer nanocomposite foams receive considerable attention in both scientific and industrial communities. These structures are defined as closed or open cells (pores) surrounded by bulk material and are widely observed in nature in the form of bone structure, sponge, corals and natural cork. Inspired by these materials, polymer nanocomposite foams are widely used in advanced applications, such as bone scaffolds, food packaging and transportation materials due to their lightweight and enhanced mechanical, thermal, and electrical properties compared to bulk polymer foams. The presence of the nanosized fillers facilitates heterogeneous bubble nucleation as a result, the number of bubbles increases while the average bubble size decreases. Therefore, the foam morphology can be controlled by the size, concentration, and surface chemistry of the nanofiller. In the current study, we used supercritical carbon dioxide as a foaming agent for silica/poly(methyl methacrylate), PMMA, foams. The silica nanoparticles were chemically modified by fluoroalkane chains to make them CO2-philic. The surface coverage was controlled via tethering density, and the effect of silica surface coverage and concentration on foam morphology was investigated through scanning electron microscopy and image processing. Results indicated that nanofiller concentration and filler surface chemistry (CO2-philicity) had tremendous effect on foam morphology but surface coverage did not have any effect.

  4. Study on the melting process of phase change materials in metal foams using lattice Boltzmann method

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A thermal lattice Boltzmann model is developed for the melting process of phase change material (PCM) embedded in open-cell metal foams. Natural convection in the melt PCM is considered. Under the condition of local thermal non-equilibrium between the metal matrix and PCM, two evolution equations of temperature distribution function are pre-sented through selecting an equilibrium distribution function and a nonlinear source term properly. The enthalpy-based method is employed to copy with phase change problem. Melting process in a cavity of the metal foams is simulated using the present model. The melting front locations and the temperature distributions in the metal foams filled with PCM are obtained by the lattice Boltzmann method. The effects of the porosity and pore size on the melting are also investigated and discussed. The re-sults indicate that the effects of foam porosity play important roles in the overall heat transfer. For the lower porosity foams, the melting rate is comparatively greater than the higher porosity foams, due to greater heat conduction from metal foam with high heat conductivity. The foam pore size has a limited effect on the melting rate due to two counteracting effects between conduction and convection heat transfer.

  5. Foam patterns

    Science.gov (United States)

    Chaudhry, Anil R; Dzugan, Robert; Harrington, Richard M; Neece, Faurice D; Singh, Nipendra P; Westendorf, Travis

    2013-11-26

    A method of creating a foam pattern comprises mixing a polyol component and an isocyanate component to form a liquid mixture. The method further comprises placing a temporary core having a shape corresponding to a desired internal feature in a cavity of a mold and inserting the mixture into the cavity of the mold so that the mixture surrounds a portion of the temporary core. The method optionally further comprises using supporting pins made of foam to support the core in the mold cavity, with such pins becoming integral part of the pattern material simplifying subsequent processing. The method further comprises waiting for a predetermined time sufficient for a reaction from the mixture to form a foam pattern structure corresponding to the cavity of the mold, wherein the foam pattern structure encloses a portion of the temporary core and removing the temporary core from the pattern independent of chemical leaching.

  6. Activating transcription factor 1 directs Mhem atheroprotective macrophages through coordinated iron handling and foam cell protection.

    Science.gov (United States)

    Boyle, Joseph J; Johns, Michael; Kampfer, Theresa; Nguyen, Aivi T; Game, Laurence; Schaer, Dominik J; Mason, Justin C; Haskard, Dorian O

    2012-01-06

    Intraplaque hemorrhage (IPH) drives atherosclerosis through the dual metabolic stresses of cholesterol-enriched erythrocyte membranes and pro-oxidant heme/iron. When clearing tissue hemorrhage, macrophages are typically seen storing either iron or lipid. We have recently defined hemorrhage-associated macrophages (HA-mac) as a plaque macrophage population that responds adaptively to IPH. This study aimed to define the key transcription factor(s) involved in HO-1 induction by heme. To address this question, we used microarray analysis and transfection with siRNA and plasmids. To maintain physiological relevance, we focused on human blood-derived monocytes. We found that heme stimulates monocytes through induction of activating transcription factor 1 (ATF-1). ATF-1 coinduces heme oxygenase-1 (HO-1) and Liver X receptor beta (LXR-β). Heme-induced HO-1 and LXR-β were suppressed by knockdown of ATF-1, and HO-1 and LXR-β were induced by ATF-1 transfection. ATF-1 required phosphorylation for full functional activity. Expression of LXR-β in turn led to induction of other genes central to cholesterol efflux, such as LXR-α and ABCA1. This heme-directed state was distinct from known macrophage states (M1, M2, Mox) and, following the same format, we have designated them Mhem. These results show that ATF-1 mediates HO-1 induction by heme and drives macrophage adaptation to intraplaque hemorrhage. Our definition of an ATF-1-mediated pathway for linked protection from foam cell formation and oxidant stress may have therapeutic potential.

  7. Investigation of the fluid-structure interaction of a high head Francis turbine using OpenFOAM and Code_Aster

    Science.gov (United States)

    Eichhorn, M.; Doujak, E.; Waldner, L.

    2016-11-01

    The increasing energy consumption and highly stressed power grids influence the operating conditions of turbines and pump turbines in the present situation. To provide or use energy as quick as possible, hydraulic turbines are operated more frequent and over longer periods of time in lower part load at off-design conditions. This leads to a more turbulent behavior and to higher requirements of the strength of stressed components (e.g. runner, guide or stay vanes). The modern advantages of computational capabilities regarding numerical investigations allow a precise prediction of appearing flow conditions and thereby induced strains in hydraulic machines. This paper focuses on the calculation of the unsteady pressure field of a high head Francis turbine with a specific speed of nq ≈ 24 min-1 and its impact on the structure at different operating conditions. In the first step, unsteady numerical flow simulations are performed with the open-source CFD software OpenFOAM. To obtain the appearing dynamic flow phenomena, the entire machine, consisting of the spiral casing, the stay vanes, the wicket gate, the runner and the draft tube, is taken into account. Additionally, a reduced model without the spiral casing and with a simplified inlet boundary is used. To evaluate the accuracy of the CFD simulations, operating parameters such as head and torque are compared with the results of site measurements carried out on the corresponding prototype machine. In the second part, the obtained pressure fields are used for a fluid-structure analysis with the open-source Finite Element software Code_Aster, to predict the static loads on the runner.

  8. Foam Microrheology

    Energy Technology Data Exchange (ETDEWEB)

    KRAYNIK,ANDREW M.; LOEWENBERG,MICHAEL; REINELT,DOUGLAS A.

    1999-09-01

    The microrheology of liquid foams is discussed for two different regimes: static equilibrium where the capillary number Ca is zero, and the viscous regime where viscosity and surface tension are important and Ca is finite. The Surface Evolver is used to calculate the equilibrium structure of wet Kelvin foams and dry soap froths with random structure, i.e., topological disorder. The distributions of polyhedra and faces are compared with the experimental data of Matzke. Simple shearing flow of a random foam under quasistatic conditions is also described. Viscous phenomena are explored in the context of uniform expansion of 2D and 3D foams at low Reynolds number. Boundary integral methods are used to calculate the influence of Ca on the evolution of foam microstructure, which includes bubble shape and the distribution of liquid between films, Plateau borders, and (in 3D) the nodes where Plateau borders meet. The micromechanical point of view guides the development of structure-property-processing relationships for foams.

  9. Study on Foaming Behavior of Microcellular Foam Polypropylene Composites%微发泡聚丙烯复合材料发泡行为研究

    Institute of Scientific and Technical Information of China (English)

    龚维; 何颖; 张纯; 李宏; 何力

    2012-01-01

    以PP(聚丙烯)为基体材料,分别添加发泡剂母粒、发泡剂和助剂母粒及发泡剂、助剂、成核剂母粒,在二次开模条件下注塑制备微发泡PP复合材料,分析了发泡助剂及成核剂对微发泡复合材料发泡行为的影响规律.结果表明,添加发泡助剂以后,PP体系的发泡质量得到明显改善;助剂和成核剂同时添加,微发泡PP体系的发泡质量最好,泡孔平均直径为26.79 μm,泡孔密度达到4.76×106个/cm3.%By taking PP as basic materials, foaming agent master batch,foaming agent and additives,foaming agent and additives and nucleating agent respectively was added into polypropylene. The microcellular foam PP composites was made under the condition of twice-open mold. The effect rule of additives and nucleating agent on foaming behavior was analyzed in microcellular foam composites. The results show that foaming quality of PP system is improved significantly after adding additives. There is the most ideal foaming effects in microcellular foam composites after adding promoter and nucleating agent. The cell diameter is 26.79 μm and cell density is 4. 76×106 cells/cm3.

  10. Oxidized low-density lipoprotein-induced foam cell formation is mediated by formyl peptide receptor 2.

    Science.gov (United States)

    Lee, Ha Young; Oh, Eunseo; Kim, Sang Doo; Seo, Jeong Kon; Bae, Yoe-Sik

    2014-01-17

    The increased level of LDL and its modification into oxLDL has been regarded as an important risk factor for the development of cardiovascular diseases such as atherosclerosis. Although some scavenger receptors including CD36 and RAGE have been considered as target receptors for oxLDL, involvement of other receptors should be investigated for oxLDL-induced pathological responses. In this study, we found that oxLDL-induced foam cell formation was inhibited by formyl peptide receptor 2 (FPR2) antagonist WRW(4). oxLDL also stimulated calcium signaling and chemotactic migration in FPR2-expressing RBL-2H3 cells but not in vector-expressing RBL-2H3 cells. Moreover, oxLDL stimulated TNF-α production, which was also almost completely inhibited by FPR2 antagonist. Our findings therefore suggest that oxLDL stimulates macrophages, resulting in chemotactic migration, TNF-α production, and foam cell formation via FPR2 signaling, and thus likely contributes to atherogenesis. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Dynamic Property of Aluminum Foam

    Directory of Open Access Journals (Sweden)

    S Irie

    2016-09-01

    Full Text Available Aluminum in the foam of metallic foam is in the early stage of industrialization. It has various beneficial characteristics such as being lightweight, heat resistance, and an electromagnetic radiation shield. Therefore, the use of aluminum foam is expected to reduce the weight of equipment for transportation such as the car, trains, and aircraft. The use as energy absorption material is examined. Moreover aluminum foam can absorb the shock wave, and decrease the shock of the blast. Many researchers have reported about aluminum foam, but only a little information is available for high strain rates (103 s-1 or more. Therefore, the aluminum foam at high strain rates hasn't been not characterized yet. The purpose in this research is to evaluate the behavior of the aluminum form in the high-strain rate. In this paper, the collision test on high strain rate of the aluminum foam is investigated. After experiment, the numerical analysis model will be made. In this experiment, a powder gun was used to generate the high strain rate in aluminum foam. In-situ PVDF gauges were used for measuring pressure and the length of effectiveness that acts on the aluminum foam. The aluminum foam was accelerated to about 400 m/s from deflagration of single component powder and the foam were made to collide with the PVDF gauge. The high strain rate deformation of the aluminum form was measured at two collision speeds. As for the result, pressure was observed to go up rapidly when about 70% was compressed. From this result, it is understood that complete crush of the cell is caused when the relative volume is about 70%. In the next stage, this data will be compared with the numerical analysis.

  12. Enzymatically Modified Low-Density Lipoprotein Promotes Foam Cell Formation in Smooth Muscle Cells via Macropinocytosis and Enhances Receptor-Mediated Uptake of Oxidized Low-Density Lipoprotein.

    Science.gov (United States)

    Chellan, Bijoy; Reardon, Catherine A; Getz, Godfrey S; Hofmann Bowman, Marion A

    2016-06-01

    Enzyme-modified nonoxidized low-density lipoprotein (ELDL) is present in human atherosclerotic lesions. Our objective is to understand the mechanisms of ELDL uptake and its effects on vascular smooth muscle cells (SMC). Transformation of murine aortic SMCs into foam cells in response to ELDL was analyzed. ELDL, but not acetylated or oxidized LDL, was potent in inducing SMC foam cell formation. Inhibitors of macropinocytosis (LY294002, wortmannin, amiloride) attenuated ELDL uptake. In contrast, inhibitors of receptor-mediated endocytosis (dynasore, sucrose) and inhibitor of caveolae-/lipid raft-mediated endocytosis (filipin) had no effect on ELDL uptake in SMC, suggesting that macropinocytosis is the main mechanism of ELDL uptake by SMC. Receptor for advanced glycation end products (RAGE) is not obligatory for ELDL-induced SMC foam cell formation, but primes SMC for the uptake of oxidized LDL in a RAGE-dependent manner. ELDL increased intracellular reactive oxygen species, cytosolic calcium, and expression of lectin-like oxidized LDL receptor-1 in wild-type SMC but not in RAGE(-/-) SMC. The macropinocytotic uptake of ELDL is regulated predominantly by intracellular calcium because ELDL uptake was completely inhibited by pretreatment with the calcium channel inhibitor lacidipine in wild-type and RAGE(-/-) SMC. This is in contrast to pretreatment with PI3 kinase inhibitors which completely prevented ELDL uptake in RAGE(-/-) SMC, but only partially in wild-type SMC. ELDL is highly potent in inducing foam cells in murine SMC. ELDL endocytosis is mediated by calcium-dependent macropinocytosis. Priming SMC with ELDL enhances the uptake of oxidized LDL. © 2016 American Heart Association, Inc.

  13. Stretching and folding mechanism in foams

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

    2008-10-13

    We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

  14. The finite volume method in computational fluid dynamics an advanced introduction with OpenFOAM and Matlab

    CERN Document Server

    Moukalled, F; Darwish, M

    2016-01-01

    This textbook explores both the theoretical foundation of the Finite Volume Method (FVM) and its applications in Computational Fluid Dynamics (CFD). Readers will discover a thorough explanation of the FVM numerics and algorithms used for the simulation of incompressible and compressible fluid flows, along with a detailed examination of the components needed for the development of a collocated unstructured pressure-based CFD solver. Two particular CFD codes are explored. The first is uFVM, a three-dimensional unstructured pressure-based finite volume academic CFD code, implemented within Matlab. The second is OpenFOAM®, an open source framework used in the development of a range of CFD programs for the simulation of industrial scale flow problems. With over 220 figures, numerous examples and more than one hundred exercise on FVM numerics, programming, and applications, this textbook is suitable for use in an introductory course on the FVM, in an advanced course on numerics, and as a reference for CFD programm...

  15. Metal Foaming Investigated by X-ray Radioscopy

    Directory of Open Access Journals (Sweden)

    Catalina Jiménez

    2011-12-01

    Full Text Available The use of X-ray radioscopy for in-situ studies of metal foam formation and evolution is reviewed. Selected results demonstrate the power of X-ray radioscopy as diagnostic tool for metal foaming. Qualitative analyses of foam nucleation and evolution, drainage development, issues of thermal contact, mold filling, cell wall rupture and more are given. Additionally, quantitative analyses based on series of images of foam expansion yielding coalescence rates, density distributions, etc., are performed by dedicated software. These techniques help us to understand the foaming behavior of metals and to improve both foaming methods and foam quality.

  16. On the compression of aluminium foam structures under shock

    Science.gov (United States)

    Townsend, D.; Parry, S.; Bourne, N. K.; Withers, P. J.; Wood, D. C.; Appleby-Thomas, G. J.; Hameed, A.

    2017-01-01

    Foam-based materials have an important role as both blast and impact mitigators, with their extended sub-surface structures providing multiple redundant routes for load management and distribution in the event of failure. In order to further elucidate underlying stress management mechanisms at high strain-rates, here, open cell and closed cell Aluminium were investigated via the plate-impact technique. These experiments allowed the material to be loaded under a macroscale one-dimensional state of strain. The nature of pore collapse was monitored via manganin stress gauges at the target rear surface, with resultant data related back to changes in microstructure via microstructural analysis of both un-impacted and recovered target material. Results indicated crushing of the open cell foam occurred without retarding the flyer plate and the observed shock pressures suggested the degree of compaction increased with impact velocity. The higher density closed cell foam caused significant deceleration of the flyer plate during passage through the specimen and significantly lower shock pressures were observed at the anvil compared to the open cell material.

  17. Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration

    Science.gov (United States)

    Thomson, R. C.; Yaszemski, M. J.; Powers, J. M.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

  18. Microcellular foams made from gliadin.

    Science.gov (United States)

    Quester, S; Dahesh, M; Strey, R

    2014-01-01

    We have generated closed-cell microcellular foams from gliadin, an abundantly available wheat storage protein. The extraction procedure of gliadin from wheat gluten, which involves only the natural solvents water and ethanol, respectively, is described with emphasis on the precipitation step of gliadin which results in a fine dispersion of mostly spherical, submicron gliadin particles composed of myriad of protein molecules. A dense packing of these particles was hydrated and subjected to an atmosphere of carbon dioxide or nitrogen in a high-pressure cell at 250 bar. Subsequent heating to temperatures close to but still below 100 °C followed by sudden expansion and simultaneous cooling resulted in closed-cell microcellular foam. The spherical gliadin templates along with the resulting foam have been analyzed by scanning electron microscope (SEM) pictures. The size distribution of the primary particles shows diameters peaked around 0.54 μm, and the final foam cell size peaks around 1.2 μm, at a porosity of about 80 %. These are the smallest foam cell sizes ever reported for gliadin. Interestingly, the cell walls of these microcellular foams are remarkably thin with thicknesses in the lower nanometer range, thus nourishing the hope to be able to reach gliadin nanofoam.

  19. Synthesis and in vitro biocompatibility of injectable polyurethane foam scaffolds.

    Science.gov (United States)

    Guelcher, Scott A; Patel, Vishal; Gallagher, Katie M; Connolly, Susan; Didier, Jonathan E; Doctor, John S; Hollinger, Jeffrey O

    2006-05-01

    The development of therapeutics for orthopedic clinical indications exploiting minimally invasive surgical techniques has substantial benefits, especially for treatment of fragility fractures in the distal radius of osteoporotics and vertebral compression fractures. We have designed six formulations of injectable polyurethane foams to address these clinical indications. The polyurethanes were prepared by mixing two liquid components and injecting the reactive liquid mixture into a mold where it hardens in situ. Porous polyurethane foams were synthesized from lysine methyl ester diisocyanate, a poly(epsilon-caprolactone-co-glycolide) triol, a tertiary amine catalyst, anionic and non-ionic stabilizers, and a fatty acid pore opener. The rise time of the foams varied from 8-20 min. The porosity was approximately 95% and the pores varied in size from 100-1000 microm. The polyurethane foams supported attachment of viable (>95%) MG-63 cells under dynamic seeding conditions. We anticipate compelling opportunities will be available as a consequence of the favorable biological and physical properties of the injectable polyurethane foams.

  20. Perturbed microRNA Expression by Mycobacterium tuberculosis Promotes Macrophage Polarization Leading to Pro-survival Foam Cell

    Science.gov (United States)

    Ahluwalia, Pankaj Kumar; Pandey, Rajan Kumar; Sehajpal, Prabodh Kumar; Prajapati, Vijay Kumar

    2017-01-01

    Tuberculosis (TB) is one of the prevalent causes of death worldwide, with 95% of these deaths occurring in developing countries, like India. The causative agent, Mycobacterium tuberculosis (MTb) has the tenacious ability to circumvent the host’s immune system for its own advantage. Macrophages are one of the phagocytic cells that are central to immunity against MTb. These are highly plastic cells dependent on the milieu and can showcase M1/M2 polarization. M1 macrophages are bactericidal in action, but M2 macrophages are anti-inflammatory in their immune response. This computational study is an effort to elucidate the role of miRNAs that influences the survival of MTb in the macrophage. To identify the miRNAs against critical transcription factors, we selected only conserved hits from TargetScan database. Further, validation of these miRNAs was achieved using four databases viz. DIANA-microT, miRDB, miRanda-mirSVR, and miRNAMap. All miRNAs were identified through a conserved seed sequence against the 3′-UTR of transcription factors. This bioinformatics study found that miR-27a and miR-27b has a putative binding site at 3′-UTR of IRF4, and miR-302c against IRF5. miR-155, miR-132, and miR-455-5p are predicted microRNAs against suppressor of cytokine signaling transcription factors. Several other microRNAs, which have an affinity for critical transcription factors, are also predicted in this study. This MTb-associated modulation of microRNAs to modify the expression of the target gene(s) plays a critical role in TB pathogenesis. Other than M1/M2 plasticity, MTb has the ability to convert macrophage into foam cells that are rich in lipids and cholesterol. We have highlighted few microRNAs which overlap between M2/foam cell continuums. miR-155, miR-33, miR-27a, and miR-27b plays a dual role in deciding macrophage polarity and its conversion to foam cells. This study shows a glimpse of microRNAs which can be modulated by MTb not only to prevent its elimination but

  1. Endothelial cell death and intimal foam cell accumulation in the coronary artery of infected hypercholesterolemic minipigs

    DEFF Research Database (Denmark)

    Birck, Malene Muusfeldt; Saraste, Antti; Hyttel, Poul

    2013-01-01

    Apoptosis of endothelial cells (ECs) has been suggested to play a role in atherosclerosis. We studied the synergism of hypercholesterolemia with Chlamydia pneumoniae and influenza virus infections on EC morphology and intimal changes in a minipig model. The coronary artery was excised at euthanasia...

  2. Quasi-static characterisation and impact testing of auxetic foam for sports safety applications

    Science.gov (United States)

    Duncan, Olly; Foster, Leon; Senior, Terry; Alderson, Andrew; Allen, Tom

    2016-05-01

    This study compared low strain rate material properties and impact force attenuation of auxetic foam and the conventional open-cell polyurethane counterpart. This furthers our knowledge with regards to how best to apply these highly conformable and breathable auxetic foams to protective sports equipment. Cubes of auxetic foam measuring 150 × 150 × 150 mm were fabricated using a thermo-mechanical conversion process. Quasi-static compression confirmed the converted foam to be auxetic, prior to being sliced into 20 mm thick cuboid samples for further testing. Density, Poisson’s ratio and the stress-strain curve were all found to be dependent on the position of each cuboid from within the cube. Impact tests with a hemispherical drop hammer were performed for energies up to 6 J, on foams covered with a polypropylene sheet between 1 and 2 mm thick. Auxetic samples reduced peak force by ˜10 times in comparison to the conventional foam. This work has shown further potential for auxetic foam to be applied to protective equipment, while identifying that improved fabrication methods are required.

  3. DIFFERENT PORE SIZE ALUMINA FOAMS AND STUDY OF THEIR MECHANICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    A. Hadi

    2015-03-01

    Full Text Available Recently, the open-cell ceramic foams have been extensively investigated due to special properties of these structures. They are excellent candidates for various applications such as molten metal and hot gas filtration, fabrication of metal matrix composites (MMC, heat exchangers and catalyst support. In this study to prepare high strength and high permeable foams, alumina suspensions with proper solid contents and suitable rheological behavior were used for different pore density foams. The properties of the prepared foams such as mean pore size, total porosity, mechanical strength and water permeability were characterized by using different techniques. A reduction in pore density caused an increase in total porosity from 78.5 % to 83 %. The compression strength of the samples was dependent on total porosity as well as properties of the suspension. Compression strengths of 1.77; 3.24 and 3.55 MPa were measured for 10, 17 and 27 ppi foams, respectively. Presence of high volume of permeable pores and good uniformity of the structure led to high permeable foams. The permeability measurement confirmed a rise in permeability rate with a decrease in pore density of the foams.

  4. Titanium-nickel shape memory alloy foams for bone tissue engineering.

    Science.gov (United States)

    Xiong, J Y; Li, Y C; Wang, X J; Hodgson, P D; Wen, C E

    2008-07-01

    Titanium-nickel (TiNi) shape memory alloy (SMA) foams with an open-cell porous structure were fabricated by space-holder sintering process and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The mechanical properties and shape memory properties of the TiNi foam samples were investigated using compressive test. Results indicate that the plateau stresses and elastic moduli of the foams under compression decrease with the increase of their porosities. The plateau stresses and elastic moduli are measured to be from 1.9 to 38.3 MPa and from 30 to 860 MPa for the TiNi foam samples with porosities ranged from 71% to 87%, respectively. The mechanical properties of the TiNi alloy foams can be tailored to match those of bone. The TiNi alloy foams exhibit shape memory effect (SME), and it is found that the recoverable strain due to SME decreases with the increase of foam porosity.

  5. Experimental results for oscillatory water flow in 10-ppi metal foam at low-frequencies

    Science.gov (United States)

    Bağcı, Ö.; Arbak, A.; De Paepe, M.; Dukhan, N.

    2016-09-01

    This experimental study presents results and interpretation of oscillatory water flow in open-cell metal foam. The tested foam had 10 pores per inch and a porosity of 88%. At relatively low frequencies, three flow displacements were employed in the experiment. The influence of frequency and displacement on pressure loss and friction factor is discussed. A correlation of friction factor as a function of the kinetic Reynolds number was determined. Porous media parameters, permeability and drag coefficient, were also found for the same foam via steady-state flow experiments in the Darcy and Forchheimer regimes. The friction factor of oscillating flow was found to be higher than that of steady state. The findings of this study are considered important for oscillating heat transfer in metal foam.

  6. Curcumin enhanced cholesterol efflux by upregulating ABCA1 expression through AMPK-SIRT1-LXRα signaling in THP-1 macrophage-derived foam cells.

    Science.gov (United States)

    Lin, Xiao-long; Liu, Mi-Hua; Hu, Hui-Jun; Feng, Hong-ru; Fan, Xiao-Juan; Zou, Wei-wen; Pan, Yong-quan; Hu, Xue-mei; Wang, Zuo

    2015-09-01

    Curcumin, a traditional Chinese derivative from the rhizomes of Curcuma longa, is beneficial to health by modulating lipid metabolism and suppressing atherogenesis. A key part of atherosclerosis is the failure of macrophages to restore their cellular cholesterol homeostasis and the formation of foam cells. In this study, results showed that curcumin dramatically increased the expression of ATP-binding cassette transporter 1 (ABCA1), promoted cholesterol efflux from THP-1 macrophage-derived foam cells, and reduced cellular cholesterol levels. Curcumin activated AMP-activated protein kinase (AMPK) and SIRT1, and then activated LXRα in THP-1 macrophage-derived foam cells. Inhibiting AMPK/SIRT1 activity by its specific inhibitor or by small interfering RNA could inhibit LXRα activation and abolish curcumin-induced ABCA1 expression and cholesterol efflux. Thus, curcumin enhanced cholesterol efflux by upregulating ABCA1 expression through activating AMPK-SIRT1-LXRα signaling in THP-1 macrophage-derived foam cells. This study describes a possible mechanism for understanding the antiatherogenic effects of curcumin on attenuating the progression of atherosclerosis.

  7. Follicular and percutaneous penetration pathways of topically applied minoxidil foam.

    Science.gov (United States)

    Blume-Peytavi, Ulrike; Massoudy, Lida; Patzelt, Alexa; Lademann, Jürgen; Dietz, Ekkehart; Rasulev, Utkur; Garcia Bartels, Natalie

    2010-11-01

    In the past, it was assumed that the intercellular route was the only relevant penetration pathway for topically applied substances. Recent results on follicular penetration emphasize that the hair follicles represent a highly relevant and efficient penetration pathway and reservoir for topically applied substances. This study investigates a selective closure technique of hair follicle orifices in vivo assessing interfollicular and follicular absorption rates of topical minoxidil foam in humans. In delimited skin area, single hair orifices or interfollicular skin were blocked with a microdrop of special varnish-wax-mixture in vivo. Minoxidil foam (5%) was topically applied, and transcutaneous absorption was measured by a new surface ionization mass spectrometry technique in serum. Different settings (open, closed or none of both) enabled to clearly distinguish between interfollicular and follicular penetration of the topically applied minoxidil foam. Five minutes after topical application, minoxidil was detected in blood samples when follicles remained open, whereas with closed follicles 30 min were needed. Highest levels were found first when both pathways were open, followed by open follicles and subsequently by closed follicles. These results demonstrate the high importance of the follicular penetration pathway. Hair follicles are surrounded by a dense network of blood capillaries and dendritic cells and have stem cells in their immediate vicinity, making them ideal targets for drug delivery. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Poroelastic Foams for Simple Fabrication of Complex Soft Robots.

    Science.gov (United States)

    Mac Murray, Benjamin C; An, Xintong; Robinson, Sanlin S; van Meerbeek, Ilse M; O'Brien, Kevin W; Zhao, Huichan; Shepherd, Robert F

    2015-11-01

    Open-celled, elastomeric foams allow the simple design of fully 3D pneumatic soft machines using common forming techniques. This is demonstrated through the fabrication of simple actuators and an entirely soft, functional fluid pump formed in the shape of the human heart. The device pumps at physiologically relevant frequencies and pressures and attains a flow rate higher than all previously reported soft pumps.

  9. Foam Transport in Porous Media - A Review

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z. F.; Freedman, Vicky L.; Zhong, Lirong

    2009-11-11

    Amendment solutions with or without surfactants have been used to remove contaminants from soil. However, it has drawbacks such that the amendment solution often mobilizes the plume, and its movement is controlled by gravity and preferential flow paths. Foam is an emulsion-like, two-phase system in which gas cells are dispersed in a liquid and separated by thin liquid films called lamellae. Potential advantages of using foams in sub-surface remediation include providing better control on the volume of fluids injected, uniformity of contact, and the ability to contain the migration of contaminant laden liquids. It is expected that foam can serve as a carrier of amendments for vadose zone remediation, e.g., at the Hanford Site. As part of the U.S. Department of Energy’s EM-20 program, a numerical simulation capability will be added to the Subsurface Transport Over Multiple Phases (STOMP) flow simulator. The primary purpose of this document is to review the modeling approaches of foam transport in porous media. However, as an aid to understanding the simulation approaches, some experiments under unsaturated conditions and the processes of foam transport are also reviewed. Foam may be formed when the surfactant concentration is above the critical micelle concentration. There are two main types of foams – the ball foam (microfoam) and the polyhedral foam. The characteristics of bulk foam are described by the properties such as foam quality, texture, stability, density, surface tension, disjoining pressure, etc. Foam has been used to flush contaminants such as metals, organics, and nonaqueous phase liquids from unsaturated soil. Ball foam, or colloidal gas aphrons, reportedly have been used for soil flushing in contaminated site remediation and was found to be more efficient than surfactant solutions on the basis of weight of contaminant removed per gram of surfactant. Experiments also indicate that the polyhedral foam can be used to enhance soil remediation. The

  10. Structural analysis of advanced polymeric foams by means of high resolution X-ray computed tomography

    Science.gov (United States)

    Nacucchi, M.; De Pascalis, F.; Scatto, M.; Capodieci, L.; Albertoni, R.

    2016-06-01

    Advanced polymeric foams with enhanced thermal insulation and mechanical properties are used in a wide range of industrial applications. The properties of a foam strongly depend upon its cell structure. Traditionally, their microstructure has been studied using 2D imaging systems based on optical or electron microscopy, with the obvious disadvantage that only the surface of the sample can be analysed. To overcome this shortcoming, the adoption of X-ray micro-tomography imaging is here suggested to allow for a complete 3D, non-destructive analysis of advanced polymeric foams. Unlike metallic foams, the resolution of the reconstructed structural features is hampered by the low contrast in the images due to weak X-ray absorption in the polymer. In this work an advanced methodology based on high-resolution and low-contrast techniques is used to perform quantitative analyses on both closed and open cells foams. Local structural features of individual cells such as equivalent diameter, sphericity, anisotropy and orientation are statistically evaluated. In addition, thickness and length of the struts are determined, underlining the key role played by the achieved resolution. In perspective, the quantitative description of these structural features will be used to evaluate the results of in situ mechanical and thermal test on foam samples.

  11. Application of Spray Foam Insulation Under Plywood and Oriented Strand Board Roof Sheathing

    Energy Technology Data Exchange (ETDEWEB)

    Grin, A. [Building Science Corporation, Somerville, MA (United States); Smegal, J. [Building Science Corporation, Somerville, MA (United States); Lstiburek, J. [Building Science Corporation, Somerville, MA (United States)

    2013-10-01

    Unvented roof strategies with open cell and closed cell spray polyurethane foam insulation sprayed to the underside of roof sheathing have been used since the mid-1990's to provide durable and efficient building enclosures. However, there have been isolated moisture related incidents reported anecdotally that raise potential concerns about the overall hygrothermal performance of these systems. This project involved hygrothermal modeling of a range of rainwater leakage and field evaluations of in-service residential roofs using spray foam insulation. All of the roof assemblies modeled exhibited drying capacity to handle minor rainwater leakage. All field evaluation locations of in-service residential roofs had moisture contents well within the safe range for wood-based sheathing. Explorations of eleven in-service roof systems were completed. The exploration involved taking a sample of spray foam from the underside of the roof sheathing, exposing the sheathing, then taking a moisture content reading. All locations had moisture contents well within the safe range for wood-based sheathing. One full-roof failure was reviewed, as an industry partner was involved with replacing structurally failed roof sheathing. In this case the manufacturer's investigation report concluded that the spray foam was installed on wet OSB based on the observation that the spray foam did not adhere well to the substrate and the pore structure of the closed cell spray foam at the ccSPF/OSB interface was indicative of a wet substrate.

  12. Enhancement of human ACAT1 gene expression to promote the macrophage-derived foam cell formation by dexamethasone

    Institute of Scientific and Technical Information of China (English)

    Li YANG; Ta Yuan CHANG; Bo Liang LI; Jin Bo YANG; Jia CHEN; Guang Yao YU; Pei ZHOU; Lei LEI; Zhen Zhen WANG; Catherine CY CHANG; XinYing YANG

    2004-01-01

    In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions. In this study,with the treatment of a glucocorticoid hormone dexamethasone (Dex), lipid staining results clearly showed the large accumulation of lipid droplets containing cholesteryl esters in THP- 1-derived macrophages exposed to lower concentration of the oxidized low-density lipoprotein (ox-LDL). More notably, when treated together with specific anti-ACAT inhibitors, the abundant cholesteryl ester accumulation was markedly diminished in THP-l-derived macrophages, confirming that ACAT is the key enzyme responsible for intracellular cholesteryl ester synthesis. RT-PCR and Western blot results indicated that Dex caused up-regulation of human ACAT1 expression at both the mRNA and protein levels in THP-1 and THP- 1-derived macrophages. The luciferase activity assay demonstrated that Dex could enhance the activity of human ACAT1 gene P1 promoter, a major factor leading to the ACAT1 activation, in a cell-specific manner.Further experimental evidences showed that a glucocorticoid response element (GRE) located within human ACAT1gene P1 promoter to response to the elevation of human ACAT1 gene expression by Dex could be functionally bound with glucocorticoid receptor (GR) proteins. These data supported the hypothesis that the clinical treatment with Dex,which increased the incidence of atherosclerosis, may in part due to enhancing the ACAT1 expression to promote the accumulation of cholesteryl esters during the macrophage-derived foam cell formation, an early stage of atherosclerosis.

  13. Advanced glycation end products (AGEs) increase human mesangial foam cell formation by increasing Golgi SCAP glycosylation in vitro.

    Science.gov (United States)

    Yuan, Yang; Zhao, Lei; Chen, Yaxi; Moorhead, John F; Varghese, Zac; Powis, Stephen H; Minogue, Shane; Sun, Zilin; Ruan, Xiong Z

    2011-07-01

    Advanced glycation end products (AGEs) is one of the causative factors of diabetic nephropathy, which is associated with lipid accumulation in glomeruli. This study was designed to investigate whether N(ε)-(carboxymethyl) lysine (CML; a member of the AGEs family) increases lipid accumulation by impairing the function of sterol-regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) in human mesangial cells (HMCs). Intracellular cholesterol content was assessed by Oil Red O staining and quantitative assay. The expression of molecules controlling cholesterol homeostasis was examined using real-time quantitative RT-PCR and Western blotting. The activity of Golgi-processing enzymes was determined using enzyme-based methods, and the translocation of SCAP from the endoplasmic reticulum (ER) to the Golgi was detected by confocal microscopy. CML increased cholesterol accumulation in HMCs. Exposure to CML increased expression and abnormal translocation of SCAP from the ER to the Golgi even in the presence of a high concentration of LDL. The increased SCAP translocation carried more SREBP-2 to the Golgi for activation by proteolytic cleavages, enhancing transcription of 3-hydroxy-3-methylclutaryl-CoA reductase and the LDL receptor. CML increased Golgi mannosidase activity, which may enhance glycosylation of SCAP. This prolonged the half-life and enhanced recycling of SCAP between the ER and the Golgi. The effects of CML were blocked by inhibitors of Golgi mannosidases. AGEs (CML) increased lipid synthesis and uptake, thereby causing foam cell formation via increasing transcription and protein glycosylation of SCAP in HMCs. These data imply that inhibitors of Golgi-processing enzymes might have a potential renoprotective role in prevention of mesangial foam cell formation.

  14. Chlamydia pneumoniae-induced foam cell formation requires MyD88-dependent and -independent signaling and is reciprocally modulated by liver X receptor activation.

    Science.gov (United States)

    Chen, Shuang; Sorrentino, Rosalinda; Shimada, Kenichi; Bulut, Yonca; Doherty, Terence M; Crother, Timothy R; Arditi, Moshe

    2008-11-15

    Chlamydia pneumoniae is detected by macrophages and other APCs via TLRs and can exacerbate developing atherosclerotic lesions, but how that occurs is not known. Liver X receptors (LXRs) centrally control reverse cholesterol transport, but also negatively modulate TLR-mediated inflammatory pathways. We isolated peritoneal macrophages from wild-type, TLR2, TLR3, TLR4, TLR2/4, MyD88, TRIF, MyD88/TRIF, and IFN regulatory factor 3 (IRF3) KO mice, treated them with live or UV-killed C. pneumoniae in the presence or absence of oxidized LDL, then measured foam cell formation. In some experiments, the synthetic LXR agonist GW3965 was added to macrophages infected with C. pneumoniae in the presence of oxidized LDL. Both live and UV-killed C. pneumoniae induced IRF3 activation and promoted foam cell formation in wild-type macrophages, whereas the genetic absence of TLR2, TLR4, MyD88, TRIF, or IRF3, but not TLR3, significantly reduced foam cell formation. C. pneumoniae-induced foam cell formation was significantly reduced by the LXR agonist GW3965, which in turn inhibited C. pneumoniae-induced IRF3 activation, suggesting a bidirectional cross-talk. We conclude that C. pneumoniae facilitates foam cell formation via activation of both MyD88-dependent and MyD88-independent (i.e., TRIF-dependent and IRF3-dependent) pathways downstream of TLR2 and TLR4 signaling and that TLR3 is not involved in this process. This mechanism could at least partly explain why infection with C. pneumoniae accelerates the development of atherosclerotic plaque and lends support to the proposal that LXR agonists might prove clinically useful in suppressing atherogenesis.

  15. Fracture of metal foams : In-situ testing and numerical modeling

    NARCIS (Netherlands)

    Onck, PR; van Merkerk, R.; De Hosson, JTM; Schmidt, I.

    2004-01-01

    This paper is on a combined experimental/modeling study on the tensile fracture of open-cell foams. In-situ tensile tests show that individual struts can fail in a brittle or ductile mode, presumably depending on the presence of casting defects. In-situ single strut tests were performed, enabling ob

  16. Polymer foam comprising a polymer and nanoparticles, and nanoparticles for the manufacture of such foam.

    NARCIS (Netherlands)

    Vancso, Gyula J.; Duvigneau, Joost; Nederkoorn, P.H.J.; Wassing, T.

    2014-01-01

    A polymer foam is produced comprising a polymer and nanoparticles having a maximum dimensionof 750 nm, which foam has cells with an average cell size of at most 1 µm and a cell density of at least 1012 cells/ml, wherein polymeric grafts have been attached to the nanoparticles. The nanoparticles may

  17. Polymer foam comprising a polymer and nanoparticles, and nanoparticles for the manufacture of such foam.

    NARCIS (Netherlands)

    Vancso, G.J.; Duvigneau, J.; Nederkoorn, P.H.J.; Wassing, T.

    2014-01-01

    A polymer foam is produced comprising a polymer and nanoparticles having a maximum dimensionof 750 nm, which foam has cells with an average cell size of at most 1 µm and a cell density of at least 1012 cells/ml, wherein polymeric grafts have been attached to the nanoparticles. The nanoparticles may

  18. 闭孔泡沫铝声屏障设计%Design of Closed-Cell Aluminum Foam Sound Barriers

    Institute of Scientific and Technical Information of China (English)

    梁李斯; 姚广春; 穆永亮; 华中胜

    2011-01-01

    为改变高速路两侧噪声污染严重,为设计性能更加优越的公路声屏障,结合沈阳市东西快速干道高架桥声屏障建设的工程要求,设计闭孔泡沫铝材的吸声共振型声屏障.使用噪声频谱分析仪实地测量噪声污染情况,利用驻波管法测试打孔闭孔泡沫铝板的吸声系数值.设计的声屏障主要吸声结构为密度0.3 g/cm3,厚度10 mm,打孔率3%的闭孔泡沫铝吸声板,背后设置30 mm厚空腔,其吸声特性为:吸声主频率为300~400 Hz,对500 Hz以下的低频噪声吸声率可达到60 %~90 %.%To reduce noise pollution of expressway and design better-performance sound barriers, an acoustic resonance type sound barrier is designed using closed-cell aluminum foam.The noise spectrum analyzer is used to measure the noise pollution.The sound absorption coefficient is measured using stationary-wave method.The closed-cell aluminum foam panel with 0.3g/cm3 mass density, 10mm thickness and 3% perforation rate are used for the noise barrier.A 30mm thick cavity is designed on its back.The results of measurement show that the main sound absorption frequency range is from 300 to 400Hz, the sound absorption coefficient can reach 60%-90% for the noise frequencies lower than 500Hz.

  19. Influence of Rubber Powders on Foaming Behavior and Mechanical Properties of Foamed Polypropylene Composites

    Directory of Open Access Journals (Sweden)

    HE Yue

    2017-02-01

    Full Text Available Polypropylene/rubber powders composites with different kinds of rubber powders were foamed by injection molding machine equipped with volume-adjustable cavity. The effect of dispersity of rubber powders and crystallization behavior of composites on the foaming behavior and mechanical properties was investigated. The results show that the addition of rubber powders can improve the cell structure of foamed PP with fine and uniform cell distribution. And cell density and size of PP/PP-MAH/NBR foams are 7.64×106cell/cm3 and 29.78μm respectively, which are the best among these foams. Combining cell structures with mechanical properties, notch impact strength of PP/PP-MAH/CNBR composites increases approximately by 2.2 times while tensile strength is reduced just by 26% compared with those of the pure PP. This indicates that PP/PP-MAH/CNBR composites are ideal foamed materials.

  20. The flow of a foam in a two-dimensional porous medium

    Science.gov (United States)

    Géraud, Baudouin; Jones, Siân. A.; Cantat, Isabelle; Dollet, Benjamin; Méheust, Yves

    2016-02-01

    Foams have been used for decades as displacing fluids for enhanced oil recovery and aquifer remediation, and more recently, for remediation of the vadose zone, in which case foams carry chemical amendments. Foams are better injection fluids than aqueous solutions due to their low sensitivity to gravity and because they are less sensitive to permeability heterogeneities, thus allowing a more uniform sweep. The latter aspect results from their peculiar rheology, whose understanding motivates the present study. We investigate foam flow through a two-dimensional porous medium consisting of circular obstacles positioned randomly in a horizontal transparent Hele-Shaw cell. The local foam structure is recorded in situ, which provides a measure of the spatial distribution of bubble velocities and sizes at regular time intervals. The flow exhibits a rich phenomenology including preferential flow paths and local flow nonstationarity (intermittency) despite the imposed permanent global flow rate. Moreover, the medium selects the bubble size distribution through lamella division-triggered bubble fragmentation. Varying the mean bubble size of the injected foam, its water content, and mean velocity, we characterize those processes systematically. In particular, we measure the spatial evolution of the distribution of bubble areas, and infer the efficiency of bubble fragmentation depending on the various control parameters. We furthermore show that the distributions of bubble sizes and velocities are correlated. This study sheds new light on the local rheology of foams in porous media and opens the way toward quantitative characterization of the relationship between medium geometry and foam flow properties. It also suggests that large-scale models of foam flows in the subsurface should account for the correlation between bubble sizes and velocities.

  1. An open, parallel, randomized, comparative, multicenter study to evaluate the cost-effectiveness, performance, tolerance, and safety of a silver-containing soft silicone foam dressing (intervention) vs silver sulfadiazine cream.

    Science.gov (United States)

    Silverstein, Paul; Heimbach, David; Meites, Herbert; Latenser, Barbara; Mozingo, David; Mullins, Fred; Garner, Warren; Turkowski, Joseph; Shupp, Jeffrey; Glat, Paul; Purdue, Gary

    2011-01-01

    An open, parallel, randomized, comparative, multicenter study was implemented to evaluate the cost-effectiveness, performance, tolerance, and safety of a silver-containing soft silicone foam dressing (Mepilex Ag) vs silver sulfadiazine cream (control) in the treatment of partial-thickness thermal burns. Individuals aged 5 years and older with partial-thickness thermal burns (2.5-20% BSA) were randomized into two groups and treated with the trial products for 21 days or until healed, whichever occurred first. Data were obtained and analyzed on cost (direct and indirect), healing rates, pain, comfort, ease of product use, and adverse events. A total of 101 subjects were recruited. There were no significant differences in burn area profiles within the groups. The cost of dressing-related analgesia was lower in the intervention group (P = .03) as was the cost of background analgesia (P = .07). The mean total cost of treatment was $309 vs $513 in the control (P < .001). The average cost-effectiveness per treatment regime was $381 lower in the intervention product, producing an incremental cost-effectiveness ratio of $1688 in favor of the soft silicone foam dressing. Mean healing rates were 71.7 vs 60.8% at final visit, and the number of dressing changes were 2.2 vs 12.4 in the treatment and control groups, respectively. Subjects reported significantly less pain at application (P = .02) and during wear (P = .048) of the Mepilex Ag dressing in the acute stages of wound healing. Clinicians reported the intervention dressing was significantly easier to use (P = .03) and flexible (P = .04). Both treatments were well tolerated; however, the total incidence of adverse events was higher in the control group. The silver-containing soft silicone foam dressing was as effective in the treatment of patients as the standard care (silver sulfadiazine). In addition, the group of patients treated with the soft silicone foam dressing demonstrated decreased pain and lower costs associated

  2. B-Plant canyon fire foam supply

    Energy Technology Data Exchange (ETDEWEB)

    Gainey, T.

    1995-01-01

    A new raw water supply was installed for the B-Plant fire foam system. This document details tests to be performed which will demonstrate that the system can function as designed. The tests include: Verification of the operation of the automatic valves at the cells; Measurement of water flow and pressure downstream of the proportioner; Production of foam, and measurement of foam concentration. Included as an appendix is a copy of the work package resolution (J4 & J4a).

  3. Human hepatoma cell lines on gas foaming templated alginate scaffolds for in vitro drug-drug interaction and metabolism studies.

    Science.gov (United States)

    Stampella, A; Rizzitelli, G; Donati, F; Mazzarino, M; de la Torre, X; Botrè, F; Giardi, M F; Dentini, M; Barbetta, A; Massimi, M

    2015-12-25

    Liver in vitro systems that allow reliable prediction of major human in vivo metabolic pathways have a significant impact in drug screening and drug metabolism research. In the present study, a novel porous scaffold composed of alginate was prepared by employing a gas-in-liquid foaming approach. Galactose residues were introduced on scaffold surfaces to promote cell adhesion and to enhance liver specific functions of the entrapped HepG2/C3A cells. Hepatoma cells in the gal-alginate scaffold showed higher levels of liver specific products (albumin and urea) and were more responsive to specific inducers (e.g. dexamethasone) and inhibitors (e.g. ketoconazole) of the CYP3A4 system than in conventional monolayer culture. HepG2/C3A cells were also more efficient in terms of rapid elimination of testosterone, used as a model substance, at rates comparable to those of in vivo excretion. In addition, an improvement in metabolism of testosterone, in terms of phase II metabolite formation, was also observed when the more differentiated HepaRG cells were used. Together the data suggest that hepatocyte/gas templated alginate-systems provide an innovative high throughput platform for in vitro drug metabolism and drug-drug interaction studies, with broad fields of application, and might provide a valid tool for minimizing animal use in preclinical testing of human relevance.

  4. Pharmacokinetic analysis of the uptake of liposomes by macrophages and foam cells in vitro and their distribution to atherosclerotic lesions in mice.

    Science.gov (United States)

    Chono, Sumio; Tauchi, Yoshihiko; Morimoto, Kazuhiro

    2006-02-01

    In order to evaluate the efficacy of liposomes as a drug carrier for atherosclerotic therapy, a pharmacokinetic analysis of the uptake of liposomes by macrophages and foam cells in vitro and their distribution to atherosclerotic lesions in mice was carried out. In brief, liposomes of three particle sizes (500, 200 and 70 nm) were prepared, and the uptake of liposomes by these cells in vitro and the aortic distribution following intravenous administration to atherogenic mice were examined. The internalization rate constant calculated by measuring uptake and binding was size-dependent in both types of cells in vitro. The aortic clearance (CL(a)) was size-independent in atherogenic mice and the CL(a) of 200 nm particles was the highest. Surprisingly, the aortic distribution in vivo did not correspond with the internalization to macrophages and foam cells in vitro. These results suggest that there is an optimal size for the distribution of liposomes to atherosclerotic lesions.

  5. Optimized Synthesis of Foam Glass from Recycled CRT Panel Glass

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    Most of the panel glass from cathode ray tubes (CRTs) is landfilled today. Instead of landfilling, the panel glass can be turned into new environment-friendly foam glass. Low density foam glass is an effective heat insulating material and can be produced just by using recycle glass and foaming...... additives. In this work we recycle the CRT panel glass to synthesize the foam glass as a crucial component of building and insulating materials. The synthesis conditions such as foaming temperature, duration, glass particle size, type and concentrations of foaming agents, and so on are optimized...... by performing systematic experiments. In particular, the concentration of foaming agents is an important parameter that influences the size of bubbles and the distribution of bubbles throughout the sample. The foam glasses are characterised regarding density and open/closed porosity. Differential scanning...

  6. Drag Coefficient and Foam in Hurricane Conditions.

    Science.gov (United States)

    Golbraikh, E.; Shtemler, Y.

    2016-12-01

    he present study is motivated by recent findings of saturation and even decrease in the drag coefficient (capping) in hurricane conditions, which is accompanied by the production of a foam layer on the ocean surface. As it is difficult to expect at present a comprehensive numerical modeling of the drag coefficient saturation that is followed by wave breaking and foam production, there is no complete confidence and understanding of the saturation phenomenon. Our semi-empirical model is proposed for the estimation of the foam impact on the variation of the effective drag coefficient, Cd , with the reference wind speed U10 in stormy and hurricane conditions. The proposed model treats the efficient air-sea aerodynamic roughness length as a sum of two weighted aerodynamic roughness lengths for the foam-free and foam-covered conditions. On the available optical and radiometric measurements of the fractional foam coverage,αf, combined with direct wind speed measurements in hurricane conditions, which provide the minimum of the effective drag coefficient, Cd for the sea covered with foam. The present model yields Cd10 versus U10 in fair agreement with that evaluated from both open-ocean and laboratory measurements of the vertical variation of mean wind speed in the range of U10 from low to hurricane speeds. The present approach opens opportunities for drag coefficient modeling in hurricane conditions and hurricane intensity estimation by the foam-coverage value using optical and radiometric measurements.

  7. Experimental And Analytical Study Of Heat Transfer And Fluid Flow Through Aluminum Foams

    Science.gov (United States)

    Mancin, Simone; Zilio, Claudio; Rossetto, Luisa; Cavallini, Alberto

    2010-05-01

    This paper aims at investigating the air heat transfer and fluid flow through eight Aluminum open cell foam samples with different number of pores per linear inch (PPI ranging between 5 and 40), almost constant porosity (around 0.92-0.93) and different foam core heights (20 and 40 mm). The experimental heat transfer coefficient and pressure drop measurements have been collected in a test rig built at Dipartimento di Fisica Tecnica of the University of Padova. Three different heat fluxes have been imposed: 25.0, 32.5 and 40.0 kW m-2 and the air mass flow rate has been varied between 0.005 and 0.025 kg s-1, with air approach velocity between 2 and 5 m s-1. The effect of the foam height on the heat transfer has been experimentally analysed. Finally, the pressure drop measurements have been compared against an analytical model suggested in the open literature.

  8. Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites.

    Science.gov (United States)

    Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong

    2015-10-05

    Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption.

  9. Effect of crystals and fibrous network polymer additives on cellular morphology of microcellular foams

    Science.gov (United States)

    Miyamoto, Ryoma; Utano, Tatsumi; Yasuhara, Shunya; Ishihara, Shota; Ohshima, Masahiro

    2015-05-01

    In this study, the core-back foam injection molding was used for preparing microcelluar polypropylene (PP) foam with either a 1,3:2,4 bis-O-(4-methylbenzylidene)-D-sorbitol gelling agent (Gel-all MD) or a fibros network polymer additive (Metablen 3000). Both agent and addiive could effectively control the celluar morphology in foams but somehow different ways. In course of cooling the polymer with Gel-all MD in the mold caity, the agent enhanced the crystal nucleation and resulted in the large number of small crystals. The crystals acted as effective bubble nucleation agent in foaming process. Thus, the agent reduced the cell size and increased the cell density, drastically. Furthermore, the small crystals provided an inhomogenuity to the expanding cell wall and produced the high open cell content with nano-scale fibril structure. Gell-all as well as Metablene 3000 formed a gel-like fibrous network in melt. The network increased the elongational viscosity and tended to prevent the cell wall from breaking up. The foaming temperature window was widened by the presence of the network. Especially, the temperature window where the macro-fibrous structure was formed was expanded to the higher temperature. The effects of crystal nucleating agent and PTFE on crystals' size and number, viscoelsticity, rheological propreties of PP and cellular morphology were compared and thorougly investigated.

  10. Thermal Characterization of porous graphitic foam ? convection in impinging flow

    Energy Technology Data Exchange (ETDEWEB)

    Sultan, K [University of Western Ontario, The; DeGroot, CT [University of Western Ontario, The; Straatman, Anthony G [ORNL; Gallego, Nidia C [ORNL; Hangan, H [University of Western Ontario, The

    2009-01-01

    An experimental study has been undertaken to explore the convective heat transfer enhancement that can be achieved in an impinging airflow arrangement by bonding layers of graphitic foam to a heated metal substrate. The effects of foam protrusion, foam thickness and foam properties were explored in this study. The results show that surfaces with a layer of foam protruding upward with open edges had the highest convective enhancement over that of the bare substrate under the same conditions. For the protruding cases, convective enhancements of 30-70% were observed for airflows ranging from 7-11 m/s, for foam thicknesses in the range 2-10 mm. The highest enhancements were observed for foam specimens with the most open, interconnected void structure.

  11. In Vivo Evaluation of Hydroxyapatite Foams

    Directory of Open Access Journals (Sweden)

    Sepulveda P.

    2002-01-01

    Full Text Available Porous hydroxyapatite manufactured by foaming of aqueous ceramic suspensions and setting via gelcasting of organic monomers was tested for in vivo biocompatibility in rabbit tibia for a period of 8 weeks. The foams provide tortous frameworks and large interconnected pores that support cell attachment and organisation into 3D arrays to form new tissue. The HA foam implants were progressively filled with mature new bone tissue and osteoid after the implanted period, confirming the high osteoconductive potential and high biocompatibility of HA and the suitability of foam network in providing good osteointegration. No immune or inflammatory reactions were detected.

  12. Interplay between cellular activity and three-dimensional scaffold-cell constructs with different foam structure processed by electron beam melting.

    Science.gov (United States)

    Nune, Krishna C; Misra, R Devesh K; Gaytan, Sara M; Murr, Lawrence E

    2015-05-01

    The cellular activity, biological response, and consequent integration of scaffold-cell construct in the physiological system are governed by the ability of cells to adhere, proliferate, and biomineralize. In this regard, we combine cellular biology and materials science and engineering to fundamentally elucidate the interplay between cellular activity and interconnected three-dimensional foamed architecture obtained by a novel process of electron beam melting and computational tools. Furthermore, the organization of key proteins, notably, actin, vinclulin, and fibronectin, involved in cellular activity and biological functions and relationship with the structure was explored. The interconnected foamed structure with ligaments was favorable to cellular activity that includes cell attachment, proliferation, and differentiation. The primary rationale for favorable modulation of cellular functions is that the foamed structure provided a channel for migration and communication between cells leading to highly mineralized extracellular matrix (ECM) by the differentiating osteoblasts. The filopodial interaction amongst cells on the ligaments was a governing factor in the secretion of ECM, with consequent influence on maturation and mineralization. © 2014 Wiley Periodicals, Inc.

  13. A Numerical Analysis on a Compact Heat Exchanger in Aluminum Foam

    Science.gov (United States)

    Buonomo, B.; Ercole, D.; Manca, O.; Nardini, S.

    2016-09-01

    A numerical investigation on a compact heat exchanger in aluminum foam is carried out. The governing equations in two-dimensional steady state regime are written in local thermal non-equilibrium (LTNE). The geometrical domain under investigation is made up of a plate in aluminum foam with inside a single array of five circular tubes. The presence of the open-celled metal foam is modeled as a porous media by means of the Darcy-Forchheimer law. The foam has a porosity of 0.93 with 20 pores per inch and the LTNE assumption is used to simulate the heat transfer between metal foam and air. The compact heat exchanger at different air flow rates is studied with an assigned surface tube temperature. The results in terms of local heat transfer coefficient and Nusselt number on the external surface of the tubes are given. Moreover, local air temperature and velocity profiles in the smaller cross section, between two consecutive tubes, as a function of Reynolds number are showed. The performance evaluation criteria (PEC) is assessed in order to evaluate the effectiveness of the metal foam.

  14. Hyperbolic kaleidoscopes and Chaos in foams and Hele-Shaw cell

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, A P B; Tufaile, A [Escola de Artes, Ciencias e Humanidades da Universidade de Sao Paulo, R. Arlindo Bettio, 1000, 03828-000, Sao Paulo (Brazil); Liger-Belair, G, E-mail: atufaile@usp.br [Laboratoire d' OEnologie et Chimie Appliquee, UPRES EA 2069, URVVC, Faculte de Sciences de Reims, Moulin de la Housse, B. P. 1039, 51687 Reims, Cedex 2 (France)

    2011-03-01

    Liquid foams have fascinating optical properties, which are caused by the large number of light refractions and reflections by liquid films and Plateau borders. Due to refraction and reflection at the interfaces, the direction of the rays leaving a Plateau border can vary greatly for the same incident angle and a small positional offset. A close look in some configurations of the Plateau borders or liquid bridges reveals the existence of some triangular patterns surrounded by a complex structure, and these patterns bear a resemblance to those observed in some systems involving chaotic scattering and multiple light reflections between spheres. Provided the optical properties of the sphere surfaces are chosen appropriately, fractals are natural consequences of multiple scattering of light rays in these cavities. The cavity acts as a hyperbolic kaleidoscope multiplying the scattering of light rays generating patterns related to Poincare disks and Sierpinski gaskets in comparison to linear kaleidoscopes. We present some experimental results and simulations of these patterns explained by the light of the chaotic scattering.

  15. Microstructural characterization of in situ MXCT images of high density foams under large strains

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Brian M [Los Alamos National Laboratory; Gleiman, Seth [Los Alamos National Laboratory; Marks, Trevor G [UCSB; Milstein, Fredrick [UCSB

    2009-01-01

    Foams are used in numerous applications, such as vibration damping and energy mitigation (e.g., packaging and helmets), wherein their mechanical properties are of critical importance. A typical compressive response of a high density elastomeric foam, shown in Fig 1, generally contains three regions of interest: (I) a linear-elastic region, governed by strut bending; (II) a relatively flat, or slowly increasing stress-strain response, accompanied by strut buckling and the localized collapse of pores; and (III) an exponentially increasing stress-strain curve wherein the collapse of the pore matrix leads to densification. Two material properties of interest, upon which considerable research has focused are the foam's Young's modulus, E{sub f}, defined as the slope of the stress-strain response in region I, and the collapse stress, {sigma}{sub f}, defined as the stress at which the response begins to deviate from linearity. It has been observed [1, 2, 3] that Young's modulus and the collapse stress are dependent on the material properties of the strut material and the non-dimensional relative-density of the foam, {rho}* = {rho}{sub f}/{rho}{sub m}, where {rho}{sub r} is the gross density of the foam and {rho}{sub m} is the density of the strut, or matrix, material. For foam of low relative-density, i.e, {rho}* < 0.1, the collapse stress and Young's modulus obey the relations {sigma}{sub c}/E{sub m} {proportional_to} ({rho}*){sup m} and E{sub f}/E{sub m} {proportional_to} ({rho}*){sup n} where E{sub m} is Young's modulus of the strut material and the bounds on the parameters m and n are 0.05 {le} m {le} 0.2 and 1 {le} n {le} 4 [4]. For open-celled foams, n = 2, whereas for closed-celled foams, n = 3. Theoretically, n = 1 for foams with an ''ideal strut'' configuration [6]. Foams of high relative-density ({rho}* > 0.1) require correcting terms to account for the axial contributions of the ''thick'' struts

  16. Thermal Expansion of Polyurethane Foam

    Science.gov (United States)

    Lerch, Bradley A.; Sullivan, Roy M.

    2006-01-01

    Closed cell foams are often used for thermal insulation. In the case of the Space Shuttle, the External Tank uses several thermal protection systems to maintain the temperature of the cryogenic fuels. A few of these systems are polyurethane, closed cell foams. In an attempt to better understand the foam behavior on the tank, we are in the process of developing and improving thermal-mechanical models for the foams. These models will start at the microstructural level and progress to the overall structural behavior of the foams on the tank. One of the key properties for model characterization and verification is thermal expansion. Since the foam is not a material, but a structure, the modeling of the expansion is complex. It is also exacerbated by the anisoptropy of the material. During the spraying and foaming process, the cells become elongated in the rise direction and this imparts different properties in the rise direction than in the transverse directions. Our approach is to treat the foam as a two part structure consisting of the polymeric cell structure and the gas inside the cells. The polymeric skeleton has a thermal expansion of its own which is derived from the basic polymer chemistry. However, a major contributor to the thermal expansion is the volume change associated with the gas inside of the closed cells. As this gas expands it exerts pressure on the cell walls and changes the shape and size of the cells. The amount that this occurs depends on the elastic and viscoplastic properties of the polymer skeleton. The more compliant the polymeric skeleton, the more influence the gas pressure has on the expansion. An additional influence on the expansion process is that the polymeric skeleton begins to breakdown at elevated temperatures and releases additional gas species into the cell interiors, adding to the gas pressure. The fact that this is such a complex process makes thermal expansion ideal for testing the models. This report focuses on the thermal

  17. Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

    Science.gov (United States)

    Rapp, F.; Schneider, A.; Elsner, P.

    2014-05-01

    Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO2 balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength).

  18. Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, F., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de; Schneider, A., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de [Fraunhofer Institute for Chemical Technology ICT (Germany); Elsner, P., E-mail: peter.elsner@ict.fraunhofer.de [Fraunhofer Institute for Chemical Technology ICT, Germany and Karlsruhe Institute of Technology KIT (Germany)

    2014-05-15

    Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO{sub 2} balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength)

  19. The excreted polysaccharide of Pleurotus eryngii inhibits the foam-cell formation via down-regulation of CD36.

    Science.gov (United States)

    Chen, Jingjing; Yong, Yangyang; Xia, Xian; Wang, Zeliang; Liang, Youxing; Zhang, Shizhu; Lu, Ling

    2014-11-04

    Previous study has verified the polysaccharide from the fruiting body of Pleurotus eryngii (PEPE) is capable of decreasing the lipid content in both of cell-line and mouse model. However, little is known about underlying mechanisms and whether this bioactive polysaccharide exists in submerged culture. Here, we verified the excreted polysaccharides EP and EP-1 from submersion culture of P. eryngii have the remarkable inhibitory effects on lipid accumulation in macrophage-derived foam cells. Structure analysis indicates EP-1 consists of D-types of glucose, galactose and mannose with the main β(1 → 3)-glucan glycosidic linkage branched at O-6 by α-D-glucose while EP digested by β-1,3-glucanase fails to decrease the lipid accumulation, suggesting that the special structure is essential for its function. Expression analysis suggests that EP is able to cause the down-regulation of the scavenger receptor-CD36 on both transcription and protein levels. Most importantly, EP can be obtained by fermentation in a mass-production.

  20. Effect of composites based nickel foam anode in microbial fuel cell using Acetobacter aceti and Gluconobacter roseus as a biocatalysts.

    Science.gov (United States)

    Karthikeyan, Rengasamy; Krishnaraj, Navanietha; Selvam, Ammaiyappan; Wong, Jonathan Woon-Chung; Lee, Patrick K H; Leung, Michael K H; Berchmans, Sheela

    2016-10-01

    This study explores the use of materials such as chitosan (chit), polyaniline (PANI) and titanium carbide (TC) as anode materials for microbial fuel cells. Nickel foam (NF) was used as the base anode substrate. Four different types of anodes (NF, NF/PANI, NF/PANI/TC, NF/PANI/TC/Chit) are thus prepared and used in batch type microbial fuel cells operated with a mixed consortium of Acetobacter aceti and Gluconobacter roseus as the biocatalysts and bad wine as a feedstock. A maximum power density of 18.8Wm(-3) (≈2.3 times higher than NF) was obtained in the case of the anode modified with a composite of PANI/TC/Chit. The MFCs running under a constant external resistance of (50Ω) yielded 14.7% coulombic efficiency with a maximum chemical oxygen demand (COD) removal of 87-93%. The overall results suggest that the catalytic materials embedded in the chitosan matrix show the best performance and have potentials for further development.

  1. 聚酰亚胺泡沫吸声性能与理论分析%Acoustic Absorption Properties and Theoretics of Polyimide Foams

    Institute of Scientific and Technical Information of China (English)

    潘丕昌; 詹茂盛; 沈燕侠; 王凯

    2009-01-01

    采用前驱体微球法制备闭孔聚酰亚胺泡沫,并对其吸声性能进行了研究.结果表明,闭孔聚酰亚胺泡沫具有共振吸声特点;对闭孔聚酰亚胺泡沫的吸声系数进行了理论推导,研究了泡沫厚度对泡沫吸声性能的影响,分析了聚酰亚胺泡沫的吸声理论;采用闭孔泡沫与开孔泡沫组合后,泡沫整体吸声性能显著提高.%The closed cell polyimide foams were fabricated by foaming the precursor balloons, and the foams' acoustic absorption properties were tested. The results show that the acoustic absorption properties of closed cell polyimide foams have the typical resonance acoustic absorption characteristic. The acoustic absorption properties of polyimide foams were researched, and the influence of thickness and density on its acoustic absorption properties were also studied, the acoustic absorption theoretics of polyimide foams was analyzed. The combination of closed cell and open cell polyimide foams can notable enhance the acoustic absorption coefficient.

  2. 闭孔泡沫铝的力学性能和吸能能力%Mechanical Properties and Energy Absorption Capability of Closed-cell Al Foam

    Institute of Scientific and Technical Information of China (English)

    王展光; 蔡萍; 应建中; 李书琴; 胡景智

    2012-01-01

    在闭孔泡沫铝准静态压缩试验的基础上,研究了其力学性能、吸能能力.结果表明,闭孔泡沫铝单轴压缩应力-应变曲线呈现践弹性变形、塑性平台阶段、致密化阶段3个阶段;闭孔泡沫铝的压缩强度、吸能能力随着孔隙率的增大而减小,采用Gibson-Ashby模型分析闭孔泡沫铝的压缩屈服强度,吻合良好.并在此基础上,提出可供工程使用的多孔泡沫金属吸能能力公式,为其工程应用提供理论支持.%Based on the compressive test of closed-cell Al foam, mechanical properties and energy absorption capacity under uniaxial compression were investigated. Compressive stress-strain curve of closed-cell Al foam consists of three distinct rcgions, the linear elasticity region, the plastic collapse region and the densification region. Compressive strength and energy absorption capacity of closed-cell Al foam decreases with the increase of porosity. Compressive yield stress is in good agreement with Gibson-Ashby model's expectation. Formula on energy absorption capability of closed-cell Al alloy foam was presentedt which could provide theoretical support for its engineering application.

  3. Combination Therapy with a Sodium-Glucose Cotransporter 2 Inhibitor and a Dipeptidyl Peptidase-4 Inhibitor Additively Suppresses Macrophage Foam Cell Formation and Atherosclerosis in Diabetic Mice

    Science.gov (United States)

    Hiromura, Munenori; Mori, Yusaku; Kohashi, Kyoko; Kushima, Hideki; Ohara, Makoto; Watanabe, Takuya; Andersson, Olov

    2017-01-01

    Dipeptidyl peptidase-4 inhibitors (DPP-4is), in addition to their antihyperglycemic roles, have antiatherosclerotic effects. We reported that sodium-glucose cotransporter 2 inhibitors (SGLT2is) suppress atherosclerosis in a glucose-dependent manner in diabetic mice. Here, we investigated the effects of combination therapy with SGLT2i and DPP-4i on atherosclerosis in diabetic mice. SGLT2i (ipragliflozin, 1.0 mg/kg/day) and DPP-4i (alogliptin, 8.0 mg/kg/day), either alone or in combination, were administered to db/db mice or streptozotocin-induced diabetic apolipoprotein E-null (Apoe−/−) mice. Ipragliflozin and alogliptin monotherapies improved glucose intolerance; however, combination therapy did not show further improvement. The foam cell formation of peritoneal macrophages was suppressed by both the ipragliflozin and alogliptin monotherapies and was further enhanced by combination therapy. Although foam cell formation was closely associated with HbA1c levels in all groups, DPP-4i alone or the combination group showed further suppression of foam cell formation compared with the control or SGLT2i group at corresponding HbA1c levels. Both ipragliflozin and alogliptin monotherapies decreased scavenger receptors and increased cholesterol efflux regulatory genes in peritoneal macrophages, and combination therapy showed additive changes. In diabetic Apoe−/− mice, combination therapy showed the greatest suppression of plaque volume in the aortic root. In conclusion, combination therapy with SGLT2i and DPP4i synergistically suppresses macrophage foam cell formation and atherosclerosis in diabetic mice.

  4. Experimental investigation on pore size effect on the linear viscoelastic properties of acoustic foams.

    Science.gov (United States)

    Deverge, Mickaël; Benyahia, Lazhar; Sahraoui, Sohbi

    2009-09-01

    This paper presents linear viscoelastic measurement on a large frequency range (10(-2)-10(8) Hz) for cross-linked polymer open-cell foams of same density and different pore sizes. This large extension of frequency range is obtained by the validation of a frequency-temperature superposition principle, commonly used with polymers. At higher frequencies, the shear moduli are independent of the pore size. In acoustical insulation range (1 Hz-16 kHz), the shear moduli decreases with the foams' pore size.

  5. Bacteria-Affinity 3D Macroporous Graphene/MWCNTs/Fe3O4 Foams for High-Performance Microbial Fuel Cells.

    Science.gov (United States)

    Song, Rong-Bin; Zhao, Cui-E; Jiang, Li-Ping; Abdel-Halim, Essam Sayed; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-06-29

    Promoting the performance of microbial fuel cells (MFCs) relies heavily on the structure design and composition tailoring of electrode materials. In this work, three-dimensional (3D) macroporous graphene foams incorporated with intercalated spacer of multiwalled carbon nanotubes (MWCNTs) and bacterial anchor of Fe3O4 nanospheres (named as G/MWCNTs/Fe3O4 foams) were first synthesized and used as anodes for Shewanella-inoculated microbial fuel cells (MFCs). Thanks to the macroporous structure of 3D graphene foams, the expanded electrode surface by MWCNTs spacing, as well as the high affinity of Fe3O4 nanospheres toward Shewanella oneidensis MR-1, the anode exhibited high bacterial loading capability. In addition to spacing graphene nanosheets for accommodating bacterial cells, MWCNTs paved a smoother way for electron transport in the electrode substrate of MFCs. Meanwhile, the embedded bioaffinity Fe3O4 nanospheres capable of preserving the bacterial metabolic activity provided guarantee for the long-term durability of the MFCs. With these merits, the constructed MFC possessed significantly higher power output and stronger stability than that with conventional graphite rod anode.

  6. ROS via BTK-p300-STAT1-PPARγ signaling activation mediates cholesterol crystals-induced CD36 expression and foam cell formation

    Directory of Open Access Journals (Sweden)

    Sivareddy Kotla

    2017-04-01

    Full Text Available In understanding the mechanisms of cholesterol in the pathogenesis of atherosclerosis, previous studies from other laboratories have demonstrated that cholesterol crystals (CC induce scavenger receptor CD36 expression and NLRP3-mediated inflammasome formation. In elucidating the mechanisms by which CC could enhance CD36 expression and foam cell formation, here we report that CC via NADPH and xanthine oxidases-mediated ROS production activates BTK, a non-receptor tyrosine kinase. In addition, CC induce p300 tyrosine phosphorylation and activation in a BTK-dependent manner, which in turn, leads to STAT1 acetylation and its interaction with PPARγ in CD36 expression, oxLDL uptake and foam cell formation. Furthermore, p300, STAT1 and PPARγ bound to a STAT binding site at −107 nt in CD36 promoter and enhanced its activity in ROS and BTK-dependent manner. Disruption of this STAT binding site by site-directed mutagenesis abolished CC-induced CD36 promoter activity. Together these results reveal for the first time that CC via producing ROS and activating BTK causes p300-mediated STAT1 acetylation and its interaction with PPARγ in CD36 expression, oxLDL uptake and foam cell formation.

  7. Microstructure and Electrical Conductivity of CNTs/PMMA Nanocomposite Foams Foaming by Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    YUAN Huan; XIONG Yuanlu; LUO Guoqiang; LI Meijuan; SHEN Qiang; ZHANG Lianmeng

    2016-01-01

    The carbon nanotubes (CNTs)/ polymethylmethacrylate (PMMA) nanocomposite foams were prepared by the anti-solvent precipitation and supercritical foaming method. The morphology and the electrical conductivity of the foams with different kinds of CNTs were investigated. The experimental results showed that all the foams had uniform cell structure, and the cell size changed from 1.9 to 10 μm when the foaming temperature ranged from 50℃ to 95℃. With small cell size (1.9-4.0 μm), the conductivities of the foams were 3.34×10-6-4.16×10-6 S/cm compared with the solid matrix since the introduction of micro cells did not destroy the conductive network. However, when the cell size was biger (4.5-10 μm), the aspect ratio of the CNTs played the dominant role of the conductivity. The foams with short CNTs had higher conductivity, since the short CNTs were hard to stretch and snap by the cells and can well-dispersed in the cell wall and cell edges. The results of this work provided a novel material design method for conductive foams based on the rule of both microstructure and aspect ratio of the CNTs.

  8. Influence of Orientation and Radiative Heat Transfer on Aluminum Foams in Buoyancy-Induced Convection

    Directory of Open Access Journals (Sweden)

    Marijn Billiet

    2015-10-01

    Full Text Available Two differently-produced open-cell aluminum foams were compared to a commercially available finned heat sink. Further, an aluminum plate and block were tested as a reference. All heat sinks have the same base plate dimensions of four by six inches. The first foam was made by investment casting of a polyurethane preform and has a porosity of 0.946 and a pore density of 10 pores per linear inch. The second foam is manufactured by casting over a solvable core and has a porosity of 0.85 and a pore density of 2.5 pores per linear inch. The effects of orientation and radiative heat transfer are experimentally investigated. The heat sinks are tested in a vertical and horizontal orientation. The effect of radiative heat transfer is investigated by comparing a painted/anodized heat sink with an untreated one. The heat flux through the heat sink for a certain temperature difference between the environment and the heat sink’s base plate is used as the performance indicator. For temperature differences larger than 30 °C, the finned heat sink outperforms the in-house-made aluminum foam heat sink on average by 17%. Furthermore, the in-house-made aluminum foam dissipates on average 12% less heat than the other aluminum foam for a temperature difference larger than 40 °C. By painting/anodizing the heat sinks, the heat transfer rate increased on average by 10% to 50%. Finally, the thermal performance of the horizontal in-house-made aluminum foam heat sink is up to 18% larger than the one of the vertical aluminum foam heat sink.

  9. Expanded polylactide bead foaming - A new technology

    Science.gov (United States)

    Nofar, M.; Ameli, A.; Park, C. B.

    2015-05-01

    Bead foaming technology with double crystal melting peak structure has been recognized as a promising method to produce low-density foams with complex geometries. During the molding stage of the bead foams, the double peak structure generates a strong bead-to-bead sintering and maintains the overall foam structure. During recent years, polylactide (PLA) bead foaming has been of the great interest of researchers due to its origin from renewable resources and biodegradability. However, due to the PLA's low melt strength and slow crystallization kinetics, the attempts have been limited to the manufacturing methods used for expanded polystyrene. In this study, for the first time, we developed microcellular PLA bead foams with double crystal melting peak structure. Microcellular PLA bead foams were produced with expansion ratios and average cell sizes ranging from 3 to 30-times and 350 nm to 15 µm, respectively. The generated high melting temperature crystals during the saturation significantly affected the expansion ratio and cell density of the PLA bead foams by enhancing the PLA's poor melt strength and promoting heterogeneous cell nucleation around the crystals.

  10. Torsion Property of the Structure Bonded Aluminum Foam Due to Impact

    Directory of Open Access Journals (Sweden)

    Hwang G.W.

    2017-06-01

    Full Text Available An aluminum foam added with foaming agent, is classified into an open-cell type for heat transfer and a closed-cell type for shock absorption. This study investigates the characteristic on the torsion of aluminum foam for a closed-cell type under impact. The fracture characteristics are investigated through the composite of five types of aluminum foam (the thicknesses of 25, 35, 45, 55 and 65 mm, when applying the torsional moment of impact energy on the junction of a porous structure attached by an adhesive. When applying the impact energy of 100, 200 and 300J, the aluminum foams with thicknesses of 25 mm and 35 mm broke off under all conditions. For the energy over 200J, aluminums thicker than 55 mm continued to be attached. Furthermore, the aluminum specimens with thicknesses of 55 mm and 65 mm that were attached with more than 30% of bonding interface remained, proving that they could maintain bonding interface against impact energy. By comparing the data based on the analysis and test result, an increase in the thickness of specimen leads to the plastic deformation as the stress at the top and bottom of bonding interface moves to the middle by spreading the stress horizontally. Based on this fracture characteristic, this study can provide the data on the destruction and separation of bonding interface and may contribute to the safety design.

  11. Bubble and foam chemistry

    CERN Document Server

    Pugh, Robert J

    2016-01-01

    This indispensable guide will equip the reader with a thorough understanding of the field of foaming chemistry. Assuming only basic theoretical background knowledge, the book provides a straightforward introduction to the principles and properties of foams and foaming surfactants. It discusses the key ideas that underpin why foaming occurs, how it can be avoided and how different degrees of antifoaming can be achieved, and covers the latest test methods, including laboratory and industrial developed techniques. Detailing a variety of different kinds of foams, from wet detergents and food foams, to polymeric, material and metal foams, it connects theory to real-world applications and recent developments in foam research. Combining academic and industrial viewpoints, this book is the definitive stand-alone resource for researchers, students and industrialists working on foam technology, colloidal systems in the field of chemical engineering, fluid mechanics, physical chemistry, and applied physics.

  12. Microbial analysis in biogas reactors suffering by foaming incidents.

    Science.gov (United States)

    Kougias, Panagiotis G; De Francisci, Davide; Treu, Laura; Campanaro, Stefano; Angelidaki, Irini

    2014-09-01

    Foam formation can lead to total failure of digestion process in biogas plants. In the present study, possible correlation between foaming and the presence of specific microorganisms in biogas reactors was elucidated. The microbial ecology of continuous fed digesters overloaded with proteins, lipids and carbohydrates before and after foaming incidents was characterized using 16S rRNA gene sequencing. Moreover, the microbial diversity between the liquid and foaming layer was assessed. A number of genera that are known to produce biosurfactants, contain mycolic acid in their cell wall, or decrease the surface tension of the media, increased their relative abundance after foam formation. Finally, a microorganism similar to widely known foaming bacteria (Nocardia and Desulfotomaculum) was found to increase its relative abundance in all reactors once foam was observed, regardless of the used substrate. These findings suggest that foaming and specific microorganisms might have direct association which requires to be further investigated.

  13. Three-dimensional graphene foams loaded with bone marrow derived mesenchymal stem cells promote skin wound healing with reduced scarring.

    Science.gov (United States)

    Li, Zhonghua; Wang, Haiqin; Yang, Bo; Sun, Yukai; Huo, Ran

    2015-12-01

    The regeneration of functional skin remains elusive, due to poor engraftment, deficient vascularization, and excessive scar formation. Aiming to overcome these issues, the present study proposed the combination of a three-dimensional graphene foam (GF) scaffold loaded with bone marrow derived mesenchymal stem cells (MSCs) to improve skin wound healing. The GFs demonstrated good biocompatibility and promoted the growth and proliferation of MSCs. Meanwhile, the GFs loaded with MSCs obviously facilitated wound closure in animal model. The dermis formed in the presence of the GF structure loaded with MSCs was thicker and possessed a more complex structure at day 14 post-surgery. The transplanted MSCs correlated with upregulation of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), which may lead to neo-vascularization. Additionally, an anti-scarring effect was observed in the presence of the 3D-GF scaffold and MSCs, as evidenced by a downregulation of transforming growth factor-beta 1 (TGF-β1) and alpha-smooth muscle actin (α-SMA) together with an increase of TGF-β3. Altogether, the GF scaffold could guide the wound healing process with reduced scarring, and the MSCs were crucial to enhance vascularization and provided a better quality neo-skin. The GF scaffold loaded with MSCs possesses necessary bioactive cues to improve wound healing with reduced scarring, which may be of great clinical significance for skin wound healing.

  14. FeS/nickel foam as stable and efficient counter electrode material for quantum dot sensitized solar cells

    Science.gov (United States)

    Geng, Huifang; Zhu, Liqun; Li, Weiping; Liu, Huicong; Quan, Linlin; Xi, Fanxing; Su, Xunwen

    2015-05-01

    A stable and efficient FeS/nickel foam (NF) counter electrode for quantum dots-sensitized solar cells (QDSCs) is first fabricated by electrochemistry deposition and characterized with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), current voltage and impedance spectroscopy. The QDSC based on FeS/NF CE achieves a power conversion efficiency (PCE) of 4.39% attributing to the high fill factor (FF) of 0.58, and the PCE is much higher than that of based on FeS/FTO CE (2.76%) and other reported FeS CEs (1.76% and 3.34%). The phenomenon that the electrode can transform between FeS/NF (in the polysulfide electrolyte) and Fe2O3/NF (in the air) spontaneously is first reported. And the excellent stability in photoelectric performance of the CE is also demonstrated in the present work. Therefore, the FeS/NF is very promising as a stable and efficient CE for QDSCs.

  15. GABA and Topiramate Inhibit the Formation of Human Macrophage-Derived Foam Cells by Modulating Cholesterol-Metabolism-Associated Molecules

    Directory of Open Access Journals (Sweden)

    Ying Yang

    2014-04-01

    Full Text Available Aims: γ-aminobutyric acid (GABA, the principal inhibitory neurotransmitter, acts on GABA receptors to play an important role in the modulation of macrophage functions. The present study examined the effects of GABA and a GABA receptor agonist on modulating cholesterol-metabolism-associated molecules in human monocyte-derived macrophages (HMDMs. Methods: ORO stain, HPLC, qRT-PCR, Western blot and EMSA were carried out using HMDMs exposed to ox-LDL with or without GABAergic agents as the experimental model. Results: GABA and topiramate reduced the percentage of cholesterol ester in lipid-laden HMDMs by down-regulating SR-A, CD36 and LOX-1 expression and up-regulating ABCA1, ABCG1 and SR-BI expression in lipid-laden HMDMs. The production of TNF-a was decreased in GABA-and topiramate-treated lipid-laden HMDMs, and levels of interleukin (IL-6 did not change. The activation of two signaling pathways, p38MAPK and NF-γB, was repressed by GABA and topiramate in lipid-laden HMDMs. Conclusion: GABA and topiramate inhibit the formation of human macrophage-derived foam cells and may be a possibility for macrophage targeted therapy of atherosclerotic lesions.

  16. Thermal-mechanical behavior of sandwich panels with closed-cell foam core under intensive laser irradiation

    Directory of Open Access Journals (Sweden)

    Li Zhi-Qiang

    2014-01-01

    Full Text Available Temperature field and thermal deformation of sandwich panels with closed-cell aluminum alloy foam core and heat-protective layer, which are subjected to Gaussian laser beam intensively irradiating, are investigated numerically. In transient heat analysis models, the influence of thermal conductivity, specific heat, and thickness of heat-protective layer on the temperature rise of the sandwich panels is calculated. In stress analysis models, a sequence coupled numerical method is utilized to simulate the thermal stress and deformation of sandwich panels induced by thermal expansion. Simulation results indicate that the temperature at center of sandwich panel increases firstly and then drops gradually with the increase of thermal conductivity of heat-protective layer after laser irradiation, and the critical thermal conductivity is obtained, while it decreases with the increase of specific heat and thickness of heat-protective layer. The thermal stress verifies the “Cyclo-hoop effect”, i. e. radial stress is compression stress in “hot zone” and tension stress in “cold zone”. The max thermal deformation of sandwich panels slightly increases with the increase of thickness of heat-protective layer for given specific heat and thermal conductivity.

  17. Characterization of Fatigue Fractures in Closed-Cell Aluminum Foam Using x-ray Micro-Computed Tomography

    Science.gov (United States)

    Kafka, O. L.; Ingraham, M. D.; Morrison, D. J.; Issen, K. A.

    2014-03-01

    A post-mortem study of Alporas closed-cell aluminum foam specimens previously failed under strain-controlled fully reversed tension-compression fatigue was conducted using x-ray micro-computed tomography (μCT). Volumetric renders of the 3D structure of the material were produced. Fractures were identified and marked throughout voxel-based images of the specimens. This produced a 3D plot of fracture locations. At high strain amplitudes (0.175-0.5%), fractures formed an interconnected planar zone oriented approximately perpendicular to the loading axis; typically, the angle of the plane differed from that of a tension failure. Conversely, at low strain amplitudes (0.05-0.1%), short fractures have been formed diffusely within the specimen. In both cases, observed fractures were tortuous. Our previous work with surface strain mapping via digital image correlation (DIC) suggested that for all strain amplitudes, a crack, evidenced by a zone of high extensile strain, was formed and propagated through the material. This result was confirmed at high strain amplitudes, but not at low strain amplitudes. The discrepancy is attributed to three potential causes. Using DIC, short cracks cannot be accurately resolved with relatively coarse light intensity patterns. DIC images indicate fractures under load, while μCT imaging was conducted under zero load. Finally, the localized extension seen in DIC images could be attributed to strain with no resultant fractures.

  18. Dihydroaustrasulfone Alcohol (WA-25 Impedes Macrophage Foam Cell Formation by Regulating the Transforming Growth Factor-β1 Pathway

    Directory of Open Access Journals (Sweden)

    Yi-Chen Wang

    2015-05-01

    Full Text Available Atherosclerosis is considered an inflammatory disease. However, clinically used anti-atherosclerotic drugs, such as simvastatin, have many side effects. Recently, several unique marine compounds have been isolated that possess a variety of bioactivities. In a previous study, we found a synthetic precursor of the marine compound (austrasulfone, which is dihydroaustrasulfone alcohol (WA-25, has anti-atherosclerotic effects in vivo. However, the detailed mechanisms remain unclear. Therefore, to clarify the mechanisms through which WA-25 exerts anti-atherosclerotic activity, we used RAW 264.7 macrophages as an in vitro model to evaluate the effects of WA-25. In lipopolysaccharide (LPS-stimulated RAW 264.7 cells, WA-25 significantly inhibited expression of the pro-inflammatory proteins, inducible nitric oxide synthase (iNOS and cyclooxygenase-2 (COX-2. In contrast, simvastatin increased the COX-2 expression compared to WA-25. In addition, WA-25 impedes foam cell formation and up-regulated the lysosomal and cyclic adenosine monophosphate (cAMP signaling pathway. We also observed that transforming growth factor β1 (TGF-β1 was up-regulated by WA-25 and simvastatin in LPS-induced RAW 264.7 cells, and the promising anti-atherosclerosis effects of WA-25 were disrupted by blockade of TGF-β1 signaling. Besides, WA-25 might act through increasing lipolysis than through alteration of lipid export. Taken together, these data demonstrate that WA-25 may have potential as an anti-atherosclerotic drug with anti-inflammatory effects.

  19. Foams theory, measurements, and applications

    CERN Document Server

    Khan, Saad A

    1996-01-01

    This volume discusses the physics and physical processes of foam and foaming. It delineates various measurement techniques for characterizing foams and foam properties as well as the chemistry and application of foams. The use of foams in the textile industry, personal care products, enhanced oil recovery, firefighting and mineral floatation are highlighted, and the connection between the microstructure and physical properties of foam are detailed. Coverage includes nonaqueous foams and silicone antifoams, and more.

  20. Identification of strain fields in pure Al and hybrid Ni/Al metal foams using X-ray micro-tomography under loading

    Science.gov (United States)

    Fíla, T.; Jiroušek, O.; Jung, A.; Kumpová, I.

    2016-11-01

    Hybrid foams are materials formed by a core from a standard open cell metal foam that is during the process of electrodeposition coated by a thin layer of different nanocrystalline metals. The material properties of the base metal foam are in this way modified resulting in higher plateau stress and, more importantly, by introduction of strain-rate dependence to its deformation response. In this paper, we used time-lapse X-ray micro-tomography for the mechanical characterization of Ni/Al hybrid foams (aluminium open cell foams with nickel coating layer). To fully understand the effects of the coating layer on the material's effective properties, we compared the compressive response of the base uncoated foam to the response of the material with coating thickness of 50 and 75 μm. Digital volume correlation (DVC) was applied to obtain volumetric strain fields of the deforming micro-structure up to the densification region of the deforming cellular structure. The analysis was performed as a compressive mechanical test with simultaneous observation using X-ray radiography and tomography. A custom design experimental device was used for compression of the foam specimens in several deformation states directly in the X-ray setup. Planar X-ray images were taken during the loading phases and a X-ray tomography was performed at the end of each loading phase (up to engineering strain 22%). The samples were irradiated using micro-focus reflection type X-ray tube and images were taken using a large area flat panel detector. Tomography reconstructions were used for an identification of a strain distribution in the foam using digital volumetric correlation. A comparison of the deformation response of the coated and the uncoated foam in uniaxial quasi-static compression is summarized in the paper.

  1. The silver-releasing foam dressing, Contreet Foam, promotes faster healing of critically colonised venous leg ulcers: a randomised, controlled trial

    DEFF Research Database (Denmark)

    Jørgensen, Bo; Price, Patricia; Andersen, Klaus E

    2005-01-01

    The study compared the effect of a sustained silver-release foam dressing (Contreet Foam) with a foam dressing (Allevyn Hydrocellular) without added silver in critically colonised venous leg ulcers with delayed healing. The study was a multicentre, open, randomised, controlled study lasting for 4...

  2. Method to evaluate foaming in petroleum

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, A.K.; Rezende, D.A.; Santos, R.F.; Mansur, C.R.E. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas], e-mail: celias@ima.ufrj.br

    2011-01-15

    In oil fields, gravitational separation tanks are generally used to separate the oil, gas and water phases, remove emulsifying agents present at the interfaces and permit the coalescence of water droplets associated with the crude oil being pumped. The main problem that influences the performance of these separators is the formation of foam. In this work, a method was developed to evaluate foaming in crude oil in laboratory scale, reproducing the operation conditions in gas-oil separators in real fields. This method was employed with seven crude oil samples, and the performance of silicone anti foams with different molar masses could be tested. The results indicated that the method of evaluating the breakdown of foam in oil by using the Aging Cell apparatus in a roller oven proved to be suitable. It was observed that the oil viscosity is a determining factor in predicting whether or not foam will form. (author)

  3. High temperature structural, polymeric foams from high internal emulsion polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Hoisington, M.A.; Duke, J.R.; Apen, P.G.

    1996-02-01

    In 1982, a high internal phase emulsion (HIPE) polymerization process to manufacture microcellular, polymeric foam systems was patented by Unilever. This patent discloses a polymerization process that occurs in a water-in-oil emulsion in which the water represents at least 76% of the emulsion by volume. The oil phase consists of vinyl monomers such as styrene and acrylates that are crosslinked by divinyl monomers during polymerization. After polymerization and drying to remove the water phase, the result is a crosslinked polymer foam with an open cell microstructure that is homogeneous throughout in terms of morphology, density, and mechanical properties. Since 1982, numerous patents have examined various HIPE polymerized foam processing techniques and applications that include absorbents for body fluids, cleaning materials, and ion exchange systems. All the published HIPE polymerized foams have concentrated on materials for low temperature applications. Copolymerization of styrene with maleic anhydride and N-substituted maleimides to produce heat resistant thermoplastics has been studied extensively. These investigations have shown that styrene will free radically copolymerize with N-substituted maleimides to create an alternating thermoplastic copolymer with a Tg of approximately 200{degrees}C. However, there are many difficulties in attempting the maleimide styrene copolymerization in a HIPE such as lower polymerization temperatures, maleimide solubility difficulties in both styrene and water, and difficulty obtaining a stable HIPE with a styrene/maleimide oil phase. This work describes the preparation of copolymer foams from N-ethylmaleimide and Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane with styrene based monomers and crosslinking agents.

  4. Polyurethane-Foam Maskant

    Science.gov (United States)

    Bodemeijer, R.

    1985-01-01

    Brown wax previously used to mask hardware replaced with polyurethane foam in electroplating and electroforming operations. Foam easier to apply and remove than wax and does not contaminate electrolytes.

  5. Thermoforming of foam sheet

    NARCIS (Netherlands)

    Akkerman, Remko; Pronk, Ruud M.

    1997-01-01

    Thermoforming is a widely used process for the manufacture of foam sheet products. Polystyrene foam food trays for instance can be produced by first heating the thermoplastic foam sheet, causing the gas contained to build up pressure and expand, after which a vacuum pressure can be applied to draw t

  6. Foam engineering fundamentals and applications

    CERN Document Server

    2012-01-01

    Containing contributions from leading academic and industrial researchers, this book provides a much needed update of foam science research. The first section of the book presents an accessible summary of the theory and fundamentals of foams. This includes chapters on morphology, drainage, Ostwald ripening, coalescence, rheology, and pneumatic foams. The second section demonstrates how this theory is used in a wide range of industrial applications, including foam fractionation, froth flotation and foam mitigation. It includes chapters on suprafroths, flotation of oil sands, foams in enhancing petroleum recovery, Gas-liquid Mass Transfer in foam, foams in glass manufacturing, fire-fighting foam technology and consumer product foams.

  7. Three-dimensional graphene foams loaded with bone marrow derived mesenchymal stem cells promote skin wound healing with reduced scarring

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhonghua [Department of Burn and Plastic Surgery, Provincial Hospital Affiliated to Shandong University, Jinan 250021 (China); Department of Burn and Plastic Surgery, The Fourth People' s Hospital Of Jinan, Jinan 250031 (China); Wang, Haiqin [Department of Obstetrics and Gynecology, The Fifth People' s Hospital Of Jinan, Jinan 250022 (China); Yang, Bo; Sun, Yukai [Department of Burn and Plastic Surgery, The Fourth People' s Hospital Of Jinan, Jinan 250031 (China); Huo, Ran, E-mail: rhuo12@163.com [Department of Burn and Plastic Surgery, Provincial Hospital Affiliated to Shandong University, Jinan 250021 (China)

    2015-12-01

    The regeneration of functional skin remains elusive, due to poor engraftment, deficient vascularization, and excessive scar formation. Aiming to overcome these issues, the present study proposed the combination of a three-dimensional graphene foam (GF) scaffold loaded with bone marrow derived mesenchymal stem cells (MSCs) to improve skin wound healing. The GFs demonstrated good biocompatibility and promoted the growth and proliferation of MSCs. Meanwhile, the GFs loaded with MSCs obviously facilitated wound closure in animal model. The dermis formed in the presence of the GF structure loaded with MSCs was thicker and possessed a more complex structure at day 14 post-surgery. The transplanted MSCs correlated with upregulation of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), which may lead to neo-vascularization. Additionally, an anti-scarring effect was observed in the presence of the 3D-GF scaffold and MSCs, as evidenced by a downregulation of transforming growth factor-beta 1 (TGF-β1) and alpha-smooth muscle actin (α-SMA) together with an increase of TGF-β3. Altogether, the GF scaffold could guide the wound healing process with reduced scarring, and the MSCs were crucial to enhance vascularization and provided a better quality neo-skin. The GF scaffold loaded with MSCs possesses necessary bioactive cues to improve wound healing with reduced scarring, which may be of great clinical significance for skin wound healing. - Highlights: • The GFs promoted the growth and proliferation of MSCs. • The GFs loaded with MSCs obviously facilitated wound closure in the animal model. • An anti-scarring effect was observed in the presence of 3D-GF scaffold and MSCs. • The GF scaffold loaded with MSCs has great effect on skin wound healing.

  8. Microcellular foaming of silicone rubber with supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Hong, In-Kwon; Lee, Sangmook [Dankook University, Youngin (Korea, Republic of)

    2014-01-15

    In spite of great concern on the industrial application of microcellular silicone rubber foams, such as in electric and medical devices, only a few works can be found about the foaming of silicone rubber. In this study, microcellular silicone rubber foams with a cell size of 12 µm were successfully prepared with curing by heat and foaming by supercritical CO{sub 2} as a green blowing agent. The microcellular silicone rubber foams exhibited a well-defined cell structure and a uniform cell size distribution. The crosslinking and foaming of silicone rubber was carried out separately. After foaming, the silicone rubber foam was cross-linked again to stabilize the foam structure and further improve its mechanical properties. Foaming process of cross-linked silicone rubber should be designed carefully based on the viscoelastic properties because of its elastic volume recovery in the atmosphere. The basic crosslinking condition for small cell size and high cell density was obtained after investigating the rheological behavior during crosslinking.

  9. High Temperature Alkaline Electrolysis Cells with Metal Foam Based Gas Diffusion Electrodes

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2016-01-01

    Alkaline electrolysis cells operating at 250°C and 40 bar are able to convert electrical energy into hydrogen at very high efficiencies and power densities. In the present work we demonstrate the application of a PTFE hydrophobic network and Ag nanowires as oxygen evolution electrocatalyst...

  10. Shooting in a foam.

    Science.gov (United States)

    Le Goff, Anne; Quéré, David; Clanet, Christophe

    2014-09-21

    We study the motion of a solid sphere after its fast impact on a bath of liquid foam. We identify two regimes of deceleration. At short times, the velocity is still large and the foam behaves similar to a Newtonian fluid of constant viscosity. Then we measure a velocity threshold below which the sphere starts experiencing the foam's elasticity. We interpret this behavior using a visco-elasto-plastic model for foam rheology. Finally we discuss the possibility of stopping a projectile in the foam, and evaluate the capture efficiency.

  11. Metal foam - a material for heat engineering. Porous structures increase the efficiency of heat exchangers and cooling elements; Metallschaum - ein Werkstoff fuer die Waermetechnik. Offenporige Strukturen steigern die Effizienz von Waermeuebertragern und Kuehlelementen

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Franz

    2016-11-01

    Metal foams are increasingly developing into materials with diverse uses. While metal foams with closed pores have already become established as rigid and strong lightweight materials, the open-cell variant is suitable for thermal engineering applications. Until now, the material has been rarely used in heat exchangers or coolers because the production is expensive and its application little tested. Researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden now want to change this. Together with industry partners, they are further developing the production method, are characterising different metal foams and are testing them in practice.

  12. Modeling of the role of defects in sintered FeCrAIY foams

    Institute of Scientific and Technical Information of China (English)

    M. Kepets; T. J. Lu; A. P. Dowling

    2007-01-01

    The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys, which offer novel mechanical and acoustic properties.In a separate experimental study, the mechanical properties of open-celled steel alloy (FeCrAlY) foams have been characterized under uniaxial compression and shear loading. Compared to predictions from established models, a significant knockdown in material properties was observed. This knockdown was attributed to the presence of defects throughout the microstructure that result from the unique fabrication process. In the present paper, the microstructure of sintered FeCrAlY foams was modeled by using a finite element (FE)model. In particular, microstructural variations were introduced to a base lattice, and the effects on the strength and stiffness calculated. A range of defects identified under scanning electronic microscope (SEM) imaging were considered including broken ligaments, thickness variations, and pore blockages, which are the three primary imperfections observed in sintered foams. The corresponding levels of defect present in the material were subsequently input into the FE model, with the resulting predictions correlating well withexperimental data.

  13. Foam process models.

    Energy Technology Data Exchange (ETDEWEB)

    Moffat, Harry K.; Noble, David R.; Baer, Thomas A. (Procter & Gamble Co., West Chester, OH); Adolf, Douglas Brian; Rao, Rekha Ranjana; Mondy, Lisa Ann

    2008-09-01

    In this report, we summarize our work on developing a production level foam processing computational model suitable for predicting the self-expansion of foam in complex geometries. The model is based on a finite element representation of the equations of motion, with the movement of the free surface represented using the level set method, and has been implemented in SIERRA/ARIA. An empirically based time- and temperature-dependent density model is used to encapsulate the complex physics of foam nucleation and growth in a numerically tractable model. The change in density with time is at the heart of the foam self-expansion as it creates the motion of the foam. This continuum-level model uses an homogenized description of foam, which does not include the gas explicitly. Results from the model are compared to temperature-instrumented flow visualization experiments giving the location of the foam front as a function of time for our EFAR model system.

  14. Foam consolidation and drainage.

    Science.gov (United States)

    Jun, S; Pelot, D D; Yarin, A L

    2012-03-27

    A theoretical model of foam as a consolidating continuum is proposed. The general model is applied to foam in a gravity settler. It is predicted that liquid drainage from foam in a gravity settler begins with a slow drainage stage. Next, a stage with faster drainage occurs where the drainage rate doubles compared to the initial stage. The experiments conducted within the framework of this work confirmed the theoretical predictions and allowed measurements of foam characteristics. Foams of three different concentrations of Pantene Pro-V Classic Care Solutions shampoo were studied, as well as the addition of polyethylene oxide (PEO) in one case. The shampoo's main foaming components are sodium lauryl sulfate and sodium laureth sulfate. It is shown to what extent foam drainage is slowed down by using higher shampoo concentrations and how it is further decreased by adding polymer (PEO).

  15. Development of Flexible Polyurethane Nanostructured Biocomposite Foams Derived from Palm Olein-Based Polyol

    Directory of Open Access Journals (Sweden)

    Srihanum Adnan

    2016-01-01

    Full Text Available This study examined the effect of organoclay montmorillonite (OMMT on the mechanical properties and morphology of flexible polyurethane/OMMT nanocomposite (PU/OMMT foams prepared from petroleum- and palm olein-based polyols. Palm-based PU foams exhibited inferior mechanical strength as compared to neat petroleum PU foams. However, addition of OMMT significantly improved the foams strength of flexible polyurethane/OMMT nanocomposite foams prepared from palm olein-based polyol (PU bionanocomposite foam. The morphology analysed by scanning electron microscopy (SEM showed that the cell size of the foam decreased with increasing OMMT content. PU bionanocomposite foam with 5 wt% of OMMT had the most improved tensile (63% and tear (48% strengths compared to its neat counterpart. Transmission electron microscopy (TEM revealed the exfoliated structure of the respective foam. It was concluded that OMMT improved mechanical properties and morphology of PU foams.

  16. Ultrasonic Measurement of Elastic Modulus of Kelvin Foam

    Directory of Open Access Journals (Sweden)

    Oh Sukwon

    2016-01-01

    Full Text Available Elastic modulus of 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam of 3 mm unit cell is designed and printed layer upon layer to fablicate a Kelvin foam plate of 14mm thickness by 3D CAD/printer using ABS plastic. The Kelvin foam plate is filled completely with paraffin wax for impedance matching, so that acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF method to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity.

  17. 11β-hydroxysteroid dehydrogenase type 1 gene knockout attenuates atherosclerosis and in vivo foam cell formation in hyperlipidemic apoE⁻/⁻ mice.

    Directory of Open Access Journals (Sweden)

    Ricardo A García

    Full Text Available BACKGROUND: Chronic glucocorticoid excess has been linked to increased atherosclerosis and general cardiovascular risk in humans. The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1 increases active glucocorticoid levels within tissues by catalyzing the conversion of cortisone to cortisol. Pharmacological inhibition of 11βHSD1 has been shown to reduce atherosclerosis in murine models. However, the cellular and molecular details for this effect have not been elucidated. METHODOLOGY/PRINCIPAL FINDINGS: To examine the role of 11βHSD1 in atherogenesis, 11βHSD1 knockout mice were created on the pro-atherogenic apoE⁻/⁻ background. Following 14 weeks of Western diet, aortic cholesterol levels were reduced 50% in 11βHSD1⁻/⁻/apoE⁻/⁻ mice vs. 11βHSD1⁺/⁺/apoE⁻/⁻ mice without changes in plasma cholesterol. Aortic 7-ketocholesterol content was reduced 40% in 11βHSD1⁻/⁻/apoE⁻/⁻ mice vs. control. In the aortic root, plaque size, necrotic core area and macrophage content were reduced ∼30% in 11βHSD1⁻/⁻/apoE⁻/⁻mice. Bone marrow transplantation from 11βHSD1⁻/⁻/apoE⁻/⁻ mice into apoE⁻/⁻ recipients reduced plaque area 39-46% in the thoracic aorta. In vivo foam cell formation was evaluated in thioglycollate-elicited peritoneal macrophages from 11βHSD1⁺/⁺/apoE⁻/⁻ and 11βHSD1⁻/⁻/apoE⁻/⁻ mice fed a Western diet for ∼5 weeks. Foam cell cholesterol levels were reduced 48% in 11βHSD1⁻/⁻/apoE⁻/⁻ mice vs. control. Microarray profiling of peritoneal macrophages revealed differential expression of genes involved in inflammation, stress response and energy metabolism. Several toll-like receptors (TLRs were downregulated in 11βHSD1⁻/⁻/apoE⁻/⁻ mice including TLR 1, 3 and 4. Cytokine release from 11βHSD1⁻/⁻/apoE⁻/⁻-derived peritoneal foam cells was attenuated following challenge with oxidized LDL. CONCLUSIONS: These findings suggest that 11βHSD1 inhibition may have

  18. Application of Spray Foam Insulation Under Plywood and Oriented Strand Board Roof Sheathing

    Energy Technology Data Exchange (ETDEWEB)

    Grin, A.; Smegal, J.; Lstiburek, J.

    2013-10-01

    Unvented roof strategies with open cell and closed cell spray polyurethane foam insulation sprayed to the underside of roof sheathing have been used since the mid-1990's to provide durable and efficient building enclosures. However, there have been isolated moisture related incidents reported anecdotally that raise potential concerns about the overall hygrothermal performance of these systems. The incidents related to rainwater leakage and condensation concerns. Condensation concerns have been extensively studied by others and are not further discussed in this report. This project involved hygrothermal modeling of a range of rainwater leakage and field evaluations of in-service residential roofs using spray foam insulation. All of the roof assemblies modeled exhibited drying capacity to handle minor rainwater leakage. All field evaluation locations of in-service residential roofs had moisture contents well within the safe range for wood-based sheathing. Explorations of eleven in-service roof systems were completed. The exploration involved taking a sample of spray foam from the underside of the roof sheathing, exposing the sheathing, then taking a moisture content reading. All locations had moisture contents well within the safe range for wood-based sheathing. One full-roof failure was reviewed, as an industry partner was involved with replacing structurally failed roof sheathing. In this case the manufacturer's investigation report concluded that the spray foam was installed on wet OSB based on the observation that the spray foam did not adhere well to the substrate and the pore structure of the closed cell spray foam at the ccSPF/OSB interface was indicative of a wet substrate.

  19. 'Open minded' cells: how cells can change fate.

    Science.gov (United States)

    Costa, Silvia; Shaw, Peter

    2007-03-01

    It has long intrigued researchers why some but not all organisms can regenerate missing body parts. Plants are remarkable in that they can regenerate the entire organism from a small piece of tissue, or even a single cell. Epigenetic mechanisms that control chromatin organization are now known to regulate the cellular plasticity and reprogramming necessary for regeneration. Interestingly, although animals and plants have evolved different strategies and mechanisms to control developmental processes, they have maintained many similarities in the way they regulate chromatin organization. Given that plants can rapidly switch fate, we propose that an understanding of the mechanisms regulating this process in plant cells could provide a new perspective on cellular dedifferentiation in animals.

  20. A Successful Industrial Academic Cooperation, Development of Closed-cell Metallic Foams

    Directory of Open Access Journals (Sweden)

    Sheng-Chung Tzeng

    2005-01-01

    Full Text Available This investigation proposes a successful case of industrial-academic cooperation between the Chienkuo Technology University and J. King Aluminum Inc. This study was proposed by the rotating machinery and heat transfer laboratory. They studied the optimal heat transfer and structural strength of closed-cell aluminum porous material. The cooperation involved the exchange of technical skills; the determination of policies and methods for establishing a lasting relationship, to ensure mutual trust between the parties involved and the elucidation of the benefits enjoyed by both sides. This study seeks to provide a good example to local technical industrial institutions of successful industrial-academic cooperation to promote academic professional research and the establishment of empirical formulae from relevant experimental data. The results of the example are useful in designing an electronic package and cooling device will lead to the novel material applications and reduce the cost of research in related industries, improving global production and marketing, also motivates students to combine academic skills and industrial practice as part of a professional education.

  1. Biodiesel production by using lipase immobilized onto novel silica-based hybrid foams

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Nicolas [Centre de Recherche Paul Pascal, Pessac (France); Institut des Sciences Moleculaires, Talence (France); Garcia, Annick Babeau; Oestreicher, Victor; Durand, Fabien; Backov, Renal [Centre de Recherche Paul Pascal, Pessac (France); Deleuze, Herve [Institut des Sciences Moleculaires, Talence (France); Laurent, Guillaume; Sanchez, Clement [Laboratoire de Chimie de la Matiere Condensee, Paris (France)

    2010-07-01

    The covalent immobilization of crude lipases within silica-based macroporous frameworks have been performed by combining sol-gel process, concentrated direct emulsion, lyotropic mesophase and post-synthesis functionalizations. The assynthesized open cell hybrid monoliths exhibit high macroscopic porosity, around 90%, providing interconnected scaffold while reducing the diffusion low kinetic issue. The entrapment of enzymes in such foams deals with a high stability over esterification of fatty acids, hydrolysis of triglycerides (not shown herein) and biodiesel production by transesterification. (orig.)

  2. Drainage and Stratification Kinetics of Foam Films

    Science.gov (United States)

    Zhang, Yiran; Sharma, Vivek

    2014-03-01

    Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Foam lifetime, drainage kinetics and stability are strongly influenced by surfactant type (ionic vs non-ionic), and added proteins, particles or polymers modify typical responses. The rate at which fluid drains out from a foam film, i.e. drainage kinetics, is determined in the last stages primarily by molecular interactions and capillarity. Interestingly, for certain low molecular weight surfactants, colloids and polyelectrolyte-surfactant mixtures, a layered ordering of molecules, micelles or particles inside the foam films leads to a stepwise thinning phenomena called stratification. Though stratification is observed in many confined systems including foam films containing particles or polyelectrolytes, films containing globular proteins seem not to show this behavior. Using a Scheludko-type cell, we experimentally study the drainage and stratification kinetics of horizontal foam films formed by protein-surfactant mixtures, and carefully determine how the presence of proteins influences the hydrodynamics and thermodynamics of foam films.

  3. Feynman diagrammatic approach to spin foams

    CERN Document Server

    Kisielowski, Marcin; Puchta, Jacek

    2011-01-01

    "The Spin Foams for People Without the 3d/4d Imagination" could be an alternative title of our work. We derive spin foams from operator spin network diagrams} we introduce. Our diagrams are the spin network analogy of the Feynman diagrams. Their framework is compatible with the framework of Loop Quantum Gravity. For every operator spin network diagram we construct a corresponding operator spin foam. Admitting all the spin networks of LQG and all possible diagrams leads to a clearly defined large class of operator spin foams. In this way our framework provides a proposal for a class of 2-cell complexes that should be used in the spin foam theories of LQG. Within this class, our diagrams are just equivalent to the spin foams. The advantage, however, in the diagram framework is, that it is self contained, all the amplitudes can be calculated directly from the diagrams without explicit visualization of the corresponding spin foams. The spin network diagram operators and amplitudes are consistently defined on thei...

  4. Cell Division, a new open access online forum for and from the cell cycle community

    Directory of Open Access Journals (Sweden)

    Kaldis Philipp

    2006-04-01

    Full Text Available Abstract Cell Division is a new, open access, peer-reviewed online journal that publishes cutting-edge articles, commentaries and reviews on all exciting aspects of cell cycle control in eukaryotes. A major goal of this new journal is to publish timely and significant studies on the aberrations of the cell cycle network that occur in cancer and other diseases.

  5. Mitochondrion-Targeted Peptide SS-31 Inhibited Oxidized Low-Density Lipoproteins-Induced Foam Cell Formation through both ROS Scavenging and Inhibition of Cholesterol Influx in RAW264.7 Cells.

    Science.gov (United States)

    Hao, Shuangying; Ji, Jiajie; Zhao, Hongting; Shang, Longcheng; Wu, Jing; Li, Huihui; Qiao, Tong; Li, Kuanyu

    2015-12-01

    Foam cell formation as a result of imbalance of modified cholesterol influx and efflux by macrophages is a key to the occurrence and development of atherosclerosis. Oxidative stress is thought to be involved in the pathogenesis of atherosclerosis. SS-31 is a member of the Szeto-Schiller (SS) peptides shown to specifically target the inner mitochondrial membrane to scavenge reactive oxygen species. In this study, we investigated whether SS-31 may provide protective effect on macrophage from foam cell formation in RAW264.7 cells. The results showed that SS-31 inhibited oxidized low-density lipoproteins (ox-LDL)-induced foam cell formation and cholesterol accumulation, demonstrated by intracellular oil red O staining and measurement of cholesterol content. The mechanism was revealed that SS-31 did not only significantly attenuated ox-LDL-induced generation of reactive oxygen species (ROS) and increased the activities of superoxide dismutases, but also dose-dependently inhibited the expression of CD36 and LOX-1, two scavenger receptors of ox-LDL, while the expression of ATP-binding cassette A1 and G1, playing a pivotal role in cholesterol efflux, was not affected. As a result, SS-31 decreased pro-inflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha, suggesting the prevention of inflammatory responses. In conclusion, our results demonstrate that SS-31 provides a beneficial effect on macrophages from foam cell formation, likely, through both ROS scavenging and inhibition of cholesterol influx. Therefore, SS-31 may potentially be of therapeutic relevance in prevention of human atherogenesis.

  6. Urotensin II increases foam cell formation by repressing ABCA1 expression through the ERK/NF-κB pathway in THP-1 macrophages

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan [Department of Anesthesiology, The Second Affiliated Hospital of University of South China, Hengyang 421001, Hunan (China); Wu, Jian-Feng [Department of Cardiovascular Medicine, The Second Affiliated Hospital of University of South China, Hengyang 421001, Hunan (China); Tang, Yan-Yan; Zhang, Min; Li, Yuan [Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang 421001, Hunan (China); Chen, Kong; Zeng, Meng-Ya [Department of Cardiovascular Medicine, The Second Affiliated Hospital of University of South China, Hengyang 421001, Hunan (China); Yao, Feng; Xie, Wei [Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang 421001, Hunan (China); Zheng, Xi-Long [Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute of Alberta, University of Calgary, Health Sciences Center, 3330 Hospital Dr NW, Calgary, Alberta T2N 4N1 (Canada); Zeng, Gao-Feng, E-mail: qichingnudou@tom.com [Department of Cardiovascular Medicine, The Second Affiliated Hospital of University of South China, Hengyang 421001, Hunan (China); Tang, Chao-Ke, E-mail: tangchaoke@qq.com [Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang 421001, Hunan (China)

    2014-10-03

    Highlights: • U II reduces cholesterol efflux in THP-1 macrophages. • U II decreases the expression of ABCA1. • Inhibition of the ERK/NF-κB pathway reduces U II effects on ABCA1 expression and cholesterol efflux. - Abstract: Objective: Foam cell formation in the arterial wall plays a key role in the development of atherosclerosis. Recent studies showed that Urotensin II (U II) is involved in the pathogenesis of atherosclerosis. Here we examined the effects of human U II on ATP-binding cassette transporter A1 (ABCA1) expression and the underlying mechanism in THP-1 macrophages. Methods and results: Cultured THP-1 macrophages were treated with U II, followed by measuring the intracellular lipid contents, cholesterol efflux and ABCA1 levels. The results showed that U II dramatically decreased ABCA1 levels and impaired cholesterol efflux. However, the effects of U II on ABCA1 protein expression and cellular cholesterol efflux were partially reversed by inhibition of extracellular signal regulated kinase 1/2 (ERK1/2) and nuclear factor kappa B (NF-κB) activity, suggesting the potential roles of ERK1/2 and NF-κB in ABCA1 expression, respectively. Conclusion: Our current data indicate that U II may have promoting effects on the progression of atherosclerosis, likely through suppressing ABCA1 expression via activation of the ERK/NF-κB pathway and reducing cholesterol efflux to promote macrophage foam cell formation.

  7. Enhancement of osteogenic differentiation of human adipose derived stem cells by the controlled release of platelet lysates from hybrid scaffolds produced by supercritical fluid foaming.

    Science.gov (United States)

    Santo, Vítor E; Duarte, Ana Rita C; Popa, Elena G; Gomes, Manuela E; Mano, João F; Reis, Rui L

    2012-08-20

    A new generation of scaffolds capable of acting not only as support for cells but also as a source of biological cues to promote tissue regeneration is currently a hot topic of in bone Tissue Engineering (TE) research. The inclusion of growth factor (GF) controlled release functionalities in the scaffolds is a possible strategy to achieve such goal. Platelet Lysate (PL) is an autologous source of GFs, providing several bioactive agents known to act on bone regeneration. In this study, chitosan-chondroitin sulfate nanoparticles loaded with PL were included in a poly(D,L-lactic acid) foam produced by supercritical fluid foaming. The tridimensional (3D) structures were then seeded with human adipose-derived stem cells (hASCs) and cultured in vitro under osteogenic stimulus. The osteogenic differentiation of the seeded hASCs was observed earlier for the PL-loaded constructs, as shown by the earlier alkaline phosphatase peak and calcium detection and stronger Runx2 expression at day 7 of culture, in comparison with the control scaffolds. Osteocalcin gene expression was upregulated in presence of PL during all culture period, which indicates an enhanced osteogenic induction. These results suggest the synergistic effect of PL and hASCs in combinatory TE strategies and support the potential of PL to increase the multifunctionality of the 3D hybrid construct for bone TE applications.

  8. Dynamic compressive behavior of foamed polyethylene film

    Directory of Open Access Journals (Sweden)

    Tateyama Kohei

    2015-01-01

    Full Text Available The foamed film as the shock absorption material has attracted much attention because it is thin (100 μm ∼ 400 μm and has a closed cell structure. However, the dynamic mechanical properties have not been reported in the foamed film. The purpose of this study is to elucidate the compressive behavior of the foamed polyethylene film at the wide strain rate range. First, the new compressive test apparatus for the dynamic strain rate, the drop-weight testing machine with opposed load cell, was developed, which can be also evaluated the dynamic stress equilibrium of the specimen. It is confirmed that the compressive flow stress increased with increasing the strain rate, regardless of the film thickness. The foamed polyethylene film has the high strain rate sensitivity in the quasi-static deformation. On the other hand, there is almost no change of the strain rate sensitivity in the dynamic and the impact deformation. In order to investigate the mechanism of strain rate dependence, the foamed polyethylene film was observed by X-ray computed tomography scanner before and after compressive test. The fracture of the closed cell only occurred in the quasi-static deformation. It was clarified that the strain rate sensitivity of the foamed film depends strongly on that of the construction material, polyethylene.

  9. Anaerobic Digestion Foaming Causes

    OpenAIRE

    Ganidi, Nafsika

    2008-01-01

    Anaerobic digestion foaming has been encountered in several sewage treatment plants in the UK. Foaming has raised major concerns for the water utilities due to significant impacts on process efficiency and operational costs. Several foaming causes have been suggested over the past few years by researchers. However, the supporting experimental information is limited and in some cases site specific. The present report aimed to provide a better understanding of the anaerobic di...

  10. The science of foaming.

    Science.gov (United States)

    Drenckhan, Wiebke; Saint-Jalmes, Arnaud

    2015-08-01

    The generation of liquid foams is at the heart of numerous natural, technical or scientific processes. Even though the subject of foam generation has a long-standing history, many recent progresses have been made in an attempt to elucidate the fundamental processes at play. We review the subject by providing an overview of the relevant key mechanisms of bubble generation within a coherent hydrodynamic context; and we discuss different foaming techniques which exploit these mechanisms.

  11. Fire-retardant foams

    Science.gov (United States)

    Gagliani, J.

    1978-01-01

    Family of polyimide resins are being developed as foams with exceptional fire-retardant properties. Foams are potentially useful for seat cushions in aircraft and ground vehicles and for applications such as home furnishings and building-construction materials. Basic formulations can be modified with reinforcing fibers or fillers to produce celular materials for variety of applications. By selecting reactants, polymer structure can be modified to give foams with properties ranging from high resiliency and flexibility to brittleness and rigidity.

  12. Composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  13. Composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Kaschmitter, James L. (Pleasanton, CA)

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  14. Preparation and properties of polymer foams for ICF targets

    Energy Technology Data Exchange (ETDEWEB)

    Letts, S.A.; Lucht, L.M.

    1986-09-01

    Low density small cell sized foams were developed to localize the liquid DT layer in a direct drive wetted foam laser fusion target. We have developed foams made from ultrahigh molecular weight polyethylene gels and polystyrene inverse emulsions. Materials in the density range of from 0.020 to 0.300 g/cc were prepared and characterized for cell size, mechanical properties, machinability, specific surface area, and wetting. Foams with a density of 0.05 g/cc were made with a cell size of less than 5 ..mu..m. A cell structure model was developed which relates the density and specific surface area to cell size and cell wall thickness. Wetting tests in organic solvents and in liquid hydrogen were used to characterize the capillary pressure, pore structure and uniformity of the foams. 13 refs., 9 figs., 2 tabs.

  15. Inhibiting NF-K B increases cholesterol efflux from THP-1 derived- foam cells treated with Angll via up-regulating the expression of ATP-binding cassette transporter A1

    Institute of Scientific and Technical Information of China (English)

    Kun Liu; Yanfu Wang; Zhijian Chen; Yuhua Liao; Xiang Gao; Jian Chen

    2008-01-01

    Objective:To study the role of nuclear factor-kappa B(NF- K B) in cholesterol efflux from THP-I derived-foam cells treated with Angiotensin Ⅱ (Ang Ⅱ ). Methods:Cultured THP-l derived-foam cells were treated with Ang Ⅱ or preincubated with tosyl-phenylalan inechloromethyl-ketone(TPCK) NF-K B inhibitor. The levels of activated NF-K B in the cells were examined by sandwich ELISA. Cellular cholesterol content was studied by electron microscopy scanning and zymochemistry via fluorospectrophotometer and cholesterol efflux was detected by scintillation counting technique. ABCAI mRNA and protein were quantified by RT-PCR and Western blotting. Results:Addition of TPCK to the cells before Ang Ⅱ stimulation attenuated the response of NF- K B p65 nuclear translocation induced by Ang Ⅱ and showed no peak in foam cells group and caused a reduction in cholesterol content and an increase in cholesterol effiux by 24.1%(P < 0.05) and 41.1%(P < 0.05) respectively, when compared with Ang Ⅱ group. In accordance, the ABCAl mRNA and protein were increased by 30% and 19%(P< 0.05) respectively, when compared with Ang Ⅱ group. Conclusion:Ang Ⅱ can down- regulate ABCAI in THP-l derived-foam cells via NF- K B, which leads to less cholesterol effiux and the increase of cholesterol content with the consequence of the promotion of atherosclerosis.

  16. Shape memory polymer foams

    Science.gov (United States)

    Santo, Loredana

    2016-02-01

    Recent advances in shape memory polymer (SMP) foam research are reviewed. The SMPs belong to a new class of smart polymers which can have interesting applications in microelectromechanical systems, actuators and biomedical devices. They can respond to specific external stimulus changing their configuration and then remember the original shape. In the form of foams, the shape memory behaviour can be enhanced because they generally have higher compressibility. Considering also the low weight, and recovery force, the SMP foams are expected to have great potential applications primarily in aerospace. This review highlights the recent progress in characterization, evaluation, and proposed applications of SMP foams mainly for aerospace applications.

  17. Operator Spin Foam Models

    CERN Document Server

    Bahr, Benjamin; Kamiński, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

    2010-01-01

    The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as the main tool. An equivalence relation we impose in the set of the operator spin foams allows to split the faces and the edges of the foams. The consistency with that relation requires introduction of the (familiar for the BF theory) face amplitude. The operator spin foam models are defined quite generally. Imposing a maximal symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with demanding consistency with splitting the edges, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on Spin(4) BF spin foam model is exactly the way we tend to view 4d quantum gravity, starting with the BC model and continuing with the EPRL or FK models. That makes...

  18. Toxicity evaluation and hazard review for Rigid Foam

    Energy Technology Data Exchange (ETDEWEB)

    Archuleta, M.M.; Stocum, W.E.

    1994-02-01

    Rigid Foam is a chemical delay foam used to completely encapsulate an object or to block access to an area. Prior studies have indicated that the final foam product is essentially non-toxic. The purpose of this study was to evaluate and summarize the current chemical and toxicological data available on the components of Rigid Foam and to update the information available on the toxicity of the final Rigid Foam product. Since the possibility exists for a partial deployment of Rigid Foam where only one of the components is released, this study also examined the toxicity of its chemical constituents. Rigid Foam is composed of an {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} Component. The {open_quotes}A{close_quotes} component is primarily a polymeric isocyanate and the {open_quotes}B{close_quotes} component is a mixture of polyols. In addition to the primary constituents, dichlorodifluoromethane and trichlorofluoromethane are present as blowing agents along with catalysts and silicone surfactants necessary for foaming. The pre-deployed {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} components are stored in separate vessels and are brought together in static mixing nozzles for dispersal. The results of this evaluation indicate that a completely deployed Rigid Foam under normal conditions is essentially non-toxic as determined previously. However, in the event of a partial deployment or deployment of an individual component directly at an unprotected individual, the degree of hazard is increased due to the toxic and corrosive nature of the individual constituents. The health hazard would depend on the properties of the material to which the person was exposed.

  19. A Method to Produce Foam Glasses

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a production process of foam glass from a mixture of glass cullet or slag or fly ash with a foaming agent and an oxidizing agent and heating to below 1100 C under low oxygen atmosphere. The invention relates more particularly to a process wherein pure carbon...... or a compound which yields pure carbon as the foaming agent is oxidized by a sufficient amount of an efficient oxidizing agent essentially added to the glass-carbon powder mixture, where the oxidizing agent supplies oxygen in the relevant temperature range, to release CO/CO2 gas mixture in the softened glass...... at elevated temperature, to form a foamed material with CO2 gas filled cells....

  20. Piezoresistive Foam Sensor Arrays for Marine Applications

    CERN Document Server

    Dusek, Jeff E; Lang, Jeffrey H

    2016-01-01

    Spatially-dense pressure measurements are needed on curved surfaces in marine environments to provide marine vehicles with the detailed, real-time measurements of the near-field flow necessary to improve performance through flow control. To address this challenge, a waterproof and conformal pressure sensor array comprising carbon black-doped-silicone closed-cell foam (CBPDMS foam) was developed for use in marine applications. The response of the CBPDMS foam sensor arrays was characterized using periodic hydrodynamic pressure stimuli from vertical plunging, from which a piecewise polynomial calibration was developed to describe the sensor response. Inspired by the distributed pressure and velocity sensing capabilities of the fish lateral line, the CBPDMS foam sensor arrays have significant advantages over existing commercial sensors for distributed flow reconstruction and control. Experimental results have shown the sensor arrays to have sensitivity on the order of 5 Pascal, dynamic range of 50-500 Pascal; are...

  1. Microcellular foams made from gliadin

    OpenAIRE

    Quester, S; Dahesh, M.; Strey, R.

    2014-01-01

    We have generated closed-cell microcellular foams from gliadin, an abundantly available wheat storage protein. The extraction procedure of gliadin from wheat gluten, which involves only the natural solvents water and ethanol, respectively, is described with emphasis on the precipitation step of gliadin which results in a fine dispersion of mostly spherical, submicron gliadin particles composed of myriad of protein molecules. A dense packing of these particles was hydrated and subjected to an ...

  2. Heat-Storage Modules Containing LiNO3-3H2O and Graphite Foam

    Science.gov (United States)

    Bootle, John

    2008-01-01

    A heat-storage module based on a commercial open-cell graphite foam (Poco-Foam or equivalent) imbued with lithium nitrate trihydrate (LiNO3-3H2O) has been developed as a prototype of other such modules for use as short-term heat sources or heat sinks in the temperature range of approximately 28 to 30 C. In this module, the LiNO3-3H2O serves as a phase-change heat-storage material and the graphite foam as thermally conductive filler for transferring heat to or from the phase-change material. In comparison with typical prior heat-storage modules in which paraffins are the phase-change materials and aluminum fins are the thermally conductive fillers, this module has more than twice the heat-storage capacity per unit volume.

  3. Evaluation of foaming polypropylene modified with ramified polymer

    Science.gov (United States)

    Demori, Renan; de Azeredo, Ana Paula; Liberman, Susana A.; Mauler, Raquel S.

    2015-05-01

    Polypropylene foams have great industrial interest because of balanced physical and mechanical properties, recyclability as well as low material cost. During the foaming process, the elongational forces applied to produce the expanded polymer are strong enough to rupture cell walls. As a result, final foam has a high amount of coalesced as well as opened cells which decreases mechanical and also physical properties. To increase melt strength and also avoid the coalescence effect, one of the current solution is blend PP with ramified polymers as well as branched polypropylene (LCBPP) or ethylene-octene copolymer (POE). In this research to provide extensional properties and achieve uniform cellular structures of expanded PP, 20 phr of LCBPP or POE was added into PP matrix. The blend of PP with ramified polymers was prepared by twin-screw extrusion. Injection molding process was used to produce PP foams using azodicarbonamide (ACA) as chemical blowing agent. The morphological results of the expanded PP displayed a non-uniform geometrical cell, apparent density of 0.48 g/cm3 and cell density of 13.9.104 cell/cm3. Otherwise, the expanded PP blended with LCBPP or POE displayed a homogeneous cell structure and increased the amount of smaller cells (50-100 μm of size). The apparent density slightly increased with addition of LCBPP or POE, 0.64 and 0.57 g/cm3, respectively. Thus, the cell density reduced to 65% in PP/LCBPP 100/20 and 75% in the sample PP/POE 100/20 compared to expanded PP. The thermo-mechanical properties (DMTA) of PP showed specific stiffness of 159 MPa.cm-3.g-1, while the sample PP/LCBPP 100/20 increased the stiffness values of 10%. Otherwise, the expanded PP/POE 100/20 decreased the specific stiffness values at -30%, in relation to expanded PP. In summary, blending PP with ramified polymers showed increasing of the homogenous cellular structure as well as the amount of smaller cells in the expanded material.

  4. Foam Glass for Construction Materials

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund

    2016-01-01

    Foaming is commonly achieved by adding foaming agents such as metal oxides or metal carbonates to glass powder. At elevated temperature, the glass melt becomes viscous and the foaming agents decompose or react to form gas, causing a foamy glass melt. Subsequent cooling to room temperature, result...... in a solid foam glass. The foam glass industry employs a range of different melt precursors and foaming agents. Recycle glass is key melt precursors. Many parameters influence the foaming process and optimising the foaming conditions is very time consuming. The most challenging and attractive goal is to make...... low density foam glass for thermal insulation applications. In this thesis, it is argued that the use of metal carbonates as foaming agents is not suitable for low density foam glass. A reaction mechanism is proposed to justify this result. Furthermore, an in situ method is developed to optimise...

  5. Foaming in membrane bioreactors: identification of the causes.

    Science.gov (United States)

    Di Bella, Gaetano; Torregrossa, Michele

    2013-10-15

    Membrane bioreactors (MBRs) represent by now a well established alternative for wastewater treatment. Their increasing development is undoubtedly related to the several advantages that such technology is able to guarantee. Nevertheless, this technology is not exempt from operational problems; among them the foaming still represents an "open challenge" of the MBR field, due to the high complexity of phenomenon. Unfortunately, very little work has been done on the foaming in MBRs and further studies are required. Actually, there is not a distinct difference between conventional activated system and MBR: the main difference is that the MBR plants can retain most Extracellular Polymeric Substances (EPSs) in the bioreactor. For these reason, unlike conventional activated sludge systems, MBRs have experienced foaming in the absence of foam-forming micro-organisms. Nevertheless, the actual mechanisms of EPS production and the role of bacteria in producing foam in activated sludge in MBRs are still unclear. In this paper, the authors investigated the roles of EPS and foam-forming filamentous bacteria by analyzing samples from different pilot plants using MBRs. In particular, in order to define the macroscopic features and the role of EPS and filamentous bacteria, a Modified Scum Index (MSI) test was applied and proposed. Based on the MSI and the foam power test, the causes of biological foaming were identified in terms of the potential for foaming, the quality and the quantity of the foam. The results indicated that the MBR foaming was influenced significantly by the concentration of bound EPSs in the sludge. In addition, the quantity and stability of MBR scum increased when both bound EPSs and foam-forming filamentous bacteria were present in the activated sludge.

  6. Vegetable-origin foam employed in dye extraction in tanning and leather processing facilities

    Directory of Open Access Journals (Sweden)

    José M. Cangemi

    2009-01-01

    Full Text Available This study addressed the use of conventional and vegetable origin polyurethane foams to extract C. I. Acid Orange 61 dye. The quantitative determination of the residual dye was carried out with an UV/Vis absorption spectrophotometer. The extraction of the dye was found to depend on various factors such as pH of the solution, foam cell structure, contact time and dye and foam interactions. After 45 days, better results were obtained for conventional foam when compared to vegetable foam. Despite presenting a lower percentage of extraction, vegetable foam is advantageous as it is considered a polymer with biodegradable characteristics.

  7. Beer foam physics

    NARCIS (Netherlands)

    Ronteltap, A.D.

    1989-01-01

    The physical aspects of beer foam behavior were studied in terms of the four physical processes, mainly involved in the formation and breakdown of foam. These processes are, bubble formation, drainage, disproportionation and coalescence. In detail, the processes disproportionation and

  8. Beer foam physics.

    NARCIS (Netherlands)

    Ronteltap, L.

    1989-01-01

    The physical aspects of beer foam behavior were studied in terms of the four physical processes, mainly involved in the formation and breakdown of foam. These processes are, bubble formation, drainage, disproportionation and coalescence. In detail, the processes disproportionation and coalescence we

  9. Metal foams: A survey

    Institute of Scientific and Technical Information of China (English)

    Michael; F.; Ashby; LU; Tianjian(卢天健)

    2003-01-01

    The current state-of-the-art in the development of cellular metal foams is reviewed, with focus on their fabrication, mechanical/thermal/acoustic properties, and potential applications as lightweight panels, energy absorbers, heat exchangers, and acoustic liners. Foam property charts with scaling relations are presented, allowing scoping and selection through the use of material indices.

  10. Macrophage specific overexpression of the human macrophage scavenger receptor in transgenic mice, using a 180-kb yeast artificial chromosome, leads to enhanced foam cell formation of isolated peritoneal macrophages

    NARCIS (Netherlands)

    Winther, M.P.J. de; Dijk, K.W. van; Vlijmen, B.J.M. van; Gijbels, M.J.J.; Heus, J.J.; Wijers, E.R.; Bos, A.C. van den; Breuer, M.; Frants, R.R.; Havekes, L.M.; Hofker, M.H.

    1999-01-01

    Macrophage scavenger receptors class A (MSR) are thought to play an important role in atherogenesis by mediating the unrestricted uptake of modified lipoproteins by macrophages in the vessel wall leading to foam cell formation. To investigate the in vivo role of the MSR in this process, a transgenic

  11. Investigation into stress wave propagation in metal foams

    Directory of Open Access Journals (Sweden)

    Li Lang

    2015-01-01

    Full Text Available The aim of this study is to investigate stress wave propagation in metal foams under high-speed impact loading. Three-dimensional Voronoi model is established to represent real closed-cell foam. Based on the one-dimensional stress wave theory and Voronoi model, a numerical model is developed to calculate the velocity of elastic wave and shock wave in metal foam. The effects of impact velocity and relative density of metal foam on the stress wave propagation in metal foams are explored respectively. The results show that both elastic wave and shock wave propagate faster in metal foams with larger relative density; with increasing the impact velocity, the shock wave propagation velocity increase, but the elastic wave propagation is not sensitive to the impact velocity.

  12. Modeling of metal foaming with lattice Boltzmann automata

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, C.; Thies, M.; Singer, R.F. [WTM Institute, Department of Materials Science, University of Erlangen, Martensstrasse 5, D-91058 Erlangen (Germany)

    2002-10-01

    The formation and decay of foams produced by gas bubble expansion in a molten metal is numerically simulated with the Lattice Boltzmann Method (LBM) which belongs to the cellular automaton techniques. The present state of the two dimensional model allows the investigation of the foam evolution process comprising bubble expansion, bubble coalescence, drainage, and eventually foam collapse. Examples demonstrate the influence of the surface tension, viscosity and gravity on the foaming process and the resulting cell structure. In addition, the potential of the LBM to solve problems with complex boundary conditions is illustrated by means of a foam developing within the constraints of a mould as well as a foaming droplet exposed to gravity. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  13. An Unusual Complication of Foam Sclerotherapy: Acute Kidney Injury

    Directory of Open Access Journals (Sweden)

    Müge EREK

    2014-09-01

    Full Text Available Sclerotherapy, in which an irritant solution is administered, is a method used to treat venous failure that results in complete venous destruction due to endothelial reaction and fibrosis. In recent years, foam sclerotherapy, in which a sclerosing agent (aethyl sclerole and air are mixed until they turn into foam and the resultant mixture is injected into noticeable veins directly and into other veins under ultrasonography in doses depending on the diameters of the varices, has been introduced. The drugs or gases used in foam sclerotherapy can cause local or systemic complications. Foam affects vessel endothelial cells and causes severe spasm in the vessel. It has been reported that endothelin-1 levels are high after foam sclerotherapy compared to the initial levels and that neurological complications vary with the endothelin levels. In this report, we present a case of acute kidney injury due to acute tubular necrosis probably caused by endothelin release following foam sclerotherapy.

  14. 闭孔泡沫Zn-22Al在单轴准静态加载下的压缩行为%Compressive behavior of Zn-22Al closed-cell foams under uniaxial quasi-static loading

    Institute of Scientific and Technical Information of China (English)

    A. HEYDARI ASTARAIE; H. R. SHAHVERDI; S. H. ELAHI

    2015-01-01

    通过使用氢化物发泡剂,采用熔体发泡法制备闭孔泡沫Zn−Al合金,在准静态条件下研究其压缩性能。在压缩试样过程中,分析发泡材料的结构,并研究其形态和压缩性能之间的关系。结果表明,应力−应变行为具有典型的闭孔泡沫金属和脆性泡沫金属的特征;在平稳阶段的控制变形机制是脆性破碎;泡沫Zn−22Al合金的抗压强度得到了显著提高,其压缩性能符合Gibson−Ashby模型。%Zn−22Al alloy closed-cell foams were fabricated by melt foaming process using hydride foaming agent. The compressive properties were investigated under quasi-static condition. The structure of the foamed material was analyzed during compression test to reveal the relationship between morphology and compressive behavior. The results show that the stress−strain behavior is typical of closed-cell metal foams and mostly of brittle type. Governing deformation mechanism at plateau stage is identified to be brittle crushing. A substantial increase in compressive strength of Zn−22Al foams was obtained. The agreement between compressive properties and Gibson−Ashby model was also detected.

  15. Enhanced foaming of cellular metals by internal stress superplasticity

    Energy Technology Data Exchange (ETDEWEB)

    Kitazono, K.; Sato, E.; Kuribayashi, K. [The Inst. of Space and Astronautical Science, Kanagawa (Japan)

    2004-07-01

    Effects of internal stress superplasticity on solid-state foaming process were examined using Al-8.69Si alloy and pure zinc compacts produced by the powder metallurgical (P/M) route. Isothermal and thermal cycling compression creep behaviors revealed that composite CTE (coefficient of thermal expansion)-mismatch superplasticity was induced in P/M Al-Si alloy, however, no difference was shown in the solid-state foaming. On the other hand, the foaming rate of P/M zinc was enhanced by anisotropic CTE-mismatch superplasticity. The cell morphology of the foamed zinc has anisotropy due to the original powder compact produced by hot-extrusion. (orig.)

  16. Development of Alcoa aluminum foam products

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, J.D.; Crowley, M.D.; Wang, W.; Wilhelmy, D.M.; Hunter, D.E. [Alcoa Technical Center, Alcoa Center, PA (United States)

    2007-07-01

    A new lightweight aluminum foam product was described. The foam was made through the controlled decomposition of carbonate powders within molten aluminum and was able to resist both coalescence and drainage. The fine-celled aluminum foam derived its physical and mechanical properties from the properties of the aluminum alloy matrix from which they were produced. The rheology of the molten aluminum was modified to provide a superior mesostructure. Stabilization was achieved by creating a solid-gas-liquid suspension initiated by the addition of carbonates into an aluminum alloy melt. A cascade of chemical reactions then occurred within the melt to create a foamable suspension. Carbon monoxide (CO) was generated to initiate an additional sequence of chemical reactions which resulted in the formation of solid particles within the liquid metal. CO reacted with liquid Al to form graphite. The graphite then reacted with Al to form aluminum carbide (Al{sub 4}C{sub 3}). The microstructural, mesostructural, and mechanical character of the foams produced under different processing conditions were examined. Details of experimental test procedures were also described. It was concluded that the specific crush energy absorption was as high as 20 kJ/kg. The foam exhibited a bending stiffness that was approximately 20 to 30 times higher than balsa and polymer foams. 14 refs., 2 tabs., 7 figs.

  17. Injectable silk foams for soft tissue regeneration.

    Science.gov (United States)

    Bellas, Evangelia; Lo, Tim J; Fournier, Eric P; Brown, Joseph E; Abbott, Rosalyn D; Gil, Eun S; Marra, Kacey G; Rubin, J Peter; Leisk, Gary G; Kaplan, David L

    2015-02-18

    Soft tissue fillers are needed for restoration of a defect or augmentation of existing tissues. Autografts and lipotransfer have been under study for soft tissue reconstruction but yield inconsistent results, often with considerable resorption of the grafted tissue. A minimally invasive procedure would reduce scarring and recovery time as well as allow the implant and/or grafted tissue to be placed closer to existing vasculature. Here, the feasibility of an injectable silk foam for soft tissue regeneration is demonstrated. Adipose-derived stem cells survive and migrate through the foam over a 10-d period in vitro. The silk foams are also successfully injected into the subcutaneous space in a rat and over a 3-month period integrating with the surrounding native tissue. The injected foams are palpable and soft to the touch through the skin and returning to their original dimensions after pressure is applied and then released. The foams readily absorb lipoaspirate making the foams useful as a scaffold or template for existing soft tissue filler technologies, useful either as a biomaterial alone or in combination with the lipoaspirate.

  18. Heat shock protein-27 attenuates foam cell formation and atherogenesis by down-regulating scavenger receptor-A expression via NF-κB signaling.

    Science.gov (United States)

    Raizman, Joshua E; Chen, Yong-Xiang; Seibert, Tara; Hibbert, Benjamin; Cuerrier, Charles M; Salari, Samira; Zhao, Xiaoling; Hu, Tieqiang; Shi, Chunhua; Ma, Xiaoli; Simard, Trevor; Caravaggio, Justin; Rayner, Katey; Bowdish, Dawn; Moore, Kathryn; O'Brien, Edward R

    2013-12-01

    Previously, we showed an inverse correlation between HSP27 serum levels and experimental atherogenesis in ApoE(-/-) mice that over-express HSP27 and speculated that the apparent binding of HSP27 to scavenger receptor-A (SR-A) was of mechanistic importance in attenuating foam cell formation. However, the nature and importance of the interplay between HSP27 and SR-A in atheroprotection remained unclear. Treatment of THP-1 macrophages with recombinant HSP27 (rHSP27) inhibited acLDL binding (-34%; p<0.005) and uptake (-38%, p<0.05). rHSP27 reduced SR-A mRNA (-39%, p=0.02), total protein (-56%, p=0.01) and cell surface (-53%, p<0.001) expression. The reduction in SR-A expression by rHSP27 was associated with a 4-fold increase in nuclear factor-kappa B (NF-κB) signaling (p<0.001 versus control), while an inhibitor of NF-κB signaling, BAY11-7082, attenuated the negative effects of rHSP27 on both SR-A expression and lipid uptake. To determine if SR-A is required for HSP27 mediated atheroprotection in vivo, ApoE(-/-) and ApoE(-/-) SR-A(-/-) mice fed with a high fat diet were treated for 3weeks with rHSP25. Compared to controls, rHSP25 therapy reduced aortic en face and aortic sinus atherosclerotic lesion size in ApoE(-/-) mice by 39% and 36% (p<0.05), respectively, but not in ApoE(-/-)SR-A(-/-) mice. In conclusion, rHSP27 diminishes SR-A expression, resulting in attenuated foam cell formation in vitro. Regulation of SR-A by HSP27 may involve the participation of NF-κB signaling. Lastly, SR-A is required for HSP27-mediated atheroprotection in vivo.

  19. Toughening of phenolic foam

    Science.gov (United States)

    Shen, Hongbin

    2003-06-01

    Phenolic foam has excellent FST performance with relatively low cost, and thus is an attractive material for many applications. However, it is extremely brittle and fragile, precluding it from load-bearing applications. In order to make it tougher and more viable for structural purposes, an effective approach has been proposed and investigated in this study. Composite phenolic foam with short fiber reinforcements resulted in significant improvement in mechanical performance while retaining FST properties comparable to conventional phenolic foam. For example, composite phenolic foam with aramid fibers exhibited a seven-fold increase in peel resistance together with a five-fold reduction in friability. In shear tests, aramid composite foam endured prolonged loading to high levels of strain, indicating the potential for use in structural applications. On the other hand, glass fiber-reinforced phenolic foam produced substantial improvement in the stiffness and strength relative to the unreinforced counterpart. In particular, the Young's modulus of the glass fiber composite foam was increased by as much as 100% relative to the plain phenolic foam in the foam rise direction. In addition, different mechanical behavior was observed for aramid and glass fiber-reinforced foams. In an attempt to understand the mechanical behavior of composite foam, a novel NDT technique, micro-CT, was used to acquire information on fiber length distribution (FLD) and fiber orientation distribution (FOD). Results from micro-CT measurements were compared with theoretical distribution models, achieving various degrees of agreement. Despite some limitations of current micro-CT technology, the realistic observation and measurement of cellular morphology and fiber distribution within composite foams portend future advances in modeling of reinforced polymer foam. To explain the discrepancy observed in shear stiffness between traditional shear test results and those by the short sandwich beam test, a

  20. Cell sample - Open TG-GATEs | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available [ Credits ] BLAST Search Image Search Home About Archive Update History Contact us ...: open_tggates_cell.zip File URL: ftp://ftp.biosciencedbc.jp/archive/open-tggates...ase Description Download License Update History of This Database Site Policy | Contact Us Cell sample - Open TG-GATEs | LSDB Archive ...

  1. Novel foaming agent used in preparation process of aluminum foams

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The performances of a novel foaming agent used in the preparation process of aluminum foams were investigated,and the effects of some factors,such as addition of the foaming agent,foaming temperature on the porosity,and appearance of aluminum foams were also discussed.Experimental results show that the novel foaming agent has a wide decomposition temperature range and a mild decomposed rate; the foaming agent has the ability to enhance the viscosity of aluminum melt,as a result,an extra viscosifier such as Ca or SiCp is unnecessary while using this foaming agent; the bubble-free zone in material decreases and the foaming efficiency increases with the increase of foaming agent; the bubble-free zone disappears and the foaming efficiency is near 100% when the addition of foaming agent is more than 1.4wt% ; the porosity of the aluminum foam increases with the increase of foaming agent when the addition of foaming agent is less than 2.2wt% .

  2. The effect of processing variables on morphological and mechanical properties of supercritical CO2 foamed scaffolds for tissue engineering.

    Science.gov (United States)

    White, Lisa J; Hutter, Victoria; Tai, Hongyun; Howdle, Steven M; Shakesheff, Kevin M

    2012-01-01

    The porous structure of a scaffold determines the ability of bone to regenerate within this environment. In situations where the scaffold is required to provide mechanical function, balance must be achieved between optimizing porosity and maximizing mechanical strength. Supercritical CO(2) foaming can produce open-cell, interconnected structures in a low-temperature, solvent-free process. In this work, we report on foams of varying structural and mechanical properties fabricated from different molecular weights of poly(DL-lactic acid) P(DL)LA (57, 25 and 15 kDa) and by varying the depressurization rate. Rapid depressurization rates produced scaffolds with homogeneous pore distributions and some closed pores. Decreasing the depressurization rate produced scaffolds with wider pore size distributions and larger, more interconnected pores. In compressive testing, scaffolds produced from 57 kDa P(DL)LA exhibited typical stress-strain curves for elastomeric open-cell foams whereas scaffolds fabricated from 25 and 15 kDa P(DL)LA behaved as brittle foams. The structural and mechanical properties of scaffolds produced from 57 kDa P(DL)LA by scCO(2) ensure that these scaffolds are suitable for potential applications in bone tissue engineering.

  3. Properties of baked foams from citric acid modified cassava starch and native cassava starch blends.

    Science.gov (United States)

    Pornsuksomboon, Kanlaya; Holló, Berta Barta; Szécsényi, Katalin Mészáros; Kaewtatip, Kaewta

    2016-01-20

    Starch foams from native cassava starch (NS) and citric acid modified cassava starch (CNS) were prepared using baking processes with blend ratios of 80/20, 60/40, 50/50, 40/60 and 20/80. The density, thickness, morphology, thermal stability and water absorption of the NS, CNS and blended starch foams were determined. The ratio of the two starch components had a significant influence on the density and thickness of the blended starch foams. All blended starch foams showed good water resistance. Moreover, the morphology of the blended starch foam with the NS/CNS ratio of 50/50 showed a more ordered distribution of cell sizes with thicker cell walls than for the NS and CNS foams. The thermal stability of the blended starch foams was somewhat lower than the stability of the NS foam but not to the extent that it affected any potential practical applications.

  4. Electrodeposition of palladium on carbon nanotubes modified nickel foam as an efficient electrocatalyst towards hydrogen peroxide reduction

    Science.gov (United States)

    Yang, Fan; Cao, Bo; Tao, Yue; Hu, Miao; Feng, Chengcheng; Wang, Lei; Jiang, Zhao; Cao, Dianxue; Zhang, Ying

    2015-12-01

    In this article, a three-dimensional electrode (Pd-CNT/Ni foam) based on Pd nanoparticles and carbon nanotubes (CNTs) is successfully developed by a simple "dipping and drying" process and a potentiostatic deposition technology for H2O2 reduction in base medium. The composition and structure of Pd-CNT/Ni foam electrode are examined by X-ray diffractometer, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, respectively. The cyclic voltammetry (CV) and chronoamperometry (CA) techniques are applied to determine the electrochemical performance. The electrode exhibits a high catalytic activity for H2O2 electroreduction, and it outperforms Pd/Ni foam electrode without CNT coating. At the reduction potential of -0.8 V, the reduction currents on Pd-CNT/Ni foam electrode can reach 323 mA cm-2, however, it is only 192 mA cm-2 on Pd/Ni foam electrode, which is increased by 68.2%. The impressive electrocatalytic performance is largely attributed to the superior open structure and high electronic conductivity, which allows the high utilization of Pd surfaces and makes the electrode have higher electrochemical activity. These findings may provide the opportunity on preparing binder-free carbon-supported electrode in the application of fuel cells.

  5. Visualization of the Crystallization in Foam Extrusion Process

    Science.gov (United States)

    Tabatabaei Naeini, Alireza

    In this study, crystal formation of polypropylene (PP) and poly lactic acid (PLA) in the presence of CO2 in foam extrusion process was investigated using a visualization chamber and a CCD camera. The role of pre-existing crystals on the foaming behavior of PP and PLA were studied by characterizing the foam morphology. Visualization results showed that crystals formed within the die before foaming and these crystals affect the cell nucleation behavior and expansion ratio of PP and PLA significantly. Due to the fast crystallization kinetics of PP, crystallinity should be optimum to achieve uniform cell structure with high cell density and high expansion ratio. In PLA, enhancement of crystallinity is crucial for getting foam with a high expansion ratio. It was also visualized that CO2 significantly suppresses the crystallization temperature in PP through the plasticization effect as well as its influence on flow induced crystallinity.

  6. Porous decellularized adipose tissue foams for soft tissue regeneration.

    Science.gov (United States)

    Yu, Claire; Bianco, Juares; Brown, Cody; Fuetterer, Lydia; Watkins, John F; Samani, Abbas; Flynn, Lauren E

    2013-04-01

    To design tissue-specific bioscaffolds with well-defined properties and 3-D architecture, methods were developed for preparing porous foams from enzyme-solubilized human decellularized adipose tissue (DAT). Additionally, a technique was established for fabricating "bead foams" comprised of interconnected networks of porous DAT beads fused through a controlled freeze-thawing and lyophilization procedure. In characterization studies, the foams were stable without the need for chemical crosslinking, with properties that could be tuned by controlling the protein concentration and freezing rate during synthesis. Adipogenic differentiation studies with human adipose-derived stem cells (ASCs) suggested that stiffness influenced ASC adipogenesis on the foams. In support of our previous work with DAT scaffolds and microcarriers, the DAT foams and bead foams strongly supported adipogenesis and were also adipo-inductive, as demonstrated by glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, endpoint RT-PCR analysis of adipogenic gene expression, and intracellular lipid accumulation. Adipogenic differentiation was enhanced on the microporous DAT foams, potentially due to increased cell-cell interactions in this group. In vivo assessment in a subcutaneous Wistar rat model demonstrated that the DAT bioscaffolds were well tolerated and integrated into the host tissues, supporting angiogenesis and adipogenesis. The DAT-based foams induced a strong angiogenic response, promoted inflammatory cell migration and gradually resorbed over the course of 12 weeks, demonstrating potential as scaffolds for wound healing and soft tissue regeneration.

  7. OpenCFU, a new free and open-source software to count cell colonies and other circular objects.

    Science.gov (United States)

    Geissmann, Quentin

    2013-01-01

    Counting circular objects such as cell colonies is an important source of information for biologists. Although this task is often time-consuming and subjective, it is still predominantly performed manually. The aim of the present work is to provide a new tool to enumerate circular objects from digital pictures and video streams. Here, I demonstrate that the created program, OpenCFU, is very robust, accurate and fast. In addition, it provides control over the processing parameters and is implemented in an intuitive and modern interface. OpenCFU is a cross-platform and open-source software freely available at http://opencfu.sourceforge.net.

  8. Supplementation with linoleic acid-rich soybean oil stimulates macrophage foam cell formation via increased oxidative stress and diacylglycerol acyltransferase1-mediated triglyceride biosynthesis.

    Science.gov (United States)

    Rom, Oren; Jeries, Helana; Hayek, Tony; Aviram, Michael

    2017-01-02

    During the last decades there has been a staggering rise in human consumption of soybean oil (SO) and its major polyunsaturated fatty acid linoleic acid (LA). The role of SO or LA in cardiovascular diseases is highly controversial, and their impact on macrophage foam cell formation, the hallmark of early atherogenesis, is unclear. To investigate the effects of high SO or LA intake on macrophage lipid metabolism and the related mechanisms of action, C57BL/6 mice were orally supplemented with increasing levels of SO-based emulsion or equivalent levels of purified LA for 1 month, followed by analyses of lipid accumulation and peroxidation in aortas, serum and in peritoneal macrophages (MPM) of the mice. Lipid peroxidation and triglyceride mass in aortas from SO or LA supplemented mice were dose-dependently and significantly increased. In MPM from SO or LA supplemented mice, lipid peroxides were significantly increased and a marked accumulation of cellular triglycerides was found in accordance with enhanced triglyceride biosynthesis rate and overexpression of diacylglycerol acyltransferase1 (DGAT1), the key enzyme in triglyceride biosynthesis. In cultured J774A.1 macrophages treated with SO or LA, triglyceride accumulated via increased oxidative stress and a p38 mitogen-activated protein kinase (MAPK)-mediated overexpression of DGAT1. Accordingly, anti-oxidants (pomegranate polyphenols), inhibition of p38 MAPK (by SB202190) or DGAT1 (by oleanolic acid), all significantly attenuated SO or LA-induced macrophage triglyceride accumulation. These findings reveal novel mechanisms by which supplementation with SO or LA stimulate macrophage foam cell formation, suggesting a pro-atherogenic role for overconsumption of SO or LA. © 2016 BioFactors, 43(1):100-116, 2017.

  9. Mechanical behavior of open-cell rhombic dodecahedron Ti–6Al–4V lattice structure

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lijun [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Song, Weidong, E-mail: swdgh@bit.edu.cn [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Wang, Cheng [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Liu, Haiyan; Tang, Huiping; Wang, Jianzhong [State Key Laboratory of Porous Metal Materials, Northwest Institute for Non-ferrous Metal Research, Xi’an 710016 (China)

    2015-07-29

    The compression behavior of Ti–6Al–4V lattice structure with a cell shape of rhombic dodecahedron, which was fabricated by electron beam melting, was investigated at different temperatures. A series of quasi-static compression tests were performed at ambient temperature, 200 °C, 400 °C and 600 °C with a strain rate of 10{sup −3} s{sup −1}. Two groups of design configurations were adopted by changing the cell size and thickness of struts with the sample size maintained unchanged. The results revealed that their properties varied with different cell sizes and temperatures. Larger cell size leaded to lower modulus and strength of the lattice. Higher temperatures resulted in lower strengths, modulus, densification strains and plateau stresses. The energy absorption of lattice at high temperature was discussed, and the experimental data were compared with aluminum foams, titanium foams and stainless steel lattice. It demonstrated that the rhombic dodecahedron Ti–6Al–4V lattice structure could be applied as load-bearing components and energy absorber at high temperature.

  10. OPEN

    DEFF Research Database (Denmark)

    Nickelsen, Anders; Paterno, Fabio; Grasselli, Agnese;

    2010-01-01

    One important aspect of ubiquitous environments is to provide users with the possibility to freely move about and continue to interact with the available applications through a variety of interactive devices such as cell phones, PDAs, desktop computers, intelligent watches or digital television...... and be controlled by the platform to enrich the user experience with the application. We describe the challenges following the centralisation of a migration platform that can support different types of applications, both games and business applications, implemented with either web-technologies or as component...

  11. Numerical study of metal foam heat sinks under uniform impinging flow

    Science.gov (United States)

    Andreozzi, A.; Bianco, N.; Iasiello, M.; Naso, V.

    2017-01-01

    The ever-increasing demand for performance improvement and miniaturization of electronics has led to a significant generation of waste heat that must be dissipated to ensure a reliable device operation. The miniaturization of the components complicates this task. In fact, reducing the heat transfer area, at the same required heat rate, it is necessary to increase the heat flux, so that the materials operate in a temperature range suitable to its proper functioning. Traditional heat sinks are no longer capable of dissipating the generated heat and innovative approaches are needed to address the emerging thermal management challenges. Recently, heat transfer in open-cell metal foams under an impinging jet has received attention due to the considerable heat transfer potential of combining two cooling technologies: impinging jet and porous medium. This paper presents a numerical study on Finned Metal Foam (FMF) and Metal Foam (MF) heat sinks under impinging air jet cooling. The analysis is carried out by means of the commercial software COMSOL Multiphysics®. The purpose is to analyze the thermal performance of the metal foam heat sink, finned or not, varying its geometric parameters. Results are presented in terms of predicted dissipated heat rate, convective heat transfer coefficient and pressure losses.

  12. High-Conductivity Graphite Foams for Thermal Control in Heavy Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, B. L.; McMillan, A. D.; A., Walls C.; Henry, J. J.; Sklad, P. S.

    2007-09-13

    A novel technique for creating pitch-based graphite foam was developed at Oak Ridge National Laboratory (ORNL), This technique utilizes mesophase pitch as a starting material but does not require the costly blowing or stabilization steps seen with typical carbon foams. The ORNL foam is an open-cell structure with highly aligned graphitic ligaments to be very near that of perfect graphite (0.3354 nm). As a result of its near-perfect structure, thermal conductivities along the ligament are calculated to be approximately 1700 W/m•K, with bulk conductivities {>=} 180 W/m•K. Furthermore, the material exhibits low densities (0.25-0.6 g/cm{sup 3} ) such that the specific thermal conductivity is approximcitely four to five times greater than that of copper. The very high surface area (20,000 m{sup 2}/m{sup 3}) combined with the high thermal conductivity suggests that graphite foam has significant potential for application as a thermal management material.

  13. Technology of foamed propellants

    Energy Technology Data Exchange (ETDEWEB)

    Boehnlein-Mauss, Jutta; Kroeber, Hartmut [Fraunhofer Institut fuer Chemische Technologie ICT, Pfinztal (Germany)

    2009-06-15

    Foamed propellants are based on crystalline explosives bonded in energetic reaction polymers. Due to their porous structures they are distinguished by high burning rates. Energy content and material characteristics can be varied by using different energetic fillers, energetic polymers and porous structures. Foamed charges can be produced easily by the reaction injection moulding process. For the manufacturing of foamed propellants a semi-continuous remote controlled production plant in pilot scale was set up and a modified reaction injection moulding process was applied. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  14. The foaming of lavas

    Science.gov (United States)

    Okeefe, J. A.; Walton, W.

    1976-01-01

    Foaming is of great practical and theoretical significance for volcanic processes on the earth, the moon, and perhaps the meteorite parent bodies. The theory of foams agrees with steelmaking experience to indicate that their presence depends on the existence of solutes in the lavas which reduce the surface tension, and are not saturated. These solutes concentrate at the surface, and are called surfactants. The surfactant responsible for the formation of volcanic ash was not identified; it appears to be related to the oxygen partial pressure above the lava. This fact may explain why lunar and meteoritic melts are not observed to foam. Experimental studies are needed to clarify the process.

  15. Micro flows in foams

    Science.gov (United States)

    Koehler, Stephan; Hilgenfeldt, Sascha; Stone, Howard; Weeks, Eric

    2002-11-01

    Foam drainage, the flow of liquid through foams, has been extensively studied macroscopically, on the scale of many bubbles. We use a confocal microscope to determine the flow-field in a single channel, and find good agreement with a model based upon surface rheology (R. A. Leonard and R. Lemlich, AIChE J. 11, p. 25-29 (1965)). The microscopic measurements show different types of flows depending on the type of surfactant used to stabilize the foam, which has also been observed on the macroscopic level. Surprisingly we find very little mixing in the nodes, the regions where four different channels intersect.

  16. Structural assessment of metal foam using combined NDE and FEA

    Science.gov (United States)

    Ghosn, Louis J.; Abdul-Aziz, Ali; Young, Philippe G.; Rauser, Richard W.

    2005-05-01

    Metal foams are expected to find use in structural applications where weight is of particular concern, such as space vehicles, rotorcraft blades, car bodies or portable electronic devices. The obvious structural application of metal foam is for light weight sandwich panels, made up of thin solid face sheets and a metallic foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by a light weight foam core. The resulting high-stiffness structure is lighter than that constructed only out of the solid metal material. Since the face sheets carry the applied in-plane and bending loads, the sandwich architecture is a viable engineering concept. However, the metal foam core must resist transverse shear loads and compressive loads while remaining integral with the face sheets. Challenges relating to the fabrication and testing of these metal foam panels remain due to some mechanical properties falling short of their theoretical potential. Theoretical mechanical properties are based on an idealized foam microstructure and assumed cell geometry. But the actual testing is performed on as fabricated foam microstructure. Hence in this study, a high fidelity finite element analysis is conducted on as fabricated metal foam microstructures, to compare the calculated mechanical properties with the idealized theory. The high fidelity geometric models for the FEA are generated using series of 2D CT scans of the foam structure to reconstruct the 3D metal foam geometry. The metal foam material is an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. Tensile, compressive, and shear mechanical properties are deduced from the FEA model and compared with the theoretical values. The combined NDE/FEA provided insight in the variability of the mechanical properties compared to idealized theory.

  17. A study on compressive shock wave propagation in metallic foams

    Science.gov (United States)

    Wang, Zhihua; Zhang, Yifen; Ren, Huilan; Zhao, Longmao

    2010-02-01

    Metallic foam can dissipate a large amount of energy due to its relatively long stress plateau, which makes it widely applicable in the design of structural crashworthiness. However, in some experimental studies, stress enhancement has been observed when the specimens are subjected to intense impact loads, leading to severe damage to the objects being protected. This paper studies this phenomenon on a 2D mass-spring-bar model. With the model, a constitutive relationship of metal foam and corresponding loading and unloading criteria are presented; a nonlinear kinematics equilibrium equation is derived, where an explicit integration algorithm is used to calculate the characteristic of the compressive shock wave propagation within the metallic foam; the effect of heterogeneous distribution of foam microstructures on the shock wave features is also included. The results reveal that under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, which then reduces the crush of objects. When the pulse is sufficiently high, on the other hand, stress enhancement may take place, especially in the heterogeneous foams, where high peak stresses usually occur. The characteristics of compressive shock wave propagation in the foam and the magnitude and location of the peak stress produced are strongly dependent on the mechanical properties of the foam material, amplitude and period of the pulse, as well as the homogeneity of the microstructures. This research provides valuable insight into the reliability of the metallic foams used as a protective structure.

  18. X-ray Measurements of Laser Irradiated Foam Filled Liners

    Science.gov (United States)

    Patankar, Siddharth; Mariscal, Derek; Goyon, Clement; Baker, Kevin; MacLaren, Stephan; Hammer, Jim; Baumann, Ted; Amendt, Peter; Menapace, Joseph; Berger, Bob; Afeyan, Bedros; Tabak, Max; Dixit, Sham; Kim, Sung Ho; Moody, John; Jones, Ogden

    2016-10-01

    Low-density foam liners are being investigated as sources of efficient x-rays. Understanding the laser-foam interaction is key to modeling and optimizing foam composition and density for x-ray production with reduced backscatter. We report on the experimental results of laser-irradiated foam liners filled with SiO2 and Ta2O5 foams at densities between 2 to 30mg/cc. The foam liners consist of polyimide tubes filled with low-density foams and sealed with a gold foil at one end. The open end of the tube is driven with 250J of 527nm laser light in a 2ns 2-step pulse using the Jupiter Laser Facility at LLNL. A full aperture backscatter system is used to diagnose the coupled energy and losses. A streaked x-ray camera and filtered x-ray pinhole cameras are used to measure laser penetration into the low-density foam for different mass densities. A HOPG crystal spectrometer is used to estimate a thermal electron temperature. Comparisons with beam propagation and x-ray emission simulations are presented. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, with funding support from the Laboratory Directed Research and Development Program under project 15.

  19. Mechanical Properties of a Metal Powder-Loaded Polyurethane Foam

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Neuschwanger; L. L. Whinnery; S. H. Goods

    1999-04-01

    Quasi-static compression tests have been performed on polyurethane foam specimens. The modulus of the foam exhibited a power-law dependence with respect to density of the form: E* {proportional_to} {rho}*{sup n}, where n = 1.7. The modulus data is well described by a simple geometric model (attributed to the work of Gibson and Ashby) for closed-cell foam in which the stiffness of the foam is governed by the flexure of the cell struts and cell walls. The compressive strength of the foam is also found to follow a power-law behavior with respect to foam density. In this instance, Euler buckling is used to rationalize the density dependence. The modulus of the polyurethane foam was modified by addition of a gas atomized, spherical aluminum powder. Additions of 30 and 50 weight percent of the powder significantly increased the foam modulus. However, there were only slight increases in modulus with 5 and 10 weight percent additions of the metal powder. Strength was also slightly increased at high loading fractions of powder. This increase in modulus and strength could be predicted by combining the above geometric model with a well-known model describing the effect on modulus of a rigid dispersoid in a compliant matrix.

  20. CARBONIZED STARCH MICROCELLULAR FOAM-CELLULOSE FIBER COMPOSITE STRUCTURES

    Directory of Open Access Journals (Sweden)

    Andrew R. Rutledge

    2008-11-01

    Full Text Available The production of microporous carbon foams from renewable starch microcellular foam-fiber (SMCF-Fiber composites is described. Carbon foams are used in applications such as thermal insulation, battery electrodes, filters, fuel cells, and medical devices. SMCF-Fiber compos-ites were created from an aquagel. The water in the aquagel was exchanged with ethanol and then dried and carbonized. Higher amylose content starches and fiber contents of up to 4% improved the processability of the foam. The SMCF structure revealed agglomerates of swollen starch granules connected by a web of starch with pores in the 50-200 nanometer range. Heating the SMCF-fiber in a nitrogen atmosphere to temperatures between 350-700˚C produced carbon foams with a three-dimensional closed cell foam structure with cell diameters around 50 microns and pore walls around 1-3 microns. The stress versus strain compression data for carbonized samples displayed a linear elastic region and a plateau indicative of brittle crushing, typical of an elastic-brittle foam. The carbon foam products from these renew-able precursors are promising carbon structures with moderate strength and low density.

  1. Mechanical Properties of a Metal Powder-Loaded Polyurethane Foam

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Neuschwanger; L. L. Whinnery; S. H. Goods

    1999-04-01

    Quasi-static compression tests have been performed on polyurethane foam specimens. The modulus of the foam exhibited a power-law dependence with respect to density of the form: E* {proportional_to} {rho}*{sup n}, where n = 1.7. The modulus data is well described by a simple geometric model (attributed to the work of Gibson and Ashby) for closed-cell foam in which the stiffness of the foam is governed by the flexure of the cell struts and cell walls. The compressive strength of the foam is also found to follow a power-law behavior with respect to foam density. In this instance, Euler buckling is used to rationalize the density dependence. The modulus of the polyurethane foam was modified by addition of a gas atomized, spherical aluminum powder. Additions of 30 and 50 weight percent of the powder significantly increased the foam modulus. However, there were only slight increases in modulus with 5 and 10 weight percent additions of the metal powder. Strength was also slightly increased at high loading fractions of powder. This increase in modulus and strength could be predicted by combining the above geometric model with a well-known model describing the effect on modulus of a rigid dispersoid in a compliant matrix.

  2. Foaming in stout beers

    OpenAIRE

    Lee, W. T.; M. G. Devereux

    2011-01-01

    We review the differences between bubble formation in champagne and other carbonated drinks, and stout beers which contain a mixture of dissolved nitrogen and carbon dioxide. The presence of dissolved nitrogen in stout beers gives them a number of properties of interest to connoisseurs and physicists. These remarkable properties come at a price: stout beers do not foam spontaneously and special technology, such as the widgets used in cans, is needed to promote foaming. Nevertheless the same m...

  3. Ultralight metal foams

    Science.gov (United States)

    Jiang, Bin; He, Chunnian; Zhao, Naiqin; Nash, Philip; Shi, Chunsheng; Wang, Zejun

    2015-09-01

    Ultralight (acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain ɛD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

  4. Polyurethane foam scaffold as in vitro model for breast cancer bone metastasis.

    Science.gov (United States)

    Angeloni, Valentina; Contessi, Nicola; De Marco, Cinzia; Bertoldi, Serena; Tanzi, Maria Cristina; Daidone, Maria Grazia; Farè, Silvia

    2017-09-18

    Breast cancer (BC) represents the most incident cancer case in women (29%), with high mortality rate. Bone metastasis occurs in 20-50% cases and, despite advances in BC research, the interactions between tumor cells and the metastatic microenvironment are still poorly understood. In vitro 3D models gained great interest in cancer research, thanks to the reproducibility, the 3D spatial cues and associated low costs, compared to in vivo and 2D in vitro models. In this study, we investigated the suitability of a poly-ether-urethane (PU) foam as 3D in vitro model to study the interactions between BC tumor-initiating cells and the bone microenvironment. PU foam open porosity (>70%) appeared suitable to mimic trabecular bone structure. The PU foam showed good mechanical properties under cyclic compression (E=69-109kPa), even if lower than human trabecular bone. The scaffold supported osteoblast SAOS-2 cell line proliferation, with no cytotoxic effects. Human adipose derived stem cells (ADSC) were cultured and differentiated into osteoblast lineage on the PU foam, as shown by alizarin red staining and RT-PCR, thus offering a bone biomimetic microenvironment to the further co-culture with BC derived tumor-initiating cells (MCFS). Tumor aggregates were observed after three weeks of co-culture by e-cadherin staining and SEM; modification in CaP distribution was identified by SEM-EDX and associated to the presence of tumor cells. In conclusion, we demonstrated the suitability of the PU foam to reproduce a bone biomimetic microenvironment, useful for the co-culture of human osteoblasts/BC tumor-initiating cells and to investigate their interaction. 3D in vitro models represent an outstanding alternative in the study of tumor metastases development, compared to traditional 2D in vitro cultures, which oversimplify the 3D tissue microenvironment, and in vivo studies, affected by low reproducibility and ethical issues. Several scaffold-based 3D in vitro models have been proposed

  5. Effects of strain rate and elevated temperature on compressive flow stress and absorbed energy of polyimide foam

    Directory of Open Access Journals (Sweden)

    Horikawa K.

    2012-08-01

    Full Text Available In this study, at first, the effect of strain rate on the strength and the absorbed energy of polyimide foam was experimentally examined by carrying out a series of compression tests at various strain rates, from 10−3 to 103 s−1. This polyimide foam has open cell structure with small cell size of 0.3 ∼ 0.6 mm. In the measurement of impact load, a special load cell with a small part for sensing load was adopted. For the measurement of the displacement, a high-speed camera was used. It was found that the flow stress of polyimide foam and the absorbed energy up to a strain of 0.4 increased with the increase of the strain rates. Secondly, the effect of ambient temperature on the strength and absorbed energy of polyimide foam was also investigated by using a sprit Hopkinson pressure bar apparatus and testing at elevated temperatures of 100 and 200 ∘C. With the increase of temperature, the strength and absorbed energy decreased and the effect is smaller in dynamic tests than static tests.

  6. Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily

    Energy Technology Data Exchange (ETDEWEB)

    Helene Hilger; James Oliver; Jean Bogner; David Jones

    2009-03-31

    Methane and carbon dioxide are formed in landfills as wastes degrade. Molecule-for-molecule, methane is about 20 times more potent than carbon dioxide at trapping heat in the earth's atmosphere, and thus, it is the methane emissions from landfills that are scrutinized. For example, if emissions composed of 60% methane and 40% carbon dioxide were changed to a mix that was 40% methane and 60% carbon dioxide, a 30% reduction in the landfill's global warming potential would result. A 10% methane, 90% carbon dioxide ratio will result in a 75% reduction in global warming potential compared to the baseline. Gas collection from a closed landfill can reduce emissions, and it is sometimes combined with a biocover, an engineered system where methane oxidizing bacteria living in a medium such as compost, convert landfill methane to carbon dioxide and water. Although methane oxidizing bacteria merely convert one greenhouse gas (methane) to another (carbon dioxide), this conversion can offer significant reductions in the overall greenhouse gas contribution, or global warming potential, associated with the landfill. What has not been addressed to date is the fact that methane can also escape from a landfill when the active cell is being filled with waste. Federal regulations require that newly deposited solid waste to be covered daily with a 6 in layer of soil or an alternative daily cover (ADC), such as a canvas tarp. The aim of this study was to assess the feasibility of immobilizing methane oxidizing bacteria into a tarp-like matrix that could be used for alternative daily cover at open landfill cells to prevent methane emissions. A unique method of isolating methanotrophs from landfill cover soil was used to create a liquid culture of mixed methanotrophs. A variety of prospective immobilization techniques were used to affix the bacteria in a tarp-like matrix. Both gel encapsulation of methanotrophs and gels with liquid cores containing methanotrophs were readily

  7. Foam used to drill, gravel-pack deep gas well

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, J.

    1984-05-07

    Surface-generated or preformed stable foam recently has been used as the circulating medium to drill-in and gravel-pack open hole completions along the Gulf Coast. With minor modifications to conventional tools and procedures, preformed stable foam is a viable alternative to current practices in completing underpressured reservoirs. Postproduction results indicate this is a cost-effective and reliable completion method.

  8. Prevascularization of a gas-foaming macroporous calcium phosphate cement scaffold via coculture of human umbilical vein endothelial cells and osteoblasts.

    Science.gov (United States)

    Thein-Han, WahWah; Xu, Hockin H K

    2013-08-01

    The lack of a vasculature in tissue-engineered constructs is currently a major challenge in tissue regeneration. There has been no report of prevascularization of macroporous calcium phosphate cement (CPC) via coculture of endothelial cells and osteoblasts. The objectives of this study were to (1) investigate coculture of human umbilical vein endothelial cells (HUVEC) and human osteoblasts (HOB) on macroporous CPC for the first time; and (2) develop a new microvasculature-CPC construct with angiogenic and osteogenic potential. A gas-foaming method was used to create macropores in CPC. HUVEC and HOB were seeded with a ratio of HUVEC:HOB=4:1, at 1.5×10(5) cells/scaffold. The constructs were cultured for up to 42 days. CPC with a porosity of 83% had a flexural strength (mean±SD; n=6) of 2.6±0.2 MPa, and an elastic modulus of 340±30 MPa, approaching the reported values for cancellous bone. Reverse transcription-polymerase chain reaction showed that HUVEC+HOB coculture on CPC had much higher vascular endothelial growth factor (VEGF) and collagen I expressions than monoculture (p<0.05). Osteogenic markers alkaline phosphatase, osteocalcin (OC), and runt-related transcription factor 2 (Runx2) were also highly elevated. Immunostaining of PECAM1 (CD31) showed abundant microcapillary-like structures on CPC in coculture at 42 days, as HUVEC self-assembled into extensive branches and net-like structures. However, no microcapillary was found on CPC in monoculture. In immunohistochemical staining, the neo-vessels were strongly positive for PECAM1, the von Willebrand factor, and collagen I. Scanning electron microscopy revealed microcapillary-like structures mingling with mineral nodules on CPC. Cell-synthesized minerals increased by an order of magnitude from 4 to 42 days. In conclusion, gas-foaming macroporous CPC was fabricated and HUVEC+HOB coculture was performed for prevascularization, yielding microcapillary-like structures on CPC for the first time. The novel

  9. Insights on the effective incorporation of a foam-based methanol reformer in a high temperature polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Avgouropoulos, George; Papavasiliou, Joan; Ioannides, Theophilos; Neophytides, Stylianos

    2015-11-01

    Highly active Al-doped CuMnOx catalyst supported on metallic copper foam was prepared via the combustion method and placed adjacent to the anode electrocatalyst of a high temperature PEM fuel cell operating at 200-210 °C. The addition of aluminum oxide in the catalyst composition enhanced the specific surface area (19.1 vs. 8.6 m2 g-1) and the reducibility of the Cu-Mn spinel oxide. Accordingly, the catalytic performance of CuMnOx was also improved. The doped sample is up to 2.5 times more active than the undoped sample at 200 °C, depending on the methanol concentration at the inlet, while CO selectivity is less than 0.8% in all cases. A membrane-electrode assembly comprising the ADVENT cross-linked TPS® high-temperature polymer electrolyte was integrated with the Cu-based methanol reformer in an Internal Reforming Methanol Fuel Cell (IRMFC). In order to avoid extensive poisoning of the reforming catalyst by H3PO4, a thin separation plate was placed between the reforming catalyst and the electrooxidation catalyst. Preliminary results obtained from a single-cell laboratory prototype demonstrated the improved functionality of the unit. Indeed, promising electrochemical performance was obtained during the first 24 h, during which the required H2 for achieving 580 mV at 0.2 A cm-2, was supplied from the reformer.

  10. Transport extraction for trace element separation and preconcentration. Pt. 3; Polyurethane foam sorbent supported transport extraction

    Energy Technology Data Exchange (ETDEWEB)

    Palagyi, S. (Inst. of Inorganic and Analytical Chemistry, Eoetvoes Univ., Budapest (Hungary)); Braun, T. (Inst. of Inorganic and Analytical Chemistry, Eoetvoes Univ., Budapest (Hungary))

    1994-01-01

    A new method of sorbent supported transport extraction based on the use of open-cell polyurethane foam sorbents in solvent sublation separation has been developed. The method has been shown to be effective for the separation and preconcentration of radioiodine and/or stable iodine from 4 l of deionized, drinking (tap) and surface (river) waters using N-cetylpyridinium chloride as the cationic surfactant and N[sub 2] carrier gas as the bubbling medium. A transport extraction efficiency of about 94% was obtained in 60 to 90 min; a 300-fold preconcentration was found for radioiodine as measured by direct radioactivity counting. Both radioiodine and stable iodine can be back-extracted from the polyurethane foam support (e.g. into acetone with an efficiency of almost 95%). (orig.)

  11. Sound absorption property of openpore aluminum foams

    Directory of Open Access Journals (Sweden)

    WANG Fang

    2007-02-01

    Full Text Available This paper presents a study on sound absorption property of aluminum foam by evaluating its sound absorption coefficients using standing wave tube method. Experimental results showed that the average values of sound absorption coefficients (over the test frequency range are all above 0.4, which indicate very good sound absorption property of the aluminum foams. The sound absorption coefficient is affected by frequency and pore structure, and reaches its maximum value at around 1 000 Hz. With the increase of porosity and decrease of cell diameter, the sound absorption coefficient values increase.

  12. Three dimensional graphene foam supported platinum-ruthenium bimetallic nanocatalysts for direct methanol and direct ethanol fuel cell applications

    Science.gov (United States)

    Kung, Chih-Chien; Lin, Po-Yuan; Xue, Yuhua; Akolkar, Rohan; Dai, Liming; Yu, Xiong; Liu, Chung-Chiun

    2014-06-01

    A novel composite material of hierarchically structured platinum-ruthenium (PtRu) nanoparticles grown on large surface area three dimensional graphene foam (3D GF) is reported. 3D GF was incorporated with PtRu bimetallic nanoparticles as an electrochemical nanocatalyst for methanol and ethanol oxidation. PtRu/3D GF nanocatalyst showed a higher tolerance to poisoning by CO and exhibited improved catalytic activity for both methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). Cyclic voltammetry (CV) results and long-term cycling stability tests demonstrated that GF provided a promising platform for the development of electrochemical nanocatalysts. Specifically, PtRu/3D GF nanocatalyst showed excellent catalytic activity toward MOR and EOR compared with PtRu/Graphene (Commercial graphene), PtRu/C (Vulcan XC-72R carbon), and PtRu alone. The crystal size of PtRu on 3D GF was reduced to 3.5 nm and its active surface area was enhanced to 186.2 m2 g-1. Consequently, the MOR and EOR rates were nearly doubled on PtRu/3D GF compared to those on PtRu/Graphene.

  13. Alpha-linolenic acid increases cholesterol efflux in macrophage-derived foam cells by decreasing stearoyl CoA desaturase 1 expression: evidence for a farnesoid-X-receptor mechanism of action.

    Science.gov (United States)

    Zhang, Jun; Kris-Etherton, Penny M; Thompson, Jerry T; Hannon, Daniel B; Gillies, Peter J; Heuvel, John P Vanden

    2012-04-01

    Increased cholesterol efflux from macrophage-derived foam cells (MDFCs) is an important protective mechanism to decrease lipid load in the atherosclerotic plaque. Dietary alpha-linolenic acid (ALA), an omega-3 polyunsaturated fatty acid (PUFA), decreases circulating cholesterol, but its role in cholesterol efflux has not been extensively studied. Stearoyl CoA desaturase 1 (SCD1) is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids (MUFAs). Endogenous MUFAs are preferentially incorporated into triglycerides, phospholipids and cholesteryl ester, which are abundant in atherosclerotic plaque. This study investigated the mechanisms by which ALA regulated SCD1 and subsequent effect on cholesterol storage and transport in MDFCs. Small interfering RNA (siRNA) also was applied to modify SCD1 expression in foam cells. Alpha-linolenic acid treatment and SCD1 siRNA significantly decreased SCD1 expression in MDFCs. The reduction of SCD1 was accompanied with increased cholesterol efflux and decreased intracellular cholesterol storage within these cells. Alpha-linolenic acid activated the nuclear receptor farnesoid-X-receptor, which in turn increased its target gene small heterodimer partner (SHP) expression, and decreased liver-X-receptor dependent sterol regulatory element binding protein 1c transcription, ultimately resulting in repressed SCD1 expression. In conclusion, repression of SCD1 by ALA favorably increased cholesterol efflux and decreased cholesterol accumulation in foam cells. This may be one mechanism by which dietary omega-3 PUFAs promote atherosclerosis regression. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Plasmonic nanoshell synthesis in microfluidic composite foams.

    Science.gov (United States)

    Duraiswamy, Suhanya; Khan, Saif A

    2010-09-01

    The availability of robust, scalable, and automated nanoparticle manufacturing processes is crucial for the viability of emerging nanotechnologies. Metallic nanoparticles of diverse shape and composition are commonly manufactured by solution-phase colloidal chemistry methods, where rapid reaction kinetics and physical processes such as mixing are inextricably coupled, and scale-up often poses insurmountable problems. Here we present the first continuous flow process to synthesize thin gold "nanoshells" and "nanoislands" on colloidal silica surfaces, which are nanoparticle motifs of considerable interest in plasmonics-based applications. We assemble an ordered, flowing composite foam lattice in a simple microfluidic device, where the lattice cells are alternately aqueous drops containing reagents for nanoparticle synthesis or gas bubbles. Microfluidic foam generation enables precisely controlled reagent dispensing and mixing, and the ordered foam structure facilitates compartmentalized nanoparticle growth. This is a general method for aqueous colloidal synthesis, enabling continuous, inherently digital, scalable, and automated production processes for plasmonic nanomaterials.

  15. Hafnium carbide structural foams synthesized from polymer precursors

    Science.gov (United States)

    Fan, Haibo

    2005-11-01

    A study was conducted to investigate a new low cost approach to produce Hafnium Carbide (HfC) structural foams through the thermolysis and pyrolysis of polymer precursors. Hafnium carbide has a melting point of over 3900 °C, the highest melting point of any known binary alloy. HfC structural foams can be fabricated into high temperature components or used as a thermal insulation material. Current available methods for creating HfC structural foams are time consuming, expensive or the material produced lacks mechanical strength. The objectives of this research were to produce HfC foam through the thermolysis and pyrolysis of Hf containing polymer mixture, optimize the properties of the HfC foam, and develop a knowledge base of acceptable process parameters. With the proposed method, HfC foam was produced by mixing a hafnium containing Macromolecular Metal Complex (MMC) and carbon source polymers, followed by heat treating the mixture under vacuum. XRD analysis showed that the produced foam was largely composed of HfC, with small amounts of hafnium oxide. The foam total porosity was measured to be over 85%. The HfC lattice parameter was found to range from 0.4613 nm to 0.4647 nm. The HfC conversion mechanism was investigated using Residual Gas Analysis, where it was observed that polymer decomposition occurred from 80 through 550 °C and HfC conversion started around 1100 °C. The HfC foam mechanical properties and microstructure were improved by optimizing the process methods and parameters. The initial research yielded an HfC foam with a compression strength of 15.16 +/- 4.66 MPa and evenly distributed foam cells with diameter sizes up to 50 mum. Continued research showed that HfC foams with total porosity of about 85% (density 1.9g/cm 3), and a foam compression strength of 212 +/- 25MPa were achievable. The proposed methodology for synthesizing HfC foam was found to be simple, inexpensive and require less production time. The process can be controlled to produce

  16. Origin of Open-Circuit Voltage Loss in Polymer Solar Cells and Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Hyung Do; Yanagawa, Nayu; Shimazaki, Ai; Endo, Masaru; Wakamiya, Atsushi; Ohkita, Hideo; Benten, Hiroaki; Ito, Shinzaburo

    2017-06-14

    Herein, the open-circuit voltage (VOC) loss in both polymer solar cells and perovskite solar cells is quantitatively analyzed by measuring the temperature dependence of VOC to discuss the difference in the primary loss mechanism of VOC between them. As a result, the photon energy loss for polymer solar cells is in the range of about 0.7-1.4 eV, which is ascribed to temperature-independent and -dependent loss mechanisms, while that for perovskite solar cells is as small as about 0.5 eV, which is ascribed to a temperature-dependent loss mechanism. This difference is attributed to the different charge generation and recombination mechanisms between the two devices. The potential strategies for the improvement of VOC in both solar cells are further discussed on the basis of the experimental data.

  17. Nano-Aramid Fiber Reinforced Polyurethane Foam

    Science.gov (United States)

    Semmes, Edmund B.; Frances, Arnold

    2008-01-01

    Closed cell polyurethane and, particularly, polyisocyanurate foams are a large family of flexible and rigid products the result of a reactive two part process wherein a urethane based polyol is combined with a foaming or "blowing" agent to create a cellular solid at room temperature. The ratio of reactive components, the constituency of the base materials, temperature, humidity, molding, pouring, spraying and many other processing techniques vary greatly. However, there is no known process for incorporating reinforcing fibers small enough to be integrally dispersed within the cell walls resulting in superior final products. The key differentiating aspect from the current state of art resides in the many processing technologies to be fully developed from the novel concept of milled nano pulp aramid fibers and their enabling entanglement capability fully enclosed within the cell walls of these closed cell urethane foams. The authors present the results of research and development of reinforced foam processing, equipment development, strength characteristics and the evolution of its many applications.

  18. Mechanical properties and network structure of wheat gluten foams.

    Science.gov (United States)

    Blomfeldt, Thomas O J; Kuktaite, Ramune; Johansson, Eva; Hedenqvist, Mikael S

    2011-05-09

    This Article reports the influence of the protein network structure on the mechanical properties of foams produced from commercial wheat gluten using freeze-drying. Foams were produced from alkaline aqueous solutions at various gluten concentrations with or without glycerol, modified with bacterial cellulose nanosized fibers, or both. The results showed that 20 wt % glycerol was sufficient for plasticization, yielding foams with low modulus and high strain recovery. It was found that when fibers were mixed into the foams, a small but insignificant increase in elastic modulus was achieved, and the foam structure became more homogeneous. SEM indicated that the compatibility between the fibers and the matrix was good, with fibers acting as bridges in the cell walls. IR spectroscopy and SE-HPLC revealed a relatively low degree of aggregation, which was highest in the presence of glycerol. Confocal laser scanning microscopy revealed distinct differences in HMW-glutenin subunits and gliadin distributions for all of the different samples.

  19. Dielectric and Radiative Properties of Sea Foam at Microwave Frequencies: Conceptual Understanding of Foam Emissivity

    OpenAIRE

    Gaiser, Peter W.; Anguelova, Magdalena D.

    2012-01-01

    Foam fraction can be retrieved from space-based microwave radiometric data at frequencies from 1 to 37 GHz. The retrievals require modeling of ocean surface emissivity fully covered with sea foam. To model foam emissivity well, knowledge of foam properties, both mechanical and dielectric, is necessary because these control the radiative processes in foam. We present a physical description of foam dielectric properties obtained from the foam dielectric constant including foam skin depth; foam ...

  20. Effects of surfactants on the microstructure of porous ceramic scaffolds fabricated by foaming for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xi, E-mail: nano-sun@hotmail.com [College of Chemistry and Chemical Engineering, Central South University, Lushan Road South, Changsha, Hunan 410083 (China); Ruan Jianming [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083 (China); Chen Qiyuan [College of Chemistry and Chemical Engineering, Central South University, Lushan Road South, Changsha, Hunan 410083 (China)

    2009-06-03

    A porous scaffold comprising a {beta}-tricalcium phosphate matrix and bioactive glass powders was fabricated by foaming method and the effects of surfactants as foaming agent on microstructure of scaffolds were investigated. Foaming capacity and foam stability of different surfactants in water firstly were carried out to evaluate their foam properties. The porous structure and pore size distribution of the scaffolds were systematically characterized by scanning electron microscopy (SEM) and an optical microscopy connected to an image analyzer. The results showed that the foam stability of surfactant has more remarkable influence on their microstructure such as pore shape, size and interconnectivity than the foaming ability of one. Porous scaffolds fabricated using nonionic surfactant Tween 80 with large foam stability exhibited higher open and total porosities, and fully interconnected porous structure with a pore size of 750-850 {mu}m.

  1. Properties of Water Blown Rigid Polyurethane Foams with Different Functionality

    Institute of Scientific and Technical Information of China (English)

    LI Xiaobin; CAO Hongbin; ZHANG Yi

    2008-01-01

    Water blown rigid polyurethane foams with different functionality were prepared.The physical properties of rigid foams were measured with rotational viscometer(NDJ-1),universal testing machine(lnstron3365),scanning electron microscope(SEM)and differential scanning calorimeter(DSC).The results show that the viscosity of polyether polyol increases exponentially from 62 mPa s to 6 000 mPa s with theincrease of functionality from 2 to 5.6,respectively.The overall density of foam increases slightly from 31.7kg/m3 to 37.4 kg/m3 with increasing functionality while core density exhibited little difference.Compressive strength of foam shows the similar behavior with density except for 2-functional sample.At the same time,dimensional stability becomes better with increasing functionality except for 5.6-functional foam that has worse stability than 4.8-functional foam.From the SEM results,the functionality is not an important factor in determining distribution of cell size of foam.According to the results of thermal analysis,the glass transition temperature(T)shifts to a higher temperature from 128.9℃ to 166.3℃ for the 2 to 5.6 functional foam,respectively.

  2. Surfactant monitoring by foam generation

    Science.gov (United States)

    Mullen, Ken I.

    1997-01-01

    A device for monitoring the presence or absence of active surfactant or other surface active agents in a solution or flowing stream based on the formation of foam or bubbles is presented. The device detects the formation of foam with a light beam or conductivity measurement. The height or density of the foam can be correlated to the concentration of the active surfactant present.

  3. Reduction of atherosclerosis in cholesterol-fed rabbits and decrease of expressions of intracellular adhesion molecule-1 and vascular endothelial growth factor in foam cells by a water-soluble fraction of Polygonum multiflorum.

    Science.gov (United States)

    Yang, Peng-Yuan; Almofti, Mohamad Radwan; Lu, Ling; Kang, Hui; Zhang, Jing; Li, Tie-Jun; Rui, Yao-Cheng; Sun, Lian-Na; Chen, Wan-Sheng

    2005-11-01

    Polygonum multiflorum stilbeneglycoside (PMS) is a water-soluble fraction of Polygonum multiflorum Thunb., one of the most famous tonic traditional Chinese medicines, that has protective effects on the cardiovascular system. The purpose of the present study is to elucidate the effects of PMS on macrophage-derived foam cell functions and the reduction of severity of atherosclerosis in hypercholesterolemic New Zealand White (NZW) rabbits. NZW rabbits were fed for 12 weeks with a normal diet, a high cholesterol diet, or a high cholesterol diet associated with irrigation with different doses of PMS (25, 50, or 100 mg/kg). Treatment of NZW rabbits fed with high cholesterol diet with 100 mg/kg PMS attenuated the increase in plasma cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, and plasma triglyceride. Treatment with 50 and 100 mg/kg PMS caused 43% and 60% decrease in atherosclerotic lesioned area ratio to total surface area, respectively. In U937 foam cells, PMS could decrease the high expression of intercellular adhesion molecule (ICAM)-1 protein and the vascular endothelial growth factor (VEGF) protein levels in the medium induced by oxidized lipoprotein when analyzed by flow cytometry. The results proved that PMS is a powerful agent against atherosclerosis and that PMS action could possibly be through the inhibition of the expression of ICAM-1 and VEGF in foam cells.

  4. The large-scale digital cell analysis system: an open system for nonperturbing live cell imaging.

    Science.gov (United States)

    Davis, Paul J; Kosmacek, Elizabeth A; Sun, Yuansheng; Ianzini, Fiorenza; Mackey, Michael A

    2007-12-01

    The Large-Scale Digital Cell Analysis System (LSDCAS) was designed to provide a highly extensible open source live cell imaging system. Analysis of cell growth data has demonstrated a lack of perturbation in cells imaged using LSDCAS, through reference to cell growth data from cells growing in CO(2) incubators. LSDCAS consists of data acquisition, data management and data analysis software, and is currently a Core research facility at the Holden Comprehensive Cancer Center at the University of Iowa. Using LSDCAS analysis software, this report and others show that although phase-contrast imaging has no apparent effect on cell growth kinetics and viability, fluorescent image acquisition in the cell lines tested caused a measurable level of growth perturbation using LSDCAS. This report describes the current design of the system, reasons for the implemented design, and details its basic functionality. The LSDCAS software runs on the GNU/Linux operating system, and provides easy to use, graphical programs for data acquisition and quantitative analysis of cells imaged with phase-contrast or fluorescence microscopy (alone or in combination), and complete source code is freely available under the terms of the GNU Public Software License at the project website (http://lsdcas.engineering.uiowa.edu).

  5. Foaming in stout beers

    CERN Document Server

    Lee, W T

    2011-01-01

    We review the differences between bubble formation in champagne and other carbonated drinks, and stout beers which contain a mixture of dissolved nitrogen and carbon dioxide. The presence of dissolved nitrogen in stout beers gives them a number of properties of interest to connoisseurs and physicists. These remarkable properties come at a price: stout beers do not foam spontaneously and special technology, such as the widgets used in cans, is needed to promote foaming. Nevertheless the same mechanism, nucleation by gas pockets trapped in cellulose fibres, responsible for foaming in carbonated drinks is active in stout beers, but at an impractically slow rate. This gentle rate of bubble nucleation makes stout beers an excellent model system for the scientific investigation of the nucleation of gas bubbles. The equipment needed is very modest, putting such experiments within reach of undergraduate laboratories. Finally we consider the suggestion that a widget could be constructed by coating the inside of a beer...

  6. RANS Simulations using OpenFOAM Software

    Science.gov (United States)

    2016-01-01

    processor if the cluster is composed of processors providing unequal performance. If the cluster consists of a number of identical processors then the list...of weighting coefficients can be neglected and the user only has to specify the total number of processors in the cluster . The decomposition method

  7. Long lasting decontamination foam

    Science.gov (United States)

    Demmer, Ricky L.; Peterman, Dean R.; Tripp, Julia L.; Cooper, David C.; Wright, Karen E.

    2010-12-07

    Compositions and methods for decontaminating surfaces are disclosed. More specifically, compositions and methods for decontamination using a composition capable of generating a long lasting foam are disclosed. Compositions may include a surfactant and gelatin and have a pH of less than about 6. Such compositions may further include affinity-shifting chemicals. Methods may include decontaminating a contaminated surface with a composition or a foam that may include a surfactant and gelatin and have a pH of less than about 6.

  8. Mechanical properties and energy absorption capability of closed-cell Al foam under uniaxial compression%闭孔胞状泡沫铝的单向压缩力学性能和吸能能力

    Institute of Scientific and Technical Information of China (English)

    王展光; 蔡萍; 李书琴

    2012-01-01

    Based on the uniaxial compressive test of different porosity closed-cell Al foam, the effect of porosity on mechanical properties and energy absorption capacity were investigated. Compressive stress-strain curve of closed-cell Al foam consists of three distinct regions, which is the linear region, the collapse region and the densification region. The compressive strength and energy absorption capacity of closed-cell Al foam decrease with the increase of porosity. Analyzing the compressive yield stress by Gibson-Ashby model, formula on energy absorption capability of Al foam was presented, which could provide support for its engineering application.%通过不同孔隙度闭孔胞状泡沫铝的准静态压缩试验,研究泡沫铝孔隙度对其力学性能和吸能能力的影响.闭孔胞状泡沫铝单轴压缩应力应变曲线呈现明显的3个阶段:线性变形、平台阶段、致密化阶段;在单向压缩情况下,泡沫铝的压缩强度、吸能能力随着孔隙度的增大而减小;采用Gibson-Ashby的模型分析闭孔胞状泡沫铝的压缩屈服强度,并提出泡沫铝吸能能力公式,为工程应用提供理论支持.

  9. Production of lightweight foam glass (invited talk)

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    The foam glass production allows low cost recycling of postconsumer glass and industrial waste materials as foaming agent or as melt resource. Foam glass is commonly produced by utilising milled glass mixed with a foaming agent. The powder mixture is heat-treated to around 10^3.7 – 10^6 Pa s, which...... result in viscous sintering and subsequent foaming of the glass melt. The porous glass melt is cooled down to room temperature to freeze-in the foam structure. The resulting foam glass is applied in constructions as a light weight material to reduce load bearing capacity and as heat insulating material...... in buildings and industry. We foam panel glass from old televisions with different foaming agents. We discuss the foaming ability and the foaming mechanism of different foaming systems. We compare several studies to define a viscous window for preparing low density foam glass. However, preparing foam glass...

  10. Modeling Aerosol-Cloud Interactions in Marine Open- and Closed-Cell Stratocumulus

    Science.gov (United States)

    Wang, H.; Feingold, G.

    2008-12-01

    Satellite imagery shows the recurrence of striking images of cellular structures exhibiting both closed- and open-cell patterns in marine stratocumulus fields. The open-cell region has much lower cloud albedo than closed cells. Aside from that, previous observational and modeling studies have suggested that open- and closed-cell regions are different in many other aspects, such as concentration of cloud condensation nuclei (CCN), cloud droplet number and size, precipitation efficiency, and cloud dynamics. In this work, aerosol- cloud interactions and dynamical feedbacks are investigated within a large eddy simulation (LES) modeling framework to study the activation, cloud scavenging, mixing and transport of CCN in the open- and closed- cell boundary layer and near the open/closed-cell boundaries. The model domain size of 120 km by 60 km is large enough to represent mesoscale organizations that are associated with different cellular structures and that are promoted by CCN perturbation from ship emissions. Simulation results show that depletion of CCN by collision and coalescence in clouds is critical to the formation of precipitation and open-cell structure in a stratocumulus deck. Once the open cellular structure has formed in the clean environment, a substantial increase of CCN transported from a neighboring polluted environment or from ship emissions do not close it during the 12-hour simulation due to the lack of dynamical and moisture support in the open-cell cloud-free region. However, the contaminated open cells are not able to self-sustain as a result of shutoff of precipitation. This points to the critical role of precipitation-triggered circulations in maintaining an open-cellular structure.

  11. Materials Applications for Non-Lethal: Aqueous Foams

    Energy Technology Data Exchange (ETDEWEB)

    GOOLSBY,TOMMY D.; SCOTT,STEVEN H.

    1999-09-15

    High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In the mid-1990s, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate (foaming agent) with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objectives were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might

  12. Processing and Characterization of Nickel-Manganese-Gallium Shape-Memory Fibers and Foams

    Science.gov (United States)

    Zheng, Peiqi-Paige

    makes polycrystalline Ni-Mn-Ga metallic foams attractive for magnetic refrigeration. Compared to a polycrystalline bulk material, open-cells Ni-Mn-Ga foams shows a reduction in the temperature span of the phase transition and an increase in the magnetocaloric effect (MCE). Ni-Mn-Ga wires with sub-millimeter diameter, either as individual wires or as part of a 2D/3D wire assemblies, are promising candidates for actuators, sensors, magnetic cooling systems and energy harvesting devices. Here, we report the mechanical behavior of oligocrystalline Ni-Mn-Ga Taylor wires by tensile tests at room temperature. Magnetic-field induced shape recovery is demonstrated at 0°C in a martensitic Ni-Mn-Ga microwire, where a mechanically-produced 120° bend is recovered near fully within a magnetic field produced by permanent magnets. Tubes of the ferromagnetic shape-memory alloy Ni-Mn-Ga of composition near the Ni2MnGa Heusler phase can be used, alone or combined in structures, in magnetic actuators or magnetic refrigerators. However, fabrication of Ni-Mn-Ga tubes with sub-millimeter diameter by classical cold or hot drawing methods is hampered by the brittleness of the alloy. Here, we demonstrate a new process, where Ni-Mn-Ga tubes are fabricated by interdiffusion of Mn and Ga into drawn, ductile Ni tubes with 500 and 760 micrometers inner and outer diameters.

  13. Experimental Study of the Effectiveness of Sacrificial Cladding Using Polymeric Foams as Crushable Core with a Simply Supported Steel Beam

    Directory of Open Access Journals (Sweden)

    H. Ousji

    2016-01-01

    Full Text Available The present paper focuses on the study of the effectiveness of the sacrificial cladding using polymeric foam as crushable core to reduce the delivered blast energy using a simplified structure. The latter consists of a simply supported steel beam under a localized blast load. The tested sacrificial cladding has a cross-sectional area of 80 × 80 mm2. The effect of the front plate mass and the crushable core properties (plateau stress and thickness is studied. Three polymeric foams are investigated: (a the expanded polystyrene foam (PS13 with a density of 13 kg/m3, (b the closed-cell polyurethane (PU30 with a density of 30 kg/m3, and (c the open-cell polyurethane (PU50 with a density of 50 kg/m3. Four front plate masses are used: 144, 188, 336, and 495 g. All possible combinations are tested to determine their absorption capacity. The obtained results show that the absorption capability increases by increasing the front plate mass, the plateau stress, and the thickness of the crushable core. The open-cell polyurethane PU50 performs better. Disintegration problems are observed on the expanded polystyrene PS13 after the end of the compression process.

  14. 3D Printing Variable Stiffness Foams Using Viscous Thread Instability

    Science.gov (United States)

    Lipton, Jeffrey I.; Lipson, Hod

    2016-08-01

    Additive manufacturing of cellular structures has numerous applications ranging from fabrication of biological scaffolds and medical implants, to mechanical weight reduction and control over mechanical properties. Various additive manufacturing processes have been used to produce open regular cellular structures limited only by the resolution of the printer. These efforts have focused on printing explicitly designed cells or explicitly planning offsets between strands. Here we describe a technique for producing cellular structures implicitly by inducing viscous thread instability when extruding material. This process allows us to produce complex cellular structures at a scale that is finer than the native resolution of the printer. We demonstrate tunable effective elastic modulus and density that span two orders of magnitude. Fine grained cellular structures allow for fabrication of foams for use in a wide range of fields ranging from bioengineering, to robotics to food printing.

  15. Pd-Pt loaded graphene aerogel on nickel foam composite as binder-free anode for a direct glucose fuel cell unit

    Science.gov (United States)

    Tsang, Chi Him A.; Leung, D. Y. C.

    2017-09-01

    Fabrication of electrocatalyst for direct glucose fuel cell (DGFC) operation involves destructive preparation methods with the use of stabilizer like binder, which may cause activity depreciation. Binder-free electrocatalytic electrode becomes a possible solution to the above problem. Binder-free bimetallic Pd-Pt loaded graphene aerogel on nickel foam plates with different Pd/Pt ratios (1:2.32, 1:1.62, and 1:0.98) are successfully fabricated through a green one-step mild reduction process producing a Pd-Pt/GO/nickel form plate (NFP) composite. Anode with the binder-free electrocatalysts exhibit a strong activity in a batch type DGFC unit under room temperature. The effects of glucose and KOH concentrations, and the Pd/Pt ratios of the electrocatalyst on the DGFC performance are also studied. Maximum power density output of 1.25 mW cm-2 is recorded with 0.5 M glucose/3 M KOH as the anodic fuel, and Pd1Pt0.98/GA/NFP as catalyst, which is the highest obtained so far among other types of electrocatalyst.

  16. mFOAM-1.02: A compact version of the cellular event generator FOAM

    Science.gov (United States)

    Jadach, S.; Sawicki, P.

    2007-09-01

    system: Most UNIX systems, Linux and Windows. Application programs were thoroughly tested under Red Hat Linux 7.x, CERN Scientific Linux 3.02, Fedora Linux FC3, UNIX IRIX-6.5. At present mFOAM is distributed with the ROOT package (version 4.04 and later). RAM: Depends on the complexity of the problem. For the default 2000 cells it is about 25 MB while for 100,000 cells it allocates about 35 MB. These data are for running from CINT command line and include also memory consumption by CINT itself. Keywords: Monte Carlo (MC) simulation and generation, particle physics, phase space PACS: 02.70.Rr Classification: 4.14 Nature of problem: Monte Carlo integration or generation of unweighted (weight equals 1) events with a given probability distribution is a standard problem in many areas of research, ranging from high-energy physics to economics. In any library of general utilities it is highly desirable to include a general-purpose numerical tool (program) with the MC generation algorithm featuring the built-in capability of automatically adjusting the generation procedure to an arbitrary pattern of singularities in the generated distribution. Our primary goal is the simulation of the differential distribution in the multiparticle Lorentz-invariant phase space for the purpose of comparison between Quantum Field Theory predictions, and results of high-energy experiments. However, the solution may have a much wider area of applications. Solution method: In the algorithm, a grid of cells, called "foam", is built in the process of the binary split of the cells. The resulting foam is adapted automatically to the shape of the integrand in such a way that the resulting ratio of the average weight to maximum weight or the variance to average weight is minimized. Restrictions: Consumption of computer resources depends on the complexity of the problem. The use of the program is limited to about a million of cells for a relatively small number of dimensions (⩽20) in view of the memory

  17. Morphological Study of Directionally Freeze-Cast Nickel Foams

    Science.gov (United States)

    Jo, Hyungyung; Kim, Min Jeong; Choi, Hyelim; Sung, Yung-Eun; Choe, Heeman; Dunand, David C.

    2016-03-01

    Nickel foams, consisting of 51 to 62 pct aligned, elongated pores surrounded by a network of Ni walls, were fabricated by reduction and sintering of directionally cast suspensions of nanometric NiO powders in water. Use of dispersant in the slurry considerably affected the foam morphology and microstructure at both the micro- and macro-scale, most likely by modifying ice solidification into dendrites (creating the aligned, elongated macro-pores) and NiO powder accumulation in the inter-dendritic space (creating the Ni walls with micro-pores). The mean width of the Ni walls, in foams solidified with and wi