WorldWideScience

Sample records for engineered porous materials

  1. Tailored Porous Materials

    Energy Technology Data Exchange (ETDEWEB)

    BARTON,THOMAS J.; BULL,LUCY M.; KLEMPERER,WALTER G.; LOY,DOUGLAS A.; MCENANEY,BRIAN; MISONO,MAKOTO; MONSON,PETER A.; PEZ,GUIDO; SCHERER,GEORGE W.; VARTULI,JAMES C.; YAGHI,OMAR M.

    1999-11-09

    Tailoring of porous materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films and monoliths. These issues are addressed in the context of five specific classes of porous materials: oxide molecular sieves, porous coordination solids, porous carbons, sol-gel derived oxides, and porous heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.

  2. On strength of porous material

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1999-01-01

    The question of non-destructive testing of porous materials has always been of interest for the engineering profession. A number of empirically based MOE-MOR relations between stiffness (Modulus Of Elasticity) and strength (Modulus OF Rupture) of materials have been established in order to control...

  3. Porous material neutron detector

    Science.gov (United States)

    Diawara, Yacouba [Oak Ridge, TN; Kocsis, Menyhert [Venon, FR

    2012-04-10

    A neutron detector employs a porous material layer including pores between nanoparticles. The composition of the nanoparticles is selected to cause emission of electrons upon detection of a neutron. The nanoparticles have a maximum dimension that is in the range from 0.1 micron to 1 millimeter, and can be sintered with pores thereamongst. A passing radiation generates electrons at one or more nanoparticles, some of which are scattered into a pore and directed toward a direction opposite to the applied electrical field. These electrons travel through the pore and collide with additional nanoparticles, which generate more electrons. The electrons are amplified in a cascade reaction that occurs along the pores behind the initial detection point. An electron amplification device may be placed behind the porous material layer to further amplify the electrons exiting the porous material layer.

  4. Production of porous sintered materials using wastes of manufacturing engineering in self-propagating high-temperature synthesis

    Directory of Open Access Journals (Sweden)

    Y. S. Povstyana

    2016-06-01

    Full Text Available The increasing amount of wastes produced by the manufacturing engineering, as well as their physical and mechanical properties and restorability provide a search for sphere of their application. The actual problem of modern science is the utilization of wastes and using them in further production that will minimize their harmful impact on the environment and reduce the cost of expensive raw materials. Wastes are ideally suitable for the manufacture of porous permeable materials (filters. Powder metallurgy allows obtaining products with controlled filtration, physical and mechanical properties. Such materials are good filters for regeneration of technical liquids, oils, cooling fluids, sewage etc. The article analyzes the methods and technologies for the manufacture of porous ceramic materials and a new technology for their manufacture, which is based on use of mill scale and natural mineral – saponite as the main components. Compression technology provides products at low pressures and sintering by passing high-temperature synthesis. The proposed technology is characterized by low cost and good physical and mechanical properties of the product that gives a reason to use them for filtering and regeneration of technical liquids.

  5. Porous Silicon–Carbon Composite Materials Engineered by Simultaneous Alkaline Etching for High-Capacity Lithium Storage Anodes

    International Nuclear Information System (INIS)

    Sohn, Myungbeom; Kim, Dae Sik; Park, Hyeong-Il; Kim, Jae-Hun; Kim, Hansu

    2016-01-01

    Highlights: • A porous Si–C anode is obtained by alkaline etching of a non-porous Si–C composite. • The pores in the carbon frame are created by simultaneous etching of Si and carbon. • The cycle life is greatly improved after the alkaline treatment. • The porous Si–C composite electrode shows high dimensional stability during cycling. - Abstract: Porous silicon–carbon (Si–C) composite materials have attracted a great deal of attention as high-performance anode materials for Li-ion batteries (LIBs), but their use suffers from the complex and limited synthetic routes for their preparation. Herein we demonstrate a scalable and nontoxic method to synthesize porous Si–C composite materials by means of simultaneous chemical etching of Si and carbon phases using alkaline solution. The resulting porous Si–C composite material showed greatly improved cycle performance, good rate capability, and high dimensional stability during cycling. Porous Si–C electrode showed an expansion of the height by about 22% after the first lithiation and only 16% after the first cycle. The material synthesis concept and scalable simultaneous etching approach presented here represent a means of improving the electrochemical properties of Si-based porous anode materials for use in commercial LIBs.

  6. Optimized manufacturable porous materials

    DEFF Research Database (Denmark)

    Andreassen, Erik; Andreasen, Casper Schousboe; Jensen, Jakob Søndergaard

    Topology optimization has been used to design two-dimensional material structures with specific elastic properties, but optimized designs of three-dimensional material structures are more scarsely seen. Partly because it requires more computational power, and partly because it is a major challenge...... to include manufacturing constraints in the optimization. This work focuses on incorporating the manufacturability into the optimization procedure, allowing the resulting material structure to be manufactured directly using rapid manufacturing techniques, such as selective laser melting/sintering (SLM....../S). The available manufacturing methods are best suited for porous materials (one constituent and void), but the optimization procedure can easily include more constituents. The elasticity tensor is found from one unit cell using the homogenization method together with a standard finite element (FE) discretization...

  7. Porous titanium bases for osteochondral tissue engineering

    Science.gov (United States)

    Nover, Adam B.; Lee, Stephanie L.; Georgescu, Maria S.; Howard, Daniel R.; Saunders, Reuben A.; Yu, William T.; Klein, Robert W.; Napolitano, Anthony P.; Ateshian, Gerard A.

    2015-01-01

    Tissue engineering of osteochondral grafts may offer a cell-based alternative to native allografts, which are in short supply. Previous studies promote the fabrication of grafts consisting of a viable cell-seeded hydrogel integrated atop a porous, bone-like metal. Advantages of the manufacturing process have led to the evaluation of porous titanium as the bone-like base material. Here, porous titanium was shown to support the growth of cartilage to produce native levels of Young’s modulus, using a clinically relevant cell source. Mechanical and biochemical properties were similar or higher for the osteochondral constructs compared to chondral-only controls. Further investigation into the mechanical influence of the base on the composite material suggests that underlying pores may decrease interstitial fluid pressurization and applied strains, which may be overcome by alterations to the base structure. Future studies aim to optimize titanium-based tissue engineered osteochondral constructs to best match the structural architecture and strength of native grafts. Statement of Significance The studies described in this manuscript follow up on previous studies from our lab pertaining to the fabrication of osteochondral grafts that consist of a bone-like porous metal and a chondrocyte-seeded hydrogel. Here, tissue engineered osteochondral grafts were cultured to native stiffness using adult chondrocytes, a clinically relevant cell source, and a porous titanium base, a material currently used in clinical implants. This porous titanium is manufactured via selective laser melting, offering the advantages of precise control over shape, pore size, and orientation. Additionally, this manuscript describes the mechanical influence of the porous base, which may have applicability to porous bases derived from other materials. PMID:26320541

  8. Positronium chemistry in porous materials

    International Nuclear Information System (INIS)

    Kobayashi, Y.; Ito, K.; Oka, T.; Hirata, K.

    2007-01-01

    Porous materials have fascinated positron and positronium chemists for over decades. In the early 1970s it was already known that ortho-positronium (o-Ps) exhibits characteristic long lifetimes in silica gels, porous glass and zeolites. Since then, our understanding of Ps formation, diffusion and annihilation has been drastically deepened. Ps is now well recognized as a powerful porosimetric and chemical probe to study the average pore size, pore size distribution, pore connectivity and surface properties of various porous materials including thin films. In this paper, developments of Ps chemistry in porous materials undertaken in the past some 40 yr are surveyed and problems to be addressed in future are briefly discussed

  9. Constitutive model for porous materials

    International Nuclear Information System (INIS)

    Weston, A.M.; Lee, E.L.

    1982-01-01

    A simple pressure versus porosity compaction model is developed to calculate the response of granular porous bed materials to shock impact. The model provides a scheme for calculating compaction behavior when relatively limited material data are available. While the model was developed to study porous explosives and propellants, it has been applied to a much wider range of materials. The early development of porous material models, such as that of Hermann, required empirical dynamic compaction data. Erkman and Edwards successfully applied the early theory to unreacted porous high explosives using a Gruneisen equation of state without yield behavior and without trapped gas in the pores. Butcher included viscoelastic rate dependance in pore collapse. The theoretical treatment of Carroll and Holt is centered on the collapse of a circular pore and includes radial inertia terms and a complex set of stress, strain and strain rate constitutive parameters. Unfortunately data required for these parameters are generally not available. The model described here is also centered on the collapse of a circular pore, but utilizes a simpler elastic-plastic static equilibrium pore collapse mechanism without strain rate dependence, or radial inertia terms. It does include trapped gas inside the pore, a solid material flow stress that creates both a yield point and a variation in solid material pressure with radius. The solid is described by a Mie-Gruneisen type EOS. Comparisons show that this model will accurately estimate major mechanical features which have been observed in compaction experiments

  10. Porous Materials - Structure and Properties

    DEFF Research Database (Denmark)

    Nielsen, Anders

    1997-01-01

    The paper presents some viewpoints on the description of the pore structure and the modelling of the properties of the porous building materials. Two examples are given , where it has been possible to connect the pore structure to the properties: Shrinkage of autoclaved aerated concrete...

  11. Real-time gamma imaging of technetium transport through natural and engineered porous materials for radioactive waste disposal.

    Science.gov (United States)

    Corkhill, Claire L; Bridge, Jonathan W; Chen, Xiaohui C; Hillel, Phil; Thornton, Steve F; Romero-Gonzalez, Maria E; Banwart, Steven A; Hyatt, Neil C

    2013-12-03

    We present a novel methodology for determining the transport of technetium-99m, a γ-emitting metastable isomer of (99)Tc, through quartz sand and porous media relevant to the disposal of nuclear waste in a geological disposal facility (GDF). Quartz sand is utilized as a model medium, and the applicability of the methodology to determine radionuclide transport in engineered backfill cement is explored using the UK GDF candidate backfill cement, Nirex Reference Vault Backfill (NRVB), in a model system. Two-dimensional distributions in (99m)Tc activity were collected at millimeter-resolution using decay-corrected gamma camera images. Pulse-inputs of ~20 MBq (99m)Tc were introduced into short (disposal of nuclear waste and potentially to a wide variety of other subsurface environments.

  12. FACADE SYSTEM MADE OF POROUS MATERIALS

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2012-10-01

    Full Text Available The proposed multi-component façade system is made of porous concretes employed both as bearing structures and for heat insulation and fireproofing purposes. The authors also provide their recommendations in respect of the mounting of the proposed façade system. The façade system considered in the article is composed of wall foam concrete blocks reinforced by basalt fibers (bearing elements of the structure, cellular concrete polystyrene (thermal insulation, and porous concrete (fireproofing and thermal insulation. Retained shuttering (in the fireproofing sections represents chrysolite cement sheets attached to the structures composed of glass-fiber plastic elements. The application of insulating porous concrete as a fireproofing material is based on the principle of adjustable stress-strained states of materials in the environment of variable pressure. This technology was developed at Moscow State University of Civil Engineering, and it was initially designated for the manufacturing of tailor-made products. The above concrete is also designated for retained shuttering and modified cavity masonry walls. Porous concrete that expands inside the fireproofing cavity ensures a tight contact both with the basic material and thermal insulation plates. The use of materials of the same origin (Portland cement means the formation of strong transition zones connecting the system components in the course of its hardening and further operation. The results of the thermotechnical calculation demonstrate that the thermal resistance registered on the surface of the wall that is 3 meters high (that has a 0.4 m fireproofing cavity is equal to 3.98 sq. m. C/Wt. The value of the coefficient of thermotechnical heterogeneity (r is equal to 0.86 with account for the thickness and thermal conductivity of point and linear elements. If the thermotechnical heterogeneity is taken into consideration, the thermal resistance of the proposed wall is equal to 3.42 m2 С/Wt.

  13. Properties of porous netted materials

    International Nuclear Information System (INIS)

    Daragan, V.D.; Drozdov, B.G.; Kotov, A.Yu.; Mel'nikov, G.N.; Pustogarov, A.V.

    1987-01-01

    Hydraulic and strength characteristics, efficient heat conduction and inner heat exchange coefficient are experimentally studied for porous netted materials on the base of the brass nets as dependent on porosity, cell size and method of net laying. Results of the studies are presented. It is shown that due to anisotropy of the material properties the hydraulic resistance in the direction parallel to the nets plane is 1.3-1.6 times higher than in the perpendicular one. Values of the effective heat conduction in the direction perpendicular to the nets plane at Π>0.45 agree with the data from literature, at Π<0.45 a deviation from the calculated values is marked in the direction of the heat conduction decrease

  14. Geometry and topology of porous materials

    International Nuclear Information System (INIS)

    Cohen, M.H.

    1985-01-01

    A very general definition of porous materials is given. The method of Lin and Cohen for the simple but exact description of the topology of porous materials is reviewed. The method leads to a precise definition of chambers, channels, and throats in the pore space. The power and utility of the method is illustrated via a discussion of the remarkable morphological features of porous rocks. These are enumerated and explained

  15. Moisture Sorption in Porous Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    2007-01-01

    pressure and weight data can be "translated" to pore geometry by known physical relationships. In this context, analytical descriptions are important which can relate moisture condensation in pore structures to ambient vapor pressure. Such a description, the extended BET-relation, is presented...... physical parameters, the so-called BET-parameters: The heat property factor, C, and the pore surface, SBET (derived from the so-called uni-molecular moisture content uBET). A software ‘SORP07’ has been developed to handle any calculations made in the paper. For readers who have a special interest...... in the subject considered this software is available on request to the author. Keywords: Porous materials, moisture, adsorption, desorption, BET-parameters....

  16. On strength of porous material - simple systems and densified systems

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    The question of non-destructive testing of porous materials has always been of interest for the engineering profession. A number of empirically based MOE-MOR relations between stiffness (Modulus Of Elasticity) and strength (Modulus Of Rupture) of materials have been established in order to control...

  17. The Materials Chemistry of Atomic Oxygen with Applications to Anisotropic Etching of Submicron Structures in Microelectronics and the Surface Chemistry Engineering of Porous Solids

    Science.gov (United States)

    Koontz, Steve L.; Leger, Lubert J.; Wu, Corina; Cross, Jon B.; Jurgensen, Charles W.

    1994-01-01

    Neutral atomic oxygen is the most abundant component of the ionospheric plasma in the low Earth orbit environment (LEO; 200 to 700 kilometers altitude) and can produce significant degradation of some spacecraft materials. In order to produce a more complete understanding of the materials chemistry of atomic oxygen, the chemistry and physics of O-atom interactions with materials were determined in three radically different environments: (1) The Space Shuttle cargo bay in low Earth orbit (the EOIM-3 space flight experiment), (2) a high-velocity neutral atom beam system (HVAB) at Los Alamos National Laboratory (LANL), and (3) a microwave-plasma flowing-discharge system at JSC. The Space Shuttle and the high velocity atom beam systems produce atom-surface collision energies ranging from 0.1 to 7 eV (hyperthermal atoms) under high-vacuum conditions, while the flowing discharge system produces a 0.065 eV surface collision energy at a total pressure of 2 Torr. Data obtained in the three different O-atom environments referred to above show that the rate of O-atom reaction with polymeric materials is strongly dependent on atom kinetic energy, obeying a reactive scattering law which suggests that atom kinetic energy is directly available for overcoming activation barriers in the reaction. General relationships between polymer reactivity with O atoms and polymer composition and molecular structure have been determined. In addition, vacuum ultraviolet photochemical effects have been shown to dominate the reaction of O atoms with fluorocarbon polymers. Finally, studies of the materials chemistry of O atoms have produced results which may be of interest to technologists outside the aerospace industry. Atomic oxygen 'spin-off' or 'dual use' technologies in the areas of anisotropic etching in microelectronic materials and device processing, as well as surface chemistry engineering of porous solid materials are described.

  18. Materials Science and Engineering |

    Science.gov (United States)

    Engineering? What Is Materials Science and Engineering? MSE combines engineering, physics and chemistry to solve problems in nanotechnology, biotechnology, information technology, energy, manufacturing, and more ,' which could replace steel. Materials Science and Mechanical Engineering Professors work together to

  19. Engineered porous scaffolds for periprosthetic infection prevention

    Energy Technology Data Exchange (ETDEWEB)

    Iviglia, Giorgio, E-mail: giorgio.iviglia@polito.it [Nobil Bio Ricerche Srl, 14037 Portacomaro (Italy); Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Politecnico di Torino, 10121 Torino (Italy); Cassinelli, Clara; Bollati, Daniele [Nobil Bio Ricerche Srl, 14037 Portacomaro (Italy); Baino, Francesco [Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Politecnico di Torino, 10121 Torino (Italy); Torre, Elisa; Morra, Marco [Nobil Bio Ricerche Srl, 14037 Portacomaro (Italy); Vitale-Brovarone, Chiara [Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Politecnico di Torino, 10121 Torino (Italy)

    2016-11-01

    Periprosthetic infection is a consequence of implant insertion procedures and strategies for its prevention involve either an increase in the rate of new bone formation or the release of antibiotics such as vancomycin. In this work we combined both strategies and developed a novel, multifunctional three-dimensional porous scaffold that was produced using hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), coupled with a pectin (PEC)-chitosan (CHIT) polyelectrolyte (PEI), and loaded with vancomycin (VCA). By this approach, a controlled vancomycin release was achieved and serial bacterial dilution test demonstrated that, after 1 week, the engineered construct still inhibits the bacterial growth. Degradation tests show an excellent behavior in a physiological and acidic environment (< 10% of mass loss). Furthermore, the PEI coating shows an anti-inflammatory response, and good cell proliferation and migration were demonstrated in vitro using osteoblast SAOS-2 cell line. This new engineered construct exhibits excellent properties both as an antibacterial material and as a stimulator of bone formation, which makes it a good candidate to contrast periprosthetic infection. - Highlights: • A novel three-dimensional ceramic scaffold was developed for infection prevention. • Pectin/chitosan coating stabilizes the degradation behavior in acidic environment. • Polyelectrolyte complex allows sustained release of vancomycin. • Inhibition of bacterial proliferation and biofilm formation was assessed. • PEI coating elicits anti-inflammatory response.

  20. Engineered porous scaffolds for periprosthetic infection prevention

    International Nuclear Information System (INIS)

    Iviglia, Giorgio; Cassinelli, Clara; Bollati, Daniele; Baino, Francesco; Torre, Elisa; Morra, Marco; Vitale-Brovarone, Chiara

    2016-01-01

    Periprosthetic infection is a consequence of implant insertion procedures and strategies for its prevention involve either an increase in the rate of new bone formation or the release of antibiotics such as vancomycin. In this work we combined both strategies and developed a novel, multifunctional three-dimensional porous scaffold that was produced using hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), coupled with a pectin (PEC)-chitosan (CHIT) polyelectrolyte (PEI), and loaded with vancomycin (VCA). By this approach, a controlled vancomycin release was achieved and serial bacterial dilution test demonstrated that, after 1 week, the engineered construct still inhibits the bacterial growth. Degradation tests show an excellent behavior in a physiological and acidic environment (< 10% of mass loss). Furthermore, the PEI coating shows an anti-inflammatory response, and good cell proliferation and migration were demonstrated in vitro using osteoblast SAOS-2 cell line. This new engineered construct exhibits excellent properties both as an antibacterial material and as a stimulator of bone formation, which makes it a good candidate to contrast periprosthetic infection. - Highlights: • A novel three-dimensional ceramic scaffold was developed for infection prevention. • Pectin/chitosan coating stabilizes the degradation behavior in acidic environment. • Polyelectrolyte complex allows sustained release of vancomycin. • Inhibition of bacterial proliferation and biofilm formation was assessed. • PEI coating elicits anti-inflammatory response.

  1. Dictionary materials engineering, materials testing

    International Nuclear Information System (INIS)

    1994-01-01

    This dictionary contains about 9,500 entries in each part of the following fields: 1) Materials using and selection; 2) Mechanical engineering materials -Metallic materials - Non-metallic inorganic materials - Plastics - Composites -Materials damage and protection; 3) Electrical and electronics materials -Conductor materials - Semiconductors - magnetic materials - Dielectric materials - non-conducting materials; 4) Materials testing - Mechanical methods - Analytical methods - Structure investigation - Complex methods - Measurement of physical properties - Non-destructive testing. (orig.) [de

  2. Porous polymeric materials for hydrogen storage

    Science.gov (United States)

    Yu, Luping; Liu, Di-Jia; Yuan, Shengwen; Yang, Junbing

    2013-04-02

    A porous polymer, poly-9,9'-spirobifluorene and its derivatives for storage of H.sub.2 are prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  3. Capillary condensation of adsorbates in porous materials.

    Science.gov (United States)

    Horikawa, Toshihide; Do, D D; Nicholson, D

    2011-11-14

    Hysteresis in capillary condensation is important for the fundamental study and application of porous materials, and yet experiments on porous materials are sometimes difficult to interpret because of the many interactions and complex solid structures involved in the condensation and evaporation processes. Here we make an overview of the significant progress in understanding capillary condensation and hysteresis phenomena in mesopores that have followed from experiment and simulation applied to highly ordered mesoporous materials such as MCM-41 and SBA-15 over the last few decades. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Measurement of Emissivity of Porous Ceramic Materials

    OpenAIRE

    BÜYÜKALACA, Orhan

    1998-01-01

    In this study, measurements of spectral and total emissivities of seven different porous ceramic materials and one ceramic fibre material are reported. Measurements were made for wavelength range from 1.2 µm to 20 µm and temperature range from 200 °C to 700 °C. It was found that total emissivity increases with increase of pore size but decreases with increase of temperature. The results showed all the porous ceramic materials tested to be much better than ceramic fibre in terms of total em...

  5. Porous magnesium-based scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Yazdimamaghani, Mostafa; Razavi, Mehdi; Vashaee, Daryoosh; Moharamzadeh, Keyvan; Boccaccini, Aldo R.; Tayebi, Lobat

    2017-01-01

    Significant amount of research efforts have been dedicated to the development of scaffolds for tissue engineering. Although at present most of the studies are focused on non-load bearing scaffolds, many scaffolds have also been investigated for hard tissue repair. In particular, metallic scaffolds are being studied for hard tissue engineering due to their suitable mechanical properties. Several biocompatible metallic materials such as stainless steels, cobalt alloys, titanium alloys, tantalum, nitinol and magnesium alloys have been commonly employed as implants in orthopedic and dental treatments. They are often used to replace and regenerate the damaged bones or to provide structural support for healing bone defects. Among the common metallic biomaterials, magnesium (Mg) and a number of its alloys are effective because of their mechanical properties close to those of human bone, their natural ionic content that may have important functional roles in physiological systems, and their in vivo biodegradation characteristics in body fluids. Due to such collective properties, Mg based alloys can be employed as biocompatible, bioactive, and biodegradable scaffolds for load-bearing applications. Recently, porous Mg and Mg alloys have been specially suggested as metallic scaffolds for bone tissue engineering. With further optimization of the fabrication techniques, porous Mg is expected to make a promising hard substitute scaffold. The present review covers research conducted on the fabrication techniques, surface modifications, properties and biological characteristics of Mg alloys based scaffolds. Furthermore, the potential applications, challenges and future trends of such degradable metallic scaffolds are discussed in detail. - Highlights: • A porous 3D material provides the required pathways for cells to grow, proliferate, and differentiate • Porous magnesium and Mg alloys could be used as load-bearing scaffolds • Porous magnesium and Mg alloys are good

  6. Porous magnesium-based scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Yazdimamaghani, Mostafa [School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States); Razavi, Mehdi [Department of Radiology, School of Medicine, Stanford University, Palo Alto, CA 94304 (United States); Vashaee, Daryoosh [Electrical and Computer Engineering Department, North Carolina State University, Raleigh, NC 27606 (United States); Moharamzadeh, Keyvan [School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield (United Kingdom); Marquette University School of Dentistry, Milwaukee, WI 53233 (United States); Boccaccini, Aldo R. [Institute of Biomaterials, University of Erlangen-Nuremberg, Cauerstrasse 6, 91058 Erlangen (Germany); Tayebi, Lobat, E-mail: lobat.tayebi@marquette.edu [Marquette University School of Dentistry, Milwaukee, WI 53233 (United States)

    2017-02-01

    Significant amount of research efforts have been dedicated to the development of scaffolds for tissue engineering. Although at present most of the studies are focused on non-load bearing scaffolds, many scaffolds have also been investigated for hard tissue repair. In particular, metallic scaffolds are being studied for hard tissue engineering due to their suitable mechanical properties. Several biocompatible metallic materials such as stainless steels, cobalt alloys, titanium alloys, tantalum, nitinol and magnesium alloys have been commonly employed as implants in orthopedic and dental treatments. They are often used to replace and regenerate the damaged bones or to provide structural support for healing bone defects. Among the common metallic biomaterials, magnesium (Mg) and a number of its alloys are effective because of their mechanical properties close to those of human bone, their natural ionic content that may have important functional roles in physiological systems, and their in vivo biodegradation characteristics in body fluids. Due to such collective properties, Mg based alloys can be employed as biocompatible, bioactive, and biodegradable scaffolds for load-bearing applications. Recently, porous Mg and Mg alloys have been specially suggested as metallic scaffolds for bone tissue engineering. With further optimization of the fabrication techniques, porous Mg is expected to make a promising hard substitute scaffold. The present review covers research conducted on the fabrication techniques, surface modifications, properties and biological characteristics of Mg alloys based scaffolds. Furthermore, the potential applications, challenges and future trends of such degradable metallic scaffolds are discussed in detail. - Highlights: • A porous 3D material provides the required pathways for cells to grow, proliferate, and differentiate • Porous magnesium and Mg alloys could be used as load-bearing scaffolds • Porous magnesium and Mg alloys are good

  7. Electrokinetic desalination of porous building materials

    NARCIS (Netherlands)

    Kamran, K.

    2012-01-01

    The deterioration of porous building materials and structures by the crystallization of water soluble salts is a well known phenomenon. The threats posed by salts to building materials can be minimized either by controlling the environment or by removing the salts from the deteriorated zone. In

  8. Engineered Porous Materials EXPO `93

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-01

    The EXPO was organized to increase communication between US industry and DOE`s national laboratories. The report contains copies of viewgraphs of all speakers and reports of workshops designed to identify priority needs of industry. A conference synopsis and set of recommendations to DOE are also included.

  9. Hydrogen storage by physisorption on porous materials

    Energy Technology Data Exchange (ETDEWEB)

    Panella, B.

    2006-09-13

    A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

  10. Hydrogen storage by physisorption on porous materials

    Energy Technology Data Exchange (ETDEWEB)

    Panella, B

    2006-09-13

    A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

  11. Optimal Design of Porous Materials

    DEFF Research Database (Denmark)

    Andreassen, Erik

    The focus of this thesis is topology optimization of material microstructures. That is, creating new materials, with attractive properties, by combining classic materials in periodic patterns. First, large-scale topology optimization is used to design complicated three-dimensional materials......, throughout the thesis extra attention is given to obtain structures that can be manufactured. That is also the case in the final part, where a simple multiscale method for the optimization of structural damping is presented. The method can be used to obtain an optimized component with structural details...

  12. Preparation of porous materials for radionuclides capture

    International Nuclear Information System (INIS)

    Bajzikova, Anna; Smrcek, Stanislav; Kozempel, Jan; Vlk, Martin; Barta, Jan

    2015-01-01

    Porous materials showing promise for radionuclide capture from water at contaminated sites were prepared. Nanoporous materials (size of pores 1-100 nm) and some polymers are well suited to this purpose owing their affinity for selected radionuclides. Nanoporous metal oxides and silica gel with styrene-divinylbenzene-TODGA-modified surface were prepared, characterized and tested for radionuclide ( 227 Ac, 227 Th, 223 Ra) capture efficiency. (orig.)

  13. Filter casting nanoscale porous materials

    Science.gov (United States)

    Hayes, Joel Ryan; Nyce, Gregory Walker; Kuntz, Jushua David

    2013-12-10

    A method of producing nanoporous material includes the steps of providing a liquid, providing nanoparticles, producing a slurry of the liquid and the nanoparticles, removing the liquid from the slurry, and producing monolith.

  14. Supercapacitive characteristics of electrochemically active porous materials

    Directory of Open Access Journals (Sweden)

    VLADIMIR V. PANIC

    2008-06-01

    Full Text Available The results of an investigation of the capacitive characteristics of sol–gel-processed titanium- and carbon-supported electrochemically active noble metal oxides, as representatives of porous electrode materials, are presented in the lecture. The capacitive properties of these materials were correlated to their composition, the preparation conditions of the oxides and coatings, the properties of the carbon support and to the composition of the electrolyte. The results of the electrochemical test methods, cyclic voltammetry and electrochemical impedance spectroscopy, were employed to resolve the possible physical structures of the mentioned porous materials, which are governed by the controlled conditions of the preparation of the oxide by the sol–gel process.

  15. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  16. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu; Tian, Qiwei; Dong, Xinglong; Liu, Zhaohui; Basset, Jean-Marie; Saih, Youssef; Sun, Miao; Xu, Wei; Shaikh, Sohel

    2017-01-01

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  17. Magnetic resonance and porous materials

    International Nuclear Information System (INIS)

    McDonald, P.; Strange, J.

    1998-01-01

    Mention the words magnetic resonance to your medical advisor and he or she will immediately think of a multi-million pound scanner that peers deep into the brain. A chemist, on the other hand, will imagine a machine that costs several hundred thousand pounds and produces high-resolution spectra for chemical analysis. Food technologists will probably think of a bench-top instrument for determining moisture content, while an oil prospector will envisage a device that can be operated several kilometres down an oil well. To a physicist the term is more likely to conjure up a mental picture of nuclear spins precessing in a magnetic field. These examples illustrate the diverse aspects of a phenomenon discovered by physicists over 50 years ago. Electron spin resonance was first discovered by Russian scientists, and nuclear magnetic resonance was discovered in the US shortly afterwards by Ed Purcell at Harvard University and Felix Bloch at Stanford University. Today, nuclear magnetic resonance (NMR) is the most widely used technique. Modern NMR machines are making it possible to probe microstructure and molecular movement in materials as diverse as polymers, cements, rocks, soil and foods. NMR allows the distribution of different components in a material to be determined with a resolution approaching 1μm, although the signal can be sensitive to even smaller lengthscales. In this article the authors describe how physicists are still developing magnetic resonance to exploit a range of new applications. (UK)

  18. Development of porous materials for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Shinji Oshima; Osamu Kato; Takeshi Kataoka; Yoshihiro Kobori; Michiaki Adachi [Hydrogen and New Energy Research Laboratory Nippon Oil Corporation 8, Chidoricho, Naka-ku, Yokohama, 231-0815 (Japan)

    2006-07-01

    To achieve hydrogen storage of more than 5 mass%, we are focusing on porous materials that consist of light elements. At WHEC 15, we reported that KOH-activated bamboo charcoal showed 0.79 mass% hydrogen uptake at 9.5 MPa and 303 K. After examining various carbon materials, we found that carbonized and KOH-activated polyacrylonitrile fibers showed 1.0 mass% hydrogen uptake at 9.5 MPa and 303 K. When the pressure was raised to 35 MPa, this material showed 1.5 mass% hydrogen uptake at 303 K. Besides porous carbon, other materials, such as coordination polymers, were examined. Since these materials contain elements other than carbon, different adsorption phenomena may be expected. Although the values of their hydrogen uptakes are still lower than those of carbon materials, a coordination polymer which showed 0.38 mass% hydrogen uptake at 9.5 MPa and 303 K was revealed to give an adsorption density of 47 kg/m{sup 3} at 0.1 MPa and 77 K, the highest value reported for a coordination polymer. (authors)

  19. Morphological characterization of shocked porous material

    International Nuclear Information System (INIS)

    Xu Aiguo; Zhang Guangcai; Pan, X F; Zhang Ping; Zhu Jianshi

    2009-01-01

    Morphological measures are introduced to probe the complex procedure of shock wave reaction on porous material. They characterize the geometry and the topology of the pixelized map of a state variable like temperature. The relevance to thermodynamical properties of a material is revealed and various experimental conditions are simulated. Numerical results indicate that the shock wave reaction results in a complicated sequence of compressions and rarefactions in porous material. The increasing rate of the total fractional white area A roughly gives the velocity D of a compressive-wave series. When a velocity D is mentioned, the corresponding threshold contour level of the state variable, such as temperature, should also be stated. When the threshold contour level increases, D becomes smaller. The area A increases parabolically with time t during the initial period. The A(t) curve goes back to being linear in the following three cases: (i) when the porosity δ approaches 1, (ii) when the initial shock becomes stronger and (iii) when the contour level approaches the minimum value of the state variable. The area with high temperature may continue to increase even after the early compressive waves have arrived at the downstream free surface and some rarefactive waves have come back into the target body. In the case of energetic material needing a higher temperature for initiation, a higher porosity is preferred and the material may be initiated after the precursory compressive waves have scanned the entire target body. In some cases we need scattered hot spots, but in others we need connected ones. One may desire the fabrication of a porous body and choose the appropriate shock strength according to what is needed. With the Minkowski measures, the dependence on experimental conditions is reflected simply by a few coefficients. They may be used as order parameters to classify the maps of physical variables in a similar way to thermodynamic phase transitions.

  20. Computational materials chemistry for carbon capture using porous materials

    International Nuclear Information System (INIS)

    Sharma, Abhishek; Malani, Ateeque; Huang, Runhong; Babarao, Ravichandar

    2017-01-01

    Control over carbon dioxide (CO 2 ) release is extremely important to decrease its hazardous effects on the environment such as global warming, ocean acidification, etc. For CO 2 capture and storage at industrial point sources, nanoporous materials offer an energetically viable and economically feasible approach compared to chemisorption in amines. There is a growing need to design and synthesize new nanoporous materials with enhanced capability for carbon capture. Computational materials chemistry offers tools to screen and design cost-effective materials for CO 2 separation and storage, and it is less time consuming compared to trial and error experimental synthesis. It also provides a guide to synthesize new materials with better properties for real world applications. In this review, we briefly highlight the various carbon capture technologies and the need of computational materials design for carbon capture. This review discusses the commonly used computational chemistry-based simulation methods for structural characterization and prediction of thermodynamic properties of adsorbed gases in porous materials. Finally, simulation studies reported on various potential porous materials, such as zeolites, porous carbon, metal organic frameworks (MOFs) and covalent organic frameworks (COFs), for CO 2 capture are discussed. (topical review)

  1. Anomalous water absorption in porous materials

    CERN Document Server

    Lockington, D A

    2003-01-01

    The absorption of fluid by unsaturated, rigid porous materials may be characterized by the sorptivity. This is a simple parameter to determine and is increasingly being used as a measure of a material's resistance to exposure to fluids (especially moisture and reactive solutes) in aggressive environments. The complete isothermal absorption process is described by a nonlinear diffusion equation, with the hydraulic diffusivity being a strongly nonlinear function of the degree of saturation of the material. This diffusivity can be estimated from the sorptivity test. In a typical test the cumulative absorption is proportional to the square root of time. However, a number of researchers have observed deviation from this behaviour when the infiltrating fluid is water and there is some potential for chemo-mechanical interaction with the material. In that case the current interpretation of the test and estimation of the hydraulic diffusivity is no longer appropriate. Kuentz and Lavallee (2001) discuss the anomalous b...

  2. Hysteretic capillary condensation in a porous material

    International Nuclear Information System (INIS)

    Lilly, M.P.; Hallock, R.B.

    1995-01-01

    The authors report on the behavior of hysteresis subloops in the capillary condensation of 4 He in the porous material Nuclepore. For hysteretic systems composed of many independent elements, the Preisach model may be used to predict the behavior of the resulting hysteresis. One prediction is that subloops with common chemical potential endpoints will be congruent. The observations of such subloops show that the prediction of congruence fails for this capillary condensation system. To understand deviations from Preisach behavior the authors modify the model to account for intersections among the pores. The modified model is in close agreement with the experimental results

  3. Thermal conductivity of highly porous mullite material

    International Nuclear Information System (INIS)

    Barea, Rafael; Osendi, Maria Isabel; Ferreira, Jose M.F.; Miranzo, Pilar

    2005-01-01

    The thermal diffusivity of highly porous mullite materials (35-60 vol.% porosity) has been measured up to 1000 deg C by the laser flash method. These materials were fabricated by a direct consolidation method based on the swelling properties of starch granules in concentrated aqueous suspensions and showed mainly spherical shaped pores of about 30 μm in diameter. From the point of view of heat conduction, they behave as a bi-phase material of voids dispersed in the continuous mullite matrix. The temperature dependence of thermal conductivity for the different porosities was modeled by a simple equation that considers the contribution to heat conduction of the mullite matrix and the gas inside the pores, as well as the radiation. The thermal conductivity of the matrix was taken from the measurements done in a dense mullite while the conductivity in the voids was assumed to be that of the testing atmosphere

  4. Materials science and engineering

    Energy Technology Data Exchange (ETDEWEB)

    Lesuer, D.R.

    1997-02-01

    During FY-96, work within the Materials Science and Engineering Thrust Area was focused on material modeling. Our motivation for this work is to develop the capability to study the structural response of materials as well as material processing. These capabilities have been applied to a broad range of problems, in support of many programs at Lawrence Livermore National Laboratory. These studies are described in (1) Strength and Fracture Toughness of Material Interfaces; (2) Damage Evolution in Fiber Composite Materials; (3) Flashlamp Envelope Optical Properties and Failure Analysis; (4) Synthesis and Processing of Nanocrystalline Hydroxyapatite; and (5) Room Temperature Creep Compliance of Bulk Kel-E.

  5. Design, preparation, and application of ordered porous polymer materials

    International Nuclear Information System (INIS)

    Liu, Qingquan; Tang, Zhe; Ou, Baoli; Liu, Lihua; Zhou, Zhihua; Shen, Shaohua; Duan, Yinxiang

    2014-01-01

    Ordered porous polymer (OPP) materials have extensively application prospects in the field of separation and purification, biomembrane, solid supports for sensors catalysts, scaffolds for tissue engineering, photonic band gap materials owing to ordered pore arrays, uniform and tunable pore size, high specific surface area, great adsorption capacity, and light weight. The present paper reviewed the preparation techniques of OPP materials like breath figures, hard template, and soft template. Finally, the applications of OPP materials in the field of separation, sensors, and biomedicine are introduced, respectively. - Highlights: • Breath figures involve polymer casting under moist ambience. • Hard template employs monodisperse colloidal spheres as a template. • Soft template utilizes the etched block in copolymers as template

  6. Materials Engineering Research Facility (MERF)

    Data.gov (United States)

    Federal Laboratory Consortium — Argonne?s Materials Engineering Research Facility (MERF) enables engineers to develop manufacturing processes for producing advanced battery materials in sufficient...

  7. Acoustics of multiscale sorptive porous materials

    Science.gov (United States)

    Venegas, R.; Boutin, C.; Umnova, O.

    2017-08-01

    This paper investigates sound propagation in multiscale rigid-frame porous materials that support mass transfer processes, such as sorption and different types of diffusion, in addition to the usual visco-thermo-inertial interactions. The two-scale asymptotic method of homogenization for periodic media is successively used to derive the macroscopic equations describing sound propagation through the material. This allowed us to conclude that the macroscopic mass balance is significantly modified by sorption, inter-scale (micro- to/from nanopore scales) mass diffusion, and inter-scale (pore to/from micro- and nanopore scales) pressure diffusion. This modification is accounted for by the dynamic compressibility of the effective saturating fluid that presents atypical properties that lead to slower speed of sound and higher sound attenuation, particularly at low frequencies. In contrast, it is shown that the physical processes occurring at the micro-nano-scale do not affect the macroscopic fluid flow through the material. The developed theory is exemplified by introducing an analytical model for multiscale sorptive granular materials, which is experimentally validated by comparing its predictions with acoustic measurements on granular activated carbons. Furthermore, we provide empirical evidence supporting an alternative method for measuring sorption and mass diffusion properties of multiscale sorptive materials using sound waves.

  8. Basalt fiber reinforced porous aggregates-geopolymer based cellular material

    Science.gov (United States)

    Luo, Xin; Xu, Jin-Yu; Li, Weimin

    2015-09-01

    Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress-strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress-strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

  9. Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

    Science.gov (United States)

    Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

    2013-10-01

    Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.

  10. Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

    Science.gov (United States)

    Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

    2013-01-01

    Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10–40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage. PMID:24145684

  11. Random-walk diffusion and drying of porous materials

    Science.gov (United States)

    Mehrafarin, M.; Faghihi, M.

    2001-12-01

    Based on random-walk diffusion, a microscopic model for drying is proposed to explain the characteristic features of the drying-rate curve of porous materials. The constant drying-rate period is considered as a normal diffusion process. The transition to the falling-rate regime is attributed to the fractal nature of porous materials which results in crossover to anomalous diffusion.

  12. General Theory of Absorption in Porous Materials: Restricted Multilayer Theory.

    Science.gov (United States)

    Aduenko, Alexander A; Murray, Andy; Mendoza-Cortes, Jose L

    2018-04-18

    In this article, we present an approach for the generalization of adsorption of light gases in porous materials. This new theory goes beyond Langmuir and Brunauer-Emmett-Teller theories, which are the standard approaches that have a limited application to crystalline porous materials by their unphysical assumptions on the amount of possible adsorption layers. The derivation of a more general equation for any crystalline porous framework is presented, restricted multilayer theory. Our approach allows the determination of gas uptake considering only geometrical constraints of the porous framework and the interaction energy of the guest molecule with the framework. On the basis of this theory, we calculated optimal values for the adsorption enthalpy at different temperatures and pressures. We also present the use of this theory to determine the optimal linker length for a topologically equivalent framework series. We validate this theoretical approach by applying it to metal-organic frameworks (MOFs) and show that it reproduces the experimental results for seven different reported materials. We obtained the universal equation for the optimal linker length, given the topology of a porous framework. This work applied the general equation to MOFs and H 2 to create energy-storage materials; however, this theory can be applied to other crystalline porous materials and light gases, which opens the possibility of designing the next generations of energy-storage materials by first considering only the geometrical constraints of the porous materials.

  13. Advances in design and modeling of porous materials

    Science.gov (United States)

    Ayral, André; Calas-Etienne, Sylvie; Coasne, Benoit; Deratani, André; Evstratov, Alexis; Galarneau, Anne; Grande, Daniel; Hureau, Matthieu; Jobic, Hervé; Morlay, Catherine; Parmentier, Julien; Prelot, Bénédicte; Rossignol, Sylvie; Simon-Masseron, Angélique; Thibault-Starzyk, Frédéric

    2015-07-01

    This special issue of the European Physical Journal Special Topics is dedicated to selected papers from the symposium "High surface area porous and granular materials" organized in the frame of the conference "Matériaux 2014", held on November 24-28, 2014 in Montpellier, France. Porous materials and granular materials gather a wide variety of heterogeneous, isotropic or anisotropic media made of inorganic, organic or hybrid solid skeletons, with open or closed porosity, and pore sizes ranging from the centimeter scale to the sub-nanometer scale. Their technological and industrial applications cover numerous areas from building and civil engineering to microelectronics, including also metallurgy, chemistry, health, waste water and gas effluent treatment. Many emerging processes related to environmental protection and sustainable development also rely on this class of materials. Their functional properties are related to specific transfer mechanisms (matter, heat, radiation, electrical charge), to pore surface chemistry (exchange, adsorption, heterogeneous catalysis) and to retention inside confined volumes (storage, separation, exchange, controlled release). The development of innovative synthesis, shaping, characterization and modeling approaches enables the design of advanced materials with enhanced functional performance. The papers collected in this special issue offer a good overview of the state-of-the-art and science of these complex media. We would like to thank all the speakers and participants for their contribution to the success of the symposium. We also express our gratitude to the organization committee of "Matériaux 2014". We finally thank the reviewers and the staff of the European Physical Journal Special Topics who made the publication of this special issue possible.

  14. METHOD OF IMPREGNATING A POROUS MATERIAL

    Science.gov (United States)

    Steele, G.N.

    1960-06-01

    A method of impregnating a porous body with an inorganic uranium- containing salt is outlined and comprises dissolving a water-soluble uranium- containing salt in water; saturating the intercommunicating pores of the porous body with the salt solution; infusing ammonia gas into the intercommunicating pores of the body, the ammonia gas in water chemically reacting with the water- soluble uranium-containing salt in the water solvent to form a nonwater-soluble uranium-containing precipitant; and evaporating the volatile unprecipitated products from the intercommunicating pores whereby the uranium-containing precipitate is uniformly distributed in the intercommunicating peres of the porous body.

  15. Light scattering in porous materials: Geometrical optics and stereological approach

    International Nuclear Information System (INIS)

    Malinka, Aleksey V.

    2014-01-01

    Porous material has been considered from the point of view of stereology (geometrical statistics), as a two-phase random mixture of solid material and air. Considered are the materials having the refractive index with the real part that differs notably from unit and the imaginary part much less than unit. Light scattering in such materials has been described using geometrical optics. These two – the geometrical optics laws and the stereological approach – allow one to obtain the inherent optical properties of such a porous material, which are basic in the radiative transfer theory: the photon survival probability, the scattering phase function, and the polarization properties (Mueller matrix). In this work these characteristics are expressed through the refractive index of the material and the random chord length distribution. The obtained results are compared with the traditional approach, modeling the porous material as a pack of particles of different shapes. - Highlights: • Porous material has been considered from the point of view of stereology. • Properties of a two-phase random mixture of solid material and air are considered. • Light scattering in such materials has been described using geometrical optics. • The inherent optical properties of such a porous material have been obtained

  16. Numerical investigation of porous materials composites reinforced with natural fibers

    Science.gov (United States)

    Chikhi, M.; Metidji, N.; Mokhtari, F.; Merzouk, N. k.

    2018-05-01

    The present article tends to predict the effective thermal properties of porous biocomposites materials. The composites matrix consists on porous materials namely gypsum and the reinforcement is a natural fiber as date palm fibers. The numerical study is done using Comsol software resolving the heat transfer equation. The results are fitted with theoretical model and experimental results. The results of this study indicate that the porosity has an effect on the Effective thermal conductivity biocompoites.

  17. Testing of porous materials using ion beam techniques

    International Nuclear Information System (INIS)

    Szilagyi, E.; Asrama, M.; Paszti, F.; Battistig, G.; Hajnal, Z.

    1999-01-01

    Porous materials were examined by backscattering spectrometry and oxygen resonance measurements. The material was a porous silicon (PS) sample. The BS data were evaluated by simulation, using the RBX program, and a comparison was made with measured data. The PS sample was also investigated using the 16 O(α,α) 16 O reaction, and the resonance spectra were evaluated. The data yielded useful information on porosity, mean pore diameter, mean pore distance, and structure ordering. (R.P.)

  18. Photo-patterning of porous hydrogels for tissue engineering.

    Science.gov (United States)

    Bryant, Stephanie J; Cuy, Janet L; Hauch, Kip D; Ratner, Buddy D

    2007-07-01

    Since pore size and geometry strongly impact cell behavior and in vivo reaction, the ability to create scaffolds with a wide range of pore geometries that can be tailored to suit a particular cell type addresses a key need in tissue engineering. In this contribution, we describe a novel and simple technique to design porous, degradable poly(2-hydroxyethyl methacrylate) hydrogel scaffolds with well-defined architectures using a unique photolithography process and optimized polymer chemistry. A sphere-template was used to produce a highly uniform, monodisperse porous structure. To create a patterned and porous hydrogel scaffold, a photomask and initiating light were employed. Open, vertical channels ranging in size from 360+/-25 to 730+/-70 microm were patterned into approximately 700 microm thick hydrogels with pore diameters of 62+/-8 or 147+/-15 microm. Collagen type I was immobilized onto the scaffolds to facilitate cell adhesion. To assess the potential of these novel scaffolds for tissue engineering, a skeletal myoblast cell line (C2C12) was seeded onto scaffolds with 147 microm pores and 730 microm diameter channels, and analyzed by histology and digital volumetric imaging. Cell elongation, cell spreading and fibrillar formation were observed on these novel scaffolds. In summary, 3D architectures can be patterned into porous hydrogels in one step to create a wide range of tissue engineering scaffolds that may be tailored for specific applications.

  19. Living bacterial sacrificial porogens to engineer decellularized porous scaffolds.

    Directory of Open Access Journals (Sweden)

    Feng Xu

    Full Text Available Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types.

  20. Numerical Analysis of a Class of THM Coupled Model for Porous Materials

    Science.gov (United States)

    Liu, Tangwei; Zhou, Jingying; Lu, Hongzhi

    2018-01-01

    We consider the coupled models of the Thermo-hydro-mechanical (THM) problem for porous materials which arises in many engineering applications. Firstly, mathematical models of the THM coupled problem for porous materials were discussed. Secondly, for different cases, some numerical difference schemes of coupled model were constructed, respectively. Finally, aassuming that the original water vapour effect is neglectable and that the volume fraction of liquid phase and the solid phase are constants, the nonlinear equations can be reduced to linear equations. The discrete equations corresponding to the linear equations were solved by the Arnodli method.

  1. TESTING ANTIMICROBIAL EFFICACY ON POROUS MATERIALS

    Science.gov (United States)

    The efficacy of antimicrobial treatments to eliminate or control biological growth in the indoor environment can easily be tested on nonporous surfaces. However, the testing of antimicrobial efficacy on porous surfaces, such as those found in the indoor environment [i.e., gypsum ...

  2. Filtration of engineered nanoparticles using porous membranes

    NARCIS (Netherlands)

    Trzaskus, Krzystof

    2016-01-01

    The research presented in this thesis aims at providing a better understanding of the fundamental aspects responsible for nanoparticle removal and fouling development during filtration of engineered nanoparticles. The emphasis is put on the role of interparticle interactions in the feed solution,

  3. Porous Materials from Thermally Activated Kaolinite: Preparation, Characterization and Application

    Directory of Open Access Journals (Sweden)

    Jun Luo

    2017-06-01

    Full Text Available In the present study, porous alumina/silica materials were prepared by selective leaching of silicon/aluminum constituents from thermal-activated kaolinite in inorganic acid or alkali liquor. The correlations between the characteristics of the prepared porous materials and the dissolution properties of activated kaolinite were also investigated. The results show that the specific surface area (SSA of porous alumina/silica increases with silica/alumina dissolution, but without marked change of the BJH pore size. Furthermore, change in pore volume is more dependent on activation temperature. The porous alumina and silica obtained from alkali leaching of kaolinite activated at 1150 °C for 15 min and acid leaching of kaolinite activated at 850 °C for 15 min are mesoporous, with SSAs, BJH pore sizes and pore volumes of 55.8 m2/g and 280.3 m2/g, 6.06 nm and 3.06 nm, 0.1455 mL/g and 0.1945 mL/g, respectively. According to the adsorption tests, porous alumina has superior adsorption capacities for Cu2+, Pb2+ and Cd2+ compared with porous silica and activated carbon. The maximum capacities of porous alumina for Cu2+, Pb2+ and Cd2+ are 134 mg/g, 183 mg/g and 195 mg/g, respectively, at 30 °C.

  4. Porous materials produced from incineration ash using thermal plasma technology.

    Science.gov (United States)

    Yang, Sheng-Fu; Chiu, Wen-Tung; Wang, To-Mai; Chen, Ching-Ting; Tzeng, Chin-Ching

    2014-06-01

    This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9-1.2 g cm(-3) and 50-60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m(-1) K(-1). Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Physicomechanical properties of porous fiber materials and prediction of them

    International Nuclear Information System (INIS)

    Kostornov, A.G.; Galstyan, L.G.

    1985-01-01

    A comparison is presented of the experimentally determined values of certain properties of porous fiber materials obtained by the optimum method from monodisperse fibers of copper, nickel, and Nichrome of different diameters with the corresponding theoretical values. The electrical conductivity, tensile strength, and modulus of elasticity, the basic properties of a porous body, which are determined both by the structural characteristics of the elements and by the condition of the interparticle contacts, were considered

  6. Vibro-acoustics of porous materials - waveguide modeling approach

    DEFF Research Database (Denmark)

    Darula, Radoslav; Sorokin, Sergey V.

    2016-01-01

    The porous material is considered as a compound multi-layered waveguide (i.e. a fluid layer surrounded with elastic layers) with traction free boundary conditions. The attenuation of the vibro-acoustic waves in such a material is assessed. This approach is compared with a conventional Biot's mode...

  7. Mechanical Material Engineering

    International Nuclear Information System (INIS)

    Kim, Mun Il

    1993-01-01

    This book introduced mechanical material with introduction, basic problems about metal ingredient of machine of metal and alloy, property of metal material mechanical metal material such as categorization of metal material and high tensile structure steel, mechanic design and steel material with three important points on using of steel materials, selection and directions machine structural steel, selection and directions of steel for tool, selection and instruction of special steel like stainless steel and spring steel, nonferrous metal materials and plastic.

  8. ELECTROKINETIC DEVICE AND METHOD FOR CONSOLIDATING POROUS MATERIALS

    DEFF Research Database (Denmark)

    2017-01-01

    The invention relates to a device and an associated electrokinetic method which allows the pores (superficial and deep) of a porous material to be filled, by forcing the precipitation therein of a product of low solubility in water by creating an electric field which will mobilise the cations...... and anions supplied by previously selected solutions. This method comprises two phases. In the first phase, the pores located at a specified distance from the surface of contact between the porous material and the anodic or cathodic compartment are plugged. In a second phase, the rest of the pores, mainly...... those which are on the surface level, are collapsed. As a result of the designed device and the plugging system contained therein, the porous material is not affected at any moment by chemical alteration processes caused by contact with extreme pH values. This device allows the treatment to be applied...

  9. The micro and meso-porous materials. Characterization; Les materiaux micro et mesoporeux. Caracterisation

    Energy Technology Data Exchange (ETDEWEB)

    Thibault-Starzyk, F.

    2004-10-01

    The micro and meso-porous materials, called zeolites, are very important in the modern chemical industry and in petrochemistry. This book deals in particular with the study and the characterization of zeolites. Its aim is to give to generalist chemists the tools for approaching experimentally these particular materials. The main methods of study and characterization are gathered in eight chapters, and the authors stress on the specificities due to the porous system: -structural analysis by the diffraction methods; -infrared spectroscopy; -NMR; -micro-calorimetry; -adsorption thermodynamics; -methods using the programed temperature; -modeling; -reactivity: kinetics and chemical engineering. This book appeals to students, engineers or searchers, without previous knowledge on these materials, but having a bachelor's degree or a master degree in general chemistry. (O.M.)

  10. Interconnected porous hydroxyapatite ceramics for bone tissue engineering

    Science.gov (United States)

    Yoshikawa, Hideki; Tamai, Noriyuki; Murase, Tsuyoshi; Myoui, Akira

    2008-01-01

    Several porous calcium hydroxyapatite (HA) ceramics have been used clinically as bone substitutes, but most of them possessed few interpore connections, resulting in pathological fracture probably due to poor bone formation within the substitute. We recently developed a fully interconnected porous HA ceramic (IP-CHA) by adopting the ‘foam-gel’ technique. The IP-CHA had a three-dimensional structure with spherical pores of uniform size (average 150 μm, porosity 75%), which were interconnected by window-like holes (average diameter 40 μm), and also demonstrated adequate compression strength (10–12 MPa). In animal experiments, the IP-CHA showed superior osteoconduction, with the majority of pores filled with newly formed bone. The interconnected porous structure facilitates bone tissue engineering by allowing the introduction of mesenchymal cells, osteotropic agents such as bone morphogenetic protein or vasculature into the pores. Clinically, we have applied the IP-CHA to treat various bony defects in orthopaedic surgery, and radiographic examinations demonstrated that grafted IP-CHA gained radiopacity more quickly than the synthetic HA in clinical use previously. We review the accumulated data on bone tissue engineering using the novel scaffold and on clinical application in the orthopaedic field. PMID:19106069

  11. Methods for removing contaminant matter from a porous material

    Science.gov (United States)

    Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

    2010-11-16

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  12. Teaching materials science and engineering

    Indian Academy of Sciences (India)

    Abstract. This paper is written with the intention of simulating discussion on teaching materials science and engineering in the universities. The article illustrates the tasks, priorities, goals and means lying ahead in the teaching of materials science and engineering for a sustainable future.

  13. Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

    Directory of Open Access Journals (Sweden)

    Marynowicz Andrzej

    2016-06-01

    Full Text Available The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples’ surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

  14. Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

    Science.gov (United States)

    Marynowicz, Andrzej

    2016-06-01

    The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples' surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

  15. Synthesis, Characterization and Application of Multiscale Porous Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hussami, Linda

    2010-07-01

    This thesis work brings fresh insights and improved understanding of nano scale materials through introducing new hybrid composites, 2D hexagonal in MCM-41 and 3D random interconnected structures of different materials, and application relevance for developing fields of science, such as fuel cells and solar cells. New types of porous materials and organometallic crystals have been prepared and characterized in detail. The porous materials have been used in several studies: as hosts to encapsulate metal-organic complexes; as catalyst supports and electrode materials in devices for alternative energy production. The utility of the new porous materials arises from their unique structural and surface chemical characteristics as demonstrated here using various experimental and theoretical approaches. New single crystal structures and arene-ligand exchange properties of f-block elements coordinated to ligand arene and halogallates are described in Paper I. These compounds have been incorporated into ordered 2D-hexagonal MCM-41 and polyhedral silica nano foam (PNF-SiO{sub 2}) matrices without significant change to the original porous architectures as described in Paper II and III. The resulting inorganic/organic hybrids exhibited enhanced luminescence activity relative to the pure crystalline complexes. A series of novel polyhedral carbon nano foams (PNF-C's) and inverse foams were prepared by nano casting from PNF-SiO{sub 2}'s. These are discussed in Paper IV. The synthesis conditions of PNF-C's were systematically varied as a function of the filling ratio of carbon precursor and their structures compared using various characterization methods. The carbonaceous porous materials were further tested in Paper V and VI as possible catalysts and catalyst supports in counter- and working electrodes for solar- and fuel cell applications

  16. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    International Nuclear Information System (INIS)

    Zeng, Chao; Yang, Qiang; Zhu, Meifeng; Du, Lilong; Zhang, Jiamin; Ma, Xinlong; Xu, Baoshan; Wang, Lianyong

    2014-01-01

    Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38 ± 5.12% and pore size of 165.00 ± 8.25 μm as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell–scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus

  17. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao; Yang, Qiang [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhu, Meifeng [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Du, Lilong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhang, Jiamin [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ma, Xinlong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Xu, Baoshan, E-mail: xubaoshan99@126.com [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Wang, Lianyong, E-mail: wly@nankai.edu.cn [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-04-01

    Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38 ± 5.12% and pore size of 165.00 ± 8.25 μm as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell–scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus.

  18. Statistical Inference for Porous Materials using Persistent Homology.

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Chul [Univ. of Georgia, Athens, GA (United States); Heath, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Scott A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    We propose a porous materials analysis pipeline using persistent homology. We rst compute persistent homology of binarized 3D images of sampled material subvolumes. For each image we compute sets of homology intervals, which are represented as summary graphics called persistence diagrams. We convert persistence diagrams into image vectors in order to analyze the similarity of the homology of the material images using the mature tools for image analysis. Each image is treated as a vector and we compute its principal components to extract features. We t a statistical model using the loadings of principal components to estimate material porosity, permeability, anisotropy, and tortuosity. We also propose an adaptive version of the structural similarity index (SSIM), a similarity metric for images, as a measure to determine the statistical representative elementary volumes (sREV) for persistence homology. Thus we provide a capability for making a statistical inference of the uid ow and transport properties of porous materials based on their geometry and connectivity.

  19. Characterization of porous materials by small-angle scattering

    Indian Academy of Sciences (India)

    With the availability of ultra small-angle scattering instruments, one can investigate porous materials in the sub-micron length scale. Because of the increased accessible length scale vis-a-vis the multiple scattering effect, conventional data analysis procedures based on single scattering approximation quite often fail.

  20. Computer design of porous active materials at different dimensional scales

    Science.gov (United States)

    Nasedkin, Andrey

    2017-12-01

    The paper presents a mathematical and computer modeling of effective properties of porous piezoelectric materials of three types: with ordinary porosity, with metallized pore surfaces, and with nanoscale porosity structure. The described integrated approach includes the effective moduli method of composite mechanics, simulation of representative volumes, and finite element method.

  1. Salinization effects on the water sorption of porous building materials

    NARCIS (Netherlands)

    Brocken, H.J.P.; Rook, W.; Adan, O.C.G.

    1999-01-01

    The interaction of salt transport and moisture transport plays a crucial role in some deterioration mechanisms of porous building materials. For this reason it has been an important research subject for mant' years. Yet most research was still complicated by the lack of experimental techniques

  2. Towards a more effective and reliable salt crystallization test for porous building materials: state of the art

    Czech Academy of Sciences Publication Activity Database

    Lubelli, B.; Cnudde, V.; Diaz-Goncalves, T.; Franzoni, E.; van Hees, R.; Ioannou, I.; Menéndez, B.; Nunes, Cristiana Lara; Siedel, H.; Stefanidou, M.; Verges-Belmin, V.; Viles, H.

    2018-01-01

    Roč. 51, č. 2 (2018), č. článku 55. ISSN 1359-5997 Keywords : literature review * salt damage * salt crystallization test * porous materials * RILEM Subject RIV: AL - Art, Architecture, Cultural Heritage OBOR OECD: Materials engineering Impact factor: 2.607, year: 2016 https://link.springer.com/article/10.1617/s11527-018-1180-5

  3. Numerical study of heat transfer and combustion in IC engine with a porous media piston region

    International Nuclear Information System (INIS)

    Zhou, Lei; Xie, Mao-Zhao; Luo, Kai Hong

    2014-01-01

    Based on superadiabatic combustion in porous medium (PM), the porous medium engine as a new combustion concept is proposed to achieve high combustion efficiency and low emissions. In this paper, an axisymmetric model with detailed chemistry and two-temperature treatment is implemented into a variant of the KIVA-3V code to simulate the working process of the PM engine. Comparisons with the same engine but without PM are conducted. Temperature evolution of the PM and its effects are discussed in detail. Key factors affecting heat transfer, combustion and emissions of the PM engine, such as porosity, the initial PM temperature and equivalence ratio, are analyzed. The results show that the characteristics of heat transfer, emissions and combustion of the PM engine are superior to the engine without PM, providing valuable support for the PM engine concept. In particular, the PM engine is shown to sustain ultra lean combustion. - Graphical abstract: In the PM engine, a PM reactor is mounted on the piston head as shown in Fig. 1 which shows the schematic diagram of the computational domain. The heat exchange process between PM material and compressed air increases with upward motion of piston at compression stroke. At the TDC, almost all the air is compressed and closed to PM volume, meanwhile, the fuel is injected into PM chamber to achieve homogenization combustion. - Highlights: •Two-temperature treatment studies the working process of the PM engine. •Self-balancing temperature of the PM determines the continued and stable work. •Stronger heat exchange occurs between gas and PM with smaller porosity. •The PM engine can have lower levels of NO x , unburnt HC and CO emissions

  4. Micropore engineering of carbonized porous aromatic framework (PAF-1) for supercapacitors application.

    Science.gov (United States)

    Li, Yanqiang; Roy, Soumyajit; Ben, Teng; Xu, Shixian; Qiu, Shilun

    2014-07-07

    Micropore engineering of porous carbons on the effect of capacitance was explored using a carbonized porous aromatic framework (PAF-1). The porous carbons obtained through different carbonization methods show different pore structures enabling us to do this. The capacitance was measured both in aqueous electrolyte and different organic electrolytes. The porous carbons prepared by KOH activation show both high microporous volume, which is beneficial for charge storage, and mesoporous volume, which is devoted to fast ion diffusion in the pores; properties which are highly desirable. It shows a capacitance as high as 280 F g(-1) and 203 F g(-1) at a current density of 1 A g(-1) in 6.0 M KOH and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI), respectively. We also demonstrate the effect of diffusion and that of geometric packing of the electrolyte ions in the pores, where a commensurate match of the electrolyte ions with the pores of carbonized materials control and influence significantly the capacitance of these materials.

  5. Thermodynamic Damping in Porous Materials with Spherical Cavities

    Directory of Open Access Journals (Sweden)

    Sofia D. Panteliou

    1997-01-01

    Full Text Available When a material is subjected to an alternating stress field, there are temperature fluctuations throughout its volume due to the thermoelastic effect. The resulting irreversible heat conduction leads to entropy production that in turn is the cause of thermoelastic damping. An analytical investigation of the entropy produced during a vibration cycle due to the reciprocity of temperature rise and strain yielded the change of the material damping factor as a function of the porosity of the material. A homogeneous, isotropic, elastic bar of cylindrical shape is considered with uniformly distributed spherical cavities under alternating uniform axial stress. The analytical calculation of the dynamic characteristics of the porous structure yielded the damping factor of the bar and the material damping factor. Exsperimental results on porous metals are in good correlation with an analysis.

  6. Global sensitivity analysis of multiscale properties of porous materials

    Science.gov (United States)

    Um, Kimoon; Zhang, Xuan; Katsoulakis, Markos; Plechac, Petr; Tartakovsky, Daniel M.

    2018-02-01

    Ubiquitous uncertainty about pore geometry inevitably undermines the veracity of pore- and multi-scale simulations of transport phenomena in porous media. It raises two fundamental issues: sensitivity of effective material properties to pore-scale parameters and statistical parameterization of Darcy-scale models that accounts for pore-scale uncertainty. Homogenization-based maps of pore-scale parameters onto their Darcy-scale counterparts facilitate both sensitivity analysis (SA) and uncertainty quantification. We treat uncertain geometric characteristics of a hierarchical porous medium as random variables to conduct global SA and to derive probabilistic descriptors of effective diffusion coefficients and effective sorption rate. Our analysis is formulated in terms of solute transport diffusing through a fluid-filled pore space, while sorbing to the solid matrix. Yet it is sufficiently general to be applied to other multiscale porous media phenomena that are amenable to homogenization.

  7. Cellular and Porous Materials Thermal Properties Simulation and Prediction

    CERN Document Server

    Öchsner, Andreas; de Lemos, Marcelo J S

    2008-01-01

    Providing the reader with a solid understanding of the fundamentals as well as an awareness of recent advances in properties and applications of cellular and porous materials, this handbook and ready reference covers all important analytical and numerical methods for characterizing and predicting thermal properties. In so doing it directly addresses the special characteristics of foam-like and hole-riddled materials, combining theoretical and experimental aspects for characterization purposes.

  8. Materials engineering data base

    Science.gov (United States)

    1995-01-01

    The various types of materials related data that exist at the NASA Marshall Space Flight Center and compiled into databases which could be accessed by all the NASA centers and by other contractors, are presented.

  9. Molecular Engineering of dosimetric materials

    International Nuclear Information System (INIS)

    Salas, P.; Castano, V.M.; Mendoza, D.; Gonzalez, P.

    1999-01-01

    It was studied the thermoluminescent response to the gamma radiation of a new family of solid materials of zircon-silica. In this study some materials have been prepared by the sol-gel method with different stoichiometric relations, finding that it is possible to control, at least, partially, the thermoluminescent behavior starting from the Molecular Engineering of those materials, since the mixture of both ceramics allows to produce materials with different spatial structures. (Author)

  10. Novel polymeric nanocomposites and porous materials prepared using organogels

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Wei-Chi; Tseng, Shen-Chen, E-mail: wclai@mail.tku.edu.t [Department of Chemical and Materials Engineering, Tamkang University, 151 Ying-chuan Road, Tamsui, Taipei 25137, Taiwan (China)

    2009-11-25

    We propose a new method for preparing polymeric nanocomposites and porous materials using self-assembled templates formed by 1,3:2,4-dibenzylidene sorbitol (DBS) organogels. DBS is capable of self-assembling into a 3D nanofibrillar network at relatively low concentrations in some organic solvents to produce organogels. In this study, we induced the formation of such physical cross-linked networks in styrene. Subsequently, we polymerized the styrene in the presence of chemical cross-linkers, divinyl benzene (DVB), with different amounts of DBS using thermal-initiated polymerization. The resulting materials were transparent, homogeneous polystyrene (PS) nanocomposites with both physical and chemical cross-links. The porous polymeric materials were obtained by solvent extraction of the DBS nanofibrils from the PS. Brunauer-Emmett-Teller (BET) measurements show that the amounts of DBS and DVB influenced the specific surface area after the removal of the DBS fibrils.

  11. Artificial 3D hierarchical and isotropic porous polymeric materials

    KAUST Repository

    Chisca, Stefan; Musteata, Valentina-Elena; Sougrat, Rachid; Behzad, Ali Reza; Nunes, Suzana Pereira

    2018-01-01

    Hierarchical porous materials that replicate complex living structures are attractive for a wide variety of applications, ranging from storage and catalysis to biological and artificial systems. However, the preparation of structures with a high level of complexity and long-range order at the mesoscale and microscale is challenging. We report a simple, nonextractive, and nonreactive method used to prepare three-dimensional porous materials that mimic biological systems such as marine skeletons and honeycombs. This method exploits the concurrent occurrence of the self-assembly of block copolymers in solution and macrophase separation by nucleation and growth. We obtained a long-range order of micrometer-sized compartments. These compartments are interconnected by ordered cylindrical nanochannels. The new approach is demonstrated using polystyrene-b-poly(t-butyl acrylate), which can be further explored for a broad range of applications, such as air purification filters for viruses and pollution particle removal or growth of bioinspired materials for bone regeneration.

  12. Novel polymeric nanocomposites and porous materials prepared using organogels

    International Nuclear Information System (INIS)

    Lai, Wei-Chi; Tseng, Shen-Chen

    2009-01-01

    We propose a new method for preparing polymeric nanocomposites and porous materials using self-assembled templates formed by 1,3:2,4-dibenzylidene sorbitol (DBS) organogels. DBS is capable of self-assembling into a 3D nanofibrillar network at relatively low concentrations in some organic solvents to produce organogels. In this study, we induced the formation of such physical cross-linked networks in styrene. Subsequently, we polymerized the styrene in the presence of chemical cross-linkers, divinyl benzene (DVB), with different amounts of DBS using thermal-initiated polymerization. The resulting materials were transparent, homogeneous polystyrene (PS) nanocomposites with both physical and chemical cross-links. The porous polymeric materials were obtained by solvent extraction of the DBS nanofibrils from the PS. Brunauer-Emmett-Teller (BET) measurements show that the amounts of DBS and DVB influenced the specific surface area after the removal of the DBS fibrils.

  13. Artificial 3D hierarchical and isotropic porous polymeric materials

    KAUST Repository

    Chisca, Stefan

    2018-05-11

    Hierarchical porous materials that replicate complex living structures are attractive for a wide variety of applications, ranging from storage and catalysis to biological and artificial systems. However, the preparation of structures with a high level of complexity and long-range order at the mesoscale and microscale is challenging. We report a simple, nonextractive, and nonreactive method used to prepare three-dimensional porous materials that mimic biological systems such as marine skeletons and honeycombs. This method exploits the concurrent occurrence of the self-assembly of block copolymers in solution and macrophase separation by nucleation and growth. We obtained a long-range order of micrometer-sized compartments. These compartments are interconnected by ordered cylindrical nanochannels. The new approach is demonstrated using polystyrene-b-poly(t-butyl acrylate), which can be further explored for a broad range of applications, such as air purification filters for viruses and pollution particle removal or growth of bioinspired materials for bone regeneration.

  14. Artificial 3D hierarchical and isotropic porous polymeric materials.

    Science.gov (United States)

    Chisca, Stefan; Musteata, Valentina-Elena; Sougrat, Rachid; Behzad, Ali Reza; Nunes, Suzana P

    2018-05-01

    Hierarchical porous materials that replicate complex living structures are attractive for a wide variety of applications, ranging from storage and catalysis to biological and artificial systems. However, the preparation of structures with a high level of complexity and long-range order at the mesoscale and microscale is challenging. We report a simple, nonextractive, and nonreactive method used to prepare three-dimensional porous materials that mimic biological systems such as marine skeletons and honeycombs. This method exploits the concurrent occurrence of the self-assembly of block copolymers in solution and macrophase separation by nucleation and growth. We obtained a long-range order of micrometer-sized compartments. These compartments are interconnected by ordered cylindrical nanochannels. The new approach is demonstrated using polystyrene- b -poly( t -butyl acrylate), which can be further explored for a broad range of applications, such as air purification filters for viruses and pollution particle removal or growth of bioinspired materials for bone regeneration.

  15. FEATURES OF RESTORATION OF DISPERSE POROUS MATERIALS

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2016-01-01

    Full Text Available The article presents the results of research recycling of dispersed materials in rotary furnaces. Has been received new data on the of heat and mass transfer processes and carry out intensive and continuous process of solid- liquid-phase reduction of oxides in a single unit.

  16. Porous silicon based anode material formed using metal reduction

    Science.gov (United States)

    Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

    2015-09-22

    A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

  17. Disorder-induced stiffness degradation of highly disordered porous materials

    Science.gov (United States)

    Laubie, Hadrien; Monfared, Siavash; Radjaï, Farhang; Pellenq, Roland; Ulm, Franz-Josef

    2017-09-01

    The effective mechanical behavior of multiphase solid materials is generally modeled by means of homogenization techniques that account for phase volume fractions and elastic moduli without considering the spatial distribution of the different phases. By means of extensive numerical simulations of randomly generated porous materials using the lattice element method, the role of local textural properties on the effective elastic properties of disordered porous materials is investigated and compared with different continuum micromechanics-based models. It is found that the pronounced disorder-induced stiffness degradation originates from stress concentrations around pore clusters in highly disordered porous materials. We identify a single disorder parameter, φsa, which combines a measure of the spatial disorder of pores (the clustering index, sa) with the pore volume fraction (the porosity, φ) to scale the disorder-induced stiffness degradation. Thus, we conclude that the classical continuum micromechanics models with one spherical pore phase, due to their underlying homogeneity assumption fall short of addressing the clustering effect, unless additional texture information is introduced, e.g. in form of the shift of the percolation threshold with disorder, or other functional relations between volume fractions and spatial disorder; as illustrated herein for a differential scheme model representative of a two-phase (solid-pore) composite model material.

  18. Mechanical engineers' handbook, materials and engineering mechanics

    CERN Document Server

    Kutz, Myer

    2015-01-01

    Full coverage of materials and mechanical design inengineering Mechanical Engineers' Handbook, Fourth Edition provides aquick guide to specialized areas you may encounter in your work,giving you access to the basics of each and pointing you towardtrusted resources for further reading, if needed. The accessibleinformation inside offers discussions, examples, and analyses ofthe topics covered. This first volume covers materials and mechanical design, givingyou accessible and in-depth access to the most common topics you'llencounter in the discipline: carbon and alloy steels, stainlesssteels, a

  19. Zeolitic materials with hierarchical porous structures.

    Science.gov (United States)

    Lopez-Orozco, Sofia; Inayat, Amer; Schwab, Andreas; Selvam, Thangaraj; Schwieger, Wilhelm

    2011-06-17

    During the past several years, different kinds of hierarchical structured zeolitic materials have been synthesized due to their highly attractive properties, such as superior mass/heat transfer characteristics, lower restriction of the diffusion of reactants in the mesopores, and low pressure drop. Our contribution provides general information regarding types and preparation methods of hierarchical zeolitic materials and their relative advantages and disadvantages. Thereafter, recent advances in the preparation and characterization of hierarchical zeolitic structures within the crystallites by post-synthetic treatment methods, such as dealumination or desilication; and structured devices by in situ and ex situ zeolite coatings on open-cellular ceramic foams as (non-reactive as well as reactive) supports are highlighted. Specific advantages of using hierarchical zeolitic catalysts/structures in selected catalytic reactions, such as benzene to phenol (BTOP) and methanol to olefins (MTO) are presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Materials Science & Engineering | Classification | College of Engineering &

    Science.gov (United States)

    Biomedical Engineering Concentration on Ergonomics M.S. Program in Computer Science Interdisciplinary Concentration on Energy Doctoral Programs in Engineering Non-Degree Candidate Departments Biomedical Engineering Biomedical Engineering Industry Advisory Council Civil & Environmental Engineering Civil &

  1. Recent Advances in Porous Carbon Materials for Electrochemical Energy Storage.

    Science.gov (United States)

    Wang, Libin; Hu, Xianluo

    2018-06-18

    Climate change and the energy crisis have promoted the rapid development of electrochemical energy-storage devices. Owing to many intriguing physicochemical properties, such as excellent chemical stability, high electronic conductivity, and a large specific surface area, porous carbon materials have always been considering as a promising candidate for electrochemical energy storage. To date, a wide variety of porous carbon materials based upon molecular design, pore control, and compositional tailoring have been proposed for energy-storage applications. This focus review summarizes recent advances in the synthesis of various porous carbon materials from the view of energy storage, particularly in the past three years. Their applications in representative electrochemical energy-storage devices, such as lithium-ion batteries, supercapacitors, and lithium-ion hybrid capacitors, are discussed in this review, with a look forward to offer some inspiration and guidelines for the exploitation of advanced carbon-based energy-storage materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Dynamics of Liquids Confined in Porous Materials

    DEFF Research Database (Denmark)

    Berg, Marcella Cabrera

    mobility of the hydrogen atoms, mostly from water, present in conventional GIC. Water plays a big part in the setting process in GIC. It is the reaction medium in which the cations leach to crosslink. Furthermore, water also hydrates the siliceous hydrogel and the metal polyacrylate salts. In matured GIC...... dynamics in such complex hierarchical structure, where different motions occur in a broad range of time scales and simultaneously, can be difficult. So in this Ph.D. thesis, the experimental data was combined with preliminary classical molecular dynamics simulations (MD), aiming to investigate...... the different nanoscale water dynamics in the GIC. This unique approach opens new possibilities to better explore all the information contained in the neutron spectroscopy data. Selected materials were investigated by first understanding the molecular motions of the different aqueous polyacrylic acid solutions...

  3. Sorption and migration of neptunium in porous sedimentary materials

    International Nuclear Information System (INIS)

    Tanaka, Tadao; Mukai, Masayuki; Nakayama, Shinichi

    2005-01-01

    Column migration experiments of neptunium were conducted for porous sedimentary materials: coastal sand, tuffaceous sand, ando soil, reddish soil, yellowish soil and loess, and migration behavior, sorption mechanisms and chemical formation of Np were investigated. The migration behavior of Np in each material was much different each other, due to chemical formation in solution and/or sorption mechanism of Np. Mathematical models of different concepts were applied to the experimental results to interpret the sorption mechanism and the migration behavior. It can be concluded that both of instantaneous equilibrium sorption and sorption-desorption kinetics have to be considered to model the Np migration in sedimentary materials. (author)

  4. A novel porous scaffold fabrication technique for epithelial and endothelial tissue engineering.

    Science.gov (United States)

    McHugh, Kevin J; Tao, Sarah L; Saint-Geniez, Magali

    2013-07-01

    Porous scaffolds have the ability to minimize transport barriers for both two- (2D) and three-dimensional tissue engineering. However, current porous scaffolds may be non-ideal for 2D tissues such as epithelium due to inherent fabrication-based characteristics. While 2D tissues require porosity to support molecular transport, pores must be small enough to prevent cell migration into the scaffold in order to avoid non-epithelial tissue architecture and compromised function. Though electrospun meshes are the most popular porous scaffolds used today, their heterogeneous pore size and intense topography may be poorly-suited for epithelium. Porous scaffolds produced using other methods have similar unavoidable limitations, frequently involving insufficient pore resolution and control, which make them incompatible with 2D tissues. In addition, many of these techniques require an entirely new round of process development in order to change material or pore size. Herein we describe "pore casting," a fabrication method that produces flat scaffolds with deterministic pore shape, size, and location that can be easily altered to accommodate new materials or pore dimensions. As proof-of-concept, pore-cast poly(ε-caprolactone) (PCL) scaffolds were fabricated and compared to electrospun PCL in vitro using canine kidney epithelium, human colon epithelium, and human umbilical vein endothelium. All cell types demonstrated improved morphology and function on pore-cast scaffolds, likely due to reduced topography and universally small pore size. These results suggest that pore casting is an attractive option for creating 2D tissue engineering scaffolds, especially when the application may benefit from well-controlled pore size or architecture.

  5. Modeling of heat transfer within porous multi-constituent materials

    International Nuclear Information System (INIS)

    Niezgoda, M.

    2012-01-01

    The CEA works a great deal with porous materials - carbon composites, ceramics - and aims to optimize their properties for specific uses. These materials can be composed of several constituents and generally has a complex structure with pore size of several tens of micrometers. It is used in large-scale systems that are bigger than its own characteristic scale in which they are considered as equivalent to a homogeneous medium for the simulation of its behavior in its using environment without taking into account its local morphology. We are especially interested in the effective thermal diffusivity of heterogeneous materials that we estimate as a function of temperature with the help of an inverse method by considering they are homogeneous. The identification of the diffusivity of porous and/or semi-transparent materials is made difficult because of the strong conducto-radiative coupling can quickly occur when the temperature increases. We have thus modeled the coupled conductive and radiative heat transfer as a function of the temperature within porous multi-constituent materials from their morphology discretized into a set of homogeneous voxels. We have developed a methodology that consists in starting from a 3D-microstructure of the studied materials obtained by tomography. The microstructures constitute the numerical support to this modeling that renders it possible, on the one hand, to simulate any kind of numerical thermal experiments, especially the flash method whose the results render it possible to estimate the thermal diffusivity, and on the other hand, to reproduce the thermal behavior of our materials in their using conditions. (author) [fr

  6. Zirconia-hydroxyapatite composite material with micro porous structure.

    Science.gov (United States)

    Matsumoto, Takuya Junior; An, Sang-Hyun; Ishimoto, Takuya; Nakano, Takayoshi; Matsumoto, Takuya; Imazato, Satoshi

    2011-11-01

    Titanium plates and apatite blocks are commonly used for restoring large osseous defects in dental and orthopedic surgery. However, several cases of allergies against titanium have been recently reported. Also, sintered apatite block does not possess sufficient mechanical strength. In this study, we attempted to fabricate a composite material that has mechanical properties similar to biocortical bone and high bioaffinity by compounding hydroxyapatite (HAp) with the base material zirconia (ZrO(2)), which possesses high mechanical properties and low toxicity toward living organisms. After mixing the raw material powders at several different ZrO(2)/HAp mixing ratios, the material was compressed in a metal mold (8 mm in diameter) at 5 MPa. Subsequently, it was sintered for 5 h at 1500°C to obtain the ZrO(2)/HAp composite. The mechanical property and biocompatibility of materials were investigated. Furthermore, osteoconductivity of materials was investigated by animal studies. A composite material with a minute porous structure was successfully created using ZrO(2)/HAp powders, having different particle sizes, as the starting material. The material also showed high protein adsorption and a favorable cellular affinity. When the mixing ratio was ZrO(2)/HAp=70/30, the strength was equal to cortical bone. Furthermore, in vivo experiments confirmed its high osteoconductivity. The composite material had strength similar to biocortical bones with high cell and tissue affinities by compounding ZrO(2) and HAp. The ZrO(2)/HAp composite material having micro porous structure would be a promising bone restorative material. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Multiscale modelling for better hygrothermal prediction of porous building materials

    Directory of Open Access Journals (Sweden)

    Belarbi Rafik

    2018-01-01

    Full Text Available The aim of this work is to understand the influence of the microstructuralgeometric parameters of porous building materials on the mechanisms of coupled heat, air and moisture transfers, in order to predict behavior of the building to control and improve it in its durability. For this a multi-scale approach is implemented. It consists of mastering the dominant physical phenomena and their interactions on the microscopic scale. Followed by a dual-scale modelling, microscopic-macroscopic, of coupled heat, air and moisture transfers that takes into account the intrinsic properties and microstructural topology of the material using X-ray tomography combined with the correlation of 3D images were undertaken. In fact, the hygromorphicbehavior under hydric solicitations was considered. In this context, a model of coupled heat, air and moisture transfer in porous building materials was developed using the periodic homogenization technique. These informations were subsequently implemented in a dynamic computation simulation that model the hygrothermalbehaviourof material at the scale of the envelopes and indoor air quality of building. Results reveals that is essential to consider the local behaviors of materials, but also to be able to measure and quantify the evolution of its properties on a macroscopic scale from the youngest age of the material. In addition, comparisons between experimental and numerical temperature and relative humidity profilesin multilayers wall and in building envelopes were undertaken. Good agreements were observed.

  8. Analytical and numerical models of transport in porous cementitious materials

    International Nuclear Information System (INIS)

    Garboczi, E.J.; Bentz, D.P.

    1990-01-01

    Most chemical and physical processes that degrade cementitious materials are dependent on an external source of either water or ions or both. Understanding the rates of these processes at the microstructural level is necessary in order to develop a sound scientific basis for the prediction and control of the service life of cement-based materials, especially for radioactive-waste containment materials that are required to have service lives on the order of hundreds of years. An important step in developing this knowledge is to understand how transport coefficients, such as diffusivity and permeability, depend on the pore structure. Fluid flow under applied pressure gradients and ionic diffusion under applied concentration gradients are important transport mechanisms that take place in the pore space of cementitious materials. This paper describes: (1) a new analytical percolation-theory-based equation for calculating the permeability of porous materials, (2) new computational methods for computing effective diffusivities of microstructural models or digitized images of actual porous materials, and (3) a new digitized-image mercury intrusion simulation technique

  9. 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.

  10. Carbon Nanotube Templated Microfabrication of Porous Silicon-Carbon Materials

    Science.gov (United States)

    Song, Jun; Jensen, David; Dadson, Andrew; Vail, Michael; Linford, Matthew; Vanfleet, Richard; Davis, Robert

    2010-10-01

    Carbon nanotube templated microfabrication (CNT-M) of porous materials is demonstrated. Partial chemical infiltration of three dimensional carbon nanotube structures with silicon resulted in a mechanically robust material, precisely structured from the 10 nm scale to the 100 micron scale. Nanoscale dimensions are determined by the diameter and spacing of the resulting silicon/carbon nanotubes while the microscale dimensions are controlled by lithographic patterning of the CNT growth catalyst. We demonstrate the utility of this hierarchical structuring approach by using CNT-M to fabricate thin layer chromatography (TLC) separations media with precise microscale channels for fluid flow control and nanoscale porosity for high analyte capacity.

  11. Preparation and Gas Adsorption of Porous Materials from Molecular Precursors

    DEFF Research Database (Denmark)

    Hu, Xinming

    with bimodal porosity are produced via cyclotrimerization of two aromatic tetranitriles and in situ carbonization in molten ZnCl2. The carbonization occurs by decomposition of triazine rings, which results in complete loss of nitrogen and formation of substantial mesopores. The resulting materials possess...... surface areas above 1200 m2 g−1 and exhibit exceptionally high H2 uptake (up to 2.34 wt% at 77 K and 1 bar) but low CO2 uptake capacity. In Chapter 4, a nitrogen-rich porous carbon is prepared via cyclotrimerization of a perfluorinated aromatic nitrile and in situ carbonization in molten ZnCl2......), and H2 (2.0 wt%, 77 K and 1.0 bar). Chapters 5, 6, and 7 deal with the construction of triazatriangulenium (TATA)-based ionic porous frameworks. A variety of polycondensation reactions have been applied, but only FeCl3-promoted oxidative polymerization of thiophene-/carbazolefunctionalized TATAs...

  12. Ceramic porous material and method of making same

    Science.gov (United States)

    Liu, Jun; Kim, Anthony Y.; Virden, Jud W.

    1997-01-01

    The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors.

  13. Structural control in the synthesis of inorganic porous materials

    Science.gov (United States)

    Holland, Brian Thomas

    Mesoporous (2.0--50.0 nm pore diameter) and macroporous (50.0 nm on up) materials have been the basis of my studies. These materials, for many years, possessed large pore size distributions. Recently, however, it has been possible to synthesize both mesoporous and macroporous materials that possess highly ordered uniform pores throughout the material. Workers at Mobil Corporation in 1992 discovered a hexagonally arrayed mesoporous material, designated MCM-41, which exhibited uniform pores ranging from 2.0--10.0 nm in diameter. In my work MCM-41 was used as a host for the incorporation of meso-tetrakis(5-trimethylammoniumpentyl)porphyrin (TMAP-Cl) and as a model for the synthesis of mesoporous alumino- and galloaluminophosphates which were created using cluster precursors of the type MO4Al 12(OH)24(H2O)12 7+, M = Al or Ga. Macroporous materials with uniform pore sizes have been synthesized by our group with frameworks consisting of a variety of metal oxides, metals, organosilanes, aluminophosphates and bimodal pores. These materials are synthesized from the addition of metal precursors to preordered polystyrene spheres. Removal of the spheres results in the formation of macropores with highly uniform pores extending microns in length. Porous materials with uniform and adjustable pore sizes in the mesoporous and macroporous size regimes offer distinct advantages over non-ordered materials for numerous reasons. First, catalysis reactions that are based on the ability of the porous materials to impose size and shape restrictions on the substrate are of considerable interest in the petroleum and petrochemical industries. As pore diameters increase larger molecules can be incorporated into the pores, i.e., biological molecules, dyes, etc. For the macroporous materials synthesized by our group it has been envisioned that these structures may not only be used for catalysis because of increased efficiencies of flow but for more advanced applications, e.g., photonic crystals

  14. Intrinsic Osteoinductivity of Porous Titanium Scaffold for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Maryam Tamaddon

    2017-01-01

    Full Text Available Large bone defects and nonunions are serious complications that are caused by extensive trauma or tumour. As traditional therapies fail to repair these critical-sized defects, tissue engineering scaffolds can be used to regenerate the damaged tissue. Highly porous titanium scaffolds, produced by selective laser sintering with mechanical properties in range of trabecular bone (compressive strength 35 MPa and modulus 73 MPa, can be used in these orthopaedic applications, if a stable mechanical fixation is provided. Hydroxyapatite coatings are generally considered essential and/or beneficial for bone formation; however, debonding of the coatings is one of the main concerns. We hypothesised that the titanium scaffolds have an intrinsic potential to induce bone formation without the need for a hydroxyapatite coating. In this paper, titanium scaffolds coated with hydroxyapatite using electrochemical method were fabricated and osteoinductivity of coated and noncoated scaffolds was compared in vitro. Alizarin Red quantification confirmed osteogenesis independent of coating. Bone formation and ingrowth into the titanium scaffolds were evaluated in sheep stifle joints. The examinations after 3 months revealed 70% bone ingrowth into the scaffold confirming its osteoinductive capacity. It is shown that the developed titanium scaffold has an intrinsic capacity for bone formation and is a suitable scaffold for bone tissue engineering.

  15. Mobility of engineered inorganic nanoparticles in porous media

    Science.gov (United States)

    Metreveli, George; Heidmann, Ilona; Schaumann, Gabriele Ellen

    2013-04-01

    Besides the excellent properties and great potential for various industrial, medical, pharmaceutical, cosmetic, and life science applications, engineered inorganic nanoparticles (EINP) can show also disadvantages concerning increasing risk potential with increasing application, if they are released in the environmental systems. EINP can influence microbial activity and can show toxic effects (Fabrega et al., 2009). Similar to the inorganic natural colloids, EINP can be transported in soil and groundwater systems (Metreveli et al., 2005). Furthermore, due to the large surface area and high sorption and complex formation capacity, EINP can facilitate transport of different contaminants. In this study the mobility behaviour of EINP and their effect on the transport of different metal(loid) species in water saturated porous media was investigated. For these experiments laboratory column system was used. The column was filled with quartz sand. The interactions between EINP and metal(loid)s were characterised by coupling of asymmetrical flow field flow fractionation (AF4) with inductively coupled plasma mass spectrometer (ICP-MS). As EINP laponite (synthetic three layer clay mineral), and as metal(loid)s Cu, Pb, Zn, Pt and As were used. In AF4 experiments sorption of metal(loid)s on the surface of EINP could be observed. The extent of interactions was influenced by pH value and was different for different metal(loid)s. Laboratory column experiments showed high mobility of EINP, which facilitated transport of most of metal(loid)s in water saturated porous media. Furthermore the migration of synthetic silver nanoparticles in natural soil columns was determined in leaching experiments. Acknowledgement Financial support by German Research Council (DFG) and Max-Buchner-Research Foundation (MBFSt) is gratefully acknowledged. We thank Karlsruhe Institute of Technology (KIT) for the opportunity to perform the column and AF4 experiments. References: Fabrega, J., Fawcett, S. R

  16. Positronium formation in porous materials for antihydrogen production

    International Nuclear Information System (INIS)

    Ferragut, R; Calloni, A; Dupasquier, A; Consolati, G; Giammarchi, M G; Quasso, F; Trezzi, D; Egger, W; Ravelli, L; Petkov, M P; Jones, S M; Wang, B; Yaghi, O M; Jasinska, B; Chiodini, N; Paleari, A

    2010-01-01

    Positronium (Ps) formation measurements in several porous materials as: Vycor, germanate Xerogel, Metal-Organic Frameworks MOF-177 and Aerogel with two densities (20 and 150 mg/cm 3 ), were performed by means of a variable energy positron beam provided with a Ge detector and a positron lifetime spectrometer. An efficient formation of cooled Ps atoms is a requisite for the production of antihydrogen, with the aim of a direct measurement of the Earth gravitational acceleration g of antimatter, which is a primary scientific goal of AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). Porous materials are necessary to form a high yield of Ps atoms as well as to cool Ps through collisions with the inner walls of the pores. The different materials were characterized and produce Ps into the pores. Lifetime measurements give an estimation of the typical pores dimension of the substances. A comparative study of the positron lifetime and the Ps fraction values in the above mentioned materials indicates that silica Aerogel, with the appropriate density, is an excellent candidate for an efficient formation of cold Ps atoms for the AEGIS project.

  17. Porous Materials for Hydrolytic Dehydrogenation of Ammonia Borane

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2015-07-01

    Full Text Available Hydrogen storage is still one of the most significant issues hindering the development of a “hydrogen energy economy”. Ammonia borane is notable for its high hydrogen densities. For the material, one of the main challenges is to release efficiently the maximum amount of the stored hydrogen. Hydrolysis reaction is a promising process by which hydrogen can be easily generated from this compound. High purity hydrogen from this compound can be evolved in the presence of solid acid or metal based catalyst. The reaction performance depends on the morphology and/or structure of these materials. In this review, we survey the research on nanostructured materials, especially porous materials for hydrogen generation from hydrolysis of ammonia borane.

  18. Porous Materials for Hydrolytic Dehydrogenation of Ammonia Borane.

    Science.gov (United States)

    Umegaki, Tetsuo; Xu, Qiang; Kojima, Yoshiyuki

    2015-07-21

    Hydrogen storage is still one of the most significant issues hindering the development of a "hydrogen energy economy". Ammonia borane is notable for its high hydrogen densities. For the material, one of the main challenges is to release efficiently the maximum amount of the stored hydrogen. Hydrolysis reaction is a promising process by which hydrogen can be easily generated from this compound. High purity hydrogen from this compound can be evolved in the presence of solid acid or metal based catalyst. The reaction performance depends on the morphology and/or structure of these materials. In this review, we survey the research on nanostructured materials, especially porous materials for hydrogen generation from hydrolysis of ammonia borane.

  19. Sixth Israel materials engineering conference IMEC VI

    International Nuclear Information System (INIS)

    Anon.

    1993-02-01

    Works on material engineering are presented. The main material types are: metals, alloys, superalloys, coatings, ceramics, composites, electronic materials,organic polymers and thin films. The following engineering aspects are presented: metallurgy, mechanical and physical properties, crystal structure and corrosion

  20. Rapid prototyped porous titanium coated with calcium phosphate as a scaffold for bone tissue engineering.

    NARCIS (Netherlands)

    Lopez, M.A.; Sohier, J.; Gaillard, C.A.J.M.; Quillard, S.; Dorget, M.; Layrolle, P.

    2008-01-01

    High strength porous scaffolds and mesenchymal stem cells are required for bone tissue engineering applications. Porous titanium scaffolds (TiS) with a regular array of interconnected pores of 1000 microm in diameter and a porosity of 50% were produced using a rapid prototyping technique. A calcium

  1. Pseudocapacitive and hierarchically ordered porous electrode materials supercapacitors

    Science.gov (United States)

    Saruhan, B.; Gönüllü, Y.; Arndt, B.

    2013-05-01

    Commercially available double layer capacitors store energy in an electrostatic field. This forms in the form of a double layer by charged particles arranged on two electrodes consisting mostly of active carbon. Such double layer capacitors exhibit a low energy density, so that components with large capacity according to large electrode areas are required. Our research focuses on the development of new electrode materials to realize the production of electrical energy storage systems with high energy density and high power density. Metal oxide based electrodes increase the energy density and the capacitance by addition of pseudo capacitance to the static capacitance present by the double layer super-capacitor electrodes. The so-called hybrid asymmetric cell capacitors combine both types of energy storage in a single component. In this work, the production routes followed in our laboratories for synthesis of nano-porous and aligned metal oxide electrodes using the electrochemical and sputter deposition as well as anodization methods will be described. Our characterisation studies concentrate on electrodes having redox metal-oxides (e.g. MnOx and WOx) and hierarchically aligned nano-porous Li-doped TiO2-NTs. The material specific and electrochemical properties achieved with these electrodes will be presented.

  2. Porous graphene for high capacity lithium ion battery anode material

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yusheng, E-mail: xxwysheng@163.com [College of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhang, Qiaoli; Jia, Min; Yang, Dapeng [College of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); Wang, Jianjun; Li, Meng [College of Science, Zhongyuan University of Technology, Zhengzhou 450007 (China); Zhang, Jing [College of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); Sun, Qiang [School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Jia, Yu, E-mail: jiayu@zzu.edu.cn [School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China)

    2016-02-15

    Graphical abstract: - Highlights: • Porous graphene sheet as Li storage media. • Excellent mobility both along in-plane and out-plane directions. • The interactions can be easily tuned by an applied strain. - Abstract: Based on density functional theory calculations, we studied the Li dispersed on porous graphene (PG) for its application as Li ion battery anode material. The hybridization of Li atoms and the carbon atoms enhanced the interaction between Li atoms and the PG. With holes of specific size, the PG can provide excellent mobility with moderate barriers of 0.37–0.39 eV. The highest Li storage composite can be LiC{sub 0.75}H{sub 0.38} which corresponds to a specific capacity of 2857.7 mA h/g. Both specific capacity and binding energy are significantly larger than the corresponding value of graphite, this makes PG a promising candidate for the anode material in battery applications. The interactions between the Li atoms and PG can be easily tuned by an applied strain. Under biaxial strain of 16%, the binding energy of Li to PG is increased by 17% compared to its unstrained state.

  3. [RESEARCH PROGRESS OF THREE-DIMENSIONAL PRINTING POROUS SCAFFOLDS FOR BONE TISSUE ENGINEERING].

    Science.gov (United States)

    Wu, Tianqi; Yang, Chunxi

    2016-04-01

    To summarize the research progress of several three-dimensional (3-D)-printing scaffold materials in bone tissue engineering. The recent domestic and international articles about 3-D printing scaffold materials were reviewed and summarized. Compared with conventional manufacturing methods, 3-D printing has distinctive advantages, such as enhancing the controllability of the structure and increasing the productivity. In addition to the traditional metal and ceramic scaffolds, 3-D printing scaffolds carrying seeding cells and tissue factors as well as scaffolds filling particular drugs for special need have been paid more and more attention. The development of 3-D printing porous scaffolds have revealed new perspectives in bone repairing. But it is still at the initial stage, more basic and clinical researches are still needed.

  4. 3D printed porous ceramic scaffolds for bone tissue engineering: a review.

    Science.gov (United States)

    Wen, Yu; Xun, Sun; Haoye, Meng; Baichuan, Sun; Peng, Chen; Xuejian, Liu; Kaihong, Zhang; Xuan, Yang; Jiang, Peng; Shibi, Lu

    2017-08-22

    This study summarizes the recent research status and development of three-dimensional (3D)-printed porous ceramic scaffolds in bone tissue engineering. Recent literature on 3D-printed porous ceramic scaffolds was reviewed. Compared with traditional processing and manufacturing technologies, 3D-printed porous ceramic scaffolds have obvious advantages, such as enhancement of the controllability of the structure or improvement of the production efficiency. More sophisticated scaffolds were fabricated by 3D printing technology. 3D printed bioceramics have broad application prospects in bone tissue engineering. Through understanding the advantages and limitations of different 3D-printing approaches, new classes of bone graft substitutes can be developed.

  5. Metal-Matrix Composites and Porous Materials: Constitute Models, Microstructure Evolution and Applications

    National Research Council Canada - National Science Library

    Castafieda, P

    2000-01-01

    Constitutive models were developed and implemented numerically to account for the evolution of microstructure and anisotropy in finite-deformation processes involving porous and composite materials...

  6. System level permeability modeling of porous hydrogen storage materials.

    Energy Technology Data Exchange (ETDEWEB)

    Kanouff, Michael P.; Dedrick, Daniel E.; Voskuilen, Tyler (Purdue University, West Lafayette, IN)

    2010-01-01

    A permeability model for hydrogen transport in a porous material is successfully applied to both laboratory-scale and vehicle-scale sodium alanate hydrogen storage systems. The use of a Knudsen number dependent relationship for permeability of the material in conjunction with a constant area fraction channeling model is shown to accurately predict hydrogen flow through the reactors. Generally applicable model parameters were obtained by numerically fitting experimental measurements from reactors of different sizes and aspect ratios. The degree of channeling was experimentally determined from the measurements and found to be 2.08% of total cross-sectional area. Use of this constant area channeling model and the Knudsen dependent Young & Todd permeability model allows for accurate prediction of the hydrogen uptake performance of full-scale sodium alanate and similar metal hydride systems.

  7. An improved electrokinetic method to consolidate porous materials

    DEFF Research Database (Denmark)

    Feijoo, Jorge; Ottosen, Lisbeth M.; Nóvoa, X. R.

    2017-01-01

    the consolidation using commercial products have some limitations, such as: (1) low penetrability; (2) no chemical and mineralogical affinity with the material to treat and (3) release of toxic compounds (VOCs), during the solvent evaporation. In the last years, a new consolidation method based on electrokinetic...... the pH of the solutions in contact with the porous material, which can damage it and (2) it is difficult to determine in which area the consolidation takes place. In this study an electrokinetic consolidation method, which has two steps between which the current is reversed, is proposed to solve all...... techniques was developed. This method allows filling some pores by the precipitation of an inorganic compound. As a result the method allows increasing the penetration depth of current consolidation treatments. However, this method needs to be improved since: (1) no special care is taking in controlling...

  8. THE COMPLEX USE OF LOCAL TYPES OF FUEL IN THE POROUS CONSTRUCTION MATERIALS PRODUCTION

    Directory of Open Access Journals (Sweden)

    N. P. Voronova

    2014-01-01

    Full Text Available The article presents a comprehensive low-waste technology is the use of local fuels, which can be used in the technology of some porous building materials. Also provides new methods of preparation of porous building materials based on aggloporite using local fuels and waste energy on the basis of milled peat, fuel briquettes and wood chips allow to replace expensive imported components that comprise the raw mixtures (coal, anthracite.On the basis of mathematical modeling of cooling in reheat furnaces pusher drive developed a method of engineering calculation mode batch hardening in agglomeration. Submitted constructive solution for the development of the cooling charge with thermophysical rational justification cooling modes. A study of the temperature distribution within the charge depending on the different speeds of the belt sintering machine, and hence on the cooling time.The characteristics of the raw material deposits "Fanipol" and the optimal composition of the charge which includes loam, coal, milled peat. In industrial research obtained aggloporite this formulation has shown positive results in strength and density. Established that by decreasing the particle size of the fuel increases the redox potential of the combustion products, which reduces the height of the oxidizing zone and the speed of the sintering raw mix. These processes increase the productivity of sinter machine.Technology is implemented on the "Minsk factory of building materials". The tests analyzed production technology porous construction materials using milled peat with the addition of sawdust. The study results recommend further use of sapropel, which cost significantly lower raw material mixture of submissions and in their physical and mechanical properties much closer to the properties of milled peat.

  9. Improvements in or relating to method of preparing porous material/synthetic polymer composites

    International Nuclear Information System (INIS)

    Hills, P.R.; McGahan, D.J.

    1976-01-01

    A method for preparing a composite material is described comprising polymerising a monoethylenically unsaturated monomer of a mixture of copolymerisable monoethylenically unsaturated monomers in a porous material, excluding a porous natural cellulosic fibre material, the polymerisable liquid being admixed in the porous material with a saturated aliphatic hydrocarbon or a halogen derivative thereof. It is preferable that the polymerisable liquid and the hydrocarbon or halogen derivative are present in the porous material. Impregnation may be carried out by a vacuum technique or by simple immersion. The monomers that may be used are listed, but a mixture of styrene and acrylonitrile is preferred in the proportions 60 : 40 by volume. Polymerisation may be effected by irradiation, preferably with 60 Co γ-radiation. Suitable porous materials include concrete, stone, and fibreboard. If concrete is used the composite material may be used for pressure pipes and other articles normally made of steel. Examples of the application of the process are given. (U.K.)

  10. A new equation of state for porous materials with ultra-low densities

    CERN Document Server

    Geng Hua Yun; Wu Qiang

    2002-01-01

    A thermodynamic equation of state is derived which is appropriate for investigating the thermodynamic variations along isobaric paths to predict compression behaviours of porous materials. This equation-of-state model is tested on porous iron, copper, lead and tungsten with different initial densities. The calculated Hugoniots are in good agreement with the corresponding experimental data published previously. This shows that this model can satisfactorily predict the Hugoniots of porous materials with wide porosity and pressure ranges.

  11. Characterization of Lignocellulosic Biomass as Raw Material for the Production of Porous Carbon-based Materials

    Directory of Open Access Journals (Sweden)

    Saptadi Darmawan

    2016-02-01

    Full Text Available Lignocellulosic biomass is a potential raw material that can be used in the synthesis (manufacture of porous carbon stuffs. The properties of such porous carbon products are affected by the species of the raw material and the manufacturing process, among other things. This paper scrutinizes the related characteristics of lignocellulosic raw materials that indicate potential for the production of porous carbon. Three species were used: pine (Pinus merkusii wood, mangium (Acacia mangium wood, and candlenut (Aleurites moluccana shells, representing softwoods, hardwoods, and non-wood stuffs, respectively. Analyses of their chemical compounds and proximate contents were carried out. Additionally, nano scale scrutiny of the lignocellulosic biomass was also conducted using the nano capable instruments, which consisted of SEM, EDS, XRD, FTIR, and DSC. Results revealed that pine wood had the most potential to produce porous carbon. Morphologically, pine wood afforded the best permeability, whereby at the structure of monoclinic cellulose crystals, there were cellulose-I(alpha structures, which contained less cellulose-I(beta structures. Furthermore, pine wood exhibited greater volatile matter content, as confirmed through the FTIR, which greatly assisted the forming of porosity inside its corresponding carbon.

  12. Suitability of various materials for porous filters in diffusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Aldaba, David; Vidal, Miquel; Rigol, Anna [Univ. de Barcelona (Spain). Dept. de Quimica Analitica; Glaus, Martin; Van Loon, Luc [Paul Scherrer Institut, Villigen PSI (Switzerland). Lab. for Waste Management; Leupin, Olivier [Nagra, Wettingen (Switzerland)

    2014-10-01

    The suitability of different porous materials (stainless steel, VYCOR {sup registered} glass, Al{sub 2}O{sub 3} and PEEK) for use as confining filters in diffusion experiments was evaluated by measuring the effective diffusion coefficients (D{sub e}) of neutral (HTO) and ionic solutes (Na{sup +}, Cs{sup +}, Sr{sup 2+}, Cl{sup -}, SeO{sub 4}{sup 2-}) in the materials in through-diffusion experiments. For stainless steel filters, the D{sub e} values of the target solutes correlated satisfactorily with their bulk diffusion coefficient in water (D{sub w}); thus, the diffusion process in the stainless steel filters was primarily controlled by the diffusivity of the solvated ions. For the remaining materials, the D{sub e} and D{sub w} values were also correlated for the target solutes, and the geometric factors were in the sequence: VYCOR {sup registered} glass < Al{sub 2}O{sub 3} < PEEK. Stainless steel and VYCOR {sup registered} glass were the most appropriate materials because of their high D{sub e} values, but a specific interaction of caesium with VYCOR {sup registered} glass was hypothesised because the D{sub e} values obtained for this solute were slightly higher than expected.

  13. Highly porous scaffolds of PEDOT:PSS for bone tissue engineering.

    Science.gov (United States)

    Guex, Anne Géraldine; Puetzer, Jennifer L; Armgarth, Astrid; Littmann, Elena; Stavrinidou, Eleni; Giannelis, Emmanuel P; Malliaras, George G; Stevens, Molly M

    2017-10-15

    Conjugated polymers have been increasingly considered for the design of conductive materials in the field of regenerative medicine. However, optimal scaffold properties addressing the complexity of the desired tissue still need to be developed. The focus of this study lies in the development and evaluation of a conductive scaffold for bone tissue engineering. In this study PEDOT:PSS scaffolds were designed and evaluated in vitro using MC3T3-E1 osteogenic precursor cells, and the cells were assessed for distinct differentiation stages and the expression of an osteogenic phenotype. Ice-templated PEDOT:PSS scaffolds presented high pore interconnectivity with a median pore diameter of 53.6±5.9µm and a total pore surface area of 7.72±1.7m 2 ·g -1 . The electrical conductivity, based on I-V curves, was measured to be 140µS·cm -1 with a reduced, but stable conductivity of 6.1µS·cm -1 after 28days in cell culture media. MC3T3-E1 gene expression levels of ALPL, COL1A1 and RUNX2 were significantly enhanced after 4weeks, in line with increased extracellular matrix mineralisation, and osteocalcin deposition. These results demonstrate that a porous material, based purely on PEDOT:PSS, is suitable as a scaffold for bone tissue engineering and thus represents a promising candidate for regenerative medicine. Tissue engineering approaches have been increasingly considered for the repair of non-union fractions, craniofacial reconstruction or large bone defect replacements. The design of complex biomaterials and successful engineering of 3-dimensional tissue constructs is of paramount importance to meet this clinical need. Conductive scaffolds, based on conjugated polymers, present interesting candidates to address the piezoelectric properties of bone tissue and to induce enhanced osteogenesis upon implantation. However, conductive scaffolds have not been investigated in vitro in great measure. To this end, we have developed a highly porous, electrically conductive scaffold

  14. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-01-01

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  15. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-04-24

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  16. Molecular simulation of adsorption and transport in hierarchical porous materials.

    Science.gov (United States)

    Coasne, Benoit; Galarneau, Anne; Gerardin, Corine; Fajula, François; Villemot, François

    2013-06-25

    Adsorption and transport in hierarchical porous solids with micro- (~1 nm) and mesoporosities (>2 nm) are investigated by molecular simulation. Two models of hierarchical solids are considered: microporous materials in which mesopores are carved out (model A) and mesoporous materials in which microporous nanoparticles are inserted (model B). Adsorption isotherms for model A can be described as a linear combination of the adsorption isotherms for pure mesoporous and microporous solids. In contrast, adsorption in model B departs from adsorption in pure microporous and mesoporous solids; the inserted microporous particles act as defects, which help nucleate the liquid phase within the mesopore and shift capillary condensation toward lower pressures. As far as transport under a pressure gradient is concerned, the flux in hierarchical materials consisting of microporous solids in which mesopores are carved out obeys the Navier-Stokes equation so that Darcy's law is verified within the mesopore. Moreover, the flow in such materials is larger than in a single mesopore, due to the transfer between micropores and mesopores. This nonzero velocity at the mesopore surface implies that transport in such hierarchical materials involves slippage at the mesopore surface, although the adsorbate has a strong affinity for the surface. In contrast to model A, flux in model B is smaller than in a single mesopore, as the nanoparticles act as constrictions that hinder transport. By a subtle effect arising from fast transport in the mesopores, the presence of mesopores increases the number of molecules in the microporosity in hierarchical materials and, hence, decreases the flow in the micropores (due to mass conservation). As a result, we do not observe faster diffusion in the micropores of hierarchical materials upon flow but slower diffusion, which increases the contact time between the adsorbate and the surface of the microporosity.

  17. Simulation and material testing of jet engines

    International Nuclear Information System (INIS)

    Tariq, M.M.

    2006-01-01

    The NASA software engine simulator version U 1.7a beta has been used for simulation and material testing of jet engines. Specifications of Modem Jet Engines are stated, and then engine simulator is applied on these specifications. This simulator can simulate turbojet, afterburner, turbofan and ram jet. The material of many components of engine may be varied. Conventional and advanced materials for jet engines can be simulated and tested. These materials can be actively cooled to increase the operating temperature limit. As soon as temperature of any engine component exceeds the temperature limit of material, a warning message flashes across screen. Temperature Limits Exceeded. This flashing message remainst here until necessaryc hangesa re carried out in engine operationp rocedure. Selection Criteria of Engines is stated for piston prop, turboprop, turbofan, turbojet, and turbojet with afterburner and Ramjet. Several standard engines are modeled in Engine Simulator. These engines can. be compared by several engineering specifications. The design, modeling, simulation and testing of engines helps to better understand different types of materials used in jet engines. (author)

  18. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    Science.gov (United States)

    Lin, YuPo J [Naperville, IL; Henry, Michael P [Batavia, IL; Snyder, Seth W [Lincolnwood, IL

    2011-07-12

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  19. Design and computation of modern engineering materials

    CERN Document Server

    Altenbach, Holm

    2014-01-01

     The idea of this monograph is to present the latest results related to design and computation of engineering materials and structures. The contributions cover the classical fields of mechanical, civil and materials engineering up to biomechanics and advanced materials processing and optimization. The materials and structures covered can be categorized into modern steels and titanium alloys, composite materials, biological and natural materials, material hybrids and modern joining technologies. Analytical modelling, numerical simulation, the application of state-of-the-art design tools and sophisticated experimental techniques are applied to characterize the performance of materials and to design and optimize structures in different fields of engineering applications.

  20. Application of porous materials in oil substances separation from water

    Science.gov (United States)

    Gołub, Adam; Piekutin, Janina

    2017-11-01

    The aim of the study was to determine the ability of the four porous materials: birch bark, cork, glass wool, and polyurethane foam to reduce the mineral oil index and the concentration of n-alkanes C7H16-C38H78 as well as to select the most efficient materials. Model solutions of gasoline, diesel oil, and distilled water with the following values of mineral oil index were prepared to tests: 52 μg/dm3, 68 μg/dm3 and 73 μg/dm3. Then, studies were carried out using a dynamic method, wherein the columns were filled with adsorbents tested, and in each of three testing series, 500 mL of the model solution at constant bed load of 1,0551 m3/m2h was filtered through the column. After filtration, the collected sample had volume of 250 mL. The collected samples were subject to determination of mineral oil index and concentrations of n-alkanes from C7H16 to C38H78. Studies have shown that the most effective materials to lower the mineral oil index and the concentrations of n-alkanes in water are birch bark and glass wool.

  1. An experimental investigation of unsteady thermal processes on a pre-cooled circular cylinder of porous material in the wind

    Czech Academy of Sciences Publication Activity Database

    Král, Radomil

    2014-01-01

    Roč. 77, October (2014), s. 906-914 ISSN 0017-9310 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0060; GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : circular cylinder * unsteady heat transfer * temperature distribution * wind tunnel experiment * porous material Subject RIV: JN - Civil Engineering Impact factor: 2.383, year: 2014 http://www.sciencedirect.com/science/article/pii/S0017931014005171

  2. Phase transformations in engineering materials

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Lawson, A.C.; Dunand, D.C.

    1996-01-01

    Phase transformations in engineering materials are inevitably related to mechanical behavior and are often precursors to residual stress and distortion. Neutron scattering in general is a valuable tool for studying their effects, and pulsed neutrons are of special value, because of the inherently comprehensive crystallographic coverage they provide in each measurement. At the Manuel Lujan neutron scattering center several different research programs have addressed the relationships between phase transformation/mechanical behavior and residual strains. Three disparate examples are presented; (1) stress induced transformation in a NiTi shape memory alloy, (2) cryogenically induced transformation in a quenched 5180 steel, and (3) time resolved evolution of strain induced martensite in 304 stainless steel. In each case a brief description of the principle result will be discussed in the context of using neutrons for the measurement

  3. Computational modeling, optimization and manufacturing simulation of advanced engineering materials

    CERN Document Server

    2016-01-01

    This volume presents recent research work focused in the development of adequate theoretical and numerical formulations to describe the behavior of advanced engineering materials.  Particular emphasis is devoted to applications in the fields of biological tissues, phase changing and porous materials, polymers and to micro/nano scale modeling. Sensitivity analysis, gradient and non-gradient based optimization procedures are involved in many of the chapters, aiming at the solution of constitutive inverse problems and parameter identification. All these relevant topics are exposed by experienced international and inter institutional research teams resulting in a high level compilation. The book is a valuable research reference for scientists, senior undergraduate and graduate students, as well as for engineers acting in the area of computational material modeling.

  4. Mechanical properties and biocompatibility of porous titanium scaffolds for bone tissue engineering.

    Science.gov (United States)

    Chen, Yunhui; Frith, Jessica Ellen; Dehghan-Manshadi, Ali; Attar, Hooyar; Kent, Damon; Soro, Nicolas Dominique Mathieu; Bermingham, Michael J; Dargusch, Matthew S

    2017-11-01

    Synthetic scaffolds are a highly promising new approach to replace both autografts and allografts to repair and remodel damaged bone tissue. Biocompatible porous titanium scaffold was manufactured through a powder metallurgy approach. Magnesium powder was used as space holder material which was compacted with titanium powder and removed during sintering. Evaluation of the porosity and mechanical properties showed a high level of compatibility with human cortical bone. Interconnectivity between pores is higher than 95% for porosity as low as 30%. The elastic moduli are 44.2GPa, 24.7GPa and 15.4GPa for 30%, 40% and 50% porosity samples which match well to that of natural bone (4-30GPa). The yield strengths for 30% and 40% porosity samples of 221.7MPa and 117MPa are superior to that of human cortical bone (130-180MPa). In-vitro cell culture tests on the scaffold samples using Human Mesenchymal Stem Cells (hMSCs) demonstrated their biocompatibility and indicated osseointegration potential. The scaffolds allowed cells to adhere and spread both on the surface and inside the pore structures. With increasing levels of porosity/interconnectivity, improved cell proliferation is obtained within the pores. It is concluded that samples with 30% porosity exhibit the best biocompatibility. The results suggest that porous titanium scaffolds generated using this manufacturing route have excellent potential for hard tissue engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Engineered Surface Properties of Porous Tungsten from Cryogenic Machining

    Science.gov (United States)

    Schoop, Julius Malte

    Porous tungsten is used to manufacture dispenser cathodes due to it refractory properties. Surface porosity is critical to functional performance of dispenser cathodes because it allows for an impregnated ceramic compound to migrate to the emitting surface, lowering its work function. Likewise, surface roughness is important because it is necessary to ensure uniform wetting of the molten impregnate during high temperature service. Current industry practice to achieve surface roughness and surface porosity requirements involves the use of a plastic infiltrant during machining. After machining, the infiltrant is baked and the cathode pellet is impregnated. In this context, cryogenic machining is investigated as a substitutionary process for the current plastic infiltration process. Along with significant reductions in cycle time and resource use, surface quality of cryogenically machined un-infiltrated (as-sintered) porous tungsten has been shown to significantly outperform dry machining. The present study is focused on examining the relationship between machining parameters and cooling condition on the as-machined surface integrity of porous tungsten. The effects of cryogenic pre-cooling, rake angle, cutting speed, depth of cut and feed are all taken into consideration with respect to machining-induced surface morphology. Cermet and Polycrystalline diamond (PCD) cutting tools are used to develop high performance cryogenic machining of porous tungsten. Dry and pre-heated machining were investigated as a means to allow for ductile mode machining, yet severe tool-wear and undesirable smearing limited the feasibility of these approaches. By using modified PCD cutting tools, high speed machining of porous tungsten at cutting speeds up to 400 m/min is achieved for the first time. Beyond a critical speed, brittle fracture and built-up edge are eliminated as the result of a brittle to ductile transition. A model of critical chip thickness ( hc ) effects based on cutting

  6. Simulation Study of Shock Reaction on Porous Material

    International Nuclear Information System (INIS)

    Xu Aiguo; Zhang Guangcai; Pan Xiaofei; Zhu Jianshi

    2009-01-01

    Direct modeling of porous materials under shock is a complex issue. We investigate such a system via the newly developed material-point method. The effects of shock strength and porosity size are the main concerns. For the same porosity, the effects of mean-void-size are checked. It is found that local turbulence mixing and volume dissipation are two important mechanisms for transformation of kinetic energy to heat. When the porosity is very small, the shocked portion may arrive at a dynamical steady state; the voids in the downstream portion reflect back rarefactive waves and result in slight oscillations of mean density and pressure; for the same value of porosity, a larger mean-void-size makes a higher mean temperature. When the porosity becomes large, hydrodynamic quantities vary with time during the whole shock-loading procedure: after the initial stage, the mean density and pressure decrease, but the temperature increases with a higher rate. The distributions of local density, pressure, temperature and particle-velocity are generally non-Gaussian and vary with time. The changing rates depend on the porosity value, mean-void-size and shock strength. The stronger the loaded shock, the stronger the porosity effects. This work provides a supplement to experiments for the very quick procedures and reveals more fundamental mechanisms in energy and momentum transportation. (general)

  7. Structure and Stability of Deflagrations in Porous Energetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    stephen B. Margolis; Forman A. Williams

    1999-03-01

    Theoretical two-phase-flow analyses have recently been developed to describe the structure and stability of multi-phase deflagrations in porous energetic materials, in both confined and unconfined geometries. The results of these studies are reviewed, with an emphasis on the fundamental differences that emerge with respect to the two types of geometries. In particular, pressure gradients are usually negligible in unconfined systems, whereas the confined problem is generally characterized by a significant gas-phase pressure difference, or overpressure, between the burned and unburned regions. The latter leads to a strong convective influence on the burning rate arising from the pressure-driven permeation of hot gases into the solid/gas region and the consequent preheating of the unburned material. It is also shown how asymptotic models that are suitable for analyzing stability may be derived based on the largeness of an overall activation-energy parameter. From an analysis of such models, it is shown that the effects of porosity and two-phase flow are generally destabilizing, suggesting that degraded propellants, which exhibit greater porosity than their pristine counterparts, may be more readily subject to combustion instability and nonsteady deflagration.

  8. Efficient Monte Carlo Simulations of Gas Molecules Inside Porous Materials.

    Science.gov (United States)

    Kim, Jihan; Smit, Berend

    2012-07-10

    Monte Carlo (MC) simulations are commonly used to obtain adsorption properties of gas molecules inside porous materials. In this work, we discuss various optimization strategies that lead to faster MC simulations with CO2 gas molecules inside host zeolite structures used as a test system. The reciprocal space contribution of the gas-gas Ewald summation and both the direct and the reciprocal gas-host potential energy interactions are stored inside energy grids to reduce the wall time in the MC simulations. Additional speedup can be obtained by selectively calling the routine that computes the gas-gas Ewald summation, which does not impact the accuracy of the zeolite's adsorption characteristics. We utilize two-level density-biased sampling technique in the grand canonical Monte Carlo (GCMC) algorithm to restrict CO2 insertion moves into low-energy regions within the zeolite materials to accelerate convergence. Finally, we make use of the graphics processing units (GPUs) hardware to conduct multiple MC simulations in parallel via judiciously mapping the GPU threads to available workload. As a result, we can obtain a CO2 adsorption isotherm curve with 14 pressure values (up to 10 atm) for a zeolite structure within a minute of total compute wall time.

  9. Porous materials based on foaming solutions obtained from industrial waste

    Science.gov (United States)

    Starostina, I. V.; Antipova, A. N.; Ovcharova, I. V.; Starostina, Yu L.

    2018-03-01

    This study analyzes foam concrete production efficiency. Research has shown the possibility of using a newly-designed protein-based foaming agent to produce porous materials using gypsum and cement binders. The protein foaming agent is obtained by alkaline hydrolysis of a raw mixture consisting of industrial waste in an electromagnetic field. The mixture consists of spent biomass of the Aspergillus niger fungus and dust from burning furnaces used in cement production. Varying the content of the foaming agent allows obtaining gypsum binder-based foam concretes with the density of 200-500 kg/m3 and compressive strength of 0.1-1.0 MPa, which can be used for thermal and sound insulation of building interiors. Cement binders were used to obtain structural and thermal insulation materials with the density of 300-950 kg/m3 and compressive strength of 0.9-9.0 MPa. The maximum operating temperature of cement-based foam concretes is 500°C because it provides the shrinkage of less than 2%.

  10. Electron tomography of porous materials and magnetic nanoparticles

    International Nuclear Information System (INIS)

    Uusimäki, T.

    2015-01-01

    Electron tomography, as carried out in a transmission electron microscope is a method to reveal the three dimensional structure of the sample at the nanometer scale. It is based on tilting the sample and recording subsequent images at different projections angles. Using specific reconstruction algorithms the density distribution of the sample can then be reproduced. In this thesis, electron tomography has been implemented for material science specimens and more rigorously to porous media infiltrated with magnetic nanoparticles. The volume and spatial distribution along with the knowledge of the demagnetizing factors were then used within a magnetic Monte Carlo simulation to predict the magnetic response of the nanoparticle assembly. The local curvature of nanoparticles within the template, known to be a critical geometrical parameter influencing material properties, was extracted with two distinctive methods. Furthermore, new capabilities needed for image analysis and processing of the tilt series had to be implemented for improved alignments and segmentation. A new method to align the tilt series without depending on markers was written for obtaining high quality reconstructions. Also a comparison was made between different scanning TEM acquisition modes such as incoherent bright field and high angle annular dark field imaging modes with respect to resolution and contrast changes. (author) [de

  11. Measuring adsorption, diffusion and flow in chemical engineering: applications of magnetic resonance to porous media

    International Nuclear Information System (INIS)

    Gladden, Lynn F; Mitchell, Jonathan

    2011-01-01

    Magnetic resonance (MR) techniques are increasingly used to improve our understanding of the multi-component, multi-phase processes encountered in chemical engineering. This review brings together many of the MR techniques used, and often developed specifically, to study chemical engineering systems and, in particular, processes occurring within porous media. Pulse sequences for relaxometry, pulsed field gradient measurements of diffusion, imaging and velocimetry measurements are described. Recent applications of these MR pulse sequences to microporous, mesoporous and macroporous structures are then reviewed. Considering the microporous and mesoporous systems, we focus attention on studies of rock cores, manufactured materials such as cement and gypsum plaster, and catalysts. When considering macroporous structures, the transport through packed beds of particles typical of fixed-bed catalytic reactors is reviewed; a brief overview of the increasing research interest in gas-solid fluidized beds is also presented. We highlight the field of sparse k-space sampling as an area that is in its infancy and suggest that, combined with Bayesian methods, it will offer new opportunities in both extending the application of high-field MR techniques to chemical engineering and increasing the range of measurements that can be carried out using low-field hardware.

  12. Design and Structure-Function Characterization of 3D Printed Synthetic Porous Biomaterials for Tissue Engineering.

    Science.gov (United States)

    Kelly, Cambre N; Miller, Andrew T; Hollister, Scott J; Guldberg, Robert E; Gall, Ken

    2018-04-01

    3D printing is now adopted for use in a variety of industries and functions. In biomedical engineering, 3D printing has prevailed over more traditional manufacturing methods in tissue engineering due to its high degree of control over both macro- and microarchitecture of porous tissue scaffolds. However, with the improved flexibility in design come new challenges in characterizing the structure-function relationships between various architectures and both mechanical and biological properties in an assortment of clinical applications. Presently, the field of tissue engineering lacks a comprehensive body of literature that is capable of drawing meaningful relationships between the designed structure and resulting function of 3D printed porous biomaterial scaffolds. This work first discusses the role of design on 3D printed porous scaffold function and then reviews characterization of these structure-function relationships for 3D printed synthetic metallic, polymeric, and ceramic biomaterials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Engineering evaluation of porous-dike intake screening systems

    International Nuclear Information System (INIS)

    Roberge, J.C.

    1978-01-01

    As one of many concepts currently under investigation for use in screening fish and larvae from power plant intakes, the porous-dike system presents unique challenges to the designer and constructor. A complete understanding of the hydraulic losses through such a structure is necessary to properly size and locate the intake and to ensure proper pump selection and performance. In the study described in this report, an analogy with frictional losses in conduits was employed, and empirical data on losses were determined for three sizes of filter stone typical of the types used in the construction of a porous-dike intake system. These empirical data were compared with additional information from the literature. The dependence of hydraulic losses through large-diameter media on stone shape and porosity were demonstrated although no empirical expression of this dependence was developed. A hypothetical porous-dike intake installation was developed, demonstrating the fundamental design considerations which must be made for such a structure. Finally, a cursory economic comparison of various intake screening systems demonstrated that the porous-dike intake concept was economically competitive with all others

  14. SCDAP/RELAP5 Modeling of Movement of Melted Material Through Porous Debris in Lower Head

    International Nuclear Information System (INIS)

    Siefken, L. J.

    1998-01-01

    Designs are described for implementing models for calculating the movement of melted material through the interstices in a matrix of porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and nonporous debris that results from core material slumping into the lower head during a severe accident in a Light Water Reactor. Currently, the COUPLE model has no capability to model the movement of material that melts within a matrix of porous material. The COUPLE model also does not have the capability to model the movement of liquefied core plate material that slumps onto a porous debris bed in the lower head. In order to advance beyond the assumption the liquefied material always remains stationary, designs are developed for calculations of the movement of liquefied material through the interstices in a matrix of porous material. Correlations are identified for calculating the permeability of the porous debris and for calculating the rate of flow of liquefied material through the interstices in the debris bed. Correlations are also identified for calculating the relocation of solid debris that has a large amount of cavities due to the flowing away of melted material. Equations are defined for calculating the effect on the temperature distribution in the debris bed of heat transported by moving material and for changes in effective thermal conductivity and heat capacity due to the movement of material. The implementation of these models is expected to improve the calculation of the material distribution and temperature distribution of debris in the lower head for cases in which the debris is porous and liquefied material is present within the porous debris

  15. Method for modeling the gradual physical degradation of a porous material

    Energy Technology Data Exchange (ETDEWEB)

    Flach, Greg [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-20

    Cementitious and other engineered porous materials encountered in waste disposals may degrade over time due to one or more mechanisms. Physical degradation may take the form of cracking (fracturing) and/or altered (e.g. increased) porosity, depending on the material and underlying degradation mechanism. In most cases, the hydraulic properties of degrading materials are expected to evolve due to physical changes occurring over roughly the pore to decimeter scale, which is conducive to calculating equivalent or effective material properties. The exact morphology of a degrading material in its end-state may or may not be known. In the latter case, the fully-degraded condition can be assumed to be similar to a more-permeable material in the surrounding environment, such as backfill soil. Then the fully-degraded waste form or barrier material is hydraulically neutral with respect to its surroundings, constituting neither a barrier to nor conduit for moisture flow and solute transport. Unless the degradation mechanism is abrupt, a gradual transition between the intact initial and fully-degraded final states is desired. Linear interpolation through time is one method for smoothly blending hydraulic properties between those of an intact matrix and those of a soil or other surrogate for the end-state.

  16. Method for modeling the gradual physical degradation of a porous material

    International Nuclear Information System (INIS)

    Flach, Greg

    2017-01-01

    Cementitious and other engineered porous materials encountered in waste disposals may degrade over time due to one or more mechanisms. Physical degradation may take the form of cracking (fracturing) and/or altered (e.g. increased) porosity, depending on the material and underlying degradation mechanism. In most cases, the hydraulic properties of degrading materials are expected to evolve due to physical changes occurring over roughly the pore to decimeter scale, which is conducive to calculating equivalent or effective material properties. The exact morphology of a degrading material in its end-state may or may not be known. In the latter case, the fully-degraded condition can be assumed to be similar to a more-permeable material in the surrounding environment, such as backfill soil. Then the fully-degraded waste form or barrier material is hydraulically neutral with respect to its surroundings, constituting neither a barrier to nor conduit for moisture flow and solute transport. Unless the degradation mechanism is abrupt, a gradual transition between the intact initial and fully-degraded final states is desired. Linear interpolation through time is one method for smoothly blending hydraulic properties between those of an intact matrix and those of a soil or other surrogate for the end-state.

  17. Hyper-elastic modeling and mechanical behavior investigation of porous poly-D-L-lactide/nano-hydroxyapatite scaffold material.

    Science.gov (United States)

    Han, Quan Feng; Wang, Ze Wu; Tang, Chak Yin; Chen, Ling; Tsui, Chi Pong; Law, Wing Cheung

    2017-07-01

    Poly-D-L-lactide/nano-hydroxyapatite (PDLLA/nano-HA) can be used as the biological scaffold material in bone tissue engineering as it can be readily made into a porous composite material with excellent performance. However, constitutive modeling for the mechanical response of porous PDLLA/nano-HA under various stress conditions has been very limited so far. In this work, four types of fundamental compressible hyper-elastic constitutive models were introduced for constitutive modeling and investigation of mechanical behaviors of porous PDLLA/nano-HA. Moreover, the unitary expressions of Cauchy stress tensor have been derived for the PDLLA/nano-HA under uniaxial compression (or stretch), biaxial compression (or stretch), pure shear and simple shear load by using the theory of continuum mechanics. The theoretical results determined from the approach based on the Ogden compressible hyper-elastic constitutive model were in good agreement with the experimental data from the uniaxial compression tests. Furthermore, this approach can also be used to predict the mechanical behaviors of the porous PDLLA/nano-HA material under the biaxial compression (or stretch), pure shear and simple shear. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Deformation and fracture mechanics of engineering materials

    National Research Council Canada - National Science Library

    Hertzberg, Richard W; Vinci, Richard Paul; Hertzberg, Jason L

    2012-01-01

    "Hertzberg's 5th edition of Deformation & Fracture Mechanics of Engineering Materials offers several new features including a greater number and variety of homework problems using more computational software...

  19. Design and Fabrication of Biodegradable Porous Chitosan/Gelatin/Tricalcium Phosphate Hybrid Scaffolds for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Y. Mohammadi

    2007-08-01

    Full Text Available In this study, based on a biomimetic approach, novel 3D biodegradable porous hybrid scaffolds consisting of chitosan, gelatin, and tricalcium phosphate were developed for bone and cartilage tissue engineering. Macroporous chitosan/ gelatin/β-TCP scaffolds were prepared through the process of freeze-gelation/solid-liquid phase separation. The results showed that the prepared scaffolds are highly porous, with porosities larger than 80%, and have interconnected pores. Biocompatibility studies were successfully performed by in vitro and in vivo assays. Moreover, the attachment, migration, and proliferation of chondrocytes on these unique temporary scaffolds were examined to determine their potentials in tissue engineering applications.

  20. The evaluation of hydroxyapatite (HA) coated and uncoated porous tantalum for biomedical material applications

    International Nuclear Information System (INIS)

    Safuan, Nadia; Sukmana, Irza; Kadir, Mohammed Rafiq Abdul; Noviana, Deni

    2014-01-01

    Porous tantalum has been used as an orthopedic implant for bone defects as it has a good corrosion resistance and fatigue behaviour properties. However, there are some reports on the rejection of porous Ta after the implantation. Those clinical cases refer to the less bioactivity of metallic-based materials. This study aims to evaluate hydroxyapatite coated and uncoated porous Tantalum in order to improve the biocompatibility of porous tantalum implant and osseointegration. Porous tantalum was used as metallic-base substrate and hydroxyapatite coating has been done using plasma-spraying technique. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) techniques were utilizes to investigate the coating characteristics while Confocal Raman Microscopy to investigate the interface and image. The effect of coating to the corrosion behaviour was assessed by employing potentiodynamic polarization tests in simulated body fluid at 37±1 °C. Based on SEM and FESEM results, the morphologies as well the weight element consists in the uncoated and hydroxyapatite coated porous tantalum were revealed. The results indicated that the decrease in corrosion current density for HA coated porous Ta compared to the uncoated porous Ta. This study concluded that by coating porous tantalum with HA supports to decrease the corrosion rate of pure porous.

  1. The Evaluation of Hydroxyapatite (HA) Coated and Uncoated Porous Tantalum for Biomedical Material Applications

    Science.gov (United States)

    Safuan, Nadia; Sukmana, Irza; Kadir, Mohammed Rafiq Abdul; Noviana, Deni

    2014-04-01

    Porous tantalum has been used as an orthopedic implant for bone defects as it has a good corrosion resistance and fatigue behaviour properties. However, there are some reports on the rejection of porous Ta after the implantation. Those clinical cases refer to the less bioactivity of metallic-based materials. This study aims to evaluate hydroxyapatite coated and uncoated porous Tantalum in order to improve the biocompatibility of porous tantalum implant and osseointegration. Porous tantalum was used as metallic-base substrate and hydroxyapatite coating has been done using plasma-spraying technique. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) techniques were utilizes to investigate the coating characteristics while Confocal Raman Microscopy to investigate the interface and image. The effect of coating to the corrosion behaviour was assessed by employing potentiodynamic polarization tests in simulated body fluid at 37±1 °C. Based on SEM and FESEM results, the morphologies as well the weight element consists in the uncoated and hydroxyapatite coated porous tantalum were revealed. The results indicated that the decrease in corrosion current density for HA coated porous Ta compared to the uncoated porous Ta. This study concluded that by coating porous tantalum with HA supports to decrease the corrosion rate of pure porous.

  2. Structural properties of porous materials and powders used in different fields of science and technology

    CERN Document Server

    Volfkovich, Yury Mironovich; Bagotsky, Vladimir Sergeevich

    2014-01-01

    This book provides a comprehensive and concise description of most important aspects of experimental and theoretical investigations of porous materials and powders, with the use and application of these materials in different fields of science, technology, national economy and environment. It allows the reader to understand the basic regularities of heat and mass transfer and adsorption occurring in qualitatively different porous materials and products, and allows the reader to optimize the functional properties of porous and powdered products and materials. Written in an straightforward and transparent manner, this book is accessible to both experts and those without specialist knowledge, and it is further elucidated by drawings, schemes and photographs. Porous materials and powders with different pore sizes are used in many areas of industry, geology, agriculture and science. These areas include (i) a variety of devices and supplies; (ii) thermal insulation and building materials; (iii) oil-bearing geologic...

  3. Electrokinetic salt removal from porous building materials using ion exchange membranes

    NARCIS (Netherlands)

    Kamran, K.; Van Soestbergen, M.; Pel, L.

    The removal of salt from porous building materials under the influence of an applied voltage gradient normally results in high pH gradients due to the formation of protons and hydroxyl ions at the electrodes. The formed acidic and alkaline regions not only lead to disintegration of the porous

  4. Electrokinetic salt removal from porous building materials using ion exchange membranes

    NARCIS (Netherlands)

    Kamran, K.; Soestbergen, van M.; Pel, L.

    2012-01-01

    The removal of salt from porous building materials under the influence of an applied voltage gradient normally results in high pH gradients due to the formation of protons and hydroxyl ions at the electrodes. The formed acidic and alkaline regions not only lead to disintegration of the porous

  5. Application of porous material to reduce aerodynamic sound from bluff bodies

    International Nuclear Information System (INIS)

    Sueki, Takeshi; Takaishi, Takehisa; Ikeda, Mitsuru; Arai, Norio

    2010-01-01

    Aerodynamic sound derived from bluff bodies can be considerably reduced by flow control. In this paper, the authors propose a new method in which porous material covers a body surface as one of the flow control methods. From wind tunnel tests on flows around a bare cylinder and a cylinder with porous material, it has been clarified that the application of porous materials is effective in reducing aerodynamic sound. Correlation between aerodynamic sound and aerodynamic force fluctuation, and a surface pressure distribution of cylinders are measured to investigate a mechanism of aerodynamic sound reduction. As a result, the correlation between aerodynamic sound and aerodynamic force fluctuation exists in the flow around the bare cylinder and disappears in the flow around the cylinder with porous material. Moreover, the aerodynamic force fluctuation of the cylinder with porous material is less than that of the bare cylinder. The surface pressure distribution of the cylinder with porous material is quite different from that of the bare cylinder. These facts indicate that aerodynamic sound is reduced by suppressing the motion of vortices because aerodynamic sound is induced by the unstable motion of vortices. In addition, an instantaneous flow field in the wake of the cylinder is measured by application of the PIV technique. Vortices that are shed alternately from the bare cylinder disappear by application of porous material, and the region of zero velocity spreads widely behind the cylinder with porous material. Shear layers between the stationary region and the uniform flow become thin and stable. These results suggest that porous material mainly affects the flow field adjacent to bluff bodies and reduces aerodynamic sound by depriving momentum of the wake and suppressing the unsteady motion of vortices. (invited paper)

  6. Multiphase radon generation and transport in porous materials

    International Nuclear Information System (INIS)

    Rogers, V.C.; Nielson, K.K.

    1991-01-01

    Radon generation and transport in porous materials involve solid, liquid, and gas phases in the processes of emanation, diffusion, advection, absorption, and adsorption. Oversimplifications, such as representing moist soil systems by air-phase emanation and transport models, cause theoretical inconsistencies and biases in resulting calculations. Detailed Rn rate balance equations for solid, liquid, and gas phases were analyzed and combined using phase equilibrium constants to derive a single diffusive-advective rate balance equation in the traditional form. The emanation, diffusion, and permeability coefficients in the new equation have expanded definitions and interpretations to include Rn phase transfer. Radon adsorption was characterized by an exponential moisture dependence, and diffusion and permeability constants utilized previous moisture relationships. Correct boundary and interface conditions were defined, and the unified theoretical approach was applied to field data from a diffusion-dominated system and to laboratory data from an advection-dominated system. Measured 222 Rn fluxes and concentrations validated the modeled values within the measurement variability in both applications

  7. Fractal Model for Acoustic Absorbing of Porous Fibrous Metal Materials

    Directory of Open Access Journals (Sweden)

    Weihua Chen

    2016-01-01

    Full Text Available To investigate the changing rules between sound absorbing performance and geometrical parameters of porous fibrous metal materials (PFMMs, this paper presents a fractal acoustic model by incorporating the static flow resistivity based on Biot-Allard model. Static flow resistivity is essential for an accurate assessment of the acoustic performance of the PFMM. However, it is quite difficult to evaluate the static flow resistivity from the microstructure of the PFMM because of a large number of disordered pores. In order to overcome this difficulty, we firstly established a static flow resistivity formula for the PFMM based on fractal theory. Secondly, a fractal acoustic model was derived on the basis of the static flow resistivity formula. The sound absorption coefficients calculated by the presented acoustic model were validated by the values of Biot-Allard model and experimental data. Finally, the variation of the surface acoustic impedance, the complex wave number, and the sound absorption coefficient with the fractal dimensions were discussed. The research results can reveal the relationship between sound absorption and geometrical parameters and provide a basis for improving the sound absorption capability of the PFMMs.

  8. Capillary condensation in porous materials. Hysteresis and interaction mechanism without pore blocking/percolation process.

    Science.gov (United States)

    Grosman, Annie; Ortega, Camille

    2008-04-15

    We have performed measurements of boundary hysteresis loops, reversal curves, and subloops in p+-type porous silicon, a porous material composed of straight non-interconnected pores. These data show that a strong interaction mechanism exists between the pores. The pores of porous silicon are non-independent, whereas they are not interconnected. This hysteretic behavior is very similar to that observed in porous glass, which consists of cavities connected to each other by constrictions. This questions the so-called pore blocking/percolation model developed to explain the behavior of fluid in porous glass. More generally, if we disregard the shape of the boundary hysteresis loops which depends on the porous material (H1 for MCM-41 and SBA-15, H2 for porous glass and p+-type porous silicon), the hysteretic features inside the main loop are qualitatively the same for all these porous systems. This shows that none of these systems are composed of independent pores. A coupling between the pores is always present whether they are interconnected or not and whatever the shape of the main loop is.

  9. Effect of porous material heating on the drag force of a cylinder with gas-permeable porous inserts in a supersonic flow

    Science.gov (United States)

    Mironov, S. G.; Poplavskaya, T. V.; Kirilovskiy, S. V.

    2017-10-01

    The paper presents the results of an experimental investigation of supersonic flow around a solid cylinder with a gas-permeable porous insert on its front end and of supersonic flow around a hollow cylinder with internal porous inserts in the presence of heating of the porous material. The experiments were performed in a supersonic wind tunnel with Mach number 4.85 and 7 with porous inserts of cellular-porous nickel. The results of measurements on the filtration stand of the air filtration rate through the cellular-porous nickel when it is heated are also shown. For a number of experiments, numerical modeling based on the skeletal model of a cellular-porous material was carried out.

  10. Cellulose/poly-(m-phenylene isophthalamide) porous film as a tissue-engineered skin bioconstruct

    Science.gov (United States)

    Lee, Jae Woong; Han, Sung Soo; Zo, Sum Mi; Choi, Soon Mo

    2018-06-01

    Regarding the porous structure, coagulated cellulose may not provide sufficient voids for cell proliferation, resulting in tissue growth. For this reason, it was blended with poly(m-phenylene isophthalamide) (PMIA), which could produce a porous structure in the resulting construct. The aim of this study was to confirm the potential of a novel cellulose/PMIA porous film as a tissue-engineered bioconstruct for impaired skin. The films were fabricated by a coagulation process added with a peel-off method, and the structural, mechanical properties were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and capillary flow porometry. CRL-2310 human keratinocytes were used to determine the biocompatibility of the prepared films. The attachment and proliferation of cells were investigated by scanning electron microscopy, DAPI staining, and a cell viability assay. The results show that cellulose/PMIA porous films have potential use as wound matrices for skin tissue genesis.

  11. Small-angle and surface scattering from porous and fractal materials.

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, S. K.

    1998-09-18

    We review the basic theoretical methods used to treat small-angle scattering from porous materials, treated as general two-phase systems, and also the basic experimental techniques for carrying out such experiments. We discuss the special forms of the scattering when the materials exhibit mass or surface fractal behavior, and review the results of recent experiments on several types of porous media and also SANS experiments probing the phase behavior of binary fluid mixtures or polymer solutions confined in porous materials. Finally, we discuss the analogous technique of off-specular scattering from surfaces and interfaces which is used to study surface roughness of various kinds.

  12. Assessment of porous material anisotropy and its effect on gas permeability

    Science.gov (United States)

    Wałowski, Grzegorz

    2017-10-01

    The results of experimental research upon the assessment of porous material anisotropy and its effect on gas permeability of porous materials with respect to the gas flow. The conducted research applied to natural materials with an anisotropic gap-porous structure and - for comparative purposes - to model materials such as coke, pumice and polyamide agglomerates. The research was conducted with the use of a special test stand that enables measuring the gas permeability with respect to three flow orientations compared with symmetric cubic-shaped samples. The research results show an explicit impact of the flow direction on the permeability of materials porous, which results from their anisotropic internal structures. The anisotropy coefficient and permeability effective coefficient of such materials was determined and an experimental evaluation of the value of this coefficient was conducted with respect to the gas stream and the total pressure drop across the porous deposit. The process of gas permeability was considered in the category of hydrodynamics of gas flow through porous deposits. It is important to broaden the knowledge of gas hydrodynamics assessment in porous media so far unrecognised for the development of a new generation of clean energy sources, especially in the context of biogas or raw gas production.

  13. Three-dimensional printing of porous ceramic scaffolds for bone tissue engineering.

    Science.gov (United States)

    Seitz, Hermann; Rieder, Wolfgang; Irsen, Stephan; Leukers, Barbara; Tille, Carsten

    2005-08-01

    This article reports a new process chain for custom-made three-dimensional (3D) porous ceramic scaffolds for bone replacement with fully interconnected channel network for the repair of osseous defects from trauma or disease. Rapid prototyping and especially 3D printing is well suited to generate complex-shaped porous ceramic matrices directly from powder materials. Anatomical information obtained from a patient can be used to design the implant for a target defect. In the 3D printing technique, a box filled with ceramic powder is printed with a polymer-based binder solution layer by layer. Powder is bonded in wetted regions. Unglued powder can be removed and a ceramic green body remains. We use a modified hydroxyapatite (HA) powder for the fabrication of 3D printed scaffolds due to the safety of HA as biocompatible implantable material and efficacy for bone regeneration. The printed ceramic green bodies are consolidated at a temperature of 1250 degrees C in a high temperature furnace in ambient air. The polymeric binder is pyrolysed during sintering. The resulting scaffolds can be used in tissue engineering of bone implants using patient-derived cells that are seeded onto the scaffolds. This article describes the process chain, beginning from data preparation to 3D printing tests and finally sintering of the scaffold. Prototypes were successfully manufactured and characterized. It was demonstrated that it is possible to manufacture parts with inner channels with a dimension down to 450 microm and wall structures with a thickness down to 330 microm. The mechanical strength of dense test parts is up to 22 MPa. Copyright 2005 Wiley Periodicals, Inc.

  14. Streaming Potential and Electroosmosis Measurements to Characterize Porous Materials

    NARCIS (Netherlands)

    Luong, D.T.; Sprik, R.

    2013-01-01

    Characterizing the streaming potential and electroosmosis properties of porous media is essential in applying seismoelectric and electroseismic phenomena for oil exploration. Some parameters such as porosity, permeability, formation factor, pore size, the number of pores, and the zeta potential of

  15. Analysis of an Internal Combustion Engine Using Porous Foams for Thermal Energy Recovery

    Directory of Open Access Journals (Sweden)

    Mehdi Ali Ehyaei

    2016-03-01

    Full Text Available Homogeneous and complete combustion in internal combustion engines is advantageous. The use of a porous foam in the exhaust gas in an engine cylinder for heat recovery is examined here with the aim of reducing engine emissions. The internal combustion engine with a porous core regenerator is modeled using SOPHT software, which solved the differential equations for the thermal circuit in the engine. The engine thermal efficiency is observed to increase from 43% to 53% when the porous core regenerator is applied. Further, raising the compression ratio causes the peak pressure and thermal efficiency to increase, e.g., increasing the compression ratio from 13 to 15 causes the thermal efficiency and output work to increase from 53% to 55% and from 4.86 to 4.93 kJ, respectively. The regenerator can also be used as a catalytic converter for fine particles and some other emissions. The regenerator oxidizes unburned hydrocarbons. Meanwhile, heat recovered from the exhaust gases can reduce fuel consumption, further reducing pollutant emissions from the internal combustion engine.

  16. Electrohydrodynamic bubbling: an alternative route to fabricate porous structures of silk fibroin based materials.

    Science.gov (United States)

    Ekemen, Zeynep; Ahmad, Zeeshan; Stride, Eleanor; Kaplan, David; Edirisinghe, Mohan

    2013-05-13

    Conventional fabrication techniques and structures employed in the design of silk fibroin (SF) based porous materials provide only limited control over pore size and require several processing stages. In this study, it is shown that, by utilizing electrohydrodynamic bubbling, not only can new hollow spherical structures of SF be formed in a single step by means of bubbles, but the resulting bubbles can serve as pore generators when dehydrated. The bubble characteristics can be controlled through simple adjustments to the processing parameters. Bubbles with diameters in the range of 240-1000 μm were fabricated in controlled fashion. FT-IR characterization confirmed that the rate of air infused during processing enhanced β-sheet packing in SF at higher flow rates. Dynamic mechanical analysis also demonstrated a correlation between air flow rate and film tensile strength. Results indicate that electrohydrodynamically generated SF and their composite bubbles can be employed as new tools to generate porous structures in a controlled manner with a range of potential applications in biocoatings and tissue engineering scaffolds.

  17. Matcom 86: Engineering materials in South Africa

    International Nuclear Information System (INIS)

    1986-01-01

    The Symposium MATCOM '86 represents a significant departure from the usual format of scientific and engineering conferences. It provides a unique opportunity for industrialists, economists, the engineering and scientific communities, and research and development establishments to be briefed on critical issues relating to engineering materials and the effect of these materials on the manufacturing, service, health, strategic and minerals industries. Profitability and productivity in industry can often be linked to engineering materials and their in-service performance. Major surveys conducted in South Africa and developed countries have revealed the significance of losses to industry due to materials degradation problems such as fracture, wear, corrosion etc. One of the papers delivered at this symposium focus on the nuclear engineering industry, namely the application of materials in the field of uranium enrichment

  18. Basic transport phenomena in materials engineering

    CERN Document Server

    Iguchi, Manabu

    2014-01-01

    This book presents the basic theory and experimental techniques of transport phenomena in materials processing operations. Such fundamental knowledge is highly useful for researchers and engineers in the field to improve the efficiency of conventional processes or develop novel technology. Divided into four parts, the book comprises 11 chapters describing the principles of momentum transfer, heat transfer, and mass transfer in single phase and multiphase systems. Each chapter includes examples with solutions and exercises to facilitate students’ learning. Diagnostic problems are also provided at the end of each part to assess students’ comprehension of the material.  The book is aimed primarily at students in materials science and engineering. However, it can also serve as a useful reference text in chemical engineering as well as an introductory transport phenomena text in mechanical engineering. In addition, researchers and engineers engaged in materials processing operations will find the material use...

  19. Examining porous bio-active glass as a potential osteo-odonto-keratoprosthetic skirt material.

    Science.gov (United States)

    Huhtinen, Reeta; Sandeman, Susan; Rose, Susanna; Fok, Elsie; Howell, Carol; Fröberg, Linda; Moritz, Niko; Hupa, Leena; Lloyd, Andrew

    2013-05-01

    Bio-active glass has been developed for use as a bone substitute with strong osteo-inductive capacity and the ability to form strong bonds with soft and hard tissue. The ability of this material to enhance tissue in-growth suggests its potential use as a substitute for the dental laminate of an osteo-odonto-keratoprosthesis. A preliminary in vitro investigation of porous bio-active glass as an OOKP skirt material was carried out. Porous glass structures were manufactured from bio-active glasses 1-98 and 28-04 containing varying oxide formulation (1-98, 28-04) and particle size range (250-315 μm for 1-98 and 28-04a, 315-500 μm for 28-04b). Dissolution of the porous glass structure and its effect on pH was measured. Structural 2D and 3D analysis of porous structures were performed. Cell culture experiments were carried out to study keratocyte adhesion and the inflammatory response induced by the porous glass materials. The dissolution results suggested that the porous structure made out of 1-98 dissolves faster than the structures made from glass 28-04. pH experiments showed that the dissolution of the porous glass increased the pH of the surrounding solution. The cell culture results showed that keratocytes adhered onto the surface of each of the porous glass structures, but cell adhesion and spreading was greatest for the 98a bio-glass. Cytokine production by all porous glass samples was similar to that of the negative control indicating that the glasses do not induce a cytokine driven inflammatory response. Cell culture results support the potential use of synthetic porous bio-glass as an OOKP skirt material in terms of limited inflammatory potential and capacity to induce and support tissue ingrowth.

  20. Flexible and elastic porous poly(trimethylene carbonate) structures for use in vascular tissue engineering

    NARCIS (Netherlands)

    Song, Y.; Kamphuis, Marloes; Zhang Zheng, Z.Z.; Zhang, Z.; Sterk, L.M.Th.; Vermes, I.; Poot, Andreas A.; Feijen, Jan; Grijpma, Dirk W.

    Biocompatible and elastic porous tubular structures based on poly(1,3-trimethylene carbonate), PTMC, were developed as scaffolds for tissue engineering of small-diameter blood vessels. High-molecular-weight PTMC (Mn = 4.37 × 105) was cross-linked by gamma-irradiation in an inert nitrogen atmosphere.

  1. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene

    KAUST Repository

    Cui, X.; Chen, K.; Xing, H.; Yang, Q.; Krishna, R.; Bao, Z.; Wu, H.; Zhou, W.; Dong, Xinglong; Han, Y.; Li, B.; Ren, Q.; Zaworotko, M. J.; Chen, B.

    2016-01-01

    The trade-off between physical adsorption capacity and selectivity of porous materials is a major barrier for efficient gas separation and purification through physisorption. We report control over pore chemistry and size in metal coordination

  2. Porous glasses as a host of luminescent materials, their applications and site selective determination

    Energy Technology Data Exchange (ETDEWEB)

    Reisfeld, Renata, E-mail: renata.reisfeld@mail.huji.ac.il [Institute of Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904 (Israel); Jasinska, Bozena [Institute of Physics, Maria Curie-Sklodowska University, Pl. M. Curie-Skłodowsskiej 1, 20-031 Lublin (Poland); Levchenko, Viktoria [Institute of Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904 (Israel); Gorgol, Marek [Institute of Physics, Maria Curie-Sklodowska University, Pl. M. Curie-Skłodowsskiej 1, 20-031 Lublin (Poland); Saraidarov, Tsiala; Popov, Inna [Institute of Chemistry, Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904 (Israel); Antropova, Tatiana [I. V. Grebenshchikov Institute of the Chemistry of Silicates, Russian Academy of Sciences, Nab. Makarova, 2, Liter B, Saint-Petersburg 199034 (Russian Federation); Rysiakiewicz-Pasek, Ewa [Institute of Physics, Wroclaw University of Technology, W. Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2016-01-15

    The site selective distribution of pore sizes in pure porous glasses and glasses doped by a luminescent colorant is determined by luminescent spectroscopy, SEM, SAXS and PALS. The potential applications of the studied materials as environmental and biological sensors are outlined. We suggest how luminescent porous glasses doped by complexes of Gd can act as solid scintillators in tracing elementary particles like neutrino. - Highlights: • Porous glasses are a medium for large number of luminescent materials. • Size distribution of empty and filled pores is studied. • The validity of data obtained by different methods is analyzed.

  3. Effect of Pressing Parameters on the Structure of Porous Materials Based on Cobalt and Nickel Powders

    Science.gov (United States)

    Shustov, V. S.; Rubtsov, N. M.; Alymov, M. I.; Ankudinov, A. B.; Evstratov, E. V.; Zelensky, V. A.

    2018-03-01

    Porous materials with a bulk porosity of more than 68% were synthesized by powder metallurgy methods from a cobalt-nickel mixture. The effect of the ratio of nickel and cobalt powders used in the synthesis of this porous material (including cases when either nickel or cobalt alone was applied) and the conditions of their compaction on structural parameters, such as open and closed porosities and pose size, was established.

  4. OSTEOCALCIN DINAMIC OF DISTROPHICAL BONE KISTS BY TITANIUM NIKELID POROUS MATERIALS IMPLANTATION IN CHILDREN

    Directory of Open Access Journals (Sweden)

    I. I. Kuzhelivsky

    2015-01-01

    Full Text Available The article presents results of bone kists treatment by porous granular titanium nikelid materials and dynamic of osteokalcin. A comparative examination with standard treatment technology group demonstrated high efficiency of a proposed method. Porous granular titanium nikelid materials possess mechanical strength, optimization of regeneration at the expense of osteoinductivity by osteokalcin and allow you to effectively fill the cavity with a complex anatomical structure. 

  5. OSTEOCALCIN DINAMIC OF DISTROPHICAL BONE KISTS BY TITANIUM NIKELID POROUS MATERIALS IMPLANTATION IN CHILDREN

    OpenAIRE

    I. I. Kuzhelivsky; M. A. Akselrov; L. A. Sitko

    2015-01-01

    The article presents results of bone kists treatment by porous granular titanium nikelid materials and dynamic of osteokalcin. A comparative examination with standard treatment technology group demonstrated high efficiency of a proposed method. Porous granular titanium nikelid materials possess mechanical strength, optimization of regeneration at the expense of osteoinductivity by osteokalcin and allow you to effectively fill the cavity with a complex anatomical structure. 

  6. Hafnium - material for chemical apparatus engineering

    International Nuclear Information System (INIS)

    Jennert, D.

    1981-01-01

    This work describes - on the background of available literature - the properties of hafnium in technical quality (DIN-material No. 2.6400) as material for chemical apparatus engineering. The occurence, refining, physical and chemical properties will be described as well as the material behavior. In conclusion, it has been found that there is, at present, sufficient information for the engineering of hafnium which has to be completed by additional investigations for special applications. (orig.) [de

  7. Efficiently mapping structure-property relationships of gas adsorption in porous materials: application to Xe adsorption.

    Science.gov (United States)

    Kaija, A R; Wilmer, C E

    2017-09-08

    Designing better porous materials for gas storage or separations applications frequently leverages known structure-property relationships. Reliable structure-property relationships, however, only reveal themselves when adsorption data on many porous materials are aggregated and compared. Gathering enough data experimentally is prohibitively time consuming, and even approaches based on large-scale computer simulations face challenges. Brute force computational screening approaches that do not efficiently sample the space of porous materials may be ineffective when the number of possible materials is too large. Here we describe a general and efficient computational method for mapping structure-property spaces of porous materials that can be useful for adsorption related applications. We describe an algorithm that generates random porous "pseudomaterials", for which we calculate structural characteristics (e.g., surface area, pore size and void fraction) and also gas adsorption properties via molecular simulations. Here we chose to focus on void fraction and Xe adsorption at 1 bar, 5 bar, and 10 bar. The algorithm then identifies pseudomaterials with rare combinations of void fraction and Xe adsorption and mutates them to generate new pseudomaterials, thereby selectively adding data only to those parts of the structure-property map that are the least explored. Use of this method can help guide the design of new porous materials for gas storage and separations applications in the future.

  8. Simplified method to solve sound transmission through structures lined with elastic porous material.

    Science.gov (United States)

    Lee, J H; Kim, J

    2001-11-01

    An approximate analysis method is developed to calculate sound transmission through structures lined with porous material. Because the porous material has both the solid phase and fluid phase, three wave components exist in the material, which makes the related analysis very complicated. The main idea in developing the approximate method is very simple: modeling the porous material using only the strongest of the three waves, which in effect idealizes the material as an equivalent fluid. The analysis procedure has to be conducted in two steps. In the first step, sound transmission through a flat double panel with a porous liner of infinite extents, which has the same cross sectional construction as the actual structure, is solved based on the full theory and the strongest wave component is identified. In the second step sound transmission through the actual structure is solved modeling the porous material as an equivalent fluid while using the actual geometry of the structure. The development and validation of the method are discussed in detail. As an application example, the transmission loss through double walled cylindrical shells with a porous core is calculated utilizing the simplified method.

  9. Fabrication of Porous Ceramic-Geopolymer Based Material to Improve Water Absorption and Retention in Construction Materials: A Review

    Science.gov (United States)

    Jamil, N. H.; Ibrahim, W. M. A. W.; Abdullah, M. M. A. B.; Sandu, A. V.; Tahir, M. F. M.

    2017-06-01

    Porous ceramic nowadays has been investigated for a variety of its application such as filters, lightweight structural component and others due to their specific properties such as high surface area, stability and permeability. Besides, it has the properties of low thermal conductivity. Various formation techniques making these porous ceramic properties can be tailored or further fine-tuned to obtain the optimum characteristic. Porous materials also one of the good candidate for absorption properties. Conventional construction materials are not design to have good water absorption and retention that lead to the poor performance on these criteria. Temperature is a major driving force for moisture movement and influences sorption characteristics of many constructions materials. The effect of elevated temperatures on the water absorption coefficient and retention remain as critical issue that need to be investigated. Therefore, this paper will review the process parameters in fabricating porous ceramic for absorption properties.

  10. Non-destructive testing method for determining the solvent diffusion coefficient in the porous materials products

    Science.gov (United States)

    Belyaev, V. P.; Mishchenko, S. V.; Belyaev, P. S.

    2018-01-01

    Ensuring non-destructive testing of products in industry is an urgent task. Most of the modern methods for determining the diffusion coefficient in porous materials have been developed for bodies of a given configuration and size. This leads to the need for finished products destruction to make experimental samples from them. The purpose of this study is the development of a dynamic method that allows operatively determine the diffusion coefficient in finished products from porous materials without destroying them. The method is designed to investigate the solvents diffusion coefficient in building constructions from materials having a porous structure: brick, concrete and aerated concrete, gypsum, cement, gypsum or silicate solutions, gas silicate blocks, heat insulators, etc. A mathematical model of the method is constructed. The influence of the design and measuring device operating parameters on the method accuracy is studied. The application results of the developed method for structural porous products are presented.

  11. Fabrication and in vitro degradation of porous fumarate-based polymer/alumoxane nanocomposite scaffolds for bone tissue engineering.

    Science.gov (United States)

    Mistry, Amit S; Cheng, Stacy H; Yeh, Tiffany; Christenson, Elizabeth; Jansen, John A; Mikos, Antonios G

    2009-04-01

    In this work, the fabrication and in vitro degradation of porous fumarate-based/alumoxane nanocomposites were evaluated for their potential as bone tissue engineering scaffolds. The biodegradable polymer poly (propylene fumarate)/propylene fumarate-diacrylate (PPF/PF-DA), a macrocomposite composed of PPF/PF-DA and boehmite microparticles, and a nanocomposite composed of PPF/PF-DA and surface-modified alumoxane nanoparticles were used to fabricate porous scaffolds by photo-crosslinking and salt-leaching. Scaffolds then underwent 12 weeks of in vitro degradation in phosphate buffered saline at 37 degrees C. The presence of boehmite microparticles and alumoxane nanoparticles in the polymer inhibited scaffold shrinkage during crosslinking. Furthermore, the incorporation of alumoxane nanoparticles into the polymer limited salt-leaching, perhaps due to tighter crosslinking within the nanocomposite. Analysis of crosslinking revealed that the acrylate and overall double bond conversions in the nanocomposite were higher than in the PPF/PF-DA polymer alone, though these differences were not significant. During 12 weeks of in vitro degradation, the nanocomposite lost 5.3% +/- 2.4% of its mass but maintained its compressive mechanical properties and porous architecture. The addition of alumoxane nanoparticles into the fumarate-based polymer did not significantly affect the degradation of the nanocomposite compared with the other materials in terms of mass loss, compressive properties, and porous structure. These results demonstrate the feasibility of fabricating degradable nanocomposite scaffolds for bone tissue engineering by photo-crosslinking and salt-leaching mixtures of fumarate-based polymers, alumoxane nanoparticles, and salt microparticles. Copyright 2008 Wiley Periodicals, Inc.

  12. Rankine earth pressure theory considering microstructure of porous materials

    Science.gov (United States)

    Li, Junhu; Xue, Wei; Zhang, Chao; Zhang, Wenchao; Xu, Riqing

    2017-11-01

    Soil as an engineering material has very complex properties, such as non-continuous, non-uniformity and nonlinear mechanical. In a certain extent, macroscopic properties of soil are affected by the changes of the microstructure. And microscopic porosity of soft clay and its influencing factors, the relationship between macro and micro porosity, the average contact area rate and its influencing factors are studied. Some mechanics problems were analyzed by using the relationship between macro-porosity and the average contact area rate. Combining soil lateral stress transfer principle, a calculation theory of earth pressure considering soil contact area was got. The possible reason of the differences between earth pressure and the actual monitoring earth pressure was analyzed by the case.

  13. Biomedical composites materials, manufacturing and engineering

    CERN Document Server

    Davim, J Paulo

    2013-01-01

    Composite materials are engineered materials, made from two or more constituents with significantly different physical or chemical properties which remain separate on a macroscopic level within the finished structure. Due to their special mechanical and physical properties they have the potential to replace conventional materials in various fields such as the biomedical industry.

  14. Teaching materials science and engineering

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    It makes good sense to conclude that the goal of academic teaching should not be seen in ... the wonderful feeling of the young adult to be free not only for professional training, but also for ... competence which a young engineer would like to offer to society. .... methods, to improve lifetime under rough service conditions;.

  15. Porous graphitic materials obtained from carbonization of organic ...

    Indian Academy of Sciences (India)

    features such as pore diameter, hierarchical porous archi- tectures, surface ... bon xerogels seem to be promising candidates for liquid ... co-solvent to increase the solubility of furfural, whilst the .... 100 nm, thus Vt means the total volume of pores below c.a. ..... Wang Z, Zhang X, Liu X, Lv M, Yang K and Meng J 2011 Carbon.

  16. Behavior of fragmentation front in a porous viscoelastic material

    Science.gov (United States)

    Ichihara, M.; Takayama, K.

    2002-12-01

    We are developing laboratory experiments to investigate dynamics of magma fragmentation during explosive volcanic eruptions. Fragmentation of such a mixture as magma consisting of viscoelastic melt, bubbles and solid particles, is not known yet, and experiments are necessary to establish a mathematical model. It has been shown that viscoelastic silicone compound (Dow Corning 3179) is a useful analogous material to simulate magma fragmentation. In the previous work, a porous specimen made of the compound was rapidly decompressed and development of brittle fragmentation was observed. However, there were arguments that the experiment was different from actual processes which produce fragments as small as volcanic ash, because in the experiment the specimen was broken into only several pieces. This time, results of the improved experiments are presented. The experimental apparatus is a kind of a vertical shock tube, which mainly consists of a high pressure test section and low pressure chambers. The test section is made of acrylic tube of which inner diameter is 25 mm. The internal phenomenon is recorded by a high-speed video camera. Pressure is measured in the gas above and beneath the specimen by piezoelectric transducers. The specimen is prepared in the following way. First, an acrylic tube filled with the compound is put in a nitrogen tank and kept at 45 bar for more than 8 hours. The compound absorbs the gas and equilibrates with the nitrogen. Next, the tank is decompressed back to the atmospheric pressure slowly. Nitrogen exsolves and bubbles are formed in the compound quite uniformly. Finally, the expanded compound sticking out of both ends of the tube is cut down, and the tube containing the specimen is attached to the shock tube. The specimen is rapidly decompressed by 24, 16, and 8 bars. The high-speed video images demonstrate a sequence of the fragmentation process. We observe propagation of a clear fracture front at 50 m/s for 24 bar of decompression and at

  17. 2, 3-Dihydrazone cellulose: Prospective material for tissue engineering scaffolds

    International Nuclear Information System (INIS)

    Verma, Vipin; Verma, Poonam; Ray, Pratima; Ray, Alok R.

    2008-01-01

    Cellulose was oxidized by sodium metaperiodate to give rise to 2, 3-dialdehyde cellulose with 92% oxidation ratio, which was further reacted with hydrazine to form 2, 3-dihydrazone cellulose for the incorporation of NH 2 groups. Two forms of matrix, i.e. films and sponges were fabricated. The materials were characterized by FTIR spectroscopy. Scanning electron microscopy revealed its porous architecture with an average pore size of 150 μm. Swelling studies were carried out in phosphate buffer saline (PBS) at physiological pH 7.4. The contact angle of the 2, 3-dihydrazone cellulose surface was determined for assessing its hydrophilicity which came out to be 23 deg. ± 2 deg. NIH3T3 mice fibroblast cells were used for determining the cytocompatibility of the surfaces. The morphology of the cells was observed through optical inverted microscopy. The results show that 2, 3-dihydrazone cellulose can be used as scaffold material in tissue engineering

  18. Biomimetic Materials and Fabrication Approaches for Bone Tissue Engineering.

    Science.gov (United States)

    Kim, Hwan D; Amirthalingam, Sivashanmugam; Kim, Seunghyun L; Lee, Seunghun S; Rangasamy, Jayakumar; Hwang, Nathaniel S

    2017-12-01

    Various strategies have been explored to overcome critically sized bone defects via bone tissue engineering approaches that incorporate biomimetic scaffolds. Biomimetic scaffolds may provide a novel platform for phenotypically stable tissue formation and stem cell differentiation. In recent years, osteoinductive and inorganic biomimetic scaffold materials have been optimized to offer an osteo-friendly microenvironment for the osteogenic commitment of stem cells. Furthermore, scaffold structures with a microarchitecture design similar to native bone tissue are necessary for successful bone tissue regeneration. For this reason, various methods for fabricating 3D porous structures have been developed. Innovative techniques, such as 3D printing methods, are currently being utilized for optimal host stem cell infiltration, vascularization, nutrient transfer, and stem cell differentiation. In this progress report, biomimetic materials and fabrication approaches that are currently being utilized for biomimetic scaffold design are reviewed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Wood handbook : wood as an engineering material

    Science.gov (United States)

    Robert J. Ross; Forest Products Laboratory. USDA Forest Service.

    2010-01-01

    Summarizes information on wood as an engineering material. Presents properties of wood and wood-based products of particular concern to the architect and engineer. Includes discussion of designing with wood and wood-based products along with some pertinent uses.

  20. Engineering Tough Materials: Biomimetic Eggshell

    Science.gov (United States)

    2016-08-29

    Fellow Dr. David Labonte Cambridge University Engineering Dept., Trumpington Street, Cambridge CB2 1PZ, UK ~ Approved for public release; distribution...with a brief outlook, including next steps to pursue in the new cooperative research arrangement between ERDC and the University of Cambridge . Summary...HCl in 2 h at room temperature. Shell & Membrane Shell Outer membrane Inner membrane Figure 1: Cross section of an eggshell illustrating the direct

  1. Rail Engineering and Education Symposium Materials.

    Science.gov (United States)

    2016-05-26

    The objective of this project is to develop curricular materials for the Rail Engineering and Education : Symposia held in the summers of 2012 and 2014. : Description of Activities : The main approach to accomplish the activity is to develop and deli...

  2. Steels from materials science to structural engineering

    CERN Document Server

    Sha, Wei

    2013-01-01

    Steels and computer-based modelling are fast growing fields in materials science as well as structural engineering, demonstrated by the large amount of recent literature. Steels: From Materials Science to Structural Engineering combines steels research and model development, including the application of modelling techniques in steels.  The latest research includes structural engineering modelling, and novel, prototype alloy steels such as heat-resistant steel, nitride-strengthened ferritic/martensitic steel and low nickel maraging steel.  Researchers studying steels will find the topics vital to their work.  Materials experts will be able to learn about steels used in structural engineering as well as modelling and apply this increasingly important technique in their steel materials research and development. 

  3. Obtaining of dense and highly porous ceramic materials from metallurgical slag

    OpenAIRE

    Fidancevska E.; Mangutova B.; Milosevski D.; Milosevski M.; Bossert J.

    2003-01-01

    Glass-ceramics in a dense and highly porous form can be obtained from metallurgical slag and waste glass of TV monitors. Using polyurethane foam as pore creator, a highly porous system with porosity of 65 ± 5 %, E-modulus and flexural strength of 8 ± 3 GPa and 13 ± 3.5 MPa respectively can be obtained. This porous material had durability (mass loss) of 0.03 % in 0.1 M HCl that is identical with the durability of a dense composite.

  4. Obtaining of dense and highly porous ceramic materials from metallurgical slag

    Directory of Open Access Journals (Sweden)

    Fidancevska E.

    2003-01-01

    Full Text Available Glass-ceramics in a dense and highly porous form can be obtained from metallurgical slag and waste glass of TV monitors. Using polyurethane foam as pore creator, a highly porous system with porosity of 65 ± 5 %, E-modulus and flexural strength of 8 ± 3 GPa and 13 ± 3.5 MPa respectively can be obtained. This porous material had durability (mass loss of 0.03 % in 0.1 M HCl that is identical with the durability of a dense composite.

  5. Functional Biomass Carbons with Hierarchical Porous Structure for Supercapacitor Electrode Materials

    International Nuclear Information System (INIS)

    Chen, Hao; Liu, Duo; Shen, Zhehong; Bao, Binfu; Zhao, Shuyan; Wu, Limin

    2015-01-01

    Highlights: • We successfully prepared bamboo-derived porous carbon with B and N co-doping. • This novel carbon exhibits significantly enhanced specific capacitance and energy density. • The highest specific capacitance exceeds those of most similar carbon materials. • Asymmetric supercapacitor based on this carbon shows satisfactory capacitive performance. - Abstract: This paper presents nitrogen and boron co-doped KOH-activated bamboo-derived carbon as a porous biomass carbon with utility as a supercapacitor electrode material. Owing to the high electrochemical activity promoted by the hierarchical porous structure and further endowed by boron and nitrogen co-doping, electrodes based on the as-obtained material exhibit significantly enhanced specific capacitance and energy density relative to those based on most similar materials. An asymmetric supercapacitor based on this novel carbon material demonstrated satisfactory energy density and electrochemical cycling stability.

  6. Dielectric materials for electrical engineering

    CERN Document Server

    Martinez-Vega, Juan

    2013-01-01

    Part 1 is particularly concerned with physical properties, electrical ageing and modeling with topics such as the physics of charged dielectric materials, conduction mechanisms, dielectric relaxation, space charge, electric ageing and life end models and dielectric experimental characterization. Part 2 concerns some applications specific to dielectric materials: insulating oils for transformers, electrorheological fluids, electrolytic capacitors, ionic membranes, photovoltaic conversion, dielectric thermal control coatings for geostationary satellites, plastics recycling and piezoelectric poly

  7. Dynamic characterization of partially saturated engineered porous media and gas diffusion layers using hydraulic admittance

    Science.gov (United States)

    Cheung, Perry; Fairweather, Joseph D.; Schwartz, Daniel T.

    2012-09-01

    Simple laboratory methods for determining liquid water distribution in polymer electrolyte membrane fuel cell gas diffusion layers (GDLs) are needed to engineer better GDL materials. Capillary pressure vs. liquid saturation measurements are attractive, but lack the ability to probe the hydraulic interconnectivity and distribution within the pore structure. Hydraulic admittance measurements of simple capillary bundles have recently been shown to nicely measure characteristics of the free-interfaces and hydraulic path. Here we examine the use of hydraulic admittance with a succession of increasingly complex porous media, starting with a laser-drilled sample with 154 asymmetric pores and progress to the behavior of Toray TGP-H090 carbon papers. The asymmetric laser-drilled sample clearly shows hydraulic admittance measurements are sensitive to sample orientation, especially when examined as a function of saturation state. Finite element modeling of the hydraulic admittance is consistent with experimental measurements. The hydraulic admittance spectra from GDL samples are complex, so we examine trends in the spectra as a function of wet proofing (0% and 40% Teflon loadings) as well as saturation state of the GDL. The presence of clear peaks in the admittance spectra for both GDL samples suggests a few pore types are largely responsible for transporting liquid water.

  8. Thermodynamic analysis of the heat regenerative cycle in porous medium engine

    International Nuclear Information System (INIS)

    Liu Hongsheng; Xie Maozhao; Wu Dan

    2009-01-01

    The advantages of homogeneous combustion in internal combustion engines are well known all over the world. Recent years, porous medium (PM) engine has been proposed as a new type engine based on the technique of combustion in porous medium, which can fulfils all requirements to perform homogeneous combustion. In this paper, working processes of a PM engine are briefly introduced and an ideal thermodynamic model of the PM heat regeneration cycle in PM engine is developed. An expression for the relation between net work output and thermal efficiency is derived for the cycle. In order to evaluate of the cycle, the influences of the expansion ratio, initial temperature and limited temperature on the net work and efficiency are discussed, and the availability terms of the cycle are analyzed. Comparing the PM heat regenerative cycle of the PM engine against Otto cycle and Diesel cycle shows that PM heat regenerative cycle can improve net work output greatly with little drop of efficiency. The aim of this paper is to predict the thermodynamic performance of PM heat regeneration cycle and provide a guide to further investigations of the PM engine

  9. Microstructure, Mechanical Properties and Corrosion Behavior of Porous Mg-6 wt.% Zn Scaffolds for Bone Tissue Engineering

    Science.gov (United States)

    Yan, Yang; Kang, Yijun; Li, Ding; Yu, Kun; Xiao, Tao; Wang, Qiyuan; Deng, Youwen; Fang, Hongjie; Jiang, Dayue; Zhang, Yu

    2018-03-01

    Porous Mg-based scaffolds have been extensively researched as biodegradable implants due to their attractive biological and excellent mechanical properties. In this study, porous Mg-6 wt.% Zn scaffolds were prepared by powder metallurgy using ammonium bicarbonate particles as space-holder particles. The effects of space-holder particle content on the microstructure, mechanical properties and corrosion resistance of the Mg-6 wt.% Zn scaffolds were studied. The mean porosity and pore size of the open-cellular scaffolds were within the range 6.7-52.2% and 32.3-384.2 µm, respectively. Slight oxidation was observed at the grain boundaries and on the pore walls. The Mg-6 wt.% Zn scaffolds were shown to possess mechanical properties comparable with those of natural bone and had variable in vitro degradation rates. Increased content of space-holder particles negatively affected the mechanical behavior and corrosion resistance of the Mg-6 wt.% Zn scaffolds, especially when higher than 20%. These results suggest that porous Mg-6 wt.% Zn scaffolds are promising materials for application in bone tissue engineering.

  10. Fabrication of three-dimensional porous cell-laden hydrogel for tissue engineering

    International Nuclear Information System (INIS)

    Hwang, Chang Mo; Sant, Shilpa; Masaeli, Mahdokht; Kachouie, Nezamoddin N; Zamanian, Behnam; Khademhosseini, Ali; Lee, Sang-Hoon

    2010-01-01

    For tissue engineering applications, scaffolds should be porous to enable rapid nutrient and oxygen transfer while providing a three-dimensional (3D) microenvironment for the encapsulated cells. This dual characteristic can be achieved by fabrication of porous hydrogels that contain encapsulated cells. In this work, we developed a simple method that allows cell encapsulation and pore generation inside alginate hydrogels simultaneously. Gelatin beads of 150-300 μm diameter were used as a sacrificial porogen for generating pores within cell-laden hydrogels. Gelation of gelatin at low temperature (4 0 C) was used to form beads without chemical crosslinking and their subsequent dissolution after cell encapsulation led to generation of pores within cell-laden hydrogels. The pore size and porosity of the scaffolds were controlled by the gelatin bead size and their volume ratio, respectively. Fabricated hydrogels were characterized for their internal microarchitecture, mechanical properties and permeability. Hydrogels exhibited a high degree of porosity with increasing gelatin bead content in contrast to nonporous alginate hydrogel. Furthermore, permeability increased by two to three orders while compressive modulus decreased with increasing porosity of the scaffolds. Application of these scaffolds for tissue engineering was tested by encapsulation of hepatocarcinoma cell line (HepG2). All the scaffolds showed similar cell viability; however, cell proliferation was enhanced under porous conditions. Furthermore, porous alginate hydrogels resulted in formation of larger spheroids and higher albumin secretion compared to nonporous conditions. These data suggest that porous alginate hydrogels may have provided a better environment for cell proliferation and albumin production. This may be due to the enhanced mass transfer of nutrients, oxygen and waste removal, which is potentially beneficial for tissue engineering and regenerative medicine applications.

  11. Dissolved CO2 Increases Breakthrough Porosity in Natural Porous Materials.

    Science.gov (United States)

    Yang, Y; Bruns, S; Stipp, S L S; Sørensen, H O

    2017-07-18

    When reactive fluids flow through a dissolving porous medium, conductive channels form, leading to fluid breakthrough. This phenomenon is caused by the reactive infiltration instability and is important in geologic carbon storage where the dissolution of CO 2 in flowing water increases fluid acidity. Using numerical simulations with high resolution digital models of North Sea chalk, we show that the breakthrough porosity is an important indicator of dissolution pattern. Dissolution patterns reflect the balance between the demand and supply of cumulative surface. The demand is determined by the reactive fluid composition while the supply relies on the flow field and the rock's microstructure. We tested three model scenarios and found that aqueous CO 2 dissolves porous media homogeneously, leading to large breakthrough porosity. In contrast, solutions without CO 2 develop elongated convective channels known as wormholes, with low breakthrough porosity. These different patterns are explained by the different apparent solubility of calcite in free drift systems. Our results indicate that CO 2 increases the reactive subvolume of porous media and reduces the amount of solid residual before reactive fluid can be fully channelized. Consequently, dissolved CO 2 may enhance contaminant mobilization near injection wellbores, undermine the mechanical sustainability of formation rocks and increase the likelihood of buoyance driven leakage through carbonate rich caprocks.

  12. Ultrahigh porous materials and nanocatalysts for energy harvesting and conversion

    International Nuclear Information System (INIS)

    Stamatin, Ioan

    2009-01-01

    Full text: Fuel cells represent a clean alternative to current technologies utilizing hydrocarbon fuel resources and to the photovoltaic technologies as booster to hybrid systems. Since discovered by Groove they developed in few classes depending of the electrolyte type and the working temperatures. Polymer electrolyte membrane fuel cells (PEMFCs) have acquired due importance as they are best suited for applications where a quick start up is required such as in automobiles and by their versatility to be associated with different couples fuel-oxidant such as hydrogen-oxygen or methanol-air to name few. Four main major components are concurrent in designing and engineering of the performing and marketable fuel cells: thermal/fluidic management, bipolar plates, membrane-electrode assembly, hydrogen supply. The latest three involve advanced materials from different parts of the science and technology. The prime requirements of fuel cell membranes are high proton conductivity, low methanol/water permeability, good mechanical and thermal stability and moderate price. Membranes and the operating parameters together have a profound influence on performance of PEMFCs. Perfluorinated ionomers, hydrocarbon and aromatic polymers and acid-base complexes are reviewed considering their structure-property relationship. New materials with potential impact in FC performances and high proton conduction at moderate high temperatures to reduce the catalyst CO-poisoning are taken into account. The role of the semiconducting polymers as component in membranes and support for catalyst is reconsidered based on new results. Nanocatalysts based on Pt alloys or low cost Iron-alloys groups designed via polyol-MW-synthesis open a new direction to the engineering of high performance electrocatalysts by controlling size- shape- surface electrochemical activity. The role of the nanotubes and nanowalls as catalyst support and gas diffusion layer is reconsidered in the context of the new technology

  13. Materials for advanced power engineering 2010. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Lecomte-Beckers, Jacqueline; Contrepois, Quentin; Beck, Tilmann; Kuhn, Bernd [eds.

    2010-07-01

    The 9th Liege Conference on ''Materials for Advanced Power Engineering'' presents the results of the materials related COST Actions 536 ''Alloy Development for Critical Components of Environmentally Friendly Power Plants'' and 538 ''High Temperature Plant Lifetime Extension''. In addition, the broad field of current materials research perspectives for high efficiency, low- and zero- emission power plants and new energy technologies for the next decades are reported. The Conference proceedings are structured as follows: 1. Materials for advanced steam power plants; 2. Gas turbine materials; 3. Materials for nuclear fission and fusion; 4. Solid oxide fuel cells; 5. Corrosion, thermomechanical fatigue and modelling; 6. Zero emission power plants.

  14. Materials for advanced power engineering 2010. Proceedings

    International Nuclear Information System (INIS)

    Lecomte-Beckers, Jacqueline; Contrepois, Quentin; Beck, Tilmann; Kuhn, Bernd

    2010-01-01

    The 9th Liege Conference on ''Materials for Advanced Power Engineering'' presents the results of the materials related COST Actions 536 ''Alloy Development for Critical Components of Environmentally Friendly Power Plants'' and 538 ''High Temperature Plant Lifetime Extension''. In addition, the broad field of current materials research perspectives for high efficiency, low- and zero- emission power plants and new energy technologies for the next decades are reported. The Conference proceedings are structured as follows: 1. Materials for advanced steam power plants; 2. Gas turbine materials; 3. Materials for nuclear fission and fusion; 4. Solid oxide fuel cells; 5. Corrosion, thermomechanical fatigue and modelling; 6. Zero emission power plants.

  15. Hierarchically Porous Carbon Materials for CO 2 Capture: The Role of Pore Structure

    Energy Technology Data Exchange (ETDEWEB)

    Estevez, Luis [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Barpaga, Dushyant [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Zheng, Jian [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Sabale, Sandip [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Patel, Rajankumar L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Zhang, Ji-Guang [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; McGrail, B. Peter [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Motkuri, Radha Kishan [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States

    2018-01-17

    With advances in porous carbon synthesis techniques, hierarchically porous carbon (HPC) materials are being utilized as relatively new porous carbon sorbents for CO2 capture applications. These HPC materials were used as a platform to prepare samples with differing textural properties and morphologies to elucidate structure-property relationships. It was found that high microporous content, rather than overall surface area was of primary importance for predicting good CO2 capture performance. Two HPC materials were analyzed, each with near identical high surface area (~2700 m2/g) and colossally high pore volume (~10 cm3/g), but with different microporous content and pore size distributions, which led to dramatically different CO2 capture performance. Overall, large pore volumes obtained from distinct mesopores were found to significantly impact adsorption performance. From these results, an optimized HPC material was synthesized that achieved a high CO2 capacity of ~3.7 mmol/g at 25°C and 1 bar.

  16. Porous starch/cellulose nanofibers composite prepared by salt leaching technique for tissue engineering.

    Science.gov (United States)

    Nasri-Nasrabadi, Bijan; Mehrasa, Mohammad; Rafienia, Mohammad; Bonakdar, Shahin; Behzad, Tayebeh; Gavanji, Shahin

    2014-08-08

    Starch/cellulose nanofibers composites with proper porosity pore size, mechanical strength, and biodegradability for cartilage tissue engineering have been reported in this study. The porous thermoplastic starch-based composites were prepared by combining film casting, salt leaching, and freeze drying methods. The diameter of 70% nanofibers was in the range of 40-90 nm. All samples had interconnected porous morphology; however an increase in pore interconnectivity was observed when the sodium chloride ratio was increased in the salt leaching. Scaffolds with the total porogen content of 70 wt% exhibited adequate mechanical properties for cartilage tissue engineering applications. The water uptake ratio of nanocomposites was remarkably enhanced by adding 10% cellulose nanofibers. The scaffolds were partially destroyed due to low in vitro degradation rate after more than 20 weeks. Cultivation of isolated rabbit chondrocytes on the fabricated scaffold proved that the incorporation of nanofibers in starch structure improves cell attachment and proliferation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Simultaneous Contact Sensing and Characterizing of Mechanical and Dynamic Heat Transfer Properties of Porous Polymeric Materials

    Directory of Open Access Journals (Sweden)

    Bao-guo Yao

    2017-10-01

    Full Text Available Porous polymeric materials, such as textile fabrics, are elastic and widely used in our daily life for garment and household products. The mechanical and dynamic heat transfer properties of porous polymeric materials, which describe the sensations during the contact process between porous polymeric materials and parts of the human body, such as the hand, primarily influence comfort sensations and aesthetic qualities of clothing. A multi-sensory measurement system and a new method were proposed to simultaneously sense the contact and characterize the mechanical and dynamic heat transfer properties of porous polymeric materials, such as textile fabrics in one instrument, with consideration of the interactions between different aspects of contact feels. The multi-sensory measurement system was developed for simulating the dynamic contact and psychological judgment processes during human hand contact with porous polymeric materials, and measuring the surface smoothness, compression resilience, bending and twisting, and dynamic heat transfer signals simultaneously. The contact sensing principle and the evaluation methods were presented. Twelve typical sample materials with different structural parameters were measured. The results of the experiments and the interpretation of the test results were described. An analysis of the variance and a capacity study were investigated to determine the significance of differences among the test materials and to assess the gage repeatability and reproducibility. A correlation analysis was conducted by comparing the test results of this measurement system with the results of Kawabata Evaluation System (KES in separate instruments. This multi-sensory measurement system provides a new method for simultaneous contact sensing and characterizing of mechanical and dynamic heat transfer properties of porous polymeric materials.

  18. Numerical modeling in materials science and engineering

    CERN Document Server

    Rappaz, Michel; Deville, Michel

    2003-01-01

    This book introduces the concepts and methodologies related to the modelling of the complex phenomena occurring in materials processing. After a short reminder of conservation laws and constitutive relationships, the authors introduce the main numerical methods: finite differences, finite volumes and finite elements. These techniques are developed in three main chapters of the book that tackle more specific problems: phase transformation, solid mechanics and fluid flow. The two last chapters treat inverse methods to obtain the boundary conditions or the material properties and stochastic methods for microstructural simulation. This book is intended for undergraduate and graduate students in materials science and engineering, mechanical engineering and physics and for engineering professionals or researchers who want to get acquainted with numerical simulation to model and compute materials processing.

  19. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    Science.gov (United States)

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. The Enhancement of 3D Scans Depth Resolution Obtained by Confocal Scanning of Porous Materials

    Science.gov (United States)

    Martisek, Dalibor; Prochazkova, Jana

    2017-12-01

    The 3D reconstruction of simple structured materials using a confocal microscope is widely used in many different areas including civil engineering. Nonetheless, scans of porous materials such as concrete or cement paste are highly problematic. The well-known problem of these scans is low depth resolution in comparison to the horizontal and vertical resolution. The degradation of the image depth resolution is caused by systematic errors and especially by different random events. Our method is focused on the elimination of such random events, mainly the additive noise. We use an averaging method based on the Lindeberg-Lévy theorem that improves the final depth resolution to a level comparable with horizontal and vertical resolution. Moreover, using the least square method, we also precisely determine the limit value of a depth resolution. Therefore, we can continuously evaluate the difference between current resolution and the optimal one. This substantially simplifies the scanning process because the operator can easily determine the required number of scans.

  1. The Enhancement of 3D Scans Depth Resolution Obtained by Confocal Scanning of Porous Materials

    Directory of Open Access Journals (Sweden)

    Martisek Dalibor

    2017-12-01

    Full Text Available The 3D reconstruction of simple structured materials using a confocal microscope is widely used in many different areas including civil engineering. Nonetheless, scans of porous materials such as concrete or cement paste are highly problematic. The well-known problem of these scans is low depth resolution in comparison to the horizontal and vertical resolution. The degradation of the image depth resolution is caused by systematic errors and especially by different random events. Our method is focused on the elimination of such random events, mainly the additive noise. We use an averaging method based on the Lindeberg-Lévy theorem that improves the final depth resolution to a level comparable with horizontal and vertical resolution. Moreover, using the least square method, we also precisely determine the limit value of a depth resolution. Therefore, we can continuously evaluate the difference between current resolution and the optimal one. This substantially simplifies the scanning process because the operator can easily determine the required number of scans.

  2. ANALYSIS OF INTERNAL COMBUSTION ENGINE WITH A NEW CONCEPT OF POROUS MEDIUM COMBUSTION FOR THE FUTURE CLEAN ENGINE

    Directory of Open Access Journals (Sweden)

    Ashok A Dhale

    2010-01-01

    Full Text Available At present, the emissions of internal combustion engine can only be improved by catalytic treatments of the exhaust gases. Such treatments, however, result in high costs and relatively low conversion efficiency. This suggests that a new combustion technique should be developed to yield improved primary combustion processes inside the engine with drastically reduced exhaust gas emissions. To fulfill all requirements, Dr. Franz Drust has proposed a new combustion concept to perform homogenous combustion in internal combustion engines. This concept used the porous medium combustion technique and is called "PM-engine". It is shown that the PM combustion technique can be applied to internal combustion engines. Theoretical considerations are presented for internal combustion engines, indicating that an overall improvement in thermal efficiency can be achieved for the PM-engine. This is explained and general performance of the new PM-engines is demonstrated for a single cylinder, water cooled, direct injection diesel engine. Verification of experiments at primary stage is described that were carried out as a part of the present study.

  3. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials

    NARCIS (Netherlands)

    Ganendra, G; De Muynck, W; Ho, A.; Hoefman, S.; De Vos, P.; Boeckx, P.; Boon, N.

    2014-01-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (similar to 20 % (v/v)) and low (similar to 100 ppmv) methane

  4. Molecular simulation strategy for mechanical modeling of amorphous/porous low-dielectric constant materials

    NARCIS (Netherlands)

    Yuan, C.A.; Sluis, van der O.; Zhang, G.Q.; Ernst, L.J.; Driel, van W.D.; Flower, A.E.; Silfhout, van R.B.R.

    2008-01-01

    We propose an amorphous/porous molecular connection network generation algorithm for simulating the material stiffness of a low-k material (SiOC:H). Based on a given concentration of the basic building blocks, this algorithm will generate an approximate and large amorphous network. The molecular

  5. Thermal performance of circular convective–radiative porous fins with different section shapes and materials

    International Nuclear Information System (INIS)

    Hatami, M.; Ganji, D.D.

    2013-01-01

    Graphical abstract: - Highlights: • LSM is an accurate technique for simulating heat transfer in circular porous fins. • Rectangular, convex, triangular and exponential variable sections are considered. • Radiation and convection from porous fin are considered. • Effects of material and geometry on heat transfer from fins are studied. - Abstract: In this study, heat transfer and temperature distribution equations for circular convective–radiative porous fins are presented. It’s assumed that the thickness of circular fins varies with radius so four different shapes, rectangular, convex, triangular and exponential, are considered. The heat transfer through porous media is simulated using passage velocity from the Darcy’s model. After deriving equation for each geometry, Least Square Method (LSM) and fourth order Runge–Kutta method (NUM) are applied for predicting the temperature distribution in the porous fins. The selected porous fin’s materials are Al, SiC, Cu and Si 3 N 4 . Results reveal that LSM has very effective and accurate in comparison with the numerical results. As a main outcome, Si 3 N 4 -exponential section fin has the maximum amount of transferred heat among other fins

  6. Different radiation impedance models for finite porous materials

    DEFF Research Database (Denmark)

    Nolan, Melanie; Jeong, Cheol-Ho; Brunskog, Jonas

    2015-01-01

    The Sabine absorption coefficients of finite absorbers are measured in a reverberation chamber according to the international standard ISO 354. They vary with the specimen size essentially due to diffraction at the specimen edges, which can be seen as the radiation impedance differing from...... the infinite case. Thus, in order to predict the Sabine absorption coefficients of finite porous samples, one can incorporate models of the radiation impedance. In this study, different radiation impedance models are compared with two experimental examples. Thomasson’s model is compared to Rhazi’s method when...

  7. SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head

    International Nuclear Information System (INIS)

    Siefken, L. J.; Harvego, E. A.

    2000-01-01

    A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model has been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material may permeate to near the bottom of a 1m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material was calculated to cause a 12% increase in the heat flux on the external surface of the lower head

  8. Evaluation of egg white ovomucin-based porous scaffold as an implantable biomaterial for tissue engineering.

    Science.gov (United States)

    Carpena, Nathaniel T; Abueva, Celine D G; Padalhin, Andrew R; Lee, Byong-Taek

    2017-10-01

    Studies have shown the technological and functional properties of ovomucin (OVN) in the food-agricultural industry. But research has yet to explore its potential as an implantable biomaterial for tissue engineering and regenerative medicine. In this study we isolated OVN from egg white by isoelectric precipitation and fabricated scaffolds with tunable porosity by utilizing its foaming property. Gelatin a known biocompatible material was introduced to stabilize the foams, wherein different ratios of OVN and gelatin had a significant effect on the degree of porosity, pore size and stability of the formed hydrogels. The porous scaffolds were crosslinked with EDC resulting in stable scaffolds with prolonged degradation. Improved cell proliferation and adhesion of rat bone marrow-derived mesenchymal stem cells were observed for OVN containing scaffolds. Although, scaffolds with 75% OVN showed decrease in cell proliferation for L929 fibroblast type of cells. Further biocompatibility assessment as implant material was determined by subcutaneous implantation in rats of selected scaffold. H&E staining showed reasonable vascularization over time and little evidence of severe fibrosis at the implant site. Persistent polarization of classically activated macrophage was not observed, potentially reducing inflammatory response, and showed increased expression of alternatively activated macrophage cells that is favorable for tissue repair. Analysis of IgE levels in rat serum after implantation indicated minimal and resolvable allergic response to the OVN implants. The results demonstrate OVN as an acceptable implant scaffold that could provide new opportunities as an alternative natural biocompatible and functional biomaterial in various biomedical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2107-2117, 2017. © 2016 Wiley Periodicals, Inc.

  9. Natural Origin Materials for Osteochondral Tissue Engineering.

    Science.gov (United States)

    Bonani, Walter; Singhatanadgige, Weerasak; Pornanong, Aramwit; Motta, Antonella

    2018-01-01

    Materials selection is a critical aspect for the production of scaffolds for osteochondral tissue engineering. Synthetic materials are the result of man-made operations and have been investigated for a variety of tissue engineering applications. Instead, the products of physiological processes and the metabolic activity of living organisms are identified as natural materials. Over the recent decades, a number of natural materials, namely, biopolymers and bioceramics, have been proposed as the main constituent of osteochondral scaffolds, but also as cell carriers and signaling molecules. Overall, natural materials have been investigated both in the bone and in the cartilage compartment, sometimes alone, but often in combination with other biopolymers or synthetic materials. Biopolymers and bioceramics possess unique advantages over their synthetic counterparts due similarity with natural extracellular matrix, the presence of cell recognition sites and tunable chemistry. However, the characteristics of natural origin materials can vary considerably depending on the specific source and extraction process. A deeper understanding of the relationship between material variability and biological activity and the definition of standardized manufacturing procedures will be crucial for the future of natural materials in tissue engineering.

  10. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants

    Energy Technology Data Exchange (ETDEWEB)

    Gryshkov, Oleksandr, E-mail: gryshkov@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany); Klyui, Nickolai I., E-mail: klyuini@ukr.net [College of Physics, Jilin University, 130012 Changchun (China); V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Temchenko, Volodymyr P., E-mail: tvp@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Kyselov, Vitalii S., E-mail: kyselov@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Chatterjee, Anamika, E-mail: chatterjee@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany); Belyaev, Alexander E., E-mail: belyaev@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Lauterboeck, Lothar, E-mail: lauterboeck@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany); Iarmolenko, Dmytro, E-mail: iarmolenko.dmytro@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Glasmacher, Birgit, E-mail: glasmacher@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany)

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO{sub 2}) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO{sub 2} using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO{sub 2} to the initial HA powder resulted in significant decomposition of the final HA/ZrO{sub 2} coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO{sub 2} coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. - Highlights: • Synthesis and characterization of porous biomorphic SiC ceramics derived from wood • Successful deposition of bioactive calcium phosphate coatings using gas detonation deposition • Porosity and pore size of Si

  11. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants

    International Nuclear Information System (INIS)

    Gryshkov, Oleksandr; Klyui, Nickolai I.; Temchenko, Volodymyr P.; Kyselov, Vitalii S.; Chatterjee, Anamika; Belyaev, Alexander E.; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-01-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO 2 ) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO 2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO 2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO 2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO 2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. - Highlights: • Synthesis and characterization of porous biomorphic SiC ceramics derived from wood • Successful deposition of bioactive calcium phosphate coatings using gas detonation deposition • Porosity and pore size of SiC ceramics depend on wood

  12. Frontiers of advanced engineering materials (faem-06)

    International Nuclear Information System (INIS)

    Alam, S.; Mirza, J.A.

    2006-01-01

    The second international conference on Frontiers of Advanced Engineering Materials was held on 04-06 December 2006 in Lahore, Pakistan. At a time of the rapid expending enormous potential for the wide spread development and usage of Advanced Engineering Materials. About 121 papers were presented by engineers and scientists from 30 organizations, academic institutions and foreign experts from six countries. on the recommendation of a panel after review, only 72 papers were included in this conference proceedings. The main areas of interest which remained under focus during the conference were structure property relationship, surface Modifications, Nano Technology, Super and semi conductors, Magnetic Materials, Materials Proceeding, Glass and Ceramics, Composite Materials. This Conference open a way to help in strengthening the bounds between our foreign guests local and delegates. The participants showed their keen interest in the poster sessions. Fruitful conclusions of these presentations will be helpful to give rise to new topics of research in the fields of advanced engineering Materials. (A.B.)

  13. Systems and strippable coatings for decontaminating structures that include porous material

    Science.gov (United States)

    Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

    2011-12-06

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  14. Development of chemically engineered porous metal oxides for phosphate removal

    International Nuclear Information System (INIS)

    Delaney, Paul; McManamon, Colm; Hanrahan, John P.; Copley, Mark P.; Holmes, Justin D.; Morris, Michael A.

    2011-01-01

    In this study, the application of ordered mesoporous silica (OMS) doped with various metal oxides (Zr, Ti, Fe and Al) were studied for the removal of (ortho) phosphate ions from water by adsorption. The materials were characterized by means of N 2 physisorption (BET), powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The doped materials had surface areas between 600 and 700 m 2 g -1 and exhibited pore sizes of 44-64 A. Phosphate adsorption was determined by measurement of the aqueous concentration of orthophosphate using ultraviolet-visible (UV-vis) spectroscopy before and after extraction. The effects of different metal oxide loading ratios, initial concentration of phosphate solution, temperature and pH effects on the efficiency of phosphate removal were investigated. The doped mesoporous materials were effective adsorbents of orthophosphate and up to 100% removal was observed under appropriate conditions. 'Back extracting' the phosphate from the doped silica (following water treatment) was also investigated and shown to have little adverse effect on the adsorbent.

  15. Porous Na2O-B2O3-Nd2O3 material

    Energy Technology Data Exchange (ETDEWEB)

    De Villiers, D R; Res, M A; Richter, P W

    1986-12-01

    Substitution of SiO2 by Nd2O3 in the sodium borosilicate system produced glasses containing up to 50 mass% Nd2O3. Sodium borate was leached out of some of the materials to produce either a porous Nd2O3-rich glass or a porous glass-ceramic containing NdBO3, depending on the starting material. Surface areas of up to 190 mS g- were measured. Powder X-ray diffraction (XRD) revealed the NdBO3 to be the high-temperature form with low symmetry.

  16. Sound Transmission Through Multi-Panel Structures Lined with Elastic Porous Materials

    Science.gov (United States)

    Bolton, J. S.; Shiau, N.-M.; Kang, Y. J.

    1996-04-01

    Theory and measurements related to sound transmission through double panels lined with elastic porous media are presented. The information has application to the design of noise control barriers and to the optimization of aircraft fuselage transmission loss, for example. The major difference between the work described here and earlier research in this field relates to the treatment of the porous material that is used to line the cavity between the two panels of the double panel structure. Here we have used the porous material theory proposed by Biot since it takes explicit account of all the wave types known to propagate in elastic porous materials. As a result, it is possible to use the theory presented here to calculate the transmission loss of lined double panels at arbitrary angles of incidence; results calculated over a range of incidence angles may then be combined to yield the random incidence transmission loss. In this paper, the equations governing wave propagation in an elastic porous material are first considered briefly and then the general forms for the stresses and displacements within the porous material are given. Those solutions are expressed in terms of a number of constants that can be determined by application of appropriate boundary conditions. The boundary conditions required to model double panels having linings that are either directly attached to the facing panels or separated?!from them by air gaps are presented and discussed. Measurements of the random incidence transmission loss of aluminium double-panel structures lined with polyurethane foam are presented and have been found to be in good agreement with theoretical predictions. Both the theoretical predictions and the measured results have shown that the method by which an elastic porous lining material is attached to the facing panels can have a profound influence on the transmission loss of the panel system. It has been found, for example, that treatments in which the lining material

  17. Porous heat-treated polyacrylonitrile scaffolds for bone tissue engineering

    Czech Academy of Sciences Publication Activity Database

    Vetrík, Miroslav; Pařízek, Martin; Hadraba, Daniel; Kukačková, Olivia; Brus, Jiří; Hlídková, Helena; Kománková, Lucie; Hodan, Jiří; Sedláček, Ondřej; Šlouf, Miroslav; Bačáková, Lucie; Hrubý, Martin

    2018-01-01

    Roč. 10, č. 10 (2018), s. 8496-8506 ISSN 1944-8244 R&D Projects: GA MZd(CZ) NV15-32497A; GA MŠk(CZ) LM2015064; GA MZd(CZ) NV16-30544A; GA ČR(CZ) GA16-03156S Institutional support: RVO:61389013 ; RVO:67985823 Keywords : 3D scaffolds * black orlon * carbon-based material Subject RIV: CD - Macromolecular Chemistry; EI - Biotechnology ; Bionics (FGU-C) OBOR OECD: Polymer science; Biomaterials (as related to medical implants, devices, sensors) (FGU-C) Impact factor: 7.504, year: 2016

  18. Recipes for porous building materials, More with less

    NARCIS (Netherlands)

    Brouwers, H.J.H.; Fischer, H.-B.; Bode, K.-A.; Beuthan, C.

    2012-01-01

    The building sector, comprising both buildings and infrastructure, is the largest consumer of energy and materials. As well as the huge amount of raw materials involved, enormous amounts of energy are also used for the production and transport of raw materials, building materials and products. Among

  19. Cooperation of micro- and meso-porous carbon electrode materials in electric double-layer capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Cheng [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Qi, Li; Wang, Hongyu [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Yoshio, Masaki [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

    2010-07-01

    The capacitive characteristics of micro- and meso-porous carbon materials have been compared in cyclic voltammetric studies and galvanostatic charge-discharge tests. Meso-porous carbon can keep certain high capacitance values at high scan rates, whereas micro-porous carbon possesses very high capacitance values at low scan rates but fades quickly as the scan rate rises up. For better performance of electric double-layer capacitors (EDLCs), the cooperative application of both kinds of carbon materials has been proposed in the following two ways: mixing both kinds of carbons in the same electrode or using the asymmetric configuration of carbon electrodes in the same EDLC. The cooperative effect on the electrochemical performance has also been addressed. (author)

  20. Porous decellularized tissue engineered hypertrophic cartilage as a scaffold for large bone defect healing.

    Science.gov (United States)

    Cunniffe, Gráinne M; Vinardell, Tatiana; Murphy, J Mary; Thompson, Emmet M; Matsiko, Amos; O'Brien, Fergal J; Kelly, Daniel J

    2015-09-01

    Clinical translation of tissue engineered therapeutics is hampered by the significant logistical and regulatory challenges associated with such products, prompting increased interest in the use of decellularized extracellular matrix (ECM) to enhance endogenous regeneration. Most bones develop and heal by endochondral ossification, the replacement of a hypertrophic cartilaginous intermediary with bone. The hypothesis of this study is that a porous scaffold derived from decellularized tissue engineered hypertrophic cartilage will retain the necessary signals to instruct host cells to accelerate endogenous bone regeneration. Cartilage tissue (CT) and hypertrophic cartilage tissue (HT) were engineered using human bone marrow derived mesenchymal stem cells, decellularized and the remaining ECM was freeze-dried to generate porous scaffolds. When implanted subcutaneously in nude mice, only the decellularized HT-derived scaffolds were found to induce vascularization and de novo mineral accumulation. Furthermore, when implanted into critically-sized femoral defects, full bridging was observed in half of the defects treated with HT scaffolds, while no evidence of such bridging was found in empty controls. Host cells which had migrated throughout the scaffold were capable of producing new bone tissue, in contrast to fibrous tissue formation within empty controls. These results demonstrate the capacity of decellularized engineered tissues as 'off-the-shelf' implants to promote tissue regeneration. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Applications of hierarchically structured porous materials from energy storage and conversion, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine.

    Science.gov (United States)

    Sun, Ming-Hui; Huang, Shao-Zhuan; Chen, Li-Hua; Li, Yu; Yang, Xiao-Yu; Yuan, Zhong-Yong; Su, Bao-Lian

    2016-06-13

    Over the last decade, significant effort has been devoted to the applications of hierarchically structured porous materials owing to their outstanding properties such as high surface area, excellent accessibility to active sites, and enhanced mass transport and diffusion. The hierarchy of porosity, structural, morphological and component levels in these materials is key for their high performance in all kinds of applications. The introduction of hierarchical porosity into materials has led to a significant improvement in the performance of materials. Herein, recent progress in the applications of hierarchically structured porous materials from energy conversion and storage, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine is reviewed. Their potential future applications are also highlighted. We particularly dwell on the relationship between hierarchically porous structures and properties, with examples of each type of hierarchically structured porous material according to its chemical composition and physical characteristics. The present review aims to open up a new avenue to guide the readers to quickly obtain in-depth knowledge of applications of hierarchically porous materials and to have a good idea about selecting and designing suitable hierarchically porous materials for a specific application. In addition to focusing on the applications of hierarchically porous materials, this comprehensive review could stimulate researchers to synthesize new advanced hierarchically porous solids.

  2. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures

    KAUST Repository

    Mughal, Asad Jahangir

    2014-01-01

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material\\'s luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon. This journal is

  3. A diffusivity model for predicting VOC diffusion in porous building materials based on fractal theory

    International Nuclear Information System (INIS)

    Liu, Yanfeng; Zhou, Xiaojun; Wang, Dengjia; Song, Cong; Liu, Jiaping

    2015-01-01

    Highlights: • Fractal theory is introduced into the prediction of VOC diffusion coefficient. • MSFC model of the diffusion coefficient is developed for porous building materials. • The MSFC model contains detailed pore structure parameters. • The accuracy of the MSFC model is verified by independent experiments. - Abstract: Most building materials are porous media, and the internal diffusion coefficients of such materials have an important influences on the emission characteristics of volatile organic compounds (VOCs). The pore structure of porous building materials has a significant impact on the diffusion coefficient. However, the complex structural characteristics bring great difficulties to the model development. The existing prediction models of the diffusion coefficient are flawed and need to be improved. Using scanning electron microscope (SEM) observations and mercury intrusion porosimetry (MIP) tests of typical porous building materials, this study developed a new diffusivity model: the multistage series-connection fractal capillary-bundle (MSFC) model. The model considers the variable-diameter capillaries formed by macropores connected in series as the main mass transfer paths, and the diameter distribution of the capillary bundles obeys a fractal power law in the cross section. In addition, the tortuosity of the macrocapillary segments with different diameters is obtained by the fractal theory. Mesopores serve as the connections between the macrocapillary segments rather than as the main mass transfer paths. The theoretical results obtained using the MSFC model yielded a highly accurate prediction of the diffusion coefficients and were in a good agreement with the VOC concentration measurements in the environmental test chamber.

  4. The Comparison of Engineering Properties Between Single and Double Layer Porous Asphalt made of Packing Gradation

    Directory of Open Access Journals (Sweden)

    Hardiman M. Y

    2008-01-01

    Full Text Available is paper presents the comparison of engineering properties between single and double layer porous asphalt (SLPA and DLPA made of packing gradation. Three nominal maximum aggregate sizes (NMAS were tested each made up of 10, 14, and 20 mm for SLPA. While for the DLPA with 30, 20, and 15 mm top layer are made of 10 and 14 mm NMAS, with a base layer of 20 mm NMAS. Total thickness of all mixes is 70 mm. Binders used are 60/70 penetration base bitumen and polymer binder styrene-butadiene-styrene (SBS. The result shows that the properties of SLPA mix namely permeability and resistance to abrasion loss decreases when the NMAS in SLPA decreases. The abrasion loss of DLPA mixes increases when the porous asphalt top layer thickness decreases, while drainage time value decreases. However, SLPA with 20 mm NMAS exhibits higher abrasion loss compared to all DLPA mixes.

  5. Preparation and Photocatalytic Property of TiO2/Diatomite-Based Porous Ceramics Composite Materials

    Directory of Open Access Journals (Sweden)

    Shuilin Zheng

    2012-01-01

    Full Text Available The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor of TiO2 and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at 550°C, TiO2 thin film loaded on the diatomite-based porous ceramics is anatase TiO2 and average grain size of TiO2 is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.

  6. Preparing technicians for engineering materials technology

    Science.gov (United States)

    Jacobs, James A.; Metzloff, Carlton H.

    1990-01-01

    A long held principle is that for every engineer and scientist there is a need for ten technicians to maximize the efficiency of the technology team for meeting needs of industry and government. Developing an adequate supply of technicians to meet the requirements of the materials related industry will be a challenge and difficult to accomplish. A variety of agencies feel the need and wish to support development of engineering materials technology programs. In a joint effort among Battelle Laboratories, the Department of Energy (DOE) and Northwest College and University Association for Science (NORCUS), the development of an engineering materials technology program for vocational programs and community colleges for the Pacific Northwest Region was recently completed. This effort has implications for a national model. The model Associate of Applied Science degree in Engineering Materials Technology shown provides a general structure. It purposely has course titles which need delimiting while also including a core of courses necessary to develop cognitive, affective and psychomotor skills with the underlining principles of math, science and technology so students have job entry skills, and so that students can learn about and adapt to evolving technology.

  7. Process of making porous ceramic materials with controlled porosity

    Science.gov (United States)

    Anderson, Marc A.; Ku, Qunyin

    1993-01-01

    A method of making metal oxide ceramic material is disclosed by which the porosity of the resulting material can be selectively controlled by manipulating the sol used to make the material. The method can be used to make a variety of metal oxide ceramic bodies, including membranes, but also pellets, plugs or other bodies. It has also been found that viscous sol materials can readily be shaped by extrusion into shapes typical of catalytic or adsorbent bodies used in industry, to facilitate the application of such materials for catalytic and adsorbent applications.

  8. Measurements of Acoustic Properties of Porous and Granular Materials and Application to Vibration Control

    Science.gov (United States)

    Park, Junhong; Palumbo, Daniel L.

    2004-01-01

    For application of porous and granular materials to vibro-acoustic controls, a finite dynamic strength of the solid component (frame) is an important design factor. The primary goal of this study was to investigate structural vibration damping through this frame wave propagation for various poroelastic materials. A measurement method to investigate the vibration characteristics of the frame was proposed. The measured properties were found to follow closely the characteristics of the viscoelastic materials - the dynamic modulus increased with frequency and the degree of the frequency dependence was determined by its loss factor. The dynamic stiffness of hollow cylindrical beams containing porous and granular materials as damping treatment was measured also. The data were used to extract the damping materials characteristics using the Rayleigh-Ritz method. The results suggested that the acoustic structure interaction between the frame and the structure enhances the dissipation of the vibration energy significantly.

  9. Materials for advanced power engineering 2010. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Lecomte-Beckers, Jacqueline; Contrepois, Quentin; Beck, Tilmann; Kuhn, Bernd (eds.)

    2010-07-01

    The 9th Liege Conference on ''Materials for Advanced Power Engineering'' presents the results of the materials related COST Actions 536 ''Alloy Development for Critical Components of Environmentally Friendly Power Plants'' and 538 ''High Temperature Plant Lifetime Extension''. In addition, the broad field of current materials research perspectives for high efficiency, low- and zero- emission power plants and new energy technologies for the next decades are reported. The Conference proceedings are structured as follows: 1. Materials for advanced steam power plants; 2. Gas turbine materials; 3. Materials for nuclear fission and fusion; 4. Solid oxide fuel cells; 5. Corrosion, thermomechanical fatigue and modelling; 6. Zero emission power plants.

  10. Improvements in or relating to method of preparing porous material/synthetic polymer composites

    International Nuclear Information System (INIS)

    Hills, P.R.; McGahan, D.J.

    1976-01-01

    Monomers in a porous natural material, e.g. cellulose fibre, wood, are polymerized with gamma radiation. Addition of a chlorinated hydrocarbon to the monomer improves fire resistance, brittleness and friction coefficient and reduces the radiation dose required for polymerization. (U.K.)

  11. Multiscale network model for simulating liquid water and water vapour transfer properties of porous materials

    NARCIS (Netherlands)

    Carmeliet, J.; Descamps, F.; Houvenaghel, G.

    1999-01-01

    A multiscale network model is presented to model unsaturated moisture transfer in hygroscopic capillary-porous materials showing a broad pore-size distribution. Both capillary effects and water sorption phenomena, water vapour and liquid water transfer are considered. The multiscale approach is

  12. An artificial compressibility CBS method for modelling heat transfer and fluid flow in heterogeneous porous materials

    CSIR Research Space (South Africa)

    Malan, AG

    2011-08-01

    Full Text Available to modelling both forced convection as well as heat transfer and fluid flow through heterogeneous saturated porous materials via an edge-based finite volume discretization scheme. A volume-averaged set of local thermal disequilibrium governing equations...

  13. INVESTIGATION OF HEAT CONDUCTION AND SPECIFIC ELECTRIC IMPEDANCE OF POROUS MATERIALS

    Directory of Open Access Journals (Sweden)

    E. S. Golubtsova

    2004-01-01

    Full Text Available In this article there was investigated the influence of porosity and temperature change on heat condition and electrical resistance of porous iron (PZh4M nickel and steel 14X17H2. There are received the adequate equations of regression, establishing connection between heat conduction and electrical resistance of the investigated materials with their porosity and temperature.

  14. Numerical modelling of porous cement-based materials by superabsorbent polymers

    DEFF Research Database (Denmark)

    Viejo, Ismael; Esteves, Luis Pedro; Laspalas, Manuel

    2016-01-01

    The development of new cementitious materials raises new challenges with regard to structural design. One of the potential applications of superabsorbent polymers (SAP) is to deliver well-defined porosity to cement systems. This is particularly interesting for the development of porous cement...

  15. Identification of Water Diffusivity of Inorganic Porous Materials Using Evolutionary Algorithms

    Czech Academy of Sciences Publication Activity Database

    Kočí, J.; Maděra, J.; Jerman, M.; Keppert, M.; Svora, Petr; Černý, R.

    2016-01-01

    Roč. 113, č. 1 (2016), s. 51-66 ISSN 0169-3913 Institutional support: RVO:61388980 Keywords : Evolutionary algorithms * Water transport * Inorganic porous materials * Inverse analysis Subject RIV: CA - Inorganic Chemistry Impact factor: 2.205, year: 2016

  16. PRODUCTION OF POROUS POWDER MATERIALS OF SPHERICAL POWDERS OF CORROSION-RESISTANT STEEL

    Directory of Open Access Journals (Sweden)

    V. N. Kovalevskij

    2012-01-01

    Full Text Available Production of porous powder materials from spherical powders of corrosion-resistant steel 12Х18н10Т with formation at low pressures 120–140 mpa in the mold with the subsequent activated sintering became possible due to increase of duration of process of spattering and formation of condensate particles (Si–C or (Mo–Si on surface.

  17. Strength degradation and failure limits of dense and porous ceramic membrane materials

    DEFF Research Database (Denmark)

    Pećanac, G.; Foghmoes, Søren Preben Vagn; Lipińska-Chwałek, M.

    2013-01-01

    Thin dense membrane layers, mechanically supported by porous substrates, are considered as the most efficient designs for oxygen supply units used in Oxy-fuel processes and membrane reactors. Based on the favorable permeation properties and chemical stability, several materials were suggested...

  18. Computational homogenization of sound propagation in a deformable porous material including microscopic viscous-thermal effects

    NARCIS (Netherlands)

    Gao, K.; van Dommelen, J. A. W.; Göransson, P.; Geers, M. G. D.

    2016-01-01

    Porous materials like acoustic foams can be used for acoustic shielding, which is important for high-tech systems and human comfort. In this paper, a homogenization model is proposed to investigate the relation between the microstructure and the resulting macroscopic acoustic properties. The

  19. Modeling of radionuclide migration through porous material with meshless method

    International Nuclear Information System (INIS)

    Vrankar, L.; Turk, G.; Runovc, F.

    2005-01-01

    To assess the long term safety of a radioactive waste disposal system, mathematical models are used to describe groundwater flow, chemistry and potential radionuclide migration through geological formations. A number of processes need to be considered when predicting the movement of radionuclides through the geosphere. The most important input data are obtained from field measurements, which are not completely available for all regions of interest. For example, the hydraulic conductivity as an input parameter varies from place to place. In such cases geostatistical science offers a variety of spatial estimation procedures. Methods for solving the solute transport equation can also be classified as Eulerian, Lagrangian and mixed. The numerical solution of partial differential equations (PDE) is usually obtained by finite difference methods (FDM), finite element methods (FEM), or finite volume methods (FVM). Kansa introduced the concept of solving partial differential equations using radial basis functions (RBF) for hyperbolic, parabolic and elliptic PDEs. Our goal was to present a relatively new approach to the modelling of radionuclide migration through the geosphere using radial basis function methods in Eulerian and Lagrangian coordinates. Radionuclide concentrations will also be calculated in heterogeneous and partly heterogeneous 2D porous media. We compared the meshless method with the traditional finite difference scheme. (author)

  20. Design of Molecular Materials: Supramolecular Engineering

    Science.gov (United States)

    Simon, Jacques; Bassoul, Pierre

    2001-02-01

    This timely and fascinating book is destined to be recognised as THE book on supramolecular engineering protocols. It covers this sometimes difficult subject in an approachable form, gathering together information from many sources. Supramolecular chemistry, which links organic chemistry to materials science, is one of the fastest growth areas of chemistry research. This book creates a correlation between the structure of single molecules and the physical and chemical properties of the resulting materials. By making systematic changes to the component molecules, the resulting solid can be engineered for optimum performance. There is a clearly written development from synthesis of designer molecules to properties of solids and further on to devices and complex materials systems, providing guidelines for mastering the organisation of these systems. Topics covered include: Systemic chemistry Molecular assemblies Notions of symmetry Supramolecular engineering Principe de Curie Organisation in molecular media Molecular semiconductors Industrial applications of molecular materials This superb book will be invaluable to researchers in the field of supramolecular materials and also to students and teachers of the subject.

  1. Aircraft and ancillary materials. 2. ; Engine materials. Kokuki to sono shuhen zairyo. 2. ; Engine zairyo

    Energy Technology Data Exchange (ETDEWEB)

    1993-04-05

    This paper summarizes materials for aircraft engines. Jet engines are the mainstream today, which are classified according to their operation process into a turbo jet engine, a turbo prop engine, a turbo shaft engine, and a turbo fan engine. Japan has produced 1543 engines in the past decade, almost all of which are supplied to the Defense Agency. Jet engines use mainly Ni-group heat-resistant alloys, titanium alloys and steels. Improvement of engine efficiency has caused turbine inlet temperatures to rise to 1400[degree]C to 1500[degree]C that give rise to grain boundary cracking. To prevent this, discussions are in progress on monocrystal blades replacing the conventional polycrystal precision casts. Intermetallic compounds including Al/Ti are expected especially of use as jet engine constructing materials from their high melting point and formability. Discussions are preceding on ceramics as to coating them intended of improving heat resistance. Composite materials have a problem of insufficient mechanical strength remaining unsolved. 8 figs., 5 tabs.

  2. Facile Fabrication of 3D Hierarchically Porous Carbon Foam as Supercapacitor Electrode Material

    Directory of Open Access Journals (Sweden)

    Yunfang Gao

    2018-04-01

    Full Text Available A hierarchically porous 3D starch-derived carbon foam (SCF with a high specific surface area (up to 1693 m2·g−1 was first prepared by a facile solvothermal treatment, in which Na2CO3 is used as both the template and activating agent. The hierarchically porous structure and high specific area endow the SCF with favorable electrochemical properties such as a high specific capacitance of 179.6 F·g−1 at 0.5 A·g−1 and a great rate capability and cycling stability, which suggest that the material can be a promising candidate for energy storage applications.

  3. Effective diffusion coefficients of /sup 3/H/sub 2/O in several porous materials

    Energy Technology Data Exchange (ETDEWEB)

    Terashima, Y [Kyoto Univ. (Japan). Faculty of Engineering; Kumaki, T

    1976-12-01

    Diffusion coefficients of radionuclides in some porous structural materials and porous components of earth stratum are important as the basis for the safety evaluation of the storage and disposal of radioactive wastes. In our previous works, the method of analysis and experiment using a permeative type diffusion cell for measurement of effective diffusion coefficient was established, and experimental results were reported. In this paper, effective diffusion coefficients of /sup 3/H/sub 2/O in mortar, concrete, brick, clay layer, and sand layer were measured, and characteristics of these pore structure were discussed on the basis of tourtusity factor.

  4. Effective diffusion coefficients of 3H2O in several porous materials

    International Nuclear Information System (INIS)

    Terashima, Yutaka; Kumaki, Toru.

    1976-01-01

    Diffusion coefficients of radionuclides in some porous structural materials and porous components of earth stratum are important as the basis for the safety evaluation of the storage and disposal of radioactive wastes. In our previous works, the method of analysis and experiment using a permeative type diffusion cell for measurement of effective diffusion coefficient was established, and experimental results were reported. In this paper, effective diffusion coefficients of 3 H 2 O in mortar, concrete, brick, clay layer, and sand layer were measured, and characteristics of these pore structure were discussed on the basis of tourtusity factor. (auth.)

  5. Sound transmission through stiffened double-panel structures lined with elastic porous materials

    Science.gov (United States)

    Mathur, Gopal P.; Tran, Boi N.; Bolton, J. S.; Shiau, Nae-Ming

    This paper presents transmission loss prediction models for a periodically stiffened panel and stiffened double-panel structures using the periodic structure theory. The inter-panel cavity in the double-panels structures can be modeled as being separated by an airspace or filled with an elastic porous layer in various configurations. The acoustic behavior of elastic porous layer is described by a theory capable of accounting fully for multi-dimensional wave propagation in such materials. The predicted transmission loss of a single stiffened panel is compared with the measured data.

  6. Hydrogen Storage in Porous Materials and Magnesium Hydrides

    NARCIS (Netherlands)

    Grzech, A.

    2013-01-01

    In this thesis representatives of two different types of materials for potential hydrogen storage application are presented. Usage of either nanoporous materials or metal hydrides has both operational advantages and disadvantages. A main objective of this thesis is to characterize the hydrogen

  7. Engineered polycaprolactone–magnesium hybrid biodegradable porous scaffold for bone tissue engineering

    Directory of Open Access Journals (Sweden)

    Hoi Man Wong

    2014-10-01

    Full Text Available In this paper, we describe the fabrication of a new biodegradable porous scaffold composed of polycaprolactone (PCL and magnesium (Mg micro-particles. The compressive modulus of PCL porous scaffold was increased to at least 150% by incorporating 29% Mg particles with the porosity of 74% using Micro-CT analysis. Surprisingly, the compressive modulus of this scaffold was further increased to at least 236% when the silane-coupled Mg particles were added. In terms of cell viability, the scaffold modified with Mg particles significantly convinced the attachment and growth of osteoblasts as compared with the pure PCL scaffold. In addition, the hybrid scaffold was able to attract the formation of apatite layer over its surface after 7 days of immersion in normal culture medium, whereas it was not observed on the pure PCL scaffold. This in vitro result indicated the enhanced bioactivity of the modified scaffold. Moreover, enhanced bone forming ability was also observed in the rat model after 3 months of implantation. Though bony in-growth was found in all the implanted scaffolds. High volume of new bone formation could be found in the Mg/PCL hybrid scaffolds when compared to the pure PCL scaffold. Both pure PCL and Mg/PCL hybrid scaffolds were degraded after 3 months. However, no tissue inflammation was observed. In conclusion, these promising results suggested that the incorporation of Mg micro-particles into PCL porous scaffold could significantly enhance its mechanical and biological properties. This modified porous bio-scaffold may potentially apply in the surgical management of large bone defect fixation.

  8. Fabrication of 3-Dimensional Porous Graphene Materials for Lithium Ion Batteries

    International Nuclear Information System (INIS)

    Jiang, Yu; Jiang, Zhong-Jie; Cheng, Shuang; Liu, Meilin

    2014-01-01

    A simple two-step procedure involving hydrothermal reaction and subsequent calcination has been employed to synthesis porous graphene material, which exhibits significantly high electrochemical performance when used as the anode in lithium ion batteries. - Highlights: • A PGM been synthesized by a simple two-step process involving hydrothermal reaction and subsequent calcination. • The PGM exhibits exhibit a significantly high specific surface area. • The PGM can deliver large capacities and excellent cycling performance when used in LIBs. • The high electrochemical performance of the PGM is attributed to its unique porous structure with more disordered carbon atoms. - Abstract: A 3-dimensional porous graphene material (PGM) has been synthesized using a simple two-step process: hydrothermal reaction and calcination. Hydrothermal reaction of graphene oxide (GO) in the presence of resorcinol and glutaraldehyde leads to covalent grafting of partially reduced GO with glutaraldehyde and the deposition of phenolic resin. Subsequent calcination of the composite consisting of phenolic resin deposited on partially reduced GO in the presence of KOH produces structurally stable, highly porous graphene material with a specific surface area of ∼1,066 ± 2 m 2 g −1 . When used as an active electrode material in a lithium battery, the PGM exhibits an initial discharge capacity of ∼1,538 mAh g −1 , which is significantly higher than those of graphite and other carbonaceous materials reported previously. More importantly, when cycled at higher discharge/charge rates, the PGM-based electrodes still deliver large capacities and excellent cycling performance, demonstrating great potential for high-performance lithium-ion batteries. The attractive electrochemical performance of the PGM is attributed to its unique porous structure with large specific surface area and the presence of more disordered carbon atoms produced by the KOH activation

  9. Apparatus and test method for characterizing the temperature regulating properties of thermal functional porous polymeric materials.

    Science.gov (United States)

    Yao, Bao-Guo; Zhang, Shan; Zhang, De-Pin

    2017-05-01

    In order to evaluate the temperature regulating properties of thermal functional porous polymeric materials such as fabrics treated with phase change material microcapsules, a new apparatus was developed. The apparatus and the test method can measure the heat flux, temperature, and displacement signals during the dynamic contact and then quickly give an evaluation for the temperature regulating properties by simulating the dynamic heat transfer and temperature regulating process when the materials contact the body skin. A series of indices including the psychosensory intensity, regulating capability index, and relative regulating index were defined to characterize the temperature regulating properties. The measurement principle, the evaluation criteria and grading method, the experimental setup and the test results discussion, and the gage capability analysis of the apparatus are presented. The new apparatus provides a method for the objective measurement and evaluation of the temperature regulating properties of thermal functional porous polymeric materials.

  10. Materials, processes, and environmental engineering network

    Science.gov (United States)

    White, Margo M.

    1993-01-01

    The Materials, Processes, and Environmental Engineering Network (MPEEN) was developed as a central holding facility for materials testing information generated by the Materials and Processes Laboratory. It contains information from other NASA centers and outside agencies, and also includes the NASA Environmental Information System (NEIS) and Failure Analysis Information System (FAIS) data. Environmental replacement materials information is a newly developed focus of MPEEN. This database is the NASA Environmental Information System, NEIS, which is accessible through MPEEN. Environmental concerns are addressed regarding materials identified by the NASA Operational Environment Team, NOET, to be hazardous to the environment. An environmental replacement technology database is contained within NEIS. Environmental concerns about materials are identified by NOET, and control or replacement strategies are formed. This database also contains the usage and performance characteristics of these hazardous materials. In addition to addressing environmental concerns, MPEEN contains one of the largest materials databases in the world. Over 600 users access this network on a daily basis. There is information available on failure analysis, metals and nonmetals testing, materials properties, standard and commercial parts, foreign alloy cross-reference, Long Duration Exposure Facility (LDEF) data, and Materials and Processes Selection List data.

  11. Porous materials with optimal adsorption thermodynamics and kinetics for CO2 separation

    KAUST Repository

    Nugent, Patrick S.

    2013-02-27

    The energy costs associated with the separation and purification of industrial commodities, such as gases, fine chemicals and fresh water, currently represent around 15 per cent of global energy production, and the demand for such commodities is projected to triple by 2050 (ref. 1). The challenge of developing effective separation and purification technologies that have much smaller energy footprints is greater for carbon dioxide (CO2) than for other gases; in addition to its involvement in climate change, CO 2 is an impurity in natural gas, biogas (natural gas produced from biomass), syngas (CO/H 2, the main source of hydrogen in refineries) and many other gas streams. In the context of porous crystalline materials that can exploit both equilibrium and kinetic selectivity, size selectivity and targeted molecular recognition are attractive characteristics for CO 2 separation and capture, as exemplified by zeolites 5A and 13X (ref. 2), as well as metal-organic materials (MOMs). Here we report that a crystal engineering or reticular chemistry strategy that controls pore functionality and size in a series of MOMs with coordinately saturated metal centres and periodically arrayed hexafluorosilicate (SiF 6 2-) anions enables a \\'sweet spot\\' of kinetics and thermodynamics that offers high volumetric uptake at low CO2 partial pressure (less than 0.15 bar). Most importantly, such MOMs offer an unprecedented CO 2 sorption selectivity over N2, H 2 and CH 4, even in the presence of moisture. These MOMs are therefore relevant to CO2 separation in the context of post-combustion (flue gas, CO2/N2), pre-combustion (shifted synthesis gas stream, CO 2/H 2) and natural gas upgrading (natural gas clean-up, CO2/CH 4). © 2013 Macmillan Publishers Limited. All rights reserved.

  12. Tailored Materials for High Efficiency CIDI Engines

    Energy Technology Data Exchange (ETDEWEB)

    Grant, G.J.; Jana, S.

    2012-03-30

    The overall goal of the project, Tailored Materials for High Efficiency Compression Ignition Direct Injection (CIDI) Engines, is to enable the implementation of new combustion strategies, such as homogeneous charge compression ignition (HCCI), that have the potential to significantly increase the energy efficiency of current diesel engines and decrease fuel consumption and environmental emissions. These strategies, however, are increasing the demands on conventional engine materials, either from increases in peak cylinder pressure (PCP) or from increases in the temperature of operation. The specific objective of this project is to investigate the application of a new material processing technology, friction stir processing (FSP), to improve the thermal and mechanical properties of engine components. The concept is to modify the surfaces of conventional, low-cost engine materials. The project focused primarily on FSP in aluminum materials that are compositional analogs to the typical piston and head alloys seen in small- to mid-sized CIDI engines. Investigations have been primarily of two types over the duration of this project: (1) FSP of a cast hypoeutectic Al-Si-Mg (A356/357) alloy with no introduction of any new components, and (2) FSP of Al-Cu-Ni alloys (Alloy 339) by physically stirring-in various quantities of carbon nanotubes/nanofibers or carbon fibers. Experimental work to date on aluminum systems has shown significant increases in fatigue lifetime and stress-level performance in aluminum-silicon alloys using friction processing alone, but work to demonstrate the addition of carbon nanotubes and fibers into aluminum substrates has shown mixed results due primarily to the difficulty in achieving porosity-free, homogeneous distributions of the particulate. A limited effort to understand the effects of FSP on steel materials was also undertaken during the course of this project. Processed regions were created in high-strength, low-alloyed steels up to 0.5 in

  13. Preparation and characterization of porous crosslinked collagenous matrices containing bioavailable chondroitin sulphate

    NARCIS (Netherlands)

    Pieper, J.S.; Oosterhof, A.; Dijkstra, Pieter J.; Veerkamp, J.H.; van Kuppevelt, T.H.

    1999-01-01

    Porous collagen matrices with defined physical, chemical and biological characteristics are interesting materials for tissue engineering. Attachment of glycosaminoglycans (GAGs) may add to these characteristics and valorize collagen. In this study, porous type I collagen matrices were crosslinked

  14. Degradation and biocompatibility of porous nano-hydroxyapatite/polyurethane composite scaffold for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Dong Zhihong [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China); Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Li Yubao, E-mail: nic7504@scu.edu.cn [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China); Zou Qin [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China)

    2009-04-01

    Porous scaffold containing 30 wt% nano-hydroxyapatite (n-HA) and 70 wt% polyurethane (PU) from castor oil was prepared by a foaming method and investigated by X-ray diffraction (XRD), Fourier transform infrared absorption (FTIR), scanning electron microscopy (SEM) techniques. The results show that n-HA particles disperse homogeneously in the PU matrix. The porous scaffold has not only macropores of 100-800 {mu}m in size but also a lot of micropores on the walls of macropores. The porosity and compressive strength of scaffold are 80% and 271 kPa, respectively. After soaking in simulated body fluid (SBF), hydrolysis and deposition partly occur on the scaffold. The biological evaluation in vitro and in vivo shows that the n-HA/PU scaffold is non-cytotoxic and degradable. The porous structure provides a good microenvironment for cell adherence, growth and proliferation. The n-HA/PU composite scaffold can be satisfied with the basic requirement for tissue engineering, and has the potential to be applied in repair and substitute of human menisci of the knee-joint and articular cartilage.

  15. Investigation of Overrun-Processed Porous Hyaluronic Acid Carriers in Corneal Endothelial Tissue Engineering.

    Directory of Open Access Journals (Sweden)

    Jui-Yang Lai

    Full Text Available Hyaluronic acid (HA is a linear polysaccharide naturally found in the eye and therefore is one of the most promising biomaterials for corneal endothelial regenerative medicine. This study reports, for the first time, the development of overrun-processed porous HA hydrogels for corneal endothelial cell (CEC sheet transplantation and tissue engineering applications. The hydrogel carriers were characterized to examine their structures and functions. Evaluations of carbodiimide cross-linked air-dried and freeze-dried HA samples were conducted simultaneously for comparison. The results indicated that during the fabrication of freeze-dried HA discs, a technique of introducing gas bubbles in the aqueous biopolymer solutions can be used to enlarge pore structure and prevent dense surface skin formation. Among all the groups studied, the overrun-processed porous HA carriers show the greatest biological stability, the highest freezable water content and glucose permeability, and the minimized adverse effects on ionic pump function of rabbit CECs. After transfer and attachment of bioengineered CEC sheets to the overrun-processed HA hydrogel carriers, the therapeutic efficacy of cell/biopolymer constructs was tested using a rabbit model with corneal endothelial dysfunction. Clinical observations including slit-lamp biomicroscopy, specular microscopy, and corneal thickness measurements showed that the construct implants can regenerate corneal endothelium and restore corneal transparency at 4 weeks postoperatively. Our findings suggest that cell sheet transplantation using overrun-processed porous HA hydrogels offers a new way to reconstruct the posterior corneal surface and improve endothelial tissue function.

  16. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures.

    Science.gov (United States)

    Mughal, A; El Demellawi, J K; Chaieb, Sahraoui

    2014-12-14

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material's luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon.

  17. The materials used in bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Tereshchenko, V. P., E-mail: tervp@ngs.ru; Kirilova, I. A.; Sadovoy, M. A.; Larionov, P. M. [Novosibirsk Research Institute of Traumatology and Orthopedics n.a. Ya.L. Tsivyan, Novosibirsk (Russian Federation)

    2015-11-17

    Bone tissue engineering looking for an alternative solution to the problem of skeletal injuries. The method is based on the creation of tissue engineered bone tissue equivalent with stem cells, osteogenic factors, and scaffolds - the carriers of these cells. For production of tissue engineered bone equivalent is advisable to create scaffolds similar in composition to natural extracellular matrix of the bone. This will provide optimal conditions for the cells, and produce favorable physico-mechanical properties of the final construction. This review article gives an analysis of the most promising materials for the manufacture of cell scaffolds. Biodegradable synthetic polymers are the basis for the scaffold, but it alone cannot provide adequate physical and mechanical properties of the construction, and favorable conditions for the cells. Addition of natural polymers improves the strength characteristics and bioactivity of constructions. Of the inorganic compounds, to create cell scaffolds the most widely used calcium phosphates, which give the structure adequate stiffness and significantly increase its osteoinductive capacity. Signaling molecules do not affect the physico-mechanical properties of the scaffold, but beneficial effect is on the processes of adhesion, proliferation and differentiation of cells. Biodegradation of the materials will help to fulfill the main task of bone tissue engineering - the ability to replace synthetic construct by natural tissues that will restore the original anatomical integrity of the bone.

  18. Potential of hybrid functionalized meso-porous materials for the separation and immobilization of radionuclides

    International Nuclear Information System (INIS)

    Luca, V.

    2013-01-01

    Functionalized meso-porous materials are a class of hybrid organic-inorganic material in which a meso-porous metal oxide framework is functionalized with multifunctional organic molecules. These molecules may contain one or more anchor groups that form strong bonds to the pore surfaces of the metal oxide framework and free functional groups that can impart and or modify the functionality of the material such as for binding metal ions in solution. Such materials have been extensively studied over the past decade and are of particular interest in absorption applications because of the tremendous versatility in choosing the composition and architecture of the metal oxide framework and the nature of the functional organic molecule as well as the efficient mass transfer that can occur through a well-designed hierarchically porous network. A sorbent for nuclear applications would have to be highly selective for particular radio nuclides, it would need to be hydrolytically and radiolytically stable, and it would have to possess reasonable capacity and fast kinetics. The sorbent would also have to be available in a form suitable for use in a column. Finally, it would also be desirable if once saturated with radio nuclides, the sorbent could be recycled or converted directly into a ceramic or glass waste form suitable for direct repository disposal or even converted directly into a material that could be used as a transmutation target. Such a cradle-to- grave strategy could have many benefits in so far as process efficiency and the generation of secondary wastes are concerned.This paper will provide an overview of work done on all of the above mentioned aspects of the development of functionalized meso-porous adsorbent materials for the selective separation of lanthanides and actinides and discuss the prospects for future implementation of a cradle-to-grave strategy with such materials. (author)

  19. Behavior of engineered nanoparticles in aqueous solutions and porous media: Connecting experimentation to probabilistic analysis

    Science.gov (United States)

    Contreras, Carolina

    2011-12-01

    Engineered nanoparticles have enhanced products and services in the fields of medicine, energy, engineering, communications, personal care, environmental treatment, and many others. The increased use of engineered nanoparticles in consumer products will lead to these materials in natural systems, inevitably becoming a potential source of pollution. The study of the stability and mobility of these materials is fundamental to understand their behavior in natural systems and predict possible health and environmental implications. In addition, the use of probabilistic methods such as sensitivity analysis applied to the parameters controlling their behavior is useful in providing support in performing a risk assessment. This research investigated the stability and mobility of two types of metal oxide nanoparticles (aluminum oxide and titanium dioxide). The stability studies tested the effect of sand, pH 4, 7, and 10, and the NaCl in concentrations of 10mM, 25mM, 50mM, and 75mM. The mobility was tested using saturated quartz sand columns and nanoparticles suspension at pH 4 and 7 and in the presence of NaCl and CaCl2 in concentrations of 0.1mM, 1mM, and 10mM. Additionally, this work performed a sensitivity analysis of physical parameters used in mobility experiment performed for titanium dioxide and in mobility experiments taken from the literature for zero valent iron nanoparticles and fluorescent colloids to determine their effect on the value C/Co of by applying qualitative and quantitative methods. The results from the stability studies showed that titanium dioxide nanoparticles (TiO2) could remain suspended in solution for up to seven days at pH 10 and pH 7 even after settling of the sand; while for pH 4 solutions titanium settled along with the sand and after seven days no particles were observed in suspension. Other stability studies showed that nanoparticle aluminum oxide (Al2O3) and titanium dioxide (TiO2) size increased with increasing ionic strength (10 to 75

  20. Kinetic and catalytic performance of a BI-porous composite material in catalytic cracking and isomerisation reactions

    KAUST Repository

    Al-Khattaf, S.

    2012-01-10

    Catalytic behaviour of pure zeolite ZSM-5 and a bi-porous composite material (BCM) were investigated in transformation of m-xylene, while zeolite HY and the bi-porous composite were used in the cracking of 1,3,5-triisopropylbenzene (TIPB). The micro/mesoporous material was used to understand the effect of the presence of mesopores on these reactions. Various characterisation techniques, that is, XRD, SEM, TGA, FT-IR and nitrogen sorption measurements were applied for complete characterisation of the catalysts. Catalytic tests using CREC riser simulator showed that the micro/mesoporous composite catalyst exhibited higher catalytic activity as compared with the conventional microporous ZSM-5 and HY zeolite for transformation of m-xylene and for the catalytic cracking of TIPB, respectively. The outstanding catalytic reactivity of m-xylene and TIPB molecules were mainly attributed to the easier access of active sites provided by the mesopores. Apparent activation energies for the disappearance of m-xylene and TIPB over all catalysts were found to decrease in the order: EBCM>EZSM-5 and EBCM>EHY, respectively. © 2012 Canadian Society for Chemical Engineering.

  1. Oxygen-rich hierarchical porous carbon made from pomelo peel fiber as electrode material for supercapacitor

    Science.gov (United States)

    Li, Jing; Liu, Wenlong; Xiao, Dan; Wang, Xinhui

    2017-09-01

    Oxygen-rich hierarchical porous carbon has been fabricated using pomelo peel fiber as a carbon source via an improved KOH activation method. The morphology and chemical composition of the obtained carbon materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), electron microscopy (EM), Raman spectra and elemental analysis. The unique porous structure with abundant oxygen functional groups is favorable to capacitive behavior, and the as-prepared carbon material exhibits high specific capacitance of 222.6 F g-1 at 0.5 A g-1 in 6 M KOH and superior stability over 5000 cycles. This work not only describes a simple way to prepare high-performance carbon material from the discarded pomelo peel, but also provides a strategy for its disposal issue and contributes to the environmental improvement.

  2. Modelling critical degrees of saturation of porous building materials subjected to freezing

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1996-01-01

    of SCR based on fracture mechanics and phase geometry of two-phase materials has been developed.The degradation is modelled as being caused by different eigenstrains of the pore phase and the solid phase when freezing, leading to stress concentrations and crack propagation. Simplifications are made......Frost resistance of porous materials can be characterized by the critical degree of saturation, SCR, and the actual degree of saturation, SACT. An experimental determination of SCR is very laborious and therefore only seldom used when testing frost resistance. A theoretical model for prediction...... to describe the development of stresses and the pore structure, because a mathematical description of the physical theories explaining the process of freezing of water in porous materials is lacking.Calculations are based on porosity, modulus of elasticity and tensile strength, and parameters characterizing...

  3. Fenton detemplation of ordered (meso)porous materials

    NARCIS (Netherlands)

    Melian-Cabrera, I.; Osman, A. H.; van Eck, E. R. H.; Kentgens, Arno P.M.; Polushkin, E.; Kapteijn, F.; Moulijn, J. A.; Xu, R; Gao, Z; Chen, J; Yan, W

    2007-01-01

    This article describes a new methodology (Fenton detemplation), which consists of removing the template by chemical oxidation and develop the material's porosity. The oxidizing agents are OH radicals, which are generated from H(2)O(2) in the presence of catalytic amounts of Fe cations. This is known

  4. Characterization of porous materials by small-angle scattering

    Indian Academy of Sciences (India)

    radiation is used in some cases to access large length scale and also to minimize the effect ... For numerous industrial and technological applications, it is often necessary to ... catalytic systems and gas burners require materials to be permeable and to provide ... We have estimated the scattering mean free path L, the.

  5. Preparation of steel slag porous sound-absorbing material using coal powder as pore former.

    Science.gov (United States)

    Sun, Peng; Guo, Zhancheng

    2015-10-01

    The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50% (wt.%), percentage of coal powder of 30% (wt.%), sintering temperature of 1130°C, and sintering time of 6.0hr, which were determined by analyzing the properties of the sound-absorbing material. Copyright © 2015. Published by Elsevier B.V.

  6. Estimation of local mechanical properties of highly porous ceramic materials

    Czech Academy of Sciences Publication Activity Database

    Marcián, P.; Majer, Z.; Dlouhý, Ivo; Florian, Z.

    2012-01-01

    Roč. 106, č. 3 (2012), S476-S477 ISSN 0009-2770 R&D Projects: GA ČR(CZ) GA101/09/1821 Institutional support: RVO:68081723 Keywords : cellular structures * tensile test * microCT * image processing * FEM Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.453, year: 2012 http://chemicke-listy.cz/docs/full/2012_s3_s405-s441.pdf

  7. Porous Materials for Hydrolytic Dehydrogenation of Ammonia Borane

    OpenAIRE

    Umegaki, Tetsuo; Xu, Qiang; Kojima, Yoshiyuki

    2015-01-01

    Hydrogen storage is still one of the most significant issues hindering the development of a “hydrogen energy economy”. Ammonia borane is notable for its high hydrogen densities. For the material, one of the main challenges is to release efficiently the maximum amount of the stored hydrogen. Hydrolysis reaction is a promising process by which hydrogen can be easily generated from this compound. High purity hydrogen from this compound can be evolved in the presence of solid acid or metal based ...

  8. Manufacturing of porous boron steels potentially useful as nuclear materials

    International Nuclear Information System (INIS)

    Abenojar, Juana; Velasco, Francisco; Martinez, Miguel Angel

    2006-01-01

    B 4 C is a good neutron absorber, commonly used together with light materials in panels. The objective of this work is to manufacture high boron steels, using B 4 C additions, through mechanical alloying and sintering, to get a material potentially useful for nuclear waste management. The porosity of the material can help to the removal of helium bubbles. Iron and B 4 C powders were mechanically alloyed for different times, following the process studying apparent density, morphology (SEM) and structure (XRD). Powder was uniaxially compacted and sintered at different conditions. Specimens were analysed by SEM and physical and mechanical properties were evaluated (density, dimensional change and bending strength). Microstructures are very different and therefore, they have different properties depending on sintering temperature. Although boride formation always takes place, only ferritic areas were found at 600degC, meanwhile ferritic and perlitic areas appeared at 900degC, and both of them disappeared at 1,200degC. (author)

  9. Molecular simulation of capillary phase transitions in flexible porous materials

    Science.gov (United States)

    Shen, Vincent K.; Siderius, Daniel W.; Mahynski, Nathan A.

    2018-03-01

    We used flat-histogram sampling Monte Carlo to study capillary phase transitions in deformable adsorbent materials. Specifically, we considered a pure adsorbate fluid below its bulk critical temperature within a slit pore of variable pore width. The instantaneous pore width is dictated by a number of factors, such as adsorbate loading, reservoir pressure, fluid-wall interaction, and bare adsorbent properties. In the slit pores studied here, the bare adsorbent free energy was assumed to be biparabolic, consisting of two preferential pore configurations, namely, the narrow pore and the large pore configurations. Four distinct phases could be found in the adsorption isotherms. We found a low-pressure phase transition, driven primarily by capillary condensation/evaporation and accompanied by adsorbent deformation in response. The deformation can be a relatively small contraction/expansion as seen in elastic materials, or a large-scale structural transformation of the adsorbent. We also found a high-pressure transition driven by excluded volume effects, which tends to expand the material and thus results in a large-scale structural transformation of the adsorbent. The adsorption isotherms and osmotic free energies can be rationalized by considering the relative free energy differences between the basins of the bare adsorbent free energy.

  10. Analysis of Void Growth and Coalescence in Porous Polymer Materials. Coalescence in Polymer Materials

    Directory of Open Access Journals (Sweden)

    S. A. Reffas

    2013-06-01

    Full Text Available The use of polymeric materials in engineering applications is growing more and more all over the world. This issue requests new methodologies of analysis in order to assess the material’s capability to withstand complex loads. The use of polyacetal in engineering applications has increased rapidly in the last decade. In order to evaluate the behavior, the damage and coalescence of this type of polymer, a numerical method based on damage which occurs following several stages (nucleation of cavities, their growth and coalescence in more advanced stages of deformation is proposed in this work. A particular attention is given on the stress-strain and the volumetric strain evolution under different triaxiality and for three initial void shapes. Its application to polyacetal allows approving this approach for technical polymers. Finally, this method allow us to compare the obtained results of basic calculations at different triaxiality and to discuss their possible influence on the initial size and the geometrical shape of the porosity on the material failure.

  11. Kinetic and catalytic performance of a BI-porous composite material in catalytic cracking and isomerisation reactions

    KAUST Repository

    Al-Khattaf, S.; Odedairo, T.; Balasamy, R. J.

    2012-01-01

    Catalytic behaviour of pure zeolite ZSM-5 and a bi-porous composite material (BCM) were investigated in transformation of m-xylene, while zeolite HY and the bi-porous composite were used in the cracking of 1,3,5-triisopropylbenzene (TIPB). The micro

  12. Mechanical and materials engineering of modern structure and component design

    CERN Document Server

    Altenbach, Holm

    2015-01-01

    This book presents the latest findings on mechanical and materials engineering as applied to the design of modern engineering materials and components. The contributions cover the classical fields of mechanical, civil and materials engineering, as well as bioengineering and advanced materials processing and optimization. The materials and structures discussed can be categorized into modern steels, aluminium and titanium alloys, polymers/composite materials, biological and natural materials, material hybrids and modern nano-based materials. Analytical modelling, numerical simulation, state-of-the-art design tools and advanced experimental techniques are applied to characterize the materials’ performance and to design and optimize structures in different fields of engineering applications.

  13. A diffusivity model for predicting VOC diffusion in porous building materials based on fractal theory.

    Science.gov (United States)

    Liu, Yanfeng; Zhou, Xiaojun; Wang, Dengjia; Song, Cong; Liu, Jiaping

    2015-12-15

    Most building materials are porous media, and the internal diffusion coefficients of such materials have an important influences on the emission characteristics of volatile organic compounds (VOCs). The pore structure of porous building materials has a significant impact on the diffusion coefficient. However, the complex structural characteristics bring great difficulties to the model development. The existing prediction models of the diffusion coefficient are flawed and need to be improved. Using scanning electron microscope (SEM) observations and mercury intrusion porosimetry (MIP) tests of typical porous building materials, this study developed a new diffusivity model: the multistage series-connection fractal capillary-bundle (MSFC) model. The model considers the variable-diameter capillaries formed by macropores connected in series as the main mass transfer paths, and the diameter distribution of the capillary bundles obeys a fractal power law in the cross section. In addition, the tortuosity of the macrocapillary segments with different diameters is obtained by the fractal theory. Mesopores serve as the connections between the macrocapillary segments rather than as the main mass transfer paths. The theoretical results obtained using the MSFC model yielded a highly accurate prediction of the diffusion coefficients and were in a good agreement with the VOC concentration measurements in the environmental test chamber. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Fabrication of Porous Materials from Natural/Synthetic Biopolymers and Their Composites

    Directory of Open Access Journals (Sweden)

    Udeni Gunathilake T.M. Sampath

    2016-12-01

    Full Text Available Biopolymers and their applications have been widely studied in recent years. Replacing the oil based polymer materials with biopolymers in a sustainable manner might give not only a competitive advantage but, in addition, they possess unique properties which cannot be emulated by conventional polymers. This review covers the fabrication of porous materials from natural biopolymers (cellulose, chitosan, collagen, synthetic biopolymers (poly(lactic acid, poly(lactic-co-glycolic acid and their composite materials. Properties of biopolymers strongly depend on the polymer structure and are of great importance when fabricating the polymer into intended applications. Biopolymers find a large spectrum of application in the medical field. Other fields such as packaging, technical, environmental, agricultural and food are also gaining importance. The introduction of porosity into a biomaterial broadens the scope of applications. There are many techniques used to fabricate porous polymers. Fabrication methods, including the basic and conventional techniques to the more recent ones, are reviewed. Advantages and limitations of each method are discussed in detail. Special emphasis is placed on the pore characteristics of biomaterials used for various applications. This review can aid in furthering our understanding of the fabrication methods and about controlling the porosity and microarchitecture of porous biopolymer materials.

  15. Fabrication of Porous Materials from Natural/Synthetic Biopolymers and Their Composites.

    Science.gov (United States)

    Sampath, Udeni Gunathilake T M; Ching, Yern Chee; Chuah, Cheng Hock; Sabariah, Johari J; Lin, Pai-Chen

    2016-12-07

    Biopolymers and their applications have been widely studied in recent years. Replacing the oil based polymer materials with biopolymers in a sustainable manner might give not only a competitive advantage but, in addition, they possess unique properties which cannot be emulated by conventional polymers. This review covers the fabrication of porous materials from natural biopolymers (cellulose, chitosan, collagen), synthetic biopolymers (poly(lactic acid), poly(lactic- co -glycolic acid)) and their composite materials. Properties of biopolymers strongly depend on the polymer structure and are of great importance when fabricating the polymer into intended applications. Biopolymers find a large spectrum of application in the medical field. Other fields such as packaging, technical, environmental, agricultural and food are also gaining importance. The introduction of porosity into a biomaterial broadens the scope of applications. There are many techniques used to fabricate porous polymers. Fabrication methods, including the basic and conventional techniques to the more recent ones, are reviewed. Advantages and limitations of each method are discussed in detail. Special emphasis is placed on the pore characteristics of biomaterials used for various applications. This review can aid in furthering our understanding of the fabrication methods and about controlling the porosity and microarchitecture of porous biopolymer materials.

  16. Use of natural aluminosilicates and porous ceramic materials for the inclusion of radioactive wastes

    International Nuclear Information System (INIS)

    Lazarev, L.N.; Shashukov, E.A.; Kuznetsov, Yu.V.; Lyubtsev, R.I.

    1979-01-01

    Data on using the porous inorganic materials, such as diatomite and shamote, for the incorporation of radioactive wastes are presented. In laboratory-scale experiments on simulated liquid wastes it has been shown that the operations of solution absorption by porous materials, drying and calcination of salts in pores, and the subsequent conversion into glassy phosphate-silicate products seem to be promising from a technological point of view. This product is characterized by a sodium leaching rate of the order of 10 -5 g/cm 2 . d and good resistance to crystallization. The content of various oxides in the wastes can attain 15 to 20 wt %. The data on the dependence of plasticity and open porosity of the clay-like products on Na 2 O, SrO, ZrO 2 , and MnO 2 content are also given. 3 figures, 3 tables

  17. Pore structure, mechanical properties and polymer characteristics of porous materials impregnated with methylmethacrylate

    International Nuclear Information System (INIS)

    Hastrup, K.

    1976-05-01

    The pore structure of porous materials plays a decisive role with regard to many properties of the materials. One therefore expects property improvement due to impregnation to be mostly brought about as a result of pore structure modification. This supposition formed the basis for the project here presented, which had the main aim of investigating polymer impregnation in relation to pore structure. Objectives were: 1) to examine the pore structure of hardened cement paste, beech wood and porous glass before and after gas-phase impregnation with methyl-methacrylate monomer and in situ polymerization, 2) to investigate the influence of the pore structure on the molecular weight of the polymer, 3) to investigate the influence of the degree of pore filling on the elastic modulus, damping coefficient and bending strength. (author)

  18. DIFFERENTIAL ANALYSIS OF VOLUMETRIC STRAINS IN POROUS MATERIALS IN TERMS OF WATER FREEZING

    Directory of Open Access Journals (Sweden)

    Rusin Z.

    2013-06-01

    Full Text Available The paper presents the differential analysis of volumetric strain (DAVS. The method allows measurements of volumetric deformations of capillary-porous materials caused by water-ice phase change. The VSE indicator (volumetric strain effect, which under certain conditions can be interpreted as the minimum degree of phase change of water contained in the material pores, is proposed. The test results (DAVS for three materials with diversified microstructure: clinker brick, calcium-silicate brick and Portland cement mortar were compared with the test results for pore characteristics obtained with the mercury intrusion porosimetry.

  19. Creep rupture behavior of Stirling engine materials

    Science.gov (United States)

    Titran, R. H.; Scheuerman, C. M.; Stephens, J. R.

    1985-01-01

    The automotive Stirling engine, being investigated jointly by the Department of Energy and NASA Lewis as an alternate to the internal combustion engine, uses high-pressure hydrogen as the working fluid. The long-term effects of hydrogen on the high temperature strength properties of materials is relatively unknown. This is especially true for the newly developed low-cost iron base alloy NASAUT 4G-A1. This iron-base alloy when tested in air has creep-rupture strengths in the directionally solidified condition comparable to the cobalt base alloy HS-31. The equiaxed (investment cast) NASAUT 4G-A1 has superior creep-rupture to the equiaxed iron-base alloy XF-818 both in air and 15 MPa hydrogen.

  20. A review of low density porous materials used in laser plasma experiments

    Science.gov (United States)

    Nagai, Keiji; Musgrave, Christopher S. A.; Nazarov, Wigen

    2018-03-01

    This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists' point of view to aid physicists and the new comers to this field.

  1. Biomimetic material strategies for cardiac tissue engineering

    International Nuclear Information System (INIS)

    Prabhakaran, Molamma P.; Venugopal, J.; Kai, Dan; Ramakrishna, Seeram

    2011-01-01

    Cardiovascular disease precedes many serious complications including myocardial infarction (MI) and it remains a major problem for the global community. Adult mammalian heart has limited ability to regenerate and compensate for the loss of cardiomyocytes. Restoration of cardiac function by replacement of diseased myocardium with functional cardiomyocytes is an intriguing strategy because it offers a potential cure for MI. Biomaterials are fabricated in nanometer scale dimensions by combining the chemical, biological, mechanical and electrical aspects of material for potential tissue engineering (TE) applications. Synthetic polymers offer advantageous in their ability to tailor the mechanical properties, and natural polymers offer cell recognition sites necessary for cell, adhesion and proliferation. Cardiac tissue engineering (TE) aim for the development of a bioengineered construct that can provide physical support to the damaged cardiac tissue by replacing certain functions of the damaged extracellular matrix and prevent adverse cardiac remodeling and dysfunction after MI. Electrospun nanofibers are applied as heart muscle patches, while hydrogels serve as a platform for controlled delivery of growth factors, prevent mechanical complications and assist in cell recruitment. This article reviews the applications of different natural and synthetic polymeric materials utilized as cardiac patches, injectables or 3D constructs for cardiac TE. Smart organization of nanoscale assemblies with synergistic approaches of utilizing nanofibers and hydrogels could further advance the field of cardiac tissue engineering. Rapid innovations in biomedical engineering and cell biology will bring about new insights in the development of optimal scaffolds and methods to create tissue constructs with relevant contractile properties and electrical integration to replace or substitute the diseased myocardium.

  2. Biomimetic material strategies for cardiac tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Molamma P., E-mail: nnimpp@nus.edu.sg [Health Care and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Venugopal, J. [Health Care and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Kai, Dan [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore (Singapore); Ramakrishna, Seeram [Health Care and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore)

    2011-04-08

    Cardiovascular disease precedes many serious complications including myocardial infarction (MI) and it remains a major problem for the global community. Adult mammalian heart has limited ability to regenerate and compensate for the loss of cardiomyocytes. Restoration of cardiac function by replacement of diseased myocardium with functional cardiomyocytes is an intriguing strategy because it offers a potential cure for MI. Biomaterials are fabricated in nanometer scale dimensions by combining the chemical, biological, mechanical and electrical aspects of material for potential tissue engineering (TE) applications. Synthetic polymers offer advantageous in their ability to tailor the mechanical properties, and natural polymers offer cell recognition sites necessary for cell, adhesion and proliferation. Cardiac tissue engineering (TE) aim for the development of a bioengineered construct that can provide physical support to the damaged cardiac tissue by replacing certain functions of the damaged extracellular matrix and prevent adverse cardiac remodeling and dysfunction after MI. Electrospun nanofibers are applied as heart muscle patches, while hydrogels serve as a platform for controlled delivery of growth factors, prevent mechanical complications and assist in cell recruitment. This article reviews the applications of different natural and synthetic polymeric materials utilized as cardiac patches, injectables or 3D constructs for cardiac TE. Smart organization of nanoscale assemblies with synergistic approaches of utilizing nanofibers and hydrogels could further advance the field of cardiac tissue engineering. Rapid innovations in biomedical engineering and cell biology will bring about new insights in the development of optimal scaffolds and methods to create tissue constructs with relevant contractile properties and electrical integration to replace or substitute the diseased myocardium.

  3. Sound transmission through panels and shells filled with porous material in the presence of external flow

    OpenAIRE

    Zhou, Jie

    2014-01-01

    With increasingly tighter regulations on noise exposure during flight, aircraft designers have been compelled to innovate structures that minimise noise transmission into the cabin space. Porous material is widely used as a passive noise control medium because of their light weight, low cost, and broad band sound abatement effectiveness. The present work, inspired by the need to be able to predict noise transmission characteristics for commonly used constructions, incorporates the effect of f...

  4. Two-dimensional hierarchical porous carbon composites derived from corn stalks for electrode materials with high performance

    International Nuclear Information System (INIS)

    Xu, Haitao; Zhang, Huijuan; Ouyang, Ya; Liu, Li; Wang, Yu

    2016-01-01

    Highlights: • Novel 2D porous carbon sheets from cornstalks are obtained for the first time. • The hierarchical porous carbon nansheets are gained by chemical activation. • The porous structure facilitates ion transfer and Li-ion absorption. • The strategy are applied to both cathode and anode electrode materials. • The porous nanocomposites exhibit excellent electrochemical performance. - Abstract: Herein, we propose a novel and green strategy to convert crop stalks waste into hierarchical porous carbon composites for electrode materials of lithium-ion batteries. In the method, the sustainable crop stalks, an abundant agricultural byproduct, is recycled and treated by a simple and clean chemical activation process. Afterwards, the obtained porous template is adopted for large-scale production of high-performance anode and cathode materials for lithium-ion batteries. Due to the large surface area, hierarchical porous structures and subsize of the functional particles, the electrode materials manifest excellent electrochemical performance. In particular, the prepared TiO 2 /C composite presents a reversible specific capacity of 203 mAh g −1 after 200 cycles. Our results demonstrate that the sheetlike composites show remarkable cycling stability, high specific capacity and excellent rate ability, and thus hold promise for commercializing the high-performance electrode materials as the advanced lithium-ion batteries.

  5. Aerogels of 1D Coordination Polymers: From a Non-Porous Metal-Organic Crystal Structure to a Highly Porous Material

    Directory of Open Access Journals (Sweden)

    Adrián Angulo-Ibáñez

    2016-01-01

    Full Text Available The processing of an originally non-porous 1D coordination polymer as monolithic gel, xerogel and aerogel is reported as an alternative method to obtain novel metal-organic porous materials, conceptually different to conventional crystalline porous coordination polymer (PCPs or metal-organic frameworks (MOFs. Although the work herein reported is focused upon a particular kind of coordination polymer ([M(μ-ox(4-apy2]n, M: Co(II, Ni(II, the results are of interest in the field of porous materials and of MOFs, as the employed synthetic approach implies that any coordination polymer could be processable as a mesoporous material. The polymerization conditions were fixed to obtain stiff gels at the synthesis stage. Gels were dried at ambient pressure and at supercritical conditions to render well shaped monolithic xerogels and aerogels, respectively. The monolithic shape of the synthesis product is another remarkable result, as it does not require a post-processing or the use of additives or binders. The aerogels of the 1D coordination polymers are featured by exhibiting high pore volumes and diameters ranging in the mesoporous/macroporous regions which endow to these materials the ability to deal with large-sized molecules. The aerogel monoliths present markedly low densities (0.082–0.311 g·cm−3, an aspect of interest for applications that persecute light materials.

  6. Porous Polyethylene Coated with Functionalized Hydroxyapatite Particles as a Bone Reconstruction Material

    Directory of Open Access Journals (Sweden)

    H. Fouad

    2018-03-01

    Full Text Available In this study, porous polyethylene scaffolds were examined as bone substitutes in vitro and in vivo in critical-sized calvarial bone defects in transgenic Sprague-Dawley rats. A microscopic examination revealed that the pores appeared to be interconnected across the material, making them suitable for cell growth. The creep recovery behavior of porous polyethylene at different loads indicated that the creep strain had two main portions. In both portions, strain increased with increased applied load and temperature. In terms of the thermographic behavior of the material, remarkable changes in melting temperature and heat fusion were revealed with increased the heating rates. The tensile strength results showed that the material was sensitive to the strain rate and that there was adequate mechanical strength to support cell growth. The in vitro cell culture results showed that human bone marrow mesenchymal stem cells attached to the porous polyethylene scaffold. Calcium sulfate–hydroxyapatite (CS–HA coating of the scaffold not only improved attachment but also increased the proliferation of human bone marrow mesenchymal stem cells. In vivo, histological analysis showed that the study groups had active bone remodeling at the border of the defect. Bone regeneration at the border was also evident, which confirmed that the polyethylene acted as an osteoconductive bone graft. Furthermore, bone formation inside the pores of the coated polyethylene was also noted, which would enhance the process of osteointegration.

  7. Damage and failure modeling of lotus-type porous material subjected to low-cycle fatigue

    Directory of Open Access Journals (Sweden)

    J. Kramberger

    2016-01-01

    Full Text Available The investigation of low-cycle fatigue behaviour of lotus-type porous material is presented in this paper. Porous materials exhibit some unique features which are useful for a number of various applications. This paper evaluates a numerical approach for determining of damage initiation and evolution of lotus-type porous material with computational simulations, where the considered computational models have different pore topology patterns. The low-cycle fatigue analysis was performed by using a damage evolution law. The damage state was calculated and updated based on the inelastic hysteresis energy for stabilized cycle. Degradation of the elastic stifness was modeled using scalar damage variable. In order to examine crack propagation path finite elements with severe damage were deleted and removed from the mesh during simulation. The direct cyclic analysis capability in Abaqus/Standard was used for low-cycle fatigue analysis to obtain the stabilized response of a model subjected to the periodic loading. The computational results show a qualitative understanding of pores topology influence on low-cycle fatigue under transversal loading conditions in relation to pore orientation.

  8. Accurate van der Waals force field for gas adsorption in porous materials.

    Science.gov (United States)

    Sun, Lei; Yang, Li; Zhang, Ya-Dong; Shi, Qi; Lu, Rui-Feng; Deng, Wei-Qiao

    2017-09-05

    An accurate van der Waals force field (VDW FF) was derived from highly precise quantum mechanical (QM) calculations. Small molecular clusters were used to explore van der Waals interactions between gas molecules and porous materials. The parameters of the accurate van der Waals force field were determined by QM calculations. To validate the force field, the prediction results from the VDW FF were compared with standard FFs, such as UFF, Dreiding, Pcff, and Compass. The results from the VDW FF were in excellent agreement with the experimental measurements. This force field can be applied to the prediction of the gas density (H 2 , CO 2 , C 2 H 4 , CH 4 , N 2 , O 2 ) and adsorption performance inside porous materials, such as covalent organic frameworks (COFs), zeolites and metal organic frameworks (MOFs), consisting of H, B, N, C, O, S, Si, Al, Zn, Mg, Ni, and Co. This work provides a solid basis for studying gas adsorption in porous materials. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. Multi-scale porous materials: from adsorption and poro-mechanics properties to energy and environmental applications

    International Nuclear Information System (INIS)

    Pellenq, Roland J.M.

    2012-01-01

    Document available in extended abstract form only. 'Multi-scale Porous Materials under the Nano-scope'. Setting up the stage, one can list important engineering problems such as hydrogen storage for transportation applications, electric energy storage in batteries, CO 2 sequestration in used coal mines, earthquake mechanisms, durability of nuclear fuels, stability of soils and sediment and cements and concrete cohesive properties in the context of sustainability. With the exception of health, these are basically the challenging engineering problems of the coming century that address energy, environment and natural hazards. Behind all those problems are complex multi-scale porous materials that have a confined fluid in their pore void: water in the case of clays and cement, an electrolyte in the case of batteries and super-capacitors, weakly interacting molecular fluids in the case of hydrogen storage devices, gas-shale and nuclear fuel bars. So what do we mean by 'under the nano-scope'? The nano-scope does not exist as a single experimental technique able of assessing the 3D texture of complex multi-scale material. Obviously techniques such as TEM are part of the answer but are not the 'nano-scope' in itself. In our idea, the 'nano-scope' is more than a technique producing images. It is rather a concept that links a suite of modeling techniques coupled with experiments (electron and X-rays microscopies, tomography, nano-indentation, nano-scratching...). Fig 1 gives an outline of this strategy for cement. It allows accessing material texture, their chemistry, their mechanical behavior, their adsorption/condensation behavior at all scales starting from the nano-scale upwards. The toolbox of the simulation aspect of the 'nano-scope' is akin to a statistical physics description of material texture and properties including the thermodynamics and dynamics of the fluids confined to their pore voids as a means to linking atomic scale properties to macroscopic properties

  10. Processing and characterization of chitosan/PVA and methylcellulose porous scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Kanimozhi, K.; Khaleel Basha, S.; Sugantha Kumari, V.

    2016-01-01

    Biomimetic porous scaffold chitosan/poly(vinyl alcohol) CS/PVA containing various amounts of methylcellulose (MC) (25%, 50% and 75%) incorporated in CS/PVA blend was successfully produced by a freeze drying method in the present study. The composite porous scaffold membranes were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), swelling degree, porosity, degradation of films in Hank's solution and the mechanical properties. Besides these characterizations, the antibacterial activity of the prepared scaffolds was tested, toward the bacterial species Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). FTIR, XRD and DSC demonstrated that there was strong intermolecular hydrogen bonding between the molecules of CS/PVA and MC. The crystalline microstructure of the scaffold membranes was not well developed. SEM images showed that the morphology and diameter of the scaffolds were mainly affected by the weight ratio of MC. By increasing the MC content in the hybrid scaffolds, their swelling capacity and porosity increased. The mechanical properties of these scaffolds in dry and swollen state were greatly improved with high swelling ratio. The elasticity of films was also significantly improved by the incorporation of MC, and the scaffolds could also bear a relative high tensile strength. These findings suggested that the developed scaffold possess the prerequisites and can be used as a scaffold for tissue engineering. - Highlights: • The porous scaffolds of CS/PVA containing different MC contents were fabricated. • Addition of MC improved the compatibility between CS and PVA. • The mechanical properties of these scaffolds were greatly improved with high swelling ratio. • Biocompatibility test showed that the different MC content scaffolds had no cytotoxicity.

  11. Processing and characterization of chitosan/PVA and methylcellulose porous scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Kanimozhi, K. [Department of Chemistry, Auxilium College, Vellore 632 006 (India); Khaleel Basha, S. [Department of Biochemistry, C. Abdul Hakeem College, Melvisharam 632 509 (India); Sugantha Kumari, V., E-mail: sheenasahana04@gmail.com [Department of Chemistry, Auxilium College, Vellore 632 006 (India)

    2016-04-01

    Biomimetic porous scaffold chitosan/poly(vinyl alcohol) CS/PVA containing various amounts of methylcellulose (MC) (25%, 50% and 75%) incorporated in CS/PVA blend was successfully produced by a freeze drying method in the present study. The composite porous scaffold membranes were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), swelling degree, porosity, degradation of films in Hank's solution and the mechanical properties. Besides these characterizations, the antibacterial activity of the prepared scaffolds was tested, toward the bacterial species Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). FTIR, XRD and DSC demonstrated that there was strong intermolecular hydrogen bonding between the molecules of CS/PVA and MC. The crystalline microstructure of the scaffold membranes was not well developed. SEM images showed that the morphology and diameter of the scaffolds were mainly affected by the weight ratio of MC. By increasing the MC content in the hybrid scaffolds, their swelling capacity and porosity increased. The mechanical properties of these scaffolds in dry and swollen state were greatly improved with high swelling ratio. The elasticity of films was also significantly improved by the incorporation of MC, and the scaffolds could also bear a relative high tensile strength. These findings suggested that the developed scaffold possess the prerequisites and can be used as a scaffold for tissue engineering. - Highlights: • The porous scaffolds of CS/PVA containing different MC contents were fabricated. • Addition of MC improved the compatibility between CS and PVA. • The mechanical properties of these scaffolds were greatly improved with high swelling ratio. • Biocompatibility test showed that the different MC content scaffolds had no cytotoxicity.

  12. Interaction of a high-power laser pulse with supercritical-density porous materials

    International Nuclear Information System (INIS)

    Gus'kov, Sergei Yu; Rozanov, Vladislav B; Caruso, A; Strangio, C

    2000-01-01

    The properties of a nonequilibrium plasma produced by high-power laser pulses with intensities I L ∼ 10 14 -10 15 W cm -2 irradiating plane targets made of a porous material are investigated. The mean density of matter in targets was substantially higher than the critical plasma density corresponding to a plasma resonance. The density of porous material was ρ a ∼ 1 - 20 mg cm -3 , whereas the critical density at the wavelength of incident radiation was ρ cr ∼ 3 mg cm -3 . An anomalously high absorption (no less than 80%) of laser radiation inside a target was observed. Within the first 3 - 4 ns of interaction, the plasma flow through the irradiated target surface in the direction opposite of the direction of the laser beam was noticeably suppressed. Only about 5% of absorbed laser energy was transformed into the energy of particles in this flow during the laser pulse. Absorbed energy was stored as the internal plasma energy at this stage (the greenhouse effect). Then, this energy was transformed, similar to a strong explosion, into the energy of a powerful hydrodynamic flow of matter surrounding the absorption region. The specific features of the formation and evolution of a nonequilibrium laser-produced plasma in porous media are theoretically analysed. This study allows the results of experiments to be explained. In particular, we investigated absorption of laser radiation in the bulk of a target, volume evaporation of porous material, the expansion of a laser-produced plasma inside the pores, stochastic collisions of plasma flows, and hydrothermal energy dissipation. These processes give rise to long-lived oscillations of plasma density and lead to the formation of an internal region where laser radiation is absorbed. (invited paper)

  13. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  14. A statistical method for predicting sound absorbing property of porous metal materials by using quartet structure generation set

    International Nuclear Information System (INIS)

    Guan, Dong; Wu, Jiu Hui; Jing, Li

    2015-01-01

    Highlights: • A random internal morphology and structure generation-growth method, termed as the quartet structure generation set (QSGS), has been utilized based on the stochastic cluster growth theory for numerical generating the various microstructures of porous metal materials. • Effects of different parameters such as thickness and porosity on sound absorption performance of the generated structures are studied by the present method, and the obtained results are validated by an empirical model as well. • This method could be utilized to guide the design and fabrication of the sound-absorption porous metal materials. - Abstract: In this paper, a statistical method for predicting sound absorption properties of porous metal materials is presented. To reflect the stochastic distribution characteristics of the porous metal materials, a random internal morphology and structure generation-growth method, termed as the quartet structure generation set (QSGS), has been utilized based on the stochastic cluster growth theory for numerical generating the various microstructures of porous metal materials. Then by using the transfer-function approach along with the QSGS tool, we investigate the sound absorbing performance of porous metal materials with complex stochastic geometries. The statistical method has been validated by the good agreement among the numerical results for metal rubber from this method and a previous empirical model and the corresponding experimental data. Furthermore, the effects of different parameters such as thickness and porosity on sound absorption performance of the generated structures are studied by the present method, and the obtained results are validated by an empirical model as well. Therefore, the present method is a reliable and robust method for predicting the sound absorption performance of porous metal materials, and could be utilized to guide the design and fabrication of the sound-absorption porous metal materials

  15. Fabrication and in vitro degradation of porous fumarate-based polymer/alumoxane nanocomposite scaffolds for bone tissue engineering.

    NARCIS (Netherlands)

    Mistry, A.S.; Cheng, S.H.; Yeh, T.; Christenson, E.; Jansen, J.A.; Mikos, A.G.

    2009-01-01

    In this work, the fabrication and in vitro degradation of porous fumarate-based/alumoxane nanocomposites were evaluated for their potential as bone tissue engineering scaffolds. The biodegradable polymer poly (propylene fumarate)/propylene fumarate-diacrylate (PPF/PF-DA), a macrocomposite composed

  16. Porous PEOT/PBT scaffolds for bone tissue engineering: preparation, characterization, and in vitro bone marrow cell culturing

    NARCIS (Netherlands)

    Claase, M.B.; Grijpma, Dirk W.; Mendes, S.C.; Mendes, Sandra C.; de Bruijn, Joost Dick; Feijen, Jan

    2003-01-01

    The preparation, characterization, and in vitro bone marrow cell culturing on porous PEOT/PBT copolymer scaffolds are described. These scaffolds are meant for use in bone tissue engineering. Previous research has shown that PEOT/PBT copolymers showed in vivo degradation, calcification, and bone

  17. Advances in Integrated Computational Materials Engineering "ICME"

    Science.gov (United States)

    Hirsch, Jürgen

    The methods of Integrated Computational Materials Engineering that were developed and successfully applied for Aluminium have been constantly improved. The main aspects and recent advances of integrated material and process modeling are simulations of material properties like strength and forming properties and for the specific microstructure evolution during processing (rolling, extrusion, annealing) under the influence of material constitution and process variations through the production process down to the final application. Examples are discussed for the through-process simulation of microstructures and related properties of Aluminium sheet, including DC ingot casting, pre-heating and homogenization, hot and cold rolling, final annealing. New results are included of simulation solution annealing and age hardening of 6xxx alloys for automotive applications. Physically based quantitative descriptions and computer assisted evaluation methods are new ICME methods of integrating new simulation tools also for customer applications, like heat affected zones in welding of age hardening alloys. The aspects of estimating the effect of specific elements due to growing recycling volumes requested also for high end Aluminium products are also discussed, being of special interest in the Aluminium producing industries.

  18. Small angle scattering methods to study porous materials under high uniaxial strain

    Energy Technology Data Exchange (ETDEWEB)

    Le Floch, Sylvie, E-mail: sylvie.le-floch@univ-lyon1.fr; Balima, Félix; Pischedda, Vittoria; Legrand, Franck; San-Miguel, Alfonso [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France)

    2015-02-15

    We developed a high pressure cell for the in situ study of the porosity of solids under high uniaxial strain using neutron small angle scattering. The cell comprises a hydraulically actioned piston and a main body equipped with two single-crystal sapphire windows allowing for the neutron scattering of the sample. The sample cavity is designed to allow for a large volume variation as expected when compressing highly porous materials. We also implemented a loading protocol to adapt an existing diamond anvil cell for the study of porous materials by X-ray small angle scattering under high pressure. The two techniques are complementary as the radiation beam and the applied pressure are in one case perpendicular to each other (neutron cell) and in the other case parallel (X-ray cell). We will illustrate the use of these two techniques in the study of lamellar porous systems up to a maximum pressure of 0.1 GPa and 0.3 GPa for the neutron and X-ray cells, respectively. These devices allow obtaining information on the evolution of porosity with pressure in the pore dimension subdomain defined by the wave-numbers explored in the scattering process. The evolution with the applied load of such parameters as the fractal dimension of the pore-matrix interface or the apparent specific surface in expanded graphite and in expanded vermiculite is used to illustrate the use of the high pressure cells.

  19. A porous carbon material from pyrolysis of fructus cannabis’s shells for supercapacitor electrode application

    Science.gov (United States)

    Li, Kai; Zhang, Wei-Bin; Zhao, Zhi-Yun; Zhao, Yue; Chen, Xi-Wen; Kong, Ling-Bin

    2018-02-01

    The porous carbon material is obtained via pyrolysis and activation of fructus cannabis’s shells, an easy-to-get biomass source, and is used as an active electrode material for supercapacitors. The obtained carbon exhibit a high specific surface area of 2389 m2 g-1. And the result of x-ray photoelectron spectroscopy (XPS) shows that the obtained porous carbon possess numerous oxygen groups, which can facilitate the wettability of the electrode. The prepared porous carbon also exhibit remarkable electrochemical properties, such as high specific capacitance of 357 F g-1 at a current density of 0.5 A g-1 in 6 mol L-1 aqueous KOH electrolyte, good rate capability of 77% capacitance retention as the current density increase from 0.5 A g-1 to 10 A g-1. In addition, it also presents a superior cycling stability of 100% capacitance retention after 10 000 cycles at the current density of 1 A g-1.

  20. Hierarchical porous nickel oxide-carbon nanotubes as advanced pseudocapacitor materials for supercapacitors

    Science.gov (United States)

    Su, Aldwin D.; Zhang, Xiang; Rinaldi, Ali; Nguyen, Son T.; Liu, Huihui; Lei, Zhibin; Lu, Li; Duong, Hai M.

    2013-03-01

    Hierarchical porous carbon anode and metal oxide cathode are promising for supercapacitor with both high energy density and high power density. This Letter uses NiO and commercial carbon nanotubes (CNTs) as electrode materials for electrochemical capacitors with high energy storage capacities. Experimental results show that the specific capacitance of the electrode materials for 10%, 30% and 50% CNTs are 279, 242 and 112 F/g, respectively in an aqueous 1 M KOH electrolyte at a charge rate of 0.56 A/g. The maximum specific capacitance is 328 F/g at a charge rate of 0.33 A/g.

  1. Deep convolutional neural networks for estimating porous material parameters with ultrasound tomography

    Science.gov (United States)

    Lähivaara, Timo; Kärkkäinen, Leo; Huttunen, Janne M. J.; Hesthaven, Jan S.

    2018-02-01

    We study the feasibility of data based machine learning applied to ultrasound tomography to estimate water-saturated porous material parameters. In this work, the data to train the neural networks is simulated by solving wave propagation in coupled poroviscoelastic-viscoelastic-acoustic media. As the forward model, we consider a high-order discontinuous Galerkin method while deep convolutional neural networks are used to solve the parameter estimation problem. In the numerical experiment, we estimate the material porosity and tortuosity while the remaining parameters which are of less interest are successfully marginalized in the neural networks-based inversion. Computational examples confirms the feasibility and accuracy of this approach.

  2. Scaling impact and shock-compression response for porous materials: Application to planetary formation

    Science.gov (United States)

    Jeanloz, R.

    2016-12-01

    A thermodynamic model based on the Mie-Grüneisen equation of state does a good job of describing the response of porous materials to impact, so can provide insights into the accretion and cohesion of planetesimals too small to be significantly held together by gravity (e.g., tens of km or less in average diameter). The model identifies an offset in Hugoniot pressure (ΔPH) due to porosity that is found to be in agreement with experimental shock-compression measurements for samples having a wide range of initial porosities. Assuming the Grüneisen parameter (γ) is proportional to volume (γ/V = constant), the relative offset in Hugoniot pressure as a function of initial porosity (φ = 1 - V0/V0por) and compression (η = 1 - V/V0) is ΔPH/PH = γ0 φ/[2(1 - φ) - γ0 (φ + η(1 - φ))] where subscripts 0 and por represent zero-pressure (non-porous) conditions and a porous sample, respectively. This additional thermal pressure at a given volume is due to the extra internal energy and corresponding temperature increase associated with collapsing pores (Fig. 1: near-identical curves for φ = 0.001 and 0.01). This result can be interpreted as indicating that upon collapse individual pores create hot spots with temperatures of order 103-104K above the background, suggesting that impact into an initially porous target can result in cohesion due to partial melting and vaporization. Moreover, the waste heat associated with pore closure far exceeds the dissipation in shock loading of non-porous material, reflecting the ability of a porous target to absorb and dissipate impact energy. The Mie-Grüneisen model along with analysis of waste heat thus provides a scaling for planetesimal impact that might explain how rock and regolith accrete into a gravitationally bound planet. Fig. 1. Porosity-induced anomaly in Hugoniot temperature per unit of porosity, shown as a function of compression for samples with initial porosity φ = 0.001 (green), 0.01 (blue) and 0.1 (gold) assuming

  3. [Fabrication of porous poly lactic acid-bone matrix gelatin composite bioactive material and its osteoinductive activity].

    Science.gov (United States)

    Zhang, Yumin; Li, Baoxing; Li, Ji

    2007-02-01

    To fabricate a novel porous bioactive composite biomaterial consisting of poly lactic acid (PLA)-bone matrix gelatin (BMG) by using the supercritical carbon dioxide fluid technique (SC-CO2) and to evaluate its osteoinductive activity. The cortical bones selected from healthy adult donors were processed into BMG by the defatting, demineralizing, and deproteinizing processes. PLA and BMG were mixed at a volume radio of 3 : 1; then, the PLA-BMG mixed material and the pure PLA material were respectively placed in the supercritical carbon dioxide reaction kettles, and were respectively added by the NaCl particles 100-200 microm in diameter for the porosity of the materials so that the porous PLA-BMG composite material and the porous PLA composite material could be formed. The mouse osteoblast-like MC3T3-E1 cells were cultured in the dulbecco's modified eagle medium (DMEM) supplemented with 10% fetal bovine serum. Then, 20 microl of the MC3T3-E1 cell suspensions containing 2 X 10(6) cells /ml were delivered into the culturing plate (24 wells/plate) made of the different materials, which were co-cultured for 2 weeks. In the PLA-BMG group, 100 microg of the crushed PLA-BMG material was contained in each well; in the PLA group, 100 microg of the crushed PLA material was contained in each well; and in the DMEM group, only DMEM was contained, which served as the control group. There were 6 wells in each group. The quantitative analysis on the calcification area was performed by the staining of the alizarin red S. The co-cultured cells were harvested and lysated in 1 ml of 0. 2% Nonidet P-40 by the ultrasonic lysating technique. Then, the ALP activity and the Ca content were measured according to the illuminations of the reagent kits. The porous PLA-BMG composite material showed a good homological porosity with a pore diameter of 50-150 microm and a good connectivity between the pores. The ALP activity, the Ca content, and the calcification area were significantly greater in

  4. In silico design of porous polymer networks: high-throughput screening for methane storage materials.

    Science.gov (United States)

    Martin, Richard L; Simon, Cory M; Smit, Berend; Haranczyk, Maciej

    2014-04-02

    Porous polymer networks (PPNs) are a class of advanced porous materials that combine the advantages of cheap and stable polymers with the high surface areas and tunable chemistry of metal-organic frameworks. They are of particular interest for gas separation or storage applications, for instance, as methane adsorbents for a vehicular natural gas tank or other portable applications. PPNs are self-assembled from distinct building units; here, we utilize commercially available chemical fragments and two experimentally known synthetic routes to design in silico a large database of synthetically realistic PPN materials. All structures from our database of 18,000 materials have been relaxed with semiempirical electronic structure methods and characterized with Grand-canonical Monte Carlo simulations for methane uptake and deliverable (working) capacity. A number of novel structure-property relationships that govern methane storage performance were identified. The relationships are translated into experimental guidelines to realize the ideal PPN structure. We found that cooperative methane-methane attractions were present in all of the best-performing materials, highlighting the importance of guest interaction in the design of optimal materials for methane storage.

  5. IL 14: Radiolysis of water confined in nano-porous materials

    International Nuclear Information System (INIS)

    Renault, J.P.; Pommeret, S.; Musat, R.; Le Caer, S.; Alam, M.; Mialocq, J.C.

    2010-01-01

    Radiolysis of water in nano-porous media has raised a lot of interest and involved research in the recent years, with respect to concerns arising from the storage of nuclear waste. In the civil nuclear industry, storing for a long time nuclear wastes requires safety evaluations in order to test the durability of the materials involved. Among these materials, concrete and clays are a complex heterogeneous material that traps important quantities of interstitial water. Irradiation that arises from the nuclear wastes stored in these materials may lead to the radiolysis of the interstitial water, and the formation of radiolytic products, such as H 2 , O 2 or H 2 O 2 that may cause the breaking or the corrosion of the confining matrix. This communication will describe the possible impacts of confinement on the radiolysis of water. We will especially discuss the current knowledge about the evolution of radiolytic yields of primary species (hydroxyl radical, dihydrogen, aqueous electron) as a function of the degree of confinement and of the nature of the confining material. SEM picture of a nano-porous gold sample used to study the radiolysis of confined water The yield enhancement observed in many cases revealed original energy and charge transfer phenomena that we tried to decipher. (authors)

  6. Synthesis of hierarchical porous materials with ZSM-5 structures via template-free sol–gel method

    Directory of Open Access Journals (Sweden)

    Wei Han et al

    2007-01-01

    Full Text Available Interests are focused on preparation of hierarchical porous materials with zeolite structures by using soft or rigid templates in order to solve diffusion and mass transfer limitations resulting from the small pore sizes of zeolites. Here we develop a convenient template-free sol–gel method to synthesize hierarchical porous materials with ZSM-5 structures. This method involves hydrothermal recrystallization of the xerogel converted from uniform ZSM-5 sol by a vacuum drying process. By utilizing this method we can manipulate the size of zeolite nanocrystals as building units of porous structures based on controlling temperature of recrystallization, consequently obtain hierarchical porous materials with different intercrystalline pore sizes and ZSM-5 structures.

  7. Isolated and modulated effects of topology and material type on the mechanical properties of additively manufactured porous biomaterials.

    Science.gov (United States)

    Hedayati, R; Ahmadi, S M; Lietaert, K; Pouran, B; Li, Y; Weinans, H; Rans, C D; Zadpoor, A A

    2018-03-01

    In this study, we tried to quantify the isolated and modulated effects of topological design and material type on the mechanical properties of AM porous biomaterials. Towards this aim, we assembled a large dataset comprising the mechanical properties of AM porous biomaterials with different topological designs (i.e. different unit cell types and relative densities) and material types. Porous structures were additively manufactured from Co-Cr using a selective laser melting (SLM) machine and tested under quasi-static compression. The normalized mechanical properties obtained from those structures were compared with mechanical properties available from our previous studies for porous structures made from Ti-6Al-4V and pure titanium as well as with analytical solutions. The normalized values of elastic modulus and yield stress were found to be relatively close to each other as well as in agreement with analytical solutions regardless of material type. However, the material type was found to systematically affect the mechanical properties of AM porous biomaterials in general and the post-elastic/post-yield range (plateau stress and energy absorption capacity) in particular. To put this in perspective, topological design could cause up to 10-fold difference in the mechanical properties of AM porous biomaterials while up to 2-fold difference was observed as a consequence of changing the material type. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Mechanics of materials an introduction to engineering technology

    CERN Document Server

    Ghavami, Parviz

    2015-01-01

    This book, framed in the processes of engineering analysis and design, presents concepts in mechanics of materials for students in two-year or four-year programs in engineering technology, architecture, and building construction, as well as for students in vocational schools and technical institutes. Using the principles and laws of mechanics, physics, and the fundamentals of engineering, Mechanics of Materials: An Introduction for Engineering Technology will help aspiring and practicing engineers and engineering technicians from across disciplines—mechanical, civil, chemical, and electrical—apply concepts of engineering mechanics for analysis and design of materials, structures, and machine components. The book is ideal for those seeking a rigorous, algebra/trigonometry-based text on the mechanics of materials. This book also: ·       Elucidates concepts of engineering mechanics in materials, including stress and strain, force systems on structures, moment of inertia, and shear and bending moments...

  9. Gender Equity in Materials Science and Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Angus Rockett

    2008-12-01

    At the request of the University Materials Council, a national workshop was convened to examine 'Gender Equity Issues in Materials Science and Engineering.' The workshop considered causes of the historic underrepresentation of women in materials science and engineering (MSE), with a goal of developing strategies to increase the gender diversity of the discipline in universities and national laboratories. Specific workshop objectives were to examine efforts to level the playing field, understand implicit biases, develop methods to minimize bias in all aspects of training and employment, and create the means to implement a broadly inclusive, family-friendly work environment in MSE departments. Held May 18-20, 2008, at the Conference Center at the University of Maryland, the workshop included heads and chairs of university MSE departments and representatives of the National Science Foundation (NSF), the Office of Basic Energy Sciences of the Department of Energy (DOE-BES), and the national laboratories. The following recommendations are made based on the outcomes of the discussions at the workshop. Many or all of these apply equally well to universities and national laboratories and should be considered in context of industrial environments as well. First, there should be a follow-up process by which the University Materials Council (UMC) reviews the status of women in the field of MSE on a periodic basis and determines what additional changes should be made to accelerate progress in gender equity. Second, all departments should strengthen documentation and enforcement of departmental procedures such that hiring, promotion, compensation, and tenure decisions are more transparent, that the reasons why a candidate was not selected or promoted are clear, and that faculty are less able to apply their biases to personnel decisions. Third, all departments should strengthen mentoring of junior faculty. Fourth, all departments must raise awareness of gender biases

  10. Frost induced damages within porous materials - from concrete technology to fuel cells technique

    Science.gov (United States)

    Palecki, Susanne; Gorelkov, Stanislav; Wartmann, Jens; Heinzel, Angelika

    2017-12-01

    Porous media like concrete or layers of membrane electrode assemblies (MEA) within fuel cells are affected by a cyclic frost exposure due to different damage mechanisms which could lead to essential degradation of the material. In general, frost damages can only occur in case of a specific material moisture content. In fuel cells, residual water is generally available after shut down inside the membrane i.e. the gas diffusion layer (GDL). During subsequent freezing, this could cause various damage phenomena such as frost heaves and delamination effects of the membrane electrode assembly, which depends on the location of pore water and on the pore structure itself. Porous materials possess a pore structure that could range over several orders of magnitudes with different properties and freezing behaviour of the pore water. Latter can be divided into macroscopic, structured and pre-structured water, influenced by surface interactions. Therefore below 0 °C different water modifications can coexist in a wide temperature range, so that during frost exposure a high amount of unfrozen and moveable water inside the pore system is still available. This induces transport mechanisms and shrinkage effects. The physical basics are similar for porous media. While the freezing behaviour of concrete has been studied over decades of years, in order to enhance the durability, the know-how about the influence of a frost attack on fuel cell systems is not fully understood to date. On the basis of frost damage models for concrete structures, an approach to describe the impact of cyclic freezing and thawing on membrane electrode assemblies has been developed within this research work. Major aim is beyond a better understanding of the frost induced mechanisms, the standardization of a suitable test procedure for the assessment of different MEA materials under such kind of attack. Within this contribution first results will be introduced.

  11. Stability of quasi-steady deflagrations in confined porous energetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Alexander M. Telengator; Stephen B. Margolis; Forman A. Williams

    2000-03-01

    Previous analyses have shown that unconfined deflagrations propagating through both porous and nonporous energetic materials can exhibit a thermal/diffusive instability that corresponds to the onset of various oscillatory modes of combustion. For porous materials, two-phase-flow effects, associated with the motion of the gas products relative to the condensed material, play a significant role that can shift stability boundaries with respect to those associated with the nonporous problem. In the present work, additional significant effects are shown to be associated with confinement, which produces an overpressure in the burned-gas region that leads to reversal of the gas flow and hence partial permeation of the hot gases into the unburned porous material. This results in a superadiabatic effect that increases the combustion temperature and, consequently, the burning rate. Under the assumption of gas-phase quasi-steadiness, an asymptotic model is presented that facilitates a perturbation analysis of both the basic solution, corresponding to a steadily propagating planar combustion wave, and its stability. The neutral stability boundaries collapse to the previous results in the absence of confinement, but different trends arising from the presence of the gas-permeation layer are predicted for the confined problem. Whereas two-phase-flow effects are generally destabilizing in the unconfined geometry, the effects of increasing overpressure and hence combustion temperature associated with confinement are shown to be generally stabilizing with respect to thermal/diffusive instability, analogous to the effects of decreasing heat losses on combustion temperature and stability in single-phase deflagrations.

  12. Engineering light outcoupling in 2D materials

    KAUST Repository

    Lien, Derhsien

    2015-02-11

    When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ∼11 times increase in Raman signal and a ∼30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells.

  13. Engineering light outcoupling in 2D materials

    KAUST Repository

    Lien, Derhsien; Kang, Jeongseuk; Amani, Matin; Chen, Kevin; Tosun, Mahmut; Wang, Hsinping; Roy, Tania; Eggleston, Michael S.; Wu, Ming C.; Dubey, Madan; Lee, Sichen; He, Jr-Hau; Javey, Ali

    2015-01-01

    When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ∼11 times increase in Raman signal and a ∼30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells.

  14. Contribution to research on the elastic and elastoplastic behavior of porous materials

    International Nuclear Information System (INIS)

    Frappier, J.-C.

    1979-11-01

    This three-part study concerns the mechanical behavior of porous materials. Part one, a bibliographical survey on the mechanical properties of porous materials, deals in turn with the following subjects: elastic properties, elasto-plastic boundary, plastic flow laws, fracture behavior and characterization methods. Part two is devoted to elastic behavior, giving the results of an experimental study on the elastic properties of a sintered nickel within a wide porosity range (5% to 55%) and establishing a theoretical law for the prediction of such characteristics; apart from the total porosity fraction and the elastic properties of the matrix this law can integrate parameters which represent the morphology of the material and may be determined empirically or by a modelisation, also proposed, of the structure of the material. Part three describes elastoplastic, behavior and includes experimental results obtained on sintered nickel in cases of simple mechanical stress, the demonstration - based on energy considerations of a theoretical plasticity criterion accounting for the substance, a theoretical definition of the plastic Poisson's ratio and the establishment of flow laws associated with this criterion [fr

  15. THE STRUCTURE ANALYTICAL RESEARCH OF POROUS PERMEABLE WIRE MATERIAL (in Russian

    Directory of Open Access Journals (Sweden)

    Andrzej JAKUBOWSKI

    2016-04-01

    Full Text Available The details of making technology of porous permeable material with use of wire are allowed to carry out the analytical research of structure and structural characteristics of wire winding body. Its permit for prognostication the final proper-ties of material, that is produced by the following deformation treatment (diameter reduction. Due to the regular orga-nized arrangement of wire, the coil of winding body is considered as a multispan continuous beam, but a contact of coils – as interaction of two cylinders. Possibility of exactly calculation of the contacts between coils is allowed to go over the single fragment displacements into deformation of whole winding body. During research of deformation processes in regards of winding body geometry and used wire mechanical properties, the structural characteristics of porous permea-ble wire material are expected. The optimal number of winding layers, eliminating the distortion of organized final struc-ture, is established. The material pressure–compactness relation is obtained in order to control the technological condi-tions of winding and drafting for guarantee the product required properties.

  16. Nano-Tomography of Porous Geological Materials Using Focused Ion Beam-Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-10-01

    Full Text Available Tomographic analysis using focused ion beam-scanning electron microscopy (FIB-SEM provides three-dimensional information about solid materials with a resolution of a few nanometres and thus bridges the gap between X-ray and transmission electron microscopic tomography techniques. This contribution serves as an introduction and overview of FIB-SEM tomography applied to porous materials. Using two different porous Earth materials, a diatomite specimen, and an experimentally produced amorphous silica layer on olivine, we discuss the experimental setup of FIB-SEM tomography. We then focus on image processing procedures, including image alignment, correction, and segmentation to finally result in a three-dimensional, quantified pore network representation of the two example materials. To each image processing step we consider potential issues, such as imaging the back of pore walls, and the generation of image artefacts through the application of processing algorithms. We conclude that there is no single image processing recipe; processing steps need to be decided on a case-by-case study.

  17. Bioinspired large-scale aligned porous materials assembled with dual temperature gradients.

    Science.gov (United States)

    Bai, Hao; Chen, Yuan; Delattre, Benjamin; Tomsia, Antoni P; Ritchie, Robert O

    2015-12-01

    Natural materials, such as bone, teeth, shells, and wood, exhibit outstanding properties despite being porous and made of weak constituents. Frequently, they represent a source of inspiration to design strong, tough, and lightweight materials. Although many techniques have been introduced to create such structures, a long-range order of the porosity as well as a precise control of the final architecture remain difficult to achieve. These limitations severely hinder the scale-up fabrication of layered structures aimed for larger applications. We report on a bidirectional freezing technique to successfully assemble ceramic particles into scaffolds with large-scale aligned, lamellar, porous, nacre-like structure and long-range order at the centimeter scale. This is achieved by modifying the cold finger with a polydimethylsiloxane (PDMS) wedge to control the nucleation and growth of ice crystals under dual temperature gradients. Our approach could provide an effective way of manufacturing novel bioinspired structural materials, in particular advanced materials such as composites, where a higher level of control over the structure is required.

  18. Pore-Scale Simulation for Predicting Material Transport Through Porous Media

    International Nuclear Information System (INIS)

    Goichi Itoh; Jinya Nakamura; Koji Kono; Tadashi Watanabe; Hirotada Ohashi; Yu Chen; Shinya Nagasaki

    2002-01-01

    Microscopic models of real-coded lattice gas automata (RLG) method with a special boundary condition and lattice Boltzmann method (LBM) are developed for simulating three-dimensional fluid dynamics in complex geometry. Those models enable us to simulate pore-scale fluid dynamics that is an essential part for predicting material transport in porous media precisely. For large-scale simulation of porous media with high resolution, the RLG and LBM programs are designed for parallel computation. Simulation results of porous media flow by the LBM with different pressure gradient conditions show quantitative agreements with macroscopic relations of Darcy's law and Kozeny-Carman equation. As for the efficiency of parallel computing, a standard parallel computation by using MPI (Message Passing Interface) is compared with the hybrid parallel computation of MPI-node parallel technique. The benchmark tests conclude that in case of using large number of computing node, the parallel performance declines due to increase of data communication between nodes and the hybrid parallel computation totally shows better performance in comparison with the standard parallel computation. (authors)

  19. Comparison of salt solution and air drying methods for moisture fixation in highly porous building materials

    DEFF Research Database (Denmark)

    Antonov, Yovko Ivanov; Jensen, Rasmus Lund; Møldrup, Per

    2017-01-01

    In recent years, research has identified some bio-based, porous building materials as good or excellent regulators of moisture in buildings. The ability of a material to absorb, release and store moisture is described by vapour sorption isotherms. It is necessary input to simulations of indoor...... building materials by a standardized testing method, using saturated salt solutions. Furthermore, results from the standard method are compared to values of moisture content for the same materials, obtained by air-drying at different relative humidity. This is done with the aim to compare the findings from...... the two methods with respect to time and repeatability of the results. Derived isotherms are further used as direct input in the building simulation software BSim, which is capable of predicting indoor environment parameters by solving coupled, transient heat and moisture transport equations using finite...

  20. Porous alkali activated materials with slow alkali release dynamic. Role of composition

    International Nuclear Information System (INIS)

    Bumanis, G.; Bajare, D.

    2018-01-01

    Alkali activated materials (AAM) based on calcined metakaolin or illite clay together with waste by-products, such as waste glass or aluminium scrap recycling waste, were tested as value-added materials for pH stabilization in biogas technology where decrease of pH should be avoided. Porous materials with ability to slowly leach alkalis in the water media thus providing continuous control of the pH level were obtained. XRD, FTIR, SEM and titration methods were used to characterize AAM and their leaching properties. It is clear that composition of the material has an important effect on the diffusion of alkali from structure. Namely, higher Si/Al and Na/Al molar ratios may increase pore solution transfer to the leachate. The leaching rate of alkalis from the structure of AAM is high for the first few days, decreasing over time. It was possible to calculate the buffer capacity from the mixture design of AAM. [es

  1. Evaluation of diffusion parameters of radon in porous material by flow-through diffusion experiment

    International Nuclear Information System (INIS)

    Chunnan Hsu; Shihchin Tsai; Shihming Liang

    1994-01-01

    The effectiveness of a material in reducing the fluence rate of Rn from soil was assessed in this study by using a flow-through diffusion experiment to evaluate the diffusion parameters -apparent diffusion coefficient and capacity factor - of radon (Rn) in a porous material. An improved method based on the nonlinear least-squares and Marquardt's method (NLSM method) was proposed to provide more reliable analyses of experimental data than the graphical method. The NLSM method was confirmed by the experimental results to be capable of estimating the diffusion parameters, even if the process was transient. This method was also demonstrated to correlate sufficiently with the results by the conventional method while the process had already reached steady-state. Natural mordenite was employed in this study as a testing material because it has more effective sorption for noble gas than any other earthen material. (author)

  2. New paradigms in internal architecture design and freeform fabrication of tissue engineering porous scaffolds.

    Science.gov (United States)

    Yoo, Dongjin

    2012-07-01

    Advanced additive manufacture (AM) techniques are now being developed to fabricate scaffolds with controlled internal pore architectures in the field of tissue engineering. In general, these techniques use a hybrid method which combines computer-aided design (CAD) with computer-aided manufacturing (CAM) tools to design and fabricate complicated three-dimensional (3D) scaffold models. The mathematical descriptions of micro-architectures along with the macro-structures of the 3D scaffold models are limited by current CAD technologies as well as by the difficulty of transferring the designed digital models to standard formats for fabrication. To overcome these difficulties, we have developed an efficient internal pore architecture design system based on triply periodic minimal surface (TPMS) unit cell libraries and associated computational methods to assemble TPMS unit cells into an entire scaffold model. In addition, we have developed a process planning technique based on TPMS internal architecture pattern of unit cells to generate tool paths for freeform fabrication of tissue engineering porous scaffolds. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Ageing in civil engineering materials and structures

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Jean-Marc [SETEC TPI, Tour Gamma D 58, quai de la Rapee, 75583 Paris (France)

    2005-07-01

    SETEC TPI will address the 'Aging' topic of the Dijon Symposium by talking about: aging in civil engineering materials and structures, prevention of aging phenomena, in-operation monitoring of degradations related to aging and compensatory measures required to maintain a good safety level. Works as the Millau viaduct, the EdF skyscraper at La Defense - Paris, the renovation of the Grand Palais of Paris and special structures with Monaco's floating dam as well as the 'number 10' shaped gateway boat at Marseilles are illustrations for the issues discussed. The durability of civil engineering structures has become a major concern for designers. The Millau viaduct is designed for a service life of 120 years, and the Monaco dam for 100 years. Calculation rules have been evolving toward the incorporation of the concept of life cycle, for example, the Eurocodes 2 rules (reinforced concrete). The talk will expose the factors which are being taken into account to delay aging versus structure types. This part will be focused towards materials and corresponding regulations: - Reinforced concrete (coating of reinforcements, opening of cracks, choice of reinforcement types), BAEL and Eurocodes 2 rules; - Frame steel (protection, sacrificial anode), CM66 and Eurocodes 3 rules. New materials will also be mentioned: - Ultra high-performance fiber/concrete, with the example of CERACEM applied at Millau for the covering of the toll area barrier; - Titanium, which is starting to appear in the building trades, as for instance for the Beijing China Opera House shell. The second part of the talk will be devoted to a specific case namely, the 'number 10' shaped gateway bridge, a prestressed concrete structure immersed in the Port of Marseilles, which will be used to illustrate the aging phenomenon in a corrosive environment. We will focus on the types of inspection series performed by the Autonomous Port Authority of Marseilles to check the behavior of

  4. The effects of surface aging on nanoparticle fate and transport in natural and engineered porous media

    Science.gov (United States)

    Mittelman, Anjuliee M.

    Nanomaterials will be subjected to various surface transformations in the environment and within water and wastewater treatment systems. A comprehensive understanding of the fate and transport behavior of "aged" nanomaterials in both natural and engineered porous media is required in order to accurately quantify ecological and human health risks. This research sought to (1) evaluate the impact of ultraviolet (UV) light aging on nanoparticle transport in water-saturated porous media; and (2) assess the effects of influent water quality on silver nanoparticle retention and dissolution in ceramic water filters. Additionally, the value of quartz crystal microbalance (QCM-D) data in nanoparticle fate and transport studies was evaluated by comparing deposition behavior in complementary QCM-D and sand columns experiments. Silver (nAg) and iron oxide nanoparticles exposed to UV light were up to 50% more strongly retained in porous media compared with freshly prepared suspensions due to less negative surface charge and larger aggregate sizes. UV-aged nAg were more prone to dissolution in sand columns, resulting in effluent Ag+ concentrations as high as 1.2 mg/L. In ceramic water filters, dissolution and cation exchange processes controlled silver release into treated water. The use of acidic, high salinity, or high hardness water accelerated oxidative dissolution of the silver coating and resulted in effluent silver concentrations 5-10 times above international drinking water guidelines. Results support the recommendation for a regular filter replacement or silver re-application schedule to ensure ongoing efficacy. Taken in concert, these research findings suggest that oxidative aging of nanomaterial surfaces (either through exposure to UV light or aggressive water chemistries) will alter the fate of nanomaterials in the environment and may decrease the effective lifetime of devices which utilize nanotechnology. Corresponding QCM-D and column experiments revealed that

  5. Specific Internalisation of Gold Nanoparticles into Engineered Porous Protein Cages via Affinity Binding.

    Science.gov (United States)

    Paramelle, David; Peng, Tao; Free, Paul; Fernig, David G; Lim, Sierin; Tomczak, Nikodem

    2016-01-01

    Porous protein cages are supramolecular protein self-assemblies presenting pores that allow the access of surrounding molecules and ions into their core in order to store and transport them in biological environments. Protein cages' pores are attractive channels for the internalisation of inorganic nanoparticles and an alternative for the preparation of hybrid bioinspired nanoparticles. However, strategies based on nanoparticle transport through the pores are largely unexplored, due to the difficulty of tailoring nanoparticles that have diameters commensurate with the pores size and simultaneously displaying specific affinity to the cages' core and low non-specific binding to the cages' outer surface. We evaluated the specific internalisation of single small gold nanoparticles, 3.9 nm in diameter, into porous protein cages via affinity binding. The E2 protein cage derived from the Geobacillus stearothermophilus presents 12 pores, 6 nm in diameter, and an empty core of 13 nm in diameter. We engineered the E2 protein by site-directed mutagenesis with oligohistidine sequences exposing them into the cage's core. Dynamic light scattering and electron microscopy analysis show that the structures of E2 protein cages mutated with bis- or penta-histidine sequences are well conserved. The surface of the gold nanoparticles was passivated with a self-assembled monolayer made of a mixture of short peptidols and thiolated alkane ethylene glycol ligands. Such monolayers are found to provide thin coatings preventing non-specific binding to proteins. Further functionalisation of the peptide coated gold nanoparticles with Ni2+ nitrilotriacetic moieties enabled the specific binding to oligohistidine tagged cages. The internalisation via affinity binding was evaluated by electron microscopy analysis. From the various mutations tested, only the penta-histidine mutated E2 protein cage showed repeatable and stable internalisation. The present work overcomes the limitations of currently

  6. CO2 Separation and Capture Properties of Porous Carbonaceous Materials from Leather Residues

    Science.gov (United States)

    Bermúdez, José M.; Dominguez, Pablo Haro; Arenillas, Ana; Cot, Jaume; Weber, Jens; Luque, Rafael

    2013-01-01

    Carbonaceous porous materials derived from leather skin residues have been found to have excellent CO2 adsorption properties, with interestingly high gas selectivities for CO2 (α > 200 at a gas composition of 15% CO2/85% N2, 273K, 1 bar) and capacities (>2 mmol·g−1 at 273 K). Both CO2 isotherms and the high heat of adsorption pointed to the presence of strong binding sites for CO2 which may be correlated with both: N content in the leather residues and ultrasmall pore sizes. PMID:28788352

  7. CO2 Separation and Capture Properties of Porous Carbonaceous Materials from Leather Residues

    Directory of Open Access Journals (Sweden)

    Ana Arenillas

    2013-10-01

    Full Text Available Carbonaceous porous materials derived from leather skin residues have been found to have excellent CO2 adsorption properties, with interestingly high gas selectivities for CO2 (α > 200 at a gas composition of 15% CO2/85% N2, 273K, 1 bar and capacities (>2 mmol·g−1 at 273 K. Both CO2 isotherms and the high heat of adsorption pointed to the presence of strong binding sites for CO2 which may be correlated with both: N content in the leather residues and ultrasmall pore sizes.

  8. CO₂ Separation and Capture Properties of Porous Carbonaceous Materials from Leather Residues.

    Science.gov (United States)

    Bermúdez, José M; Dominguez, Pablo Haro; Arenillas, Ana; Cot, Jaume; Weber, Jens; Luque, Rafael

    2013-10-18

    Carbonaceous porous materials derived from leather skin residues have been found to have excellent CO₂ adsorption properties, with interestingly high gas selectivities for CO₂ (α > 200 at a gas composition of 15% CO₂/85% N₂, 273K, 1 bar) and capacities (>2 mmol·g -1 at 273 K). Both CO₂ isotherms and the high heat of adsorption pointed to the presence of strong binding sites for CO₂ which may be correlated with both: N content in the leather residues and ultrasmall pore sizes.

  9. Thermal diffusion of water vapour in porous materials: fact or fiction?

    DEFF Research Database (Denmark)

    Janssen, Hans

    2011-01-01

    diffusion. Thermal diffusion opponents, on the other hand, assert that these thermal transports are negligibly small. This paper resolves that contradiction. A critical analysis of the investigations supporting the occurrence of thermal diffusion reveals that all are flawed. A correct reinterpretation...... its negligible magnitude. It can in conclusion be stated that thermal diffusion is of no importance for building science applications, leaving vapour pressure as the sole significant transport potential for the diffusion of water vapour in porous materials. (C) 2010 Elsevier Ltd. All rights reserved....

  10. Measurement of water vapour transport through a porous non-hygroscopic material in a temperature gradient

    DEFF Research Database (Denmark)

    Hansen, Thor; Padfield, Tim; Hansen, Kurt Kielsgaard

    2014-01-01

    This was an experiment to identify the driving potential for water vapour diffusion through porous materials in a temperature gradient. The specimen of mineral fibre insulation was placed between a space with controlled temperature and relative humidity and a space with a controlled, higher...... temperature, and a measured but not controlled relative humidity (RH). This assembly was allowed to reach equilibrium with no vapour movement between the spaces, as tested by a constant RH on each side and by zero flux of water vapour measured in the cold side chamber. The RH and temperature values were...

  11. Highlights from the Faraday Discussion on New Directions in Porous Crystalline Materials, Edinburgh, UK, June 2017.

    Science.gov (United States)

    Addicoat, Matthew A; Bennett, Thomas D; Stassen, Ivo

    2017-09-28

    A lively discussion on new directions in porous crystalline materials took place in June 2017, with the beautiful city of Edinburgh as a backdrop, in the context of the unique Faraday Discussions format. Here, 5 minute presentations were given on papers which had been submitted in advance of the conference, with copious time allocated for in-depth discussion of the work presented. Prof. Mircea Dincă (MIT), chair of the scientific committee, opened the conference by welcoming the many different nationalities attending, and outlining the format of discussions.

  12. New Porous Material Made from Industrial and Municipal Waste for Building Application

    Directory of Open Access Journals (Sweden)

    Diana BAJARE

    2014-09-01

    Full Text Available The aim of this study was to find a new method for usage of the hazardous waste coming from recycling industry. Two hazardous wastes – aluminium recycling final dross or non-metallic product (NMP and lead – silica glass (LSG were investigated. It is generally considered that NMP is a process waste and subject to disposal after residual metal has been recovered from primary dross. NMP is impurities which are removed from the molten metal in dross recycling process and it could be defined as a hazardous waste product in aluminium recycling industry. LSG comes from fluorescence lamp recycling plant and could be classified as hazardous waste due to high amount of lead in the composition and re-melting problems. The new alkali activated material, which can be defined as porous building material, was created. Composition of this material consisted of aluminium recycling waste, recycled fluorescent lamp LSG, sintered kaolin clay as well as commercially available alkali flakes (NaOH and liquid glass (Na2SiO3 + nH2O. Physical and mechanical properties of the obtained material were tested. Density of the obtained material was from (460 – 550 kg/m3 and the total porosity was from 82 % – 83 %. The compressive strength of the material was in range from 1.1 MPa to 2.3 MPa. The thermal conductivity was determined. The pore microstructure was investigated and the mineralogical composition of porous material was determined. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4330

  13. Frequency-Dependent Streaming Potential of Porous Media—Part 2: Experimental Measurement of Unconsolidated Materials

    Directory of Open Access Journals (Sweden)

    P. W. J. Glover

    2012-01-01

    Full Text Available Frequency-dependent streaming potential coefficient measurements have been made upon Ottawa sand and glass bead packs using a new apparatus that is based on an electromagnetic drive. The apparatus operates in the range 1 Hz to 1 kHz with samples of 25.4 mm diameter up to 150 mm long. The results have been analysed using theoretical models that are either (i based upon vibrational mechanics, (ii treat the geological material as a bundle of capillary tubes, or (iii treat the material as a porous medium. The best fit was provided by the Pride model and its simplification, which is satisfying as this model was conceived for porous media rather than capillary tube bundles. Values for the transition frequency were derived from each of the models for each sample and were found to be in good agreement with those expected from the independently measured effective pore radius of each material. The fit to the Pride model for all four samples was also found to be consistent with the independently measured steady-state permeability, while the value of the streaming potential coefficient in the low-frequency limit was found to be in good agreement with other steady-state streaming potential coefficient data.

  14. Enthalpy-based equation of state for highly porous materials employing modified soft sphere fluid model

    Science.gov (United States)

    Nayak, Bishnupriya; Menon, S. V. G.

    2018-01-01

    Enthalpy-based equation of state based on a modified soft sphere model for the fluid phase, which includes vaporization and ionization effects, is formulated for highly porous materials. Earlier developments and applications of enthalpy-based approach had not accounted for the fact that shocked states of materials with high porosity (e.g., porosity more than two for Cu) are in the expanded fluid region. We supplement the well known soft sphere model with a generalized Lennard-Jones formula for the zero temperature isotherm, with parameters determined from cohesive energy, specific volume and bulk modulus of the solid at normal condition. Specific heats at constant pressure, ionic and electronic enthalpy parameters and thermal excitation effects are calculated using the modified approach and used in the enthalpy-based equation of state. We also incorporate energy loss from the shock due to expansion of shocked material in calculating porous Hugoniot. Results obtained for Cu, even up to initial porosities ten, show good agreement with experimental data.

  15. High-Throughput Characterization of Porous Materials Using Graphics Processing Units

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jihan; Martin, Richard L.; Rübel, Oliver; Haranczyk, Maciej; Smit, Berend

    2012-05-08

    We have developed a high-throughput graphics processing units (GPU) code that can characterize a large database of crystalline porous materials. In our algorithm, the GPU is utilized to accelerate energy grid calculations where the grid values represent interactions (i.e., Lennard-Jones + Coulomb potentials) between gas molecules (i.e., CH$_{4}$ and CO$_{2}$) and material's framework atoms. Using a parallel flood fill CPU algorithm, inaccessible regions inside the framework structures are identified and blocked based on their energy profiles. Finally, we compute the Henry coefficients and heats of adsorption through statistical Widom insertion Monte Carlo moves in the domain restricted to the accessible space. The code offers significant speedup over a single core CPU code and allows us to characterize a set of porous materials at least an order of magnitude larger than ones considered in earlier studies. For structures selected from such a prescreening algorithm, full adsorption isotherms can be calculated by conducting multiple grand canonical Monte Carlo simulations concurrently within the GPU.

  16. Porous TiO2 Conformal Coating on Carbon Nanotubes as Energy Storage Materials

    International Nuclear Information System (INIS)

    Yan, Litao; Xu, Yun; Zhou, Meng; Chen, Gen; Deng, Shuguang; Smirnov, Sergei; Luo, Hongmei; Zou, Guifu

    2015-01-01

    The controllable synthesis of strongly coupled inorganic materials/carbon nanotubes (CNTs) hybrids represents a long-standing challenge for developing advanced catalysts and energy-storage materials. Here we report a simple sol-gel method for facile synthesis of TiO 2 /CNTs hybrid. The porous anatase TiO 2 nanoparticles are uniformly coated on the CNTs conducting network, which leads to remarkably improved electrochemical performances such as exceptional cycling stability, good high rate durability, and reduced resistance. This hybrid exhibits a reversible capacity as high as 200 mA·h g −1 at a current density of 0.1 A g −1 as an anode in lithium-ion battery (LIB). As a supercapacitor (SC), it shows a specific supercapacitance of 145 F g −1 in 0.5 M H 2 SO 4 electrolyte, higher than that of the previously reported TiO 2 based supercapacitors. Moreover, this hybrid also exhibits excellent durability after 1000 cycles for both LIBs and SCs. Such superior performance and cycling durability demonstrate the reinforced synergistic effects between the porous TiO 2 and interweaved CNTs network, indicating a great application potential for such hybrid materials in high power LIBs and SCs

  17. Fabrication and Properties of Silica Gel/Calcium Sulfate/Strontium-doped β-tricalcium Phosphate Composite Porous Scaffolds for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    QIN Xiao-su

    2018-03-01

    Full Text Available The calcium sulfate/strontium-doped β-tricalcium phosphate composite spherical pellets was fabricated, using the calcium sulfate/strontium-doped β-TCP as raw material, and through the stirring spray drying method, and then composite spherical pellets were combined with silica gel, porous silica gel/calcium sulfate/strontium-doped β-tricalcium phosphate scaffold was obtained by stacking aggregation method in the mould. The XRD, SEM and FT-IR, etc are employed to examine the chemical composition, composite morphology and structure characteristics, and the degradability, porosity, mechanical properties and cytotoxicity of the scaffolds materials were studied. The results reveal that the composite porous scaffolds have irregular pore structure with pore size between 0.2-1.0mm, and they have a large number of micropores on each of the composite spherical pellets, with the aperture between 50-200μm. Moreover, the porosity of the composite scaffolds is about 62%, which can meet the requirements of scaffolds for bone tissue engineering in porosity; the cytotoxicity tests show the composite scaffolds have no cytotoxic effect and it has good degradation. Therefore, it has good application prospect in bone tissue engineering of the bone defect repair of non-bearing site.

  18. Sol gel-derived hydroxyapatite films over porous calcium polyphosphate substrates for improved tissue engineering of osteochondral-like constructs.

    Science.gov (United States)

    Lee, Whitaik David; Gawri, Rahul; Pilliar, Robert M; Stanford, William L; Kandel, Rita A

    2017-10-15

    Integration of in vitro-formed cartilage on a suitable substrate to form tissue-engineered implants for osteochondral defect repair is a considerable challenge. In healthy cartilage, a zone of calcified cartilage (ZCC) acts as an intermediary for mechanical force transfer from soft to hard tissue, as well as an effective interlocking structure to better resist interfacial shear forces. We have developed biphasic constructs that consist of scaffold-free cartilage tissue grown in vitro on, and interdigitated with, porous calcium polyphosphate (CPP) substrates. However, as CPP degrades, it releases inorganic polyphosphates (polyP) that can inhibit local mineralization, thereby preventing the formation of a ZCC at the interface. Thus, we hypothesize that coating CPP substrate with a layer of hydroxyapatite (HA) might prevent or limit this polyP release. To investigate this we tested both inorganic or organic sol-gel processing methods, asa barrier coating on CPP substrate to inhibit polyP release. Both types of coating supported the formation of ZCC in direct contact with the substrate, however the ZCC appeared more continuous in the tissue formed on the organic HA sol gel coated CPP. Tissues formed on coated substrates accumulated comparable quantities of extracellular matrix and mineral, but tissues formed on organic sol-gel (OSG)-coated substrates accumulated less polyP than tissues formed on inorganic sol-gel (ISG)-coated substrates. Constructs formed with OSG-coated CPP substrates had greater interfacial shear strength than those formed with ISG-coated and non-coated substrates. These results suggest that the OSG coating method can modify the location and distribution of ZCC and can be used to improve the mechanical integrity of tissue-engineered constructs formed on porous CPP substrates. Articular cartilage interfaces with bone through a zone of calcified cartilage. This study describes a method to generate an "osteochondral-like" implant that mimics this

  19. Preparation of dexamethasone-loaded biphasic calcium phosphate nanoparticles/collagen porous composite scaffolds for bone tissue engineering.

    Science.gov (United States)

    Chen, Ying; Kawazoe, Naoki; Chen, Guoping

    2018-02-01

    Although bone is regenerative, its regeneration capacity is limited. For bone defects beyond a critical size, further intervention is required. As an attractive strategy, bone tissue engineering (bone TE) has been widely investigated to repair bone defects. However, the rapid and effective bone regeneration of large non-healing defects is still a great challenge. Multifunctional scaffolds having osteoinductivity and osteoconductivity are desirable to fasten functional bone tissue regeneration. In the present study, biomimetic composite scaffolds of collagen and biphasic calcium phosphate nanoparticles (BCP NPs) with a controlled release of dexamethasone (DEX) and the controlled pore structures were prepared for bone TE. DEX was introduced in the BCP NPs during preparation of the BCP NPs and hybridized with collagen scaffolds, which pore structures were controlled by using pre-prepared ice particulates as a porogen material. The composite scaffolds had well controlled and interconnected pore structures, high mechanical strength and a sustained release of DEX. The composite scaffolds showed good biocompatibility and promoted osteogenic differentiation of hMSCs when used for three-dimensional culture of human bone marrow-derived mesenchymal stem cells. Subcutaneous implantation of the composite scaffolds at the dorsa of athymic nude mice demonstrated that they facilitated the ectopic bone tissue regeneration. The results indicated the DEX-loaded BCP NPs/collagen composite scaffolds had high potential for bone TE. Scaffolds play a crucial role for regeneration of large bone defects. Biomimetic scaffolds having the same composition of natural bone and a controlled release of osteoinductive factors are desirable for promotion of bone regeneration. In this study, composite scaffolds of collagen and biphasic CaP nanoparticles (BCP NPs) with a controlled release nature of dexamethasone (DEX) were prepared and their porous structures were controlled by using ice particulates

  20. A Novel FCC Catalyst Based on a Porous Composite Material Synthesized via an In Situ Technique

    Directory of Open Access Journals (Sweden)

    Shu-Qin Zheng

    2015-11-01

    Full Text Available To overcome diffusion limitations and improve transport in microporous zeolite, the materials with a wide-pore structure have been developed. In this paper, composite microspheres with hierarchical porous structure were synthesized by an in situ technique using sepiolite, kaolin and pseudoboehmite as raw material. A novel fluid catalytic cracking (FCC catalyst for maximizing light oil yield was prepared based on the composite materials. The catalyst was characterized by XRD, FT-IR, SEM, nitrogen adsorption-desorption techniques and tested in a bench FCC unit. The results indicated that the catalyst had more meso- and macropores and more acid sites than the reference catalyst, and thus can increase light oil yield by 1.31 %, while exhibiting better gasoline and coke selectivity.

  1. Synthesis of nitrogen-doped porous carbon nanofibers as an efficient electrode material for supercapacitors.

    Science.gov (United States)

    Chen, Li-Feng; Zhang, Xu-Dong; Liang, Hai-Wei; Kong, Mingguang; Guan, Qing-Fang; Chen, Ping; Wu, Zhen-Yu; Yu, Shu-Hong

    2012-08-28

    Supercapacitors (also known as ultracapacitors) are considered to be the most promising approach to meet the pressing requirements of energy storage. Supercapacitive electrode materials, which are closely related to the high-efficiency storage of energy, have provoked more interest. Herein, we present a high-capacity supercapacitor material based on the nitrogen-doped porous carbon nanofibers synthesized by carbonization of macroscopic-scale carbonaceous nanofibers (CNFs) coated with polypyrrole (CNFs@polypyrrole) at an appropriate temperature. The composite nanofibers exhibit a reversible specific capacitance of 202.0 F g(-1) at the current density of 1.0 A g(-1) in 6.0 mol L(-1) aqueous KOH electrolyte, meanwhile maintaining a high-class capacitance retention capability and a maximum power density of 89.57 kW kg(-1). This kind of nitrogen-doped carbon nanofiber represents an alternative promising candidate for an efficient electrode material for supercapacitors.

  2. Hierarchical porous carbon materials derived from petroleum pitch for high-performance supercapacitors

    Science.gov (United States)

    Abudu, Patiman; Wang, Luxiang; Xu, Mengjiao; Jia, Dianzeng; Wang, Xingchao; Jia, Lixia

    2018-06-01

    In this work, a honeycomb-like carbon material derived from petroleum pitch was synthesized by a simple one-step carbonization/activation method using silica nanospheres as the hard templates. The obtained hierarchical porous carbon materials (HPCs) with a large specific surface area and uniform macropore distribution provide abundant active sites and sufficient ion migration channels. When used as an electrode material for supercapacitors, the HPCs exhibit a high specific capacitance of 341.0 F g-1 at 1 A g-1, excellent rate capability with a capacitance retention of 55.6% at 50 A g-1 (189.5 F g-1), and outstanding cycling performance in the three-electrode system.

  3. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    Science.gov (United States)

    Rollins, Harry W [Idaho Falls, ID; Petkovic, Lucia M [Idaho Falls, ID; Ginosar, Daniel M [Idaho Falls, ID

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  4. Preparation of degradable porous structures based on 1,3-trimethylene carbonate and D,L-lactide (co)polymers for heart tissue engineering

    NARCIS (Netherlands)

    Pego, AP; Siebum, B; Van Luyn, MJA; Van Seijen, XJGY; Poot, AA; Grijpma, DW; Feijen, J

    2003-01-01

    Biodegradable porous scaffolds for heart tissue engineering were prepared from amorphous elastomeric (co)polymers of 1,3-trimethylene carbonate (TMC) and D,L-lactide (DLLA). Leaching of salt from compression-molded polymer-salt composites allowed the preparation of highly porous structures in a

  5. Dual-energy X-ray absorptiometry for the simultaneous determination of Density and Moisture Content in Porous Structural Materials

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Jensen, Signe Kamp; Gerward, Leif

    1999-01-01

    The paper describes the dual-energy x-ray equipment, which consists of a x-ray source, filters and a detector. The x-ray beam can be moved automatically in two dimensions relative to a fixed specimen. The purpose of the equipment is to measure simultaneously the density and moisture content...... in porous materials relevant for the building industry. The theory of dual-energy x-ray absorptiometry (DEXA) is presented. DEXA results on two combinations of aluminium and acrylic plastic are compared with corresponding values calculated from the geometry of the experimental setup. The results from the x......-ray measurements show good agreement with results from the two standard materials which imitate water in a porous material. On this background the dual-energy x-ray absorptiometry measurement principle can be used on porous structural materials....

  6. Ultrafast Vibrational Spectrometer for Engineered Nanometric Energetic Materials

    National Research Council Canada - National Science Library

    Dlott, Dana

    2002-01-01

    The proposer requested funding for laser equipment that would be used to study engineered nanometric energetic materials consisting of nanometer metal particles, passivation layers and oxidizing binders...

  7. Engineer Research and Development Center's Materials Testing Center (MTC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Engineer Research and Development Center's Materials Testing Center (MTC) is committed to quality testing and inspection services that are delivered on time and...

  8. Environmental, Health, and Safety Research Needs for Engineered Nanoscale Materials

    National Research Council Canada - National Science Library

    Alderson, Norris; Alexander, Catherine; Merzbacher, Celia; Chernicoff, William; Middendorf, Paul; Beck, Nancy; Chow, Flora; Poster, Dianne; Danello, Mary Ann; Barrera, Enriqueta

    2006-01-01

    ...) research and information needs related to understanding and management of potential risks of engineered nanoscale materials that may be used, for example, in commercial or consumer products, medical...

  9. Clutches using engineering ceramics as friction material

    Energy Technology Data Exchange (ETDEWEB)

    Albers, A.; Arslan, A.; Mitariu, M. [Universitaet Karlsruhe (T.H.), IPEK - Institut fuer Produktentwicklung, Kaiserstr. 10, 76131 Karlsruhe (Germany)

    2005-03-01

    The experimental and constructive results illustrate that engineering ceramic materials have a high potential in the field of dry running friction systems. According to first estimations, it is possible to build the vehicle clutch 53 % smaller or to transmit up to 180 % higher torque with the same size by an appropriate selection of the system friction pairing and an adequate ceramic design [1, 2]. The friction coefficient characteristic (decreasing friction coefficient above sliding speed) is unfavourable with regard to comfort (self-induced grab oscillations [3]) of the vehicle clutch. Furthermore, it is important to select the test procedure of the experimental analyses to be as close to the system as possible in order to obtain exact information concerning the target system. (Abstract Copyright [2005], Wiley Periodicals, Inc.) [German] Die experimentellen und konstruktiven Ergebnisse haben gezeigt, dass ingenieurkeramische Werkstoffe ein hohes Potenzial im Bereich der trockenlaufenden Friktionssysteme haben. Durch geeignete Wahl der Systemreibpaarung und eine keramikgerechte Konstruktion ist es nach ersten Abschaetzungen moeglich, die Kfz-Kupplung um 53 % kleiner zu bauen bzw. bei gleicher Groesse bis zu 180 % hoehere Drehmomente zu uebertragen [1, 2]. Die Reibungszahlcharakteristik (fallende Reibungszahl ueber Gleitgeschwindigkeit) ist im Hinblick auf Komfort (selbsterregte Rupfschwingungen [3]) fuer die Kraftfahrzeugkupplung unguenstig. Des Weiteren ist es wichtig, die Versuchsfuehrung der experimentellen Untersuchungen so systemnah wie moeglich zu waehlen, um genauere Aussagen auf das Zielsystem zu erhalten. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  10. Experimental study on method for heat transfer enhancement using a porous material

    International Nuclear Information System (INIS)

    Shimura, Takuya; Takeda, Tetsuaki

    2011-01-01

    There are several methods for enhancement of heat transfer; for example, there are attaching various fins on the heat transfer surface, processing the surface roughly, and so on. When cooling high temperature circular or rectangular channels by forced convection of gas, there are several methods for enhancement of heat transfer such as attaching radial or spiral fins on the channel surface or inserting twisted tape in the channel. In the case of the gas heating type steam reformer, disk type fins are attached on the outside surface of the reformer tube, and the tube is inserted into the guide tube to increase an amount of heat transferred from the high temperature gas. However, it has to take into consideration the deterioration of the structure strength by attaching the fins on the tube surface with the design of the steam reformer. The objective of this study is to clarify performances of a method for heat transfer enhancement using porous material with high porosity. The experiment has been performed using an apparatus which simulated the passage structure of the steam reformer to obtain characteristics of heat transfer and pressure drop. From the results obtained in this experiment, the heat transfer rate by this method showed a good performance in the laminar flow region. It was also found that the method for heat transfer enhancement using porous material with high porosity is further improved under the high temperature condition as compared with the other methods for heat transfer enhancement. (author)

  11. Optimization of process for creating porous structure of materials from industrial waste

    International Nuclear Information System (INIS)

    Mangutova-Stoilkovska, Bianka

    2005-01-01

    Republic of Macedonia, as many European countries, possesses great quantities of industrial waste materials from thermo electrical power stations and metallurgical capacities. The powder from waste fly ash and metallurgical slag was specified from chemical, geometrical, structural and thermochemical aspects. After the consolidation, the compacts were specified from structural, mechanical and thermophysical aspects. Using three kinds of waste glasses (TV glass, window and flask), the sintering temperature was significantly reduced and ecologically risky components were fixed molecularly in the matrix based on fly ash and metallurgical slag. The glass was characterized from chemical, geometrical and thermophysical point of view. The amount of glass in the composites varied from 10%-50%. The mechanical and thermal expansion properties of the sintered compacts, in the temperature region from 800 o -1200 o C were determined. The thermodynamic stability, mechanical properties and chemical inertness have been used as criterion for selection of the consolidated compacts. Special attention was given to the creation of highly porous structure. For the purpose to obtain a high joint porous structure, several types of porosity have been used: polyurethane foam, hydrogen peroxide, limestone, carbon ash and carbon fibres. The obtained glass-ceramic materials could be used in the building industry, for making filters for gases and liquids as well as diffusers for waste water aeration. (Author)

  12. Material transport through porous media: a finite-element Galerkin model

    International Nuclear Information System (INIS)

    Duguid, J.O.; Reeves, M.

    1976-03-01

    A two-dimensional transient model for flow of a dissolved constituent through porous media has been developed. Mechanisms for advective transport, hydrodynamic dispersion, chemical absorption, and radioactive decay are included in the mathematical formulation. Implementations of quadrilateral finite elements, bilinear spatial interpolation, and Gaussian elimination are used in the numerical formulation. The programming language FORTRAN IV is used exclusively in the computer implementation. A listing of the program is included. This material-transport model is completely compatible with our moisture-transport model (Reeves and Duguid, 1975) for predicting advective Darcy velocities for porous media which may be partly unsaturated. In addition to a description of the mathematical formulation, the numerical treatment and the computer implementation results of two computer simulations are included in this document. One is a comparison with a well-known analytical treatment (Lapidus and Amundson, 1952) and is intended as a partial validation. The other simulation, a seepage-pond problem, is a more realistic demonstration of the capabilities of the computer model. Complete listings of input and output are given in the appendices so that this simulation may be used for check-out purposes. A comprehensive description of the material-transport computer model is given

  13. Natural sisal fibers derived hierarchical porous activated carbon as capacitive material in lithium ion capacitor

    Science.gov (United States)

    Yang, Zhewei; Guo, Huajun; Li, Xinhai; Wang, Zhixing; Yan, Zhiliang; Wang, Yansen

    2016-10-01

    Lithium-ion capacitor (LIC) is a novel advanced electrochemical energy storage (EES) system bridging gap between lithium ion battery (LIB) and electrochemical capacitor (ECC). In this work, we report that sisal fiber activated carbon (SFAC) was synthesized by hydrothermal treatment followed by KOH activation and served as capacitive material in LIC for the first time. Different particle structure, morphology, specific surface area and heteroatoms affected the electrochemical performance of as-prepared materials and corresponding LICs. When the mass ratio of KOH to char precursor was 2, hierarchical porous structured SFAC-2 was prepared and exhibited moderate specific capacitance (103 F g-1 at 0.1 A g-1), superior rate capability and cyclic stability (88% capacity retention after 5000 cycles at 1 A g-1). The corresponding assembled LIC (LIC-SC2) with optimal comprehensive electrochemical performance, displayed the energy density of 83 Wh kg-1, the power density of 5718 W kg-1 and superior cyclic stability (92% energy density retention after 1000 cycles at 0.5 A g-1). It is worthwhile that the source for activated carbon is a natural and renewable one and the synthesis method is eco-friendly, which facilitate that hierarchical porous activated carbon has potential applications in the field of LIC and other energy storage systems.

  14. One-dimensional scanning of moisture in heated porous building materials with NMR.

    Science.gov (United States)

    van der Heijden, G H A; Huinink, H P; Pel, L; Kopinga, K

    2011-02-01

    In this paper we present a new dedicated NMR setup which is capable of measuring one-dimensional moisture profiles in heated porous materials. The setup, which is placed in the bore of a 1.5 T whole-body scanner, is capable of reaching temperatures up to 500 °C. Moisture and temperature profiles can be measured quasi simultaneously with a typical time resolution of 2-5 min. A methodology is introduced for correcting temperature effects on NMR measurements at these elevated temperatures. The corrections are based on the Curie law for paramagnetism and the observed temperature dependence of the relaxation mechanisms occurring in porous materials. Both these corrections are used to obtain a moisture content profile from the raw NMR signal profile. To illustrate the methodology, a one-sided heating experiment of concrete with a moisture content in equilibrium with 97% RH is presented. This kind of heating experiment is of particular interest in the research on fire spalling of concrete, since it directly reveals the moisture and heat transport occurring inside the concrete. The obtained moisture profiles reveal a moisture peak building up behind the boiling front, resulting in a saturated layer. To our knowledge the direct proof of the formation of a moisture peak and subsequent moisture clogging has not been reported before. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. A new porous hybrid material derived from silica fume and alginate for sustainable pollutants reduction

    Science.gov (United States)

    Zanoletti, Alessandra; Vassura, Ivano; Venturini, Elisa; Monai, Matteo; Montini, Tiziano; Federici, Stefania; Zacco, Annalisa; Treccani, Laura; Bontempi, Elza

    2018-03-01

    In this work a new mesoporous adsorbent material obtained from a natural, high abundant raw material and a high volume industrial by-product is presented. The material is consolidated by the gelling properties of alginate and by decomposition of sodium-bicarbonate controlled porosity at low temperatures (70-80°C) at different scale lengths. The structural, thermal, and morphological characterization shows that the material is a mesoporous organic-inorganic hybrid. The material is tested as adsorbent, showing high performances. Methylene blue, used as model pollutant, can be adsorbed and removed from aqueous solutions even at a high concentration with efficiency up to 94%. By coating the material with a 100 nm thin film of titania, good photodegradation performance (more than 20%) can be imparted. Based on embodied energy and carbon footprint of its primary production, the sustainability of the new obtained material is evaluated and quantified in respect to activated carbon as well. It is shown that the new proposed material has an embodied energy lower than one order of magnitude in respect to the one of activated carbon, which represents the gold standards. The versatility of the new material is also demonstrated in terms of its design and manufacturing possibilities. In addition, this material can be printed in 3D. Finally, preliminary results about its ability to capture diesel exhaust particulate matter are reported. The sample exposed to diesel contains a large amount of carbon in its surface. At the best of our knowledge this is the first time that hybrid porous materials are proposed as a new class of sustainable materials, produced to reduce pollutants in the wastewaters and in the atmosphere.

  16. 3D printing of porous hydroxyapatite scaffolds intended for use in bone tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Cox, Sophie C.; Thornby, John A.; Gibbons, Gregory J., E-mail: G.J.Gibbons@warwick.ac.uk; Williams, Mark A.; Mallick, Kajal K.

    2015-02-01

    A systematic characterisation of bone tissue scaffolds fabricated via 3D printing from hydroxyapatite (HA) and poly(vinyl)alcohol (PVOH) composite powders is presented. Flowability of HA:PVOH precursor materials was observed to affect mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The ultimate compressive strength of 55% porous green scaffolds printed along the Y-axis and dried in a vacuum oven for 6 h was 0.88 ± 0.02 MPa. Critically, the pores of 3D printed constructs could be user designed, ensuring bulk interconnectivity, and the imperfect packing of powder particles created an inherent surface roughness and non-designed porosity within the scaffold. These features are considered promising since they are known to facilitate osteoconduction and osteointegration in-vivo. Characterisation techniques utilised in this study include two funnel flow tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), compressive strength testing and computed tomography (CT). - Highlights: • Flowability of HA and PVOH powders corresponded to scaffold printability. • Anisotropic behaviour of 3D printed scaffolds was highlighted by compressive tests. • Maximum compressive strength of 3D printed 55% porous scaffolds was 0.88 MPa. • Imperfect packing of precursors resulted in a rough surface and microporosity. • A CT method was designed and used to quantify designed and non-designed porosity.

  17. 3D printing of porous hydroxyapatite scaffolds intended for use in bone tissue engineering applications

    International Nuclear Information System (INIS)

    Cox, Sophie C.; Thornby, John A.; Gibbons, Gregory J.; Williams, Mark A.; Mallick, Kajal K.

    2015-01-01

    A systematic characterisation of bone tissue scaffolds fabricated via 3D printing from hydroxyapatite (HA) and poly(vinyl)alcohol (PVOH) composite powders is presented. Flowability of HA:PVOH precursor materials was observed to affect mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The ultimate compressive strength of 55% porous green scaffolds printed along the Y-axis and dried in a vacuum oven for 6 h was 0.88 ± 0.02 MPa. Critically, the pores of 3D printed constructs could be user designed, ensuring bulk interconnectivity, and the imperfect packing of powder particles created an inherent surface roughness and non-designed porosity within the scaffold. These features are considered promising since they are known to facilitate osteoconduction and osteointegration in-vivo. Characterisation techniques utilised in this study include two funnel flow tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), compressive strength testing and computed tomography (CT). - Highlights: • Flowability of HA and PVOH powders corresponded to scaffold printability. • Anisotropic behaviour of 3D printed scaffolds was highlighted by compressive tests. • Maximum compressive strength of 3D printed 55% porous scaffolds was 0.88 MPa. • Imperfect packing of precursors resulted in a rough surface and microporosity. • A CT method was designed and used to quantify designed and non-designed porosity

  18. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures

    KAUST Repository

    Mughal, Asad Jahangir; El Demellawi, Jehad K.; Chaieb, Saharoui

    2014-01-01

    reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size

  19. Artificial implant materials - role of biomaterials in the tissue engineering

    International Nuclear Information System (INIS)

    Lewandowska-Szumiel, M.

    2007-01-01

    Lecture presents different materials applicable in production of implants. All these materials should be sterilized, however some of them can be modified using by irradiation (e.g. polymers). Numerous examples of tissue engineering are presented

  20. Application of computational methods to the design and characterisation of porous molecular materials.

    Science.gov (United States)

    Evans, Jack D; Jelfs, Kim E; Day, Graeme M; Doonan, Christian J

    2017-06-06

    Composed from discrete units, porous molecular materials (PMMs) possess unique properties not observed for conventional, extended, solids, such as solution processibility and permanent porosity in the liquid phase. However, identifying the origin of porosity is not a trivial process, especially for amorphous or liquid phases. Furthermore, the assembly of molecular components is typically governed by a subtle balance of weak intermolecular forces that makes structure prediction challenging. Accordingly, in this review we canvass the crucial role of molecular simulations in the characterisation and design of PMMs. We will outline strategies for modelling porosity in crystalline, amorphous and liquid phases and also describe the state-of-the-art methods used for high-throughput screening of large datasets to identify materials that exhibit novel performance characteristics.

  1. Sound transmission through double cylindrical shells lined with porous material under turbulent boundary layer excitation

    Science.gov (United States)

    Zhou, Jie; Bhaskar, Atul; Zhang, Xin

    2015-11-01

    This paper investigates sound transmission through double-walled cylindrical shell lined with poroelastic material in the core, excited by pressure fluctuations due to the exterior turbulent boundary layer (TBL). Biot's model is used to describe the sound wave propagating in the porous material. Three types of constructions, bonded-bonded, bonded-unbonded and unbonded-unbonded, are considered in this study. The power spectral density (PSD) of the inner shell kinetic energy is predicted for two turbulent boundary layer models, different air gap depths and three types of polyimide foams, respectively. The peaks of the inner shell kinetic energy due to shell resonance, hydrodynamic coincidence and acoustic coincidence are discussed. The results show that if the frequency band over the ring frequency is of interest, an air gap, even if very thin, should exist between the two elastic shells for better sound insulation. And if small density foam has a high flow resistance, a superior sound insulation can still be maintained.

  2. Production of nanotubes in delignified porous cellulosic materials after hydrolysis with cellulase.

    Science.gov (United States)

    Koutinas, Αthanasios Α; Papafotopoulou-Patrinou, Evgenia; Gialleli, Angelika-Ioanna; Petsi, Theano; Bekatorou, Argyro; Kanellaki, Maria

    2016-08-01

    In this study, tubular cellulose (TC), a porous cellulosic material produced by delignification of sawdust, was treated with a Trichoderma reesei cellulase in order to increase the proportion of nano-tubes. The effect of enzyme concentration and treatment duration on surface characteristics was studied and the samples were analyzed with BET, SEM and XRD. Also, a composite material of gelatinized starch and TC underwent enzymatic treatment in combination with amylase (320U) and cellulase (320U) enzymes. For TC, the optimum enzyme concentration (640U) led to significant increase of TC specific surface area and pore volume along with the reduction of pore diameter. It was also shown that the enzymatic treatment did not result to a significant change of cellulose crystallinity index. The produced nano-tubular cellulose shows potential for application to drug and chemical preservative delivery systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Synthesis of Nanoscale Lithium-Ion Battery Cathode Materials Using a Porous Polymer Precursor Method

    KAUST Repository

    Deshazer, H.D.

    2011-01-01

    Fine particles of metal oxides with carefully controlled compositions can be easily prepared by the thermal decomposition of porous polymers, such as cellulose, into which solutions containing salts of the desired cations have been dissolved. This is a simple and versatile method that can be used to produce a wide variety of materials with a range of particle sizes and carefully controlled chemical compositions. Examples of the use of this method to produce fine particles of LiCoO2 and Li(NiMnCo)1/3O2, which are used in the positive electrodes of lithium-ion batteries, are shown. Experiments have demonstrated that materials made using this method can have electrochemical properties comparable to those typically produced by more elaborate procedures. © 2011 The Electrochemical Society.

  4. The Effect of Plasma Surface Treatment on a Porous Green Ceramic Film with Polymeric Binder Materials

    International Nuclear Information System (INIS)

    Yun Jeong Woo

    2013-01-01

    To reduce time and energy during thermal binder removal in the ceramic process, plasma surface treatment was applied before the lamination process. The adhesion strength in the lamination films was enhanced by oxidative plasma treatment of the porous green ceramic film with polymeric binding materials. The oxygen plasma characteristics were investigated through experimental parameters and weight loss analysis. The experimental results revealed the need for parameter analysis, including gas material, process time, flow rate, and discharge power, and supported a mechanism consisting of competing ablation and deposition processes. The weight loss analysis was conducted for cyclic plasma treatment rather than continuous plasma treatment for the purpose of improving the film's permeability by suppressing deposition of the ablated species. The cyclic plasma treatment improved the permeability compared to the continuous plasma treatment.

  5. Influence of kaolin and firing temperature on the mullite formation in porous mullite-corundum materials

    International Nuclear Information System (INIS)

    Mahnicka, L; Svinka, R; Svinka, V

    2011-01-01

    The refractory ceramics became very important in both the traditional and the advanced materials applications as it has outstanding thermal and mechanical properties. The refractoriness of ceramics can be achieved by getting the mullite-corundum. Refractory ceramics with high porosity serve as a heat insulator and constructional material. Three series of porous mullite-corundum ceramic samples were prepared from Al 2 O 3 (Nabalox, Germany) and pure SiO 2 in 2.57:1 ratio that was conformed to mullite compositions (3Al 2 O 3 ·2SiO 2 ). α-Al 2 O 3 (d 50 = 4 μm) and γ-Al 2 O 3 (d 50 = 80 μm) were in 1:3 ratio. Quantity of kaolin (MEKA, Germany) was 10, 20 and 30 wt.%. Porous materials were prepared by slip casting of suspension of raw materials, where the aluminium paste (0.18 wt.%) was used as a pore former. Water content in the suspensions was 38-40 wt.%. Pore formation occured in result of hydrogen formation in chemical reaction between aluminium paste and water. The samples were sintered at 1650, 1700 and 1750°C temperature for one hour. SiO 2 and γ-Al 2 O 3 on the contrary reduced mechanical properties, but decreased shrinkage. Using of α-, γ-Al 2 O 3 , SiO 2 and kaolin in corresponding ratios the samples with open porosity of 30 to 54 vol% were acquired. The relative amounts of pores depended on the initial content of kaolin and on firing temperature.

  6. Rapid Generation of Superheated Steam Using a Water-containing Porous Material

    Science.gov (United States)

    Mori, Shoji; Okuyama, Kunito

    Heat treatment by superheated steam has been utilized in several industrial fields including sterilization, desiccation, and cooking. In particular, cooking by superheated steam is receiving increased attention because it has advantages of reducing the salt and fat contents in foods as well as suppressing the oxidation of vitamin C and fat. In this application, quick startup and cut-off responses are required. Most electrically energized steam generators require a relatively long time to generate superheated steam due to the large heat capacities of the water in container and of the heater. Zhao and Liao (2002) introduced a novel process for rapid vaporization of subcooled liquid, in which a low-thermal-conductivity porous wick containing water is heated by a downward-facing grooved heating block in contact with the upper surface of the wick structure. They showed that saturated steam is generated within approximately 30 seconds from room-temperature water at a heat flux 41.2 kW⁄m2. In order to quickly generate superheated steam of approximately 300°C, which is required for cooking, the heat capacity of the heater should be as small as possible and the imposed heat flux should be so high enough that the porous wick is able to dry out in the vicinity of the contact with the heater and that the resulting heater temperature becomes much higher than the saturation temperature. The present paper proposes a simple structured generator to quickly produce superheated steam. Only a fine wire heater is contacted spirally on the inside wall in a hollow porous material. The start-up, cut-off responses and the rate of energy conversion for input power are investigated experimentally. Superheated steam of 300°C is produced in approximately 19 seconds from room-temperature water for an input power of 300 W. The maximum rate of energy conversion in the steady state is approximately 0.9.

  7. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

    Science.gov (United States)

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

    2014-04-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.

  8. Preparation of gelatin based porous biocomposite for bone tissue engineering and evaluation of gamma irradiation effect on its properties

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Md. Minhajul [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka 1000 (Bangladesh); Khan, Mubarak A. [Institute of Radiation and Polymer Technology (IRPT), Atomic Energy Research Establishment (AERE), P. O. Box No. 3787, Dhaka 1000 (Bangladesh); Rahman, Mohammed Mizanur, E-mail: mizanur.rahman@du.ac.bd [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka 1000 (Bangladesh)

    2015-04-01

    Biodegradable porous hybrid polymer composites were prepared by using gelatin as base polymer matrix, β-tricalcium phosphate (TCP) and calcium sulfate (CS) as cementing materials, chitosan as an antimicrobial agent, and glutaraldehyde and polyethylene glycol (PEG) as crosslinkers at different mass ratios. Thereafter, the composites were subjected to γ-radiation sterilization. The structure and properties of these composite scaffolds were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mechanical properties testing (compressive, bending, tensile and impact), thermogravimetry/differential thermal analysis (TG/DTA), and physical stability test in simulated body fluid (SBF). We found that TCP rich composites showed enhanced mechanical properties among all the crosslinked composites. γ-Radiation sterilization triggered further cross linking in polymer matrix resulting a decrease in pore size of the composites and an increase in pore wall thickness with improved mechanical and thermal properties. The chemically crosslinked composite with 40% TCP followed by γ-radiation sterilization showed the smallest pore size distribution with a mean pore diameter of 159.22 μm, which falls in the range of 100–350 μm — known to be suitable for osteoconduction. Considering its improved mechanical and thermal properties along with osteoconduction ability without cytotoxicity, we propose this biocomposite as a viable candidate for bone tissue engineering. - Highlights: • Composite scaffolds were prepared from biopolymers (gelatin and chitosan). • β-TCP and CS were used as bioactive cementing materials at different ratios. • γ-Sterilization improved the mechanical properties of the biocomposites. • γ-Sterilization reduced the cytotoxicity and induced high antimicrobial properties. • Composite having 40% TCP has the proper pore size distribution for osteoconduction.

  9. General and special engineering materials science. Vol. 1

    International Nuclear Information System (INIS)

    Ondracek, G.; Voehringer, O.

    1983-04-01

    The present report about general and special engineering materials science is the result of lectures given by the authors in two terms in 1982 at Instituto Balseiro, San Carlos de Bariloche, the graduated college of the Universidad de Cuyo and Comision Nacional de Energia Atomica, Republica Argentina. These lectures were organised in the frame of the project ''nuclear engineering'' (ARG/78/020) of the United Nations Development Program (UNDP) by the International Atomic Energy Agency (IAEA). Some chapters of the report are written in English, others in Spanish. The report is subdivided into three volumes: Volume I treats general engineering materials science in 4 capital chapters on the structure of materials, the properties of materials, materials technology and materials testing and investigation supplemented by a selected detailed chapter about elasticity plasticity and rupture mechanics. Volume II concerns special engineering materials science with respect to nuclear materials under normal reactor operation conditions including reactor clad and structural materials, nuclear fuels and fuel elements and nuclear waste as a materials viewpoint. Volume III - also concerning special engineering materials science - considers nuclear materials with respect to off-normal (''accident'') reactor operation conditions including nuclear materials in loss-of-coolant accidents and nuclear materials in core melt accidents. (orig.) [de

  10. Engineering and material aspects of impurity control systems

    International Nuclear Information System (INIS)

    Koski, J.A.

    1985-01-01

    The design of impurity control devices for fusion energy devices is discussed from the engineering and materials viewpoint. First, examples of impurity control devices are presented, and the plasma edge environment for which they are designed is briefly described. Materials concerns related to the design of the components are discussed and some currently proposed designs presented. Engineering tools available to the designer are listed, and some commonly encountered engineering analysis problems described

  11. Expanding UCR’s Interdisciplinary Materials Science and Engineering Faculty

    Science.gov (United States)

    2018-02-27

    and Engineering Faculty 5a. CONTRACT NUMBER 5b. GRANT NUMBER N00014-16-1-2298 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Cindy Larive, Provost Shane...Cybart, Assistant Professor Mitch Boretz, Office of the Dean, Bourns College of Engineering 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT...the Materials Science and Engineering program. Dr. Cybart’s expertise is in superconducting materials, specifically complex oxide devices. His work has

  12. The measurement of pore size in porous and microporous materials using resonant ion beam backscattering

    International Nuclear Information System (INIS)

    Armitage, B.H.; Ramsay, J.D.F.; Brady, F.P.

    1978-01-01

    Established methods for measuring the size of pores in porous materials include those of mercury porosimetry and gas adsorption. A disadvantage of these methods is that only one determination can be made for each prepared specimen. A property of the ion beam backscattering method is that each specimen can be probed over the surface and also as a function of depth. Furthermore for microporous samples (pore width less than 2 nm) mercury penetration methods cannot be used because the high pressures involved make unreasonable demands in terms of mechanical strength. At the same time gas adsoption techniques are considerably restricted because capillary condensation is no longer possible because of the small size of the pores. A description is given of the methods of calculation of pore size from resonant ion beam backscattering data, with various assumptions for the pore and interpore path length distributions. Examples are shown of results obtained with highly porous silica gels where good agreement with gas adsoption has been achieved. Finally, some results obtained by scanning silica gels of lower porosity are also given. (Auth.)

  13. Elaboration of porous gehlenite and anorthite based ceramics using low price raw materials

    Directory of Open Access Journals (Sweden)

    F. Zenikheri

    Full Text Available Abstract Porous ceramics of good quality cost a lot in the world market, which has limited their use in developing countries. This is why this work was mainly devoted to prepare low-cost and good quality ceramics, using kaolin (DD2 type and calcite (CaCO3 available in abundance in Algeria. Based on previous results, 28 wt% CaCO3 ceramic was selected. The presence of CaCO3 favors to achieve porous samples characterized by a high percentage of porosity due to the CO2 release and CaO formation during its calcination at about 700 °C. The choice of these raw materials is based on their natural abundance (low price. It has been found that the samples had interesting characteristics: average pore size between 2.87 and 6.50 μm and porosity between 53 and 57%. It has also been found that the manufactured membrane supports are mainly constituted of gehlenite and anorthite phases. Moreover, the pore size distribution was mono-modal type. The surface and cross-section morphologies observed through a scanning electron microscope were also homogeneous and do not present any possible macro-defects (cracks, etc..

  14. Vapor Phase Polymerization Deposition Conducting Polymer Nanocomposites on Porous Dielectric Surface as High Performance Electrode Materials

    Institute of Scientific and Technical Information of China (English)

    Ya jie Yang; Luning Zhang; Shibin Li; Zhiming Wang; Jianhua Xu; Wenyao Yang; Yadong Jiang

    2013-01-01

    We report chemical vapor phase polymerization(VPP) deposition of poly(3,4-ethylenedioxythiophene)(PEDOT) and PEDOT/graphene on porous dielectric tantalum pentoxide(Ta2O5) surface as cathode films for solid tantalum electrolyte capacitors. The modified oxidant/oxidant-graphene films were first deposited on Ta2O5 by dip-coating, and VPP process was subsequently utilized to transfer oxidant/oxidant-graphene into PEDOT/PEDOT-graphene films. The SEM images showed PEDOT/PEDOT-graphene films was successfully constructed on porous Ta2O5 surface through VPP deposition, and a solid tantalum electrolyte capacitor with conducting polymer-graphene nano-composites as cathode films was constructed. The high conductivity nature of PEDOT-graphene leads to resistance decrease of cathode films and lower contact resistance between PEDOT/graphene and carbon paste. This nano-composite cathode films based capacitor showed ultralow equivalent series resistance(ESR) ca. 12 m? and exhibited excellent capacitance-frequency performance, which can keep 82% of initial capacitance at 500 KHz. The investigation on leakage current revealed that the device encapsulation process has no influence on capacitor leakage current, indicating the excellent mechanical strength of PEDOT/PEDOT-gaphene films. This high conductivity and mechanical strength of graphene-based polymer films shows promising future for electrode materials such as capacitors, organic solar cells and electrochemical energy storage devices.

  15. Synthesis of Hierarchically Porous Sandwich-Like Carbon Materials for High-Performance Supercapacitors.

    Science.gov (United States)

    Li, Yiju; Chen, Chaoji; Gao, Tingting; Zhang, Dongming; Huang, Xiaomei; Pan, Yue; Ye, Ke; Cheng, Kui; Cao, Dianxue; Wang, Guiling

    2016-11-14

    For the first time, hierarchically porous carbon materials with a sandwich-like structure are synthesized through a facile and efficient tri-template approach. The hierarchically porous microstructures consist of abundant macropores and numerous micropores embedded into the crosslinked mesoporous walls. As a result, the obtained carbon material with a unique sandwich-like structure has a relatively high specific surface (1235 m 2  g -1 ), large pore volume (1.30 cm 3  g -1 ), and appropriate pore size distribution. These merits lead to a comparably high specific capacitance of 274.8 F g -1 at 0.2 A g -1 and satisfying rate performance (87.7 % retention from 1 to 20 A g -1 ). More importantly, the symmetric supercapacitor with two identical as-prepared carbon samples shows a superior energy density of 18.47 Wh kg -1 at a power density of 179.9 W kg -1 . The asymmetric supercapacitor based on as-obtained carbon sample and its composite with manganese dioxide (MnO 2 ) can reach up to an energy density of 25.93 Wh kg -1 at a power density of 199.9 W kg -1 . Therefore, these unique carbon material open a promising prospect for future development and utilization in the field of energy storage. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Ultrahigh and Selective SO2 Uptake in Inorganic Anion-Pillared Hybrid Porous Materials.

    Science.gov (United States)

    Cui, Xili; Yang, Qiwei; Yang, Lifeng; Krishna, Rajamani; Zhang, Zhiguo; Bao, Zongbi; Wu, Hui; Ren, Qilong; Zhou, Wei; Chen, Banglin; Xing, Huabin

    2017-07-01

    The efficient capture of SO 2 is of great significance in gas-purification processes including flue-gas desulfurization and natural-gas purification, but the design of porous materials with high adsorption capacity and selectivity of SO 2 remains very challenging. Herein, the selective recognition and dense packing of SO 2 clusters through multiple synergistic host-guest and guest-guest interactions by controlling the pore chemistry and size in inorganic anion (SiF 6 2- , SIFSIX) pillared metal-organic frameworks is reported. The binding sites of anions and aromatic rings in SIFSIX materials grasp every atom of SO 2 firmly via S δ+ ···F δ- electrostatic interactions and O δ- ···H δ+ dipole-dipole interactions, while the guest-guest interactions between SO 2 molecules further promote gas trapping within the pore space, which is elucidated by first-principles density functional theory calculations and powder X-ray diffraction experiments. These interactions afford new benchmarks for the highly efficient removal of SO 2 from other gases, even if at a very low SO 2 concentration. Exceptionally high SO 2 capacity of 11.01 mmol g -1 is achieved at atmosphere pressure by SIFSIX-1-Cu, and unprecedented low-pressure SO 2 capacity is obtained in SIFSIX-2-Cu-i (4.16 mmol g -1 SO 2 at 0.01 bar and 2.31 mmol g -1 at 0.002 bar). More importantly, record SO 2 /CO 2 selectivity (86-89) and excellent SO 2 /N 2 selectivity (1285-3145) are also achieved. Experimental breakthrough curves further demonstrate the excellent performance of these hybrid porous materials in removing low-concentration SO 2 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Effect of sintering conditions on the microstructural and mechanical characteristics of porous magnesium materials prepared by powder metallurgy.

    Science.gov (United States)

    Čapek, Jaroslav; Vojtěch, Dalibor

    2014-02-01

    There has recently been an increased demand for porous magnesium materials in many applications, especially in the medical field. Powder metallurgy appears to be a promising approach for the preparation of such materials. Many works have dealt with the preparation of porous magnesium; however, the effect of sintering conditions on material properties has rarely been investigated. In this work, we investigated porous magnesium samples that were prepared by powder metallurgy using ammonium bicarbonate spacer particles. The effects of the purity of the argon atmosphere and sintering time on the microstructure (SEM, EDX and XRD) and mechanical behaviour (universal loading machine and Vickers hardness tester) of porous magnesium were studied. The porosities of the prepared samples ranged from 24 to 29 vol.% depending on the sintering conditions. The purity of atmosphere played a significant role when the sintering time exceeded 6h. Under a gettered argon atmosphere, a prolonged sintering time enhanced diffusion connections between magnesium particles and improved the mechanical properties of the samples, whereas under a technical argon atmosphere, oxidation at the particle surfaces caused deterioration in the mechanical properties of the samples. These results suggest that a refined atmosphere is required to improve the mechanical properties of porous magnesium. © 2013.

  18. Engineered Materials for Advanced Gas Turbine Engine, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop innovative composite powders and composites that will surpass the properties of currently identified materials for advanced gas turbine...

  19. Hyperbranched Polymers - Engineering Materials and Degradation Behavior

    National Research Council Canada - National Science Library

    Wooley, Karen

    2000-01-01

    .... In the studies supported under this grant, hyperbranched polycarbonates were designed as analogs to common engineering polymers to investigate the effects of branching upon the chain-chain packing...

  20. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene

    KAUST Repository

    Cui, X.

    2016-05-20

    The trade-off between physical adsorption capacity and selectivity of porous materials is a major barrier for efficient gas separation and purification through physisorption. We report control over pore chemistry and size in metal coordination networks with hexafluorosilicate and organic linkers for the purpose of preferential binding and orderly assembly of acetylene molecules through cooperative host-guest and/or guest-guest interactions. The specific binding sites for acetylene are validated by modeling and neutron powder diffraction studies. The energies associated with these binding interactions afford high adsorption capacity (2.1 millimoles per gram at 0.025 bar) and selectivity (39.7 to 44.8) for acetylene at ambient conditions. Their efficiency for the separation of acetylene/ethylene mixtures is demonstrated by experimental breakthrough curves (0.73 millimoles per gram from a 1/99 mixture).

  1. The role of positron annihilation lifetime studies and nuclear sensors for characterising porous materials

    International Nuclear Information System (INIS)

    Mume, E; Smith, S V; Uedono, A; Mizunaga, G; Lynch, D E

    2011-01-01

    A series of nuclear sensors were designed to assess the chemistry within the nanopores of a porous material. The nuclear sensors of varying size, charge, and hydrophobicity were exposed to hollow silica shells (HSS) at varying pH. Uptake and release kinetics were studied over a 24 h period at room temperature. Preliminary study indicate positively charged nuclear sensors were selectively and rapidly (within 10 min) absorbed by the HSS at pH 7 to 9. PALS showed there were two types of pores (1.7 and 0.7 nm) present. The data suggest the nuclear sensors sit within the larger pore of the HSS. Both PALS and nuclear sensors are required to obtain an accurate insight into the nanoporosity of the hollow silica shells.

  2. Investigations on deflagration to detonation transition in porous energetic materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States)

    1999-07-01

    The research carried out by this contract was part of a larger effort funded by LANL in the areas of deflagration to detonation in porous energetic materials (DDT) and detonation shock dynamics in high explosives (DSD). In the first three years of the contract the major focus was on DDT. However, some researchers were carried out on DSD theory and numerical implementation. In the last two years the principal focus of the contract was on DSD theory and numerical implementation. However, during the second period some work was also carried out on DDT. The paper discusses DDT modeling and DSD modeling. Abstracts are included on the following topics: modeling deflagration to detonation; DSD theory; DSD wave front tracking; and DSD program burn implementation.

  3. Sound transmission through double panel constructions lined with elastic porous materials

    Science.gov (United States)

    Bolton, J. S.; Green, E. R.

    1986-07-01

    Attention is given to a theory governing one-dimensional wave motion in elastic porous materials which is capable of reproducing experimental transmission measurements for unfaced polyurethane foam layers. Calculations of the transmission loss of fuselage-like foam-lined double panels are presented and it is shown that the foam/panel boundary conditions have a large effect on the panel performance; a hybrid arrangement whereby the foam is bonded directly to one panel and separated from the other by a thin air gap appears to be the most advantageous under practical circumstances. With this configuratiom, the mass-air-mass resonance is minimized and increased low-frequency performance is offered.

  4. Theoretical analysis of moisture transport in wood as an open porous hygroscopic material

    DEFF Research Database (Denmark)

    Hozjan, Tomaz; Svensson, Staffan

    2010-01-01

    Moisture transport in an open porous hygroscopic material such as wood is a complex system of coupled processes. For seasoned wood in natural climate three fully coupled processes active in the moisture transport are readily identified: (1) diffusion of vapor in pores; (2) phase change from one...... state to another, also called moisture sorption; and (3) diffusion of bound water in wood tissue (in the cell wall). A mathematical model for predicting moisture transport in wood for a given condition must at least consider the dominating active processes simultaneously to be considered accurate...... of the three processes on the outcome of the coupled model. Least significant is the bound water diffusion. Based on the results from the sensitivity analyses, a simplified model for moisture transport in wood is proposed....

  5. Predicting the mechanical properties of brittle porous materials with various porosity and pore sizes.

    Science.gov (United States)

    Cui, Zhiwei; Huang, Yongmin; Liu, Honglai

    2017-07-01

    In this work, a micromechanical study using the lattice spring model (LSM) was performed to predict the mechanical properties of BPMs by simulation of the Brazilian test. Stress-strain curve and Weibull plot were analyzed for the determination of fracture strength and Weibull modulus. The presented model composed of linear elastic elements is capable of reproducing the non-linear behavior of BPMs resulting from the damage accumulation and provides consistent results which are in agreement with experimental measurements. Besides, it is also found that porosity shows significant impact on fracture strength while pore size dominates the Weibull modulus, which enables us to establish how choices made in the microstructure to meet the demand of brittle porous materials functioning in various operating conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. A study on improving mechanical properties of porous HA tissue engineering scaffolds by hot isostatic pressing

    International Nuclear Information System (INIS)

    Zhao Jing; Xiao Suguang; Lu Xiong; Wang Jianxin; Weng Jie

    2006-01-01

    Various interconnected porous hydroxyapatite (HA) ceramic scaffolds are universally used to induct the tissue growth for bone repair and replacement, and serve to support the adhesion, transfer, proliferation and differentiation of cells. Impregnation of polyurethane sponges with a ceramic slurry is adopted to produce highly porous HA ceramic scaffolds with a 3D interconnected structure. However, high porosity always accompanies a decrease in the strength of the HA ceramic scaffolds. Therefore, it is significant to improve the strength of the HA ceramic scaffolds with highly interconnected porosity so that they are more suitable in clinical applications. In this work, highly porous HA ceramic scaffolds are first produced by the polymer impregnation approach, and subsequently further sintered by hot isostatic pressing (HIP). The phase composition, macro- and micro-porous structure, sintering and mechanical properties of the porous HA scaffolds are investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation analysis and compressive test. The experimental results show that the nanohardness and compressive strength of HIP-sintered porous HA ceramics are higher than those of commonly sintered HA scaffolds. The HIP technique can effectively improve the sintering property and densification of porous HA ceramic scaffolds, so inducing an increase in the compression strength

  7. 3D printing of porous hydroxyapatite scaffolds intended for use in bone tissue engineering applications.

    Science.gov (United States)

    Cox, Sophie C; Thornby, John A; Gibbons, Gregory J; Williams, Mark A; Mallick, Kajal K

    2015-02-01

    A systematic characterisation of bone tissue scaffolds fabricated via 3D printing from hydroxyapatite (HA) and poly(vinyl)alcohol (PVOH) composite powders is presented. Flowability of HA:PVOH precursor materials was observed to affect mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The ultimate compressive strength of 55% porous green scaffolds printed along the Y-axis and dried in a vacuum oven for 6h was 0.88 ± 0.02 MPa. Critically, the pores of 3D printed constructs could be user designed, ensuring bulk interconnectivity, and the imperfect packing of powder particles created an inherent surface roughness and non-designed porosity within the scaffold. These features are considered promising since they are known to facilitate osteoconduction and osteointegration in-vivo. Characterisation techniques utilised in this study include two funnel flow tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), compressive strength testing and computed tomography (CT). Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Multi-walled carbon nanotube-reinforced porous iron oxide as a superior anode material for lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Xin-Jing; Zhang, Juan; Qi, Gong-Wei; Dai, Xiao-Hui; Zhou, Jun-Ping [School of Chemistry and Chemical Engineering, Shandong University, No. 27, Shanda Nan Rd., Jinan 250100 (China); Zhang, Shu-Yong, E-mail: syzhang@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, No. 27, Shanda Nan Rd., Jinan 250100 (China); National Key Lab of Crystal, Shandong University, No. 27, Shanda Nan Rd., Jinan 250100 (China)

    2015-08-15

    Highlights: • Electrochemical performance of Fe{sub 3}O{sub 4} is improved by combining different approaches. • Porous Cu substrate is used to enlarge surface area and improve conductivity. • MWCNT is used to reinforce the electrode structure and change morphology of Fe{sub 3}O{sub 4}. • Reversible capacity, capacity retention and high-rate performance are improved. - Abstract: Multi-walled carbon nanotube-reinforced porous iron oxide (Fe{sub 3}O{sub 4}/MWCNT) is synthesized by a two-step approach with porous Cu substrate serving as current collector. Porous Cu substrate is prepared through electroless deposition with hydrogen bubble serving as template. Fe{sub 3}O{sub 4}/MWCNT composites are prepared by the electrodeposition of Fe{sub 3}O{sub 4} in the presence of dispersed MWCNTs from a Fe{sub 2}(SO{sub 4}){sub 3} solution with MWCNT suspension. Results showed that Fe{sub 3}O{sub 4} forms granular nanoparticles on the porous Cu substrate with several MWCNTs embedded in it. Adding MWCNTs changes the morphology of Fe{sub 3}O{sub 4}. Smooth Fe{sub 3}O{sub 4}, smooth Fe{sub 3}O{sub 4}/MWCNT, and porous Fe{sub 3}O{sub 4} composites are also prepared for comparison. When used as anode materials, porous Fe{sub 3}O{sub 4}/MWCNT composites have a reversible capacity of approximately 601 mA h g{sup −1} at the 60th cycle at a cycling rate of 100 mA g{sup −1}. This value is higher than that of the other materials. The reversible capacity at a cycling rate of 10,000 mA g{sup −1} is approximately 50% of that at 100 mA g{sup −1}. Therefore, the MWCNT-reinforced porous Fe{sub 3}O{sub 4} composite exhibits much better reversible capacity, capacity retention, and high-rate performance than the other samples. This finding can be ascribed to the porous structure of Fe{sub 3}O{sub 4}, better conductivity of porous Cu substrate and MWCNTs, and the morphology change of Fe{sub 3}O{sub 4} nanoparticles upon the addition of MWCNTs.

  9. Matrix changes and side effects induced by electrokinetic treatment of porous and particulate materials

    DEFF Research Database (Denmark)

    Skibsted, Gry

    Transport of ions in an applied electric field holds many applications within both civil and environmental engineering, e.g. for removal of chlorides from concrete to hinder reinforcement corrosion, remediation of heavy metals from soils and other waste materials and recently for desalination...

  10. Amine Functionalized Porous Network

    KAUST Repository

    Eddaoudi, Mohamed; Guillerm, Vincent; Weselinski, Lukasz Jan; Alkordi, Mohamed H.; Mohideen, Mohamed Infas Haja; Belmabkhout, Youssef

    2015-01-01

    Amine groups can be introduced in porous materials by a direct (one pot) or post-synthetic modification (PSM) process on aldehyde groups, and the resulting porous materials have increased gas affinity.

  11. Amine Functionalized Porous Network

    KAUST Repository

    Eddaoudi, Mohamed

    2015-05-28

    Amine groups can be introduced in porous materials by a direct (one pot) or post-synthetic modification (PSM) process on aldehyde groups, and the resulting porous materials have increased gas affinity.

  12. Microdroplet engineering for microbioassay and synthesis of functional structured porous particles

    Science.gov (United States)

    Rastogi, Vinayak

    redistribution of magnetic nanoparticles in droplets containing mixtures of latex and magnetic particle suspensions. The redistribution is dictated by the pattern of magnetic field to which the droplet templates are introduced during drying. We developed new types of patchy magnetic particles that can find application in targeted drug delivery. The latex matrix can be infused with a drug and the magnetic patch(es) facilitate remote manipulation of the carrier. A new microfluidic chip was developed for the in-vitro characterization of drug/material release rate from the porous latex network in a live environment. The release rate of dye (drug simulant) from the porous supports is quantified and interpreted on the basis of diffusion/dissolution based mass transfer models. The technique has the potential to perform simultaneous screening of multiple samples and replace the conventional bulk laboratory setup needed for determining the release profiles in drug development process.

  13. Preparation of 3D fibroin/chitosan blend porous scaffold for tissue engineering via a simplified method.

    Science.gov (United States)

    Ruan, Yuhui; Lin, Hong; Yao, Jinrong; Chen, Zhengrong; Shao, Zhengzhong

    2011-03-10

    In this work, we developed a simple and flexible method to manufacture a 3D porous scaffold based on the blend of regenerated silk fibroin (RSF) and chitosan (CS). No crosslinker or other toxic reagents were used in this method. The pores of resulted 3D scaffolds were connected with each other, and their sizes could be easily controlled by the concentration of the mixed solution. Compared with pure RSF scaffolds, the water absorptivities of these RSF/CS blend scaffolds with significantly enhanced mechanical properties were greatly increased. The results of MTT and RT-PCR tests indicated that the chondrocytes grew very well in these blend RSF/CS porous scaffolds. This suggested that the RSF/CS blend scaffold prepared by this new method could be a promising candidate for applications in tissue engineering. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Modeling the transport of engineered nanoparticles in saturated porous media - an experimental setup

    Science.gov (United States)

    Braun, A.; Neukum, C.; Azzam, R.

    2011-12-01

    The accelerating production and application of engineered nanoparticles is causing concerns regarding their release and fate in the environment. For assessing the risk that is posed to drinking water resources it is important to understand the transport and retention mechanisms of engineered nanoparticles in soil and groundwater. In this study an experimental setup for analyzing the mobility of silver and titanium dioxide nanoparticles in saturated porous media is presented. Batch and column experiments with glass beads and two different soils as matrices are carried out under varied conditions to study the impact of electrolyte concentration and pore water velocities. The analysis of nanoparticles implies several challenges, such as the detection and characterization and the preparation of a well dispersed sample with defined properties, as nanoparticles tend to form agglomerates when suspended in an aqueous medium. The analytical part of the experiments is mainly undertaken with Flow Field-Flow Fractionation (FlFFF). This chromatography like technique separates a particulate sample according to size. It is coupled to a UV/Vis and a light scattering detector for analyzing concentration and size distribution of the sample. The advantage of this technique is the ability to analyze also complex environmental samples, such as the effluent of column experiments including soil components, and the gentle sample treatment. For optimization of the sample preparation and for getting a first idea of the aggregation behavior in soil solutions, in sedimentation experiments the effect of ionic strength, sample concentration and addition of a surfactant on particle or aggregate size and temporal dispersion stability was investigated. In general the samples are more stable the lower the concentration of particles is. For TiO2 nanoparticles, the addition of a surfactant yielded the most stable samples with smallest aggregate sizes. Furthermore the suspension stability is

  15. [Strategies to choose scaffold materials for tissue engineering].

    Science.gov (United States)

    Gao, Qingdong; Zhu, Xulong; Xiang, Junxi; Lü, Yi; Li, Jianhui

    2016-02-01

    Current therapies of organ failure or a wide range of tissue defect are often not ideal. Transplantation is the only effective way for long time survival. But it is hard to meet huge patients demands because of donor shortage, immune rejection and other problems. Tissue engineering could be a potential option. Choosing a suitable scaffold material is an essential part of it. According to different sources, tissue engineering scaffold materials could be divided into three types which are natural and its modified materials, artificial and composite ones. The purpose of tissue engineering scaffold is to repair the tissues or organs damage, so could reach the ideal recovery in its function and structure aspect. Therefore, tissue engineering scaffold should even be as close as much to the original tissue or organs in function and structure. We call it "organic scaffold" and this strategy might be the drastic perfect substitute for the tissues or organs in concern. Optimized organization with each kind scaffold materials could make up for biomimetic structure and function of the tissue or organs. Scaffold material surface modification, optimized preparation procedure and cytosine sustained-release microsphere addition should be considered together. This strategy is expected to open new perspectives for tissue engineering. Multidisciplinary approach including material science, molecular biology, and engineering might find the most ideal tissue engineering scaffold. Using the strategy of drawing on each other strength and optimized organization with each kind scaffold material to prepare a multifunctional biomimetic tissue engineering scaffold might be a good method for choosing tissue engineering scaffold materials. Our research group had differentiated bone marrow mesenchymal stem cells into bile canaliculi like cells. We prepared poly(L-lactic acid)/poly(ε-caprolactone) biliary stent. The scaffold's internal played a part in the long-term release of cytokines which

  16. Novel hierarchically porous carbon materials obtained from natural biopolymer as host matrixes for lithium-sulfur battery applications.

    Science.gov (United States)

    Zhang, Bin; Xiao, Min; Wang, Shuanjin; Han, Dongmei; Song, Shuqin; Chen, Guohua; Meng, Yuezhong

    2014-08-13

    Novel hierarchically porous carbon materials with very high surface areas, large pore volumes and high electron conductivities were prepared from silk cocoon by carbonization with KOH activation. The prepared novel porous carbon-encapsulated sulfur composites were fabricated by a simple melting process and used as cathodes for lithium sulfur batteries. Because of the large surface area and hierarchically porous structure of the carbon material, soluble polysulfide intermediates can be trapped within the cathode and the volume expansion can be alleviated effectively. Moreover, the electron transport properties of the carbon materials can provide an electron conductive network and promote the utilization rate of sulfur in cathode. The prepared carbon-sulfur composite exhibited a high specific capacity and excellent cycle stability. The results show a high initial discharge capacity of 1443 mAh g(-1) and retain 804 mAh g(-1) after 80 discharge/charge cycles at a rate of 0.5 C. A Coulombic efficiency retained up to 92% after 80 cycles. The prepared hierarchically porous carbon materials were proven to be an effective host matrix for sulfur encapsulation to improve the sulfur utilization rate and restrain the dissolution of polysulfides into lithium-sulfur battery electrolytes.

  17. Hierarchical porous carbon materials prepared using nano-ZnO as a template and activation agent for ultrahigh power supercapacitors.

    Science.gov (United States)

    Wang, Haoran; Yu, Shukai; Xu, Bin

    2016-09-20

    Hierarchical porous carbon materials with high surface areas and a localized graphitic structure were simply prepared from sucrose using nano-ZnO as a hard template, activation agent and graphitization catalyst simultaneously, which exhibit an outstanding high-rate performance and can endure an ultrafast scan rate of 20 V s -1 and ultrahigh current density of 1000 A g -1 .

  18. Influence of ferrocyanide inhibitors on the transport and crystrallization processes of sodium chloride in porous building materials

    NARCIS (Netherlands)

    Gupta, S.; Terheiden, K.H; Pel, L.; Sawdy - Heritage, A.M.

    2012-01-01

    Salt weathering leads to destruction of many valuable cultural heritage monuments and porous building materials. In order to reduce the impact of this, effective treatment methods are required. The use of crystallization inhibitors to mitigate salt damage has been proposed in the past; however, to

  19. The enhanced local pressure model for the accurate analysis of fluid pressure driven fracture in porous materials

    NARCIS (Netherlands)

    Remij, E.W.; Remmers, J.J.C.; Huyghe, J.M.R.J.; Smeulders, D.M.J.

    2015-01-01

    In this paper, we present an enhanced local pressure model for modelling fluid pressure driven fractures in porous saturated materials. Using the partition-of-unity property of finite element shape functions, we describe the displacement and pressure fields across the fracture as a strong

  20. A gravitational procedure to measure the diffusion coefficient of mater in porous materials : a case study on concrete

    NARCIS (Netherlands)

    Zanden, van der A.J.J.; Taher, A.

    2014-01-01

    A new procedure is presented with which the diffusion coefficient of water in partially saturated porous materials can be measured. The first step in the procedure is the creation of a non-equilibrium situation inside a sample by placing it into a centrifuge. In the second step, the mass of the

  1. Effective Chemical Route to 2D Nanostructured Silicon Electrode Material: Phase Transition from Exfoliated Clay Nanosheet to Porous Si Nanoplate

    International Nuclear Information System (INIS)

    Adpakpang, Kanyaporn; Patil, Sharad B.; Oh, Seung Mi; Kang, Joo-Hee; Lacroix, Marc; Hwang, Seong-Ju

    2016-01-01

    Graphical abstract: Effective morphological control of porous silicon 2D nanoplate can be achieved by the magnesiothermically-induced phase transition of exfoliated silicate clay nanosheets. The promising lithium storage performance of the obtained silicon materials with huge capacity and excellent rate characteristics underscores the prime importance of porously 2D nanostructured morphology of silicon. - Highlights: • 2D nanostructured silicon electrode materials are successfully synthesized via the magnesiothermically-induced phase transition of exfoliated clay 2D nanosheets. • High discharge capacity and rate capability are achieved from the 2D nanoplates of silicon. • Silicon 2D nanoplates can enhance both Li"+ diffusion and charge-transfer kinetics. • 2D nanostructured silicon is beneficial for the cycling stability by minimizing the volume change during lithiation-delithiation. - Abstract: An efficient and economical route for the synthesis of porous two-dimensional (2D) nanoplates of silicon is developed via the magnesiothermically-induced phase transition of exfoliated clay 2D nanosheets. The magnesiothermic reaction of precursor clay nanosheets prepared by the exfoliation and restacking with Mg"2"+ cations yields porous 2D nanoplates of elemental silicon. The variation in the Mg:SiO_2 ratio has a significant effect on the porosity and connectivity of silicon nanoplates. The porous silicon nanoplates show a high discharge capacity of 2000 mAh g"−"1 after 50 cycles. Of prime importance is that this electrode material still retains a large discharge capacity at higher C-rates, which is unusual for the elemental silicon electrode. This is mainly attributed to the improved diffusion of lithium ions, charge-transfer kinetics, and the preservation of the electrical connection of the porous 2D plate-shaped morphology. This study highlights the usefulness of clay mineral as an economical and scalable precursor of high-performance silicon electrodes with

  2. MINIMUM SOLID AREA MODELS FOR THE EFFECTIVE PROPERTIES OF POROUS MATERIALS - A REFUTATION

    Directory of Open Access Journals (Sweden)

    Willi Pabst

    2015-09-01

    Full Text Available Minimum solid area (MSA models are popular models for the calculation of the effective properties of porous materials and are frequently used to justify the use of a simple exponential relation for fitting purposes. In this contribution it is shown that MSA models, and the simple exponentials they support, are misleading and should be avoided. In particular, taking Young modulus and conductivity (thermal or electrical as examples, it is shown that MSA models are based on the unjustified (and unjustifiable hypothesis that the relative Young modulus and relative conductivity are identical, and moreover equal to the MSA fraction itself. This claim is generally false for isotropic materials, both random or periodic. Although indeed a very specific case exists in which this claim is true for the properties in one specific direction (viz., extremely anisotropic materials with translational invariance, in this specific case MSA models are redundant, because the relative properties are given exactly by the volume- or area-weighted arithmetic mean. It is shown that the mere existence of non-trivial cross-property relations is incompatible with the existence of MSA models. Finally, it is shown by numerical (finite-element modeling that MSA models provide incorrect results even in the simplest of the cases for which they were originally designed, i.e. for simple cubic packings of partially sintered isometric (initially spherical grains. Therefore, paraphrasing Box, MSA models are not only wrong, but also useless, and should be abandoned.

  3. Manganese Dioxide Supported on Porous Biomorphic Carbons as Hybrid Materials for Energy Storage Devices.

    Science.gov (United States)

    Gutierrez-Pardo, Antonio; Lacroix, Bertrand; Martinez-Fernandez, Julian; Ramirez-Rico, Joaquin

    2016-11-16

    A facile and low-cost method has been employed to fabricate MnO 2 /C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO 2 nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO 2 nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO 2 content and crystallite size via the concentration of KMnO 4 used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g -1 in electrodes containing 3 wt % MnO 2 with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.

  4. Graphene-Like 2D Porous Carbon Nanosheets Derived from Cornstalk Pith for Energy Storage Materials

    Science.gov (United States)

    Gao, Kezheng; Niu, Qingyuan; Tang, Qiheng; Guo, Yaqing; Wang, Lizhen

    2018-01-01

    Biomass materials from different organisms or different parts (even different periods) of the same organism have different microscopic morphologies, hierarchical pore structures and even elemental compositions. Therefore, carbon materials inheriting the unique hierarchical microstructure of different biomass materials may exhibit significantly different electrochemical properties. Cornstalk pith and cornstalk skin (dried by freeze-drying) exhibit significantly different microstructures due to their different biological functions. The cornstalk skin-based carbon (S-carbon) exhibits a thick planar morphology, and the Barrett-Emmett-Teller (BET) surface area is only about 332.07 m2 g-1. However, cornstalk pith-based carbon (P-carbon) exhibits a graphene-like 2D porous nanosheet structure with a rough, wrinkled morphology, and the BET surface area is about 805.17 m2 g-1. In addition, a P-carbon supercapacitor exhibits much higher specific capacitance and much better rate capability than an S-carbon supercapacitor in 6 M potassium hydroxide (KOH) electrolyte.

  5. The potential of biobased materials in the civil engineering sector

    NARCIS (Netherlands)

    Venema, Anne

    2012-01-01

    SUMMARY Large quantities of materials are used in the Dutch civil engineering sector every year. Many of these materials have a significant impact on the environment because these materials are based on non-renewable resources and the production is often

  6. Engineering solutions for sustainability materials and resources II

    CERN Document Server

    Mishra, Brajendra; Anderson, Dayan; Sarver, Emily; Neelameggham, Neale

    2016-01-01

    With impending and burgeoning societal issues affecting both developed and emerging nations, the global engineering community has a responsibility and an opportunity to truly make a difference and contribute. The papers in this collection address what materials and resources are integral to meeting basic societal sustainability needs in critical areas of energy, transportation, housing, and recycling. Contributions focus on the engineering answers for cost-effective, sustainable pathways; the strategies for effective use of engineering solutions; and the role of the global engineering community. Authors share perspectives on the major engineering challenges that face our world today; identify, discuss, and prioritize engineering solution needs; and establish how these fit into developing global-demand pressures for materials and human resources.

  7. Meso-scale modelling of the heat conductivity effect on the shock response of a porous material

    Science.gov (United States)

    Resnyansky, A. D.

    2017-06-01

    Understanding of deformation mechanisms of porous materials under shock compression is important for tailoring material properties at the shock manufacturing of advanced materials from substrate powders and for studying the response of porous materials under shock loading. Numerical set-up of the present work considers a set of solid particles separated by air representing a volume of porous material. Condensed material in the meso-scale set-up is simulated with a viscoelastic rate sensitive material model with heat conduction formulated from the principles of irreversible thermodynamics. The model is implemented in the CTH shock physics code. The meso-scale CTH simulation of the shock loading of the representative volume reveals the mechanism of pore collapse and shows in detail the transition from a high porosity case typical for abnormal Hugoniot response to a moderate porosity case typical for conventional Hugoniot response. Results of the analysis agree with previous analytical considerations and support hypotheses used in the two-phase approach.

  8. Porous chromatographic materials as substrates for preparing synthetic nuclear explosion debris particles

    International Nuclear Information System (INIS)

    Harvey, S.D.; Carman, A.J.; Martin Liezers; Antolick, K.C.; Garcia, B.J.; Eiden, G.C.; Sweet, L.E.

    2013-01-01

    Several porous chromatographic materials were investigated as synthetic substrates for preparing surrogate nuclear explosion debris particles. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110 deg C) to drive off water, and then treating them at high temperatures (up to 800 deg C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies characterized material balance and the formation of recalcitrant species. Metal loading was 1.5-3 times higher than expected from the pore volume alone, a result attributed to surface coating. Most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating selective loading. High-temperature treatments caused reduced solubility of several metals, and the loss of some volatile species (rhenium and tellurium). Sample preparation reproducibility was high (the inter- and intra-batch relative standard deviations were 7.8 and 0.84 %, respectively) indicating suitability for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex nuclear explosion debris forms (e.g., Trinitite). (author)

  9. Design and fabrication of porous biodegradable scaffolds: a strategy for tissue engineering.

    Science.gov (United States)

    Raeisdasteh Hokmabad, Vahideh; Davaran, Soodabeh; Ramazani, Ali; Salehi, Roya

    2017-11-01

    Current strategies of tissue engineering are focused on the reconstruction and regeneration of damaged or deformed tissues by grafting of cells with scaffolds and biomolecules. Recently, much interest is given to scaffolds which are based on mimic the extracellular matrix that have induced the formation of new tissues. To return functionality of the organ, the presence of a scaffold is essential as a matrix for cell colonization, migration, growth, differentiation and extracellular matrix deposition, until the tissues are totally restored or regenerated. A wide variety of approaches has been developed either in scaffold materials and production procedures or cell sources and cultivation techniques to regenerate the tissues/organs in tissue engineering applications. This study has been conducted to present an overview of the different scaffold fabrication techniques such as solvent casting and particulate leaching, electrospinning, emulsion freeze-drying, thermally induced phase separation, melt molding and rapid prototyping with their properties, limitations, theoretical principles and their prospective in tailoring appropriate micro-nanostructures for tissue regeneration applications. This review also includes discussion on recent works done in the field of tissue engineering.

  10. Assembly of core–shell structured porous carbon–graphene composites as anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Guo, Rong; Zhao, Li; Yue, Wenbo

    2015-01-01

    As potential anode materials for lithium-ion batteries, mesoporous carbons such as CMK-3 and CMK-8 usually show stable cycling performances but only slightly higher reversible capacities than commercial graphite. Graphene has much higher theoretical capacity than that of graphite in theory. However, its electrochemical behavior is not as good as expected due to the aggregation of graphene nanosheets. Herein we describe a novel strategy for the preparation of core–shell structured porous carbon–graphene composites. Compared to pure porous carbons or pure graphene nanosheets, these novel composites exhibit superior electrochemical performances including higher reversible capacities and better cycle/rate performances. This core–shell structure can avoid the aggregation of graphene nanosheets as well as may stabilize the mesostructure of porous carbon, which is beneficial to improving the electrochemical performances of the composites

  11. Electrospun Nanofibrous Materials for Neural Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Yee-Shuan Lee

    2011-02-01

    Full Text Available The use of biomaterials processed by the electrospinning technique has gained considerable interest for neural tissue engineering applications. The tissue engineering strategy is to facilitate the regrowth of nerves by combining an appropriate cell type with the electrospun scaffold. Electrospinning can generate fibrous meshes having fiber diameter dimensions at the nanoscale and these fibers can be nonwoven or oriented to facilitate neurite extension via contact guidance. This article reviews studies evaluating the effect of the scaffold’s architectural features such as fiber diameter and orientation on neural cell function and neurite extension. Electrospun meshes made of natural polymers, proteins and compositions having electrical activity in order to enhance neural cell function are also discussed.

  12. Materials to Engineer the Immune System

    Science.gov (United States)

    2011-04-01

    alone (Lysate), or with GM-CSF and lysate (GM+Lys), and 14 days later 200,000 NT1 cells were injected into the mammary pad. Mice survival was...followed over time. Fig. 2. Therapeutic vaccination against NT1 transplantable tumors. NT1 cells (200,000) were injected into the mammary...Engineer the Immune System David Mooney Harvard College Cambridge, MA 02136 Dendritic cells , GM-CSF, CpG, poly(lactide-co-glycolide) The

  13. Integrated Computational Material Engineering Technologies for Additive Manufacturing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — QuesTek Innovations, a pioneer in Integrated Computational Materials Engineering (ICME) and a Tibbetts Award recipient, is teaming with University of Pittsburgh,...

  14. A multi-scale homogenization model for fine-grained porous viscoplastic polycrystals: II - Applications to FCC and HCP materials

    Science.gov (United States)

    Song, Dawei; Ponte Castañeda, P.

    2018-06-01

    In Part I of this work (Song and Ponte Castañeda, 2018a), a new homogenization model was developed for the macroscopic behavior of three-scale porous polycrystals consisting of random distributions of large pores in a fine-grained polycrystalline matrix. In this second part, the model is used to investigate both the instantaneous effective behavior and the finite-strain macroscopic response of porous FCC and HCP polycrystals for axisymmetric loading conditions. The stress triaxiality and Lode parameter are found to have significant effects on the evolution of the substructure, which in turn have important implications for the overall hardening/softening behavior of the porous polycrystal. The intrinsic effect of the texture evolution of the polycrystalline matrix is inferred by appropriate comparisons with corresponding results for porous isotropic materials, and found to be significant, especially at low triaxialities. In particular, the predictions of the model identify, for the first time, two disparate regimes for the macroscopic response of porous polycrystals: a porosity-controlled regime at high triaxialities, and a texture-controlled regime at low triaxialities. The transition between these two regimes is found to be quite sharp, taking place between triaxialities of 1 and 2.

  15. Influence of corn flour as pore forming agent on porous ceramic material based mullite: Morphology and mechanical properties

    Directory of Open Access Journals (Sweden)

    Ayala-Landeros J.G.

    2016-01-01

    Full Text Available Porous material was processed by the mixing, molding and pressing the ceramic material, afterward burnout and sintering; through the forming porous, using corn flour at different concentration (10, 15 and 20 wt.% as a pore forming agent; in order to determinate the influence of porous on the mechanical, morphological and structural properties. The effect of the volume fraction of corn flour in the mullite matrix, at various sintering temperature from 1100, 1200, 1300 and 1500°C were tested by Diffraction X ray, showing changes in crystalline phases of mullite (3Al2O3-2SiO2, as result of sintered temperatures. Presence of talcum powder in formula, also cause the formation of the cordierite and cristobalite crystalline phases, giving stability and adhesion to the structure of ceramic material. When sintering at temperatures between 1300 to 1500°C, and it was used the concentration of corn flour 15-20 wt.% as forming agent porous, it was found the better mechanical properties. The scanning electron microscopy analysis shows the presence of open porosity and anisotropy.

  16. Mechanics of materials formulas and problems : engineering mechanics 2

    CERN Document Server

    Gross, Dietmar; Wriggers, Peter; Schröder, Jörg; Müller, Ralf

    2017-01-01

    This book contains the most important formulas and more than 140 completely solved problems from Mechanics of Materials and Hydrostatics. It provides engineering students material to improve their skills and helps to gain experience in solving engineering problems. Particular emphasis is placed on finding the solution path and formulating the basic equations. Topics include: - Stress - Strain - Hooke’s Law - Tension and Compression in Bars - Bending of Beams - Torsion - Energy Methods - Buckling of Bars - Hydrostatics .

  17. Classroom Demonstrations in Materials Science/Engineering.

    Science.gov (United States)

    Hirschhorn, J. S.; And Others

    Examples are given of demonstrations used at the University of Wisconsin in a materials science course for nontechnical students. Topics include crystal models, thermal properties, light, and corrosion. (MLH)

  18. Updated candidate list for engineered barrier materials

    International Nuclear Information System (INIS)

    McCright, R.D.

    1995-10-01

    This report describes candidate materials to be evaluated over the next several years during advanced design phases for the waste package to be used for the underground disposal of high-level radioactive wastes at the Yucca Mountain facility

  19. SMART MATERIALS AS MODERN ENGINEERING SUBSTANCES

    Directory of Open Access Journals (Sweden)

    Adam Ćwikła

    2013-03-01

    Full Text Available The article presents the type and use of intelligent materials in aviation and medicine. Their basic features and properties have been discussed. Moreover, the authors quote examples of different uses of intelligent materials, both the existing ones and those in design and development stages. Their use is claimed to be increasing the efficiency and reliability of processes and equipment as well as facilitates the development of new mechanisms.

  20. Bimetallic Porous Iron (pFe) Materials for Remediation/Removal of Tc from Aqueous Systems

    Energy Technology Data Exchange (ETDEWEB)

    Li, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-29

    Remediation of Tc remains an unresolved challenge at SRS and other DOE sites. The objective of this project was to develop novel bimetallic porous iron (pFe) materials for Tc removal from aqueous systems. We showed that the pFe is much more effective in removing TcO4 - (×30) and ReO4 - (×8) from artificial groundwater than granular iron. Tc K-edge XANES spectroscopy indicated that Tc speciation on the pFe was 18% adsorbed TcO4 -, 28% Tc(IV) in Tc dioxide and 54% Tc(IV) into the structure of Fe hydroxide. A variety of catalytic metal nanoparticles (i.e., Ni, Cu, Zn, Ag, Sn and Pd) were successfully deposited on the pFe using scalable chemical reduction methods. The Zn-pFe was outstanding among the six bimetallic pFe materials, with a capacity increase of >100% for TcO4 - removal and of 50% for ReO4 - removal, compared to the pFe. These results provide a highly applicable platform for solving critical DOE and industrial needs related to nuclear environmental stewardship and nuclear power production.

  1. The study of CO2 absorption intensification using porous media material in aqueous AMP solution

    Directory of Open Access Journals (Sweden)

    Min Xiao

    2018-03-01

    Full Text Available In this work, the performance of CO2 absorption into aqueous 2-amino-2-methyl-propanol (AMP solution was investigated by measuring the amount of CO2 in the liquid phase during CO2 absorption process to identify initial CO2 absorption rate. Then, the porous media material named as MCM41 was introduced into the amine solution to test its influence on CO2 absorption. It was found that MCM41 increased initial CO2 absorption rate and enhanced CO2 absorption process. The physico-chemical properties of MCM41 were characterized in terms of specific surface area, average pore diameter, total pore volume and chemical properties, the amount of acidic sites and the Brϕnsted/Lewis (B/L acid sites ratio. Results showed that MCM41 was a type of Lewis acid catalyst with large specific surface area and pore volume. In addition, the pKa of AMP solution with and without MCM41 was obtained using acid titration technology to help understand the effect brought by MCM41. A mechanism illustrating how MCM41 increases the CO2 absorption rate of the AMP solution was proposed and demonstrated that MCM41 is a potential material for enhancing CO2 absorption.

  2. Porous Structures in Stacked, Crumpled and Pillared Graphene-Based 3D Materials.

    Science.gov (United States)

    Guo, Fei; Creighton, Megan; Chen, Yantao; Hurt, Robert; Külaots, Indrek

    2014-01-01

    Graphene, an atomically thin material with the theoretical surface area of 2600 m 2 g -1 , has great potential in the fields of catalysis, separation, and gas storage if properly assembled into functional 3D materials at large scale. In ideal non-interacting ensembles of non-porous multilayer graphene plates, the surface area can be adequately estimated using the simple geometric law ~ 2600 m 2 g -1 /N, where N is the number of graphene sheets per plate. Some processing operations, however, lead to secondary plate-plate stacking, folding, crumpling or pillaring, which give rise to more complex structures. Here we show that bulk samples of multilayer graphene plates stack in an irregular fashion that preserves the 2600/N surface area and creates regular slot-like pores with sizes that are multiples of the unit plate thickness. In contrast, graphene oxide deposits into films with massive area loss (2600 to 40 m 2 g -1 ) due to nearly perfect alignment and stacking during the drying process. Pillaring graphene oxide sheets by co-deposition of colloidal-phase particle-based spacers has the potential to partially restore the large monolayer surface. Surface areas as high as 1000 m 2 g -1 are demonstrated here through colloidal-phase deposition of graphene oxide with water-dispersible aryl-sulfonated ultrafine carbon black as a pillaring agent.

  3. A mesomechanical analysis of the deformation and fracture in polycrystalline materials with ceramic porous coatings

    Science.gov (United States)

    Balokhonov, R. R.; Zinoviev, A. V.; Romanova, V. A.; Batukhtina, E. E.

    2015-10-01

    The special features inherent in the mesoscale mechanical behavior of a porous ceramic coating-steel substrate composite are investigated. Microstructure of the coated material is accounted for explicitly as initial conditions of a plane strain dynamic boundary-value problem solved by the finite difference method. Using a mechanical analogy method, a procedure for generating a uniform curvilinear finite difference computational mesh is developed to provide a more accurate description of the complex grain boundary geometry. A modified algorithm for generation of polycrystalline microstructure of the substrate is designed on the basis of the cellular automata method. The constitutive equations for a steel matrix incorporate an elastic-plastic model for a material subjected to isotropic hardening. The Hall-Petch relation is used to account for the effect of the grain size on the yield stress and strain hardening history. A brittle fracture model for a ceramic coating relying on the Huber criterion is employed. The model allows for crack nucleation in the regions of triaxial tension. The complex inhomogeneous stress and plastic strain patterns are shown to be due to the presence of interfaces of three types: coating-substrate interface, grain boundaries, and pore surfaces.

  4. Measurement of the resistivity of porous materials with an alternating air-flow method.

    Science.gov (United States)

    Dragonetti, Raffaele; Ianniello, Carmine; Romano, Rosario A

    2011-02-01

    Air-flow resistivity is a main parameter governing the acoustic behavior of porous materials for sound absorption. The international standard ISO 9053 specifies two different methods to measure the air-flow resistivity, namely a steady-state air-flow method and an alternating air-flow method. The latter is realized by the measurement of the sound pressure at 2 Hz in a small rigid volume closed partially by the test sample. This cavity is excited with a known volume-velocity sound source implemented often with a motor-driven piston oscillating with prescribed area and displacement magnitude. Measurements at 2 Hz require special instrumentation and care. The authors suggest an alternating air-flow method based on the ratio of sound pressures measured at frequencies higher than 2 Hz inside two cavities coupled through a conventional loudspeaker. The basic method showed that the imaginary part of the sound pressure ratio is useful for the evaluation of the air-flow resistance. Criteria are discussed about the choice of a frequency range suitable to perform simplified calculations with respect to the basic method. These criteria depend on the sample thickness, its nonacoustic parameters, and the measurement apparatus as well. The proposed measurement method was tested successfully with various types of acoustic materials.

  5. Molecular Engineering of dosimetric materials; Ingenieria Molecular de materiales dosimetricos

    Energy Technology Data Exchange (ETDEWEB)

    Salas, P.; Castano, V.M. [Instituto de Fisica, UNAM, A.P. 1-1010, Queretaro (Mexico); Mendoza, D.; Gonzalez, P. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027 Mexico D.F. (Mexico)

    1999-07-01

    It was studied the thermoluminescent response to the gamma radiation of a new family of solid materials of zircon-silica. In this study some materials have been prepared by the sol-gel method with different stoichiometric relations, finding that it is possible to control, at least, partially, the thermoluminescent behavior starting from the Molecular Engineering of those materials, since the mixture of both ceramics allows to produce materials with different spatial structures. (Author)

  6. Effects of Temperature, Oxygen Partial Pressure, and Materials Selection on Slag Infiltration into Porous Refractories for Entrained-Flow Gasifiers

    Science.gov (United States)

    Kaneko, Tetsuya Kenneth

    The penetration rate of molten mineral contents (slag) from spent carbonaceous feedstock into porous ceramic-oxide refractory linings is a critical parameter in determining the lifecycle of integrated gasification combined cycle energy production plants. Refractory linings that withstand longer operation without interruption are desirable because they can mitigate consumable and maintenance costs. Although refractory degradation has been extensively studied for many other high-temperature industrial processes, this work focuses on the mechanisms that are unique to entrained-flow gasification systems. The use of unique feedstock mixtures, temperatures from 1450 °C to 1600 °C, and oxygen partial pressures from 10-7 atm to 10-9 atm pose engineering challenges in designing an optimal refractory material. Experimentation, characterization, and modeling show that gasifier slag infiltration into porous refractory is determined by interactions between the slag and the refractory that either form a physical barrier that impedes fluid flow or induce an increased fluid viscosity that decelerates the velocity of the fluid body. The viscosity of the slag is modified by the thermal profile of the refractory along the penetration direction as well as reactions between the slag and refractory that alter the chemistry, and thereby the thermo-physical properties of the fluid. Infiltration experiments reveal that the temperature gradient inherently present along the refractory lining limits penetration. A refractory in near-isothermal conditions demonstrates deeper slag penetration as compared to one that experiences a steeper thermal profile. The decrease in the local temperatures of the slag as it travels deeper into the refractory increases the viscosity of the fluid, which in turn slows the infiltration velocity of fluid body into the pores of the refractory microstructure. With feedstock mixtures that exhibit high iron-oxide concentrations, a transition-metal-oxide, the oxygen

  7. Fabrication and Characterization of Collagen-Immobilized Porous PHBV/HA Nano composite Scaffolds for Bone Tissue Engineering

    International Nuclear Information System (INIS)

    Jin-Young, B.; Zhi-Cai, X.; Giseop, K.; Keun-Byoung, Y.; Soo-Young, P.; Lee, S.P.; Inn-Kyu, K.

    2012-01-01

    The porous composite scaffolds (PHBV/HA) consisting of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and hydroxyapatite (HA) were fabricated using a hot-press machine and salt-leaching. Collagen (type I) was then immobilized on the surface of the porous PHBV/HA composite scaffolds to improve tissue compatibility. The structure and morphology of the collagen-immobilized composite scaffolds (PHBV/HA/Col) were investigated using a scanning electron microscope (SEM), Fourier transform infrared (FTIR), and electron spectroscopy for chemical analysis (ESCA). The potential of the porous PHBV/HA/Col composite scaffolds for use as a bone scaffold was assessed by an experiment with osteoblast cells (MC3T3-E1) in terms of cell adhesion, proliferation, and differentiation. The results showed that the PHBV/HA/Col composite scaffolds possess better cell adhesion and significantly higher proliferation and differentiation than the PHBV/HA composite scaffolds and the PHBV scaffolds. These results suggest that the PHBV/HA/Col composite scaffolds have a high potential for use in the field of bone regeneration and tissue engineering.

  8. THE USE OF A NOVEL ALDEHYDE-FUNCTIONALIZED CHITOSAN HYDROGEL TO PREPARE POROUS TUBULAR SCAFFOLDS FOR VASCULAR TISSUE ENGINEERING APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Eduardo P. Azevedo

    Full Text Available In this work, porous tubular scaffolds were prepared from a novel water soluble aldehyde-functionalized chitosan (ALDCHIT hydrogel, which was obtained by dissolving this chitosan derivative in water and using oxidized dextrose (OXDEXT as the crosslinking agent at different ALDCHIT:OXDEXT mole ratios (10:1, 10:2 and 10:4. By increasing the amount of OXDEXT in respect to ALDCHIT the hydrogels became more rigid and could absorb more than 200% of its weight in water. Since the ALDCHIT:OXDEXT 10:4 was the most stable hydrogel, its ability to form porous tubular scaffolds was investigated. The tubular scaffolds were prepared by the lyophilization method, where the orientation of the pores was controlled by exposing either the internal or the external surface of the frozen hydrogel during the sublimation step. When only the inner surface of the frozen hydrogel was exposed, tubular scaffolds with a highly porous lumen and a sealed outer surface were obtained, where the orientation of the pores, their sizes and interconnectivity seem to be optimum for vascular tissue engineering application.

  9. Porous Chromatographic Materials as Substrates for Preparing Synthetic Nuclear Explosion Debris Particles

    International Nuclear Information System (INIS)

    Harvey, Scott D.; Liezers, Martin; Antolick, Kathryn C.; Garcia, Ben J.; Sweet, Lucas E.; Carman, April J.; Eiden, Gregory C.

    2013-01-01

    In this study, we investigated several porous chromatographic materials as synthetic substrates for preparing surrogate nuclear explosion debris particles. The resulting synthetic debris materials are of interest for use in developing analytical methods. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110°C) to drive off water, and then treating them at high temperatures (up to 800°C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies were applied to characterize solubility, material balance, and formation of recalcitrant species. Dissolution experiments indicated loading was 1.5 to 3 times higher than expected from the pore volume alone, a result attributed to surface coating. Analysis of load solutions before and after filling the material pores revealed that most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating some metals were selectively loaded. High-temperature treatments caused reduced solubility of several metal species, and loss of some metals (rhenium and tellurium) because volatile species were formed. Sample preparation reproducibility was high (the inter-batch relative standard deviation was 7.8%, and the intra-batch relative standard deviation was 0.84%) indicating that this material is suitable for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in

  10. General and special engineering materials science. Vol. 3

    International Nuclear Information System (INIS)

    Ondracek, G.; Hofmann, P.

    1983-04-01

    The report about general and special engineering materials science is the result of lectures given by the authors in two terms in 1982 at Instituto Balseiro, San Carlos de Bariloche, the graduated college of the Universidad de Cuyo and Comision Nacional de Energia Atomica, Republica Argentina. These lectures were organised in the frame of the project ''nuclear engineering'' (ARG/78/020) of the United Nations Development Program (UNDP) by the International Atomic Energy Agency (IAEA). Some chapters of the report are written in English, others in Spanish. The report is subdivided into three volumes. The present volume III concerns special engineering materials science and considers nuclear materials with respect to off-normal (''accident'') reactor operation conditions including nuclear materials in loss-of-coolant accident and nuclear materials in core melt accidents. (orig./IHOE) [de

  11. General and special engineering materials science. Vol. 2

    International Nuclear Information System (INIS)

    Anderko, K.; Kummerer, K.R.; Ondracek, G.

    1983-04-01

    The present report about general and special engineering materials science is the result of lectures given by the authors in two terms in 1982 at Instituto Balseiro, San Carlos de Bariloche, the graduated college of the Universidad de Cuyo and Comision Nacional de Energia Atomica, Republica Argentina. These lectures were organised in the frame of the project ''nuclear engineering'' (ARG/78/020) of the United Nations Development Program (UNDP) by the International Atomic Energy Agency (IAEA). Some chapters of the report are written in English, others in Spanish. The report is subdivided into three volumes. The present volume II concerns special engineering materials science with respect to nuclear materials under normal reactor operation conditions including 1. reactor clad and structural materials, 2. nuclear fuels and fuel elements, 3. nuclear waste as a materials viewpoint. (orig./IHOE) [de

  12. Ice crystallization in porous building materials: assessing damage using real-time 3D monitoring

    Science.gov (United States)

    Deprez, Maxim; De Kock, Tim; De Schutter, Geert; Cnudde, Veerle

    2017-04-01

    Frost action is one of the main causes of deterioration of porous building materials in regions at middle to high latitudes. Damage will occur when the internal stresses due to ice formation become larger than the strength of the material. Hence, the sensitivity of the material to frost damage is partly defined by the structure of the solid body. On the other hand, the size, shape and interconnection of pores manages the water distribution in the building material and, therefore, the characteristics of the pore space control potential to form ice crystals (Ruedrich et al., 2011). In order to assess the damage to building materials by ice crystallization, lot of effort was put into identifying the mechanisms behind the stress build up. First of all, volumetric expansion of 9% (Hirschwald, 1908) during the transition of water to ice should be mentioned. Under natural circumstances, however, water saturation degrees within natural rocks or concrete cannot reach a damaging value. Therefore, linear growth pressure (Scherer, 1999), as well as several mechanisms triggered by water redistribution during freezing (Powers and Helmuth, 1953; Everett, 1961) are more likely responsible for damage due to freezing. Nevertheless, these theories are based on indirect observations and models and, thus, direct evidence that reveals the exact damage mechanism under certain conditions is still lacking. To obtain this proof, in-situ information needs to be acquired while a freezing process is performed. X-ray computed tomography has proven to be of great value in material research. Recent advances at the Ghent University Centre for Tomography (UGCT) have already allowed to dynamically 3D image crack growth in natural rock during freeze-thaw cycles (De Kock et al., 2015). A great potential to evaluate the different stress build-up mechanisms can be found in this imaging technique consequently. It is required to cover a range of materials with different petrophysical properties to achieve

  13. FREEZE-THAW TEST RESULTS OF POROUS CONCRETE WITH CRUSHED SCALLOP SHELL MATERIAL ADDED

    OpenAIRE

    SUGIYAMA, Masashi

    2004-01-01

    This paper addresses the possibility of recycling an abundantly available byproduct of the fisheries industry, scallop shells, by adding it to porous concrete. If these shells, now discarded as refuse, can be used as an additive in porous concrete, this c

  14. Microfabrication of hierarchical structures for engineered mechanical materials

    Science.gov (United States)

    Vera Canudas, Marc

    Materials found in nature present, in some cases, unique properties from their constituents that are of great interest in engineered materials for applications ranging from structural materials for the construction of bridges, canals and buildings to the fabrication of new lightweight composites for airplane and automotive bodies, to protective thin film coatings, amongst other fields. Research in the growing field of biomimetic materials indicates that the micro-architectures present in natural materials are critical to their macroscopic mechanical properties. A better understanding of the effect that structure and hierarchy across scales have on the material properties will enable engineered materials with enhanced properties. At the moment, very few theoretical models predict mechanical properties of simple materials based on their microstructures. Moreover these models are based on observations from complex biological systems. One way to overcome this challenge is through the use of microfabrication techniques to design and fabricate simple materials, more appropriate for the study of hierarchical organizations and microstructured materials. Arrays of structures with controlled geometry and dimension can be designed and fabricated at different length scales, ranging from a few hundred nanometers to centimeters, in order to mimic similar systems found in nature. In this thesis, materials have been fabricated in order to gain fundamental insight into the complex hierarchical materials found in nature and to engineer novel materials with enhanced mechanical properties. The materials fabricated here were mechanically characterized and compared to simple mechanics models to describe their behavior with the goal of applying the knowledge acquired to the design and synthesis of future engineered materials with novel properties.

  15. Current trends in chemistry of materials

    Indian Academy of Sciences (India)

    materials) [7] inorganic-organic hybrid materials ... Keywords. Solid materials; dense; porous; energy; synthesis; theory. 21 ... its response to the applied field were important ..... for advanced engineering and utilisation of these solids.

  16. Biodegradable electroactive materials for tissue engineering applications

    Science.gov (United States)

    Guimard, Nathalie Kathryn

    This dissertation focuses on the development of biomaterials that could be used to enhance the regeneration of severed peripheral nerves. These materials were designed to be electroactive, biodegradable, and biocompatible. To render the materials electroactive the author chose to incorporate conducting polymer (CP) units into the materials. Because CPs are inherently non-degradable, the key challenge was to create a CP-based material that was also biodegradable. Two strategies were explored to generate a biodegradable CP-based material. The first strategy centered around the incorporation of both electroactive and biodegradable subunits into a copolymer system. In the context of this approach, two bis(methoxyquaterthiophene)-co-adipic acid polyester (QAPE) analogues were successfully synthesized, one through polycondensation (giving undoped QAPE) and the second through oxidative polymerization (giving doped QAPE-2). QAPE was found to be electroactive by cyclic voltammetry, bioerodible, and cytocompatible with Schwann cells. QAPE was doped with ferric perchlorate, although only a low doping percentage was realized (˜8%). Oxidative polymerization of a bis(bithiophene) adipate permitted the direct synthesis of doped QAPE-2, which was found to have a higher doping level (˜24%). The second strategy pursued with the goal of generating an electroactive biodegradable material involved covalently immobilizing low molecular weight polythiophene chains onto the surface of crosslinked hyaluronic acid (HA) films. HA films are not only biodegradable and biocompatible, but they also provide mechanical integrity to bilayer systems. Dicyclocarbodiimide coupling of carboxylic acids to HA alcohol groups was used to functionalize HA films. The HA-polythiophene composite is still in the early stages of development. However, to date, thiophene has been successfully immobilized at the surface of HA films with a high degree of substitution. The author has also shown that thiophene

  17. Materials and surface engineering in tribology

    CERN Document Server

    Takadoum, Jamal

    2010-01-01

    This title is designed to provide a clear and comprehensive overview of tribology. The book introduces the notion of a surface in tribology where a solid surface is described from topographical, structural, mechanical, and energetic perspectives. It also describes the principal techniques used to characterize and analyze surfaces. The title then discusses what may be called the fundamentals of tribology by introducing and describing the concepts of adhesion, friction, wear, and lubrication. The book focuses on the materials used in tribology, introducing the major classes of materials used, ei

  18. Graphene synthesized on porous silicon for active electrode material of supercapacitors

    Science.gov (United States)

    Su, B. B.; Chen, X. Y.; Halvorsen, E.

    2016-11-01

    We present graphene synthesized by chemical vapour deposition under atmospheric pressure on both porous nanostructures and flat wafers as electrode scaffolds for supercapacitors. A 3nm thin gold layer was deposited on samples of both porous and flat silicon for exploring the catalytic influence during graphene synthesis. Micro-four-point probe resistivity measurements revealed that the resistivity of porous silicon samples was nearly 53 times smaller than of the flat silicon ones when all the samples were covered by a thin gold layer after the graphene growth. From cyclic voltammetry, the average specific capacitance of porous silicon coated with gold was estimated to 267 μF/cm2 while that without catalyst layer was 145μF/cm2. We demonstrated that porous silicon based on nanorods can play an important role in graphene synthesis and enable silicon as promising electrodes for supercapacitors.

  19. Graphene synthesized on porous silicon for active electrode material of supercapacitors

    International Nuclear Information System (INIS)

    Su, B B; Chen, X Y; Halvorsen, E

    2016-01-01

    We present graphene synthesized by chemical vapour deposition under atmospheric pressure on both porous nanostructures and flat wafers as electrode scaffolds for supercapacitors. A 3nm thin gold layer was deposited on samples of both porous and flat silicon for exploring the catalytic influence during graphene synthesis. Micro-four-point probe resistivity measurements revealed that the resistivity of porous silicon samples was nearly 53 times smaller than of the flat silicon ones when all the samples were covered by a thin gold layer after the graphene growth. From cyclic voltammetry, the average specific capacitance of porous silicon coated with gold was estimated to 267 μF/cm 2 while that without catalyst layer was 145μF/cm 2 . We demonstrated that porous silicon based on nanorods can play an important role in graphene synthesis and enable silicon as promising electrodes for supercapacitors. (paper)

  20. Porous media modeling and micro-structurally motivated material moduli determination via the micro-dilatation theory

    Science.gov (United States)

    Jeong, J.; Ramézani, H.; Sardini, P.; Kondo, D.; Ponson, L.; Siitari-Kauppi, M.

    2015-07-01

    In the present contribution, the porous material modeling and micro-structural material parameters determination are scrutinized via the micro-dilatation theory. The main goal is to take advantage of the micro-dilatation theory which belongs to the generalized continuum media. In the first stage, the thermodynamic laws are entirely revised to reach the energy balance relation using three variables, deformation, porosity change and its gradient underlying the porous media as described in the micro-dilatation theory or so-called void elasticity. Two experiments over cement mortar specimens are performed in order to highlight the material parameters related to the pore structure. The shrinkage due to CO2 carbonation, porosity and its gradient are calculated. The extracted values are verified via 14C-PMMA radiographic image method. The modeling of swelling phenomenon of Delayed Ettringite Formation (DEF) is studied later on. This issue is performed via the crystallization pressure application using the micro-dilatation theory.

  1. Engineered porous silicon counter electrodes for high efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Erwin, William R; Oakes, Landon; Chatterjee, Shahana; Zarick, Holly F; Pint, Cary L; Bardhan, Rizia

    2014-06-25

    In this work, we demonstrate for the first time, the use of porous silicon (P-Si) as counter electrodes in dye-sensitized solar cells (DSSCs) with efficiencies (5.38%) comparable to that achieved with platinum counter electrodes (5.80%). To activate the P-Si for triiodide reduction, few layer carbon passivation is utilized to enable electrochemical stability of the silicon surface. Our results suggest porous silicon as a promising sustainable and manufacturable alternative to rare metals for electrochemical solar cells, following appropriate surface modification.

  2. Target system materials and engineering problems

    International Nuclear Information System (INIS)

    Fischer, W.E.

    1989-01-01

    This paper discusses the common problems of target design. As a model for the discussion, the author considers a spallation source which is fed by a high power proton beam of the order of one megawatt. The materials used for the target station and particularly for the spallation target itself depend on whether the source is built for pulsed, modulated or continuous operation. The difference of materials used is mainly determined by the neutronics considerations. Depending on the choice of materials for the target systems, the characters of material problems met, are of somewhat different nature. It is recognized that for each target version quite specific difficulties have to be overcome. On the other hand, there is a whole set of problems which is common to all target versions. These are: heat load in region of proton beam interactions; thermal stress and cycling; and radiation damage. It is shown that solutions to the whole package of problems up to a beam power of 0 (1MW) have been found. The whole effort concentrates onto the region of the first few centimeters of beam penetration. Two solutions have been proposed: (1) Keep the power of proton beam limited and produce neutrons elsewhere in the target. and (2) Dilute the power by moving mechanically the target and the window. 8 refs., 11 figs

  3. Development of highly porous scaffolds based on bioactive silicates for dental tissue engineering

    International Nuclear Information System (INIS)

    Goudouri, O.M.; Theodosoglou, E.; Kontonasaki, E.; Will, J.; Chrissafis, K.; Koidis, P.; Paraskevopoulos, K.M.; Boccaccini, A.R.

    2014-01-01

    Graphical abstract: - Highlights: • Synthesis of an Mg-based glass-ceramic via the sol–gel technique. • The heat treatment of the glass-ceramic promoted the crystallization of akermanite. • Akermanite scaffolds coated with gelatin were successfully fabricated. • An HCAp layer was developed on the surface of all scaffolds after 9 days in SBF. - Abstract: Various scaffolding materials, ceramics and especially Mg-based ceramic materials, including akermanite (Ca 2 MgSi 2 O 7 ) and diopside (CaMgSi 2 O 6 ), have attracted interest for dental tissue regeneration because of their improved mechanical properties and controllable biodegradation. The aim of the present work was the synthesis of an Mg-based glass-ceramic, which would be used for the construction of workable akermanite scaffolds. The characterization of the synthesized material was performed by Fourier Transform Infrared Spectroscopy (FTIR) X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). Finally, the apatite forming ability of the scaffolds was assessed by immersion in simulated body fluid. The scaffolds were fabricated by the foam replica technique and were subsequently coated with gelatin to provide a functional surface for increased cell attachment. Finally, SEM microphotographs and FTIR spectra of the scaffolds after immersion in SBF solution indicated the inorganic bioactive character of the scaffolds suitable for the intended applications in dental tissue engineering

  4. Development of highly porous scaffolds based on bioactive silicates for dental tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Goudouri, O.M., E-mail: menti.goudouri@ww.uni-erlangen.de [Institute for Biomaterials, University of Erlangen-Nuremberg, 91058 Erlangen (Germany); Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Theodosoglou, E. [School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Kontonasaki, E. [Department of Fixed Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Will, J. [Institute for Biomaterials, University of Erlangen-Nuremberg, 91058 Erlangen (Germany); Chrissafis, K. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Koidis, P. [Department of Fixed Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Paraskevopoulos, K.M. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Boccaccini, A.R. [Institute for Biomaterials, University of Erlangen-Nuremberg, 91058 Erlangen (Germany)

    2014-01-01

    Graphical abstract: - Highlights: • Synthesis of an Mg-based glass-ceramic via the sol–gel technique. • The heat treatment of the glass-ceramic promoted the crystallization of akermanite. • Akermanite scaffolds coated with gelatin were successfully fabricated. • An HCAp layer was developed on the surface of all scaffolds after 9 days in SBF. - Abstract: Various scaffolding materials, ceramics and especially Mg-based ceramic materials, including akermanite (Ca{sub 2}MgSi{sub 2}O{sub 7}) and diopside (CaMgSi{sub 2}O{sub 6}), have attracted interest for dental tissue regeneration because of their improved mechanical properties and controllable biodegradation. The aim of the present work was the synthesis of an Mg-based glass-ceramic, which would be used for the construction of workable akermanite scaffolds. The characterization of the synthesized material was performed by Fourier Transform Infrared Spectroscopy (FTIR) X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). Finally, the apatite forming ability of the scaffolds was assessed by immersion in simulated body fluid. The scaffolds were fabricated by the foam replica technique and were subsequently coated with gelatin to provide a functional surface for increased cell attachment. Finally, SEM microphotographs and FTIR spectra of the scaffolds after immersion in SBF solution indicated the inorganic bioactive character of the scaffolds suitable for the intended applications in dental tissue engineering.

  5. Engineering design skills coverage in K-12 engineering program curriculum materials in the USA

    Science.gov (United States)

    Chabalengula, Vivien M.; Mumba, Frackson

    2017-11-01

    The current K-12 Science Education framework and Next Generation Science Standards (NGSS) in the United States emphasise the integration of engineering design in science instruction to promote scientific literacy and engineering design skills among students. As such, many engineering education programmes have developed curriculum materials that are being used in K-12 settings. However, little is known about the nature and extent to which engineering design skills outlined in NGSS are addressed in these K-12 engineering education programme curriculum materials. We analysed nine K-12 engineering education programmes for the nature and extent of engineering design skills coverage. Results show that developing possible solutions and actual designing of prototypes were the highly covered engineering design skills; specification of clear goals, criteria, and constraints received medium coverage; defining and identifying an engineering problem; optimising the design solution; and demonstrating how a prototype works, and making iterations to improve designs were lowly covered. These trends were similar across grade levels and across discipline-specific curriculum materials. These results have implications on engineering design-integrated science teaching and learning in K-12 settings.

  6. Materials engineering issues, LMFBR steam generators

    International Nuclear Information System (INIS)

    Spalaris, C.N.; Challenger, K.D.; Day, R.A.; Dutina, D.; Ring, P.J.

    1976-01-01

    Selection of 2-1/4 Cr-1 Mo as the reference construction material for LMFBR steam generators assumed a balance between its known intrinsic properties and our ability to accommodate certain of its deficiencies through design allowance. A comprehensive development program was undertaken to define base data needed, confirm assumptions made relative to desired performance, minimize defects by optimization of melting, fabrication and heat treatment processes, and prepare specifications for purchasing reactor components

  7. A comparison study of different physical treatments on cartilage matrix derived porous scaffolds for tissue engineering applications

    International Nuclear Information System (INIS)

    Moradi, Ali; Pramanik, Sumit; Ataollahi, Forough; Pingguan-Murphy, Belinda; Abdul Khalil, Alizan; Kamarul, Tunku

    2014-01-01

    Native cartilage matrix derived (CMD) scaffolds from various animal and human sources have drawn attention in cartilage tissue engineering due to the demonstrable presence of bioactive components. Different chemical and physical treatments have been employed to enhance the micro-architecture of CMD scaffolds. In this study we have assessed the typical effects of physical cross-linking methods, namely ultraviolet (UV) light, dehydrothermal (DHT) treatment, and combinations of them on bovine articular CMD porous scaffolds with three different matrix concentrations (5%, 15% and 30%) to assess the relative strengths of each treatment. Our findings suggest that UV and UV–DHT treatments on 15% CMD scaffolds can yield architecturally optimal scaffolds for cartilage tissue engineering. (paper)

  8. Hepatic Differentiation of Human Induced Pluripotent Stem Cells in a Perfused 3D Porous Polymer Scaffold for Liver Tissue Engineering

    DEFF Research Database (Denmark)

    Hemmingsen, Mette; Muhammad, Haseena Bashir; Mohanty, Soumyaranjan

    A huge shortage of liver organs for transplantation has motivated the research field of tissue engineering to develop bioartificial liver tissue and even a whole liver. The goal of NanoBio4Trans is to create a vascularized bioartificial liver tissue, initially as a liver-support system. Due...... to limitations of primary hepatocytes regarding availability and maintenance of functionality, stem cells and especially human induced pluripotent stem cells (hIPS cells) are an attractive cell source for liver tissue engineering. The aim of this part of NanoBio4Trans is to optimize culture and hepatic...... differentiation of hIPS-derived definitive endoderm (DE) cells in a 3D porous polymer scaffold built-in a perfusable bioreactor. The use of a microfluidic bioreactor array enables the culture of 16 independent tissues in one experimental run and thereby an optimization study to be performed....

  9. Digital Manufacturing of Selective Porous Barriers in Microchannels Using Multi-Material Stereolithography

    Directory of Open Access Journals (Sweden)

    Yong Tae Kim

    2018-03-01

    Full Text Available We have developed a sequential stereolithographic co-printing process using two different resins for fabricating porous barriers in microfluidic devices. We 3D-printed microfluidic channels with a resin made of poly(ethylene glycol diacrylate (MW = 258 (PEG-DA-258, a UV photoinitiator, and a UV sensitizer. The porous barriers were created within the microchannels in a different resin made of either PEG-DA (MW = 575 (PEG-DA-575 or 40% (w/w in water PEG-DA (MW = 700 (40% PEG-DA-700. We showed selective hydrogen ion diffusion across a 3D-printed PEG-DA-575 porous barrier in a cross-channel diffusion chip by observing color changes in phenol red, a pH indicator. We also demonstrated the diffusion of fluorescein across a 3D-printed 40% PEG-DA-700 porous barrier in a symmetric-channel diffusion chip by measuring fluorescence intensity changes across the porous barrier. Creating microfluidic chips with integrated porous barriers using a semi-automated 3D printing process shortens the design and processing time, avoids assembly and bonding complications, and reduces manufacturing costs compared to micromolding processes. We believe that our digital manufacturing method for fabricating selective porous barriers provides an inexpensive, simple, convenient and reproducible route to molecule delivery in the fields of molecular filtration and cell-based microdevices.

  10. Morphology and characterization of 3D micro-porous structured chitosan scaffolds for tissue engineering.

    Science.gov (United States)

    Hsieh, Wen-Chuan; Chang, Chih-Pong; Lin, Shang-Ming

    2007-06-15

    This research studies the morphology and characterization of three-dimensional (3D) micro-porous structures produced from biodegradable chitosan for use as scaffolds for cells culture. The chitosan 3D micro-porous structures were produced by a simple liquid hardening method, which includes the processes of foaming by mechanical stirring without any chemical foaming agent added, and hardening by NaOH cross linking. The pore size and porosity were controlled with mechanical stirring strength. This study includes the morphology of chitosan scaffolds, the characterization of mechanical properties, water absorption properties and in vitro enzymatic degradation of the 3D micro-porous structures. The results show that chitosan 3D micro-porous structures were successfully produced. Better formation samples were obtained when chitosan concentration is at 1-3%, and concentration of NaOH is at 5%. Faster stirring rate would produce samples of smaller pore diameter, but when rotation speed reaches 4000 rpm and higher the changes in pore size is minimal. Water absorption would reduce along with the decrease of chitosan scaffolds' pore diameter. From stress-strain analysis, chitosan scaffolds' mechanical properties are improved when it has smaller pore diameter. From in vitro enzymatic degradation results, it shows that the disintegration rate of chitosan scaffolds would increase along with the processing time increase, but approaching equilibrium when the disintegration rate reaches about 20%.

  11. Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

    Directory of Open Access Journals (Sweden)

    Marwa Akkari

    2016-12-01

    Full Text Available In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica–organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica–organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP homogeneously assembled to the clay–SiO2 framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite–silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM. The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.

  12. Materials for construction and civil engineering science, processing, and design

    CERN Document Server

    Margarido, Fernanda

    2015-01-01

    This expansive volume presents the essential topics related to construction materials composition and their practical application in structures and civil installations. The book's diverse slate of expert authors assemble invaluable case examples and performance data on the most important groups of materials used in construction, highlighting aspects such as nomenclature, the properties, the manufacturing processes, the selection criteria, the products/applications, the life cycle and recyclability, and the normalization. Civil Engineering Materials: Science, Processing, and Design is ideal for practicing architects; civil, construction, and structural engineers, and serves as a comprehensive reference for students of these disciplines. This book also: ·       Provides a substantial and detailed overview of traditional materials used in structures and civil infrastructure ·       Discusses properties of natural and synthetic materials in construction and materials' manufacturing processes ·  �...

  13. Quasi-optic millimeter-wave device application of liquid crystal material by using porous PMMA matrix

    Science.gov (United States)

    Nose, T.; Watanabe, Y.; Kon, A.; Ito, R.; Honma, M.

    2018-02-01

    Recently, millimeter-waves (MMWs) have become indispensable for application in next-generation high-speed wireless communication i.e., 5G, in addition to conventional applications such as in automobile collision avoidance radars and airport security inspection systems. Some manageable devices to control MMW propagation will be necessary with the development of this new technology field. We believe that liquid crystal (LC) devices are one of the major candidates for such applications because it is known that LC materials are excellent electro-optic materials. However, as the wavelength of MMWs is extremely longer than the optics region, extremely thick LC layers are necessary if we choose the quasioptic approach to attain LC MMW control devices. Therefore, we adopt a PDLC structure to attain the extremely thick LC layers by using porous (polymethyl methacrylate) PMMA materials, which can be easily obtained using a solvent consisting of a mixture of ethanol/water and a little heating. In this work, we focus on Fresnel lens, which is an important quasi-optic device for MMW application, to introduce a tunable property by using LC materials. Here, we adopt the thin film deposition method to obtain a porous PMMA matrix with the aim of obtaining final composite structure based on the Fresnel substrate. First, the fundamental material properties of porous PMMA are investigated to control the microscopic porous structure. Then, the LC-MMW Fresnel lens substrate is prepared using a 3D printer, and the fundamental MMW focusing properties of the prototype composite Fresnel structure are investigated.

  14. Nitrogen-doped hierarchical porous carbon materials prepared from meta-aminophenol formaldehyde resin for supercapacitor with high rate performance

    International Nuclear Information System (INIS)

    Zhou, Jin; Zhang, Zhongshen; Xing, Wei; Yu, Jing; Han, Guoxing; Si, Weijiang; Zhuo, Shuping

    2015-01-01

    Graphical abstract: N-doped hierarchical porous carbons with high rate capacitive performance are prepared by a combination method of nano-SiO 2 template/KOH activation. - Highlights: • A mass produced nano-SiO 2 is used to prepared hierarchical porous carbon. • N-doped hierarchical porous carbon materials are easily prepared. • The NHPCs materials exhibit a very high capacitance of up to 260.5 F g −1 . • The NHPC-800 sample shows very high rate capability. • Hierarchical porosity and N-doping synergistically enhances the whole capacitance. - Abstract: In this work, nitrogen-doped hierarchical porous carbon materials (NHPCs) are prepared by a two-step method combined of a hard template process and KOH-activation treatment. Low cost and large-scale commercial nano-SiO 2 are used as a hard template. The hierarchical porosity, structure and nitrogen-doped surface chemical properties are proved by a varies of means, such as scanning electron microscopy, transition electron microscopy, N 2 sorption, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. When the prepared NHPCs materials are used as the electrode materials for supercapacitors in KOH electrolyte, they exhibit very high specific capacitance, good power capability and excellent cyclic stability. NHPC-800 carbon shows a high capacitance of 114.0 F g −1 at the current density of 40 A g −1 , responding to a high energy and power densities of 4.0 Wh kg −1 and 10 000 W kg −1 , and a very short drain time of 1.4 s. The excellent capacitive performance may be due to the synergistic effect of the hierarchical porosity, high effective surface area and heteroatom doping, resulting in both electrochemical double layer and Faradaic capacitance contributions

  15. Material Engineering for Phase Change Memory

    Science.gov (United States)

    Cabrera, David M.

    As semiconductor devices continue to scale downward, and portable consumer electronics become more prevalent there is a need to develop memory technology that will scale with devices and use less energy, while maintaining performance. One of the leading prototypical memories that is being investigated is phase change memory. Phase change memory (PCM) is a non-volatile memory composed of 1 transistor and 1 resistor. The resistive structure includes a memory material alloy which can change between amorphous and crystalline states repeatedly using current/voltage pulses of different lengths and magnitudes. The most widely studied PCM materials are chalcogenides - Germanium-Antimony-Tellerium (GST) with Ge2Sb2Te3 and Germanium-Tellerium (GeTe) being some of the most popular stochiometries. As these cells are scaled downward, the current/voltage needed to switch these materials becomes comparable to the voltage needed to sense the cell's state. The International Roadmap for Semiconductors aims to raise the threshold field of these devices from 66.6 V/mum to be at least 375 V/mum for the year 2024. These cells are also prone to resistance drift between states, leading to bit corruption and memory loss. Phase change material properties are known to influence PCM device performance such as crystallization temperature having an effect on data retention and litetime, while resistivity values in the amorphous and crystalline phases have an effect on the current/voltage needed to write/erase the cell. Addition of dopants is also known to modify the phase change material parameters. The materials G2S2T5, GeTe, with dopants - nitrogen, silicon, titanium, and aluminum oxide and undoped Gallium-Antimonide (GaSb) are studied for these desired characteristics. Thin films of these compositions are deposited via physical vapor deposition at IBM Watson Research Center. Crystallization temperatures are investigated using time resolved x-ray diffraction at Brookhaven National Laboratory

  16. Preface to 18. Chemnitz seminar on materials engineering

    International Nuclear Information System (INIS)

    2016-01-01

    The Institute of Materials Science and Engineering (Institut für Werkstoffwissenschaft und Werkstofftechnik, IWW) is a well-established part of the Faculty of Mechanical Engineering at Technische Universität Chemnitz, Germany. We are proud to host our traditional scientific meeting, the Chemnitz Seminar on Materials Engineering - Werkstofftechnisches Kolloquium, this year being the 18 th Seminar. The aim of our meeting is to bring together scientists and engineers both from academia and industry, and this is reflected by the different scientific sessions that cover various relevant topics, such as composite materials, microstructural analysis, and surface engineering. Special focus sessions highlight recent developments in the Federal Cluster of Excellence MERGE and in the Collaborative Research Center SFB 692, both established in Chemnitz. We, as organizers, continuously strive to improve our Seminar, and we therefore decided to provide all contributors with the opportunity to publish their papers, in addition to the printed Proceedings volume, in an international, peer-reviewed journal. Publication in IOP Conference Series: Materials Science and Engineering allows for a wide dissemination of the many interesting and relevant results presented in our Seminar. Clearly, this is understood and appreciated by many participants of our meeting: more than 65% of all authors chose to also publish their Proceedings papers in this special issue, which consequently provides an excellent overview of the main topics of our Seminar. Chemnitz, March 2016 Prof. Thomas Lampke Prof. Guntram Wagner Prof. Martin F.-X. Wagner (paper)

  17. Atomic Layer Deposition on Porous Materials: Problems with Conventional Approaches to Catalyst and Fuel Cell Electrode Preparation

    Directory of Open Access Journals (Sweden)

    Tzia Ming Onn

    2018-03-01

    Full Text Available Atomic layer deposition (ALD offers exciting possibilities for controlling the structure and composition of surfaces on the atomic scale in heterogeneous catalysts and solid oxide fuel cell (SOFC electrodes. However, while ALD procedures and equipment are well developed for applications involving flat surfaces, the conditions required for ALD in porous materials with a large surface area need to be very different. The materials (e.g., rare earths and other functional oxides that are of interest for catalytic applications will also be different. For flat surfaces, rapid cycling, enabled by high carrier-gas flow rates, is necessary in order to rapidly grow thicker films. By contrast, ALD films in porous materials rarely need to be more than 1 nm thick. The elimination of diffusion gradients, efficient use of precursors, and ligand removal with less reactive precursors are the major factors that need to be controlled. In this review, criteria will be outlined for the successful use of ALD in porous materials. Examples of opportunities for using ALD to modify heterogeneous catalysts and SOFC electrodes will be given.

  18. Mechanical Properties of Ti-6Al-4V Octahedral Porous Material Unit Formed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Jianfeng Sun

    2012-01-01

    Full Text Available The Ti-6Al-4V octahedral porous material unit is designed to calculate its load. In this paper, ANSYS is adopted for the load simulation of the unit. And a simplified model of dimensional theoretical calculation is established, by which the analytical equation of the fracture load is obtained and the calculation of the load of Ti-6Al-4V is completed. Moreover, selective laser melting is adopted in processing the Ti-6Al-4V porous material unit. The experimental value of fracture load of this material is obtained through compression experiment. The results show that the simulation curves approximate the variation tendency of the elastic deformation of the compression curves; the curves of theoretical calculation approximate the general variation tendency; and the experimental value of fracture load is very close to the theoretical value. Therefore, the theoretical prediction accuracy of fracture load is high, which lays the foundation for the mechanical properties of the octahedral porous material.

  19. Microstructural characterization of porous materials by X-ray microtomography and gamma ray transmission techniques

    International Nuclear Information System (INIS)

    Moreira, Anderson Camargo

    2006-01-01

    This work presents the application of the X-ray microtomography and gamma ray transmission techniques for the microstructure characterization of different kinds of materials. Total porosity, pore size distribution and the two point correlation functions were measured. The two point correlation function, which allows the reconstruction of 3D models, was carried out for two samples. Seven ceramic tablets of Alumina (Al 2 O 3 ), seven tablets of Boron Carbide (B 4 C), three samples of sedimentary rocks and one sample of Titanium foam were analyzed. The experimental set up for the Gamma Ray Transmission technique consisted of: a 2'' x 2'' crystal NaI(Tl) detector, an 241 Am radioactive source (59,53 keV, 100 mCi), an automatic micrometric table for the sample XZ movement and standard gamma spectrometry electronics. Two microtomography systems were used: a Fein Focus system, constituted by an X-ray tube, operated at 160 kV and 0.3 to 1.1 mA, a CCD camera and the movement sample system, and a Skyscan system, model 1072, with a X-ray tube operated at 100 kV and 100μA, and a CCD camera. The ceramic tablets, analyzed by the gamma ray transmission technique presented results for most of the porosities data with smaller confidence intervals and inside the intervals supplied by the tablets manufacturer. The Titanium porous sample was analyzed by the two techniques, its microtomography images achieved a resolution of 17μm, obtained employing the Fein Focus system. For both techniques, this sample showed high porosity, which allows its application for this purpose. The sandstones samples were analyzed by the Skyscan system, achieving resolutions of 19μm, 11μm and 3.8μm for each sample, respectively. The resolutions of 11μm and 3.8μm were the ones that generated better 2D sections for the respective samples and, consequently, more reliable porosities. The 3.8μm resolution was the one that best quantified the pore size distribution data, showing information not shown by

  20. Exploring Trianglamine Derivatives and Trianglamine Coordination Complexes as Porous Organic Materials

    KAUST Repository

    Eziashi, Magdalene

    2018-05-01

    Trianglamines are triangular chiral macrocycles that were first synthesized by Gawronski’s group in Poland in the year 2000.1 Despite their unique properties; triangular pore shape, chirality, symmetric structure and tunable pore size, they are still a poorly researched class of macrocycles today. Trianglamines have yet a role to play as porous organic molecules for separation processes, as macrocyclic precursors to build increasingly complex supramolecular assemblies and as building blocks for caged porous organic structures. The aim of the Thesis work is to explore trianglamine, its derivatives, and assemblies as viable porous organic molecules for potential gas capture and separation.

  1. Different effects of surface heterogeneous atoms of porous and non-porous carbonaceous materials on adsorption of 1,1,2,2-tetrachloroethane in aqueous environment.

    Science.gov (United States)

    Chen, Weifeng; Ni, Jinzhi

    2017-05-01

    The surface heterogeneous atoms of carbonaceous materials (CMs) play an important role in adsorption of organic pollutants. However, little is known about the surface heterogeneous atoms of CMs might generate different effect on adsorption of hydrophobic organic compounds by porous carbonaceous materials - activated carbons (ACs) and non-porous carbonaceous materials (NPCMs). In this study, we observed that the surface oxygen and nitrogen atoms could decrease the adsorption affinity of both ACs and NPCMs for 1,1,2,2-tetrachloroethane (TeCA), but the degree of decreasing effects were very different. The increasing content of surface oxygen and nitrogen ([O + N]) caused a sharper decrease in adsorption affinity of ACs (slope of lg (k d /SA) vs [O + N]: -0.098∼-0.16) than that of NPCMs (slope of lg (k d /SA) vs [O + N]: -0.025∼-0.059) for TeCA. It was due to the water cluster formed by the surface hydrophilic atoms that could block the micropores and generate massive invalid adsorption sites in the micropores of ACs, while the water cluster only occupied the surface adsorption sites of NPCMs. Furthermore, with the increasing concentration of dissolved TeCA, the effect of surface area on adsorption affinity of NPCMs for TeCA kept constant while the effect of [O + N] decreased due to the competitive adsorption between water molecule and TeCA on the surface of NPCMs, meanwhile, both the effects of micropore volume and [O + N] on adsorption affinity of ACs for TeCA were decreased due to the mechanism of micropore volume filling. These findings are valuable for providing a deep insight into the adsorption mechanisms of CMs for TeCA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Engineering spinal fusion: evaluating ceramic materials for cell based tissue engineered approaches

    NARCIS (Netherlands)

    Wilson, C.E.

    2011-01-01

    The principal aim of this thesis was to advance the development of tissue engineered posterolateral spinal fusion by investigating the potential of calcium phosphate ceramic materials to support cell based tissue engineered bone formation. This was accomplished by developing several novel model

  3. Chitin based heteroatom-doped porous carbon as electrode materials for supercapacitors.

    Science.gov (United States)

    Zhou, Jie; Bao, Li; Wu, Shengji; Yang, Wei; Wang, Hui

    2017-10-01

    Chitin biomass has received much attention as an amino-functional polysaccharide precursor for synthesis of carbon materials. Rich nitrogen and oxygen dual-doped porous carbon derived from cicada slough (CS), a renewable biomass mainly composed of chitin, was synthesized and employed as electrode materials for electrochemical capacitors, for the first time ever. The cicada slough-derived carbon (CSC) was prepared by a facile process via pre-carbonization in air, followed by KOH activation. The weight ratio of KOH and char plays an important role in fabricating the microporous structure and tuning the surface chemistry of CSC. The obtained CSC had a large specific surface area (1243-2217m 2 g -1 ), fairly high oxygen content (28.95-33.78 at%) and moderate nitrogen content (1.47-4.35 at%). The electrochemical performance of the CS char and CSC as electrodes for capacitors was evaluated in a three-electrode cell configuration with 6M KOH as the electrolyte. Electrochemical studies showed that the as-prepared CSC activated at the KOH-to-char weight ratio of 2 exhibited the highest specific capacitance (266.5Fg -1 at a current density of 0.5Ag -1 ) and excellent rate capability (196.2Fg -1 remained at 20Ag -1 ) and cycle durability. In addition, the CSC-2-based symmetrical device possessed the desirable energy density and power density of about 15.97Whkg -1 and 5000Wkg -1 at 5Ag -1 , respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Hierarchically interconnected porous scaffolds for phase change materials with improved thermal conductivity and efficient solar-to-electric energy conversion.

    Science.gov (United States)

    Yang, Jie; Yu, Peng; Tang, Li-Sheng; Bao, Rui-Ying; Liu, Zheng-Ying; Yang, Ming-Bo; Yang, Wei

    2017-11-23

    An ice-templating self-assembly strategy and a vacuum impregnation method were used to fabricate polyethylene glycol (PEG)/hierarchical porous scaffold composite phase change materials (PCMs). Hierarchically interconnected porous scaffolds of boron nitride (BN), with the aid of a small amount of graphene oxide (GO), endow the composite PCMs with high thermal conductivity, excellent shape-stability and efficient solar-to-electric energy conversion. The formation of a three-dimensional (3D) thermally conductive pathway in the composites contributes to improving the thermal conductivity up to 2.36 W m -1 K -1 at a relatively low content of BN (ca. 23 wt%). This work provides a route for thermally conductive and shape-stabilized composite PCMs used as energy storage materials.

  5. Scalable preparation of porous micron-SnO2/C composites as high performance anode material for lithium ion battery

    Science.gov (United States)

    Wang, Ming-Shan; Lei, Ming; Wang, Zhi-Qiang; Zhao, Xing; Xu, Jun; Yang, Wei; Huang, Yun; Li, Xing

    2016-03-01

    Nano tin dioxide-carbon (SnO2/C) composites prepared by various carbon materials, such as carbon nanotubes, porous carbon, and graphene, have attracted extensive attention in wide fields. However, undesirable concerns of nanoparticles, including in higher surface area, low tap density, and self-agglomeration, greatly restricted their large-scale practical applications. In this study, novel porous micron-SnO2/C (p-SnO2/C) composites are scalable prepared by a simple hydrothermal approach using glucose as a carbon source and Pluronic F127 as a pore forming agent/soft template. The SnO2 nanoparticles were homogeneously dispersed in micron carbon spheres by assembly with F127/glucose. The continuous three-dimensional porous carbon networks have effectively provided strain relaxation for SnO2 volume expansion/shrinkage during lithium insertion/extraction. In addition, the carbon matrix could largely minimize the direct exposure of SnO2 to the electrolyte, thus ensure formation of stable solid electrolyte interface films. Moreover, the porous structure could also create efficient channels for the fast transport of lithium ions. As a consequence, the p-SnO2/C composites exhibit stable cycle performance, such as a high capacity retention of over 96% for 100 cycles at a current density of 200 mA g-1 and a long cycle life up to 800 times at a higher current density of 1000 mA g-1.

  6. Numerical study for enhancing the thermal conductivity of phase change material (PCM) storage using high thermal conductivity porous matrix

    International Nuclear Information System (INIS)

    Mesalhy, Osama; Lafdi, Khalid; Elgafy, Ahmed; Bowman, Keith

    2005-01-01

    In this paper, the melting process inside an irregular geometry filled with high thermal conductivity porous matrix saturated with phase change material PCM is investigated numerically. The numerical model is resting on solving the volume averaged conservation equations for mass, momentum and energy with phase change (melting) in the porous medium. The convection motion of the liquid phase inside the porous matrix is solved considering the Darcy, Brinkman and Forchiemer effects. A local thermal non-equilibrium assumption is considered due to the large difference in thermal properties between the solid matrix and PCM by applying a two energy equation model. The numerical code shows good agreement for pure PCM melting with another published numerical work. Through this study it is found that the presence of the porous matrix has a great effect on the heat transfer and melting rate of the PCM energy storage. Decreasing the porosity of the matrix increases the melting rate, but it also damps the convection motion. It is also found that the best technique to enhance the response of the PCM storage is to use a solid matrix with high porosity and high thermal conductivity

  7. Superior performance of nanoscaled Fe3O4 as anode material promoted by mosaicking into porous carbon framework

    Science.gov (United States)

    Wan, Wang; Wang, Chao; Zhang, Weidong; Chen, Jitao; Zhou, Henghui; Zhang, Xinxiang

    2014-01-01

    A nanoscale Fe3O4/porous carbon-multiwalled carbon nanotubes (MWCNTs) composite is synthesized through a simple hard-template method by using Fe2O3 nanoparticles as the precursor and SiO2 nanoparticles as the template. The composite shows good cycle performance (941 mAh g-1 for the first cycle at 0.1 C, with 106% capacity retention at the 80th cycle) and high rate capability (71% capacity retained at 5 C rate). Its excellent electrical properties can be attributed to the porous carbon framework structure, which is composed of carbon and MWCNTs. In this composite, the porous structure provides space for the change in Fe3O4 volume during cycling and shortens the lithium ion diffusion distance, the MWCNTs increase the electron conductivity, and the carbon coating reduces the risk of side reactions. The results provide clear evidences for the utility of porous carbon framework to improve the electrochemical performances of nanosized transition-metal oxides as anode materials for lithium-ion batteries.

  8. Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material for ²⁹Si Magnetic Resonance Imaging.

    Science.gov (United States)

    Seo, Hyeonglim; Choi, Ikjang; Whiting, Nicholas; Hu, Jingzhe; Luu, Quy Son; Pudakalakatti, Shivanand; McCowan, Caitlin; Kim, Yaewon; Zacharias, Niki; Lee, Seunghyun; Bhattacharya, Pratip; Lee, Youngbok

    2018-05-20

    Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for ²⁹Si magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their ²⁹Si MR signals; the particles demonstrated long ²⁹Si spin-lattice relaxation (T₁) times (~ 25 mins), which suggests potential applicability for medical imaging. Furthermore, ²⁹Si hyperpolarization levels were sufficient to allow ²⁹Si MRI in phantoms. These results underscore the potential of porous silicon nanoparticles that, when combined with hyperpolarized magnetic resonance imaging, can be a powerful theragnostic deep tissue imaging platform to interrogate various biomolecular processes in vivo. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Exploring Trianglamine Derivatives and Trianglamine Coordination Complexes as Porous Organic Materials

    KAUST Repository

    Eziashi, Magdalene

    2018-01-01

    , they are still a poorly researched class of macrocycles today. Trianglamines have yet a role to play as porous organic molecules for separation processes, as macrocyclic precursors to build increasingly complex supramolecular assemblies and as building blocks

  10. Investigation of the adsorption properties and structures of porous materials for adsorptive removal of pollutants from water

    OpenAIRE

    ZAHRA ABBASI

    2017-01-01

    Adsorption is a low cost and effective method for the removal of non-biodegradable and harmful pollutants from water which has been widely used in industry. Porous and nanoporous materials such as metal organic frameworks (MOFs) and fly ash wastes were used as adsorbents for the removal of pollutants from water. The study showed MOF adsorbent could be fabricated as beads for easy handling and recycling due to the very low buoyancy. Temperature of heat treatment had significant effect on adsor...

  11. Porous InP as piezoelectric matrix material in 1-3 magnetoelectric composite sensors

    International Nuclear Information System (INIS)

    Gerngross, M.-D.; Leisner, M.; Carstensen, J.; Foell, H.

    2011-01-01

    This work shows the results of the fabrication of semi-insulating piezoelectric porous InP structures by electrochemical etching and subsequent purely chemical post-etching in an isotropic HF, HNO 3 , EtOH and HAc containing electrolyte. The piezoelectric modulus d 14 of porous InP is measured to around |60| pm / V, which larger by a factor of 30 compared to bulk InP.

  12. Advanced materials and protective coatings in aero-engines application

    OpenAIRE

    M. Hetmańczyk; L. Swadźba; B. Mendala

    2007-01-01

    Purpose: The following article demonstrates the characteristics of the materials applied as parts of aircraft engine turbines and the stationary gas turbines. The principal technologies for manufacturing the heat resistant coatings and the erosion and corrosion resistant coatings were characterized. Sample applications for the aforementioned coatings are presented: on turbine blades, compressor blades and on parts of combustion chambers of aircraft engines.Design/methodology/approach: The nic...

  13. Positron annihilation lifetime spectroscopy (PALS) application in metal barrier layer integrity for porous low- k materials

    CERN Document Server

    Simon, Lin; Gidley, D W; Wetzel, J T; Monnig, K A; Ryan, E T; Simon, Jang; Douglas, Yu; Liang, M S; En, W G; Jones, E C; Sturm, J C; Chan, M J; Tiwari, S C; Hirose, M

    2002-01-01

    Positron Annihilation Lifetime Spectroscopy (PALS) is a useful tool to pre-screen metal barrier integrity for Si-based porous low-k dielectrics. Pore size of low-k, thickness of metal barrier Ta, positronium (Ps) leakage from PALS, trench sidewall morphology, electrical test from one level metal (1LM) pattern wafer and Cu diffusion analysis were all correlated. Macro-porous low-k (pore size >=200 AA) and large scale meso-porous low-k (>50~200 AA) encounter both Ps leakage and Cu diffusion into low-k dielectric in the 0.25 mu mL/0.3 mu mS structures when using SEMATECH in-house PVD Ta 250 AA as barrier layer. For small scale meso-porous (>20~50 AA) and micro- porous (<=20 AA) low-k, no Ps leakage and no Cu diffusion into low-k were observed even with PVD Ta 50 AA, which is proved also owing to sidewall densification to seal all sidewall pores due to plasma etch and ash. For future technology, smaller pore size of porous Si-based low-k (=<50 AA) will be preferential for dense low-k like trench sidewall to...

  14. A new numerical modelling method for deformation behaviour of metallic porous materials using X-ray computed microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Doroszko, M., E-mail: m.doroszko@pb.edu.pl; Seweryn, A., E-mail: a.seweryn@pb.edu.pl

    2017-03-24

    Microtomographic devices have limited imaging accuracy and are often insufficient for proper mapping of small details of real objects (e.g. elements of material mesostructures). This paper describes a new method developed to compensate the effect of X-ray computed microtomography (micro-CT) inaccuracy in numerical modelling of the deformation process of porous sintered 316 L steel. The method involves modification of microtomographic images where the pore shapes are separated. The modification consists of the reconstruction of fissures and small pores omitted by micro-CT scanning due to the limited accuracy of the measuring device. It enables proper modelling of the tensile deformation process of porous materials. In addition, the proposed approach is compared to methods described in the available literature. As a result of numerical calculations, stress and strain distributions were obtained in deformed sintered 316 L steel. Based on the results, macroscopic stress-strain curves were received. Maximum principal stress distributions obtained by the proposed calculation model, indicated specific locations, where the stress reached a critical value, and fracture initiation occurred. These are bridges with small cross sections and notches in the shape of pores. Based on calculation results, the influence of the deformation mechanism of the material porous mesostructures on their properties at the macroscale is described.

  15. A new numerical modelling method for deformation behaviour of metallic porous materials using X-ray computed microtomography

    International Nuclear Information System (INIS)

    Doroszko, M.; Seweryn, A.

    2017-01-01

    Microtomographic devices have limited imaging accuracy and are often insufficient for proper mapping of small details of real objects (e.g. elements of material mesostructures). This paper describes a new method developed to compensate the effect of X-ray computed microtomography (micro-CT) inaccuracy in numerical modelling of the deformation process of porous sintered 316 L steel. The method involves modification of microtomographic images where the pore shapes are separated. The modification consists of the reconstruction of fissures and small pores omitted by micro-CT scanning due to the limited accuracy of the measuring device. It enables proper modelling of the tensile deformation process of porous materials. In addition, the proposed approach is compared to methods described in the available literature. As a result of numerical calculations, stress and strain distributions were obtained in deformed sintered 316 L steel. Based on the results, macroscopic stress-strain curves were received. Maximum principal stress distributions obtained by the proposed calculation model, indicated specific locations, where the stress reached a critical value, and fracture initiation occurred. These are bridges with small cross sections and notches in the shape of pores. Based on calculation results, the influence of the deformation mechanism of the material porous mesostructures on their properties at the macroscale is described.

  16. Quantum engineering of transistors based on 2D materials heterostructures

    Science.gov (United States)

    Iannaccone, Giuseppe; Bonaccorso, Francesco; Colombo, Luigi; Fiori, Gianluca

    2018-03-01

    Quantum engineering entails atom-by-atom design and fabrication of electronic devices. This innovative technology that unifies materials science and device engineering has been fostered by the recent progress in the fabrication of vertical and lateral heterostructures of two-dimensional materials and by the assessment of the technology potential via computational nanotechnology. But how close are we to the possibility of the practical realization of next-generation atomically thin transistors? In this Perspective, we analyse the outlook and the challenges of quantum-engineered transistors using heterostructures of two-dimensional materials against the benchmark of silicon technology and its foreseeable evolution in terms of potential performance and manufacturability. Transistors based on lateral heterostructures emerge as the most promising option from a performance point of view, even if heterostructure formation and control are in the initial technology development stage.

  17. Quantum engineering of transistors based on 2D materials heterostructures.

    Science.gov (United States)

    Iannaccone, Giuseppe; Bonaccorso, Francesco; Colombo, Luigi; Fiori, Gianluca

    2018-03-01

    Quantum engineering entails atom-by-atom design and fabrication of electronic devices. This innovative technology that unifies materials science and device engineering has been fostered by the recent progress in the fabrication of vertical and lateral heterostructures of two-dimensional materials and by the assessment of the technology potential via computational nanotechnology. But how close are we to the possibility of the practical realization of next-generation atomically thin transistors? In this Perspective, we analyse the outlook and the challenges of quantum-engineered transistors using heterostructures of two-dimensional materials against the benchmark of silicon technology and its foreseeable evolution in terms of potential performance and manufacturability. Transistors based on lateral heterostructures emerge as the most promising option from a performance point of view, even if heterostructure formation and control are in the initial technology development stage.

  18. Fabrication and characterization of hydrothermal cross-linked chitosan porous scaffolds for cartilage tissue engineering applications.

    Science.gov (United States)

    Shamekhi, Mohammad Amin; Rabiee, Ahmad; Mirzadeh, Hamid; Mahdavi, Hamid; Mohebbi-Kalhori, Davod; Baghaban Eslaminejad, Mohamadreza

    2017-11-01

    The use of various chemical cross-linking agents for the improvement of scaffolds physical and mechanical properties is a common practical method, which is limited by cytotoxicity effects. Due to exerting contract type forces, chondrocytes are known to implement shrinkage on the tissue engineered constructs, which can be avoided by the scaffold cross-linking. In the this research, chitosan scaffolds are cross-linked with hydrothermal treatment with autoclave sterilization time of 0, 10, 20 and 30min, to avoid the application of the traditional chemical toxic materials. The optimization studies with gel content and crosslink density measurements indicate that for 20min sterilization time, the gel content approaches to ~80%. The scaffolds are fully characterized by the conventional techniques such as SEM, porosity and permeability, XRD, compression, thermal analysis and dynamic mechanical thermal analysis (DMTA). FT-IR studies shows that autoclave inter-chain cross-linking reduces the amine group absorption at 1560cm -1 and increase the absorption of N-acetylated groups at 1629cm -1 . It is anticipated, that this observation evidenced by chitosan scaffold browning upon autoclave cross-linking is an indication of the familiar maillard reaction between amine moieties and carbonyl groups. The biodegradation rate analysis shows that chitosan scaffolds with lower concentrations, possess suitable degradation rate for cartilage tissue engineering applications. In addition, cytotoxicity analysis shows that fabricated scaffolds are biocompatible. The human articular chondrocytes seeding into 3D cross-linked scaffolds shows a higher viability and proliferation in comparison with the uncross-linked samples and 2D controls. Investigation of cell morphology on the scaffolds by SEM, shows a more spherical morphology of chondrocytes on the cross-linked scaffolds for 21days of in vitro culture. Copyright © 2017. Published by Elsevier B.V.

  19. Sliding seal materials for low heat rejection engines

    Science.gov (United States)

    Beaty, Kevin; Lankford, James; Vinyard, Shannon

    1989-01-01

    Sliding friction coefficients and wear rates of promising piston seal materials were measured under temperature, environmental, velocity, and loading conditions that are representative of the low heat rejection (LHR) diesel engine environment. These materials included carbides, oxides, and nitrides. In addition, silicon nitride and partially stablized zirconia disks (cylinder liners) were ion-implanted with TiNi, Ni, Co, and Cr, and subsequently run against carbide pins (piston rings), with the objective of producing reduced friction via solid lubrication at elevated temperature. Friction and wear measurements were obtained using pin-on-disk laboratory experiments and a unique engine friction test rig. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above during the pin-on-disk tests. The coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combination, by the ion-implantation of TiNi or Co. This beneficial effect was found to derive from the lubricious Ti, Ni, and Co oxides. Similar results were demonstrated on the engine friction test rig at lower temperatures. The structural integrity and feasibility of engine application with the most promising material combination were demonstrated during a 30-hour single-cylinder, direct-injection diesel engine test.

  20. Advanced materials for aircraft engine applications. Koku engine yo zairyo no doko

    Energy Technology Data Exchange (ETDEWEB)

    1994-05-01

    The thrust/weight ratio which is thrust per unit weight of engine is a parameter of aircraft engine performance. With a mean material density of 6.6g/cm[sup 3], some of the supersonic plane engines are 7.9 in thrust/weight ratio. Its attaining 20 is predicted by some reports. The turbine inlet temperature is a parameter of engine temperature heightening exceeds 1400[degree]C. Its attaining 2000[degree]C in the 21st century is also predicted by some reports. By dividing the aircraft engine materials into both improvement and innovation material systems, the present paper explained the characteristics and present status of materials, and how to put them in practical use. As an improvement material, titanium alloy, nickel base alloy and resinous composite materials were exhibited with examples of having improved the established material system in performance and cost. Used as a turbine vane member, the nickel base alloy contributes, as a unidirectional coagulation alloy, single crystal alloy and oxide dispersion exciting alloy, to the creep resistance strengthening at high temperatures against the fatigue due to thermal strain. It is also explained how to put TiAl and FRM to practical use. 8 refs., 13 figs., 2 tabs.