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Search results for: POROUS STRUCTURES
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Porous structures in aspects of transpirating cooling of oxycombustion chamber walls
PublicationA wet oxycombustion chamber, which must be effectively cooled due to high temperature evolved during the oxy-combustion process, by using the phenomena of Reynolds thermal transpiration and Navier slip velocity. Closures needed to execute mass flow rate in a microchannel, which should be treated as a single porous structure in the walls of the combustion chamber, have been obtained by applying a local 3D approach. The Navier-Stokes...
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Processing of porous structures of YBa2Cu3O7-δ High-temperature superconductor
PublicationPublikacja opisuje technikę otrzymywania nadprzewodnika wysokotemperaturowego YBa2Cu3O7-x o porach otwartych.
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3D porous graphene-based structures- synthesis and applications
PublicationPorous carbon-based materials are of the great industrial and academic interest due to their high surface area, low density, good electrical conductivity, chemical inertness and low cost of fabrication. Up to now, the main approach to obtain porous carbon structures has involved the pyrolysis of carbonaceous natural or synthetic precursors. After the isolation of graphene, the interest in 3D porous graphene-based structures (called...
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Processing of Polyester-Urethane Filament and Characterization of FFF 3D Printed Elastic Porous Structures with Potential in Cancellous Bone Tissue Engineering
PublicationThis paper addresses the potential of self-made polyester-urethane filament as a candidate for Fused Filament Fabrication (FFF)-based 3D printing (3DP) in medical applications. Since the industry does not provide many ready-made solutions of medical-grade polyurethane filaments, we undertook research aimed at presenting the process of thermoplastic polyurethane (TPU) filament formation, detailed characteristics, and 3DP of specially...
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A method for evaluating durability of porous slide bearings
PublicationThe article presents the structures of porous bearings bushes and greasy lubricants, and the similarity criterion resulting from this structures. A phisical model is proposed which describes the operation of the porous slide bearing bush taking into account, via analogy, the phenomena taking place in the grease lubricant nodes instead of those observed in the bush structures.Included are the result of experimental tests of three...
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ESTIMATION OF YOUNG`S MODULUS OF THE POROUS TITANIUM ALLOY WITH THE USE OF FEM PACKAGE
PublicationPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can easily be produced by stereolithographic techniques, e.g. selective laser melting (SLM). Numerical methods, like Finite Element Method (FEM) have great potential in testing new scaffold designs, according to their mechanical properties before manufacturing, i.e. strength or stiffness. An example of such designs...
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Porous material-based sorbent coatings in Solid-phase microextraction technique: Recent trends and future perspectives
PublicationThe use of porous materials as sorbents in sample preparation techniques has gained recent scientific attention in the context of developing novel fibers for the Solid-phase microextraction (SPME) technique. SPME requires the appropriate selection of a robust sorbent for successful utilization under variable conditions. A deeper understanding of the nature of newly developed porous SPME coatings and the impact of their structures...
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Electrochemicalsynthesis of 3D nano-/micro-structured porous polypyrrole
PublicationIn this work, electrosynthesis of electroactive, 3D nano-/micro-structured porous polypyrrole film is presented. The PPy film was synthesized potentiostatically in a one-step process from aqueous solution of pyrrole and lithium perchlorate. The growth mechanism of such structure included: the formation of typical globular PPy film, followed by the formation of the PPy fibers, which then took part in the formation of 3D highly porous...
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3D Printing of Metallic Implants
PublicationThe fabrication of various elements, solid and open porous structures of stainless steel and Ti alloy is described. The process was started with the design of 3D models in CAD/CAM system. The 3D models were transformed into *.stl files and then the manufacturing process of the real structures by means of the selective laser melting with the SLM Realizer 100 3D printer was made. The paper shows the porous specimens made for possible...
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Structural and Material Determinants Influencing the Behavior of Porous Ti and Its Alloys Made by Additive Manufacturing Techniques for Biomedical Applications
PublicationOne of the biggest challenges in tissue engineering is the manufacturing of porous structures that are customized in size and shape and that mimic natural bone structure. Additive manufacturing is known as a sufficient method to produce 3D porous structures used as bone substitutes in large segmental bone defects. The literature indicates that the mechanical and biological properties of scaffolds highly depend on geometrical features...
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A review: Fabrication of porous polyurethane scaffolds
PublicationThe aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical...
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Formation of Porous Structure of the Metallic Materials Used on Bone Implants
PublicationResearch on improvement of structure and fabrication methods of the bone implants are carried out for many years. Research are aimed to shape the structures, that will have a Young's modulus value similar to the value of the human bones Young's modulus. Depending on theporosity, Young's moduli can even be tailored to match the modulus of bone closer than solid metals can, thus reducing the problems associated with stress shielding...
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A facile approach to fabricate load-bearing porous polymer scaffolds for bone tissue engineering
PublicationBiodegradable porous scaffolds with oriented interconnected pores and high mechanical are load-bearing biomaterials for bone tissue engineering. Herein, we report a simple, non-toxic, and cost-effective method to fabricate high-strength porous biodegradable scaffolds, composed of a polymer matrix of polycaprolactone (PCL) and water-soluble poly (ethylene oxide) (PEO) as a sacrificial material by integrating annealing treatment,...
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Fabrication, Microstructure and High Temperature Corrosion Resistance of Porous Alloys for Solid Oxide Fuel Cells
PublicationPorous alloys find use in modern Solid Oxide Fuel Cells as the supporting structures. As they are exposed to high temperatures (> 500°C) an oxide scale forms on their surface due to high temperature corrosion phenomena. Since the ratio between the surface area and volume is much higher than for planar samples, formation of the oxide can lead to a breakaway oxidation after relatively short times. Therefore corrosion properties of...
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Experimental study of pressure rise at the evaporator of capillary pumped loop with acetone and water as working fluids
PublicationIn this work studied is the possibility of fluid pumping using capillary forces in the capillary pumped loop. Experimental and theoretical studies have been performed to understand the phenomena associated with heat transfer in porous structure of the evaporator. The capillary effect was studied during operation of two different capillary porous structures with two different working fluids, namely water and acetone. The results...
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Fabrication of Composite Polyurethane/Hydroxyapatite Scaffolds Using Solvent-Casting Salt Leaching Technique
PublicationScaffolds are porous three-dimensional structures which are used to fill bone losses and make them possible to cells to grow. Many different structural and biological properties are required from them: porosity, mechanical strength and biocompability. The present research is aimed at development of composite polyurethane/hydroxyapatite scaffolds by using the solvent-casting salt leaching method. The SEM examinations were applied...
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Preparation, characterization, and manufacturing of new polymeric materials for 3D printing for medical applications
PublicationThis work concerns the synthesis, formation, and characteristics of new filaments for 3D printing in FDM™/FFF technology for medical purposes. Two types of filaments were developed, i.e. degradable polyurethane and biodegradable polylactide-starch. The influence of the 3D printing process on selected filament properties was investigated. A detailed analysis of the filament formation process by the extrusion method was carried out,...
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Computational analysis of power-law fluids for convective heat transfer in permeable enclosures using Darcy effects
PublicationNatural convection is a complex environmental phenomenon that typically occurs in engineering settings in porous structures. Shear thinning or shear thickening fuids are characteristics of power-law fuids, which are non-Newtonian in nature and fnd wide-ranging uses in various industrial processes. Non-Newtonian fuid fow in porous media is a difcult problem with important consequences for energy systems and heat transfer. In this...
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Synthesis and modification of reduced graphene oxide aerogels for biofuel cell applications
PublicationWe have carried out the preparation of reduced graphene oxide aerogels using eco-friendly method that is based on the Hummers method of graphite oxidation without the use of NaNO3 that produces toxic gases. To obtain a porous 3D structure of reduced graphene oxide, we performed the hydrothermal reduction at elevated temperature. We also prepared the rGO aerogel/CNT composite using multiwalled carbon nanotubes as linkers. The rGO...
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Deposition of phosphate coatings on titanium within scaffold structure
PublicationPurpose: Existing knowledge about the appearance, thickness, and chemical composition of phosphate coatings on titanium inside porous structures is insufficient. Such knowledge is important for the design and fabrication of porous implants. Methods: Metallic scaffolds were fabricated by selective laser melting of 316L stainless steel powder. Phosphate coatings were deposited on Ti sensors placed either outside the scaffolds or...
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Materiał węglowy ptrzymany na bazie karbonizowanego chitozanu domieszkowanego platyną = CARBON MATERIAL RECEIVED THROUGH CARBONIZATION OF CHITOSAN DOPED WITH PLATINUM
PublicationThe aim of this work was to investigate the impact of porous carbons with high nitrogen content onthe platinum catalyst performance properties. The system may be applied as well as cathodic catalyst for oxygenreduction in microbial fuel cells.We report a simple route for preparation of dispersed Platinum on the carbon support. Chitosan powder wasprotonated using aqueous solution of organic acid. The water from the pores was removed...
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Plasma-Based Deposition and Processing Techniques for Optical Fiber Sensing
PublicationPlasma-based techniques are widely applied for well-controlled deposition, etching or surface functionalization of a number of materials. It is difficult to imagine fabrication of novel microelectronic and optoelectronic devices without using plasma-enhanced deposition of thin films, their selective etching or functionalization of their surfaces for subsequent selective binding of chemical or biological molecules. Depending on...
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Mitigating metal-organic framework (MOF) toxicity for biomedical applications
PublicationMetal-organic frameworks (MOFs) are a novel class of crystalline porous materials, consisting of metal ions and organic linkers. These hybrid materials are highly porous and have a large specific surface area, making them of great interest for applications in gas separation, energy storage, biomedical imaging, and drug delivery. As MOFs are being explored for biomedical applications, it is essential to comprehensively assess their...
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Flow cytometric approach to evaluate the impact of hydro-technical concrete compounds’ release to the freshwater microbiome
PublicationThe aim of this research was to test the potential of applying a flow cytometric procedure to evaluate the impact of concrete compounds’ release to the freshwater microbiome. Cells from the collected samples were stained with a fluorogenic redox indicator dye that measures the redox potential of microbial cells. This novel approach was combined with the assessment of microorganisms’ penetration into the internal structures of concrete...
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On the necessity of experimental verification of numerical results in biomedical applications
PublicationPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can be easily produced by stereolitography techniques, e.g. selective laser melting (SLM). Numerical techniques, like finite element method (FEM) have great potential in testing new, even the most sophisticated designs, according to their mechanical properties, i.e. strength or stiffness. However, due to different...
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Microporous N-Doped Carbon Obtained from Salt Melt Pyrolysis of Chitosan toward Supercapacitor and Oxygen Reduction Catalysts
PublicationThe direct carbonization of low-cost and abundant chitosan biopolymer in the presencesalt eutectics leads to highly microporous, N-doped nanostructures. The microporous structureeasily manufactured using eutectic mixture (ZnCl2 -KCl) and chitosan. Potassium ions here can act as an intercalating agent, leading to the formation of lamellar carbon sheets, whereas zinc chloride generates significant porosity. Here, we present an efficient...
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Wykorzystanie wiązań niekowalencyjnych do otrzymywania jedno- i dwuskładnikowych struktur supramolekularnych
PublicationPrzedstawiona rozprawa doktorska dotyczy badań nad wykorzystaniem oddziaływań międzycząsteczkowych do projektowania i syntezy uporządkowanych struktur krystalicznych, ze szczególnym uwzględnieniem wiązań halogenowych i chalkogenowych jako stosunkowo nowych i bardzo atrakcyjnych z punktu widzenia inżynierii kryształu. Praca podzielona jest na kilka części. Pierwsza z nich stanowi wstęp teoretyczny obejmujący opis, założenia oraz...
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Implementation of Hermite-Ritz method and Navier’s Technique for Vibration of Functionally Graded Porous Nanobeam Embedded in Winkler-Pasternak Elastic Foundation Using bi-Helmholtz type of nonlocal elasticity
PublicationPresent study is devoted to investigating the vibration characteristics of Functionally Graded (FG) porous nanobeam embedded in an elastic substrate of Winkler-Pasternak type. Classical beam theory (CBT) or Euler-Bernoulli beam theory (EBT) has been incorporated to address the displacement of the FG nanobeam. Bi-Helmholtz type of nonlocal elasticity is being used to capture the small scale effect of the FG nanobeam. Further, the...
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The use of lightweight aggregate saturated with PCM as a temperature stabilizing material for road surfaces.
PublicationThis paper presents the possibility of adding lightweight building aggregates to increase the stability – mechanical as well as thermal - of constructions and road objects. This stability can be achieved through saturating the porous granules of aggregate with a phase-change material (PCM) that allows the accumulation of solar heat. Intense solar radiation, especially during the summer, can cause the asphalt on road surfaces, bridges...
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Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti13Nb13Zr Alloy
PublicationTitanium implants are commonly used because of several advantages, but their surface modification is necessary to enhance bioactivity. Recently, their surface coatings were developed to induce local antibacterial properties. The aim of this research was to investigate and compare me-chanical properties of three coatings: multi-wall carbon nanotubes (MWCNTs), bi-layer composed of an inner MWCNTs layer and an outer TiO2 layer, and...
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Nonlocal elasticity analysis of moderately thick porous functionally graded plates in a hygro-thermal environment
PublicationThis work performs a novel quasi three-dimensional (3D) bending analysis for a moderately thick functionally graded material (FGM) made of nanoceramics and metal powders, in presence of porosities due to some incorrect manufacturing processes. Such porosities can appear within the plate in two forms, namely, even and uneven distributions. The modeled system assumes a polymer matrix where both shear and transverse factors coexist....
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Synthesis of highly crystalline photocatalysts based on TiO2 and ZnO for the degradation of organic impurities under visible-light irradiation
PublicationA TiO2–ZnO binary oxide system (with molar ratio TiO2:ZnO = 8:2) was synthesized by a hydrothermal method, assisted by calcination at temperatures of 500, 600 and 700 °C, using zinc citrate as the precursor of ZnO. The morphology (SEM, TEM), crystalline structure (XRD, Raman spectroscopy), diffuse reflectance spectra (DRS), chemical surface composition (EDXRF), porous structure parameters (low-temperature N2 sorption) and characteristic...
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Evolution of Edges and Porosity of Urban Blue Spaces: A Case Study of Gdańsk
PublicationCurrent waterfront studies focus mainly on a land-based perspective, failing to include the water side. Water is, however, not just a resource for port and industrial purposes and an edge to the waterfront; it is also a feature of the waterfront and the complex relation between water and city. Thus, the article suggests that water-land edges need to be re-contextualised, taking into consideration also their shape, functionality,...
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Port Cities within Port Regions: Shaping Complex Urban Environments in Gdańsk Bay, Poland
PublicationPort cities located within various metropolitan or functional regions face very different development scenarios. This applies not only to entire municipalities but also to particular areas that play important roles in urban development—including ports as well as their specialized parts. This refers also to the various types of maritime industries, including the processing of goods, logistics operations, shipbuilding, or ship repairing,...
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Temperature distribution of supercapacitors prepared by various technologies
PublicationSupercapacitors, also known by different names such as electrostatic double-layer capacitors (EDLCs) or ultra-capacitors, are electrical storage devices still in development. These devices require fast and reliable methods of assessing their state-of-health. Thermographic imaging is a method which can be applied with this aim due to its popularity, and the high negative impact of overheating on a supercapacitor’s parameters. Moreover,...
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Molecular Design Using Selected Concentration Effects in Optically Activated Fluorescent Matrices
PublicationMolecular physics plays a pivotal role in various fields, including medicine, pharmaceuticals, and broader industrial applications. This study aims to enhance the methods for producing specific optically active materials with distinct spectroscopic properties at the molecular level, which are crucial for these sectors, while prioritizing human safety in both production and application. Forensic science, a significant socio-economic...
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PLA–Potato Thermoplastic Starch Filament as a Sustainable Alternative to the Conventional PLA Filament: Processing, Characterization, and FFF 3D Printing
PublicationThe growing popularity of the fused filament fabrication (FFF) 3D printing technology in science, industry, and in-home use is associated with an increased demand for high-quality polymer filaments. This study presents an in-depth characterization and analysis of a self-made bio-based polylactide (PLA)/thermoplastic potato starch (TPS) filament dedicated for the FFF 3D printing technology. The obtained results were compared with...
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N-doped carbon materials as electrodes for highly stable supercapacitors
PublicationThis article reports a strategy to use nitrogen-doped carbon materials as electrodes for supercapacitors. Depending on the carbon precursor, the porous structure is changed with specific surface area reached up to 2270 m2 g−1. The capacitance of carbon materials used as electrodes is related strictly to pore size. The microstructure and nitrogen functionalities enable a high capacitance (327 F g−1) and cycle durability. The nanoporous...
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The role of aluminium in metal–organic frameworks derived carbon doped with cobalt in electrocatalytic oxygen evolution reaction
PublicationWater electrolysis is one of the most crucial processes in the development of new energy sources, where ultra-clean fuel is produced - hydrogen. Oxygen evolution reaction (OER) is the sluggish process of overall water splitting. Therefore, this study presents the design, characterization and electrochemical study of cobalt-based electrocatalysts embedded into porous carbons derived from an Al-metal–organic...
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The influence of the Cu2O deposition method on the structure, morphology and photoresponse of the ordered TiO2NTs/Cu2O heterojunction
PublicationThe increased interest in highly ordered titania structures exhibiting tubular shape that could be directly formed onto the stable substrate is related with the intensive research on their modification enabling absorption of light within the wide solar spectrum and its further conversion into electric or chemical energy. Among others, formation of uniform 3D heterojunctions based on the TiO2 nanotubes attracts attention since porous...
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Tribological model of porous bearings with particular attention given to the lubricant lubricity
PublicationThe friction and wear problems, accompanying all the tribological systems, lead to reduced service life. In order to prevent such situation, it is necessary to maintain fluid friction, which improves durability of all friction nodes in a tribological system. In the paper, the tribological system consists of porous bearings and the model deals with their weakest spots - the oil outflow points in the porous wall. A kinetic model...
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Glass-ceramic joining of Fe22Cr porous alloy to Crofer22APU: interfacial issues and mechanical properties
PublicationThis work deals with the joining of porous Fe22Cr ferritic stainless steel to a dense Crofer22APU plate by using a silica-based, Ba-containing glass-ceramic. The chemical and interfacial stability and the mechanical properties of the joints were evaluated before and after thermal ageing at 700 ◦C for 500hrs. The sintering behaviour of the glass was assessed by using heating stage microscopy (HSM) to study the influence of a porous...
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Polymeric porous membranes as solid support and protective material in microextraction processes: A review
PublicationPolymeric porous membranes have proven to be a versatile and efficient material for microextraction processes. In analytical practice, they are used both as a solid support and as a protective medium for improved sample preparation in various analytical applications. Polymeric porous membranes offer unique advantages in microextraction due to their large surface area and controllable pore size, eliminating interfering effects from...
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A comprehensive study on nonlinear hygro-thermo-mechanical analysis of thick functionally graded porous rotating disk based on two quasi three-dimensional theories
PublicationIn this paper, a highly efficient quasi three-dimensional theory has been used to study the nonlinear hygro-thermo-mechanical bending analysis of very thick functionally graded material (FGM) rotating disk in hygro-thermal environment considering the porosity as a structural defect. Two applied quasi three-dimensional displacement fields are assumed in which the strain along the thickness is not zero unlike most of the other plate...
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High temperature corrosion evaluation and lifetime prediction of porous Fe22Cr stainless steel in air in temperature range 700–900 °C
PublicationThis work describes a high temperature corrosion kinetics study of ~30% porous Fe22Cr alloys. The surface area of the alloy (~0.02 m2 g-1) has been determined by tomographic microscopy. The weight gain of the alloys was studied by isothermal thermogravimetry in the air for 100 hours at 700 - 900 °C. Breakaway oxidation was observed after oxidation at 850 °C (~100 hours) and 900 °C (~30 hours). The lifetime prediction shows the...
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Novel Research on Biomedical Polyurethanes
PublicationThe variety of mechanical properties characterizes properly designed PURs. They may be biocompatible and reveal compatibility with blood, making them attractive materials for the fabrication of tissue scaffolds; however, like all synthetic materials, PURs don’t reveal sufficient biocompatibility. PURs may undergo certain chemical modifications (e.g., 1,4:3,6-dianhydro-D-sorbitol, ascorbic acid (AA), growth factors, covering with...
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Advancements in the Additive Manufacturing of Magnesium and Aluminum Alloys through Laser-Based Approach
PublicationComplex structures can now be manufactured easily utilizing AM technologies to meet the pre-requisite objectives such as reduced part numbers, greater functionality, and lightweight, among others. Polymers, metals, and ceramics are the few materials that can be used in AM technology, but metallic materials (Magnesium and Aluminum) are attracting more attention from the research and industrial point of view. Understanding the role...
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Numerical modelling of the mesofracture process of sintered 316L steel under tension using microtomography
PublicationThis paper concerns numerical modelling of the deformation process, taking into account the local fracture of porous 316L sinters at the mesoscopic scale using the finite element method. Calculations are performed with the use of geometrical models, to map the realistic shape of the porous mesostructure of the material, obtained by means of computed microtomography. The microtomographic device has limited and insufficient measurement...
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Preparation of Hydrogen Electrodes of Solid Oxide Cells by Infiltration: Effects of the Preparation Procedure on the Resulting Microstructure
PublicationIn this work, the infiltration technique was used to produce hydrogen electrodes for solid oxide cells. Different infiltration methodologies were tested in order to try to shorten the infiltration cycle time. The porous scaffolds used for infiltration were based on highly porous yttria-stabilized zirconia (YSZ) obtained by etching the reduced nickel from the Ni-YSZ cermet in HNO3 acid. The support had a complex structure which...
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Pool boiling of nanofluids on rough and porous coated tubes: experimental and correlation
PublicationThe paper deals with pool boiling of water-Al2O3 and water- Cu nanofluids on rough and porous coated horizontal tubes. Commercially available stainless steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate the test heater. The tube surface was roughed with emery paper 360 or polished with abrasive compound. Aluminium porous coatings of 0.15 mm thick with porosity of about 40% were produced by...