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Search results for: GRAPHENE SHEET, NANOCOMPOSITE, POLYURETHANE, SHAPE MEMORY
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Fe3O4/graphene oxide/Fe4[Fe(CN)6]3 nanocomposite for high performance electromagnetic interference shielding
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Conductive Thermoplastic Polyurethane Nanocomposite Foams Derived from a Cellulose/MWCNTs Aerogel Framework: Simultaneous Enhancement of Piezoresistance, Strength, and Endurance
PublicationHigh conductivity and excellent mechanical properties of composite polymers favors their application as piezoresistive strain sensors. Nonetheless, it is difficult to develop composite polymers with desirable piezoresistance, mechanicaland durable properties. Herein, we developed conductive cellulose/MWCNTs aerogel using the freeze-drying technique. Besides, we explored the application of the highly-sensitive piezoresistive polymer...
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Controllable Synthesis of 3D Hollow-Carbon-Spheres/Graphene-Flake Hybrid Nanostructures from Polymer Nanocomposite by Self-Assembly and Feasibility for Lithium-Ion Batteries
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Mechanistic insights into the reactive radicals-assisted degradation of sulfamethoxazole via calcium peroxide activation by manganese-incorporated iron oxide–graphene nanocomposite: Formation of radicals and degradation pathway
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Application of Box–Behnken design in the optimization of a simple graphene oxide/zinc oxide nanocomposite-based pipette tip micro-solid phase extraction for the determination of Rhodamine B and Malachite green in seawater samples by spectrophotometry
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Electroactive polymer/graphene oxide nanostructured composites; evidence for direct chemical interactions between PEDOT and GOx
PublicationThis work concerns electrochemical synthesis of nanocomposites consisting of conducting polymer and reduced graphene oxide (rGOx) as electrode materials for supercapacitors. The electrosynthesis was performed in an aqueous solution of the 3,4-ethylenedioxytiophene (EDOT) monomer and graphene oxide (GOx) without supporting electrolyte. The amount of GOx was optimized to obtain the best electrochemical performance of the nanocomposite...
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Development of polyurethanes for bone repair
PublicationThe purpose of this paper is to review recent developments on polyurethanes aimed at the design, synthesis, modifications, and biological properties in the field of bone tissue engineering. Different polyurethane systems are presented and discussed in terms of biodegradation, biocompatibility and bioactivity. A comprehensive discussion is provided of the influence of hard to soft segments ratio, catalysts, stiffness and hydrophilicity...
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Continuum contact model for friction between graphene sheets that accounts for surface anisotropy and curvature
PublicationUnderstanding the interaction mechanics between graphene layers and co-axial carbon nanotubes (CNTs) is essential for modeling graphene and CNT-based nanoelectromechanical systems. This work proposes a new continuum contact model to study interlayer interactions between curved graphene sheets. The continuum model is calibrated and validated using molecular dynamics (MD) simulations. These are carried out employing the reactive...
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Eco-Friendly Electromagnetic Interference Shielding Materials from Flexible Reduced Graphene Oxide Filled Polycaprolactone/Polyaniline Nanocomposites
PublicationHybrid nanocomposites have the unique ability of enhancing material properties due to the existing synergistic effect of the fillers. In this study, the authors report such an eco-friendly hybrid nanocomposite comprising of polyaniline and reduced graphene oxide in polycaprolactone. The conducting polyaniline improved the processability of polycaprolactone, and the final composites were prepared by incorporating graphene oxide...
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Mechanical analysis of eccentric defected bilayer graphene sheets considering the van der Waals force
PublicationIn this article, we have tried to simulate nonlinear bending analysis of a double-layered graphene sheet which contains a geometrical imperfection based on an eccentric hole. The first-order shear deformation theory is considered to obtain the governing equations. Also, the nonlinear von Kármán strain field has been assumed in order to obtain large deformations. Whereas the double-layered graphene sheet has been considered, the...
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Tailoring Graphene to Achieve Negative Poisson's Ratio Properties
PublicationGraphene can be made auxetic through the introduction of vacancy defects. This results in the thinnest negative Poisson's ratio material at ambient conditions known so far, an effect achieved via a nanoscale de-wrinkling mechanism that mimics the behavior at the macroscale exhibited by a crumpled sheet of paper when stretched.
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The effect of boron concentration on the electrical, morphological and optical properties of boron-doped nanocrystalline diamond sheets: Tuning the diamond-on-graphene vertical junction
PublicationIn this paper, the effect of boron doping on the electrical, morphological and structural properties of free-standing nanocrystalline diamond sheets (thickness ~ 1 μm) was investigated. For this purpose, we used diamond films delaminated from a mirror-polished tantalum substrate following a microwave plasma-assisted chemical vapor deposition process, each grown with a different [B]/[C] ratio (up to 20,000 ppm) in the gas phase....
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Microstructure–Property Relationship of Polyurethane Foams Modified with Baltic Sea Biomass: Microcomputed Tomography vs. Scanning Electron Microscopy
PublicationIn this paper, novel rigid polyurethane foams modified with Baltic Sea biomass were compared with traditional petro-based polyurethane foam as reference sample. A special attention was focused on complex studies of microstructure, which was visualized and measured in 3D with high-resolution microcomputed tomography (microCT) and, as commonly applied for this purpose, scanning electron microscopy (SEM). The impact of pore volume,...
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Preparation and characterization of rigid polyurethane-polyglycerolnanocomposite foams
PublicationThis work reports on the preparation of polyurethane-polyisocyanurate (PUR-PIR) foams containing different polyglycerols and layered silicate nanoclays. The rigid polyurethane foams were obtained in a laboratory scale, in a single step method, from a two-component system with a NCO to OH groups ratio equal to two. The reaction mixture consisted of the proper amounts of a commercial oligoetherpolyol, polyglycerol, catalysts, water,...
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Nonlinear Viscoelastic Properties of Polyurethane Nanocomposites
PublicationIn recent years, the nonlinear viscoelastic behaviors of elastomeric nanocomposites have been examined, especially for a wide range of rubbery composite (including natural rubber) materials. This chapter describes the influence of fillers and nanofillers on the nonlinear viscoelastic properties of elastomeric polyurethane systems. These filled elastomers (similar to the classic natural rubber reinforced elastomers), also exhibit...
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„Jeśli my zapomnimy, kto będzie pamiętał?". Dzieło sztuki jako manifestacja postpamięci
PublicationTekst jest próbą ujęcia relacji między postpamięcią (lub inaczej ujmując - „pamięcią zastępczą”) a sztuką, przy czym szczególny akcent położono na sztuki wizualne. Dokonano analizy dzieł artystów młodszego pokolenia, podejmujących temat pamięci o Szoa (między innymi Libera, Bałka, Żmijewski, do pewnego stopnia Betlejewski), traktując je jako formy manifestacji postpamięci. Wychodząc z założenia, że analiza zjawisk artystycznych...
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Influence of Surface-Modified Montmorillonite Clays on the Properties of Elastomeric Thin Layer Nanocomposites
PublicationIn recent years, polyurethane nanocomposites have attracted more attention due to the massive demand for materials with increasingly exceptional mechanical, optical, electrical, and thermal properties. As nanofillers have a high surface area, the interaction between the nanofiller and the polymer matrix is an essential issue for these materials. The main aim of this study is to validate the impact of the montmorillonite nanofiller...
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MnWO4/reduced graphene oxide-based electrochemical sensing platform for simultaneous detection of catechol and resorcinol
Publicationn this study, a novel electrochemical sensor for accurate and sensitive catechol determination was demonstrated employing a screen-printed graphite electrode (SPGE) modified with MnWO4/reduced graphene oxide (MnWO4/rGO) nanocomposite. The MnWO4/rGO nanocomposite has been successfully prepared by using hydrothermal technique, and it was then characterized using several microscopic and spectroscopic methods (XRD, FE-SEM, and EDS)....
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Multimodal Genetic Algorithm with Phase Analysis to Solve Complex Equations of Electromagnetic Analysis
PublicationIn this contribution, a new genetic-algorithm-based method of finding roots and poles of a complex function of a complex variable is presented. The algorithm employs the phase analysis of the function to explore the complex plane with the use of the genetic algorithm. Hence, the candidate regions of root and pole occurrences are selected and verified with the use of discrete Cauchy's argument principle. The algorithm is evaluated...
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Rigid polyurethane foams modified with selected layered silicate nanofillers
PublicationThe aim of this study was to investigate the effect of three different nanofillers on the properties of rigid polyurethane foams, which were prepared by a one-step, laboratory-scale method from a two-component system at the ratio of NCO groups to OH groups equaled to 2. The reaction mixture consisted of the proper amounts of the commercial oligoether polyol, catalysts, water, nanoclays, and polymeric diphenylmethane diisocyanate....
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Experimental and numerical studies on the mechanical response of a piezoelectric nanocomposite-based functionally graded materials
PublicationThis work presents an experimental study of piezoelectric structures reinforced by graphene platelets, based on the concept of the functionally graded materials (FGMs). The assumed model is a rectangular beam/plate and the composition is due to the Halpin-Tsai rule. The model is also simulated in the Abaqus software which is the first time that such a structure has been modelled in an FEM package. In addition, a mathematical model...
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Adsorption-assisted transport of water vapour in super-hydrophobic membranes filled with multilayer graphene platelets
PublicationThe effects of confinement of multilayer graphene platelets in hydrophobic microporous polymeric membranes are here examined. Intermolecular interactions between water vapour molecules and nanocomposite membranes are envisaged to originate assisted transport of water vapour in membrane distillation processes when a suitable filler-polymer ratio is reached. Mass transport coefficients are estimated under different working conditions,...
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Thermal and Mechanical Properties of Microporous Polyurethanes Modified with Reduced Graphene Oxide
PublicationMicroporous polyurethanes (MPU) were modified by adding 0.25%–1.25 wt% of reduced graphene oxide (RGO). The materials were prepared without solvent via in situ polymerization. From a technological point of view, it is very important to obtain functional materials by using reacting compounds only. The thermal characteristics of obtained MPU were investigated using TGA, DSC, and DMA techniques. In comparison to nonmodified microporous...
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Chemically reduced graphene oxide based aerogels - Insight on the surface and textural functionalities dependent on handling the synthesis factors
PublicationEfficient adjusting of reduced graphene oxide aerogels properties requires information about experimental factor-aerogel property relationship. In this work, the reduced graphene oxide aerogels surface and textural functionalities in relation to precursor concentration, gelation time and hydrogel freezing temperature were studied in detail, with the use of dynamic adsorption method of gaseous organic probes and experimental design....
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Thermal-Resistant Polyurethane/Nanoclay Powder Coatings: Degradation Kinetics Study
PublicationIn the present study, thermal degradation kinetics of polyurethane (PU) powder coatings reinforced with organo-modified montmorillonite (OMMT) was investigated. PU nanocomposites were prepared in different concentrations of 1, 3, and 5 wt.% of OMMT via the extrusion method. The microstructure of the nanocomposites was observed by scanning electron microscope (SEM) illustrating uniform dispersion of OMMT nano-clay platelets in the...
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Titanium lanthanum three oxides decorated magnetic graphene oxide for adsorption of lead ions from aqueous media
PublicationThe current study presents a viable and straightforward method for synthesizing titanium lanthanum three oxide nanoparticles (TiLa) and their decoration onto the ferrous graphene oxide sheets to produce FeGO-TiLa as efficient magnetic adsorbent. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibration sample magnetometer (VSM) were used to evaluate...
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On noncausal weighted least squares identification of nonstationary stochastic systems
PublicationIn this paper, we consider the problem of noncausal identification of nonstationary, linear stochastic systems, i.e., identification based on prerecorded input/output data. We show how several competing weighted (windowed) least squares parameter smoothers, differing in memory settings, can be combined together to yield a better and more reliable smoothing algorithm. The resulting parallel estimation scheme automatically adjusts...
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Allergic reactions as a defense of the organism to the influence of implants components made of stainless steel
PublicationDue to the increasing number of cases of hypersensitivity caused by direct contact with metals, as well as the increasing demand for implants in humans all ages numerous studies on the effects of the impact of implant components are being carried out. The paper presents the phenomenon of etiology of allergy in general terms and in relation to the biomaterials used in medicine. There have been characterized in terms of impact on...
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Allergic Reactions as a Defense of the Organism to the Influence of Implants Components Made of Stainless Steel
PublicationDue to the increasing number of cases of hypersensitivity caused by direct contact with metals, as well as the increasing demand for implants in humans all ages numerous studies on the effects of the impact of implant components are being carried out. The paper presents the phenomenon of etiology of allergy in general terms and in relation to the biomaterials used in medicine. There have been characterized in terms of impact on...
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Clays as Inhibitors of Polyurethane Foams’ Flammability
PublicationPolyurethanes are a very important group of polymers with an extensive range of applications in different branches of industry. In the form of foams, they are mainly used in bedding, furniture, building, construction, and automotive sectors. Due to human safety reasons, these applications require an appropriate level of flame retardance, often required by various law regulations. Nevertheless, without the proper modifications,...
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Real‐Time PPG Signal Conditioning with Long Short‐Term Memory (LSTM) Network for Wearable Devices
PublicationThis paper presents an algorithm for real‐time detection of the heart rate measured on a person’s wrist using a wearable device with a photoplethysmographic (PPG) sensor and accelerometer. The proposed algorithm consists of an appropriately trained LSTM network and the Time‐Domain Heart Rate (TDHR) algorithm for peak detection in the PPG waveform. The Long Short‐Term Memory (LSTM) network uses the signals from the accelerometer...
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Research on Linear Actuators for Active Foil Bearings
PublicationActive foil bearings are a kind of gas foil bearing. They contain actuators which allow for modification of the bearing sleeve size and the shape of the lubrication gap. Rotor vibrations can be actively controlled by these changes. It is possible, among other things, to reduce the starting torque, control the vibration amplitude at different speeds and improve operational safety. Prototypes of active foil bearings are being developed...
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BIOMATERIALS AND IMPLANTS IN CARDIAC AND VASCULAR SURGERY - REVIEW
PublicationCurrently, on prosthesis in cardiac blood vessels and heart valves are used materials of animal or synthetic origin. For animal materials include, among others pericardial sac in which is the heart. Materials such as this (natural) are characterized by a remarkable biocompatibility within the human body, but their main disadvantage is the relatively low durability. In turn, synthetic materials, which include the austenitic chromium-nickel-molybdenum...
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Boron-doped carbon nanowalls for fast and direct detection of cytochrome C and ricin by matrix-free laser desorption/ionization mass spectrometry
PublicationDetecting proteins via surface assisted laser desorption/ionization mass spectrometry (SALDI-MS) method is still highly challenging, and only few examples of nanomaterials have been demonstrated to perform such detection so far. In this study, carbon nanowalls (CNWs), vertically aligned graphene sheet-based materials, presenting specific morphology, dimensions, and boron doping levels have shown improved performances for both qualitative...
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Graphene oxide aerogels for adsorptive separation of aromatic hydrocarbons and cycloalkanes
PublicationEfficient separation of benzene and cyclohexane has critical importance for production of commodity chemicals, and is one of the most challenging separations in the industry. Physisorption by recyclable, porous solids has a significant potential in substituting energy-intensive azeotropic or extractive distillation methods. Reduced graphene oxide aerogels (rGOAs) are emerging materials holding great promise for connecting unique...
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Survey of Methodologies, Approaches, and Challenges in Parallel Programming Using High-Performance Computing Systems
PublicationThis paper provides a review of contemporary methodologies and APIs for parallel programming, with representative technologies selected in terms of target system type (shared memory, distributed, and hybrid), communication patterns (one-sided and two-sided), and programming abstraction level. We analyze representatives in terms of many aspects including programming model, languages, supported platforms, license, optimization goals,...
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Uproszczone metody obliczania wyboczenia silosów z blachy falistej wzmocnionych słupami na podstawie analizy MES i wyników doświadczalnych
PublicationRozprawa doktorska dotyczy zagadnienia stateczności i nośności granicznej stalowych silosów z płaszczem z blachy falistej wzmocnionych pionowymi słupami. Przeprowadzono zaawansowane analizy numeryczne MES oraz badania doświadczalne dotyczące wyboczenia/stateczności analizowanych silosów. Analizy numeryczne zostały przeprowadzone w zakresie liniowej oraz nieliniowej analizy stateczności, z uwzględnieniem wstępnych imperfekcji geometrycznych...
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A universal NDT method for examination of low energy impact damage in CFRP with the use of TLC film
PublicationThe article presents an attempt to use a sheet of laminated thermochromic liquid crystal film (TLC film) for non-destructive testing of the impact damage (energy values: 1J, 2J, 3J and 4J) in carbon fibre-reinforced polymer (CFRP). This is a new, alternative NDT approach based on the thermo-optical effect. The main advantages of this method are a) the low cost of TLC film, b) the low cost of recording devices due to the usage of...
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Removal of lead ions from wastewater using lanthanum sulfide nanoparticle decorated over magnetic graphene oxide
PublicationIn this study, the new lanthanum sulfide nanoparticle (La2S3) was synthesized and incorporated onto magnetic graphene oxide (MGO) sheets surface to produce potential adsorbent (MGO@LaS) for efficient removal of lead ions (Pb2+) from wastewater. The synthesized MGO@LaS adsorbent was characterized using Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The...
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Reactive extrusion of bio-based polymer blends and composites – Current trends and future developments
PublicationReactive extrusion is a cost-effective and environmentally-friendly method to produce new materials with enhanced performance properties. At present, reactive extrusion allows in-situ polymerization, modification/functionalization of polymers or chemical bonding of two (or more) immiscible phases, which can be carried out on commonly used extrusion lines. Although reactive extrusion has been known for many years, its application...
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Effects of preheating on laser beam–welded NSSC 2120 lean duplex steel
PublicationDuplex stainless steels show sustainable alternative for the conventional austenitic grades, with higher strength, higher resistance against stress corrosion cracking, and lower purchase cost. Thus, duplex stainless steel gains more attention in construction, oil and gas, and chemical industries. Among duplex stainless steels, low nickel and low molybdenum alloyed lean duplex stainless steel are a cost-efective substitution of...
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Smart Materials in Architecture: Useful Tools with Practical Applications or Fascinating Inventions for Experimental Design?
PublicationFor at least several decades smart or so-called intelligent materials, being the result of great advancements in material engineering, appear in architecture in different applications. Most of them are called "smart" because of their inherent properties: a real-time response to environmental stimuli. There are also those considered to be "smart" due to smart design: their original structure or the composition of their materials...
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Seismic performance evaluation of steel buckling-restrained braced frames including SMA materials
PublicationThe permanent deformation of the building after seismic excitations can be determined by the Maximum Residual Interstory Drift Ratio (MR-IDR), which may be used for measuring the damage states. Low-post yield stiffness of the steel buckling-restrained braced frame (BRBF) makes this system vulnerable to large MR-IDR after a severe earthquake event. To overcome this issue, this paper investigates the seismic limit state performances...
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Sustainability of Civil Structures through the Application of Smart Materials: A Review
PublicationEvery year, structural flaws or breakdowns cause thousands of people to be harmed and cost billions of dollars owing to the limitations of design methods and materials to withstand extreme earthquakes. Since earthquakes have a significant effect on sustainability factors, there is a contradiction between these constraints and the growing need for more sustainable structures. There has been a significant attempt to circumvent...
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Enhancing seismic performance of rigid and semi-rigid connections equipped with SMA bolts incorporating nonlinear soil-structure interaction
PublicationNowadays, using smart connections can improve the performance of buildings with some recentering features that are from the superelastic behavior of Shape Memory Alloys (SMAs). It seems that there is different rigidity between the designed connection and the real one in Steel Moment-Resisting Frames (SMRFs), which can be considered as a problematic issue due to the importance of connections in seismic performance assessment. This...
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Enhancing seismic performance of buckling-restrained brace frames equipped with innovative bracing systems
PublicationNowadays, to improve the performance of conventional bracing systems, in which, buckling in the pressure loads is the main disadvantage, the buckling-restrained brace (BRB) is introduced as a solution. In this study, the performance of the BRB system was improved with innovative lateral-resisting systems of double-stage yield buckling-restrained brace (DYB), and a combination of DYB improved with shape memory alloy (SMA) materials...