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Search results for: REDUCED GRAPHENE OXIDE
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The properties of reduced Bi-Ge-O glasses for thermoelectric devices
PublicationThe bismuth-germanate glasses have been investigated to examine their applicability for thermoelectric devices. In order to increase their electrical conductivity, the 25Bi2O3–75GeO2 glass samples have been reduced at 340-380°C for 10 hours in hydrogen. It has been shown that such heat treatment in H2 leads to the reduction of metal ions Bi3+ and Ge4+ into neutral atoms and the formation of metal grains both in an amorphous glass...
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A Goal-Oriented Error Estimator for Reduced Basis Method Modeling of Microwave Devices
PublicationThis letter proposes a novel a-posteriori error estimator suitable for the reduced order modeling of microwave circuits. Unlike the existing error estimators based on impedance function residuals, the new one exploits the residual error associated with the computation of the scattering matrix. The estimator can be effectively used in the Reduced Basis Method (RBM) to automatically generate reduced-order models. The results of numerical...
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Enhanced gas sensing by graphene-silicon Schottky diodes under UV irradiation
PublicationThe effect of ultraviolet (UV) or blue irradiation on graphene/n-doped silicon Schottky junctions toward gas sensing was investigated. Schottky diodes were subjected to oxidizing nitrogen dioxide (NO2, 1–3 ppm) and reducing tetrahydrofuran (THF, 50–200 ppm), showing significantly different responses observed on the currentvoltage (I-V) characteristics, especially under UV light (275 nm). NO2 affected the resistive part of the forward region...
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Development of biocompatible iron oxide-silicon oxide core-shell nanoparticles as subcellular delivery platform for glucosamine-6-phosphate synthase inhibitors
PublicationIn order to develop the preparation of iron oxide-silica coreshell nanoparticles (CSNPs), thesis deeply explores the cetyltrimethylammonium (CTA+) directed silica coating methods of the oleic-acid capped iron oxide nanoparticles (OA-IONPs) initialized under near-neutral pH conditions. It is demonstrated that the initial alkaline hydrolysis of ethyl acetate in the presence of CTA+ and OA-IONPs induces an unusual ligand exchange...
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Biharmonic reduced stress.
PublicationRozpatrywane jest wieloosiowe naprężenie o biharmonicznych składowych. Aproksymuje ono m.in. naprężenie w rufowej części kadłuba statku przy regularnym falowaniu morskim. Celem pracy jest zamodelowanie tego naprężenia jednoosiowym naprężeniem zredukowanym. Dla uniknięcia zniekształcenia widma naprężenia wyznaczono biharmoniczne naprężenie zredukowane. W tym celu wykorzystano hipotezę uśrednionej energii odkształcenia postaciowego.
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A Compact Basis for Reliable Fast Frequency Sweep via the Reduced-Basis Method
PublicationA reliable reduced-order model (ROM) for fast frequency sweep in time-harmonic Maxwell’s equations by means of the reduced-basis method is detailed. Taking frequency as a parameter, the electromagnetic field in microwave circuits does not arbitrarily vary as frequency changes, but evolves on a very low-dimensional manifold. Approximating this low-dimensional manifold by a low dimension subspace, namely, reduced-basis space, gives...
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Modelling of Graphene Field-Effect Transistor for lectronic sensing applications
PublicationA top-gated Graphene Field-Effect Transistor (GFET) suitable for electronic sensing applications was modelled. The applied simulation method reproduces correctly the output transfer GFET characteristics and allows to investigate doping effect caused by different physical, chemical or biological factors. The appearance of additional charge in the system results in the shift of the current-voltage characteristic. This feature could...
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3D Hierarchical Boron-Doped Diamond-Multilayered Graphene Nanowalls as an Efficient Supercapacitor Electrode
PublicationSynthesis of stable hybrid carbon nanostructure for high-performance supercapacitor electrode with long life-cycle for electronic and energy storage devices is a real challenge. Here, we present a one-step synthesis method to produce conductive boron-doped hybrid carbon nanowalls (HCNWs), where sp2-bonded graphene has been integrated with and over a three-dimensional curved wall-like network of sp3-bonded diamond. The spectroscopic...
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An Enhanced Reduced Basis Method for Wideband Finite Element Method Simulations
PublicationIn this paper, we present a novel strategy for selecting expansion points in the reduced basis method. A single computation of the error estimator is used to select a few expansion points in the multi-parameter space simultaneously. The number of selected points is determined adaptively, based on the accuracy of the current reduced model. The reliability and efficiency of this proposed approach are illustrated by numerical tests...
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Thermoelectric properties of bismuth-antimony-telluride alloys obtained by reduction of oxide reagents
PublicationThe BieSbeTe alloys with different Bi/Sb/Te ratio were fabricated by an innovative method. For that purpose the oxide reagents were melted at high temperature, then quenched to form pellets, milled to a powder and finally reduced in hydrogen at various temperatures. Complex structures consisting of connected thin layers forming a continuous path between nano- and micrometer size grains have been obtained. The electrical conductivity,...
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A study of the kinetics of bismuth telluride synthesis by an oxide reduction method
PublicationThe kinetics of a reduction of bismuth and tellurium oxides in a hydrogen atmosphere, leading to the formation of thermoelectric bismuth telluride is investigated. The evaluation of the reaction kinetics was based on a thermogravimetric analysis performed in non-isothermal conditions. A non-parametric analysis method and the Friedman method were used for the evaluation of the data. Additionally, for a better understanding of the...
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Thermo-resonance analysis of an excited graphene sheet using a new approach
PublicationForced vibration of graphene nanoplate based on a refined plate theory in conjunction with higher-order nonlocal strain gradient theory in the thermal environment has been investigated. Regarding the higher-order nonlocal strain gradient theory, both stress nonlocality and size-dependent effects are taken into account, so the equilibrium equations which are governing on the graphene sheet have been formulated by the theory....
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Graphene-Coated PVDF Membranes: Effects of Multi-Scale Rough Structure on Membrane Distillation Performance
PublicationGraphene-coated membranes for membrane distillation have been fabricated by using a wet-filtration approach. Graphene nanoplatelets have been deposited onto PVDF membrane surfaces. Morphology and physicochemical properties have been explored to evaluate the changes in the surface topography and related effects on the membrane performance in water desalination. The membranes have been tested in membrane distillation plants by using...
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The EDS elemental maps of reduced LSCNT (SEM)
Open Research DataThe dataset includes elemental maps of La, Ce, Ti, O, Sr, Ni in La0.27Sr0.54Ce0.09Ni0.1Ti0.9O3-s produced using Pechini method sintered at 1200oC under air atmosphere and reduced at 900 for 12 h in wet H2.
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Reduced order models in computational electromagnetics (in memory of Ruediger Vahldieck)
PublicationThis paper reviews research of Ruediger Vahldieck's group and the group at the Gdansk University of Technology in the area of model order reduction techniques for accelerating full-wave simulations. The applications of reduced order models to filter design as well as of local and nested(multilevel) macromodels for solving 3D wave equations and wave-guiding problems using finite difference and finite element methods are discussed.
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Graphene hydrogels with embedded metal nanopatricles as efficient catalysts in 4-nitrophenol reduction and methylene blue decolorization
PublicationSynthesis and characterization of the graphene hydrogels with three different metallic nanoparticles, that is Au, Ag and Cu, respectively is presented. Synthesized in a one-pot approach graphene hydrogels with embedded metallic nanoparticles were tested as heterogeneous catalysts in a model reaction of 4-nitrophenol reduction. The highest activity was obtained for graphene hydrogel with Cu NPs and additional reaction of methylene...
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Electrical characteristics simulation of top-gated graphene field-effect transistor (GFET) with 10 μm x 10 μm graphene channel
Open Research DataThe presented data set is part of the research on graphene field-effect transistor (GFET) modelling. The calculations were performed with the use of GFET Tool program (https://nanohub.org/resources/gfettool DOI: 10.4231/D3QF8JK5T), which enabled simulation of the drain current (Id) vs. drain voltage (Vd) characteristics for different gate voltages (Vg)...
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Electrical characteristics simulation of top-gated graphene field-effect transistor (GFET) with 10 μm x 3 μm graphene channel
Open Research DataThe presented data set is part of the research on graphene field-effect transistor (GFET) modelling. The calculations were performed with the use of GFET Tool program (https://nanohub.org/resources/gfettool DOI: 10.4231/D3QF8JK5T), which enabled simulation of the drain current (Id) vs. drain voltage (Vd) characteristics for different gate voltages (Vg)...
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Interatomic potential suitable for the modeling of penta-graphene: Molecular statics/molecular dynamics studies
PublicationWe test the potentials available for elemental carbon, with the scope to choose the potential suitable for the modeling of penta-graphene, the latest two dimensional carbon allotrope. By using molecular statics and molecular dynamics simulations we show that there is only one potential e namely the Tersoff-type potential proposed by Erhart and Albe in 2005 e which is able to correctly describe all the important features of penta-graphene....
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Effect of graphene thickness on photocatalytic activity of TiO2-graphene nanocomposites
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Structure and thermoelectric properties of Bi–Te alloys obtained by novel method of oxide substrates reduction
PublicationA novel method of thermoelectric materials fabrication has been developed. Oxide reagents have been melted at high temperature in air, quenched, milled to powder and reduced in hydrogen to form Bi–Te alloys. Structural and thermoelectric properties of samples have been investigated depending on initial composition and temperature of reduction process. Sample 25Bi2O3–75TeO2 reduced at 340 °C for 10 h has been found to be a p-type...
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Comparison of Compact Reduced Basis Method with Different Model Order Reduction Techniques
PublicationDifferent strategies suitable to compare the performance of different model order reduction techniques for fast frequency sweep in finite element analysis in Electromagnetics are proposed and studied in this work. A Frobenius norm error measure is used to describe how good job a reduced-order model is doing with respect to the true system response. In addition, the transfer function correct behavior is monitored by studying the...
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High-performance graphene-based biosensor using a metasurface of asymmetric silicon disks
PublicationIn recent years, optical biosensors widely applicable for medical applications, have received much attention. In this paper, we propose a high-performance polarization-insensitive optical biosensor based on a graphene-dielectric metasurface. The metasurface consists of an asymmetric dielectric disk array that supports a high Q-factor Fano resonance. The provided sharp Fano resonance results in an enhanced light-matter interaction...
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An improved method for flow boiling heat transfer with account of the reduced pressure effect
PublicationIn the paper are presented the results using the authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data to investigate the sensitivity of the in-house developed model. In the work are presented the results of calculations obtained using the semi-empirical model on selected experimental flow boiling data of the refrigerants: R134a, R1234yf,...
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Solvent-Free Synthesis of Phosphonic Graphene Derivative and Its Application in Mercury Ions Adsorption
PublicationFunctionalized graphene was efficiently prepared through ball-milling of graphite in the presence of dry ice. In this way, oxygen functional groups were introduced into material. The material was further chemically functionalized to produce graphene derivative with phosphonic groups. The obtained materials were characterized by spectroscopic and microscopic methods, along with thermogravimetric analysis. The newly developed material...
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Reduced model of gyroscopic system
PublicationThe paper presents the method of model reduction for the system with gyroscopic interactions. Two methods were used to obtain the approximate discrete models of the continuous structure: the modal decomposition method and the rigid finite element method. The first approach is used for this part of a system for which it is easy to formulate orthogonality conditions, meanwhile the second one is used for other part. The method enables...
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Low-frequency noise in Au-decorated graphene–Si Schottky barrier diode at selected ambient gases
PublicationWe report results of the current–voltage characteristics and low-frequency noise in Au nanoparticle (AuNP)-decorated graphene–Si Schottky barrier diodes. Measurements were conducted in ambient air with addition of either of two organic vapors, tetrahydrofuran [(CH2)4O; THF] and chloroform (CHCl3), as also during yellow light illumination (592nm), close to the measured particle plasmon polariton frequency of the Au nanoparticle...
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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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Properties of chitosan/CuNPs coatings electrophoretically deposited on TiO2 nanotubular oxide layer of Ti13Zr13Nb alloy
PublicationCoatings based on chitosan/CuNPs (chit/CuNPs) were obtained by a one-step electrophoretic deposition (EPD) on nanotubular oxide layer of Ti13Zr13Nb alloy. The deposition was carried out for 1 min applying voltages of 10 and 20 V with and without the addition of dispersing agent (Polysorbate 20) to the suspension. The coatings obtained for the lower voltage were more uniform than for the higher voltage. By adding a dispersing agent,...
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Application of Regression Line to Obtain Specified Number of Points in Reduced Large Datasets
PublicationModern measurement techniques like scanning technology or sonar measurements, provide large datasets, which are a reliable source of information about measured object, however such datasets are sometimes difficult to develop. Therefore, the algorithms for reducing the number of such sets are incorporated into their processing. In the reduction algorithms based on the...
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Efficient and robust quadratures for isogeometric analysis: Reduced Gauss and Gauss–Greville rules
PublicationThis work proposes two efficient quadrature rules, reduced Gauss quadrature and Gauss–Greville quadrature, for isogeometric analysis. The rules are constructed to exactly integrate one-dimensional B-spline basis functions of degree p, and continuity class C^{p−k}, where k is the highest order of derivatives appearing in the Galerkin formulation of the problem under consideration. This is the same idea we utilized in Zou et al....
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Nanotubular oxide layers and hydroxyapatite coatings on ‘Ti–13Zr–13Nb’ alloy
PublicationThe presented research was aimed to determine the mechanical properties of the nanotubular oxide layer covered with hydroxyapatite coating. The Ti–13Zr–13Nb alloy was oxidised in 1M phosphoric acid with an addition of 0?5% HF for HF solution at 20 V voltage. The electrochemically assisted deposition of hydroxyapatite was performed at cyclic polarisation in NH4H2PO4 and CaCl2 solution at 80uC. The mechanical properties were determined...
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Electron attachment to hexafluoropropylene oxide (HFPO)
PublicationWe probe the electron attachment in hexafluoropropylene oxide (HFPO), C3F6O, a gas widely used in plasma technologies. We determine the absolute electron attachment cross section using two completely different experimental approaches: (i) a crossed-beam experiment at single collision conditions (local pressures of 5 × 10−4 mbar) and (ii) a pulsed Townsend experiment at pressures of 20–100 mbar. In the latter method, the cross sections...
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The effect of aluminium oxide on the reduction of cobalt oxide and thermostabillity of cobalt and cobalt oxide
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Analysis of graphene multi-strip planar guiding structures with the use of spectral domain approach
PublicationSpectral domain approach is modified and used to analyze some simple structures containing graphene strips. The modification is simple and concerns the Green’s function only. Moreover, the method is combined with the recently published root finding algorithms, which significantly improve the efficiency of the analysis. The results obtained for a simple guiding structure is verified and the field displacement effect is confirmed.
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Towards Computer-Aided Graphene Covered TiO2-Cu/(CuxOy) Composite Design for the Purpose of Photoinduced Hydrogen Evolution
PublicationIn search a hydrogen source, we synthesized TiO2-Cu-graphene composite photocatalyst for hydrogen evolution. The catalyst is a new and unique material as it consists of copper-decorated TiO2 particles covered tightly in graphene and obtained in a fluidized bed reactor. Both, reduction of copper from Cu(CH3COO) at the surface of TiO2 particles and covering of TiO2-Cu in graphene thin layer by Chemical Vapour Deposition (CVD) were...
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Ultrafast high-temperature sintering (UHS) of cerium oxide-based compound
PublicationUltrafast high-temperature sintering (UHS) is an innovative sintering technique that can densify ceramics in a few seconds, dramatically reducing the carbon footprint and firing costs. In this work, the feasibility of applying UHS in Gd-doped ceria (GDC) and GDC-Er-stabilized bismuth oxide (ESB) composite powders was investigated. At high UHS currents (22-24 A), a fully dense GDC sample with a large grain size was obtained. Nonetheless,...
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Nanotubular Ti Oxide Layers for Enhancement of Bone-Implant Bonding and Bioactivity
PublicationAbstrakt artykułu pt. ''Nanotubular Ti Oxide Layers for Enhancement of Bone-Implant Bonding and Bioactivity''. The paper describes techniques to improve the bioactivity of titanium and ehnahnce the bone-implant bonding ability by the electrochemical anodization to fabricate titania nanotubular oxide layer.
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BET specific surface area measurements of bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) structures
Open Research DataThe BET specific surface area was measured using an N2 adsorption/desorption isotherm (Micromeritics ASAP 2460, Norcross, GA, USA).
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Organic Vapor Sensing Mechanisms by Large-Area Graphene Back-Gated Field-Effect Transistors under UV Irradiation
PublicationThe gas sensing properties of graphene back-gated field-effect transistor (GFET) sensors toward acetonitrile, tetrahydrofuran, and chloroform vapors were investigated with the focus on unfolding possible gas detection mechanisms. The FET configuration of the sensor device enabled gate voltage tuning for enhanced measurements of changes in DC electrical characteristics. Electrical measurements were combined with a fluctuation-enhanced...
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Preparation of nano-tubular oxide layers on titanium alloy Ti13Nb13Zr
PublicationThe article presents results of oxidation tests and corrosion investigations of titanium alloy Ti13Nb13Zr preformed at different conditions. The oxide layers have been formed using electrochemical method in 2M H3PO4 + 0,3% HF solution for 30 min. and 1h at 20V constant voltage. The corrosion tests heve been made with poteniodynamic method in Ringer's solution at pH ranged 3 and 7. It has been shown that the nano-oxide films, which...
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Parameter values for topological chaos in the reduced Chialvo model
Open Research DataThe following dataset is connected with a map-based neuron model introduced by D. Chialvo (Chaos, Solitons & Fractals, 5 (3-4) 1995). The reduced version of this model is a one dimensional discrete system which describes the evolution of the membrane voltage when the value of the second variable, the recovery variable, is fixed. We have recently...
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The effect of reduced pressure on carbon dioxide flow boiling heat transfer in minichannels
Publication. In the paper presented are the results of the study on the effect of reduced pressure on flow boiling heat transfer data in minichannels as well as conventional ones. That effect renders that most of heat transfer correlations fail to return appropriate results of predictions. Mostly they have been developed for the reduced pressures from the range 0.1-0.3. The special correction has been postulated to the in-house model of flow...
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Electronic structure and magnetism of samarium and neodymium adatoms on free-standing graphene
PublicationThe electronic structure of selected rare-earth atoms adsorbed on a free-standing graphene was investigated using methods beyond the conventional density functional theory (DFT+U, DFT +HIA, and DFT+ED). The influence of the electron correlations and the spin-orbit coupling on the magnetic properties has been examined. The DFT+U method predicts both atoms to carry local magnetic moments (spin and orbital) contrary to a nonmagnetic...
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SEM images of SFM, LSFM and SFMNb in as-prepared state and reduced
Open Research DataThis dataset contains SEM images taken for pristine strontium ferrite molybdate, as well as ones doped with lanthanum or niobium. Materials were characterized in powder, under high vacuum in secondary electron mode. The images are divided into folders for as-prepared samples and reduced (H2, 800 deg, 4 h) ones.
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Anisotropic mechanical behavior and auxeticity of penta-graphene: Molecular statics/molecular dynamics studies
PublicationWe investigate the mechanical properties of penta-graphene (PG), a recently proposed two-dimensional carbon allotrope using atomistic simulation techniques combined with the empirical description of interatomic interactions. We report on the dependence of its three in-plane mechanical moduli (i.e. Young's modulus, Poisson's ratio and shear modulus) on the deformation direction, strain and temperature. We show that PG displays a...
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Structure and thermoelectric properties of Te/Ag/Ge/Sb (TAGS) materials obtained by reduction of melted oxide substrates
PublicationThe Ge0.77Ag0.1Sb0.13Te1alloy was fabricated by a novel two step route. For that purpose firstly the oxide reagents were melted at high temperature and quenched into pellets. After that pellets were milled to the powder and then reduced in hydrogen at various temperatures and for various periods of time. Energy dispersive X-ray analysis indicated the possibility of successful fabrication of stoichiometric thermoelectric materials...
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Is reduced integration just a numerical trick
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Flow boiling of R1233zd(E) in a 3 mm vertical tube at moderate and high reduced pressures
PublicationThe results of flow boiling of R1233zd(E) in a 3 mm vertical stainless steel tube are presented at moderate and high saturation temperatures. Integral flow characteristics in the form of pressure drop and heat transfer coefficient are discussed for saturation temperatures ranging from 115 to 145 °C (corresponding reduced pressures from 0.2 to 0.7), mass velocity of 800 kg/m2s and heat flux of 20 kW/m2. All of the obtained heat...
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The SEM images of LSCNT reduced at 900 degrees C under H2
Open Research DataThe dataset includes SEM image of La0.27Sr0.54Ce0.09Ni0.1Ti0.9O3-s sintered at 1200oC under air atmosphere for 12 h and reduced at 900oC under H2 for 10 h. Samples were produced using aqueous soft chemistry methods (Pechini).