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Wyniki wyszukiwania dla: HIGH-IMPEDANCE SPECTROSCOPY
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Nonlinear Impedance as Possible Result of Ion-Polaron Interaction in Cu2O-Al2O3-SiO2 Glass
PublikacjaNonlinear a.c. impedance measurements were performed in Cu2O-Al2O3-SiO2 glass in wide frequency range. The obtained results shows that a large nonlinearity in the impedance signal is observed at moderate electric fields of an order 1V/mm. The contents of the third harmonics reaches about 10% and strongly depends on temperature and frequency. The investigated glass exhibits mixed electronic-ionic conductivity. Electronic conduction...
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INFLUENCE OF BISMUTH CONTENT ON COMPLEX IMMITTANCE CHARACTERISTICS OF PRESSURELESS SINTERED BiNbO4 CERAMICS
PublikacjaGoal of the present research was to study immittance properties of BiNbO4 ceramics fabricated by the solid state reaction route followed by pressureless sintering. Four sets of samples were examined, namely the one fabricated from the stoichiometric mixture of oxides, viz. Bi2O3 and Nb2O5 as well as the ones with an excess of 3%, 5% and 10% by mole of Bi2O3. The immittance properties were studied by impedance spectroscopy. Measurements...
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Application of different modes of nanoscale impedance microscopy in materials research
PublikacjaIn recent years, there is noticeable interest in application of various types of scanning probe microscopy in material science research. One of them is contact atomic force microscopy combined with local impedance measurements, known as nanoscale impedance microscopy. Literature references present its application in investigations of new materials, microelectronics diagnostics, or research of protective coatings performance. In...
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The Impact of Crushed Rock Spoil on Pitting Corrosion of Selected Stainless Steel
PublikacjaThe paper presents the results of the pitting resistance investigations of selected stainless steels in the chloride environment and the simultaneous impact of erosive factors using the cyclic polarization technique. Additionally, using electrochemical techniques, ie: electrochemical impedance spectroscopy (EIS) and measurement of corrosion potential, the behavior of the passive layer of selected stainless steels in the environment...
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Application of multisine nanoscale impedance microscopy to heterogeneous alloy surface investigations
PublikacjaIn the recent years atomic force microscopy is recognized as valuable tool for investigation of surficial features of construction materials. It concerns, among other things, studies of changes caused by such phenomena as galvanic corrosion, passivation associated with the growth of oxide layers, or sensitization of austenitic steels with the formation of carbide phases. In addition, atomic forcemicroscopy allows easy coupling...
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A telemedical and an outpatient thoracic impedance measurements - a validation algorithm of the electrodes placement
PublikacjaThis paper presents the algorithm for validation of electrodes locations for the thoracic impedance measurements. In particular the presented algorithm was designed to perform the telemetric sleep apnea monitoring. One of the problems, during the clinical tests of a developed device, was to preserve the repeatability of measurements. It strongly depended on the appropriate electrodes placement on the examined person’s thorax. It...
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Galvanostatic impedance measurements for the efficient adsorption isotherm construction in corrosion inhibitor studies
PublikacjaWe present an approach towards an accurate and time-efficient adsorption isotherm determination to evaluate the corrosion inhibitor interaction in electrolytic environments. The approach is based on dynamic impedance spectroscopy measurements in galvanostatic mode (g-DEIS). The studied corrosion inhibitor is continuously injected between the secondary cell and the corrosion cell. The efficiency corresponding to instantaneous inhibitor...
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Implementation and Validation of Multisinusoidal, Fast Impedance Measurements in Atomic Force Microscope Contact Mode.
PublikacjaThis study presents a novel approach to impedance measurements. The methodology discussed is limited to contact in the sample-probe system under ambient conditions without the presence of electrolyte. Comparison with results of direct and alternating current measurements for well-defined metallic surfaces are made. In spite of idealization related to the type of contact examined, the proposed technique provides an improvement of...
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Design and Optimization of a Compact Super-Wideband MIMO Antenna with High Isolation and Gain for 5G Applications
PublikacjaThis paper presents a super-wideband multiple-input multiple-output (SWB MIMO) antenna with low profile, low mutual coupling, high gain and compact size for microwave and millimeter wave (mm-wave) fifth-generation (5G) applications. A single antenna is a simple elliptical-square shape with a small physical size of 20 × 20 × 0.787 mm3. The combination of both square and elliptical shapes results in an exceptionally broad impedance...
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Performance of zinc-rich coatings evaluated using AFM-based electrical properties imaging
PublikacjaThe paper presents the results of investigation of polyvinyl zinc-rich coating exposed to 97% relativehumidity atmosphere for 40 days. Condition of the coating and evolution of its protective properties weredetermined with the novel AFM-based approach capable of providing surface profiles, local dc currentmaps as well as local impedance spectra. The proposed technique allowed insight into the local changesof coating topography...
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Influence of electropolymerization conditions on the morphological and electrical properties of PEDOT film
PublikacjaIn this work the effects of electropolymerization conditions on the morphological properties and conductivity of poly(3,4-ethylenedioxythiophene) (PEDOT) film have been studied. PEDOT films were electrochemically synthesized in a one step process from acetonitrile solution containing 3,4-ethylenedioxythiophene (EDOT) and lithium perchlorate. Based on atomic force microscopy, scanning electron microscopy, cyclic voltammetry and...
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Evaluation of applicability of classic methods of a fault loop impedance measurement to circuits with residual current devices
PublikacjaMeasurement of fault loop impedance in low voltage grids and systems is in most cases performed to verify the effectiveness of protection against electric shock by automatic disconnection of supply. For the sake of measurement accuracy, it is advisable to perform it using large current. Unfortunately, in circuits with residual current devices which are very widely used nowadays, a large measurement current may trigger those devices...
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EM-Driven Multi-Objective Design of Impedance Transformers By Pareto Ranking Bisection Algorithm
PublikacjaIn the paper, the problem of fast multi-objective optimization of compact impedance matching transformers is addressed by utilizing a novel Pareto ranking bisection algorithm. It approximates the Pareto front by dividing line segments connecting the designs found in the previous iterations, and refining the obtained candidate solutions by means of poll-type search involving Pareto ranking. The final Pareto set is obtained using...
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Properties of Composite Oxide Layers on The Ti13Nb13Zr Alloy
PublikacjaThe development of composite oxide layers on the Ti13Nb13Zr alloy, their structure and properties have been demonstrated. Two subsequent methods were applied to prepare the composite layers. During the first stage gas oxidation produced a solid oxide layer, and subsequently oxide nanotubes were produced by using an electrochemical method. Scanning electron microscopy (SEM), chemical analysis, energy dispersive X-ray spectroscopy...
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Impedance monitoring of corrosion degradation of plasma electrolytic oxidation coatings (PEO) on magnesium alloy
PublikacjaImpedance technique based on continuous multisinusoidal current perturbation was used to explain degradation process of plasma electrolytic oxidation coatings (PEO) on magnesium alloy. An obtained impedance spectrum was fitted by electrical equivalent circuit to describe properties of conversion layer on magnesium alloy. Additionally, galvanostatic mode maintained during experiment, with DC current equal to zero, allowed to achieve...
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On deterministic procedures for low-cost multi-objective design optimization of miniaturized impedance matching transformers
PublikacjaPurpose This paper aims to investigate deterministic strategies for low-cost multi-objective design optimization of compact microwave structures, specifically, impedance matching transformers. The considered methods involve surrogate modeling techniques and variable-fidelity electromagnetic (EM) simulations. In contrary to majority of conventional approaches, they do not rely on population-based metaheuristics, which permit lowering...
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Assessment of protective properties of rubber lining in absorbers of flue gas desulphurization systems.
PublikacjaResults of research on degradation of rubber lining which is the main protection of absorbers in flue gas desulphurization (FGD) systems were presented. The power plant where the system operated is lignite-fired. Owing to measurements using electrochemical impedance spectroscopy and gravimetric determination of water content in the lining, the areas of the system which are most exposed to degradation were shown. The results obtained...
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Effects of V2O5 Additive on Structure and Dielectric Properties of BiNbO4 Ceramics
PublikacjaGoal of the present research was to investigate the influence of V2O5 additive on the structure and dielectric properties of BiNbO4 ceramics. To fabricate BiNbO4 ceramics with V2O5 added the solid state reaction route and pressureless sintering was utilized. Thus obtained ceramics was characterized in terms of its microstructure (SEM), chemical composition (EDS), phase composition and crystalline structure (X-ray phase and structural...
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Applicability of an effective conductivity approach in modeling thoracic impedance changes
PublikacjaThis paper describes numerical simulations of the influence of conductivity changes inside a volume conductor on impedance changes measured on its surface. A simple model based on the finite element method has been developed to estimate an applicability of the effective conductivity theory in human chest modeling. The model consisted of a cylinder with two concentric spheres inside. Simulations were performed for two cases: first...
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Multi-objective design of miniaturized impedance transformers by domain segmentation
PublikacjaFast multi-objective design optimization of compact microstrip impedance transformers is discussed. Our approach exploits approximation models constructed using sampled coarse- mesh EM simulation data in a partitioned design space and response correction techniques for design refinement. Demonstra
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A bisection‐based heuristic for rapid EM‐driven multiobjective design of compact impedance transformers
PublikacjaDesign of microwave structures is a multiobjective task where several conflicting requirements have to be considered at the same time. For contemporary circuits characterized by complex geometries, multiobjective optimization cannot be performed using standard population‐based algorithms due to high cost of electromagnetic (EM) evaluations. In this work, we propose a deterministic approach for fast EM‐driven multiobjective design...
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Insightful Analysis of Phenomena Arising at the Metal|Polymer Interphase of Au-Ti Based Non-Enzymatic Glucose Sensitive Electrodes Covered by Nafion
PublikacjaThis paper focuses on the examination of glucose oxidation processes at an electrode material composed of gold nanoparticles embedded in a titanium template. Three dierent conditions were investigated: the chloride content in the electrolyte, its ionic conductivity and the presence of a Nafion coating. The impact of the provided environment on the oxidation reaction was evaluated by cyclic voltammetry (CV) and electrochemical impedance...
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Exploring Mechanism of Corrosion Inhibition of WE43 and AZ31 Alloys by Aqueous Molybdate in Hank’s Solution by Multisine Impedimetric Monitoring
PublikacjaThe concept of utilizing multisine dynamic electrochemical impedance spectroscopy to monitor effectiveness of a model molybdate inhibitor for AZ31 and WE43 Mg alloys is proposed. The corrosion kinetics and instantaneous values of inhibition efficiency (IE) of molybdate at concentrations up to 150 mM were examined. The inhibitor provides inhibition in Hank’s solution at concentrations starting from ca. 25 mM, with the IE of about...
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A high-gain gap waveguide-based 16 × 16 slot antenna array with low sidelobe level for mmwave applications
PublikacjaThis study presents the design of a high-gain 16 × 16-slot antenna array with a low sidelobe level (SLL) using a tapered ridge gap waveguide feeding network for Ka-band applications. The proposed antenna element includes four cavity-backed slot antennas. A tapered feeding network is designed and utilized for unequal feeding of the radiating elements. Ridge gap waveguide technology is used to reduce the feeding network loss and...
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The contactless method of chip-to-chip high-speed data transmission monitoring
PublikacjaThis paper presents a technique of decoupling differential signals transmitted in a pair of microstrip lines on a printed circuit board (PCB), using dedicated coupler for high speed data transmission monitoring in chip-to-chip interconnections. The coupler used for signal probing is overlayed on the pair of microstrip lines under test, and provides a signal to the next blocks of the measurement system without disturbing transmission...
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Enhanced photocatalytic activity of accordion-like layered Ti3C2 (MXene) coupled with Fe-modified decahedral anatase particles exposing {1 0 1} and {0 0 1} facets
PublikacjaNew composites consisting of decahedral anatase particles exposing {001} and {101} facets coupled with accordion-like layered Ti3C2 with boosted photocatalytic activity towards phenol and carbamazepine degradation were investigated. The photocatalysts were characterized with X-ray diffraction (XRD), diffuse reflectance spectroscopy (DR/UV–Vis), Brunauer-Emmett-Teller (BET) specific surface area, Raman spectroscopy, scanning electron...
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Structural and electrical properties of titanium-doped yttrium niobate
PublikacjaIn this work, the influence of the substitution of niobium by titanium in Y3Nb1-xTixO7-δ on the structural and electrical properties is reported. Several experimental techniques, i.e. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS) and Electrochemical Impedance Spectroscopy (EIS), were applied to investigate the system Y3Nb1-xTixO7-δ. Titanium in Y3Nb1-xTixO7-δ is an acceptor-type...
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Hydrothermal Cobalt Doping of Titanium Dioxide Nanotubes towards Photoanode Activity Enhancement
PublikacjaDoping and modification of TiO2 nanotubes were carried out using the hydrothermal method. The introduction of small amounts of cobalt (0.1 at %) into the structure of anatase caused an increase in the absorption of light in the visible spectrum, changes in the position of the flat band potential, a decrease in the threshold potential of water oxidation in the dark, and a significant increase in the anode photocurrent. The material...
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Conductivity and viscosity changes of imidazolium ionic liquids induced by H2O and CO2
PublikacjaSeveral solutions of ionic liquids based on 1-ethyl-3-methylimidazolium cation saturated and unsaturated with carbon dioxide were prepared and characterized by electrochemical impedance spectroscopy. The in fluence of ILs saturation on its electrical conductivity was determined. Additionally, the in fluence of the water presence and variations of temperature on electrical properties of ionic liquids were investigated. Changes of...
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Phase Separation and Electrical Properties of Manganese Borosilicate Glasses
PublikacjaThe structure and electrical properties of manganese borosilicate glasses of a composition of xMnO-(0.8-x)SiO2-(0.2)B2O3 (x=0.4, 0.5 and 0.6 in mol) were investigated by impedance spectroscopy, SEM, XRD and confocal microscopy methods. The influence of composition on the glass structure and electrical properties was discussed. A separation of two amorphous phases was observed and it was concluded that one phase is SiO2-rich and...
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Tailoring the electrochemical degradation of iron protected with polypyrrole films for biodegradable cardiovascular stents
PublikacjaThe degradation of polypyrrole (PPy) coated iron is studied in phosphate buffer saline solution at 37 °C by odd random phase multisine electrochemical impedance spectroscopy (ORP-EIS). PPy is electropolymerized with anti-inflammatory salicylates incorporated in the film, as a drug release system. The modelling of EIS over time provides the quantitative description of the corrosion behaviour of the material. Thus, the reliable...
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Reliable data-driven modeling of high-frequency structures by means of nested kriging with enhanced design of experiments
PublikacjaData-driven (or approximation) surrogate models have been gaining popularity in many areas of engineering and science, including high-frequency electronics. They are attractive as a way of alleviating the difficulties pertinent to high computational cost of evaluating full-wave electromagnetic (EM) simulation models of microwave, antenna, and integrated photonic components and devices. Carrying out design tasks that involve massive...
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Instantaneous impedance monitoring of synergistic effect between cavitation erosion and corrosion processes
PublikacjaThe most common method of determination of cavitation erosion resistance as well as the magnitude of erosion-corrosion synergistic interaction is based on the weight loss measurements. Nondestructive characterization of installations elements is in most cases impossible to perform. Also, such a measurement does not include local types of failure or alteration of operating conditions. There is an urge to elaborate a method for monitoring...
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Surrogate modeling of impedance matching transformers by means of variable‐fidelity electromagnetic simulations and nested cokriging
PublikacjaAccurate performance evaluation of microwave components can be carried out using full‐wave electromagnetic (EM) simulation tools, routinely employed for circuit verification but also in the design process itself. Unfortunately, the computational cost of EM‐driven design may be high. This is especially pertinent to tasks entailing considerable number of simulations (eg, parametric optimization, statistical analysis). A possible...
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Vitamin B9 as a new eco-friendly corrosion inhibitor for copper in 3.5% NaCl solution
PublikacjaFolic acid salt (sodium folate) was studied as an eco-friendly and non-toxic copper corrosion inhibitor in 3.5% NaCl solution. Electrochemical impedance spectroscopy, polarization resistance and weight-loss measurements show that the inhibitor efficiency increases with concentration (the highest value- approx. 96% was reported for the solution containing 16 mM sodium folate after 24 h). EIS data and Tafel plots indicate that sodium...
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Microstructure and Dielectric Properties of Barium-vanadate Glasses
PublikacjaThe ac and dc conductivity in barium-vanadate glasses was investigated as a function of temperature and frequency with the use of impedance spectroscopy. The topography and microstructure of glasses were investigated by the means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The XRD results show that all samples are amorphous but microscopy investigation reveals that glasses with greater amount of V2O5...
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Improved performance of LaNi0.6Fe0.4O3 solid oxide fuel cell cathode by application of a thin interface cathode functional layer
PublikacjaIn this work, novel functional layers were prepared by a low temperature spray pyrolysis method on the oxygen side of the solid oxide cells. Thin layers of Ce0.8Gd0.2O2 and LaNi0.6Fe0.4O3 are prepared between the electrolyte and the porous oxygen electrode. Additionally the influence of the sprayed ceria barrier layer on the zirconia based electrolyte with the new layers is evaluated. Impedance spectroscopy results show improvement...
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A family of new generation miniaturized impedance analyzers for technical object diagnostics
PublikacjaThe paper presents the family of three analyzers allowing to measure impedance in range of 10 ohm<|Zx|<10 Gohm in a wide frequency range from 10 mHz up to 100 kHz. The most important features of the analyzers family are: miniaturization, low power consumption, low production cost, telemetric controlling and the use of impedance measurement method based on digital signal processing DSP. The miniaturization and other above mentioned...
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Locust bean gum as green and water-soluble binder for LiFePO4 and Li4Ti5O12 electrodes
PublikacjaLocust Bean Gum (LBG, carob bean gum) was investigated as an environmentally friendly, natural, and water-soluble binder for cathode (LFP) and anode (LTO) in lithium-ion batteries (Li-ion). For the frst time, we show LBG as an electrode binder and compare to those of the most popular aqueous (CMC) and conventional (PVDF) binders. The electrodes were characterized using TGA/DSC, the galvanostatic charge–discharge cycle test, cyclic...
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Corrosion Resistance and Surface Bioactivity of Ti6Al4V Alloy after Finish Turning under Ecological Cutting Conditions
PublikacjaThe influence of cooling conditions and surface topography after finish turning of Ti6Al4V titanium alloy on corrosion resistance and surface bioactivity was analyzed. The samples were machined under dry and minimum quantity lubrication (MQL) conditions to obtain different surface roughness. The surface topographies of the processed samples were assessed and measured using an optical profilometer. The produced samples were subjected...
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Phospholipid-functionalized gold electrode for cellular membrane interface studies - interactions between DMPC bilayer and human cystatin C
PublikacjaThis work describes the electrochemical studies on the interactions between V57G mutant of human cystatin C (hCC V57G) and membrane bilayer immobilized on the surface of a gold electrode. The electrode was modified with 6-mercaptohexan-1-ol (MCH) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). DMPC was used as a membrane mimetic for monitoring electrochemical changes resulting from the interactions between the functionalized...
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Heterogeneous oxidation of highly boron-doped diamond electrodes and its influence on the surface distribution of electrochemical activity
PublikacjaThe electrochemical active surface area (EASA) of polycrystalline boron-doped diamond (BDD) electrodes is heterogeneous and can be affected by numerous factors. There is a strong need for proper consideration of BDD heterogeneity in order to improve this material's range of application in electrochemistry. Localized changes in surface termination due to the influence of oxidation agent result in increased surface resistance. The...
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Rapid multi-objective design optimization of miniaturized impedance transformer by Pareto front exploration
PublikacjaFast multi-objective optimization of compact impedance transformer is discussed. A set of alternative designs representing possible trade-offs between conflicting design criteria, i.e., electrical performance (here, wideband matching) and the structure size, is obtained through Pareto front exploration by means of surrogate-assisted methods.
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Ellipse-fitting algorithm implementation in the impedance measurement system based on DAQ card with FPGA
PublikacjaThe paper presents an implementation of the ellipse-fitting algorithm in the impedance measurement system based on DAQ card equipped with FPGA chip. The method implementation was tested by simulation means as well as experimentally in the designed and presented measurement system. Finally, the limit values of sampling parameters which assures satisfying accuracy were given.
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Visible light activity of pulsed layer deposited BiVO4/MnO2 films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation
PublikacjaThin films containing BiVO4 and MnO2 deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27–115 nm) were...
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Optimization of boron-doping process of titania nanotubes via electrochemical method toward enhanced photoactivity
PublikacjaIn this work, we were focused on the development of the electrochemical approach resulting in a stable boron doping of titania nanotubes. The doping procedure concerns anodic polarization of as-anodized titania in a H3BO3 solution acting as n boron precursor. The series of attempts were taken in order to elaborate the most beneficial doping conditions. The parameters of electrochemical doping allowing to obtain boron-doped titania...
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Stratification of nano-pigments in anti-corrosive coatings by means of magnetic field
PublikacjaThe concept of self-stratification of coatings, although attractive, causes difficulties in its practical use, especially when pigments are added to the resins. An alternative way of obtaining a multilayer structure in a single step was presented. Using the inhomogeneous magnetic field and magnetically active components of the coating, the possibility of vertically graded differentiation of the one layer properties has been verified....
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Synthesis, thermal, structural and electrical properties of vanadium-doped lithium-manganese-borate glass and nanocomposites
PublikacjaA glassy sample with a nominal formula LiMn1−3x/2VxBO3 (where x = 0.05) was synthesised using the melt-quenching method. Material was characterised by differential thermal analysis (DTA), X-ray diffactometry (XRD) at room temperature and as a function of temperature (HT-XRD), X-ray photoelectron spectroscopy (XPS), impedance spectroscopy (IS) and scanning electron microscopy (SEM). Dependences of glass transition and crystallisation...
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ZnO-decorated green-synthesized multi-doped carbon dots from Chlorella pyrenoidosa for sustainable photocatalytic carbamazepine degradation
PublikacjaThe promising green synthesis of carbon dots (CDs) from microalga Chlorella pyrenoidosa was achieved using simple hydrothermal and microwave-assisted methods. Doping of nanomaterials by nonmetals (N, S, and P) was confirmed by X-ray photoelectron spectroscopy (XPS), while the existence of metals in the CDs was confirmed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and transmission electron microscopy (TEM),...
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Electrochemical investigations on the corrosion behaviour of reinforcing steel in diatomite- and zeolite-containing concrete exposed to sulphuric acid
PublikacjaCorrosion is a major concern for most structural applications. Its detrimental effect significantly reduces the life of metallic components. This paper presents the results of an experimental investigation of corrosion in the steel reinforcement of concrete samples having three different substituents: 20% diatomite, 20% zeolite, and a reference without zeolite or diatomite. All concrete specimens were subjected to a solution of...