Electric Layer Research Articles

Residual Image Reduction Using Electric Field Shield Metal in Plastic Organic Light-Emitting Diode Display.

A plastic organic light-emitting diode display is a device that emits light in an organic layer in proportion to the amount of current applied from a thin film transistor, which constitutes a pixel. However, it was confirmed that the residual image was shown by the operation of the thin film transistor. To suppress residual image, the effect of electric field was studied in operation of a-IGZO thin film transistor. The a-IGZO thin film transistor, in which a polyimide film was used as a substrate, was applied as a driving thin film transistor for pixel circuits in a plastic organic light-emitting diode display, and the effect of the electric field behavior inside the film on residual images was studied. Residual images were strongly connection with the electric field distribution characteristics inside the polyimide substrate, and they were reduced by introducing an electric field shield metal layer in the a-IGZO thin film transistor. The correlation between residual image generation and the operation of the a-IGZO thin film transistor was further explained through technology computer-aided design simulation (Silvaco Group Inc.).

A review of installation effects of ultra-high bypass ratio engines

The adoption of ultra-high bypass ratio (UHBPR) engines has been long recognised to bring about reduction of specific fuel consumption and noise emission. In the need to fulfil ambitious environmental targets and mitigate the aviation sector impact, they represent a smoother technology change, compared to futuristic aircraft designs featuring electric, distributed and boundary layer ingesting propulsion. However, the challenges related to UHBPR adoption can prevent a real system performance improvement, due to interdependent counteracting factors and enhanced interference between engine and airframe. This paper reviews the installation effects on underwing-mounted UHBPR turbofan engines, first presenting the cycle design studies and how they are affected by considering integration. The advancements in nacelle components modelling and optimisation are then reviewed, where new numerical models, statistical methods and optimisation algorithms are employed to tackle the inherently multi-objective problems. The computational estimation of installation effects and the studies on optimal engine position are also presented, highlighting the overall effect on the aerodynamic characteristics. Finally, the wind tunnel tests using powered engine simulators are discussed. The tools developed to quantify the thrust and drag figures of installed propulsors and obtain indications on their best underwing location now allow quite accurate estimations, both in numerical and experimental simulations. The higher level of interaction and the increased mutual sensitivity of engine operation and wing flow field, however, suggest the need to elaborate closely coupled methods to correctly replicate these effects and an assessment of current wind tunnel practices for the design and operation of powered engine simulators.

Theoretical Evaluation for the Function of Economical and Green Conducting Composite Material-based Chip for Jamaican Vomiting Sickness Diagnostics

A possibility of an economical and green conducting-polymer composite base chip for Jamaican vomiting sickness diagnostics by hypoglycin electrochemical determination has been evaluated. The correspondent mathematical model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It has been detected that the chip is efficient for either reduced or semi-oxidized form determination in an efficient manner, so it may serve as a rapid hypoglycin intoxication diagnostics tool. On the other hand, as all of the correspondent components possess amino acid moieties, influencing the double electric layer ionic forces.

Theoretical Description for Copper (II) Electrochemical Determination and Retention on a 1(2-pyridilazo)-2-naphthole-Modified Anode

A modern and flexible spectrophotometric method for copper determination in food has been proposed to be posted on the electrochemical tracks. The theoretical analysis of the correspondent model confirms the efficiency of the electrochemical reaction for either electroanalytical or electro-synthetical or eliminative processes for copper. As for the oscillatory instability, it will be caused by either chemical or electrochemical influences on the double electric layer.

The impedance of hydrogen oxidation reaction in a proton exchange membrane fuel cell in the presence of carbon monoxide in hydrogen stream

Evaluation of performance of a proton exchange membrane fuel cell, which isaffected by carbon monoxide that pollutes the hydrogen stream, was presented. This influence was studied for carbon monoxide concentration of 125–325 ppb, which are close to values specified in ISO 14687:2019 standard. Performed studies provided crucial information for further development of fuel cell as an energy source for automotive application. Impedance with the use of Dynamic Electrochemical Impedance Spectroscopy profile measurements were completed for chosen carbon monoxide concentration under a constant current load andanode impedance variations were determined as a function of the time exposed to carbon monoxide. A method to determine the impedance of hydrogen oxidation was proposed. It was determined how the carbon monoxide surface coverage of anodic catalyst varies as a function of time. The capacitance of the double electrical layer and the charge transfer resistance of anodic reaction are discussed to evaluate them with respect to exposure time and surface coverage. It has been shown that proposed methodology can be used as a universal tool for testing fuel cells for both research and industrial applications, with the overall aim of optimization, monitoring, and diagnostics of the fuel cell.

The Theoretical Description for the Electrochemical Determination of Anti-COVID-19 Drug Umifenovir, Assisted by a Poly(squaraine dye-co-naphthoquinones) Composite with CoO(OH), Paired with CoO2

For the first time, the system with anti-COVID19 drug umivenofir electrochemical determination, assisted by a Squaraine Dye – CoO(OH)/CoO2 composite, has been described theoretically. The mechanism contains hydrolysis, chemical, and electrochemical oxidation stages. The correspondent mathematical model has been developed and analyzed using linear stability theory and bifurcation analysis. Despite the branched character of the mechanism, the composite of Squaraine Dye with CoO(OH)/CoO2 may be an efficient electrode modifier for the umivenofir determination. However, the oscillatory behavior may be possible, but only because of double electric layer influences on the electrochemical stage.

Effect of quenching rate on crystalline and impedance properties of NiO nanoparticles

NiO nanopowder is produced through plasma-chemical synthesis in a low-pressure arc reactor in an atmosphere of 80% Ar + 20% O 2 at a pressure of 40 (sample 1) and 180 Pa (sample 2). The crystalline, morphological, and impedance properties are studied by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and impedance spectroscopy. It is shown that an increase in pressure leads to the synthesis of nanomaterials with fundamentally different crystalline and electrical properties. Sample 1 shows a non-stoichiometric composition (Ni 42 O 58 ), a face-centered cubic lattice, and a size of coherent scattering regions (CSR) of 16 nm. The impedance studies shows that the frequency dependences are well described by the Debye relaxation model, at low frequencies the real part of the dielectric constant is equal to 35, and thermal studies show a negative temperature coefficient of resistance (NTCR). Sample 2 has an amorphous structure, almost stoichiometric composition (Ni 48 O 52 ). At low frequencies, the real and imaginary parts of the dielectric constant reaches 105. The anomaly is explained by the formation of a double electric layer near the electrodes due to proton-ion conductivity.

Особенности электронно-оптических систем с плазменным эмиттером на основе стационарных двойных электрических слоев в плазме

The physical concept and the model of the construction of the plasma source of charged particles in crossed E × H fields are presented in which, due to the special configuration of the electrode structure, conditions are created for the formation of stationary double electric layers. It is shown that the formation of such layers promotes the growth of the source perveance and provides the possibility of simultaneous or alternating formation of flows of charged particles of different signs. The electrode structure and the main characteristics of the developed source are given, and the mechanism of its operation is proposed.

Laser speckle contrast imaging as a better tool to access the cutaneous microcirculation: Reproducibility and comparison to laser Doppler imaging in animal models

Current assessment of skin microcirculation function in animal models use laser Doppler flometry (LDF) or laser Doppler imaging (LDI). Both methods are limited by either low spatial resolution (LDF) or low temporal resolution (LDI). Laser speckle contrast imaging (LSCI) is a novel imaging technique of the cutaneous microcirculation with high spatial and temporal resolution. In this study, we report the use of LSCI in C57Bl/6 J mice in baseline flux, current induced vasodilation (CIV) and in wound healing monitoring (WHM) of excisionnal wound over 8 days. We describe the use of two high-resolution LSCI devices and compare them to LDI. To compare inter-day or/and inter-subject reproducibility of LSCI and LDI in CIV and WHM. Reproducibility will be expressed as coefficient of variation and intraclass coefficient correlation. Animal experiments were performed on 10-week-old C57Bl/6 J mice. CIV was produced by the administration of 100 μA of cathodal current over 4 min using a 1 cm 2 woven silver electrode with carboxymethylcellulose gel (Suprasorb G) as the electric diffusion layer. WHM was performed daily over 8 days after two 6 mm 2 wound were created on the back skin of the mice. Skin perfusion was assessed on the wound area and the periulcer skin. Both tested LSCI devices presented high resolution to 20 μm/pixel which allowed for the accurate mapping of the skin microcirculation in mice. Reproducibility data will be presented at the congress. LSCI is useful in assessing the cutaneous microcirculation compared to LDI. Additional testing is required such as skin microvascular reactivity to iontophoresis of acetylcholine and sodium nitroprusside and pressure ulcers for wound healing monitoring.

Synthesis of Refractory Metal Carbides on Carbon Fibers in Molten Salts and Their Electrochemical and Electrocatalytic Properties

Method of currentless transfer in molten salts was used for synthesis of tantalum and niobium carbides coatings and crystals of molybdenum carbide on carbon fibers. Temperature of process was varied from 800 up to 900 °C, and time of process from 0.5 up to 24 hours.Figure 1. Micrographs of carbon fiber with TaC and NbC coatings and Mo2C crystals (from left to right), obtained in molten salts melts by currentless transfer.The splicing of fibers with each other was not observed; coatings were uniform in a cross section as well as along the fiber. Thickness of TaC and NbC coatings on carbon fiber was 50 – 250 nm. Size of crystals of Mo2C was approximately several micrometers.Investigation of refractory metal (Ta, Nb, Mo) carbides on carbon fiber of the Carbopon-B-22 brand was carried out by impedance spectroscopy method. The values of the standard rate constants of charge transfer and capacities of the double electric layer were determined for synthesized materials in water solution with hydrogen peroxide.Coatings and crystals of refractory metal carbides on carbon fibers can be used as catalysts and electrocatalysts. The kinetics of the electrocatalytic decomposition of hydrogen peroxide on the surface of TaC/C, NbC/C and Mo2C/C composite materials was studied. This reaction was investigated on measuring the volume of released oxygen. The initial carbon fiber of the Carbopon-B-22 brand was used as the cathode. The composite materials made of carbon fiber coated with tantalum carbide TaC (NbC) or modified by molybdenum carbide Mo2C served as the anode. The reaction order was established, the rate constants and activation energies of the hydrogen peroxide decomposition were calculated. The composition with the highest electrocatalytic activity was determined. Figure 1

GIS bio-waste assessment and suitability analysis for biogas power plant: A case study of Anambra state of Nigeria

Environmental concerns have increased over environmental hazards associated with fossil energy source, transition to renewable energy sources have been emphasized, this however requires relevant data for informed decision making. Critical analytical methods in situating bioenergy plants for bioenergy production are advantageous from environmental, economic and sustainable perspectives. A study therefore was undertaken to provide relevant data on biogas renewable energy source using Anambra State of Nigeria as a case study. The study was carried out using the power of Geographical Information System (GIS) technology. Several GIS thematic layers were obtained considering important factors in bioenergy plant location analysis. GIS-based thematic maps used for the production of the suitability map include political boundary map layer, road network layer, Land Use and Land Cover (LULC) layer, Digital Elevation Map (DEM) layer, river layer, slope layer, electric transmission line network layer, biomass potential density layer etc. Considering the fact that bioenergy plant is dependent on heat energy source which is also abundant in the tropics, hill-shade layer was integrated into the GIS location suitability analysis. Various economic and socio-environmental factors were considered and utilized in the development of economic, land suitability and bio-resource spatial density maps. These thematic maps were overlaid to obtain the final suitability map index. The most suitable sites identified were located in Njikoka, Onitsha North and Dunukofia Local Government Areas (L.G.As) of the Study area. The annual cumulative bio-wastes generated from the three LGA are 9,133,220 kg, 3,992,735 kg, and 6,909,450 kg respectively. It is recommended that government and stake-holders should take this study as a veritable tool in green energy technology implementation plan.

Effect of the surface hydration of clay minerals on the adsorption of cesium and strontium from dilute solutions

The use of clay minerals for the decontamination of liquid radioactive waste generated during the work of nuclear energy enterprises remains currently relevant. The effect of the surface hydration of a montmorillonite nanocrystal on the adsorption of cesium and strontium ions from dilute solutions was studied. As opposed to the generally accepted mechanism of the adsorption of cesium and strontium ions on active sites of clay mineral crystals, we considered the adsorption of radiocesium and radiostrontium by montmorillonite taking into account its colloidal chemical properties. When montmorillonite nanocrystals interact with water, a double electric layer with a mobile diffuse ionic atmosphere forms on the surface of the solid phase. The adsorption of cesium and strontium ions from dilute aqueous solutions confines itself to ion-exchange reactions of cesium and strontium ions of a dispersion medium with exchange cations of the diffuse ionic atmosphere of montmorillonite. Enhanced adsorption of cesium ions compared with strontium ions was explained by low charge density on the outer shell of cesium ions and the ability of cesium ions to overcome the diffuse ionic atmosphere easily and to be fixed firmly on the outer surface of the montmorillonite nanocrystal.

Unusual Phenomenon of Forced Heat Exchange Taking Place during Quenching Silver Probe in Cold Electrolyte

It is shown in the paper that forced heat transfer exchange during quenching silver probes in cold electrolytes is explained by periodical replacement of short film boiling process by shock boiling. The frequency of such process is very high that increases cardinally heat transfer exchange. This phenomenon doesn’t fit contemporary theory concerning nucleate boiling processes and needs further careful investigations. The reason for existing periodical process is a double boundary electrical layer where are acting increased electrical forces during quenching in electrolytes. In contrast of quenching steel, silver generates higher heat flux density during quenching; however full film boiling cannot be developed due to presence of high electrical forces in a double electrical layer caused by increased electrical conductivity of silver. The discovered phenomenon can be used in the practice in the future after its careful investigation to force heat transfer exchange by external electrical forces to eliminate any film boiling process during batch quenching.

Improvement of stability of nano-SiO2/HPAM/SDS dispersion systems and its effect on oil displacement performances

The turbidity and Zeta potential experiments of nano-SiO2/HPAM/SDS dispersion systems at 60°C, 1.0×104 mg/L NaCl brine and simulated formation water were first investigated and the results indicated that Ca2+ and Mg2+ ions were responsible for the instability of dispersion system. Then, the methods of reducing pH value and adding chelating agents were used to improve the stability of nano-SiO2/HPAM/SDS dispersion system in simulated formation water, and the improvement effects and mechanisms were discussed based on sedimentation experiments and Zetasizer. The influences of these two methods on the oil displacement performances of dispersion system were analyzed by rheometer and interfacial tensiometer. The experimental results suggested that with the decrease of pH value, the stability of dispersion system was enhanced by the protection of H+ in the SiO2 double electric layer and the enhancement of hydration forces between particles although the absolute value of Zeta potential(|ζ|) of dispersion system decreased. All of the chelating agents including Na2EDTA, ATMP and Na4EDTA can improve the stability of dispersion system. Ca2+ and Mg2+ ions were complexed and pH value of dispersion system was decreased with the addition of Na2EDTA and ATMP, however, the decrease of pH value resulted in a sharp deterioration in the viscosity of dispersion systems. With the addition of Na4EDTA, the pH value of dispersion systems increased. The |ζ|, viscosity, storage modulus and loss modulus of dispersion systems all increased, which were benefited from the formation of stable complexes between Na4EDTA, and Ca2+ and Mg2+. Meanwhile, the ability of dispersion system to reduce oil and water interfacial tension was enhanced. Thus, after addition of Na4EDTA with mass ratio of 0.4% (optimal mass ratio) in dispersion system with nano-SiO2 mass ratio of 0.5%, the oil recovery was increased by 3.1%.

Achieved deep-dewatering of dredged sediments by Fe(II) activating persulfate pretreatment: Filtrating performance and mechanistic insights

The dredged sediments, being produced from sediment dredging process, would cause serious second environmental pollution without being disposed appropriately. Dewatering could effectively reduce the volume of dredged sediments before their disposal. Here, we for the first time achieved the deep-dewatering of dredged sediments with Fe(II)/Persulfate pretreatment and unraveled the involved mechanism. Fe(II)/Persulfate pretreatment was found to dramatically elevate the dewatering of dredged sediments, with water content of dredged sediments decreased from 84.8% ± 0.5% (the blank) to 39.5% ± 1.3% after pretreatment with 8 mg/g total suspended solids (TSS) Fe(II) and 20 mg/g TSS Persulfate. Mechanism investigation indicated that SO4−, OH, and Fe(III) were produced during Fe(II)/Persulfate process in the presence of H2O, while these species possibly resulted in the advanced dewaterability of dredged sediments. SO4− and OH broke extracellular polymeric substances (EPS) matrix and decomposed their main components in dredged sediments, which caused the disengagement of bound water in EPS, benefited to the reduction in hydrophilcity of sediments, and facilitated decrement of their viscidity. Furthermore, these radicals likely affected the proteic conformation in EPS and therefore stretched the proteic hydrophobic sites, which drove the increment in hydrophobicity of dredged sediments, availing to the escape of unbound water. Additionally, the electrostatic repulsions were reduced and the double electric layers round particles were compressed under the influence of Fe(III), which facilitated aggregating the dredged sediments particulates. Furthermore, the aggregated sediments particles were kept by Fe(III) combination with carboxyl and hydroxyl groups in sediments. After Fe(II)/Persulfate pretreatment of dredged sediments, their bound water content, surface area, electronegativity, and viscidity were alleviated while their flocculation, hydrophobicity, and water-draining structure were strengthened, which facilitated the deep-dewatering of dredged sediments.

Photovoltage from ferroelectric domain walls in BiFeO3

We calculate the component of the photovoltage in bismuth ferrite that is generated by ferroelectric domain walls, using first-principles methods, in order to compare its magnitude to the experimentally measured photovoltage. We find that excitons at the ferroelectric domain walls form an electric dipole layer resulting in a domain-wall driven photovoltage. This is of the same order of magnitude as the experimentally measured one, but only if the carrier lifetimes and diffusion lengths are larger than previously assumed.

Structure and electronic structure of van der Waals interfaces at a Au(1 1 1) surface covered with a well-ordered molecular layer of n-alkanes

The structure and electronic structure of a system comprising molecular layers of n-alkane adsorbed on Au(111) were investigated to understand the origin of the interfacial electric dipole layer. These alkane molecules are inert and thus van der Waals (vdW) interaction is the primary adsorptive force. Although these vdW interfaces are regarded as ideal physical adsorption systems unlikely to chemically interact with the metal surface, a large interfacial electric dipole layer over 1 eV is formed. It is important to elucidate the mechanism underlying the generation of such large dipole layers to understand the electrode interface in organic semiconductor devices. Thus, this paper elucidates the details of the vdW interface, in particular between tetratetracontane (TTC) and Au(111). First, the mechanism of growth of the TTC layer up to monolayer thickness was revealed using a low-energy electron-diffraction method. Second, the interface states were newly formed, as determined using angle-resolved photoelectron spectroscopy, X-ray photoemission spectroscopy, and near-edge absorption fine-structure spectroscopy. Our findings indicate, unexpectedly, that a relatively strong inter-orbital interaction governs this vdW interface, similar to a weak chemisorption system rather than a physisorption system.

Metal Foam Electrode as a Cathode for Copper Electrowinning

The geometry of porous materials is complex, and the determination of the true surface area is important because it affects current density, how certain reactions will progress, their rates, etc. In this work, we have investigated the dependence of the electrochemical deposition of copper coatings on the geometry of the copper substrate (flat plates or 3D foams). Chronoamperometric measurements show that copper deposition occurs 3 times faster on copper foams than on a flat electrode with the same geometric area in the same potential range, making metal foams great electrodes for electrowinning. Using electrochemical impedance spectroscopy (EIS), the mechanism of copper deposition was determined at various concentrations and potentials, and the capacities of the double electric layer (DL) for both types of electrodes were calculated. The DL capacity on the foam electrodes is up to 14 times higher than that on the plates. From EIS data, it was determined that the charge transfer resistance on the Cu foam electrode is 1.5–1.7 times lower than that on the Cu plate electrode. Therefore, metal foam electrodes are great candidates to be used for processes that are controlled by activation polarization or by the adsorption of intermediate compounds (heterogeneous catalysis) and processes occurring on the entire surface of the electrode.

Durable and Controllable Smart Windows Based on Thermochromic Hydrogels.

In recent years, the use of smart windows to adjust sunlight to achieve energy conversion has received increasing attention. In this paper, a novel smart window was easily prepared by using thermochromic hydrogels as an interlayer and indium tin oxide films as an electric heating layer. The shielding transmission rates of visible and near-infrared light reached 88.3 and 85.4% at the temperature of 25 °C, respectively. However, the transmittance at a light wavelength of 550 nm was greater than 70% after applying voltage. The smart windows with different components could possess thermochromic temperature ranging from 28 to 35 °C, which was suitable for daily life. The smart window could maintain a stable reversible thermochromic transition. Importantly, the time of light transition and the demand of energy efficiency could be adjusted by controlling the magnitude of the output voltage, which benefited the development of energy-efficient materials.

Piezoelectric Micromachined Ultrasonic Transducer With Superior Acoustic Outputs for Pulse-Echo Imaging Application

This article proposes a novel structured aluminum nitrate (AlN) thin film based piezoelectric micromachined ultrasonic transducer (PMUT) with superior ultrasonic performances that can directly be applied for pulse-echo imaging. The bottom electrode of the PMUT is thickened and serves both as the electrical layer and supporting layer. Large numbers of elements are parallelly connected to form square arrays. This method can not only improve the acoustic output but also reduce the total impedance. The ultrasonic transmitting, receiving behaviors of our developed 6.37 MHz (in air) PMUT array containing vibration elements of horizontal x vertical = 20 × 20 are investigated. It can generate superior acoustic output with a normalized value of 1.71 kPa·V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ·mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> at 3.6 mm away in deionized water media. Thanks to the lager acoustic output and reduced electrical impedance, ultrasonic pulse-echo imaging with our developed PMUT array is realized only with the assistance of a switch to separate the ultrasound transmission and reception process. We have mechanically scanned a mark in steel plate and generate a B-mode image with great accuracy using the recorded pulse-echo signals. These demonstrate the superior acoustic behavior of our developed PMUT array and open an avenue to the development of portable ultrasonic imaging devices.