Electric Layer Research Articles

Quantum model of the magnetic field of the Hot Expanding Earth

Principally new quantum model of the magnetic field of the Hot Earth [1] is proposed here. The model proceeds from the generation scheme of the Earth magnetic field (EMF) reported at the conference in 2019 [2], where crucial role of quantum entanglement (QE) of the inner G-core matter for EMF generation under the Hall effect was first evidenced. With regard to my impact into geodynamics of the Hot Earth [3] and quantum geophysics [4] the improved version of [2] is presented here. The justification for the model of EMF generation given in the encyclopedia of Geomagnetism [5] due to the daily rotation of the DEL (double electric layer), exciting a weak field and its amplification by the Hall current is first used here.

Quantitative analysis of micellar effect on the reaction rate of cationic triphenylmethine dyes with water according to Berezin’s model

Several approaches quantitatively describe the effect of surfactant micellar solution on the reaction rate. The most used among them are Piszkiewicz’s, Berezin’s, and Pseudophase Ion-Exchange (PIE) models. The last-named was developed by Bunton and Romsted. Piszkiewicz’s model is based on representations of the micellization according to the mass action law with the formation of a catalytic micelle, which consists of some surfactant molecules and a substrate. In our previously paper, this model was used to explain the kinetic micellar effect on the reaction of cationic triphenylmethine dyes with water once again showed the main disadvantages of this approach. Berezin’s model is based on another model of micelle formation viz. the pseudophase model, and the binding of reagents by micelles is considered as the distribution of a substance between two phases. In this work, we aim to consider the applicability of Berezin’s approach for the interaction of malachite green and brilliant green cations with water molecule as a nucleophile in aqueous systems of nonionic, anionic, cationic, and zwitterionic surfactants. On the whole, Berezin's model performed well when applied to the description of the micellar effect on the reaction of similar dye with the hydroxide ion. However, it was revealed that this model does not take into account the change in the local concentration of the HO– ions due to a compression of the double electric layer upon addition of reacting ions to the system, as well as the constant of association of the HO– ions with cationic head groups of surfactant. In this case, when water is used as a nucleophile, the question of the degree of nucleophile binding can be solved differently. The PIE model is also based on a pseudophase model of micellization, but a substrate binding by micelles is considered as an association in a stoichiometric ratio of 1:1, and a nucleophile concentration is expressed in a local concentration based on the neutralization degree of micelles. Given the latter, its approach cannot be applied to the kinetic micellar influence on the reaction of cationic triphenylmethine dyes with water.

Mechanism of thermally stimulated current occurrence in fine heterogeneous medium on the example of grain crops

The mechanism of thermally stimulated current occurrence in non-equilibrium heterogeneous fine-dispersed medium was analyzed on the example of mechanically activated barley. Presence of charged defects on ground grain crops surface causes formation of enveloping water films on their surface with ordered orientation of molecules and develops a double electric layer capable of accumulating electric current in the absence of external voltage. The area of double electric layer on the interfacial boundary of the grain medium under study with rigid fixation of molecules becomes a potential obstacle capable of increasing the substance electric strength. Occurrence of thermally stimulated electric current in the analyzed medium without external voltage results from the formation of potential difference of internal electric field, and is one of the reasons for grain mass burning. It is noted that disordering the structural properties of the ground grain has a serious effect on the temperature and humidity processes in the medium and the thermally stimulated current amount. The amount of electric current depends on the size of mechanically activated particles as well as temperature and humidity conditions.

Образование пузырька на гидрофобной поверхности

The paper investigates the formation of charged equilibrium nanobubble on smooth hydrophobic water - solid interface. Expressions are given for change the Gibbs energy of the system taking into account the capillary Kelvin formula, the electrostatic energy of the double electric layer at the bubble-water boundary and the surface energy. It is shown that the dependence of the Gibbs energy on the radius of nanobubble have a minimum, which indicates the possibility of spontaneous generation of these nanostructures. The dependence of Gibbs energy on the contact angle, as well as water salinity and surface tension coefficient of water is investigated. Calculated surface charge required for the stability of nanobubble.

Liquid-crystalline behavior and ferroelectric property of viologen-based ionic liquid crystals

Viologen-based ionic liquid crystals (VILCs) bearing viologen cations and various counter anions (Br−1, CsO−, PF6−1, CF3COO−, TsO−, and BF4−1) were prepared using cholesterol, bromobutanoyl chloride, bipyridine and different anionic salts. The chemical structures and the SmC⁎ phase were identified, and the effect of different anions on both liquid crystalline behavior and ferroelectric property was investigated. Melting temperatures of these VILCs with different anions were similar, but SmC*-isotropic phase transition temperatures were elevated in sequence of TsO−, CsO−, CF3COO−, PF6−, Br− and BF4−. They showed different polarization values changed from −9.1 to 9 nC/cm2 as the electric field changed from −10 V to 10 V. The ferroelectric parameters ±Ec, ±Pr, and ±Ps changed a little due to the different counter anions. The VILC with BF4− anion showed the optimal ferroelectric properties in these VILCs series. Unlike conventional ferroelectric liquid crystals, the VILCs displayed asymmetry in the hysteresis loops due to formation of double electrical layers in the ordered SmC⁎ phase.

Molecular modeling study concerning the self-assembly capacity of some photosensitive amphiphilic polysiloxanes

The understanding of self-assembly conditions has become the main purpose of experimental and theoretical research studies on micelles. Association of the micelles in clusters is a challenging topic, given the enhanced complexity of cluster systems. This work reports molecular dynamics studies on micellar structures of azo-polysiloxanes modified with quaternary ammonium groups like triethylammonium or dimethyldodecilammonium chloride. Previously, our experimental results have shown a very particular type of aggregation of long hydrocarbon chain amine-based micelles, which was not yet mentioned in the literature. If tertiary amines are low size, such as triethylammonium, the aggregation process of micelles in clusters is no longer present. Molecular dynamics simulations revealed the formation of an amphiphilic layer mainly composed of hydrocarbon chains of the ammonium groups, together with chlorobenzyl and azobenzene moieties. This ordering manner opposes to the idea of a continuous electrical layer of low molecular weight molecules on the surface of the micelle, or to those of a compositionally uniform coating formed by copolymers (diblock, triblock or graft). The herein paper also reports force field parameters, such as quantum mechanical derived atomic partial charges for the studied compounds, bringing improvements to the force fields developed so far.

Non-linear elasticity effects and stratification in brushes of branched polyelectrolytes.

Brushes formed by arm-tethered starlike polyelectrolytes may exhibit internal segregation into weakly and strongly extended populations (stratified two-layer structure) when strong ionic intermolecular repulsions induce stretching of the tethers up to the limit of their extensibility. We propose an approximate Poisson-Boltzmann theory for analysis of the structure of the stratified brush and compare it with results of numerical self-consistent field modeling. Both analytical and numerical models point to the formation of a narrow cloud of counterions (internal double electrical layer) localized inside a stratified brush at the boundary between the layers.

Analysis of Recovery Time of HTS Tapes With Electrical Insulation Layers for Superconducting Fault Current Limiters Under Load Conditions

The implementation of superconducting fault current limiters (SFCL) in the electrical power system requires the coordination of its parameters with the installed power system protection (PSP), in particular when using automatic reclosing (AR). The crucial parameter for AR is the recovery time of the SFCL, understood as the SFCL return time to the superconducting state after its operation. This time will depend mainly on the efficiency of the cooling system and the heat dissipation processes in the electrical insulation system. This article presents the results of experimental research on the return time to the superconducting state of superconducting tapes with layers of electrical insulation of various thicknesses. The tests were carried out in conditions in which the density of energy generated during the surge current flow correspond to the operating conditions of superconducting material in SFCL. Also, the transfer of this energy to liquid nitrogen corresponds to phenomena occurring in SFCL. The recovery time of several types of high temperature superconducting tapes in the zero current state and recovery under load were determined. The range of the load current at which it is possible return to the superconducting state was determined for tapes with and without electrical insulation. It has been shown that the analysis of these processes must take into account the strong dependence between the thermal energy transfer from the sample surface to liquid nitrogen and the type of nitrogen evaporation process on the surface of the sample. The presented research results are of particular importance for the functionality of SFCL and its cooperation with the PSP.

MODELLING NANO-TECHNOLOGICAL PROCESSES OF OIL EMULSIONS FORMATION AND DESTRUCTION

It is shown that oil preparation process is related to nanotechnologies, since they are carried out at the Nano-dimensional level consisting in the charge interaction of mono and polyvalent ions being present in interacting environments of oil and reservoir (intermediate) water. Taking into account specific features (Nano-phenomena) of oil emulsion formation and destruction, a mathematical model for thermochemical oil dehydration process is proposed. As it is known, the main processes of formation and destruction of AC at the interfacial section (oil-water) occur at the molecular level, and molecular-surface phenomena (Nano-phenomena) are dominant in the process of oil preparation. First of all, this is the charge interaction of nano-dimensional particles, manifested in the form of physicochemical adsorption of natural emulsifiers on the surface of EWD, wetting the armoring casings of the latter (with corresponding demulsifier interaction), ion-exchange formation of a double electric layer (DEL) on surfaces of EWD and mechanical impurities (solid particles of clay, quartz, limestone, dolomite, iron sulfide, etc.). Consequently, the modeling of these processes is an urgent task, and the article is dedicated to above-mentioned problem.

Simultaneous pressure and electro-osmosis driven flow in charged porous media: Pore-scale effects on mixing and dispersion

Electrokinetic effects in porous media play a key role in a number of natural and industrial processes. Applications such as enhanced oil recovery, soil remediation and even drug delivery are affected by the Coulombic forces created by the solid-fluid interfacial interactions. These electrokinetic effects promote the development of non-homogenous slipping flow over charged surfaces at the pore scale, which can have a significant impact in the hydrodynamics of tight porous materials. For transport of ionic solutions in such systems (e.g. transport of low salinity water in tight oil reservoirs), combined effect of hydrodynamic transport and electrokinetic transport would be expected. While transport in pressure-driven transport will be pronounced in high permeability flow pathways, transport due to electric fields (e.g. electro-osmosis) will be more pronounced in tight pores were electrical diffuse layer is not negligible. In this work, we explored the pore-scale hydrodynamic characteristics of charged porous media using computational fluid dynamics. Different flow driving mechanisms were studied, e.g. conventional pressure driven flow, pure electro-osmosis as well as their superposition under different amounts of charged material. We then analyzed the effect of these distinct flow regimes on the transport of a passive tracer, finding how different driving mechanism result in distinct dispersion and mixing characteristics.

A double four-point probe method for reliable measurement of energy conversion efficiency of thermoelectric materials

A thermoelectric material’s efficiency in converting heat to electricity is its most important factor for considering the material for practical applications. Therefore, accurately measuring the conversion efficiency of any thermoelectric material is essential. However, the electrical contact layers without resistance between a thermoelectric material and electrodes, which are very difficult if not impossible to make, are required to reliably demonstrate the actual conversion efficiency. Here we report a double four-point probe method that can reliably measure the conversion efficiency of any thermoelectric material without the need to make the contact layers. In this method, copper foils acting as electrodes are mechanically pressed on the ends of the thermoelectric leg to conduct the measurement. Conversion efficiency for Mg3Sb2-based thermoelectric materials was measured to be ∼12.4% at a temperature difference of ∼420 °C, consistent with the predicted value from COMSOL Multiphysics, a finite element-analysis tool that reliably predicts the measured efficiencies. This method can be applied to any thermoelectric material without undertaking the tedious contact-fabrication process, which is important for rapidly screening thermoelectric materials, although practical applications still require reliable contacts.

Negative Fermi-Level Pinning Effect of Metal/n-GaAs(001) Junction Induced by a Graphene Interlayer.

It is demonstrated that the electric dipole layer due to the overlapping of electron wave functions at the metal/graphene contact results in a negative Fermi-level pinning effect on the region of the GaAs surface with low interface-trap density in the metal/graphene/n-GaAs(001) junction. The graphene interlayer plays the role of a diffusion barrier, preventing the atomic intermixing at the interface and preserving the low interface-trap density region. The negative Fermi-level pinning effect is supported by the decrease of the Schottky barrier with the increase of the metal work function. Our work shows that the graphene interlayer can invert the effective work function of the metal between high and low, making it possible to form both Schottky and Ohmic-like contacts with identical (particularly high work function) metal electrodes on a semiconductor substrate possessing low surface-state density.

STUDY ON ELECTROKINETIC PARAMETERS OF COMPOSITE COAGULANTS-FLOCCULANTS

In this work the electrokinetic parameters of composite coagulants-flocculants based on combination of polyaluminum chloride (aluminum oxychloride) and organic polymers were studied systematically. The experimental results, obtained by the streaming current and electrophoresis methods, witness that the combination of polyaluminum chloride and cationic organic polymer can effectively enhance the charge neutrality capacity. The results obtained directly indicate that after the combination of polyaluminum chloride and cationic organic polymer, the positive charge of suspended particles obviously enhances, and the ability of double electrical layer on solid surface with negative charge improves. The most important factor is that the charge neutrality capacity of composite coagulant is stronger, thus, in comparison with polyaluminum chloride efficiency, the efficiency of composite reagent is higher. Moreover, due to the existence of long molecular chain, adding cationic organic polymer into polyaluminum chloride can enhance the bridging coagulation between its particulate matters. The experimental results indicate that if to combine polyaluminum chloride with natural cationic organic polymer - chitin and industrial cationic organic polymer product C109P, its electric charge can be largely enhanced This fact undoubtedly deserves attention when developing compositions of coagulants-flocculants to improve their ability to charge neutrality in the processes of coagulation and agglomeration of suspended particles. When executing experiment on the use of anionic organic polymers, the regulation of the coagulation-flocculation theory that the main function of an anionic organic polymer in a composite reagent is the function of a bridge between solid particles was taken as a basis. At the same time, an effective influence on this property of the system can hardly lead to a decrease in the ability to neutralize the charge of polyaluminium chloride. Experimental data relating to the study of the composition reagent containing polyaluminium chloride and industrial anionic organic polymer products AH200P and AN910SH, confirm the fact that this combination does not reduce the ability to neutralize the charge.

Synthesis of a novel dispersant with topological structure by using humic acid as raw material and its application in coal water slurry preparation

This work reports the synthesis and performance of a novel dispersant for coal water slurry (CWS). The dispersant is derived from humic acid (HA) and has a topological structure, named humic acid-graft-poly(sodium styrene sulfonate) (HA-g-PSSNa). A series of HA-g-PSSNa with simultaneous presence of hydrophobic humic acid skeleton and hydrophilic poly(sodium styrene sulfonate) side chains were synthesized via surface acylation reaction of HA and followed by atom transfer radical polymerization. The structure and chemical composition of HA-g-PSSNa were verified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy observation suggests that the incorporation of PSSNa segments onto HA skeleton remarkably affects its morphology. The performances of CWS prepared using HA-g-PSSNa, PSSNa, and naphthalene sulfonic formaldehyde condensate (NSF) as dispersants were studied and systematically compared using various technologies. The results show that the slurry-making performance of HA-g-PSSNa enhanced with the increase in the length of PSSNa side chains. In the case of HA-g-PSSNa with appropriate PSSNa chain length, the CWS prepared using HA-g-PSSNa as dispersant exhibits excellent apparent viscosity as well as static stability, even superior to those of PSSNa and NSF. The dispersing and stabilizing mechanism of HA-g-PSSNa is proposed as follows: When used as a dispersant for CWS, HA skeleton provides sufficient hydrophobic interaction to coal surface and drives the adsorption of HA-g-PSSNa molecules. Hydrophilic PSSNa side chains are oriented to water, thus forming a dense electrical layer and steric hindrance surrounding the coal particles. Accordingly, the aggregation of coal particles was suppressed.

Micro Alkaline Fuel Cell supported by MEMS-based Backbone

This work presents the application of nitride membranes produced with Si-MEMS-technology as a platform to build up new membrane-electrode assemblies (MEA) for alkaline fuel cells. Active alkaline fuel cell MEAs were combined by integrating hydroxide permeable electrolyte into micro-channels of 1 μm diameter in 5 to 10 μm thick MEMS-based membranes. A platinum catalyst was sprayed onto the surface and an electric conductive layer was applied on top. Taking advance of the small form factor these fuel cells can be applied in small devices with low energy demand.

Probabilistic reliability evaluation of distribution systems considering the spatial and temporal distribution of electric vehicles

Fast-growing electric vehicles load can impose various reliability concerns and peak demand increase in electric power systems, particularly distribution networks. From a power system point of view, electric vehicles can be considered as random moving loads. A new probabilistic approach is, therefore, proposed in this paper to evaluate the impact of electric vehicles on the reliability performance of power distribution systems. A two-layer stochastic electric vehicle charging demand estimation model is proposed. The model comprises of a traffic layer representing the spatial-temporal distributions of electric vehicles and an electrical network layer describing the electric vehicles charging demand. A Dynamic Hidden Markov Model is used to capture the electric vehicle movements in the traffic layer. Electric vehicle travel patterns and charging demand are simulated using a sequential Monte Carlo simulation approach considering the vehicle distance traveled, the type of charging location and the driver class. The proposed approach and the models are used to perform reliability studies on an example test system, and a series of analysis results are presented.

The electric properties of AOT reverse micelles by molecular dynamics simulations

Reverse micelles (RMs) are the main component of a reverse microemulsion. The ionic RMs of sodium and calcium bis(2-ethylhexyl)sulfosuccinate (AOTNa and AOT2Ca, respectively), and water clusters of different size in isooctane were simulated by the united-atom molecular dynamics method. The radial density profiles characterized the local structure. The local electric potential and the electric field were calculated to describe the electric layer (EL). The behavior of these functions differs principally from the related quantities in the classical electric double layer. The decrease in the size of RMs leads to a noticeable compression of the EL. The value of the local electric field near the surface of the RM increases significantly with the replacement of Na+ counterions by Ca2+. The mutual compensation of the contributions from water and ions calculated separately was revealed, which results in poor sensitivity of the electric properties of the RMs to salt addition. The mean-square dipole moment was calculated for all considered aggregates. It was shown that this quantity strongly depends on the aggregate size as could be expected due to its fluctuation nature. Comparison of the mean-square dipole moment value obtained by the atomistic simulation with the one obtained within the primitive model witnesses that the strong overestimation of the dielectric permittivity of confined water in the primitive model of the RM leads to a significant decrease in the value of the micellar mean-square dipole moment.

Triaxial Shear Test on Hydrochloric Acid-Contaminated Clay Treated by Lime, Crushed Concrete, and Super Absorbent Polymer

Acid pollution weakens the bearing capacity of subgrade, and discarded concrete occupies land. The mechanical properties of hydrochloric acid-contaminated clay were investigated by triaxial consolidation undrained tests. Also, the theory of diffusion double electric layer was employed to explain the change principle of cohesion and compression characteristics of hydrochloric acid-contaminated clay. In addtion, the curing effects of lime, crushed concrete, and SAP on the shear strength of hydrochloric acid-contaminated clay were compared. The triaxial test results show that cohesion decreased with the increase of hydrochloric acid concentration. The internal friction angle firstly increased and then decreased, and the change of internal friction angle was less affected by acid concentration. The curing effect of crushed concrete was similar to that of lime, which was better than lime. SAP could only improve the cohesion of the hydrochloric acid-contaminated clay; the internal friction angle decreased significantly; the three kinds of curing materials could significantly improve the cohesion of acid-contaminated clay to be higher than the natural clay, improving the shear strength to a certain extent. Additionally, the theory analysis illustrated that due to the change in the thickness of the diffusion layer between the clay particles, the van der Waals force between the particles changed, and the colloidal formation of the micelles led to changes in cohesion. The study can provide references to the treatment of contaminated soil in engineering practice.

Electrical insulation improvements of ceramic coating for high temperature sensors embedded on aeroengine turbine blade

Intelligent aeroengine requires high temperature sensors, especially MEMS thin film sensors directly fabricated on the surface of turbine blade. For this purpose, an electrical insulation layer is needed on blade substrate metals. However, the electrical insulation of ceramic materials will degrade at high temperatures, thereby affecting the characteristics of the sensor. In this paper, ceramic material of YSZ thermal barrier coating (TBC) formulation was modified by adding a certain amount of Al2O3 to improve its insulation at high temperatures. Micro processing was carried out on the surface of the TBC, including the fabrication of platinum-point thermocouples and thermal resistor on TBC surface, and high temperature electrical insulation properties of the modified TBC were studied. Results show that electrical insulation can be improved several orders of magnitude with adding Al2O3 which meets the requirement to build reliable thin film sensors on the top of TBC surface coated on turbine blade metals. Several verification experiments were carried out to ensure the working ability of TBC layer, including robustness test, thermal shock test and high temperature retention test.

Quantum Modeling of a Double Electrical Layer

The article studies the problems of calculating both stationary and dynamic diffuse double electric layers (DELs), taking the quantum factor into account. The self-consistent field of the quantum mechanical DEL is simulated based on the Schrodinger equation and its modification in the Madelung form. An approximate solution of the equations of quantum mechanics and the electric field is carried out by the finite difference method. An example of modeling a diffuse double electric layer for a gas plasma and a cryogenic solution of quantum particles is considered. The effects of the form factor of the initial plasma density distribution, temperature, microscopic friction forces, and parameters of the computational method are studied.