Action Of Electric Field Research Articles

Preparation, deposited behavior and hydrophobic property of modified graphene oxide reinforced Ni composite coatings by magnetic field assisted electro-brush plating

Graphene oxide (GO) as nano reinforcement has been extensively used to improve the overall performance of metal-based composite coatings. In this work, GO nanosheets with surface modification and magnetic field (MF) assisted electro-brush plating (EBP) technique were employed to construct Ni-based composite coatings with biomimetic structure to improve the corrosion resistance of coatings. The preparation, deposited behavior and some properties of coatings were investigated. The results showed that after surface modification, GO surface carried numerous Co7Fe3 magnetic nanoparticles with the size of 40–50 nm. During the MF assisted EBP process, the co-deposition of CoFe@GO magnetic powders with the reduced Ni atoms contributed to the formation of Ni-CoFe@GO composite coatings with stripe-like structure that resembled the surface morphology of conch. Besides, induced by the synergistic action of MF and electric field, most magnetic powders were distributed regularly in the stripe-like areas. After two weeks exposure to air, Ni-CoFe@GO composite coatings changed spontaneously from hydrophilic for fresh coatings to hydrophobic. This transformation was mainly attributed to the high surface roughness and the adsorption of a lot of hydrocarbons on the stripe-like surface. Moreover, air pockets that resulted from these hydrocarbons formed on the coating surface impeded the diffusion of corrosive media into coatings. Consequently, Ni-CoFe@GO composite coatings exhibited good corrosion resistance. Therefore, the preparation proposed in this work is desirable and has a prospect in further improving the corrosion resistance of GO reinforced Ni-based composite coatings.

A particle tracking velocimetry method to measure size and charge distributions in tribocharged powder particles

Simultaneous charge and size of tribocharged particles suspended in a gas stream are measured using image analysis. Under the action of a homogeneous electric field, drag, and electric forces are the main factors influencing particle trajectory, from which electric charge and polarity are derived. We could check that the system operates in a laminar gas regime inside the analysis cell since high flow turbulences would alter the particle “electrical” path, thus invalidating the measurement. Single component granular materials and binary mixtures are studied, all cases showing bipolar distributions and dependence on particle size. Mixture composition affects the overall charge polarity in the dispersed powder, and this effect can not solely be attributed to the weight proportion of the components. PTV is a powerful tool in techniques used for triboelectric dry separation of organic and inorganic products since their efficiency relies much on the charge to mass ratio.

Electricity Generation, Salt and Nitrogen Removal and Microbial Community in Aircathode Microbial Desalination Cell for Saline-Alkaline Soil-Washing Water Treatment

An aircathode microbial desalination cell (AMDC) was successfully started by inoculating anaerobic sludge into the anode of a microbial desalination cell and then used to study the effects of salinity on performance of AMDC and effect of treatment of coastal saline-alkaline soil-washing water. The results showed that the desalination cycle and rate gradually shorten, but salt removal gradually increased when the salinity was decreased, and the highest salt removal was 98.00 ± 0.12% at a salinity of 5 g/L. COD removal efficiency was increased with the extension of operation cycle and largest removal efficiency difference was not significant, but the average coulomb efficiency had significant differences under the condition of each salinity. This indicates that salinity conditions have significant influence on salt removal and coulomb efficiency under the combined action of osmotic pressure, electric field action, running time and microbial activity, etc. On the contrary, COD removal effect has no significant differences under the condition of inoculation of the same substrate in the anode chamber. The salt removal reached 99.13 ± 2.1% when the AMDC experiment ended under the condition of washing water of coastal saline-alkaline soil was inserted in the desalination chamber. Under the action of osmotic pressure, ion migration, nitrification and denitrification, NH4+-N and NO3−-N in the washing water of the desalination chamber were removed, and this indicates that the microbial desalination cell can be used to treatment the washing water of coastal saline-alkaline soil. The microbial community and function of the anode electrode biofilm and desalination chamber were analyzed through high-throughput sequencing, and the power generation characteristics, organics degradation and migration and transformation pathways of nitrogen of the aircathode microbial desalination cell were further explained.

External impacts on structure and relaxation properties of thermotropic liquid crystal copolyester

The methods of thermally stimulated depolarization (TSD) and X-ray diffraction analysis were used to study the impact of electric and temperature fields on the relaxation properties, structure, and molecular mobility of a liquid crystal (LC) copolymer based on polyethylene terephthalate (PET) and n-hydroxybenzoic acid (n – HBA). It was shown that polarization in the LC state besides the main relaxation transition leads to the formation of additional high-temperature maximum on current thermograms of thermally stimulated depolarization (TSD). The data of X-ray diffraction analysis indicate a change in the orientation of mesogenic units after polarization in an electric field. The results were explained by the combined action of electric and temperature fields on the conformational structure of the liquid crystal copolyester, namely, a change in the degree of crystallinity of the studied copolyester under the influence of external fields.

Experimental investigations on electrorheological properties of lubricating oils containing ionic liquid. Part 2. Testing in dielectric spectroscopy

The paper presents the results of investigations of two mixtures and their ingredients i.e. base insulating oils and ionic liquids as electrically active additives using, so called, dielectric spectroscopy. In part 1 of the study [1], the ER effect was found in both mixtures when they were subjected to an external constant electric field with the intensity of E ≤ 0.2 kV·mm–1. However, the electrorheological effect was short-lived and unique on the same liquid sample, which suggested significant changes in its internal structure. Using the HP 4192 A Hewlett Packard impedance analyzer, the variability of their dielectric constans (), as well as the resistance (R) and the conductivity (σ), as a function of the frequency (f) of the constant electric field BIAS-u (DC) was assessed for different values of the applied voltage (U). Repeated tests were also carried out on the same samples of mixtures to observe how the originally applied BIAS field affects the further behavior of the liquid in the electric field. Based on the results of the research, the basis for confirming the symptoms of changes in the internal structure of mixtures, resulting, from the action of an external electric field, leading to the disappearance of the ER effect was obtained. In order to recognize the mechanism of disappearance of the ER effect, in situ microscopic tests of the prepared mixtures, subjected to an external electric field, will be carried out. Keywords: electrorheological effect, lubricating oils, ionic liquids, dielectric spectroscopy

Ferroelectric-field accelerated charge transfer in 2D CuInP2S6 heterostructure for enhanced photocatalytic H2 evolution

Abstract The development of ferroelectric photocatalytic materials with polarization electric field is a key approach to realize the spatial separation and fast transfer of charge carriers in visible-light-driven H2 evolution. Generally, replacing traditional 3D perovskite-type ferroelectric materials with 2D ferroelectric materials is disregarded as candidates for photocatalysis. Herein a 2D CuInP2S6 (CIPS) with room-temperature ferroelectricity (a Curie Temperature of around 47 °C) is developed as a new photocatalyst, and 2D/2D heterojunction of CuInP2S6 nanosheet/g-C3N4 ultrathin flake (CIPS/CN) is constructed to further accelerate charge transfer. Benefitting from the synergetic action of the inner polarization electric field of CIPS and 2D/2D heterojunction, CIPS/CN displays a substantially accelerated charge transfer and significantly enhanced photocatalytic H2 evolution rate, which is up to 7.6 times by contrast with that of paraelectric-phase CIPS. This work would provide a new platform for the design of 2D ferroelectric photocatalytic system with highly-efficient charge transfer.

Review about PD and breakdown induced by conductive particles in an insulating liquid

In insulating liquid, a conductive particle becomes charged through the interaction with a conductor exposed to an applied field. Then, it migrates in the action of both electric field and fluid and causes the enhancement of local field when it is in proximity of the conductor with opposite polarity. The enhancement will lead to partial discharge (PD) and may even ignite full gap breakdown in special cases. This study reviews comprehensive researches relevant to these topics. In the first place, several theoretical methods about how to obtain the charges held by a conductive particle with known potential are introduced, so are experimental methods. Then, forces acting on the charged particle in liquid are classified, and its migration characteristics, as well as influential factors, are described. Subsequently, PD and breakdown mechanisms of liquid initiated by conductive particles are presented. The latter involves two cases: electric-field enhancement when the particle concentration is low and bridging phenomenon when it is high. At last, two important, but frequently ignored factors, i.e. dielectric barrier and oil flow, are highlighted, and the authors’ suggestions for future work are put forward.

Heavy Metals Nanofiltration Using Nanotube and Electric Field by Molecular Dynamics

Heavy metal contamination in the world is increasing the impact on the environment and human life. Currently, carbon nanotubes and boron are some possible ideals for the nanofiltration of heavy metals due to the property of ion selectivity, optimized by the applications of the surface and the application of an external electric field. In this work, molecular dynamic was used to transport water with heavy metals under the force exerted by the electric field action inside nanotubes. This external electric field generates a propelling electrical force to expel only water molecules and retain ions. These metal ions were retained to pass through only water molecules, under constant temperature and pressure, for a time of 100 ps under the action of electric fields with values from 10-8 to 10-1 au. Each of the metallic contaminants evaluated (Pb2+, Cd2+, Fe2+, Zn2+, Hg2+) was subjected to molecular test simulations in the water. It was found that the measurement of the intensity of the electric field increased or the percentage of filtered water reduced (in both nanotubes), in which the intramolecular and intermolecular forces intensified by the action of the electric field contribute to retain the heavy metal ions due to the evanescent effect. The best results for nanofiltration in carbon and boron nanotubes occur under the field 10-8 au. Since the filtration in the boron nitride nanotubes, a small difference in the percentage of filtered water for the boron nitride nanotube was the most effective (90 to 98%) in relation to the carbon nanotube (80 to 90%). The greater hydrophobicity and thermal stability of boron nanotubes are some of the factors that contributed to this result.

Investigation of discharge process for argon spark switch at atmospheric pressure

In this paper, a 2D fluid switch model for argon spark switch at atmospheric pressure was established and the detailed discharge process was numerically investigated. The distributions of physical quantities such as electric field strength, electron density, particle density, electron temperature and electron migration velocity at different time were obtained. It is shown that at the initial moment of the discharge process, the electrons move from the cathode to the anode under the action of the external electric field. As the electric field strength increases, the streamer is first formed at the anode and rapidly propagates to the cathode, which finally forms streamer breakdown. The electron temperature starts to rise slowly near the location of anode and cathode, then decreases near the anode and rapidly transfers to the cathode. In addition, the repeated pulse discharge experiment based on the gas switch model was preliminarily carried out. And the current waveform and amplitude obtained by numerical simulation are basically consistent with the experimental results. The results indicate that the present research might provide theoretical basis for the study on the discharge process of gas spark switch.

Formation of Silver-Containing Polymeric Nanocomposites by the Reduction of Ag+ Ions in Polyelectrolyte–Metal Complexes Under the Action of Electric Fields

By the methods of wide-angle X-ray diffraction and small-angle X-ray scattering, we study the specific features of the structural organization of pectin–Ag0–P4VP nanocomposites obtained under the action of constant electric fields. It is shown that, in the process of chemical reduction of Ag+ ions in polyelectrolyte–metal complexes, under the action of electric fields, we observe the formation of nanocomposites with higher contents of metallic silver than in the absence of the field. By the method of thermomechanical analysis, it is demonstrated that these materials have a much higher temperature of vitrification, a lower temperature of transition into the viscous-flow state, and a higher susceptibility to relative deformation.

Study of the electric field-induced domain structure transformation in BaTiO3 ceramics by high resolution methods

Ferroelectric domain structure in BaTiO3 ceramics was studied with nanoscale spatial resolution before and after poling by application of the uniform electric field. Complimentary vector piezoresponse force microscopy (PFM) and backscattered scanning electron microscopy allow visualizing domain structure in the individual grains of ceramics and study of the interaction between domains and grain boundaries. Analysis of the vector PFM images after application of electric field was used for characterization of the transformation of polarization direction in domains and domain bands. Collective dynamics of ferroelastic domains under the action of electric field is discussed.

Computational insights of two‐dimensional infrared spectroscopy under electric fields in phosphorylcholine

AbstractInfluence of static electric field in biological cells causes electroporation, which results in the increase of permeability of the cells and phospholipid bilayer. However, the precise mode of action of electric fields on phospholipid bilayer and their quantum mechanics are still unclear. Therefore, to understand the quantum‐based biological effect, we aimed to study two‐dimensional infrared (2D‐IR) spectra‐adopted quantum mechanics/molecular mechanics (QM/MM) simulations under the influence of static electric fields on Phosphorylcholine, an important component in phospholipid membrane. Initially, QM/MM studies were performed under the influence of electric field, ranging from −1.543 to 1.028 V/nm. A multilayer ONIOM model (in combination with DFT/B3LYP/6‐31G [d, p] and DREIDING force fields) was used to obtain 2D‐IR simulated spectra to calculate electrostatic interaction in the biological system. The results demonstrated that the phosphate group played an important role on α‐rotation in LUMO and the chlorine atom had a major contribution in HOMO. In addition, decreased number of hydrogen bonds demonstrated that uncoupling reaction of the P‐O stretching vibrations while the electric field was −1.542 V/nm. Moreover, we observed that the electric field is −1.028 V/nm, there is no rotational isomerization in phosphorylcholine. We concluded that the static electric fields significantly affect the anharmonic frequencies, vibration coupling and the structure of the phosphorylcholine.

Enhanced surface insulation of micron alumina/epoxy composites brought by plasma co‐hydrothermal fluorination of filler

AbstractEpoxy resin filled with micron alumina (micro‐Al2O3/ER) has been widely used in the manufacture of basin insulators for its excellent mechanical and thermal properties. However, charge dissipation properties of micro‐Al2O3/ER are too poor to ensure its surface insulation on strength under long‐term action of a DC electric field. In this paper, the modification method of plasma cohydrothermal fluorination of filler was proposed to improve its surface charge dissipation performance. The surface morphology and the element content of Al2O3 were observed, and the flashover voltage and charge characteristics of different composites were tested. Finally, the trap distribution was calculated by isothermal current attenuation method. Self‐comparison analysis with single‐step modification of plasma treatment shows that the cofluorination method has a high graft rate of fluorine element and an ideal modification effect on surface insulation, with its technical means convenient to be applied in the insulator manufacturing industry.

Effect of Thunderstorm Electric Field on the Cosmic Ray Secondary Particle Energy at LHAASO

The Large High Altitude Air Shower Observatory (LHAASO) is located in Daocheng, Sichuan. Featured with frequent thunderstorms in summer seasons, it is beneficial to study the influence of atmospheric electric field on cosmic rays during thunderstorms. In this paper, Monte-Carlo simulations are performed to study the effect of thunderstorm electric field on the cosmic ray secondary electron energy at LHAASO. The energy distribution of electrons changes under the action of electric field. In the low energy region, the total number of electrons increases significantly, while at high energies, it does not change obviously. In the electric field of 1700V·cm−1 (above the critical field of the Relativistic Runaway Electron Avalanche (RREA) process), the electrons with an energy less than 120MeV can be accelerated. When the energy is below 60MeV, the number of electrons increases exponentially with an amplitude up to about 2252%. It is consistent with the theory of RREA. When the electric field strength is 1000V·cm−1 (below the threshold of the RREA process), the electrons with an energy less than 70MeV are accelerated, and their number increases significantly, but the increase (about 86%) is far lower than that of the critical field of the RREA process. The physical mechanism for accelerating the cosmic ray secondary particles by the thunderstorm electric field is discussed in the case when the electric field is less than the runaway electric field. These results may provide important information for studying the variations of cosmic ray intensity on the LHAASO detection surface during thunderstorms.

Hybrid Magneto-Electric Materials for Sensing of Weak Electric Field Using Magnetic-Resonance Imaging

We study magneto-electric (ME) coupling mechanisms in two systems, namely ferromagnetic (FM) particles dispersed in a liquid crystal (LC) and hybrid ferroelectric (FE)–FM grains. The ME effect may appear in these systems due to the rotation of nanoparticles under the action of electric and magnetic fields. We show that a high sensitivity to the applied electric field can be achieved in both LC/magnetic particles system and hybrid FE–FM particles. In particular, even the electric field of 10 V/m essentially influences the magnetic state of these materials for proper geometric parameters. At that magnetic state, these systems can be measured in magnetic-resonance imaging (MRI) experiments. We show that MRI contrast changes up to 10% in a weak electric field. These systems can be used as MRI contrast agents for studying electrical activity in a human body.

Effect of the Electric Field on DNA Bases as Pigments for Nanodevices: A First-Principles Study.

In this work we used Density Functional Theory to simulate the molecular electronics behavior of the nitrogenous bases of human DNA under electric field effects. The results can describe some internal effects in the use of DNA-based as photoconductor or semiconductor nanodevices. For this investigation, calculations were performed to predict structural deformations, HOMO and LUMO orbitals, and thermodynamic properties of each one of the following nitrogenous bases: adenine, thymine, guanine and cytosine. All the quantities were calculated as functions of the electric field. This analysis allows us to verify the influence of the electric field in the molecular geometry of nitrogenous bases, enabling us to determine that adenine, thymine and guanine are those bases most susceptible to presenting substantial deformations when DNA is submitted to the action of an external electric field, while the molecular structure of cytosine is highly resistant to this effect.

INTENSITY OF ELECTRIC FIELD UNDER OVERHEAD POWER LINE USING CATENARY SHAPE OF CONDUCTORS

<p><span lang="EN-US"><strong><span style="font-family: Times New Roman; font-size: small;">This </span></strong></span><span lang="EN-GB"><strong><span style="font-family: Times New Roman; font-size: small;">article presents a superposition method in combination with the Coulomb’s law and the Method of image charges for calculation of the electric field distribution generated by high voltage overhead power lines above a flat surface in every dimension. Such calculations are required to ensure the operational safety of people exposed to the action of external electric field as well as to reduce the cost of people protection. The method provides options for calculation of the field around the wire of a general shape. This substantial improvement of the method could be applied to eliminate the usual error in the calculation created using approximation of catenary shape conductors by infinite straight conductors. The method has been extensively tested on a set of shapes with known analytical solutions. It has been shown that the numerical solution converges uniformly to the analytical solution and the accuracy depends only on the number of finite elements.</span></strong></span></p>

The use of an adaptive mesh based on a quadtree for modeling the final state of a quantum field system under pulsed external action

The success of using mathematical models that determine the behavior of quantum field systems in parametric spaces critically depends on the level of optimization of the procedure of finding the solution. The paper considers the problem of calculating the density of carriers arising in graphene as a result of the action of a pulsed electric field. The basis of the model is a system of kinetic equations that provide the calculation of the residual distribution function. Its integration over momentum space gives the desired carrier density. The problem lies in the high computational complexity of covering the momentum space with a uniform mesh, which provides an accurate calculation of the density for various parameters of the field momentum. Moreover, the model does not contain criteria for determining satisfactory mesh parameters. The article proposes and implements a procedure for constructing an adaptive mesh in the form of a quadtree having a variable size of covering squares. The procedure is iterative and combined with the process of calculating the values of the distribution function.

Electrically induced transformations of defects in cholesteric layer with tangential-conical boundary conditions

Electric-field-induced changes of the orientational structures of cholesteric liquid crystal layer with the tangential-conical boundary conditions have been investigated. The samples with the ratio of the cholesteric layer thickness d to the helix pitch p equalled to 0.57 have been considered. The perpendicularly applied electric field causes a decrease of the azimuthal director angle at the substrate with the conical surface anchoring. In the cells with d = 22 μm, the defect loops having the under-twisted and over-twisted areas are formed. At the defect loop the pair of point peculiarities is observed where the 180° jump of azimuthal angle of the director occurs. Under the action of electric field the loops shrink and disappear. In the cells with d = 13 μm, the over-twisted and under-twisted defect lines are formed. Applied voltage results in the shortening of lines or/and their transformation into a defect of the third type. The director field distribution near defect lines of three types has been investigated by the polarising microscopy techniques. It has been revealed that the length ratio between the over-twisted and third-type defect lines can be controlled by the electric field.

Plane electroelastic problem for a cracked piezoelectric half-space subject to remote electric field action

Plane electroelastic problem is considered for a longitudinal crack in a transversely-isotropic piezoelectric half-space subject to remote electric field perpendicular to the flat surface of the half-space. The flat surface is fully covered by thin electrode and free of mechanical load. The Lekhnitskii’ generalized complex potentials are used for the solution representation. For a case of an internal crack, boundary conditions on the flat surface are satisfied analytically by use of the Cauchy integration technique. The least-square method is applied for satisfying boundary conditions on the crack surface. An edge crack is considered. Numerical investigations are carried out for a internal or an edge crack in dependency on crack orientation and location. The results showed that one of the most dangerous crack is parallel to the flat surface. A crack perpendicular to the flat surface does not cause any significant electroelastic field in a piezoelectric half-space. Location of a crack relative the flat surface influences on electromechanical coupling near its tips.