Effects Of Electric Field Strength Research Articles

Electric Field Strength From Prefrontal Transcranial Direct Current Stimulation Determines Degree of Working Memory Response: A Potential Application of Reverse-Calculation Modeling?

BackgroundTranscranial direct current stimulation (tDCS) for working memory is an enticing treatment, but there is mixed evidence to date. ObjectivesWe tested the effects of electric field strength from uniform 2 mA dosing on working memory change from prestimulation to poststimulation. Second, we statistically evaluated a reverse-calculation method of individualizing tDCS dose and its effect on normalizing electric field at the cortex. Materials and MethodsWe performed electric field modeling on a data set of 28 healthy older adults (15 women, mean age = 73.7, SD = 7.3) who received ten sessions of active 2 mA tDCS (N = 14) or sham tDCS (N = 14) applied over bilateral dorsolateral prefrontal cortices (DLPFC) in a triple-blind design. We evaluated the relationship between electric field strength and working memory change on an N-back task in conditions of above-median, high electric field from active 2 mA (N = 7), below-median, low electric field from active 2 mA (N = 7), and sham (N = 14) at regions of interest (ROI) at the left and right DLPFC. We then determined the individualized reverse-calculation dose to produce the group average electric field and measured the electric field variance between uniform 2 mA doses vs individualized reverse-calculation doses at the same ROIs. ResultsWorking memory improvements from pre- to post-tDCS were significant for the above-median electric field from active 2 mA condition at the left DLPFC (mixed ANOVA, p = 0.013). Furthermore, reverse-calculation modeling significantly reduced electric field variance at both ROIs (Levene's test; p < 0.001). ConclusionsHigher electric fields at the left DLPFC from uniform 2 mA doses appear to drive working memory improvements from tDCS. Individualized doses from reverse-calculation modeling significantly reduce electric field variance at the cortex. Taken together, using reverse-calculation modeling to produce the same, high electric fields at the cortex across participants may produce more effective future tDCS treatments for working memory.

Influence of electric field strength applied during the solution heat treatment of the Al–Mg–Si–Cu Alloy AA6111

Abstract In the present paper, the effect of electric field strength in the range E = 0.1 – 5.0 kV/cm applied during the solution heat treatment (SHT) of the AA6111 alloy at 475° –550 °C has been determined employing resistivity. An increase in the as-quenched resistivity ρ w occurred for all field strengths, the increase being relatively rapid up to E ≈ 1 kV/cm and only slight, if at all, for higher fields. Analysis of the results gave that the field reduced the enthalpy, entropy and Gibbs free energy of solution, the amount of reduction increasing with field strength. The electric current, which occurred with application of the field during SHT, ranged from (7 × 10 –3 to 4 × 102) μA, increasing with field strength and SHT temperature, but decreasing with time during the SHT. The role of the current in the enhancement of ρ w by the field is not clear.

Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions.

In this review, the research conducted by the authors on anodic oxide films on aluminum is described, paying particular attention to how the electric field strength, as a factor other than voltage, controls the nanostructures and properties of the films. It will also be indicated what factors contribute to the formation of defects, which, in contrast to the ideal or model film structure, contains a significant number of defects in the film. In addition to electrochemical measurements, the films were examined with a variety of advanced instruments, including electron microscopes, to confirm the “reality of film nanostructure” from a slightly different angle than the conventional view. The following topics on anodic films formed in four types of major anodizing electrolytes are discussed: pore initiation process, steady-state porous structure, sealing mechanism, the relationship between cell parameters and voltage/electric field strength, amount and depth of anion incorporation, electrolyte types, radial branching of pores, atypical pore structures, defect formation mechanism, self-ordering, Al coordination number, and the creation of α-alumina membranes.

Effect of pulsed electric field‐assisted extraction on recovery of sulforaphane from broccoli florets

AbstractSulforaphane (SFN) is an isothiocyanate occurring in broccoli, with exceptional health‐beneficial properties, such as anticancer, anti‐inflammatory, and anti‐hypertensive effects. Processes to maximize SFN content in broccoli developed until now are expensive and SFN bioavailability in the vegetable is not optimal. To increase SFN extraction yield from broccoli florets, it was proposed to complement traditional solvent extraction with pulsed electric field (PEF) as tissue disruption method enabling the reduction of mass transfer resistance in vegetable matrices. Tissue disruption methods enhance the performance of this process because it reduces mass transfer resistance. PEF is an innovative technology recently introduced in the food industry. We studied the effect of electric field strength (10 and 15 kV/cm) and time of exposure to the PEF treatment (30, 90, and 150 s) on the recovery of SFN from broccoli florets, using a statistical factorial design. Electric field strength and exposure time significantly affected SFN recovery in a positive way. PEFs increase SFN recovery by more than 50% compared to traditional extraction. This result was achieved at 150 s exposure to PEF and 10 kV/cm.Practical ApplicationsThe use of pulsed electric fields significantly improved sulforaphane recovery from broccoli in comparison with traditional extraction methods. Even though in this work the raw material was commercial broccoli heads, it is most likely that the results obtained here can be replicated using low‐value raw material, such as broccoli heads that do not meet commercial standards or crop discards. Accordingly, PEF technology constitutes an option for valorization of Brassicaceae agroindustry discards.

Effect of electric field strength stimulation on phase evolution in flash sintered hydroxyapatite at high-temperature range

ABSTRACT Flash sintering (FS) is becoming a popular densification route for high-temperature oxide ceramics because of its rapid sintering performance. In the current study, bar-shaped hydroxyapatite (HA) specimens were hung between two Pt wire electrodes and consolidated by FS through a direct electric field at a constant furnace temperature (1000°C or 1100°C) in air. The electric field facilitated the sintering of HA at relatively lower furnace temperatures than that obtained using the conventional sintering method. The voltage required for the onset of the flash decreased with increasing furnace temperature. The effects of the DC electric field strength at different sintering furnace temperatures were examined in terms of the phase evolution and stability of HA. HA phase dissociation was not observed regardless of the electric field strength or furnace temperature because of the very short FS time. Higher grain growth with fast densification in the flashed-sintered HA samples occurred with increasing electric field strength at each furnace temperature.

Alignment dynamics of single-wall carbon nanotubes under electric field in different surfactant solutions

The dynamics of metallic single-wall carbon nanotube (SWCNT) alignment inside various viscous media under electric field is investigated in this simulation work for the manifestation of macroscale aligned SWCNT films. An alternating current (AC) electric field was applied to the liquid solution of several surfactants (DIW, DMF, CHEX, SDS, and DOC) containing SWCNTs. The time required for the SWCNTs to get aligned to the applied AC electric field was simulated for different initial conditions for all the surfactants. An analytical model based on dielectrophoresis induced torque was employed. The model considers the viscosity and conductivity of the surrounding medium. The influence of SWCNT length, SWCNT radius, and frequency of the AC field on the assembly of SWCNTs were studied. Our analysis showed that a longer and narrower SWCNT prompts faster assembly to an aligned SWCNT aggregation. Furthermore, the effect of the concentration of SDS and the effect of electric field strength for DIW surfactant were also investigated. Viscosity plays a significant role in the alignment process. Slower SWCNT alignment is caused by a medium of higher viscosity.

Effect of electric field strength on deformation and breakup behaviors of droplet in oil phase: A molecular dynamics study

Electrostatic demulsification process is frequently accompanied by the occurrence of droplet breakup, which will cause a fall in the efficiency of droplet electro-coalescence. To uncover mechanisms of droplet deformation and breakup in the water-in-oil (W/O) emulsion, molecular dynamics simulations were used here to investigate the influence of electric field strength on the motion behavior of a single droplet. The results showed that with increasing field strengths, the droplet underwent deformation, breakup at one end, breakup at both ends, and breakup in the middle part, respectively, which is consistent with the experimental findings at mesoscopic scales. Quantum chemical calculations and noncovalent interaction analysis found that non-bonded potential energies between water molecules played a dominant role in droplet morphology transformation, supporting the reasonableness for gas-phase molecules instead of oil-phase molecules. Besides deformation ratio (Dr), solvent accessible surface area (SASA) is also an important parameter for characterizing the degree of droplet deformation at the molecular level. Electrostatic attraction among water molecules and external electric field force were found to be the key factors affecting droplet deformation. At field strength of 1.4 V nm−1, the majority of the hydrogen bonds between H2O had a very brief lifetime, 0.79 ps. Hydrated ions and ion migration perform critical roles during droplet breakup. This study fills an important gap in the molecular dynamics study of electrostatic coalescence by introducing real oil molecules.

Experimental Study on the Performance of a Novel Compact Electrostatic Coalescer with Helical Electrodes

As most of the light and easy oil fields have been produced or are nearing their end-life, the emulsion stability is enhanced and water cut is increasing in produced fluid which have brought challenges to oil–water separation in onshore and offshore production trains. The conventional solution to these challenges includes a combination of higher chemical dosages, larger vessels and more separation stages, which often demands increased energy consumption, higher operating costs and larger space for the production facility. It is not always feasible to address the issues by conventional means, especially for the separation process on offshore platforms. Electrostatic coalescence is an effective method to achieve demulsification and accelerate the oil–water separation process. In this paper, a novel compact electrostatic coalescer with helical electrodes was developed and its performance on treatment of water-in-oil emulsions was investigated by experiments. Focused beam reflectance measurement (FBRM) was used to make real-time online measurements of water droplet sizes in the emulsion. The average water droplet diameters and number of droplets within a certain size range are set as indicators for evaluating the effect of coalescence. We investigated the effect of electric field strength, frequency, water content and fluid velocity on the performance of coalescence. The experimental results showed that increasing the electric field strength could obviously contribute to the growth of small water droplets and coalescence. The extreme value of electric field strength achieved in the high-frequency electric field was much higher than that in the power-frequency (50 Hz) electric field, which can better promote the growth of water droplets. The initial average diameters of water droplets increase with higher water content. The rate of increment in the electric field was also increased. Its performance was compared with that of the plate electrodes to further verify the advantages of enhancing electrostatic coalescence and demulsification with helical electrodes. The research results can provide guidance for the optimization and performance improvement of a compact electrocoalescer.

Molecular dynamics study of electrocoalescence of pure water and salty nanodroplets

The mechanisms governing the electrocoalescence between droplets are intricate owing to the presence of many influential parameters. In this work, we conduct molecular dynamics simulations to explore the effects of electric field strength and ionic concentration on the electrocoalescence behaviors of one pure water droplet and one salty droplet. The dynamic evolution is difierent from that for two identical droplets. The electric field strengths are chosen near the critical value. When the electric field strength is less than the critical value, the coalescence process is similar regardless of the ionic concentration of the salty droplet. The analysis on the mobility of ions demonstrates that the diffusion time of ions is much longer compared to the characteristic time of deformation of the coalesced droplet. At a stronger electric field than the critical field, the coalescence behavior exhibits dependence on the ionic concentration. For cases of high ionic concentrations, a rebounding behavior between two droplets is identified due to aggregation of ions close to the contact region of the droplets. Further, we also investigate molecular interaction energy, hydrogen bonding and ejection of daughter droplets during the electrocoalescence. Our study reveals that the coupling effect between the electric field and the ionic concentration plays an important role in controlling the electrocoalescence behavior of droplets.

Analysis of Effect Electric Field Strenght on Safe Distance Below Main Substation Busbar 150 kV

This research is to analyze the effect of electric field strength on the safe distance under the 150kV substation busbar. The research was conducted at 150 kV substation Rancaekek, substation Rancakasumba, substation Cikasungka. The electric field exposure threshold value according to SNI, ICNIRP, IRPA/INIRP and WHO is 10kV / m for the working community. The lowest distance of the busbar conductor to the ground surface is 7.5m. Measurements and calculations of transverse electric field strength from busbar 1 to busbar 2. The height of the test point is 0 m to 2.3 m from the ground surface. From the results of the calculation of the electric field, strength obtained that the shortest minimum safe distance is 7.48 m, while the highest minimum safe distance is 7.88 m. From the results of the measurements of the electric field From the results of measurements of electric field strength obtained that the fastest duration of electric field exposure was 4.42 hours while the longest electric field exposure duration was 5.75 hours. From the calculation of the electric field, strength obtained that: the fastest duration of electric field exposure is 7.56 hours while the longest duration of electric field exposure is 7.91 hours.

Ice nucleation in high alternating electric fields: Effect of electric field strength and frequency.

Icing is a severe problem for many technical systems such as aircraft or systems for high-voltage power transmission and distribution. Ice nucleation in water droplets is affected by several influencing factors like impurities or the liquid temperature, which have been widely investigated. However, although an electric field affects nucleation, this influence has been far less investigated and is still not completely understood. The present work is focused on the influence of high alternating electric fields on ice nucleation in sessile water droplets, which is examined for a systematic variation of the electric field frequency and strength. All experiments used to determine the influence of a single parameter like the electric field strength or frequency are performed with the same set of droplets to ensure well-defined conditions and a high repeatability of the procedure. For each parameter variation a large number of nucleation events is observed and analyzed. Droplet survival curves and the nucleation site density are used to analyze the experiments and to determine the influence of the electric field on ice nucleation. Especially for high electric field strengths, a significant influence on nucleation is observed. Some droplets freeze earlier, which leads to a higher median nucleation temperature. On the other hand, the lowest temperature required to freeze all droplets is almost constant compared to the reference case without an electric field. It is shown that not all droplets are affected by the electric field in the same way, but the influence of the electric field on ice nucleation is rather of singular nature. In addition, the frequency of the applied electric field has an impact on the nucleation behavior. The present experimental data quantitatively demonstrate the effect of an electric field on ice nucleation and improves our understanding of heterogeneous nucleation of supercooled water subjected to high alternating electric fields.

Heat Transfer Features under Bubble Boiling in an Electroconvection Flow

The effects of electric field strength and interelectrode distance on the main parameters of boiling under conditions of electrohydrodynamic flow have been studied. It has been found that the field effect exhibits a decrease with increasing heat flux density. The optimum interelectrode distance corresponding to the most intense heat transfer has been determined. Based on visual observations and high-speed cinematography of the process, the hydrodynamic pattern of the two-phase flow has been analyzed in interrelation with the intensity of heat transfer. The calculated relationships are in good agreement with the experimental results.

Response Surface Method Analysis on Electro-Enhanced Technique for Remediation of Cadmium Contaminated Soil

In view of the problems of long remediation time, high energy consumption and low remediation efficiency in electrokinetic remediation of heavy metal contaminated soil, Cd was used to simulate heavy metals in contaminated soil, and response surface method (RSM) was used to optimize the factors influencing electrokinetic remediation. Central Composite (CCD) experimental design method was taken to study the effects of electric field strength, remediation time and water content on removal rate of Cd in soil. Also, polynomial regression mathematical model and optimal reaction conditions were provided for Cd pollution in electrokinetic soil remediation. The simulated equation F was 15.67, the correlation coefficient was 0.9338, and the adjustment correlation coefficient was 0.9042, indicating good regression and strong significance of the equation. The model results showed that, for the optimal experimental conditions, electric field strength was 2.25V·cm-1, the remediation time was 120.79h, and the water content was 17.06%. On the basis of such reaction condition, intermittent current flow method was adopted d to further enhance the electrokinetic remediation effect. The cadmium removal rate in the soil was increased by 3.17%, 2.86% and 2.43%, respectively, and the electric energy consumption was decreased by 10.54%, 11.28% and 9.97%, respectively, suggesting that the method could effectively improve the removal rate of Cd and reduce energy consumption.

Numerical investigation of a conducting drop’s interaction with a conducting liquid pool under an external electric field

A charged conducting drop suspended in an insulating medium shows non-coalescence with an interface under high strength of an externally applied electric field. We perform numerical simulations of the non-coalescence phenomenon to understand the underlying physical mechanisms and the effect of electric field strength and fluid conductivity on the coalescence behavior of a conducting drop with a conducting liquid pool under highly viscous conditions. We show that two factors primarily govern the coalescence or non-coalescence of the drop with the interface. First, the magnitude of the charge transfer time scale (which governs the rate of charge transfer during contact between the drop and the pool) relative to the time scale of the capillary waves. Second, the strength of the electric forces compared to the viscous forces. We further show that for the case of macro drops (D∼2 mm), charge transfer by fluid convection dominates charge conduction at lower electric conductivities (σ∼10−8 S/m) only. Finally, we explain the non-dependence of secondary droplet’s size and charge on the fluid’s electric conductivity as observed in the experiments.

Verification of the effect of electric field strength and gradient on the elongation of DNA molecules using the confinement effect

Verification of the effect of electric field strength and gradient on the elongation of DNA molecules using the confinement effect

Ohmic heating effect on enzyme assisted aqueous extraction of rice bran oil

This study explored the improvement of oil recovery from rice bran by pre-treatment of ohmic heating prior to enzyme assisted aqueous oil extraction process (EAEP). A full factorial design was utilized to investigate the effect of electric field strength (OH450V, OH550V and OH650V), end point temperature (75, 85 and 95°C) and holding time (0, 5 and 10 min.). Incremental oil recovery through combined EAEP and ohmic heating ranged from 3.5% to 15.5% over EAEP alone. The electric field strength of OH650V at 95°C for 10 min holding time yielded maximum oil recovery (82%) for combined ohmic and EAEP treatment. The extracted oil was comparatively darker in colour than examined market edible rice bran oil. Pre-treatment of ohmic heating with EAEP on rice bran slightly increased the FFA in oil (1.89–2.24%) compared to market edible rice bran oil.

Field confinement effect induced by nonlinear interface between nonlinear focusing and defocusing media

We describe the non-symmetrical spatial-distributed electric field near the thin optic layer with nonlinear properties that separated two focusing and defocusing media with Kerr-type nonlinearity differing by values of refractive index. The nonlinear Schrödinger equation (NLSE) with nonlinear potential containing two parameters describes the distribution of electric field strength in adiabatic approximation. The problem is reduced to the solution of NLSEs at the half-spaces with the nonlinear boundary conditions at the interface plane. We obtain five new types of nonlinear stationary states describing the confinement effect of electric field strength across the interface. The field confinement effect is the localization of nonlinear spatially periodic wave during the transition from a one half-space to another one where the field distribution is monotonically damping from the interface. We derive and analyze the frequencies of field confinement effect possibility in dependence of media and interface characteristics.

Investigation of electroosmotically induced pressure gradient in rectangular capillaries

This paper investigates the pressure gradient created by electroosmotic effect in closed-end rectangular capillaries with DC electric field. An existing theoretical model was reviewed. Experiments were carried out to validate the model. The capillaries were square in geometry, 50 mm long with internal sizes of 75 µm and 100 µm. The electrolyte was NaCl solution with concentrations of 0.0005 M and 0.01 M. The range of electric field tested was between 10 and 60 kV/m. Comparison of numerical and experimental data showed that they were generally in good agreement in the range of operating conditions tested. The accuracy of the theoretical model can be improved further by using an accurate zeta potential estimation model. The effects of electric field strength, electrolyte concentration and capillary size to the induced pressure gradient were also studied. It was found that induced pressure gradient was linearly proportional to electric field strength, with a rate of 2 kPa/m for every 10 kV/m increment of field strength. Induced pressure gradient was not affected significantly by electrolyte concentration in the range of conditions tested, regardless of capillary size. Reduction of capillary size increased induced pressure gradient. The rate of increase was higher with a smaller capillary size.

Opening and Closing of Particle Shells on Droplets via Electric Fields and Its Applications.

Active, tunable, and reversible opening and closing of particle shells on droplets may facilitate chemical reactions in droplets and enable various small-scale laboratory operations, including online detection, measurement, and adjustment of droplet liquid. Manipulating various types of particle shells in a controlled manner requires new routes. This work provides a new strategy for controlling the spatial arrangement of particle-covered oil droplets using electric fields that expands the application of responsive droplets beyond the abovementioned examples. The behavior of stimulated particle-covered droplets is exploited in multiple ways: to form an active smart device, fabricate Janus and patchy shells, create an online diagnostic tool, and produce a tool for fundamental studies. Electric fields are used here to manipulate particle films on oil droplets through the synergetic action of droplet deformation and electrohydrodynamic liquid flows. First, the effects of electric field strength and liquid viscosity on droplet deformation, surface particle arrangements, and dynamics are examined in detail. Then three examples of applications of responsive particle-covered droplets are demonstrated. Our results show that the reversible opening and closing of the droplet's shells, composed of various types of particles, can be conveniently achieved through electric fields, opening up a new possibility for applications in optics, clinical diagnostics, microfluidics, and material engineering.

Enhancement of ablation rate and production of colloidal nanoparticles by irradiation of metals with nanosecond pulsed laser in presence of external electric field

This paper presents the results of experimental study on the effect of electric field on the ablation rate during the nanosecond pulsed laser ablation of aluminum and copper in deionized water. The effect of electric field strength on the material removal rate and its mechanisms were investigated both in the electric field parallel and perpendicular to the laser beam path schemes. The ablation rate was estimated by measuring the dimensions of craters on the target induced by laser. The crater dimensions and optical properties of the produced colloidal nanoparticles were characterized by means of optical microscopy and UV–Vis absorption spectroscopy, respectively. The results indicate that pulsed laser ablation in the presence of an electric field significantly leads to higher material removal rate. The experimental results also confirm that the crater geometry extremely depends on the direction of the electric field with respect to the laser beam direction. The UV–Vis spectra show that the nanoparticles production efficiency increases with increasing the electric field strength.