Electrical Potential Difference Research Articles

Biodegradable Piezoelectric-Conductive Integrated Hydrogel Scaffold for Repair of Osteochondral Defects.

Osteochondral injury is a prevalent condition for which no specific treatment is currently available. This study presents a piezoelectric-conductive scaffold composed of a piezoelectric cartilage-decellularized extracellular matrix (dECM) and piezoelectric-conductive modified gelatin (Gel-PC). The piezoelectricity of the scaffold is achieved through the modification of diphenylalanine (FF) assembly on the pore surface, while the conductive properties of scaffold are achieved by the incorporating poly(3,4-ethylenedioxythiophene). In vitro experiments demonstrate that bone marrow mesenchymal stem cells (BMSCs) undergo biphasic division during differentiation. In vivo studies using a Parma pig model of osteochondral defects demonstrate that the piezoelectric-conductive scaffold exhibits superior reparative efficacy. Notably, the generation of electrical stimulation is linked to joint movement. During joint activity, mechanical forces compress the scaffold, leading to deformation and the subsequent generation of an electric potential difference. The positive charges accumulated on the upper layer of the scaffold attract BMSCs, promoting their migration to the upper layer and chondrogenic differentiation. Meanwhile, the negative charges in the lower layer induce the osteogenic differentiation of BMSCs. Overall, this piezoelectric-conducive scaffold provides a promising platform for the effective repair of osteochondral defects.

Assessing key parameters in simultaneous simulation of rapid kinetics of chlorophyll a fluorescence and trans-thylakoid electric potential difference.

Our study attempts to address the following questions: among numerous photosynthetic modules, which parameters notably influence the rapid chlorophyll fluorescence (ChlF) rise, the so-called O-J-I-P transient, in conjunction with the P515 signal, as these two records are easily obtained and widely used in photosynthesis research, and how are these parameters ranked in terms of their importance? These questions might be difficult to answer solely through experimental assays. Therefore, we employed an established photosynthesis model. Firstly, we utilized the model to simulate the measured rapid ChlF rise and P515 kinetics simultaneously. Secondly, we employed the sensitivity analysis (SA) tool by randomly altering model parameters to observe their effects on model output variables. Thirdly, we systematically identified significant parameters for both or one of the kinetics across various scenarios. A novel aspect of our study is the application of the Morris method, a global SA tool, to simultaneously assess the significance of model parameters in shaping both or one of the kinetics. The Morris SA technique enables the quantification of how much a specific parameter affects O-J-I-P transient during particular time intervals (e.g., J, I, and P steps). This allowed us to theoretically analyze which step is more significantly influenced by the parameter. In summary, our study contributes to the field by providing a comprehensive analysis of photosynthesis kinetics and emphasizing the importance of parameter selection in modelling this process. These findings can inform future research efforts aimed at improving photosynthesis models and advancing our understanding of photosynthetic processes.

Exposure to natural stray currents of low voltage affects the behaviour and some stress biomarkers of weaned piglets

With the modernisation of pig breeding facilities, pigs may be exposed to both on-farm and off-farm sources of stray voltages. Data from ruminant species suggest that exposition to stray voltages may be a source of stress and impair animal welfare, but data are scarce for pigs. The aim of this study was to evaluate the impact of stray currents of voltages under 0.5 Volts in pig housing on piglet behaviours and some biomarkers after weaning. Two replicates of 820 piglets were reared in a farm naturally exposed to stray voltage for seven weeks. The difference in electrical potential between the floor and each drinker and feeder was measured every two weeks. Piglets exposed to high-voltage drinkers (HVD > 125 mV) spent more time orally manipulating pen mates (P = 0.0031). They also spent more time lying inactive with open eyes (P = 0.0027) and less time nosing pen mates (P = 0.043), but these effects were influenced by the voltage in feeders (P = 0.0021 and P = 0.024, respectively). Piglets exposed to high-voltage feeders (HVF > 50 mV) spent less time lying with their eyes closed (P = 0.024) and more time aggressing pen mates (P = 0.0081). Fifty days after entering the farm, blood hydroperoxide concentration was higher in piglets exposed to HVD (P = 0.039). The increase in socio-negative behaviours and oxidative stress in pigs exposed to stray voltages in pig housing suggested that stray voltages might have moderate detrimental consequences for piglets in post-weaning facilities.

Effect of voltage amplitude and frequency on the characteristic parameters of a piezoelectric actuated micro-blower

Micro-blower is an innovative device that is used for sensitive applications such as electronics cooling, avionics and the medical field. It features a piezoelectric disc (PED)-diaphragm assembly. A 3D computational model of micro-blower is developed and simulated using COMSOL Multiphysics and studied its characteristic parameters such as maximum displacement (w), average velocity (w̅’), maximum von Mises stress (Tv), total kinetic energy (EK), total elastic strain energy (EU) and total electric energy (EE). The frequency-dependent electric potential difference was supplied to the Lead Zirconate Titanate (PZT-5H) PED. Seven different square wave ultrasonic frequencies were used as input for the PED ranging from 22 to 28 kHz, a resonance frequency is proposed in the study. There were three peak-to-peak voltages, Vp-p, of 10, 15 and 20 V were used. The characteristic parameters were estimated for the diaphragm, PED and PED-diaphragm assembly. For a 20 Vp-p and at 27 kHz, the maximum w reached 1.987 µm. The maximum Tv on the diaphragm surface and EE developed in the PED were 29.925 MPa and 442.98 nJ, respectively. The present numerical results were validated with previous studies on a similar domain and were in good agreement.

Fate of micropollutants in struvite production from swine wastewater with sacrificial magnesium anode

Struvite recovery shows significant potential for simultaneously recovering nitrogen (N) and phosphorus (P) from swine wastewater but is challenged by the occurrence and transformation of antibiotic residuals. Electrochemically mediated struvite precipitation with sacrificial magnesium anode (EMSP-Mg) is promising due to its automation and chemical-free merits. However, the fate of antibiotics remains underexplored. We investigated the behavior of sulfadiazine (SD), an antibiotic frequently detected but less studied than others within the EMSP-Mg system. Significantly less SD (≤ 5%) was co-precipitated with recovered struvite in EMSP-Mg than conventional chemical struvite precipitation (CSP) processes (15.0 to 50.0%). The reduced SD accumulation in struvite recovered via EMSP was associated with increased pH and electric potential differences, which likely enhanced the electrostatic repulsion between SD and struvite. In contrast, the typical strategies used in enhancing P removal in the EMSP-Mg system, including increasing the Mg/P ratio or the Mg-release rates, have shown negligible effects on SD adsorption. Furthermore, typical coexisting ions (Ca2+, Cl−, and HCO3−) inhibited SD adsorption onto recovered products. These results provide new insights into the interactions between antibiotics and struvite within the EMSP-Mg system, enhancing our understanding of antibiotic migration pathways and aiding the development of novel EMSP processes for cleaner struvite recovery.

Apply frequency response function schemes for damage detection in composite nanoscale-pipes under transient conditions

Knowledge of Nanoscale-structures sustainability is strongly associated with the reliability and the performances of Nano-electro-mechanical systems such as Nanoactuators and Nano-sensors that are widely used in bio-applications. Therefore, the damages in these types of infinitesimal systems must be quickly and accurately detected, located, and repaired. In this study, a novel damage detection framework in Carbon Fiber Reinforced Polymer (CFRP) composite Nanoscale-Pipes (CNP) subjected to the fatigue effect of water internal pressure and thermal effect via Nanoscale-electrical capacitance sensors (NECS). First, a finite element model (FEM) of CNP damage is established, then the electrical potential difference (EPD) between the Nanoscale-electrodes (NEs) pairs before and after damage is measured. The distributed NECS measuring nano-electrodes are installed around the CNP and load the transient external excitations between each other. It is proposed and applied the transfer function (TF) of the CNP as an "open loop control" system to reflect the evolution of damage. The accuracy and reliability of the suggested technology are verified through the experimental results available in the literature. The results show that when the damage under NEs pairs has begun to grow, the signal amplitude value will change suddenly and sensitively, which demonstrates the effectiveness of the proposed method and the good potential for engineering applications.

A unified model for mechanical deformations of single stranded DNA-microbeam biosensors considering surface charge effects

A unified energy model for mechanical deformation of the microbeam included by single stranded DNA (ssDNA) adsorption considering the surface charge density on substrate is investigated. First, a free energy model is established to quantify the deflection and axial displacement of the microbeam, the ion concentration in the solution, as well as the electric potential distribution inside and outside the ssDNA film with a uniform surface charge density. Then, the governing equations and corresponding boundary conditions are obtained by minimizing the free energy with three types of variational variables. And, the relationship of the electric potential difference between the two sides of the ssDNA film and the deformation of microcantilever and simply support beam are determined in different solutions (1: 1, 1: 2, 1: 3). Moreover, the numerical solutions of the electric potential distribution inside and outside the ssDNA film are investigated by using the finite difference method and Newton's iteration method. The results suggest that the nonlinear model for electric potential distribution should be used under higher surface charge density. By fitting and comparing the present predictions with Arroyo-Hernandez's experimental data, the effectiveness of the model is verified. The study shows that the surface charge density can modulate the magnitude and direction of ssDNA-microbeam deformation, which also indicates that there exists a critical surface charge density, causing the failure of ssDNA-microbeam detection. These conclusions are helpful for designing the efficient biosensors based on DNA-microbeam.

Analogy among electrical potential difference and gravitational dotencial difference on the teaching physics

The current research proposes to create a strategy that enables solid learning of the topicof electrical potential, through an analogy between electrical and gravitational potentials. The proposed activity conceives the use of low-cost materials with the objective of bringing physical knowledge closer to the students’ daily lives. This is because a certain lack of interest in Physics has been perceived in the focus population of this study, which in some way is contradictory, since thepresence of this science in our daily lives is manifested in the various activities that we carry out.in the context in which we are inserted. As well as, in the widespread use of new information andcommunication technologies to which the human species has been having access in recent years. For its part, for the creation of the aforementioned strategy, the use. The methodology includes a review of the available literature on the subject and has a qualitative-quantitative tendency, referring to the collected data’s analysis during the experience. The results shows that there were better students performances during the second stage of the research process. Which allows us to conclude that teaching Physics through analogies developed by the teachers of this subject enables better learning of this science to the extent that scientific and everyday knowledge are linked.

Inactive Overhang in Silicon Anodes

Li-ion batteries contain excess anode area to improve manufacturability and prevent Li plating. These overhang areas in graphite electrodes are active but experience decreased Li+ flux during cycling. Over time, the overhang and the anode portions directly opposite to the cathode can exchange Li+, driven by differences in local electrical potential across the electrode, which artificially inflates or decreases the measured cell capacity. Here, we show that lithiation of the overhang is less likely to happen in silicon anodes paired with layered oxide cathodes. The large voltage hysteresis of silicon creates a lower driving force for Li+ exchange as lithium ions transit into the overhang, rendering this exchange highly inefficient. For crystalline Si particles, Li+ storage at the overhang is prohibitive, because the low potential required for the initial lithiation can act as thermodynamic barrier for this exchange. We use micro-Raman spectroscopy to demonstrate that crystalline Si particles at the overhang are never lithiated even after cell storage at 45 °C for four months. Because the anode overhang can affect the forecasting of cell life, cells using silicon anodes may require different methodologies for life estimation compared to those used for traditional graphite-based Li-ion batteries.

On a Method for Calculating Bending and Shear Vibrations of a Porous Piezoelement in the Low-Frequency Region

Introduction. Devices for collecting and storing energy from the external environment are low-power sources of electric energy that are actively used. The autonomous devices for monitoring the damaged condition of various structures include them as well. The working element of these devices is a piezoelectric generator (PEG) — a converter of mechanical energy into electrical energy. The design of PEG is associated with the preliminary construction of their mathematical and computer models, with the help of which the calculation and optimization of structures is carried out. One of the ways to model and calculate PEG is to develop approximate calculation methods based on applied theories. The applied theories for calculating bending vibrations of multilayer piezoactive plates are known and previously developed in the literature. However, in the scientific literature there is not enough information about bending and shear vibrations as a tool for improving the efficiency of engineering calculations of the described structures. The objective of this work was to develop an applied method for calculating bending and shear vibrations of piezoceramic plates, including porous ones.Materials and Methods. Piezoceramics PZT-4, including porous ones, were used as the piezoactive material of the plate. When using porous ceramics, the rigidity of the structure decreased to a greater extent than the piezoelectric modules, which made it possible to obtain a more effective PEG under mechanical action. The mathematical formulation was carried out within the framework of the linear theory of electroelasticity with plate polarization in thickness. The sides of the plate were electrodated, the right side was fixed, and a smooth contact in the vertical wall was set on the left side. Steady-state vibrations of the plate were caused by pressure on the front surfaces of the plate or the difference in electrical potentials at the electrodes. To calculate the characteristics of PEG, the authors proposed an applied theory based on hypotheses about the distribution of characteristics of the stress-strain state and the electric field.Results. Transverse vibrations of a piezoceramic plate in the low-frequency region (below the first bending-shear resonance) were studied. Due to the fact that the mathematical formulation was considered within the framework of the linear theory of elasticity, the problem was divided into the sum of two. The first one took into account the mechanical effect: a distributed load and a transverse force at the left end acted on the front surfaces of the plate, and the potentials at the electrodes were zero. In the second task, there were no mechanical loads, but the potential difference was set at the electrodes. Based on hypotheses about the distribution of deformations, mechanical stresses and electric potential, both problems were reduced to a system of ordinary differential equations and boundary conditions. Comparison with the results of calculations by the finite element method in the ACELAN package showed the adequacy of the proposed applied theory in the low-frequency region.Discussion and Conclusion. Since the formulation of the problem was considered in the linear theory of electroelasticity, and the low-frequency region was studied, the work succeeded in dividing the problem of bending-shear vibrations of a porous piezoceramic plate into two: bending — with mechanical action at zero potentials, and shear — when setting the potential difference and zero mechanical action. The corresponding hypotheses about bending and shear were used. Two systems of ordinary differential equations and boundary conditions, which were solved analytically without the use of “heavy” finite element packages, were constructed. To compare the results and confirm the adequacy of the proposed method, the finite element modeling of such tasks was carried out in a specialized ACELAN package. The comparison showed that the error in determining displacements and electric potential when using this approach, in the case of setting mechanical loads and potential differences, did not exceed 6%. The method developed in the paper can be applied in the design of piezoelectric generators for energy storage in the low-frequency region.

Delineating leachate-groundwater interaction at Gyadi-Gyadi dumpsite, Kano, using natural electromagnetic (EM) field detector and Vertical Electrical Sounding (VES)

Geophysical investigations are mostly used for hydrogeological studies, mining, geotechnical investigation and environmental surveys. Geophysical investigation of groundwater within the dumpsite is highly critical because the extent of interaction between leachate plume/contaminated zone and aquifer zones could significantly reduce groundwater quality. The textural complexity and clay content of soils could change their electrical properties, thus reflecting inconsistent resistivity values using the resistivity method. This research investigates the extent of leachate infiltration from waste dumpsite into groundwater at Gyadi-Gyadi Kano State, using natural Electromagnetic (EM) field and Vertical Electrical Sounding (VES) methods. Six natural EM profiles were obtained in various locations within the study area using PQWT-TC 150 model. Six VES data points were occupied along the EM profile lines using SAS 1000 ABEM resistivity meter. The two techniques employed revealed some intercalations of low resistivity (conductive) as well as very low electrical potential differences in the study area. The low resistivity media are mixtures of leachates into groundwater units, thereby creating formations from the surface to a depth of about 40 m. The first and second layers have experience leachate-aquifer interaction in the northern, southern and eastern parts of the study area to about 40 m depth, and the leachate-aquifer interaction has extended to the deep aquifer of about 70 m depth at the western part. Shallow aquifer has not been infiltrated by leachate at about >100 m away from the waste dumpsite. Therefore, for potable groundwater exploitation in this area, it is advised that boreholes should be sited >100 m away from the dumpsite, where leachate-aquifer interaction has attenuated. The natural EM field detector is evidently constrained by issues of over-generalization and summation of potential values, probably due to its relatively low resolution. Hence it might not be capable of precisely delineating varying geological units. In contrast, the resistivity method is able to delineate and discretize the subsurface into sub-units of different resistive zones. This implies that VES is better suited for accurately defining the true subsurface geology, while the NEF detector is effective for determining the extent of a leachate plume.

Exploring deeper groundwater in a dolomite aquifer using telluric electric frequency selection method geophysical approach

Several Telluric Electric Frequency Selection Method (TEFSM) geophysical equipment is now available for groundwater exploration. However, case studies on its application in different hydrogeological settings are limited. This study investigates the TEFSM geophysical approach's application to identify groundwater potential sites for drilling production boreholes in a dolomite aquifer in South Africa. Field tests comprised geophysical surveys using the TEFSM approach to collect vertical and horizontal electrical potential difference profile data from four sites. Evaluation of the potential difference profile data before borehole drilling indicated that two sites had groundwater potential. Two sites were therefore prepared for drilling. Corroboration of the survey data and drilling lithology show that the TEFSM investigated up to 230 m depth and delineated the thickness of the dolomite aquifer from 170 m to 210 m. The dolomite aquifer was delineated based on low EPD contrast ranging from 0.042 to 0.083 mV. The ability of the TEFSM to delineate the dolomite aquifer at a depth of 170–210 m highlights the technical capability of the approach in exploring deeper aquifers that are important to meet the rising demand for freshwater. More research is necessary to establish the EPD ranges of aquifer lithology in different hydrogeological settings. It will assist in the interpretation of the data by field practitioners to optimise the application of this TEFSM technology in groundwater investigations.

Analytical description of the ionic relaxation in the presence of surface adsorption

The temporal evolution of the surface electric field in a cell in the presence of ionic adsorption is investigated. The analysis is performed in the framework of the Poisson–Nernst–Planck model, based on the conservation of particles and the equation of Poisson for the actual electric potential across the cell, assuming that only the ions of a given sign are mobile. The adsorption is described using a kinetic equation of Langmuir’s type. The simple case of small adsorption is considered, in which the saturation effect can be neglected, and the fundamental equations of the model can be linearized. In this framework, the effective relaxation time describing the dynamics of the system is evaluated, as well as the profiles of the ions and the electric field. The case in which the sample is a half-space is first considered. A more realistic situation where the sample is a slab of thickness d, limited by two identical or different electrodes, is analyzed too. The difference in electric potential due to the adsorption phenomenon between the electrodes is determined. Our analysis shows that its time dependence, when the electrodes have different adsorption properties, is not monotonic.

Acute intracardiac electrogram changes and their relation to pulsed field ablation dose in porcine left ventricle

Abstract Background Pulsed field ablation (PFA) is an emerging cardiac ablation modality based on irreversible electroporation with promising preclinical and clinical results. Acute reduction of intracardiac electrograms (bipolar iEGMs) is consistently observed, similar to other ablation modalities, e.g. radiofrequency ablation. We and others have previously reported lesion size dependence on PFA dosing. However, the relevance of iEGM changes and their dependence on the PFA dose is not established. Furthermore, our study shows that unipolar iEGM signals may contain additional information about the effects of PFA in cardiac tissue. Purpose To quantify the effect of different PFA dosing on changes observed in bipolar and unipolar iEGMs within 5 minutes after the ablation. Methods In total, PFA was applied endocardially at 40 sites in the left ventricles of 8 pigs via a 5 mm tip catheter using a modified decapolar catheter in the inferior vena cava for current return (all electrodes). The following PFA doses (voltage and number of pulse trains) were used: 1000 V, 4 trains; 1300 V, 4 trains; 1500 V, 1 train; 1500 V, 4 trains; 1500 V, 8 trains; and 1500 V, 16 trains. For standard bipolar iEGMs (30 Hz – 500 Hz) the reduction in peak-to-peak amplitude after PFA was considered as a measure of the effect. In addition, unipolar iEGMs (0.5 Hz – 500 Hz) were decomposed into non-overlapping frequency sub-bands with Daubechies order 6 discrete wavelet transform (Figure 1A) allowing separate analysis in high-frequency (HF) and low-frequency (LF) ranges (63 Hz – 500 Hz and 0.5 Hz – 8 Hz, respectively). Results In total, 30 standard bipolar and 35 unipolar iEGMs (with at least 3.5 minutes of artefact-free post-ablation duration) were analysed. No dose dependency was observed for standard bipolar iEGMs within 5 minutes post-ablation (data not shown). However, the HF and LF content of unipolar iEGMs revealed opposing effects: a decrease in the HF and an increase in the LF content. Correlation with the dose was clearer in the LF content 3.5 minutes post-ablation, the difference being significant (p<0.05) between the lowest and the highest doses (Figure 1B and C). Discussion The decrease in HF content could reflect electrical silencing, ie. stunning of locally affected cardiomyocytes, most likely caused by irreversibly electroporated (ablated) cells located close to the catheter tip and by reversibly electroporated or otherwise temporarily silenced cells in adjacent tissue. The increase in LF content could reflect the current-of-injury effect, which is a broader area phenomenon derived from electrical potential differences between affected (reversibly and irreversibly electroporated) and non-affected regions. Conclusion Unipolar iEGMs acquired with a broadened frequency range and decomposed into HF and LF content provide new insight into the effects of PFA and correlate with PFA dosing in this pre-clinical porcine model.

Numerical analysis of electrothermoconvection of a dielectric nanofluid in a heated cavity

A numerical analysis of electrohydrodynamic (EHD) flow and heat transfer of nanofluid in a heated rectangular cavity is presented. A two-dimensional (2D) rectangular cavity heated from the bottom is considered. An electric potential difference is applied vertically, with the bottom wall acting as a high-voltage electrode, and the top wall is grounded. TiO2-25 # transformer oil nanofluid with nanoparticle volume fraction ranging from 0–5% is considered. The numerical model for EHD flow and heat transfer of nanofluid is implemented in the finite-volume method (FVM) based numerical framework of OpenFOAM. A single-phase approach based on the effective properties is adopted to model the nanofluids. A two-way coupled EHD flow model is employed to consider mutual interactions of flow and electric field variables. The flow and heat transfer behavior of nanofluids in the presence of an electric field is quantified with reference to the key parameters, electric Rayleigh number (T), and the nanoparticle volume fraction ϕ. The addition of nanoparticles increased the viscosity and marginally reduced the natural convective flow and heat transfer. However, EHD flow induced by the electric field aided in overcoming the weak natural convection flow in nanofluids. Results confirm that nanofluids’ net effective heat transfer rates are notably increased in the presence of the electric field. For the parameters under consideration, combining electric fields with nanofluids led to a significant heat transfer enhancement of up to 32.3%. The present study showcases the feasibility of combining passive heat transfer enhancement using nanoparticles and active heat transfer enhancement using EHD flow.

Influence of the Dielectric Constant on the Ionic Current Rectification of Bipolar Nanopores.

In this paper, we investigate how the dielectric constant, ϵ, of an electrolyte solvent influences the current rectification characteristics of bipolar nanopores. It is well recognized that bipolar nanopores with two oppositely charged regions rectify current when exposed to an alternating electric potential difference. Here, we consider dilute electrolytes with NaCl only and with a mixture of NaCl and charged nanoparticles. These systems are studied using two levels of description, all-atom explicit water molecular dynamics (MD) simulations and coarse-grained implicit solvent MD simulations. The charge density and electric potential profiles and current-voltage relationship predicted by the implicit solvent simulations with ϵ = 11.3 show good agreement with the predictions from the explicit water simulations. Under nonequilibrium conditions, the predictions of the implicit solvent simulations with a dielectric constant closer to the one of bulk water are significantly different from the predictions obtained with the explicit water model. These findings are closely aligned with experimental data on the dielectric constant of water when confined to nanometric spaces, which suggests that ϵ decreases significantly compared to its value in the bulk. Moreover, the largest electric current rectification is observed in systems containing nanoparticles when ϵ = 78.8. Using enhanced sampling, we have shown that this larger rectification arises from the presence of a significantly deeper minimum in the free energy of the system with a larger ϵ, and when a negative voltage bias is applied. Since implicit solvent models and mean-field continuum theories are often used to design Janus membranes based on bipolar nanopores, this work highlights the importance of properly accounting for the effects of confinement on the dielectric constant of the electrolyte solvent. The results presented here indicate that the dielectric constant in implicit solvent simulations may be used as an adjustable parameter to approximately account for the effects of nanometric confinement on aqueous electrolyte solvents.

Electrode Spacing Effects on the Capacitance of Glassy Carbon Electrodes in Aqueous Electrolytes

Matched glassy carbon electrodes in aqueous K2SO4 electrolytes were used to examine the effects of opposing electrode spacing on capacitive performance. Planar non-porous glassy carbon electrodes were used to avoid complications with porosity and roughness. Electrode spacing effects were examined in terms of device and individual electrode performance, using cyclic voltammetry, coupled with its deconvolution into residual, diffusional, and capacitive processes. Decreasing the spacing between electrodes led to a decrease in capacitive contributions, and a relative increase in diffusional and residual contributions, implying that individual electrodes were influencing the behaviour of each other. This is also consistent with the use of more dilute electrolytes. Electrode behaviour was modelled using the Poisson-Boltzmann equation, together with its integrated outputs of electric field and potential difference. For electrodes with the same amount of charge and a similar diffuse layer thickness, the electric field and potential drop was diminished because of their charge interaction. Conversely, it is shown that for a similar potential drop across the electrodes, the variable controlled in a cyclic voltammetry experiment, more charge accumulation is needed at the electrode-electrolyte interface to compensate for the counter charge generate from the opposing electrode.

Magnetic field based finite element method for magneto-static problems with discontinuous electric potential distributions

We introduce two finite element formulations to approximate magneto-static problems with discontinuous electric potential based respectively on the electrical scalar potential and the magnetic field. This work is motivated by our interest in Liquid Metal Batteries (LMBs), a promising technology for storing intermittent renewable sources of energy in large scale energy storage devices. LMBs consist of three liquid layers stably stratified and immiscible, with a light liquid metal on top (negative electrode), a molten salt in the middle (electrolyte) and a heavier liquid metal on bottom (positive electrode). Energy is stored in electrical potential differences that can be modeled as jumps at each electrode-electrolyte interface. This paper focuses on introducing new finite element methods for computing current and potential distributions, which account for internal voltage jumps in liquid metal batteries. Two different formulations that use as primary unknowns the electrical potential and magnetic field, respectively, are presented. We validate them using various manufactured test cases, and discuss their applications for simulating the current distribution during the discharge phase in a liquid metal battery.

Effect of hydrostatic pressure on the anodic dissolution process of X80 steel

Based on the fact that hydrostatic pressure affects chemical potentials of reaction species and the structure evolution of electric double layer (EDL), the authors propose a generalized-BV equation to analyze the anodic dissolution process of X80 steel in deep-sea environment. Combined with the results of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests, the following conclusions can be drawn: hydrostatic pressure can compress the electric double layer non-uniformly. The CHCD (CD: capacitance of diffused layer; CH: capacitance of compact layer) value increases first and then decreases with increasing hydrostatic pressure and reaches its maximum at 15 MPa, which is sure to influence the difference in electrical potential that drives chemical reaction at interface. Ultimately, the anodic dissolution current increases and then decreases with rising hydrostatic pressure at the same anodic polarized potential. Besides, low hydrostatic pressure may contribute to forming a dense corrosion product film and inducing a good inhibiting effect on further dissolution of X80 steel; However, when the hydrostatic pressure exceeds the critical value of 20Mpa, too high anodic dissolution rate along with promoted Cl− adsorption will deteriorate the protection performance of corrosion product film, and exacerbate local corrosion process.

Investigation of leachate infiltration on groundwater using georesistivity and natural electric field method around Ojoou-Olayanju’s dumpsite, Ada, southwestern Nigeria

The investigation of groundwater within the dumpsite environment is highly important in geophysical study. This is because the extent of interaction between the aquiferous medium and the contaminated zone could pose a serious threat to the end users especially humans when consumed. This research aimed at investigating leachate infiltration and its potential influence on groundwater at Ojoou Olayanju's Dumpsite using combining geo-resistivity and natural electric field (NEF) methods. In this study, five dipole-dipole and five NEF measurements were obtained using the Omega resistivity meters and PQWT-150 equipment respectively. The dipole-dipole method was deployed to obtain a 2D near-surface pseudo-section, and the NEF method was used to obtain the frequency curve and profile maps of electric potential difference. The dipoledipole results revealed the lateral variation in the resistivity along the traverses, suggesting that the materials within this near-surface are heterogeneous, and the closely spaced contours' varying gradients indicate fracture, which would facilitate potential leachate filtration. The NEF results revealed curves, and a subsurface image with respect to depth and profile distance. The points of convergence signals on the frequency model correspond to a medium with low resistivity on the profile map. The conductive medium is seen as being saturated with leachate, which suggests that very large portion of the study area around the dumpsite has been contaminated by leachate. Conclusively, it was revealed that leachate filtration is evidence especially at the topsoil and due to the presence of fractured zones, the groundwater quality is at risk of contamination by continuous filtration of leachate