Electric Potential Research Articles

Comprehensive device modeling for AlGaN/GaN based Schottky barrier diodes with beveled p-GaN termination to control electric field

In this article, we have systematically investigated the impact of different structural parameters on the electrical characteristics for AlGaN/GaN based Schottky barrier diodes (SBDs) with beveled p-GaN termination by using TCAD simulation tools. The p-GaN termination can decrease the electric field at the Schottky contact region, thereby suppressing the electrical field magnitude in the Schottky contact region. Then, the breakdown voltage can be enhanced without remarkably sacrificing the forward conduction characteristics. However, in spite of the reduced electric field magnitude in the Schottky contact region, the electric field will possess the peak value at the edge of p-GaN termination. Therefore, the premature breakdown can occur when the electric field therein reaches critical value. Hence, we have comprehensively manipulated the electric field distributions by designing different p-GaN terminations and detailed optimization strategy for the AlGaN/GaN based Schottky barrier diodes has been conducted. Moreover, we find that the strong electric field at the p-GaN termination edge can be reduced by using beveled p-GaN termination, which can extend the electric potential into the bulk GaN region. With the developed defected-related physical models, we also find that the p-GaN termination suppress the capture and release process for the carriers by defects, which improves the dynamic characteristics for the proposed devices.

Tracking Minority Species in Redox Reactions: A Quantitative Combined XAS and Modulation Excitation Study

AbstractUnderstanding the nature of intermediates/active species in reactions is a major challenge in chemistry. This is because spectator species typically dominate the experimentally derived data and consequently active phase contributions are masked. Transient methods offer a means to bypass this difficulty. In particular, modulation excitation with phase‐sensitive detection (ME‐PSD) provides a mechanism to distinguish between spectator and reacting species. Herein, modulation excitation (ME) time‐resolved (energy dispersive) X‐ray absorption spectroscopy, assisted by phase sensitive detection (PSD) analysis, has been applied to the study of a liquid phase process; in this case the classic ferrocyanide/ferricyanide redox couple. Periodic switches of the electrical potential (anodic/cathodic) enabled the use of the ME approach. Structural changes at fractions as low as 2 % of the total number of electroactive species were detected within the X‐ray beam probe volume containing ~30 pmol of Fe(II)/Fe(III).

The effect of titanium surface treatment by application of constant potential or current on the viability of pre-osteoblast cells: an in-vitro study.

The aim of this study was to investigate the impact of electrochemical treatment of a titanium surface employing constant current and potential on the viability of the tissue cells attached to the surface and determining the safety limits for this type of treatment. Pre-osteoblast cells (pOB) were cultured and seeded onto titanium discs. The cell-seeded discs were then exposed to a range of contant direct electrical potentials (-6V-6V) or contant direct electrical currents (-12.5mA, -25mA, or -50mA) using a three-electrode system connected to a potentiostat. Cell viability was assessed using live/dead assay and fluorescence microscopy. Exposure of cells to high negative potentials caused cell detachment, while exposure to positive ones led to cell death on the cpTi surfaces. However, cellular viability was preserved when the electrical potentials were kept between -3 and +3V. Cells retained 80% viability when subjected to -12.5mA currents with an initial pOB cell count of 5 × 104. However, when the initial cell count was elevated to 1 × 105, the cells demonstrated the ability to withstand an even greater current (-25mA) while preserving their vitality at the same level. Treatment of a titanium dental implant surface employing constant potential or current can harm cells surrounding dental implants. However, this damage can be minimized by keeping the potential within a safety limit.

Assessment of merits and demerits of perpendicular and slanted photovoltaic/thermal facades

This study compares the thermal and electrical energy production potential and wind load assessment of perpendicular versus slanted photovoltaic (PV) facades. The goal is to identify the optimal facade orientation for societal adoption based on energy efficiency and wind load considerations. Using Hybrid RANS/LES models, the aerodynamic performance and energy yield of both orientations are analyzed under varying angles and environmental conditions. The findings show that while the slanted façade is better designed to capture solar irradiance, it produces 4 to 8 % less energy than the perpendicular façade and yields approximately 2 % less exergy efficiency due to wind regime. However, the slanted design reduces wind load by 9.8 %, enhancing structural stability. The maximum thermal energy output of 217 kW is recorded from the perpendicular façade at a wind speed of 1 m/s, while the slanted façade generates a peak electrical power of 68 kW at 8 m/s wind speed. Overall, the perpendicular façade underscores more efficient in equal weather conditions, making it a sustainable choice for PV installation. These results provide valuable insights for architects, engineers, and policymakers in optimizing PV facade design for urban environments.

Resolving the Size and Charge of Small Particles: A Predictive Model of Nanopore Mechanics.

The movement of small particles and molecules through nanopore membranes is widespread and has far-reaching implications. Consequently, the development of mathematical models is essential for understanding these processes on a micro level, leading to deeper insights. In this endeavor, we suggested a model based on a set of empirical equations to predict the transport of substances through a solid-state nanopore and the associated signals generated during their translocation. This model establishes analytical relationships between the ionic current and electrical double-layer potential observed during analyte translocation and their size, charge, and mobility in an electrolyte solution. This framework allows for rapid interpretation and prediction of the nanopore system's behavior and provides a means for quantitatively determining the physical properties of molecular analytes. To illustrate the analytical capability of this model, ceria nanoparticles were investigated while undergoing oxidation or reduction within an original nanopore device. The results obtained were found to be in good agreement with predictions from physicochemical methods. This developed approach and model possess transferable utility to various porous materials, thereby expediting research efforts in membrane characterization and the advancement of nano- and ultrafiltration or electrodialysis technologies.

Investigating the optical bistability of pure spheroidal nanoinclusions in passive and active host matrices

The study examined the effects of the depolarization factor (L) and the real and imaginary parts of the dielectric function of the host matrix (εh ) on the local field enhancement factor and optical bistability of pure spheroidal nanoinclusions with both passive and active host matrices. By solving the Laplace equation in the quasi-static limit, we derived expressions for the electric potentials of the pure spheroidal nanoinclusions. We then incorporated L and the Lorentz-Drude model into these expressions to derive the equation for the enhancement factor in the core of the spheroidal nanoinclusions. The results show that, regardless of whether L varies or remains constant, the pure spheroidal nanoinclusions exhibit only one set of enhancement factor peaks, independent of whether the host matrix is passive or active. However, for the same increase in ε h , the enhancement factor intensities of the pure metal spheroidal nanoinclusions are higher when the host matrix is active compared to when it is passive. The number and intensities of the enhancement factor peaks, as well as the optical bistability of the pure spheroidal nanoinclusions, vary significantly depending on whether the core is made of a passive or active dielectric material. Furthermore, by adjusting parameters such as L and the real and imaginary parts of the host matrices, we were able to achieve tunable enhancement factors and optical bistability, which could be useful for applications in optical sensing, nonlinear optics, and quantum optics.

Electroosmotic peristaltic transport of magnetohydrodynamic Casson nanofluid in a non-uniform wavy porous asymmetric micro-channel

Magnetohydrodynamics (MHD) have numerous engineering and biomedical applications such as sensors, MHD pumps, magnetic medications, MRI, cancer therapy, astronomy, cosmology, earthquakes, and cardiovascular devices. In view of these applications and current developments, we investigate the magnetohydrodynamic MHD electro-osmotic flow of Casson nanofluid during peristaltic movement in a non-uniform porous asymmetric channel. The effect of thermal radiation, heat source, and Hall current on the Casson fluid peristaltic pumping in a porous medium is taken into consideration. The effect of chemical reactions is also considered. The mass, momentum, energy, and concentration equations were constructed using the proper transformations and dimensionless variables to make them easier for non-Newtonian fluids. A lubricating strategy is used to make the system less complicated. The Boltzmann distribution of electric potential over an electric double layer is studied using the Debye–Huckel approximation. The temperature and concentration equations are addressed using the homotopy perturbation method (HPM), while the exact solution is determined for the velocity field. The study examines the performance of velocity, pressure rise, temperature, concentration, streamlines, Nusselt, and Sherwood numbers for the involved parameters using graphical illustrations and tables. Asymmetric channels exhibit varying behavior, with velocity declining near the left wall and accelerating towards the right wall while enhancing the Casson fluid parameter. The pumping rate boosts in the retrograde region due to the evolution of the permeability parameter value, while it declines in the augment region. The temperature profile optimizes as the value of the heat source parameter gets higher. The concentration profile significantly falls as the chemical reaction parameter rises. The size of the trapped bolus strengthens with a spike in the parameter for the Casson fluid.

Exploration of vanoxerine analogues as antibacterial agents.

Mycobacterium tuberculosis is a bacterial pathogen, responsible for approximately 1.3 million deaths in 2022 through tuberculosis infections. The complex treatment regimen required to treat tuberculosis and growing rates of drug resistance, necessitates the development of new anti-mycobacterial agents. One approach is to repurpose drugs from other clinical applications. Vanoxerine (GBR 12909) was previously shown to have anti-mycobacterial activity, through dissipating the membrane electric potential and hence, cellular energetics. Several vanoxerine analogues were synthesised in this study, which exhibited a range of activities against mycobacteria and enterococcus. All active analogues had similar impacts on the membrane electric potential and inhibition of ethidium bromide efflux. The most active compound displayed reduced inhibitory activity against the known human target of vanoxerine, the dopamine transporter. This work has identified a promising analogue, which could provide a starting point for further medicinal chemistry and drug development efforts to target mycobacteria.

Electromagnetic Model of K‐Changes

AbstractK‐changes are observed as step‐like increases in the thundercloud electric fields. The K‐changes occur in the late part of intra‐cloud lightning or during negative cloud‐to‐ground lightning between return strokes. It has been shown that the processes leading to K‐changes initiate in the decayed part of a positive leader channel and propagate toward the flash origin. They are often accompanied by microsecond‐scale electric field pulses. We introduce a new model to simulate processes leading to the K‐changes in cloud‐to‐ground lightning. Our method is based on the full solution of Maxwell's equations coupled to Poisson's equation for the thundercloud charge structure. To model the K‐changes, we gradually increase the decayed channel conductivity. The modeled current wavefront propagates due to the K‐processes downward along a vertical channel and completely attenuates before reaching the ground. We derive the evolution of the linear charge densities and the scalar electric potential along the channel leading to K‐changes. We model electrostatic step‐like changes in the measured electric field together with the approximate rates and amplitudes of the microsecond scale pulses. Step‐like changes increase their amplitudes with the length of the simulated channel and with a higher conductivity of the channel. The microsecond‐scale pulse waveshapes depend mainly on the propagation velocity of the current wave, and the time scale of the conductivity increase. We show that our modeled waveforms are in a good agreement with observations conducted in Florida.

Development of three-dimensional forward modeling method for the magnetometric resistivity (MMR) method

We have developed a 3-D forward modeling method for the magnetometric resistivity (MMR) technique, specially focusing on the marine MMR method, which utilizes a vertical bipole source and seafloor receivers to measure magnetic field variations. The bipole source generates an artificial electric current between two electrodes: one on the sea surface and another on the seafloor. When computing the electric potential using the relaxation method, while conserving electric current, singularities arise at the electrode locations. To address this issue, we introduce two electrical resistivity structures to mitigate the effects of these singularities and to obtain magnetic field anomalies caused by arbitrary 3-D electrical resistivity anomalies beneath the seafloor. By determining the sign of the magnetic field anomaly, we can infer whether the electrical resistivity of the anomalous body is more conductive or more resistive compared to the surrounding oceanic crust. Furthermore, we demonstrate that increasing the number of bipole sources is more effective in exploring anomalous bodies than increasing the number of receivers.Graphical abstract

Nonlinear forced vibration of the FGM piezoelectric microbeam with flexoelectric effect

In this paper, based on the extended dielectric theory, Euler beams theory and von Karman’s geometric nonlinearity, a nonlinear FGM piezoelectric microbeam model is established with flexoelectric effect. The governing equations, initial conditions and boundary conditions are obtained by applying Hamilton’s principle and then solved by combining the differential quadrature method (DQM) and iteration method. The innovation of this paper is to construct a nonlinear forced vibration model of piezoelectric microbeams. The coupling response between the inverse flexoelectric effect and the inverse piezoelectric effect is investigated. Various effects are examined, including the functional gradient index m and transverse distributed load q affecting the distribution of electric potential. Results indicated that the functional gradient index m, beam thickness h, and span-length ratio L/h have a significant impact on the dimensionless deflection of the FGM microbeam. The influence of the flexoelectric effect on dimensionless deflection increases with the decrease of scale. In addition, transverse load q and the functional gradient index m also have a significant impact on the distribution of electric potential. This paper will provide useful theoretical guidance for the design of micro-sensors and micro-actuators.

The future of clean energy: Agricultural residues as a bioethanol source and its ecological impacts in Africa

This study presents a comprehensive analysis of Africa's potential to produce bioethanol from agricultural residues and its environmental impact. The relentless consumption of fossil fuels and associated environmental challenges necessitate a shift toward sustainable energy sources, with bioethanol emerging as a promising alternative. This study evaluates the capacity for bioethanol generation from agricultural residues in Africa, considering its land, water, and carbon footprints. Based on data from 85 primary agricultural residues across Africa, approximately 102.256 Gt of fresh agricultural residue is estimated to be available in Africa, translating to approximately 62.117 Gt of dry-weight material. This significant capacity indicates a substantial potential for bioethanol production in Africa, corresponding to a net output of 207.127 EJ. The coproduction potential of bioethanol and electricity are also highlighted, with electricity accounting for 8.016 % of the total net bioethanol energy production. However, the environmental impact of bioethanol production varies across African nations, suggesting the need for optimization and sustainable practices. Additionally, the study discusses the challenges encountered in the bioethanol sector, including the sustainability of production, emission reduction, technological and financial constraints, and the broader context of biomass usage. In conclusion, although bioethanol production from agricultural residues is a promising alternative for Africa's energy sector, it should be realized only after a multifaceted assessment involving technological, economic, policy, and environmental considerations.

Magnetoelectric nanodiscs enable wireless transgene-free neuromodulation.

Deep brain stimulation with implanted electrodes has transformed neuroscience studies and treatment of neurological and psychiatric conditions. Discovering less invasive alternatives to deep brain stimulation could expand its clinical and research applications. Nanomaterial-mediated transduction of magnetic fields into electric potentials has been explored as a means for remote neuromodulation. Here we synthesize magnetoelectric nanodiscs (MENDs) with a core-double-shell Fe3O4-CoFe2O4-BaTiO3 architecture (250 nm diameter and 50 nm thickness) with efficient magnetoelectric coupling. We find robust responses to magnetic field stimulation in neurons decorated with MENDs at a density of 1 µg mm-2 despite individual-particle potentials below the neuronal excitation threshold. We propose a model for repetitive subthreshold depolarization that, combined with cable theory, supports our observations in vitro and informs magnetoelectric stimulation in vivo. Injected into the ventral tegmental area or the subthalamic nucleus of genetically intact mice at concentrations of 1 mg ml-1, MENDs enable remote control of reward or motor behaviours, respectively. These findings set the stage for mechanistic optimization of magnetoelectric neuromodulation towards applications in neuroscience research.

Electro-magneto-mechanical critical load analysis of piezoelectric/piezomagnetic sport force plates used for testing athlete performance

Electro-magneto-thermo-mechanical critical loads of a sandwich microplate composed of a core integrated with piezoelectric/piezomagnetic face-sheets are analyzed in this paper based on higher order shear and normal deformation theory and modified couple stress theory. The constitutive relations are developed based on generalized Hooke’s law and electromagnetic relations. In order to measure athletic performance and his/her quantitatively or qualitatively grades, a force plate is used. The thickness stretching of the sport force plates is accounted based on a new function in displacement field. The electric and magnetic potentials are assumed as summation of a linear function including applied electric/magnetic potential and two functions for satisfying the zero condition at top and bottom of the sport force plates.

Plasmonic coupling effect of annealed gold nanoarrays

Periodic metal nanodisc arrays have the potential to exhibit regularly spaced large local field enhancements, especially when high-Q collective plasmonic grating resonances can be obtained. Here we demonstrate how Laser interference lithography (LIL) as a maskless and high throughput technique can be used to fabricate these on square centimeter areas. The drawback of LIL is the rather fixed ratio of the size of the individual nanostructure (d) to the period of the array (p) of about d/p ∼ 0.5 for the setup used in the current article, thereby, limiting its ability to create resonances with ultra-high quality factors (Q-factors). To improve the Q-factor of the resonances of the arrays, we study the effect of thermal annealing nanodisk arrays fabricated by LIL and a lift off process. The nanodisk arrays with periods of 400 nm and 500 nm exhibited a plasmonic resonance, which was caused by the interaction of the single disk resonance and a (1 0) grating resonance. Annealing for a short duration lowered the d/p ratio from 0.5 to 0.4, and led to smoothening of the disk surfaces and growth of gold grains, resulting in lower ohmic and radiative losses and doubling of the Q-factor of the resonances. Finite element method (FEM) simulations were used to monitor this improvement in material parameters. Annealing for a longer duration disintegrated the nanodisk into several smaller particles while maintaining the overall periodicity of the array. While the plasmonic resonances of the experimentally investigated fragmented disks were basically destroyed, simulation predict that for larger periods fragmented nanodisk arrays (keeping the d/p ∼ 0.4) can exhibit extremely strong and sharp resonances whose Q-factor increases more than 58.4 times compared to the unfragmented discs. In addition, simulations show a massive enhancement of the local electric field promising immense potential for surface enhanced Raman sensing.

Long range self-transport of liquid droplets driven by electric field and roughness gradient

It is well known that roughness and charge gradients could be used for droplet self-transport. The key issue is how to synergize the two effects. The uniform density charge can form linearly increasing charge gradient on a roughness gradient surface. Under this condition, the influence on the droplet self-transport under the synergy of these two effects was obtained by statics analysis, and the driving function was presented. An energy equation was constructed to study the conditions for crossing periodic boundaries, and the problem of distance limitation on periodic surfaces due to energy dissipation was solved by converting electric potential into droplet kinetic energy. A periodic roughness gradient surface with K = 0.07 was designed and prepared via 3D printing. Water droplets can be transported over long distances and the maximum velocity increases with charge density up to 46 mm/s. Finally, the effect of different structures on the maximum charge density in the Cassie state was investigated by simulation. The biomimetic structures exhibit great compressive stability, which can increase the surface charge density of droplets in the Cassie state by 3.6 times compared to pillar structures. It can be widely used in the fields of materials science and interface chemistry, etc.

Mitochondrial dysfunction in patients with respiratory diseases

The aim of this scientific literature review was to find new solutions to urgent problems of treating respiratory diseases and reducing the associated temporary loss of ability to work and disability. The article presents the results of the analysis of 62 scientific papers published over 23 years (2001 – 2023) on mitochondrial dysfunction (MD), new methods of its diagnosis, and ways of its correction in respiratory diseases. Disorder of the energy function of mitochondria has been identified as an urgent scientific problem of respiratory medicine. It is noted that new methods of pathogenetic therapy for common and currently difficult-to-treat diseases are being developed to solve this problem. The key section of the review is devoted to the results of studies of mitochondrial dysfunction in patients with asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, and pulmonary hypertension.Conclusion. The article assesses MD diagnostic methods that are potentially applicable in real clinical practice. The results of studying the electric potential of the inner mitochondrial membrane, accumulation of active forms of oxygen, production of adenosine triphosphate in blood cells, alveocytes and epithelium of the respiratory tract, as well as bronchial smooth muscle cells, endothelium and vascular smooth muscle cells in the pulmonary artery system, determination of mitochondrial DNA in biological environments are compared. Proposed methods for the correction of MD syndrome in the clinical picture of respiratory diseases are briefly covered.

Effects of Functionalized Carbon Nanotube on Cellular Homeostasis of Murine Hepatocytes

Nanotechnology in medicine represents a revolution offering significant advancements in the diagnosis, treatment, and prevention of diseases. This technology enables the development of devices and materials at the nanometer scale, allowing precise interactions with biological systems at the molecular and cellular levels. Among various nanomaterials, carbon nanotubes (CNTs) stand out due to their unique physical, chemical and mechanical properties. Due to their high strength, electrical and thermal conductivity and large surface area, CNTs have a wide range of applications. In healthcare they are explored for drug delivery and imaging diagnostics. CNTs can be functionalized to target drugs directly to diseased cells, minimizing side effects and enhancing treatment efficacy, additionally can be used in biosensors for early disease detection and in tissue engineering to cellular regeneration. The present study evaluated the effects of OCNT-TEPA, a multi-walled carbon nanotube functionalized, in murine hepatocytes AML-12. Cells were exposed to different concentrations of the sample for 12, 24, 48, and 72 hours. Cellular metabolism tests, cellular morphology by optical microscopy, synthesis of reactive oxygen species, changes in membrane potential and IL-6 cytokine secretion were performed. The results show that OCNT-TEPA altered the homeostasis of hepatocytes, as cellular metabolism decreased, cellular morphology was altered, the membrane experienced changes in its electrical potential, oxidative stress increased and inflammatory signaling molecules were synthesized. This alteration is dose-dependent, which may be harmful to hepatocytes at high concentrations but could be applied to the body at lower concentrations without causing harm.

Application of G-Ori metamaterials as sports equipment baseball bat in an electro-magneto-elastic sandwich composite beam

In this work, a higher order thickness stretched model is employed for electro-magneto-elastic results of a shear deformable baseball bat as a sandwich beam. The formulation is performed using the two dimensional constitutive relations as well as electric potential and magnetic induction relations for a shear deformable baseball bat. The proposed model can be used as a baseball bat in sport equipment. The principle of virtual work is employed to derive governing equations in the presence of thermal, electrical and magnetic loads. The physical model is a sandwich baseball bat beam composed of graphene origami reinforced copper matric core integrated with two piezoelectric/piezomagnetic face-sheets in thermal environment excited by electric and magnetic potentials.

Impact of Dual Functionalities of Mo‐Doped BiFeO3 Decorated with Bi4MoO9 Heteroatoms for Piezo‐Photocatalytic Activity

AbstractPiezocatalysts have shown great promise for effcient hydrogen generation. However, their application is limited by the rapid charge recombination and sluggish charge transfer rate of piezo‐induced charge carriers. This work aims to address the preceding limitations by controlled synthesis of a representative piezocatalyst, BiFeO3 doped with Mo atoms and decorated with Bi4MoO9 (BMO) heteroatoms using sol‐gel method. The substitutional doping of Mo on BFO (BFMO) was shown to induce a shallow energy level near the conduction band that acted as a trapping state, to suppress recombination of charge carriers, enhance charge mobility for transport to the surface, modulate band alignment, and lower the energy barrier for surface reaction. The formation of BFMO/BMO heterostructures induced electrical band bending, leading to the electric potential gradient, hence promoting charge carrier separation and transfer. The BFMO/BMO with 0.5 mol % Mo (Mo‐5) demonstrated four times faster piezocatalytic Rhodamine B (RhB) dye degradation rate (k of 0.032 min−1) compared to pristine BFO (0.009 min−1). Further, the Mo‐5 exhibited a 45% higher piezocatalytic H2 production rate (14.4 µmol/g/h) compared to pristine BFO (9.8 µmol/g/h) while being cocatalyst‐free. Coupling piezocatalysis with photocatalysis was found to reduceperformance relative to the individual processes, which is attributed to Auger recombination which impedes any potential synergistic effect.