Electric Current Research Articles

Influence of the use of ground enhancement materials on the reduction of electrical resistivity in grounding systems: a review

A grounding system (GS) is an indispensable component in an electrical system network, as it is responsible for conducting electrical discharges to the ground due to faults caused by lightning strikes or transient system failures. Globally, it is estimated that 40 lightning strikes occur per second on the planet, amounting to around 1.2 billion per year, resulting in daily losses of various electrical equipment and human fatalities ranging from 6,000 to 24,000. Additionally, soil resistivity, which impedes the flow of electricity from electrical discharges into the ground, leads to inadequate mitigation of electrical overload effects, resulting in poor GS performance. Consequently, the implementation of ground enhancement materials (GEMs) to reduce impedance to optimal levels becomes necessary. The objective of this review is to broadly examine the current status of GEMs reported in the literature for use in GS, focusing on their composition and their effectiveness in improving soil conductivity and dissipating electrical currents as well as to identify emerging trends and current challenges in the development and application of these materials, in order to provide information to guide future research in the design and implementation of efficient and safe GS.

Energy-loss process in Ni63 betavoltaic batteries

The betavoltaic effect is characterized by multiple random scatterings and high energy density exchange. The conversion of beta-particles’ energy to electric current is a sophisticated process. A GEANT4-based code is used to model the energy-loss mechanisms of emitted electrons from 63Ni radioisotope, considering the physics behind these losses (such as Coulomb scattering, nuclear stopping, and Bethe-Bloch theory) while taking into account self-absorption and backscattering factors. The study indicates the existence of a significant non-ionizing energy-loss of penetrating beta-particles that may stimulate remarkable local heating in the absorbing structure, which results in a degradation in the performance of betavoltaic batteries using 63Ni as nuclear fuel

Progress on Polyolefin/Graphene Nanocomposites with High Dielectric Constant and Low Dielectric Loss for Electrical Applications

Introduction: The attached oxygen functional group in graphene oxide (GO) with layers that are about 1.1 ± 0.2 nm thick, has hindered the performance of electrical characteristics. Diminution of the oxygen functional group, and increasing the carbon/oxygen (C/O) ratio can enhance electrical conductivity. Method: This study investigated the effect of graphene derivatives (C/O) ratios on the dielectric properties of low-density polyethylene (PE) made of metallocene, as well as polypropylene (PP) and mixtures of them. The oxygen functional groups were reduced by utilizing graphene oxide (GO) and reduced graphene oxide (rGO). The effect of GO and rGO-based polyolefin produced by solution blending while lowering the oxygen functional group is explored. Result: The surface morphology and chemical structure were examined by using a scanning electron microscope (SEM) and Fourier Transformed Infrared Spectroscopy (FTIR). The electrical characteristics of the composite films, such as their loss factor (tan δ) and dielectric constant, permittivity and conductivity, and imaginary permittivity were examined. At room temperature, measurements were performed at frequencies ranging from 300 Hz to 8 MHz. ε'; the dielectric permittivity and imaginary permittivity (ε") of polymer/ reduced graphene oxidehowever, these values rapidly decreased with increasing Conclusion: The alternating current conductivity of the composites was likewise shown to increase with increasing frequency.

A wideband circularly polarized filtering dielectric resonator antenna array based on magneto-electric currents combination

ABSTRACT A circularly polarized (CP) filtering dielectric resonator antenna (DRA) array is proposed based on the magneto-electric currents combination (MECC) method in this paper. The array consists of four rectangular DRAs, four hook-shaped electric dipoles (HSED), and two layers of substrate integrated waveguide (SIW) cavities. The electric current (EC) on the HSED is excited by the slot aperture of the SIW cavity, and the equivalent magnetic current (MC) is simultaneously generated with HSED in the DRA. Based on the surface current regulation, the EC and MC are adjusted to achieve appropriate amplitudes and phases, thereby realizing wideband CP radiation. The filtering function is realized with the high-pass characteristics of the SIW and the effective suppression of the higher-order modes in the resonance cavity. Due to the presence of an air gap between the DRAs and HSED, the higher modes of the DRA are designed for bandwidth enhancement. The prototype of the DRA array has been fabricated and measured, exhibiting a relative bandwidth of 26.1% and an axial ratio bandwidth of 17.77%, with radiation nulls present at either side of the passband. With the advantages of wide bandwidth and high gain, the proposed DRA array can be applied to satellite communications.

Restoring Plasticity in Nickel‐Based Superalloy Using High‐Density Pulsed Electric Current

This study explores the efficacy of high‐density pulsed electric current (HDPEC) in healing plastic deformation damage in single‐crystal Ni‐based superalloys. Single‐crystal specimens are prepared from directionally solidified nickel‐based superalloy to assess the potential of electric current treatment in restoring plastic deformation capability. Experiments involving various current densities and pulse durations reveal that a pulsed electric current of 17 ms at 400 A mm−2 yields optimal results, enhancing fracture elongation from 7.8% to 12.3% without compromising strength. The study conducts a comprehensive analysis of microstructural changes induced by pulsed electric current, employing quasi‐in‐situ electron backscatter diffraction and transmission electron microscopy techniques. The results demonstrate that HDPEC disrupts the planar dislocation network, homogenizes dislocation distribution, and promotes dislocation entanglement. Consequently, microdefects in the alloy are eliminated, restoring the material's ductility. The findings suggest that this technology holds significant promise for repairing fatigued components and underscore the potential for further research in this domain.

KARAKTERISASI KEKUATAN GESER DAN STRUKTUR MIKRO HASIL SPOT WELDING PELAT BAJA KARBON RENDAH

Spot welding is a joining method that utilizes thermal energy generated by the resistance of electric current. Research was conducted to determine the effect of plate thickness, current and welding time on the characteristics of spot welding results. Spot welding was performed on low carbon steel plates of 0.8 mm, 1.5 mm and 1.8 mm thickness with current (50, 60, 70, 80 amperes) and welding time (10, 15, 20 seconds). Characterization of the spot welds was done by shear test (ASTM D1002-10) and observation of macro and micro structure (ASTM E3-11) and failure surface of the specimens. From the research conducted, it is known that the average shear strength increases with decreasing plate thickness, increasing welding current and decreasing welding time. The highest average shear strength of 502,772 N/mm2 was obtained with a plate thickness of 0.8 mm, a welding current of 70 A, and a welding time of 10 seconds. For thin plates, most of the shear test specimens failed in the area of the heat affected zone, while for thick plates, most of the shear test specimens failed in the area of the nugget spot weld.

Conduction system pacing in heart failure: Time for a paradigm shift?

Heart failure (HF) is a major clinical challenge characterized by significant morbidity and mortality. Electrical conduction abnormalities play a critical role in HF pathophysiology and progression, often leading to suboptimal outcomes with conventional pacing techniques. Con-duction system pacing (CSP), encompassing His bundle pacing and left bundle branch area pacing, has emerged as a novel approach. Despite data come from observational studies, recent guidelines recommend that a specific population may benefit from CSP. However, significant practical considerations and challenges need to be clarified before CSP can be routinely implemented in clinical practice. The reliance on observational studies means that long-term clinical outcomes for HF patients remain uncertain until data from randomized controlled trials (RCTs) become available. Current CSP practices face challenges with lead implantation, mechanical stress on leads, and the need for more advanced tools and artificial intelligence integration to improve procedure efficacy and safety. Future large-scale RCTs are essential to identify optimal candidates and address these technical challenges, potentially leading to a paradigm shift in HF management.

Thermally Induced Enhancement of Photoresponse in Radio Frequency‐Sputtered CdS Thin‐Film Photodetectors

This work focuses on understanding the defect‐related electronic transport in cadmium sulfide (CdS) thin films, and finds thermal treatment as an efficient tool to tailor its intrinsic defect charge carrier concentration for optimum visible‐light photodetection performance. The radio frequency (RF)‐sputtered CdS thin‐films show a substantial decrease in measured dark‐current by three orders of magnitude (μA to nA) with an increase in substrate deposition temperature (Ts) from room‐temperature (RT) to a maximum of 400 °C. With increase in Ts, the current conduction behavior changes from Ohmic (at RT) to Schottky‐behavior (Ts ≥ 100–400 °C). The decrease in dark‐current and the crossover from Ohmic to Schottky electronic transport behavior, pointed to a decrease in defect‐density charge carrier concentration, with increased Ts. Additionally, post‐deposition thermal annealing of CdS thin films also is found to result in a similar decrease in dark‐current (μA to nA). The photo‐to‐dark‐current ratio of CdS thin‐film visible‐light photodetectors increased by two‐orders of magnitude, and its dynamic response time decreased by an order of magnitude via. thermal engineering. The thermal‐annealing treatment possibly reduced the defect‐related trap‐sites, which enables a reliable and faster photo‐switching response for CdS thin‐film‐based visible‐light photodetectors.

Induction of Alkaline Bands in Chara by External Electric Current Reveals the Influence of Plasma Membrane H+ Fluxes on Cyclosis-Mediated Signaling

Long-distant communications in plants and giant plant cells are essential for optimal cell functioning under variable environmental conditions. In characean internodal cells exposed to spotted or flickering light, the redox balance in dimly lit chloroplasts is sensitive to the reducing power produced in brightly illuminated chloroplasts of a distal cell region located upstream in the directed cytoplasmic flow. The distant communication is mediated by excessive production in the high-light region of reducing metabolites that are exported into the streaming cytoplasm and delivered by cytoplasmic flow to light-starving chloroplasts. These target chloroplasts perceive the transportable metabolic signal, which is reflected in the transient increase of modulated chlorophyll fluorescence F '. Previous studies of cyclosis-mediated F ' transients revealed that they are sensitive to natural H+ fluxes across the plasma membrane and that the signal transduction is suppressed in cell areas with massive H+ influx. In this study with Chara australis R. Br., we show that the injection of inward electric current is accompanied by proton influx sufficient for the creation of artificial alkaline band. The combined application of PAM chlorophyll microfluorometry, local light stimuli, and measurements of pericellular pH showed that the microfluidic signal transduction is notably suppressed under artificially produced alkaline band where H+ influx acidifies the cytoplasm. It is hypothesized that changes in cytoplasmic pH regulate the rates of electron flows directed to NADP reduction and O2 reduction, which may disturb long-distance redox control system involving production and consumption of reducing equivalents.

Measurement of initial crystallization temperature of mold flux based on alternate current conductivity method

Measurement of initial crystallization temperature of mold flux based on alternate current conductivity method

Current-induced resonance in long conductive ferromagnetic nano-wires

Ferromagnetic nanowires are receiving attention as functional elements in technologically important applications in microwave devices, spintronics, and biomedicine. They can be readily fabricated over large areas using electrodeposition, and their magnetic response can be tuned through control of their size, geometry, and composition. Additionally, their geometrical properties provide a stable spin structure for manipulating magnetization dynamics using spin-polarized currents for spintronic applications. Structural analysis of individual cobalt nanowires indicated magnetocrystalline anisotropy predominantly perpendicular to the nanowire axis. This significantly alters the micromagnetic energy landscape in the nanowire and breaks the circular symmetry of the dynamic magnetization and resonance modes which is often assumed in theory. In this article, we investigate, using finite-element micromagnetic–electromagnetic simulations, the effect of the variation of magnetocrystalline anisotropy angle on the dynamic magnetization in the nanowire and leads to a shift in the resonance frequencies and modes. The resonance is induced by a pulsed electric current applied along the nanowire axis and simulations include the contributions of magnetocrystalline anisotropy, exchange, dipolar fields, and eddy currents. Understanding the magnetization dynamics induced by electric currents and spin-wave modes in metallic magnetic nanowires and their size and anisotropy angle dependence is important for the design and tuning of magnetic nanowire arrays and devices.

Efficacy of Invasive and Non-Invasive Methods in Orthodontic Tooth Movement Acceleration: A Systematic Review

Objective: The aim of this review was to evaluate the currently available scientific evidence on the efficacy of different methods as accelerators of tooth movement during orthodontic treatment: corticotomies, piezocision, micro-osteoperforations (MOP), photobiomodulation (LLLT and LED laser) and microvibrations. Search Methods: A comprehensive search was performed in the PubMed, Google Scholar, Scopus and Medline databases in May 2024. Selection Criteria: We selected randomized controlled trials based on acceleration of tooth movement during orthodontic treatment. Articles that were not randomized controlled trials (RCTs), were not published in the last ten years or corresponded to animal trials as well as those dealing with orthognathic surgery, distraction osteogenesis, electric currents, pulsed electric fields and pharmacological approaches were excluded. Results: Twenty-three studies were included in this review. All trials show accelerated tooth movement after low-level laser application, and seven studies support the efficacy of surgically assisted orthodontic treatment with corticotomies, piezocision or MOP. No article indicates statistically significant differences between the application of microvibration during orthodontic treatment and conventional treatment. No negative effects on the periodontium, loss of dental vitality or serious root resorption were reported in any publication, except in a study carried out with MOP (with an increase in root resorption). Conclusions: There is some evidence that low-level laser therapy and surgical methods are effective techniques in accelerating tooth movement during orthodontic treatment, while the evidence is very weak for vibration.

Magnetohydrodynamic Enhancement of Biofuel Cell Performance.

Biofuel cells have become an interesting alternative for the design of sustainable energy conversion systems with multiple applications ranging from biosensing and bioelectronics to autonomously moving devices. However, as an electrochemical system, their performance is intimately related to mass transport conditions. In this work, the magnetohydrodynamic (MHD) effect is studied as an easy and straightforward alternative to enhance the performance of a biofuel cell based on the enzymes glucose oxidase (GOx) and bilirubin oxidase (BOD). The synergetic effect between the electric and ionic currents, produced by the enzymatic redox reactions, and a magnetic field orthogonal to the surface of the electrodes, leads to the formation of localized magnetohydrodynamic vortexes. Such an integrated convective regime generates an increase of the bioelectrocatalytic current and its concomitant power output in the presence of the external magnetic field. In addition, by fine-tuning the spatial arrangement of the anode and cathode, it is possible to benefit from the sum of anodic and cathodic MHD vortexes, leading to an enhanced power output of up to 300%.

Exploring the Role of Prefrontal Cortex tDCS in Hypertension: A Mini-Review.

Arterial Hypertension (HTN) is the leading cause of cardiovascular diseases, which, in turn, are the primary cause of mortality worldwide. The success rates in Blood Pressure (BP) control among the general population remain unacceptably low. HTN etiology is multifactorial, but ample evidence has shown an essential role of the Autonomic Nervous System (ANS) dysfunction in its physiopathology. Concurrently, studies have pointed to the promising effect of non-invasive cortical stimulation techniques, such as transcranial Direct Current Stimulation (tDCS), on modulating blood pressure and the ANS. tDCS involves the application of a direct low-intensity electric current between two electrodes (cathode and anode) placed on the scalp and skull over areas of interest in the cerebral cortex. The impacts of this technique on regulating BP levels and cardiovascular autonomic modulation have excellent potential to be explored in hypertension. This study aimed to review and discuss the existing evidence concerning the efficacy of tDCS in modulating BP and ANS, focusing on its potential as a therapeutic intervention for HTN. This narrative mini-review presents and discusses critical findings regarding using tDCS to modulate BP and the ANS. Data obtained from clinical and preclinical studies have been addressed in this work. The evidence gathered and discussed in this mini-review suggests the promising role of tDCS as a non-invasive intervention for HTN; however, the underlying mechanisms through which it exerts its effects remain poorly understood. More mechanistic studies must be carried out to draw definitive conclusions regarding the effectiveness and safety of tDCS as a treatment for HTN.

Overview of the Factors Influencing the Efficiency of PV Solar Cells

PV technology works through the direct conversion of sunlight into electricity, a process based on the photoelectric effect. This phenomenon happens when specific materials absorb light particles, leading to the release of electrons. Capturing these electrons produces an electric current. Which can be harnessed as usable electricity. The development of more efficient PV system designs and enhancements in their operation and maintenance are key areas of current innovation. These advances are crucial for improving the overall performance and sustainability of solar energy systems, making them a more viable and dependable option for future energy needs. In the literature there are plenty of papers on solar energy, in order to advance the research on this subject we needs up to date information on the current situation. As such is lacking at present, A current literature review of this phenomenon is reffered for more detail.

Exciton Enhanced Nonlinear Optical Responses in Monolayer h-BN and MoS2: Insight from First-Principles Exciton-State Coupling Formalism and Calculations.

Excitons are vital in the photophysics of materials, especially in low-dimensional systems. The conceptual and quantitative understanding of excitonic effects in nonlinear optical (NLO) processes is more challenging compared to linear ones. Here, we present an ab initio approach to second-order NLO responses, incorporating excitonic effects, that employs an exciton-state coupling formalism and allows for a detailed analysis of the role of individual excitonic states. Taking monolayer h-BN and MoS2 as two prototype 2D materials, we calculate their second harmonic generation (SHG) susceptibility and shift current conductivity tensor. We find strong excitonic enhancement in the NLO responses requires that the resonant excitons are not only optically bright themselves but also able to couple strongly to other bright excitons. Our results explain the occurrence of two strong peaks in the SHG of monolayer h-BN and why the A and B excitons of MoS2 unexpectedly exhibit minimal excitonic enhancement in both SHG and shift current generation.

Electrochemically Induced, Metal Free Synthesis of 2-substituted chroman-4-ones.

Electrochemically induced, decarboxylative functionalization of chromone-3-carboxylic acids by N-hydroxyphthalimide esters as alkyl radical precursors was studied. Electrochemical protocol offers a sustainable and green approach, obviating the need for catalysts, relying on the direct reduction of NHPI esters using electric current. Developed protocol provides a straightforward route to the synthesis of diverse molecules with potential biological activity.

Energy harvesting through the triboelectric nanogenerator (TENG) based on polyurethane/cellulose nanocrystal

This study investigates how physical and mechanical properties affect the performance of triboelectric nanogenerators (TENGs). Polyurethane (PU) was prepared using two methods: (i) one-step PU (non-chain extended polyurethane) and (ii) two-step PU (chain extended polyurethane) via the prepolymer method; both types were filled with different concentrations of nanocrystalline cellulose. Mechanical properties significantly influence the deformation at the material interface that occurs during contact or friction. Key surface characteristics, including surface energy, geometry, and physicochemical properties, affect the effective contact area and potential distribution. One-step PU with 0.1 % CNC demonstrates a maximum capacitance of 29.20 pF, a voltage of 2.04 V, an electric current of 0.43 µA and power of 0.89 µW, representing a 74.5 % increase in power compared to the neat one-step PU, exhibits significant potential for TENG applications. Performance improvements are associated with lower concentrations of cellulose nanocrystals, enhanced hydrogen bonding, and beneficial surface energy. The observed enhancements in output are attributed to improved internal polarization from well-dispersed crystalline nanocellulose, increased crystallinity of the soft segment, and reduced charge transfer mechanisms due to amino groups in the chain extender. However, the impact of the molecular structure and conformation of polyurethanes on triboelectrification remains unclear, highlighting the need for theoretical models and experimental data. This research provides a practical approach for developing stretchable triboelectric materials with enhanced mechanical properties, emphasizing the importance of considering factors such as mechanical parameters, nanofiller content, and surface physicochemical properties to optimize TENG design.

The effect of single walled carbon nanotubes on conductivity and thermal properties of glass fiber reinforced composites

Abstract This paper reports on a comprehensive study of the effect of single-walled carbon nanotube (SWCNT) on the alternating current (AC) conductivity, thermal and morphological properties of the unsaturated polyester based glass fiber reinforced polymer composite (GFRPC). AC conductivity measurements were carried out using the impedance spectrum and thermal measurements were carried out using differential scanning calorimetry (DSC) at a temperature range of 24-900 °C and heating rates of 20 °C/min. Impedance results showed that the conductivity behavior in the nanotube-loaded composite laminate obeys a Jonscher-type mechanism. At low frequencies, the conductivity value remains almost constant for the doped material and takes the value of 10-5 S/cm. It is observed that the AC conductivity starts to increase after the critical frequency value of approximately 103 Hz and increases up to 10-2 S/cm due to hopping and tunneling mechanisms caused by space charge polarization accumulated in the local regions at high frequencies. The pure material with an insulating nature also exhibited a typical insulating behavior. Thermal testing showed that nanotube reinforcement increases thermal conductivity in three different directions. DSC thermocurves analysis also revealed that the addition of carbon nanotubes increased the glass transition temperature of the material from 180°C to 190°C. The scaling and fractal analysis methods were also applied to obtain hetero morphological structure of materials. The fractal analysis results indicated that carbon nanotube doping to the standard sample increases the coating rates, scalability and heterogeneity of the solid phase surface of the sample. The coating rates of composite surfaces were calculated as 45% and 36%, respectively. Morphology analysis revealed that the probability of finding surface particles for the nanotube-doped sample decreased compared to the undoped sample, but the fractal dimension value increased. While this value was 1.83 in the pure sample, it increased to 1.92 in the nanotube material.

Green Synthesis of Urea from Carbon Dioxide and Ammonia Catalyzed by Ultraporous Permanently Polarized Hydroxyapatite.

The sustainable synthesis of urea from ammonia (NH3) and carbon dioxide (CO2) using ultraporous permanently polarized hydroxyapatite (upp-HAp) as catalyst has been explored as an advantageous CO2-revalorization strategy. As the simultaneous activation of N2 and CO2 (single-step) demands an increase of the reaction conditions, we have re-visited the industrial two-step Bazarov reaction. upp-HAp has been designed as a stable multifunctional catalyst capable of promoting both CO2 and NH3 adsorption for their subsequent C-N bond formation. Herein we report the synthesis of 1 mmol/gcat of urea with a selectivity of 97% under strictly mild conditions (95-120 ºC and 1 bar of CO2; without applying any electrical currents or UV irradiation) which represents an efficiency of ~2% and ~30% with respect to the NH3 and CO2 content, respectively. The study of the NH3 content, products adsorbed in the catalyst, presence of intermediates and temperature of the reaction allows unveiling the great potential of upp-HAp as a green catalyst for sustainable Bazarov reactions. Results suggest that the double-step approach could be more advantageous for both synthesizing urea and as a CO2-revalorization strategy, which in turn promotes the development of specific technologies for the independent synthesis of green NH3.