Current Increases Research Articles

Analysis the impact of ground conductivity source current speed and source current rise time on peak induced voltage on overhead conductors

The paper presents a finite element modeling approach to analyze lightning-induced voltages (LIV) on overhead conductors, focusing on factors such as the distance from the strike point, ground conductivity, source current speed, and current rise time. Firstly, the return stroke current (RSC) at various altitudes throughout the lightning path and the electromagnetic field radiation surrounding the strike point have been thoroughly examined. Secondly, the influence of ground conductivity on peak-induced LIV on overhead conductor, with specific numerical findings (e.g., peak-induced voltages reaching 109.9 kV at 40 m horizontal distance from the strike point for finite ground conductivity; at the same horizontal distance, peak-induced voltages reaching 95.9 kV for infinite ground conductivity). Thirdly, it is observed that at different horizontal distances from the strike point, the peak-induced voltages on overhead conductors increase if the source current speed increases. Additionally, the impact of source current rise time on peak-induced voltages of an overhead conductor has been noted and found that if the source current rise time increases, peak-induced voltages decrease. When developing an overhead conductor protection strategy and creating a mechanism of failure, the suggested model and analysis would be helpful.

The Safety and Efficacy of Dietary Epigallocatechin Gallate Supplementation for the Management of Obesity and Non-Alcoholic Fatty Liver Disease: Recent Updates

Epigallocatechin gallate (EGCG) is the predominant bioactive catechin in green tea, and it has been ascribed a range of beneficial health effects. Current increases in obesity and non-alcoholic fatty liver disease (NAFLD) rates represent a persistent and burdensome threat to global public health. While many clinical studies have demonstrated that EGCG is associated with positive effects on various health parameters, including metabolic biomarkers, waist circumference, and body weight when consumed by individuals affected by obesity and NAFLD, there are also some reports suggesting that it may entail some degree of hepatotoxicity. The present review provides a comprehensive summary of the extant clinical findings pertaining to the safety and effectiveness of EGCG in managing obesity and NAFLD, with a particular focus on how treatment duration and dose level affect the bioactivity of this compound.

Exome sequencing reveals a rare damaging variant in GRIN2C in familial late-onset Alzheimer's disease

BackgroundAlzheimer's disease (AD) is a progressive neurodegenerative disorder with both genetic and environmental factors contributing to its pathogenesis. While early-onset AD has well-established genetic determinants, the genetic basis for late-onset AD remains less clear. This study investigates a large Italian family with late-onset autosomal dominant AD, identifying a novel rare missense variant in GRIN2C gene associated with the disease, and evaluates the functional impact of this variant.MethodsAffected and unaffected members from a Northern Italian family were included. Genomic DNA from family members was extracted and initially screened for pathogenic mutations in APP, PSEN1, and PSEN2, and screened for 77 genes associated with neurodegenerative conditions using NeuroX array assay. Exome sequencing was performed on three affected individuals and two healthy relatives. Bioinformatics analyses were conducted. Functional analysis was performed using primary neuronal cultures, and the impact of the variant was assessed through immunocytochemistry and electrophysiology.ResultsPathogenic variants were not identified in APP, PSEN1, or PSEN2, nor in the 77 genes in NeuroX array assay. Exome Sequencing revealed the c.3215C > T p.(A1072V) variant in GRIN2C gene (NM 000835.6), encoding for the glutamate ionotropic receptor N-methyl-D-aspartate receptor (NMDA) type subunit 2C (GluN2C). This variant segregated in 6 available AD patients in the family and was absent in 9 healthy relatives. Primary rat hippocampal neurons overexpressing GluN2CA1072V showed an increase in NMDAR-induced currents, suggesting altered glutamatergic transmission. Surface expression assays demonstrated an elevated surface/total ratio of the mutant GluN2C, correlating with the increased NMDAR current. Additionally, immunocytochemistry revealed in neurons expressing the mutant variant a reduced colocalization between the GluN2C subunit and 14-3-3 proteins, which are known to facilitate membrane trafficking of NMDARs.DiscussionWe identified a rare missense variant in GRIN2C associated with late-onset autosomal dominant Alzheimer's disease. These findings highlight the role of GluN2C-containing NMDARs in glutamatergic signaling and their potential contribution to AD pathogenesis.

Current Treatment Regimens and Promising Molecular Therapies for Chronic Hepatobiliary Diseases

Chronic hepatobiliary damage progressively leads to fibrosis, which may evolve into cirrhosis and/or hepatocellular carcinoma. The fight against the increasing incidence of liver-related morbidity and mortality is challenged by a lack of clinically validated early-stage biomarkers and the limited availability of effective anti-fibrotic therapies. Current research is focused on uncovering the pathogenetic mechanisms that drive liver fibrosis. Drugs targeting molecular pathways involved in chronic hepatobiliary diseases, such as inflammation, hepatic stellate cell activation and proliferation, and extracellular matrix production, are being developed. Etiology-specific treatments, such as those for hepatitis B and C viruses, are already in clinical use, and efforts to develop new, targeted therapies for other chronic hepatobiliary diseases are ongoing. In this review, we highlight the major molecular changes occurring in patients affected by metabolic dysfunction-associated steatotic liver disease, viral hepatitis (Delta virus), and autoimmune chronic liver diseases (autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis). Further, we describe how this knowledge is linked to current molecular therapies as well as ongoing preclinical and clinical research on novel targeting strategies, including nucleic acid-, mesenchymal stromal/stem cell-, and extracellular vesicle-based options. Much clinical development is obviously still missing, but the plethora of promising potential treatment strategies in chronic hepatobiliary diseases holds promise for a future reversal of the current increase in morbidity and mortality in this group of patients.

Study of thermohydrodynamic processes in the air environment in the system of melting ice on the wires of the power transmission line

The paper considers issues related to modeling thermal and hydrodynamic processes in the "wire – ice shell – air" system that occur during melting of ice on wires. The problem of ice shell growth on the surface of power transmission line wires has been known for a long time, and many works in the field of ice growth control and technical means of combating this phenomenon are devoted to its solution. Recently, works have appeared on melting systems that operate without disconnecting lines from consumers, which increases the reliability and uninterruptible power supply, reduces economic losses from undersupply of products during power supply interruptions. The process of ice melting can occur under conditions of heating the conductors with a high current to a steady positive temperature until the ice shell is destroyed. In this case, switching to the melting mode is carried out for a short period of time. An alternative to this method is to combine power supply to consumers and ice melting. In this case, the heat generation capacity in the wires is less, the melting time is increased, but there is no need to disconnect consumers. The problem of maintaining the line in the operating mode of transmitting electric energy to consumers is solved by additionally loading the line with reactive currents by connecting a certain inductive load. The increase in currents and power coming from the supply transformer to the line must be technically feasible so as not to overload the source and not cause its shutdown. Due to power limitations, it is necessary to carry out accurate calculations of thermal processes to determine acceptable modes of melting the ice layer. Complex modeling of thermohydrodynamic processes in the "wire – ice shell – air" system is considered. Several methods for determining the coefficients of convective heat exchange at the boundaries of the conductor at different wind speeds are considered.

Utilization of Palliative Care in Cardiogenic Shock Patients: A Retrospective Analysis of the National Inpatient Sample Database, 2020.

Background: Cardiogenic shock (CS) is one of the leading causes of death in patients with myocardial infarction, myocarditis, and congestive heart failure. The utilization patterns of specialist palliative care (PC) consultation in these patients are currently unknown. Objectives: To determine the utilization of PC in patients with CS and the overall comorbidities of that population. Methods: Review of the 2020 National Inpatient Sample identified 6,471,165 hospitalizations of which 38,531 patients were hospitalized with CS via International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10 CM) code R57.0. Demographics and details of hospitalization were compared for patients who received PC evaluation (N = 8457) and those who did not (N = 30,074) as identified via ICD-10 CM code Z51.5. Results: Patients who received PC evaluation were older (≥65 years: 69.01% vs. 55.04%, p < 0.001), had shorter hospital stays (<14 days: 78.92% vs. 70.35% patients, p < 0.001), and higher in-hospital mortality (65.80% vs. 24.23%, p < 0.001) with higher Charlson Comorbidity Index (≥4, 55.22% vs. 48.09%, p < 0.001). Furthermore, the patients who received PC had significantly higher odds of death than those who did not (adjusted odds ratio = 6, p < 0.0001). Conclusion: Despite high mortality rates, specialist PC is not routinely involved in the care of those who die with CS, although does appear to be utilized among those most likely to die. This suggests preferential utilization of specialist PC for terminal patients; however, further research will be helpful to better understand current consult practices and increase PC utilization for this highly morbid population.

Research on the Application of Silver Nanowire-Based Non-Magnetic Transparent Heating Films in SERF Magnetometers.

We propose a non-magnetic transparent heating film based on silver nanowires (Ag-NWs) for application in spin-exchange relaxation-free (SERF) magnetic field measurement devices. To achieve ultra-high sensitivity in atomic magnetometers, the atoms within the alkali metal vapor cell must be maintained in a stable and uniform high-temperature environment. Ag-NWs, as a transparent conductive material with exceptional electrical conductivity, are well suited for this application. By employing high-frequency AC heating, we effectively minimize associated magnetic noise. The experimental results demonstrate that the proposed heating film, utilizing a surface heating method, can achieve temperatures exceeding 140 °C, which is sufficient to vaporize alkali metal atoms. The average magnetic flux coefficient of the heating film is 0.1143 nT/mA. Typically, as the current increases, a larger magnetic field is generated. When integrated with the heating system discussed in this paper, this characteristic can effectively mitigate low-frequency magnetic interference. In comparison with traditional flexible printed circuits (FPC), the Ag-NWs heating film exhibits a more uniform temperature distribution. This magnetically transparent heating film, leveraging Ag-NWs, enhances atomic magnetometry and presents opportunities for use in chip-level gyroscopes, atomic clocks, and various other atomic devices.

Optimizing solar performance of CFTSe-based solar cells using MoSe2 as an innovative buffer layers

In this study, we explore the photovoltaic performance of an innovative high efficiency heterostructure utilizing the quaternary semiconductor Cu2FeSnSe4 (CFTSe). This material features a kesterite symmetrical structure and is distinguished by its non-toxic nature and abundant presence in the earth’s crust. Utilizing the SCAPS simulator, we explore various electrical specifications such as short circuit current (Jsc), open circuit voltage (Voc), the fill factor (FF), and power conversion efficiency (PCE) were explored at a large range of thicknesses, and the acceptor carrier concentration doping (NA). Our results demonstrate that optimized parameters yield a remarkable PCE of 26.47%, accompanied by a Voc of 1.194 V, Jsc of 35.37 mA/cm2, and FF of 62.65% at a CFTSe absorber thickness of 0.5 μm. Furthermore, the performance of the photovoltaic cell is assessed for the defect levels in the CFTSe absorber and MoSe2 buffer layers. Results indicate that deep defect levels above 1 × 1017 cm− 3 lead to a decrease in Jsc. The study also investigates the effect of operating temperature on cell performance within the 300–500 K range. A notable decline in Voc is observed, likely due to an increase in saturation current, suggesting an interaction between temperature and cell behavior. In this work, we propose a practical CFTSe-based structure that replaces conventional buffer layers, such as CdS, with MoSe2 TMDC as a promising alternative buffer layer, paving the way for more sustainable solar technology.

Enzyme-modified Pt nanoelectrodes for glutamate detection.

We present here a glutamate oxidase (GluOx)-modified platinum (Pt) nanoelectrode with a planar geometry for glutamate detection. The Pt nanoelectrode was characterized using electrochemistry and scanning electron microscopy (SEM). The radius of the Pt nanoelectrode measured using SEM is ∼210 nm. GluOx-modified Pt nanoelectrodes were generated by dip coating GluOx on the Pt nanoelectrode in a solution of 0.9% (wt%) bovine serum albumin (BSA), 0.126% (wt%) glutaraldehyde, and 100 U mL-1 GluOx. An increase in current was observed at +0.7 V vs. Ag/AgCl/1 M KCl with adding increasing concentrations of glutamate. Two-sample t-test results showed that there is a significant difference for current at +0.7 V between the blank and the added lowest glutamate concentration, as well as between adjacent glutamate concentrations, confirming that the increase in current is related to the increased glutamate concentration. The experimental current-concentration curve of glutamate detection fitted well to the theoretical Michaelis-Menten curve. At the low concentration range (50 μM to 200 μM), a linear relationship between the current and glutamate concentration was observed. The Michaelis-Menten constants of Imax and Km were calculated to be 1.093 pA and 0.227 mM, respectively. Biosensor efficiency (the ratio of glutamate sensitivity to H2O2 sensitivity) is calculated to be 57.9%. Enzact (Imax/H2O2 sensitivity, an indicator of the amount of enzyme loaded on the electrode) of the GluOx-modified Pt nanoelectrode is 0.243 mM. We further compared the sensitivity of a GluOx-modified Pt nanoelectrode with a GluOx-modified carbon fiber microelectrode (7 μm diameter and a sensing length of ∼350 μm). Glutamate detection on the GluOx-modified carbon fiber microelectrode fitted well to a Michaelis-Menten like response. Based on the fitting, the GluOx-modified carbon fiber microelectrode exhibited an Imax of 0.689 nA and a Km of 301.2 μM towards glutamate detection. The best linear range of glutamate detection on the GluOx-modified carbon fiber microelectrode is from 50 μM to 150 μM glutamate. The GluOx-modified carbon fiber microelectrode exhibited a higher potential requirement for glutamate detection compared to the GluOx-modified Pt nanoelectrode.

A centrifugal spring mechanism empowers self-adjusting in piezoelectric wind energy harvesting

Piezoelectric wind energy harvesters (PWEHs) offer promises in sustainable green energy supply for micropower electronics. However, traditional PWEHs encounter challenges in terms of high start-up wind speeds, subpar output performance, and narrow bandwidth, hampering their widespread adoption. To enhance the energy capture efficiency, a novel self-adjusting PWEH integrating a centrifugal spring mechanism (CSM) is presented. The CSM consists of a sliding rod, a 304 stainless steel spring, an exciting magnet, and a mass block. Additionally, the PWEH employs a vertical-axis blade design, allowing it to capture wind from different directions. Via theoretical analyses, finite element simulations, and experiments, key parameters of the PWEH are optimized including the CSM additional mass, spring wire diameter, and the configuration of multi-frequency piezoelectric transducers. Results demonstrate that the optimized PWEH works at 1.5m/s and generates 0.45mW, 2.742mW, and 5.973mW at wind speeds of 2m/s, 3.3m/s, and 4.75m/s, respectively. Compared to the unoptimized PWEH, the introduction of the CSM results in an 80.7% enhancement in open-circuit voltage and a 90.9% increase in short-circuit current. Additionally, by utilizing four pairs of piezo-transducers with different resonance frequencies (6.83Hz, 9.38Hz, 12.1Hz, and 14.8Hz), the resonance bandwidth of the PWEH is expanded to 1.5~5.5m/s. The feasibility of PWEH for powering signage, electronic screens, and Bluetooth thermohygrometer is demonstrated. The potential of PWEH in constructing high-precision intelligent wind speed monitoring systems is tested via convolutional neural networks. The study offers a strategy for designing the PWEH for both powering of the microelectronic devices, and intelligent sensing and monitoring of wind.

Effect of the Electrogalvanized and Galvannealed Zn Coatings on the Liquid Metal Embrittlement Susceptibility of High Si and Mn Advanced High-Strength Steel

The advanced high-strength steels (AHSSs) with high Si and Mn contents are extensively applied in the automobile manufacturing industry. To improve the corrosion resistance, Zn coatings are generally applied to the steel substrate. However, heat input and tensile stress occur during the resistance spot welding (RSW) process; thus, Zn-induced liquid metal embrittlement (LME) can be produced due to the existence of liquid Zn. Unfortunately, the LME occurrence can trigger the premature failure of welded joints, seriously affecting the service life of vehicle components. In this study, the LME behaviors in high Si and Mn RSW joints with electrogalvanized (EG) and galvannealed (GA) Zn coatings were comparatively investigated. Based on the Auto/Steel Partnership (A/SP) criterion, 16 groups of different welding currents were designed. In particular, four typical groups of RSW joints were selected to reveal the characteristics of the LME behaviors. Moreover, these four typical groups of EG and GA high Si and Mn RSW joints were, respectively, etched to measure their nugget sizes. The results indicated that with the increase in the welding current, more severe LME cracks tended form. As determined during the comprehensive evaluation of the 16 groups of EG and GA welded joints, higher LME susceptibility occurred in the EG high Si and Mn steels. It was concluded that the formation of Fe-Zn intermetallic compounds (IMCs) and internal oxide layers during the annealing process could account for the lower LME susceptibility in the GA welded joints.

Role of mutation G255A in modulating pyrethroid sensitivity in insect sodium channels.

A voltage-gated sodium channel (VGSC) plays a crucial role in insect electrical signals, and it is a target for various naturally occurring and synthesized neurotoxins, including pyrethroids and dichlorodiphenyltrichloroethane. The type of agent is typically widely used to prevent and control sanitary and agricultural pests. The perennial use of insecticides has caused mutations in VGSCs that have given rise to resistance in most insects. These mutations are located among the two pyrethroid receptors, i.e., PyR1 and PyR2, as predicted by previous studies. The two binding regions are relatively symmetrical, and here we focus on the linkers between S4 and S5 of Domains I and II. The S4-S5 linker can promote a rapid increase in sodium current and the onset of action potential. By predicting mutations in 19 other amino acids at all the amino acids on S4-S5 linkers, their harmfulness is analyzed, and whether they affect protein stability and drug binding is determined. Through molecular docking and based on docking scores, four mutations were predicted to affect the binding of sodium channels to pyrethroids. Mutations G255V, G255A, A906V, and A906T were introduced into the VGSC of Blattella germanica (BgNav1-1), and their effects on channel gating and pyrethroid sensitivity in Xenopus oocytes were studied. The treatment of VGSCs with two types of pyrethroids (1nM), Types I (permethrin, bifenthrin) and II (deltamethrin, λ-cyhalothrin), produced tail currents. Among the four, mutant G255A exhibited a certain degree of increased sensitivity to the two types of pyrethroids. This finding was in contrast with the three other mutations, which demonstrated a certain degree of sensitization to one or two pyrethroids. We predicted and validated the critical mutation G255A on the insect VGSC Domain I S4-S5 linker using by electrophysiological technology. In generally, under the pressure of many insecticides, gene modifications, such as transcriptional changes and point mutations in the coding region make insects resistant to insecticides. This phenomenon leads to a higher detoxification rate of insecticides and makes the target site insensitive. However, we found that G255A mutation could promote the combination of pyrethroid and VGSCs by changing the binding force with insecticides. This finding has potential application value in reversing insect resistance. The discovery of mutation G255A exhibits considerable significance for the current use of gene editing and gene drive technology to control pests and delay their resistance development.

Flow and heat transfer characteristics of a porous-coated cylinder under simultaneous wave and current forces at a high Reynolds number

In the present study, a two-dimensional finite volume method is used to simulate the heat transfer rate of a circular cylinder coated with different structures of porous materials at Re=4800. The incompressible uniform flow is associated with deep-water waves created by a flap-type wave maker to investigate the effects of simultaneous current and wave forces on the pressure coefficients, flow characteristics, and heat transfer rate of cylinders wrapped by various porous structures (S2, S3, S4, and S5) and different Darcy numbers (Da=10, 10−1, and 10−2). According to the results, the porous layer thickness (e*) affects the outer shape of the porous coating and alters the influence of wave–current interaction on the flow characteristic. Therefore, compared to the current case, the lift and drag forces in the wave–current case increase in S2, but decrease in other porous structures. Moreover, S5, with the thickest porous coating showed the maximum heat transfer rate. Porous materials with low permeability decrease the impact of e* on heat transfer. However, the vortex-shedding patterns with thermal plumes become stronger with decreasing the Darcy number. The heat transfer rate of porous structures increases by about 42% as Da decreases from 10 to 0.1, and another 37% increase is observed at Da= 0.01, resulting in a total rise of 96% in the average Nusselt number (Nu¯). Therefore, the gap between the heat transfer rate of porous structures and the smooth cylinder (S1) increases by about 17%, 79%, and 126% at Da= 10, Da= 0.1, and Da= 0.01, respectively.

The physical mechanisms of plasma directional deflection in cross-coupled arc

Cross-coupled arcs (CCAs), as a novel heat source, enable decoupled control of heat and mass transfer, offering significant potential in metal processing applications such as additive manufacturing, welding, and surface treatment. To ascertain the primary cause of the main-arc deflection in the CCA, numerical models of the double-wire plasma arc (DW-PA), CCA, and without magnetic coupling for plasma cross-coupled arc (WMC-CCA) were constructed. Through the comparative analysis of the temperature, electromagnetic field, and force field following the calculation of the models, the coupled magnetic field in the CCA is the fundamental cause of the influence of the main-arc deflection. Additionally, the welding parameters in the CCA numerical model are modified to analyze its effect on the extent of main-arc deflection. As the main-arc current and inter-wire current increase, the degree of main-arc deflection concomitantly increases. The center area of the main-arc deflects relatively small because high plasma flow velocity increases the arc stiffness, hindering its deflection to the sides. In addition, the spatial position of the welding wire is another key factor affecting arc deflection.

Improved Voltammetric Procedure for Chloride Determination in Highly Acidic Media.

Cyclic voltammetry (CV) can be applied as a reliable method for the determination of chloride ions in a range from several to a couple hundred (about 200) ppm. Since the standard potential of chloride ion/gaseous chlorine is 1.36 V vs. normal hydrogen electrode (NHE), the efficient oxidation of Cl- ion occurs at very positive electrode potentials, usually higher than +1.7 V vs. NHE. It is possible to observe this phenomenon only at noble-metal or inert carbon electrodes. Many other solutes, usually organic compounds, are often oxidized at this potential. This is the reason why the determination of Cl- content directly from an increase in the oxidation current is not reliable and could lead to overestimated values. However, gaseous chlorine, generated at a positive potential dissolve in the analyzed solution, could be reduced in the reverse scan of a cyclic voltammetric curve. Optimization of the experimental procedure using statistical tools enables the development of an improved method for the direct quantification of chloride ions in acid copper electroplating baths. Under the proposed experimental conditions, the calibration curve (Cl2 voltammetric reduction current vs. chloride ions concentration) is represented by the linear model for the concentration of chlorides ranging from 10 to 200 mg/dm3. The developed method for analyzing chloride ions in an acid sulfate electroplating copper bath has many unique properties. It is fast; the time of a single analysis is less than 20 min. In automatic mode, it can be repeated up to 50 times a day. The method does not require processing of the sample of the analyzed bath before measurement. As a result, no additional chemical reagents are used, and the test sample can be returned to the plating bath.

Determination of performance properties of galvanic coatings based on cobalt

Abstract. Problem. An effective solution to the problem of the durability of construction materials is the application of protective coatings, which allow tosignificantly expand the scope of use and service life of products. The purpose of the work was to determine the performance characteristics of electrolytic coatings with Co-Ni-Zr alloy, namely adhesion and microhardness. Methodology The microhardness of the coatings was determined by the indentation depth of the diamond pyramid. Coating adhesion was determined by the fracture method. The chemical composition of the obtained coatings was determined by the X-ray fluorescence method using the SPRUT portable spectrometer. The analysis was carried out at least in 3 points with subsequent averaging of the obtained values. Electrodeposition was carried out with a unipolar current in stationary and pulsed modes (ti/tр=2/2) while varying the current density. Originality. There are no signs of delamination of the coatings on the sandpaper, which emphasizes strong adhesion to the base. The results of metallographic studies proved that Co-Ni-Zr coatings have good adhesion to the substrate material and retain it under mechanical loads. The highest value of microhardness – 850.0 MPa was obtained in the galvanostatic mode at i = = 6 A/dm2, while the zirconium content in the alloy is 1.5 wt.%. From the results of the experiments, it can be concluded that the zirconium content does not affect the microhardness of the Co-Ni-Zr coating. When the current density increases, the microhardness of the deposit decreases, which can be explained by reaching the maximum density of the deposition current. The optimal deposition current density for the galvanostatic mode is 6 A/dm2, pulsed 6 A/dm2 for obtaining coatings with high microhardness

Entropy Production in an Electro-Membrane Process at Underlimiting Currents—Influence of Temperature

The entropy production in the polarization phenomena occurring in the underlimiting regime, when an electric current circulates through a single cation-exchange membrane system, has been investigated in the 3–40 °C temperature range. From the analysis of the current–voltage curves and considering the electro-membrane system as a unidimensional heterogeneous system, the total entropy generation in the system has been estimated from the contribution of each part of the system. Classical polarization theory and the irreversible thermodynamics approach have been used to determine the total electric potential drop and the entropy generation, respectively, associated with the different transport mechanisms in each part of the system. The results show that part of the electric power input is dissipated as heat due to both electric migration and diffusion ion transports, while another part is converted into chemical energy stored in the saline concentration gradient. Considering the electro-membrane process as an energy conversion process, an efficiency has been defined as the ratio between stored power and electric power input. This efficiency increases as both applied electric current and temperature increase.

Performance-enhanced piezoelectric energy harvesting system induced by Karman vortex using concave pseudo-blunt body structure

Abstract In recent years, the technology of fluid-induced piezoelectric vibration energy harvesting for blunt body structures based on Karman vortex street effect has been widely studied. In order to further improve the efficiency of energy harvesting, a performance-enhanced method of Karman vortex street energy harvesting based on structural modification is proposed. Different pseudo-blunt bodies with concave surfaces are designed and combined with piezoelectric device to harvest energy. The finite element simulation results show that, compared with the cylindrical blunt body, the pseudo-blunt body with concave surface can enhance the turbulent action of the fluid and make the Karman vortex shedding more intense. Especially for the pseudo-blunt body with S-concave, the amplitude of Karman vortex street and the turbulent kinetic energy behind the pseudo-blunt is strongest. In addition, based on wind tunnel, the energy harvesting performance of Karman vortex behind a cylinder with different surface structures is experimentally studied. The experimental results show that the piezoelectric energy harvesting efficiency behind the cylindrical pseudo-blunt body with concave surface is better than that behind the cylindrical blunt body without concave surface. In particular, the S-concave pseudo-passivate has the best energy harvesting performance, with a peak output voltage of 23.6 V, an output voltage span of 31.2 V, a maximum current of up to 0.23mA, and a maximum power density of up to 6.64 W/m³, which are 136% and 81% higher than that of the ordinary cylindrical passivate, with an increase in the maximum current of 155% and an increase in the optimal power density of 532%, respectively. The above results show that the concave-based pseudo-blunt body structure can effectively improve the efficiency of vortex energy harvesting using piezoelectric mechanism, which lays an important foundation for the development and application of piezoelectric vortex energy harvesting theory.

Performance of the AlGaN/GaN HEMT with Sunken Source Connected Field Plate under High Voltage Reverse Bias Step Stress

The manuscript investigates the DC performance of conventional HEMT and Sunken Source Connected Field Plate (SSC-FP) HEMT reliability under reverse bias step stress. To assess the electrical performance of the device at the gate terminal is subjected to a high reverse bias step stress up to – 40 V with an increase of – 5 V step. A higher degree of ON–state resistance (RON) degradation is observed in the conventional HEMT than in the SSC-FP HEMT device. Post-stress drain to source current (Ids) degradation is ~11% and ~6% in non-FP and with SSC-FP devices respectively. In conventional devices when gate voltage (VGS) is up to -20V, the device leakage current is recoverable but after that, the gate current increases exponentially and becomes noisy. In SSC-FP devices, this behavior is shown after gate voltage -30V.

The Synthesis and Characterization of CdS Nanostructures Using a SiO2/Si Ion-Track Template

In the present work, we present the process of preparing CdS nanostructures based on templating synthesis using chemical deposition (CD) on a SiO2/Si substrate. A 0.7 μm thick silicon dioxide film was thermally prepared on the surface of an n-type conduction Si wafer, followed by the creation of latent ion tracks on the film by irradiating them with swift heavy Xe ions with an energy of 231 MeV and a fluence of 108 cm−2. As a result of etching in hydrofluoric acid solution (4%), pores in the form of truncated cones with different diameters were formed. The filling of the nanopores with cadmium sulfide was carried out via templated synthesis using CD methods on a SiO2 nanopores/Si substrate for 20–40 min. After CdS synthesis, the surfaces of nanoporous SiO2 nanopores/Si were examined using a scanning electron microscope to determine the pore sizes and the degree of pore filling. The crystal structure of the filled silica nanopores was investigated using X-ray diffraction, which showed CdS nanocrystals with an orthorhombic structure with symmetry group 59 Pmmn observed at 2θ angles of 61. 48° and 69.25°. Photoluminescence spectra were recorded at room temperature in the spectral range of 300–800 nm at an excitation wavelength of 240 nm, where emission bands centered around 2.53 eV, 2.45 eV, and 2.37 eV were detected. The study of the CVCs showed that, with increasing forward bias voltage, there was a significant increase in the forward current in the samples with a high degree of occupancy of CdS nanoparticles, which showed the one-way electronic conductivity of CdS/SiO2/Si nanostructures. For the first time, CdS nanostructures with orthorhombic crystal structure were obtained using track templating synthesis, and the density of electronic states was modeled using quantum–chemical calculations. Comparative analysis of experimental and calculated data of nanostructure parameters showed good agreement and are confirmed by the results of other authors.