Electrical Current Levels Research Articles

Weak electric current increases ceramide levels by inducing ceramide synthase expression

We previously demonstrated that weak electric current (WEC) induces the skin penetration of macromolecules by the cleavage of intercellular junctions and allows for incorporation of macromolecules into cells via endocytosis. We further showed that WEC facilitates the leakage of macromolecules from endosomes to cytoplasm and that this phenomenon correlates with increased endosomal ceramide levels. From these observations, it suggested ceramide production is induced by WEC. In this study, to investigate mechanisms by which WEC treatment increases ceramide levels, acyl chains in ceramides of WEC-treated cells were analyzed. As a result, we found that WEC increased the amounts of C16:0, C22:0, and C24:1 ceramides and that WEC induced ceramide synthase 2 expression. Therefore, we conclude that WEC activates the ceramide synthesis pathway and that increased endosomal ceramide would contribute to the leakage of macromolecules.

Bonding Properties of AA1050 Strips Fabricated Via Electrically Assisted Roll Bonding (EARB) Process

Abstract In this study, aluminium alloy 1050 strips were bonded together using the electrically assisted roll bonding process (EARB) at electric current levels from 0 A up to 300 A. The effect of electric current level and plastic strain as the two main EARB parameters have been investigated on bonding strength by using the peel test. Results showed that by increasing the electric current level and reduction in thickness, stronger bonding strength can be obtained. Scanning electron microscopy was utilized to characterize the peeled surfaces of samples versus different thickness reduction ratios and electric current levels. Decreasing the forming strength of strips and increasing the bond strength of bonded strips about three times due to Joule heating effect in the EARB process was achieved. Moreover, by scanning electron microscopy (SEM), the peeled surfaces of samples after the peel test have been studied to investigate the bonding quality.

Design and Simulation of Grid-Connected Photovoltaic System’s Performance Analysis with Optimal Control of Maximum Power Point Tracking Based on Artificial Intelligence

The research presented in this paper is part of a more significant effort to improve the dynamic and static performance of power generation systems using solar panels under specific climatic conditions. The solar panel can produce the greatest power only at the specified voltage and electric current levels. Environmental variables, such as random atmospheric oscillations, have a significant effect on the performance of a solar system connected to the network. Irradiation and ambient temperature are the two inputs to a PV (photovoltaic) system. Because solar radiation varies in nature, the PV system efficiency is low. To improve the efficiency of a solar PV system, several maximum power point tracking (MPPT) approaches are used. The purpose of this paper is to improve the performance of DC/DC chopper controllers and PV inverters in the face of abrupt climate change. To that end, the primary goal of this paper is to compare the following maximum power point search (MPPT) algorithms: the incremental conductance (IC) algorithm, the fuzzy logic (FL) algorithm, VSI controller, and the particle swarm optimization (PSO) strategy. These algorithms were evaluated in terms of efficiency, stability, and speed. A 100 kW PV system is design using MATLAB software 2021a version.

Electrochemotherapy treatment safety under parallel needle deflection

Electrochemotherapy is a selective electrical-based cancer treatment. A thriving treatment depends on the local electric field generated by pairs of electrodes. Electrode damage as deflection can directly affect this treatment pillar, the distribution of the electric field. Mechanical deformations such as tip misshaping and needle deflection are reported with needle electrode reusing in veterinary electrochemotherapy. We performed in vitro and in silico experiments to evaluate potential problems with ESOPE type II electrode deflection and potential treatment pitfalls. We also investigated the extent to which the electric currents of the electroporation model can describe deflection failure by comparing in vitro with the in silico model of potato tuber (Solanum tuberosum). The in silico model was also performed with the tumor electroporation model, which is more conductive than the vegetal model. We do not recommend using deflected electrodes. We have found that a deflection of ± 2 mm is unsafe for treatment. Inward deflection can cause dangerous electrical current levels when treating a tumor and cannot be described with the in silico vegetal model. Outward deflection can cause blind spots in the electric field.

Dynamic‐transient modeling and performance evaluation of a multilayer variable‐capacitance energy conversion system

This paper proposes an analytical method for dynamic-transient modeling of a variable capacitance energy conversion system as a multi-layer synchronous machine. The dynamic-transient models are achieved based on the analytical formulas and are valid for all machine structures with flat electrode plates. In addition, the equivalent circuits and operational characteristics are obtained for both dynamic-transient and steady-state conditions. The analytical model is evaluated and well verified through both experimental test results and computer-aided numerical methods such as finite element analysis (FEA). The numerical 3D-FEA simulations are performed using Ansys Maxwell 3D software. Design and manufacturing of the experimental prototype are performed using printed circuit board (PCB) technology. The variable capacitance machines (VCMs) have a low weight and volume, and fast transient response. The results show that the electrical current level of the VCMs is very low which can be effective in reducing electrical losses. In addition, regarding the duality between VCMs and magnetic machines, this paper compares some of the features and behaviors of these two groups of energy conversion systems.

Análisis de los factores que intervienen en el envejecimiento prematuro de las baterías de ion-litio mediante modelo teórico validado en laboratorio

Este artículo presenta un análisis cuantitativo de las variables que repercuten en el envejecimiento prematuro de las baterías de ion-litio.
 Para este cometido, primero se realiza la validación de un modelo teórico desarrollado en Matlab-Simulink mediante la comparación del comportamiento de sus parámetros de interés respecto a un sistema real implementado en laboratorio. Para ello se consideran parámetros como las características de las celdas y las condiciones ambientales en ambos casos.
 Posteriormente, una vez validada la herramienta de simulación, se realizan ciclos de carga y descarga en el modelo implementado en Matlab-Simulink. Como parte del proceso se realizan pruebas considerando diferentes temperaturas, tasas de carga/descarga, y diferentes profundidades de descarga, esto con el objetivo de determinar la repercusión de estos parámetros en la vida útil de las baterías de ion-litio.
 En la sección final del documento se presentan los resultados del experimento donde se expone, entre otros aspectos, la influencia de la temperatura ambiente en el deterioro de las baterías de ion-litio, así como, el impacto de un proceso de carga/descarga de las celdas estudiadas con altos niveles de corriente eléctrica.
 Este artículo presenta un análisis cuantitativo de las variables que repercuten en el envejecimiento prematuro de las baterías de ion-litio.
 Para este cometido, primero se realiza la validación de un modelo teórico desarrollado en Matlab-Simulink mediante la comparación del comportamiento de sus parámetros de interés respecto a un sistema real implementado en laboratorio. Para ello se consideran parámetros como las características de las celdas y las condiciones ambientales en ambos casos.
 Posteriormente, una vez validada la herramienta de simulación, se realizan ciclos de carga y descarga en el modelo implementado en Matlab-Simulink. Como parte del proceso se realizan pruebas considerando diferentes temperaturas, tasas de carga/descarga, y diferentes profundidades de descarga, esto con el objetivo de determinar la repercusión de estos parámetros en la vida útil de las baterías de ion-litio.
 En la sección final del documento se presentan los resultados del experimento donde se expone, entre otros aspectos, la influencia de la temperatura ambiente en el deterioro de las baterías de ion-litio, así como, el impacto de un proceso de carga/descarga de las celdas estudiadas con altos niveles de corriente eléctrica.

A Novel Method of Archaeological Bronze Identification - Electromagnetic Signatures <i>vs</i> Chemical Composition

Bronze metallurgy was a significant step in human technology and civilization as societies evolved from the Neolithic to the Bronze period and acquired the ability to shape different metals into useful tools. The technology to work with copper and bronze was independently developed across the world and, due to different smelting techniques and local ore chemistry, metal ware developed in different regions of the world at various time periods have unique chemical profiles. We previously developed a technique to identify metal alloys based on their stimulated dynamic magnetic signatures. We demonstrated that metals of different chemical composition would exhibit different electrical conductivity, and thus different magnetic field strengths when evoked by different levels of electric current. We further demonstrated that the electromagnetic signatures could be detected by the internal magnetometers located inside most smartphones as a part of the internal compass. In this manuscript we have compiled the electromagnetic signatures and magnetic force vectors of different copper alloys in various electromagnetic fields. The database of signatures are cross-referenced to chemical composition and tensile strength such that one can quickly compare the magnetic signatures of any unknown copper and bronze artifact and arrive at a tentative identity of the metal artifact.

Evaluation of the energy driving performance of a cooling system assembled with a Peltier module operated in hot climates at different electrical currents

Peltier devices have two sides with two different temperatures when an electrical current is applied through it. In the hot side, heat is dissipated and in the cool side, heat is absorbed, requiring additional electrical current to decrease heat absorption, primarily in hot climates. In this work, a block model was design with a Simulink tool of Matlab software to analyze thermal performance of a Peltier module in hot-imitate climate at different electric current levels. Through this model, it would be possible to evaluate the operating conditions of different control systems for Peltier applications, such as energy optimization in human thermal comfort devises, for sports, mobility, and medical care applications.

Performance Evaluation of Current Leads for a 5 Tesla Electromagnetic Properties Measurement System

The development of the Electromagnetic Property Measurement System is underway at the Korea Basic Science Institute. The Electromagnetic Property Measurement System is used for electrical, thermal, and magnetic specimen property measurements in variable magnetic fields and temperatures with a low-temperature superconducting magnet. To activate low-temperature superconducting magnet that operates with liquid helium, we propose the use of vapor-cooled current leads. The low-temperature superconducting magnet is connected to the power supply at room temperature through a pair of current leads. Accordingly, heat inflows through the current leads and represents one of the major contributory factors of the entire heat inflow. Therefore, design optimization and evaluation of the current leads is necessary to minimize heat and liquid helium consumption. Vapor-cooled, and hybrid current leads were designed and fabricated, and testing in liquid helium cryostat was conducted. The low-temperature superconducting magnet was charged with electrical current up to the operating level, and the liquid helium boil-off rate was measured with respect to the supplied electrical current level. The performances of the two current leads were accessed based on the thermal load and boil-off rate of the liquid helium. The experimental and analyzed liquid helium boil-off rates associated with the current leads were in close agreement.

Lyndsay Orr Pamela Houghton Paul Holyoke Deena Lala

This quasi-experimental design study aimed to determine whether an educational program could improve health care providers' knowledge and attitudes regarding the use of E-Stim for treating PrIs in community-dwelling individuals with spinal cord injury living in 1 region of Ontario, Canada. An educational intervention based on a university-level continuing education program was developed as part of a multifaceted knowledge mobilization project. Health care providers (eg, nurses, physicians, and allied health professionals) from multiple agencies were invited to participate. The instructional series included 8 online modules on background theory and knowledge and a hands-on workshop that familiarized participants with the equipment necessary to deliver E-Stim. Knowledge (percentage of correct answers using a knowledge test developed by the research team) and attitudes (assessed using the E-Stim Attitude Survey in which items were scored using a 5-point Likert scale (where 0 indicated a negative attitude and 5 a positive attitude) were evaluated 3 times (pre-education, post-online, and post-workshop). Data were aggregated into unit-weighted averaged composites of 3 attitude subscales (resources, evidence-based practice, and education), which were compared before and after educational sessions using a linear mixed effect model. Among the 83 participants, a significant increase in knowledge scores was noted from pre-education (55.9%) to post-online (78.4%) and post-workshop (78.0%) (X² [2] = 89.34; P <.001). A significant increase in attitude scores was noted across time points (resources: X² [2] = 27.32, P <.0001; evidence-based practice: X² [2] = 38.93, P <.0001; and education: X² [2] = 92.88, P <.0001). For the evidence-based practice subscale, attitude increased significantly post-online (t[127] = 6.03, P <.0001). For the resources subscale, a significant increase was detected after post-workshop (t[113] = 5.23, P <.001]. Online education increased health care providers' knowledge about E-Stim; however, hands-on workshops were required to change certain attitudes about the use of E-Stim for wound healing. Further research is required to evaluate 1) whether a change in knowledge and attitude scores translates to a practice change for health care providers and 2) the potential importance of ongoing coaching and mentorship for a sustainable change in the clinical setting.

Archaeometallurgical Analysis of Bronze Artifacts: A Magnetometer Approach

Bronze has been utilized by human civilization for the past five millennia, and societies across the globe have mined, extracted, and purified copper and tin to create bronze alloys. Due to the different mineral composition of ores and the varying techniques involved with metal smelting, bronze artifacts from around the world often have very different chemical compositions. The determination of chemical composition is often invasive and expensive, and is usually conducted in laboratories. We previously developed an inexpensive and mobile test to identify metal alloys based on their magnetic signatures. We demonstrated that metals of different compositions would exhibit different electrical conductivity, and thus different magnetic field strengths when evoked by different levels of electric current. In this manuscript, we now detail the experiment protocol to produce evoked dynamic electromagnetic signals from bronze alloys, and the capture of signals with the smartphone magnetometer.

Development and analysis of synoptic evaluation strategy for research platforms for Cochlear Implants and hearing aids

Cochlear Implants—Hearing Aids(CI/HA) offer opportunities for researchers wishing to advance algorithm development, since the existing commercial CIs/HAs are closed/sealed for customization, due to intellectual property and safety requirements. In general, Research Platforms (RPs), such as CCi-MOBILE (developed at CRSS-CILab, UTDallas), emulate the functionality of CIs/HAs, and allow researchers to insert their customized sub-algorithms for either benchtop (soundbooth) or field testing. To date, little formalized studies have explored RP performance effectiveness or a formal safety test paradigm. Here, a two phase comprehensive evaluation strategy is proposed that involves acoustical signal processing and user specified electrical stimulation configuration for CCi-MOBILE. While the full evaluation strategy is tedious (+407 h of audio testing: Acoustical test {380 h}, Stimulation parameter test {27 h}), an agile reduced safety test and researcher performance evaluation paradigm is developed by sub-sampling the comprehensive test and system evaluation parameter space. The synoptic safety and performance evaluation paradigm is evaluated to selectively prioritize test conditions based on: (i) acoustical diversity and electrical current level characteristics and (ii) CI stimulation configuration test conditions using physical limits of RF pulses. The proposed synoptic safety and performance evaluation paradigm is shown to be efficient, effective, and ensures reliability of each potentially deployed RP in the field.

Gamma-ray irradiation effects on the electrical properties of organic field-effect transistors

We investigated the changes in the organic transistor characteristics of poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) thin films upon high-energy gamma-ray irradiation. Devices based on both organic semiconductors showed a lower field-effect mobility and electrical current levels after gamma-ray irradiation. The threshold voltage of P3HT transistors shifted negative, while that of PCBM-based devices shifted positive. These changes in electrical performance of the devices can be utilized as a gamma-ray sensing elements.

Energy efficient spark plasma sintering: Breaking the threshold of large dimension tooling energy consumption

AbstractAn energy efficient spark plasma sintering method enabling the densification of large size samples assisted by very low electric current levels is developed. In this method, the electric current is concentrated in the graphite foils around the sample. High‐energy dissipation is then achieved in this area enabling the heating and full densification of large (alumina) parts (Ø 40 mm) at relatively low currents (800 A). The electrothermal mechanical simulation reveals that the electric current needed to heat the large samples is 70% lower in the energy efficient configuration compared to the traditional configuration. The presence of thermal and densification gradients is also revealed for the larger size samples. Potential solutions for this problem are discussed. The experiments confirm the possibility of full densification (96%‐99%) of large alumina samples. This approach allows using small (and low cost) SPS devices (generally limited to 10‐15 mm samples) for large‐size samples (40‐50 mm). The developed technique enables also an optimized energy consumption by large‐scale SPS systems.

3D printing of shape memory polymer (SMP)/carbon black (CB) nanocomposites with electro-responsive toughness enhancement

In this work, a simple approach to 3D printing of carbon black based shape memory polymer nanocomposites (SMP/CB) with toughness improving capabilities during programing stage using electrical stimulus is reported. Conductive SMP/CB nanocomposites, consisting of commercial SMP filled with conductive CB nanoparticles, were fabricated using solvent casting and single screw extrusion processes. Subsequently, material extrusion (ME) technique was used to 3D print dog bones type IV specimens for tensile test and electrical stimulus. It was found that SMP/CB electrical conductivity can be tuned by the filler fraction. In addition, electrical current passing through SMP/CB nanocomposites causes temperature increments and changes on material strength condition. Temperature profiles at various electrical current levels are reported. Moreover, Young’s modulus and toughness of the 3D printed specimens subjected and not subjected to electrical current are presented. It was observed that conductive SMP/CB specimens responded to electrical current stimulus by increasing their toughness four times higher than with no current applied during tensile test. This paper is a reference for rheological and conductive properties of SMP/CB nanocomposites fabricated by ME 3D printing process.

Rate modulation detection thresholds for cochlear implant users

The perception of temporal amplitude modulations is critical for speech understanding by cochlear implant (CI) users. The present study compared the ability of CI users to detect sinusoidal modulations of the electrical stimulation rate and current level, at different presentation levels (80% and 40% of the dynamic range) and modulation frequencies (10 and 100 Hz). Rate modulation detection thresholds (RMDTs) and amplitude modulation detection thresholds (AMDTs) were measured and compared to assess whether there was a perceptual advantage to either modulation method. Both RMDTs and AMDTs improved with increasing presentation level and decreasing modulation frequency. RMDTs and AMDTs were correlated, indicating that a common processing mechanism may underlie the perception of rate modulation and amplitude modulation, or that some subject-dependent factors affect both types of modulation detection.

Experimental Testbed for Monitoring the Energy Requirements of LPWAN Equipped Sensor Nodes

This paper presents a simple and flexible testbed for measuring and/or modifying the behaviour of sensor nodes equipped with radio interfaces of interest, like the LoRa ones. The proposed experimental testbed is using a module that measures the overall power consumption of the raspberry pi based sensor nodes hosting the radio modules like the LoRa interface. The power consumption measurements are performed at electric charge level and not at electric current level so as not to miss the sudden energy drains the radio transmit operation is invoking. Furthermore, the radio behaviour (e.g. transmit power or data rate modification) can be easily controlled via simple commands, sent via a conventional smart phone, making the overall setup ideal for educational purposes or not very experienced personnel.

Research of Influence of Noise Pollution on the Value of the Threshold Current Tangible

Stable safety while working on electrical installations can be achieved by following the rules of the electrical safety. Today maximum permissible levels of touch voltage and electric current flow through any part of a person’s body are established by Russian Federation GOST system 12.1.038-82. Unfortunately, recommended by International Electrotechnical Commission (IEC) maximum allowable amount of electric current and voltage level do not take into account interaction between said electric current and other physical factors; noise, in particular. The influence of sound frequency and its pressure level on body resistance has been proven earlier in thesis by V.V. Katz. Studies of the noise effects on the value of the threshold current tangible have been renewed in laboratories of Life Safety Department in South Ural State University. To obtain reliable results, testing facility that includes anechoic chamber, sources of simulated voltages and noise and a set of recording instruments was designed and built. As a rule, noise influence on electrotechnical personnel varies depending on noise level or/and the duration of its impact. According to modern theories, indirect noise influence on various organs and systems through central nervous system has to be considered. Differential evaluation of noise pollution and its correlation with emerged effects can be obtained with the usage of the dose approach. First of all, there were conducted studies, in which frequency of the applied voltage (f) was to 50 Hz. Voltages and currents that caused sensations before and during 97 dB noise affections were measured. Obtained dependence led to questioning previous researches results of the necessity of reducing the amperage of tripping protection devices. At the same time electrical resistance changes of human body were being studied. According to those researches, no functional dependence between fluctuations in the magnitude of the resistance of human body to electric current flow and constant noise affection were found. Taking into account that contradiction, additional studies of primary electrical safety criteria for cases when exposed to high frequency noise pollution were conducted.

Evaluating the effectiveness of local- and regional-scale wildlife corridors using quantitative metrics of functional connectivity

While corridors in conservation have a long history of use, evaluations of proposed or existing corridors in conservation landscapes are important to avoid the same fate as poorly-functioning “paper parks”. We used resistance surface modeling and circuit theory to evaluate a number of corridors developed at regional and at local scales that aim to improve connectivity for large wildlife in the central part of the Kavango-Zambezi transfrontier conservation area. We used hourly GPS data from 16 collared African elephants (Loxodonta africana), and associated environmental data at used versus available movement paths, to develop a hierarchical Bayesian path selection function model. We used the resulting resistance surface across the study area as an input into circuit theory modeling to assess how well connectivity levels were captured by both types of corridors relative to several alternative scenarios. We found that the majority of regional-scale corridors performed relatively well at capturing elevated levels of connectivity relative to non-corridor comparisons, with 7 of 9 corridors rated as good or better in terms of how they captured electrical current levels (a proxy for connectivity). In contrast, only 14 of 33 smaller-scale, local corridors captured significantly higher levels of connectivity than adjacent non-corridor areas. Our results have practical implications for the design and implementation of wildlife connectivity conservation efforts in the world's largest transfrontier conservation landscape. Modern connectivity science approaches can help evaluate which proposed corridors are likely to function as intended, and which may need further refinement.

Influence of structural defects in solution-processed InZnO semiconductors on the electrical stability of thin-film transistors

In this study, we investigate the morphological effect of solution-processed indium-zinc-oxide (InZnO) active layers on the electrical stability of InZnO thin-film transistors (TFTs). We first observe that in the spin-coating method, precursor agglomerates and aggregates remain on the substrates after spin coating an InZnO solution at a low spin speed, thereby causing particle-type morphological defects in the InZnO films. The morphological defects are proven to degrade the basic performance parameters of the InZnO TFTs, including the electrical current level, field-effect mobility, and threshold voltage. In addition, devices having morphological defects show a relatively large hysteresis in transfer characteristics compared to those without defects. In a test of the electrical stability over time, we determine that particle-type morphological defects cause a rapid increase in the conductivity of the InZnO films, which affects the variations in the saturation drain current and the threshold voltage.