Electric Current Research Articles

ALMA Observations of Solar Spicules in a Polar Coronal Hole

Abstract We report observations of solar spicules at millimeter wavelengths (mm-λ) using the Atacama Large Millimeter/submillimeter Array (ALMA). These are supplemented by observations in optical, ultraviolet (UV), and extreme ultraviolet (EUV) wavelengths. The observations were made on 2018 December 25 of the northern polar coronal hole. ALMA obtained time-resolved imaging observations at wavelengths of 3 mm (100 GHz; 2 s cadence) and 1.25 mm (239 GHz; ≈2 minutes cadence) with an angular resolution of 2 . ″ 2 × 1 . ″ 3 and 1 . ″ 5 × 0 . ″ 7, respectively. Spicules observed at mm-λ are easily seen low in the chromosphere whereas spicules in UV bands are seen to extend higher. The spicules observed at mm-λ are seen in absorption against coronal EUV emission, allowing us to estimate the column depth of neutral hydrogen. Spicular emission at mm-λ, due to thermal free–free radiation, allows us to estimate the electron number density as a function of height. We find that spicule densities, inferred from the mm-λ data are uniquely insensitive to assumptions regarding the temperature of plasma in spicules. We suggest that the upward mass flux carried by spicules is unlikely to play a significant role in the mass budget of the solar corona and solar wind, and the transport of hot material into the corona by spicules may not play a significant role in coronal heating. However, the possibility that electric currents, fast kink and torsional waves, or other wave modes carried by spicules may play a role in transporting energy into the solar corona cannot be excluded.

High Q-factor mie lattice resonance generated from out-of-plane magnetic dipole in all-dielectric defected semi-cylinder metasurface array

Abstract Due to the weak far-field radiation and strong local field enhancement properties of Mie lattice resonances(MLRs), a transmission resonance with a significantly high Q factor is achieved, which can be used in applications such as refractive index sensing, filtering, and nanolasing. In this paper, we design a semi-cylinder with a cuboid defect metasurface array working in the near-infrared, where a resonance with extremely narrow linewidth in transmission spectrum has been demonstrated at the wavelength of 870.9408 nm. The full width at half-maximum of the resonance is as narrow as 0.0032 nm with a corresponding Q factor of 272169. According to distributions of the electric field and displacement current, it is confirmed that the narrow linewidth resonance is generated by the MLR, which originates from the coupling between the out-of-plane magnetic dipole mode and Rayleigh Anomalous diffraction. It is further verified that the out-of-plane magnetic dipole mode is excited due to the induce defect in the semi-cylinder. When applied to refractive index sensing, a sensitivity of 333 nm RIU‒1 and a figure of merit of 104063 RIU − 1 are numerically achieved simultaneously. Our study here provides a new approach for achieving resonances with high Q-factors for the required applications.

Plasticizer modulation of dynamic mechanical properties and dielectric performance in sodium alginate-based biopolymer films

Abstract This work focuses on the effects of various plasticizers, such as glycerol (GLY), polyethylene glycol (PEG), and dioctyl phthalate (DOP) at 0%, 25%, and 50% concentrations, on the structure, dynamic mechanical behavior, and relaxation dynamics of charge carriers of sodium alginate (SA) film. The investigation of the structure was conducted using attenuated total reflectance fourier transform infrared (ATR-FTIR) and X-ray diffraction (XRD). The AT-FTIR analysis indicated changes in the OH and C–O bands of plasticized SA films, suggesting potential intermolecular interactions between the SA matrix and the plasticizers. Moreover, XRD revealed that GLY and PEG enhanced the amorphous phase of SA, promoting flexibility, while DOP increased crystallinity. Dynamic mechanical testing revealed that the pristine SA biofilm displayed a high storage modulus ( $$\:E^{\prime}$$ ) of 11 GPa at − 50 °C, indicating a stiff structure. The plasticization process with GLY, PEG, and DOP resulted in a decrease in the values to 0.09, 0.1, and 7.11 GPa, respectively, as well as a decrease in the glass transition temperature, which was attributed to weakened polymer chain interactions. The drastic reduction in storage modulus upon plasticization indicates enhanced flexibility. Dielectric measurements revealed significantly higher dielectric constants ranging from 1.65 × 106 to 0.12 × 106 at 0.1 Hz and direct current conductivity at lower frequencies, also decreasing in relaxation time for films plasticized with GLY and PEG linked to increased hydroxyl groups and higher amorphous content. These findings highlight the potential of SA films plasticized with GLY and PEG as advanced materials for electrochemical and conductive polymer electrode applications.

The Research on the Construction of Traditional Village Heritage Corridors in the Taihu Lake Region Based on the Current Effective Conductance (CEC) Theory

This study focuses on constructing a heritage corridor for traditional villages in the Taihu Lake region, aiming to promote the cultural heritage preservation and sustainable development of these villages through innovative pathway design. Based on the spatial distribution characteristics of traditional villages across five cities surrounding Taihu Lake (Suzhou, Wuxi, Changzhou, Huzhou, and Jiaxing) and the existing transportation network, this research integrates the Circuit Effective Conductance (CEC) theory with ArcGIS spatial analysis methods to optimize the pathways of the heritage corridor. The results show that the expected nearest neighbor distance of 307 traditional villages in the Taihu Lake region is 5245.61 m, with the actual nearest neighbor distance being 3385.60 m, a z-score of −11.85, and a nearest neighbor index of 0.645786, indicating that traditional villages in this region exhibit clustered distribution. Combined with kernel density results, a “dual-core–four zones–multiple scatter points” spatial structure of traditional villages in the Taihu Lake region is revealed, with Dongshan Island and Wujiang District serving as the primary and secondary cultural cores, respectively. By establishing a “dual-ring heritage corridor” spatial network, a stable pathway for village heritage preservation and cultural transmission has been formed, consisting of 137 heritage corridors. Meanwhile, the CEC model demonstrates high adaptability in generating circular heritage corridors, particularly in creating closed-loop structures around the lake, thereby enhancing the spatial connectivity of the corridors and facilitating the effective flow of cultural resources. Through the strategic design of outer and inner ring corridors, this study successfully links traditional villages in the Taihu Lake region and develops optimal travel routes. The study provides practical solutions for the protection, revitalization, and integration of cultural tourism in the region and offers a new perspective for constructing heritage corridors in lakefront geographies in China.

A review of parameter settings for galvanic vestibular stimulation in clinical applications

Galvanic Vestibular Stimulation (GVS) is a method of manipulating the vestibular system through non-invasive electrical current. Depending on how GVS is applied, it produces specific sensations related to vestibular mediated central pathways. The method has been tested for decades for both medical and non-medical applications and has demonstrated promise in treating a variety of disorders including peripheral vestibular conditions, central vestibular pathology due to neurodegenerative diseases, and post-stroke motor rehabilitation. As GVS continues to grow in popularity and applications, the field lacks clarity on appropriate stimulation parameters, despite their importance for safe and efficacious neuromodulation. This study aims to review the parameters used in various treatment applications while also providing a concise overview of the mechanisms underlying GVS thereby offering essential context and justification for the chosen parameters. We performed a literature search on the PubMed and Embase databases for clinical trials including the term “galvanic vestibular stimulation.” After removing duplicates, secondary analyses, and studies that did not use GVS for therapeutic purposes, we were left with 53 independent studies. We extracted the stimulation parameters used in each study and report them here. The results of this review suggest that while some stimulation parameters are relatively standardized for specific treatment indications, others lack universally accepted guidelines as the field of GVS continues to evolve. Based on our findings, we recommend that future GVS research include at least one sham condition, the use of individualized current intensity, and the comparison of multiple GVS parameters within the same trial.

Electrical conduction in ternary Na2O-ZnO-B2O3 glasses; a unique dependence on the mobility of Na+ ions as main charge carriers

Electrical conduction in ternary Na2O-ZnO-B2O3 glasses; a unique dependence on the mobility of Na+ ions as main charge carriers

Study on the change of the oil-paper insulation’s AC conductivity characteristics based on dielectric response in frequency domain

Oil-immersed power equipment (transformers and high voltage bushings) are key components of power systems. Oil-paper insulation has endured complex and harsh operating conditions when used as a primary insulation system, so it is essential to determine the insulation state of oil-paper insulation system to ensure a stable operation for the power grid. The oil-paper insulation’s conductivity behavior can effectively characterize the degree of insulation deterioration. However, the relationship between the alternating current (AC) and direct current (DC) conductivity behavior for oil-paper insulation systems is still unclear in current research, resulting in limitations in the traditional evaluation model’s application. Therefore, this paper uses oil-paper insulation materials under different aging to carry out relevant research about the changing features of the complex AC conductivity under different test temperature environments. The influence of oil-paper insulation aging, test temperature, and excitation frequency on the complex AC conductivity is verified. Considering the correlation between low-frequency AC conductivity and DC conductivity, the frequency range of AC conductivity is extended by means of frequency temperature and conductance double translation. The temperature dependence of the AC conductivity behavior is defined over a wide frequency test range. The relaxation polarization process dominated the AC conductivity variation law is obtained. The impact of experimental temperature and insulation aging on the cumulative characteristic parameters of AC ionic mobility is clarified. This study theoretically corrects the traditional calculation model for AC conductivity of oil-paper insulation. The bias in conductivity calculations caused by only considering a single relaxation polarization process is eliminated. The conductivity model that can characterize multiple relaxation polarization processes in the dielectric is established. This model provides theoretical support for the later assessment of oil-paper insulation state depending on conductance behavior.

MAPK14/AIFM2 pathway regulates mitophagy-dependent apoptosis to improve atrial fibrillation.

To investigate the role and mechanism of MAPK14/AIFM2 pathway in Ang II-induced atrial fibrillation in rats. A rat model of AF was established for in vivo experiments and HL-1 cells were treated with Ang II to develop an in vitro model. In addition, HL1 cells overexpressing AIFM2 (oeAIFM2) were constructed. SB203580 was used to inhibit the expression of MAPK14. The role of MAPK14 in Ang II-AF model was investigated by in vivo electrophysiological examination and molecular biology tests. The role of MAPK14 / AIFM2 pathway on AF induced by Ang II was explored in vitro. MAPK14 and AIFM2 were significantly up-regulated in AF induced by Ang II (all P<0.05). In vivo experiments indicated that inhibition of MAPK14 down-regulated AIFM2, improved atrial electrical conduction, AF inducibility and durations, and alleviated the structural and functional damage of heart and mitochondria (all P<0.05). Both in vivo and in vitro tests showed that the MAPK14/AIFM2 pathway prevented Ang II-induced AF via regulating mitophagy-dependent apoptosis. Inhibition of the MAPK14/AIFM2 pathway improved Ang II-induced AF by inhibiting mitophagy-dependent apoptosis.

Innovation in The Use of Organic Waste for Biobattery and Biogas Production at TPS3R Lamongan

Organic waste that accumulates in the 3R Waste Processing Site (TPS3R) environment needs to be utilized as well as possible. The purpose of this community service activity is to utilize energy from organic waste as the main raw material for making biobattery and biogas. The final result of this community service is a tool that can convert energy from organic waste to electricity (biobattery) and produce gas (biogas). The community service method uses socialization and technology application workshops by assembling tools and materials. Biobattery and biogas equipment, if operated every day, can increase the utilization of organic waste by 17 kg, with 5 kg for biobattery and 12 kg for biogas. Biobattery cells containing around 100 mL of organic waste can produce a maximum voltage of 0.9 Volts and a maximum electric current of 6 mA. Biogas itself requires a sorting process and a fermentation process whose time is adjusted to the presence or absence of organic waste stock at TPS3R. The initial Biogas Place (Digester) requires 600 kg of organic waste. This community service work is expected to inspire the community, especially the Sekar Manfaat Sekaran Lamongan TPS3R Team, to better manage the waste in their surroundings.

Modeling of Glugur Substation grounding systems using MATLAB graphical user interface

The grounding system in substations generally uses electrode rods, because electrodes can affect the effectiveness of fault current conduction, so the equipment will be safer. Considering the importance of the grounding system, the installed grounding system must be considered and maintained properly. One of them is the grounding found in Glugur. The main objective of this research is to comprehensively evaluate the substation grounding system by modeling the grounding system at the Glugur Substation using MATLAB graphical user interface (GUI). The grounding resistance follows a grid system with an area of 20×15=300 m² with specific resistance being clay using 100 rod electrodes. From the results of ground resistance simulation modeling using MATLAB GUI, it can be concluded as follows: for a certain resistance value, the number of electrodes for 100 Ωm is 3.55 Ω, for ground resistance with a constant depth and a varying number of 100 electrodes, it is 3.45 Ω, and for. The grounding resistance with a constant and varying number of 1,000 rods is obtained at 2.65 Ω. From these results, the modeling carried out is in accordance with the standards of electricity regulations in Indonesia.

Chemical and structural features of spin-coated magnesium oxide (MgO) and its impact on the barrier parameters and current conduction process of Au/undoped-InP Schottky contact as an interfacial layer

This work examines the structural and chemical characteristics of spin-coated magnesium oxide (MgO) on undoped InP (un-InP) and its effects on the barrier parameters and current transport phenomena in the Au/un-InP Schottky contact (SC). Using XRD and XPS, the structural and chemical features of MgO are assessed, confirming that the MgO was deposited on un-InP. The current-voltage (log(I)-V) features were measured for the SC and Au/MgO/un-InP metal/insulator/semiconductor (MIS)-type Schottky contact. The MIS contact revealed an excellent rectification behavior as compared to the SC. The calculated barrier height (Φb) was higher for the MIS contact (0.61 eV) than the SC (0.52 eV), which implies that the MgO interlayer influences the Φb of the SC. The Φb was also estimated using the Cheung’s, Mikhelashvili and Norde procedures, the values are similar, indicating their stability and reliability. The acquired interface state density (NSS) of the MIS contact was less than the SC, proving that the MgO interlayer reduced the NSS. The ohmic behavior was observed in the lower bias region for the SC and MIS contacts, while the trap-free space-charge-limited current (SCLC) was noted in the moderate and upper bias regions of the MIS contact under forward bias. Poole-Frenkel emission (PFE) governs at a lower bias, while Schottky emission (SE) dominates at the upper bias of SC and MIS contacts under reverse bias. These findings demonstrate the potential application of MgO interlayer in advancing electronic devices.

Nanopores for DNA and biomolecule analysis: Diagnostic, genomic insights, applications in energy conversion and catalysis.

Recently, nanopores have emerged as highly significant structures with broad applications in diverse scientific and technological fields. They can naturally occur in biological membranes or be artificially fabricated using advanced techniques. Recent advances in nanopore technology have revolutionized genomics by offering previously unheard-of capacities for deoxyribo nucleic acid (DNA) sequencing and analysis. These tiny holes allow individual molecules to be found more easily, allowing for real-time DNA analysis and providing currently unheard-of insights into genetics and diagnostics. By tracking alterations in electrical or ionic currents as biomolecules traverse the pore, nanopores make possible the real-time recognition of other biomolecules, like proteins, nucleic acids, and small molecules, eliminating the need for labeling. This label-free detection potential holds a huge promise in medical diagnostics, genotyping, environmental monitoring, etc. Nanopores have significantly improved DNA sequencing technology such as increment in read length, enabling researchers to sequence entire genomic regions, accuracy can be improved and recent updates have led to a reported increase in total DNA reads, demonstrating the technology's capacity for high-throughput applications via trapping individual DNA strands and monitoring the variations of ionic current as each nucleotide passes across the pore. Finally, nanopore sequencing is well-known as a novel and highly flexible technique for DNA analyses, which has a huge deal of promise in clinical diagnosis and genomics research. Hence, this review article comprehensively explains nanopores for DNA analysis and other biomolecules, their synthesis, and diverse applications.

Advancing cancer therapy with custom-built alternating electric field devices

BackgroundIn glioblastoma (GBM) therapy research, tumour treating fields by the company Novocure™, have shown promise for increasing patient overall survival. When used with the chemotherapeutic agent temozolomide, they extend median survival by five months. However, there is a space to design alternative systems that will be amenable for wider use in current research. Therefore, we sought to establish a custom-built alternating electric field device to investigate the effect of electrode design on the responsiveness of cancer cells to this therapy.MethodsA 96-well microtiter plate modified with an electrode array was fabricated to investigate its application as an in vitro alternating electric field device. This was initially performed with patient-derived GCE 31 and GIN 31 cell lines found in the core and invasive margin of the GBM tumour, respectively. We sought to establish the effect of the application of low-intensity (3 V/ cm) electric fields with an application duration of 4—48 h, using intermediate frequency (300 kHz) alternating currents (AC). To demonstrate that electric fields were entering the cell, GCE 31 and GIN 31 cells were treated with the inorganic, non-conductive zinc oxide (ZnO) nanoparticles (NP), previously demonstrated to enhance the efficacy of TTFs. After a 4-h exposure to NP, cells were then exposed to alternating electric fields or currents and their metabolic activity was assessed. To better understand how the position and morphology of cells can affect cell therapy responsiveness to alternating electric fields or currents, GBM results were compared to those from the semi-adherent brain tumour cell line, D425.ResultsContrary to previous findings, there was no significant difference between the GIN 31 and GCE 31 cells exposed to alternating electric fields or currents treated with or without NP compared to cells untreated and unstimulated. D425 cells exposed to alternating electric fields exhibited a pronounced metabolic increase (1.8-fold), while those exposed to alternating electric currents with or without ZnO had a reduced metabolism relative to the untreated control.ConclusionsThe initial hypothesis for the lack of effect of electrical stimulation on the adherent cells was that, due to only a single pair of electrodes being used, the proportion of cells that were in the correct orientation for electric field effects was limited. However, the dramatic shift in cell behaviour of the semi-adherent cells shows that cell morphology plays an important role in the responsiveness of cancer cells to AC electric fields. This study highlights the lack of understanding of the complex mechanisms by which electric fields exert effects on cancer cells. We propose that, for the therapy to be enhanced for patients, research should first focus on the underlying mechanisms of action, specifically on how individual cancer cell types respond to this therapy.

Superior energy storage capacity of polymer-based bilayer composites by introducing 2D ferroelectric micro-sheets

Dielectric polymer capacitors suffer from low discharged energy density and efficiency due to their low breakdown strength, small dielectric constant and large electric hysteresis. Herein, a synergistic enhancement strategy is proposed to significantly increase both breakdown strength and dielectric constant while suppressing hysteresis, through introducing 2-dimensional bismuth layer-structured Na0.5Bi4.5Ti4O15 micro-sheets and designing a unique bilayer structure. Excitingly, an ultra-high discharged energy density of 25.0 J cm−3 and a large efficiency of 81.2% are achieved in Na0.5Bi4.5Ti4O15-poly(vinylidene fluoride-co-hexafluoropropylene)/Na0.5Bi4.5Ti4O15-polyetherimide bilayer composites under a dramatically enhanced breakdown strength of 8283 kV cm−1. Finite element simulations along with experimental test results demonstrate that greatly improved breakdown strength is ascribed to uniform and horizontal alignments of Na0.5Bi4.5Ti4O15 sheets (~1–2 μm) in the matrix and interface effect of adjacent layers with large dielectric differences, which effectively inhibit electrical tree evolution and conduction loss. This work provides a strong foundation for developing high-performance polymer-based energy storage devices.

Temporal properties of transcutaneous direct current motor conduction block.

Direct current (DC) electrical block of peripheral nerve conduction shows promise for clinical applications to treat spasticity, pain, and cardiac arrhythmias. Most previous work has used invasive nerve cuffs. Here we investigate the potential of non-invasive transcutaneous direct current motor block (tDCB). &#xD;&#xD;In anesthetized rats, force output from the tibialis and peroneus muscles was measured in response to stimulation proximally on the sciatic nerve. DC blocking waveforms were delivered via a surface electrode placed distally on the skin over the common peroneal nerve. The efficacy of the block was observed as the reduction/abolition of muscle force. Experiments using this model were performed with two different electrode types. A range of DC amplitudes and durations was used to elucidate the temporal properties of block.&#xD;&#xD;Higher levels of DC resulted in a larger block percentage. The amount of time needed to induce block depended on the level of DC, with smaller amplitudes resulting in longer induction times. When block was applied for a longer period of time (120s), the block was sustained following DC delivery. This "recovery period" was longer for higher amplitudes of block. &#xD;&#xD;In addition to the block thresholds and temporal effects, two additional evaluations were made: In some animals the efficacy of tDCB to block tetanic muscle contractions was successfully verified. Finally, the effect of tDCB on nerve health was verified using a second distal electrode for comparison. &#xD;&#xD;In this study, tDCB has been shown to reversibly blocked action potentials in peripheral motor nerves. A lower amplitude applied for a longer duration could produce delayed complete block as well as delayed partial block. Also, a higher amplitude was associated with a longer recovery time. These temporal properties are important considerations for potential clinical applications.&#xD.

Dual Roles of PTSA in Electrical Conductivity of PEDOT:PTSA with Large Seebeck Coefficient

The electrical conduction mechanism of PEDOT:PTSA thermoelectric conversion material supported on PET fiber was investigated with varying PTSA concentrations. Raman analysis revealed that an increasing PTSA concentration promoted transformation from a benzoid to a quinoid structure in PEDOT chains, reaching saturation in higher concentrations. All samples exhibited p-type behavior, with Seebeck coefficients ranging from 0.9 to 2.7 mV/K. The temperature dependence of electrical conductivity showed that conductivity and activation energy exhibited extreme values with increasing PTSA concentration, correlating with the saturation of quinoid structure transformation. This behavior suggests that PTSA serves dual roles: at lower concentrations, it enhances electrical conductivity through chemical doping, increasing carrier concentration and mobility via quinoid structure formation; at higher concentrations, excess PTSA induces carrier scattering without contributing to chemical doping, thereby reducing conductivity. These findings indicate that the thermoelectric properties of PEDOT:PTSA on PET fiber are governed by the balance between chemical doping effects and carrier scattering mechanisms, which are both influenced by PTSA concentration.

SCIENTOMETRIC ANALYSIS OF ELECTRICAL MODALITIES IN KNEE REHABILITATION (1983-2023)

Introduction: Electrical modalities represent a therapeutic modality employed in rehabilitation settings aimed at augmenting or facilitating the recovery of individuals afflicted with diverse neurological or musculoskeletal diseases. This intervention requires the application of electrical currents to targeted regions of the body, typically administered via electrodes positioned on the skin, with the intent of eliciting physiological responses and fostering therapeutic benefits. An examination of its trajectory through various analytical lenses, such as bibliometrics, underscores the imperative of comprehending its global ramifications. In recent years, scientometric investigations have emerged as interactive methodologies for evaluating the performance of specific domains of inquiry. These inquiries yield interactive visualizations and figures, affording insights into multifaceted aspects of information. Moreover, scientometric research equips scholars with tools to synthesize evidence gleaned from literature amassed in scientific repositories. Method: The inception of the Web of Science (WOS) database in 1983 has facilitated the aggregation of scientific publications, revealing a discernible uptrend in research pertaining to electrical modalities for knee rehabilitation from 1983 to 2023. This study endeavors to delineate the contemporary landscape of research surrounding electrical modalities for knee rehabilitation through scientometric analysis. Result: The progression of scientific publications in this domain demonstrates a consistent upward trajectory. While the volume of publications was inadequate in 1983, comprising merely one paper, this figure surged dramatically, reaching 80 publications by 2019. Furthermore, these publications collectively garnered a substantial citation count of 19,660, precipitating the identification of 27 co-citation clusters through cluster analysis. Conclusion: The realm of electrical modalities for knee rehabilitation emerges as a promising frontier for scholarly inquiry. The escalating trajectory of research publications, coupled with the considerable citation impact, underscores the significance and prospective advancements within this sphere.

Observation of Real-Time Spin-Orbit Torque Driven Dynamics in Antiferromagnetic Thin Film.

In the burgeoning field of spintronics, antiferromagnetic materials (AFMs) are attracting significant attention for their potential to enable ultra-fast, energy-efficient devices. Thin films of AFMs are particularly promising for practical applications due to their compatibility with spin-orbit torque (SOT) mechanisms. However, studying these thin films presents challenges, primarily due to the weak signals they produce and the rapid dynamics driven by SOT, that are too fast for conventional electric transport or microwave techniques to capture. The time-resolved magneto-optical Kerr effect (TR-MOKE) has been a successful tool for probing antiferromagnetic dynamics in bulk materials, thanks to its sub-picosecond (sub-ps) time resolution. Yet, its application to nanometer-scale thin films has been limited by the difficulty of detecting weak signals in such small volumes. In this study, the first successful observation of antiferromagnetic dynamics are presented in nanometer-thick orthoferrite films using the pump-probe technique to detect TR-MOKE signal. This paper report an exceptionally low damping constant of 1.5 × 10-4 and confirms the AFM magnonic nature of these dynamics through angular-dependent measurements. Furthermore, it is observed that electrical currents can potentially modulate these dynamics via SOT. Thefindings lay the groundwork for developing tunable, energy-efficient spintronic devices, paving the way for advancements in next-generation spintronic applications.

Investigation into the Prediction of the Service Life of the Electrical Contacting of a Wheel Hub Drive

This article examines contacting by means of ultrasonic welding between a cast aluminum winding and a copper conductor of a wheel hub drive for a passenger car. The effect of thermal stress on the formation and growth of intermetallic phases (IMC) in the contact is analyzed. By using microscopy, the growth constant under the specific load conditions can be identified with the help of the parabolic time law and offer a possibility for predicting the service life of the corresponding contacts. As a result, it can be stated that the increase in electrical resistance of the present contact at load temperatures of 120 °C, 150 °C, and 180 °C does not reach a critical value. The growth rates of the IMC also show no critical tendencies at the usual operating temperatures (120 °C and 150 °C, e.g., at 150 °C = 4.59 × 10−7 μm2/s). The activation energy calculated using the Arrhenius plot of 155 kJ/mol (1.61 eV) can be classified as high in comparison to similar studies. In addition, it was found that future investigations of the IMC growth of corresponding electrical contacts should rather be carried out with electric current. The 180 °C sample series were carried out in the oven and with electric current; the samples in the oven did not show clear IMC, while the samples exposed to electric current already showed IMC under the microscope.

Logarithmic Separable Solutions of Force-Free Magnetic Fields in Plane-Parallel and Axial Symmetry

This work introduces a systematic method for identifying analytical and semi-analytical solutions of force-free magnetic fields with plane-parallel and axial symmetry. The method of separation of variables is used, allowing the transformation of the non-linear partial differential equation, corresponding to force-free magnetic fields, to a system of decoupled ordinary differential equations, which nevertheless, are in general non-linear. It is then shown that such solutions are feasible for configurations where the electric current has a logarithmic dependence to the magnetic field flux. The properties of the magnetic fields are studied for a variety of physical parameters, through solution of the systems of the ordinary differential equations for various values of the parameters. It is demonstrated that this new logarithmic family of solutions has properties that are highly distinct from the known linear and non-linear equations, as it allows for bounded solutions of magnetic fields, for periodic solutions and for solutions that extend to infinity. Possible applications to astrophysical fields and plasmas are discussed as well as their use in numerical studies, and the overall enrichment of our understanding of force-free configurations.