Search Results (661)

The self-directed channel (SDC) class of memristors employs a multilayer architecture that is designed to enable robust Ag ion conduction, long cycling lifetime, and thermal stability. While several layers contribute to mechanical and chemical reliability, two layers primarily govern the electrical behavior: the amorphous Ge–chalcogenide active layer that is adjacent to the bottom electrode and the overlying metal–chalcogenide source layer. In this work, we investigate how the variation in the chalcogen species in these two layers influences switching characteristics in the pre-write regime, both in the pristine state and after a write/erase cycle, as well as the conduction behavior at room temperature. The devices were fabricated using Ge-rich chalcogenides containing O, S, Se, or Te, combined with SnS, SnSe, or Ag₂Se metal–chalcogenide layers. The DC current-voltage measurements were analyzed using the standard linearization approaches to examine whether the transport behavior in the pre-write regime exhibits characteristics that are associated with Ohmic, Schottky, Poole–Frenkel, or space charge limited conduction. These measurements specifically probe the pre-write region of the I-V curve, where early ionic redistribution and structural rearrangement precede the abrupt formation of the conductive channels responsible for the resistive switching. The results show that the chalcogen composition strongly affects the threshold voltage, the resistance window, and the onset of field-enhanced transport, reflecting the differences in ionic distribution and channel formation dynamics. The results indicate that transport evolves with a bias and a compliance current, transitioning between regimes that are influenced by the interface injection and bulk-limited conduction, depending on the material stack. These findings clarify the role of chalcogen chemistry in governing the SDC switching behavior and provide guidance for the material selection in application-specific device design. Full article

Urban geophysical exploration faces significant hurdles due to strong electromagnetic interference and limited operational space, which restrict the efficiency and depth of traditional Electrical Resistivity Tomography (ERT). To overcome these limitations, this paper presents a novel ERT measurement and control system based on the Frequency Division Multiplexing (FDM) principle. Unlike conventional time-domain methods, this instrument synchronously transmits three independent AC signals at distinct frequencies. The acquisition station utilizes Fast Fourier Transform (FFT) to isolate specific frequency responses, enabling the simultaneous retrieval of apparent resistivity data for three different electrode spacings from a single transmission. The system architecture integrates low-power STM32 microcontrollers with an Android-based control terminal via Bluetooth, Wi-Fi, and NB-IoT technologies. This wireless design supports real-time current monitoring and cloud-based data synchronization. Experimental results demonstrate that the FDM operating mode significantly enhances data acquisition efficiency and anti-interference capability through frequency-domain separation. Controlled indoor and preliminary field tests indicate that FDM mode substantially improves acquisition efficiency through concurrent multi-channel measurement while effectively resolving target signals from noise. This study demonstrates the system’s technical feasibility and provides a practical foundation for future geophysical detection in time-constrained urban environments. Full article

Electrochemical vibration sensors offer high sensitivity, low mechanical noise, and superior low-frequency performance, making them attractive for applications such as seismic detection and underwater acoustic sensing. However, existing electrochemical seismometers, angular accelerometers, and vector hydrophones primarily focus on sensitivity and noise, while sensor linearity—especially across wide frequency ranges—remains insufficiently investigated. In practice, linearity degradation frequently occurs at low and high frequencies due to diffusion limitations of electroactive species in the electrolyte. In this study, the linearity mechanism of electrochemical vibration sensors is analyzed, and two key structural parameters affecting linearity are identified: one is the anode–cathode spacing and the other is the effective cathode length. To improve linearity, an electrochemical sensing electrode incorporating an ultra-narrow insulating ring and a tapered micro-orifice is proposed. Finite element simulations are performed to evaluate the effects of electrode spacing, orifice geometry and excitation frequency. The sensor is fabricated using MEMS fabrication technology and experimentally characterized. Results show a peak sensitivity of 1242 V/(m/s) and excellent linearity within an input velocity range of 0.0002–0.012 m/s at 5 Hz, 10 Hz, 40 Hz and 100 Hz, with correlation coefficients exceeding 0.998. The proposed design provides an effective approach for linearity enhancement in electrochemical vibration sensors. Full article

A capacitor modeled as a parallel combination of a resistance ($\mathrm{R}$) and a capacitance ($\mathrm{C}$) exhibits three distinct operating regimes when both parameters depend on the applied voltage (V): a positive-capacitance regime ($\mathrm{d}\mathrm{R}/\mathrm{R}>\mathrm{d}\mathrm{V}/\mathrm{V}$), an Ohmic regime ($\mathrm{d}\mathrm{R}/\mathrm{R}=\mathrm{d}\mathrm{V}/\mathrm{V}$), and a negative-capacitance regime ($\mathrm{d}\mathrm{R}/\mathrm{R}<\mathrm{d}\mathrm{V}/\mathrm{V}$). In the limit ($\mathrm{R}\to \mathrm{\infty }$), the device behaves as a conventional permittivity-based capacitor, whereas in the limit ($\mathrm{R}\to 0$), negative capacitance emerges due to nonlinear current–voltage characteristics. To verify this mechanism, we fabricated nanometer-spaced two-electrode structures using multi-walled carbon nanotubes (MWCNTs) and Si crystals. The measurements confirmed negative capacitance consistent with theoretical predictions. Unlike ferroelectric negative capacitance, the effect demonstrated here arises solely from the nonlinear I–V characteristics at the electrode interfaces, without involving any ferroelectric polarization dynamics. This negative capacitance can be interpreted as an equivalent inductance, enabling a two-dimensional tunable reactance element (TDTRE) that operates without electromagnetic coupling and is compatible with conventional IC technologies. Full article

Mining tailings are waste generated continuously in large quantities and have accumulated over time, posing significant environmental challenges. This study evaluates the influence of low (MinPC) and high (MaxPC) current densities on the recovery of elements from untreated mining tailings obtained from SCM Paicaví by electrodeposition. To define both conditions, tailings were placed in containers with electrodes spaced 3–18 cm apart, and controlled currents of 1–100 mA were applied. Although MaxPC electrodes recovered a greater mass of material (1.51 g) than MinPC (0.22 g), the latter achieved higher enrichment of elements such as Ni and Mn. Under MinPC conditions, Ni exhibited the highest recovery, enrichment (19.3), and selectivity (4.8), whereas under MaxPC, the enrichment and selectivity decreased to 9.6 and 2.0, respectively. Elemental analyses (XRF, AAS, ICP-MS), together with mineralogical characterization (XRD, FT-IR, and SEM-EDS), identified quartz, pyrite, and chlorite as the main phases associated with the recovered elements. Overall, the results demonstrate that direct electrodeposition enables selective metal recovery from untreated tailings without pretreatment, chemical reagents, or additional water consumption, providing a novel and environmentally sustainable route for tailings valorization. Full article

Electrochemotherapy is a minimally invasive treatment based on the principle of reversible electroporation of target cells in pathologic tissues in order to increase the local effect of chemotherapeutic agents. The mechanism of action relies on temporarily increasing cell permeability to increase the uptake of cytotoxic drugs in the intracellular space. Originally developed for the treatment of cutaneous malignancies, electrochemotherapy has significantly evolved over the past few decades, thanks to advancements in electrode design and image guidance, finding fertile ground in musculoskeletal oncological pathologies, such as bone and soft tissue tumors and different kinds of vascular malformations. Moreover, initial experiences have reported on the treatment of other soft tissue tumors such as desmoid fibromatosis. The aim of this review is to summarize the literature on the role of electrochemotherapy across a variety of musculoskeletal conditions, starting from established oncologic indications, such as metastatic bone or soft tissue tumors, to emerging evidence on primary musculoskeletal pathology, with particular attention paid to the results of the leading studies relating to the efficacy, complications, and recurrence rate. Full article

The influence of different voltage measurement and current injection configurations on the quality of image reconstruction in electrical impedance tomography (EIT) was investigated using numerical simulations. Adjacent and opposing techniques were systematically used to examine their effectiveness in voltage acquisition and current delivery. The simulation model employed 16 equally spaced electrodes arranged around a circular domain, with an injected alternating current of 1 mA at a frequency of 50 kHz. A circular object with a conductivity of 0.9 units was sequentially positioned at five distinct locations within the imaging domain, each spaced 0.05 units apart. The reconstructed images were analyzed for positional accuracy and contrast resolution. While each configuration offers specific advantages, they exhibit inherent limitations depending on the application. The results of this study enable the understanding of the trade-offs involved in selecting electrode drive and measurement strategies for optimizing image quality in EIT systems. Full article

This paper presents a comprehensive investigation into the synthesis, morphological characteristics, electrical conductivity, dielectric behavior, and electrocatalytic activity of perovskite-structured iron manganite (FeMnO₃), with a specific focus on its performance in the hydrogen evolution reaction (HER). FeMnO₃(FMO) nanoparticles (NPs) were synthesized using a sol–gel-type Pechini method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (FESEM-EDS). XRD analysis confirmed the formation of a crystalline structure with cubic symmetry assigned to the Ia-3 space group, with an average crystallite size of 52.47 nm. FESEM images revealed a relatively uniform morphology with an average particle diameter of 55.84 nm. The redox and oxidation states of Fe and Mn can be studied by temperature-programmed oxidation (TPO-O₂) in order to understand oxygen uptake and metal oxidation processes occurring within the FMO lattice. The dielectric constant, dielectric loss, electric modulus and electrical conductivity were calculated as a function of frequency and temperature using a Novocontrol Alpha-A broadband dielectric spectrometer (Novocontrol system) coupled with the LCR-800 precision meter. The dielectric data reveal that the FMO has semiconducting behavior with dominant charge- or ionic-relaxation processes. The electrocatalytic activity toward the HER was evaluated using linear sweep voltammetry (LSV), with the working electrode modified by an FMO catalyst ink. The material exhibited significant catalytic activity within the HER potential range, and an increase in the number of cycles led to stabilized current and enhanced hydrogen evolution. These results highlight the stability of FeMnO₃ for hydrogen generation. Full article

The photovoltaic industry generates a substantial amount of high-purity waste silicon powder during the diamond-wire saw cutting process, which can serve as an environmentally friendly and cost-effective resource for lithium-ion battery recycling. However, its commercial application is hindered by the surface attachment of silicon dioxide, organic substances, metal impurities, as well as its intrinsic drawbacks such as significant volume expansion (>300%) during lithium (de)intercalation and low electronic conductivity. To address these issues, this study first purifies the waste silicon powder and then designs the structure of the composites. Using a simple ball-milling combined with sol-gel method, a core-shell composite material with a carbon-coated two-dimensional conductive network (FVW-Si/G₅₀₀@C) was synthesized. The two-dimensional conductive network provides sufficient space to accommodate the volume expansion of silicon, while the mesoporous structure on the carbon shell offers a fast transport pathway for Li⁺, thereby enhancing the electrode kinetics. The prepared FVW-Si/G₅₀₀@C electrode maintained a high reversible capacity of 951.8 mAh g⁻¹ after 100 cycles at a current density of 0.2 A g⁻¹. Even at a high current density of 1 A g⁻¹, it retained a reversible capacity of 230.4 mAh g⁻¹. The results indicated that the synergistic effect between graphite sheets and the mesoporous carbon shell significantly improved the rate performance and cycling stability of the FVW-Si/G₅₀₀@C electrode. This study provided a theoretical foundation for the scalable, green, and high-value utilization of waste silicon powder in the photovoltaic industry and offered technical support for sustainable energy development. Full article

This study investigates the development of a predictive model in simulations for assessing steel corrosion in determining corrosion-affected zones in reinforced concrete. A series of reinforced concrete cubes with varying degrees of corrosion were tested using a four-probe Wenner configuration. The experimental data showed a clear inverse relationship between ER and steel mass loss, with a strong negative correlation, highlighting the potential of ER as a corrosion indicator. A third-degree polynomial model was developed to predict the diameter of the corrosion-affected region based on steel mass loss and concrete cover, achieving high predictive accuracy. This model was validated using numerical simulation conducted in COMSOL Multiphysics, which replicated the experimental setup under steady-state conditions. Parametric studies further examined the effects of electrical conductivity ($\sigma$) and electrode spacing on the simulated results. The findings confirm that while $\sigma$ has a moderate impact, electrode spacing significantly influences the measured ER values. The study underscores the importance of incorporating variable parameters into simulation models to improve the accuracy and field applicability of ER-based corrosion assessments. Furthermore, the simulation framework developed in this study demonstrates how numerical modeling can enhance the interpretive value of ER measurements, supporting the advancement of non-destructive testing techniques aimed at improving corrosion monitoring and maintenance strategies. Full article

V₂CT_x MXene is a promising anode material for lithium-ion batteries due to its high electrical conductivity and abundant active sites. However, the spatial environment within its layers restricts the function of its energy storage electrode. Herein, V₂CT_x MXene was synthesized via an NH₄F–HCl-assisted hydrothermal etching method, followed by electrochemical pre-intercalation of Mn²⁺ using a three-electrode system. Structural characterizations confirm that Mn²⁺ pre-intercalation effectively modulates the interlayer environment, reduces surface F terminations, and maintains a stable layered structure. Electrochemical measurements demonstrate that the Mn²⁺-intercalated V₂CT_x MXene delivers an enhanced reversible capacity of 313.6 mAh·g⁻¹ after 200 cycles, outperforming pristine V₂CT_x MXene. The improved rate capability and reduced charge transfer resistance indicate accelerated ion/electron transport kinetics. This study provides an effective interlayer engineering strategy for improving MXene-based lithium-ion storage performance. Full article

Peripheral nerve regeneration is most rapid during the early post-injury period but gradually slows over time, often limiting functional recovery. Electrical stimulation (ES) delivered via percutaneous needle electrodes has been shown to modulate the local neural microenvironment and promote axonal regeneration; however, the optimal temporal window and duration of stimulation remain unclear. This study aimed to evaluate the time-dependent effects of needle-based ES on peripheral nerve regeneration in a rat model of sciatic nerve transection, using a well-established silicone nerve conduit as a stable and reproducible non-biodegradable repair model. Female Sprague–Dawley rats underwent sciatic nerve transection and repair. Postoperatively (PO), animals were randomly assigned to control (C) needle insertion or needle-based ES groups, receiving stimulation for either 3 weeks (C-3W-PO and ES-3W-PO, respectively) or 7 weeks (C-7W-PO and ES-7W-PO, respectively). Functional recovery was evaluated using cold plate latency and rotarod performance tests. Electrophysiological assessments included measurements of nerve conduction velocity (NCV), compound muscle action potential amplitude, and muscle action potential (MAP) area. Histomorphometric analysis of regenerated nerve tissue quantified total nerve cross-sectional area, endoneurial space, axon number, and axon density. Retrograde labeling with fluoro-gold (FG) was used to quantify reinnervated motor neurons. Immunohistochemical analyses of calcitonin gene-related peptide (CGRP) and macrophage-associated markers were conducted to assess sensory neuropeptide expression and immune cell infiltration within the regenerated nerve. ES significantly improved both sensory and motor recovery in a duration-dependent manner. Behavioral data showed increased cold pain thresholds and improved motor coordination in ES groups, with the most pronounced functional gains observed in the ES-7W-PO group. Electrophysiological measures revealed higher NCV, amplitude, and MAP area in ES-treated animals, with the most pronounced improvements at 7 weeks. Morphologically, ES enhanced nerve regeneration, as evidenced by increased total and endoneurial areas, axonal counts, and axon density. FG-labeled neuron counts were significantly elevated in ES groups, indicating enhanced motor reinnervation. At 3 weeks, ES induced higher CGRP expression and macrophage density, suggesting transient activation of sensory-associated and pro-regenerative immune responses during the early post-injury phase. These findings demonstrate that ES accelerates peripheral nerve repair in rats and that sustained stimulation across the early regenerative window yields superior structural and functional outcomes. Full article

In this work, indanone derivatives with a triphenylamine core structure (IND-1, IND-2, and IND-3) were studied as prospective electrodes. The indanones were synthesized and characterized for optimal deposition as charge-modulating electrodes. The structural arrangement of compound IND-3 was established, and the structure crystallized in a P2₁/c monoclinic space group. The electrodes were evaluated for reflectance and band gaps of direct and indirect transitions. Indanones show optical band gap values in the range of 2.46 and 2.86 eV. These values were compared with those obtained theoretically by means of DFT, from which the HOMO and LUMO molecular orbitals were also calculated. To evaluate the indanone response, photoactive devices with indanone-derivative electrodes and copper phthalocyanine as a photoactive electrode were fabricated. Cyclic voltammetry (CV) was conducted using a two-electrode arrangement, within a potential range of −0.1 to 1 V, a step of 10 mV, and a scan rate of 0.1 V/s. The transported current is around 10⁻¹–10⁴ µA, and CV revealed distinct behaviors related to each kind of indanone. Finally, the electrodes were removed from each device and analyzed by IR spectroscopy, demonstrating that they did not undergo degradation during operation and can continue to be used for the manufacture of other devices. Full article

To address the stringent insulation safety requirements of modern high-voltage transformers, accurately characterizing the transient electric field is critical. However, a significant problem remains: current engineering models typically rely on static capacitive distributions, failing to capture the dynamic electric field distortion induced by rapid space charge injection under lightning impulses. Therefore, a non-contact spatial electric field measurement method based on the optical Kerr effect was employed to analyze the influence of electrode material, voltage amplitude, and wavefront time. Unlike traditional simulation models that often assume constant mobility and focus solely on the shielding effect, this study reveals a non-monotonic electric field evolution driven by a ‘Static-Dynamic’ mode transition. The proposed model highlights two critical breakthroughs: (1) Mechanism Innovation: It experimentally verifies that charge injection is governed by the ion charge-to-mass ratio rather than just the work function, leading to a newly identified field enhancement phase during the wavefront that overcomes the limitations of capacitive models that underestimate transient stress. (2) Parameter Quantification: Precise spatiotemporal thresholds are established—negative charges traverse the gap within ~200 ns, while positive charges require ~10 μs to reach equilibrium. These findings provide experimentally calibrated time constants for simulation correction and offer new criteria for optimizing electrode materials in UHV transformers to mitigate transient field distortion. Full article

The generation of atmospheric pressure nonequilibrium plasma using electrical discharges is an active area of research due to its significance in a wide spectrum of applications including medicine, combustion, and manufacturing. In our attempt to create a helium plasma jet in a pin-plane discharge with a constant current source, we observed self-pulsating behavior. We present the results of the electrical, optical, and spectroscopic measurements carried out to characterize the discharge. The duration of the discharge is a few tens of nanoseconds, and the repetition rate is in the few tens of kHz. The effect of the gap distance and gas flow is discussed. The effective capacitance formed by the space charge in the discharge region plays an important role in determining the pulsing frequency. The results of voltage swing, current pulse, and light emission are also discussed. Such self-pulsating discharges can be used to produce helium plasmas under ambient conditions in applications such as plasma medicine. Full article