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Integrating both electrical and light-modulated multi-type neuromorphic functions in a single synaptic memristive device holds the most potential for realizing next-generation neuromorphic systems, but is still challenging yet achievable. Herein, a simple bi-terminal optoelectronic synaptic memristor is newly proposed based on kesterite Cu2ZnSnS4, exhibiting stable nonvolatile resistive switching with excellent spatial uniformity and unique optoelectronic synaptic behaviors. The device demonstrates not only low switching voltage (−0.39 ± 0.08 V), concentrated Set/Reset voltage distribution (<0.08/0.15 V), and long retention time (>104 s) but also continuously modulable conductance by both electric (different width/interval/amplitude) and light (470–808 nm with different intensity) stimulus. These advantages make the device good electrically and optically simulated synaptic functions, including excitatory and inhibitory, paired-pulsed facilitation, short-/long-term plasticity, spike-timing-dependent plasticity, and "memory-forgetting" behavior. Significantly, decimal arithmetic calculation (addition, subtraction, and commutative law) is realized based on the linear conductance regulation, and high precision pattern recognition (>88%) is well achieved with an artificial neural network constructed by 5 × 5 × 4 memristor array. Predictably, such kesterite-based optoelectronic memristors can greatly open the possibility of realizing multi-functional neuromorphic systems. [ABSTRACT FROM AUTHOR]

Percutaneous ventricular assist devices (pVADs) incorporated with admittance electrodes have been validated in animal studies for accurate instantaneous volumetric measurements. Since miniaturization of the pVAD profile is a priority to reduce vascular complications in patients, our study aimed to validate admittance measurements using three electrodes instead of the standard four. Complex admittance was measured between an electrode pair and a pVAD metallic blood-intake tip, both with finite element analysis and on the benchtop. The catheter and electrode arrays were first simulated inside prolate ellipsoid models of the left ventricle (LV) demonstrating current flow throughout all parts of the LV as well as minimal influence of off-center catheter placement in the recorded signal. Admittance measurements were validated in 3D-printed models of healthy and dilated hearts (100–400 mL end-diastolic volumes). Minimal interference between a pVAD motor and the current signal of our admittance system was demonstrated. A modified Wei's equation focused on three electrodes was developed to be compatible with reduced profile pVADs occurring clinically, incorporated with admittance electrodes and wires. The modified equation was compared against Wei's original equation showing improved accuracy of calculated volumes. Reducing electrode footprint can simplify the incorporation of Admittance technology on any pVAD, allowing for instantaneous recognition of native heart recovery and assistance with pVAD weaning. [ABSTRACT FROM AUTHOR]

Using the AC electric field to induce the orientation of nonlinear conductive fillers in composites is an effective solution for alleviating electric field distortion in power modules. However, the mechanism by which the electric field affects the filler dynamic characteristics and the composites' electrical properties remains unclear. In this paper, the correlation between the microscopic dynamic processes of fillers and the macroscopic current amplitude was analyzed. The results show that the current increases rapidly (0 ∼ 173 s) and then slowly (173 ∼ 869 s) at 600 V mm−1, influenced by the rotation and attraction processes of the fillers. This demonstrates that the orientation stops at about 869 s and the filler orientation state is a key factor in determining the dielectric properties. Secondly, the global orientation evaluation index D for the filler network was proposed, which can also derive the minimum time and energy loss required for preparation. Finally, the impact of different filler orientations on the composites' conductivity was investigated. In the low electric field stress region, with the average carrier jump distance decreasing from 150.23 to 109.71 nm as the D increases from −0.93 to −0.05. On this basis, materials with nonlinear conductivity gradient distribution can be easily prepared. Before optimization, the electric field stress of the power module at the triple point was 35.79 kV. This composite can reduce the value to 15.42 kV, a decrease of 56.9%, while maintaining good electric field uniformity. [ABSTRACT FROM AUTHOR]

Wide bandgap orthorhombic polymorph of gallium oxide (κ‐Ga2O3) possessing a high spontaneous polarization grown on wurtzite‐type semiconducting substrates is considered to create a high mobility electron channel suitable for applications. Such κ‐Ga2O3 layers are composed of hexagon microprisms whose properties affect the lateral electric conductance. In this work, the structure and recombination properties of extended defects in individual “suspended” thin microprisms are investigated with transmission and scanning electron microscopy techniques (STEM, HR‐TEM) including cathodoluminescence (CL‐SEM). It is established that the microprism is composed of six equisized orthorhombic domains bounded by twin domain boundaries (TDBs) along the directions <110>. Twin domain contains a parallel array of antiphase boundaries (APB) of a high density stretched in the [010] direction. APBs possess steps or interruption and can form double oppositely shifted spatially separated layers (APB dipoles). TDBs on majority of their length are incoherent and serve as the border for the APB terminations. Panchromatic CL maps reveal either enhanced or reduced intensity of APB without noticeable spectral changes. CL intensity enhancement is proposed to be due to enhanced electron–hole generation caused by excess scattering of primary electron beam by APBs in thin films while, in fact, APB exhibits enhanced nonradiative recombination activity. [ABSTRACT FROM AUTHOR]

Using computer simulations, we have studied the percolation and the electrical conductance of two-dimensional, random percolating networks of curved, zero-width metallic nanowires. We mimicked the curved nanowires using circular arcs. The percolation threshold decreased as the aspect ratio of the arcs increased. Comparison with published data on the percolation threshold of symmetric quadratic Bézier curves suggests that when the percolation of slightly curved wires is simulated, the particular choice of curve to mimic the shape of real-world wires is of little importance. Considering the electrical properties, we took into account both the nanowire resistance per unit length and the junction (nanowire/nanowire contact) resistance. Using mean-field approximation (MFA), we derived the total electrical conductance of nanowire-based networks as a function of their geometrical and physical parameters. The MFA predictions have been confirmed by our Monte Carlo numerical simulations. For our random homogeneous and isotropic systems of conductive curved wires, the electric conductance decreased as the wire shape changed from a stick to a ring when the wire length remained fixed. [ABSTRACT FROM AUTHOR]

Dielectric permittivity, electrical conductivity, and photoluminescence properties of high-density polyethylene with the additive of CaGa2S4:Eu+2 are studied. It was shown that dielectric permittivity and electric conductance increase with increasing filler concentration at all temperatures. In this case, conductivity has a hopping mechanism described by the Josher theory. The corresponding exponent parameter and activation energy slightly decrease with increasing filler concentration. The experimental data of dielectric permittivity are compared with the Maxwell–Garnett theory. It is also shown that the position of maximum of photoluminescence does not change with an increase in the concentration of Eu2+ ions and equals to about 550 nm. In this case, its intensity is maximal at the concentration of the filler is 5 mol. %. [ABSTRACT FROM AUTHOR]

In this review amino acid-surfactant interactions mainly in aqueous solution has been explained. Amino acids and surfactants interactions are important in many studies because of their enhanced effectiveness in both living and non-living worlds. As physicochemical properties are additive, the study of interactions between amino acids and surfactants offer insights into how proteins unfold and denaturate in various media, which further alters with a change in physiological parameters like pH, additives, no of carbon in the chain and temperature. Keeping this in mind, in this review main emphasis has been on conductometric, volumetric and computational studies for detailed exploration of solute–solvent interactions of amino acids and surfactants in aqueous medium and effect of temperature on these interactions. Conductance data has been used to find the critical micelle concentration (CMC) of the surfactant. Using CMC, standard Gibbs free energy of micellization, ( Δ G m 0 ), enthalpy of micellization, ( Δ H m 0 ), entropy of micellization, ( Δ S m 0 ) have been determined for surfactant in presence of amino acids. In volumetric investigation, density data has been utilized to find apparent molar volumes of amino acids, (ϕv) and partial molar volume (ϕ0v), which is used to find soute-solvent interaction. In computational studies the effects of carbon tail length on CMC and aggregation number, (Ag) for the pure Gemini surfactant system were examined and these data were compared with experimental results to find the agreement between different methods. [ABSTRACT FROM AUTHOR]

The experimentally obtained material microstructure can be used to calculate a material's properties and identify microstructure–property relationships. The key procedure to enable this is to interpret the observed microstructure accurately. This work reports on a newly developed computational method to serve such a purpose. The method is based on cubic spline interpolation and a simple search algorithm. Parameterisation was accomplished via the comparison between its preliminary statistical results and the information in a phase diagram. The method was applied to analyse the quenched microstructure of multicomponent and multiphase metallic-oxide materials. The importance of adequate parameterisation is demonstrated. The results provide a good explanation for the experimentally measured electric conductance behaviour. Further application of the method to the deformation of materials is discussed. The algorithms are directly available for the analysis of the three-dimensional microstructure of materials. [ABSTRACT FROM AUTHOR]

Memristor crossbar arrays are expected to achieve highly energy-efficient neuromorphic computing via implementing parallel vector–matrix multiplication (VMM) in situ. The similarities between memristors and neural synapses offer opportunities for realizing hardware-based brain-inspired computing, such as spike neural networks. However, the nonlinear I–V characteristics of the memristors limit the implementation of parallel VMM on passive memristor crossbar arrays. In our work, we propose to utilize differential conductance as a synaptic weight to implement linear VMM operations on a passive memristor array in parallel. We fabricated a TiO2/HfO2 memristor crossbar array, in which differential-conductance-based synaptic weight exhibits plasticity, nonvolatility, multi-states, and tunable ON/OFF ratio. The noise-dependent accuracy performance of VMM operations based on the proposed approach was evaluated, offering an optimization guideline. Furthermore, we demonstrated a spike neural network circuit capable of processing small spiking signals through the differential-conductance-based synapses. The experimental results showcase effective space-coded and time-coded spike pattern recognition. Importantly, our work opens up new possibilities for the development of passive memristor arrays, leading to increased energy and area efficiency in brain-inspired chips. [ABSTRACT FROM AUTHOR]

The method and equipment of conductometry in a pulsed electric field of increasing intensity were used to measure the specific electrical conductivity of various types of natural waters (artesian, river, spring). The potential of using the electrical conductivity of natural water in the function of the field strength as an integral characteristic of natural mineralization with conductive impurities (including those of anthropogenic origin) was demonstrated using the waters of the eastern part of the Kama Basin District. The pollution of some natural waters in the basin area was studied and assessed. Some aspects of the application of pulsed conductometry in an electric field with increasing strength were considered as applied to studying the seasonal, environmental, and other parameters of natural waters. [ABSTRACT FROM AUTHOR]

Brain‐inspired electronics with multimodal signal processing have been investigated as the next‐generation semiconductor platforms owing to the limitations of von Neumann architecture, which limits data processing and energy consumption efficiencies. This study demonstrates the molecular reconfiguration of plasticity of artificial synaptic devices with tunable electric conductance based on molecular dynamics at the channel surfaces for realizing chemical multimodality. Carrier transport dynamics are adjusted using the density of trapped carriers for the molecular adsorption of HS in the MoSe2 channel, and the results are consistent with the molecular simulations. In molecular dynamics‐controlled devices, enhanced hysteresis enables the engineering of artificial neuroplasticity, mimicking the neurotransmitter release of biological synapses. Owing to the molecular reconfigurability of MoSe2 devices, the synaptic weights of excitatory and inhibitory synapse modes are significantly enhanced. Thus, this study can potentially contribute to the creation of the next generation of multimodal interfaces and artificial intelligence hardware realization. [ABSTRACT FROM AUTHOR]

This study proposes a current-mode KHN universal filter design that can perform three standard functions simultaneously: low-pass, high-pass, and band-pass. The circuit is built around a multiple-output operation transconductance amplifier (MO-OTA), which allows for electronically adjustable pole frequency and quality factor by modifying input bias currents (IB). The circuit layout is straightforward, with two MO-OTAs and two grounded capacitors, eliminating the need for external resistors and depending entirely on grounded components. Because of its simplicity, the circuit is suited for use in a tiny, efficient design. The proposed circuit's operation was validated using LT-Spice simulations, and the results were in line with theoretical expectations. The circuit used around 298µW of power at ±0.2V power supply voltages. These results demonstrate the circuit's potential for low-power applications, which are crucial in many modern electronic devices. The suggested current-mode KHN universal filter offers a viable option for combining various filter functions in a single circuit with customizable parameters. Its simplicity, efficiency, and performance qualities make it a feasible choice for incorporation into a variety of electronic systems, allowing for more filter design freedom [ABSTRACT FROM AUTHOR]

This article examines the potential overestimation of the importance of small-scale electric fields in the polar ionosphere. The author suggests that previous studies may have exaggerated the impact of these electric field variations on energy dissipation through Joule heating. The article emphasizes the need for future multispacecraft measurements to accurately determine the dimensions and lifetimes of these fluctuations. It also highlights the limitations of current satellite configurations in detecting and measuring these electric field spikes. The text concludes by stating that further research is needed to accurately assess the significance of small-scale electric field fluctuations in Joule heating. [Extracted from the article]

In the fabrication of 3D p-n junctions, doping or surface modification caused by ion injection changes the electrical properties and crystal structure of the semiconductor. In addition, as the size of the semiconductor device decreases, various quantum effects are gradually appearing in them. This shows that the scope of application of classical device theory is now limited. In recent years, twodimensional (2D) materials with amazing atomically fine properties have attracted great interest. The electrostatic field properties of some 2D p-n junctions, such as WS2, MoS2, MoSe2, WSe2, and black phosphorus (BP), open the door to new possibilities for semiconductors. Changes in the diffusion capacitances and differential conductance's of 2D p-n junctions under the influence of an microwave field, and the diffusion capacitances and differential conductance's of 2D and 3D p-n junctions the change of conductivities under the influence of microwave field is compared. [ABSTRACT FROM AUTHOR]

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This article explores the use of lichens in biomonitoring to assess heavy metal concentrations, environmental factors, and lichen diversity in Bengaluru, Karnataka, India. Lichens are cost-effective options for biomonitoring due to their unique characteristics. The study examined heavy metal concentrations, acidity, and electrical conductance in different tree species across six locations. The findings revealed a correlation between acidity levels and lichen species in all tree species studied. Lichen diversity was lower in areas with heavy traffic and industrial activity. The article emphasizes the importance of considering abiotic factors and conducting chemical analysis in environmental pollution studies. The analysis of tree bark acidity, conductivity, and buffering capacity in different locations revealed significant variations. Bark pH values were lower in polluted areas with heavy traffic and higher air pollution levels. Pollution can impact the conductivity and buffering capacity of tree bark through the deposition of contaminants and chemical reactions. Furthermore, the concentration of heavy metals in lichens can indicate pollution levels in the environment, with areas near industrial and heavily trafficked areas showing higher levels. The study concludes that Station 2 and Station 4 are the most polluted locations, while Station 3 and Station 6 have lower pollution levels due to favorable conditions and green spaces. [Extracted from the article]

We theoretically study a magnon–polariton in a dynamical inductor consisting of a coil and a bilayer of ferromagnetic insulator (FI) with perpendicular magnetization and a three-dimensional topological insulator (TI). Taking into account the coherent magnetic-dipole (Zeeman) interaction as well as the dissipative spin pumping effect on the FI/TI interface, we formulate a dynamical permeability of the FI/TI bilayer and calculate a corresponding electric admittance of an RLC-circuit. As a result, the spin pumping gives rise to a competitive effect on the modes hybridization, whereas a huge level repulsion due to the coherent coupling, which reaches the ultrastrong coupling regime, is found at room temperature for realistic parameter sets. Our work may open a new avenue for designing on-chip microwave devices based on a magnon–polariton in the RLC-circuit. [ABSTRACT FROM AUTHOR]

This paper outlines the development of a high-performance maximum power point tracking (MPPT)-based solar irradiance estimator for photovoltaic (PV) systems. The suggested estimator is constructed around a simple current–voltage-based algebraic equation that hinges on the operation of the PV system at its maximum power point (MPP). In the realm of MPP operation, the overall system is driven by a nonlinear MPPT controller. To achieve this function, we integrated a hybrid incremental conductance integral backstepping (H-INC-IBS) controller to effectively regulate the PV system. This controller was specially chosen for its powerful potency in maximizing the dynamics of the PV system, leading to heightened robustness against changing environmental conditions. The simulation results are provided to showcase the suitability of the proposed estimator. Furthermore, the estimator was verified under experimental conditions, highlighting its soundness and practicality. Through evaluations and comparisons with the conventional irradiance estimator, this paper aimed to emphasize the superiority of the proposed solar irradiance estimator in providing more accurate estimations of solar irradiance for PV systems operating under MPPT supervision. [ABSTRACT FROM AUTHOR]

For the first time, the specific features of snow cover chemistry were studied in the period of its accumulation on Bolshevik Island (the area near the research station Cape Baranov Ice Base). In winter 2018/2019, the specific electric conductance, density, titrated acidity, pH, , , , , and Si were measured in fresh and compacted snow and, additionally, Na+, К+, Ca2+, Mg2+, Cl−, and were measured in compacted snow. Patterns of variations of fresh and compacted snow characteristics were identified, and the effect of marine and anthropogenic factors was discussed. Snow chemistry on Bolshevik Island was compared with the chemistry of precipitation and snow cover in other background areas of the Russian Federation. [ABSTRACT FROM AUTHOR]

The electric and dielectric processes of AlGaN/GaN/Si HEMTs produced by molecular beam epitaxy were examined utilizing direct current-voltage, impedance spectroscopy, and DLTS measurements. Using current-voltage measurements, the DC electrical characteristics of AlGaN/GaN/Si HEMTs revealed the self-heating effect. The relaxation dynamics of charge carriers appear to be studied by the conductance mechanism and electric modulus formalisms. Behavior that is frequency dependent has been observed in impedance spectroscopy. Last but not least, DLTS data have demonstrated the existence of electron traps. The prevalence of parasitic effects and conduction mechanisms are remarkably correlated with deep levels. [ABSTRACT FROM AUTHOR]

In this article, the properties of trapezoidal polymer PSBNP-co-PTNI for capacitive energy storage are investigated theoretically, stimulated by the recent experimental reports [Chen et al., Nature 615, 62 (2023)]. The flatband structures of PSBNP-co-PTNI copolymer reveal that very large effective mass of electron results in Anderson electron localization and then small electric conductance. The TNI doping significantly decreases optical absorption in an ultraviolet region, which can significantly suppress photocurrent. Raman spectrum demonstrates that phonon Debye temperature can be significantly decreased, due to the U-process of phonon scattering by TNI doping, and then results in the phonon delocalization, and then the large thermal conductivity and thermal capacity. The simultaneous regulations on decreasing electric conductivity and on increasing thermal conductivity can significantly increase the ability of capacitive energy storage. The unit-length dependent thermal electric current manifests that the thermal electric current can be significantly decreased by slightly increase in length of copolymer. Overall, our research contributes to the understanding of the impact of TNI doping on the energy storage properties of the polymer and provides a valuable reference for future research focused on polymer energy storage. [ABSTRACT FROM AUTHOR]

Dry soil had a high electric resistance, and thus, electric fences are not always efficient in arid regions. When an animal standing on the ground touches the electric line, an electric circuit is formed and the animal gets shocked. Not only dry soil but also snow reduces the efficacy of electric fences. This is because liquid water is conductive, but solid snow is an insulator. However, the conductance of frozen soil is not studied enough. This study aims to investigate whether frozen soil reduces the effectiveness of electric fences and determines the electrical resistance of frozen soil. Four electric fences were installed on the forest edge in Yamanashi Prefecture, central Japan. From May 2021 to March 2022, two sensor cameras per fence were used to detect "probability of electrification" and "probability of intrusion into the fences." We treated from May to October 2021 and November 2021 to March 2022 as a non-frozen season (summer) and frozen season (winter), respectively. Results showed that in winter, the probability of electrification was decreased from 0.5 to 0.29 and the intrusion was increased from 0.03 to 0.07. When a pulsed current was applied, the electric conductance of frozen soil was reduced to 0.5% of that of the wet soil. Therefore, due to their reduced effectiveness in cold conditions, alternate grounding techniques for electric fences are required. For instance, the use of weed control sheet interwoven with stainless steel wire could be a practical solution. [ABSTRACT FROM AUTHOR]

The advance in digital diagnostic technologies has significantly facilitated the detection of dental caries. Despite the increase in clinically available digital diagnostic aids for dental caries, there is yet to be a comprehensive summary of all available technology. This review aims to provide an overview of digital diagnostic aids for the clinical detection of dental caries, particularly those at an initial stage. Currently available digital diagnostic aids for caries detection can be classified into four categories according to the initial source of energy, including radiation-based aids, light-based aids, ultrasound-based aids, and electric-based aids. Radiation-based aids use ionizing radiation, normally X-ray, to produce images of dental structures. Radiation-based aids encompass digital bitewing radiography and cone beam computed tomography. Light-based aids employ light or laser to induce signals for the detection of the changes in the carious dental hard tissue. Common light-based aids include digital transillumination and light/laser-induced fluorescence. Ultrasound-based aids detect the signal of ultrasound waves to assess the acoustic impedance of the carious teeth. The ultrasound caries detector is an available ultrasound-based aid. Electric-based aids assess the changes in the electric current conductance or impedance of the teeth with caries. Available electric-based aids include electrical conductance measurement and alternating current impedance spectroscopy. Except for these clinically available digital diagnostic aids, many digital diagnostic aids for caries detection are still under development with promising results in laboratory settings. [ABSTRACT FROM AUTHOR]

The lead-free ceramics (1 − x)(0.94 Bi 0. 4 7 Na 0. 4 7 Ba 0. 0 6 TiO3-0.06BiAlO3)- x AgNbO3 (denoted as BNBTA- x AN) were synthesized via a solid-state sintering method. The effect of AgNbO3 doping amount on dielectric properties of the ceramics was studied systematically. X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscope were used to detect the structure of the ceramics. Temperature-dependent dielectric spectra, frequency-dependent dielectric constant and alternating current (ac) electric conductance at various temperatures were measured. The doping of AgNbO3 greatly reduces dielectric constant around Curie temperature and thus enhances the temperature stability of the dielectric constant. The ceramic BNBTA-0.03AN exhibits excellent temperature-stable dielectric properties with temperature coefficient of capacitance (TCC) ≤ ± 15% between 55∘C and 418∘C with temperature window 363∘C and small changes of dielectric constant and dielectric loss from 100 Hz to 1 MHz at different temperatures. The obtained ceramics are expected to be used in high-temperature capacitors due to its excellent temperature stability. [ABSTRACT FROM AUTHOR]

In this work, prominent longitudinal variation of polar electrojet (PEJ) and field‐aligned currents (FACs) are reported for the first time in different local times and hemispheres. Larger longitudinal differences exist mostly in the south than in the north with nearly opposite phase except for the nighttime. The most prominent longitudinal variation occurs around noontime. In the nighttime, the longitudinal changes of PEJ and upward FACs in both hemispheres are similar. The larger northern summer FACs and PEJ at noon occur more frequently around 0°–60° and 300°–360° magnetic longitude (MLon), while the larger southern summer currents occur around 120°–300° MLon. The summer‐winter hemispheric differences in PEJ and upward FACs disappear in the midnight sector. The northern FACs dominance exists around 0°–120° and 270°–360° MLon, except for winter when the northern dominance of upward FACs at night exist in nearly all longitudes. In local summer, PEJ shows northern dominance around 0°–60° and 270°–360° MLon, and southern dominance around 120°–240° MLon. In local winter, PEJ shows northern dominance around 180° MLon near midnight, while in most other local times, PEJ shows northern dominance around 270° MLon. These longitudinal, seasonal and hemispheric differences are discussed in terms of mixing effects of ionospheric conductance and merging electric field in different local time sectors. Key Points: Prominent longitudinal variations of polar electrojet (PEJ) and field‐aligned currents (FACs) in different local times and seasonsHemispheric asymmetry of PEJ and FACs show obvious longitudinal variationsMixing effects of ionospheric conductance and merging electric field exist in different local times [ABSTRACT FROM AUTHOR]

Passivated, selective contacts in silicon solar cells consist of a double layer of highly doped polycrystalline silicon (poly Si) and thin interfacial silicon dioxide (SiO2). This design concept allows for the highest efficiencies. Here, we report on a selective laser activation process, resulting in highly doped p++-type poly Si on top of the SiO2. In this double-layer structure, the p++-poly Si layer serves as a layer for transporting the generated holes from the bulk to a metal contact and, therefore, needs to be highly conductive for holes. High boron-doping of the poly Si layers is one approach to establish the desired high conductivity. In a laser activation step, a laser pulse melts the poly Si layer, and subsequent rapid cooling of the Si melt enables electrically active boron concentrations exceeding the solid solubility limit. In addition to the high conductivity, the high active boron concentration in the poly Si layer allows maskless patterning of p++-poly Si/SiO2 layers by providing an etch stop layer in the Si etchant solution, which results in a locally structured p++-poly Si/SiO2 after the etching process. The challenge in the laser activation technique is not to destroy the thin SiO2, which necessitates fine tuning of the laser process. In order to find the optimal processing window, we test laser pulse energy densities (Hp) in a broad range of 0.7 J/cm2 ≤ Hp ≤ 5 J/cm2 on poly Si layers with two different thicknesses dpoly Si,1 = 155 nm and dpoly Si,2 = 264 nm. Finally, the processing window 2.8 J/cm2≤ Hp ≤ 4 J/cm2 leads to the highest sheet conductance (Gsh) without destroying the SiO2 for both poly Si layer thicknesses. For both tested poly Si layers, the majority of the symmetric lifetime samples processed using these Hp achieve a good passivation quality with a high implied open circuit voltage (iVOC) and a low saturation current density (J0). The best sample achieves iVOC = 722 mV and J0 = 6.7 fA/cm2 per side. This low surface recombination current density, together with the accompanying measurements of the doping profiles, suggests that the SiO2 is not damaged during the laser process. We also observe that the passivation quality is independent of the tested poly Si layer thicknesses. The findings of this study show that laser-activated p++-poly Si/SiO2 are not only suitable for integration into advanced passivated contact solar cells, but also offer the possibility of maskless patterning of these stacks, substantially simplifying such solar cell production. [ABSTRACT FROM AUTHOR]

This paper proposes a new method of dynamic estimation based on a linear quadratic estimation (LQE) to identify the parameters of impedance and admittance of a three-phase electric power medium-size transmission line using measurements provided by phasor units. First, a novel set of phasor equations for the steady-state operation of a medium-length transmission line are introduced. Then, the equations are transformed based on unscented transformation into a dynamic system model. The effectiveness of the new method is validated through the comparison of the results based on simulated data provided by two types of phasor unit models during step variation in line voltage and frequency. One model represents a typical phasor unit that adopts Fourier Transform-Based (FT-Based) algorithm, while the second one is adopting an unscented transform-based algorithm. Simulations have demonstrated the effectiveness of the proposed method for both models when step variation in line voltage and frequency occurs in the transmission line. [ABSTRACT FROM AUTHOR]

Dependences of the electrokinetic potential of the surface of 8V-NT (3 M HCl) MIP plates in NaCl solutions: (1) AP; (2) e calculated by Eq. (7); (3) e calculated by Eq. (11). In a 0.1 M NaCl solution, it turned out that the electrokinetic potential of the porous surface of a plane-parallel capillary approaches the values found for a continuous surface. [Extracted from the article]

The characterization of performance and losses of proton exchange membrane (PEM) and anion exchange membrane (AEM) electrolysis cells is typically carried out by electrochemical impedance spectroscopy and polarization curve measurements. With these common methods, lateral inhomogeneities, local degradation, or defects cannot be mapped. Lock‐in thermography (LIT) offers the possibility of mapping current flows and electrical losses. It has already been used successfully for many years in microelectronics and photovoltaics, among others. Conventional LIT with pulsed DC excitation does not work below the reversible voltage of water electrolysis. Therefore, high frequencies are used to generate the conductivity of the ion exchange membrane. Herein, for the first time, the method variable‐frequency AC excitation (VACE)‐LIT is presented. It combines aspects of electrochemical impedance spectroscopy with LIT and is applied to a PEM electrolysis membrane electrode assembly. It is shown that PEMs can exhibit strongly nonhomogeneous current densities, presumably resulting from contact resistances in the layer stack. In addition, local currents flowing at low frequencies indicate electronically conductive defects in the membrane. [ABSTRACT FROM AUTHOR]

Shaded conditions cause a decrease in the performance of photovoltaic (PV) systems. In this situation, the power versus voltage curve shows two maximum power points, namely local (LMPP) and global (GMPP). The main challenge for extracting the maximum power from a PV system during shading conditions is the existence of a false maximum or LMPP along with a true maximum or GMPP. Traditional maximum power point tracking (MPPT) has faced hurdles in overcoming the situation. Therefore, this paper describes the implementation of Queen Honey Bee Migration (or QHBM for short) to track GMPP of PV systems, which called QHBM MPPT. The highlight of this paper is the simulation results of QHBM MPPT on PV systems under various shading conditions. We implemented QHBM MPPT on a boost converter installed on a 1200 Wp PV system. We conducted a simulation using MATLAB® with five scenarios which aim to show the various shadows that PV systems might encounter in reality. The MPPT QHBM is tested repeatedly and then the average value is taken to measure performance in MPP tracking. The average value is used to calculate tracking efficiency, number of iteration or convergence time. We also compared QHBM with other methods, namely incremental conductance (IC) and Particle Swarm Optimization (PSO). The results obtained show that the QHBM and PSO MPPTs outperform the IC MPPT in terms of efficiency, convergence time and the number of iterations. IC MPPTs oscillate under shading conditions since no knowledge of GMPP. Both PSO and QHBM MPPTs know GMPP from scouts or particles, respectively. Therefore, PSO and QHBM MPPTs are better than IC MPPT in various shading cases. [ABSTRACT FROM AUTHOR]

The article considers the theory, methods, and some results of four-year field studies of the processes of runoff formation on a small freezing experimental river catchment in a continuous thick (400 m) permafrost zone (the Republic of Sakha (Yakutia)) based on data on natural water chemistry. The analyzed problems include the seasonal and daily dynamics of river flow in the warm season, the concentrations of some dissolved substances in different types of water, as well as the role of channel widenings, supra-permafrost water, and aufeises in flow formation. Various types of relationships between water discharges and the concentrations of some dissolved substances are described under varying hydrothermal conditions. The role of nonfreezing lake-like channel widenings (bochags) in the regulation of freshet flow of water and dissolved matter is evaluated. The efficiency of the automated digital registration of the level, temperature, and specific electric conductance of water with a high time resolution at hydrological gages is discussed, especially, as applied to the rapid processes in a river. [ABSTRACT FROM AUTHOR]

Potassium (K+) channels establish and maintain the resting potential of most living cells. Their activity is predominantly regulated by the membrane voltage or the K+ gradient across the cell membrane. However, many cells also express small-conductance calciumactivated potassium (SK) channels, which have the unique ability to translate changes in the level of the intracellular second messenger, Ca2+ to changes in the membrane K+ conductance and, therefore, the resting membrane potential. This article reviews the structure, presence, distribution, and function of SK channels, their pharmacological modulation, and their role in health and disease, emphasizing nociception and pain. [ABSTRACT FROM AUTHOR]

We adopt the tight-binding model and the mode-matching method to study the electrical modulation of the valley polarization in strained silicene constrictions. The effects of the potential energy, the external electric field, and the strain on the band structures and the transport property are investigated. The conductance shows a clear valley polarization and zero conductance in the absence of the electric field and the strain. It is found that the external electric field can open a clear bandgap and result in an extra zero conductance. However, the strain can not induce a bandgap, which only slightly change the energy band. Correspondingly, the strain has little effect on the system's conductance. The transport behavior of zero conductance is elucidated in terms of band structures of the silicene constriction. Therefore, one can realize an effective modulation of the valley-dependent transport of the silicene constriction by combining the potential energy and the electric field. The electrical modulation of the valley polarization and zero conductance can be exploited for silicene-based valleytronics devices. [ABSTRACT FROM AUTHOR]

Motivated by the trend of increasing miniaturization and multifunctional implementation, the electronic transport properties of two silicon carbide (SiC) molecular chains in parallel sandwiched between two semi-infinite Au(100)-3 × 6 electrodes are investigated using the density-functional theory and nonequilibrium Green's function formalism. The π-bonding molecular orbitals resulting from the in-phase combination of two px or py atomic orbitals of the C and Si atoms are found to play a key role in the electronic transport, and the possible electron pathways are summarized. Our results show that changing the separation between the two chains in a certain range can produce remarkable differences in transport properties. When the two chains are in small separation (d = 2.884 Å), their strong electrostatic interaction makes a constructive contribution to the electronic transport properties, in which the underlying physical mechanism has been revealed. We also find that d = 5.768 Å is the critical distance both for the transport difference and for the electrostatic interaction in the top-top configuration. Both the conductance (classical Kirchhoff's superposition law) and the current follow the superposition law well in the atomic scale when d = 5.768 Å, much smaller than the critical distance of 15.5 Å from the result of Zhou et al. [Carbon 95, 503 (2015)]. Additionally, the superposition law is more valid for a larger chain spacing (d ≥ 5.768 Å). Our work demonstrates that the realization of the superposition law and the way of increasing current and rectification effect may lay the foundation for the miniaturization exploration and multifunctional implementation of SiC chain related molecular devices. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulation, we studied the electrical conductance of two-dimensional films. The films consisted of a poorly conductive host matrix and highly conductive rodlike fillers (rods). The rods were of various lengths, obeying a log-normal distribution. They were allowed to be aligned along a given direction. The impacts of the length dispersity and the extent of the rod alignment on the insulator-to-conductor phase transition were studied. Two alternative computational approaches were compared. Within Model I, the films were transformed into resistor networks with regular structures and randomly distributed conductances. Within Model II, the films were transformed into resistor networks with irregular structures but with equal conductivities of the conductors. A comparison of the models evidenced similar behavior in both models when the concentration of fillers exceeded the percolation threshold. However, a fairly fine mesh should be used in Model I to obtain a reasonable estimation of the electrical conductance. The electrical conductance is slightly overestimated in Model I. In anisotropic systems, the length dispersity of fillers has a more pronounced effect on the electrical conductance along the direction of the rod alignment. Some analytical results were obtained: (i) the relationship between the number of fillers per unit area and the transmittance of the films within Model I and (ii) the electrical conductance of the films for dense networks within Model II. [ABSTRACT FROM AUTHOR]

The bias dependent behaviors in magnetic field effects (MFEs) of the current and the electroluminescence (EL) intensity in organic light emitting diodes (OLEDs) have been investigated from electrically-detected and EL-detected magnetic resonance (EDMR and ELDMR) techniques. An EDMR signal was not detected from the electron-only device, and the hole-only device gave only a much smaller EDMR signal than the OLED device. Both the EDMR and ELDMR signals observed from the OLED are concluded to primarily arise from the spin-dependent reaction of electron-hole (e-h) pairs. Both the normalized EDMR and ELDMR signal intensities decrease by increasing the operation bias of OLED, because the increased bias enhances the dissociation and recombination of e-h pairs beyond the increase in the pair-density by the bias. The bias-dependence curves of magneto-conductances and magneto-EL intensities are demonstrated to be very similar to those of the normalized EDMR and ELDMR, respectively. This similarity gives direct evidence that e-h pairs determine the MFEs of the present OLEDs at room temperature and that the MFEs are reduced by bias-dependent dissociation and recombination of e-h pairs. The bias-dependent EDMR and ELDMR experiments are thus effective as probing methods to examine the magnetic field properties via e-h pairs of OLEDs. [ABSTRACT FROM AUTHOR]

Hysteresis in the current-voltage characteristics is usually observed in several types of materials and devices. Its origin is still controversial and the subject of intense research even to date. The interest in this phenomenon is constantly renewed as new materials that exhibit this characteristic are developed because of its undesired effects on the performance of different devices like solar cells and sensors. The space charge limited current spectroscopy is a technique frequently used to study transport in general and it has been used particularly to identify the dominant mechanisms during different branches of the current voltage hysteresis loops. The transport regimes are identified from the slope of double logarithmic plots of the experimental data. This methodology is relatively poor, particularly when linear regions of those plots are narrow or even non-existent. Thus, more efficient and detailed analytical techniques are required. One of these techniques is based on the use of the normalized differential conductance. This function allows obtaining hidden information of the transport mechanism not available with the traditional methodology. The use of this method to study the hysteresis is analyzed in this work. Different nanocomposites, made of chitosan or polyvinyl alcohol, containing gold nanoparticles or carbon nanotubes as fillers, whose current-voltage characteristics exhibit hysteresis when subjected to applied voltage cycling, are used as a test workbench for the proposed methodology. Whereas different normalized differential conductance versus voltage curves are obtained for forward ramps, the same behaviors during reverse ramps are observed for all the materials, indicating clearly a change of the transport mechanisms. From the voltage dependencies, it is possible to conclude that whereas bulk mechanisms dominate during forward ramps, interface or electrode mechanisms are more important during reverse ramps. [ABSTRACT FROM AUTHOR]

Monatomic and molecular hydrogen and also oxygen, as well as water molecules and OH that are exposed to atomic copper in intimate contact, have been studied theoretically using computational methods. The authors optimized moderately large structures of Cu/H/Cu, Cu/HCuH/Cu, Cu/H2/Cu, Cu/H2O/Cu, Cu/OH/Cu, Cu/O/Cu, and Cu/O2/Cu and calculated appropriate values for conductance and inelastic tunneling spectroscopy (IETS) properties of the contact junctions, elucidating them as being a possible outcome resulting from the exposure of copper electrodes to the atomic/molecular contaminant species. Here we also demonstrate the IETS properties, by means of ab initio calculations, which can determine the form of the junction geometries. Furthermore, we identify the bonding geometries at the interfaces of the copper electrodes that directly give rise to the specific IETS signatures that have been observed in recent experiments. Based on low-bias conductance and IETS calculations, for the specific case of water exposure of copper electrodes, it was concluded that a single hydrogen or a single oxygen atom bridging the copper electrodes is not responsible for the high conductance peak measurements. Regarding Model 4, where an individual water molecule is considered to be the bridging constituent, our computational results suggest that it has a relatively low probability of being an appropriate candidate. Based upon current computational results, the two hydrogens in Model 3 appear to be in molecular form, although they still form a bond with the adjacent copper atoms. Comparing computational with experimental results indicates that Model 3 is in acceptable agreement with available data. [ABSTRACT FROM AUTHOR]

To determine the dynamic characteristics of a gas-centered swirl coaxial injector under backpressure, an experimental system of dynamic injection in a backpressure chamber was constructed. Filtered water and nitrogen were used as simulant media for rocket propellants, which are typically used with this kind of injector. An inertial flow pulsator was manufactured to generate the pulsation of the flows that feed to the liquid injector. The electric conductance method was adopted to measure liquid film thickness. After the pulsation of incoming flow in the feedline was tested, and the operating conditions for the injector to start pulsating were validated, the effects of the chamber backpressure and the recess length of the injector on the dynamic characteristics of spray, such as liquid film thickness, breakup length, and amplitude of pulsation, have been investigated in detail. Experimental results demonstrated that the increase in chamber backpressure prompts the liquid sheet to rupture earlier with a shorter breakup length, which results from the increased density of the ambient gas. Chamber backpressure suppresses the pulsation of the outlet flow, especially for a longer recess length. Moreover, a decrease in the recess length results in a reduction in breakup length due to an intense gas–liquid shearing in a narrower recess section. For a lower backpressure, the amplitude of outlet flow generally increases when the recess length increases. However, this phenomenon is not obvious for the conditions of higher backpressure and lower pulsation frequency. [ABSTRACT FROM AUTHOR]

The article presents a new van der Waals heterojunction strategy to fabricate layer-by-layer single-molecule switches.It mentions that the method involves incorporating a single molecule between two single-layer graphene electrodes, which enables the fabrication of smaller devices, including the ability to control conformation and cross-plane charge transport, resulting in reversible switches.

Dry sliding behavior of an AISI 1020 steel and sintered powder composites (pins) at sliding velocities of 5 and 15 m/s has been investigated applying general pin-on-disk and pin-on-ring wear loading configurations. Three main output parameters of the current-collecting tribosystem, namely, the electrical conductivity of the contact, the current density in the contact, and the wear intensity corresponding to the onset of catastrophic wear were chosen to compare the tribotechnical behavior of the materials. It was found that pin-on-ring sliding caused the electrical conductivity of the contact σA(j) = (200–300) S/cm2, whereas pin-on-disk sliding caused σA(j) < 200 S/cm2 in the presence of FeO (wuestite) on the pin sliding surface, but pin-on-ring sliding caused the ultimate current density jc < 300 A/cm2 comparing with jc = (500–600) A/cm2 in pin-on-disk sliding. The absence of FeO on the sliding surface caused unsatisfactory contact characteristics. An increase in the sliding speed has led to a decrease in the electrical conductivity of the contact, but significant changes in the maximum contact current density and wear intensity were not observed. It is shown that two morphologically different images of specimen sliding surface are formed. This was observed for most specimens and was presented as a plastic deformation pattern of specimen sliding surface under electric current of high density. [ABSTRACT FROM AUTHOR]

Polar group-modified crosslinked polyethylene (XLPE) materials are developed with a peroxide thermochemical method of individually grafting chloroacetic acid allyl ester (CAAE) and maleic anhydride (MAH) to polyethylene molecular-chains, which are dedicated to ameliorating dielectric characteristics through charge-trapping mechanism. By free radical addition reactions, the CAAE and MAH molecules are successfully grafted to polyethylene molecular chains of XLPE in crosslinking process, as verified by infrared spectroscopy molecular characterizations. Dielectric spectra, electric conductance, and dielectric breakdown strength are tested to evaluate the improved dielectric performances. Charge trap characteristics are investigated by analyzing thermal stimulation depolarization currents in combination with first-principles electronic-structure calculations to reveal the polar-group introduced mechanisms of contributing dipole dielectric polarization, impeding electric conduction, and promoting electrical breakdown field. The grafted polar-group molecules, especially for MAH, can introduce deep-level charge traps in XLPE materials to effectively restrict charge injections and hinder charge carrier transports, which accounts for the significant improvements in electric resistance and dielectric breakdown strength. [ABSTRACT FROM AUTHOR]

The frequency and temperature dependences of dielectric permittivity and electric conductivity of high-density polyethylene with the additive of monodisperse barium titanate particles are studied. It was shown that dielectric permittivity and electric conductance increase with increasing of filler concentration at all temperatures. In this case, conductivity has hopping mechanizm described by the Josher theory. The corresponding exponent parameter and activation energy decrease as well as conductivity rises with increasing of barium titanate concentration. The experimental data of dielectric permittivity are compared with the Maxwell-Garnett and Bruggeman theories. [ABSTRACT FROM AUTHOR]

Phase-change memory (PCM) is an emerging non-volatile memory technology that is based on the reversible and rapid phase transition between the amorphous and crystalline phases of certain phase-change materials. The ability to alter the conductance levels in a controllable way makes PCM devices particularly well-suited for synaptic realizations in neuromorphic computing. A key attribute that enables this application is the progressive crystallization of the phase-change material and subsequent increase in device conductance by the successive application of appropriate electrical pulses. There is significant inter- and intra-device randomness associated with this cumulative conductance evolution, and it is essential to develop a statistical model to capture this. PCM also exhibits a temporal evolution of the conductance values (drift), which could also influence applications in neuromorphic computing. In this paper, we have developed a statistical model that describes both the cumulative conductance evolution and conductance drift. This model is based on extensive characterization work on 10 000 memory devices. Finally, the model is used to simulate the supervised training of both spiking and non-spiking artificial neuronal networks. [ABSTRACT FROM AUTHOR]

A thorough study of the admittance of TiN/Ti/HfO2/W bipolar resistive memories [resistance random access memory (RRAM)] was carried out under different bias conditions and in a wide range of ac signal frequencies. We demonstrate that a continuum of intermediate states can be obtained by applying appropriate dc bias waveforms. Cumulative writing and erasing admittance cycles were performed by applying triangular voltage waveform of increasing amplitude. The influence of the initial conditions on the variation of the real (conductance) and imaginary (susceptance) components of the admittance is described. An accurate control of the memory state is achieved both in terms of the conductance and the susceptance by means of an adequate selection of the voltage values previously applied. A method to obtain three-dimensional voltage-conductance-susceptance state-plots is described in detail. Memory maps of admittance parameters as a function of the programming voltage are made by sensing the memory state at 0 V, without static power consumption. The multilevel nature of RRAM devices and their suitability for neuromorphic computation are demonstrated. [ABSTRACT FROM AUTHOR]

Novel Deep Neural Network (DNN) accelerators based on crossbar arrays of non-volatile memories (NVMs)—such as Phase-Change Memory or Resistive Memory—can implement multiply-accumulate operations in a highly parallelized fashion. In such systems, computation occurs in the analog domain at the location of weight data encoded into the conductances of the NVM devices. This allows DNN training of fully-connected layers to be performed faster and with less energy. Using a mixed-hardware-software experiment, we recently showed that by encoding each weight into four distinct physical devices—a "Most Significant Conductance" pair (MSP) and a "Least Significant Conductance" pair (LSP)—we can train DNNs to software-equivalent accuracy despite the imperfections of real analog memory devices. We surmised that, by dividing the task of updating and maintaining weight values between the two conductance pairs, this approach should significantly relax the otherwise quite stringent device requirements. In this paper, we quantify these relaxed requirements for analog memory devices exhibiting a saturating conductance response, assuming either an immediate or a delayed steep initial slope in conductance change. We discuss requirements on the LSP imposed by the "Open Loop Tuning" performed after each training example and on the MSP due to the "Closed Loop Tuning" performed periodically for weight transfer between the conductance pairs. Using simulations to evaluate the final generalization accuracy of a trained four-neuron-layer fully-connected network, we quantify the required dynamic range (as controlled by the size of the steep initial jump), the tolerable device-to-device variability in both maximum conductance and maximum conductance change, the tolerable pulse-to-pulse variability in conductance change, and the tolerable device yield, for both the LSP and MSP devices. We also investigate various Closed Loop Tuning strategies and describe the impact of the MSP/LSP approach on device endurance. [ABSTRACT FROM AUTHOR]

Conducting behavior of two-dimensional (2D) disordered nanowire networks (DNNs) is studied. We find that the length-ratio (ηcp) of conducting paths to all nanowires in the network plays a key role in determining the network conductivity. An algorithm is designated to monitor the formation of conducting paths in the networks and the evolution of network conductance at the same time. As either the area fraction or length of nanowires increases, the length-ratio (ηcp) of the conducting paths expands; meanwhile, the network conductance increases. The network conductance is normalized by the conductance of the regular network so that normalized network conductivity (σ) is obtained. A linear relationship is observed when plotting r against ηcp. An equation of σ = 2(ηcp -0:5) is obtained when ηcp is higher than the threshold. It could fit most part of the simulated plots, except for the region near ηcp ~ 0:5. 2D transparent and conductive films are built from randomly arranged silver nanowires. Linear behavior is also observed, with the slope less than 2, which is due to the existence of the junction resistance between nanowires. The obtained equation is in agreement with the previous result of the Effective Medium Theory. Finally, the length-ratio (ηcp) could serve as a basic topological parameter in describing the conducting behavior of DNNs. [ABSTRACT FROM AUTHOR]

Conducting behavior of two-dimensional (2D) disordered nanowire networks (DNNs) is studied. We find that the length-ratio ( η c p ) of conducting paths to all nanowires in the network plays a key role in determining the network conductivity. An algorithm is designated to monitor the formation of conducting paths in the networks and the evolution of network conductance at the same time. As either the area fraction or length of nanowires increases, the length-ratio ( η c p ) of the conducting paths expands; meanwhile, the network conductance increases. The network conductance is normalized by the conductance of the regular network so that normalized network conductivity (σ) is obtained. A linear relationship is observed when plotting σ against η c p . An equation of σ = 2 (η c p − 0.5) is obtained when η c p is higher than the threshold. It could fit most part of the simulated plots, except for the region near η c p ∼ 0.5. 2D transparent and conductive films are built from randomly arranged silver nanowires. Linear behavior is also observed, with the slope less than 2, which is due to the existence of the junction resistance between nanowires. The obtained equation is in agreement with the previous result of the Effective Medium Theory. Finally, the length-ratio ( η c p ) could serve as a basic topological parameter in describing the conducting behavior of DNNs. [ABSTRACT FROM AUTHOR]