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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]

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]

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]

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]

During geomagnetically active intervals, latitudinally narrow channels of fast westward ion drifts were at times observed in the subauroral region. They are termed the "subauroral ion drifts" (SAID). The Strong Thermal Emission Velocity Enhancement (STEVE), a subauroral optical phenomenon, is intrinsically related to intense SAID. Recently, we had developed a two‐dimensional (2D) time‐dependent model to study the self‐consistent variations of the ionosphere under intense SAID. The present study further advances the model to a current generator scenario of SAID. By assuming magnetospheric field‐aligned current (FAC) inputs based on existing knowledge and observations, we model the self‐consistent variations of the ionosphere, with focus on the dynamic changes of the plasma density, the Pedersen conductance, and the electric field. We can reproduce the self‐consistent evolution of an intense SAID and its associated ionospheric dynamics such as extreme heating and depletion. We illustrate that the ion Pedersen drifts can cause dynamic density variations in the lower ionosphere. Positive feedback is found to exist between the self‐consistent variations of the electric field and the conductance: the ion Pedersen transport associated with the electric field leads to density depletion in the lower ionosphere, thus reducing the Pedersen conductance and further enhancing the electric field there. We conclude that such positive feedback is key to the formation of intense SAID's in the ionosphere. Key Points: We present a 2D time‐dependent ionospheric model according to a current generator scenario of SAID with realistic FAC inputsWe reproduce the self‐consistent evolution of an intense SAID and its associated ionospheric dynamics such as heating and depletionIon Pedersen transport plays a crucial role in the positive feedback between the conductance reduction and the SAID intensification [ABSTRACT FROM AUTHOR]

This paper deals with power generation through solar photovoltaic (SPV) system and its implementation as grid‐tied and stand‐alone systems. The major setbacks of SPV system of low conversion efficacy, that can be enhanced through the maximum power point tracking (MPPT) algorithm. A modified incremental conductance (MIC), termed as error based incremental conductance MPPT, has been proposed, and its behaviour is comprehensively compared with classical perturb and observe (P&O) and incremental conductance (IC) techniques. Dealing with the on‐grid application of SPV system, maximum power obtained through MIC is fed to a three‐phase grid operating at unity power factor (UPF), and the quality of grid current is monitored. Further, the power obtained through MIC finds its application in designing an SPV‐diesel generator (DG) based hybrid renewable energy system (HRES) for areas either not connected to the grid or have insufficient fossils. The stochastic nature of source or uncertain load demand leads to deviation in system frequency. This paper proposes an intelligent, comprehensive supervisory optimal‐fuzzy‐proportional‐integral‐derivative (O‐F‐PID) controller for load frequency control (LFC). The performance of proposed O‐F‐PID controller has been vividly compared with the designed optimal‐PID (O‐PID) and conventional PID (C‐PID) controllers under varying source and load demand conditions. [ABSTRACT FROM AUTHOR]

Ionospheric conductance plays a crucial and active role in magnetosphere‐ionosphere‐thermosphere coupling processes. Despite its importance, direct global observations of conductance are unavailable. This limitation inspires the development of empirical models that are widely used to specify global distributions of conductance indirectly. In this work, a new model, COnductance Model based on PFISR And SWARM Satellite observations, describing the statistical relationships between conductance and field‐aligned currents (FACs) is presented. The conductance was calculated using the electron densities measured by Poker Flat Incoherent Scattering Radar (PFISR), and the FACs were determined by the magnetic perturbations measured by SWARM at Low‐Earth Orbit. Between 2014 and 2020, there were ∼3,900 conjunction events between PFISR and SWARM, providing a large data set for investigating the relationship between conductance and FACs. It is found that both Hall and Pedersen conductances vary as a power of j∥ $\left\vert {j}_{{\Vert} }\right\vert $, and the power index a depends on magnetic local time and the direction of FACs, ranging from 0.0 to 0.6. Properties of this power index a are founded as follows: (a) the largest power index is obtained on the dawn side, and the minimum is at noon; and (b) the power indices are positive for both upward and downward FACs and are larger for upward FACs than downward FACs. The underlying physical mechanisms of the observed variations of the model parameters are also discussed. Despite the complicated relationship between FACs and conductance, this model provides a convenient way to specify global distributions of the auroral zone conductance. Plain Language Summary: Ionospheric conductance is a crucial parameter in the modeling of the geospace response to varying solar wind forcing. However, direct global observations of conductance are unavailable. This limitation inspires the development of this new model, COnductance Model based on PFISR And SWARM Satellite observations, describing the statistical relationships between conductance and field‐aligned currents (FACs). Global distributions of FACs are relatively easy to obtain from either observations or numerical simulations. Thus, this model provides a convenient way to specify the global distribution of the ionospheric conductance. Key Points: Ionospheric conductance varies as a power of j∥ $\left\vert {j}_{{\Vert} }\right\vert $ in the ionosphere based on a linear weighted least square fitting methodThe power indices peak on the dawn side and dip at noonUpward field‐aligned currents (FACs) are associated with larger power indices than downward FACs [ABSTRACT FROM AUTHOR]

A new technique has been developed to determine the high‐latitude electric potential from observed field‐aligned currents (FACs) and modeled ionospheric conductances. FACs are observed by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), while the conductances are modeled by Sami3 is Also a Model of the Ionosphere (SAMI3). This is a development of the Magnetosphere‐Ionosphere Coupling approach first demonstrated by Merkin and Lyon (2010), https://doi.org/10.1029/2010ja015461. An advantage of using SAMI3 is that the model can be used to predict total electron content (TEC), based on the AMPERE‐derived potential solutions. 23 May 2014 is chosen as a case study to assess the new technique for a moderately disturbed case (min Dst: −36 nT, max AE: 909 nT) with good GPS data coverage. The new AMPERE/SAMI3 solutions are compared against independent GPS‐based TEC observations from the Multi‐Instrument Data Analysis Software (MIDAS) by Mitchell and Spencer (2003), and against Defense Meteorological Satellite Program (DMSP) ion drift data. The comparison shows excellent agreement between the location of the tongue of ionization in the MIDAS GPS data and the AMPERE/SAMI3 potential pattern, and good overall agreement with DMSP drifts. SAMI3 predictions of high‐latitude TEC are much improved when using the AMPERE‐derived potential as compared to Weimer's (2005), https://doi.org/10.1029/2005ja011270 model. The two potential models have substantial differences, with Weimer producing an average 77 kV cross‐cap potential versus 60 kV for the AMPERE‐derived potential. The results indicate that the 66‐satellite Iridium constellation provides sufficient resolution of FACs to estimate large‐scale ionospheric convection as it impacts TEC. Plain Language Summary: Plasma in the ionosphere convects across high latitudes in response to electric fields generated by solar wind driving of Earth's magnetosphere. Magnetic data from the 66‐satellite Iridium satellite constellation is routinely analyzed to measure the electric currents flowing between the ionosphere and magnetosphere. In this paper, we combined these observed field‐aligned currents with a model of the ionospheric conductance to estimate the corresponding electric field in the ionosphere. We used these electric field estimates to specify the plasma convection in a first‐principles ionosphere model, and compared the results against independent data in a moderately disturbed period. The results of our case study indicate that the technique works well, although plasma convection is not the only factor that causes uncertainty into predictions of the high‐latitude ionosphere. The data used here can be made available in near‐real‐time, so it is possible that our technique could be adopted for operational space weather prediction. Key Points: Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) field‐aligned currents have been combined with the Sami3 is Also a Model of the Ionosphere (SAMI3) model to estimate the high‐latitude potentialIndependent validation of the new technique using satellite drifts and ground‐based total electron content indicates good agreement overallThe SAMI3 model performs better in this case when using AMPERE‐derived potentials than when using the empirical Weimer potential [ABSTRACT FROM AUTHOR]

Traditional constant admittance controller (CAC) in uncertain contact environment is highly dependent on environmental location and stiffness, which are always difficult to obtain in most applications. To address this problem, a fuzzy adaptive admittance controller (FAAC) based on fuzzy inference rules is proposed in this paper. Firstly, an adaptive admittance controller (AAC) that can compensate for the admittance parameters in real time based on force error information is proposed. Secondly, a fuzzy logic loop is introduced into the adaptive term of the AAC system to reduce the overshoot when force tracking, thus creating the FAAC. The detailed design method of FAAC is presented, and the stability conditions are analysed. Finally, simulations and experiments are conducted in several dynamic environments to demonstrate the force tracking performance of the proposed controller. [ABSTRACT FROM AUTHOR]

The safe and reliable operation of a modern power system imposes the need to describe and estimate the system stability through impedance‐admittance measurement and identification. The integration and operation of medium voltage equipment in existing infrastructure requires impedance‐admittance measurement devices which are currently few in number and often limited in output voltage level and output bandwidth. The four‐quadrant Cascaded H‐Bridge (CHB) topology, featuring a three‐phase Active Front‐End (AFE) and a single‐phase H‐Bridge inverter presents itself as a potential solution to this problem. To support the development of the CHB topology the AFE hardware and control platforms require implementation and testing. The testing aspect of the process additionally includes the measurement of terminal characteristics such as the input admittance and the output impedance. The complexity of the CHB converter and its increased number of power electronics building blocks requires the use of industrial control platforms. This work defines the hardware implementation and control principle of the three‐phase AFE of a CHB converter as well as the system for measuring its terminal characteristics. The results obtained show that the proposed system can be successfully used to measure the input admittance and output impedance of the AFE upon which the development of the CHB is based. [ABSTRACT FROM AUTHOR]

Based on the Swarm 16 Hz Advanced Plasma Density data set, and using the Swarm A satellite, we apply automatic detection of spectral breaks in seven million sampled plasma density power spectra in the high‐latitude F‐region ionosphere. This way, we survey the presence of plasma irregularity dissipation due to an enhanced E‐region conductance, caused both by solar photoionization and particle precipitation. We introduce a new quantity named the steepening slope index (SSI) which we use to estimate the occurrence rate of break‐points in sampled plasma densities. We provide an interpretation of SSI in the context of solar photoionization‐induced conductance enhancements of the E‐region. We present a comprehensive climatology of the SSI occurrence rate, along with statistics documenting characteristic high‐latitude plasma density spectra. In the absence of steepening, the typical spectral index is 2.1. When density spectra steepen, the index is typically 1.6 at large scales, and 2.7 at small scales. We discuss the impact of high‐energy deeply penetrating electron precipitation in the diffuse aurora, and precipitating electrons in the aurora at large. Here, a key finding is that near the cusp, where the F‐region conductance is enhanced, spectra tend not to steepen. We find that both the diffuse and discrete aurora are modulating F‐region plasma irregularity dissipation through an enhancement of E‐region conductance, highlighting the role played by factors other than solar zenith angle in high‐latitude plasma dynamics. The influence of E‐region conductance on spectral shapes indicates the need for a new discussion of how particle precipitation can structure the local winter high‐latitude F‐region ionosphere. Plain Language Summary: While the growth of turbulent plasma structures in the high‐latitude ionosphere has been paid much attention, the dissipation or decay of these structures has evidently not. By analyzing a massive amount of data from the European Space Agency's Swarm mission, we can create a map of turbulent structure decay in the polar and sub‐polar regions of Earth. Perhaps surprisingly, we find that turbulence and dissipation in fact go hand in hand. Both extreme ultraviolet radiation from the Sun and energetic particles in the aurora are causing widespread plasma turbulence dissipation. Key Points: We present a new index to process break‐points and subsequent steepening in plasma density spectra at high latitudes on a systematic basisWhen the E‐region conductance is high, there is a strong tendency for spectra to steepen at the scale interval between 40 and 1 kmThere is a tendency for spectra not to steepen near the cusp, where F‐region plasma density and turbulence is enhanced [ABSTRACT FROM AUTHOR]

The accuracy and feasibility of the traditional XY model of transformer oil–paper insulation system are disputable since it ignored the effect of non‐uniform aging and conductance on dielectric response property. Given this issue, this work attempted to report a modified XY model to overcome these defects. The novelty of this work is in the exploration of the modified XY model as a potential tool for establishing the quantitative correlation among the complex relative permittivity of the liquid insulation, solid insulation, and liquid–solid composite insulation. In that respect, the presented verification experiments proved the feasibility and accuracy of the reported model. The contributions are expected to provide a theoretical basis for the condition evaluation of transformer solid insulation under non‐uniform aging conditions. [ABSTRACT FROM AUTHOR]

Enhanced precipitation of magnetospheric energetic electrons during substorms increases ionospheric electron density and conductance. Such enhancements, which have timescales of a few hours, are not reproduced by the existing ionospheric models. We use the linear prediction filter (LPF) method to reconstruct the substorm‐related response of electron densities and integral conductances from long‐term ionospheric observations made by the European Incoherent SCATer radar located at Tromsø. To characterize the intensity of substorm dipolarization at a 5 min time step, we use the midlatitude positive bay index. We build response functions (LP filters) as a function of substorm time between T0−1 h and T0 + 4 h (T0 is a substorm onset time) in different magnetic local time (MLT) sectors to estimate the magnitude and delays of the ionospheric density response at different altitudes. Systematic and large relative changes are mostly observed in the D‐ and E regions. The duration of the response is about 3 h. It starts and reaches maximum magnitude near midnight, propagating from there toward the east and decaying after passing into the noon‐evening sector. The reliability of LPF results is confirmed by the consistency of D‐region response with independently derived response of the auroral absorption. Whereas strong ionization increases are seen in both E‐ and D‐regions on the nightside, the D‐region response is stronger in the morning‐dayside sector. Such MLT variation corresponds to the drift motion and precipitation of the high‐energy electrons injected in the nightside magnetosphere during substorm dipolarization. The inferred ionization changes result in strong enhancements of integral Hall (and Pedersen) conductance in the nightside auroral zone, where intense auroral currents are known to occur during substorms Key Points: Substorm‐related relative increase of electron density is small in F‐ and large in D and E regions, it mainly increases Hall conductanceThe electron density and conductance response starts near midnight at substorm onset, propagates eastward and decays after passing noonStrongest D‐region response in the pre‐noon MLT sector suggesting hard electron precipitation is observed [ABSTRACT FROM AUTHOR]

This paper proposes a power sharing control scheme for power electronics interfaced distributed generation to attain accurate harmonic power dispatch as well as unbalanced power sharing. The proposed controller is composed of two main blocks: 1) a harmonic power sharing unit, which leads to an accurate harmonic power sharing, and 2) individual triple‐droop control units separately applied to the control unit of each phase, which properly provide unbalanced power sharing. For this purpose, a virtual harmonic conductance concept is developed to control the inherent impedance of the inverter under non‐linear load conditions. As a result, the fundamental power sharing performance as well as the harmonic power dispatch accuracy is ensured. Simulation results from an islanded microgrid prototype using the CIGRE low‐voltage distribution network are provided to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

To solve the problem of difficult location (especially high grounding resistances) for single‐phase grounding faults in distribution networks, a fault location method based on equivalent admittance distortion rate is proposed in this paper. The equivalent admittance distortion rates are first obtained by measuring the pre‐fault and post‐fault equivalent admittances of each phase, each feeder and each section. Then the phase with the largest equivalent admittance distortion rate in each phase is determined as the fault phase, the feeder with the largest equivalent admittance distortion rate in each feeder is determined as the fault feeder, and the section with the largest equivalent admittance distortion rate in each section is determined as the fault section. Moreover, a fault identification strategy for single‐phase grounding faults is proposed to improve the robustness of this method. By measuring bus voltages and currents before and after faults, the fault type with only one‐phase in which voltage decreased and current increased is identified as single‐phase grounding faults. Compared with the existing methods, simulation results show that the proposed method is simple to implement and has strong robustness to high grounding resistances, long grounding distances and interference harmonics. [ABSTRACT FROM AUTHOR]

We present an investigation of polar cap plasma structure lifetimes. We analyze both simulated data from ionospheric models (International Reference Ionosphere model and Mass Spectrometer Incoherent Scatter model) and in situ data from the Swarm satellite mission (the 16 Hz Advanced Plasma Density dataset). We find that the theoretical prediction that E-region conductance is a predictor of F-region polar cap plasma structure lifetimes is indeed supported by both in situ-based observations and by ionospheric models. In situ plasma structure lifetimes correlate well with the ratio of F- to E-region conductance. We present explicit predictions of small scale (~1 km) structure lifetimes, which range from less than 1 h during local summer to around 3 h during local winter. We highlight a large discrepancy between the observational and theoretical scale-dependency of decay due to diffusion. [ABSTRACT FROM AUTHOR]

This study proposes an alternative method to calculate the transient responses of multi‐conductor overhead transmission lines based on ABCD representation, recursive convolutions and numerical method for rational approximation in the frequency‐dependent curves. In the classical universal line model, the characteristic admittance matrix Yc(ω) and propagation matrix H(ω) are represented by rational functions. In H(ω), previous and correct identification of the modal travelling times is required. However, these modal travelling times are estimated numerically, which do not offer good accuracy in some cases. This fact has a considerable effect on the rational representation of H(ω) itself and consequently on the transient responses. In the alternative method, a previous estimation of the modal travel times is unnecessary because when using the ABCD representation for each propagation mode, a direct relation exists between the currents and tensions of the receiving and sending ends. These relationships are fitted by smooth rational functions, and then, using recursive convolution methods, the authors obtain the explicit equations of the currents and voltages to calculate the transient responses. The results demonstrate that the alternative method is accurate when compared with the frequency‐domain solution of the transmission line transformed to the time domain using the numeric Laplace transform and with the Bergeron method. [ABSTRACT FROM AUTHOR]

Ionospheric conductivity perpendicular to the magnetic field plays a crucial role in the electrical coupling between planetary magnetospheres and ionospheres. At Jupiter, it controls the flow of ionospheric current from above and the closure of the magnetosphere‐ionosphere circuit in the ionosphere. We use multispectral images collected with the Ultraviolet Spectral (UVS) imager on board Juno to estimate the two‐dimensional distribution of the electron energy flux and characteristic energy. These values are fed to an ionospheric model describing the generation and loss of different ion species, to calculate the auroral Pedersen conductivity. The vertical distributions of H3+, hydrocarbon ions, and electrons are calculated at steady state for each UVS pixel to characterize the spatial distribution of electrical conductance in the auroral region. We find that the main contribution to the Pedersen conductance stems from collisions of H3+and heavier ions with H2. However, hydrocarbon ions contribute as much as 50% to Σp when the auroral electrons penetrate below the homopause. The largest values are usually associated with the bright main emission, the Io auroral footprint and occasional bright emissions at high latitude. We present examples of maps for both hemispheres based on Juno‐UVS images, with Pedersen conductance ranging from less than 0.1 to a few mhos. Plain Language Summary: One of the quantities characterizing the ability of ionospheres to carry currents perpendicular to the magnetic field is the altitude integrated Pedersen conductivity. On Jupiter, it is an important quantity that partly controls how electric currents can flow between the magnetosphere and the high‐latitude ionosphere. It is therefore a key element in the understanding of how and where the Jovian aurora is formed and an important input to numerical models of auroral precipitation. We use observations from the UltraViolet spectral imager near Juno's closest approach to Jupiter to remotely characterize the flux of energy carried by the auroral electrons and their mean energy. These quantities are evaluated for each instrumental pixel and used as inputs to a model to map the Pedersen integrated conductivity. The main contributions to the conductance are caused by collisions between H3+ and hydrocarbon ions such as CH5+ and C3Hn+ with neutral constituents. We present examples of Pedersen conductance maps for both hemispheres. We find that the conductance is spatially very variable with values ranging from less than 0.1 to several mhos. The largest values are usually associated with the bright main emission, the Io auroral footprint and occasional bright emissions at high latitude. Key Points: Multispectral auroral observations from UVS‐Juno are used to map the auroral ionospheric Pedersen conductance in both hemispheresH3+ and hydrocarbon ions make most of the contribution to auroral ionospheric conductanceThe conductance varies from less than 0.1 up to several mhos in the main aurora, high latitude precipitation, and Io magnetic footprint [ABSTRACT FROM AUTHOR]

Nearly all studies of impulsive magnetic perturbation events (MPEs) with large magnetic field variability (dB/dt) that can produce dangerous geomagnetically induced currents (GICs) have used data from the Northern Hemisphere. Here we present details of four large‐amplitude MPE events (|ΔBx| > 900 nT and |dB/dt| > 10 nT/s in at least one component) observed between 2015 and 2018 in conjugate high‐latitude regions (65–80° corrected geomagnetic latitude), using magnetometer data from (1) Pangnirtung and Iqaluit in eastern Arctic Canada and the magnetically conjugate South Pole Station in Antarctica and (2) the Greenland West Coast Chain and two magnetically conjugate chains in Antarctica, AAL‐PIP and BAS LPM. From one to three different isolated MPEs localized in corrected geomagnetic latitude were observed during three premidnight events; many were simultaneous within 3 min in both hemispheres. Their conjugate latitudinal amplitude profiles, however, matched qualitatively at best. During an extended postmidnight interval, which we associate with an interval of omega bands, multiple highly localized MPEs occurred independently in time at each station in both hemispheres. These nighttime MPEs occurred under a wide range of geomagnetic conditions, but common to each was a negative interplanetary magnetic field Bz that exhibited at least a modest increase at or near the time of the event. A comparison of perturbation amplitudes to modeled ionospheric conductances in conjugate hemispheres clearly favored a current generator model over a voltage generator model for three of the four events; neither model provided a good fit for the premidnight event that occurred near vernal equinox. Key Points: Conjugate premidnight MPEs were largest in dBx/dt and were often but not always simultaneous to within 3 min over ~100–700 km in latitudeConjugate postmidnight MPEs were associated with omega bands, often largest in dBy/dt, very localized, and independent in time over ~1.5 hrPerturbation amplitudes and maximum derivatives favored a current generator model over a voltage generator model for near‐solstice events [ABSTRACT FROM AUTHOR]

Aim: This study evaluated the effectiveness and safety of rapid and slow rehydration in children aged 6-60 months with dehydrating diarrhoea and severe malnutrition.Methods: A randomised controlled trial was conducted from July 2011 to March 2014 at the International Centre for Diarrhoeal Disease Research Bangladesh. We included children with weight for age and, or, weight for length Z-scores of less than -3 or with bipedal oedema and acute diarrhoea with severe dehydration. The children received intravenous fluid at different rates: 105 rapidly over six hours and 103 slowly over the 12 hours recommended by the World Health Organization.Results: All the children were successfully rehydrated. The admittance weights were similar for the slow and rapid groups: 8.4 kg and 8.3 kg. After 24 hours, the mean percentage weight gain was 8.5% and 9.0%, respectively. This confirmed that most of the children had been suffering from severe dehydration on admission. The respective proportions of children who received unscheduled intravenous fluid were 18% and 17%. None developed fluid overload or heart failure and most recovered normal renal function after rehydration.Conclusion: Rapid rehydration saved time, was as safe as slow rehydration and was a better option for dehydrating diarrhoea and severe malnutrition. [ABSTRACT FROM AUTHOR]

A circuit analogy for magnetosphere‐ionosphere current systems has two extremes: the voltage generator (when the ground magnetic response is proportional to the ionospheric conductance) and the current generator (when the ground magnetic response practically does not depend on the ionospheric conductance). Nonsteady field‐aligned currents interact with the ionosphere in a different way depending on the ratio between the driver time scale τ and the Alfven field line eigenperiod TA. Sudden Commencement (SC) impulses at high latitudes correspond to the situation when τ≪TA. This case of Alfven pulses propagating independently away from the equatorial plane is analytically examined with the magnetospheric plasma box model with thin asymmetric conjugate ionospheres. At high latitudes the amplitude ratio in conjugate ionospheres in general does not correspond directly to either the current or voltage regimes. Theoretical predictions are supported by examples of typical SC event observations at conjugate magnetometer sites in Greenland and Antarctica during summer and winter periods. Key Points: Interhemispheric properties of Alfvenic pulses with duration less than field line eigenperiod must differ from larger period disturbancesAt high latitudes the amplitude ratio in conjugate ionospheres in general does not correspond directly to either current or voltage regimesInterhemispheric asymmetry of SC amplitudes at Greenland and Antarctica magnetometers corresponds qualitatively to the Alfvenic pulse model [ABSTRACT FROM AUTHOR]

This article develops an efficient solution to design beam‐scanning transmitarray (TA). The four‐layer unit associated with the focal planar substrate integrated waveguide (SIW) array is presented and characterized. The proposed linearly polarized TA is implemented as four‐layer sheet admittance composed of the subwavelength unit, whose transmission feature would be accurate analyzed by the equivalent circuit model. The phase layout of TA is optimized by using the PMM method in order to achieve a wide scanning behavior and reduce the scan loss. Arc‐shaped SIW horn antenna array is adopted as the feeding source. Artificial impedance surfaces printed on either side against the low‐profile substrate results in a greatly enhanced radiation performance. The TA and feeds presented at 20 GHz are both fabricated using standard PCB processing. The measured results show a greatly improved ±45° scan range with the gain loss of 0.73 dBi by switching the SIW horn antenna. Good radiation and bandwidth characters are performed in all states of operation for both ports, confirmed the effectiveness of proposed design process. [ABSTRACT FROM AUTHOR]

Thermal admittance spectroscopy and capacitance‐voltage measurements are well established techniques to study recombination‐active deep defect levels and determine the shallow dopant concentration in photovoltaic absorbers. Applied to thin‐film solar cells or any device stack consisting of multiple layers, interpretation of these capacitance‐based techniques is ambiguous at best. We demonstrate how to assess electrical measurements of thin‐film devices and develop a range of criteria that allow to estimate whether deep defects could consistently explain a given capacitance measurement. We show that a broad parameter space, achieved by exploiting bias voltage, time, and illumination as additional experimental parameters in admittance spectroscopy, helps to distinguish between deep defects and capacitive contributions from transport barriers or additional layers in the device stack. On the example of Cu(In,Ga)Se2 thin‐film solar cells, we show that slow trap states are indeed present but cannot be resolved in typical admittance spectra. We explain the common N1 signature by the presence of a capacitive barrier layer and show that the shallow net dopant concentration is not distributed uniformly within the depth of the absorber. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the synthesis problem of one‐port mechanical networks consisting of one damper, one inerter, and a finite number of springs, where the damping coefficient and inertance are some values in given intervals. Due to the construction limitation, the element values of dampers and inerters are usually required to be constrained in certain ranges instead of any positive values. A necessary and sufficient condition is derived for any positive‐real admittance to be realizable as such class of networks, which is in terms of the coefficients of the admittance and the upper and lower bounds of element value constraints. Moreover, the corresponding synthesis procedure is presented based on the derivation process and realizations of three‐port spring networks. Finally, numerical examples are given for illustration. The results of this paper can be utilized in the design of inerter‐based mechanical control systems. [ABSTRACT FROM AUTHOR]

The present study shows that the ionospheric Hall polarization can deform the high‐latitude ionospheric convection field, which is widely considered to be a manifestation of the convection field in the magnetosphere. We perform the Hall polarization field separation with a potential solver by changing the conductance distribution step by step from a uniform one to a more realistic one. We adopt dawn‐dusk and north‐south symmetric distributions of conductance and region 1 (R1) field‐aligned current (FAC). The pair of the primary field of the R1 system and each gradient of off‐diagonal component of conductance tensor (Hall conductance) generates the Hall polarization field and consequently causes potential deformations as follows. (a) The equatorward gradient causes clockwise rotation. (b) The gradient across the terminator, together with the effect of the equatorward gradient, causes the dawn‐dusk asymmetry. (c) The high conductance band in the auroral region causes kink‐type deformations. In particular, a nested structure at the equatorward edge of the band in the midnight sector well resembles the Harang Reversal. Result (a) can explain the clockwise bias inexplicable by the IMF‐By effect alone, the combination of (a) and (b) can explain the clearness and unclearness in the round or crescent shapes of the dawn‐dusk cells depending on the IMF‐By polarity, and (c) suggests that the ionosphere may not need the upward‐FAC for the formation of the Harang Reversal. We suggest that the final structure of the ionospheric potential is established by the combined effects of the magnetospheric requirements (external causes) and ionospheric polarization (internal effect). Key Points: Ionospheric Hall polarization field generated by the off‐diagonal conductance (Hall conductance) nonuniformity causes potential deformationLatitudinal and terminator gradient of off‐diagonal conductance causes clockwise rotation and dawn‐dusk asymmetry of the two‐cell potentialA structure resembling the Harang Reversal is generated by the Hall polarization field without an upward field‐aligned current [ABSTRACT FROM AUTHOR]

Background: Initially after tattooing, the skin barrier function is broken. However, the long‐term impact of clinically healed tattoos on this has never been studied. The aim was to investigate the long‐term effect on the skin barrier function in normal tattoos and examples of tattoos with chronic inflammatory complication. Methods: Participants were recruited from the "Tattoo clinic" of the Dermatological Department on Bispebjerg Hospital in Denmark, where patients with complicated tattoo reactions are treated. Transepidermal water loss (TEWL), conductance, capacitance, and pH were measured in tattooed skin with regional control measurements in normal non‐tattooed skin. Natural moisturizing factor (NMF) was measured in collected tape strips. Results: Twenty six individuals with 28 tattoos were included, that is, 23 normal tattoos without any pathologic reaction and 5 tattoos with chronic inflammatory complications. No significant differences were found in tattooed versus non‐tattooed skin with respect to TEWL (median values 6.6 vs 7.2 g/m2/h), conductance (76 vs 78 a.u.), pH (5.94 vs 5.79), and NMF (0.58 vs 0.59 mmol/g protein). Capacitance (64 vs 57 a.u.) was higher in tattooed skin compared to non‐tattooed skin (P = 0.006). Similar results were found in tattoos with inflammatory reactions. Conclusion: Overall, skin tattoos do not affect the long‐term skin barrier function markedly. The skin capacitance was, however, affected in tattooed skin areas compared to non‐tattooed skin areas. [ABSTRACT FROM AUTHOR]

A high resistivity PD‐SOI MOSFET equivalent circuit model including a parallel connection of intrinsic output capacitance and conductance with frequency‐dependent empirical equations is newly proposed to accurately simulate their abrupt change in the low‐frequency region. This new empirical model is superior to a conventional RC one, because equivalent circuit structure and parameter extraction process are simpler. Better agreements with measured Y22‐parameter are obtained for the new model than the conventional one. [ABSTRACT FROM AUTHOR]

Multi-terminal DC (MTDC) transmission system is one of the effective technical means to perform a wide range connection of energy and load centres, also it has strong competitiveness and is economic efficiency. This study proposes full-scale studies on engineering application architecture of an MTDC system. Firstly, advantages and weaknesses of several typical types of MTDC are analysed, and based on the LCC parallel MTDC (P-MTDC) system, which is most applicable among all types, detailed studies are done on main topology, including polarity-reversal switches to realise power reversion; secondly, P-MTDC main circuit calculation method is presented, which decoupled the main circuit calculation into two parts: DC network and converter equation calculation, and general admittance matrix of the DC network is deduced in the study; thirdly, a novel constant-U control strategy is proposed to simplify the control logic and reduce the control system complexity, by means of setting the nearest point of common coupling from the rectifier station as the voltage control reference point. Finally, one practical case study is taken, for example, of a certain three-terminal DC project in the world, rated DC parameters are calculated, and a simulation model of MTDC system is built on Electro Magnetic Transient in DC System (EMTDC). The validity of the polarity-reversal control strategy proposed in the study is demonstrated by simulation. [ABSTRACT FROM AUTHOR]

This paper proposes a maximum power point tracking (MPPT) method with partial shading (PS) detection based on modified PI incremental conductance (IC) for photovoltaic inverters. To accurately trigger the algorithm, a PS detecting approach based on voltage deviation is derived through the comparison of voltage and current characteristics under uniform and non-uniform insolation. To track the global maximum power point (GMPP) precisely and fast, a global search scheme considering appropriate voltage reference, search direction and termination criteria is presented. The modified PI-based IC method is implemented in the local search process. In order to verify the effectiveness of the algorithm, the proposed method is utilised in the two-stage grid-connected photovoltaic inverters built in MATLAB/Simulink. The performance of the scheme is compared with the traditional IC method under step-changing and gradual-changing insolation and various temperature. In all simulation cases, the proposed approach can identify the PS with multiple local maxima, accurately trigger the global search process and track the GMPP. The search periods are around 0.1–0.2 s, and the efficiencies of PV generation under steady state are normally above 99.5%. The presented method can improve the efficiency of distributed and centralised PV system. [ABSTRACT FROM AUTHOR]

A polymesomorphic thermal phase‐transition of a macrocyclic amphiphile consisting of aromatic groups and oligoethylene glycol (OEG) chains is reported. The macrocyclic amphiphile exists in a highly‐ordered liquid crystal (LC) phase at room temperature. Upon heating, this macrocycle shows phase‐transition from columnar‐lamellar to nematic LC phases followed by crystallization before melting. Spectroscopic studies suggest that the thermally induced crystallization is triggered by a conformational change at the OEG chains. Interestingly, while the macrocycle returns to the columnar‐lamellar phase after cooling from the isotropic liquid, it retains the crystallinity after cooling from the thermally‐induced crystal. Thanks to this bistability, conductance switching was successfully demonstrated. A different macrocyclic amphiphile also shows an analogous phase‐transition behavior, suggesting that this molecular design is universal for developing switchable and memorizable materials, by means of hysteretic phase‐transition processes. Going through phases: A macrocyclic amphiphile with a multiblock structure shows a polymesomorphic thermal phase‐transition from a highly‐ordered liquid crystalline phase to a nematic phase and crystallization before melting upon heating. The amphiphile retains the crystallinity after cooling from the thermally‐induced crystal, while cooling from the isotropic liquid resulted in the return to the liquid crystalline phase. This hysteretic bistability enables conductance switching by the thermal process. [ABSTRACT FROM AUTHOR]

A circuit analogy for magnetosphere‐ionosphere current systems has two extremes for drivers of ionospheric currents: the "voltage generator" (ionospheric electric fields/voltages are constant, while current varies) and the "current generator" (current is constant, while the electric field varies). Here we indicate another aspect of the magnetosphere‐ionosphere interaction, which should be taken into account when considering the current/voltage dichotomy. We show that nonsteady field‐aligned currents interact with the ionosphere in a different way depending on a forced driving or resonant excitation. A quasi‐DC driving of field‐aligned current corresponds to a voltage generator, when the ground magnetic response is proportional to the ionospheric Hall conductance. The excitation of resonant field line oscillations corresponds to the current generator, when the ground magnetic response only weakly depends on the ionospheric conductance. According to the suggested conception, quasi‐DC nonresonant disturbances correspond to a voltage generator. Such ultralow frequency (ULF) phenomena as traveling convection vortices and Pc5 waves should be considered as the resonant response of magnetospheric field lines, and they correspond to a current generator. However, there are quite a few factors that may obscure the determination of the current/voltage dichotomy. Key Points: Quasi‐DC driving of FAC corresponds to voltage generator, when ground response is proportional to ionospheric conductanceResonant driving corresponds to current generator, when ground response weakly depends on local ionospheric conductanceDayside TCVs and Pc5 ULF waves should be considered as a result of current generator [ABSTRACT FROM AUTHOR]

Impedance analysis has been widely used in small‐signal stability analysis of power systems and power electronic device. This study proposes an iterative approach to impedance model of individual device. The proposed method applies numerical iteration in the calculation of impedance model instead of complex mathematical derivation. It is easy to be implemented in computer programs. First, initial value of a key impedance/admittance of the target device is set. Second, an iterative algorithm is designed according to structure of the device and transfer functions of its components. Finally, the equivalent impedance is computed and stability characteristics of the whole system are analysed. The obtained model could include all elements of the target device, such as phase‐locked loop and shaft system. Thus, it could also be applied to the analysis of sub‐synchronous control interaction and torsional interaction. The proposed method could provide impedance contribution from different parts of the target device. This character will benefit the analysis and solution of system instability. [ABSTRACT FROM AUTHOR]

A right isosceles triangular waveguide fed longitudinal slot has been analysed in this Letter by employing the method of moments. The internal admittance has been evaluated by using the image technique to simplify the problem from that of a slot in a triangular waveguide wall to that of two slots in a square waveguide, one each in an adjacent wall. A triangular waveguide has been fabricated and measurements have been taken on slots cut in one of the two equal sides of the triangular waveguide. It has been shown that the theoretical results agree well with the measured results. The theory is useful in the design of triangular waveguide fed slot arrays. [ABSTRACT FROM AUTHOR]

Summary: The influence of the end part of the scroll on the pumping characteristics and indicated power of the oil free scroll vacuum pump is considered. With the help of developed mathematical model of the scroll pump dependence of pumping speed on the inlet pressure at different curvature radii of the scroll end part and compression duration is obtained. The influence of compression duration on the ultimate pressure and delivery rate is examined. Dependence of the indicated power on the inlet pressure at different number of scroll wraps and compression duration is calculated. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a new method to easily and rapidly extract RF figures of merit of MOSFET transistors. Using DC and low frequency measurements, the extrinsic resistances (Rg, Rs, Rd), the intrinsic conductances (gm, gd), and the input capacitance Cgg have been extracted. The evaluation of these parameters has enabled to compute 2 RF figures of merit (FoM), namely, the current gain cutoff frequency fT and the maximum oscillation frequency fmax. It has been shown that both the proposed method and the conventional RF extraction technique give quite close values. [ABSTRACT FROM AUTHOR]

Abstract: The active zone of presynaptic nerve terminals organizes the neurotransmitter release machinery, thereby enabling fast Ca2+‐triggered synaptic vesicle exocytosis. BK‐channels are Ca2+‐activated large‐conductance K+‐channels that require close proximity to Ca2+‐channels for activation and control Ca2+‐triggered neurotransmitter release by accelerating membrane repolarization during action potential firing. How BK‐channels are recruited to presynaptic Ca2+‐channels, however, is unknown. Here, we show that RBPs (for RIM‐binding proteins), which are evolutionarily conserved active zone proteins containing SH3‐ and FN3‐domains, directly bind to BK‐channels. We find that RBPs interact with RIMs and Ca2+‐channels via their SH3‐domains, but to BK‐channels via their FN3‐domains. Deletion of RBPs in calyx of Held synapses decreased and decelerated presynaptic BK‐currents and depleted BK‐channels from active zones. Our data suggest that RBPs recruit BK‐channels into a RIM‐based macromolecular active zone complex that includes Ca2+‐channels, synaptic vesicles, and the membrane fusion machinery, thereby enabling tight spatio‐temporal coupling of Ca2+‐influx to Ca2+‐triggered neurotransmitter release in a presynaptic terminal. [ABSTRACT FROM AUTHOR]

Silicon nanowires (SiNW) are highly sensitive to biomolecules. In some publications, changes of SiNW conductance in relation to their concentration levels are displayed. Upon binding, biomolecule charges change the surface potential and, thereby, the SiNW conductance. We discussed earlier that SiNWs can be regarded as long‐channel, ion‐sensitive field‐effect transistors (ISFETs). The choice of a stable working point is important and defines the SiNW conductance. The common detection principle is based on the shift in threshold voltage. Regardless of conductance change or threshold voltage shift, relative values are related to biomolecule concentrations. However, potentiometric detection suffers from Debye screening of biomolecule charges by counter ions of the test solution. This makes biosensing in physiological buffer solutions difficult if not impossible. In this report, a method for impedance sensing with SiNWs, which was earlier used for ISFET devices is introduced. This method gains comparable results to potentiometric sensing. The change of interface impedance is indirectly linked with the biomolecule charges. In addition, the dielectric property of the interface layer plays an important role. At elevated frequencies, our method can be regarded as an alternative mechanism similar to dielectric spectroscopy at low frequencies. Thereby, Debye screening does no longer dominate the recordings. [ABSTRACT FROM AUTHOR]

Abstract: Inspirited by the wide range of applications of graphene and the similarity between boron and carbon, 2D boron sheets have gained extensive research interest. In this work, using first‐principles combined with a nonequilibrium Green's function method, thermal conductance of fully hydrogenated borophene, named borophane, is studied. Interestingly and in contrast to widely perceived sense, at 300 K, it is found that the thermal conductance of borophane in the armchair direction is remarkably larger than that of graphene. More interesting, a dimensionality crossover is observed in phonon transmission where low‐frequency phonons exhibit 2D characteristic, while high‐frequency phonons behave like a 1D system, oriented along armchair direction, which results in the ultrahigh thermal conductance. An anomalous increase of thermal conductance with uniaxial tensile strain is observed, which is well explained by the unique puckered structure and chemical bonding in borophane. The excellent in‐plane stiffness and flexibility together with the high thermal conductance suggest that borophane is promising for soft thermal channel. Moreover, this unique dimensionality crossover in phonon transmission offers a perfect platform for studying the effect of phonon population in mode space, which is of primary importance for thermal transport in low‐dimensional systems. [ABSTRACT FROM AUTHOR]

Herein, the spectral and transport properties in the finite phosphorene lattice are investigated using the tight‐binding model in the presence of Anderson disorder potential. The focus is on the zig‐zag edge states localization, provided by the numerically calculated inverse participation number. At low disorder, the zig‐zag states undergo a localization process, keeping their 1D character, while further increasing the disorder leads to delocalization due to hybridization with the extended 2D states. The disorder‐induced changes in the electronic conductance, from one zig‐zag edge to the other, are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Shewanella oneidensis MR‐1 gains energy by extracellular electron transfer to solid surfaces. They employ c‐type cytochromes in two Mtr transmembrane complexes, forming a multiheme wire for electron transport across the cellular outer membrane. We investigated electron‐ and hole‐transfer mechanisms in the external terminal of the two complexes, MtrC and MtrF. Comparison of computed redox potentials with previous voltammetry experiments in distinct environments (isolated and electrode‐bound conditions of PFV or in vivo) suggests that these systems function in different regimes depending on the environment. Analysis of redox potential shifts in different regimes indicates strong coupling between the hemes via an interplay between direct Coulomb and indirect interactions through local structural reorganization. The latter results in the screening of Coulomb interactions and explains poor correlation of the strength of the heme‐to‐heme interactions with the distance between the hemes. [ABSTRACT FROM AUTHOR]

In this article the operation and thermal conductance of a series of quantum cascade lasers (QCLs) emitting at 4.6 μm grown with between 5 and 30 cascades in the active region is analyzed. A reduced number of cascades, but with fixed active region design, results in larger threshold current density but lower threshold power density. An analysis of the temperature gradient in the active region implies that for continuous‐wave QCL operation, using fewer than 15 cascades in the active region is advantageous, especially for broad‐area structures. We demonstrate a QCL with 10 cascades operating in continuous‐wave mode at room temperature emitting 0.9 W from a 4 mm × 30 μm stripe. [ABSTRACT FROM AUTHOR]

Abstract: Leaf photosynthesis of crops acclimates to elevated CO2 and temperature, but studies quantifying responses of leaf photosynthetic parameters to combined CO2 and temperature increases under field conditions are scarce. We measured leaf photosynthesis of rice cultivars Changyou 5 and Nanjing 9108 grown in two free‐air CO2 enrichment (FACE) systems, respectively, installed in paddy fields. Each FACE system had four combinations of two levels of CO2 (ambient and enriched) and two levels of canopy temperature (no warming and warmed by 1.0–2.0°C). Parameters of the C3 photosynthesis model of Farquhar, von Caemmerer and Berry (the FvCB model), and of a stomatal conductance (gs) model were estimated for the four conditions. Most photosynthetic parameters acclimated to elevated CO2, elevated temperature, and their combination. The combination of elevated CO2 and temperature changed the functional relationships between biochemical parameters and leaf nitrogen content for Changyou 5. The gs model significantly underestimated gs under the combination of elevated CO2 and temperature by 19% for Changyou 5 and by 10% for Nanjing 9108 if no acclimation was assumed. However, our further analysis applying the coupled gs–FvCB model to an independent, previously published FACE experiment showed that including such an acclimation response of gs hardly improved prediction of leaf photosynthesis under the four combinations of CO2 and temperature. Therefore, the typical procedure that crop models using the FvCB and gs models are parameterized from plants grown under current ambient conditions may not result in critical errors in projecting productivity of paddy rice under future global change. [ABSTRACT FROM AUTHOR]

Abstract: A novel series of 1,2,3‐substituted ferrocene‐based wires a1–a2 and b4–b5 have been synthesized by using an iterative Pd‐mediated Sonogashira cross‐coupling methodology. The molecular structures of a2 and b3 were determined by single‐crystal X‐ray analysis. Electrochemical data showed that there was a strong electronic communication among the ferrocenyl moieties in b1–b5. The UV absorption spectra indicated that replacing the 1,1′‐substituted ferrocene unit with a 1,2,3‐substituted ferrocene moiety causes delocalization of electrons in the extended π orbitals. The self‐assembled monolayers of wire a1 and a2 on Au surfaces have been comprehensively characterized by electrochemistry and scanning tunneling microscopy break junction. The data demonstrated that 1,2,3‐substituted ferrocene‐based wires reduced the intermolecular π–π stacking, and furthermore solved the rotation problem in the 1,1′‐substituted ferrocene‐based wires. [ABSTRACT FROM AUTHOR]

We calculate an AC response of the edge states of a two‐dimensional topological insulator, which can exchange electrons with a conducting puddle in the bulk of the insulator. This exchange leads to finite corrections to the response of isolated edge states both at low and high frequencies. By comparing these corrections, one may determine the parameters of the puddle. [ABSTRACT FROM AUTHOR]

Abstract: Threshold switches with Ag or Cu active metal species are volatile memristors (also termed diffusive memristors) featuring spontaneous rupture of conduction channels. The temporal dynamics of the conductance evolution is closely related to the electrochemical and diffusive dynamics of the active metals which could be modulated by electric field strength, biasing duration, temperature, and so on. Microscopic pictures by electron microscopy and quantitative thermodynamics modeling are examined to give insights into the underlying physics of the switching. Depending on the time scale of the relaxation process, such devices find a variety of novel applications in electronics, ranging from selector devices for memories to synaptic devices for neuromorphic computing. [ABSTRACT FROM AUTHOR]

In this work, a novel approach for the computer-aided noise analysis of a multiwall carbon nanotube (MWCNT) is proposed. A transmission line model of the MWCNT and a noise correlation matrix based on admittance representation are used for the computer-aided noise analysis. This work presents a simple, fast and effective noise analysis approach for the MWCNT. The noise figure is computed for different values of the parameters of the MWCNT for determining the effects of parameter values on the noise figure of the MWCNT. The results of the computer-aided noise analysis of the MWCNT are given and discussed in detail. According to the results, the variation of the distance from the ground plane of the outer shell has little effect on the value of noise figure, when the value of inner radius or the total number of shells increases the value of noise figure decreases. Therefore the noise figure decreases with increasing diameter because the diameter increases with the increasing value of inner radius and the total number of shells. The value of noise figure increases when the value of nanotube length or physical absolute temperature increases. The value of noise figure decreases with the decreasing value of source admittance. [ABSTRACT FROM AUTHOR]

Conjugated polyelectrolytes (CPEs) are a focus of research because combine their inherent electrical conductivity and the ability to interact with ions in aqueous solutions or biological systems. However, it is still not understood to what degree the counter ion in CPEs influences the properties of the CPE itself and the performance of electronic transducers. In order to investigate this, three different conjugated polyelectrolytes, poly(6-(thiophen-3-yl)hexane- 1-sulfonate)s (PTHS--X+), are synthesized, which have the same polythiophene backbone but different X+ counter ions: the bulky tetrabutylammonium (TBA+), tetraethylammonium (TEA+), and the smallest tetramethylammonium (TMA+). At the interface with biological systems, thin CPE films have to be stable in an aqueous environment and should allow the inward and outward flow of ions from the electrolyte. Since the studied PTHS--X+ have different solubilities in water, the optical properties of pristine PTHS--X+ as well as of crosslinked PTHS--X+ via UV--vis absorption spectroscopy are investigated additionally. PTHS--TMA+ exhibits better aggregation, fast interdiffusion of ions, and fast recovery from the oxidized state. Additionally, spectroelectrochemical and cyclic voltammetric as well as electrochemical capacitance investigations show that PTHS--TMA+ can be oxidized to a higher degree. This leads to a better performance of PTHS--TMA+-based organic electrochemical transistors. [ABSTRACT FROM AUTHOR]

Spin–charge separation is known to be broken in many physically interesting one‐dimensional (1D) and quasi‐1D systems with spin–orbit interaction because of which spin and charge degrees of freedom are mixed in collective excitations. Mixed spin–charge modes carry an electric charge and therefore can be investigated by electrical means. We explore this possibility by studying the dynamic conductance of a 1D electron system with image‐potential‐induced spin–orbit interaction. The real part of the admittance reveals an oscillatory behavior versus frequency that reflects the collective excitation resonances for both modes at their respective transit frequencies. By analyzing the frequency dependence of the conductance the mode velocities can be found and their spin–charge structure can be determined quantitatively. [ABSTRACT FROM AUTHOR]

A method to investigate dc‐network instabilities in multi‐terminal high‐voltage DC (HVDC) systems is presented. The method consists of defining subsystems, called in this Letter Z and Y, which can be interpreted as a dc‐network impedance matrix and as set of converter admittances, respectively. Through the analysis of the Z and Y terms, it is shown that resonances originated from the system's dc network can be amplified if the converters show a negative dc‐side conductance. Moreover, it is also shown that converters located at different terminals can contribute to instability if the resonances to which they are exposed are of the same frequency. The analysis method is applied to a four‐terminal HVDC system as an example and, using the theory developed in this Letter, mitigation measures are applied. The results are verified through time‐domain simulations. [ABSTRACT FROM AUTHOR]

This paper discusses a comprehensive analytical study of electrical properties of single-wall conventional carbon nanotube field-effect transistor (CNTFET) devices of subthreshold swing (SS), transconductance ( gm), and extension resistance. The analytical expressions for SS and gm have been derived based on channel modulated potential. In the study, it was observed that SS value of the CNTFET device is equal to 60 mV/decade, which is smaller than the conventional and double gate metal-oxide-semiconductor field-effect transistors. The subthreshold swing degrades at larger tube's diameter and gate-source voltage due to increased source-drain leakage current. Carbon nanotube field-effect transistor devices achieve larger gm at large gate-source voltage, which has a disadvantage of reducing the allowable voltage swing at the drain. The extension resistance of the device falls with diameter of the tube. [ABSTRACT FROM AUTHOR]