Search

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., Competing Interests: Declarations Competing interests LADS, ABG, and DN declare no conflicting financial interests. MDF has received funding for research grants from Abiomed and CardioVol Corp. JWV discloses a financial relationship with CardioVol Corp., (© 2024. International Federation for Medical and Biological Engineering.)

A major challenge for carbon nanotube (CNT) to become a viable replacement of copper and tungsten in the next-generation on-chip via interconnects is the high contact resistance between CNT and metal electrodes. A first step in meeting this challenge is an accurate characterization of via contact resistance. In this paper, the scanning electron microscope (SEM) image contrast at low landing energy is employed to estimate the conductive CNT area inside vias. The total conductive CNT area inside each via is deduced using SEM image with 0.1 keV landing energy and a specified threshold brightness, yielding via resistance versus CNT area behavior, which correlates well with electrical nanoprobing measurements of via resistance. Monte Carlo simulation of secondary electron generation lends further support for our analysis and suggests that the residue covering the CNT does not affect the conduction across the contact for residue thickness below 1 nm. This imaging and analysis technique can add much value to CNT via interconnect contact characterization. [ABSTRACT FROM AUTHOR]

Besides the peak at one conductance quantum, G0, two additional features at ~0.4 G0 and ~1.3 G0 have been observed in the conductance histograms of silver quantum point contacts at room temperature in ambient conditions. In order to understand such feature, here we investigate the electronic transport and mechanical properties of clean and oxygen-doped silver atomic contacts by employing the non-equilibrium Green's function formalism combined with density functional theory. Our calculations show that, unlike clean Ag single-atom contacts showing a conductance of 1 G0, the low-bias conductance of oxygen-doped Ag atomic contacts depends on the number of oxygen impurities and their binding configuration. When one oxygen atom binds to an Ag monatomic chain sandwiched between two Ag electrodes, the low-bias conductance of the junction always decreases. In contrast, when the number of oxygen impurities is two and the O-O axis is perpendicular to the Ag-Ag axis, the transmission coefficients at the Fermi level are, respectively, calculated to be 1.44 for the junction with Ag(111) electrodes and 1.24 for that with Ag(100) electrodes, both in good agreement with the measured value of ~1.3 G0. The calculated rupture force (1.60 nN for the junction with Ag(111) electrodes) is also consistent with the experimental value (1.66 ± 0.09 nN), confirming that the measured ~1.3 G0 conductance should originate from Ag single-atom contacts doped with two oxygen atoms in a perpendicular configuration. [ABSTRACT FROM AUTHOR]

By applying nonequilibrium Green's function formalism combined first-principles density functional theory, a new mechanism for optical switch of single molecular device with carbon nanotube electrodes is proposed. The molecule comprises the switch can convert between enol and keto isomers upon photoinduced excited state hydrogen transfer in the molecular bridge. Theoretical results show that these two isomers exhibit very different current-voltage characteristics both in armchair and zigzag junction, which can realize the on and off states of the molecular switch. Meantime, the chirality of the single-walled carbon nanotube (SWCNT) electrodes strongly affects the switching characteristics of the molecular junctions. The maximum value of on-off ratio can reach 72 at 1.6V for the switch with zigzag SWCNT electrodes, suggesting potential applications of this junction in future design of light-driven molecular switches. [ABSTRACT FROM AUTHOR]

A noncontact (capacitive-coupled) probe for the measurement of the conductivity of liquids is presented. Insulation introduced between the measurement electrodes and the liquid intrudes a couple of coupling capacitances. Though the capacitive coupling overcomes the problems of electrode polarization and contamination associated with contacting electrodes, the large reactances of the coupling capacitors pose a problem in the measurement of comparatively very small resistance of the liquid. An auto-balancing signal conditioning scheme presented here overcomes the problem posed by the large capacitive reactances and provides directly a measurable output proportional only to the conductance of the liquid. Error analysis of the probe presented herein helps the optimal design of the probe. A worst case error of ± 0.9% was obtained from a prototype noncontact conductivity probe, developed and tested. [ABSTRACT FROM AUTHOR]

Electron transfer reactions can now be followed at the single-molecule level, but the connection between the microscopic and macroscopic data remains to be understood. By monitoring the conductance of a single molecule, we show that the individual electron transfer reaction events are stochastic and manifested as large conductance fluctuations. The fluctuation probability follows first-order kinetics with potential dependent rate constants described by the Butler-Volmer relation. Ensemble averaging of many individual reaction events leads to a deterministic dependence of the conductance on the external electrochemical potential that follows the Nernst equation. This study discloses a systematic transition from stochastic kinetics of individual reaction events to deterministic thermodynamics of ensemble averages and provides insights into electron transfer processes of small systems, consisting of a single molecule or a small number of molecules. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The electronic transport properties of a single diketopyrrolopyrrole molecule connected to different electrodes are studied. • Remarkable NDR behavior can be found in the single diketopyrrolopyrrole molecular device with ZGNR electrode. • The current values of the molecular device are sensitive to the connecting groups obviously. Abstract In present work, we have studied the electronic transport properties of a single diketopyrrolopyrrole molecule connected to the gold electrode or the zigzag graphene nanoribbon electrode via the benzene or the pyrene by performing first-principle quantum transport calculations. The results show that the conductance of the single diketopyrrolopyrrole molecular device can be modulated by changing the electrode. Remarkable negative differential resistance behavior can be found in the single diketopyrrolopyrrole molecular device with zigzag graphene nanoribbon electrode. In addition, we find that the anchoring groups play an important role in the magnitude of the device's current. [ABSTRACT FROM AUTHOR]

Highlights • A single-molecular junction was controlled reversibly by bidirectional motion of a phenyl ring between the Cu(110) surface and the tip of STM. • The effect of atomic-scale oxidation of the electrode on the single-molecule junction conductance was detected for the first time. • The hydroxyl group adsorbed in the vicinity of the molecule was found to reduce the molecular conductance by 30%. Graphical abstract Abstract Electronic conduction through molecular junctions depends critically on the electronic state at the anchor site, suggesting that local reactions on the electrodes may play an important role in determining the transport properties. However, single-molecule junctions have never been studied with the chemical states of the electrodes controlled down to the atomic scale. Here, we study the effect of surface adsorbates on the molecular junction conductance by using a scanning tunneling microscope (STM) combined with density functional theory (DFT) and nonequilibrium Green's function (NEGF) calculations. By vertical control of a STM tip over a phenoxy (PhO) molecule on Cu(110), we can lift and release the molecule against the tip, and thus reproducibly control a molecular junction. Using this model system, we investigate how the conductance changes as the molecule is brought to the vicinity of oxygen atoms or a hydroxyl group chemisorbed on the surface. This proximity effect of surface adsorbates on the molecular conductance is simulated by DFT-NEGF calculations. [ABSTRACT FROM AUTHOR]

Highlights • Electric transport analysis based on dc and small signal admittance spectroscopy. • Evaluation of the equivalent circuit and parasitic resistances. • Electrode potential barriers for injection of free charge carriers. Abstract The objective of this work was to determine electric transport in the organic device based on a planar junction of electron donor and electron acceptor materials, namely ITO/MoO 3 /DBP/F 16 ZnPc/BCP/Ag. The analysis reported herein was based on direct current-voltage measurements and small-signal admittance spectra in the dark and under illumination. Such analysis may provide information on potential barriers, parasitic resistances and presence of space charge affecting the electric current flow within the device. Therefore, this approach could be applied for determination of physical processes related to electric charge transport within multilayer structures, such as photovoltaic cells or photodetectors. In the case of the investigated system, the parallel parasitic resistance, the resistance of electrodes, and the geometric capacitance of 10 MΩ, 55 Ω, and 1.6 nF respectively were found. It was also shown that the direct current flowing from ITO to Ag was limited by charge carrier injection from electrodes, while in the case of current flowing from Ag to ITO no essential barriers at electrodes were noticed. [ABSTRACT FROM AUTHOR]

TiO2 nanotube electrodes were self-doped by electrochemical cathodic polarization, potentially converting Ti4+ into Ti3+, and thereby increasing both the normalized conductance and capacitance of the electrodes. One-hundred (from 19.2 ± 0.1 μF cm-2 to 1.9 ± 0.1 mF cm-2 for SD-TNT) and two-fold (from ~6.2 to ~14.4 mS cm-2) concomitant increases in capacitance and conductance, respectively, were achieved in self-doped TiO2 nanotubes; this was compared with the results for their undoped counterparts. The increases in the capacitance and conductance indicate that the Ti3+ states enhance the density of the electronic states; this is attributed to an existing relationship between the conductance and capacitance for nanoscale structures built on macroscopic electrodes. The ratio between the conductance and capacitance was used to detect and quantify, in a reagentless manner, the triamterene (TRT) diuretic by designing an appropriate doping level of TiO2 nanotubes. The sensitivity was improved when using immittance spectroscopy (Patil et al. Anal. Chem. 2015, 87, 944-950; Bedatty Fernandes et al. Anal. Chem. 2015, 87, 12137-12144) (2.4 × 106 % decade-1) compared to cyclic voltammetry (5.8 × 105 % decade-1). Furthermore, a higher linear range from 0.5 to 100 μmol L-1 (5.0 to 100 μmol L-1 for cyclic voltammetry measurements) and a lower limit-of-detection of approximately 0.2 μmol L-1 were achieved by using immittance function methodology (better than the 4.1 μmol L-1 obtained by using cyclic voltammetry). [ABSTRACT FROM AUTHOR]

We present a proof-of-concept nanoelectronics device with a negative differential conductance, an attractive from the applied viewpoint functionality. The device, characterized by the decreasing current with increasing voltage in a certain voltage region above a threshold bias of about several hundred millivolts, consists of two superconducting electrodes with an amorphous 10-nm-thick silicon interlayer doped by tungsten nano-inclusions. We show that small changes in the W content radically modify the shape of the trilayer current-voltage dependence and identify sudden conductance switching at a threshold voltage as an effect of Andreev fluctuators. The latter entities are two-level systems at the superconductor-doped silicon interface where a Cooper pair tunnels from a superconductor and occupies a pair of localized electronic states. We argue that in contrast to previously proposed devices, our samples permit very large-scale integration and are practically feasible. [ABSTRACT FROM AUTHOR]

The effect of iron atom junction on transport characteristics of carbon-silicon mixed chain has been studied from an ab initio study. At zero bias, the Fe(CSi) system appears to be the decrease of the conductance as the number of the Si-C pairs in the chain increases ( n changes). When n 5, the conductance tends to zero. These changes are independent of the transferring charge of the system, depending on the coupling of the electrodes and the central region. Under bias, the higher the bias voltage, the bigger the transmission coefficient of the system, and the transmission peak moves closer to the Fermi level. The I- V curves of Fe(CSi)2 and Fe (CSi)3 are linear, showing the behavior of metal resistance. [ABSTRACT FROM AUTHOR]

We study the full counting statistics of electron transport through a serially coupled double quantum dot (QD) system with spin–orbit coupling (SOC) weakly coupled to two electrodes. We demonstrate that the spin polarizations of the source and drain electrodes determine whether the shot noise maintains super-Poissonian distribution, and whether the sign transitions of the skewness from positive to negative values and of the kurtosis from negative to positive values take place. In particular, the interplay between the spin polarizations of the source and drain electrodes and the magnitude of the external magnetic field, can give rise to a gate-voltage-tunable strong negative differential conductance (NDC) and the shot noise in this NDC region is significantly enhanced. Importantly, for a given SOC parameter, the obvious variation of the high-order current cumulants as a function of the energy-level detuning in a certain range, especially the dip position of the Fano factor of the skewness can be used to qualitatively extract the information about the magnitude of the SOC. [ABSTRACT FROM AUTHOR]

We study the electronic transport through ac driven graphene p–n junctions under a perpendicular magnetic field. It is found that subject to the transversely or longitudinally polarized ac field, in the p–n region, the conductance versus the on-site energy of the right electrode exhibits a characteristic structure with a zero value plateau and the followed oscillation peaks, whose widths are greatly suppressed by the ac field. In the n–n region, the conductance plateaus at G = ( n + 1 / 2 ) ( 4 e 2 / h ) ( n is an integer) shrink for the transversely polarized ac field, whereas accompanied with the addition of the new quantized plateaus at G = n ( 4 e 2 / h ) for the longitudinally polarized ac field. The combined influence of the ac field with the disorder can trigger a change in the mixing of the hole and electron states at the p–n interface, which leads to a destruction of the plateaus structure in the conductance versus the disorder strength with the emergence of new ones. The influence of the elliptically and circularly polarized ac field on the conductance is also shown. [ABSTRACT FROM AUTHOR]

We study negative differential conductance (NDC) effects in polyporphyrin oligomers with nonlinear backbones. Using a low-temperature scanning tunneling microscope, we selectively controlled the charge transport path in single oligomer wires. We observed robust NDC when charge passed through a T-shape junction, bistable NDC when charge passed through a 90° kink and no NDC when charge passed through a 120° kink. Aided by density functional theory with nonequilibrium Green's functions simulations, we attributed this backbone-dependent NDC to bias-modulated hybridization of the electrode states with the resonant transport molecular orbital. We argue this mechanism is generic in molecular systems, which opens a new route of designing molecular NDC devices. [ABSTRACT FROM AUTHOR]

It is known that the conductance of a wire decreases linearly with the increase of its length in the macro circuit. But things are different in mesoscopic field, especially in molecular dimensional circuits due to the quantum interferences in molecular size. In this work, first principles is used to investigate how wire length and hydrogenation degree influence the conductance of molecular wires. For comparison, two types of carbon-based molecular wires, single carbon atomic wire and phenyl ring wire with single hydrogenation or dihydrogenation, are chosen and coupled to two zigzag graphene nanoribbon electrodes, respectively. We show that the conductance of zigzag carbon atomic wire with single hydrogenation exhibits an evident even-odd oscillatory behavior with the increase of wire length, while that of phenyl ring wire starts to increase before decreasing. However, when the above types of wires are edged with dihydrogenation, their conductance decreases exponentially with the increasing wire length. In addition, fine current rectification is found in asymmetric phenyl wires induced by hydrogenation degree, which can be used as diode in future molecular devices. Analyses via orbital hybridization, transmission path, HOMO-LUMO position and so on reveal the microscopic mechanism of the above interesting results. [ABSTRACT FROM AUTHOR]

The length of Source/Drain (S/D) extension ( L ) of nano-node p-channel FinFETs ( pFinFETs) on SOI wafer influencing the device performance is exposed, especially in drive current and gate/S/D leakage. In observation, the longer L pFinFET provides a larger series resistance and degrades the drive current ( I ), but the isolation capability between the S/D contacts and the gate electrode is increased. The shorter L plus the shorter channel length demonstrates a higher trans-conductance ( G ) contributing to a higher drive current. Moreover, the subthreshold swing (S.S.) at longer channel length and longer L represents a higher value indicating the higher amount of the interface states which possibly deteriorate the channel mobility causing the lower drive current. [ABSTRACT FROM AUTHOR]

We report a series of single-molecule transport measurements carried out in an ionic environment with oligophenylenediamine wires. These molecules exhibit three discrete conducting states accessed by electrochemically modifying the contacts. Transport in these junctions is defined by the oligophenylene backbone, but the conductance is increased by factors of ∼20 and ∼400 when compared to traditional dative junctions. We propose that the higher-conducting states arise from in situ electrochemical conversion of the dative Au←N bond into a new type of Au-N contact. Density functional theorybased transport calculations establish that the new contacts dramatically increase the electronic coupling of the oligophenylene backbone to the Au electrodes, consistent with experimental transport data. The resulting contact resistance is the lowest reported to date; more generally, our work demonstrates a facile method for creating electronically transparent metal-organic interfaces. [ABSTRACT FROM AUTHOR]

By using the first-principles method, conductance of molecular junctions containing one of five-atom cyclic unit cyclopentadiene, furan, and thiophene connected to two gold electrodes via different kinds of anchoring groups is theoretically investigated. The numerical results reveal that the experimental finding of negative relationship between conductance and molecular aromaticity (NRCA rule) does not always hold, and it is affected by the molecular anchoring group and contact manner between the molecule and electrodes. When the thiol or methylene anchoring group is used, NRCA rule is proved valid. However, this rule is not applicable for the case where isocyanide end group is used. Moreover, for methylene as the anchoring groups, it is found that the NRCA rule becomes invalid when the contact manner between the molecule and electrodes is changed from a cross style to a parallel one. The results are understood in terms of the molecular projected self-consistent Hamiltonian states as well as transmission spectra. This work facilitates the deep understanding of experimental observation from the theoretical point of view and is helpful for rational design of functional molecular devices. [ABSTRACT FROM AUTHOR]

Negative susceptance is experimentally measured in the low resistance state of TiN/Ti/HfO2/W resistive RAM memories. A meminductive-like behavior appears along with the memristive effects. A detailed study of small-signal parameters measured at 0 V after applying positive and negative voltage pulses is presented. A simple model for the conductive filaments consisting in a resistance in series with an inductance is used. In the equivalent circuit, both elements are in parallel with the geometrical capacitance of the structure. Both resistance and inductance show two clearly differentiate states. Positive voltages switch the device to the ON state, in which the resistance value is low and the inductance value is high. By applying appropriate negative voltages, the device switches to the OFF state, in which resistance value is high and inductance becomes negligible. The negative susceptance could be related to lags between current and electric field due to transport mechanisms occurring in the ON state. [ABSTRACT FROM AUTHOR]

We demonstrate that the notched-wire mechanically controllable break junction technique can be exploited for the study of single molecule junctions. We have developed a protocol for deposition of thiol-coupled molecules onto Au electrodes from solution. We find surprisingly sharp conductance historgrams at low temperatures, which suggest that the commonly observed large width of the peaks in conductance historgams is the result of inhomogeneous broadening. [ABSTRACT FROM AUTHOR]

Abstract : Randles-Ershler admittance model is extensively used in the modeling of batteries, fuel cells, sensors etc. It is also used in understanding response of the fundamental systems with coupled processes like charge transfer, diffusion, electric double layer charging and uncompensated solution resistance. We generalize phenomenological theory for the Randles-Ershler admittance at the electrode with double layer capacitance and charge transfer heterogeneity, viz., non-uniform double layer capacitance and charge transfer resistance ( $$c_d$$ and $$R_{CT}$$ ). Electrode heterogeneity is modeled through distribution functions of $$R_{CT}$$ and $$c_d$$ , viz., log-normal distribution function. High frequency region captures influence of electric double layer while intermediate frequency region captures influence from the charge transfer resistance of heterogeneous electrode. A heterogeneous electrode with mean charge transfer resistance $$\overline{R_{CT}}$$ shows faster charge transfer kinetics over a electrode with uniform charge transfer resistance ( $$\overline{R_{CT}}$$ ). It is also observed that a heterogeneous electrode having high mean with large variance in the $$R_{CT}$$ and $$c_d$$ can behave same as an electrode having low mean with small variance in the $$R_{CT}$$ and $$c_d$$ . The origin of coupling of uncompensated solution resistance (between working and reference electrode) with the charge transfer kinetics is explained. Finally, our model provides a simple route to understand the effect of spatial heterogeneity. Graphical Abstract: SYNOPSIS An electrochemical system consisting of heterogeneous working electrode (non-uniform charge transfer (CT) resistance ( $$R_{CT}^{(i)}$$ ) and electric double layer capacitance ( $$c_{d}^{(i)}$$ )) and ohmic losses ( $$R_\Omega $$ ) between working and reference electrode. The analysis suggests that electrode with heterogeneity results in faster CT kinetics as compared to CT kinetics over homogeneous electrode. [ABSTRACT FROM AUTHOR]

We report on a 1-transisor/2-resistor (1T2R) synapse device with improved conductance linearity and conductance ratio under an identical pulse condition for hardware neural networks with high pattern-recognition accuracy. Utilizing an additional series-connected resistor, the conductance linearity of a synapse device was significantly improved owing to the reduced initial voltage drop on an resistive RAM (RRAM) device during depression conditions. Moreover, to maximize the conductance ratio of a synapse device, we utilized a steep subthreshold region of an MOSFET by a parallel connection of an RRAM and a transistor. A small change in voltage on the RRAM directly controlled the gate bias of the MOSFET, which causes a large change in the drain current. Compared with a conventional RRAM synapse device, the 1T2R synapse device shows an improved conductance linearity and conductance ratio ( $> \times 100$ ). Finally, we confirmed an excellent classification accuracy by using a neural network simulation based on a multilayer perceptron. [ABSTRACT FROM AUTHOR]

In this study, a new and improved electrical conductance sensor is proposed for application not only to a horizontal pipe, but also an inclined one. The conductance sensor was designed to have a dual layer, each consisting of a three-electrode set to obtain two instantaneous conductance signals in turns, so that the area-averaged void fraction and structure velocity could be measured simultaneously. The optimum configuration of the electrodes was determined through numerical analysis, and the calibration curves for stratified and annular flow were obtained through a series of static experiments. The fabricated conductance sensor was applied to a 45 mm inner diameter U-shaped downward inclined pipe with an inclination angle of 3° under adiabatic air-water flow conditions. In the tests, the superficial velocities ranged from 0.1 to 3.0 m/s for water and from 0.1 to 18 m/s for air. The obtained mean void fraction and the structure velocity from the conductance sensor were validated against the measurement by the wire-mesh sensor and the cross-correlation technique for the visualized images, respectively. The results of the flow regime classification and the corresponding time series of the void fraction at a variety of flow velocities were also discussed. [ABSTRACT FROM AUTHOR]

Formation of abrupt tunneling junction for the sub-nanometer tunnel FET (TFET) is crucial for achieving better electrical behavior. This task is more challenging in the case of dopingless TFETs (DL TFETs). In this concern, we propose a novel design of DL TFET, wherein a metallic layer has been placed in the oxide region at the space present between gate and source electrode (used for inducing p+ region) of conventional dopingless n-TFET to overcome the issue of low on-state current ( \textI\mathrm{on} ) due to presence of tunneling barrier. Proposed modification is helpful for achieving steeper tunneling junction at the source/channel interface, which enables higher tunneling generation rate of charge carriers at this interface. The optimization for work function of the metal layer (ML) has been performed for improving \text I\mathrm{on} , point subthreshold swing and threshold voltage ( \text V\text {th} ). Finally, the impact of the ML misalignment from the gate/source terminal and optimization of its length is also presented. [ABSTRACT FROM PUBLISHER]

Liquid film thickness measurements under temperature-varying conditions in a two-phase flow are of great importance to refining our understanding of two-phase flows. In order to overcome the limitations of the conventional electrical means of measuring the thickness of a liquid film, this study proposes a three-electrode conductance method, with the device fabricated on a flexible printed circuit board (FPCB). The three-electrode conductance method offers the advantage of applicability under conditions with varying temperatures in principle, while the FPCB has the advantage of usability on curved surfaces and in relatively high-temperature conditions in comparison with sensors based on a printed circuit board (PCB). Two types of prototype sensors were fabricated on an FPCB and the feasibility of both was confirmed in a calibration test conducted at different temperatures. With the calibrated sensor, liquid film thickness measurements were conducted via a falling liquid film flow experiment, and the working performance was tested. [ABSTRACT FROM AUTHOR]

The multi-scale analysis is an important method for detecting nonlinear systems. In this study, we carry out experiments and measure the fluctuation signals from a rotating electric field conductance sensor with eight electrodes. We first use a recurrence plot to recognise flow patterns in vertical upward gas-liquid two-phase pipe flow from measured signals. Then we apply a multi-scale morphological analysis based on the first-order difference scatter plot to investigate the signals captured from the vertical upward gas-liquid two-phase flow loop test. We find that the invariant scaling exponent extracted from the multi-scale first-order difference scatter plot with the bisector of the second-fourth quadrant as the reference line is sensitive to the inhomogeneous distribution characteristics of the flow structure, and the variation trend of the exponent is helpful to understand the process of breakup and coalescence of the gas phase. In addition, we explore the dynamic mechanism influencing the inhomogeneous distribution of the gas phase in terms of adaptive optimal kernel time-frequency representation. The research indicates that the system energy is a factor influencing the distribution of the gas phase and the multi-scale morphological analysis based on the first-order difference scatter plot is an effective method for indicating the inhomogeneous distribution of the gas phase in gas-liquid two-phase flow. [ABSTRACT FROM AUTHOR]

Transparent electrodes based on In 2 O 3 :Sn (ITO) and SnO 2 :Sb (ATO) thin films have been deposited by sputtering at room temperature on soda lime glass (SLG) substrates. The preparation conditions were adjusted to obtain 250 nm-thick ITO layers with high conductivity and textured ATO coatings with various thicknesses from 80 to 200 nm. These ITO and ATO films have been combined to enhance the optical scattering and the electrical conductivity of the bilayer electrodes. Besides, a suitable ATO coating can prevent the oxidation of the ITO underlayer, thus increasing the stability of the overall electrical performance. With this purpose the structure, morphology, optical and electrical properties have been analysed comparatively for SLG/ITO, SLG/ATO and SLG/ITO/ATO samples after heating in air at 500 °C, studying the influence of the ATO layer thickness on the light scattering and thermal stability of the electrodes. In this way, a minimum sheet resistance of 8 Ω/sq has been achieved with a 120 nm-thick ATO film deposited on the 250 nm-thick ITO layer; such stacked electrode has visible transmittance near 80% and average haze H T = 10%, showing superior stability, light scattering and electrical performance than the isolated ITO and ATO films. [ABSTRACT FROM AUTHOR]

In this work, we study the cyclic telescoping of multi-walled carbon nanotubes (MWCNTs) inside a high-resolution transmission electron microscope. The nanotubes are observed in real time, while simultaneously measuring their electrical properties. Experiments are conducted by first ‘sharpening’ a MWCNT by approaching it with a piezo-controlled tungsten tip and applying a single voltage pulse. This results in controlled and localized peeling of the outer walls, giving rise to a telescope structure. The exposed core is then contacted with the tungsten tip and reproducibly pulled out then re-inserted, while measuring conductance behaviour at each movement step. Results demonstrate that an electrical current can be maintained for multiple in-and-out cycles, and for telescoping distances of up to 650 nm. The systems display complex conductance behaviour, with most MWCNT telescopes demonstrating diminishing conduction (and current) as a function of the number of cycles, while for some these properties improve. Control experiments have been carried out to investigate the effect of current annealing and beam damage on whole MWCNTs. One potential application for these structures is use as flexible electrical contacts, which allow for relative motion of the two electrodes, while maintaining electrical conduction. [ABSTRACT FROM AUTHOR]

We consider the differential conductance of a periodically driven system connected to infinite electrodes. We focus on the situation where the dissipation occurs predominantly in these electrodes. Using analytical arguments and a detailed numerical study we relate the differential conductances of such a system in two and three terminal geometries to the spectrum of quasi-energies of the Floquet operator. Moreover these differential conductances are found to provide an accurate probe of the existence of gaps in this quasi-energy spectrum, being quantized when topological edge states occur within these gaps. Our analysis opens the perspective to describe the intermediate time dynamics of driven mesoscopic conductors as topological Floquet filters. [ABSTRACT FROM AUTHOR]

We analyze the response of identical pulses on a filamentary resistive memory (RRAM) to implement the synapse function in neuromorphic systems. Our findings show that the multilevel states of conductance are achieved by varying the measurement conditions related to the formation and rupture of a conductive filament. Furthermore, abrupt set switching behavior in the RRAM leads to an unchanged conductance state, leading to degradation in the accuracy of pattern recognition. Thus, we demonstrate a linear potentiation (or depression) behavior of conductance under identical pulses using the effect of barrier layer on the switching, which was realized by fabricating an RRAM on top of an Al electrode. As a result, when the range of the conductance is symmetrically controlled at both polarities, a significantly improved accuracy is achieved for pattern recognition using a neural network with a multilayer perceptron. [ABSTRACT FROM PUBLISHER]

Measuring water holdup and characterizing the flow behavior of an oil–water two-phase flow is a contemporary and challenging problem of significant importance in industry. To address this problem, we develop a new method to design a new four-sector distributed conductance sensor. Specifically, we first use the finite-element method (FEM) to investigate the sensitivity distribution of the electric field and then calculate its response on the measurement electrodes. Based on the FEM analysis results, we extract two optimizing indexes to describe and find the optimum geometry for the four-sector distributed conductance sensor. We carry out oil–water two-phase flow experiments in a vertical upward pipe to validate the designed sensor implemented in the measurement of water holdup. In addition, we use the multivariate pseudo Wigner distribution (MPWD) method to analyze the multivariate signals from the four-sector distributed sensor. Our analytical and experimental results indicate that the four-sector distributed conductance sensor enables measuring water holdup and the MPWD allows uncovering local flow behavior revealing different oil–water flow patterns. [ABSTRACT FROM PUBLISHER]

The electrical conductance G of magnetostrictive nanocontacts made from Galfenol (Fe73Ga27) can be reproducibly switched between "on" and "off" states in a low magnetic field of ~20-30mT at 10 K. The switching behavior is in agreement with the magnetic field dependence of the magnetostriction inferred from the magnetization behavior, causing a positive magnetostrictive strain along the magnetic field. The repeated magnetic-field cycling leads to a stable contact geometry and to a robust contact configuration with a very low hysteresis of ~1mT between opening and closing the contact due to a training effect. Non-integral multiples of the conductance quantum G0 observed for G > G0 are attributed to electron backscattering at defect sites in the electrodes near the contact interface. When the contact is closed either mechanically or by magnetic field, the conductance shows an exponential behavior below G0 due to electron tunneling. This allows to estimate the magnetostriction λ = 4 x 10-5 at 10 K. The results demonstrate that such magnetostrictive devices are suitable for the remote control of the conductance by low magnetic ?elds in future nanotechnology applications. [ABSTRACT FROM AUTHOR]

Herein the application of a recently introduced new method of tracking in-situ the intercalation-induced deformations of supercapacitor and Li-battery electrodes is reviewed. The method is based on the use of multi-harmonic electrochemical quartz microbalance with dissipation monitoring, EQCM-D (in-situ hydrodynamic spectroscopy) which enables a permanent control of the electrodes' state-of-health by probing their mechanical properties. The potential-dependent frequency and resonance width changes are fitted to a chosen hydrodynamic admittance model allowing thus quantification of the electrode deformations under different charging conditions. Intercalation of different alkaline metal cations into layered MXene electrode serves as a readily understandable working example of quantifying such electrodes deformations. Further method developments including in-situ viscoelastic characterization of composite porous electrodes are envisaged in the near future. [ABSTRACT FROM AUTHOR]

We present the overall conductance as well as the circulating currents in individual loops of a Sierpinski gasket (SPG) as we apply bias voltage via the side attached electrodes. SPG being a self-similar structure, its manifestation on loop currents and magnetic fields is examined in various generations of this fractal and it has been observed that for a given configuration of the electrodes, the physical quantities exhibit certain regularity as we go from one generation to another. Also a notable feature is the introduction of anisotropy in hopping causes an increase in magnitude of overall transport current. These features are a subject of interest in this article. [ABSTRACT FROM AUTHOR]

The single molecule conductances of a series of bis-2,2':6',2"-terpyridine complexes featuring Ru(II), Fe(II), and Co(II) metal ions and trimethylsilylethynyl (Me3SiC=C-) or thiomethyl (MeS-) surface contact groups have been determined. In the absence of electrochemical gating, these complexes behave as tunneling barriers, with conductance properties determined more by the strength of the electrode-molecule contact and the structure of the "linker" than the nature of the metal-ion or redox properties of the complex. [ABSTRACT FROM AUTHOR]

A molecular single-electron transistor (SET) with (10-Boranylanthracene-9-yl)borane molecule as an island has been analyzed in an effort to model a better acene series SET. The (10-Boranylanthracene-9-yl)borane molecule was obtained through the substitution of dangling hydrogens of middle honeycomb by boron in anthracene. A first principle analysis has been performed to analyze the impact of boron substitution in anthracene and on the SET performance using density functional theory (DFT)-based ab initio tools Atomistix Toolkit-Virtual Nanolab and Gaussian03. To analyze the impact of boron substitution, different structural and electronic properties, such as electron density difference, natural bond orbital analysis, electron localization function, molecular energy spectrum, total energy, bond lengths, and bond angles, have been calculated, and to analyze the device performance, charging energies have been calculated and plotted total energies, charge stability diagram as a function of bias potentials. The analysis confirms that the proposed doped anthracene-based SET has high switching speed and power efficiency in comparison with the other organic molecular SETs reported of the kind. [ABSTRACT FROM PUBLISHER]

We investigate the electron transport properties in atomic carbon wires between two zigzag graphene nanoribbon (ZGNR) electrodes by applying nonequilibrium Green's functions in combination with the density-functional theory. It shows that the ZGNR electrode twisting can modulate the conductance of the atomic carbon wire-graphene junctions remarkably. Typical currents of devices with odd carbon wires are much higher than currents of devices with even carbon wires to exhibit even-odd behavior. The negative differential resistance behaviors are only found in the devices with odd carbon wires. When the right ZGNR electrode is twisted, the curvatures of the current–voltage characteristics change remarkably upon twisted angles. The current will decrease by up to 5 orders of magnitude when the twisted angle reaches to 90°. That means the atomic carbon wire-graphene junctions can be made as a mechanical switching. [ABSTRACT FROM AUTHOR]

Charge plasma based doping-less dual material double gate (DL-DMDG) junctionless transistor (JLT) is proposed. This paper also demonstrate the potential impact of gate stacking (GS) (high-k + Sio 2 ) on DL-DMDG (DL-GSDMDG) JLT device. The efficient charge plasma is created in an intrinsic silicon film to form n + source/drain (S/D) by selecting proper work function of S/D electrode which helps to minimize threshold voltage fluctuation that occurs in a heavily doped JLT device. The analog performance parameters are analyzed for both the device structures. Results are also compared with conventional dual material double gate (DMDG) and gate stacked dual material double gate (GSDMDG) JLT devices. A DL-DMDG JLT device shows improved early voltage (V EA ), intrinsic gain (A V = g m /g DS ) and reduced output conductance (g DS ) as compared to conventional DMDG and GSDMDG JLT devices. These values are further improved for DL-GSDMDG JLT. The effect of control gate length (L 1 ) for a fixed gate length (L = L 1 +L 2 ) are also analyzed. [ABSTRACT FROM AUTHOR]

We report the development of a multi sensor array integrated with four different layers of tin oxide/additive combinations, which operates thermo-cyclically by triangular heater voltages, for specific gas identification. These multi sensor arrays could yield simultaneously four different patterns of dynamic conductance, which can be used for specific gas component analysis. Pure SnO 2 , SnO 2 /Sb 2 O 3 , SnO 2 /Sb 2 O 3 /La 2 O 3 and SnO 2 /Sb 2 O 3 /CuO were used as sensing materials on a single chip with Au or Pt as electrode material to study the response behavior to propene, CO and methane at different concentrations and temperature rates/cycle time. The nature of the specific gas recognition patterns is highly determined by additive material, electrode metallization, temperature rate, type of gas and gas concentration. The specific gas behavior is discussed in connection with the reaction processes taking place at the pores of the sensing layer and at the triple phase boundary of layer, electrode and gas. [ABSTRACT FROM AUTHOR]

Nonaqueous redox flow batteries (RFB) leverage nonaqueous solvents to enable higher operating voltages compared to their aqueous counterparts. Most commercial components for flow batteries, however, are designed for aqueous use. One critical component, the ion-selective membrane, provides ionic conductance between electrodes while preventing crossover of electroactive species. Here we evaluate the area-specific conductances and through-plane conductivities of commercially available microporous separators (Celgard 2400, 2500) and anion exchange membranes (Neosepta AFX, Neosepta AHA, Fumasep FAP-450, Fumasep FAP-PK) soaked in acetonitrile, propylene carbonate, or two imidazolium-based ionic liquids. Fumasep membranes combined with acetonitrile-based electrolyte solutions provided the highest conductance values and conductivities by far. When tested in ionic liquids, all anion exchange membranes displayed conductivities greater than those of the Celgard microporous separators, though the separators' decreased thickness-enabled conductances on par with the most conductive anion exchange membranes. Ionic conductivity is not the only consideration when choosing an anion exchange membrane; testing of FAP-450 and FAP-PK membranes in a nonaqueous RFB demonstrated that the increased mechanical stability of PEEK-supported FAP-PK minimized swelling, in turn decreasing solvent mediated crossover and enabling greater electrochemical yields (40% vs. 4%) and Coulombic efficiencies (94% vs. 90%) compared to the unsupported, higher conductance FAP-450. [ABSTRACT FROM AUTHOR]

This paper proposes a mathematical model for electrical discharge plasmas between moving electrodes under ac condition, which happens in ac switching apparatuses. The modeling work is started by converting the problem to a conventional RL network that treats the arcing phenomenon as a black box and proposing a transient differential equation to represent the breaking arc process. A resistance–time relation model developed from the classic Mayr model is then proposed. A conceptual unit-arc approach is used to deal with the issue of variable arc length as the contacts move. Experimental data from ac contactor tests are used to approximate the resistance–time function by a nonlinear curve fitting. The model is solved computationally and compared with the experimental data. It is that the model adequately describes the breaking arc phenomenon. [ABSTRACT FROM PUBLISHER]

A determination of the frequency behavior of the Physikalisch-Technische Bundesanstalt (PTB) calculable capacitor in the audio frequency range is carried out by applying an equivalent circuit model. The circuit model considers the influence of distributed admittances and impedances within the calculable capacitor and has been derived from the main currents flowing inside the calculable capacitor and the voltage drops caused by these currents. It has been found that the frequency dependence of the cross capacitance is proportional to the square of the frequency, whereby mutual inductances of opposite electrodes and capacitances to ground dominate the behavior at higher frequencies. At a frequency of 1592 Hz, the correction of the PTB calculable capacitor with a value of 1 pF amounts to 9.2\times 10^-8 pF with an expanded uncertainty ( $k=2$ ) of 3.1\times 10^{-8} pF. [ABSTRACT FROM PUBLISHER]

We demonstrate the ink-jet printed fabrication technique for TiO2-based memristor, followed by detailed analysis of electrical characteristics and development of a new model that considers observed phenomena of quantized conductance steps. The existence of pinched hysteretic current–voltage characteristics is evidence of memristive behavior, provided by the reversible atomic rearrangement taking place in the functional layer. For the first time, performed electrical measurement on the micrometer thickness devices based on TiO2 active layer has captured the plateaux steps of the conductance at integer multiples of elementary quantum conductance. This behavior is consistent with the assumption that transport from electrode to electrode emerges through confined paths of conductive filaments with radius in the nanometer size range. Moreover, we introduce a novel model, based on the diffusion equation for ballistic transport in memristive devices, which considers the conductance plateaux steps. [ABSTRACT FROM AUTHOR]

Constructing electronic circuits containing singly wired molecules is at the frontier of electrical device miniaturisation. When a molecule is wired between a pair of electrodes, the two points of contact are determined by the chemical anchoring groups, located at the ends of the molecule. At this point, when a bias is applied, electrons are channelled from a metallic environment through an extremely narrow constriction, essentially a single atom, into the molecule. The fact that this is such an abrupt change in the electron pathway makes the nature of the chemical anchoring groups critically important regarding the propagation of electrons from the electrode across the molecule. A delicate interplay of phenomena can occur when a molecule binds to the electrodes, which can produce profound differences in conductance properties depending on the anchoring group. This makes answering the question “what is the best anchoring group for single molecule studies” far from straight forward. In this review, we firstly take a look at techniques developed to ‘wire-up’ single molecules, as understanding their limitations is key when assessing a molecular wire's performance. We then analyse the various chemical anchoring groups, and discuss their merits and disadvantages. Finally we discuss some theoretical concepts of molecular junctions to understand how transport is affected by the nature of the chemical anchor group. [ABSTRACT FROM AUTHOR]

We present an ab initio study of the structural, electronic, and quantum transport properties of B–N-complex edge-doped graphene nanoribbons (GNRs). We find that the B–N edge codoping is energetically a very favorable process and furthermore can achieve novel doping effects that are absent for the single B or N doping. The compensation effect between B and N is predicted to generally recover the excellent electronic transport properties of pristine GNRs. For the zigzag GNRs, however, the spatially localized B–N defect states selectively destroy the doped-side spin-polarized GNR edge currents at the valence and conduction band edges. We show that the energetically and spatially spin-polarized currents survive even in the fully ferromagnetic metallic state and heterojunction configurations. This suggests a simple yet efficient scheme to achieve effectively smooth GNR edges and graphene-based spintronic devices. [ABSTRACT FROM AUTHOR]

Electroencephalography (EEG) is an important biopotential, and has been widely applied in clinical applications. The conventional EEG electrode with conductive gels is usually used for measuring EEG. However, the use of conductive gel also encounters with the issue of drying and hardening. Recently, many dry EEG electrodes based on different conductive materials and techniques were proposed to solve the previous issue. However, measuring EEG in the hairy site is still a difficult challenge. In this study, a novel active comb-shaped dry electrode was proposed to measure EEG in hairy site. Different form other comb-shaped or spike-shaped dry electrodes, it can provide more excellent performance of avoiding the signal attenuation, phase distortion, and the reduction of common mode rejection ratio. Even under walking motion, it can effectively acquire EEG in hairy site. Finally, the experiments for alpha rhythm and steady-state visually evoked potential were also tested to validate the proposed electrode. [ABSTRACT FROM PUBLISHER]

We report an electrochemical gating approach with ~100% efficiency to tune the conductance of single-molecule 4,40-bipyridine junctions using scanning-tunnelling-microscopy break junction technique. Density functional theory calculation suggests that electrochemical gating aligns molecular frontier orbitals relative to the electrode Fermi-level, switching the molecule from an off resonance state to ''partial'' resonance. [ABSTRACT FROM AUTHOR]

We have measured the force and conductance of Au-octanedithiol-Au junctions using a modified conducting atomic force microscopy break junction technique with sawtooth modulations. Force-conductance two-dimensional cross-correlation histogram (FC-2DCCH) analysis for the single-molecule plateaus is demonstrated. Interestingly, four strong correlated regions appear in FC-2DCCHs consistently when modulations with different amplitudes are applied, in sharp contrast to the results under no modulation. These regions reflect the conductance and force changes during the transition of two molecule/electrode contact configurations. As the modulation amplitude increases, intermediate transition states of the contact configurations are discerned and further confirmed by comparing individual traces. This study unravels the relation between force and conductance hidden in the data of a modulated single-molecule break junction system and provides a fresh understanding of electron transport properties at molecule/electrode interfaces. [ABSTRACT FROM AUTHOR]

We theoretically investigate the electrically controllable conductance and tunneling magnetoresistance (TMR) through a two-dimensional topological insulator (TI) quantum well sandwiched between ferromagnetic (FM) electrodes in the method of nonequilibrium Green's function (GF). It is demonstrated that the inter-edge tunnelings modulated conductance for spin-up and spin-down carriers presents an opposite tend with the polarization of the FM electrodes. The system TMR from the spin-valve effect is observed to be up to 65,000 %, as can be significantly suppressed and enhanced by the backscattering and spin-dephasing effect of the inter-edge spin-conserving and spin-flipping tunneling, respectively, other than the quite different energy-dependent oscillation behavior. The obtained results may provide a deeper understanding of the TI edge states and be used to design a dissipationless spintronic device based on TIs. [ABSTRACT FROM AUTHOR]