Electric Field Coupling Research Articles

Collective behaviors in a multiple functional network with hybrid synapses

Because of functional differentiation of biological neurons, more functional regions have been developed and formed in the brain and the neurons with the same biophysical function are connected in a specific region. Many neural circuits can be improved to exit specific functions by incorporating special electric components into the branch circuits, and they can be connected to simulate the cooperation of neurons with different biophysical properties. In this paper, three kinds of functional neural circuits are connected to develop a functional network for detecting external illumination, temperature changes and acoustic wave synchronously. The synchronous stability between neurons are much dependent on the intrinsic properties of the synaptic connection along the coupling channels. Electric synapse connection, capacitor-connection and induction coil connection are applied to trigger voltage, electric field and magnetic field couplings along the links in the neural network, respectively. Indeed, the field coupling induced by capacitive and inductive coupling can be controllable under external field by injecting energy continuously. The results indicate that the phase lock of the neural network can be stabilized by taming the coupling intensity carefully, and it can be further enhanced and switched by involving the noise. The Hamilton energy is estimated and in line with the phase synchronization. These results are helpful to know potential biophysical mechanism of synchronous firing and mode selection in the functional network.

Electromagnetic Modeling of Lossy Interconnects From DC to High Frequencies With a Potential-Based Boundary Element Formulation

The accurate electromagnetic modeling of both low- and high-frequency physics is crucial in the signal and power integrity analysis of electrical interconnects. The boundary element method (BEM) is appealing for lossy conductor modeling because it can capture the frequency-dependent variation of skin depth with only a surface-based discretization of the structure. Conventional BEM formulations rely on the mutual coupling of electric and magnetic fields, and can become inaccurate or unstable at low frequencies. We develop a new full-wave BEM formulation based on potentials which can accurately model lossy conductors from exactly DC to very high frequencies. A new set of simple boundary conditions is proposed along with a modified Lorenz gauge to ensure that the proposed formulation has a stable condition number down to DC. Moreover, coupling the potential-based integral equations to a circuit model allows the straightforward extraction of network parameters. Realistic numerical examples at both the chip and package level demonstrate the accuracy and stability of the proposed method from DC to high frequencies, beyond the capabilities of state-of-the-art BEM formulations based on fields.

1D/0D Z-scheme heterostructure of Bi2S3/CdXZn1−XS with strong interfacial electric field coupling enhanced mass transfer based on gas-liquid-solid micro interface contact for efficient photothermal synergistic catalytic CO2 reduction to syngas

The reduction of CO2 to syngas by visible light-driven H2O is an attractive process, but this reaction is often limited by the poor mass transfer of CO2 in the liquid phase and the poor separation and mobility of photocatalyst carriers. In this paper, CdXZn1−XS nanospheres (CZS-X) uniformly decorated hollow Bi2S3 nanotube (H-BS NTs) heterojunction for photocatalytic CO2 reduction was successfully fabricated by in situ electrostatic self-assembly method. The yields of CO and H2 over 15 % H-BS NTs/CZS-0.5 was 32.11 μmol∙g−1∙h−1 and 33.10 μmol∙g−1∙h−1 without any sacrificial agent, which was 24.0 and −6.3 times than that of CZS-0.5, accordingly. The excellent activity was mainly attributed to the strong interfacial electric field (IEF) formed between H-BS NTs and CZS-0.5, which derived the rapid separation and transfer of charges dynamically. Meanwhile, the photo-thermal catalysis (PTC) with the novel gas-liquid-solid micro reactor inhibited efficiently the interface contact of the hydrogen evolution reaction and thermodynamically accelerated the rate of photocatalytic reduction of CO2. The accelerated photogenerated charge transfer was investigated in detail by density functional theory (DFT) calculations, in situ Kelvin probe force microscopy (IS-KPFM) and in situ X-ray Photoelectron Spectroscopy (IS-XPS). The results provided a new idea for promoting interfacial mass transfer, as well as photo-thermo-electric fields coupling to improve activity and selectivity.

Coupling characteristics of fluid and charge behaviors in an EHD wall jet produced by a surface dielectric barrier injection actuator

The mechanism of an EHD wall jet generated by a surface dielectric barrier injection (SDBI) actuator remains to be elucidated due to asymmetry of the electrode structure and existence of the dielectric layer. Taking into account the charge injection and dissociation mechanisms as well as the surface charge accumulation effect, an EHD wall jet model of general applicability based on the finite element method is established to explore the electric field and flow field coupling characteristics under a square wave signal. Simulation results show that a homocharge region is formed at the tip of the electrode while a heterocharge one is built at the upper surface area. Injected charges are attached to the dielectric surface owing to migration and accumulation as they move downstream with the flow field. The motion of opposite charges contributes to the vortex formation process and its trajectory is in line with the vortex evolution path. For each half-cycle of the square wave, the feature of an abrupt increase followed by an exponential decrease applies to both the velocity evolution characteristic and the current variation law.

Multiple polarization-selective and wideband enhanced optical properties of a cubic quantum dot realized by the multi-physical field.

The coupling of intense laser field and electric field serves as a new method to achieve the desired electronic states, optical absorption coefficients and refractive index changes of cubic quantum dot for the first time, to the best of our knowledge. The stationary Schrödinger equation was derived and calculated by means of the Kramers-Henneberger transformation, the non-perturbative Floquet method, and the finite difference method. The energy-level anticrossing is activated by multi-physical field to transform suitable quantum states, resulting in the multiple-polarization-selective absorption and refractive index changes. The results show that ultra-wideband frequency shift and resonance enhancement characteristics of optical absorption coefficients and refractive index changes strongly depend on the laser-dressed parameter, the amplitude of electric field, and the polarization directions of the intense laser field and electric field.

Interlayer coupling and external electric field controllable electronic structures and Schottky contact of HfSeX (X = S, Se)/graphene van der Waals heterostructures

Graphene-based van der Waals heterostructures (vdWHs) owing to their remarkable physical properties and extensive application attract much attention. However, the Schottky barrier height (SBH) at the interface limits the charge injection effect. Here, we investigate the geometry, electronic structures, contact behavior and optical properties of the HfSeX/graphene (HfSeX/G, X = S, Se) vdWHs via first-principles calculations. The effect of interlayer coupling and external electric field (Efield) on the HfSeX/G are examined. Our results show that the Dirac cones of graphene are well preserved in all modes due to weak van der Waals interaction and a small bandgap is opened in graphene. The SBH of n-type Schottky contact types (SCT) HfSe2/G, SHfSe/G and SeHfS/G vdWHs are 0.100, 0.085 and 0.114 eV, respectively. Both the interlayer distance and Efield can induce the n-type SCT of the Janus HfSSe/G to transfer to p-type, and large Efield can cause an Ohmic contact. The HfSeX/G heterostructures enhance light absorption intensity in visible-light region compared with isolate graphene and HfSeX monolayers. The work provides a valuable theoretical guidance for designing Schottky-based devices of the HfSeX/G heterostructures, as well as indicates that the heterostructures have a flexible application prospect in further optoelectronic and field effect transistors devices.

How to correctly estimate the electric field in capacitively coupled systems for tissue engineering: a comparative study

Capacitively Coupled (CCoupled) electric fields are used to stimulate cell cultures in Tissue Engineering. Knowing the electric field (E-Field) magnitude in the culture medium is fundamental to establish a relationship between stimulus strength and cellular effects. We analysed eight CCoupled studies and sought to corroborate the reported estimates of the E-Field in the culture medium. First, we reviewed the basic physics underlying CCoupled stimulation and delineated three approaches to estimate the E-field. Using these approaches, we found that the reported values were overestimated in five studies, four of which were based on incorrect assumptions. In all studies, insufficient information was provided to reproduce the setup exactly. Creating electrical models of the experimental setup should improve the accuracy of the E-field estimates and enhance reproducibility. For this purpose, we developed a free open-source tool, the E-field Calculator for CCoupled systems, which is available for download from an internet hosting platform.

A Study on the Influence of End-Sheath Aging and Moisture Absorption on Abnormal Heating of Composite Insulators

Abnormal heating of composite insulators of high-voltage transmission lines concentrate at its end, especially in a high-humidity environment. In order to study the influence of end-sheath aging and moisture absorption on abnormal heating of composite insulators, in this paper, we first discuss the appearance test, temperature rise test, and dielectric characteristic test conducted on 110 kV decommissioned composite insulators. Test results indicated the temperature rise in composite insulators increased with ambient humidity, but temperature rise was not severely affected by surface contamination of its shed and sheath; in dry environments, the dielectric constant and dielectric loss factor of high-voltage end sheaths are higher than of those of medium- and low-voltage end sheaths, and the loss effect becomes more severe after moisture absorption in a high-humidity environment. After the tests, the authors established a COMSOL simulation model of composite insulators, to analyze changes in the electric field and thermal field of the end sheath of composite insulators due to the coupling of electric and thermal fields. It was concluded that the dielectric constant of a high-voltage end sheath of the composite insulator increased after moisture absorption, distorting the partial electric field on the surface; meanwhile, the dielectric loss factor increased significantly after water molecules intruded into the aging layer of the sheath as polar molecules. Therefore, the dielectric loss (leakage conductance loss and lossy polarization loss) caused by aging and moisture absorption of the sheath surface under partially high field strength in the high-humidity environment was the leading cause of abnormal heating at the high-voltage end of composite insulators. The conclusion of this paper serves as an important reference for revealing the causes of abnormal heating of composite insulators in high-humidity environments and the influence mechanism of external factors on abnormal heating.

Thermal analysis of micropolar fluid flow driven by electroosmosis and peristalsis in microchannel

Thermo-micropolar fluids contain small conductive particles which would be useful for drug delivery and localized heating. Considering the importance of the special fluid model (micropolar fluids), a mathematical model is formulated to analyse the heat transfer in electroosmotic flow of thermo-micropolar fluid in curved microchannel. A curvilinear coordinate system is adopted to describe the curved microchannel which is propagated by peristaltic pumping and generate the pressure gradient in addition to electroosmotic force. Eringen’s micropolar theory is employed to introduce the conservation of mass, linear momentum, angular momentum, and energy to model the problem. Numerical solutions are computed for low zeta potential and low Reynolds number using Mathematica NDSolver. The effects of microchannel curvature, electrokinetic, zeta potential, micropolar parameter and viscosities (shear and vortex viscosities) ratio on velocity fields, pressure gradient, temperature, contour of stream lines, shear stress isotherms and heat transfer coefficient are examined to provide a parametric analysis. Numerical results reveal that the pressure has slight deviation with wall curvature however the pressure changes significantly with variation in coupling number and electric field. Further, the linear and angular velocities of the micropolar fluid could be controlled by the electrokinetic phenomena.

In-situ construction of abundant active centers on hierarchically porous carbon electrode toward high-performance phosphate electrosorption: Synergistic effect of electric field and capture sites

Phosphate removal is crucial for eutrophication control and water quality improvement. Electro-assisted adsorption, an eco-friendly electrosorption process, exhibited a promising potential for wastewater treatment. However, there are few works focused on phosphate electrosorption, and reported electrodes cannot attach satisfactory removal capacities and rates. Herein, electro-assisted adsorption of phosphate via in-situ construction of La active centers on hierarchically porous carbon (LaPC) has been originally demonstrated. The resulted LaPC composite not only possessed a hierarchically porous structure with uniformly dispersed La active sites, but also provided good conductivity for interfacial electron transfer. The LaPC electrode achieved an ultrahigh phosphate electrosorption capability of 462.01 mg g−1 at 1 V, outperforming most existing electrodes. The superior phosphate removal performance originates from abundant active centers formed by the coupling of electric field and capture sites. Besides, the stability and selectivity toward phosphate capture were maintained well even under comprehensive conditions. Moreover, a series of kinetics and isotherms models were employed to validate the electrosorption process. This work demonstrates a deep understanding and promotes a new level of phosphate electrosorption.

Plasmonic and bi-piezoelectric enhanced photocatalysis using PVDF/ZnO/Au nanobrush

Abstract The photocatalytic degradation, as an environmental-friendly technology, has great significance for cost-effective and efficient catalysis processes, wherein piezo-photocatalysis can significantly increase the catalytic degradation rate using both solar and mechanical energy. Here, a ternary heterostructure PVDF/ZnO/Au (PZA) nanobrush photocatalyst with high piezo-photocatalytic efficiency was presented via low-temperature hydrothermal and chemical reduction methods. Under both solar and mechanical energy, the current response and degradation rate of the as-synthesized PZA nanobrush all increase significantly compared with that under solar alone and under mechanical energy alone, and the excellent recyclability is investigated. It is found that the PZA nanobrush with ultrasonic-assisted piezo-photocatalysis completely degrade MO of 20 mg/L in 60 min, which exhibits greater enhancement of photocatalytic activity than with stirring-assisted piezo-photocatalysis due to higher power. The high piezo-photocatalytic activity of PZA nanobrush is attributed to the surface plasmon resonance (SPR) coupling of Au and built-in electric field originating from the ZnO and PVDF, which can increase the absorption of visible light, promote the charge transfer and separation of photogenerated electrons/holes. This work introduces the SPR and bipiezotronic effect to improve plasmonic photocatalysis with PZA heterostructures, which offers a new solution in green technologies to design high-performance catalysts for the environmental remediation.

SmI3:4f5 honeycomb magnet with spin-orbital entangled Γ7 Kramers doublet

We report magnetic properties of a 4f-honeycomb iodide SmI3 made up of edge-shared network of SmI6 octahedra. High temperature magnetic susceptibility indicates {\Gamma}7 Kramers doublet ground state of Sm3+ (4f5) ions stabilized by the spin-orbit coupling and octahedral crystal electric field, which interact with Sm-I-Sm bond angle nearly 90 degree. Magnetization measurements down to 0.1 K detected antiferromagnetic correlations and an anomaly in the magnetization curve before saturation without a sign of long-range order. Relevance between SmI3 and the antiferromagnetic Kitaev material proposed in the 4f-electron system is discussed.

Intrinsic Valley Splitting and Direct-to-Indirect Band Gap Transition in Monolayer HfZrSiCO2.

Both a reasonably large valley splitting (VS) and a sufficiently long valley exciton lifetime are crucial in valleytronics device applications. Currently, no single system possesses both attributes simultaneously. Herein, we demonstrate that a Janus monolayer HfZrSiCO2 concurrently hosts a giant intrinsic VS and excitonic quasi-particles with long valley lifetime due to valley-sublayer coupling and built-in electric field. In addition, the band structure of the monolayer HfZrSiCO2 can be continuously manipulated by either an external electric field or a biaxial strain, giving rise to a tunable VS and driving a direct-to-indirect band gap transition. Moreover, the system exhibits valley-contrasting linear dichroism in exciton absorption. These results suggest that the Janus monolayer HfZrSiCO2 is a promising candidate for information applications.

Rational design of piezoelectric metamaterials with tailored electro-momentum coupling

Piezoelectric materials have wide sensing and energy transduction applications due to their inherent coupling of mechanical deformation and electric field. Recent discoveries have revealed that asymmetric or heterogeneous microstructures of piezoelectric composites can create an additional coupling of macroscopic momentum to an electric field termed electro-momentum coupling, introducing a new degree of design freedom. In this work, by employing the homogenization scheme, the physical origin of electro-momentum coupling is explored by a high throughput sweep over the microstructure design space of a piezoelectric composite system. This study shows how material constituent properties and geometrical arrangements can affect electro-momentum coupling and be smartly tailored for applications of interest.

Automatic Detection of Electric Field VLF Electromagnetic Wave Abnormal Disturbance on Zhangheng-1 Satellite

Ionosphere disturbances are mainly caused by solar activities and earth surface activities. Different electromagnetic wave disturbances show different shapes on the spectrogram, such as artificial very low frequency transmitting stations, power systems, and satellite platform disturbances which all show a horizontal shape. Due to the electric field coupling or superposition by other electromagnetic disturbances, the horizontal electromagnetic wave clarity on the spectrogram is reduced, interrupted, or disappears. Aiming at this phenomenon, based on computer vision technology, this paper proposes an automatic detection and recognition algorithm for the space electric field abnormal interference. Firstly, the horizontal electromagnetic wave on the spectrogram is detected, and then the detected window density on the horizontal line is counted. We then record and save the density anomaly windows on multiple horizontal lines at the same time, so as to realize the electric field anomaly disturbance automatic detection. The accuracy of the algorithm for detecting continuous electromagnetic wave disturbance with a wide frequency and time interval is up to 98.2%. Through the space electromagnetic disturbances automatic identification from massive data, combined with space events and multi-dimensional information, such as time, space and orbit, it is helpful to further find out the global space-time transformation laws of space events.

Theta waves, neural spikes and seizures can propagate by ephaptic coupling in vivo

Electric field coupling has been shown to be responsible for non-synaptic neural activity propagation in hippocampal slices and cortical slices. Epileptiform and slow-wave sleep activity can propagate by electric field coupling without using synaptic connections at speeds of ~0.1 m/s in vitro. However, the characteristics of the events that can propagate using electric field coupling through a volume conductor in vivo have not been studied. Thus, we tested the hypothesis that various types of neural signals such as interictal spikes, theta waves and seizures could propagate in vivo across a transection in the hippocampus. We induced epileptiform activity in 4 rats under anesthesia by injecting 4-aminopyridine in the temporal region of the hippocampus, four recording electrodes were inserted along the longitudinal axis of the hippocampus. A transection was made between the electrodes to study the propagation of the neural activity. Although 54% of the interictal spikes could propagate through the cut, only those spikes with a high amplitude and short duration had a high probability to do so. 70% of seizure events could propagate through the cut but parameters distinguishing between propagating and non-propagating seizure events could not be identified. Theta activity was also observed to propagate at a mean speed of 0.16 ± 0.12 m/s in the characteristic range of propagation using electric field coupling through the transection. The electric field volume conduction mechanism was confirmed by showing that propagation was blocked by placing a dielectric layer within the cut. The speed of propagation was not affected by the transection thereby providing further evidence that various types of neural signals including activity in the theta range can propagate by electric field coupling in-vivo.

Efficiently rejecting and concentrating Li+ by nanofiltration membrane under a reversed electric field

Efficiently concentrating dilute lithium ion (Li+) solution is very important for the synthesis of Li+ products after Li+ extraction from salt lake brine. In this work, a reversed electric field coupling nanofiltration membrane (RENF) was designed to reject and concentrate Li+ solution from a low concentration feed. The effects of membrane pore structure, electric field and electrode spacing, and feed properties on Li+ rejection of RENF process were investigated. The concentration performance and energy consumption of the RENF process were also explored. Results showed that the NF membrane with a small structural coefficient under an electric field of >8 V/cm exhibited high Li+ rejection. A Li+ rejection of 97.01% by RENF and a high permeation flux were achieved. Likewise, the RENF showed a stable concentrating performance with a high Li+ recovery for dilute Li+ solution. The energy consumption of the RENF process only has a 0.17% increase as compared with the NF process, an order of magnitude lower than that of the RO process. The high rejection performance of RENF was resulted from the synergistic effects of the reversed EF dragging force to cations and sieving effect of the NF membrane with a small structural coefficient.

Broadband and high-efficiency photonic spin-Hall effect with all-metallic metasurfaces.

In this paper, all-metallic reflective metasurfaces comprising S-shape streamline structures are proposed to achieve the photonic spin-Hall effect with average cross-polarization conversion efficiency exceeding ∼84% in the range of 8-14 µm. By comparing with all-metallic nanobricks, it is demonstrated that the electric field coupling could be enhanced by constructing a similar split ring resonator between adjacent unit elements to further improve its efficiency and bandwidth. As a proof of concept, the photonic spin Hall effect and spin-to-orbit angular momentum conversion could be observed by two metadevices with the maximum diffraction efficiency of ∼95.7%. Such an all-metallic configuration may provide a platform for various high-efficiency electromagnetic components, catenary optics, and practical applications.

Broadband infrared emissivity of Ag@SiO2 nanoparticles due to coupled transverse EM modes

The extension of plasmonic spectra to the Mid-Infrared (MIR) spectral range (2 μm to 14 μm) of Silver coated Silica (Ag@SiO2) nanoparticles was discussed in this paper. Most of the previous findings in this regard, describe the intrinsic infrared response of individual Ag@SiO2 particles or dimer and less explanation is available about the effect of electric field coupling over infrared radiation. This work provides detailed analysis about the contribution in the infrared response from the coupling of transverse EM (Electric-Magnetic) modes between the particles in the dimer. The simulated data also suggests a strong dependence of infrared radiation on the coupling of transverse EM which will facilitate the researchers in future to prepare the paint of randomly distributed Ag@SiO2 nanoparticles for passive radiative cooling. A smooth extra thin shell of Ag were deposited over SiO2 nanoparticles successfully, by employing wet chemical method. The morphology, qualitative and quantitative analysis were performed by using Transmission Electron spectroscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDS) respectively. The emissivity of the particles was measured with the Fourier Transform Infrared (FTIR) Spectrometer. The IR response of Ag@SiO2 nanoparticles was simulated by employing the Finite Element Method (FEM) with the Microwave Studio in Computer Simulation Technology (CST) software. All the simulations and experimental results were found in agreement with slight difference between them. This slight difference has been explained in Modeling and Numerical analysis section.

Study of band alignment type in Janus HfSe2/Ga2SeS and HfSeS/GaSe heterostructures

Motivated by the successful preparations and excellent properties of Janus monolayers, we construct the van der Waals (vdW) heterostructures HfSe2/Ga2SeS, and HfSeS/GaSe. Their electronic features and the type of band alignment are investigated. We find that the HfSe2/Ga2SeS exhibits the similar electronic properties to HfSe2/GaSe. Both heterostructures own type-I band alignment, in which both valence band maximum (VBM) and conduction band minimum (CBM) are provided by HfSe2 layer. However, the HfSeS/GaSe heterostructure owns type-II band alignment, in which the electrons and holes are located within the HfSeS layer and the layer of GaSe, respectively. This means that the HfSeS/GaSe heterostructure can facilitate the effective separation of the photo-generated hole and electron pairs. The band offsets of valence bands are 0.09 eV, 0.26 eV and 0.17 eV for HfSe2/GaSe, HfSe2/Ga2SeS, and HfSeS/GaSe heterostructures. The small band offsets indicate the band alignment can easily be modulated by some external means. Thus, the external electric field and interlayer coupling effect are considered to modulate the electronic properties of those heterostructures. They can simultaneously tune the band gap and induce the band alignment transition between type-I and type-II. These results indicate that HfSe2/GaSe and Janus HfSe2/GaSe heterostructures have great applications in nanoelectronic device.