Electric Field Parameters Research Articles

Control of electronic and optical properties of a laser dressed double quantum dot molecule by lateral electric field

We study the confined states of a molecule formed by two laterally coupled quantum dots. The static electric field and incident plane wave laser field are considered with different polarization. The respective Shrödinger equation is obtained in the framework of the high-frequency limit of Floquet theory. It is shown that the electric field has a qualitative impact on the spatial symmetry of electronic states. An in-depth study of electric and laser field combined effects show a strong correlation between them. Additionally, we show that the linear, nonlinear and total optical absorption coefficients and relative refractive index of the considered structure can be effectively tuned by changing electric field strength and intense laser field parameter. Our results indicate the possibility of controlling the optical response of double quantum dots molecule for future applications in nanostructure-based quantum information science.

Starting a Fire Without Flame: The Induction of Cell Death and Inflammation in Electroporation-Based Tumor Ablation Strategies.

New therapeutic strategies and paradigms are direly needed for the treatment of cancer. While the surgical removal of tumors is favored in most cancer treatment plans, resection options are often limited based on tumor localization. Over the last two decades, multiple tumor ablation strategies have emerged as promising stand-alone or combination therapeutic options for patients. These strategies are often employed to treat tumors in areas where surgical resection is not possible or where chemotherapeutics have proven ineffective. The type of cell death induced by the ablation modality is a critical aspect of therapeutic success that can impact the efficacy of the treatment and systemic anti-tumor immune system responses. Electroporation-based ablation technologies include electrochemotherapy, irreversible electroporation, and other modalities that rely on pulsed electric fields to create pores in cell membranes. These pores can either be reversible or irreversible depending on the electric field parameters and can induce cell death either alone or in combination with a therapeutic agent. However, there have been many controversial findings among these technologies as to the cell death type initiated, from apoptosis to pyroptosis. As cell death mechanisms can impact treatment side effects and efficacy, we review the main types of cell death induced by electroporation-based treatments and summarize the impact of these mechanisms on treatment response. We also discuss potential reasons behind the variability of findings such as the similarities between cell death pathways, differences between cell-types, and the variation in electric field strength across the treatment area.

Flexoelectric fluid membrane vesicles in spherical confinement

The morphology of spherically confined flexoelectric fluid membrane vesicles in an external uniform electric field is studied numerically. Due to the deformations induced by the confinement, the membrane becomes polarized resulting in an interaction with the external field. The equilibrium shapes of the vesicle without electric field can be classified in a geometrical phase diagram as a function of scaled area and reduced volume (Kahraman O. et al., EPL, 97 (2012) 68008; Kahraman O. et al., New. J. Phys., 14 (2012) 095021). When the area of the membrane is only slightly larger than the area of the confining sphere, a single axisymmetric invagination appears. A non-vanishing electric field induces an additional elongation of the confined vesicle which is either perpendicular or parallel depending on the sign of the electric field parameter. Higher values of the surface area or the electric field parameter can reduce the symmetry of the system leading to more complex folding. We present the resulting shapes and show that transition lines are shifted in the presence of an electric field. The obtained folding patterns could be of interest for biophysical and technological applications alike.

Nonlinear Electrophysical Phenomena in Ionic Dielectrics with a Complicated Crystal Structure

The methods of quasi-classical kinetic theory are used to study the phenomena of nonlinear relaxation polarization in ionic dielectrics with a complicated crystal lattice structure (layered crystals, ceramics, perovskites, vermiculites, etc.) characterized by high ionic conductivity. A special case of materials of this class are proton semiconductors and dielectrics (mica, talc, pyrophyllite, etc.) characterized by high proton conductivity in fairly wide ranges of field parameters (100 kV/m – 1000 MV/m) and temperatures (1–1500 K). Based on the continuity equation for the ion current, a generalized kinetic equation is constructed that describes transfer of electric charge in ionic dielectrics in an alternating polarizing field with blocking electrodes. The nonlinearity of the mathematical model is ensured by the dependences of the diffusion coefficients and ion mobility on the parameters of the inhomogeneous electric field in the dielectric. It is shown that the Fokker–Planck equation, known in the kinetic theory, is a zero approximation of the generalized nonlinear kinetic equation with respect to a small dimensionless parameter. The dielectric polarization is written from the solution of the Fokker–Planck equation in the infinite approximation of the perturbation theory (k = 1, 2, 3, ...) for an arbitrary value of the multiplicity factor r over the alternating field frequency. The spectra of a complex dielectric permittivity constructed at the fundamental frequency of the alternating field (r = 1) taking into account all subsequent (starting from the second one) approximations of the perturbation theory (k > 1) differ significantly from the classical laws of the Debye dispersion (corresponding to the first approximation of the perturbation theory (k = 1)). The theoretical foundations have been laid for the program algorithms of computer prediction of properties and parameters of electrical materials for the functional elements of the microelectronic device circuits, isolation technology, and non-volatile high-speed memory devices.

Method and Mechanism of Regulating Rheological Properties of Water-Based Drilling Fluid by High-Frequency and High-Voltage Alternating Current Electric Field

Summary The rheology of drilling fluid is commonly regulated by chemical methods. In this work, a physical method of a high-frequency and high-voltage alternating current (AC) electric field to regulate the rheological properties of water-based drilling fluid is established. The effects of the electric field on the continuous phase and dispersed phase, as well as two kinds of water-based drilling fluids, were investigated, and the response relationship among rheological properties modeled by Bingham and Herschel-Bulkley (H-B) models and electric-field parameters was explored. Results showed that water conductivity increased when voltage reached 4 kV, whereas it was restored to the original state after 3 hours in the absence of an electric field, showing a memory effect. The effect was also observed on bentonite suspension, whose plastic viscosity increased with the aid of an electric field and decreased over time. Voltage showed the greatest effect on bentonite-suspension viscosity, followed by frequency and pulse-width ratio. Under the condition of voltage of 5 kV, frequency of 5 kHz, and pulse-width ratio of 80%, there was a maximum increase of 50% in viscosity. The addition of salts caused bentonite-suspension flocculation, and electric field reduced the consistency coefficient and relieved flocculation state. When polymers were incorporated in bentonite suspension, the electric field could decrease the adsorption amount between clay particles and polymeric additives such as amphoteric and acrylamide-based polymers. For two typical drilling fluids, the voltage of an introduced electric field was the main controlling factor to change the rheological properties; their plastic viscosity and consistency coefficient both started to increase when voltage reached 4 kV.

A finite element method for the generalized Ericksen model of nematic liquid crystals

We consider the generalized Ericksen model of liquid crystals, which is an energy with 8 independent “elastic”constants that depends on two order parameters n (director) ands(variable degree of orientation). In addition, we present a new finite element discretization for this energy, that can handle the degenerate elliptic part without regularization, with the following properties: it is stable and it Γ-converges to the continuous energy. Moreover, it does not require the mesh to be weakly acute (which was an important assumption in our previous work). Furthermore, we include other effects such as weak anchoring (normal and tangential), as well as fully coupled electro-statics with flexo-electric and order-electric effects. We also present several simulations (in 2-D and 3-D) illustrating the effects of the different elastic constants and electric field parameters.

Carbon Composite Nanofibers Produced By Hybrid-Spinning of Polyacrylonitrile Precursor As Anodes for Lithium Ion Batteries

In this study, polyacrylonitrile (PAN) nanofibers are produced through a novel technique known as Hybrid-Spinning (HS) and used as a precursor for anodes in lithium ion batteries (LIBs). HS is a combination of two fiber-producing technologies: Centrifugal spinning (CS) and Electrospinning (ES). The use of HS for nanofiber production is promising due the limitations of both CS and ES. CS produces a high yield of nanofibers through centrifugal forces but is unable to account for the control of the fiber morphology, which limits the potential of the nanofibers-production through this technology. ES, on the other hand, produces nanofibers through electrical forces, allowing for a high degree of fiber morphology control by alternating the electrical field and process parameters. However, the high cost, safety concerns, and low yield of ES makes it unsuitable for the mass production of nanofibers in industry. Therefore, Hybrid Spinning has a high potential in changing the nanofiber industry by removing the limitations of both ES and FS while also minimizing safety-concerns, cost, and environmental impact. This work documents the morphology and characteristics of PAN nanofibers produced through HS and compares them to nanofibers made through FS and ES. The PAN fibrous mats obtained by HS are then converted into carbon nanofibers by calcination and directly used as free-binder anodes in lithium-ion batteries. The electrochemical performance of the HS carbon-fiber anodes is then compared with that prepared by ES and CS to determine the viability of HS technology with respect to Lithium-ion battery applications.

Applicability of Pulsed Electric Field (PEF) Pre-Treatment for a Convective Two-Step Drying Process.

Available literature and previous studies focus on the Pulsed Electric Field (PEF) parameters influencing the drying process of fruit and vegetable tissue. This study investigates the applicability of PEF pre-treatment considering the industrial-scale drying conditions of onions and related quality parameters of the final product. First, the influence of the PEF treatment (W = 4.0 kJ/kg, E = 1.07 kV/cm) on the convective drying was investigated for samples dried at constant temperatures (65, 75, and 85 °C) and drying profiles (85/55, 85/65, and 85/75 °C). These trials were performed along with the determination of the breakpoint to assure an industrial drying profile with varying temperatures. A reduction in drying time of 32% was achieved by applying PEF prior to drying at profile 85/65 °C (target moisture ≤7%). The effective water diffusion coefficient for the last drying section has been increased from 1.99 × 10−10 m2/s to 3.48 × 10−10 m2/s in the PEF-treated tissue. In case of the 85/65 °C drying profile, the PEF-treated sample showed the highest benefits in terms of process efficiency and quality compared to the untreated sample. A quality analysis was performed considering the colour, amount of blisters, pyruvic acid content, and the rehydration behavior comparing the untreated and PEF-treated sample. The PEF-treated sample showed practically no blisters and a 14.5% higher pyruvic acid content. Moreover, the rehydration coefficient was 47% higher when applying PEF prior to drying.

Magnetic transition due to the inter-singlet spin-exchange interaction and elastic softening by the interplay of electric quadrupoles in the distorted kagome lattice antiferromagnet Tb3Ru4Al12

The distorted kagome lattice antiferromagnet ${\mathrm{Tb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ with a hexagonal structure has the N\'eel temperature ${T}_{\mathrm{N}}=22$ K. To clarify the $4f$-electronic state and an influence of electric quadrupoles in ${\mathrm{Tb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$, ultrasonic measurements on a single-crystalline sample at zero magnetic field and under fields were carried. A characteristic elastic softening of the transverse modulus ${C}_{66}$ originating from a quadrupole interaction was found. The crystal electric field parameters were determined to reproduce ${C}_{66}$, magnetic susceptibilities, and magnetization curves. The obtained level scheme is that the ground and first excited states are singlets, despite the existence of both the magnetic transition and the quadrupole interaction, indicating that ${\mathrm{Tb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ is a curious compound. The positive sign of the quadrupole-quadrupole coupling constant for ${C}_{66}$ indicates a ferroquadrupolar-type interaction of the electric quadrupole ${O}_{xy}$ or ${O}_{2}^{2}$. The anisotropic magnetic field dependencies of ${T}_{\mathrm{N}}$ in the field along [100] and [001] were also clarified.

Effect of interphase and interpulse delay in high-frequency irreversible electroporation pulses on cell survival, membrane permeabilization and electrode material release

To achieve high efficiency of electroporation and to minimize unwanted side effects, the electric field parameters must be optimized. Recently, it was suggested that biphasic high-frequency irreversible electroporation (H-FIRE) pulses reduce muscle contractions. However, it was also shown for sub-microsecond biphasic pulses that the opposite polarity phase of the pulse cancels the effect of the first phase if the interphase delay is short enough. We investigated the effect of interphase and interpulse delay (ranging from 0.5 to 10,000 µs) of 1 µs biphasic H-FIRE pulses on cell membrane permeabilization, on survival of four mammalian cell lines and determined metal release from aluminum, platinum and stainless steel electrodes. Biphasic H-FIRE pulses were compared to 8 × 100 µs monophasic pulses. We show that a longer interphase and interpulse delay results in lower cell survival, while the effects on cell membrane permeabilization are ambiguous. The cancellation effect was observed only for the survival of one cell line. Application of biphasic H-FIRE pulses results in lower metal release from electrodes but the interphase and interpulse delay does not have a large effect. The electrode material, however, importantly influences metal release – the lowest release was measured from platinum and the highest from aluminum electrodes.

AC electrokinetic immobilization of organic dye molecules

The application of inhomogeneous AC electric fields for molecular immobilization is a very fast and simple method that does not require any adaptions to the molecule’s functional groups or charges. Here, the method is applied to a completely new category of molecules: small organic fluorescence dyes, whose dimensions amount to only 1 nm or even less. The presented setup and the electric field parameters used allow immobilization of dye molecules on the whole electrode surface as opposed to pure dielectrophoretic applications, where molecules are attracted only to regions of high electric field gradients, i.e., to the electrode tips and edges. In addition to dielectrophoresis and AC electrokinetic flow, molecular scale interactions and electrophoresis at short time scales are discussed as further mechanisms leading to migration and immobilization of the molecules.Graphical

Simulation and Experiment on Micro-Texture of Bionic Surface Array

In view of the anti-friction and anti-adhesion characteristics of bionic surface structure in bioengineering, a new processing technology of hole-to-hole strip sprinkler tool is proposed innovatively to achieve precision and large-scale surface micro-texture manufacturing. On the basis of electrolytic jet mask processing, the array structure of strip nozzle with variable hole spacing was designed. Combining with electric field parameters, the model was established by COMSOL Multiphysics software and the simulation analysis was carried out. Experiments show that the technology has high processing efficiency, low surface roughness, regular morphology and good consistency of the fabricated arrays, which provides a new idea for the fabrication of bionic micro-texture arrays.

Обеспечение электромагнитной совместимости морской техники при возникновении электростатических разрядов

The paper describes the problem of electromagnetic compatibility for electrostatic discharge (ESD), which is most actual for ships where all systems are highly automated and susceptible to ESD digital technology. The results of electromagnetic compatibility tests of ship systems after their installation on the vessel allow to conclude that it is not enough to fulfill only the existing ESD immunity requirements of the Russian Maritime register of shipping which are currently confirmed by ESD tests in the laboratory. ESD methods and reasons have been analyzed. The possible accumulated potentials and parameters of currents, voltages and field strengths during discharge are presented. The existing ESD immunity standards are being considered. The scheme of the developed and certified generator of electrostatic discharges ESD – 25000 is presented. The most frequent defects under the influence of ESD are given. There have been formulated the equivalent schemes of the electric equipment housing at different lengths of grounding of the housing and the methods of connecting the cover with the housing. The results of measurements of electric field and magnetic field parameters are presented. The results of modeling and experiments are compared. The developed sensors, methods of their calibration and obtained technical characteristics are being tested. There are given the parameters and forms of ESD voltage and current, experimental data of ESD secondary effects in the EE hull and adjacent equipment, results of discharges in the ship's cable, interference in the supply network through secondary power sources. The most effective design and ESD protection methods have been analyzed

In‐depth analysis of the static behaviour of a SiC MOSFET and of its associated parameters using both compact modelling and physical simulation

In this study, the authors aim at investigating the static electro-thermal behaviour of two new generations of power silicon carbide metal oxide semiconductor field effect transistors (SiC MOSFETs). The studied devices are commercialised and have a vertical structure. Two approaches are followed: device modelling and physical simulation. An improved compact model based on an accurate method of parameters extraction is introduced. The simulation results obtained with this method perfectly fit the measurements. The parameters extracted precisely from the model (threshold voltage, saturation region transconductance and transverse electric field parameter) are used to accurately analyse the static behaviour of 1200 V Gen 2 and 900 V Gen 3 SiC MOSFETs. Physical simulation is conducted to understand the impact of the temperature and the physical parameters on the threshold voltage and the on-state resistance.

Rapid Production of Liposomes using Electrodialysis

Liposomes, enclosed spherical vesicles that mimic the cell membrane, are currently used for a large variety of scientific and medical applications, including drug delivery into tumors. They may be produced by employing a large variety of methods such as sonication, extrusion, organic phase separation, and several others. Dialysis, i.e. separation of a detergent phase by filtration, is a very affordable approach for liposome production. Nonetheless, it may imply the use of dedicated equipment, large amounts of exchange buffers, and extended time required for production. In order to alleviate many of these shortcomings, we investigated liposome production by employing electrodialysis as a fast and reliable method. Unlike traditional dialysis, the proposed approach encompasses quick separation of the charged detergent from the bulk, driven by an electrophoretic force. Our work shows that liposomes may be obtained from multiple lipid mixtures much faster than traditional dialysis and by employing multiple detergents. In addition, we also investigated successful loading of fluorescent dyes into liposomes as well as further separation during electrodialysis. Physical characterization and load assessments were performed by Dynamic Light Scattering (DLS) and fluorescence spectroscopy (FS), which were also employed for stability studies. Our investigations also focused on examining the influence presented by lipid composition, detergent chemistry, concentrations, and electric field parameters on the produced liposomes. We concluded that electrodialysis may prove an extremely useful and versatile method for fast and reliable production of stable liposomes to be used for scientific and medical applications.

Systematic Study of the Impact of Pulsed Electric Field Parameters (Pulse/Pause Duration and Frequency) on ED Performances during Acid Whey Treatment.

Processing acid whey is still a challenge for the dairy industry due to its high lactic acid and mineral contents. Their removal processes represent a high investment and running cost in addition to significant production of polluting effluents. A previous study showed that the use of electrodialysis with the application of pulsed electric fields (PEFs) was sufficiently efficient to produce dryable acid whey with reduced scaling issues during the process. In the present work, eight PEF conditions using different pulse/pause durations and frequencies were tested for 1) process optimization and 2) understanding of the underlying mechanisms involved in PEF process improvements. Best results were obtained for PEF conditions (5 s/5 s) and (15 s/15 s) with almost complete scaling mitigation and minimal energy consumption (5.3 ± 0.4 Wh/g of lactic acid vs. 9.33 ± 1.38 Wh/g for continuous current). Longer pause times also led to better divalent ion demineralization at the expense of sodium elimination induced by stronger affinity with the membrane and longer retention times. For the first time, PEF parameters of relatively low frequencies (<1) were studied in sub-limiting current conditions on a complex solution such as acid whey.

High-intensity pulsed electric fields or thermal treatment of broccoli juice: the effects of processing on minerals and free amino acids

This research evaluated the influence of high-intensity pulsed electric fields (HIPEF) parameters, electric field strength (15–35 kV/cm), treatment time (500–2000 μs) and polarity (monopolar or bipolar mode) on minerals and free amino acids content of broccoli juice. Additionally, HIPEF-processed broccoli juice was compared with thermally treated (90 °C/60 s) and untreated juices. In general, HIPEF parameters significantly influenced the content of minerals and free amino acids, except Cu, S, P, Trp, Ala, His, and Tyr, which were not influenced by electric field strength, treatment time and/or polarity. At the strongest HIPEF conditions (35 kV/cm for 2000 μs) in bipolar mode, an increment or not significant changes in the mineral content in comparison to fresh broccoli juice was observed. Iron (214.2%), manganesus (117.7%) and zinc (148.4%) were the minerals with the greatest relative augment. While, the highest amino acid retention was histidine (159.3%), and lysine (157.8%). Increment in mineral content was associated to electrode corrosion; while the increase in amino acid content was related to the increment in the activity of enzymes associated with their biosynthesis. Changes in the content of free amino acids depended on HIPEF treatment conditions applied and the amino acid evaluated. Significant losses of minerals and free amino acids were reached after thermal processing of broccoli juice. Overall, HIPEF-treated broccoli juice had superior mineral and free amino acids content than those thermally treated.

Трехкоординатный электроиндукционный датчик напряженности электрического поля в виде трех взаимно перпендикулярных дисков

Measuring the parameters of electric fields affecting technical and biological objects is impossible without the use of electric field strength sensors. Accurate measurement and control of electric field strength levels is challenging. This is due to the fact that the intensity is a vector quantity, characterized not only by the modulus, but also by the direction. The existing wide variety of strain gauges of various shapes (cubic, cylindrical, spherical), the principle of action (directional and non-directional reception) and design features (case, bodyless) do not provide the desired metrological characteristics. Therefore, the work related to the development of electric field strength sensors does not stand still and is relevant. The aim of the study is to create a frameless threeaxis sensor of electric field strength, the calculation of which would be simple as for the case, and the simplicity of design and low weight as for the frameless sensors. The sensor created as a result of research is structurally represented by three mutually perpendicular dielectric disks, the bases of which are conducting sensitive elements. The sensor depending on the desired error has a different spatial measurement range and the larger the error, the wider the range. For a measurement error not exceeding 10 %, the maximum possible spatial measurement range will be a = 0,4. Therefore, the minimum possible distance to the field source, at which the sensor error does not go beyond 10 %, will be d = 2,5R, where R is the radius of the sensor disk

Effects of High-Voltage Electric Field Process Parameters on the Water-Holding Capacity of Frozen Beef during Thawing Process

In order to investigate the thawing time and water-holding capacity under high-voltage electric field (HVEF), we studied the thawing experiments of frozen beef in a multiple needles-to-plate electrode system. The electric field, thawing characteristics, and quality parameters during the thawing process were measured. The results showed that compared with the control, the thawing time of beef under HVEF was significantly shortened, the thawing rate increased significantly, the drip loss decreased, and the centrifugal loss increased during the thawing process. By the response surface analysis and single-factor analysis of variance, the best thawing conditions for each thawing parameter were determined. It provides a theoretical basis and practical guidance for understanding the characteristic parameters of the high-voltage electric field thawing technology.

Suppression of Leidenfrost phenomenon of nanodroplets through an external electric field

When a droplet comes into contact with a hot sold surface, heat is conducted from the surface to the droplet, triggering phase change of the droplet. As the surface temperature increases, the droplet undergoes successively evaporation, nucleate boiling, and transition boiling. When the surface temperature increases further and exceeds a critical one, a vapor layer immediately generates between the droplet and surface, and separates the droplet from the surface, making the droplet depart from the surface. This phenomenon is commonly termed the Leidenfrost phenomenon and the critical temperature is referred as Leidenfrost point (LFP). The Leidenfrost phenomenon significantly reduces heat dissipation from a surface because heat is transported from the surface to a droplet only by heat conduction of the vapor film, so that the surface temperature abruptly increases, which may lead to surface burnout. Various methods have been developed to suppress the Leidenfrost phenomenon. Among these methods, electrostatic suppression of the Leidenfrost phenomenon by external electric fields exhibits many advantages, and hence is considered as a very promising method. Many efforts have been devoted to understanding the mechanisms behind electrostatic suppression and optimizing the parameters of electric fields. These studies focused on droplets with sizes ranging from a few millimeters to a few tens of microns. With the development of micro/nano technique, heat transfer enhancement by manipulation of micro/nanodroplets has attracted a great deal of attention. Thus, how to suppress the Leidenfrost phenomenon of micro/nanodroplets becomes an interesting problem. In this work, the Leidenfrost phenomenon of a nanoscale water droplet on gold plates with different wettabilities is first investigated via molecular dynamics simulations. The main emphasis is focused on how the surface wettability affects the LFP. Our simulations show that, with the same plate temperature of 700 K, only evaporation on the free surface of the droplet takes place on a hydrophilic surface, whereas the Leidenfrost phenomenon is triggered on a moderate wettability surface and a hydrophobic surface. Moreover, the triggering time is earlier on the hydrophobic surface. The further simulations demonstrate that the Leidenfrost phenomenon can be triggered on the hydrophilic surface by increasing the surface temperature to 1132 K , whereas it can also be suppressed on both the moderate wettability surface and the hydrophobic surface by decreasing the surface temperature. Therefore, it is concluded that the LFP increases as the increased surface hydrophilicity. By charging gold atoms in two specific region of the gold plate bottom, an electric field parallel to the surface is generated. This electric field is employed to suppress the Leidenfrost phenomenon. With the same plate temperature of 700 K, it is found that the Leidenfrost phenomenon is successfully suppressed on both the moderate wettability surface and the hydrophobic surface by the electric field, but a stronger electric field is required by the hydrophobic surface. The electric field enhances the interaction between water molecules and gold atoms, making the surface more wettable by the droplet. In other words, the electric field enhances the surface hydrophilicity, which is responsible for the electrostatic suppression of the Leidenfrost phenomenon.