High-voltage Electric Field Research Articles

Impact of high voltage electric field thawing on the quality of frozen tuna fish (Thunnus albacares)

Recently, high voltage electric field (HVEF) has been considered as a new technology in the food industry. Since this method has several benefits over conventional methods, the changes in the quality of tuna fish cuts under HVEF thawing were compared with those in control samples. The experimental tuna cubes were thawed under HVEF subjected to three different voltages from corona starting to breakdown voltage (4.5–14kV) at electrode gaps of 3, 4.5, and 6cm; the control being thawed at 20°C without being subjected to HVEF. The results showed that thawing under HVEF significantly improves thawing rate and total volatile binding nitrogen of the frozen fish cubes. The highest thawing rate was 1.78 times greater than that obtained for the control samples. However, color, texture, and protein solubility of fish samples declined as a result of thawing under HVEF. Increasing the applied voltage decreased protein solubility and affected the hardness, gumminess, cohesiveness, and chewiness of the fish samples as compared to the control. The application of HVEF thawing has the potential of extending the freshness of thawed tuna fish.

Non-linear vibration of a water drop subjected to high-voltage pulsed electric field in oil: Estimation of stretching deformation and resonance frequency

A drop of water subjected to a pulsed electric field in emulsified oil undergoes periodic stretching vibration, which is very effective for promoting the coalescence of the emulsified drops. In this study, the forces that act on a single water drop during its vibration in a pulsed electric field are analysed, and a dynamics model of the vibration of the drop is developed. The expression of the model indicates that the vibration can be described as a non-linear parametric excitation vibration, and comparison of the model predictions with experimental results reveals a good similarity. In addition, a first-order approximation of the predictions of the model is used to obtain the waveforms of the vibration, and the peak of the amplitude–frequency curve reveals the occurrence of resonance. This affords a basis for determining the optimal demulsification frequency of the emulsified oil in the pulsed electric field.

Pulsed Electrical Technologies Assisted Polyphenols Extraction from Agricultural Plants and Bioresources: A Review

The application of pulsed electrical technologies such as high voltage electrical discharges (HVED) and pulsed electric fields (PEF) have been currently proposed for promoting biocompounds extraction. Even if their principles of action are different, both of these techniques have shown to be efficient for the enhancement of polyphenols extraction from different raw materials as compared to control extraction. Depending on the product, the energy consumption, the cell disruption, the polyphenols composition, the extraction and purification steps are different when applying PEF or HVED. This paper thus reviews the current status of research on the application of HVED and PEF for extraction and purification of polyphenols from plants.

Stable deformation of droplets surface subjected to a high-voltage electric field in oil

Abstract Electro-demulsification is widely applied to the dehydration of emulsified oil. A droplet exposed to an electric field is polarised in oil and then stretched to a prolate sphere. The internal electric field distributions of prolate-sphere and spherical droplets are analysed in this work. The expressions of force acting on the droplets surface are obtained by establishing a model of stable droplet stretching deformation. An experiment is conducted to determine the draw ratio of water droplets subjected to a high electric field and exposed in four types of base oil. Comparison of the results of the experiment and model shows that the stable deformation of droplets is well predicted by the model. System parameters, such as electric field strength, droplet initial radius, interfacial tension of droplet – oil, permittivity and effect on the deformation of droplets, are also discussed.

Experimental Study of Formaldehyde Diffusion with in Building Materials in Different High-Voltage Electric Field

An experiment of formaldehyde diffusion within building materials in different high-voltage electric field using different samples had been done. High Density Fiberboard(HDF) was also tested under uniform and nonuniform electric field respectively. The experimental result indicated that formaldehyde emitted from Middle Density Fiberboard (MDF) and HDF were both affected strongly in the action of high-voltage electric field. The influence of electric field to MDF and HDF were obvious and almost same in low electric intensity, while the enhancement of equilibrium concentration of MDF was greater than that of HDF in higher electric intensity. However, the uniform and nonuniform electric field had no obvious different influence to formaldehyde diffusion. It can conclude that it was easier for formaldehyde to emit from both MDF and HDF in high voltage field. The formaldehyde diffused in the building materials can be speeded up under the action of the high-voltage electric field, which provided the feasibility of removing formaldehyde in man-made boards.

Calculation and Experiment of Vibration of Droplet Subjected to Pulse Electric Field in Emulsified Oil

Under excitation of high-voltage pulse electric field, the deformation vibration of droplet in oil was very important to electro-dehydration of emulsified oil. So far, the theoretical calculation on vibration of droplet was scarcely studied. In order to calculate the vibration of droplet, the forces acted on a single droplet needed to be analyzed, and the vibration kinetic model of droplet needed to be established. The model was resolved by method of harmonious wave balance. It was found by analysis that the resonance of droplet might occur. In the experiment, the results approximated to that of model calculation. So it was verified that the model could efficiently calculate the vibration amplitude of droplet.

Assessing the impact of electrohydrodynamic jetting on encapsulated cell viability, proliferation, and ability to self-assemble in three-dimensional structures.

In this article, we propose a systemic approach to investigate the impact of electrohydrodynamic jetting (EHDJ) encapsulation on viability, proliferation, and functionality of the encapsulated cells. EHDJ consists in applying a high-voltage electrical field between a target substrate and a jetting needle, which is fed with a suspension of cells in a polymeric solution undergoing a sol-gel transition upon contact with the target. The viability, proliferation, and self-assembling ability of SHSY5Y human neuroblastoma cell line encapsulated in 2% alginate microbeads were analyzed by confocal microscopy and DNA quantification assays. In addition, the expression of stress (HSP70B'), apoptotic (CASP3), necrotic (HMGB1), hypoxic (HYOU1, GAPDH), and adhesion (CDH2) markers was measured with reverse transcription quantitative polymerase chain reaction (qPCR). After an initial upregulation of the HSP70B' expression within 24 h, its expression decreased to the negative control level together with a decrease in the expression of CASP3. Any increase in necrotic or hypoxic marker expression was not detected, while a slight upregulation of CDH2 was observed in the first days after encapsulation, followed by its downregulation and stabilization to the control level. Furthermore, cell-laden beads started to self-assemble in three-dimensional (3D) constructs from the 3rd week after encapsulation. The results indicated that the EHDJ encapsulation method had a mild effect on cells, which after a week, fully recovered their proliferation rate and ability to self-assemble into 3D constructs.

Evaluating the potential of cell disruption technologies for green selective extraction of antioxidant compounds from Stevia rebaudiana Bertoni leaves

An increased interest has been shown by both food technologists and food industry regarding Stevia rebaudiana Bertoni leaves (Stevia) for their high content of bioactive components (phenolic compounds, vitamin C, carotenoids). The aim of this work was to study the effect of emerging technologies such as high voltage electrical discharges (HVED) and pulsed electric fields (PEF) and ultrasounds (US) on the intensification of the extraction of valuable compounds from Stevia leaves. The proposed processes combined pretreatment (HVED, PEF and US) and extraction of intracellular compounds using water as solvent at ambient temperature. The energy inputs of the treatments varied from 24 to 141kJ/kg and the results were compared to control diffusion experiments. Chlorophyll a, and b, total carotenoid, total phenolic compounds and antioxidant capacity (DPPH) were determined. A significant increase in soluble matter and antioxidant compounds was found after HVED, PEF and US-assisted extraction as compared to control samples. Results showed that HVED, PEF and US treatments improved both kinetics and extraction yield of soluble matter. These results show the ability of HVED to be used as a potential technology to enhance protein recovery using water and avoiding the use of other solvents and grinding. Chlorophyll content was significantly higher (3-fold increase) after HVED assisted extraction at 141kJ/kg in comparison to control sample (0.352 and 0.355mg/L for chlorophyll a and b, respectively). The same energy input for HVED permitted attain highest extraction diffusivities of total soluble matter (D=3.06×10−09m2/s), followed by total phenolic compounds (D=2.60×10−10m2/s) and then proteins (D=6.00×10−11m2/s).

The Influence of High Voltage Electric Field for Barley Seed Germination and its Mechanism

This paper through the effect of seed germination under different voltage that it can concluded that the influence of electric field on seed growth.Experiment to select different gradient field acts on the barley seed, the results show that the appropriate voltage of the electric field and action time has obvious promoting effect to seed germination. By discussing the electric field effect on the cell membrane permeability, using a planar lipid double model, discussed that high voltage electric field makes the cell membrane barrier height change.Ion through the barrier of risk as a result of the existence of tunneling effect will be affected by the barrier height, namely transmembrane potential.Thus an effect on the permeability of cell membrane.

The Effect of Molecules Adsorbed to the Cathode Surface on the Characteristics of a High-Voltage Gas Discharge

Relationships inherent in the processes that occur at the initial stage of a high-voltage (electric field strength E > 1 MV/cm) gas discharge with participation of nonmetal nanofilms adsorbed to the cathode are considered. It is shown that the current-voltage characteristic of the prebreakdown current obeys the Fowler-Nordheim equation corrected for the quantum character of image forces. Based on electronic polaron theory, a general expression for the field emission current at the interface between two media is obtained. It is shown that for the abovementioned fields, the field dependence of the electron tunneling current is appreciably different from the well-known classical relations.

Microscopic mechanism for the effect of adding salt on electrospinning by molecular dynamics simulations

Adding salts into polymer solution has been found to modulate the fiber structure and significantly improve the solution spinnability in electrospinning. However, the mechanisms have not been fully understood. This work adopted molecular dynamics method to investigate the dynamic behavior of poly(ethylene oxide) (PEO)/water droplet with or without dissolved NaCl salt under high-voltage electric field. Our simulation results agreed with the previous experimental reports well. We observed that some daughter droplets detach from the mother droplet due to the ions evaporation and hydration effect, which significantly accelerates the water evaporation and hence improves the solution spinnability. We also observed that some sodium ions are always coordinated with the ether oxygen group in the PEO chain. When these ions are accelerated by the electric field, the PEO chain segments follow the motion of the ions, inevitably stretching the chain and improving the fiber morphology.

The drying efficiency of electrohydrodynamic (EHD) systems based on the drying characteristics of cooked beef and mathematical modeling

The aim of this work is to select the most suitable mathematical model to describe the thin layer electrohydrodynamic (EHD) drying of cooked beef based on voltage and such geometrical characteristics as thickness and cross-sectional area of the material. To accomplish this, the EHD drying technique was employed at 0 kV, 6 kV, 14 kV, 21 kV and 32 kV for alternating current (AC). The drying temperature was 21 ± 2 ◦ C, and the drying relative humidity was 30 ± 5%, while the ambient wind speed was 0 m/s. Samples of cooked beef of different thickness and cross-sectional area were put into a high voltage electric field at 24 kV for AC. Six different mathematical drying models were then compared to simulate drying curves based on root mean square error, reduced mean square of deviation and modeling efficiency. The results showed that the drying rate of cooked beef was notably greater in the EHD system when compared to control. Both thickness and cross-sectional area of cooked beef had more impact on drying rate during the first half hour, and the Demir et al. model was the best mathematical model. Therefore, this work provides guidance for optimizing and improving the drying efficiency of EHD.

Calculation of electric and magnetic induced fields in humans subjected to electric power lines

In this work, analysis of the human body exposed to high voltage electric and magnetic fields is presented. The distribution of the electric field is obtained by using Laplace's equation. This relates the surface charge induced on the body to the potential in a reciprocal Laplace problem, which is then calculated by charge simulation method coupled with genetic algorithms to determine the appropriate arrangement of simulating charges inside the human body. The magnetic field intensity along the vertical center line of the human is calculated. Exposure to external electric and magnetic fields at power frequency induces electric field, magnetic field and currents inside the human body. The presented model for simulating electric and magnetic fields are a three dimensional field problem and introduced different types of charges to simulate the different elementary geometrical shapes of human body. The particular strength of the charge simulation method in this application is its ability to allow a detailed representation of the shape and posture of the human body. The results have been assessed through comparison induced current, electric field, magnetic field and there distribution over the body surface, as estimated in other experimental and computational work.

Dependence of effective internal field of congruent lithium niobate on its domain configuration and stability

Congruent lithium niobate is characterized by its internal field, which arises due to defect clusters within the crystal. Here, it is shown experimentally that this internal field is a function of the molecular configuration in a particular domain and also on the stability of that particular configuration. The measurements of internal field are done using interferometric technique, while the variation of domain configuration is brought about by room temperature high voltage electric field poling.

Chemical Analysis on the Effect of Pulsed Electric Fields in Pineapple Juices Preservation

The application of high voltage electric field for preservation of fruit juices has a promising scope in the food industry. The pulsed electric field (PEF) is an innovative non- thermal technique and free from bio-toxic effects. The technique has a viable solution of the problem yet faced in the food industry to prolong life and preserve and maintain quality with natural properties of the liquid food and beverages. In this study, we have treated the pineapples juice samples by different strengths of pulsed electric field such as 10, 20 and 30kV/cm for 5 minutes in each test. This study used new design of helix treatment chamber with three different lengths of 20, 30and 50cm. In these experiments, all samples were kept in same and normal condition with a temperature around 25-26 andthe humidity was between 55 and 65%. Then the observation based on chemical tests such as pH, conductivity, salinity and total dissolved solids (TDS) was recorded for all samples before and after the test. Based on results obtained by chemical parameters suggest that the injection on pulsed electric field of 30 kV/cm by the 50 cm treatment chamber has the best effect on pineapple juices characteristic as compared to the other value. The result of this experiment is encouraging and supportive of the better way for pasteurization the pineapple juices and increasing longevity of pineapple juices.

Preliminary Studies on Spanish Mackerel Fresh-Keeping Method in High-Voltage Electric Field

An innovative fresh-keeping method for aquatic products is presented in this article. Spanish mackerel (Scomberomorus niphonius) were treated with a high-voltage electric field (HVEF) at different voltages and times and then stored in a refrigerator at 4°C. Bacteria count, total volatile basic nitrogen (TVB-N), sensory index, proximate composition, and pH were measured to evaluate the fresh-keeping effect of the proposed method. Results indicate that HVEF can restrain bacteria growth, reduce TVB-N, and delay sensory score decline; and that 45 kV for 20 min is the optimal treatment parameter of HVEF for extending Spanish mackerel shelf life. Results also suggest a potential application for HVEF treatment in aquatic products preservation.

Interferometric measurement of the internal field of lithium niobate without high-voltage electric field poling

A simple interferometric technique for measurement of the internal field (IF) in a ferroelectric crystal has been proposed. This technique has several advantages over the other methods used previously for evaluation of IFs in ferroelectric crystals. Here, the electro-optic property of lithium niobate is exploited for quantitative analysis of its IF. The strength of IF obtained using this technique lies within the range given in the literature. However, at frustrated domain inversion state, the measured value of IF shows a reduced value. A possible reason for this reduction based on the defect model has been discussed.

Significantly improved surface flashover characteristics of insulators in vacuum by direct fluorination

Seeking an insulator supporting high voltage and short pulsed-power electric field in vacuum is an important topic especially for some sophisticated equipments. The voltage breakdown along the surface of insulator in vacuum (i.e. surface flashover) is one of the most serious problems for insulators, and it greatly limits the overall performance of a vacuum-dielectric system. The improvement of surface flashover characteristics of insulators in vacuum become a significant challenge for the development of high voltage pulsed-power devices. Herein, we report a simple and convenient avenue to achieve the high surface flashover performance of high density polyethylene (HDPE) in vacuum based on direct fluorination technique. The physicochemical properties of the fluorinated HDPE (i.e., surface morphology, the chemical component, structure and dielectric capability) were comparatively investigated with the untreated HDPE. The surface flashover characteristics of HDPE in vacuum were mainly discussed. The performance of HDPE at different fluorination temperature was also investigated. The results demonstrated that the direct fluorination strategy developed in this work is an effective means to improve the surface dielectric capability of insulators in vacuum. It is believed to provide a novel possibility for the common insulators applied in high electric field vacuum environments.

Compressive stress profiles of chemically strengthened glass after exposure to high voltage electric fields

The ion exchange process for chemical strengthening of glass involves an inter-diffusion of alkali ions between the glass and a molten salt bath. In most commercial glasses, this comprises an exchange of Na+ ions in the glass for larger K+ ions from the salt bath. The stuffing of K+ ions into sites previously occupied by Na+ in the glass results in the formation of a compressive stress profile in the glass. In the absence of stress relaxation, this compressive stress profile largely follows the concentration profile of the K+ ions. Any subsequent migration of K+ ions within the glass would result in a change in this stress profile, which could lead to different mechanical behaviors of the glass. In particular, a reduction of the surface compressive stress could lead to a compromise in the retained strength of the glass, making it more susceptible to failure. Recent work has shown that chemically strengthened glass can be used as an effective substrate material for organic thin film transistors (TFTs), since the temperatures involved with organic TFT deposition are low enough to avoid any compromise in the compressive stress profile. This opens the possibility of fabricating high strength organic TFT displays. However, the question remains as to whether the exposure of the glass to an electric field may lead to the diffusion of the alkali ions and a corresponding alteration of the stress profile, which could compromise the strength of the organic TFT device. In this paper, we demonstrate that there is no change in the stress profile of Corning® Gorilla® Glass 3 after subjecting the glass to much higher voltage dc fields compared to the maximum field that would be exhibited in an organic TFT device. The stress profile is modified only after treating the glass at sufficiently high temperature, where alkali migration becomes thermally activated.

Thoron and thoron progeny measurements in German clay houses

In recent years, elevated thoron concentrations were found in houses built of unfired clay. In this study experiments were carried out in 17 traditional and modern clay houses in Germany to obtain an overview of indoor thoron in such houses. Long-term measurements over an 8-week period were performed using a newly developed Unattended Battery-Operated Progeny Measurement Device (UBPM) for measuring thoron progeny. This instrument uses a high-voltage electric field to precipitate radon and thoron progeny on nuclear track detectors. Additional active and passive measurements of radon, thoron and their progeny were performed. The equilibrium equivalent thoron concentration was found to be between 2 and 10 Bq m(-3). Gas concentrations were found to be between 20 and 160 Bq m(-3) for radon and between 10 and 90 Bq m(-3) for thoron 20 cm from the wall. The thoron exposure contributes significantly to the inhalation dose of the dwellers (0.6-4 mSv a(-1)).