Optimal Electric Field Research Articles

High-Frequency Pulsed Electric Field Ablation in Beagle Model for Treatment of Prostate Cancer

Simple SummaryAround 248,530 newly diagnosed in 2021, prostate cancer has been the most frequently diagnosed cancer in the USA. Rapid decellularization preserving acellular tissues is essential for accurate treatment and regeneration in affected areas. Our study aimed to assess the safety and efficacy of high-frequency pulsed electric field (HF-PEF) in a beagle model for the treatment of prostate cancer. We confirmed that HF-PEF of 1800 V/cm, 100 μs width, 2 ms interval successfully decellularized the prostate tissue after 4 hours, and the tissues were almost regenerated in 28 days. IRE with HF-PEF has therapeutic potential to treat prostate cancer while minimizing damage to the surrounding tissues.Conventional irreversible electroporation (IRE) with low-frequency pulsed electric field (LF-PEF) is used to induce cell death; however, it has several disadvantages including a long procedure time and severe muscle contraction due to high-voltage electric field. This study investigates a novel IRE protocol with high-frequency pulsed electric field (HF-PEF) of 500 Hz repetition to ablate the prostate tissue in beagles for treatment of prostate cancer. A finite element analysis was performed to validate optimal electrical field strength for the procedure. In total, 12 beagles received HF-PEF of 500 Hz and were sacrificed at 4 h, 4 days, and 28 days (3 each). The remaining three beagles underwent sham procedure. The outcomes of HF-PEF were assessed by histological responses. HF-PEF successfully decellularized the prostate tissues 4 h after the treatment. The prostate glands, duct, and urethra were well preserved after IRE with HF-PEF. The ablated prostatic tissues were gradually regenerated and appeared similar to the original tissues 28 d after IRE with HF-PEF. Moreover, electrocardiography and hematology demonstrated that IRE with HF-PEF did not seriously affect the cardiac tissue. HF-PEF was effective and safe in the beagle prostate and effectively induced the ablation and gradually recovered with cellular regeneration.

Novel Spiral Silicon Drift Detector with Equal Cathode Ring Gap and Given Surface Electric Fields.

Since the advent of semiconductor detectors, they have been developed for several generations, and their performance has been continuously improved. In this paper, we propose a new silicon drift detector structure that is different from the traditional spiral SDD structure that has a gap between the cathode ring and the width of cathode ring, increasing gradually with the increase of the radius of the cathode ring. Our new structure of spiral SDD structure has equal cathode ring gap and a given surface electric field, which has many advantages compared with the traditional structure. The novel SDD structure controllably reduces the area of silicon oxide between the spiral rings, which in turn reduces the surface leakage current due to the reduction of total oxide charge in the silicon oxide and electronic states on the silicon/silicon oxide interface. Moreover, it has better controllability to adjust this spiral ring cathode gap to achieve better surface electric field distribution, thus realizing the optimal carrier drift electric field and achieving the optimal detector performance. In order to verify this theory, we have modeled this new structure and simulated its electrical properties using the Sentaurus TCAD tool. We have also analyzed and compared different spiral ring cathode gap structures (from 10 µm to 25 µm for the gap). According to the simulation results of potential, electric field, and electron concentration, we have obtained that a spiral ring cathode gap of 10 µm has the best electrical characteristics, more uniform distribution of potential and surface electric field, and a more smooth and straight electron drift channel.

Electrical and aerodynamic characteristics of sliding discharge based on a microsecond pulsed plasma supply

Plasma flow control technology has broad prospects for application. Compared with conventional dielectric barrier discharge plasma actuators (DBD-PA), the sliding discharge plasma actuator (SD-PA) has the advantages of a large discharge area and a deflectable induced jet. To achieve the basic performance requirements of light weight, low cost, and high reliability required for UAV (Unmanned Aerial Vehicle) plasma flight experiments, this work designed a microsecond pulse plasma supply that can be used for sliding discharge plasma actuators. In this study, the topology of the primary circuit of the microsecond pulse supply is determined, the waveform of the output terminal of the microsecond pulse plasma supply is detected using the Simulink simulation platform, and the design of the actuation voltage, the pulse frequency modulation function and the construction of the hardware circuit are achieved. Using electrical diagnosis and flow field analysis, the actuation characteristics and flow characteristics of sliding discharge plasma under microsecond pulse actuation are studied, the optimal electrical actuation parameters and flow field characteristics are described.

Novel assistive technologies for efficient freezing of pork based on high voltage electric field and static magnetic field: A comparative study

To enhance the freezing rate and thawed product quality of pork tenderloin, an experimental study was conducted using the high voltage electric field and static magnetic field separately during freezing. Pork tenderloin pieces were frozen at −20 °C under several high voltage electric fields (10 kV/m (HVEF1), 30 kV/m (HVEF3), 50 kV/m (HVEF5)) and magnetic fields of 2 mT (MF2), 4 mT (MF4), 6 mT (MF6) and 8 mT (MF8). The effects of different methods on freezing rate, ice crystal size as well as the distribution, and product quality after thawing were investigated. The freezing time of pork tenderloin was reduced by 40.04% and 37.81% respectively, under the optimal electric and magnetic field conditions tested. The thawing loss decreased from 5.7% of conventional freezing to 1.7% of HVEF1 and 2.4% of MF2, respectively. In addition, both high-voltage electric field freezing and magnetic field freezing can better maintain the moisture state in the sample. The results for color and pH confirmed that the thawed product quality using HVEF1 and MF2 was superior to that obtained under other conditions. The myofibrillar protein in the thawed products obtained from HVEF1 and MF2 treatments was also found to be thermally more stable. It is noteworthy that the HVEF1 treated sample has the highest umami signal and the lowest salty signal. Considering the enhanced freezing efficiency and improved quality, application of HVEF1 is recommended as a viable strategy to produce high-quality frozen pork tenderloin. Industrial relevanceThe slow freezing rate of frozen meat products and serious deterioration of product quality are the key problems. Therefore, improving the efficiency of freezing is desirable. This study provides ideas for pork preservation. It caters to the need of industrial production of meat product where better efficiency freezing process is highly desirable, and the findings of this study is beneficial to the meat processing industry.

Influencing factors for nutrient removal from piggery digestate by coupling microalgae and electric field

ABSTRACT Microalgae show great potential for nutrient removal from piggery digestate. However, full-strength piggery digestate have been found to severely inhibit microalgal growth. In this study, microalgae were coupled into the electric field (EF)system to form an electric field-microalgae system (EFMS). The effects of EF characteristics and environmental conditions on the growth of Desmodesmus sp. CHX1 and the removal of nitrogen and phosphorus in EFMS were explored. The results indicated that the optimal EF parameters for forming a fine EFMS were electrode of Zn (anode)/graphite (cathode), electric frequency of three times per day (10 min/time) and voltage of 12 V. The suitable light intensity and microalgae inoculation concentration for the EFMS were 180 μmol photons/(m2·s) and 0.2 g/L, respectively. Ammonium nitrogen and total phosphorus removal efficiencies were 65.38% and 96.16% in the piggery digestate by EFMS under optimal conditions. These results indicate that EFMS is a promising technology for nutrient removal from piggery digestate.

Investigating and Simulating the Electrostatic Field of Four Types of Collectors in Electrostatic Dust Filters

Electrostatic dust purifiers are widely used in many industries such as thermal power plants, cement plants, waste incineration and glass production. Optimization of the electrode and collector is important for higher efficiency (to achieve high efficiency) in electrostatic dust filtration. This study examines the electrostatic properties of four types of collector plates: flat, curved, spike, and spike with groove. The electric field strength, the charge density, the velocity of movement, and the collection efficiency are analysed for each type of collector. The inflow of air is perpendicular to the collector plate instead of parallel in traditional models, which improves the efficiency. The velocity of dust towards the collector plate depends on the electrostatic force and the velocity field around the collector. The Deutsch model is used to determine the performance among receiver plate types. The results show that the spike plate achieves the best collection efficiency because of the optimal static electric field and velocity field around it.

Carbon cloth as an important electrode support for the high selective electrosorption of uranium from acidic uranium mine wastewater

An amidoxime modified carbon cloth electrode (CC-AO) was applied for uranium electrosorption at low pH value of 2. Experiments using other carbon-based electrodes were also carried out for comparison. The kinetics, isotherm, selectivity, reusability and power consumption during the uranyl ions (UO22+) electrosorption were studied in-depth. The effects of voltage and frequency on UO22+ selectivity among coexisting ions were investigated. The results showed that UO22+ (20 mg/L), removal by CC-AO was 94.3% at pH = 2 with a high electrosorption capacity of 989.5 mg/g (within 12.5 h). The electric field drove UO22+ to move to the cathode surface and produced UO3·2H2O on CC-AO. Under the optimal electric field (- 2.5 V, 800 Hz), CC-AO achieved the highest UO22+ selectivity in the simulated acidic uranium mine wastewater, and the frequency was the main factor. The CC-AO can be effectively used for seven UO22+ electrosorption-desorption cycles. Moreover, a new index of “unit power consumption for half amount uptake” (PC1/2) was proposed to quantify the power consumption during UO22+ uptake by different electrodes. In electrosorption system, the available area of CC-AO is larger than that of CF-AO, so its electrosorption efficiency for UO22+ is much higher than the latter. The current CC-AO showed clear advantages in terms of electrochemical features, adsorption capacity, selectivity, and power consumption at such low pH condition, indicating an application potential for uranium recovery from acidic uranium mine wastewaters.

Electric-permittivity-based instability of two dielectric miscible liquids under DC field.

This paper considers the mixing of two dielectric miscible viscous liquids with different electric permittivities bounded by solid walls in an external electric field normal to the interface of the liquids. The mutual diffusion of these two liquids leads to the formation of an unsteady self-similar 1D diffusion layer. This layer is found to be unstable to the perturbations of the interface. A special sophisticated mathematical approach in self-similar variables is developed to estimate its stability. The results of a linear stability theory are verified by direct numerical simulations of the full nonlinear problem. A mixing efficiency based on the separation amplitude and an optimal electric field strength to achieve the fastest mixing are proposed in the present study.

Determining the effects of LFHV-PEF treatment on the water distribution and vigor of aged rice seeds using LF-NMR

This study aimed to investigate the effect of low-frequency high-voltage pulsed electric field (LFHV-PEF) treatment on the germination of aged rice seeds. Aged rice seeds were subjected to LFHV-PEF treatment with different electric field strengths, and low-field nuclear magnetic resonance (LF-NMR) was performed to acquire the LF-NMR data of rice seeds at different germination periods during a standard seed germination test to analyze their internal patterns of water state and distribution. Optimal treatment conditions were determined based on the physicochemical data collected during germination, and the improvements in seed vigor were verified. The findings indicated that during germination, the contents of bound and semi-bound water within the aged rice seeds initially increased and then decreased, whereas free water and total water contents increased continuously and rapidly. Side peaks were also observed within the seeds. Under the LFHV-PEF treatment, the semi-bound water within the seeds was more easily converted to free water, and the water absorption rate, germination potential, germination rate, germination index, and vigor index of these seeds improved. Further, the optimal electrical field strength was 12 kV. By analyzing the internal patterns of water state and distribution in seeds, the mechanism by which electric field treatment improved seed vigor was elucidated, thus, providing theoretical support and data evidence for research on water absorption during the germination of rice seeds, and methods for improving seed vigor. Keywords: aged rice seeds, germination, water phase, seed vigor, LF-NMR, LFHV-PEF DOI: 10.25165/j.ijabe.20221504.7590 Citation: Cheng E S, Song P, Hou T G, Wu L Y, Zhang B H. Determining the effects of LFHV-PEF treatment on the water and vigor of aged rice seeds using LF-NMR. Int J Agric & Biol Eng, 2022; 15(4): 190–196.

Investigations on Breakdown Voltage of Trench-gate-type Super Barrier Rectifier with Stepped Oxide

A novel trench-gate-type super barrier rectifier (TSBR) with stepped oxide (SO-TSBR) is proposed and researched by device simulator. As an improved TSBR structure, the proposed SO-TSBR with high breakdown voltages be effective in achieving low forward voltage drop. Simulations have demonstrated the two-dimensional charge coupling in the N-drift region resulting in an optimal electric field distribution. The 280 V SO-TSBR used for the numerical simulations decreases the on-state drop by 26.6% at the forward current density of 2.5 A/cm2 than that of the conventional TSBR. The SO-TSBR with deep trench structure reduces further the forward voltage drop by 11.0% at the forward current density of 20 A/cm2.

Application of WOA–SVR in Seed Vigor of High-Voltage Electric Field Treatment on Aged Cotton (Gossypium spp.) Seeds

When seeds are treated with a high-voltage electric field (HVEF) to improve seed vigor, due to the large differences in the biological electromagnetic effects on different types of seeds, the methods of variance analysis and regression analysis based on data statistics are generally used to construct the optimal electric field dose prediction model; however, the generalization performance of the prediction model tends to be poor. To solve this problem, the electric intensity, frequency and treatment time were taken as the input variables for hybrid support vector regression (SVR) analysis to establish the prediction model of the seed comprehensive germination index. The whale optimization algorithm (WOA) was used to optimize the kernel parameters of the SVR. The optimized hybrid WOA–SVR model predicted the optimal comprehensive germination index of aged cotton (Gossypium spp.) seeds to be 329, the optimal HVEF dosage was 3.64 kV/cm × 99 s, and the frequency was 1.4 Hz. The aged cotton seeds were treated with the optimal HVEF and the germination test was carried out. Compared with the check (CK), the comprehensive germination index of seeds increased by 48%. The research results provided a new method and new idea for the optimal design of parameters for seed treatment with HVEF.

Ultra-high frequency and Self-adaptive voltage technology for water separation from oil emulsion

Electrical dehydrators are often used to separate water from oil emulsions. However, the frequency and electric field strength are fixed during separation and cannot change with the flow rate and emulsion properties. To solve this problem, ultra-high frequency and self-adaptive voltage transformer was developed to enhance the separation efficiency and compared with ordinary high frequency transformer. To this end, a small-scale evaluation test system was designed to investigate the influence of electric fields and operating parameters on water dehydration of different emulsions. The results showed there are different optimal electric field strengths for emulsions of various properties. Higher frequency values required lower electric field strengths. Under high frequencies, the formed water chains attracted surrounding small water droplets to form larger droplets. During the separation process, the frequency was kept stable but the electric field strength adaptively changed and gradually decreased, resulting in declined power consumption. Ordinary high-frequency electric fields illustrated low dehydration efficiencies on heavy oil emulsions, high-water concentration emulsions, and water-containing polymer emulsions. By comparison, ultra-high-frequency self-adaptive electric field strengths transformer showed superior separation efficiencies, low energy consumptions, and more stability. Besides, the separated water was cleaner and exhibiting superior adaptability to adverse conditions. In sum, these findings look promising for optimizing the operation of existing electrical dehydrators and promoting the use of ultra-high-frequency and self-adaptive electric fields.

Effects of high voltage electric field on storage life and antioxidant capacity of whole pomegranate fruit

The objective of this study was to investigate the effects of high voltage electric field (HVEF) on the antioxidant system in stored pomegranate fruit. The experiments were conducted at cold storage for two months under three selected electric field levels (0, 1.5 and 3 kV/cm). Results showed that non-enzymatic antioxidant contents including phenols and ascorbic acid were better preserved by 1.5 kV/cm treatment than control after 60 days of storage. While the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) in pomegranate fruit were significantly enhanced with 1.5 kV/cm treatment compared to control, Guaiacol peroxidase (G-POX) levels in the control group increased steadily and were highest at the end of the storage. Although the results obtained from 3 kV/cm treatment were acceptable till the end of the first month, due to oxidative damage of reactive oxygen species (ROS) produced in response to HVEF stress, their results come close to the control group at the end of the second month. These data suggest that the optimum electric field intensity for enhancing antioxidant contents in stored pomegranate fruits was 1.5 kV/cm.

Numerical simulation of dynamic characteristics of droplet in oil under a CPPM electric field

The size of droplets in oil are dynamically changes during demulsification, thereby changing the optimum demulsification electric field frequency. Thus, the constant pulsed electric field cannot meet the requirement of optimum frequency. The variable frequency pulsed electric field can cater to the change in optimum demulsification frequency, and has high demulsification ability. However, the dynamic characteristics of the droplet in oil at the variable frequency pulsed electric field are unclear. Therefore, a chaotic pulse position modulation (CPPM) electric field is considered a type of variable frequency pulsed electric field, where the pulse frequency is chaotic but pulse width and field intensity are constant. The droplet deformation dynamic model under the CPPM electric field is established by applying finite element method. The dynamic and chaotic characteristics of the droplet deformation in oil in this electric field are investigated, and the influence of pulse width and electric field intensity on droplet deformation is discussed. Results show that the deformation of droplet in oil is nonstationary vibration with the action of the CPPM electric field, and its deformation is chaotic vibration. The chaos of droplet deformation decreases with the increase in pulse width, and an optimum pulse width can be found to make the droplet have large deformation ratio and high vibration times. The deformation ratio of droplet can be increased by increasing the electric field intensity, but the droplet are easy to split and the deformation is no longer chaotic at high electric field intensity, and an optimum electric field intensity can be found to make the droplet have large deformation ratio and deformation stability.

314 mm2 Hexagonal Double-Sided Spiral Silicon Drift Detector for Soft X-Ray Detection Based on Ultra-Pure High Resistance Silicon

An X-ray pulsar is a remnant of massive star evolution, collapse, and supernova explosions. It has an extremely stable spin cycle and is known as the most accurate astronomical clock in the natural world. It presents high-precision navigational information, such as the location, speed, time, and attitude, which are used in deep space exploration and interstellar flight, such as the X-ray pulsar navigation (XPNAV). However, the energy of the X-ray from the pulsar is very low and its signal is very weak; this X-ray is known as the soft X-ray. In the low and medium energy radiation spectroscopy, the semiconductor detectors, especially the silicon drift detectors (SDD), achieve the best energy resolution. In this study, a 314 mm2 and a 600 mm2 double-sided spiral hexagonal silicon drift detector (DSSH-SDD) single cell for the pulsar soft X-ray detection is analyzed based on ultra-pure high-resistance silicon. The DSSH-SDD device is fabricated using ultra-pure high-resistivity silicon substrates patterned with ion-implanted electrodes. This study proposes a model capable of reaching a large area of 314 mm2 or 600 mm2 single cell and maintaining an optimal drift electric field. The design, modeling, 3D simulation, and the fabrication of the model are performed to analyze the physical performance of the DSSH-SDD. The electrical characteristics of the as-processed SDD chips, including leakage current, anode capacitance, and the spiral resistor current under the positive and negative biases are measured, and the energy resolution test is performed at the Tsinghua University. The energy resolution is an important indicator of the detector and is often expressed by full width at half maximum (FWHM). The results obtained in this study can be applied in the future for novel, flexible, large-area, high-resolution ionizing radiation detection systems capable of providing quantitative and real-time information of the relative position of spacecraft and pulsars through the pulsar X-ray radiation.

Inactivation of Escherichia coli using atmospheric pressure cold plasma jet with thin quartz tubes

In this study, the temporal evolution and electrical characteristics of atmospheric pressure cold plasma jet (APPJ) structures with different quartz tube wall thicknesses that used AC power were investigated via experimentation and simulation. The percentage increase of electron density based on the wall thickness was investigated. Based on the optimal electric field intensity distribution and flow field distribution, the quartz tube with the optimal wall thickness improved the electron density. We applied the optimized APPJ structures to inactivate E. coli. We demonstrated that the APPJ structures with thin-walled quartz tubes had better inactivation characteristics than those with thick-walled structures regardless of the duration of treatment. The electron density properties of APPJ structures with different quartz tube wall thicknesses have a prominent impact on the improvement in the killing rate in the sterilization processes.

Electroporation of suspension cell lines – A proposed assay set for optimizations

To make in vitro single cell electroporation protocols more comparable between various cancer types and groups, we propose a set of assays to test a range of electric field strengths at the start of any new project to determine the optimal electric field strength for a given cell line. While testing a range of electric field strengths, we kept the other ESOPE parameters constant (8 pulses, 100 µs pulse duration, 1 Hz pulse frequency). Basic assays were employed to measure short-term viability, effectiveness of treatment, metabolic activity, and recovery potential post-treatment to determine the optimal field strength for a particular cell line. Six cancer cell lines were tested, three of human (A549, A375 and Pan02) and three murine (LLC, B16F10 and MIA-PACA2). Our findings demonstrate that the optimal electroporation setting while keeping with all other ESOPE parameters are 800 V/cm for A549 and Pan02, 700 V/cm for A375, Mia-PACA2, and B16F10, and 1300 V/cm for LLC. Having an agreed upon set of assays to determine each cell lines optimal electric field strength should allow an improve translation of findings between cell lines for in vitro work from various groups and potentially improve translation into the clinic.

BiPO4 Nanorod/Graphene Composite Heterojunctions for Photocatalytic Degradation of Tetracycline Hydrochloride

Precisely manipulating the built-in electric fields of heterojunctions is an effective way to promote photogenerated charge separation. In this work, BiPO4 nanorods/graphene (GA) hydrogels were prepared by hydrothermal methods. The BiPO4 nanorods were evenly embedded in the graphene hydrogel, forming a stable three-dimensional (3D) network structure. The 70% BiPO4/GA hydrogel shows the highest tetracycline hydrochloride degradation activity, which is 3.2 times that of pure BiPO4. The formation of the built-in electric field of the BiPO4/GA hydrogel is demonstrated by experimental investigation (especially in situ atomic force microscopy (AFM) surface potential investigation) and theoretical calculation. The reasons for the enhanced photocatalytic activity are the optimal built-in electric field of the interface induced by precisely manipulating the interfacial contact of the BiPO4/GA hydrogel, as well as the synergistic effect of in situ photocatalytic degradation and adsorption enrichment induced by the 3D network structure. This work provides technical approach and research ideas for the photocatalytic degradation of antibiotics through the manipulation of interlaminar built-in electric field and heterojunction.

Electric Field Distribution Analysis of Blood Cancer as a Potential Blood Cancer Therapy

Blood cancer causes a significant increase in the concentration of Leukocytes, which can be broken down through dielectrophoresis and electrochemical procedures. Therefore, the electric field plays an important role in the migration of leukocytes to high voltage areas. This is because different electrode arrangements produce varying electric field distributions. Furthermore, this study applied finite element methods to generate electric fields when electrodes with an AC voltage were applied to blood placed in a chamber. Therefore, in this study, variations of mediums and electrode arrangements were investigated, which led to the recommendation of 3 models. The objective was to investigate electrode arrangements that produce optimal electric field distribution for the three models to exhibit a booster of electric field distribution. The maximum electric field is generated close to the electrode (Z=2 mm and Z=92 mm) for any material (i.e. normal blood, B lymphocyte, and T lymphocyte) with values of 22.6 V/m and 23.47 V/m, 22.85 V/m and 22.97 V/m, and 24.88 V/m and 25.01 V/m. Based on principle, lymphocytes in the blood result in positive dielectrophoresis, since they migrate to a higher electric field close to the electrode, with enough input voltage to turn the electrochemical process on the leukocytes into electric current. Furthermore, this study provides new perspectives and ideas, which have not been revealed in previous studies on blood cancer therapy using the electric field of Ag electrode in blood cancer distribution.Keywords: blood cancer, dielectrophoresis, electric field, voltage, electrochemical, and cancer therapy.

P-248 Determination of the optimal electrical field for apoptosis in the rat stomach during irreversible electroporation

Irreversible electroporation (IRE) is a tissue ablation technique inducing apoptosis. However, the most efficient electrical field strength for IRE has not been determined. We aimed to investigate the optimal electrical field strength for IRE to promote gastric tissue apoptosis and to identify the post-IRE tissue recovery.