High Electric Pulses Research Articles

Effect of high energy electric pulse on microstructure and mechanical properties of pre-deformed SUS 304 ultra-thin strip

To improve the mechanical properties of the pre-deformed SUS 304 ultra-thin strip by regulating its microstructure, the paper uses high energy pulsed current to treat the pre-deformed SUS 304 ultra-thin strip. Uniaxial tensile samples with different pre-deformation (10%, 30%, 50%) are prepared by tensile testing machine and used to study the changes in microstructure and mechanical properties of the pre-deformed samples before and after the electric pulse treatment. The results show that the electric pulse treatment results in a complete recovery of plasticity and a 10% increase in elongation at break for the 10% pre-deformed sample, and leads to a 6.8% decrease in yield strength, a 13.2% increase in tensile strength and a 34.4% increase in elongation at break for the 50% pre-deformed sample. The electric pulse treatment causes recovery and static recrystallization of pre-deformed samples at lower temperatures, and some annealing twins are formed within the recrystallized grains. The electric pulse treatment reduces the dislocation density, refines the deformed grains, alleviates the {111} silk texture generated during pre-tensile deformation, and improves the anisotropy. It can be seen that the electric pulse treatment can significantly improve the mechanical properties of pre-deformed samples and promote the plastic deformation capacity of the SUS 304 ultra-thin strip.

Pulsed electric field technology in food preservation: As an active competitor of thermal treatments

Pulsed electric field technology is a novel non-thermal technology in food preservation to improve the quality and shelf life of the food product. There are many thermal and non-thermal technologies for food preservation like traditional methods including freezing, refrigeration, blanching and non-thermal technologies like pulsed electric field technology, ultrasound technique, irradiation, high pressure processing etc. Among this pulsed electric field technology advantageous compared to others. It is claimed as superior to any other techniques of food preservation because it reduces the detrimental changes in food quality and keeps the physical and sensorial attributes of food. And this technique can be used mostly in the case of liquid foods and semi-solid foods. In this technique, high electric pulses should be applied through the electrodes to the food which is kept between the electrodes in the treatment chamber. And the external electric field leads to breakdown of the cell membrane of microorganisms by the process called electroporation. In this review, importance of pulsed electric field technology, its major components, microbial inactivation process, and the factors responsible for inactivation, major applications of PEF, etc. are discussed.

A Liquid Stratification Model to Predict Failure in Thermally Damaged EBW Detonators

AbstractIn previous work, commercially available downward facing exploding bridgewire detonators (EBWs) were exposed to elevated temperatures. These detonators were then initiated using a firing set which discharged a high amplitude short duration electrical pulse into a thin gold bridgewire. Responses of the detonators were measured using photonic doppler velocimetry (PDV) and high‐speed photography. A time delay of 2 μs between EBW initiation and first movement of an output flyer separated operable detonators from inoperable detonators or duds. In the current work, we propose a simple method to determine detonator operability from the calculated state of the detonator at the time the firing set is initiated. The failure criterion is based on the gap distance between the exploding bridgewire (EBW) and the adjacent initiating explosive within the detonator which is low‐density pentaerythritol tetranitrate (PETN) that melts between 413–415 K (140–142 °C). The gap forms as PETN melts and flows to the bottom of the input pellet. Melting of PETN is modeled thermodynamically as an energy sink using a normal distribution spread over a temperature range between the onset temperature of 413 K and the ending temperature of 415 K. The extent of the melt is determined from the average temperature of the PETN. The PETN liquid is assumed to occupy the interstitial gas volume in the lower part of the input pellet. The vacated volume from the relocated liquid forms the gap between the EBW and the PETN. The remaining sandwiched layer consists of solid PETN particles and gas filling interstitial volume. We predict that a threshold gap between 17–27 μm separates properly functioning detonators from duds.

Evaluation of electroporated area using 2,3,5-triphenyltetrazolium chloride in a potato model

Irreversible electroporation (IRE) is a tissue ablation method, uses short high electric pulses and results in cell death in target tissue by irreversibly permeabilizing the cell membrane. Potato is commonly used as a tissue model for electroporation experiments. The blackened area that forms 12 h after electric pulsing is regarded as an IRE-ablated area caused by melanin accumulation. Here, the 2,3,5-triphenyltetrazolium chloride (TTC) was used as a dye to assess the IRE-ablated area 3 h after potato model ablation. Comparison between the blackened area and TTC-unstained white area in various voltage conditions showed that TTC staining well delineated the IRE-ablated area. Moreover, whether the ablated area was consistent over time and at different staining times was investigated. In addition, the presumed reversible electroporation (RE) area was formed surrounding the IRE-ablated area. Overall, TTC staining can provide a more rapid and accurate electroporated area evaluation.

Synthesis of Fe/Fe3O4 core-shell nanoparticles by electrical explosion of the iron wire in an oxygen-containing atmosphere

Magnetic nanoparticles based on iron and its oxides are promising in various biomedical applications. Currently, as a rule, ferromagnetic iron oxide particles with a low specific magnetic moment are used for medical purposes. In the present work, a new method for the synthesis of magnetic nanoparticles based on the electric explosion of a Fe wire is proposed. When wires are dispersed by high current electric pulse in an inert atmosphere containing less than 5% oxygen, nanoparticles with a core-shell structure are formed, where the core is α-Fe and the shell is formed by a mixture of oxides Fe3O4 and FeO. The oxygen concentration in the buffer gas has been found to determine the size of the resulting nanoparticles, their shape, and iron content. The iron oxide shell protects the iron core from the external environment, preventing the rapid dissolution of Fe containing in the nanoparticles, in contrast to nanoparticles obtained in argon atmosphere. The specific magnetic moment of nanoparticles, depending on the content of iron oxides, varies from 90 to 180 emu/g.

Pulsed Electric Field Treatment of Sugar Beet

The effect of high electric filed pulses on sugar extraction from sugar beet strip during continuous pilot scale extraction was investigated. The results have shown that sugar beet strip could be extracted at moderate temperature (35-50°C) using PEF pre-treatment. The sugar extraction yield of PEF pre-treated samples was about 98.5 to 99.8 % (for extraction times of 30 an 70 min at 50 °C respectively). In contrast, the sugar extraction yield for untreated samples was distinct lower (92.5 % at 50 °C, 30 min and 94 % at 50 °C and 70 min extraction time. In additions, the pressing of PEF pre-treated extracted pulp was more effective than thermal extracted (at 70 °C) sample. Furthermore, the drying of PEF pre-treated extracted pulp was faster than drying of pulp from thermal extracted sample. The results of this study confirmed that the PEF technique is an energy and time saving method for continuous sugar beet processing.

Perovskite neural trees

Trees are used by animals, humans and machines to classify information and make decisions. Natural tree structures displayed by synapses of the brain involves potentiation and depression capable of branching and is essential for survival and learning. Demonstration of such features in synthetic matter is challenging due to the need to host a complex energy landscape capable of learning, memory and electrical interrogation. We report experimental realization of tree-like conductance states at room temperature in strongly correlated perovskite nickelates by modulating proton distribution under high speed electric pulses. This demonstration represents physical realization of ultrametric trees, a concept from number theory applied to the study of spin glasses in physics that inspired early neural network theory dating almost forty years ago. We apply the tree-like memory features in spiking neural networks to demonstrate high fidelity object recognition, and in future can open new directions for neuromorphic computing and artificial intelligence.

Rapid and Effective Electroporation Protocol for Nannochloropsis oceanica.

Electroporation refers to the application of high strength electric pulse to create transient pores in the membrane, thereby enabling the passage of hydrophilic molecules into the cells. Based on the properties of cell and cell wall, the electroporation parameters vary among the algal species. Here, we demonstrated the optimized protocol for successful introduction of recombinant DNA (~5000bp) into Nannochloropsis oceanica. The linearized recombinant plasmid that harbors eGFP and Bh-sle as the reporter and marker gene, respectively, was electroporated into the electrocompetent N. oceanica cells at voltage of 2200V, 50μF, resistance at 600Ω using electroporator, and the transformed cells were then screened by molecular analysis. The report exemplifies a straightforward and reliable electroporation strategy for generating transgenic N. oceanica cells.

Response of an actin network in vesicles under electric pulses

We study the role of a biomimetic actin network during the application of electric pulses that induce electroporation or electropermeabilization, using giant unilamellar vesicles (GUVs) as a model system. The actin cortex, a subjacently attached interconnected network of actin filaments, regulates the shape and mechanical properties of the plasma membrane of mammalian cells, and is a major factor influencing the mechanical response of the cell to external physical cues. We demonstrate that the presence of an actin shell inhibits the formation of macropores in the electroporated GUVs. Additionally, experiments on the uptake of dye molecules after electroporation show that the actin network slows down the resealing process of the permeabilized membrane. We further analyze the stability of the actin network inside the GUVs exposed to high electric pulses. We find disruption of the actin layer that is likely due to the electrophoretic forces acting on the actin filaments during the permeabilization of the GUVs. Our findings on the GUVs containing a biomimetic network provide a step towards understanding the discrepancies between the electroporation mechanism of a living cell and its simplified model of the empty GUV.

Dual-Functional Long-Term Plasticity Emulated in IGZO-Based Photoelectric Neuromorphic Transistors

Indium–gallium–zinc-oxide (IGZO) photoelectric neuromorphic transistors with low-temperature atomic layer deposited Al2O3 gate dielectrics are fabricated. Dual-functional long-term plasticity, including long-term depression (LTD) and long-term potentiation (LTP), is emulated. The emulation of LTD is achieved by applying high-electrical pulse trains on the gate electrode. The LTP emulation is realized by applying light pulse trains on the IGZO channel layer. The operation mechanisms of the LTD and the LTP are discussed based on the electron/hole trapping in the Al2O3 gate dielectrics and the persistent photoconductivity of the IGZO channel layer.

Rapid deformation of IPMC under a high electrical pulse stimulus inspired by action potential

Slow deformation seriously restrains application development of IPMC actuator, especially for thick and ionic liquid-based IPMC. Inspired by the action potential of muscle cell, this letter proposes a concept of high electrical pulse stimulus to accelerate IPMC deformation. By analyzing the dynamic process of voltage drop at the electrode-polymer interface, high voltage pulse is proved theoretically to be safe for IPMC in a short time. After charging the electrical double layer at the interface, the voltage pulse should be reduced to a safe level before electrochemical reactions. In our experiments, applying various high voltage pulses to a thick IPMC, the deformation can be sped up a few hundred times at most without any electrolysis damage. The results strongly support the practicability of the impulsive driving method.

Mechanical Analysis of Cells via Electrodeformation-Relaxation

An electrodeformation-relaxation technique is developed to characterize mechanical properties of cells in suspension. The experimental platform was established using an indium-tin-oxide (ITO) coated glass slide and parallel electrodes were lithographically defined by etching ITO. Various types of cells in suspension, including MCF-10A, MCF-7, MDA-MB-231, and GBM were exposed to high frequency and amplitude electric pulses. The pulsing protocol ensures the occurrence of deformation and the absence of electroporation. Owing to the design of the electrodeformation chip, cells were trapped at the edge of the electrodes under dielectrophoretic forcing. The subsequent deformation and relaxation (upon pulse cessation) were captured via synchronized high-speed camera. Images were analyzed and the shape factor (ratio between long and short axes) was extracted as a function of time. In the relaxation process, two distinctive regimes, dilational and constant-tension, were observed. Data were analyzed with a mathematical theory that we developed previously, which provides a closed-form solution for ellipsoidal deformation-relaxation. The properties of the various cell types were analyzed and extracted using this model. The technique promises ease of implementation and high-throughput for large-scale cell mechanical analysis.

Localized Electroporation With Dielectrophoretic Field Flow Fractionation: Toward Removal of Circulating Tumour Cells From Human Blood.

This paper presents the design and experimental performance of a microelectrode-based device to selectively lyse cells in a flow in a microfluidic channel. Localized cell lysis is achieved by utilizing "irreversible electroporation," in which cells are exposed to high magnitude electric pulses. Localized cell lysis in a flow has research applications and may allow for the removal of harmful cells, such as circulating tumor cells from blood. Due to the dependence of this technique on the magnitude of the applied electric field, lethal electric field regions can be localized in the channel by the calibration of the applied voltage. Dielectrophoresis field flow fractionation is used to levitate target cancer cells in the lethal region of the device microchannel. Experiments are performed to demonstrate the localized lysis of MCF7 cancer cells in a mixture of blood cells. Due to their larger size, these circulating tumor cell analogues levitate to a greater height in the channel than erythrocytes. MCF7 lysis is observed to increase from 4.6% in control experiments to 57.3% in active experiments. Leukocyte viability was unaffected in active experiments. These results demonstrate the feasibility of localizing cell lysis in a microfluidic flow environment.

Enhancing Efficiency of Silicon Photovoltaic Cells Using High Frequency Electric Pulses

Enhancing Efficiency of Silicon Photovoltaic Cells Using High Frequency Electric Pulses

Defect dipole induced large recoverable strain and high energy-storage density in lead-free Na0.5Bi0.5TiO3-based systems

In this letter, we propose an effective route to obtain large recoverable strain, purely electrostrictive effects and high energy-storage density by inducing defect dipoles into Na0.5Bi0.5TiO3 (NBT)-based relaxor ferroelectrics. It has been found that pinched and double polarization hysteresis loops with high maximum polarization (Pmax) and negligible remanent polarization (Pr) can be observed due to the presence of acceptor-induced defect dipoles. A large recoverable strain of 0.24% with very little hysteresis and high electrostriction coefficient of 0.022 m4 C2 with purely electrostrictive characteristics were acquired when 11 mol. ‰ Mn-doped. Meanwhile, a high recoverable energy density of 1.06 J/cm3 with excellent temperature stability was obtained at the same composition owing to the enlarged value of Pmax-Pr (36.8 μC/cm2) and relatively high electric field (95 kV/cm). Our achievement can open up the exciting opportunities for ferroelectric materials in high-precision positioning devices and high electric power pulse energy storage applications.

Interaural time difference sensitivity with high rate electrical pulse trains in bilateral cochlear implant users

Interaural time differences (ITDs) are an important cue for obtaining binaural hearing benefits. Bilateral cochlear implant (BiCI) users have shown poor ITD sensitivity when using clinical processors, but have some ITD sensitivity with carefully controlled stimuli presented using synchronized research processors. In BiCI users, low stimulation rates yield best ITD sensitivity, but declines as the stimulation rate increases. However, high rates are typically needed for good speech understanding, which poses a conundrum for maximizing the benefit of BiCIs. Aperiodic high-rate stimulation has been shown to promote ITD sensitivity. However, it is uncertain whether this improvement is due to changes in the loudness level, which may provide an envelope ITD cue. In this study, we tested this hypothesis by measuring ITD just noticeable differences (JNDs) with 4000-Hz electrical pulse trains. Pulse trains either had: (1) constant amplitude and rate; (2) aperiodic timing in the pulses; and (3) aperiodic timing + a random amplitude applied to each pulse. Results have implications in determining whether aperiodic high-rate stimulation can be useful for restoring ITD sensitivity. [Work supported by NIH-NIDCD (R01DC003083 to Ruth Litovsky) and NIH-NICHD (P30HD03352 to the Waisman Center).]

High speed and multi-level resistive switching capability of Ta2O5 thin films for nonvolatile memory application

Bipolar resistive switching performance has been demonstrated in the sandwiched Pt/Ta2O5/TiN structures, including uniform set and reset voltages distributions, good endurance, long retention, and high operation speed. In addition, multi-level storage capability has been achieved through controlling different reset stop voltages and different compliance currents in direct current voltage sweeping modes and by means of different pulse erasing voltages in pulse programming/erasing modes. High speed electrical pulse induced multi-level storage capability shows good endurance and long retention of the four level resistance states. On the basis of the conducting filament model, the multi-level switching capability has been explained. This study suggests that the Pt/Ta2O5/TiN devices have potential application in nonvolatile high speed and multi-level resistive switching memory.

Electrotransfer parameters as a tool for controlled and targeted gene expression in skin

Skin is an attractive target for gene electrotransfer. It consists of different cell types that can be transfected, leading to various responses to gene electrotransfer. We demonstrate that these responses could be controlled by selecting the appropriate electrotransfer parameters. Specifically, the application of low or high electric pulses, applied by multi-electrode array, provided the possibility to control the depth of the transfection in the skin, the duration and the level of gene expression, as well as the local or systemic distribution of the transgene. The influence of electric pulse type was first studied using a plasmid encoding a reporter gene (DsRed). Then, plasmids encoding therapeutic genes (IL-12, shRNA against endoglin, shRNA against melanoma cell adhesion molecule) were used, and their effects on wound healing and cutaneous B16F10 melanoma tumors were investigated. The high-voltage pulses resulted in gene expression that was restricted to superficial skin layers and induced a local response. In contrast, the low-voltage electric pulses promoted transfection into the deeper skin layers, resulting in prolonged gene expression and higher transgene production, possibly with systemic distribution. Therefore, in the translation into the clinics, it will be of the utmost importance to adjust the electrotransfer parameters for different therapeutic approaches and specific mode of action of the therapeutic gene.

Skin Electroporation of a Plasmid Encoding hCAP-18/LL-37 Host Defense Peptide Promotes Wound Healing

Host defense peptides, in particular LL-37, are emerging as potential therapeutics for promoting wound healing and inhibiting bacterial growth. However, effective delivery of the LL-37 peptide remains limiting. We hypothesized that skin-targeted electroporation of a plasmid encoding hCAP-18/LL-37 would promote the healing of wounds. The plasmid was efficiently delivered to full-thickness skin wounds by electroporation and it induced expression of LL-37 in the epithelium. It significantly accelerated reepithelialization of nondiabetic and diabetic wounds and caused a significant VEGFa and interleukin (IL)-6 induction. IL-6 was involved in LL-37-mediated keratinocyte migration in vitro and IL-6 neutralizing antibodies delivered to mice were able to suppress the wound healing activity of the hCAP-18/LL-37 plasmid. In a hindlimb ischemia model, electroporation of the hCAP-18/LL-37 plasmid increased blood perfusion, reduced muscular atrophy, and upregulated the angiogenic chemokines VEGFa and SDF-1a, and their receptors VEGF-R and CXCR-4. These findings demonstrate that a localized gene therapy with LL-37 is a promising approach for the treatment of wounds.

Energy storage properties of (1 − x)(Bi0.5Na0.5)TiO3–xKNbO3 lead-free ceramics

In this study, a simple compound (1 − x)(Bi0.5Na0.5)TiO3–xKNbO3 (x = 0 – 0.12) lead-free bulk ceramic was developed for high electric power pulse energy storage applications. The dielectric and ferroelectric properties of the ceramics were measured. The results illustrate that the energy storage density of the ceramics is enhanced by the addition of KNbO3. The influence of applied electric field, temperature, and fatigue on the energy storage properties of the ceramics was evaluated for the composition-optimized (Bi0.5Na0.5)TiO3–0.1KNbO3 ceramic. The results demonstrate that (Bi0.5Na0.5)TiO3–0.1KNbO3 ceramic is a promising lead-free material for high power pulse capacitor applications. The excellent energy storage properties of the (Bi0.5Na0.5)TiO3–0.1KNbO3 ceramics are ascribed to the reversible relaxor–ferroelectric phase transition induced by the electric field.