Bipolar Pulse Research Articles

A molecular dynamics study of phospholipid membrane electroporation induced by bipolar pulses with different intervals.

The mechanism of changes in cell electroporation (EP) during the intervals of bipolar pulses is still unclear, and few studies have investigated the effect of the intervals at the molecular level. In this study, EP induced by bipolar pulses (BP) with different intervals was investigated using all-atom molecular dynamics simulations. Firstly, EP was formed during the positive pulses of 2 ns and 0.5 V nm-1, then the effects of various intervals of 0, 1, 5, and 10 ns on EP evolution were investigated, and the dynamic changes of different degrees of EP induced by the following negative pulses of 2 ns and 0.5 V nm-1 were analyzed. The elimination effect of intervals was determined and it was related to the degrees of EP and the time of intervals. At the last moment of the intervals the phospholipid membrane was classified and quantitatively defined in three states according to the degrees of EP, namely, Resealing, Destabilizing and Retaining states. These states appeared due to the combined effect of both the positive pulse and the interval, and the states represent the degrees of EP which had different responses after applying the negative pulse. These results can improve our understanding of the fundamental mechanism of BP-induced EP.

Peculiarities of Excitation of a Particle in a Single-Level Quantum Well by an Extremely Short Attosecond Pulse

Using the solution of the time-dependent Schrodinger equation, the features of the excitation of a bound state of a particle in a one-dimensional rectangular quantum well of small depth by an extremely short light pulse are studied. The case of a shallow well with only one energy level is considered. In this case, the system is excited by an attosecond pulse whose duration is shorter than the characteristic time associated with the energy of the bound state of the particle in the well. It is shown that in this case the population of the bound state and the ionization probability are determined by the ratio of the electric area of the pulse to its atomic scale, which is inversely proportional to the well width. The calculation results showed that unipolar subcycle pulses with nonzero electric area can excite the system faster and more efficiently than bipolar pulses with zero area. The possibility of using unipolar gamma-ray pulses of zeptosecond duration for deuteron excitation is discussed, and numerical estimates of the required duration and electric area of the pulse are given. Keywords: extremely short pulses attosecond pulses, unipolar pulses, electric area of a pulse, atomic scale of electric area, one-dimensional quantum wells, nanostructures.

Особенности возбуждения частицы в одноуровневой квантовой яме предельно коротким аттосекундным импульсом

Using the solution of the time Schrödinger equation, the features of the excitation of a bound state of a particle in a one-dimensional rectangular quantum well of small depth by an extremely short light pulse are studied. The case of a shallow well with only one energy level is considered. In this case, the system is excited by an attosecond pulse whose duration is shorter than the characteristic time associated with the energy of the bound state of the particle in the well. It is shown that in this case the population of the bound state and the ionization probability are determined by the ratio of the electric area of the pulse to its atomic measure, which is inversely proportional to the well width. The calculation results showed that unipolar subcycle pulses with nonzero electric area can excite the system faster and more efficiently than bipolar pulses with zero area. The possibility of using unipolar gamma-ray pulses of zeptosecond duration for deuteron excitation is discussed, and numerical estimates of the required duration and electric area of the pulse are given.

Development of sensitive measuring circuits for measurement of physicochemical parameters and their metrological characteristics

A sensitive measuring scheme has been developed for capacitive-semiconductor converters of humidity of dispersed media, and basic static characteristics have been obtained depending on the duration of bipolar pulses, providing an increase in accuracy and linearity of the static characteristics. A scientifically based increase in the reliability of the results of chemical analysis and physicochemical measurements, the identification and minimization of their errors are impossible without the use of the foundations of metrology - the science of measurements. At the same time, theoretical metrology is rather closely intertwined with the legislative - a set of state acts and regulatory documents that regulate the rules, requirements and norms that must be guided by when making measurements. Obviously, the more responsible the decision is made on the basis of the measurement results, the more stringent the requirements are imposed on them, the less the measurement results should depend on the subjective opinion of the experimenter. Main provisions of measurement error assessment and principles of uniformity of measurements required for rational performance of physical and chemical measurements and chemical analysis are presented. Regularities of normal and other most common types of random v.e. distribution are considered.

The use of the combined anesthesia method using local anesthesia and percutaneous electroneurostimulation for dental implantation

The purpose of the work: to conduct a comparative assessment of the adequacy of pain relief based on the study of the dynamics of pain indicators, the autonomic nervous system and the psycho-emotional status of patients with a combination of local anesthesia and percutaneous electroneurostimulation.
 Materials and methods. 40 patients aged 38 to 63 years took part in the study. The number of patients in the first group amounted to 20 people aged 38 to 63 years, and they all completed the study. In the first group, only local anesthesia (MA) was used by a 4% solution of articaine with epinephrine in a concentration of 1: 200000. In the second group, the number of patients was 20 people aged 38 to 60 years, and all of them also completed the study. In the second group — a combination of percutaneous electroneurostimulation (Chens) with subsequent local anesthesia (Chens+Ma); Electroneurostimulation was carried out using the EPB50-01 Electronics device (Russia), which generates bipolar asymmetric current pulses of 20 s and a frequency of 10 imp/s. The intensity of electroneurostimulation was selected individually until the patient achieve intense non -pain sensations.
 Results. The use of percutaneous electroneurostimulation potentiates the analgesic effect of local anesthesia in the intraoperative period and has a prolonged analgesic effect, which manifests itself in a decrease in the intensity of pain throughout the postoperative period. Analysis of the features of the action of percutaneous electroneurostimulation indicates that this effect is due to exacerbation of not pain sensitivity, but by sensitization (exacerbation of sensitivity) of non -column peripheral nerves and oral trigeminal core, transmitting signals from receptors that are excited with no damaging effects (touches, displacement of tissues). This sensitization can develop as a result of prolonged preliminary electroneurostimulation, which was carried out before the injection. Against the background of sensitization of sensation from any mechanical effects on the tissue, more acute will be perceived, which was evaluated by patients as more intense pain. This feature of the action of percutaneous electroneurostimulation must be taken into account when compiling methods of its application in clinical practice.
 Conclusion. The use of percutaneous electroneurostimulation creates favorable conditions for the period of adaptation and integration of implants in the early stages of the postoperative period.

Effect of ion control strategies on the deposition rate and properties of copper films in bipolar pulse high power impulse magnetron sputtering

Effect of ion control strategies on the deposition rate and properties of copper films in bipolar pulse high power impulse magnetron sputtering

Response of Human Malignant Glioma Cells to Asymmetric Bipolar Electrical Impulses

Electric and electromagnetic pulses have been shown to enhance the endocytosis rate, with all-or-nothing responses beyond a field strength threshold and linear responses as a function of field strength and treatment duration utilizing bipolar symmetrical and monopolar pulses, respectively. Malignant glioma (MG) is resistant to chemotherapy. The present study looked for a new electrical impulse that can aid electrochemotherapy to deliver anticancer drugs while using less electrical energy. Bipolar asymmetric electric pulses were applied to U251MG cells suspended in physiologically conductive media in the presence of molecular probes, including Bleomycin. The delivered electric pulses with a pulse duration range of 180-500 µs and a frequency range of 100-400 Hz had a low field intensity ranging from 1.5 V/cm to 7.3 V/cm. Spectrophotometric and spectrofluorometric measurements were used to investigate the impact of these variables on cancer cell survival and the molecular probe uptake induced by the electric pulses. An all-or-nothing response was observed above a specified threshold of electric field intensity of 4 V/cm. This threshold was unaffected by changes in repetition frequency or pulse duration. It was not a temperature effect that caused the molecular probe uptake to increase. When bipolar asymmetric electric pulses were applied just before electroporation, the effectiveness of the cytotoxic impact of bleomycin was increased from 80%, when employing electroporation pulses alone, to 100%.

Characterization of the initial stage in upward lightning at the Gaisberg Tower: 2. Electric field signatures

• Near and far electric field signatures of IS current pulses were analyzed. • Electric field signatures of early-stage-IS bipolar current pulses were characterized. • Such bipolar pulses could be associated with upward leader inception. We examined the characteristics of electric field signatures occurring during the initial stage of 58 flashes measured simultaneously at near (170 m) and far (79 or 109 km) distances from the Gaisberg Tower located near Salzburg, Austria. Of the 340 field signatures measured at the near station, 68 (20%) were associated with current pulses occurring during the initiation and propagation phase (IPP) of the upward leader, and 272 (80%) were associated with pulses that occurred during the mature phase (MP) of the upward leader. Of the 68 field signatures of IPP pulses, 40 were associated with bipolar (IPP-B type) current pulses and 28 were associated with unipolar (IPP-U type) current pulses. Field signatures of IPP-B pulses were only detected at the near measurement station and appear to be associated with currents in relatively short (meter-scale) channel segments formed during the upward leader inception. At the far stations, field signatures of 84 IS pulses were recorded and analyzed. There was modest correlation between the background-to-peak current of IS pulses and near and far electric radiation field changes as well as between radiation field changes recorded at near and far distances.

Arrays of combined antennas with equal-amplitude distribution of bipolar voltage pulses

The paper presents the comparative characteristics of the radiation pattern of the combined antenna arrays excited by a bipolar pulse and harmonic oscillations near the central frequency of the spectrum of ultrawideband radiation. Particular attention is paid to the 3x3 array radiation source with maximum efficiency.

Characterization of the initial stage in upward lightning at the Gaisberg Tower: 1. Current pulses

• Upward-flash IS current is comprised of slowly varying and impulsive components. • 60% of IS current pulses were bipolar and 40% were unipolar. • Bipolar current pulses only occurred at early times (within first 15% of IS duration). We examined current waveforms for 58 upward flashes occurring in 2006–2014 initiated from the Gaisberg Tower located near Salzburg, Austria. The initial stage (IS) of these flashes comprised of relatively slowly varying “background” current, with faster, more impulsive current variations overlaid on this background current. In 46 of the 58 flashes (79%) the background continuing current was negative, and in the other 12 flashes (21%) it was bipolar. 1180 current pulses occurred during the IS of these 58 flashes, of which 708 (60%) were positive bipolar (positive initial polarity with a negative opposite polarity overshoot), 28 (2.4%) were positive unipolar (positive initial polarity with no opposite polarity overshoot), 440 (37%) were negative unipolar, and four (0.3%) were negative bipolar pulses. We found that bipolar current pulses only occurred in the IS at early times. We divided the IS current into two phases: (1) upward leader initiation and propagation phase (IPP) and (2) upward leader mature phase (MP). 901 or 76% (712 bipolar and 189 unipolar) pulses occurred during the IPP, and 279 or 21% (unipolar) pulses occurred during the MP. The median background-to-peak current was 134 A for IPP pulses and 687 A for MP pulses.

Bipolar Waveform Synthesis With an Optically Driven Josephson Arbitrary Waveform Synthesizer

An array of Josephson junctions (JJs) was driven with photonically generated current pulses to synthesize a high-fidelity 1 kHz bipolar voltage waveform with a quantum-based amplitude that can be directly related to fundamental constants. A photodiode capable of producing high average photocurrent was used to generate large-amplitude current pulses that were ac-coupled to a JJ array. The resulting bipolar current pulses have enabled the first demonstration of quantum-based bipolar waveform synthesis with an optical drive. We measured the quantum locking range with respect to several operating parameters, including 1.2 mA with respect to a dc bias current applied to the array, confirming the robust synthesis of bipolar waveforms.

PEMF Device With Bipolar Pulse Waves Based on Single Chip Computer

PEMF therapy, a non-invasive technology, is frequently reported in medical journals. It can send electric and magnetic fields to the body through induction coils [1,2], so as to provoke cells to stimulate nerves and muscles. Based on performances of large PEMF equipment on the market, on average, the low frequency emitted by most PEMF equipment is 0-300HZ An appropriate single chip is selected to make an extremely low frequency 0-30HZ that can be easily developed and easily changed. And has bipolar pulse wave so that simple equipment can also get enough effect.

Characterization of Preliminary Breakdown Pulse Trains in Negative Cloud-To-Ground Flashes Recorded during A Rainy Season in The Bogota Savannah, Colombia

Lightning-generated electric field measurement is used to characterize cloud-to-ground (CG) flashes. Prior to the first return stroke (FRS), these signals sometimes exhibit a pulse train, known as preliminary breakdown pulses (PBP), whose study provides information about the first event that originate the breakdown process inside the cloud. Considering that characteristics of PBPs may change according to geographical conditions, in this work, six parameters (temporal and magnitude) associated with 69 trains identified in negative CG flashes that occurred in the Bogota savannah, Colombia were analyzed. The signatures were recorded in 2017 using a fast response antenna (10 MHz bandwidth), a 100 ns sampling time and a window of 500 ms. Among the most relevant results, it was found that the train duration ( ) varied from 0.5 ms up to 5.2 ms with arithmetic mean (AM) of 1.74 ms, while the time interval between the peak of the train and the FRS (PBP-FRS) had an AM and a geometric mean (GM) of 35.7 ms and 10.2 ms, respectively. On the other hand, the ratio between the peak value of the PBP and its FRS ( ) exhibited an AM of 0.7 and a GM of 0.56. It was concluded that PBP train starts with low amplitude pulses, later increases its magnitude in the central region and decreases at the end. Furthermore, bipolar pulses with similar polarity to that of the FRS were identified at the beginning and in the middle of the train, while unipolar pulses were observed at the end of the signatures.

Ultra-microhistological study of nonthermal irreversible electroporation on the esophagus

Esophageal ulceration and even fistula are severe complications of pulmonary vein isolation using traditional thermal ablation. Nonthermal irreversible electroporation (NTIRE) is a new technique for pulmonary vein isolation in patients with atrial fibrillation. NTIRE has been shown to be a safe method for pulsed electroporation near the esophagus. NTIRE preserves the structural framework of the esophagus and allows for rapid recovery of the whole layers of the esophagus. The purpose of this study was to elucidate the ultrastructural changes and cytological mechanisms of cell regeneration and tissue repair after esophageal electroporation. The parameter combination of 2000 V/cm multiplied by 90-pulse output was directly applied to the esophagus in 60 New Zealand rabbits, and ultrastructure analysis of the esophagus was implemented subsequently. NTIRE predominantly triggered apoptosis of esophageal cells shortly after electroporation. Since the tissue structural framework was preserved, esophageal cells could regenerate through self-replication within 4 weeks. Complete anatomical repair can eventually be achieved through structural remodeling, and no lumen stenosis, ulcer, or fistula was observed in the ablated segment. Monophasic, bipolar NTIRE pulses delivered using plate electrodes in an esophageal model demonstrates no irreversible ultra-micropathological changes to the esophagus after 4 weeks.

Action spectra and mechanisms of (in) efficiency of bipolar electric pulses at electroporation

The reversal of the electric field direction inhibits various biological effects of nanosecond electric pulses (nsEP). This feature, known as “bipolar cancellation,” enables interference targeting of nsEP bioeffects remotely from stimulating electrodes, for prospective applications such as precise cancer ablation and non-invasive deep brain stimulation. This study was undertaken to achieve the maximum cancellation of electroporation, by quantifying the impact of the pulse shape, duration, number, and repetition rate across a broad range of electric field strengths. Monolayers of endothelial cells (BPAE) were electroporated in a non-uniform electric field. Cell membrane permeabilization was quantified by YO-PRO-1 (YP) dye uptake and correlated to local electric field strength. For most conditions tested, adding an opposite polarity phase reduced YP uptake by 50–80 %. The strongest cancellation, which reduced YP uptake by 95–97 %, was accomplished by adding a 50 % second phase to 600-ns pulses delivered at a high repetition rate of 833 kHz. Strobe photography of nanosecond kinetics of membrane potential in single CHO cells revealed the temporal summation of polarization by individual unipolar nsEP applied at sub-MHz rate, leading to enhanced electroporation. In contrast, there was no summation for bipolar pulses, and increasing their repetition rate suppressed electroporation. These new findings are discussed in the context of bipolar cancellation mechanisms and remote focusing applications.

Non-Thermal Processing of a Protein Functional Beverage Using Pulsed Electric Fields: Escherichia coli Inactivation and Effect on Proteins

The application of pulsed electric fields (PEFs) for the inactivation of Escherichia coli, suspended in a protein shake beverage and diluted with sterilized distilled water was carried out. Square bipolar pulses in the range of 25–40 kV/cm electric field intensities were applied at different frequencies (400–900 Hz) to investigate the effect of different PEF conditions on the microbial population and proteins relevant to this functional beverage. The treatment temperature was kept below the lethal temperature of the microorganism under investigation. As power consumption plays an important role in the efficiency of the PEF application, the dissipated power was also estimated. Four log reductions in the E. coli population were obtained with 10 pulses at a 40 kV/cm field intensity and 25 pulses at a 25 kV/cm field intensity. PEF-treated whey-protein concentrates showed less denaturation in proteins than thermally treated concentrates, especially for lower electric field intensities (0% denaturation ± 0.007 at 25 kV/cm and 900 Hz, 4.41% denaturation ± 0.008 at 40 kV/cm and 400 Hz). Soy protein isolates manifested high sensitivity to PEF processing and resulted in denaturation and aggregation in the protein structure.

A Solid-State Bipolar Pulse Power Generator for Dielectric Barrier Discharge Applications

This article provides a distinctive unipolar/bipolar high voltage pulse power generator (PPG) architecture that produces exponential waveform with a rise time in the range of nanosecond. The setup is fit for dielectric barrier discharge applications, in practice. In this work, a push-pull circuit with a three-winding transformer is utilized on the charging side, as well as a quasi-resonant between the transformer leakage inductance and the capacitor on the discharging side to boost the voltage gain. As a result of the two windings on the primary side, and the bidirectional switches on the high voltage side, the tool offers either unipolar or bipolar high voltage pulses from a relatively low dc source. In addition to accomplishing the high gain objective, the effort focuses on lowering the number of circuit elements in contrast to previously studied topologies. The generator functions in discontinuous conduction mode, which enhances system efficiency by allowing complete positive and/or negative waves to be generated while lessening conduction losses. The pulse generator operation intervals are described in depth. The simulation results will demonstrate how this topology outperforms the prior models. Moreover, a 1000-V experimental prototype is also implemented to validate the projected PPG-enhanced properties in real-time.

ИМПУЛЬСНЫЕ ХАРАКТЕРИСТИКИ КРЕМНИЕВЫХ СТРУКТУР С N-P ПЕРЕХОДОМ, ОБЛУЧЕННЫХ ПРОТОНАМИ

Currently, methods are being actively developed to create semiconductor structures with desiredproperties by irradiation with ionizing particles (radiation defect engineering). The interactionof radiation defects with impurities, dislocations and other structural defects causes a change in theproperties of semiconductors and semiconductor devices. Irradiation with protons makes it possibleto controllably create radiation defects with a distribution maximum in a pre-calculated region. Theaim of this work is to analyze the effect of irradiation with low-energy protons on the impulse characteristicsof silicon structures with an n+-p junction. The task is to determine the effective lifetime  ofcharge carriers in the space charge region (SCR) of the n+-p junction. The n+-p-p+-structures madeof silicon grown by the Czochralski method, irradiated from the side of the n+-layer by a low-energyproton flux at sample temperatures of 300 K and 83 K were studied. To measure the impulse characteristics,bipolar rectangular voltage pulses with a constant amplitude of 10 mV and a frequency of1 MHz were used. The experimental data are explained using models of nonstationary charge carriertransport in inhomogeneous semiconductors and the formation of radiation defects in silicon underthe action of protons. Depth distributions of the average number of primary radiation defects arecalculated: interstitial silicon, vacancies, divacancies created by one proton per unit length of theprojective path. It is shown that irradiation with protons with a dose of 1015 cm2 and an energy of40 keV does not change the value of , but with an energy of 180 keV creates a region with an effectivelifetime of 5.5108 s in the SCR of the n+-p junction.

Bipolar Pulse Current Magnetizer for Driving a Magnetization Reversal Motor

Magnetization reversal motors (MRMs) have been proposed as motors with lower power losses. MRMs comprise the same configuration as interior permanent magnet synchronous motors; however, a low coercive force core is applied to the stator. Driving an MRM requires a pulse current for magnetizing the stator core. In this paper, a bipolar pulse current magnetizer is proposed for driving MRMs Moreover, the relationship between passive components is reported in terms of voltage, current, and circuit constant. Finally, this paper presents experimental verification of the proposed magnetizer using an inductive load to simulate a single phase of an MRM.

Analysis and Design of a Compact Bipolar High-Voltage Short-Pulse Power Supply for DBD Application

As known, a short-pulse excitation voltage with a high rising rate and idle time [At this period, the current of dielectric barrier discharge (DBD) loads is equal to or close to zero] simultaneously is conducive to taking advantage of the potential of DBD loads. However, how to use a simple and classical topology to provide such an excitation voltage is rarely researched and is still an important issue for DBD application fields. The adoption of a set of modes that can generate the excitation voltage in a half-bridge-inverter and the design of a control strategy for the inverter are the main contributions of this article. Through mode analysis, the characteristics of the power supply are discussed, and a design process of the power supply is demonstrated. The simulation and experimental results show that not only an expected bipolar pulse excitation voltage can be generated, but also the soft-switching of all power switches is realized. Compared with other types of power supplies, the potential of the excimer lamp can be well developed with the presented power supply, and the power supply has the advantages of a more compact structure, fewer components and higher working frequency.