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Sample records for 600-ns electric pulses

  1. Calcium influx affects intracellular transport and membrane repair following nanosecond pulsed electric field exposure

    NASA Astrophysics Data System (ADS)

    Thompson, Gary Lee; Roth, Caleb C.; Dalzell, Danielle R.; Kuipers, Marjorie; Ibey, Bennett L.

    2014-05-01

    The cellular response to subtle membrane damage following exposure to nanosecond pulsed electric fields (nsPEF) is not well understood. Recent work has shown that when cells are exposed to nsPEF, ion permeable nanopores (<2 nm) are created in the plasma membrane in contrast to larger diameter pores (>2 nm) created by longer micro- and millisecond duration pulses. Nanoporation of the plasma membrane by nsPEF has been shown to cause a transient increase in intracellular calcium concentration within milliseconds after exposure. Our research objective is to determine the impact of nsPEF on calcium-dependent structural and repair systems in mammalian cells. Chinese hamster ovary (CHO-K1) cells were exposed in the presence and absence of calcium ions in the outside buffer to either 1 or 20, 600-ns duration electrical pulses at 16.2 kV/cm, and pore size was determined using propidium iodide and calcium green. Membrane organization was observed with morphological changes and increases in FM1-43 fluorescence. Migration of lysosomes, implicated in membrane repair, was followed using confocal microscopy of red fluorescent protein-tagged LAMP1. Microtubule structure was imaged using mEmerald-tubulin. We found that at high 600-ns PEF dosage, calcium-induced membrane restructuring and microtubule depolymerization coincide with interruption of membrane repair via lysosomal exocytosis.

  2. Electrical pulse generator

    DOEpatents

    Norris, Neil J.

    1979-01-01

    A technique for generating high-voltage, wide dynamic range, shaped electrical pulses in the nanosecond range. Two transmission lines are coupled together by resistive elements distributed along the length of the lines. The conductance of each coupling resistive element as a function of its position along the line is selected to produce the desired pulse shape in the output line when an easily produced pulse, such as a step function pulse, is applied to the input line.

  3. ELECTRICAL PULSE COUNTER APPARATUS

    DOEpatents

    Kaufman, W.M.; Jeeves, T.A.

    1962-09-01

    A progressive electrical pulse counter circuit rs designed for the counting of a chain of input pulses. The circuit employs a series of direct connected bistable counting stages simultaneously pulsed by each input pulse and a delay means connected between each of the stages. Each bistable stage has two d-c operative states, which stage, when in its initial state, prevents the next succeeding stage from changing its condition when the latter stage is pulsed. Since the delay circuits between the stages prevents the immediate decay of the d-c state of each stage when the stages are pulsed, only one stage will change its state for each input pulse, thereby providing progressive stage-by-stage counting. (AEC)

  4. Pulsed electric fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

  5. Transient features in nanosecond pulsed electric fields differentially modulate mitochondria and viability.

    PubMed

    Beebe, Stephen J; Chen, Yeong-Jer; Sain, Nova M; Schoenbach, Karl H; Xiao, Shu

    2012-01-01

    It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs), determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0-80 kV/cm) and short (15 ns) or long (150 ns) rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE) to determine mitochondria membrane potentials (ΔΨm). Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death. PMID:23284682

  6. ELECTRIC PULSE GENERATOR

    DOEpatents

    Buntenbach, R.W.

    1959-06-01

    S>An electro-optical apparatus is described which produces electric pulses in programmed sequences at times and durations controlled with great accuracy. An oscilloscope CRT is supplied with signals to produce a luminous spot moving in a circle. An opaque mask with slots of variable width transmits light from the spot to a photoelectric transducer. For shorter pulse decay times a CRT screen which emits UV can be used with a UVtransmitting filter and a UV- sensitive photoelectric cell. Pulses are varied by changing masks or by using masks with variable slots. This device may be used in multiple arrangements to produce other pulse aT rangements, or it can be used to trigger an electronic pulse generator. (T.R.H.)

  7. Changes in protein expression of U937 and Jurkat cells exposed to nanosecond pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Moen, Erick K.; Roth, Caleb C.; Cerna, Caesar; Estalck, Larry; Wilmink, Gerald; Ibey, Bennett L.

    2013-02-01

    Application of nanosecond pulsed electric fields (nsPEF) to various biological cell lines has been to shown to cause many diverse effects, including poration of the plasma membrane, depolarization of the mitochondrial membrane, blebbing, apoptosis, and intracellular calcium bursts. The underlying mechanism(s) responsible for these diverse responses are poorly understood. Of specific interest in this paper are the long-term effects of nsPEF on cellular processes, including the regulation of genes and production of proteins. Previous studies have reported transient activation of select signaling pathways involving mitogen-activated protein kinases (MAPKs), protein phosphorylation and downstream gene expression following nsPEF application. We hypothesize that nsPEF represents a unique stimulus that could be used to externally modulate cellular processes. To validate our hypothesis, we performed a series of cuvette-based exposures at 10 and 600ns pulse widths using a custom Blumlien line pulser system. We measured acute changes in the plasma membrane structure using flow cytometry by tracking phosphatidylserine externalization via FITC-Annexin V labeling and poration via propidium iodide uptake. We then compared these results to viability of the cells at 24 hours post exposure using MTT assay and changes in the MAPK family of proteins at 8 hours post-exposure using Luminex assay. By comparing exposures at 10 and 600ns duration, we found that most MAPK family-protein expression increased in Jurkat and U937 cell lines following exposure and compared well with drops in viability and changes in plasma membrane asymmetry. What proved interesting is that some MAPK family proteins (e.g. p53, STAT1), were expressed in one cell line, but not the other. This difference may point to an underlying mechanism for observed difference in cellular sensitivity to nsPEFinduced stresses.

  8. Neurostimulation using subnanosecond electric pulses

    NASA Astrophysics Data System (ADS)

    Xiao, Shu; Pakhomov, Andrei; Guo, Fei; Polisetty, Swetha; Schoenbach, Karl H.

    2013-02-01

    We have for the first time recorded action potentials in rat hippocampus neurons when they were stimulated by subnanosecond electric pulses. The preliminary results show that applying a series of pulses allowed the accumulation of depolarization before activating the voltage gated channels. The depolarization only occurred when the electric pulses were applied. It is unclear whether the depolarization is caused by the charge accumulation across the membrane or the cation influx due to the membrane permeabilization. We have also conducted an electromagnetic simulation of delivering subnanosecond pulses to tissues using an impulse radiating antenna. The results show that the pulses can be confined in the deep region in the brain but the amplitude is reduced significantly due to the attenuation of the tissues. A partially lossy dielectric lens may be used to reverse the decreasing trend of the electric field.

  9. Nanosecond pulsed electric field thresholds for nanopore formation in neural cells

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Tolstykh, Gleb P.; Payne, Jason A.; Kuipers, Marjorie A.; Thompson, Gary L.; DeSilva, Mauris N.; Ibey, Bennett L.

    2013-03-01

    The persistent influx of ions through nanopores created upon cellular exposure to nanosecond pulse electric fields (nsPEF) could be used to modulate neuronal function. One ion, calcium (Ca), is important to action potential firing and regulates many ion channels. However, uncontrolled hyper-excitability of neurons leads to Ca overload and neurodegeneration. Thus, to prevent unintended consequences of nsPEF-induced neural stimulation, knowledge of optimum exposure parameters is required. We determined the relationship between nsPEF exposure parameters (pulse width and amplitude) and nanopore formation in two cell types: rodent neuroblastoma (NG108) and mouse primary hippocampal neurons (PHN). We identified thresholds for nanoporation using Annexin V and FM1-43, to detect changes in membrane asymmetry, and through Ca influx using Calcium Green. The ED50 for a single 600 ns pulse, necessary to cause uptake of extracellular Ca, was 1.76 kV/cm for NG108 and 0.84 kV/cm for PHN. At 16.2 kV/cm, the ED50 for pulse width was 95 ns for both cell lines. Cadmium, a nonspecific Ca channel blocker, failed to prevent Ca uptake suggesting that observed influx is likely due to nanoporation. These data demonstrate that moderate amplitude single nsPEF exposures result in rapid Ca influx that may be capable of controllably modulating neurological function.

  10. External stimulation by nanosecond pulsed electric fields to enhance cellular uptake of nanoparticles

    NASA Astrophysics Data System (ADS)

    Franklin, Samantha; Beier, Hope T.; Ibey, Bennett L.; Nash, Kelly

    2015-03-01

    As an increasing number of studies use gold nanoparticles (AuNPs) for potential medicinal, biosensing and therapeutic applications, the synthesis and use of readily functional, bio-compatible nanoparticles is receiving much interest. For these efforts, the particles are often taken up by the cells to allow for optimum sensing or therapeutic measures. This process typically requires incubation of the particles with the cells for an extended period. In an attempt to shorten and control this incubation, we investigated whether nanosecond pulsed electric field (nsPEF) exposure of cells will cause a controlled uptake of the particles. NsPEF are known to induce the formation of nanopores in the plasma membrane, so we hypothesized that by controlling the number, amplitude or duration of the nsPEF exposure, we could control the size of the nanopores, and thus control the particle uptake. Chinese hamster ovary (CHO-K1) cells were incubated sub-10 nm AuNPs with and without exposure to 600-ns electrical pulses. Contrary to our hypothesis, the nsPEF exposure was found to actually decrease the particle uptake in the exposed cells. This result suggests that the nsPEF exposure may be affecting the endocytotic pathway and processes due to membrane disruption.

  11. High frequency application of nanosecond pulsed electric fields alters cellular membrane disruption and fluorescent dye uptake

    NASA Astrophysics Data System (ADS)

    Steelman, Zachary A.; Tolstykh, Gleb P.; Beier, Hope T.; Ibey, Bennett L.

    2016-03-01

    Cells exposed to nanosecond-pulsed electric fields (nsPEF) exhibit a wide variety of nonspecific effects, including blebbing, swelling, intracellular calcium bursts, apoptotic and necrotic cell death, formation of nanopores, and depletion of phosphatidylinositol 4,5-biphosphate (PIP2) to induce activation of the inositol trisphosphate/diacylglycerol pathway. While several studies have taken place in which multiple pulses were delivered to cells, the effect of pulse repetition rate (PRR) is not well understood. To better understand the effects of PRR, a laser scanning confocal microscope was used to observe CHO-K1 cells exposed to ten 600ns, 200V pulses at varying repetition rates (5Hz up to 500KHz) in the presence of either FM 1-43, YO-PRO-1, or Propidium Iodide (PI) fluorescent dyes, probes frequently used to indicate nanoporation or permeabilization of the plasma membrane. Dye uptake was monitored for 30 seconds after pulse application at a rate of 1 image/second. In addition, a single long pulse of equivalent energy (200V, 6 μs duration) was applied to test the hypothesis that very fast PRR will approximate the biological effects of a single long pulse of equal energy. Upon examination of the data, we found strong variation in the relationship between PRR and uptake in each of the three dyes. In particular, PI uptake showed little frequency dependence, FM 1-43 showed a strong inverse relationship between frequency and internal cell fluorescence, and YO-PRO-1 exhibited a "threshold" point of around 50 KHz, after which the inverse trend observed in FM 1-43 was seen to reverse itself. Further, a very high PRR of 500 KHz only approximated the biological effects of a single 6 μs pulse in cells stained with YO-PRO-1, suggesting that uptake of different dyes may proceed by different physical mechanisms.

  12. Pulsed plasmoid electric propulsion

    NASA Technical Reports Server (NTRS)

    Bourque, Robert F.; Parks, Paul B.; Tamano, Teruo

    1990-01-01

    A method of electric propulsion is explored where plasmoids such as spheromaks and field reversed configurations (FRC) are formed and then allowed to expand down a diverging conducting shell. The plasmoids contain a toroidal electric current that provides both heating and a confining magnetic field. They are free to translate because there are no externally supplied magnetic fields that would restrict motion. Image currents in the diverging conducting shell keep the plasmoids from contacting the wall. Because these currents translate relative to the wall, losses due to magnetic flux diffusion into the wall are minimized. During the expansion of the plasma in the diverging cone, both the inductive and thermal plasma energy are converted to directed kinetic energy producing thrust. Specific impulses can be in the 4000 to 20000 sec range with thrusts from 0.1 to 1000 Newtons, depending on available power.

  13. Neuromuscular disruption with ultrashort electrical pulses

    NASA Astrophysics Data System (ADS)

    Pakhomov, Andrei; Kolb, Juergen F.; Joshi, Ravindra P.; Schoenbach, Karl H.; Dayton, Thomas; Comeaux, James; Ashmore, John; Beason, Charles

    2006-05-01

    Experimental studies on single cells have shown that application of pulsed voltages, with submicrosecond pulse duration and an electric field on the order of 10 kV/cm, causes sudden alterations in the intracellular free calcium concentration, followed by immobilization of the cell. In order to examine electrical stimulation and incapacitation with such ultrashort pulses, experiments on anesthetized rats have been performed. The effect of single, 450 nanosecond monopolar pulses have been compared with that of single pulses with multi-microsecond duration (TASER pulses). Two conditions were explored: 1. the ability to elicit a muscle twitch, and, 2. the ability to suppress voluntary movement by using nanosecond pulses. The second condition is relevant for neuromuscular incapacitation. The preliminary results indicate that for stimulation microsecond pulses are advantageous over nanosecond pulses, whereas for incapacitation, the opposite seems to apply. The stimulation effects seem to scale with electrical charge, whereas the disruption effects don't follow a simple scaling law. The increase in intensity (time of incapacitation) for a given pulse duration, is increasing with electrical energy, but is more efficient for nanosecond than for microsecond pulses. This indicates different cellular mechanisms for incapacitation, most likely subcellular processes, which have been shown to become increasingly important when the pulse duration is shortened into the nanosecond range. If further studies can confirm these initial results, consequences of reduced pulse duration are a reduction in weight and volume of the pulse delivery system, and likely, because of the lower required energy for neuromuscular incapacitation, reduced safety risks.

  14. Pulsed electric field increases reproduction.

    PubMed

    Panagopoulos, Dimitris J

    2016-01-01

    Purpose To study the effect of pulsed electric field - applied in corona discharge photography - on Drosophila melanogaster reproduction, possible induction of DNA fragmentation, and morphological alterations in the gonads. Materials and methods Animals were exposed to different field intensities (100, 200, 300, and 400 kV/m) during the first 2-5 days of their adult lives, and the effect on reproductive capacity was assessed. DNA fragmentation during early- and mid-oogenesis was investigated by application of the TUNEL (Terminal deoxynucleotide transferase dUTP Nick End Labeling) assay. Sections of follicles after fixation and embedding in resins were observed for possible morphological/developmental abnormalities. Results The field increased reproduction by up to 30% by increasing reproductive capacity in both sexes. The effect increased with increasing field intensities. The rate of increase diminished at the strongest intensities. Slight induction of DNA fragmentation was observed exclusively in the nurse (predominantly) and follicle cells, and exclusively at the two most sensitive developmental stages, i.e., germarium and predominantly stage 7-8. Sections of follicles from exposed females at stages of early and mid-oogennesis other than germarium and stages 7-8 did not reveal abnormalities. Conclusions (1) The specific type of electric field may represent a mild stress factor, inducing DNA fragmentation and cell death in a small percentage of gametes, triggering the reaction of the animal's reproductive system to increase the rate of gametogenesis in order to compensate the loss of a small number of gametes. (2) The nurse cells are the most sensitive from all three types of egg chamber cells. (3) The mid-oogenesis checkpoint (stage 7-8) is more sensitive to this field than the early oogenesis one (germarium) in contrast to microwave exposure. (4) Possible therapeutic applications, or applications in increasing fertility, should be investigated. PMID:26651869

  15. Coherent Fourier transform electrical pulse shaping.

    PubMed

    Xiao, Shijun; Weiner, Andrew M

    2006-04-01

    Fourier synthesis pulse shaping methods allowing generation of programmable, user defined femtosecond optical waveforms have been widely applied in ultrafast optical science and technology. In the electrical domain, arbitrary waveform generation is well established at frequencies below approximately 1 GHz, but is difficult at higher frequencies due to limitations in digital-to-analog converter technology. In this paper we demonstrate a method for electrical waveform synthesis at substantially higher frequencies (approximately 20 GHz electrical bandwidth) by combining Fourier optical pulse shaping (extended to hyperfine frequency resolution) and heterodyne optical to electrical conversion. Our scheme relies on coherent manipulation of fields and phases at all stages, both for processing in the optical domain and for conversion from the optical to the electrical domain. We illustrate this technique through a number of examples, including programmable retardation or advancement of short electrical pulses in time over a range exceeding ten pulse durations. Such optically implemented, coherent Fourier transform electrical pulse shaping should open new prospects in ultrawideband electromagnetics. PMID:19516448

  16. Transcranial electrical stimulator producing high amplitude pulses and pulse trains.

    PubMed

    Suihko, V; Eskola, H

    1998-01-01

    Transcranial electrical stimulation can be used for clinical investigations of the central nervous system and for monitoring of motor nerve tracts during surgical operations. We wished to reduce the pain involved with the transcranial electrical stimulation and to improve the usefulness of the method for monitoring during surgical operations. A dedicated transcranial electrical stimulator was designed having special features to reduce the pain sensation and the nerve blocking effect of anaesthetics. It provides constant current and constant voltage stimulation pulses with very short duration and high amplitude. The pulse length is adjustable in the range of 15 to 125 microseconds, while the maximum amplitude is 100 V and 1 A for voltage and current stimulation modes, respectively. Special features included high-repetition-rate pulse trains (50-2000 pulses s-1) and a three-electrode stimulation configuration. We suggest that the electrical transcranial stimulation has the potential to be a relatively painless method for routine clinical investigations and a reliable method for monitoring during surgery. PMID:9807743

  17. Safety of pulsed electric devices.

    PubMed

    Nimunkar, Amit J; Webster, John G

    2009-01-01

    The strength-duration curve for tissue excitation can be modeled by a parallel resistor-capacitor circuit that has a time constant. We tested several short-duration electric generators: five electric fence energizers, the Taser X26 and a high-frequency generator to determine their current-versus-time waveforms. We estimated their safety characteristics using existing IEC and UL standards for electric fence energizers. The current standards are difficult to follow, with cumbersome calculations, and do not explicitly explain the physiological relevance of the calculated parameters. Hence we propose a new standard. The proposed new standard would consist of a physical RC circuit with a certain time constant. The investigator would discharge the device into a passive resistor-capacitor circuit and measure the resulting maximum voltage. If the maximum voltage does not exceed a limit, the device passes the test. PMID:19104137

  18. Pulsed Electric Propulsion Thrust Stand Calibration Method

    NASA Technical Reports Server (NTRS)

    Wong, Andrea R.; Polzin, Kurt A.; Pearson, J. Boise

    2011-01-01

    The evaluation of the performance of any propulsion device requires the accurate measurement of thrust. While chemical rocket thrust is typically measured using a load cell, the low thrust levels associated with electric propulsion (EP) systems necessitate the use of much more sensitive measurement techniques. The design and development of electric propulsion thrust stands that employ a conventional hanging pendulum arm connected to a balance mechanism consisting of a secondary arm and variable linkage have been reported in recent publications by Polzin et al. These works focused on performing steady-state thrust measurements and employed a static analysis of the thrust stand response. In the present work, we present a calibration method and data that will permit pulsed thrust measurements using the Variable Amplitude Hanging Pendulum with Extended Range (VAHPER) thrust stand. Pulsed thrust measurements are challenging in general because the pulsed thrust (impulse bit) occurs over a short timescale (typically 1 micros to 1 millisecond) and cannot be resolved directly. Consequently, the imparted impulse bit must be inferred through observation of the change in thrust stand motion effected by the pulse. Pulsed thrust measurements have typically only consisted of single-shot operation. In the present work, we discuss repetition-rate pulsed thruster operation and describe a method to perform these measurements. The thrust stand response can be modeled as a spring-mass-damper system with a repetitive delta forcing function to represent the impulsive action of the thruster.

  19. Pulsed electric breakdown in adipose tissue

    NASA Astrophysics Data System (ADS)

    Kolb, Juergen F.; Scully, Noah; Paithankar, Dilip

    2011-08-01

    High voltage pulses of sub-microsecond duration can instigate electrical breakdown in adipose tissue, which is followed by a spark discharge. Breakdown voltages are generally lower than observed for purified lipids but higher than for air. Development of breakdown for the repetitive application of pulses resembles a gradual and stochastic process as reported for partial discharges in solid dielectrics. The inflicted tissue damage itself is confined to the gap between electrodes, providing a method to use spark discharges as a precise surgical technique.

  20. Earthquake Triggering by High Power Electric Pulses

    NASA Astrophysics Data System (ADS)

    Novikov, Victor; Konev, Yuri; Zeigarnik, Vladimir

    2010-05-01

    The study carried out by the Joint Institute for High Temperatures in cooperation with the Institute of Physics of the Earth and the Research Station in Bishkek of Russian Academy of Sciences in 1999-2008 showed a response of weak seismicity at field experiments with electric pulsed power systems, as well as acoustic emission of rock specimens under laboratory conditions on high-power electric current pulses applied to the rocks. It was suggested that the phenomenon discovered may be used in practice for partial release of tectonic stresses in the Earth crust for earthquake hazard mitigation. Nevertheless, the mechanism of the influence of man-made electromagnetic field on the regional seismicity is not clear yet. One of possible cause of the phenomenon may be pore fluid pressure increase in the rocks under stressed conditions due to Joule heat generation by electric current injected into the Earth crust. It is known that increase of pore fluid pressure in the fault zone over a critical pressure of about 0.05 MPa is sufficient to trigger an earthquake if the fault is near the critical state due to accumulated tectonic deformations. Detailed 3D-calculaton of electric current density in the Earth crust of the Northern Tien Shan provided by pulsed electric high-power system connected to grounded electric dipole showed that at the depth of earthquake epicenters (over 5 km) the electric current density is lower than 10-7 A/m2 that is not sufficient for increase of pressure in the fluid-saturated porous geological medium due to Joule heat generation, which may provide formation of cracks resulting in the fault propagation and release of tectonic stresses in the Earth crust. Nevertheless, under certain conditions, when electric current will be injected into the fault through the casing pipes of two deep wells with preliminary injection of conductive fluid into the fault, the current density may be high enough for significant increase of mechanic pressure in the porous two

  1. Hemorrhage control by microsecond electrical pulses

    NASA Astrophysics Data System (ADS)

    Mandel, Yossi; Manivanh, Richard; Dalal, Roopa; Huie, Phil; Wang, Jenny; Brinton, Mark; Palanker, Daniel

    2013-02-01

    Non-compressible hemorrhages are the most common preventable cause of death on battlefield or in civilian traumatic injuries. We report the use of sub-millisecond pulses of electric current to induce rapid constriction in femoral and mesenteric arteries and veins in rats. Extent of vascular constriction could be modulated by pulse duration, amplitude and repetition rate. Electrically-induced vasoconstriction could be maintained at steady level until the end of stimulation, and blood vessels dilated back to their original size within a few minutes after the end of stimulation. At higher settings, a blood clotting could be introduced, leading to complete and permanent occlusion of the vessels. The latter regime dramatically decreased the bleeding rate in the injured femoral and mesenteric arteries, with a complete hemorrhage arrest achieved within seconds. The average blood loss from the treated femoral artery was about 7 times less than that of a non-treated control. This new treatment modality offers a promising approach to non-damaging control of bleeding during surgery, and to efficient hemorrhage arrest in trauma patients.

  2. MULTI-CHANNEL ELECTRIC PULSE HEIGHT ANALYZER

    DOEpatents

    Gallagher, J.D. et al.

    1960-11-22

    An apparatus is given for converting binary information into coded decimal form comprising means, in combination with a binary adder, a live memory and a source of bigit pulses, for synchronizing the bigit pulses and the adder output pulses; a source of digit pulses synchronized with every fourth bigit pulse; means for generating a conversion pulse in response to the time coincidence of the adder output pulse and a digit pulse: means having a delay equal to two bigit pulse periods coupling the adder output with the memory; means for promptly impressing said conversion pulse on the input of said memory: and means having a delay equal to one bigit pulse period for again impressing the conversion pulse on the input of the memory whereby a fourth bigit adder pulse results in the insertion into the memory of second, third and fourth bigits.

  3. The Effects of Intense Submicrosecond Electrical Pulses on Cells

    PubMed Central

    Deng, Jingdong; Schoenbach, Karl H.; Buescher, E. Stephen; Hair, Pamela S.; Fox, Paula M.; Beebe, Stephen J.

    2003-01-01

    A simple electrical model for living cells predicts an increasing probability for electric field interactions with intracellular substructures of both prokaryotic and eukaryotic cells when the electric pulse duration is reduced into the sub-microsecond range. The validity of this hypothesis was verified experimentally by applying electrical pulses (durations 100 μs–60 ns, electric field intensities 3–150 kV/cm) to Jurkat cells suspended in physiologic buffer containing propidium iodide. Effects on Jurkat cells were assessed by means of temporally resolved fluorescence and light microscopy. For the longest applied pulses, immediate uptake of propidium iodide occurred consistent with electroporation as the cause of increased surface membrane permeability. For nanosecond pulses, more delayed propidium iodide uptake occurred with significantly later uptake of propidium iodide occurring after 60 ns pulses compared to 300 ns pulses. Cellular swelling occurred rapidly following 300 ns pulses, but was minimal following 60 ns pulses. These data indicate that submicrosecond pulses achieve temporally distinct effects on living cells compared to microsecond pulses. The longer pulses result in rapid permeability changes in the surface membrane that are relatively homogeneous across the cell population, consistent with electroporation, while shorter pulses cause surface membrane permeability changes that are temporally delayed and heterogeneous in their magnitude. PMID:12668479

  4. Plasma Membrane Permeabilization by Trains of Ultrashort Electric Pulses

    PubMed Central

    Ibey, Bennett L.; Mixon, Dustin G.; Payne, Jason A.; Bowman, Angela; Sickendick, Karl; Wilmink, Gerald J.; Roach, W. Patrick; Pakhomov, Andrei G.

    2010-01-01

    Ultrashort electric pulses (USEP) cause long-lasting increase of cell membrane electrical conductance, and that a single USEP increased cell membrane electrical conductance proportionally to the absorbed dose (AD) with a threshold of about 10 mJ/g. The present study extends quantification of the membrane permeabilization effect to multiple USEP and employed a more accurate protocol that identified USEP effect as the difference between post- and pre-exposure conductance values (Δg) in individual cells. We showed that Δg can be increased by either increasing the number of pulses at a constant E-field, or by increasing the E-field at a constant number of pulses. For 60-ns pulses, an E-field threshold of 6 kV/cm for a single pulse was lowered to less than 1.7 kV/cm by applying 100-pulse or longer trains. However, the reduction of the E-field threshold was only achieved at the expense of a higher AD compared to a single pulse exposure. Furthermore, the effect of multiple pulses was not fully determined by AD, suggesting that cells permeabilized by the first pulse(s) in the train become less vulnerable to subsequent pulses. This explanation was corroborated by a model that treated multiple-pulse exposures as a series of single-pulse exposures and assumed an exponential decline of cell susceptibility to USEP as Δg increased after each pulse during the course of the train. PMID:20171148

  5. Electrical breakdown of soil under nonlinear pulsed current spreading

    NASA Astrophysics Data System (ADS)

    Vasilyak, L. M.; Pecherkin, V. Ya; Vetchinin, S. P.; Panov, V. A.; Son, E. E.; Efimov, B. V.; Danilin, A. N.; Kolobov, V. V.; Selivanov, V. N.; Ivonin, V. V.

    2015-07-01

    Laboratory investigations on pulsed current spreading from spherical electrodes and evolution of electrical breakdown of silica sand with different water contents under a 15-20 kV voltage pulse were carried out. A sharp nonlinear decrease in the pulsed resistance of soil was observed when the current density exceeded a certain threshold value. Then ionization-overheating instability develops and leads to current contraction and plasma channel formation in the soil. The method for determination of the threshold electric field for ionization is proposed. Electrical discharge in wet sand was found to develop with a significant delay time for long discharge gaps similar to thermal breakdown.

  6. Bipolar nanosecond electric pulses are less efficient at electropermeabilization and killing cells than monopolar pulses

    PubMed Central

    Ibey, Bennett L.; Ullery, Jody; Pakhomova, Olga N.; Roth, Caleb C.; Semenov, Iurri; Beier, Hope T.; Tarango, Melissa; Xiao, Shu; Schoenbach, Karl; Pakhomov, Andrei G.

    2014-01-01

    Multiple studies have shown that bipolar (BP) electric pulses in the microsecond range are more effective at permeabilizing cells while maintaining similar cell survival rates as compared to monopolar (MP) pulse equivalents. In this paper, we investigated whether the same advantage existed for BP nanosecond-pulsed electric fields (nsPEF) as compared to MP nsPEF. To study permeabilization effectiveness, MP or BP pulses were delivered to single Chinese hamster ovary (CHO) cells and the response of three dyes, Calcium Green-1, Propidium Iodide (PI), and FM1-43, was measured by confocal microscopy. Results show that BP pulses were less effective at increasing intracellular calcium concentration or PI uptake and cause less membrane reorganization (FM1-43) than MP pulses. Twenty-four hour survival was measured in three cell lines (Jurkat, U937, CHO) and over ten times more BP pulses were required to induce death as compared to MP pulses of similar magnitude and duration. Flow cytometry analysis of CHO cells after exposure (15 minutes) revealed that to achieve positive FITC-Annexin V and PI expression, ten times more BP pulses were required than MP pulses. Overall, unlike longer pulse exposures, BP nsPEF exposures proved far less effective at both membrane permeabilization and cell killing than MP nsPEF. PMID:24332942

  7. Nanopore formation in neuroblastoma cells following ultrashort electric pulse exposure

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Payne, Jason A.; Wilmink, Gerald J.; Ibey, Bennett L.

    2011-03-01

    Ultrashort or nanosecond electrical pulses (USEP) cause repairable damage to the plasma membranes of cells through formation of nanopores. These nanopores are able to pass small ions such as sodium, calcium, and potassium, but remain impermeable to larger molecules like trypan blue and propidium iodide. What remains uncertain is whether generation of nanopores by ultrashort electrical pulses can inhibit action potentials in excitable cells. In this paper, we explored the sensitivity of excitable cells to USEP using Calcium Green AM 1 ester fluorescence to measure calcium uptake indicative of nanopore formation in the plasma membrane. We determined the threshold for nanopore formation in neuroblastoma cells for three pulse parameters (amplitude, pulse width, and pulse number). Measurement of such thresholds will guide future studies to determine if USEP can inhibit action potentials without causing irreversible membrane damage.

  8. Microsecond-scale electric field pulses in cloud lightning discharges

    NASA Technical Reports Server (NTRS)

    Villanueva, Y.; Rakov, V. A.; Uman, M. A.; Brook, M.

    1994-01-01

    From wideband electric field records acquired using a 12-bit digitizing system with a 500-ns sampling interval, microsecond-scale pulses in different stages of cloud flashes in Florida and New Mexico are analyzed. Pulse occurrence statistics and waveshape characteristics are presented. The larger pulses tend to occur early in the flash, confirming the results of Bils et al. (1988) and in contrast with the three-stage representation of cloud-discharge electric fields suggested by Kitagawa and Brook (1960). Possible explanations for the discrepancy are discussed. The tendency for the larger pulses to occur early in the cloud flash suggests that they are related to the initial in-cloud channel formation processes and contradicts the common view found in the atmospheric radio-noise literature that the main sources of VLF/LF electromagnetic radiation in cloud flashes are the K processes which occur in the final, or J type, part of the cloud discharge.

  9. Intense ionospheric electric and magnetic field pulses generated by lightning

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Ding, J. G.; Holzworth, R. H.

    1990-01-01

    Electric and magnetic field measurements have been made in the ionosphere over an active thunderstorm and an optical detector onboard the same rocket yielded an excellent time base for the study of waves radiated into space from the discharge. In addition to detection of intense, but generally well understood whistler mode waves, very unusual electric and magnetic field pulses preceded the 1-10 kHz component of the radiated signal. These pulses lasted several ms and had a significant electric field component parallel to the magnetic field. No known propagating wave mode has this polarization nor a signal propagation velocity as high as those measured here. This study investigated and rejected an explanation based on an anomalous skin depth effect. Although only a hypothesis at this time, a more promising explanation involving the generation of the pulse via a nonlinear decay of whistler mode waves in the frequency range 10-80 kHz is being investigated.

  10. Skin rejuvenation with non-invasive pulsed electric fields.

    PubMed

    Golberg, Alexander; Khan, Saiqa; Belov, Vasily; Quinn, Kyle P; Albadawi, Hassan; Felix Broelsch, G; Watkins, Michael T; Georgakoudi, Irene; Papisov, Mikhail; Mihm, Martin C; Austen, William G; Yarmush, Martin L

    2015-01-01

    Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature, and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases. PMID:25965851

  11. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    PubMed Central

    Golberg, Alexander; Khan, Saiqa; Belov, Vasily; Quinn, Kyle P.; Albadawi, Hassan; Felix Broelsch, G.; Watkins, Michael T.; Georgakoudi, Irene; Papisov, Mikhail; Mihm Jr., Martin C.; Austen Jr., William G.; Yarmush, Martin L.

    2015-01-01

    Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature, and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases. PMID:25965851

  12. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    NASA Astrophysics Data System (ADS)

    Golberg, Alexander; Khan, Saiqa; Belov, Vasily; Quinn, Kyle P.; Albadawi, Hassan; Felix Broelsch, G.; Watkins, Michael T.; Georgakoudi, Irene; Papisov, Mikhail; Mihm, Martin C., Jr.; Austen, William G., Jr.; Yarmush, Martin L.

    2015-05-01

    Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature, and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases.

  13. Temporal pulse shaping for smoothing of printed metal surfaces

    NASA Astrophysics Data System (ADS)

    Berg, Yuval; Zenou, Michael; Dolev, Omer; Kotler, Zvi

    2015-01-01

    The surfaces of laser-induced forward transfer (LIFT) printed metal structures show typical roughness characteristic of the metal droplet size (3 to 10 μm). Submicron voids are often observed in the bulk of such printed metal structures with consequences on the mechanical strength, chemical resistivity, and electrical conductivity. We present the results of our efforts to reduce surface roughness and bulk voids by controlled laser melting. We have used temporally shaped pulses from a fiber laser tunable in the range from 1 to 600 ns in order to improve the quality of LIFT printed copper and aluminum structures. For the best case shown, roughness was improved from RRMS=0.8 μm to RRMS=0.2 μm and the relative percentage of the voids was reduced from 7.3% to 0.9%.

  14. Electrical characterization of a Mapham inverter using pulse testing techniques

    NASA Technical Reports Server (NTRS)

    Baumann, E. D.; Myers, I. T.; Hammoud, A. N.

    1990-01-01

    The use of a multiple pulse testing technique to determine the electrical characteristics of large megawatt-level power systems for aerospace missions is proposed. An innovative test method based on the multiple pulse technique is demonstrated on a 2-kW Mapham inverter. The concept of this technique shows that characterization of large power systems under electrical equilibrium at rated power can be accomplished without large costly power supplies. The heat generation that occurs in systems when tested in a continuous mode is eliminated. The results indicate that there is a good agreement between this testing technique and that of steady state testing.

  15. Wave packet dynamics under effect of a pulsed electric field

    NASA Astrophysics Data System (ADS)

    da Silva, A. R. C. B.; de Moura, F. A. B. F.; Dias, W. S.

    2016-06-01

    We studied the dynamics of an electron in a crystalline one-dimensional model under effect of a time-dependent Gaussian field. The time evolution of an initially Gaussian wave packet it was obtained through the numerical solution of the time-dependent Schrödinger equation. Our analysis consists of computing the electronic centroid as well as the mean square displacement. We observe that the electrical pulse is able to promote a special kind of displacement along the chain. We demonstrated a direct relation between the group velocity of the wave packet and the applied electrical pulses. We compare those numerical calculations with a semi-classical approach.

  16. Electrical characterization of a Mapham inverter using pulse testing techniques

    NASA Astrophysics Data System (ADS)

    Baumann, E. D.; Myers, I. T.; Hammoud, A. N.

    The use of a multiple pulse testing technique to determine the electrical characteristics of large megawatt-level power systems for aerospace missions is proposed. An innovative test method based on the multiple pulse technique is demonstrated on a 2-kW Mapham inverter. The concept of this technique shows that characterization of large power systems under electrical equilibrium at rated power can be accomplished without large costly power supplies. The heat generation that occurs in systems when tested in a continuous mode is eliminated. The results indicate that there is a good agreement between this testing technique and that of steady state testing.

  17. Pulsed electric field processing for fruit and vegetables

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This month’s column reviews the theory and current applications of pulsed electric field (PEF) processing for fruits and vegetables to improve their safety and quality. This month’s column coauthor, Stefan Toepfl, is advanced research manager at the German Institute of Food Technologies and professo...

  18. Pulsed electric field (PEF)research at USDA, ARS, ERRC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article summarizes the effects of pulsed electric fields on the microbiological safety and quality aspects of various liquid food matrices, obtained at USDA, ARS, Eastern Regional Research Center under CRIS Project No. 1935-41420-013-00D, Processing Intervention Technologies for Enhancing the S...

  19. Broadband electrically detected magnetic resonance using adiabatic pulses.

    PubMed

    Hrubesch, F M; Braunbeck, G; Voss, A; Stutzmann, M; Brandt, M S

    2015-05-01

    We present a broadband microwave setup for electrically detected magnetic resonance (EDMR) based on microwave antennae with the ability to apply arbitrarily shaped pulses for the excitation of electron spin resonance (ESR) and nuclear magnetic resonance (NMR) of spin ensembles. This setup uses non-resonant stripline structures for on-chip microwave delivery and is demonstrated to work in the frequency range from 4 MHz to 18 GHz. π pulse times of 50 ns and 70 μs for ESR and NMR transitions, respectively, are achieved with as little as 100 mW of microwave or radiofrequency power. The use of adiabatic pulses fully compensates for the microwave magnetic field inhomogeneity of the stripline antennae, as demonstrated with the help of BIR4 unitary rotation pulses driving the ESR transition of neutral phosphorus donors in silicon and the NMR transitions of ionized phosphorus donors as detected by electron nuclear double resonance (ENDOR). PMID:25828243

  20. Electrical Excitation of the Acoustically Sensitive Auditory Nerve: Single-Fiber Responses to Electric Pulse Trains

    PubMed Central

    Abbas, Paul J.; Robinson, Barbara K.; Nourski, Kirill V.; Zhang, Fawen; Jeng, Fuh-Cherng

    2006-01-01

    Nearly all studies on auditory-nerve responses to electric stimuli have been conducted using chemically deafened animals so as to more realistically model the implanted human ear that has typically been profoundly deaf. However, clinical criteria for implantation have recently been relaxed. Ears with “residual” acoustic sensitivity are now being implanted, calling for the systematic evaluation of auditory-nerve responses to electric stimuli as well as combined electric and acoustic stimuli in acoustically sensitive ears. This article presents a systematic investigation of single-fiber responses to electric stimuli in acoustically sensitive ears. Responses to 250 pulse/s electric pulse trains were collected from 18 cats. Properties such as threshold, dynamic range, and jitter were found to differ from those of deaf ears. Other types of fiber activity observed in acoustically sensitive ears (i.e., spontaneous activity and electrophonic responses) were found to alter the temporal coding of electric stimuli. The electrophonic response, which was shown to greatly change the information encoded by spike intervals, also exhibited fast adaptation relative to that observed in the “direct” response to electric stimuli. More complex responses, such as “buildup” (increased responsiveness to successive pulses) and “bursting” (alternating periods of responsiveness and unresponsiveness) were observed. Our findings suggest that bursting is a response unique to sustained electric stimulation in ears with functional hair cells. PMID:16708257

  1. Active RF Pulse Compression Using An Electrically Controlled Semiconductor Switch

    SciTech Connect

    Guo, Jiquan; Tantawi, Sami; /SLAC

    2007-01-10

    First we review the theory of active pulse compression systems using resonant delay lines. Then we describe the design of an electrically controlled semiconductor active switch. The switch comprises an active window and an overmoded waveguide three-port network. The active window is based on a four-inch silicon wafer which has 960 PIN diodes. These are spatially combined in an overmoded waveguide. We describe the philosophy and design methodology for the three-port network and the active window. We then present the results of using this device to compress 11.4 GHz RF signals with high compression ratios. We show how the system can be used with amplifier like sources, in which one can change the phase of the source by manipulating the input to the source. We also show how the active switch can be used to compress a pulse from an oscillator like sources, which is not possible with passive pulse compression systems.

  2. Nanosecond electric pulses trigger actin responses in plant cells

    SciTech Connect

    Berghoefer, Thomas; Eing, Christian; Flickinger, Bianca; Hohenberger, Petra; Wegner, Lars H.; Frey, Wolfgang; Nick, Peter

    2009-09-25

    We have analyzed the cellular effects of nanosecond pulsed electrical fields on plant cells using fluorescently tagged marker lines in the tobacco cell line BY-2 and confocal laser scanning microscopy. We observe a disintegration of the cytoskeleton in the cell cortex, followed by contraction of actin filaments towards the nucleus, and disintegration of the nuclear envelope. These responses are accompanied by irreversible permeabilization of the plasma membrane manifest as uptake of Trypan Blue. By pretreatment with the actin-stabilizing drug phalloidin, the detachment of transvacuolar actin from the cell periphery can be suppressed, and this treatment can also suppress the irreversible perforation of the plasma membrane. We discuss these findings in terms of a model, where nanosecond pulsed electric fields trigger actin responses that are key events in the plant-specific form of programmed cell death.

  3. Controlled motion of electrically neutral microparticles by pulsed direct current

    PubMed Central

    Zhang, Xinfang; Qin, Rongshan

    2015-01-01

    A controlled motion of electrically neutral microparticles in a conductive liquid at high temperatures has not yet been realized under the uniform direct electric current field. We propose a simple method, which employs pulsed direct current to a conductive liquid metal containing low-conductivity objects at high temperature. The electric current enables the low-conductivity particles to pass from the centre towards the various surfaces of the high-conductivity liquid metal. Most interestingly, the directionality of microparticles can be controlled and their speed can be easily regulated by adjusting pulsed current density. We find that the movement may arise from the configuration of electrical domains which generates a driving force which exceeds the force of gravity and viscous friction. All of these features are of potential benefit in separating the particles of nearly equal density but distinctly different electrical conductivities, and also offer considerable promise for the precise and selective positioning of micro-objects or the controlled motion of minute quantities of surrounding fluids. PMID:25955864

  4. Pulsed electric field processing of foods: a review.

    PubMed

    Jeyamkondan, S; Jayas, D S; Holley, R A

    1999-09-01

    Use of pulsed electric fields (PEFs) for inactivation of microorganisms is one of the more promising nonthermal processing methods. Inactivation of microorganisms exposed to high-voltage PEFs is related to the electromechanical instability of the cell membrane. Electric field strength and treatment time are the two most important factors involved in PEF processing. Encouraging results are reported at the laboratory level, but scaling up to the industrial level escalates the cost of the command charging power supply and of the high-speed electrical switch. In this paper, we critically review the results of earlier experimental studies on PEFs and we suggest the future work that is required in this field. Inactivation tests in viscous foods and in liquid food containing particulates must be conducted. A successful continuous PEF processing system for industrial applications has yet to be designed. The high initial cost of setting up the PEF processing system is the major obstacle confronting those who would encourage the system's industrial application. Innovative developments in high-voltage pulse technology will reduce the cost of pulse generation and will make PEF processing competitive with thermal-processing methods. PMID:10492486

  5. Electrical properties of pulsed glow discharge Two new aspects

    NASA Astrophysics Data System (ADS)

    Efimova, V. V.; Voronov, M. V.; Hoffmann, V.; Eckert, J.

    2008-07-01

    At the application of pulsed glow discharge (PGD) a transient power of several kW can be reached. This leads to a significant increase of the excitation and ionization efficiency of the sputtered sample atoms. Moreover, with pulsed mode temporally resolved optical emission spectrometry (OES) and mass spectrometry (MS) deliver additional information about the chemical bonds (Harrison 1998, Bengtson et al. 2000, Hang et al. 1996, Klingler et al. 1990, Lewis et al. 2001, Jackson and King 2003). However, the practical application of pulsed glow discharge (PGD) requires an understanding of the processes taking place in the pulsed system. There are some publications, where attention was paid on the voltage current characteristics and the current signal shape of PGD (King and Pan 1993, Lewis et al. 2003). Nevertheless more attention should be paid on the electrical properties of the PGD. In this work the shapes of current, voltage and emission intensity signals, obtained with two different pulse generators are compared. For better understanding of processes, taking place in the discharge the knowledge of the gas temperature is very important. Several authors have mentioned that heating of the cathode leads to changes of the voltage current curve, mainly a decrease of the current at the same voltage. This can be explained by a lower gas density at the same pressure but at higher temperatures (Chenlong et al. 1999, Tian and Chu 2001, Kasik et al. 2002). This phenomenon gives an approach to estimate the gas temperature of the plasma.

  6. Pulsed electrical discharge in gas bubbles in water

    NASA Astrophysics Data System (ADS)

    Gershman, Sophia

    A phenomenological picture of pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying one microsecond long 5 to 20 kilovolt pulses between the needle and disk electrodes submerged in water. A gas bubble is generated at the tip of the needle electrode. The study includes detailed experimental investigation of the discharge in argon bubbles and a brief look at the discharge in oxygen bubbles. Imaging, electrical characteristics, and time-resolved optical emission data point to a fast streamer propagation mechanism and formation of a plasma channel in the bubble. Spectroscopic methods based on line intensity ratios and Boltzmann plots of line intensities of argon, atomic hydrogen, and argon ions and the examination of molecular emission bands from molecular nitrogen and hydroxyl radicals provide evidence of both fast beam-like electrons and slow thermalized ones with temperatures of 0.6 -- 0.8 electron-volts. The collisional nature of plasma at atmospheric pressure affects the decay rates of optical emission. Spectroscopic study of rotational-vibrational bands of hydroxyl radical and molecular nitrogen gives vibrational and rotational excitation temperatures of the discharge of about 0.9 and 0.1 electron-volt, respectively. Imaging and electrical evidence show that discharge charge is deposited on the bubble wall and water serves as a dielectric barrier for the field strength and time scales of this experiment. Comparing the electrical and imaging information for consecutive pulses applied at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from long-lived chemical species, such as ozone and oxygen. Intermediate values for the discharge gap and pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique

  7. Evaluation of pulse power devices in electric vehicle propulsion systems

    SciTech Connect

    Burke, A.F. ); Dowgiallo, E.J. )

    1990-01-01

    The application of pulse power devices in electric vehicle propulsion systems to load level the main energy storage battery has been studied. Both high energy density capacitors (ultracapacitors) and high power density, bipolar batteries are considered. Computer simulations of vehicle operation with hybrid (two power source) powertrains indicated the energy storage capacities of the pulse power devices required to load level the main battery are 300 to 500 Wh for the capacitors and 5 to 10 Ah for the bipolar batteries can be reduced from 79 W/kg to about 40 W/kg depending on the vehicle gradeability (speed, percent grade, and length of grade) desired. Evaluation of the status of the technology for the pulse power devices indicated that for both devices, improvements in technology are needed before the devices can be used in EV applications. In the case of the ultracapacitor, the energy density of present devices are 1 to 2 Wh/kg. A minimum energy density of about 5 Wh/kg is needed for electric vehicle applications. Progress in increasing the energy density of ultracapacitors has been rapid in recent years and the prospects for meeting the 5 Wh/kg requirement for EVs appear to be good. For bipolar batteries, a minimum power density of 500 W/kg is needed and the internal resistance must be reduced by about a factor of ten from that found in present designs.

  8. Nanosecond electric pulses deprive zinc ions of carboxypeptidase G2.

    PubMed

    Yu, Tinghe; Fu, Xiao

    2015-02-01

    Nanosecond electric pulses (nsEP, 10kV/cm with a pulse duration of 8, 16 or 24ns) inhibited the activity of carboxypeptidase G2 (CPG2), a zinc-dependent homodimer; the relative activity was <20% when the total exposure time was >120s. No alterations were detected in electrophoresis, chromatography, mass spectroscopy and circular dichroism, thus demonstrating intactness of the apoenzyme. Inductively coupled plasma-mass spectrometry indicated that zinc levels were 3.30μg/mg protein in control CPG2, and decreased to 0.40, 0.12 or 0.38μg/mg protein after 240s of 8-, 16- or 24-ns pulses, respectively. In CPG2 exposed to 240s of 8-, 16- and 24-ns pulses, the reloading of zinc with redialysis recovered the activity to 94.7±3.4%, 84.0±5.2% and 81.7±7.0%, respectively (p=0.0853, 0.0741, 0.0668). These data demonstrated that nsEP inhibited CPG2 via removal of zinc, and that nsEP can be used to modulate CPG2. PMID:25049063

  9. Considering effects of nanosecond pulsed electric fields on proteins.

    PubMed

    Beebe, Stephen J

    2015-06-01

    Most, if not all, effects of intense, pulsed electric fields are analyzed in terms of electrical charging of plasma membranes and/or subcellular membranes. However, not all cell responses from nanosecond pulsed electric fields (nsPEFs) are fully explained by poration of cell membranes. Observations that nsPEFs induce a Ca2-dependent dissipation of the mitochondria membrane potential (ΔΨm), which is enhanced when high frequency components are present in fast rise-fall waveforms, are not compatible with a poration event. Ca(2+) is shown to have little or no effect on propidium iodide uptake as a measure of plasma membrane poration and consequently intracellular membranes. Since most if not all Ca(2+)-regulated events are mediated by proteins, actions of nsPEFs on a protein(s) that regulate and/or affect the mitochondria membrane potential are possible. To show that nsPEFs can directly affect proteins, nsPEFs non-thermally inactivated the catalytic (phosphotransferase) activity of the catalytic subunit of the cAMP-dependent protein kinase, which is the prototype of the protein kinase superfamily that share a common catalytic mechanism and whose functions are highly dependent on their structure. These studies present indirect and direct evidences that nsPEFs can affect proteins and their functions, at least in part, by affecting their structure. PMID:25218277

  10. High-Voltage Pulsed Current Electrical Stimulation in Wound Treatment

    PubMed Central

    Polak, Anna; Franek, Andrzej; Taradaj, Jakub

    2014-01-01

    Significance: A range of studies point to the efficacy of electrical stimulation (ES) in wound treatment, but the methodology of its application has not been determined to date. This article provides a critical review of the results of clinical trials published by researchers using high-voltage pulsed current (HVPC) to treat chronic wounds. In describing the methodology of the trials, the article gives special attention to electric stimulus parameters, the frequency of procedures and total treatment duration. Recent Advances: HVPC is a monophasic pulsed electric current that consists of double-peaked impulses (5–200 μs), at very high peak-current amplitude (2–2.5 A), and high voltage (up to 500 V), at a frequency of 1–125 pulses per second. HVPC can activate “skin battery” and cellular galvanotaxis, and improves blood flow and capillary density. Critical Issues: HVPC efficacy was evaluated in conservatively treated patients with diabetic foot, venous leg and pressure ulcers (PUs), and in some patients with surgically treated venous insufficiency. Future Directions: The efficacy of HVPC as one of several biophysical energies promoting venous leg ulcer (VLU) and PU healing has been confirmed. Additional studies are needed to investigate its effect on the healing of other types of soft tissue defects. Other areas that require more research include the identification of the therapeutic effect of HVPC on infected wounds, the determination of the efficacy of cathodal versus anodal stimulation, and the minimal daily/weekly duration of HVPC required to ensure optimal promotion of wound healing. PMID:24761351

  11. High-Voltage Pulsed Current Electrical Stimulation in Wound Treatment.

    PubMed

    Polak, Anna; Franek, Andrzej; Taradaj, Jakub

    2014-02-01

    Significance: A range of studies point to the efficacy of electrical stimulation (ES) in wound treatment, but the methodology of its application has not been determined to date. This article provides a critical review of the results of clinical trials published by researchers using high-voltage pulsed current (HVPC) to treat chronic wounds. In describing the methodology of the trials, the article gives special attention to electric stimulus parameters, the frequency of procedures and total treatment duration. Recent Advances: HVPC is a monophasic pulsed electric current that consists of double-peaked impulses (5-200 μs), at very high peak-current amplitude (2-2.5 A), and high voltage (up to 500 V), at a frequency of 1-125 pulses per second. HVPC can activate "skin battery" and cellular galvanotaxis, and improves blood flow and capillary density. Critical Issues: HVPC efficacy was evaluated in conservatively treated patients with diabetic foot, venous leg and pressure ulcers (PUs), and in some patients with surgically treated venous insufficiency. Future Directions: The efficacy of HVPC as one of several biophysical energies promoting venous leg ulcer (VLU) and PU healing has been confirmed. Additional studies are needed to investigate its effect on the healing of other types of soft tissue defects. Other areas that require more research include the identification of the therapeutic effect of HVPC on infected wounds, the determination of the efficacy of cathodal versus anodal stimulation, and the minimal daily/weekly duration of HVPC required to ensure optimal promotion of wound healing. PMID:24761351

  12. Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields

    PubMed Central

    Xie, Fei; Varghese, Frency; Pakhomov, Andrei G.; Semenov, Iurii; Xiao, Shu; Philpott, Jonathan; Zemlin, Christian

    2015-01-01

    Background Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations. Methods We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume. Results In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters. Conclusions Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation. PMID:26658139

  13. Electrical characterization of a Mapham inverter using pulse testing techniques

    NASA Technical Reports Server (NTRS)

    Baumann, E. D.; Myers, I. T.; Hammond, A. N.

    1990-01-01

    Electric power requirements for aerospace missions have reached megawatt power levels. Within the next few decades, it is anticipated that a manned lunar base, interplanetary travel, and surface exploration of the Martian surface will become reality. Several research and development projects aimed at demonstrating megawatt power level converters for space applications are currently underway at the NASA Lewis Research Center. Innovative testing techniques will be required to evaluate the components and converters, when developed, at their rated power in the absence of costly power sources, loads, and cooling systems. Facilities capable of testing these components and systems at full power are available, but their use may be cost prohibitive. The use of a multiple pulse testing technique is proposed to determine the electrical characteristics of large megawatt level power systems. Characterization of a Mapham inverter is made using the proposed technique and conclusions are drawn concerning its suitability as an experimental tool to evaluate megawatt level power systems.

  14. Impact of nanosecond pulsed electric fields on primary hippocampal neurons

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Payne, Jason A.; Kuipers, Marjorie A.; Thompson, Gary L.; Wilmink, Gerald J.; Ibey, Bennett L.

    2012-02-01

    Cellular exposure to nanosecond pulsed electric fields (nsPEF) are believed to cause immediate creation of nanopores in the plasma membrane. These nanopores enable passage of small ions, but remain impermeable to larger molecules like propidium iodide. Previous work has shown that nanopores are stable for minutes after exposure, suggesting that formation of nanopores in excitable cells could lead to prolonged action potential inhibition. Previously, we measured the formation of nanopores in neuroblastoma cells by measuring the influx of extracellular calcium by preloading cells with Calcium Green-AM. In this work, we explored the impact of changing the width of a single nsPEF, at constant amplitude, on uptake of extracellular calcium ions by primary hippocampal neurons (PHN). Calcium Green was again used to measure the influx of extracellular calcium and FM1-43 was used to monitor changes in membrane conformation. The observed thresholds for nanopore formation in PHN by nsPEF were comparable to those measured in neuroblastoma. This work is the first study of nsPEF effects on PHN and strongly suggests that neurological inhibition by nanosecond electrical pulses is highly likely at doses well below irreversible damage.

  15. Electrical noise modulates perception of electrical pulses in humans: sensation enhancement via stochastic resonance.

    PubMed

    Iliopoulos, Fivos; Nierhaus, Till; Villringer, Arno

    2014-03-01

    Although noise is usually considered to be harmful for signal detection and information transmission, stochastic resonance (SR) describes the counterintuitive phenomenon of noise enhancing the detection and transmission of weak input signals. In mammalian sensory systems, SR-related phenomena may arise both in the peripheral and the central nervous system. Here, we investigate behavioral SR effects of subliminal electrical noise stimulation on the perception of somatosensory stimuli in humans. We compare the likelihood to detect near-threshold pulses of different intensities applied on the left index finger during presence vs. absence of subliminal noise on the same or an adjacent finger. We show that (low-pass) noise can enhance signal detection when applied on the same finger. This enhancement is strong for near-threshold pulses below the 50% detection threshold and becomes stronger when near-threshold pulses are applied as brief trains. The effect reverses at pulse intensities above threshold, especially when noise is replaced by subliminal sinusoidal stimulation, arguing for a peripheral direct current addition. Unfiltered noise applied on longer pulses enhances detection of all pulse intensities. Noise applied to an adjacent finger has two opposing effects: an inhibiting effect (presumably due to lateral inhibition) and an enhancing effect (most likely due to SR in the central nervous system). In summary, we demonstrate that subliminal noise can significantly modulate detection performance of near-threshold stimuli. Our results indicate SR effects in the peripheral and central nervous system. PMID:24353303

  16. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    It is advantageous for gas-fed pulsed electric thrusters to employ pulsed valves so propellant is only flowing to the device during operation. The propellant utilization of the thruster will be maximized when all the gas injected into the thruster is acted upon by the fields produced by the electrical pulse. Gas that is injected too early will diffuse away from the thruster before the electrical pulse can act to accelerate the propellant. Gas that is injected too late will miss being accelerated by the already-completed electrical pulse. As a consequence, the valve must open quickly and close equally quickly, only remaining open for a short duration. In addition, the valve must have only a small amount of volume between the sealing body and the thruster so the front and back ends of the pulse are as coincident as possible with the valve cycling, with very little latent propellant remaining in the feed lines after the valve is closed. For a real mission of interest, a pulsed thruster can be expected to pulse at least 10(exp 10) - 10(exp 11) times, setting the range for the number of times a valve must open and close. The valves described in this paper have been fabricated and tested for operation in an inductive pulsed plasma thruster (IPPT) for in-space propulsion. In general, an IPPT is an electrodeless space propulsion device where a capacitor is charged to an initial voltage and then discharged, producing a high-current pulse through a coil. The field produced by this pulse ionizes propellant, inductively driving current in a plasma located near the face of the coil. Once the plasma is formed, it can be accelerated and expelled at a high exhaust velocity by the electromagnetic Lorentz body force arising from the interaction of the induced plasma current and the magnetic field produced by the current in the coil. The valve characteristics needed for the IPPT application require a fast-acting valve capable of a minimum of 10(exp 10) valve actuation cycles. Since

  17. Optical pulse compression reflectometry based on single-sideband modulator driven by electrical frequency-modulated pulse

    NASA Astrophysics Data System (ADS)

    Zou, Weiwen; Yu, Lei; Yang, Shuo; Chen, Jianping

    2016-05-01

    We propose a novel scheme to generate a linear frequency-modulated optical pulse with high extinction ratio based on an electrical frequency-modulated pulse and optical single-sideband modulator. This scheme is proved to improve the stability and accuracy of optical pulse compression reflectometry (OPCR). In the experiment, a high spatial resolution of 10 cm and a long measurement range of 10.8 km using a laser source with 2-km coherence length are demonstrated.

  18. Numerical simulation of nanosecond-pulse electrical discharges

    NASA Astrophysics Data System (ADS)

    Poggie, J.; Adamovich, I.; Bisek, N.; Nishihara, M.

    2013-02-01

    Recent experiments with a nanosecond-pulse, dielectric barrier discharge at the stagnation point of a Mach 5 cylinder flow have demonstrated the formation of weak shock waves near the electrode edge, which propagate upstream and perturb the bow shock. This is a promising means of flow control, and understanding the detailed physics of the conversion of electrical energy into gas motion will aid in the design of efficient actuators based on the concept. In this work, a simplified configuration with planar symmetry was chosen as a vehicle to develop a physics-based model of nanosecond-pulse discharges, including realistic air kinetics, electron energy transport, and compressible bulk gas flow. A reduced plasma kinetic model (23 species and 50 processes) was developed to capture the dominant species and reactions for energy storage and thermalization in the discharge. The kinetic model included electronically and vibrationally excited species, and several species of ions and ground state neutrals. The governing equations included the Poisson equation for the electric potential, diffusion equations for each neutral species, conservation equations for each charged species, and mass-averaged conservation equations for the bulk gas flow. The results of calculations with this model highlighted the path of energy transfer in the discharge. At breakdown, the input electrical energy was transformed over a time scale on the order of 1 ns into chemical energy of ions, dissociation products, and vibrationally and electronically excited particles. About 30% of this energy was subsequently thermalized over a time scale of 10 µs. Since the thermalization time scale was faster than the acoustic time scale, the heat release led to the formation of weak shock waves originating near the sheath edge, consistent with experimental observations. The computed translational temperature rise (40 K) and nitrogen vibrational temperature rise (370 K) were of the same order of magnitude as

  19. Locating initial breakdown pulses using electric field change network

    NASA Astrophysics Data System (ADS)

    Karunarathne, Sumedhe; Marshall, Thomas C.; Stolzenburg, Maribeth; Karunarathna, Nadeeka; Vickers, Lauren E.; Warner, Tom A.; Orville, Richard E.

    2013-07-01

    Initial breakdown pulses (IBPs) observed in the fast electric field change (E-change) at the beginning of intracloud (IC) and cloud-to-ground (CG) lightning flashes are located using a time-of-arrival technique called Position By Fast Antenna (PBFA) with data from a network of 10 E-change sensors located at Kennedy Space Center. Location errors, estimated using a Monte Carlo method, are usually less than 100 m for horizontal coordinates and several hundreds of meters for altitude, depending on distance to the sensors and altitude of the source. Comparison of PBFA source locations to locations from a VHF lightning mapping system (Lightning Detection and Ranging II (LDAR2)) shows that PBFA locates most of the "classic" IBPs while LDAR2 locates only a few percent of them. As the flash develops during the IB stage, PBFA and LDAR2 obtain similar locations when they detect the same IBPs. The overall vertical motion indicated by the PBFA positions of IBPs was downward with time for CG flashes and upward with time for IC flashes. Location of the fast pulses due to return strokes of CG flashes is also determined using PBFA. Comparison to locations from the Cloud-to-Ground Lightning Surveillance System (CGLSS) shows that PBFA reliably locates ground strokes. These results are verified using ground truth data acquired with a high-speed video camera. After cross calibration with the CGLSS data set, peak currents of return strokes are also determined.

  20. Effects of nanosecond pulse electric fields on cellular elasticity.

    PubMed

    Dutta, Diganta; Asmar, Anthony; Stacey, Michael

    2015-05-01

    We investigated the effects of a single 60 nanosecond pulsed electric field (nsPEF) of low (15 kV/cm) and high (60 kV/cm) field strengths on cellular morphology and membrane elasticity in Jurkat cells using fluorescent microscopy and atomic force microscopy (AFM). We performed force displacement measurements on cells using AFM and calculated the Young's modulus for membrane elasticity. Differential effects were observed depending upon pulsing conditions. We found that a single nsPEF of low field strength did not induce any apparent cytoskeletal breakdown and had minor morphological changes. Interestingly, force measurements and calculation of Young's modulus showed a significant decrease in membrane elasticity. A single nsPEF of high field strength induced stark morphological changes due to disruption of the actin cytoskeleton and a marked decrease in elasticity likely caused by irreversible membrane damage. We suggest that the cellular morphology is mainly dependent on stabilization by the actin cytoskeleton, while the elasticity changes are partially dependent on the cytoskeletal integrity. PMID:25732004

  1. Electrical and hydrodynamic characterization of a high current pulsed arc

    NASA Astrophysics Data System (ADS)

    Sousa Martins, R.; Chemartin, L.; Zaepffel, C.; Lalande, Ph; Soufiani, A.

    2016-05-01

    High current pulsed arcs are of significant industrial interest and, aiming to reduce time and cost, there is progressively more and more need for computation tools that describe and predict the behaviour of these arcs. These simulation codes need inputs and validations by experimental databases, but accurate data is missing for this category of electric discharges. The principal lack of understanding is with respect to the transient phase of the current, which can reach thousands of amperes in a few microseconds. In this paper, we present the work realized on an experimental setup that simulates in the laboratory an arc column subjected to five levels of high pulsed current, ranging from 10 kA to 100 kA, with the last one corresponding to the standard lightning current waveform used in aircraft certification processes. This device was instrumented by high speed video cameras to assess the characteristic sizes of the arc channel and to characterize the shock wave generated by the arc expansion. The arc channel radius was measured over time during the axisymmetric phase and reached 3.2 cm. The position and velocity of the shock wave was determined during the first 140 μs. The background-oriented schlieren method was used to study the shock wave and a model for the light deflection inside the shock wave was developed. The mass density profile of the shock wave was estimated and showed good agreement with Rankine–Hugoniot relations at the wave front. Electrical measurements were also used to estimate the time-dependent resistance and conductivity of the arc for times lasting up to 50 μs.

  2. Transient electrical field across cellular membranes: pulsed electric field treatment of microbial cells

    NASA Astrophysics Data System (ADS)

    Timoshkin, I. V.; MacGregor, S. J.; Fouracre, R. A.; Crichton, B. H.; Anderson, J. G.

    2006-02-01

    The pulsed electric field (PEF) treatment of liquid and pumpable products contaminated with microorganisms has attracted significant interest from the pulsed power and bioscience research communities particularly because the inactivation mechanism is non-thermal, thereby allowing retention of the original nutritional and flavour characteristics of the product. Although the biological effects of PEF have been studied for several decades, the physical mechanisms of the interaction of the fields with microorganisms is still not fully understood. The present work is a study of the dynamics of the electrical field both in a PEF treatment chamber with dielectric barriers and in the plasma (cell) membrane of a microbial cell. It is shown that the transient process can be divided into three physical phases, and models for these phases are proposed and briefly discussed. The complete dynamics of the time development of the electric field in a spherical dielectric shell representing the cellular membrane is then obtained using an analytical solution of the Ohmic conduction problem. It was found that the field in the membrane reaches a maximum value that could be two orders of magnitude higher than the original Laplacian electrical field in the chamber, and this value was attained in a time comparable to the field relaxation time in the chamber. Thus, the optimal duration of the field during PEF treatment should be equal to such a time.

  3. Conductivity affects nanosecond electrical pulse induced pressure transient formation

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Glickman, Randolph D.

    2016-03-01

    Nanoporation occurs in cells exposed to high amplitude short duration (< 1μs) electrical pulses. The biophysical mechanism(s) responsible for nanoporation is unknown although several theories exist. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. Our group has shown that mechanical forces of substantial magnitude are also generated during nsEP exposures. We hypothesize that these mechanical forces may contribute to pore formation. In this paper, we report that alteration of the conductivity of the exposure solution also altered the level of mechanical forces generated during a nsEP exposure. By reducing the conductivity of the exposure solutions, we found that we could completely eliminate any pressure transients normally created by nsEP exposure. The data collected for this proceeding does not definitively show that the pressure transients previously identified contribute to nanoporation; however; it indicates that conductivity influences both survival and pressure transient formation.

  4. Improving Carotenoid Extraction from Tomato Waste by Pulsed Electric Fields

    PubMed Central

    Luengo, Elisa; Álvarez, Ignacio; Raso, Javier

    2014-01-01

    In this investigation, the influence of the application of pulsed electric fields (PEFs) of different intensities (3–7 kV/cm and 0–300 μs) on the carotenoid extraction from tomato peel and pulp in a mixture of hexane:acetone:ethanol was studied with the aim of increasing extraction yield or reducing the percentage of the less green solvents in the extraction medium. According to the cellular disintegration index, the optimum treatment time for the permeabilization of tomato peel and pulp at different electric field strengths was 90 μs. The PEF permeabilization of tomato pulp did not significantly increase the carotenoid extraction. However, a PEF treatment at 5 kV/cm improved the carotenoid extraction from tomato peel by 39% as compared with the control in a mixture of hexane:ethanol:acetone (50:25:25). Further increments of electric field from 5 to 7 kV/cm did not increase significantly the extraction of carotenoids. The presence of acetone in the solvent mixture did not positively affect the carotenoid extraction when the tomato peels were PEF-treated. Response surface methodology was used to determine the potential of PEF for reducing the percentage of hexane in a hexane:ethanol mixture. The application of a PEF treatment allowed reducing the hexane percentage from 45 to 30% without affecting the carotenoid extraction yield. The antioxidant capacity of the extracts obtained from tomato peel was correlated with the carotenoid concentration and it was not affected by the PEF treatment. PMID:25988115

  5. Ultrawideband monocycle pulse generation based on polarization modulator and low speed electrical NRZ signal

    NASA Astrophysics Data System (ADS)

    Sun, Guodan; Zhang, Qiufang; Wang, Quan

    2015-07-01

    A novel ultrawideband (UWB) monocycle pulse generation system by modulating a polarization modulator (PolM) with a low speed electrical nonreturn-to-zero (NRZ) signal is proposed, which significantly reduce the bandwidth requirement of the driving signal. At each bit transition of the input NRZ signal, two polarity-reversed Gaussian pulses are generated. By properly setting the delay between these two Gaussian pulses, an optical UWB monocycle pulse can be generated. Biphase modulation (BPM) can be realized by electrically switching the polarization direction at the output of PolM, if an electrically tunable arbitrary wave plate (AWP) is employed.

  6. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    The design and test results for two types of pulsed gas valves are presented. The valves, a piezo valve and a solenoid actuated valve, must have exceedingly long lifetime to support gas-fed pulsed electric thruster operation for missions of interest. The performance of both valves was tested, with both demonstrating the capability to throttle the gas flow rate while maintaining low leakage levels below 10(exp -3) sccs of He at the beginning of valve lifetime. The piezo valve varies the flow rate by changing the amount that the valve is open, which is a function of applied voltage. This valve demonstrated continuous throttlability from 0-10 mL/s, with opening and closing times of 100 microsecond or less. The solenoid actuated valve flow rate changes as a function of the inlet gas pressure, with demonstrated flow rates in these tests from 2.7-11 mL per second. The valve response time is slower than the piezo valve, opening in 1-2 ms and closing in several ms. The solenoid actuated valve was tested to one million cycles, with the valve performance remaining relatively unchanged throughout the test. Galling of the sliding plunger caused the valve to bind and fail just after one million cycles, but at this point in the test the valve sealing surface leak rate still appeared to be well below the maximum target leak rake of 1×10(exp -3) sccs of He.

  7. A physics-based model of the electric field pulses occurring during the lightning initiation

    NASA Astrophysics Data System (ADS)

    Kaspar, Petr; Santolik, Ondrej; Kolmasova, Ivana

    2016-04-01

    We investigate properties of the electric field pulses observed during the lightning initiation using a generalization of electrostatic and transmission-line models. In the model, the initial leader has a finite conductivity, the current in the channel is inducted owing to an ambient field generated by charge structure inside a thundercloud, and the electric field is computed by a formula derived from exact solution of the Maxwell's equations for a given inducted current. We show how the shape of electric field waveform of individual pulses depends on various parameters of the model with an emphasis on the thundercloud charge structure. We generalize the model to include sequences of several electric field pulses. We show how the peak current pulse is related to the preliminary breakdown electric field peak pulse and we compare this estimation with observations.

  8. Modular Pulsed Plasma Electric Propulsion System for Cubesats

    NASA Technical Reports Server (NTRS)

    Perez, Andres Dono; Gazulla, Oriol Tintore; Teel, George Lewis; Mai, Nghia; Lukas, Joseph; Haque, Sumadra; Uribe, Eddie; Keidar, Michael; Agasid, Elwood

    2014-01-01

    Current capabilities of CubeSats must be improved in order to perform more ambitious missions. Electric propulsion systems will play a key role due to their large specific impulse. Compared to other propulsion alternatives, their simplicity allows an easier miniaturization and manufacturing of autonomous modules into the nano and pico-satellite platform. Pulsed Plasma Thrusters (PPTs) appear as one of the most promising technologies for the near term. The utilization of solid and non-volatile propellants, their low power requirements and their proven reliability in the large scale make them great candidates for rapid implementation. The main challenges are the integration and miniaturization of all the electronic circuitry into a printed circuit board (PCB) that can satisfy the strict requirements that CubeSats present. NASA Ames and the George Washington University have demonstrated functionality and control of three discrete Micro-Cathode Arc Thrusters (CAT) using a bench top configuration that was compatible with the ARC PhoneSat Bus. This demonstration was successfully conducted in a vaccum chamber at the ARC Environmental Test Laboratory. A new effort will integrate a low power Plasma Processing Unit and two plasma thrusters onto a single printed circuit board that will utilize less than 13 U of Bus volume. The target design will be optimized for the accommodation into the PhoneSatEDISON Demonstration of SmallSatellite Networks (EDSN) bus as it uses the same software interface application, which was demonstrated in the previous task. This paper describes the design, integration and architecture of the proposed propulsion subsystem for a planned Technology Demonstration Mission. In addition, a general review of the Pulsed Plasma technology available for CubeSats is presented in order to assess the necessary challenges to overcome further development.

  9. Generation of an ultra-short electrical pulse with width shorter than the excitation laser.

    PubMed

    Shi, Wei; Wang, Shaoqiang; Ma, Cheng; Xu, Ming

    2016-01-01

    We demonstrate experimentally a rare phenomenon that the width of an electrical response is shorter than that of the excitation laser. In this work, generation of an ultrashort electrical pulse is by a semi-insulating GaAs photoconductive semiconductor switch (PCSS) and the generated electrical pulse width is shorter than that of the excitation laser from diode laser. When the pulse width and energy of the excitation laser are fixed at 25.7 ns and 1.6 μJ respectively, the width of the generated electrical pulse width by 3-mm-gap GaAs PCSS at the bias voltage of 9 kV is only 7.3 ns. The model of photon-activated charge domain (PACD) is used to explain the peculiar phenomenon in our experiment. The ultrashort electrical pulse width is mainly relevant to the time interval of PACD from occurrence to disappearance in the mode. The shorter the time interval is, the narrower the electrical pulse width will become. In more general terms, our result suggests that in nonlinear regime a response signal can have a much short width than the excitation pulses. The result clearly indicates that generating ultrashort electrical pulses can be achieved without the need of ultrashort lasers. PMID:27273512

  10. Generation of an ultra-short electrical pulse with width shorter than the excitation laser

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Wang, Shaoqiang; Ma, Cheng; Xu, Ming

    2016-06-01

    We demonstrate experimentally a rare phenomenon that the width of an electrical response is shorter than that of the excitation laser. In this work, generation of an ultrashort electrical pulse is by a semi-insulating GaAs photoconductive semiconductor switch (PCSS) and the generated electrical pulse width is shorter than that of the excitation laser from diode laser. When the pulse width and energy of the excitation laser are fixed at 25.7 ns and 1.6 μJ respectively, the width of the generated electrical pulse width by 3-mm-gap GaAs PCSS at the bias voltage of 9 kV is only 7.3 ns. The model of photon-activated charge domain (PACD) is used to explain the peculiar phenomenon in our experiment. The ultrashort electrical pulse width is mainly relevant to the time interval of PACD from occurrence to disappearance in the mode. The shorter the time interval is, the narrower the electrical pulse width will become. In more general terms, our result suggests that in nonlinear regime a response signal can have a much short width than the excitation pulses. The result clearly indicates that generating ultrashort electrical pulses can be achieved without the need of ultrashort lasers.

  11. Generation of an ultra-short electrical pulse with width shorter than the excitation laser

    PubMed Central

    Shi, Wei; Wang, Shaoqiang; Ma, Cheng; Xu, Ming

    2016-01-01

    We demonstrate experimentally a rare phenomenon that the width of an electrical response is shorter than that of the excitation laser. In this work, generation of an ultrashort electrical pulse is by a semi-insulating GaAs photoconductive semiconductor switch (PCSS) and the generated electrical pulse width is shorter than that of the excitation laser from diode laser. When the pulse width and energy of the excitation laser are fixed at 25.7 ns and 1.6 μJ respectively, the width of the generated electrical pulse width by 3-mm-gap GaAs PCSS at the bias voltage of 9 kV is only 7.3 ns. The model of photon-activated charge domain (PACD) is used to explain the peculiar phenomenon in our experiment. The ultrashort electrical pulse width is mainly relevant to the time interval of PACD from occurrence to disappearance in the mode. The shorter the time interval is, the narrower the electrical pulse width will become. In more general terms, our result suggests that in nonlinear regime a response signal can have a much short width than the excitation pulses. The result clearly indicates that generating ultrashort electrical pulses can be achieved without the need of ultrashort lasers. PMID:27273512

  12. Membrane potential perturbations induced in tissue cells by pulsed electric fields

    SciTech Connect

    Cooper, M.S.

    1995-09-01

    Pulsed electric fields directly influence the electrophysiology of tissue cells by transiently perturbing their transmembrane potential. To determine the magnitude and time course of this interaction, electronic cable theory was used to calculate the membrane potential perturbations induced in tissue cells by a spatially uniform, pulsed electric field. Analytic solutions were obtained that predict shifts in membrane potential along the length of cells as a function of time in response to an electrical pulse. For elongated tissue cells, or groups of tissue cells that are couple electronically by gap junctions, significant hyperpolarizations and depolarizations can result form millisecond applications of electric fields with strengths on the order of 10--100 mV/cm. The results illustrate the importance of considering cellular cable parameters in assessing the effects of transient electric fields on biological systems, as well as in predicting the efficacy of pulsed electric fields in medical treatments.

  13. Cell stimulation and calcium mobilization by picosecond electric pulses.

    PubMed

    Semenov, Iurii; Xiao, Shu; Kang, Dongkoo; Schoenbach, Karl H; Pakhomov, Andrei G

    2015-10-01

    We tested if picosecond electric pulses (psEP; 190 kV/cm, 500 ps at 50% height), which are much shorter than channel activation time, can activate voltage-gated (VG) channels. Cytosolic Ca(2+) was monitored by Fura-2 ratiometric imaging in GH3 and NG108 cells (which express multiple types of VG calcium channels, VGCC), and in CHO cells (which express no VGCC). Trains of up to 100 psEP at 1 kHz elicited no response in CHO cells. However, even a single psEP significantly increased Ca(2+) in both GH3 (by 114 ± 48 nM) and NG108 cells (by 6 ± 1.1 nM). Trains of 100 psEP amplified the response to 379 ± 33 nM and 719 ± 315 nM, respectively. Ca(2+) responses peaked within 2-15s and recovered for over 100 s; they were 80-100% inhibited by verapamil and ω-conotoxin, but not by the substitution of Na(+) with N-methyl-D-glucamine. There was no response to psEP in Ca(2+)-free medium, but adding external Ca(2+) even 10s later evoked Ca(2+) response. We conclude that electrical stimuli as short as 500 ps can cause long-lasting opening of VGCC by a mechanism which does not involve conventional electroporation, heating (which was under 0.06 K per psEP), or membrane depolarization by opening of VG Na(+) channels. PMID:26011130

  14. Model for electron detachment from negative ions by ultrashort half-cycle electric-field pulses

    NASA Astrophysics Data System (ADS)

    Grozdanov, T. P.; Jaćimović, J.

    2009-01-01

    We study a model for electron detachment from negative ions by ultrashort unipolar electric pulses. The electron-atom interaction is described by the zero-range potential and the temporal dependence of the electric field is approximated by the Dirac δ functions. The case of a single pulse can be treated semianalytically and explicit expressions are obtained for momentum and energy distributions of detached electrons as well as for the total detachment probability. The determination of angular distribution involves numerical evaluation of a one-dimensional integral. The case of two alternating electric pulses requires numerical evaluation of more complicated integrals but leads to interesting effects caused by the quantum interference of the electronic wave packets produced during the interactions with the first and the second pulses. The differential and integral detachment probabilities are calculated and discussed for a variety of pulse strengths and time delays between the pulses.

  15. Method and apparatus for electrical cable testing by pulse-arrested spark discharge

    DOEpatents

    Barnum, John R.; Warne, Larry K.; Jorgenson, Roy E.; Schneider, Larry X.

    2005-02-08

    A method for electrical cable testing by Pulse-Arrested Spark Discharge (PASD) uses the cable response to a short-duration high-voltage incident pulse to determine the location of an electrical breakdown that occurs at a defect site in the cable. The apparatus for cable testing by PASD includes a pulser for generating the short-duration high-voltage incident pulse, at least one diagnostic sensor to detect the incident pulse and the breakdown-induced reflected and/or transmitted pulses propagating from the electrical breakdown at the defect site, and a transient recorder to record the cable response. The method and apparatus are particularly useful to determine the location of defect sites in critical but inaccessible electrical cabling systems in aging aircraft, ships, nuclear power plants, and industrial complexes.

  16. Short pulse generation from a flashlamp-pumped rhodamine 6G ring dye laser using the colliding pulse mode-locking technique

    SciTech Connect

    Singh, S.

    1987-01-01

    The colliding pulse mode-locking (CPM) technique has been applied to a flashlamp-pumped rhodamine 6G dye laser to reliably generate pulses of <1.5 ps. Pulse evolution in the ring cavity has been studied by examining the pulse characteristics at various parts of the pulse train using a Photochron II streak camera. The measured pulse durations in the ring cavity were found to be detector-limited and were shorter than those generated in a linear cavity. The shortest pulses were observed to evolve toward the end of the --600-ns long mode-locked train.

  17. Effect of electric pulse processing on physical and chemical properties of inorganic materials

    NASA Astrophysics Data System (ADS)

    Sakipova, S. E.; Nussupbekov, B. R.; Ospanova, D.; Khassenov, A.; Sakipova, Sh E.

    2015-04-01

    This article analyzes various aspects of the practical application of electric pulse technology of industrial raw materials processing as a result of a spark electric discharge in a liquid solution of the raw material under processing. The object of the study are samples of technogenic materials from a deposit in Central Kazakhstan, which are crushed and ground to particles with a preset degree of fragmentation. The electric pulse processing is performed by using different numbers of discharges. The effect of electric pulse processing with different electrical parameters is carried out on the basis of comparison of the properties and structure of metal-containing and industrial raw materials after machining and electric pulse processing. The X-ray spectral microanalysis was performed using a scanning microscope. The researchers obtained data on changes in the microstructure and elemental composition of inorganic material samples as a result of electric pulse processing. It was established that the technology of electric pulse crushing and grinding of inorganic materials makes it possible to obtain not only a final product with desired size of dispersed particles, but also to change their physical and chemical properties.

  18. Assessment of the electrochemical effects of pulsed electric fields in a biological cell suspension.

    PubMed

    Chafai, Djamel Eddine; Mehle, Andraž; Tilmatine, Amar; Maouche, Bachir; Miklavčič, Damijan

    2015-12-01

    Electroporation of cells is successfully used in biology, biotechnology and medicine. Practical problems still arise in the electroporation of cells in suspension. For example, the determination of cell electroporation is still a demanding and time-consuming task. Electric pulses also cause contamination of the solution by the metal released from the electrodes and create local enhancements of the electric field, leading to the occurrence of electrochemical reactions at the electrode/electrolyte interface. In our study, we investigated the possibility of assessing modifications to the cell environment caused by pulsed electric fields using electrochemical impedance spectroscopy. We designed an experimental protocol to elucidate the mechanism by which a pulsed electric field affects the electrode state in relation to different electrolyte conductivities at the interface. The results show that a pulsed electric field affects electrodes and its degree depends on the electrolyte conductivity. Evolution of the electrochemical reaction rate depends on the initial free charges and those generated by the pulsed electric field. In the presence of biological cells, the initial free charges in the medium are reduced. The electrical current path at low frequency is longer, i.e., conductivity is decreased, even in the presence of increased permeability of the cell membrane created by the pulsed electric field. PMID:26315352

  19. Optical controling dynamic and fluctuation processes in ensemble of neurons at pulsed electrical excitation ex vivo

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Seliverstov, George A.; Akchurin, Alexander G.; Akchurin, George G.

    2004-05-01

    Dynamic response of the somatic frog nerve on electrical pulsed excitation was investigated ex vivo. Strong fluctuation of consequence compound action potential in ensemble of neurons near-threshold was discovered. The nonlinear response of the Hodgkin-Huxley model neurons with external electrical pulsed was investigated and numeral results correlation with experiments. Complex dynamic of compound action potential was discovered when on-line time of stimulatory electrical pulses comparable with nerve refractory period. New techniques research nonlinear behavior using photodynamic reactions or UV-A radiation at somatic frog nerve was approved. This nonlinear dynamic regime was controlling laser induced inactivation of processes in membrane of nerve.

  20. Nanosecond pulsed electric fields and the cell cycle

    NASA Astrophysics Data System (ADS)

    Mahlke, Megan A.

    Exposure to nanosecond pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. The phase of the cell cycle at the time of exposure is linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Additionally, nsPEFs are capable of activating cell cycle checkpoints, which could lead to apoptosis or slow population growth. NsPEFs are emerging as a method for treating tumors via apoptotic induction; therefore, investigating the relevance of nsPEFs and the cell cycle could translate into improved efficacy in tumor treatment. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate the role of cell cycle phase in survival of nsPEFs. CHO populations appeared similar to sham populations post-nsPEFs but exhibited arrest in the G1 phase at 6h after exposure. Jurkat cells exhibited increased cell death after nsPEFs compared to CHO cells but did not exhibit checkpoint arrest at any observed time point. The G1/S phase checkpoint is partially controlled by the action of p53; the lack of an active p53 response in Jurkat cells could contribute to their ability to pass this checkpoint and resist cell cycle arrest. Both cell lines exhibited increased sensitivity to nsPEFs in G2/M phase. Live imaging of CHO cells after nsPEF exposure supports the theory of G1/S phase arrest, as a reduced number of cells undergo mitosis within 24 h when

  1. Pulsed electric field processing of egg products: a review.

    PubMed

    Yogesh, K

    2016-02-01

    Thermal processing ensures safety and enhances the shelf-life of most of the food products. It alters the structural-chemical composition, modifies heat labile components, as well as affects the functional properties of food products. This has driven the development of non-thermal food processing techniques, primarily for extending the shelf-life of different food products. These techniques are currently also being evaluated for their effects on product processing, quality and other safety parameters. Pulsed electric field (PEF) is an example of non-thermal technique which can be applied for a variety of purpose in the food processing industry. PEF can be used for antimicrobial treatment of various food products to improve the storability or food safety, for extraction and recovery of some high-value compounds from a food matrix or for stabilization of various food products through inactivation of some enzymes or catalysts. Research on the application of PEF to control spoilage or pathogenic microorganisms in different egg products is being currently focused. It has been reported that PEF effectively reduces the activity of various microorganisms in a variety of egg products. However, the PEF treatment also alters the structural and functional properties to some extent and there is a high degree of variability between different studies. In addition to integrating findings, the present review also provides several explanations for the inconsistency in findings between different studies related to PEF processing of egg products. Several specific recommendations for future research directions on PEF processing are well discussed in this review. PMID:27162373

  2. Molecular Simulation of Cell Membrane Deformation by Picosecond Intense Electric Pulse.

    PubMed

    Petrishia, Arockiasamy; Sasikala, Mohan

    2015-12-01

    The application of pulsed electric field is emerging as a new technique for cancer therapy. The irreversible electroporation is the major bioelectric effect to induce cell death. The pulsed electric field is transferred to target deep tissue non-invasively and precisely when the pulse duration is in picosecond regime. In this proposed work, the intense electric field with 100 ps pulse width is used for irreversible electroporation. If the electric field strength increases, the pore in the cell membrane enlarges, causing a loss of membrane intactness and the direct killing of cancer cells. This phenomenon is explored by molecular dynamics simulation. The electric field in the range of 0.8-5 V/nm is used for membrane dynamics. The membrane deformation occurs at the electric field of 5 V/nm. Picosecond pulsed electric field has a wealth of ultra-band spectrum, with extended time and enhanced spatial resolution and low signal distortion. The ultra-wide band antenna is used as a pulse delivery system for non-invasive skin cancer therapy. PMID:26054382

  3. Discharge Characteristics of SF6 in a Non-Uniform Electric Field Under Repetitive Nanosecond Pulses

    NASA Astrophysics Data System (ADS)

    Ran, Huijuan; Wang, Lei; Wang, Jue; Wang, Tao; Yan, Ping

    2014-05-01

    The characteristics of high pressure sulphur hexafluoride (SF6) discharges in a highly non-uniform electric field under repetitive nanosecond pulses are investigated in this paper. The influencing factors on discharge process, such as gas pressure, pulse repetition frequency (PRF), and number of applied pulses, are analyzed. Experimental results show that the corona intensity weakens with the increase of gas pressure and strengthens with the increase of PRF or number of applied pulses. Spark discharge images suggest that a shorter and thicker discharge plasma channel will lead to a larger discharge current. The number of applied pulses to breakdown descends with the increase of PRF and ascends with the rise of gas pressure. The reduced electric field (E/p) decreases with the increase of PRF in all circumstances. The experimental results provide significant supplements to the dielectric characteristics of strongly electronegative gases under repetitive nanosecond pulses.

  4. A dipole model of generating electric pulses in relaxation processes in the Earth's crust

    NASA Astrophysics Data System (ADS)

    Loseva, T. V.; Spivak, A. A.; Kuz'micheva, M. Yu.

    2012-01-01

    A new numerical model of generating electric pulses in the Earth's crust with use of a system of electric dipoles that are located uniformly over an active surface of the structural block relaxing after its constrained turn is developed. Electric moments of dipoles change with time according to the amplitude of differential movements. It is shown that the amplitude of electric pulses and the degree of their attenuation with distance to the source are in agreement with the data of results of instrumental observations.

  5. [Focusing properties of picosecond electric pulses in non-invasive cancer treatment].

    PubMed

    Long, Zaiquan; Yao, Chenguo; Li, Chengxiang; Mi, Yan; Sun, Caixin

    2010-10-01

    In the light of optical theory, we advanc an ultra-wideband impulse radiating antenna (IRA) which is composed of an ellipsoidal reflector and a cone radiator. The high-intensity ultra-short electric pulses radiated by IRA can be transferred into the deep target in tissue non-invasively and be focused effectively. With the focused picosecond electric pulses, the organelles (mitochondria) transmembrane potential shall change to collapse under which the tumor cells will be targetly induced to apoptosis, so the method of non-invasive treatment of tumors would be achieved. Based on the time-domain electromagnetic field theory, the propagation characteristics of picosecond electric pulses were analyzed with and without the context of biological tissue, respectively. The results show that the impulse characteristics of input pulse were maintained and the picosecond electric pulses can keep high resolution in target areas. Meanwhile, because of the dispersive nature of medium, the pulse amplitude of the pulses will attenuate and the pulse width will be broadened. PMID:21089684

  6. Validation of a pulsed electric field process to pasteurize strawberry puree

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An inexpensive data acquisition method was developed to validate the exact number and shape of the pulses applied during pulsed electric fields (PEF) processing. The novel validation method was evaluated in conjunction with developing a pasteurization PEF process for strawberry puree. Both buffered...

  7. Pasteurization of strawberry puree using a pilot plant pulsed electric fields (PEF) system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The processing of strawberry puree by pulsed electric fields (PEF) in a pilot plant system has never been evaluated. In addition, a method does not exist to validate the exact number and shape of the pulses applied during PEF processing. Both buffered peptone water (BPW) and fresh strawberry puree (...

  8. Design and Construction of a High Voltage Pulsed Source for Electric Excitation of the Gas Laser

    NASA Astrophysics Data System (ADS)

    Díaz, Xavier Daza; Neira, Oscar León B.; Díaz-Pérez, H. Abraham

    2008-04-01

    In this paper, the design, construction and implementation of High Voltage Pulsed Source for Electrical Excitation of the Gas Lasers, as a first phase of the research project "Design and Construction of an economically and reliable Laser System constituted by a molecular pulsed laser and a single optical head for dyes" is presented. We proposed and considered the design and the construction of a source of pulsed high voltage that adjusts to the requirements of the pumping system that requires a low pressure nitrogen laser. The design and construction of the source high voltage prototype is presented like part of the electrical pumping system for a Pulsed Nitrogen Laser. The electrical pumping System is conformed by three subsystems: the high pulsed regulated voltage Source, the storage and unloading system of electrical energy of active medium, and the frequency control system of discharge repetition (spark gap) constituted by a circuit RLC and the electrodes of the laser discharge tube. In the present work the aspects related to the pulsed high regulated voltage Source is presented, Our Source of high pulsed voltage is constituted by four fundamental stages: the Stage of Conversion AC-DC (voltage reducer), the Stage of Commutation by means of a Insulated Gate Bipolar Transistor (IGBT), the stage of Generation of signal modulated by the pulses width "PWM" (with base to Circuit TL 494) and the Stage of Elevation of Voltage (using a FlyBack Transformer).

  9. Pulse power generated electric fields as a means to control zebra mussels

    SciTech Connect

    Smythe, A.G.; Lange, C.L.; Doyle, J.F.

    1995-06-01

    In 1994, a study was conducted to determine if pulsed electric fields could reduce zebra mussel settlement rates. The study was a continuation of a study that began in 1991. Several types of fields were generated over the four-year study. The 1994 study concluded that fast rise DC, pulse power signals could stun post-veligers and significantly reduce settlement.

  10. Elimination of free-living amoebae in fresh water with pulsed electric fields.

    PubMed

    Vernhes, M C; Benichou, A; Pernin, P; Cabanes, P A; Teissié, J

    2002-08-01

    This study investigates the effects of pulsed electric fields on the inactivation of trophozoite form of Naegleria lovaniensis Ar9M-1 in batch and flow processes, systematically examining the lethal effect of field strength, pulse duration, number of pulses, and pulse frequency. Our results show that amoebae eradication is modulated by pulse parameters, composition of the pulsing medium, and physiological state of the cells. Cell survival is not related to the energy delivered to the cell suspension during the electrical treatment. For a given energy a strong field applied for a short cumulative pulse duration affects viability more than a weak field with a long cumulative pulsation. We also determine the optimal electrical conditions to obtain an inactivation rate higher than 95% while using the least energy. Flow processes allow to treat large-scale volumes. Our results show that the most efficient flow process for amoeba eradication requires a field parallel to the flow. Pulsed electric fields are a new and attractive method for inactivating amoebae in large volumes of fresh water. PMID:12230188

  11. Response of larval sea lampreys (Petromyzon marinus) to pulsed DC electrical stimuli in laboratory experiments

    USGS Publications Warehouse

    Bowen, Anjanette K.; Weisser, John W.; Bergstedt, Roger A.; Famoye, Felix

    2003-01-01

    Four electrical factors that are used in pulsed DC electrofishing for larval sea lampreys (Petromyzon marinus) were evaluated in two laboratory studies to determine the optimal values to induce larval emergence over a range of water temperatures and conductivities. Burrowed larvae were exposed to combinations of pulsed DC electrical factors including five pulse frequencies, three pulse patterns, and two levels of duty cycle over a range of seven voltage gradients in two separate studies conducted at water temperatures of 10, 15, and 20°C and water conductivities of 25, 200, and 900 μS/cm. A four-way analysis of variance was used to determine significant (α = 0.05) influences of each electrical factor on larval emergence. Multiple comparison tests with Bonferroni adjustments were used to determine which values of each factor resulted in significantly higher emergence at each temperature and conductivity. Voltage gradient and pulse frequency significantly affected emergence according to the ANOVA model at each temperature and conductivity tested. Duty cycle and pulse pattern generally did not significantly influence the model. Findings suggest that a setting of 2.0 V/cm, 3 pulses/sec, 10% duty, and 2:2 pulse pattern seems the most promising in waters of medium conductivity and across a variety of temperatures. This information provides a basis for understanding larval response to pulsed DC electrofishing gear factors and identifies electrofisher settings that show promise to increase the efficiency of the gear during assessments for burrowed sea lamprey larvae.

  12. Synergistic antibacterial effects of treatments with low temperature plasma jet and pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhuang, Jie; von Woedtke, Thomas; Kolb, Juergen F.; Zhang, Jue; Fang, Jing; Weltmann, Klaus-Dieter

    2014-09-01

    Inactivation of Staphylococcus aureus by a non-thermal argon operated plasma jet and by microsecond pulsed electric fields (PEF) was investigated. The different methods were either applied by themselves or in combination with each other. Treatments with plasma alone or pulsed electric fields alone were found to result in significant but not complete inactivation. A 2-log reduction was observed for the longest plasma exposure time of 3 min or for the application of 300 consecutive electric field pulses with 100-μs duration and 15-kV/cm amplitude. For the combined treatment with non-thermal plasma and pulsed electric fields, significant synergistic antibacterial effects were observed when samples were treated with plasma first. However, only an additive or at most a slight synergistic effect was observed when samples were first treated with pulsed electric fields instead. The acidification of the bacteria suspension after plasma treatment is likely responsible for the support of subsequent reaction mechanisms that are induced by exposures to pulsed electric fields and is hence the reason for the observed synergy.

  13. Dynamic response of ensemble neurons to pulsed optical and electrical excitation in vivo and in vitro

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Seleverstov, George A.; Kamenskih, Tatyana G.; Akchurin, George G.; Bondarenko, Olga A.

    2002-07-01

    The nonlinear response of the Hodgkin-Huxley model neuron with external electrical pulsed was investigated. Dynamic response of somatic frog nerve on electrical pulsed duration was study in vitro. Transcutaneous millisecond of excitation of the ganglion cell of the human retina by electric uses is used for diagnosis, determination of the extent of optic nerve damage, and also partial restoration of visual function in patients with glaucoma, myopia and different types of optic nerve atrophy. Correlation between the threshold of phosphen formation and duration of the stimulating electric pulses was determined experimentally in normal eyes and in eyes with various pathologies. Comparison of optical and electrical scintillating frequency gives information about the dynamic processes in the normal and pathological retina.

  14. Lysosomal exocytosis in response to subtle membrane damage following nanosecond pulse exposure

    NASA Astrophysics Data System (ADS)

    Dalzell, Danielle R.; Roth, Caleb C.; Bernhard, Joshua A.; Payne, Jason A.; Wilmink, Gerald J.; Ibey, Bennett L.

    2011-03-01

    The cellular response to subtle membrane damage following exposure to nanosecond electric pulses (nsEP) is not well understood. Recent work has shown that when cells are exposed to nsEP, ion permeable nanopores (< 2nm) are created in the plasma membrane in contrast to larger diameter pores (> 2nm) created by longer micro and millisecond duration pulses. Macroscopic damage to a plasma membrane by a micropipette has been shown to cause internal vesicles (lysosomes) to undergo exocytosis to repair membrane damage, a calcium mediated process called lysosomal exocytosis. Formation of large pores in the plasma membrane by electrical pulses has been shown to elicit lysosomal exocytosis in a variety of cell types. Our research objective is to determine whether lysosomal exocytosis will occur in response to nanopores formed by exposure to nsEP. In this paper we used propidium iodide (PI) and Calcium Green-1 AM ester (CaGr) to differentiate between large and small pores formed in CHO-K1 cells following exposure to either 1 or 20, 600-ns duration electrical pulses at 16.2 kV/cm. This information was compared to changes in membrane organization observed by increases in FM1-43 fluorescence, both in the presence and absence of calcium ions in the outside buffer. In addition, we monitored the real time migration of lysosomes within the cell using Cellular Lights assay to tag LAMP-1, a lysosomal membrane protein. Both 1 and 20 pulses elicited a large influx of extracellular calcium, while little PI uptake was observed following a single pulse exposure. Statistically significant increases in FM1-43 fluorescence were seen in samples containing calcium suggesting that calcium-triggered membrane repair may be occurring. Lastly, density of lysosomes within cells, specifically around the nucleus, appeared to change rapidly upon nsEP stimulation suggesting lysosomal migration.

  15. Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2003-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

  16. [Negative air ions generated by plants upon pulsed electric field stimulation applied to soil].

    PubMed

    Wu, Ren-ye; Deng, Chuan-yuan; Yang, Zhi-jian; Weng, Hai-yong; Zhu, Tie-jun-rong; Zheng, Jin-gui

    2015-02-01

    This paper investigated the capacity of plants (Schlumbergera truncata, Aloe vera var. chinensis, Chlorophytum comosum, Schlumbergera bridgesii, Gymnocalycium mihanovichii var. friedrichii, Aspidistra elatior, Cymbidium kanran, Echinocactus grusonii, Agave americana var. marginata, Asparagus setaceus) to generate negative air ions (NAI) under pulsed electric field stimulation. The results showed that single plant generated low amounts of NAI in natural condition. The capacity of C. comosum and G. mihanovichii var. friedrichii generated most NAI among the above ten species, with a daily average of 43 ion · cm(-3). The least one was A. americana var. marginata with the value of 19 ion · cm(-3). When proper pulsed electric field stimulation was applied to soil, the NAI of ten plant species were greatly improved. The effect of pulsed electric field u3 (average voltage over the pulse period was 2.0 x 10(4) V, pulse frequency was 1 Hz, and pulse duration was 50 ms) was the greatest. The mean NAI concentration of C. kanran was the highest 1454967 ion · cm(-3), which was 48498.9 times as much as that in natural condition. The lowest one was S. truncata with the value of 34567 ion · cm(-3), which was 843.1 times as much as that in natural condition. The capacity of the same plants to generate negative air ion varied extremely under different intensity pulsed electric fields. PMID:26094455

  17. Electric-discharge XeCl laser emitting 10-J, 300-ns pulses

    SciTech Connect

    Konovalov, I N; Losev, V F; Panchenko, Yu N; Ivanov, N G; Sukhov, M Yu

    2005-03-31

    The development of a long-pulse electric-discharge XeCl laser with the 9 x 6 x 100 cm active volume is reported. Laser is excited by using a double circuit with a pulsed charged storage capacitor consisting of paper-oil capacitors forming the pulse-shaping line. The storage capacitor is switched by a multichannel extended gap. The laser mixture was preionised by X-rays. The laser generated the 10-J output pulses with the FWHM of 300 ns, and a uniform intensity distribution over the exit aperture. (lasers)

  18. Lethality mechanisms in Escherichia coli induced by intense sub-microsecond electrical pulses

    NASA Astrophysics Data System (ADS)

    Chalise, P. R.; Perni, S.; Shama, G.; Novac, B. M.; Smith, I. R.; Kong, M. G.

    2006-10-01

    In this letter, the authors present the inactivation kinetics of cells of Escherichia coli and its mutants following treatment with high-intensity electrical pulses of 700 and 32ns durations. Their experimental results suggest that bacterial inactivation by 700ns pulses is consistent with a mechanism of reversible electroporation, whereas inactivation by 32ns pulses may occur as a result of damage to intracellular components. They believe that their results represent a first step towards elucidating the mechanism of lethality of submicrosecond pulses of different durations in prokaryotes.

  19. Permeabilization of yeast Saccharomyces cerevisiae cell walls using nanosecond high power electrical pulses

    NASA Astrophysics Data System (ADS)

    Stirke, A.; Zimkus, A.; Balevicius, S.; Stankevic, V.; Ramanaviciene, A.; Ramanavicius, A.; Zurauskiene, N.

    2014-12-01

    The electrical field-induced changes of the yeast Saccharomyces cerevisiae cells permeabilization to tetraphenylphosphonium (TPP+) ions were studied using square-shaped, nanosecond duration high power electrical pulses. It was obtained that pulses having durations ranging from 10 ns to 60 ns, and generating electric field strengths up to 190 kV/cm significantly (up to 65 times) increase the absorption rate of TPP+ ions without any detectible influence on the yeast cell viability. The modelling of the TPP+ absorption process using a second order rate equation demonstrates that depending on the duration of the pulses, yeast cell clusters of different sizes are homogeniously permeabilized. It was concluded, that nanosecond pulse-induced permeabilization can be applied to increase the operational speed of whole cell biosensors.

  20. System for adjusting frequency of electrical output pulses derived from an oscillator

    DOEpatents

    Bartholomew, David B.

    2006-11-14

    A system for setting and adjusting a frequency of electrical output pulses derived from an oscillator in a network is disclosed. The system comprises an accumulator module configured to receive pulses from an oscillator and to output an accumulated value. An adjustor module is configured to store an adjustor value used to correct local oscillator drift. A digital adder adds values from the accumulator module to values stored in the adjustor module and outputs their sums to the accumulator module, where they are stored. The digital adder also outputs an electrical pulse to a logic module. The logic module is in electrical communication with the adjustor module and the network. The logic module may change the value stored in the adjustor module to compensate for local oscillator drift or change the frequency of output pulses. The logic module may also keep time and calculate drift.

  1. Pulsed Electric Fields: Processing System, Microbial and Enzyme Inhibition, and Shelf Life Extension of Foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulsed electric field (PEF) nonthermal food processing has been of growing interest owing to its excellent potential to provide consumers with microbiologically-safe and fresh-like quality foods. Application of high voltage electric field at a certain level for a very short time by PEF not only inhi...

  2. Effect of Pulsed Electric Field Pre-Treatment on Osmotic Dehydration of Strawberries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to study the effect of pulsed electric fields (PEF) as a pre-treatment on osmotic dehydration characteristics and quality of strawberries. The studied PDF treatment conditions included three strengths of electric field (1.0, 2.0, 3.0 Kw/cm) and three numbers of pu...

  3. Long term survival of mice with hepatocellular carcinoma after pulse power ablation with nanosecond pulsed electric fields.

    PubMed

    Chen, X; Zhuang, J; Kolb, J F; Schoenbach, K H; Beebe, S J

    2012-02-01

    Novel therapies are needed for treating hepatocellular carcinoma (HCC) without recurrence in a single procedure. In this work we evaluated anti-neoplastic effects of a pulse power ablation (PPA) with nanosecond pulsed electric fields (nsPEFs), a non-thermal, non-drug, local, regional method and investigated its molecular mechanisms for hepatocellular carcinoma tumor ablation in vivo. An ectopic tumor model was established using C57BL/6 mice with Hepa1-6 hepatocellular carcinoma cells. Pulses with durations of 30 or 100 ns and fast rise times were delivered by a needle or ring electrode with different electric field strengths (33, 50 and 68 kV/cm), and 900 pulses in three treatment sessions (300 pulses each session) or a single 900 pulse treatment. Treated and control tumor volumes were monitored by ultrasound and apoptosis and angiogenesis markers were evaluated by immunohistochemistry. Seventy five percent of primary hepatocellular carcinoma tumors were eradicated with 900 hundred pulses at 100 ns pulses at 68 kV/cm in a single treatment or in three treatment sessions without recurrence within 9 months. Using quantitative analysis, tumors in treated animals showed nsPEF-mediated nuclear condensation (3 h post-pulse), cell shrinkage (1 h), increases in active executioner caspases (caspase-3 > -7 > -6) and terminal deoxynucleotidyl transferase dUTP nick-end-labeling (1 h) with decreases in vascular endothelial growth factor expression (7d) and micro-vessel density (14d). NsPEF ablation eliminated hepatocellular carcinoma tumors by targeting two therapeutic sites, apoptosis induction and inhibition of angiogenesis, both important cancer hallmarks. These data indicate that PPA with nsPEFs is not limited to treating skin cancers and provide a rationale for continuing to investigate pulse power ablation for hepatocellular carcinoma using other models in pre-clinical applications and ultimately in clinical trials. Based on present treatments for specific HCC stages, it

  4. Application of Microsecond Voltage Pulses for Water Disinfection by Diaphragm Electric Discharge

    NASA Astrophysics Data System (ADS)

    Kakaurov, S. V.; Suvorov, I. F.; Yudin, A. S.; Solovyova, T. L.; Kuznetsova, N. S.

    2015-11-01

    The paper presents the dependence of copper and silver ions formation on the duration of voltage pulses of diaphragm electric discharge and on the pH of treated liquid medium. Knowing it allows one to create an automatic control system to control bactericidal agent's parameters obtained in diaphragm electric discharge reactor. The current-voltage characteristic of the reactor with a horizontal to the diaphragm membrane water flow powered from the author's custom pulse voltage source is also presented. The results of studies of the power consumption of diaphragm electric discharge depending on temperature of the treated liquid medium are given.

  5. Dynamic response of the human retina to pulsed optical and electrical stimulation

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Bakutkin, Valery V.; Kamenskih, Tatyana G.; Zemskova, Tatyana M.; Ahuja, Poonam

    2000-04-01

    Transcutaneous millisecond stimulation of the retina by electric pulses is used for diagnosis, determination of the extent of optic nerve damage, and also partial restoration of visual function in patients with glaucoma, myopia and different types of optic nerve atrophy. Correlation between the threshold of phosphen formation and duration of the stimulating electric pulses was determined experimentally in normal eyes and in eyes with various pathologies. Comparison of optical and electrical scintillating frequency gives information about the dynamic processes in the normal and pathological retina.

  6. Mechanism for membrane electroporation irreversibility under high-intensity, ultrashort electrical pulse conditions

    NASA Astrophysics Data System (ADS)

    Joshi, R. P.; Schoenbach, K. H.

    2002-11-01

    An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g., mitochondria), without irreversible shock at the outer membranes, by a nanosecond, high-intensity electric pulse. This mechanism also explains the greater damage from multiple electric shocks.

  7. Pulsed oxygen-iodine chemical laser initiated by an electrical discharge

    SciTech Connect

    Zhang Rongyao; Chen Fang; Song Xueqin; Xu Qingzhou; Huan Changqing; Zhuang Qi; Zhang Cunhao

    1988-08-01

    This paper demonstrates for the first time the feasibility of an electrically initiated, pulsed oxygen-iodine laser which can be initiated efficiently by low energy electrons. By electrical initiation, an O/sub 2/(/sup 1/..delta..)--CH/sub 3/I--N/sub 2/ mixture has been made to lase with an output energy of 130 mJ. The efficiency of the electrical initiation is 350 times higher than that obtained with photo-initiation.

  8. Effects of high voltage nanosecond electric pulses on eukaryotic cells (in vitro): A systematic review.

    PubMed

    Batista Napotnik, Tina; Reberšek, Matej; Vernier, P Thomas; Mali, Barbara; Miklavčič, Damijan

    2016-08-01

    For this systematic review, 203 published reports on effects of electroporation using nanosecond high-voltage electric pulses (nsEP) on eukaryotic cells (human, animal, plant) in vitro were analyzed. A field synopsis summarizes current published data in the field with respect to publication year, cell types, exposure configuration, and pulse duration. Published data were analyzed for effects observed in eight main target areas (plasma membrane, intracellular, apoptosis, calcium level and distribution, survival, nucleus, mitochondria, stress) and an additional 107 detailed outcomes. We statistically analyzed effects of nsEP with respect to three pulse duration groups: A: 1-10ns, B: 11-100ns and C: 101-999ns. The analysis confirmed that the plasma membrane is more affected with longer pulses than with short pulses, seen best in uptake of dye molecules after applying single pulses. Additionally, we have reviewed measurements of nsEP and evaluations of the electric fields to which cells were exposed in these reports, and we provide recommendations for assessing nanosecond pulsed electric field effects in electroporation studies. PMID:26946156

  9. Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: Circuitry and mechanical design

    SciTech Connect

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-15

    A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 {mu}s. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

  10. Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: Circuitry and mechanical design

    NASA Astrophysics Data System (ADS)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

    A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

  11. Active RF Pulse Compression using Electrically Controlled Semiconductor Switches

    SciTech Connect

    Guo, J.; Tantawi, S.G.; /SLAC

    2008-01-30

    In this paper, we will present our recent results on the research of the ultra-fast high power RF switches based on silicon. We have developed a switch module at X-band which can use a silicon window as the switch. The switching is realized by generation of carriers in the bulk silicon. The carriers can be generated electrically or/and optically. The electrically controlled switches use PIN diodes to inject carrier. We have built the PIN diode switches at X-band, with <300ns switching time. The optically controlled switches use powerful lasers to excite carriers. By combining the laser excitation and electrical carrier generation, significant reduction in the required power of both the laser and the electrical driver is expected. High power test is under going.

  12. Electrical measurement techniques for pulsed high current electron beams

    SciTech Connect

    Struve, K.W.

    1986-04-01

    The advent of high current (1 to 100 kA), moderate energy (>10 MeV), short pulse (1 to 100 ns) electron accelerators used for charged particle beam research has motivated a need to complement standard diagnostics with development of new diagnostic techniques to measure electron beam parameters. A brief survey is given of the diagnostics for measuring beam current, position, size, energy, and emittance. While a broad scope of diagnostics will be discussed, this survey will emphasize diagnostics used on the Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA). Focus is placed on diagnostics measuring beam current, position and size. Among the diagnostics discussed are resistive wall current monitors, B/sub theta/ loops, Rogowski coils, Faraday cups, and x-ray wire diagnostics. Operation at higher current levels also increases radiation and electromagnetic pulse interference. These difficulties and methods for circumventing them are also discussed.

  13. Eradication of multidrug-resistant pseudomonas biofilm with pulsed electric fields.

    PubMed

    Khan, Saiqa I; Blumrosen, Gaddi; Vecchio, Daniela; Golberg, Alexander; McCormack, Michael C; Yarmush, Martin L; Hamblin, Michael R; Austen, William G

    2016-03-01

    Biofilm formation is a significant problem, accounting for over eighty percent of microbial infections in the body. Biofilm eradication is problematic due to increased resistance to antibiotics and antimicrobials as compared to planktonic cells. The purpose of this study was to investigate the effect of Pulsed Electric Fields (PEF) on biofilm-infected mesh. Prolene mesh was infected with bioluminescent Pseudomonas aeruginosa and treated with PEF using a concentric electrode system to derive, in a single experiment, the critical electric field strength needed to kill bacteria. The effect of the electric field strength and the number of pulses (with a fixed pulse length duration and frequency) on bacterial eradication was investigated. For all experiments, biofilm formation and disruption were confirmed with bioluminescent imaging and Scanning Electron Microscopy (SEM). Computation and statistical methods were used to analyze treatment efficiency and to compare it to existing theoretical models. In all experiments 1500 V are applied through a central electrode, with pulse duration of 50 μs, and pulse delivery frequency of 2 Hz. We found that the critical electric field strength (Ecr) needed to eradicate 100-80% of bacteria in the treated area was 121 ± 14 V/mm when 300 pulses were applied, and 235 ± 6.1 V/mm when 150 pulses were applied. The area at which 100-80% of bacteria were eradicated was 50.5 ± 9.9 mm(2) for 300 pulses, and 13.4 ± 0.65 mm(2) for 150 pulses. 80% threshold eradication was not achieved with 100 pulses. The results indicate that increased efficacy of treatment is due to increased number of pulses delivered. In addition, we that showed the bacterial death rate as a function of the electrical field follows the statistical Weibull model for 150 and 300 pulses. We hypothesize that in the clinical setting, combining systemic antibacterial therapy with PEF will yield a synergistic effect leading to improved

  14. Electrical short pulses generation using a resonant tunneling diode nonlinear transmission line

    NASA Astrophysics Data System (ADS)

    Essimbi, B. Z.; Jäger, D.

    2012-03-01

    In this paper, the generation of short electrical pulses based on nonlinear active wave propagation effects along the resonant tunneling diode transmission line is studied. The principle of operation is discussed and it is shown by computer experiments that an input rectangular pulse as well as a sinusoidal input signal can be converted into a set of output spikes, suitable for A/D conversion at millimeter wave frequencies.

  15. Suprachoroidal electrical stimulation: effects of stimulus pulse parameters on visual cortical responses

    NASA Astrophysics Data System (ADS)

    John, Sam E.; Shivdasani, Mohit N.; Williams, Chris E.; Morley, John W.; Shepherd, Robert K.; Rathbone, Graeme D.; Fallon, James B.

    2013-10-01

    Objective. Neural responses to biphasic constant current pulses depend on stimulus pulse parameters such as polarity, duration, amplitude and interphase gap. The objective of this study was to systematically evaluate and optimize stimulus pulse parameters for a suprachoroidal retinal prosthesis. Approach. Normally sighted cats were acutely implanted with platinum electrode arrays in the suprachoroidal space. Monopolar stimulation comprised of monophasic and biphasic constant current pulses with varying polarity, pulse duration and interphase gap. Multiunit responses to electrical stimulation were recorded in the visual cortex. Main results. Anodal stimulation elicited cortical responses with shorter latencies and required lower charge per phase than cathodal stimulation. Clinically relevant retinal stimulation required relatively larger charge per phase compared with other neural prostheses. Increasing the interphase gap of biphasic pulses reduced the threshold of activation; however, the benefits of using an interphase gap need to be considered in light of the pulse duration and polarity used and other stimulation constraints. Based on our results, anodal first biphasic pulses between 300-1200 µs are recommended for suprachoroidal retinal stimulation. Significance. These results provide insights into the efficacy of different pulse parameters for suprachoroidal retinal stimulation and have implications for the design of safe and clinically relevant stimulators for retinal prostheses.

  16. Optimization of electric pulse amplitude and frequency in vitro for low voltage and high frequency electrochemotherapy.

    PubMed

    Shankayi, Zeinab; Firoozabadi, S M P; Hassan, Zohair Saraf

    2014-02-01

    During standard electrochemotherapy (ECT), using a train of 1,000 V/cm amplitude rectangular pulses with 1 Hz frequency, patients experience an unpleasant sensation and slight edema. According to the patients, muscle contractions provoked by high amplitude (about 1,000 V/cm) and low repetition frequency (1 Hz) pulses are the most unpleasant and painful sensations. Recently, ECT using low voltage and higher repetition frequency (LVHF) has been shown to be an effective tool for inhibiting tumor growth. The aim of the present study was to optimize electric pulse amplitude and repetition frequency for LVHF ECT by sampling the different sets of pulse parameters on cell viability and permeabilization. In ECT, a reversible effect based on high permeabilization is desirable. For this purpose, we used bleomycin to evaluate the permeabilization of K562 and MIA-PACA2 cells caused by low voltage (50-150 V/cm) and higher repetition frequency (4-6 kHz) electric pulses. We show that the reversible effect with electropermeabilization of the cells caused by LVHF ECT is accessible; this interaction is more effective for electric pulses with 70 V/cm amplitude. PMID:24271721

  17. Tumour cell membrane poration and ablation by pulsed low-intensity electric field with carbon nanotubes.

    PubMed

    Wang, Lijun; Liu, Dun; Zhou, Ru; Wang, Zhigang; Cuschieri, Alfred

    2015-01-01

    Electroporation is a physical method to increase permeabilization of cell membrane by electrical pulses. Carbon nanotubes (CNTs) can potentially act like "lighting rods" or exhibit direct physical force on cell membrane under alternating electromagnetic fields thus reducing the required field strength. A cell poration/ablation system was built for exploring these effects of CNTs in which two-electrode sets were constructed and two perpendicular electric fields could be generated sequentially. By applying this system to breast cancer cells in the presence of multi-walled CNTs (MWCNTs), the effective pulse amplitude was reduced to 50 V/cm (main field)/15 V/cm (alignment field) at the optimized pulse frequency (5 Hz) of 500 pulses. Under these conditions instant cell membrane permeabilization was increased to 38.62%, 2.77-fold higher than that without CNTs. Moreover, we also observed irreversible electroporation occurred under these conditions, such that only 39.23% of the cells were viable 24 h post treatment, in contrast to 87.01% cell viability without presence of CNTs. These results indicate that CNT-enhanced electroporation has the potential for tumour cell ablation by significantly lower electric fields than that in conventional electroporation therapy thus avoiding potential risks associated with the use of high intensity electric pulses. PMID:25822874

  18. Tumour Cell Membrane Poration and Ablation by Pulsed Low-Intensity Electric Field with Carbon Nanotubes

    PubMed Central

    Wang, Lijun; Liu, Dun; Zhou, Ru; Wang, Zhigang; Cuschieri, Alfred

    2015-01-01

    Electroporation is a physical method to increase permeabilization of cell membrane by electrical pulses. Carbon nanotubes (CNTs) can potentially act like “lighting rods” or exhibit direct physical force on cell membrane under alternating electromagnetic fields thus reducing the required field strength. A cell poration/ablation system was built for exploring these effects of CNTs in which two-electrode sets were constructed and two perpendicular electric fields could be generated sequentially. By applying this system to breast cancer cells in the presence of multi-walled CNTs (MWCNTs), the effective pulse amplitude was reduced to 50 V/cm (main field)/15 V/cm (alignment field) at the optimized pulse frequency (5 Hz) of 500 pulses. Under these conditions instant cell membrane permeabilization was increased to 38.62%, 2.77-fold higher than that without CNTs. Moreover, we also observed irreversible electroporation occurred under these conditions, such that only 39.23% of the cells were viable 24 h post treatment, in contrast to 87.01% cell viability without presence of CNTs. These results indicate that CNT-enhanced electroporation has the potential for tumour cell ablation by significantly lower electric fields than that in conventional electroporation therapy thus avoiding potential risks associated with the use of high intensity electric pulses. PMID:25822874

  19. Electrical passivation of nonselective bio molecules in carbon nanotubes: Effect of pulse train in serum

    NASA Astrophysics Data System (ADS)

    Kim, Seok Hyang; Woo, Jun-Myung; Choi, Seongwook; Park, Young June

    2015-06-01

    We present an experimental and simulation study about a desorption of albumin, a representative nonselective molecules in serum, on carbon nanotube (CNT) surface as an electrical bio sensing channel under the pulse train condition. The motivation of the study on binding kinetics between CNT surface and albumin is to suppress the adsorption of nonselective proteins in blood such as albumin, thereby enhancing the selectivity of the electrical biosensor. To theoretically model the behavior of molecules and ions under the step pulse bias, the physics on the reaction rate, mass transport, and the resulting surface pH-value are considered using the Poisson and drift-diffusion equations. For the simulation model, the phosphate buffered saline is considered as the electrolyte solution and albumin is considered as a representative charged molecule for nonspecific binding in serum. Both the transient simulation and experimental result indicate that the suppression of the nonspecific binding under the pulse train is due to the unsymmetrical field force experienced by the protein during the pulse transitions (high to low and low to high) and the non-symmetry is caused by the different transient times between the electric field and the charge/discharge of the protein according to the surface pH modulation in serum. The experimental and simulation results clearly indicate that the pulse bias suppresses the nonselective bio molecules adsorption at the CNT surface so that the selectivity of the electrical biosensor for detecting the target molecules can be enhanced.

  20. Electrophysiological considerations relevant to the limiting of pulsed electric and magnetic fields

    SciTech Connect

    Jokela, K.

    1997-03-01

    The objective of the study was to theoretically examine the stimulation threshold of large myelinated axons and to use the results to formulate criteria for exposure limits of pulsed magnetic fields. The induced electric fields were calculated with a homogeneous tissue equivalent prolate spheroid. The stimulation level of the field was computed with the SENN model by using a folded axon with 2 mm separation for the Ranvier nodes. In the case of rectangler induced electric field pulses, the asymptotic stimulation level for electric field strength was 10 Vm{sup -1} with pulse durations greater than 100 {mu}s and for integrated electric field strength 1 x 10{sup -3} V m{sup -1} s with pulse durations less than 100 {mu}s. The latter threshold level was exceeded in the surface of the prolate spheroid when the magnetic flux density changed by more than 7.4 mT within 100 {mu}s. For Sinusoidal bursts, the threshold amplitude of the magnetic field decreased asymptotically to a minimum value 2.5 mT when the carrier frequency and burst duration exceeded 5 kHz and 100 {mu}s, respectively. If the same safety criteria are applied for pulsed and continuous exposure, the peak limits for induced current densities and magnetic field can exceed the amplitude values of the limits for continuous exposure only by a factor varying from 3 to 10. 31 refs., 12 figs.

  1. Transverse electric and transverse magnetic pulsed-beam decomposition of time-dependent aperture fields.

    PubMed

    Melamed, Timor; Abuhasira, Dor; Dayan, David

    2012-06-01

    The present contribution is concerned with applying beam-type expansion to a planar aperture time-dependent (TD) electromagnetic field in which the propagating elements, the electromagnetic pulsed-beams, are a priori decomposed into transverse electric (TE) and transverse magnetic (TM) field polarizations. The propagating field is described as a discrete superposition of tilted, shifted, and delayed TE and TM electromagnetic pulsed-beam propagators over the frame spectral lattice. These waveobjects are evaluated by using TD plane-wave spectral representations. Explicit asymptotic expressions for electromagnetic isodiffracting pulsed-quadratic beam propagators are presented, as well as a numerical example. PMID:22673443

  2. Tickling the retina: integration of subthreshold electrical pulses can activate retinal neurons

    NASA Astrophysics Data System (ADS)

    Sekhar, S.; Jalligampala, A.; Zrenner, E.; Rathbun, D. L.

    2016-08-01

    Objective. The field of retinal prosthetics has made major progress over the last decade, restoring visual percepts to people suffering from retinitis pigmentosa. The stimulation pulses used by present implants are suprathreshold, meaning individual pulses are designed to activate the retina. In this paper we explore subthreshold pulse sequences as an alternate stimulation paradigm. Subthreshold pulses have the potential to address important open problems such as fading of visual percepts when patients are stimulated at moderate pulse repetition rates and the difficulty in preferentially stimulating different retinal pathways. Approach. As a first step in addressing these issues we used Gaussian white noise electrical stimulation combined with spike-triggered averaging to interrogate whether a subthreshold sequence of pulses can be used to activate the mouse retina. Main results. We demonstrate that the retinal network can integrate multiple subthreshold electrical stimuli under an experimental paradigm immediately relevant to retinal prostheses. Furthermore, these characteristic stimulus sequences varied in their shape and integration window length across the population of retinal ganglion cells. Significance. Because the subthreshold sequences activate the retina at stimulation rates that would typically induce strong fading (25 Hz), such retinal ‘tickling’ has the potential to minimize the fading problem. Furthermore, the diversity found across the cell population in characteristic pulse sequences suggests that these sequences could be used to selectively address the different retinal pathways (e.g. ON versus OFF). Both of these outcomes may significantly improve visual perception in retinal implant patients.

  3. A tactile sensor translating texture and sliding motion information into electrical pulses

    NASA Astrophysics Data System (ADS)

    Liao, Zhipeng; Liu, Weihua; Wu, You; Zhang, Chen; Zhang, Yan; Wang, Xiaoli; Li, Xin

    2015-06-01

    An electric pulse output by a nanogenerator upon a strain-and-release event resembles a neural impulse. Cutaneous receptors imbedded in skin transduce mechanical forces impinging the skin into neural impulses and the tactile information is encoded into the firing rates of the neural impulses. Here, we report a nanogenerator-type tactile sensor, which records the texture and sliding motion by outputting a sequence of electric pulses. The sensitive component of the device is an NG embedded in a polydimethylsiloxane package. An artificial finger-print serving as a strain introducer mimicking finger prints is integrated over the NG. The electric pulses outputted by the device transmit the texture and sliding motion information. The device demonstrates a capability of detecting punch holes with depth less than 200 μm on a nonwoven cloth. It also shows a perfect reproducibility of the electric pulses as it scans the same area of a band wire and a piece of nonwoven cloth. The artificial finger-print is the key element in transferring the strain direction, which allows the active sensor (a nanogenerator) beneath to detect the bumpy structure during a touch and sliding motion.An electric pulse output by a nanogenerator upon a strain-and-release event resembles a neural impulse. Cutaneous receptors imbedded in skin transduce mechanical forces impinging the skin into neural impulses and the tactile information is encoded into the firing rates of the neural impulses. Here, we report a nanogenerator-type tactile sensor, which records the texture and sliding motion by outputting a sequence of electric pulses. The sensitive component of the device is an NG embedded in a polydimethylsiloxane package. An artificial finger-print serving as a strain introducer mimicking finger prints is integrated over the NG. The electric pulses outputted by the device transmit the texture and sliding motion information. The device demonstrates a capability of detecting punch holes with depth less

  4. Pulsed electric fields versus thermal treatment: equivalent processes to obtain equally acceptable citrus juices.

    PubMed

    Sentandreu, E; Carbonell, L; Rodrigo, D; Carbonell, J V

    2006-08-01

    Pulsed electric field treatment has been claimed to produce more acceptable chilled citrus juices than those obtained by conventional thermal treatment. The pectin methylesterase activity and the acceptability of nine juices obtained from Clementine mandarins, Valencia oranges, and Ortanique fruits (hybrid of mandarin and orange), untreated, pasteurized (85 degrees C for 10 s), and treated by pulsed electric fields (25 kV/cm for 330 micros), were evaluated. The treatments, selected to reach a similar level of pectin methylesterase inactivation, produced juices that did not differ in acceptability from each other for the three varieties and in all cases were less acceptable than the untreated juice. PMID:16924935

  5. Pulsed electromembrane extraction: a new concept of electrically enhanced extraction.

    PubMed

    Rezazadeh, Maryam; Yamini, Yadollah; Seidi, Shahram; Esrafili, Ali

    2012-11-01

    In the present work, pulsed electromembrane extraction (PEME) is introduced for the first time as an efficient and inexpensive method for the extraction of ionizable compounds from different matrices. The setup proposed for electromembrane extraction (EME) provides a very stable system and satisfactory repeatability (RSDs<4.4) in comparison with existing methods. In this paper, PEME is conducted for the extraction of model analytes from biological fluids. The effective parameters such as extraction time, applied voltage and the duration of pulse and outage period are optimized using the experimental design. Preconcentration factors in the range of 100-140 and recoveries in the range of 95-108 were obtained in different biological matrices. The linear dynamic ranges of 5-200 ng mL(-1) (with correlation coefficient higher than 0.9955) and limits of detection of 1.0 ng mL(-1) were obtained for both of the drugs. The figures of merit of PEME were compared with the results from conventional EME, which proves the advantages of the proposed technique. PMID:22999198

  6. Laser-spectroscopic electric field measurements in a ns-pulsed microplasma in nitrogen

    NASA Astrophysics Data System (ADS)

    Boehm, Patrick; Luggenhoelscher, Dirk; Czarnetzki, Uwe; 1123 Research Group Collaboration

    2013-09-01

    In this work for the first time ns-pulsed discharges in nitrogen at near atmospheric pressures are investigated by laser-spectroscopic electric field measurements, ultra-fast optical emission spectroscopy, current and voltage measurements. The discharge is operated with kV-pulses of about 150 ns duration between two parallel plate electrodes with a 1.2 mm gap. The laser technique for electric field measurement is based on a four-wave mixing process similar to Coherent anti-Stokes Raman Scattering (CARS). Here the static electric field acts effectively as the third wave with a zero frequency. The frequency of the generated anti-Stokes wave is in the IR regime and the amplitude is proportional to the electric field strength. By measuring the intensity of the IR- and anti-Stokes-signal it is now possible to determine the static electric field. Due to the short pulse-length of the lasers a temporal resolution in the ns range and a typical sensitivity of 50 - 100 V/mm in pure nitrogen is achieved (p > 50 mbar). Field-measurements are accompanied by emission measurements using a streak-camera with sub-ns resolutions. Further, current and voltage measurements combined with the electric field measurements allow determination of the plasma density. Funding by DFG through FOR 1123.

  7. Nanoparticle mediated thermal ablation of breast cancer cells using a nanosecond pulsed electric field.

    PubMed

    Burford, Christopher D; Bhattacharyya, Kiran D; Boriraksantikul, Nattaphong; Whiteside, Paul J D; Robertson, Benjamin P; Peth, Sarah M; Islam, Naz E; Viator, John A

    2013-06-01

    In the past, ablation of cancer cells using radiofrequency heating techniques has been demonstrated, but the current methodology has many flaws, including inconsistent tumor ablation and significant ablation of normal cells. Other researchers have begun to develop a treatment that is more selective for cancer cells using metallic nanoparticles and constant electric field exposure. In these studies, cell necrosis is induced by heating antibody functionalized metallic nanoparticles attached to cancer cells. Our approach to studying this phenomenon is to use similarly functionalized metallic nanoparticles that are specific for the T47D breast cancer cell line, exposing these nanoparticle cell conjugates to a nanosecond pulsed electric field. Using fluorescent, polystyrene-coated, iron-oxide nanoparticles, the results of our pilot study indicated that we were able to ablate up to approximately 80% of the cells using 60 ns pulses in increasing numbers of pulses and up to approximately 90% of the cells using 300 ns pulses in increasing numbers of pulses. These quantities of ablated cells were achieved using a cumulative exposure time 6 orders of magnitude less than most in vitro constant electric field studies. PMID:23694696

  8. Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma

    PubMed Central

    Frelinger, Andrew L.; Gerrits, Anja J.; Garner, Allen L.; Torres, Andrew S.; Caiafa, Antonio; Morton, Christine A.; Berny-Lang, Michelle A.; Carmichael, Sabrina L.; Neculaes, V. Bogdan; Michelson, Alan D.

    2016-01-01

    Background Activated autologous platelet-rich plasma (PRP) used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF) to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF) pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma. Aims To determine whether sub-microsecond duration, low electric field (SMLEF) bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity. Methods PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl2 and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and platelet factor 4 (PF4), and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl2 activated with 1 U/mL bovine thrombin. Results PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the

  9. Estimating of pulsed electric fields using optical measurements.

    SciTech Connect

    Flanagan, Timothy McGuire; Chantler, Gary R.

    2013-09-01

    We performed optical electric field measurements ion nanosecond time scales using the electrooptic crystal beta barium borate (BBO). Tests were based on a preliminary bench top design intended to be a proofofprinciple stepping stone towards a modulardesign optical Efield diagnostic that has no metal in the interrogated environment. The long term goal is to field a modular version of the diagnostic in experiments on large scale xray source facilities, or similarly harsh environments.

  10. A pulse-compression-ring circuit for high-efficiency electric propulsion.

    PubMed

    Owens, Thomas L

    2008-03-01

    A highly efficient, highly reliable pulsed-power system has been developed for use in high power, repetitively pulsed inductive plasma thrusters. The pulsed inductive thruster ejects plasma propellant at a high velocity using a Lorentz force developed through inductive coupling to the plasma. Having greatly increased propellant-utilization efficiency compared to chemical rockets, this type of electric propulsion system may one day propel spacecraft on long-duration deep-space missions. High system reliability and electrical efficiency are extremely important for these extended missions. In the prototype pulsed-power system described here, exceptional reliability is achieved using a pulse-compression circuit driven by both active solid-state switching and passive magnetic switching. High efficiency is achieved using a novel ring architecture that recovers unused energy in a pulse-compression system with minimal circuit loss after each impulse. As an added benefit, voltage reversal is eliminated in the ring topology, resulting in long lifetimes for energy-storage capacitors. System tests were performed using an adjustable inductive load at a voltage level of 3.3 kV, a peak current of 20 kA, and a current switching rate of 15 kA/micros. PMID:18377034

  11. Effect of gel structure of matrix orientation in pulsed alternating electric fields

    SciTech Connect

    Stellwagen, N.C.; Stellwagen, J.

    1993-12-31

    Four polymeric gels with different structures, LE agarose, HEEO agarose, beta-carrageenan, and polyacrylamide, were studied by transient electric birefringence to determine the importance of various structural features on the orientation of the gels in pulsed alternating electric fields. The birefrigence relaxation times observed for agarose gels in low voltage electric fields suggest that long fibers and/or domains, ranging up to tens of microns in size, are oriented by the electric field. The sign of the birefringence reverses when the direction of the electric field is reversed, suggesting that the oriented domains change their direction of orientation from parallel to perpendicular (or vice versa) when the polarity of the electric field is reversed. These anamalous orientation effects are observed with both types of agarose gels, but not with beta-carrageenan or polyacrylamide gels, suggesting that the alternating D,L galactose residues in the agarose backbone are responsible for the anomalies.

  12. Time-frequency analysis of single pulse electrical stimulation to assist delineation of epileptogenic cortex.

    PubMed

    van 't Klooster, Maryse A; Zijlmans, Maeike; Leijten, Frans S S; Ferrier, Cyrille H; van Putten, Michel J A M; Huiskamp, Geertjan J M

    2011-10-01

    Epilepsy surgery depends on reliable pre-surgical markers of epileptogenic tissue. The current gold standard is the seizure onset zone in ictal, i.e. chronic, electrocorticography recordings. Single pulse electrical stimulation can evoke epileptic, spike-like responses in areas of seizure onset also recorded by electrocorticography. Recently, spontaneous pathological high-frequency oscillations (80-520 Hz) have been observed in the electrocorticogram that are related to epileptic spikes, but seem more specific for epileptogenic cortex. We wanted to see whether a quantitative electroencephalography analysis using time-frequency information including the higher frequency range could be applied to evoked responses by single pulse electrical stimulation, to enhance its specificity and clinical use. Electrocorticography data were recorded at a 2048-Hz sampling rate from 13 patients. Single pulse electrical stimulation (10 stimuli, 1 ms, 8 mA, 0.2 Hz) was performed stimulating pairs of adjacent electrodes. A time-frequency analysis based on Morlet wavelet transformation was performed in a [-1 s : 1 s] time interval around the stimulus and a frequency range of 10-520 Hz. Significant (P = 0.05) changes in power spectra averaged for 10 epochs were computed, resulting in event-related spectral perturbation images. In these images, time-frequency analysis of single pulse-evoked responses, in the range of 10-80 Hz for spikes, 80-250 Hz for ripples and 250-520 Hz for fast ripples, were scored by two observers independently. Sensitivity, specificity and predictive value of time-frequency single pulse-evoked responses in the three frequency ranges were compared with seizure onset zone and post-surgical outcome. In all patients, evoked responses included spikes, ripples and fast ripples. For the seizure onset zone, the median sensitivity of time-frequency single pulse-evoked responses decreased from 100% for spikes to 67% for fast ripples and the median specificity increased from

  13. Permeabilization of plant tissues by monopolar pulsed electric fields: effect of frequency.

    PubMed

    Asavasanti, Suvaluk; Ristenpart, William; Stroeve, Pieter; Barrett, Diane M

    2011-01-01

    Pulsed electric fields (PEF) nonthermally induce cell membrane permeabilization and thereby improve dehydration and extraction efficiencies in food plant materials. Effects of electrical field strength and number of pulses on plant tissue integrity have been studied extensively. Two previous studies on the effect of pulse frequency, however, did not provide a clear view: one study suggested no effect of frequency, while the other found a greater impact on tissue integrity at lower frequency. This study establishes the effect of pulse frequency on integrity of onion tissues. Changes in electrical characteristics, ion leakage, texture parameters, and percent weight loss were quantified for a wide range of pulse frequencies under conditions of fixed field strength and pulse number. Optical microscopy and viable-cell staining provided direct visualization of effects on individual cells. The key finding is that lower frequencies (f < 1 Hz) cause more damage to tissue integrity than higher frequencies (f = 1 to 5000 Hz). Intriguingly, the optical microscopy observations demonstrate that the speed of intracellular convective motion (that is, cytoplasmic streaming) following PEF application is strongly correlated with PEF frequency. We provide the first in situ visualization of the intracellular consequence of PEF at different frequencies in a plant tissue. We hypothesize that cytoplasmic streaming plays a significant role in moving conductive ionic species from permeabilized cells to the intercellular space between plant cells, making subsequent pulses more efficacious at sufficiently low frequencies. The results suggest that decreasing the pulse frequency in PEF may minimize the number of pulses needed to achieve a desired amount of permeabilization, thus lowering the total energy consumption. Practical Application: PEF cause pores to be formed in plant cell membranes, thereby improve moisture removal and potential extraction of desirable components. This study used in

  14. Electric field in an AC dielectric barrier discharge overlapped with a nanosecond pulse discharge

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-08-01

    The effect of ns discharge pulses on the AC barrier discharge in hydrogen in plane-to-plane geometry is studied using time-resolved measurements of the electric field in the plasma. The AC discharge was operated at a pressure of 300 Torr at frequencies of 500 and 1750 Hz, with ns pulses generated when the AC voltage was near zero. The electric field vector is measured by ps four-wave mixing technique, which generates coherent IR signal proportional to the square of electric field. Absolute calibration was done using an electrostatic (sub-breakdown) field applied to the discharge electrodes, when no plasma was generated. The results are compared with one-dimensional kinetic modeling of the AC discharge and the nanosecond pulse discharge, predicting behavior of both individual micro-discharges and their cumulative effect on the electric field distribution in the electrode gap, using stochastic averaging based on the experimental micro-discharge temporal probability distribution during the AC period. Time evolution of the electric field in the AC discharge without ns pulses, controlled by a superposition of random micro-discharges, exhibits a nearly ‘flat top’ distribution with the maximum near breakdown threshold, reproduced quite well by kinetic modeling. Adding ns pulse discharges on top of the AC voltage waveform changes the AC discharge behavior in a dramatic way, inducing transition from random micro-discharges to a more regular, near-1D discharge. In this case, reproducible volumetric AC breakdown is produced at a well-defined moment after each ns pulse discharge. During the reproducible AC breakdown, the electric field in the plasma exhibits a sudden drop, which coincides in time with a well-defined current pulse. This trend is also predicted by the kinetic model. Analysis of kinetic modeling predictions shows that this effect is caused by large-volume ionization and neutralization of surface charges on the dielectrics by ns discharge pulses. The present

  15. S. cerevisiae fermentation activity after moderate pulsed electric field pre-treatments.

    PubMed

    Mattar, Jessy R; Turk, Mohammad F; Nonus, Maurice; Lebovka, Nikolai I; El Zakhem, Henri; Vorobiev, Eugene

    2015-06-01

    The batch fermentation process, inoculated by Pulsed Electric Field (PEF) treated wine yeasts (Saccharomyces cerevisiae Actiflore F33), was studied. PEF treatment was applied to the aqueous yeast suspensions ([Y] = 0.012 g/L) at the electric field strengths of E = 100 and 6000 V/cm using the same treatment protocol (number of pulses n = 1000, pulse duration ti = 100 μs, and pulse repetition time Δt = 100 ms). Electrical conductivity was increasing during and after the PEF treatment, which reflected cell electroporation. Then, fermentation was run for 150 h in an incubator (30 °C) with synchronic agitation. Electro-stimulation was revealing itself by the improvement of fermentation characteristics, and thus increased yeast metabolism. At the end of the lag phase (t = 40 h), fructose consumption in samples with electrically activated inoculum exceeded that of the control samples by ≈ 2.33 times for E = 100 V/cm and by ≈ 3.98 for E = 6000 V/cm. At the end of the log phase (120 h of fermentation), ≈ 30% mass reduction was reached in samples with PEF-treated inocula (E = 6000 V/cm), whereas the same mass reduction of the control sample required approximately 20 extra hours of fermentation. PMID:25204702

  16. Cost analysis of commercial pasteurization of orange juice by pulsed electric fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cost of pulsed electric field (PEF) pasteurization of orange juice was estimated. The cost analysis was based on processing conditions that met the US FDA (5 log reduction) requirement for fruit juice pasteurization and that achieved a 2 month microbial shelf-life. PEF-treated samples processed ...

  17. Energetic electron propagation in solid targets driven by the intense electric fields of femtosecond laser pulses

    SciTech Connect

    Seely, J. F.; Szabo, C. I.; Audebert, P.; Brambrink, E.

    2011-06-15

    An analytical model is used to interpret experimental data on the propagation of energetic electrons perpendicular to and parallel to the propagation direction of intense femtosecond laser pulses that are incident on solid targets. The pulses with {approx_equal}10{sup 20} W/cm{sup 2} intensity are incident normal onto a gadolinium or tungsten wire embedded in an aluminum substrate, and MeV electrons generated in the focal spot propagate along the laser direction into the irradiated wire. Electrons also propagate laterally from the focal spot through the aluminum substrate and into a dysprosium or hafnium spectator wire at a distance up to 1 mm from the irradiated wire. The ratio of the K shell emission from the spectator and irradiated wires is a measure of the numbers and energies of the MeV electrons propagating parallel to and perpendicular to the intense oscillating electric field of the laser pulse. It is found that the angular distribution of electrons from the focal spot is highly non-isotropic, and approximately twice as many electrons are driven by the electric field toward the spectator wire as into the irradiated wire. This quantitative result is consistent with the qualitative experimental observation that the oscillating electric field of an intense femtosecond laser pulse, when interacting with a heavy metal target, preferentially drives energetic electrons in the electric field direction as compared to perpendicular to the field.

  18. Effect of pulsed electric field treatment on hot-boned muscles of different potential tenderness.

    PubMed

    Suwandy, Via; Carne, Alan; van de Ven, Remy; Bekhit, Alaa El-Din A; Hopkins, David L

    2015-07-01

    In this study, the effect of pulsed electric field (PEF) treatment and ageing on the quality of beef M. longissimus lumborum (LL) and M. semimembranosus (SM) muscles was evaluated, including the tenderness, water loss and post-mortem proteolysis. Muscles were obtained from 12 steers (6 steers for each muscle), removed from the carcasses 4 hour postmortem and were treated with pulsed electric field within 2h. Six different pulsed electric field intensities (voltages of 5 and 10 kV × frequencies of 20, 50 and 90 Hz) plus a control were applied to each muscle to determine the optimum treatment conditions. Beef LL was found to get tougher with increasing treatment frequency whereas beef SM muscle was found to have up to 21.6% reduction in the shear force with pulsed electric field treatment. Post-mortem proteolysis showed an increase in both troponin and desmin degradation in beef LL treated with low intensity PEF treatment (20 Hz) compared to non-treated control samples. PMID:25754097

  19. A Pulsed Electric Field (PEF) bench static system to study bacteria inactivation

    NASA Astrophysics Data System (ADS)

    Cortese, Pietro; Dellacasa, Giuseppe; Gemme, Roberto; Bonetta, Sara; Bonetta, Silvia; Carraro, Elisabetta; Motta, Francesca; Paganoni, Marco; Pizzichemi, Marco

    2011-06-01

    Pulsed Electric Fields (PEF) technology is a promising non-thermal processing method for inactivation of microorganisms. A small PEF bench system able to treat a 0.4 ml static liquid volume has been built and tested at the laboratories of the Università del Piemonte Orientale in Alessandria, Italy. The technique used to produce the required fields consists of charging high voltage cables of various lengths and subsequently discharge them on a cylindrical cell. The pulse intensity can be adjusted to reach a maximum electric field in the cell of about 35 kV/cm and the pulse frequency can reach 10 Hz. We describe the PEF system in some detail and, as a benchmark of its performances, we report preliminary results obtained on Escherichia coli (ATCC 25922) at 10 9 Cfu/ml concentration suspended in a McIlvaine buffer (pH 7.2).

  20. Inactivation of Saccharomyces cerevisiae suspended in orange juice using high-intensity pulsed electric fields.

    PubMed

    Elez-Martínez, Pedro; Escolà-Hernández, Joan; Soliva-Fortuny, Robert C; Martín-Belloso, Olga

    2004-11-01

    Saccharomyces cerevisiae is often associated with the spoilage of fruit juices. The purpose of this study was to evaluate the effect of high-intensity pulsed electric field (HIPEF) treatment on the survival of S. cerevisiae suspended in orange juice. Commercial heat-sterilized orange juice was inoculated with S. cerevisiae (CECT 1319) (10(8) CFU/ml) and then treated by HIPEFs. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency, and pulse width) were evaluated and compared to those of heat pasteurization (90 degrees C/min). In all of the HIPEF experiments, the temperature was kept below 39 degrees C. S. cerevisiae cell damage induced by HIPEF treatment was observed by electron microscopy. HIPEF treatment was effective for the inactivation of S. cerevisiae in orange juice at pasteurization levels. A maximum inactivation of a 5.1-log (CFU per milliliter) reduction was achieved after exposure of S. cerevisiae to HIPEFs for 1,000 micros (4-micros pulse width) at 35 kV/cm and 200 Hz in bipolar mode. Inactivation increased as both the field strength and treatment time increased. For the same electric field strength and treatment time, inactivation decreased when the frequency and pulse width were increased. Electric pulses applied in the bipolar mode were more effective than those in the monopolar mode for destroying S. cerevisiae. HIPEF processing inactivated S. cerevisiae in orange juice, and the extent of inactivation was similar to that obtained during thermal pasteurization. HIPEF treatments caused membrane damage and had a profound effect on the intracellular organization of S. cerevisiae. PMID:15553647

  1. A Two-Dimensional Extremely Short Optical Pulse in a System of Carbon Nanotubes in a Direct Current Electric Field

    NASA Astrophysics Data System (ADS)

    Belonenko, M. B.; Galkina, E. N.; Filimonova, Z. A.

    2016-03-01

    The effect of an external dc electric field on the two-dimensional extremely short optical pulse propagating in a zigzag carbon nanotube array was investigated. The electromagnetic field evolution in the investigated nanotube system is described by the Maxwell equations. Using numerical simulation, the interaction between the pulse electromagnetic field and the external electric field applied to the carbon nanotube array is analyzed.

  2. Resistance of a pulsed electrical breakdown channel in ionic crystals

    NASA Astrophysics Data System (ADS)

    Punanov, I. F.; Emlin, R. V.; Kulikov, V. D.; Cholakh, S. O.

    2014-04-01

    A technique for estimating the resistance of the electrical breakdown channel in ionic crystals is proposed. This technique is based on measuring the channel velocity in a sample when a ballast resistor is connected to the circuit of a needle anode and on using the theoretical dependence of the channel velocity on the channel conductivity. The breakdown channel resistance at a voltage of 140 kV is about 6.5 kΩ in KCl and about 6.1 kΩ in KBr. These resistances are shown to characterize a gas phase. The gas-phase resistance is found to be nonuniform along the breakdown channel. The head part ˜1 mm long has the maximum resistance. This head region is concluded to contain dielectric substance clusters, which then decompose into metal and halogen ions. The cluster lifetime is ˜10-9 s.

  3. Effects of low frequency pulsed electrical current on keratinocytes in vitro

    SciTech Connect

    Hinsenkamp, M.; Jercinovic, A.

    1997-05-01

    The effects of low frequency pulsed electrical current on epidermal repair in vitro were examined. Charge-balanced current stimuli proposed for chronic wound treatment were tested on skin keratinocytes cultured at an air-liquid interface on dead human dermis. Results imply that the balance between proliferation and differentiation in electrically treated samples is significantly modified in favor of differentiation. More advanced differentiation, shown through epidermal histology, was obtained in cultures exposed to electrical current, whereas the culture growth, the result of keratinocyte migration and proliferation, was greater in control samples.

  4. Non-contact thrust stand calibration method for repetitively pulsed electric thrusters.

    PubMed

    Wong, Andrea R; Toftul, Alexandra; Polzin, Kurt A; Pearson, J Boise

    2012-02-01

    A thrust stand calibration technique for use in testing repetitively pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoid to produce a pulsed magnetic field that acts against a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasi-steady average deflection of the thrust stand arm away from the unforced or "zero" position can be related to the average applied force through a simple linear Hooke's law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other. The overall error on the linear regression fit used to determine the calibration coefficient was roughly 1%. PMID:22380121

  5. Strategies, Protections and Mitigations for Electric Grid Affets from Electro-Magnetic Pulse

    SciTech Connect

    Foster, Rita Ann; Frickey, Steven Jay

    2016-01-01

    The mission of DOE’s Office of Electricity Delivery and Energy Reliability (OE) is to lead national efforts to modernize the electricity delivery system, enhance the security and reliability of America’s energy infrastructure and facilitate recovery from disruptions to the energy supply. One of the threats OE is concerned about is a high-altitude electro-magnetic pulse (HEMP) from a nuclear explosion and eletro-magnetic pulse (EMP) or E1 pulse can be generated by EMP weapons. DOE-OE provides federal leadership and technical guidance in addressing electric grid issues. The Idaho National Laboratory (INL) was chosen to conduct the EMP study for DOE-OE due to its capabilities and experience in setting up EMP experiments on the electric grid and conducting vulnerability assessments and developing innovative technology to increase infrastructure resiliency. This report identifies known impacts to EMP threats, known mitigations and effectiveness of mitigations, potential cost of mitigation, areas for government and private partnerships in protecting the electric grid to EMP, and identifying gaps in our knowledge and protection strategies.

  6. Effect of Paired-Pulse Electrical Stimulation on the Activity of Cortical Circuits

    PubMed Central

    Saito, Kei; Onishi, Hideaki; Miyaguchi, Shota; Kotan, Shinichi; Fujimoto, Shuhei

    2015-01-01

    Objective: We investigated the transient effect of short-duration paired-pulse electrical stimulation (ppES) on corticospinal excitability and the after-effect of long-duration ppES on excitability, short-latency afferent inhibition (SAI), and afferent facilitation (AF). Methods: A total of 28 healthy subjects participated in two different experiments. In Experiment 1, motor-evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles before and immediately after short-duration ppES (5 s) at various inter-pulse intervals (2, 3, 4, 5, 6, 7, 10, 15, 20, and 30 ms). In Experiment 2, MEPs, SAI, and AF were measured before, immediately, and 20 and 40 min after long-duration ppES (20 min, inter-pulse interval of 5 and 15 ms) and peripheral electrical stimulation (20 min, 10 and 20 Hz). Results: Short-duration ppES with inter-pulse intervals of 5 and 20 ms significantly increased MEP measured in APB but not in ADM. Long-duration ppES with an inter-pulse interval of 5 ms significantly decreased SAI but not MEPs in APB. In contrast, long-duration ppES did not affect ADM. Conclusion: The afferent inputs induced by ppES-5 ms were effective for transiently increasing MEP and sustaining SAI reduction. PMID:26733847

  7. Conductivities of pig dermis and subcutaneous fat measured with rectangular pulse electrical current

    SciTech Connect

    Cheng, K. |; Tarjan, P.P.; Mertz, P.M.

    1996-12-31

    The authors examined experimentally the relationship between perpendicular and tangential electrical conductivities, {sigma}, and peak current density J, in pig skin dermis and subcutaneous fat specimens by using a four-electrode measuring system with rectangular pulse electrical current (RPEC). They also investigated the relationship of the conductivity, {sigma}, vs. pulse rate, f. The rates were selected at 8, 32, 64, and 128 pulses per second (pps), and the pulse width was fixed at 140 {micro}s. These values are often used in vivo to enhance cutaneous regeneration with RPEC stimulation. It was found that the conductivities may be approximated to be {sigma}{sub d} = [{sigma}{sub dx}{sigma}{sub dy}{sigma}{sub dz}] = [0.38 S/m 0.38 S/m 0.27 S/m] for the skin dermis and {sigma}{sub f} = [{sigma}{sub fx}{sigma}{sub fy}{sigma}{sub fz}] = [0.074 S/m 0.074 S/m 0.045 S/m] for the subcutaneous fat in the conditions of this experiment. These findings implies that the conductivities of the pig skin dermis and subcutaneous fat are anisotropic, i.e., {sigma}{sub x} = {sigma}{sub y} {ne} {sigma}{sub z}. It was also found that the conductivities are independent of current density and pulse rate in the current range from 20 {micro}A/cm{sup 2} to 120 mA/cm{sup 2}.

  8. Enabling pulsed power technologies for the generation of intense, nanosecond electric fields

    NASA Astrophysics Data System (ADS)

    Sanders, Jason M.

    This dissertation focuses on the design and implementation of pulsed power systems with an emphasis on systems that generate high peak powers on nanosecond and subnanosecond timescales. These systems are an enabling technology for many areas of scientific research focused on the effects of intense, nanosecond pulsed electric fields or pulsed discharges on physical processes. Researchers at USC use these systems in a variety of diverse application areas, including research into ignition and combustion using nanosecond discharges, research into the effects of pulsed electric fields on biological systems, and research into the efficacy of cold plasma discharges for disinfection. Each of these applications has its own set of pulsed power parameters, and in most cases these parameters necessitate that the systems be custom developed. The bulk of what follows will address the design methodologies, materials, and implementation techniques required for systems capable of generating high current (20 -- 500 Amperes), high voltage (1 kV -- 100 kV), nanosecond pulses. These principles culminate in the presentation of a new, compact, solid state architecture, which has been implemented into a system called the Rapid Pulser. This architecture uses diode opening switches at the output to switch inductively stored energy into a resistive load. To switch properly, these diodes must be pumped in the forward and reverse directions by a current, and this new architecture introduces a pumping circuit that significantly improves pulse shape as well as reduces amplitude jitter, time jitter, complexity, cost, and size. At 1.6 kg, this is the lightest pulsed power system developed at USC's Pulsed Power Lab, which is significant because minimizing size and weight is necessary for applications focused on the ignition and combustion of fuels. A summary of research focused on magnetic and dielectric materials for nonlinear energy compression will also be presented. Nonlinearities inherent to

  9. Irreversible electroporation: Medical application of intense electric pulses for sustainable health

    NASA Astrophysics Data System (ADS)

    Kurata, Kosaku; Takamatsu, Hiroshi

    2016-03-01

    Irreversible electroporation (IRE) is a promising method for the ablation of tumors using intense electric pulses. Because the mechanism of IRE is based on the breaking of the cytoplasmic membrane, only the cells are necrotized non-thermally without causing damage to the extracellular matrix when pulse settings are optimized to avoid Joule heating. In IRE therapy, a train of electric pulses of a few kilovolts is applied to the targeted tissue via a pair of electrodes. To definitely ablate the tissue and minimize the temperature rise during the application of pulses, determination of the adequate settings of the pulsesand electrode configuration prior to the therapy are important. Studies from the engineering perspective are therefore highly helpful for the successful use of IRE. In the current study, the authors' work associated with IRE will be introduced, including a 3D numerical simulation for the estimation of the electric field and temperature distribution around the electrodes, IRE experiment with a 3D cell culture model, and evaluation of cell destruction and thermal injury.

  10. Electrical Pulse Modification and Reversal of the Exchange-Bias in Magnetic Tunnel Junction Structures

    NASA Astrophysics Data System (ADS)

    Li, Yun; Tseng, Hsin-Wei; Ralph, Dan; Buhrman, Robert

    2010-03-01

    The use of antiferromagnetic layers to exchange-bias (EB) the reference layer is common in spin-torque (ST) experiments. Previous work has shown that the EB in both MTJs and spin valves can be degraded or reversed by electrical pulses, with the effect being attributed to heating or possibly to ST effects in the spin valve case. We have studied EB modification due to individual electrical pulses in the presence of a small external field (<50Oe) in FeCoB/MgO/FeCoB/IrMn MTJs as a function of MgO thickness. For MgO thickness = 1.7 nm, RA = 5 x 10^3φμm^2, pulses with Jc = 4 x 10^4A/cm^2 and V = 1.8 V, can repeatedly and reliably reverse the EB. For 1.3 nm barriers, RA =150φμm^2, much higher power pulses, Jc = 6 x 10^5A/cm^2 and V = 0.9 V, are required for reversal. Such results indicate that a combination of heating and ST, with the latter possibly involving the field-like spin torque component at high bias, is responsible for EB reversal in our MTJs. We will discuss the details of the EB reversal behavior and report the phase diagram for reversal as function of electrical and field bias.

  11. Enhanced anthocyanin extraction from red cabbage using pulsed electric field processing.

    PubMed

    Gachovska, Tanya; Cassada, David; Subbiah, Jeyamkondan; Hanna, Milford; Thippareddi, Harshavardhan; Snow, Daniel

    2010-08-01

    This study was conducted to evaluate the effect of pulsed electric field (PEF) treatment on anthocyanin extraction from red cabbage using water as a solvent. Mashed cabbage was placed in a batch treatment chamber and subjected to PEF (2.5 kV/cm electric field strength; 15 micros pulse width and 50 pulses, specific energy 15.63 J/g). Extracted anthocyanin concentrations (16 to 889 microg/mL) were determined using HPLC. Heat and light stabilities of the control and PEF-treated samples, having approximately the same initial concentrations, were studied. PEF treatments enhanced total anthocyanin extraction in water from red cabbage by 2.15 times with a higher proportion of nonacylated forms than the control (P < 0.05). The heat and light stabilities of the PEF-treated samples and control samples were not significantly different (P > 0.05). Practical Application: An innovative pretreatment technology, pulsed electric field processing, enhanced total anthocyanin extraction in water from red cabbage by 2.15 times. Manufacturers of natural colors can use this technology to extract anthocyanins from red cabbage efficiently. PMID:20722916

  12. Electrical delay line multiplexing for pulsed mode radiation detectors.

    PubMed

    Vinke, Ruud; Yeom, Jung Yeol; Levin, Craig S

    2015-04-01

    Medical imaging systems are composed of a large number of position sensitive radiation detectors to provide high resolution imaging. For example, whole-body Positron Emission Tomography (PET) systems are typically composed of thousands of scintillation crystal elements, which are coupled to photosensors. Thus, PET systems greatly benefit from methods to reduce the number of data acquisition channels, in order to reduce the system development cost and complexity. In this paper we present an electrical delay line multiplexing scheme that can significantly reduce the number of readout channels, while preserving the signal integrity required for good time resolution performance. We experimented with two 4 × 4 LYSO crystal arrays, with crystal elements having 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm dimensions, coupled to 16 Hamamatsu MPPC S10931-050P SiPM elements. Results show that each crystal could be accurately identified, even in the presence of scintillation light sharing and inter-crystal Compton scatter among neighboring crystal elements. The multiplexing configuration degraded the coincidence timing resolution from ∼243 ps FWHM to ∼272 ps FWHM when 16 SiPM signals were combined into a single channel for the 4 × 4 LYSO crystal array with 3 mm × 3 mm × 20 mm crystal element dimensions, in coincidence with a 3 mm × 3 mm × 5 mm LYSO crystal pixel. The method is flexible to allow multiplexing configurations across different block detectors, and is scalable to an entire ring of detectors. PMID:25768002

  13. Electrical delay line multiplexing for pulsed mode radiation detectors

    NASA Astrophysics Data System (ADS)

    Vinke, Ruud; Yeom, Jung Yeol; Levin, Craig S.

    2015-04-01

    Medical imaging systems are composed of a large number of position sensitive radiation detectors to provide high resolution imaging. For example, whole-body Positron Emission Tomography (PET) systems are typically composed of thousands of scintillation crystal elements, which are coupled to photosensors. Thus, PET systems greatly benefit from methods to reduce the number of data acquisition channels, in order to reduce the system development cost and complexity. In this paper we present an electrical delay line multiplexing scheme that can significantly reduce the number of readout channels, while preserving the signal integrity required for good time resolution performance. We experimented with two 4 × 4 LYSO crystal arrays, with crystal elements having 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm dimensions, coupled to 16 Hamamatsu MPPC S10931-050P SiPM elements. Results show that each crystal could be accurately identified, even in the presence of scintillation light sharing and inter-crystal Compton scatter among neighboring crystal elements. The multiplexing configuration degraded the coincidence timing resolution from ∼243 ps FWHM to ∼272 ps FWHM when 16 SiPM signals were combined into a single channel for the 4 × 4 LYSO crystal array with 3 mm × 3 mm × 20 mm crystal element dimensions, in coincidence with a 3 mm × 3 mm × 5 mm LYSO crystal pixel. The method is flexible to allow multiplexing configurations across different block detectors, and is scalable to an entire ring of detectors.

  14. Electrical delay line multiplexing for pulsed mode radiation detectors

    PubMed Central

    Vinke, Ruud; Yeom, Jung Yeol; Levin, Craig S.

    2015-01-01

    Medical imaging systems are composed of a large number of position sensitive radiation detectors to provide high resolution imaging. For example, whole-body Positron Emission Tomography (PET) systems are typically composed of thousands of scintillation crystal elements, which are coupled to photosensors. Thus, PET systems greatly benefit from methods to reduce the number of data acquisition channels, in order to reduce the system development cost and complexity. In this paper we present an electrical delay line multiplexing scheme that can significantly reduce the number of readout channels, while preserving the signal integrity required for good time resolution performance. We experimented with two 4 × 4 LYSO crystal arrays, with crystal elements having 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm dimensions, coupled to 16 Hamamatsu MPPC S10931-050P SiPM elements. Results show that each crystal could be accurately identified, even in the presence of scintillation light sharing and inter-crystal Compton scatter among neighboring crystal elements. The multiplexing configuration degraded the coincidence timing resolution from ~ 243 ps FWHM to ~272 ps FWHM when 16 SiPM signals were combined into a single channel for the 4 × 4 LYSO crystal array with 3 mm × 3 mm × 20 mm crystal element dimensions, in coincidence with a 3 mm × 3 mm × 5 mm LYSO crystal pixel. The method is exible to allow multiplexing configurations across different block detectors, and is scalable to an entire ring of detectors. PMID:25768002

  15. Detection of picosecond electrical pulses using the intrinsic Franz{endash}Keldysh effect

    SciTech Connect

    Lampin, J. F.; Desplanque, L.; Mollot, F.

    2001-06-25

    We report time-resolved measurements of ultrafast electrical pulses propagating on a coplanar transmission line using the intrinsic Franz{endash}Keldysh effect. A low-temperature-grown GaAs layer deposited on a GaAs substrate allows generation and also detection of ps pulses via electroabsorption sampling (EAS). This all-optical method does not require any external sampling probe. A typical rise time of 1.1 ps has been measured. EAS is a good candidate for use in THz characterization of ultrafast devices. {copyright} 2001 American Institute of Physics.

  16. Characterization of acoustic shockwaves generated by exposure to nanosecond electrical pulses

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Maswadi, Saher; Ibey, Bennett L.; Beier, Hope T.; Glickman, Randolph D.

    2014-03-01

    Despite 30 years of research, the mechanism behind the induced breakdown of plasma membranes by electrical pulses, termed electroporation, remains unknown. Current theories treat the interaction between the electrical field and the membrane as an entirely electrical event pointing to multiple plausible mechanisms. By investigating the biophysical interaction between plasma membranes and nanosecond electrical pulses (nsEP), we may have identified a non-electric field driven mechanism, previously unstudied in nsEP, which could be responsible for nanoporation of plasma membranes. In this investigation, we use a non-contact optical technique, termed probe beam deflection technique (PBDT), to characterize acoustic shockwaves generated by nsEP traveling through tungsten wire electrodes. We conclude these acoustic shockwaves are the result of the nsEP exposure imparting electrohydraulic forces on the buffer solution. When these acoustic shockwaves occur in close proximity to lipid bilayer membranes, it is possible that they impart a sufficient amount of mechanical stress to cause poration of that membrane. This research establishes for the first time that nsEP discharged in an aqueous medium generate measureable pressure waves of a magnitude capable of mechanical deformation and possibly damage to plasma membranes. These findings provide a new insight into the longunanswered question of how electric fields cause the breakdown of plasma membranes.

  17. The Effect of High Voltage, High Frequency Pulsed Electric Field on Slain Ovine Cortical Bone

    PubMed Central

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-01-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network

  18. The effect of high voltage, high frequency pulsed electric field on slain ovine cortical bone.

    PubMed

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-04-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network

  19. Generation of isolated sub-40-attosecond pulse with a multicycle chirped laser and a static electric field

    NASA Astrophysics Data System (ADS)

    Mohebbi, Masoud

    2016-02-01

    We numerically investigate the high-order harmonic generation and isolated attosecond pulse generation in a waveform that linearly produced by chirped laser pulse, chirp-free laser pulse, and static electric field. When a chirp-free laser pulse is added to the produced field of the chirped driving pulse and the static electric field, the plateau harmonic yield is enhanced by two orders. The spectral modulation is also significantly decreased, and the bandwidth of XUV spectrum is further broadened. An intense and a clean isolated 38-as pulse can be produced from the intense broadband XUV supercontinuum. After proper phase compensation, an isolated sub-8-attosecond pulse can be obtained. Furthermore, quantum time-frequency analysis reveals that the selection of the short quantum path can be achieved in this scheme.

  20. Pulse

    MedlinePlus

    Heart rate; Heart beat ... The pulse can be measured at areas where an artery passes close to the skin. These areas include the: ... side of the foot Wrist To measure the pulse at the wrist, place the index and middle ...

  1. Creating and manipulating vortices in atomic wave functions with short electric field pulses.

    PubMed

    Ovchinnikov, S Yu; Sternberg, J B; Macek, J H; Lee, Teck-Ghee; Schultz, D R

    2010-11-12

    We demonstrate the creation of vortices in the electronic probability density of an atom subject to short electric field pulses, how these vortices evolve and can be manipulated by varying the applied pulses, and that they persist to macroscopic distances in the spectrum of ejected electrons. This opens the possibility to use practical femtosecond or shorter laser pulses to create and manipulate these vortex quasiparticles at the atomic scale and observe them in the laboratory. Within a hydrodynamic interpretation we also show, since the Schrödinger equation is a particular instance of the Navier-Stokes equations, that for compressible fluids vortices can appear spontaneously and with a certain time delay, which is not expected to occur from the conventional point of view, illustrating applicability of the present study to vortex formation more broadly. PMID:21231229

  2. Sensitivity of ion induced charge pulses to the electrical and crystallographic properties of 60° dislocations

    NASA Astrophysics Data System (ADS)

    Breese, M. B. H.; King, P. J. C.; Grime, G. W.

    1994-12-01

    This letter reports evidence that the size of MeV ion induced charge pulses measured from epitaxial Si0.875Ge0.125/Si depends on both the crystallographic and electrical properties of the 60° misfit dislocations present. The results are correlated with both backscattered and transmission ion channeling analysis. With the sample in nonchanneled alignment the measured ion induced charge pulses depend on the number of charge carriers which recombine at the dislocations. With the sample in channeled alignment the rotated (110) and (11¯0) planes around the 60° dislocations affect the local rate of carrier generation and so alter the size of the measured ion induced charge pulses.

  3. [Pulsed electric fields inhibit tumor growth but induce myocardial injury of melanoma-bearing mice].

    PubMed

    Pan, Fengying; Wu, Sha; Wang, Xiaoxu; Zhang, Xiaogang

    2016-07-01

    Objective To investigate the tumor inhibiting effect of pulsed electric fields (PEFs) on melanoma-bearing mice, and understand its influence on myocardial cells and cardial electrical activity. Methods The melanoma models of the BALB/c mice were established by subcutaneously injecting B16 melanoma cells. These mice were randomly divided into four groups. The treated groups received pulsed electric stimulation at pulse width of 1, 3, 5 ms, with field strength of 100 V/cm and frequency of 10 Hz for 10 minutes daily in 15 consecutive days. ECG of mice was recorded. Tumor volume was measured with vernier caliper. Morphological changes of tumors were observed by HE staining. The expression of proliferating cell nuclear antigen (PCNA) mRNA was tested by real-time quantitative PCR, and the expression of PCNA protein was detected by immunofluorescence histochemistry. The ultrastructural changes of the cardiac tissues were observed by transmission electron microscopy (TEM). The serum levels of cardial troponin T (cTnT) and creatine kinase isoenzyme MB (CK-MB) were detected by ELISA. Results Compared with the control group, tumor volumes in all treated groups were reduced 7 days after PEFs treatment; more melanin granules in tumor cells were found in the treated groups; the expressions of PCNA mRNA and protein were down-regulated in all treated groups, and there were greater changes in the groups receiving the bigger pulse width. Myocardial injury was found in 3 ms group and 5 ms group, and the expressions of cTnT and CK-MB were significantly higher than those in the control group. Conclusion PEFs can inhibit tumor growth in melanoma-bearing mice. Increase of pulse width will aggravate myocardial injury. PMID:27363271

  4. Volatile profile and sensory evaluation of tomato juices treated with pulsed electric fields.

    PubMed

    Vallverdú-Queralt, Anna; Bendini, Alessandra; Barbieri, Sara; Di Lecce, Giuseppe; Martin-Belloso, Olga; Toschi, Tullia Gallina

    2013-02-27

    Tomato juices produced from tomatoes subjected to moderate-intensity pulsed electric fields (MIPEF) and from untreated tomatoes were preserved by high-intensity pulsed electric fields (HIPEF) or by thermal treatment (TH) having, in both cases, the fresh juice as a reference. The chemical and sensory changes of tomato juices stored at 4 °C for increasing period of time were analyzed. A quantitative descriptive analysis was developed to characterize the sensory quality of samples. Tomatoes subjected to MIPEF treatments led to tomato juices with a higher content of volatile compounds and better sensory properties than those prepared with untreated tomatoes. An enhancement was observed in hexanal and (E)-2-hexenal just after processing in juices prepared with MIPEF-treated tomatoes. A slight decrease in volatile compounds and a loss of sensory quality was observed over time in TH and HIPEF juices, but HIPEF-processed samples just after processing and through storage maintained higher overall quality. PMID:23373424

  5. Characterization of pulse amplitude and pulse rate modulation for a human vestibular implant during acute electrical stimulation

    NASA Astrophysics Data System (ADS)

    Nguyen, T. A. K.; DiGiovanna, J.; Cavuscens, S.; Ranieri, M.; Guinand, N.; van de Berg, R.; Carpaneto, J.; Kingma, H.; Guyot, J.-P.; Micera, S.; Perez Fornos, A.

    2016-08-01

    Objective. The vestibular system provides essential information about balance and spatial orientation via the brain to other sensory and motor systems. Bilateral vestibular loss significantly reduces quality of life, but vestibular implants (VIs) have demonstrated potential to restore lost function. However, optimal electrical stimulation strategies have not yet been identified in patients. In this study, we compared the two most common strategies, pulse amplitude modulation (PAM) and pulse rate modulation (PRM), in patients. Approach. Four subjects with a modified cochlear implant including electrodes targeting the peripheral vestibular nerve branches were tested. Charge-equivalent PAM and PRM were applied after adaptation to baseline stimulation. Vestibulo-ocular reflex eye movement responses were recorded to evaluate stimulation efficacy during acute clinical testing sessions. Main results. PAM evoked larger amplitude eye movement responses than PRM. Eye movement response axes for lateral canal stimulation were marginally better aligned with PRM than with PAM. A neural network model was developed for the tested stimulation strategies to provide insights on possible neural mechanisms. This model suggested that PAM would consistently cause a larger ensemble firing rate of neurons and thus larger responses than PRM. Significance. Due to the larger magnitude of eye movement responses, our findings strongly suggest PAM as the preferred strategy for initial VI modulation.

  6. SESAM-modelocked electrically pumped VECSELs emitting 6.3-ps pulses

    NASA Astrophysics Data System (ADS)

    Zaugg, C. A.; Pallmann, W. P.; Mangold, M.; Dahhan, I.; Golling, M.; Tilma, B. W.; Witzigmann, B.; Keller, U.

    2014-03-01

    Optically pumped vertical external cavity surface emitting lasers (OP-VECSELs) evolved to high-power laser sources offering excellent beam-quality, wavelength flexibility and low-noise properties in a compact and simple cavity. Passively modelocked with a semiconductor saturable absorber mirror (SESAM), VECSELs demonstrated fs-pulses with multi-Watt average output powers at gigahertz repetition rates. Electrical pumping (EP) is an obvious step to make these semiconductor lasers even more compact and suitable for chip integration, potentially enabling access to applications such as data communication or optical clocking. With SESAMmodelocked EP-VECSELs, 57-ps pulses with an average output power of 40 mW and 9.5-ps pulses with 7.6 mW have been obtained. However, due to the intrinsic trade-off between electrical and optical properties in the design of EPVECSELs, short pulses at high average output power are difficult to achieve. This challenge was previously addressed in our theoretical guidelines for power scaling and modelocking optimization and later experimentally verified. Here, we report on the successful implementation of an improved design and fabrication scheme for EP-VECSELs, grown and fabricated at ETH Zurich. These lasers enabled a further decrease in pulse duration to 7.3 ps while increasing the average output power to 13.1 mW at 1.46-GHz repetition rate. The shortest pulse duration measured was 6.3 ps with an average power of 6.2 mW. In addition to the modelocking experiments, we present a thorough cw-characterization of our EP-VECSELs of different sizes and in different cavity configurations, pointing out the inevitable trade-off between high-power multi-mode and low-power single-mode operation limiting the modelocking performance.

  7. Electric propulsion. [pulsed plasma thruster and electron bombardment ion engine for MSAT attitude control and stationkeeping

    NASA Technical Reports Server (NTRS)

    1982-01-01

    An alternative propulsion subsystem for MSAT is presented which has a potential of reducing the satellite weight by more than 15%. The characteristics of pulsed plasma and ion engines are described and used to estimate of the mass of the propellant and thrusters for attitude control and stationkeeping functions for MSAT. Preliminary estimates indicate that the electric propulsion systems could also replace the large momentum wheels necessary to counteract the solar pressure; however, the fine pointing wheels would be retained. Estimates also show that either electric propulsion system can save approximately 18% to 20% of the initial 4,000 kg mass. The issues that require further experimentation are mentioned.

  8. Delay-Dependent Response in Weakly Electric Fish under Closed-Loop Pulse Stimulation

    PubMed Central

    Forlim, Caroline Garcia; Pinto, Reynaldo Daniel; Varona, Pablo; Rodríguez, Francisco B.

    2015-01-01

    In this paper, we apply a real time activity-dependent protocol to study how freely swimming weakly electric fish produce and process the timing of their own electric signals. Specifically, we address this study in the elephant fish, Gnathonemus petersii, an animal that uses weak discharges to locate obstacles or food while navigating, as well as for electro-communication with conspecifics. To investigate how the inter pulse intervals vary in response to external stimuli, we compare the response to a simple closed-loop stimulation protocol and the signals generated without electrical stimulation. The activity-dependent stimulation protocol explores different stimulus delivery delays relative to the fish’s own electric discharges. We show that there is a critical time delay in this closed-loop interaction, as the largest changes in inter pulse intervals occur when the stimulation delay is below 100 ms. We also discuss the implications of these findings in the context of information processing in weakly electric fish. PMID:26473597

  9. LPS levels in root canals after the use of ozone gas and high frequency electrical pulses.

    PubMed

    Melo, Tiago André Fontoura de; Gründling, Grasiela Sabrina Longhi; Montagner, Francisco; Scur, Alcione Luiz; Steier, Liviu; Scarparo, Roberta Kochenborger; Figueiredo, José Antônio Poli de; Vier-Pelisser, Fabiana Vieira

    2016-01-01

    The present study aims to verify the effect of ozone gas (OZY® System) and high frequency electric pulse (Endox® System) systems on human root canals previously contaminated with Escherichia colilipopolysaccharide (LPS). Fifty single-rooted teeth had their dental crowns removed and root lengths standardized to 16 mm. The root canals were prepared up to #60 hand K-files and sterilized using gamma radiation with cobalt 60. The specimens were divided into the following five groups (n = 10) based on the disinfection protocol used: OZY® System, one 120-second-pulse (OZY 1p); OZY® System, four 24-second-pulses (OZY 4p); and Endox® System (ENDOX). Contaminated and non-contaminated canals were exposed only to apyrogenic water and used as positive (C+) and negative (C-) controls, respectively. LPS (O55:B55) was administered in all root canals except those belonging to group C-. After performing disinfection, LPS samples were collected from the canals using apyrogenic paper tips. Limulus Amoebocyte Lysate (LAL) was used to quantify the LPS levels, and the data obtained was analyzed using one-way ANOVA. The disinfection protocols used were unable to reduce the LPS levels significantly (p = 0.019). The use of ozone gas and high frequency electric pulses was not effective in eliminating LPS from the root canals. PMID:26981752

  10. Development of Short Electrical Pulses in a Schottky Line Periodically Loaded with Resonant Tunneling Diodes

    NASA Astrophysics Data System (ADS)

    Essimbi, B. Z.; Jäger, D.

    2012-06-01

    The characteristics of a Schottky line periodically loaded with resonant tunneling diodes (RTDs) are discussed for the development of short electrical pulses. RTDs act as electronic switches and exhibit a pronounced N-shaped I-V characteristic even at millimetre wave frequencies. The dynamics of the line is reduced to an extended KdV equation. These dynamics are considered both within the method of perturbation and the numerical integration of the transmission equation of the line.

  11. Direct hydrogen production from alcohol using pulse-electron emission in an unsymmetrical electric field

    NASA Astrophysics Data System (ADS)

    Matsuura, H.; Tanikawa, T.; Takaba, H.; Fujiwara, Y.

    2004-05-01

    We report a means of instantaneously producing hydrogen directly from alcohol using pulse-electron emission in an unsymmetrical electric field. We selected 1-butanol as a hydrogen-rich material for producing hydrogen. A 1-butanol molecule has more than twice as many hydrogen atoms as the methanol molecule and is a good candidate for a hydrogen source. The direct electron emission on the surface of volatile 1-butanol prevented intense discharge and produced hydrogen at room temperature in air.

  12. Pulsed currents carried by whistlers. IV. Electric fields and radiation excited by an electrode

    SciTech Connect

    Stenzel, R.L.; Urrutia, J.M.; Rousculp, C.L.

    1995-04-01

    Electromagnetic properties of current pulses carried by whistler wave packets are obtained from a basic laboratory experiment. While the magnetic field and current density are described in the preceding companion paper (Part III), the present analysis starts with the electric field. The inductive and space charge electric field contributions are separately calculated in Fourier space from the measured magnetic field and Ohm`s law along B{sub 0}. Inverse Fourier transformation yields the total electric field in space and time, separated into rotational and divergent contributions. The space-charge density in whistler wave packets is obtained. The cross-field tensor conductivity is determined. The frozen-in condition is nearly satisfied, {bold E}+{bold v}{sub {ital e}}{times}{bold B}{congruent}0. The dissipation is obtained from Poynting`s theorem. The waves are collisionally damped; Landau damping is negligible. A radiation resistance for the electrode is determined. Analogous to Poynting`s theorem, the transport of helicity is analyzed. Current helicity is generated by a flow of helicity between pulses traveling in opposite directions which carry opposite signs of helicity. Helicity is dissipated by collisions. These observations complete a detailed description of whistler/current pulses which can occur in various laboratory and space plasmas. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  13. Removal of phenol by activated alumina bed in pulsed high-voltage electric field.

    PubMed

    Zhu, Li-nan; Ma, Jun; Yang, Shi-dong

    2007-01-01

    A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe2+. The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/L Fe2+ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation. PMID:17915702

  14. Selective Field Effects on Intracellular Vacuoles and Vesicle Membranes with Nanosecond Electric Pulses

    PubMed Central

    Tekle, Ephrem; Oubrahim, Hammou; Dzekunov, Sergey M.; Kolb, Juergen F.; Schoenbach, Karl H.; Chock, P. B.

    2005-01-01

    Electric pulses across intact vesicles and cells can lead to transient increase in permeability of their membranes. We studied the integrity of these membranes in response to external electric pulses of high amplitude and submicrosecond duration with a primary aim of achieving selective permeabilization. These effects were examined in two separate model systems comprising of 1), a mixed population of 1,2-di-oleoyl-sn-glycero-3-phosphocholine phospholipid vesicles and in 2), single COS-7 cells, in which large endosomal membrane vacuoles were induced by stimulated endocytosis. It has been shown that large and rapidly varying external electric fields, with pulses shorter than the charging time of the outer-cell membrane, could substantially increase intracellular fields to achieve selective manipulations of intracellular organelles. The underlying principle of this earlier work is further developed and applied to the systems studied here. Under appropriate conditions, we show preferential permeabilization of one vesicle population in a mixed preparation of vesicles of similar size distribution. It is further shown that large endocytosed vacuoles in COS-7 cells can be selectively permeabilized with little effect on the integrity of outer cell membrane. PMID:15821165

  15. Acceleration of ions by electric field pulses in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Liu, J.; Angelopoulos, V.; Runov, A.

    2015-06-01

    Intense (˜5-15 mV/m), short-lived (≤1 min) electric field pulses have been observed to accompany earthward propagating, dipolarizing flux bundles (flux tubes with a strong magnetic field) before they are stopped by the strong dipole field. Using Time History of Events and Macroscale Interactions during Substorms observations and test particle modeling, we investigate particle acceleration around L shell ˜7-9 in the nightside magnetosphere and demonstrate that such pulses can effectively accelerate ions with tens of keV initial energy to hundreds of keV. This acceleration occurs because the ion gyroradius is comparable to the spatial scale of the localized electric field pulse at the leading edge of the flux bundle before it stops. The proposed acceleration mechanism can reproduce observed spectra of high-energy ions. We conclude that the electric field associated with dipolarizing flux bundles prior to their stoppage in the inner magnetosphere provides a natural site for intense local ion acceleration.

  16. Pulsed Electric Processing of the Seismic-Active Fault for Earthquake Hazard Mitigation

    NASA Astrophysics Data System (ADS)

    Novikov, V. A.; Zeigarnik, V. A.; Konev, Yu. B.; Klyuchkin, V. N.

    2010-03-01

    Previous field and laboratory investigations performed in Russia (1999-2008) showed a possibility of application of high-power electric current pulses generated by pulsed MHD power system for triggering the weak seismicity and release of tectonic stresses in the Earth crust for earthquake hazard mitigation. The mechanism of the influence of man-made electromagnetic field on the regional seismicity is not clear yet. One of possible cause of the phenomenon may be formation of cracks in the rocks under fluid pressure increase due to Joule heat generation by electric current injected into the Earth crust. Detailed 3D-calculaton of electric current density in the Earth crust of Northern Tien Shan provided by pulsed MHD power system connected to grounded electric dipole showed that at the depth of earthquake epicenters (> 5km) the electric current density is lower than 10-7 A/m2 that is not sufficient for increase of pressure in the fluid-saturated porous geological medium due to Joule heat generation, which may provide formation of cracks resulting in the fault propagation and release of tectonic stresses in the Earth crust. Nevertheless, under certain conditions, when electric current will be injected into the fault through the casing pipes of deep wells with preliminary injection of conductive fluid into the fault, the current density may be high enough for significant increase of mechanic pressure in the porous two-phase geological medium. Numerical analysis of a crack formation triggered by high-power electric pulses based on generation of mechanical pressure in the geological medium was carried out. It was shown that calculation of mechanical pressure impulse due to high-power electrical current in the porous two-phase medium may be performed neglecting thermal conductance by solving the non-stationary equation of piezo-conductivity with Joule heat generation. For calculation of heat generation the known solution of the task of current spreading from spherical or

  17. Impact of external medium conductivity on cell membrane electropermeabilization by microsecond and nanosecond electric pulses

    PubMed Central

    Silve, Aude; Leray, Isabelle; Poignard, Clair; Mir, Lluis M.

    2016-01-01

    The impact of external medium conductivity on the efficiency of the reversible permeabilisation caused by pulsed electric fields was investigated. Pulses of 12 ns, 102 ns or 100 μs were investigated. Whenever permeabilisation could be detected after the delivery of one single pulse, media of lower conductivity induced more efficient reversible permeabilisation and thus independently of the medium composition. Effect of medium conductivity can however be hidden by some saturation effects, for example when pulses are cumulated (use of trains of 8 pulses) or when the detection method is not sensitive enough. This explains the contradicting results that can be found in the literature. The new data are complementary to those of one of our previous study in which an opposite effect of the conductivity was highlighted. It stresses that the conductivity of the medium influences the reversible permeabilization by several ways. Moreover, these results clearly indicate that electropermeabilisation does not linearly depend on the energy delivered to the cells. PMID:26829153

  18. Electroporation dynamics in biological cells subjected to ultrafast electrical pulses: A numerical simulation study

    NASA Astrophysics Data System (ADS)

    Joshi, R. P.; Schoenbach, K. H.

    2000-07-01

    A model analysis of electroporation dynamics in biological cells has been carried out based on the Smoluchowski equation. Results of the cellular response to short, electric pulses are presented, taking account of the growth and resealing dynamics of transient aqueous pores. It is shown that the application of large voltages alone may not be sufficient to cause irreversible breakdown, if the time duration is too short. Failure to cause irreversible damage at small pulse widths could be attributed to the time inadequacy for pores to grow and expand beyond a critical threshold radius. In agreement with earlier studies, it is shown that irreversible breakdown would lead to the formation of a few large pores, while a large number of smaller pores would appear in the case of reversible breakdown. Finally, a pulse width dependence of the applied voltage for irreversible breakdown has been obtained. It is shown that in the absence of dissipation, the associated energy input necessary reduces with decreasing pulse width to a limiting value. However, with circuit effects taken into account, a local minima in the pulse dependent energy function is predicted, in keeping with previously published experimental reports.

  19. Non-Contact Thrust Stand Calibration Method for Repetitively-Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Wong, Andrea R.; Toftul, Alexandra; Polzin, Kurt A.; Pearson, J. Boise

    2011-01-01

    A thrust stand calibration technique for use in testing repetitively-pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoidal coil to produce a pulsed magnetic field that acts against the magnetic field produced by a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasisteady average deflection of the thrust stand arm away from the unforced or zero position can be related to the average applied force through a simple linear Hooke s law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other as the constant relating average deflection and average thrust match within the errors on the linear regression curve fit of the data. Quantitatively, the error on the calibration coefficient is roughly 1% of the coefficient value.

  20. Investigation of a direct effect of nanosecond pulse electric fields on mitochondria

    NASA Astrophysics Data System (ADS)

    Estlack, Larry E.; Roth, Caleb C.; Cerna, Cesario Z.; Wilmink, Gerald J.; Ibey, Bennett L.

    2014-03-01

    The unique cellular response to nanosecond pulsed electric field (nsPEF) exposure, as compared to longer pulse exposure, has been theorized to be due to permeabilization of intracellular organelles including the mitochondria. In this investigation, we utilized a high-throughput oxygen and pH sensing system (Seahorse® XF24 extracellular flux analyzer) to assess the mitochondrial activity of Jurkat and U937 cells after nsPEF. The XF Analyzer uses a transient micro-chamber of only a few μL in specialized cell culture micro-plates to enable oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) to be monitored in real-time. We found that for nsPEF exposures of 10 pulses at 10-ns pulse width and at 50 kV/cm e-field, we were able to cause an increase in OCR in both U937 and Jurkat cells. We also found that high pulse numbers (>100) caused a significant decrease in OCR. Higher amplitude 150 kV/cm exposures had no effect on U937 cells and yet they had a deleterious effect on Jurkat cells, matching previously published 24 hour survival data. These results suggest that the exposures were modulating metabolic activity in cells possibly due to direct effects on the mitochondria themselves. To validate this hypothesis, we isolated mitochondria from U937 cells and exposed them similarly and found no significant change in metabolic activity for any pulse number. In a final experiment, we removed calcium from the buffer solution that the cells were exposed in and found that no significant enhancement in metabolic activity was observed. These results suggest that direct permeabilization of the mitochondria is unlikely a primary effect of nsPEF exposure and calcium-mediated intracellular pathway activation is likely responsible for observed pulse-induced mitochondrial effects.

  1. Behavior of yeast cells in aqueous suspension affected by pulsed electric field.

    PubMed

    El Zakhem, H; Lanoisellé, J-L; Lebovka, N I; Nonus, M; Vorobiev, E

    2006-08-15

    This work discusses pulsed electric fields (PEF) induced effects in treatment of aqueous suspensions of concentrated yeast cells (S. cerevisiae). The PEF treatment was done using pulses of near-rectangular shape, electric field strength was within E=2-5 kV/cm and the total time of treatment was t(PEF)=10(-4)-0.1 s. The concentration of aqueous yeast suspensions was in the interval of C(Y)=0-22 (wt%), where 1% concentration corresponds to the cellular density of 2x10(8) cells/mL. Triton X-100 was used for studying non-ionic surfactant additive effects. The electric current peak value I was measured during each pulse application, and from these data the electrical conductivity sigma was estimated. The PEF-induced damage results in increase of sigma with t(PEF) increasing and attains its saturation level sigma approximately sigma(max) at long time of PEF treatment. The value of sigma(max) reflects the efficiency of damage. The reduced efficiency of damage at suspension volume concentration higher than phi(Y) approximately 32 vol% is explained by the percolation phenomenon in the randomly packed suspension of near-spherical cells. The higher cytoplasmic ions leakage was observed in presence of surfactant. Experiments were carried out in the static and continuous flow treatment chambers in order to reveal the effects of mixing in PEF-treatment efficiency. A noticeable aggregation of the yeast cells was observed in the static flow chamber during the PEF treatment, while aggregation was not so pronounced in the continuous flow chamber. The nature of the enhanced aggregation under the PEF treatment was revealed by the zeta-potential measurements: these data demonstrate different zeta-potential signs for alive and dead cells. The effect of the electric field strength on the PEF-induced extraction of the intracellular components of S. cerevisiae is discussed. PMID:16690074

  2. Impact of a pulsed electric field on damage of plant tissues: effects of cell size and tissue electrical conductivity.

    PubMed

    Ben Ammar, J; Lanoisellé, J-L; Lebovka, N I; Van Hecke, E; Vorobiev, E

    2011-01-01

    Efficiency of pulsed electric field (PEF) induced permeabilization at 293 K in selected fruit and vegetable plant tissues (apple, potato, carrot, courgette, orange, and banana) at electric field strength (E) of 400 V·cm(-1), 1000 V·cm(-1) and pulse duration (t(p)) of 1000 μs was studied experimentally. The mean cell radius (〈r〉) was within 30 to 60 μm, and the ratio of electrical conductivities of the intact and damaged tissues (σ(i)/σ(d)) was within 0.07 to 0.79 for the studied tissues. Electroporation theory predicts higher damage for tissue with larger cells; however, the direct correlation between PEF damage efficiency and size of cell was not always observed. To explain this anomaly, a theoretical Monte Carlo model was developed and checked for parameters typical for potato tissue. The model showed a strong dependence of PEF damage efficiency and power consumption (W) on σ(i)/σ(d) ratio. The optimum value of electric field strength (E(opt)) was an increasing function of σ(i)/σ(d), and plant tissues with high σ(i)/σ(d) ratio (σ(i)/σ(d) ≈ 1) required application of a rather strong field (for example, E(opt) ≈ 3000 V·cm(-1) for σ(i)/σ(d) ≈ 0.8). However, the PEF treatment at a lower field (E ≈ 400 V·cm(-1)) allowed regulation of the selectivity of damage of cells in dependence of their size. A good qualitative correspondence between experimental data and simulation results were observed. PMID:21535680

  3. Cells exposed to nanosecond electrical pulses exhibit biomarkers of mechanical stress

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Moen, Erick K.; Glickman, Randolph D.

    2015-03-01

    Exposure of cells to very short (<1 μs) electric pulses in the megavolt/meter range have been shown to cause disruption of the plasma membrane. This disruption is often characterized by the formation of numerous small pores (<2 nm in diameter) in the plasma membrane that last for several minutes, allowing the flow of ions into the cell. These small pores are called nanopores and the resulting damage to the plasma membrane is referred to as nanoporation. Nanosecond electrical pulse (nsEP) exposure can impart many different stressors on a cell, including electrical, electro-chemical, and mechanical stress. Thus, nsEP exposure is not a "clean" insult, making determination of the mechanism of nanoporation quite difficult. We hypothesize that nsEP exposure creates acoustic shock waves capable of causing nanoporation. Microarray analysis of primary adult human dermal fibroblasts (HDFa) exposed to nsEP, indicated several genes associated with mechanical stress were selectively upregulated 4 h post exposure. The idea that nanoporation is caused by external mechanical force from acoustic shock waves has, to our knowledge, not been investigated. This work will critically challenge the existing paradigm that nanoporation is caused solely by an electric-field driven event and could provide the basis for a plausible explanation for electroporation.

  4. High resolution in-operando microimaging of solar cells with pulsed electrically-detected magnetic resonance.

    PubMed

    Katz, Itai; Fehr, Matthias; Schnegg, Alexander; Lips, Klaus; Blank, Aharon

    2015-02-01

    The in-operando detection and high resolution spatial imaging of paramagnetic defects, impurities, and states becomes increasingly important for understanding loss mechanisms in solid-state electronic devices. Electron spin resonance (ESR), commonly employed for observing these species, cannot meet this challenge since it suffers from limited sensitivity and spatial resolution. An alternative and much more sensitive method, called electrically-detected magnetic resonance (EDMR), detects the species through their magnetic fingerprint, which can be traced in the device's electrical current. However, until now it could not obtain high resolution images in operating electronic devices. In this work, the first spatially-resolved electrically-detected magnetic resonance images (EDMRI) of paramagnetic states in an operating real-world electronic device are provided. The presented method is based on a novel microwave pulse sequence allowing for the coherent electrical detection of spin echoes in combination with powerful pulsed magnetic-field gradients. The applicability of the method is demonstrated on a device-grade 1-μm-thick amorphous silicon (a-Si:H) solar cell and an identical device that was degraded locally by an electron beam. The degraded areas with increased concentrations of paramagnetic defects lead to a local increase in recombination that is mapped by EDMRI with ∼20-μm-scale pixel resolution. The novel approach presented here can be widely used in the nondestructive in-operando three-dimensional characterization of solid-state electronic devices with a resolution potential of less than 100 nm. PMID:25557860

  5. Improved temporal coding of sinusoids in electric stimulation of the auditory nerve using desynchronizing pulse trains

    NASA Astrophysics Data System (ADS)

    Litvak, Leonid M.; Delgutte, Bertrand; Eddington, Donald K.

    2003-10-01

    Rubinstein et al. [Hearing Res. 127, 108-118 (1999)] suggested that the representation of electric stimulus waveforms in the temporal discharge patterns of auditory-nerve fiber (ANF) might be improved by introducing an ongoing, high-rate, desynchronizing pulse train (DPT). To test this hypothesis, activity of ANFs was studied in acutely deafened, anesthetized cats in response to 10-min-long, 5-kpps electric pulse trains that were sinusoidally modulated for 400 ms every second. Two classes of responses to sinusoidal modulations of the DPT were observed. Fibers that only responded transiently to the unmodulated DPT showed hyper synchronization and narrow dynamic ranges to sinusoidal modulators, much as responses to electric sinusoids presented without a DPT. In contrast, fibers that exhibited sustained responses to the DPT were sensitive to modulation depths as low as 0.25% for a modulation frequency of 417 Hz. Over a 20-dB range of modulation depths, responses of these fibers resembled responses to tones in a healthy ear in both discharge rate and synchronization index. This range is much wider than the dynamic range typically found with electrical stimulation without a DPT, and comparable to the dynamic range for acoustic stimulation. These results suggest that a stimulation strategy that uses small signals superimposed upon a large DPT to encode sounds may evoke temporal discharge patterns in some ANFs that resemble responses to sound in a healthy ear.

  6. High resolution in-operando microimaging of solar cells with pulsed electrically-detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Katz, Itai; Fehr, Matthias; Schnegg, Alexander; Lips, Klaus; Blank, Aharon

    2015-02-01

    The in-operando detection and high resolution spatial imaging of paramagnetic defects, impurities, and states becomes increasingly important for understanding loss mechanisms in solid-state electronic devices. Electron spin resonance (ESR), commonly employed for observing these species, cannot meet this challenge since it suffers from limited sensitivity and spatial resolution. An alternative and much more sensitive method, called electrically-detected magnetic resonance (EDMR), detects the species through their magnetic fingerprint, which can be traced in the device's electrical current. However, until now it could not obtain high resolution images in operating electronic devices. In this work, the first spatially-resolved electrically-detected magnetic resonance images (EDMRI) of paramagnetic states in an operating real-world electronic device are provided. The presented method is based on a novel microwave pulse sequence allowing for the coherent electrical detection of spin echoes in combination with powerful pulsed magnetic-field gradients. The applicability of the method is demonstrated on a device-grade 1-μm-thick amorphous silicon (a-Si:H) solar cell and an identical device that was degraded locally by an electron beam. The degraded areas with increased concentrations of paramagnetic defects lead to a local increase in recombination that is mapped by EDMRI with ∼20-μm-scale pixel resolution. The novel approach presented here can be widely used in the nondestructive in-operando three-dimensional characterization of solid-state electronic devices with a resolution potential of less than 100 nm.

  7. Influence of electric current pulses on the solidification of Cu-Bi-Sn immiscible alloys

    PubMed Central

    Hongxiang, Jiang; Jie, He; Jiuzhou, Zhao

    2015-01-01

    Continuous solidification experiments were carried out with Cu-Bi-Sn alloys under the effects of Electric Current Pulses (ECPs). A model describing the microstructure evolution was developed. The formation of the microstructure in the continuously solidified alloys was calculated. The calculations demonstrated that ECPs mainly affect the solidification process through changing the energy barrier for the nucleation of the minority phase droplets (MPDs). When the matrix liquid has a lower electric conductivity compared to the MPD, the ECPs lead to a decrease in the energy barrier for the nucleation of the MPDs which then promote the formation of a finely dispersed microstructure. When the matrix liquid has a higher electric conductivity compared to the MPD, the ECPs cause an increase in the energy barrier for the nucleation and lead to the formation of a phase segregated microstructure. PMID:26228180

  8. Structural properties and digestibility of pulsed electric field treated waxy rice starch.

    PubMed

    Zeng, Feng; Gao, Qun-Yu; Han, Zhong; Zeng, Xin-An; Yu, Shu-Juan

    2016-03-01

    Waxy rice starch was subjected to pulsed electric field (PEF) treatment at intensity of 30, 40 and 50kVcm(-1). The impact of PEF treatment on the granular morphology, molecular weight, semi-crystalline structure, thermal properties, and digestibility were investigated. The micrographs suggested that electric energy could act on the granule structure of starch granule, especially at high intensity of 50kVcm(-1). Gelatinization onset temperature, peak temperature, conclusion temperature and enthalpy value of PEF treated starches were lower than that of native starch. The 9nm lamellar peak of PEF treated starches decreased as revealed by small angle X-ray scattering. The relative crystallinity of treated starches decreased as the increase of electric field intensity. Increased rapidly digestible starch level and decreased slowly digestible starch level was found on PEF treated starches. These results would imply that PEF treatment induced structural changes in waxy rice starch significantly affected its digestibility. PMID:26471687

  9. Apoptosis induction with electric pulses - A new approach to cancer therapy with drug free

    SciTech Connect

    Tang, Liling; Yao, Chenguo; Sun, Caixin

    2009-12-25

    Electrical pulses have been widely used in biomedical fields, whose applications depend on the parameters such as durations and electric intensity. Conventional electroporation (0.1-1 kV/cm, 100 {mu}s) has been used in cell fusion, transfection and electrochemotherapy. Recent studies with high-intensity (MV/cm) electric field applications with durations of several tens of nanoseconds can affect intracellular signal transduction and intracellular structures with plasma intact, resulting in an application of intracellular manipulation. The most recent development is the finding that parameters between those two ranges could be used to induce apoptosis of cancer cells. Proposal of apoptosis induction and tumor inhibition has advantages to pursue the treatment of cancer free of cytotoxic drugs.

  10. Pulsed electric fields for burn wound disinfection in a murine model.

    PubMed

    Golberg, Alexander; Broelsch, G Felix; Vecchio, Daniela; Khan, Saiqa; Hamblin, Michael R; Austen, William G; Sheridan, Robert L; Yarmush, Martin L

    2015-01-01

    Emerging bacterial resistance renders many antibiotics ineffective, making alternative strategies of wound disinfection important. Here the authors report on a new, physical burn wound disinfection method: pulsed electric fields (PEFs). High voltage, short PEFs create nonthermal, permanent damage to cell membranes, possibly by irreversible electroporation. In medicine, PEF technology has recently been used for nonthermal ablation of solid tumors. The authors have expanded the spectrum of PEF applications in medicine to burn wound disinfection. A third-degree burn was induced on the dorsal skin of C57BL/6 mice. Immediately after the injury, the burn wound was infected with Acinetobacter baumannii expressing the luxCDABE operon. Thirty minutes after infection, the infected areas were treated with 80 pulses delivered at 500 V/mm, 70 μs, 1 Hz. The authors used bioluminescence to quantify bacteria on skin. Three animals were used for each experimental condition. PEFs were effective in the disinfection of infected burned murine skin. The bacterial load reduction correlated with the number of delivered pulses. Forty pulses of 500 V/mm led to a 2.04 ± 0.29 Log10 reduction in bacterial load; 80 pulses led to the immediate 5.53 ± 0.30 Log10 reduction. Three hours after PEF, the bacterial reduction of the skin treated with 500 V/mm, 80 pulses was 4.91 ± 0.71 Log10. The authors introduce a new method of wound disinfection using high voltage, short PEFs. They believe that PEF technology may represent an important alternative to antibiotics in addressing bacterial contamination of wounds, particularly those contaminated with multidrug-resistant bacteria. PMID:25167374

  11. Electrical pulse induced biological effects using dielectric spectroscopy and mathematical models

    NASA Astrophysics Data System (ADS)

    Garner, Allen Lawrence

    This dissertation studies the effects of pulsed electric fields (PEFs) on biological cells by measuring the changes in the electrical properties of the pulsed cells and mathematically modeling avascular tumor growth, cell population dynamics, and Ohmic heating. These issues are critical because of the recent use of intense ultrashort PEFs for various biological and medical applications. Recent research using PEFs for tumor treatment motivated an investigation of a simple model for the growth of an avascular tumor. We modeled tumor growth before and after necrotic core formation by incorporating spatial dependence into a one dimensional scaling law. This model emphasized the importance of cell metabolic rate in determining the final steady state size of the tumor. Experimental results showing changes in cell survival and cell cycle due to PEFs led to an investigation of a simple mathematical model for cell population dynamics that considered the cells to be proliferating (dividing) or quiescent (resting). Although some cell populations apparently reached steady state quickly, the proliferating cell population fell below one, meaning that the overall cell population would eventually decay away. This result, which was unaltered by including a transition from the quiescent to proliferating state, emphasized the importance of targeting proliferating cells for successful cancer treatments. Time domain dielectric spectroscopy was used to measure the electrical properties of a biological cell suspension over a wide frequency range with a single pulse following multiple PEFs. Fitting the dielectric properties of a cancer cell (Jurkat) suspension to a double shell model yielded the dielectric parameters of the cell membrane, cytoplasm, nuclear envelope, and nucleoplasm. Decreased cytoplasm and nucleoplasm conductivity and increased suspension conductivity suggestion transport from the cell interior to the exterior consistent with electroporation. Reduced cell membrane

  12. Controlling micro-sized droplet generation using electrical pulses for studying liquid-liquid systems

    NASA Astrophysics Data System (ADS)

    Fernandino, M.; La Forgia, N.; Vera, A. J.; Bjerknes, J.; Dorao, C. A.

    2014-04-01

    Water droplets removal from oil is a critical process in several industries, in particular in the oil and gas industry. Water/oil separation is commonly done in large gravitational sedimentation tanks, which are over dimensioned due to the lack of accurate models to allow for optimization. This can become challenging for off-shore and subsea processing installations. One of the bottlenecks to study droplet dynamics in the micron range, is the generation of droplets with less than 100μm in diameter. In this regard, one of the most promising techniques for controlling the generated droplet size is based on the use of a high voltage electrical signal or electro-hydrodynamic technique (EHD). Although much work on EHD and droplet generation can been found in the literature, many challenges still remain. One of this is the generation of droplets smaller than 100μm in diameter in a controllable, on-demand manner. In this work, the effect of the meniscus shape and the electric pulse characteristics on the size of the generated droplet is investigated. Both the meniscus height and width help to determine the droplet size, with the latter having a stronger effect. No significant influence of the pulse amplitude and pulse width was observed for the tested conditions.

  13. Pre-breakdown processes in a dielectric fluid in inhomogeneous pulsed electric fields

    SciTech Connect

    Shneider, Mikhail N.; Pekker, Mikhail

    2015-06-14

    We consider the development of pre-breakdown cavitation nanopores appearing in the dielectric fluid under the influence of the electrostrictive stresses in the inhomogeneous pulsed electric field. It is shown that three characteristic regions can be distinguished near the needle electrode. In the first region, where the electric field gradient is greatest, the cavitation nanopores, occurring during the voltage nanosecond pulse, may grow to the size at which an electron accelerated by the field inside the pores can acquire enough energy for excitation and ionization of the liquid on the opposite pore wall, i.e., the breakdown conditions are satisfied. In the second region, the negative pressure caused by the electrostriction is large enough for the cavitation initiation (which can be registered by optical methods), but, during the voltage pulse, the pores do not reach the size at which the potential difference across their borders becomes sufficient for ionization or excitation of water molecules. And, in the third, the development of cavitation is impossible, due to an insufficient level of the negative pressure: in this area, the spontaneously occurring micropores do not grow and collapse under the influence of surface tension forces. This paper discusses the expansion dynamics of the cavitation pores and their most probable shape.

  14. Pre-breakdown processes in a dielectric fluid in inhomogeneous pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Shneider, Mikhail N.; Pekker, Mikhail

    2015-06-01

    We consider the development of pre-breakdown cavitation nanopores appearing in the dielectric fluid under the influence of the electrostrictive stresses in the inhomogeneous pulsed electric field. It is shown that three characteristic regions can be distinguished near the needle electrode. In the first region, where the electric field gradient is greatest, the cavitation nanopores, occurring during the voltage nanosecond pulse, may grow to the size at which an electron accelerated by the field inside the pores can acquire enough energy for excitation and ionization of the liquid on the opposite pore wall, i.e., the breakdown conditions are satisfied. In the second region, the negative pressure caused by the electrostriction is large enough for the cavitation initiation (which can be registered by optical methods), but, during the voltage pulse, the pores do not reach the size at which the potential difference across their borders becomes sufficient for ionization or excitation of water molecules. And, in the third, the development of cavitation is impossible, due to an insufficient level of the negative pressure: in this area, the spontaneously occurring micropores do not grow and collapse under the influence of surface tension forces. This paper discusses the expansion dynamics of the cavitation pores and their most probable shape.

  15. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    NASA Astrophysics Data System (ADS)

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-05-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry.

  16. Computer modeling and experimental study of non-chain pulsed electric-discharge DF laser.

    PubMed

    Ruan, Peng; Xie, Jijiang; Zhang, Laiming; Guo, Jin; Xie, Jingjiang; Yang, Guilong; Li, Dianjun; Pan, Qikun; Tan, Gaijuan; Meng, Fanjiang; Li, Shiming

    2012-12-17

    Computer simulation and experimental study of a pulsed electrical-discharge DF laser pumped by the SF(6)-D(2) non-chain reaction are presented. The computer model encompassing 28 reactions is based on laser rate equations theory, and applied to approximately describe the chemical processes of non-chain DF laser. A comprehensive study of the dependence of number density on time for all particles in the gain area is conducted by numerical calculation adopting Runge-Kutta method. The output performance of non-chain pulsed DF laser as a function of the output mirror reflectivity and the mixture ratio are analyzed. The calculation results are compared with experimental data, showing good agreement with each other. Both the theoretical analysis and experimental results present that the laser output performance can be improved by optimizing the mixture ratio and output mirror reflectivity. The optimum values of mixture ratio and output mirror reflectivity are respectively 10:1 and 30%. The single pulse energy of 4.95J, pulse duration of 148.8ns and peak power of 33.27 MW are achieved under the optimum conditions. PMID:23263131

  17. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs).

    PubMed

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-01-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry. PMID:27181521

  18. [Simulation Analysis of the Pulse Signal on the Electricity Network of Cardiovascular System].

    PubMed

    Liu, Ying; Yin, Yanfei; Zhang, Defa; Wang, Menghong; Bi, Yongqiang

    2015-12-01

    Pulse waves contain abundant physiological and pathological information of human body. Research of the relationship between pulse wave and human cardiovascular physiological parameters can not only help clinical diagnosis and treatment of cardiovascular diseases, but also contribute to develop many new medical instruments. Based on the traditional double elastic cavity model, the human cardiovascular system was established by using the electric network model in this paper. The change of wall pressure and blood flow in artery was simulated. And the influence of the peripheral resistance and vessel compliance to the distribution of blood flow in artery was analyzed. The simulation results were compared with the clinical monitoring results to predict the physiological and pathological state of human body. The result showed that the simulation waveform of arterial wall pressure and blood flow was stabile after the second cardiac cycle. With the increasing of peripheral resistance, the systolic blood pressure of artery increased, the diastolic blood pressure had no significant change, and the pulse pressure of artery increased gradually. With the decreasing of vessel compliance, the vasoactivity became worse and the pulse pressure increased correspondingly. The simulation results were consistent with the clinical monitoring results. The increasing of peripheral resistance and decreasing of vascular compliance indicated that the incidence of hypertension and atherosclerosis was increased. PMID:27079088

  19. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    PubMed Central

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-01-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry. PMID:27181521

  20. Dynamical studies of model membrane and cellular response to nanosecond, high-intensity pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Hu, Qin

    The dynamics of electroporation of biological cells subjected to nanosecond, high intensity pulses are studied based on a coupled scheme involving the current continuity and Smoluchowski equations. The improved pore formation energy model includes a dependence on pore population and density. It also allows for variable surface tension and incorporates the effects of finite conductivity on the electrostatic correction term, which was not considered by the simple energy models in the literature. It is shown that E(r) becomes self-adjusting with variations in its magnitude and profile. The whole scheme is self-consistent and dynamic. An electromechanical analysis based on thin-shell theory is presented to analyze cell shape changes in response to external electric fields. The calculations demonstrate that at large fields, the spherical cell geometry can be modified, and even ellipsoidal forms may not be appropriate to account for the resulting shape. It is shown that, in keeping with reports in the literature, the final shape depends on membrane thickness. This has direct implications for tissues in which significant molecular restructuring can occur. This study is also focused on obtaining qualitative predictions of pulse width dependence to apoptotic cell irreversibility that has been observed experimentally. The analysis couples a distributed electrical model for current flow with the Smoluchowski equation to provide self-consistent, time-dependent transmembrane voltages. The model captures the essence of the experimentally observed pulse-width dependence, and provides a possible physical picture that depends only on the electrical trigger. Different cell responses of normal and malignant (Farage) tonsillar B-cell are also compared and discussed. It is shown that subjecting a cell to an ultrashort, high-intensity electric pulse is the optimum way for reversible intracellular manipulation. Finally, a simple but physical atomistic model is presented for molecular

  1. Discharge processes of UV pre-ionized electric-discharge pulsed DF laser

    NASA Astrophysics Data System (ADS)

    Pan, Qikun; Xie, Jijiang; Shao, Chunlei; Wang, Chunrui; Shao, Mingzhen; Guo, Jin

    2016-03-01

    The discharge processes of ultraviolet (UV) pre-ionized electric-discharge pulsed DF laser operating with a SF6-D2 gas mixture are studied. A mathematical model based on continuity equation of electrons and Kirchhoff equations for discharge circuit is established to describe the discharge processes. Voltage and current waveforms of main discharge and voltage waveforms of pre-ionization are solved numerically utilizing the model. The calculations correctly display some physical processes, such as the delay time between pre-ionization and main discharge, breakdown of the main electrode and self-sustained volume discharge (SSVD). The results of theory are consistent with the experiments, which are performed in our non-chain pulsed DF laser. Then the delay inductance and peak capacitance are researched to analyze their influences on discharge processes, and the circuit parameters of DF laser are given which is useful to improve the discharge stability.

  2. Autocorrelation measurement of an ultra-short optical pulse using an electrically focus-tunable lens

    NASA Astrophysics Data System (ADS)

    Serna, Juan; Hamad, Abdullatif; Rueda, Edgar; Garcia, Hernando

    2015-10-01

    In this communication, a novel technique to measure the temporal width of an ultra-short optical pulse using an electrically focus-tunable lens (EFTL) is proposed and implemented (no need for a mechanical translation stage). The principle is based on the time delay experienced by the pulse when it passes through the deformed membrane of the EFTL as the focal length changes by an applied current. The resolution of the system is approximately 0.23 fs, with a total time delay of 0.69 ps. A typical autocorrelation can be performed in less than 5 s with an excellent Signal to Noise Ratio. The same technique can be implemented to study ultrafast phenomena like electronic relaxation or ultrafast fluorescence in a pump-probe configuration.

  3. Inactivation of Penicillum expansum in sour cherry juice, peach and apricot nectars by pulsed electric fields.

    PubMed

    Evrendilek, Gulsun Akdemir; Tok, Fatih M; Soylu, E Mine; Soylu, Soner

    2008-08-01

    Inhibitory effects of pulsed electric fields (PEF) on Penicillum expansum inoculated into sour cherry juice, apricot and peach nectars were determined based on germination tube elongation, spore germination rate, and light and scanning electron microscopy (SEM) observations in this study. After inoculation of juice/nectar samples with P. expansum spores at the level of 10(5)-10(6)cfu/mL, the samples were processed by bench scale PEF pulse generator as a function of differing electric field strengths (0, 13, 17, 20, 23, 27, 30 and 34kV/cm) and processing times (0, 62, 94, 123, 163, 198 and 218mus). Results revealed that with an increase in electric field strength and processing time, germination tube elongation and spore germination rate were completely inhibited. Light and SEM observations revealed considerable morphological alterations in fungal conidia such as cytoplasmic coagulation, vacuolations, shrinkage and protoplast leakage. PEF processing of juice/nectars was demonstrated to be effective in inactivating P. expansum. To our knowledge, this is the first study confirming the inhibitory effects of PEF on germination tube elongation and spore germination rate of P. expansum in fruit juice/nectars. PMID:18541164

  4. Biophysical Studies of Nanosecond Pulsed Electric Field Induced Cell Membrane Permeabilization

    NASA Astrophysics Data System (ADS)

    Wu, Yu-Hsuan

    Nanosecond megavolts-per-meter pulsed electric field (nsPEF) offers a non-invasive manipulation of intracellular organelles and functions of biological cells. Accordingly, nsPEF is a potential technique for biophysical research and cancer therapy, and is of growing interest. Although, the application of nsPEF has shown electroperturbation on cell plasma membranes and intracellular membranes as well, the mechanisms underlying the electropermeabilization are still not clear. In this thesis, we systematically study nsPEFs (5 and 30 ns) induced membrane permeability change in biological cell in-vitro with different pulse parameters. In Chapter 3, we investigate the nsPEF-induced intracellular membrane permeabilization of mitochondria which play key roles in activating apoptosis in mammalian cells. The results show the evidences of nsPEF-induced membrane permeability increase in mitochondria, and suggest that nsPEF is a potential technology for cancer cell ablation without delivery of drug or gene into cells. In Chapter 2, 4 and 6, we study the properties of nsPEF-induced plasma membrane permeabilization. In the beginning, the change of plasma membrane permeability is studied by uptake of YO-PRO-1 and propidium iodide, fluorescent dyes specifically used as indicators of plasma membrane permeabilization. However, the detection is limited by the fluorescent emission efficiency and detector capability. To increase the detection sensitivity, we later develop a method based on cell volume change due to regulation of osmotic balance that causes water and small ions transport through plasma membrane. We find that even a single 10 MV/m pulse of 5 ns duration produces measureable cell swelling. The results demonstrate that cell swelling is susceptible to nsPEF and can detect membrane permeabilization more easily and precisely than fluorescent dyes. We compare the effects of different pulse parameters (pulse duration, pulse number, electric field amplitude and pulse repetition

  5. Rhodamine B as an optical thermometer in cells focally exposed to infrared laser light or nanosecond pulsed electric fields

    PubMed Central

    Moreau, David; Lefort, Claire; Burke, Ryan; Leveque, Philippe; O’Connor, Rodney P.

    2015-01-01

    The temperature-dependent fluorescence property of Rhodamine B was used to measure changes in temperature at the cellular level induced by either infrared laser light exposure or high intensity, ultrashort pulsed electric fields. The thermal impact of these stimuli were demonstrated at the cellular level in time and contrasted with the change in temperature observed in the extracellular bath. The method takes advantage of the temperature sensitivity of the fluorescent dye Rhodamine B which has a quantum yield linearly dependent on temperature. The thermal effects of different temporal pulse applications of infrared laser light exposure and of nanosecond pulsed electric fields were investigated. The temperature increase due to the application of nanosecond pulsed electric fields was demonstrated at the cellular level. PMID:26504658

  6. Rhodamine B as an optical thermometer in cells focally exposed to infrared laser light or nanosecond pulsed electric fields.

    PubMed

    Moreau, David; Lefort, Claire; Burke, Ryan; Leveque, Philippe; O'Connor, Rodney P

    2015-10-01

    The temperature-dependent fluorescence property of Rhodamine B was used to measure changes in temperature at the cellular level induced by either infrared laser light exposure or high intensity, ultrashort pulsed electric fields. The thermal impact of these stimuli were demonstrated at the cellular level in time and contrasted with the change in temperature observed in the extracellular bath. The method takes advantage of the temperature sensitivity of the fluorescent dye Rhodamine B which has a quantum yield linearly dependent on temperature. The thermal effects of different temporal pulse applications of infrared laser light exposure and of nanosecond pulsed electric fields were investigated. The temperature increase due to the application of nanosecond pulsed electric fields was demonstrated at the cellular level. PMID:26504658

  7. Pulse

    MedlinePlus

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the patient's heart is pumping. ... rate gives information about your fitness level and health.

  8. Deformation mechanism transition caused by strain rate in a pulse electric brush-plated nanocrystalline Cu

    NASA Astrophysics Data System (ADS)

    Jiang, Zhonghao; Zhang, Hanzhuo; Gu, Changdong; Jiang, Qing; Lian, Jianshe

    2008-09-01

    Bulk nanocrystalline Cu was synthesized by a pulse electric brush-plating technique. A very large strength (at 2% plastic strain) increase from 644 to 1451 MPa was obtained by compression tests at room temperature and strain rates from 1×10-5 to 3×100 s-1. A transition in plastic deformation mechanism with strain rate from a combination of the thermally activated grain boundary sliding and the dislocation emission-absorption in grain boundaries to one dominated by the dislocation activity has been revealed by the significant changes in strain rate sensitivity and apparent activation volume with strain rate.

  9. Effect of repetitive laser pulses on the electrical conductivity of intervertebral disc tissue

    SciTech Connect

    Omel'chenko, A I; Sobol', E N

    2009-03-31

    The thermomechanical effect of 1.56-{mu}m fibre laser pulses on intervertebral disc cartilage has been studied using ac conductivity measurements with coaxial electrodes integrated with an optical fibre for laser radiation delivery to the tissue. The observed time dependences of tissue conductivity can be interpreted in terms of hydraulic effects and thermomechanical changes in tissue structure. The laserinduced changes in the electrical parameters of the tissue are shown to correlate with the structural changes, which were visualised using shadowgraph imaging. Local ac conductivity measurements in the bulk of tissue can be used to develop a diagnostic/monitoring system for laser regeneration of intervertebral discs. (laser biology and medicine)

  10. Bipolaron formation in organic solar cells observed by pulsed electrically detected magnetic resonance.

    PubMed

    Behrends, J; Schnegg, A; Lips, K; Thomsen, E A; Pandey, A K; Samuel, I D W; Keeble, D J

    2010-10-22

    We report the observation of a spin-dependent dark transport current, exhibiting spin coherence at room temperature, in a π-conjugated polymer-fullerene blend using pulsed electrically detected magnetic resonance. The resonance at g = 2.0028(3) is due to polarons in the polymer, and exhibits spin locking at high microwave fields. The presence of an excess of fullerene, and the operating voltage (1 V) used, suppresses negative polaron formation in the polymer. It is concluded that spin-dependent transport is due to the formation of positive bipolarons. PMID:21231063

  11. Mitigation of magnetohydrodynamic electromagnetic pulse (MHD-EMP) effects from commerical electric power systems

    SciTech Connect

    Barnes, P.R. ); Tesche, F.M. , Dallas, TX ); Vance, E.F. , Fort Worth, TX )

    1992-03-01

    A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth's magnetic field and produces a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). This can adversely affect electrical power systems. In this report, the effects of this nuclear environment on critical facilities connected to the commercial power system are considered. Methods of mitigating the MHD-EMP impacts are investigated, and recommended protection schemes are presented. Guidelines for testing facilities to determine the effects of MHD-EMP and to validate the mitigation methods also are discussed.

  12. Diode-Pumped Long-Pulse-Length Ho:Tm:YLiF4 Laser at 10 Hz

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G.; Naranjo, Felipe L.; Barnes, Norman P.; Murray, Keith E.; Lockard, George E.

    1995-01-01

    An optical efficiency of 0.052 under normal mode operation for diode-pumped Ho:Tm:YLiF4 at a pulse repetition frequency of 10 Hz has been achieved. Laser output energy of 30 mJ in single Q-switched pulses with 600-ns pulse length were obtained for an input energy of 3 J. A diffusion-bonded birefringent laser rod consisting of Ho:Tm-doped and undoped pieces of YLF was utilized for 10-Hz operation.

  13. Numerical Simulation on the Liquid Bridge Formation by the Applied Electric Pulse

    NASA Astrophysics Data System (ADS)

    Hong, Jin Seok; Kang, In Seok

    2010-11-01

    In this work, liquid bridge (LB) formation by the applied electric field is analyzed numerically. Numerical simulation captures the temporal behavior of liquid surface during the LB formation between a top plate and a bottom nozzle. Numerical results show the three stages of LB formation; interface elevation, impact/fast spreading and slow spreading/stabilization. The effect of the applied voltage pulse is also studied in terms of minimal electrical energy for LB formation. Non-linear behavior such as bubble trapping at the impact of liquid to plate is also captured and explained qualitatively. Grounded and floating plate is considered. The wetting criterion for LB formation is suggested and explained in terms of capillary pressure. The linear decrease of the final contact radius with the top plate contact angle is shown from the numerical results. In addition, the effects of the liquid properties on the dynamics are briefly discussed.

  14. Electrical and optical properties of vanadium dioxide containing gold nanoparticles deposited by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Orlianges, J.-C.; Leroy, J.; Crunteanu, A.; Mayet, R.; Carles, P.; Champeaux, C.

    2012-09-01

    Nanostructured vanadium dioxide is one of the most interesting and studied member of the vanadates family performing a reversible transition from an insulating state to a metallic state associated with a structural transition when heated above a temperature of 68 °C. On the other hand, noble metal nanoparticles (NPs) support localized surface plasmon resonance which causes selective absorption bands in the visible and near-IR regions. The purpose of this letter is to study structural, optical, and electrical properties of vanadium dioxide thin films containing gold nanoparticles synthetized using pulsed laser deposition process. Thus, we have performed x-ray diffraction, optical transmission, and four point probe electrical measurements to investigate the nanocomposite properties versus its temperature. Interestingly, we have observed switching behavior for VO2 film containing gold NPs with a resistivity contrast of four orders of magnitude and a decrease of its transition temperature.

  15. Study on the Sensitivity of Landmine Electrical Fuse Circuit Under the Interference of Natural Electromagnetic Pulse

    NASA Astrophysics Data System (ADS)

    Qin, Dechun

    Landmine electrical fuse circuits on the battlefield will be interfered by natural electromagnetic pulse such as electrostatic discharge and lightning, which will undermine the circuit performance and trigger the early burst or mistaken burst of the landmines. In this paper, numerically simulation analysis is conducted on the electrostatic and lightning effects received by the landmine fuse circuit by means of building simulation model of the fuse circuit and analyzing the electric and magnetic field changes of the observation The mechanism of the influence of electrostatic discharge and lightning on the sensitivity of the fuse circuit is explored. The conclusion is that electrostatic effect cause the mistaken burst of the landmines by enabling the interference voltage to reach the components turn-on threshold and cause the circuit malfunction, and lighting effect by long period accumulation of energy.

  16. Simulations of intracellular calcium release dynamics in response to a high-intensity, ultrashort electric pulse

    NASA Astrophysics Data System (ADS)

    Joshi, R. P.; Nguyen, A.; Sridhara, V.; Hu, Q.; Nuccitelli, R.; Beebe, S. J.; Kolb, J.; Schoenbach, K. H.

    2007-04-01

    Numerical simulations for electrically induced, intracellular calcium release from the endoplasmic reticulum are reported. A two-step model is used for self-consistency. Distributed electrical circuit representation coupled with the Smoluchowski equation yields the ER membrane nanoporation for calcium outflow based on a numerical simulation. This is combined with the continuum Li-Rinzel model and drift diffusion for calcium dynamics. Our results are shown to be in agreement with reported calcium release data. A modest increase (rough doubling) of the cellular calcium is predicted in the absence of extra-cellular calcium. In particular, the applied field of 15kV/cm with 60ns pulse duration makes for a strong comparison. No oscillations are predicted and the net recovery period of about 5min are both in agreement with published experimental results. A quantitative explanation for the lack of such oscillatory behavior, based on the density dependent calcium fluxes, is also provided.

  17. Pulsed electric field (PEF) as an intensification pretreatment for greener solvent lipid extraction from microalgae.

    PubMed

    Zbinden, Mauricio D Antezana; Sturm, Belinda S M; Nord, Ryan D; Carey, William J; Moore, David; Shinogle, Heather; Stagg-Williams, Susan M

    2013-06-01

    Microalgae, with their high lipid content, are a promising feedstock for renewable fuels. Traditionally, human and environmentally toxic solvents have been used to extract these lipids, diminishing the sustainability of this process. Herein, pulsed electric field technology was utilized as a process intensification strategy to enhance lipid extraction from Ankistrodesmus falcatus wet biomass using the green solvent, ethyl acetate. The extraction efficiency for ethyl acetate without PEF was lower (83-88%) than chloroform. In addition, the ethyl acetate exhibited a 2-h induction period, while the chloroform showed no time dependence. Utilizing PEF technology resulted in 90% of the cells being lysed and a significant enhancement in the rate of lipid recovery using ethyl acetate. The increase in lipid recovery was due to the presence of the electric field and not due to temperature effects. The PEF technology uses less energy than other PEF systems reported in the literature. PMID:23297018

  18. Inactivation of spores using pulsed electric field in a pressurized flow system

    SciTech Connect

    Choi, Jaegu; Wang Douyan; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori; Lin Xiaofei; Sato, Hiroshi; Seta, Harumichi; Matsubara, Hitoshi; Saeki, Takeshi

    2008-11-01

    Pulsed electric field (PEF) inactivation is a very effective method to kill bacteria in liquid while avoiding thermal damage. However, only a limited inactivation effect on spores has been reported to date and the possible mechanisms are still unclear. Therefore, a study of inactivation of spores using PEF in a pressurized flow system is reported in this paper. PEF with a maximum magnitude higher than 110 kV/cm and a pulse width of 100 ns has been applied to a carefully designed treatment chamber through which a suspension fluid of 0.5 MPa continuously flows. Using the proposed PEF inactivation method, maximum 6.7 log reductions were achieved for B. subtilis spores that were investigated. These reductions were much greater than those obtained by a heat inactivation approach. Through frequency analysis using the frequency components of the applied pulses and the frequency response of the equivalent circuit of the spore, it was found that most voltage is applied to the outside of the core in the lower frequency and to the inside in the upper frequency. Also, transmission electron microscope micrographs of B. subtilis spores were taken in order to verify the effect of the PEF treatment.

  19. Role of cytoskeleton and elastic moduli in cellular response to nanosecond pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Thompson, Gary L.; Roth, Caleb; Tolstykh, Gleb; Kuipers, Marjorie; Ibey, Bennett L.

    2013-02-01

    Nanosecond pulsed electric fields (nsPEFs) are known to increase cell membrane permeability to small molecules in accordance with dosages. As previous work has focused on nsPEF exposures in whole cells, electrodeformation may contribute to this induced-permeabilization in addition to other biological mechanisms. Here, we hypothesize that cellular elasticity, based upon the cytoskeleton, affects nsPEF-induced decrease in cellular viability. Young's moduli of various types of cells have been calculated from atomic force microscopy (AFM) force curve data, showing that CHO cells are stiffer than non-adherent U937 and Jurkat cells, which are more susceptible to nsPEF exposure. To distinguish any cytoskeletal foundation for these observations, various cytoskeletal reagents were applied. Inhibiting actin polymerization significantly decreased membrane integrity, as determined by relative propidium uptake and phosphatidylserine externalization, upon exposure at 150 kV/cm with 100 pulses of 10 ns pulse width. Exposure in the presence of other drugs resulted in insignificant changes in membrane integrity and 24-hour viability. However, Jurkat cells showed greater lethality than latrunculin-treated CHO cells of comparable elasticity. From these results, it is postulated that cellular elasticity rooted in actin-membrane interaction is only a minor contributor to the differing responses of adherent and non-adherent cells to nsPEF insults.

  20. Enhanced electroporation in plant tissues via low frequency pulsed electric fields: influence of cytoplasmic streaming.

    PubMed

    Asavasanti, Suvaluk; Stroeve, Pieter; Barrett, Diane M; Jernstedt, Judith A; Ristenpart, William D

    2012-01-01

    Pulsed electric fields (PEF) are known to be effective at permeabilizing plant tissues. Prior research has demonstrated that lower pulse frequencies induce higher rates of permeabilization, but the underlying reason for this response is unclear. Intriguingly, recent microscopic observations with onion tissues have also revealed a correlation between PEF frequency and the subsequent speed of intracellular convective motion, i.e., cytoplasmic streaming. In this paper, we investigate the effect of cytoplasmic streaming on the efficacy of plant tissue permeabilization via PEF. Onion tissue samples were treated with Cytochalasin B, a known inhibitor of cytoplasmic streaming, and changes in cellular integrity and viability were measured over a wide range of frequencies and field strengths. We find that at low frequencies (f < 1 Hz), the absence of cytoplasmic streaming results in a 19% decrease in the conductivity disintegration index compared with control samples. Qualitatively, similar results were observed using a microscopic cell viability assay. The results suggest that at low frequencies convection plays a statistically significant role in distributing more conductive fluid throughout the tissue, making subsequent pulses more efficacious. The key practical implication is that PEF pretreatment at low frequency can increase the rate of tissue permeabilization in dehydration or extraction processes, and that the treatment will be most effective when cytoplasmic streaming is most active, i.e., with freshly prepared plant tissues. PMID:22246974

  1. Electrosensitization assists cell ablation by nanosecond pulsed electric field in 3D cultures

    PubMed Central

    Muratori, Claudia; Pakhomov, Andrei G.; Xiao, Shu; Pakhomova, Olga N.

    2016-01-01

    Previous studies reported a delayed increase of sensitivity to electroporation (termed “electrosensitization”) in mammalian cells that had been subjected to electroporation. Electrosensitization facilitated membrane permeabilization and reduced survival in cell suspensions when the electric pulse treatments were split in fractions. The present study was aimed to visualize the effect of sensitization and establish its utility for cell ablation. We used KLN 205 squamous carcinoma cells embedded in an agarose gel and cell spheroids in Matrigel. A local ablation was created by a train of 200 to 600 of 300-ns pulses (50 Hz, 300–600 V) delivered by a two-needle probe with 1-mm inter-electrode distance. In order to facilitate ablation by engaging electrosensitization, the train was split in two identical fractions applied with a 2- to 480-s interval. At 400–600 V (2.9–4.3 kV/cm), the split-dose treatments increased the ablation volume and cell death up to 2–3-fold compared to single-train treatments. Under the conditions tested, the maximum enhancement of ablation was achieved when two fractions were separated by 100 s. The results suggest that engaging electrosensitization may assist in vivo cancer ablation by reducing the voltage or number of pulses required, or by enabling larger inter-electrode distances without losing the ablation efficiency. PMID:26987779

  2. Ventricular myocyte injury by high-intensity electric field: Effect of pulse duration.

    PubMed

    Prado, Luiza Ns; Goulart, Jair T; Zoccoler, Marcelo; Oliveira, Pedro X

    2016-04-01

    Although high-intensity electric fields (HEF) application is currently the only effective therapy available to terminate ventricular fibrillation, it may cause injury to cardiac cells. In this study we determined the relation between HEF pulse length and cardiomyocyte lethal injury. We obtained lethality curves by survival analysis, which were used to determine the value of HEF necessary to kill 50% of cells (E50) and plotted a strength-duration (SxD) curve for lethality with 10 different durations: 0.1, 0.2, 0.5, 1, 3, 5, 10, 20, 35 and 70 ms. For the same durations we also obtained an SxD curve for excitation and established an indicator for stimulatory safeness (stimulation safety factor - SSF) as the ratio between the SxD curve for lethality and one for excitation. We found that the lower the pulse duration, the higher the HEF intensity required to cell death. Contrary to expectations, the highest SSF value does not correspond to the lowest pulse duration but to the one of 0.5 ms. As defibrillation threshold has been described as duration-dependent, our results imply that the use of shorter stimulus duration - instead of the one typically used in the clinic (10 ms) - might increase defibrillation safeness. PMID:26830130

  3. Crystallization of Ti33Cu67 metallic glass under high-current density electrical pulses

    PubMed Central

    2011-01-01

    We have studied the phase and structure evolution of the Ti33Cu67 amorphous alloy subjected to electrical pulses of high current density. By varying the pulse parameters, different stages of crystallization could be observed in the samples. Partial polymorphic nanocrystallization resulting in the formation of 5- to 8-nm crystallites of the TiCu2 intermetallic in the residual amorphous matrix occurred when the maximum current density reached 9.7·108 A m-2 and the pulse duration was 140 μs, though the calculated temperature increase due to Joule heating was not enough to reach the crystallization temperature of the alloy. Samples subjected to higher current densities and higher values of the evolved Joule heat per unit mass fully crystallized and contained the Ti2Cu3 and TiCu3 phases. A common feature of the crystallized ribbons was their non-uniform microstructure with regions that experienced local melting and rapid solidification. PACS: 81; 81.05.Bx; 81.05.Kf. PMID:21871070

  4. Permeabilization of the nuclear envelope following nanosecond pulsed electric field exposure.

    PubMed

    Thompson, Gary L; Roth, Caleb C; Kuipers, Marjorie A; Tolstykh, Gleb P; Beier, Hope T; Ibey, Bennett L

    2016-01-29

    Permeabilization of cell membranes occurs upon exposure to a threshold absorbed dose (AD) of nanosecond pulsed electric fields (nsPEF). The ultimate, physiological bioeffect of this exposure depends on the type of cultured cell and environment, indicating that cell-specific pathways and structures are stimulated. Here we investigate 10 and 600 ns duration PEF effects on Chinese hamster ovary (CHO) cell nuclei, where our hypothesis is that pulse disruption of the nuclear envelope membrane leads to observed cell death and decreased viability 24 h post-exposure. To observe short-term responses to nsPEF exposure, CHO cells have been stably transfected with two fluorescently-labeled proteins known to be sequestered for cellular chromosomal function within the nucleus - histone-2b (H2B) and proliferating cell nuclear antigen (PCNA). H2B remains associated with chromatin after nsPEF exposure, whereas PCNA leaks out of nuclei permeabilized by a threshold AD of 10 and 600 ns PEF. A downturn in 24 h viability, measured by MTT assay, is observed at the number of pulses required to induce permeabilization of the nucleus. PMID:26721436

  5. Morphologically Aligned Cation-Exchange Membranes by a Pulsed Electric Field for Reverse Electrodialysis.

    PubMed

    Lee, Ju-Young; Kim, Jae-Hun; Lee, Ju-Hyuk; Kim, Seok; Moon, Seung-Hyeon

    2015-07-21

    A low-resistance ion-exchange membrane is essential to achieve the high-performance energy conversion or storage systems. The formation methods for low-resistance membranes are various; one of the methods is the ion channel alignment of an ion-exchange membrane under a direct current (DC) electric field. In this study, we suggest a more effective alignment method than the process with the DC electric field. First, an ion-exchange membrane was prepared under a pulsed electric field [alternating current (AC) mode] to enhance the effectiveness of the alignment. The membrane properties and the performance in reverse electrodialysis (RED) were then examined to assess the membrane resistance and ion selectivity. The results show that the membrane electrical resistance (MER) had a lower value of 0.86 Ω cm(2) for the AC membrane than 2.13 Ω cm(2) observed for the DC membrane and 4.30 Ω cm(2) observed for the pristine membrane. Furthermore, RED achieved 1.34 W/m(2) of maximum power density for the AC membrane, whereas that for the DC membrane was found to be 1.14 W/m(2) [a RED stack assembled with CMX, used as a commercial cation-exchange membrane (CEM), showed 1.07 W/m(2)]. Thereby, the novel preparation process for a remarkable low-resistance membrane with high ion selectivity was demonstrated. PMID:26114376

  6. Temporal characteristics of the pulsed electric discharges in small gaps filled with hydrocarbon oil

    NASA Astrophysics Data System (ADS)

    Maradia, U.; Hollenstein, Ch; Wegener, K.

    2015-02-01

    In order to understand the role of electrode materials in electrical discharges with micro gaps (<200 µm) filled with a liquid hydrocarbon dielectric, the post-breakdown phase of low ignition voltage (100 V) and low current (<20 A) pulsed electric discharges is experimentally investigated. The electric discharge energies are selected in the range from 1 to 150 mJ. Due to the non-repetitive and transient nature of the micro-discharges, time-resolved imaging, spectroscopy and electrical analysis of single discharges are performed. The plasma-material interaction is investigated by analysing the erosion craters on anode and cathode. It is found that the electrode materials in these multiphase discharges affect the gas bubble dynamics, the transport properties of the discharge plasmas and the transition from the gaseous to metallic vapour plasma. The change in the energy fractions dissipated in the electrodes in function of the discharge time is influenced by the thermo-physical properties of the electrode materials. The simulation of craters in multiple discharge process requires consideration of the gas bubble dynamics due to different energy fractions and plasma flushing efficiencies.

  7. Morphology and Electric Conductance Change Induced by Voltage Pulse Excitation in (GeTe)2/Sb2Te3 Superlattices.

    PubMed

    Bolotov, Leonid; Saito, Yuta; Tada, Tetsuya; Tominaga, Junji

    2016-01-01

    Chalcogenide superlattice (SL) phase-change memory materials are leading candidates for non-volatile, energy-efficient electric memory where the electric conductance switching is caused by the atom repositioning in the constituent layers. Here, we study the time evolution of the electric conductance in [(GeTe)2/(Sb2Te3)1]4 SLs upon the application of an external pulsed electric field by analysing the structural and electrical responses of the SL films with scanning probe microscopy (SPM) and scanning probe lithography (SPL). At a low pulse voltage (1.6-2.3 V), a conductance switching delay of a few seconds was observed in some SL areas, where the switch to the high conductance state (HCS) is accompanied with an SL expansion under the strong electric field of the SPM probe. At a high pulse voltage (2.5-3.0 V), the HCS current was unstable and decayed in a few seconds; this is ascribed to the degradation of the HCS crystal phase under excessive heating. The reversible conductance change under a pulse voltage of opposite polarity emphasised the role of the electric field in the phase-transition mechanism. PMID:27618797

  8. Electrical and optical characterization of pulsed plasma of N2 H2

    NASA Astrophysics Data System (ADS)

    Martínez, H.; Yousif, F. B.

    2008-03-01

    This paper considers the electrical and optical characterization of glow discharge pulsed plasma in N2/H2 gas mixtures at a pressures range between 0.5 and 4.0 Torr and discharge current between 0.2 and 0.6 A. Electron temperature and ion density measurements were performed employing a double Langmuir probe. They were found to increase rapidly as the H2 percentage in the mixture was increased up to 20%. This increase slows down as the H2 percentage in the gas mixture was increased above 20% at the same pressure. Emission spectroscopy was employed to observe emission from the pulsed plasma of a steady-state electric discharge. The discharge mainly emits within the range 280 500 nm. The emission consists of N2 (C-X) 316, 336, 358 nm narrow peaks and a broad band with a maximum at λmax = 427 nm. Also lines of N2, N2 + and NH excited states were observed. All lines and bands have their maximum intensity at the discharge current of 0.417 A. The intensities of the main bands and spectral lines are determined as functions of the total pressure and discharge current. Agreement with other theoretical and experimental groups was established.

  9. Pulsed electric field pretreatment of rapeseed green biomass (stems) to enhance pressing and extractives recovery.

    PubMed

    Yu, X; Gouyo, T; Grimi, N; Bals, O; Vorobiev, E

    2016-01-01

    The objective of this study was to investigate the effects of pulsed electric field (PEF) pretreatment on the valorization of extractives (proteins and polyphenols) from rapeseed green biomass (stems) by pressing. The effect of pressure, electric field strength and pulse number on the juice expression yield, total polyphenols and total proteins content in the expressed juices were studied. Experiments conducted under optimal conditions (E = 8 kV/cm, tPEF = 2 ms, P = 10 bar) permitted to increase the juice expressed yield from 34% to 81%. Significant increases in total polyphenols content (0.48 vs. 0.10 g GAE/100g DM), in total proteins content (0.14 vs. 0.07 g BSA/100g DM) and in consolidation coefficient (9.0 × 10(-8) vs. 2.2 × 10(-8)m(2)/s) were also observed after PEF pretreatment. The recovered press cake was well dehydrated with an increase of dry matter content from 8.8% to 53.0%. PMID:26341008

  10. The Influence of Vesicle Shape and Medium Conductivity on Possible Electrofusion under a Pulsed Electric Field

    PubMed Central

    Liu, Linying; Mao, Zheng; Zhang, Jianhua; Liu, Na; Liu, Qing Huo

    2016-01-01

    The effects of electric field on lipid membrane and cells have been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest due to their wide use in cell biology and biotechnology. However, numerical studies on the electrofusion of cells (or vesicles) with different deformed shapes are still rare. Vesicle, being of cell size, can be treated as a simple model of cell to investigate the behaviors of cell in electric field. Based on the finite element method, we investigate the effect of vesicle shape on electrofusion of contact vesicles in various medium conditions. The transmembrane voltage (TMV) and pore density induced by a pulsed field are examined to analyze the possibility of vesicle fusion. In two different medium conditions, the prolate shape is observed to have selective electroporation at the contact area of vesicles when the exterior conductivity is smaller than the interior one; selective electroporation is more inclined to be found at the poles of the oblate vesicles when the exterior conductivity is larger than the interior one. Furthermore, we find that when the exterior conductivity is lower than the internal conductivity, the pulse can induce a selective electroporation at the contact area between two vesicles regardless of the vesicle shape. Both of these two findings have important practical applications in guiding electrofusion experiments. PMID:27391692

  11. An investigation for structure transformation in electric pulse modified liquid aluminum

    NASA Astrophysics Data System (ADS)

    Qi, Jingang; Wang, Jianzhong; He, Lijia; Zhao, Zuofu; Du, Huiling

    2011-02-01

    The electric pulse (EP) modification of liquid metal is a novel method for grain refinement. In this work, the structure tests of EP-modified liquid aluminum were conducted and investigated using high-temperature X-ray diffractometer by virtue of the outstanding structural heredity of EP-modified liquid aluminum. The results show that the EP-modified liquid structure tends to be slack and unordered with increasing temperature similar to that of the unmodified. Nevertheless, the quantitative characterization denoted by the liquid structural parameters exhibits its discrepancy. At the modifying temperature of 750 °C, the order of degree of EP-modified liquid aluminum is remarkably strengthened and the value of average atomic number per cluster changes from 119 (no EP) up to 174 (EP) by an increase of 46%. These tests experimentally testified Wang's electric pulse modification (EPM) model that was built only by phenomenology, and hereby the mechanism of grain refinement resulting from EPM is further elucidated.

  12. Impact of high-intensity pulsed electric fields on carotenoids profile of tomato juice made of moderate-intensity pulsed electric field-treated tomatoes.

    PubMed

    Vallverdú-Queralt, Anna; Odriozola-Serrano, Isabel; Oms-Oliu, Gemma; Lamuela-Raventós, Rosa M; Elez-Martínez, Pedro; Martín-Belloso, Olga

    2013-12-01

    The effect of pulsed electric fields (PEF) on the carotenoid content of tomato juices was studied. First, moderate-intensity PEF (MIPEF) was applied to raw tomatoes. Afterwards, MIPEF-treated and untreated tomatoes were immediately refrigerated at 4 °C for 24 h and then, they were separately ground to produce tomato juices. Juices were treated by heat treatments or by high-intensity PEF (HIPEF) and stored under refrigeration for 56 days. MIPEF treatment of tomatoes increased the content of carotenoid compounds in tomato juices. An enhancement of 63-65% in 15-cis-lycopene was observed in juices prepared with MIPEF-treated tomatoes. A slight increase in cis-lycopene isomers was observed over time, whereas other carotenoids slightly decreased. However, HIPEF treated tomato juices maintained higher carotenoid content (10-20%) through the storage time than thermally and untreated juices. The combination of MIPEF and HIPEF treatments could be used not only to produce tomato juices with high carotenoid content but also, to maintain higher the carotenoid content during storage time. PMID:23871069

  13. Computer modeling of electrical and thermal performance during bipolar pulsed radiofrequency for pain relief

    SciTech Connect

    Pérez, Juan J.; Pérez-Cajaraville, Juan J.; Muñoz, Víctor; Berjano, Enrique

    2014-07-15

    Purpose: Pulsed RF (PRF) is a nonablative technique for treating neuropathic pain. Bipolar PRF application is currently aimed at creating a “strip lesion” to connect the electrode tips; however, the electrical and thermal performance during bipolar PRF is currently unknown. The objective of this paper was to study the temperature and electric field distributions during bipolar PRF. Methods: The authors developed computer models to study temperature and electric field distributions during bipolar PRF and to assess the possible ablative thermal effect caused by the accumulated temperature spikes, along with any possible electroporation effects caused by the electrical field. The authors also modeled the bipolar ablative mode, known as bipolar Continuous Radiofrequency (CRF), in order to compare both techniques. Results: There were important differences between CRF and PRF in terms of electrical and thermal performance. In bipolar CRF: (1) the initial temperature of the tissue impacts on temperature progress and hence on the thermal lesion dimension; and (2) at 37 °C, 6-min of bipolar CRF creates a strip thermal lesion between the electrodes when these are separated by a distance of up to 20 mm. In bipolar PRF: (1) an interelectrode distance shorter than 5 mm produces thermal damage (i.e., ablative effect) in the intervening tissue after 6 min of bipolar RF; and (2) the possible electroporation effect (electric fields higher than 150 kV m{sup −1}) would be exclusively circumscribed to a very small zone of tissue around the electrode tip. Conclusions: The results suggest that (1) the clinical parameters considered to be suitable for bipolar CRF should not necessarily be considered valid for bipolar PRF, and vice versa; and (2) the ablative effect of the CRF mode is mainly due to its much greater level of delivered energy than is the case in PRF, and therefore at same applied energy levels, CRF, and PRF are expected to result in same outcomes in terms of

  14. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-06-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  15. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-04-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  16. Electromagnetic pulse research on electric power systems: Program summary and recommendations

    SciTech Connect

    Barnes, P.R.; McConnell, B.W.; Van Dyke, J.W. ); Tesche, F.M. , Dallas, TX ); Vance, E.F. , Fort Worth, TX )

    1993-01-01

    A single nuclear detonation several hundred kilometers above the central United States will subject much of the nation to a high-altitude electromagnetic pulse (BENT). This pulse consists of an intense steep-front, short-duration transient electromagnetic field, followed by a geomagnetic disturbance with tens of seconds duration. This latter environment is referred to as the magnetohydrodynamic electromagnetic pulse (NMENT). Both the early-time transient and the geomagnetic disturbance could impact the operation of the nation's power systems. Since 1983, the US Department of Energy has been actively pursuing a research program to assess the potential impacts of one or more BENT events on the nation's electric energy supply. This report summarizes the results of that program and provides recommendations for enhancing power system reliability under HENT conditions. A nominal HENP environment suitable for assessing geographically large systems was developed during the program and is briefly described in this report. This environment was used to provide a realistic indication of BEMP impacts on electric power systems. It was found that a single high-altitude burst, which could significantly disturb the geomagnetic field, may cause the interconnected power network to break up into utility islands with massive power failures in some areas. However, permanent damage would be isolated, and restoration should be possible within a few hours. Multiple bursts would likely increase the blackout areas, component failures, and restoration time. However, a long-term blackout of many months is unlikely because major power system components, such as transformers, are not likely to be damaged by the nominal HEND environment. Moreover, power system reliability, under both HENT and normal operating conditions, can be enhanced by simple, and often low cost, modifications to current utility practices.

  17. Electromagnetic pulse research on electric power systems: Program summary and recommendations. Power Systems Technology Program

    SciTech Connect

    Barnes, P.R.; McConnell, B.W.; Van Dyke, J.W.; Tesche, F.M.; Vance, E.F.

    1993-01-01

    A single nuclear detonation several hundred kilometers above the central United States will subject much of the nation to a high-altitude electromagnetic pulse (BENT). This pulse consists of an intense steep-front, short-duration transient electromagnetic field, followed by a geomagnetic disturbance with tens of seconds duration. This latter environment is referred to as the magnetohydrodynamic electromagnetic pulse (NMENT). Both the early-time transient and the geomagnetic disturbance could impact the operation of the nation`s power systems. Since 1983, the US Department of Energy has been actively pursuing a research program to assess the potential impacts of one or more BENT events on the nation`s electric energy supply. This report summarizes the results of that program and provides recommendations for enhancing power system reliability under HENT conditions. A nominal HENP environment suitable for assessing geographically large systems was developed during the program and is briefly described in this report. This environment was used to provide a realistic indication of BEMP impacts on electric power systems. It was found that a single high-altitude burst, which could significantly disturb the geomagnetic field, may cause the interconnected power network to break up into utility islands with massive power failures in some areas. However, permanent damage would be isolated, and restoration should be possible within a few hours. Multiple bursts would likely increase the blackout areas, component failures, and restoration time. However, a long-term blackout of many months is unlikely because major power system components, such as transformers, are not likely to be damaged by the nominal HEND environment. Moreover, power system reliability, under both HENT and normal operating conditions, can be enhanced by simple, and often low cost, modifications to current utility practices.

  18. Energy-optimal electrical-stimulation pulses shaped by the Least-Action Principle.

    PubMed

    Krouchev, Nedialko I; Danner, Simon M; Vinet, Alain; Rattay, Frank; Sawan, Mohamad

    2014-01-01

    Electrical stimulation (ES) devices interact with excitable neural tissue toward eliciting action potentials (AP's) by specific current patterns. Low-energy ES prevents tissue damage and loss of specificity. Hence to identify optimal stimulation-current waveforms is a relevant problem, whose solution may have significant impact on the related medical (e.g. minimized side-effects) and engineering (e.g. maximized battery-life) efficiency. This has typically been addressed by simulation (of a given excitable-tissue model) and iterative numerical optimization with hard discontinuous constraints--e.g. AP's are all-or-none phenomena. Such approach is computationally expensive, while the solution is uncertain--e.g. may converge to local-only energy-minima and be model-specific. We exploit the Least-Action Principle (LAP). First, we derive in closed form the general template of the membrane-potential's temporal trajectory, which minimizes the ES energy integral over time and over any space-clamp ionic current model. From the given model we then obtain the specific energy-efficient current waveform, which is demonstrated to be globally optimal. The solution is model-independent by construction. We illustrate the approach by a broad set of example situations with some of the most popular ionic current models from the literature. The proposed approach may result in the significant improvement of solution efficiency: cumbersome and uncertain iteration is replaced by a single quadrature of a system of ordinary differential equations. The approach is further validated by enabling a general comparison to the conventional simulation and optimization results from the literature, including one of our own, based on finite-horizon optimal control. Applying the LAP also resulted in a number of general ES optimality principles. One such succinct observation is that ES with long pulse durations is much more sensitive to the pulse's shape whereas a rectangular pulse is most frequently

  19. Inactivation of Salmonella Typhimurium in orange juice containing antimicrobial agents by pulsed electric field.

    PubMed

    Liang, Ziwei; Mittal, Gauri S; Griffiths, Mansel W

    2002-07-01

    Combinations of different hurdles, including moderately high temperatures (<60 degrees C), antimicrobial compounds, and pulsed electric field (PEF) treatment, to reduce Salmonella in pasteurized and freshly squeezed orange juices (with and without pulp) were explored. Populations of Salmonella Typhimurium were found to decrease with an increase in pulse number and treatment temperature. At a field strength of 90 kV/cm, a pulse number of 20, and a temperature of 45 degrees C, PEF treatment did not have a notable effect on cell viability or injury. At and above 46 degrees C, however, cell death and injury were greatly increased. Salmonella numbers were reduced by 5.9 log cycles in freshly squeezed orange juice (without pulp) treated at 90 kV/cm, 50 pulses, and 55 degrees C. When PEF treatment was carried out in the presence of nisin (100 U/ml of orange juice), lysozyme (2,400 U/ml), or a mixture of nisin (27.5 U/ml) and lysozyme (690 U/ml), cell viability loss was increased by an additional 0.04 to 2.75 log cycles. The combination of nisin and lysozyme had a more pronounced bactericidal effect than did either nisin or lysozyme alone. An additional Salmonella count reduction of at least 1.37 log cycles was achieved when the two antimicrobial agents were used in combination. No significant difference (P > 0.05) in cell death was attained by lowering the pH value; only cell injury increased. Inactivation by PEF was significantly more extensive (P < 0.05) in pasteurized orange juice than in freshly squeezed orange juice under the same treatment conditions. This increase might be due to the effect of the chemical composition of the juices. PMID:12117238

  20. Diffuse, non-polar electropermeabilization and reduced propidium uptake distinguish the effect of nanosecond electric pulses.

    PubMed

    Semenov, Iurii; Zemlin, Christian; Pakhomova, Olga N; Xiao, Shu; Pakhomov, Andrei G

    2015-10-01

    Ca2+ activation and membrane electroporation by 10-ns and 4-ms electric pulses (nsEP and msEP) were compared in rat embryonic cardiomyocytes. The lowest electric field which triggered Ca2+ transients was expectedly higher for nsEP (36 kV/cm) than for msEP (0.09 kV/cm) but the respective doses were similar (190 and 460 mJ/g). At higher intensities, both stimuli triggered prolonged firing in quiescent cells. An increase of basal Ca2+ level by >10 nM in cells with blocked voltage-gated Ca2+ channels and depleted Ca2+ depot occurred at 63 kV/cm (nsEP) or 0.14 kV/cm (msEP) and was regarded as electroporation threshold. These electric field values were at 150-230% of stimulation thresholds for both msEP and nsEP, notwithstanding a 400,000-fold difference in pulse duration. For comparable levels of electroporative Ca2+ uptake, msEP caused at least 10-fold greater uptake of propidium than nsEP, suggesting increased yield of larger pores. Electroporation by msEP started Ca2+ entry abruptly and locally at the electrode-facing poles of cell, followed by a slow diffusion to the center. In a stark contrast, nsEP evoked a "supra-electroporation" pattern of slower but spatially uniform Ca2+ entry. Thus nsEP and msEP had comparable dose efficiency, but differed profoundly in the size and localization of electropores. PMID:26112464

  1. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    PubMed Central

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V/cm. Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  2. Combination pulsed electric field with ethanol solvent for Nannochloropsis sp. extraction

    NASA Astrophysics Data System (ADS)

    Nafis, Ghazy Ammar; Mumpuni, Perwitasari Yekti; Indarto, Budiman, Arief

    2015-12-01

    Nowadays, energy is one of human basic needs. As the human population increased, energy consumption also increased. This condition causes energy depletion. In case of the situation, alternative energy is needed to replace existing energy. Microalgae is chosen to become one of renewable energy resource, especially biodiesel, because it contains high amount of lipid instead of other feedstock which usually used. Fortunately, Indonesia has large area of water and high intensity of sunlight so microalgae cultivation becomes easier. Nannochloropsis sp., one of microalgae species, becomes the main focus because of its high lipid content. Many ways to break the cell wall of microalgae so the lipid content inside the microalgae will be released, for example conventional extraction, ultrasonic wave extraction, pressing, and electrical method. The most effective way for extraction is electrical method such as pulsed electric field method (PEF). The principal work of this method is by draining the electrical current into parallel plate. Parallel plate will generate the electrical field to break microalgae cell wall and the lipid will be released. The aim of this work is to evaluate two-stage procedure for extraction of useful components from microalgae Nannochloropsis sp. The first stage of this procedure includes pre-treatment of microalgae by ethanol solvent extraction and the second stage applies the PEF extraction using a binary mixture of water and ethanol solvent. Ethanol is chosen as solvent because it's safer to be used and easier to be handled than other solvent. Some variables that used to study the most effective operation conditions are frequency and duty cycle for microalgae. The optimum condition based on this research are at frequency 1 Hz and duty cycle 13%.

  3. Effect of pulsed electric field treatments on permeabilization and extraction of pigments from Chlorella vulgaris.

    PubMed

    Luengo, Elisa; Condón-Abanto, Santiago; Álvarez, Ignacio; Raso, Javier

    2014-12-01

    The effect of pulsed electric field (PEF) treatments of different intensities on the electroporation of the cytoplasmatic membrane of Chlorella vulgaris, and on the extraction of carotenoids and chlorophylls were investigated. Staining the cells with propidium iodide before and after the PEF treatment revealed the existence of reversible and irreversible electroporation. Application of PEF treatments in the range of 20-25 kV cm(-1) caused most of the population of C. vulgaris to be irreversibly electroporated even at short treatment times (5 pulses of 3 µs). However, at lower electric field strengths (10 kV cm(-1)), cells that were reversibly electroporated were observed even after 50 pulses of 3 µs. The electroporation of C. vulgaris cells by PEF higher than 15 kV cm(-1) and duration is higher than 15 µs increased significantly the extraction yield of intracellular components of C. vulgaris. The application of a 20 kV cm(-1) for 75 μs increased the extraction yield just after the PEF treatment of the carotenoids, and chlorophylls a and b 0.5, 0.7, and 0.8 times, respectively. However, further increments in electric field strength and treatment time did not cause significant increments in the extraction yield. The extraction of carotenoids from PEF-treated C. vulgaris cells after 1 h of the application of the treatment significantly increased the extraction yield in comparison to the yield obtained from the cells extracted just after the PEF treatment. After PEF treatment at 20 kV cm(-1) for 75 µs, extraction yield for carotenoids, and chlorophylls a and b increased 1.2, 1.6, and 2.1 times, respectively. A high correlation was observed between irreversible electroporation and percentage of yield increase when the extraction was conducted after 1 h of the application of PEF treatment (R: 0.93), but not when the extraction was conducted just after PEF treatment (R: 0.67). PMID:24880235

  4. The effect of high density electric pulses on sintered aluminum 201AB silicon carbide MMC PM compacts during plastic deformation

    NASA Astrophysics Data System (ADS)

    Dariavach, Nader Guseinovich

    The effect of high-density electrical pulses on mechanical and structural properties of sintered aluminum SiC metal-matrix composites, fabricated by standard powder-metallurgy compaction and sintering, was investigated. Three types of phenomena where investigated during transverse rupture testing of the samples: a consolidation effect (increasing of the transverse rupture strength (TRS)), an electroplastic effect (decreasing of the flow stresses), and an increasing of the stress intensity factor by electric pulse application. It was observed, that an increase in the TRS strength of sintered powder metallurgy (PM) aluminum and aluminum metal matrix composite (MMC) compacts is a result of the electric pulse consolidation effect due to non-uniform temperature distribution around the grain boundaries. Three analytical models of the thermal effect of electric pulses on aluminum samples where considered: total temperature change of the sample due to a one electric pulse, one-dimensional steady state model and transient 2D thermal analysis of the temperature distribution around the grain boundary. The 2D transient analysis shows that the temperature rise in the grain boundary of a sintered PM aluminum sample due to an electric pulse can exceed the melting point. At the same time the temperature of the bulk material has an insignificant (<28°C) change. It was found that the electroplastic effect, due to electric pulse application, can account for up to a 40% load drop in aluminum MMC PM compacts. Reduction of flow stresses during plastic deformation could reduce the risk of structural damage, micro-cracks, SiC particle fracture and delamination of the aluminum MMC. These results may find practical application for manufacturing processes such as forging, extrusion, rolling, which involve plastic deformation. It was experimentally proven that a non-uniform temperature distribution around the crack could re-melt the crack tip and increase the strength of the damaged material

  5. Polarization of antiferroelectric ceramics for pulse capacitors under transient electric field

    NASA Astrophysics Data System (ADS)

    Xu, Ran; Xu, Zhuo; Feng, Yujun; Wei, Xiaoyong; Tian, Jingjing; Huang, Dong

    2016-06-01

    The polarization of (Pb0.94La0.04)[(Zr0.7Sn0.3)0.87Ti0.13]O3 antiferroelectric (AFE) ceramics under unipolar pulse electric field was studied, and the transient hysteresis loop was achieved. Compared to the traditional quasi-static results, the forward transition field increases and the backward transition field decreases. The forward and backward phase transitions can be deduced in microseconds scale. Under the transient field, the releasable energy density decreases significantly, while the stored energy density changes slightly. Consequently, the efficiency decreases and the declination of energy density under transient situation is verified by the charge-discharge experiment. The above results prove the necessity of the study of the transient behaviors in AFE and the limitation of quasi-static analysis.

  6. Influence of sulfides on the tribological properties of composites produced by pulse electric current sintering

    NASA Astrophysics Data System (ADS)

    Kim, Seung Ho

    2014-01-01

    Self-lubricating Al2O3-15wt% ZrO2 composites with sulfides, such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) serving as solid lubricants, were fabricated by using the pulse electric current sintering (PECS) technique. The coefficient of friction (COF) of the Al2O3-15wt% ZrO2 composite without/with sulfides was in the range of 0.37-0.48 and 0.27-0.49, respectively. As the amount of sulfides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.

  7. Cell wall as a target for bacteria inactivation by pulsed electric fields

    PubMed Central

    Pillet, Flavien; Formosa-Dague, Cécile; Baaziz, Houda; Dague, Etienne; Rols, Marie-Pierre

    2016-01-01

    The integrity and morphology of bacteria is sustained by the cell wall, the target of the main microbial inactivation processes. One promising approach to inactivation is based on the use of pulsed electric fields (PEF). The current dogma is that irreversible cell membrane electro-permeabilisation causes the death of the bacteria. However, the actual effect on the cell-wall architecture has been poorly explored. Here we combine atomic force microscopy and electron microscopy to study the cell-wall organization of living Bacillus pumilus bacteria at the nanoscale. For vegetative bacteria, exposure to PEF led to structural disorganization correlated with morphological and mechanical alterations of the cell wall. For spores, PEF exposure led to the partial destruction of coat protein nanostructures, associated with internal alterations of cortex and core. Our findings reveal for the first time that the cell wall and coat architecture are directly involved in the electro-eradication of bacteria. PMID:26830154

  8. Effect of pulsed electric fields treatment and mash size on extraction and composition of apple juices.

    PubMed

    Turk, Mohammad F; Baron, Alain; Vorobiev, Eugene

    2010-09-01

    This study explored the effect of pulsed electric field (PEF) treatment (E=450 V/cm; tt=10 ms; E<3 kJ/kg) and apple mash size on juice yield, polyphenolic compounds, sugars, and malic acid. Juice yield increased significantly after PEF treatment of large mash (Y=71.4%) and remained higher than the juice yield obtained for a control small mash (45.6%). The acid sweet balance was not altered by PEF. A correlation was established between the decrease of light absorbance (control: 1.43; treated: 1.10) and the decline of native polyphenols yield due to PEF treatment (control: 9.6%; treated: 5.9% for small mash). An enhanced oxidation of phenolic compounds in cells due to electroporation of the inner cell membrane and the adsorption of the oxidized products on the mash may explain both the lower light absorbance and the lower native polyphenol concentration. PMID:20701245

  9. Electrical and optical characterization of multilayered thin film based on pulsed laser deposition of metal oxides

    NASA Astrophysics Data System (ADS)

    Marotta, V.; Orlando, S.; Parisi, G. P.; Giardini, A.; Perna, G.; Santoro, A. M.; Capozzi, V.

    2000-12-01

    Thin films of semiconducting oxides such as In2O3, SnO2, and multilayers of these two compounds have been deposited by reactive pulsed laser ablation, with the aim to produce toxic gas sensors. Deposition of these thin films has been carried out by a frequency doubled Nd-YAG laser (λ=532 nm) on silicon (1 0 0) substrates. A comparison, among indium oxide, tin oxide, and multilayers of indium and tin oxides, has been performed. The influence of physical parameters such as substrate temperature, laser fluence and oxygen pressure in the deposition chamber has been investigated. The deposited films have been characterized by X-ray diffraction (XRD), optical and electric resistance measurements.

  10. Experimental characterization of plasma formation and shockwave propagation induced by high power pulsed underwater electrical discharge.

    PubMed

    Claverie, A; Deroy, J; Boustie, M; Avrillaud, G; Chuvatin, A; Mazanchenko, E; Demol, G; Dramane, B

    2014-06-01

    High power pulsed electrical discharges into liquids are investigated for new industrial applications based on the efficiency of controlled shock waves. We present here new experimental data obtained by combination of detailed high speed imaging equipments. It allows the visualization of the very first instants of plasma discharge formation, and then the pulsations of the gaseous bubble with an accurate timing of events. The time history of the expansion/compression of this bubble leads to an estimation of the energy effectively transferred to water during the discharge. Finally, the consecutive shock generation driven by this pulsating bubble is optically monitored by shadowgraphs and schlieren setup. These data provide essential information about the geometrical pattern and chronometry associated with the shock wave generation and propagation. PMID:24985821

  11. Energy-efficient biomass processing with pulsed electric fields for bioeconomy and sustainable development.

    PubMed

    Golberg, Alexander; Sack, Martin; Teissie, Justin; Pataro, Gianpiero; Pliquett, Uwe; Saulis, Gintautas; Stefan, Töpfl; Miklavcic, Damijan; Vorobiev, Eugene; Frey, Wolfgang

    2016-01-01

    Fossil resources-free sustainable development can be achieved through a transition to bioeconomy, an economy based on sustainable biomass-derived food, feed, chemicals, materials, and fuels. However, the transition to bioeconomy requires development of new energy-efficient technologies and processes to manipulate biomass feed stocks and their conversion into useful products, a collective term for which is biorefinery. One of the technological platforms that will enable various pathways of biomass conversion is based on pulsed electric fields applications (PEF). Energy efficiency of PEF treatment is achieved by specific increase of cell membrane permeability, a phenomenon known as membrane electroporation. Here, we review the opportunities that PEF and electroporation provide for the development of sustainable biorefineries. We describe the use of PEF treatment in biomass engineering, drying, deconstruction, extraction of phytochemicals, improvement of fermentations, and biogas production. These applications show the potential of PEF and consequent membrane electroporation to enable the bioeconomy and sustainable development. PMID:27127539

  12. Tracing explosive in solvent using quantum cascade laser with pulsed electric discharge system

    SciTech Connect

    Park, Seong-Wook; Tian, Chao; Martini, Rainer; Chen, Gang; Chen, I-chun Anderson

    2014-11-03

    We demonstrated highly sensitive detection of explosive dissolved in solvent with a portable spectroscopy system (Q-MACS) by tracing the explosive byproduct, N{sub 2}O, in combination with a pulsed electric discharge system for safe explosive decomposition. Using Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), the gas was monitored and analyzed by Q-MACS and the presence of the dissolved explosive clearly detected. While HMX presence could be identified directly in the air above the solutions even without plasma, much better results were achieved under the decomposition. The experiment results give an estimated detection limit of 10 ppb, which corresponds to a 15 pg of HMX.

  13. Energy-Optimal Electrical-Stimulation Pulses Shaped by the Least-Action Principle

    PubMed Central

    Krouchev, Nedialko I.; Danner, Simon M.; Vinet, Alain; Rattay, Frank; Sawan, Mohamad

    2014-01-01

    Electrical stimulation (ES) devices interact with excitable neural tissue toward eliciting action potentials (AP’s) by specific current patterns. Low-energy ES prevents tissue damage and loss of specificity. Hence to identify optimal stimulation-current waveforms is a relevant problem, whose solution may have significant impact on the related medical (e.g. minimized side-effects) and engineering (e.g. maximized battery-life) efficiency. This has typically been addressed by simulation (of a given excitable-tissue model) and iterative numerical optimization with hard discontinuous constraints - e.g. AP’s are all-or-none phenomena. Such approach is computationally expensive, while the solution is uncertain - e.g. may converge to local-only energy-minima and be model-specific. We exploit the Least-Action Principle (LAP). First, we derive in closed form the general template of the membrane-potential’s temporal trajectory, which minimizes the ES energy integral over time and over any space-clamp ionic current model. From the given model we then obtain the specific energy-efficient current waveform, which is demonstrated to be globally optimal. The solution is model-independent by construction. We illustrate the approach by a broad set of example situations with some of the most popular ionic current models from the literature. The proposed approach may result in the significant improvement of solution efficiency: cumbersome and uncertain iteration is replaced by a single quadrature of a system of ordinary differential equations. The approach is further validated by enabling a general comparison to the conventional simulation and optimization results from the literature, including one of our own, based on finite-horizon optimal control. Applying the LAP also resulted in a number of general ES optimality principles. One such succinct observation is that ES with long pulse durations is much more sensitive to the pulse’s shape whereas a rectangular pulse is most

  14. Comparative study of electrical breakdown properties of deionized water and heavy water under pulsed power conditions

    NASA Astrophysics Data System (ADS)

    Veda Prakash, G.; Kumar, R.; Saurabh, K.; Nasir, Anitha, V. P.; Chowdhuri, M. B.; Shyam, A.

    2016-01-01

    A comparative study of electrical breakdown properties of deionized water (H2O) and heavy water (D2O) is presented with two different electrode materials (stainless steel (SS) and brass) and polarity (positive and negative) combinations. The pulsed (˜a few tens of nanoseconds) discharges are conducted by applying high voltage (˜a few hundred kV) pulse between two hemisphere electrodes of the same material, spaced 3 mm apart, at room temperature (˜26-28 °C) with the help of Tesla based pulse generator. It is observed that breakdown occurred in heavy water at lesser voltage and in short duration compared to deionized water irrespective of the electrode material and applied voltage polarity chosen. SS electrodes are seen to perform better in terms of the voltage withstanding capacity of the liquid dielectric as compared to brass electrodes. Further, discharges with negative polarity are found to give slightly enhanced discharge breakdown voltage when compared with those with positive polarity. The observations corroborate well with conductivity measurements carried out on original and post-treated liquid samples. An interpretation of the observations is attempted using Fourier transform infrared measurements on original and post-treated liquids as well as in situ emission spectra studies. A yet another important observation from the emission spectra has been that even short (nanosecond) duration discharges result in the formation of a considerable amount of ions injected into the liquid from the electrodes in a similar manner as reported for long (microseconds) discharges. The experimental observations show that deionised water is better suited for high voltage applications and also offer a comparison of the discharge behaviour with different electrodes and polarities.

  15. Transmission electron microscopy of Listeria innocua treated by pulsed electric fields and nisin in skimmed milk.

    PubMed

    Calderón-Miranda, M L; Barbosa-Cánovas, G V; Swanson, B G

    1999-10-01

    Pulsed electric fields (PEF) is a nonthermal food preservation process where organoleptic and nutritional properties of the food are maintained. PEF is known to inactivate microorganisms by causing dielectric breakdown of the cell membrane, thus altering the functionality of the membrane as a semipermeable barrier. The extent of damage of the cell membrane, whether visible in the form of a pore or as loss of membrane functionality leads to the inactivation of the microorganism. The objective of this study was to investigate under transmission electron microscopy (TEM) the morphological changes on Listerit innocua as a result of PEF treatment in skimmed milk containing nisin. L. innocua was subjected to PEF at selected electric field intensities of 30, 40, and 50 kV/cm. L. innocua was treated by PEF in both skimmed milk with and without 37 IU nisin/ml. L. innocua treated by PEF in skimmed milk exhibited an increase in the cell wall roughness. cytoplasmic clumping, leakage of cellular material, and rupture of the cell walls and cell membranes. L. innocua subjected to PEF in skimmed milk containing 37 IU nisin/ml exhibited an increased cell wall width. At the highest electric field intensity, 50 kV/cm, elongation of the cell length was observed. There were no morphological differences between cells treated by PEF in skimmed milk with or without nisin. The combination of PEF and nisin exhibit an additive effect in the morphological damage observed on L. innocua. Pore formation was observed on L. innocua for an electric field intensity of 40 kV/cm. The inactivation of L. innocua was a consequence of rupture of the cell membrane and loss of cell membrane functionality. PMID:10563461

  16. Producing nitric oxide by pulsed electrical discharge in air for portable inhalation therapy.

    PubMed

    Yu, Binglan; Muenster, Stefan; Blaesi, Aron H; Bloch, Donald B; Zapol, Warren M

    2015-07-01

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation and is an effective therapy for treating pulmonary hypertension in adults and children. In the United States, the average cost of 5 days of inhaled NO for persistent pulmonary hypertension of the newborn is about $14,000. NO therapy involves gas cylinders and distribution, a complex delivery device, gas monitoring and calibration equipment, and a trained respiratory therapy staff. The objective of this study was to develop a lightweight, portable device to serve as a simple and economical method of producing pure NO from air for bedside or portable use. Two NO generators were designed and tested: an offline NO generator and an inline NO generator placed directly within the inspiratory line. Both generators use pulsed electrical discharges to produce therapeutic range NO (5 to 80 parts per million) at gas flow rates of 0.5 to 5 liters/min. NO was produced from air, as well as gas mixtures containing up to 90% O2 and 10% N2. Potentially toxic gases produced in the plasma, including nitrogen dioxide (NO2) and ozone (O3), were removed using a calcium hydroxide scavenger. An iridium spark electrode produced the lowest ratio of NO2/NO. In lambs with acute pulmonary hypertension, breathing electrically generated NO produced pulmonary vasodilation and reduced pulmonary arterial pressure and pulmonary vascular resistance index. In conclusion, electrical plasma NO generation produces therapeutic levels of NO from air. After scavenging to remove NO2 and O3 and filtration to remove particles, electrically produced NO can provide safe and effective treatment of pulmonary hypertension. PMID:26136478

  17. Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity

    NASA Astrophysics Data System (ADS)

    Wei, Kai; Li, Wei; Gao, Shan; Ji, Bin; Zang, Yating; Su, Bo; Wang, Kaile; Yao, Maosheng; Zhang, Jue; Wang, Jinglin

    2016-01-01

    Ricin is one of the most toxic and easily produced plant protein toxin extracted from the castor oil plant, and it has been classified as a chemical warfare agent. Here, nanosecond pulsed electric fields (nsPEFs) at 30 kV/cm (pulse durations: 10 ns, 100 ns, and 300 ns) were applied to inactivating ricin up to 4.2 μg/mL. To investigate the efficacy, cells and mice were tested against the ricin treated by the nsPEFs via direct intraperitoneal injection and inhalation exposure. Results showed that nsPEFs treatments can effectively reduce the toxicity of the ricin. Without the nsPEFs treatment, 100% of mice were killed upon the 4 μg ricin injection on the first day, however 40% of the mice survived the ricin treated by the nsPEFs. Compared to injection, inhalation exposure even with higher ricin dose required longer time to observe mice fatality. Pathological observations revealed damages to heart, lung, kidney, and stomach after the ricin exposure, more pronounced for lung and kidney including severe bleeding. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) and circular dichroism (CD) analyses revealed that although the primary structure of ricin was not altered, its secondary structures (beta-sheet and beta-turn) underwent transition upon the nsPEFs treatment.

  18. Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity

    PubMed Central

    Wei, Kai; Li, Wei; Gao, Shan; Ji, Bin; Zang, Yating; Su, Bo; Wang, Kaile; Yao, Maosheng; Zhang, Jue; Wang, Jinglin

    2016-01-01

    Ricin is one of the most toxic and easily produced plant protein toxin extracted from the castor oil plant, and it has been classified as a chemical warfare agent. Here, nanosecond pulsed electric fields (nsPEFs) at 30 kV/cm (pulse durations: 10 ns, 100 ns, and 300 ns) were applied to inactivating ricin up to 4.2 μg/mL. To investigate the efficacy, cells and mice were tested against the ricin treated by the nsPEFs via direct intraperitoneal injection and inhalation exposure. Results showed that nsPEFs treatments can effectively reduce the toxicity of the ricin. Without the nsPEFs treatment, 100% of mice were killed upon the 4 μg ricin injection on the first day, however 40% of the mice survived the ricin treated by the nsPEFs. Compared to injection, inhalation exposure even with higher ricin dose required longer time to observe mice fatality. Pathological observations revealed damages to heart, lung, kidney, and stomach after the ricin exposure, more pronounced for lung and kidney including severe bleeding. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) and circular dichroism (CD) analyses revealed that although the primary structure of ricin was not altered, its secondary structures (beta-sheet and beta-turn) underwent transition upon the nsPEFs treatment. PMID:26728251

  19. Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity.

    PubMed

    Wei, Kai; Li, Wei; Gao, Shan; Ji, Bin; Zang, Yating; Su, Bo; Wang, Kaile; Yao, Maosheng; Zhang, Jue; Wang, Jinglin

    2016-01-01

    Ricin is one of the most toxic and easily produced plant protein toxin extracted from the castor oil plant, and it has been classified as a chemical warfare agent. Here, nanosecond pulsed electric fields (nsPEFs) at 30 kV/cm (pulse durations: 10 ns, 100 ns, and 300 ns) were applied to inactivating ricin up to 4.2 μg/mL. To investigate the efficacy, cells and mice were tested against the ricin treated by the nsPEFs via direct intraperitoneal injection and inhalation exposure. Results showed that nsPEFs treatments can effectively reduce the toxicity of the ricin. Without the nsPEFs treatment, 100% of mice were killed upon the 4 μg ricin injection on the first day, however 40% of the mice survived the ricin treated by the nsPEFs. Compared to injection, inhalation exposure even with higher ricin dose required longer time to observe mice fatality. Pathological observations revealed damages to heart, lung, kidney, and stomach after the ricin exposure, more pronounced for lung and kidney including severe bleeding. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) and circular dichroism (CD) analyses revealed that although the primary structure of ricin was not altered, its secondary structures (beta-sheet and beta-turn) underwent transition upon the nsPEFs treatment. PMID:26728251

  20. Tool path influence on electric pulse aided deformation during incremental sheet metal forming

    SciTech Connect

    Asgar, J.; Lingam, R. Reddy, V. N.

    2013-12-16

    Titanium and its alloys are difficult to form at room temperature due to their high flow stress. Super plastic deformation of Ti alloys involves low strain rate forming at very high temperatures which need special tooling which can withstand high temperatures. It was observed that when high current density electric pulse is applied during deformation it reduces the flow stress through electron-dislocation interaction. This phenomenon is known as electro-plasticity. In the present work, importance of tool configuration to enhance the formability without much resistive heating is demonstrated for Incremental Sheet Metal Forming (ISMF). Tool configuration is selected to minimize the current carrying zone in DC pulse aided incremental forming to enhance the formability due to electro plasticity and the same is demonstrated by forming two pyramid shaped components of 30° and 45° wall angles using a Titanium alloy sheet of 0.6 mm thickness. Load measurement indicated that a critical current density is essential for the electro-plasticity to be effective and the same is realized with the load and temperature measurements.

  1. Transmembrane voltage analyses in spheroidal cells in response to an intense ultrashort electrical pulse

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Joshi, R. P.

    2009-01-01

    Self-consistent evaluations of both the transmembrane potential (TMP) and possible electroporation density across membrane of spheroidal cells in response to ultrashort, high-intensity pulses are reported and discussed. Most treatments in the literature have been based on spherical cells, and this represents a step towards more realistic analyses. The present study couples the Laplace equation with Smoluchowski theory of pore formation, to yield dynamic membrane conductivities that influence the TMP. It is shown that the TMP induced by pulsed external voltages can be substantial higher in oblate spheroids as compared to spherical or prolate spheroidal cells. Flattening of the surface area in oblate spheroids leads to both higher electric fields seen by the membrane, and allows a great fraction of the surface area to be porated. This suggests that biomedical applications such as drug delivery and electrochemotherapy could work best for flatter-shaped cells, and secondary field-enabled orienting would be beneficial. Results for arbitrary field orientations and different cell sizes have also been presented.

  2. A protective effect after clearance of orthotopic rat hepatocellular carcinoma by nanosecond pulsed electric fields.

    PubMed

    Chen, Ru; Sain, Nova M; Harlow, K Tyler; Chen, Yeong-Jer; Shires, Peter K; Heller, Richard; Beebe, Stephen J

    2014-10-01

    Strategies for treating liver cancer using radiation, chemotherapy combinations and tyrosine kinase inhibitors targeting specific mutations have provided longer survival times, yet multiple treatments are often needed and recurrences with new malignant phenotypes are not uncommon. New and innovative treatments are undoubtedly needed to successfully treat liver cancer. Over the last decade, nanosecond pulsed electric fields (nsPEFs) have shown promise in pre-clinical studies; however, these have been limited to treatment of skin cancers or xenographs in mice. In the present report, an orthotopic hepatocellular carcinoma (HCC) model is established in rats using N1-S1 HCC cells. Data demonstrate a response rate of 80-90% when 1000 pulses are delivered with 100ns durations, electric field strengths of 50kV/cm and repetition rates of 1Hz. N1-S1 tumours treated with nsPEFs expressed significant number of cells with active caspase-3 and caspase-9, but not caspase-8, indicating an intrinsic apoptosis mechanism(s) as well as caspase-independent mechanisms. Most remarkably, rats with successfully ablated tumours failed to re-grow tumours when challenged with a second injection of N1-S1 cells when implanted in the same or different liver lobe that harboured the original tumour. Given this protective effect, infiltration of immune cells and the presence of granzyme B expressing cells within days of treatment suggest the possibility of an anti-tumour adaptive immune response. In conclusion, NsPEFs not only eliminate N1-S1 HCC tumours, but also may induce an immuno-protective effect that defends animals against recurrences of the same cancer. PMID:25081978

  3. Dynamic effects and applications for nanosecond pulsed electric fields in cells and tissues

    NASA Astrophysics Data System (ADS)

    Beebe, Stephen J.; Blackmore, Peter F.; Hall, Emily; White, Jody A.; Willis, Lauren K.; Fauntleroy, Laura; Kolb, Juergen F.; Schoenbach, Karl H.

    2005-04-01

    Nanosecond, high intensity pulsed electric fields [nsPEFs] that are below the plasma membrane [PM] charging time constant have decreasing effects on the PM and increasing effects on intracellular structures and functions as the pulse duration decreases. When human cell suspensions were exposed to nsPEFs where the electric fields were sufficiently intense [10-300ns, <=300 kV/cm.], apoptosis signaling pathways could be activated in several cell models. Multiple apoptosis markers were observed in Jurkat, HL-60, 3T3L1-preadipocytes, and isolated rat adipocytes including decreased cell size and number, caspase activation, DNA fragmentation, and/or cytochrome c release into the cytoplasm. Phosphatidylserine externalization was observed as a biological response to nsPEFs in 3T3-L1 preadipocytes and p53-wildtype and -null human colon carcinoma cells. B10.2 mouse fibrosarcoma tumors that were exposed to nsPEFs ex vivo and in vivo exhibited DNA fragmentation, elevated caspase activity, and reduced size and weight compared to contralateral sham-treated control tumors. When nsPEF conditions were below thresholds for apoptosis and classical PM electroporation, non-apoptotic responses were observed similar to those initiated through PM purinergic receptors in HL-60 cells and thrombin in human platelets. These included Ca2+ mobilization from intracellular stores [endoplasmic reticulum] and subsequently through store-operated Ca2+ channels in the PM. In addition, platelet activation measured as aggregation responses were observed in human platelets. Finally, when nsPEF conditions followed classical electroporation-mediated transfection, the expression intensity and number of GFP-expressing cells were enhanced above cells exposed to electroporation conditions alone. These studies demonstrate that application of nsPEFs to cells or tissues can modulate cell-signaling mechanisms with possible applications as a new basic science tool, cancer treatment, wound healing, and gene therapy.

  4. Self-consistent analyses for potential conduction block in nerves by an ultrashort high-intensity electric pulse

    NASA Astrophysics Data System (ADS)

    Joshi, R. P.; Mishra, A.; Hu, Q.; Schoenbach, K. H.; Pakhomov, A.

    2007-06-01

    Simulation studies are presented that probe the possibility of using high-field (>100kV/cm) , short-duration (˜50ns) electrical pulses for nonthermal and reversible cessation of biological electrical signaling pathways. This would have obvious applications in neurophysiology, clinical research, neuromuscular stimulation therapies, and even nonlethal bioweapons development. The concept is based on the creation of a sufficiently high density of pores on the nerve membrane by an electric pulse. This modulates membrane conductance and presents an effective “electrical short” to an incident voltage wave traveling across a nerve. Net blocking of action potential propagation can then result. A continuum approach based on the Smoluchowski equation is used to treat electroporation. This is self-consistently coupled with a distributed circuit representation of the nerve dynamics. Our results indicate that poration at a single neural segment would be sufficient to produce an observable, yet reversible, effect.

  5. Optimized Nanosecond Pulsed Electric Field Therapy Can Cause Murine Malignant Melanomas to Self-Destruct with a Single Treatment

    PubMed Central

    Nuccitelli, Richard; Tran, Kevin; Sheikh, Saleh; Athos, Brian; Kreis, Mark; Nuccitelli, Pamela

    2010-01-01

    We have identified a new, nanosecond pulsed electric field (nsPEF) therapy capable of eliminating murine melanomas located in the skin with a single treatment. When these optimized parameters are used, nsPEFs initiate apoptosis without hyperthermia. We have developed new suction electrodes that are compatible with human skin and have applied them to a xenograft nude mouse melanoma model system to identify the optimal field strength, pulse frequency and pulse number for the treatment of murine melanomas. A single treatment using the optimal pulse parameters (2000 pulses, 100 ns in duration, 30 kV/cm in amplitude at a pulse frequency of 5–7 pulses/s) eliminated all 17 melanomas treated with those parameters in 4 mice. This was the highest pulse frequency that we could use without raising the treated skin tumor temperature above 40 °C. We also demonstrate that the effects of nsPEF therapy are highly localized to only cells located between electrodes and results in very little scarring of the nsPEF-treated skin. PMID:20473857

  6. Fuzzy control with amplitude/pulse-width modulation of nerve electrical stimulation for muscle force control

    NASA Astrophysics Data System (ADS)

    Lin, C.-C. K.; Liu, W.-C.; Chan, C.-C.; Ju, M.-S.

    2012-04-01

    The main goal of this study was to study the performance of fuzzy logic controllers combined with simplified hybrid amplitude/pulse-width (AM/PW) modulation to regulate muscle force via nerve electrical stimulation. The recruitment curves with AM/PW and AM modulations were constructed for the calf muscles of rabbits. Integrated with the modulation methods, a proportional-integral-derivative (PID) and three fuzzy logic controllers were designed and applied for the electrical stimulation of tibial nerves to control the ankle torque under isometric conditions. The performance of the two modulation methods combined with the four controllers was compared when the ankle was fixed at three positions for both in vivo experiments and model simulations using a nonlinear muscle model. For the animal experiments, AM/PW modulation performed better than AM modulation alone. The fuzzy PI controller performed marginally better and was resistant to external noises, though it tended to have a larger overshoot. The performance of the controllers had a similar trend in the three different joint positions, and the simulation results with the nonlinear model matched the experimental results well. In conclusion, AM/PW modulation improved controller performance, while the contribution of fuzzy logic was only marginal.

  7. Simultaneous observation of ultrafast structural dynamics and transient electrical field by picosecond electron pulses

    NASA Astrophysics Data System (ADS)

    Li, Run-Ze; Zhu, Pengfei; Chen, Long; Chen, Jie; Cao, Jianming; Sheng, Zheng-Ming; Zhang, Jie

    2014-03-01

    Ultrafast electron diffraction and microscopy are very promising methods to study transient structural dynamics with atomic spatial-temporal resolution. However, in these laser-pump electron-probe studies of structural dynamics, a transient electric field induced by laser excitation of the sample could deflect probing electrons, which may eventually leads to a misinterpretation of the diffraction data. Here, picosecond structural dynamics and transient surface electric field evolution, excited by femtosecond laser interaction with a metallic thin film, have been observed simultaneously in real time by ultrashort electron pulses in a transmission configuration. By tracing time dependent changes of electron diffraction and deflection angles, these two processes are found to be significantly different and distinguishable in their temporal behavior. This observation provides an effective approach to extract the otherwise obscured ultrafast structural dynamics and may help to improve the spatiotemporal resolution in ultrafast electron diffraction and microscopy studies. This work was supported by the National Basic Research Program of China and the National Natural Science Foundation of China.

  8. Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Barnes, Ronald A., Jr.; Ibey, Bennett L.; Beier, Hope T.; Christopher Mimun, L.; Maswadi, Saher M.; Shadaram, Mehdi; Glickman, Randolph D.

    2015-10-01

    The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, electrochemical interactions, thermoelastic expansion, and others. To date, very limited research has investigated non-electric phenomena occurring during nsEP exposures and their potential effect on cell nanoporation. Of primary interest is the production of acoustic shock waves during nsEP exposure, as it is known that acoustic shock waves can cause membrane poration (sonoporation). Based on these observations, our group characterized the acoustic pressure transients generated by nsEP and determined if such transients played any role in nanoporation. In this paper, we show that nsEP exposures, equivalent to those used in cellular studies, are capable of generating high-frequency (2.5 MHz), high-intensity (>13 kPa) pressure transients. Using confocal microscopy to measure cell uptake of YO-PRO®-1 (indicator of nanoporation of the plasma membrane) and changing the electrode geometry, we determined that acoustic waves alone are not responsible for poration of the membrane.

  9. Modelling inactivation of Listeria monocytogenes by pulsed electric fields in media of different pH.

    PubMed

    Gómez, N; García, D; Alvarez, I; Condón, S; Raso, J

    2005-08-25

    A study of the effect of square-wave pulsed electric fields (PEF) on the inactivation of Listeria monocytogenes in McIlvaine buffer of different pH (3.5-7.0) was conducted. L. monocytoges was more PEF sensitive at higher electric field strengths (E) and in media of low pH. A treatment at 28 kV/cm for 400 mus that inactivated 1.5, 2.3 and 3.0 Log10 cycles at pH 7.0, 6.5 and 5.0 respectively destroyed almost 6.0 Log10 cycles at pH 3.5. The general shape of survival curves of L. monocytogenes PEF treated at different pH was convex/concave upwards. A mathematical model based on the Weibull distribution accurately described these survival curves. At each pH, the shape parameter (n value) did not depend on E. The relationship between n value of the Weibull model and the pH of the treatment medium was described by the Gompertz equation. A multiple linear regression model using three predictor variables (E, E2, pH2) related the Log10 of the scale paramenter (b value) of the Weibull model with E and pH of the treatment medium. A tertiary model developed using McIlvaine buffer as treatment medium predicted satisfactorily the inactivation of L. monocytogenes in apple juice. PMID:16083822

  10. Characterization of nanosecond pulse electrical field shock waves using imaging techniques

    NASA Astrophysics Data System (ADS)

    Mimun, L. Chris; Ibey, Bennett L.; Roth, Caleb C.; Barnes, Ronald A.; Sardar, Dhiraj K.; Beier, Hope T.

    2015-03-01

    Nanosecond pulsed electric fields (nsPEF) cause the formation of small pores, termed nanopores, in the membrane of cells. Current nanoporation models treat nsPEF exposure as a purely electromagnetic phenomenon, but recent publications showing pressure transients, ROS production, temperature gradients, and pH waves suggest the stimulus may be physically and chemically multifactorial causing elicitation of diverse biological conditions and stressors. Our research group's goal is to quantify the breadth and participation of these stressors generated during nsPEF exposure and determine their relative importance to the observed cellular response. In this paper, we used advanced imaging techniques to identify a possible source of nsPEF-induced acoustic shock waves. nsPEFs were delivered in an aqueous media via a pair of 125 μm tungsten electrodes separated by 100 μm, mirroring our previously published cellular exposure experiments. To visualize any pressure transients emanating from the electrodes or surrounding medium, we used the Schlieren imaging technique. Resulting images and measurements confirmed that mechanical pressure waves and electrode-based stresses are formed during nsPEF, resulting in a clearer understanding of the whole exposure dosimetry. This information will be used to better quantify the impact of nsPEF-induced acoustic shock waves on cells, and has provided further evidence of non-electrical-field induced exposures for elicitation of bioieffects.

  11. Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure

    PubMed Central

    Roth, Caleb C.; Barnes Jr., Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Christopher Mimun, L.; Maswadi, Saher M.; Shadaram, Mehdi; Glickman, Randolph D.

    2015-01-01

    The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, electrochemical interactions, thermoelastic expansion, and others. To date, very limited research has investigated non-electric phenomena occurring during nsEP exposures and their potential effect on cell nanoporation. Of primary interest is the production of acoustic shock waves during nsEP exposure, as it is known that acoustic shock waves can cause membrane poration (sonoporation). Based on these observations, our group characterized the acoustic pressure transients generated by nsEP and determined if such transients played any role in nanoporation. In this paper, we show that nsEP exposures, equivalent to those used in cellular studies, are capable of generating high-frequency (2.5 MHz), high-intensity (>13 kPa) pressure transients. Using confocal microscopy to measure cell uptake of YO-PRO®-1 (indicator of nanoporation of the plasma membrane) and changing the electrode geometry, we determined that acoustic waves alone are not responsible for poration of the membrane. PMID:26450165

  12. Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure.

    PubMed

    Roth, Caleb C; Barnes, Ronald A; Ibey, Bennett L; Beier, Hope T; Christopher Mimun, L; Maswadi, Saher M; Shadaram, Mehdi; Glickman, Randolph D

    2015-01-01

    The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, electrochemical interactions, thermoelastic expansion, and others. To date, very limited research has investigated non-electric phenomena occurring during nsEP exposures and their potential effect on cell nanoporation. Of primary interest is the production of acoustic shock waves during nsEP exposure, as it is known that acoustic shock waves can cause membrane poration (sonoporation). Based on these observations, our group characterized the acoustic pressure transients generated by nsEP and determined if such transients played any role in nanoporation. In this paper, we show that nsEP exposures, equivalent to those used in cellular studies, are capable of generating high-frequency (2.5 MHz), high-intensity (>13 kPa) pressure transients. Using confocal microscopy to measure cell uptake of YO-PRO®-1 (indicator of nanoporation of the plasma membrane) and changing the electrode geometry, we determined that acoustic waves alone are not responsible for poration of the membrane. PMID:26450165

  13. Impacts of a nominal nuclear electromagnetic pulse on electric power systems

    NASA Astrophysics Data System (ADS)

    Kruse, V. J.; Nickel, D. L.; Bonk, J. J.; Taylor, E. R., Jr.

    1991-04-01

    A high-altitude nuclear detonation several hundred kilometers above the central United States will subject much of the nation to an electromagnetic pulse (EMP) consisting of intense steep-front short-duration transient electromagnetic fields followed by a geomagnetic disturbance with a duration of tens of seconds. Since 1983, the Department of Energy has been actively pursuing a research program to assess the potential impacts of one or more EMP events on the nation's electric energy supply. A nominal EMP environmental suitable for assessing geographically large systems has been used to provide an indication of EMP impacts on electric power systems. It was found that a single high-altitude burst, which significantly disturbs the geomagnetic field, could cause significant load and generation loss, but permanent damage would be isolated. Multiple bursts would increase the disturbance. Nevertheless, based on the effects of a nominal EMP environment, a long-term blackout is not expected since major components such as power transformers are not likely to be damaged.

  14. Fuzzy control with amplitude/pulse-width modulation of nerve electrical stimulation for muscle force control.

    PubMed

    Lin, C-C K; Liu, W-C; Chan, C-C; Ju, M-S

    2012-04-01

    The main goal of this study was to study the performance of fuzzy logic controllers combined with simplified hybrid amplitude/pulse-width (AM/PW) modulation to regulate muscle force via nerve electrical stimulation. The recruitment curves with AM/PW and AM modulations were constructed for the calf muscles of rabbits. Integrated with the modulation methods, a proportional-integral-derivative (PID) and three fuzzy logic controllers were designed and applied for the electrical stimulation of tibial nerves to control the ankle torque under isometric conditions. The performance of the two modulation methods combined with the four controllers was compared when the ankle was fixed at three positions for both in vivo experiments and model simulations using a nonlinear muscle model. For the animal experiments, AM/PW modulation performed better than AM modulation alone. The fuzzy PI controller performed marginally better and was resistant to external noises, though it tended to have a larger overshoot. The performance of the controllers had a similar trend in the three different joint positions, and the simulation results with the nonlinear model matched the experimental results well. In conclusion, AM/PW modulation improved controller performance, while the contribution of fuzzy logic was only marginal. PMID:22422279

  15. [The application of electrical stimulation by bipolar pulsed currents and galanthamine electrophoresis for the rehabilitation of patients with diabetes mellitus].

    PubMed

    Lazarenko, N N; Gerasimenko, M Iu; Khamidullin, G N

    2011-01-01

    Clinical observations provided evidence of the positive effects of multichannel electrical stimulation by bipolar pulsed currents in combination with galanthamine electrophoresis applied for the treatment of patients with complicated diabetes mellitus. Such treatment facilitated normalization of water and carbohydrate metabolism and reduction of the body weight; moreover, it improved blood circulation and the state of the nervous system. PMID:22403949

  16. Influence of vacuum impregnation and pulsed electric field on the freezing temperature and ice propagation rates of spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efforts are currently directed towards improving the quality of sensitive tissues of fruits and vegetables after freezing and thawing. One of the methods under investigation is the combination of vacuum impregnation (VI) with cryoprotectants and pulsed electric field (PEF) applied to the plant tiss...

  17. Upscaling from benchtop processing to industrial scale production: More factors to be considered for pulsed electric field food processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulsed electric field (PEF) processing has been intensively studied with benchtop scale experiments. However, there is still limited information regarding critical factors to be considered for PEF efficacy in microbial reduction with PEF processing at a pilot or commercial scale production of juice....

  18. Pulsed electric field inactivation of E. coli O157:H7 and surrogate bacteria in orange juice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: United States FDA juice HACCP rules mandate that orange juice (OJ) processors treat juice for a 5 log reduction of the target pathogen. Thermal pasteurization, however, reduces the sensory characteristics of OJ by removing or altering volatile compounds. Pulsed electric field (PEF) ...

  19. A bioluminescence ATP assay for estimating surface hydrophobicity and membrane damage of Escherichia coli cells treated with pulsed electric fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulse Electric Field (PEF) treatments, a non-thermal process have been reported to injure and inactivate bacteria in liquid foods. However, the effect of this treatment on bacterial cell surface charge and hydrophobicity has not been investigated. Apple juice (AJ, pH 3.8) purchased from a wholesale ...

  20. Effect of Twisted Fiber Anisotropy in Cardiac Tissue on Ablation with Pulsed Electric Fields

    PubMed Central

    Xie, Fei; Zemlin, Christian W.

    2016-01-01

    Background Ablation of cardiac tissue with pulsed electric fields is a promising alternative to current thermal ablation methods, and it critically depends on the electric field distribution in the heart. Methods We developed a model that incorporates the twisted anisotropy of cardiac tissue and computed the electric field distribution in the tissue. We also performed experiments in rabbit ventricles to validate our model. We find that the model agrees well with the experimentally determined ablation volume if we assume that all tissue that is exposed to a field greater than 3 kV/cm is ablated. In our numerical analysis, we considered how tissue thickness, degree of anisotropy, and electrode configuration affect the geometry of the ablated volume. We considered two electrode configurations: two parallel needles inserted into the myocardium (“penetrating needles” configuration) and one circular electrode each on epi- and endocardium, opposing each other (“epi-endo” configuration). Results For thick tissues (10 mm) and moderate anisotropy ratio (a = 2), we find that the geometry of the ablated volume is almost unaffected by twisted anisotropy, i.e. it is approximately translationally symmetric from epi- to endocardium, for both electrode configurations. Higher anisotropy ratio (a = 10) leads to substantial variation in ablation width across the wall; these variations were more pronounced for the penetrating needle configuration than for the epi-endo configuration. For thinner tissues (4 mm, typical for human atria) and higher anisotropy ratio (a = 10), the epi-endo configuration yielded approximately translationally symmetric ablation volumes, while the penetrating electrodes configuration was much more sensitive to fiber twist. Conclusions These results suggest that the epi-endo configuration will be reliable for ablation of atrial fibrillation, independently of fiber orientation, while the penetrating electrode configuration may experience problems when the

  1. Cationic Peptide Exposure Enhances Pulsed-Electric-Field-Mediated Membrane Disruption

    PubMed Central

    Kennedy, Stephen M.; Aiken, Erik J.; Beres, Kaytlyn A.; Hahn, Adam R.; Kamin, Samantha J.; Hagness, Susan C.; Booske, John H.; Murphy, William L.

    2014-01-01

    Background The use of pulsed electric fields (PEFs) to irreversibly electroporate cells is a promising approach for destroying undesirable cells. This approach may gain enhanced applicability if the intensity of the PEF required to electrically disrupt cell membranes can be reduced via exposure to a molecular deliverable. This will be particularly impactful if that reduced PEF minimally influences cells that are not exposed to the deliverable. We hypothesized that the introduction of charged molecules to the cell surfaces would create regions of enhanced transmembrane electric potential in the vicinity of each charged molecule, thereby lowering the PEF intensity required to disrupt the plasma membranes. This study will therefore examine if exposure to cationic peptides can enhance a PEF’s ability to disrupt plasma membranes. Methodology/Principal Findings We exposed leukemia cells to 40 μs PEFs in media containing varying concentrations of a cationic peptide, polyarginine. We observed the internalization of a membrane integrity indicator, propidium iodide (PI), in real time. Based on an individual cell’s PI fluorescence versus time signature, we were able to determine the relative degree of membrane disruption. When using 1–2 kV/cm, exposure to >50 μg/ml of polyarginine resulted in immediate and high levels of PI uptake, indicating severe membrane disruption, whereas in the absence of peptide, cells predominantly exhibited signatures indicative of no membrane disruption. Additionally, PI entered cells through the anode-facing membrane when exposed to cationic peptide, which was theoretically expected. Conclusions/Significance Exposure to cationic peptides reduced the PEF intensity required to induce rapid and irreversible membrane disruption. Critically, peptide exposure reduced the PEF intensities required to elicit irreversible membrane disruption at normally sub-electroporation intensities. We believe that these cationic peptides, when coupled with

  2. Multiple nanosecond electric pulses increase the number but not the size of long-lived nanopores in the cell membrane.

    PubMed

    Pakhomov, Andrei G; Gianulis, Elena; Vernier, P Thomas; Semenov, Iurii; Xiao, Shu; Pakhomova, Olga N

    2015-04-01

    Exposure to intense, nanosecond-duration electric pulses (nsEP) opens small but long-lived pores in the plasma membrane. We quantified the cell uptake of two membrane integrity marker dyes, YO-PRO-1 (YP) and propidium (Pr) in order to test whether the pore size is affected by the number of nsEP. The fluorescence of the dyes was calibrated against their concentrations by confocal imaging of stained homogenates of the cells. The calibrations revealed a two-phase dependence of Pr emission on the concentration (with a slower rise at<4μM) and a linear dependence for YP. CHO cells were exposed to nsEP trains (1 to 100 pulses, 60ns, 13.2kV/cm, 10Hz) with Pr and YP in the medium, and the uptake of the dyes was monitored by time-lapse imaging for 3min. Even a single nsEP triggered a modest but detectable entry of both dyes, which increased linearly when more pulses were applied. The influx of Pr per pulse was constant and independent of the pulse number. The influx of YP per pulse was highest with 1- and 2-pulse exposures, decreasing to about twice the Pr level for trains from 5 to 100 pulses. The constant YP/Pr influx ratio for trains of 5 to 100 pulses suggests that increasing the number of pulses permeabilizes cells to a greater extent by increasing the pore number and not the pore diameter. PMID:25585279

  3. Numerically simulated cardiac exposure to electric current densities induced by TASER X-26 pulses in adult men

    NASA Astrophysics Data System (ADS)

    Leitgeb, N.; Niedermayr, F.; Neubauer, R.; Loos, G.

    2010-10-01

    There is still an ongoing debate whether or not electronic stun devices (ESDs) induce cardiac fibrillation. To assess the ventricular fibrillation risk of law enforcing electronic control devices, quantitative estimates of cardiac electric current densities induced by delivered electric pulses are essential. Numerical simulations were performed with the finite integration technique and the anatomical model of a standardized European man (NORMAN) segmented into 2 mm voxels and 35 different tissues. The load-dependent delivery of TASER X-26 pulses has been taken into account. Cardiac exposure to electric current densities of vertically and horizontally aligned dart electrodes was quantified and different hit scenarios compared. Since fibrillation thresholds critically depend on exposed volume, the provided quantitative data are essential for risk assessment. The maximum cardiac rms current densities amounted to 7730 A m-2. Such high current densities and exposed cardiac volumes do not exclude ventricular fibrillation.

  4. Inactivation of Escherichia coli O157:H7 and Escherichia coli 8739 in apple juice by pulsed electric fields.

    PubMed

    Evrendilek, G A; Zhang, Q H; Richter, E R

    1999-07-01

    The effect of high voltage pulsed electric field (PEF) treatment on Escherichia coli O157:H7 and generic E. coli 8739 in apple juice was investigated. Fresh apple juice samples inoculated with E. coli O157:H7 and E. coli 8739 were treated by PEF with selected parameters including electric field strength, treatment time, and treatment temperature. Samples were exposed to bipolar pulses with electric field strengths of 30, 26, 22, and 18 kV/cm and total treatment times of 172, 144, 115, and 86 micros. A 5-log reduction in both cultures was determined by a standard nonselective medium spread plate laboratory procedure. Treatment temperature was kept below 35 degrees C. Results showed no difference in the sensitivities of E. coli O157:H7 and E. coli 8739 against PEF treatment. PEF is a promising technology for the inactivation of E. coli O157:H7 and E. coli 8739 in apple juice. PMID:10419274

  5. Optical and electrical properties of SnO2 thin films after ultra-short pulsed laser annealing

    NASA Astrophysics Data System (ADS)

    Scorticati, D.; Illiberi, A.; Römer, G. R. B. E.; Bor, T.; Ogieglo, W.; Klein Gunnewiek, M.; Lenkferink, A.; Otto, C.; Skolski, J. Z. P.; Grob, F.; de Lange, D. F.; Huis in't Veld, A. J.

    2013-09-01

    Ultra-short pulsed laser sources, with pulse durations in the ps and fs regime, are commonly exploited for cold ablation. However, operating ultra-short pulsed laser sources at fluence levels well below the ablation threshold allows for fast and selective thermal processing. The latter is especially advantageous for the processing of thin films. A precise control of the heat affected zone, as small as tens of nanometers, depending on the material and laser conditions, can be achieved. It enables the treatment of the upper section of thin films with negligible effects on the bulk of the film and no thermal damage of sensitive substrates below. By applying picosecond laser pulses, the optical and electrical properties of 900 nm thick SnO2 films, grown by an industrial CVD process on borofloat®-glass, were modified. The treated films showed a higher transmittance of light in the visible and near infra-red range, as well as a slightly increased electrical sheet resistance. Changes in optical properties are attributed to thermal annealing, as well as to the occurrence of Laser- Induced Periodic Surface Structures (LIPSSs) superimposed on the surface of the SnO2 film. The small increase of electrical resistance is attributed to the generation of laser induced defects introduced during the fast heating-quenching cycle of the film. These results can be used to further improve the performance of SnO2-based electrodes for solar cells and/or electronic devices.

  6. Changes of colour and carotenoids contents during high intensity pulsed electric field treatment in orange juices.

    PubMed

    Cortés, C; Esteve, M J; Rodrigo, D; Torregrosa, F; Frígola, A

    2006-11-01

    Liquid chromatography (LC) was the method chosen to evaluate the effects of high intensity pulsed electric fields (HIPEF), with different electric field intensities (25, 30, 35 and 40 kV/cm) and different treatment times (30-340 micros), on orange juice cis/trans carotenoid contents. In parallel, a conventional heat treatment (90 degrees C, 20 s) was applied to the orange juice in order to compare the effect on the carotenoid contents. HIPEF processing of orange juice is an alternative to the thermal treatment of pasteurization, provided that it is kept refrigerated, because, when the most extreme conditions of this kind of treatment are applied, the decrease in the concentration of carotenoids with vitamin A activity is very small, and also most of the carotenoids identified have a slightly increased concentration after application of the most intense treatments, although always less than in untreated fresh juice. In any case, pasteurization treatment causes a greater decrease in the concentration of most of the carotenoids identified and the carotenoids with vitamin A activity. The total carotenoid concentration decreased by 12.6% in pasteurized orange juice with respect to untreated fresh orange juice, as opposed to decreases of 9.6%, 6.3% or 7.8% when fields of 25, 30 or 40 kV/cm were applied. Orange juice treated with HIPEF shows a greater tendency towards the colour yellow and a lesser tendency towards red with respect to untreated orange juice, while the luminance of the juice remains practically invariable. This tendency is less than in pasteurized orange juice. PMID:16914247

  7. Ultraviolet and pulsed electric field treatments have additive effect on inactivation of E. coli in apple juice.

    PubMed

    Gachovska, T K; Kumar, S; Thippareddi, H; Subbiah, J; Williams, F

    2008-11-01

    Apple juice inoculated with Escherichia coli ATCC 23472 was processed continuously using either ultraviolet (UV), high-voltage pulsed electric field (PEF), or a combination of the PEF and UV treatment systems. Apple juice was pumped through either of the systems at 3 flow rates (8, 14, and 20 mL/min). E. coli was reduced by 3.46 log CFU/mL when exposed in a 50 cm length of UV treatment chamber at 8 mL/min (2.94 s treatment time with a product temperature increase of 13 degrees C). E. coli inactivation of 4.87 log CFU/mL was achieved with a peak electric field strength of 60 kV/cm and 11.3 pulses (average pulse width of 3.5 mus, product temperature increased to 52 degrees C). E. coli reductions resulting from a combination treatment of UV and PEF applied sequentially were evaluated. A maximum E. coli reduction of 5.35 log CFU/mL was achieved using PEF (electrical field strength of 60 kV/cm, specific energy of 162 J/mL, and 11.3 pulses) and UV treatments (length of 50 cm, treatment time of 2.94 s, and flow rate of 8 mL/min). An additive effect was observed for the combination treatments (PEF and UV), regardless of the order of treatment (P > 0.05). E. coli reductions of 5.35 and 5.30 log CFU/mL with PEF treatment (electrical field strength of 60 kV/cm, specific energy of 162 J/mL, and 11.3 pulses) followed by UV (length of 30 cm, treatment time of 1.8 s, and flow rate of 8 mL/min) and UV treatment followed by PEF (same treatment conditions), respectively. No synergistic effect was observed. PMID:19021811

  8. Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium

    PubMed Central

    Yun, Ou; Zeng, Xin-An; Brennan, Charles S.; Han, Zhong

    2016-01-01

    Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0–4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms. PMID:27556460

  9. Inactivation of Escherichia coli phage by pulsed electric field treatment and analysis of inactivation mechanism

    NASA Astrophysics Data System (ADS)

    Tanino, Takanori; Yoshida, Tomoki; Sakai, Kazuki; Ohshima, Takayuki

    2013-03-01

    Inactivation of bacteriophage by pulsed electric field (PEF) treatment, one of the effective procedures for bacteria nonthermal inactivation, was studied. Model phage particles Escherichia coli bacteriophages M13mp18 and λ phage, were successfully inactivated by PEF treatment. The survival ratios of both bacteriophages decreased depending on the PEF treatment time when applied peak voltage was 5 or 7 kV, and the survival ratios after 12 min PEF treatment were 10-4 - 10-5. Electrophoresis analyses of biological molecules of inactivated λ phage detected no degradation of total protein and genomic DNA. These results suggested that the factor of phage inactivation by PEF treatment was not based on the degradation of protein or DNA, but on the destruction of phage particle structure. Sensitivity of E. coli phage to PEF treatment was compared with that of E. coli cell. Phage and MV1184 cell were treated with same condition PEF at 5 kV, respectively. After 12 min treatment, the survival ration of λ phage and MV1184 were 4.0 × 10-5 and 1.7 × 10-3, respectively. The survival ratio of phage was lower than that of MV1184. E. coli cell is more tolerant to inactivation with PEF treatment than coli phage.

  10. Effect of pulsed electric fields assisted acetylation on morphological, structural and functional characteristics of potato starch.

    PubMed

    Hong, Jing; Chen, Rujiao; Zeng, Xin-An; Han, Zhong

    2016-02-01

    Pulsed electric fields (PEF)-assisted acetylation of potato starch with different degree of substitution (DS) was prepared and effects of PEF strength, reaction time, starch concentration on DS were studied by response surface methodology. Results showed DS was increased from 0.054 (reaction time of 15 min) to 0.130 (reaction time of 60 min) as PEF strength increased from 3 to 5 kV/cm. External morphology revealed that acetylated starch with higher DS was aggravated more bulges and asperities. Fourier-transformed infrared spectroscopy confirmed the introduction of acetyl group through a band at 1730 cm(-1). The optimum sample (DS =0 .13) had lower retrogradation (39.1%), breakdown (155 BU) and setback value (149BU), while pasting temperature (62.2 °C) was slightly higher than non-PEF-assisted samples. These results demonstrated PEF treatment can be a potential and beneficial method for acetylation and achieve higher DS with shorter reaction time. PMID:26304315

  11. Treatment of cancer using pulsed electric field in combination with chemotherapeutic agents or genes.

    PubMed

    Nishi, T; Dev, S B; Yoshizato, K; Kuratsu, J; Ushio, Y

    1997-03-01

    Electroporation is a standard laboratory technique originally developed for in vitro transfer of molecules into cells. It involves application of electrical pulses ranging from micro- to milliseconds that create transient pores in the cell membrane allowing intracellular access of exogenous molecules. This technique has been successfully applied to regress tumors in animal models by combining electroporation with chemotherapeutic agents--a process known as electrochemotherapy (ECT) which substantially enhance cytotoxicity of some antineoplastic agents. Recently ECT has moved into clinical arena and patients with cutaneous tumors and head and neck cancers have been treated very effectively with ECT. Parallel to ECT, a technique has also been developed which makes it possible to inject plasmid DNA and combine it with in vivo electroporation--electro--genetherapy (EGT)--to deliver in a highly efficient manner both marker and functional genes into target tissue and achieve gene expression. Thus, in vivo electroporation is contributing to the development of a new strategy for cancer treatment with both drugs and genes. PMID:9234068

  12. Activation of autophagy in response to nanosecond pulsed electric field exposure.

    PubMed

    Ullery, Jody C; Tarango, Melissa; Roth, Caleb C; Ibey, Bennett L

    2015-03-01

    Previous work demonstrated significant changes in cellular membranes following exposure of cells to nanosecond pulsed electric fields (nsPEF), including nanoporation and increases in intracellular calcium concentration. While it is known that nsPEF exposure can cause cell death, how cells repair and survive nsPEF-induced cellular damage is not well understood. In this paper, we investigated whether autophagy is stimulated following nsPEF exposure to repair damaged membranes, proteins, and/or organelles in a pro-survival response. We hypothesized that autophagy is activated to repair nsPEF-induced plasma membrane damage and overwhelming this compensatory mechanism results in cell death. Activation of autophagy and subsequent cell death pathways were assessed measuring toxicity, gene and protein expression of autophagy markers, and by monitoring autophagosome formation and maturation using fluorescent microscopy. Results show that autophagy is activated at subtoxic nsPEF doses, as a compensatory mechanism to repair membrane damage. However, prolonged exposure results in increased cell death and a concomitant decrease in autophagic markers. These results suggest that cells take an active role in membrane repair, through autophagy, following exposure to nsPEF. PMID:25660455

  13. Decontamination of collagen biomatrices with combined pulsed electric field and nisin treatment.

    PubMed

    Griffiths, Sarah; Maclean, Michelle; Macgregor, Scott J; Anderson, John G; Helen Grant, M

    2011-02-01

    Pulsed electric field (PEF) treatment has been proposed as a decontamination method for labile matrices used in tissue engineering applications. Through the application of PEF, a non-thermal treatment that causes bacterial inactivation through the irreversible rupture of microbial cell membranes, inactivation is achieved without loss of scaffold structure and function. However, some microorganisms are less susceptible to PEF treatment. This study shows that treatment with PEF and nisin, a food preservative bacteriocin, has a synergistic effect on the inactivation of Staphylococcus epidermidis in collagen gels. Almost complete inactivation of a 10(3) -10(4) CFU/mL S. epidermidis population was achieved when treated with a combination of PEF and 500 IU/mL nisin, with results demonstrating a 3.4 log(10) reduction, compared with 0.66 log(10) reduction with PEF alone. Nisin, at concentrations up to 3000 IU/mL, had no discernable toxicity to mammalian 3T3 cells when added to the culture medium or incorporated into the collagen gels. This combined decontamination method, involving PEF plus nisin, may provide a non-destructive process for inactivation of PEF-resistant bacteria in labile tissue engineering scaffolds. PMID:21210508

  14. Effects of Pulsed Electric Fields (PEF) on Vitamin C and Its Antioxidant Properties

    PubMed Central

    Zhang, Zhi-Hong; Zeng, Xin-An; Brennan, Charles S.; Brennan, Margaret; Han, Zhong; Xiong, Xia-Yu

    2015-01-01

    In this study, pulsed electric fields (PEF) treatments and their effects on the structure of vitamin C (VIT-C) were estimated by fluorescence and Fourier transform infrared (FT-IR) spectroscopy, the relative content of VIT-C was measured by HPLC and the antioxidant properties of treated VIT-C by DPPH radical scavenging as well as reducing power tests. The fluorescence intensity of treated VIT-C increased slightly compared to the untreated VIT-C. Moreover, the effect of PEF on the structure of VIT-C was observed using the FT-IR spectra. These phenomena indicated that the PEF affected the conformation of VIT-C, which promoted the VIT-C isomer transformed enol-form into keto-form. In addition, the PEF treatments did not suffer the damage to VIT-C and could slow down the oxidation process in involving of experimental conditions by HPLC. The antioxidant properties of the treated VIT-C were enhanced, which was proved by radical scavenging and also the reducing power tests. PMID:26473846

  15. Effects of pulsed electric fields on the quality of orange juice and comparison with heat pasteurization.

    PubMed

    Yeom, H W; Streaker, C B; Zhang, Q H; Min, D B

    2000-10-01

    Effects of pulsed electric fields (PEF) at 35 kV/cm for 59 micros on the quality of orange juice were investigated and compared with those of heat pasteurization at 94.6 degrees C for 30 s. The PEF treatment prevented the growth of microorganisms at 4, 22, and 37 degrees C for 112 days and inactivated 88% of pectin methyl esterase (PME) activity. The PEF-treated orange juice retained greater amounts of vitamin C and the five representative flavor compounds than the heat-pasteurized orange juice during storage at 4 degrees C (p < 0.05). The PEF-treated orange juice had lower browning index, higher whiteness (L), and higher hue angle (theta) values than the heat-pasteurized orange juice during storage at 4 degrees C (p < 0. 05). The PEF-treated orange juice had a smaller particle size than the heat-pasteurized orange juice (p < 0.05). degrees Brix and pH values were not significantly affected by processing methods (p > 0. 05). PMID:11052706

  16. Effects of pulsed electric fields on pathogenic microorganisms of major concern in fluid foods: a review.

    PubMed

    Mosqueda-Melgar, Jonathan; Elez-Martínez, Pedro; Raybaudi-Massilia, Rosa M; Martín-Belloso, Olga

    2008-09-01

    Pathogenic microorganisms such as Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Yersinia enterocolitica, and Campylobacter jejuni have been implicated in foodborne diseases and outbreaks worldwide. These bacteria have been associated with the consumption of fresh fruit juices, milk, and dairy products, which are foodstuff, highly demanded by consumers in retails and supermarkets. Nowadays, consumers require high quality, fresh-like, and safe foods. Pulsed electric field (PEF) is a non-thermal preservation method, able to inactivate pathogenic microorganisms without significant loss of the organoleptic and nutritional properties of food. The PEF treatment effectiveness to destroy bacteria such as Listeria innocua, E. coli, Salmonella Typhimurium, E. coli O157:H7 and E. coli 8739 at pasteurization levels (> or = 5.0 log(10) cycles) in some fluid foods was reported. However, data on the inactivation of some microorganisms such as Bacillus cereus, Staphylococcus aureus, Yersinia enterocolitica, and Campylobacter jejuni in fluid foods by PEF processing is very limited. Therefore, future works should be focused toward the inactivation of these pathogenic bacteria in real foods. PMID:18756397

  17. Direct activation of the Mauthner cell by electric field pulses drives ultrarapid escape responses.

    PubMed

    Tabor, Kathryn M; Bergeron, Sadie A; Horstick, Eric J; Jordan, Diana C; Aho, Vilma; Porkka-Heiskanen, Tarja; Haspel, Gal; Burgess, Harold A

    2014-08-15

    Rapid escape swims in fish are initiated by the Mauthner cells, giant reticulospinal neurons with unique specializations for swift responses. The Mauthner cells directly activate motoneurons and facilitate predator detection by integrating acoustic, mechanosensory, and visual stimuli. In addition, larval fish show well-coordinated escape responses when exposed to electric field pulses (EFPs). Sensitization of the Mauthner cell by genetic overexpression of the voltage-gated sodium channel SCN5 increased EFP responsiveness, whereas Mauthner ablation with an engineered variant of nitroreductase with increased activity (epNTR) eliminated the response. The reaction time to EFPs is extremely short, with many responses initiated within 2 ms of the EFP. Large neurons, such as Mauthner cells, show heightened sensitivity to extracellular voltage gradients. We therefore tested whether the rapid response to EFPs was due to direct activation of the Mauthner cells, bypassing delays imposed by stimulus detection and transmission by sensory cells. Consistent with this, calcium imaging indicated that EFPs robustly activated the Mauthner cell but only rarely fired other reticulospinal neurons. Further supporting this idea, pharmacological blockade of synaptic transmission in zebrafish did not affect Mauthner cell activity in response to EFPs. Moreover, Mauthner cells transgenically expressing a tetrodotoxin (TTX)-resistant voltage-gated sodium channel retained responses to EFPs despite TTX suppression of action potentials in the rest of the brain. We propose that EFPs directly activate Mauthner cells because of their large size, thereby driving ultrarapid escape responses in fish. PMID:24848468

  18. Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium.

    PubMed

    Yun, Ou; Zeng, Xin-An; Brennan, Charles S; Han, Zhong

    2016-01-01

    Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0-4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms. PMID:27556460

  19. Picosecond pulsed electric fields induce apoptosis in a cervical cancer xenograft.

    PubMed

    Jia, Jia; Xiong, Zheng-Ai; Qin, Qin; Yao, Chen-Guo; Zhao, Xiao-Zhen

    2015-03-01

    The aim of the present study was to evaluate the efficacy of picosecond pulsed electric fields (psPEF) on a cervical cancer xenograft. Human cervical cancer xenografts were established in nude mice by transplantation of HeLa cells, and the tumors were then treated with psPEF. The histological changes were observed by hematoxylin‑eosin staining and transmission electron microscopy. The rate of tumor cell apoptosis was determined using a terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling assay. The mitochondrial transmembrane potential of the tumor cells was detected by laser scanning confocal microscopy, and the activity of caspase‑3, ‑8, ‑9 and ‑12 was determined. The inhibitory rate seven days post‑psPEF treatment was also calculated. The results showed that exposure to psPEF led to an increased rate of apoptosis, collapse of mitochondrial transmembrane potential, and activation of caspases. The inhibitory rate was 9.11% at day 7. The results of the present study indicate that psPEF may induce apoptosis in a cervical cancer xenograft through the endoplasmic reticulum stress and caspase‑dependent signaling pathways. PMID:25405328

  20. Electrical characterization of Si doped AlN films synthesized by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Simeonov, Simeon; Bakalova, Silvia; Szekeres, Anna; Minkov, Ivaylo; Socol, Gabriel; Ristoscu, Carmen; Mihailescu, Ion

    2015-04-01

    The electrical properties of thin AlN films doped with Si (AlN:Si) have been investigated. The films were synthesized on Si substrates at 800 °C by pulsed laser deposition in low-pressure nitrogen ambient. The AlN:Si films exhibit non-ohmic I-V characteristics and the current through these films is controlled by space charge limited current. The C-V dependence of metal-insulator-silicon (MIS) structures with AlN:Si films exhibits an excess capacitance around zero bias voltage. This excess capacitance indicates the presence of deep acceptor levels situated at the boundaries of adjacent grains in the AlN:Si films. The Si donor density in the AlN:Si films, estimated from the 1 MHz C-V characteristics, is of the order of 1018 cm-3. The impedance measurements of these AlN:Si structures at different test voltage frequencies reveal that the charge transport mechanism is dominated by either thermally-activated hopping or electron tunneling from occupied to nearest unoccupied deep levels.

  1. Characteristics and Antitumor Activity of Morchella esculenta Polysaccharide Extracted by Pulsed Electric Field

    PubMed Central

    Liu, Chao; Sun, Yonghai; Mao, Qian; Guo, Xiaolei; Li, Peng; Liu, Yang; Xu, Na

    2016-01-01

    Polysaccharides from Morchella esculenta have been proven to be functional and helpful for humans. The purpose of this study was to investigate the chemical structure and anti-proliferating and antitumor activities of a Morchella esculenta polysaccharide (MEP) extracted by pulsed electric field (PEF) in submerged fermentation. The endo-polysaccharide was separated and purified by column chromatography and Gel permeation chromatography, and analyzed by gas chromatography. The MEP with an average molecular weight of 81,835 Da consisted of xylose, glucose, mannose, rhamnose and galactose at the ratio of 5.4:5.0:6.5:7.8:72.3. Structure of MEP was further analyzed by Fourier-transform infrared spectroscopy and 1H and 13C liquid-state nuclear magnetic resonance spectroscopy. Apoptosis tests proved that MEP could inhibit the proliferation and growth of human colon cancer HT-29 cells in a time- and dose-dependent manner within 48 h. This study provides more information on chemical structure of anti-proliferating polysaccharides isolated from Morchella esculenta. PMID:27338370

  2. Direct activation of the Mauthner cell by electric field pulses drives ultrarapid escape responses

    PubMed Central

    Tabor, Kathryn M.; Bergeron, Sadie A.; Horstick, Eric J.; Jordan, Diana C.; Aho, Vilma; Porkka-Heiskanen, Tarja; Haspel, Gal

    2014-01-01

    Rapid escape swims in fish are initiated by the Mauthner cells, giant reticulospinal neurons with unique specializations for swift responses. The Mauthner cells directly activate motoneurons and facilitate predator detection by integrating acoustic, mechanosensory, and visual stimuli. In addition, larval fish show well-coordinated escape responses when exposed to electric field pulses (EFPs). Sensitization of the Mauthner cell by genetic overexpression of the voltage-gated sodium channel SCN5 increased EFP responsiveness, whereas Mauthner ablation with an engineered variant of nitroreductase with increased activity (epNTR) eliminated the response. The reaction time to EFPs is extremely short, with many responses initiated within 2 ms of the EFP. Large neurons, such as Mauthner cells, show heightened sensitivity to extracellular voltage gradients. We therefore tested whether the rapid response to EFPs was due to direct activation of the Mauthner cells, bypassing delays imposed by stimulus detection and transmission by sensory cells. Consistent with this, calcium imaging indicated that EFPs robustly activated the Mauthner cell but only rarely fired other reticulospinal neurons. Further supporting this idea, pharmacological blockade of synaptic transmission in zebrafish did not affect Mauthner cell activity in response to EFPs. Moreover, Mauthner cells transgenically expressing a tetrodotoxin (TTX)-resistant voltage-gated sodium channel retained responses to EFPs despite TTX suppression of action potentials in the rest of the brain. We propose that EFPs directly activate Mauthner cells because of their large size, thereby driving ultrarapid escape responses in fish. PMID:24848468

  3. Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling

    PubMed Central

    Luu, Phan; Essaki Arumugam, Easwara Moorthy; Anderson, Erik; Gunn, Amanda; Rech, Dennis; Turovets, Sergei; Tucker, Don M.

    2016-01-01

    In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual’s cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling. PMID:27531976

  4. Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling.

    PubMed

    Luu, Phan; Essaki Arumugam, Easwara Moorthy; Anderson, Erik; Gunn, Amanda; Rech, Dennis; Turovets, Sergei; Tucker, Don M

    2016-01-01

    In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual's cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling. PMID:27531976

  5. Modulation of molecular hybridization and charge screening in a carbon nanotube network channel using the electrical pulse method.

    PubMed

    Woo, Jun-Myung; Kim, Seok Hyang; Chun, Honnggu; Kim, Sung Jae; Ahn, Jinhong; Park, Young June

    2013-09-21

    In this paper, we investigate the effect of electrical pulse bias on DNA hybridization events in a biosensor platform, using a Carbon Nanotube Network (CNN) and Gold Nano Particles (GNP) as an electrical channel. The scheme provides both hybridization rate enhancement of bio molecules, and electrical measurement in a transient state to avoid the charge screening effect, thereby significantly improving the sensitivity. As an example, the probe DNA molecules oscillate with pulse trains, resulting in the enhancement of DNA hybridization efficiency, and accordingly of the sensor performances in Tris-EDTA (TE) buffer solution, by as much as over three times, compared to the non-biasing conditions. More importantly, a wide dynamic range of 10(6) (target-DNA concentration from 5 pM to 5 μM) is achieved in human serum. In addition, the pulse biasing method enables one to obtain the conductance change, before the ions within the Electrical Double Layer (EDL) are redistributed, to avoid the charge screening effect, leading to an additional sensitivity enhancement. PMID:23900200

  6. Defining treatment conditions for pulsed electric field pasteurization of apple juice.

    PubMed

    Saldaña, G; Puértolas, E; Monfort, S; Raso, J; Alvarez, I

    2011-11-15

    The influence of temperature and the presence of N(α)-lauroyl ethylester (ethyl lauroyl arginate, LAE) on the inactivation caused by continuous pulsed electric field treatments (PEF) in Escherichia coli O157:H7 suspended in apple juice have been investigated to define treatment conditions applicable at industrial scale that promote an equivalent safety level when compared with thermal processing. In the range of experimental conditions investigated (outlet temperature: 20-40 °C, electric field strength: 20-30 kV, treatment time: 5-125 μs) at outlet temperatures equal or lower than 55±1 °C, the inactivation of E. coli O157:H7 treated in apple juice ranged from 0.4 to 3.6 Log₁₀ cycles reduction and treated in apple juice supplemented with LAE (50 ppm) ranged from 0.9 to 6.7 Log₁₀ cycles reduction. An empirical mathematical model was developed to estimate the treatment time and total specific energy input to obtain 5 Log₁₀ cycles reduction in the population of E. coli O157:H7 suspended in apple juice supplemented with 50 ppm of LAE at different electric field strengths and inlet temperatures. Treatment conditions established for E. coli O157:H7 were validated with other PEF resistant Gram-positive (Listeria monocytogenes, and Staphylococcus aureus) and Gram-negative (Salmonella enterica serovar Typhimurium) strains. When the treatment was applied to the apple juice, a treatment of 25 kV/cm for 63 μs corresponding with an outlet temperature of 65 °C and input energy of 125 kJ/kg was required to achieve more than 5 Log₁₀ cycles in the four strains investigated. The addition of LAE reduced the treatment time required to obtain an equivalent inactivation (>5 Log₁₀ cycles) in the four microorganisms to 38.4 μs, the outlet temperature to 55 °C, and the input energy to 83.2 kJ/kg. PMID:21880388

  7. The application of weak electric field pulses to measure the pseudo-Stark split by photon echo beating

    NASA Astrophysics Data System (ADS)

    Lisin, V. N.; Shegeda, A. M.; Samartsev, V. V.

    2016-07-01

    A novel scheme for determining the pseudo-Stark splitting of optical lines has been suggested and tested in experiment. The scheme allows one to observe the beating of a photon echo waveform under conditions of overlap in time between a weak electric pulse and its echo-pulse. The pseudo-Stark splitting is equal to the inverse average modulation period of the echo waveform. The photon echo beating of the R1-line in Ruby has been observed. The dependence of the inverse average modulation period of the echo waveform on the average value of the electric field over the optically excited volume has been found. The obtained values of the pseudo-Stark parameter are in good agreement with known literature data.

  8. Optical-induced electrical current in diamond switched by femtosecond-attosecond laser pulses by ab initio simulations

    NASA Astrophysics Data System (ADS)

    Gao, L. L.; Wang, F.; Jiang, L.; Qu, L. T.; Lu, Y. F.

    2016-01-01

    The electric current has been switched in diamond by a dual-laser field with an attosecond pulse train and a femtosecond laser, respectively serving to excite and drive electrons. The optical-induced current is simulated by the developed method based on the time-dependent density functional theory. The electric current is induced within several attoseconds with the diamond’s conductivity increased by 16~23 orders of magnitude. Our work opens the way to extending electronic signal processing from the present gigahertz domain into the exahertz domain.

  9. Effect of high-intensity pulsed electric fields processing and conventional heat treatment on orange-carrot juice carotenoids.

    PubMed

    Torregrosa, Francisco; Cortés, Clara; Esteve, María J; Frígola, Ana

    2005-11-30

    Liquid chromatography (LC) was the method of choice for quantification of carotenoids (including geometrical isomers) to evaluate the effects of high-intensity pulsed electric field (HIPEF), a nonthermal preservation method, with different parameters (electric field intensities and treatment times), on an orange-carrot juice mixture (80:20, v/v). In parallel, a conventional heat treatment (98 degrees C, 21 s) was applied to the juice. HIPEF processing generally caused a significant increase in the concentrations of the carotenoids identified as treatment time increased. HIPEF treatment at 25 and 30 kV/cm provided a vitamin A concentration higher than that found in the pasteurized juice. PMID:16302771

  10. Single attosecond pulse generation in an orthogonally polarized two-color laser field combined with a static electric field

    SciTech Connect

    Xia Changlong; Zhang Gangtai; Wu Jie; Liu Xueshen

    2010-04-15

    We investigate theoretic high-order harmonic generation and single attosecond pulse generation in an orthogonally polarized two-color laser field, which is synthesized by a mid-infrared (IR) pulse (12.5 fs, 2000 nm) in the y component and a much weaker (12 fs, 800 nm) pulse in the x component. We find that the width of the harmonic plateau can be extended when a static electric field is added in the y component. We also investigate emission time of harmonics in terms of a time-frequency analysis to illustrate the physical mechanism of high-order harmonic generation. We calculate the ionization rate using the Ammosov-Delone-Krainov model and interpret the variation of harmonic intensity for different static electric field strengths. When the ratio of strengths of the static and the y-component laser fields is 0.1, a continuous harmonic spectrum is formed from 220 to 420 eV. By superposing a properly selected range of the harmonic spectrum from 300 to 350 eV, an isolated attosecond pulse with a duration of about 75 as is obtained, which is near linearly polarized.

  11. Pulsed electric fields-processed orange juice consumption increases plasma vitamin C and decreases F2-isoprostanes in healthy humans.

    PubMed

    Sánchez-Moreno, Concepción; Cano, M Pilar; de Ancos, Begoña; Plaza, Lucía; Olmedilla, Begoña; Granado, Fernando; Elez-Martínez, Pedro; Martín-Belloso, Olga; Martín, Antonio

    2004-10-01

    Orange juice, a rich source of vitamin C, accounts for 60% of all fruit juices and juice-based drinks consumed in western Europe. Orange juice preservation is currently accomplished by traditional pasteurization. Pulsed electric fields (PEF) have been studied as a nonthermal food preservation method. Food technology needs in the area of processing are driven by nutrition. Therefore, the objectives of this study were to assess the bioavailability of vitamin C from pulsed electric fields-treated orange juice in comparison with freshly squeezed orange juice and its impact on 8-epiPGF(2alpha) concentrations (biomarker of lipid peroxidation) in a healthy human population. Six subjects consumed 500 mL/day of pulsed electric fields-treated orange juice and six subjects consumed 500 mL/day of freshly squeezed orange juice for 14 days, corresponding to an intake of about 185 mg/day of ascorbic acid. On the first day of the study, subjects drank the juice in one dose, and on days 2-14 they consumed 250 mL in the morning and 250 mL in the afternoon. Blood was collected every hour for 6 hours on the first day and again on days 7 and 14. In the dose-response study, the maximum increase in plasma vitamin C occurred 4 hours postdose. Vitamin C remained significantly higher on days 7 and 14 in both orange juice groups. Plasma 8-epiPGF(2alpha) concentrations was lower at the end of the study (P < 0.001) in both groups. Plasma levels of vitamin C and 8-epiPGF(2alpha) were inversely correlated. Pulsed electric fields-preservation of orange juice retains the vitamin C bioavailability and antioxidant properties of fresh juice with a longer shelf-life. PMID:15542351

  12. Desynchronization of electrically evoked auditory-nerve activity by high-frequency pulse trains of long duration

    NASA Astrophysics Data System (ADS)

    Litvak, Leonid M.; Smith, Zachary M.; Delgutte, Bertrand; Eddington, Donald K.

    2003-10-01

    Rubinstein et al. [Hear. Res. 127, 108-118 (1999)] suggested that the neural representation of the waveforms of electric stimuli might be improved by introducing an ongoing, high-rate, desynchronizing pulse train (DPT). A DPT may desynchronize neural responses to electric stimulation in a manner similar to spontaneous activity in a healthy ear. To test this hypothesis, responses of auditory-nerve fibers (ANFs) to 10-min-long electric pulse trains (5 kpps) were recorded from acutely deafened, anesthetized cats. Stimuli were delivered via an intracochlear electrode, and their amplitude was chosen to elicit a response in most ANFs. Responses to pulse trains showed pronounced adaptation during the first 1-2 min, followed by either a sustained response or cessation of spike discharges for the remainder of the stimulus. The adapted discharge rates showed a broad distribution across the ANF population like spontaneous activity. However, a higher proportion of fibers (46%) responded to the DPT at rates below 5 spikes/s than for spontaneous activity, and 12% of the fibers responded at higher rates than any spontaneously active fiber. Interspike interval histograms of sustained responses for some fibers had Poisson-like (exponential) shapes, resembling spontaneous activity, while others exhibited preferred intervals and, occasionally, bursting. Simultaneous recordings from pairs of fibers revealed no evidence of correlated activity, suggesting that the DPT does desynchronize the auditory nerve activity. Overall, these results suggest that responses to an ongoing DPT resemble spontaneous activity in a normal ear for a substantial fraction of the ANFs.

  13. Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

    PubMed Central

    Pei, Bao-an; Zi, Jin-hua; Wu, Li-sheng; Zhang, Cun-hua; Chen, Yun-zhen

    2015-01-01

    Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 mA and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers. PMID:26692864

  14. Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury.

    PubMed

    Pei, Bao-An; Zi, Jin-Hua; Wu, Li-Sheng; Zhang, Cun-Hua; Chen, Yun-Zhen

    2015-10-01

    Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 mA and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers. PMID:26692864

  15. Pulsed Electric Field inactivation of microbial cells: the use of ceramic layers to increase the efficiency of treatment

    NASA Astrophysics Data System (ADS)

    Pizzichemi, M.

    2009-12-01

    The impact of Pulsed Electric Fields (PEF) on bacteria and plant or animal cells has been investigated since the early 1960s. High electric fields pulses (20-70 kV/cm, 1-10 μs) are reported to cause rupture of the cellular lipid membrane, through the mechanism of irreversible electroporation. Quantitative description of cell inactivation kinetics is based on the analysis of stability of lipid bilayers under electric fields and the thermal fluctuations associated with the production of pores. PEF has been successfully applied to inactivation of both Gram-positive and Gram-negative bacteria in many sorts of liquids, such as milk, fruit juices and liquid eggs. In all these media, the level of inactivation could reach the 5 Logs for an approximate range of pulses of 100-200, and an energy consumption of ˜ 10-100 kJ/kg. The advantages of PEF are the superior maintenance of functional and nutritional levels (if compared to traditional thermal treatment), continuous treatment and short processing times, while the current high costs of this technique make it more suitable for treatment of expensive media. We present a solution to the problem of volumes in PEF treatment through the use of high permittivity ceramics, while retaining the same inactivation efficiency and improving the duration of the electrodes.

  16. Picosecond electric field pulse induced coherent magnetic switching in MgO/FePt/Pt(001)-based tunnel junctions: a multiscale study.

    PubMed

    Zhu, Wanjiao; Xiao, Dun; Liu, Yaowen; Gong, S J; Duan, Chun-Gang

    2014-01-01

    Combined methods of first-principles calculations and Landau-Lifshitz-Gilbert (LLG) macrospin simulations are performed to investigate the coherent magnetization switching in the MgO/FePt/Pt(001)-based magnetic tunnel junctions triggered by short pulses of electric field through the control of magnetic anisotropy energy (MAE) electrically. First-principles calculations indicate that the MAE of MgO/FePt/Pt(001) film varies linearly with the change of the electric field, whereas the LLG simulations show that the change in MAE by electric field pulses could induce the in-plane magnetization reversal of the free layer by tuning the pulse parameters. We find that there exist a critical pulse width τmin to switch the in-plane magnetization, and this τmin deceases with the increasing pulse amplitude E0. Besides, the magnetization orientation cannot be switched when the pulse width exceeds a critical value τmax, and τmax increases asymptotically with E0. In addition, there exist some irregular switching areas at short pulse width due to the high precessional frequency under small initial angle. Finally, a successive magnetization switching can be achieved by a series of electric field pulses. PMID:24844293

  17. Picosecond electric field pulse induced coherent magnetic switching in MgO/FePt/Pt(001)-based tunnel junctions: a multiscale study

    PubMed Central

    Zhu, Wanjiao; Xiao, Dun; Liu, Yaowen; Gong, S. J.; Duan, Chun-Gang

    2014-01-01

    Combined methods of first-principles calculations and Landau-Lifshitz-Gilbert (LLG) macrospin simulations are performed to investigate the coherent magnetization switching in the MgO/FePt/Pt(001)-based magnetic tunnel junctions triggered by short pulses of electric field through the control of magnetic anisotropy energy (MAE) electrically. First-principles calculations indicate that the MAE of MgO/FePt/Pt(001) film varies linearly with the change of the electric field, whereas the LLG simulations show that the change in MAE by electric field pulses could induce the in-plane magnetization reversal of the free layer by tuning the pulse parameters. We find that there exist a critical pulse width τmin to switch the in-plane magnetization, and this τmin deceases with the increasing pulse amplitude E0. Besides, the magnetization orientation cannot be switched when the pulse width exceeds a critical value τmax, and τmax increases asymptotically with E0. In addition, there exist some irregular switching areas at short pulse width due to the high precessional frequency under small initial angle. Finally, a successive magnetization switching can be achieved by a series of electric field pulses. PMID:24844293

  18. Cytoprotective Role of Nrf2 in Electrical Pulse Stimulated C2C12 Myotube

    PubMed Central

    Horie, Masaki; Warabi, Eiji; Komine, Shoichi; Oh, Sechang; Shoda, Junichi

    2015-01-01

    Regular physical exercise is central to a healthy lifestyle. However, exercise-related muscle contraction can induce reactive oxygen species and reactive nitrogen species (ROS/RNS) production in skeletal muscle. The nuclear factor-E2-related factor-2 (Nrf2) transcription factor is a cellular sensor for oxidative stress. Regulation of nuclear Nrf2 signaling regulates antioxidant responses and protects organ structure and function. However, the role of Nrf2 in exercise- or contraction-induced ROS/RNS production in skeletal muscle is not clear. In this study, using differentiated C2C12 cells and electrical pulse stimulation (EPS) of muscle contraction, we explored whether Nrf2 plays a role in the skeletal muscle response to muscle contraction-induced ROS/RNS. We found that EPS (40 V, 1 Hz, 2 ms) stimulated ROS/RNS accumulation and Nrf2 activation. We also showed that expression of NQO1, HO-1 and GCLM increased after EPS-induced muscle contraction and was remarkably suppressed in cells with Nrf2 knockdown. We also found that the antioxidant N-acetylcysteine (NAC) significantly attenuated Nrf2 activation after EPS, whereas the nitric oxide synthetase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) did not. Furthermore, Nrf2 knockdown after EPS markedly decreased ROS/RNS redox potential and cell viability and increased expression of the apoptosis marker Annexin V in C2C12 myotubes. These results indicate that Nrf2 activation and expression of Nrf2 regulated-genes protected muscle against the increased ROS caused by EPS-induced muscle contraction. Thus, our findings suggest that Nrf2 may be a key factor for preservation of muscle function during muscle contraction. PMID:26658309

  19. Intraoperative dorsal language network mapping by using single-pulse electrical stimulation.

    PubMed

    Yamao, Yukihiro; Matsumoto, Riki; Kunieda, Takeharu; Arakawa, Yoshiki; Kobayashi, Katsuya; Usami, Kiyohide; Shibata, Sumiya; Kikuchi, Takayuki; Sawamoto, Nobukatsu; Mikuni, Nobuhiro; Ikeda, Akio; Fukuyama, Hidenao; Miyamoto, Susumu

    2014-09-01

    The preservation of language function during brain surgery still poses a challenge. No intraoperative methods have been established to monitor the language network reliably. We aimed to establish intraoperative language network monitoring by means of cortico-cortical evoked potentials (CCEPs). Subjects were six patients with tumors located close to the arcuate fasciculus (AF) in the language-dominant left hemisphere. Under general anesthesia, the anterior perisylvian language area (AL) was first defined by the CCEP connectivity patterns between the ventrolateral frontal and temporoparietal area, and also by presurgical neuroimaging findings. We then monitored the integrity of the language network by stimulating AL and by recording CCEPs from the posterior perisylvian language area (PL) consecutively during both general anesthesia and awake condition. High-frequency electrical stimulation (ES) performed during awake craniotomy confirmed language function at AL in all six patients. Despite an amplitude decline (≤32%) in two patients, CCEP monitoring successfully prevented persistent language impairment. After tumor removal, single-pulse ES was applied to the white matter tract beneath the floor of the removal cavity in five patients, in order to trace its connections into the language cortices. In three patients in whom high-frequency ES of the white matter produced naming impairment, this "eloquent" subcortical site directly connected AL and PL, judging from the latencies and distributions of cortico- and subcortico-cortical evoked potentials. In conclusion, this study provided the direct evidence that AL, PL, and AF constitute the dorsal language network. Intraoperative CCEP monitoring is clinically useful for evaluating the integrity of the language network. PMID:24615889

  20. Nanosecond electric pulses affect a plant-specific kinesin at the plasma membrane.

    PubMed

    Kühn, Sebastian; Liu, Qiong; Eing, Christian; Frey, Wolfgang; Nick, Peter

    2013-12-01

    Electric pulses with high field strength and durations in the nanosecond range (nsPEFs) are of considerable interest for biotechnological and medical applications. However, their actual cellular site of action is still under debate--due to their extremely short rise times, nsPEFs are thought to act mainly in the cell interior rather than at the plasma membrane. On the other hand, nsPEFs can induce membrane permeability. We have revisited this issue using plant cells as a model. By mapping the cellular responses to nsPEFs of different field strength and duration in the tobacco BY-2 cell line, we could define a treatment that does not impinge on short-term viability, such that the physiological responses to the treatment can be followed. We observe, for these conditions, a mild disintegration of the cytoskeleton, impaired membrane localization of the PIN1 auxin-efflux transporter and a delayed premitotic nuclear positioning followed by a transient mitotic arrest. To address the target site of nsPEFs, we made use of the plant-specific KCH kinesin, which can assume two different states with different localization (either near the nucleus or at the cell membrane) driving different cellular functions. We show that nsPEFs reduce cell expansion in nontransformed cells but promote expansion in a line overexpressing KCH. Since cell elongation and cell widening are linked to the KCH localized at the cell membrane, the inverted response in the KCH overexpressor provides evidence for a direct action of nsPEFs, also at the cell membrane. PMID:24062185

  1. Real time kinetic flow cytometry measurements of cellular parameter changes evoked by nanosecond pulsed electric field.

    PubMed

    Orbán, Csaba; Pérez-García, Esther; Bajnok, Anna; McBean, Gethin; Toldi, Gergely; Blanco-Fernandez, Alfonso

    2016-05-01

    Nanosecond pulsed electric field (nsPEF) is a novel method to increase cell proliferation rate. The phenomenon is based on the microporation of cellular organelles and membranes. However, we have limited information on the effects of nsPEF on cell physiology. Several studies have attempted to describe the effects of this process, however no real time measurements have been conducted to date. In this study we designed a model system which allows the measurement of cellular processes before, during and after nsPEF treatment in real time. The system employs a Vabrema Mitoplicator(TM) nsPEF field generating instrument connected to a BD Accuri C6 cytometer with a silicon tube led through a peristaltic pump. This model system was applied to observe the effects of nsPEF in mammalian C6 glioblastoma (C6 glioma) and HEK-293 cell lines. Viability (using DRAQ7 dye), intracellular calcium levels (using Fluo-4 dye) and scatter characteristics were measured in a kinetic manner. Data were analyzed using the FACSKin software. The viability and morphology of the investigated cells was not altered upon nsPEF treatment. The response of HEK-293 cells to ionomycin as positive control was significantly lower in the nsPEF treated samples compared to non-treated cells. This difference was not observed in C6 cells. FSC and SSC values were not altered significantly by the nsPEF treatment. Our results indicate that this model system is capable of reliably investigating the effects of nsPEF on cellular processes in real time. © 2016 International Society for Advancement of Cytometry. PMID:26990601

  2. Robust, Efficient, and Practical Electrogene Transfer Method for Human Mesenchymal Stem Cells Using Square Electric Pulses

    PubMed Central

    Liew, Aaron; Lesueur, Léa L.; De Ménorval, Marie-Amélie; O'Brien, Timothy; Mir, Lluis M.

    2013-01-01

    Abstract Mesenchymal stem cells (MSCs) are multipotent nonhematopoietic cells with the ability to differentiate into various specific cell types, thus holding great promise for regenerative medicine. Early clinical trials have proven that MSC-based therapy is safe, with possible efficacy in various diseased states. Moreover, genetic modification of MSCs to improve their function can be safely achieved using electrogene transfer. We previously achieved transfection efficiencies of up to 32% with preserved viability in rat MSCs. In this study, we further improved the transfection efficiency and transgene expression in human MSCs (hMSCs), while preserving the cells viability and ability to differentiate into osteoblasts and adipocytes by increasing the plasmid concentration and altering the osmotic pressure of the electrotransfer buffer. Using a square-wave electric pulse generator, we achieved a transfection efficiency of more than 80%, with around 70% viability and a detectable transgene expression of up to 30 days. Moreover, we demonstrated that this transfection efficiency can be reproduced reliably on two different sources of hMSCs: the bone marrow and adipose tissue. We also showed that there was no significant donor variability in terms of their transfection efficiency and viability. The cell confluency before electrotransfer had no significant effect on the transfection efficiency and viability. Cryopreservation of transfected cells maintained their transgene expression and viability upon thawing. In summary, we are reporting a robust, safe, and efficient protocol of electrotransfer for hMSCs with several practical suggestions for an optimal use of genetically engineered hMSCs for clinical application. PMID:23931158

  3. DNA Electrophoretic Migration Patterns Change after Exposure of Jurkat Cells to a Single Intense Nanosecond Electric Pulse

    PubMed Central

    Romeo, Stefania; Zeni, Luigi; Sarti, Maurizio; Sannino, Anna; Scarfì, Maria Rosaria; Vernier, P. Thomas; Zeni, Olga

    2011-01-01

    Intense nanosecond pulsed electric fields (nsPEFs) interact with cellular membranes and intracellular structures. Investigating how cells respond to nanosecond pulses is essential for a) development of biomedical applications of nsPEFs, including cancer therapy, and b) better understanding of the mechanisms underlying such bioelectrical effects. In this work, we explored relatively mild exposure conditions to provide insight into weak, reversible effects, laying a foundation for a better understanding of the interaction mechanisms and kinetics underlying nsPEF bio-effects. In particular, we report changes in the nucleus of Jurkat cells (human lymphoblastoid T cells) exposed to single pulses of 60 ns duration and 1.0, 1.5 and 2.5 MV/m amplitudes, which do not affect cell growth and viability. A dose-dependent reduction in alkaline comet-assayed DNA migration is observed immediately after nsPEF exposure, accompanied by permeabilization of the plasma membrane (YO-PRO-1 uptake). Comet assay profiles return to normal within 60 minutes after pulse delivery at the highest pulse amplitude tested, indicating that our exposure protocol affects the nucleus, modifying DNA electrophoretic migration patterns. PMID:22164287

  4. Development of double-pulse lasers ablation system for generating gold ion source under applying an electric field

    NASA Astrophysics Data System (ADS)

    Khalil, A. A. I.

    2015-12-01

    Double-pulse lasers ablation (DPLA) technique was developed to generate gold (Au) ion source and produce high current under applying an electric potential in an argon ambient gas environment. Two Q-switched Nd:YAG lasers operating at 1064 and 266 nm wavelengths are combined in an unconventional orthogonal (crossed-beam) double-pulse configuration with 45° angle to focus on a gold target along with a spectrometer for spectral analysis of gold plasma. The properties of gold plasma produced under double-pulse lasers excitation were studied. The velocity distribution function (VDF) of the emitted plasma was studied using a dedicated Faraday-cup ion probe (FCIP) under argon gas discharge. The experimental parameters were optimized to attain the best signal to noise (S/N) ratio. The results depicted that the VDF and current signals depend on the discharge applied voltage, laser intensity, laser wavelength and ambient argon gas pressure. A seven-fold increases in the current signal by increasing the discharge applied voltage and ion velocity under applying double-pulse lasers field. The plasma parameters (electron temperature and density) were also studied and their dependence on the delay (times between the excitation laser pulse and the opening of camera shutter) was investigated as well. This study could provide significant reference data for the optimization and design of DPLA systems engaged in laser induced plasma deposition thin films and facing components diagnostics.

  5. Optical visualization and electrical characterization of fast-rising pulsed dielectric barrier discharge for airflow control applications

    NASA Astrophysics Data System (ADS)

    Benard, Nicolas; Zouzou, Nourredine; Claverie, Alain; Sotton, Julien; Moreau, Eric

    2012-02-01

    Flow control consists of manipulating flows in an effective and robust manner to improve the global performances of transport systems or industrial processes. Plasma technologies, and particularly surface dielectric barrier discharge (DBD), can be a good candidate for such purpose. The present experimental study focuses on optical and electrical characterization of plasma sheet formed by applying a pulse of voltage with rising and falling periods of 50 ns for a typical surface DBD geometry. Positive and negative polarities are compared in terms of current behavior, deposited energy, fast-imaging of the plasma propagation, and resulting modifications of the surrounding medium by using shadowgraphy acquisitions. Positive and negative pulses of voltage produce streamers and corona type plasma, respectively. Both of them result in the production of a localized pressure wave propagating in the air with a speed maintained at 343 m/s (measurements at room temperature of 20 °C). This suggests that the produced pressure wave can be considered as a propagating sound wave. The intensity of the pressure wave is directly connected to the dissipated energy at the dielectric wall with a linear increase with the applied voltage amplitude and a strong dependence toward the rising time. At constant voltage amplitude, the pressure wave is reinforced by using a positive pulse. The present investigation also reveals that rising and decaying periods of a single pulse of voltage result in two distinct pressure waves. As a result, superposition or successive pressure wave can be produced by adjusting the width of the pulse.

  6. Effect of pulsed electric fields on the flavour profile of red-fleshed sweet cherries (Prunus avium var. Stella).

    PubMed

    Sotelo, Kristine Ann Gualberto; Hamid, Nazimah; Oey, Indrawati; Gutierrez-Maddox, Noemi; Ma, Qianli; Leong, Sze Ying

    2015-01-01

    The aim of this research was to study the effect of pulsed electric fields (PEF) on the flavour profile of red-fleshed sweet cherries (Prunus avium variety Stella). The cherry samples were treated at a constant pulse frequency of 100 Hz, a constant pulse width of 20 μs, different electric field strengths between 0.3 and 2.5 kV/cm and specific energy ranging from 31 to 55 kJ/kg. Volatile compounds of samples were analysed using an automated headspace solid phase microextraction (HS-SPME) method coupled with gas chromatography-mass spectrometry (GC-MS). A total of 33 volatile compounds were identified with benzaldehyde, hexanal, (E)-2-hexenal, (Z)-2-hexen-1-ol, and benzyl alcohol being the predominant volatiles in different PEF-treated samples. Aldehydes namely butanal, octanal, 2-octenal, and nonanal, and (Z)-2-hexen-1-ol increased significantly 24 h after PEF treatment at electric field strengths of more than 1.0 kV/cm. Samples incubated for 24 h after PEF treatment (S3) generated higher concentrations of volatiles than samples immediately after PEF treatments (S2). Quantitative results revealed that more flavour volatiles were released and associated with S3 samples after 24 h storage and S2 samples immediately after PEF both with the highest electric field intensities. Interestingly, this study found that the PEF treatments at the applied electric field strength and energy did not result in releasing/producing undesirable flavour compounds. PMID:25806548

  7. Measurement and simulation of Joule heating during treatment of B-16 melanoma tumors in mice with nanosecond pulsed electric fields.

    PubMed

    Pliquett, Uwe; Nuccitelli, Richard

    2014-12-01

    Experimental evidence shows that nanosecond pulsed electric fields (nsPEF) trigger apoptosis in skin tumors. We have postulated that the energy delivered by nsPEF is insufficient to impart significant heating to the treated tissue. Here we use both direct measurements and theoretical modeling of the Joule heating in order to validate this assumption. For the temperature measurement, thermo-sensitive liquid crystals (TLC) were used to determine the surface temperature while a micro-thermocouple (made from 30 μm wires) was used for measuring the temperature inside the tissue. The calculation of the temperature distribution used an asymptotic approach with the repeated calculation of the electric field, Joule heating and heat transfer, and the subsequent readjustment of the electrical tissue conductivity. This yields a temperature distribution both in space and time. It can be shown that for the measured increase in temperature an unexpectedly high electrical conductivity of the tissue would be required, which was indeed found by using voltage and current monitoring during the experiment. Using impedance measurements within t(after)=50 μs after the pulse revealed a fast decline of the high conductivity state when the electric field ceases. The experimentally measured high conductance of a skin fold (mouse) between plate electrodes was about 5 times higher than those of the maximally expected conductance due to fully electroporated membrane structures (G(max)/G(electroporated))≈5. Fully electroporated membrane structure assumes that 100% of the membranes are conductive which is estimated from an impedance measurement at 10 MHz where membranes are capacitively shorted. Since the temperature rise in B-16 mouse melanoma tumors due to equally spaced (Δt=2 s) 300 ns-pulses with E=40 kV/cm usually does not exceed ΔΤ=3 K at all parts of the skin fold between the electrodes, a hyperthermic effect on the tissue can be excluded. PMID:24680133

  8. Note: Tesla based pulse generator for electrical breakdown study of liquid dielectrics

    NASA Astrophysics Data System (ADS)

    Veda Prakash, G.; Kumar, R.; Patel, J.; Saurabh, K.; Shyam, A.

    2013-12-01

    In the process of studying charge holding capability and delay time for breakdown in liquids under nanosecond (ns) time scales, a Tesla based pulse generator has been developed. Pulse generator is a combination of Tesla transformer, pulse forming line, a fast closing switch, and test chamber. Use of Tesla transformer over conventional Marx generators makes the pulse generator very compact, cost effective, and requires less maintenance. The system has been designed and developed to deliver maximum output voltage of 300 kV and rise time of the order of tens of nanoseconds. The paper deals with the system design parameters, breakdown test procedure, and various experimental results. To validate the pulse generator performance, experimental results have been compared with PSPICE simulation software and are in good agreement with simulation results.

  9. Note: Tesla based pulse generator for electrical breakdown study of liquid dielectrics.

    PubMed

    Veda Prakash, G; Kumar, R; Patel, J; Saurabh, K; Shyam, A

    2013-12-01

    In the process of studying charge holding capability and delay time for breakdown in liquids under nanosecond (ns) time scales, a Tesla based pulse generator has been developed. Pulse generator is a combination of Tesla transformer, pulse forming line, a fast closing switch, and test chamber. Use of Tesla transformer over conventional Marx generators makes the pulse generator very compact, cost effective, and requires less maintenance. The system has been designed and developed to deliver maximum output voltage of 300 kV and rise time of the order of tens of nanoseconds. The paper deals with the system design parameters, breakdown test procedure, and various experimental results. To validate the pulse generator performance, experimental results have been compared with PSPICE simulation software and are in good agreement with simulation results. PMID:24387484

  10. Reduction in levels of Escherichia coli O157:H7 in apple cider by pulsed electric fields.

    PubMed

    Iu, J; Mittal, G S; Griffiths, M W

    2001-07-01

    Many studies have demonstrated that high voltage pulsed electric field (PEF) treatment has lethal effects on microorganisms including Escherichia coli O157:H7; however, the survival of this pathogen through the PEF treatment is not fully understood. Fresh apple cider samples inoculated with E. coli O157:H7 strain EC920026 were treated with 10, 20, and 30 instant charge reversal pulses at electric field strengths of 60, 70, and 80 kV/cm, at 20, 30, and 42 degrees C. To accurately evaluate the lethality of apple cider processing steps, counts were determined on tryptic soy agar (TSA) and sorbitol MacConkey agar (SMA) to estimate the number of injured and uninjured E. coli O157:H7 cells after PEF treatment. Cell death increased significantly with increased temperatures and electric field strengths. A maximum of 5.35-log10 CFU/ml (P < 0.05) reduction in cell population was achieved in samples treated with 30 pulses and 80 kV/cm at 42 degrees C. Cell injury measured by the difference between TSA and SMA counts was found to be insignificant (P > 0.05). Under extreme conditions, a 5.91-log10 CFU/ml reduction in cell population was accomplished when treating samples with 10 pulses and 90 kV/cm at 42 degrees C. PEF treatment, when combined with the addition of cinnamon or nisin, triggered cell death, resulting in a reduction in E. coli O157:H7 count of 6 to 8 log10 CFU/ml. Overall, the combination of PEF and heat treatment was demonstrated to be an effective pasteurization technique by sufficiently reducing the number of viable E. coli O157:H7 cells in fresh apple cider to meet U.S. Federal Drug Administration recommendations. PMID:11456204

  11. The optimal conditions for the correlation of object pulse temporary form with the stimulated photon echo response in the presence of external spatial inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Garnaeva, G. I.; Nefediev, L. A.; Hakimzyanova, E. I.; Nefedieva, K. L.

    2014-08-01

    The influence of external spatially inhomogeneous electric fields on the reproducibility of the information and effectiveness of stimulated photon echo responses locking at different encoding information in the object laser pulses are investigated.

  12. A system for mapping sources of VHF and electric field pulses from in-cloud lightning at KSC

    NASA Technical Reports Server (NTRS)

    Thomson, Ewen M.; Medelius, Pedro J.

    1991-01-01

    The literature concerning VHF radiation and wideband electric fields from in-cloud lightning is reviewed. VHF location systems give impressive radio images of lightning in clouds with high spatial and temporal resolution. Using systems based on long and short baseline time-or-arrival and interferometry, workers have detected VHF sources that move at speeds of 10(exp 5) to 10(exp 8) m/s. The more slowly moving sources appear to be associated with channel formation but the physical basis for the higher speeds is not clear. In contrast, wideband electric fields are directly related to physical parameters such as current and tortuosity. A long baseline system is described to measure simultaneously VHF radiation and wideband electric fields at five stations at Kennedy Space Center. All signals are detected over remote, isolated ground planes with fiber optics for data transmission. The modification of this system to map rapidly varying dE/dt pulses is discussed.

  13. Effects of pH and Temperature on Inactivation of Salmonella Tyhimurium DT104 in Liquid Whole Egg by Pulsed Electric Fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulsed electric fields (PEF) applies very short (microseconds) pulses of very high intensity (10 to 50 kV/cm) to foods to inactivate microorganisms by rupturing their lipid membranes. PEF process may be conducted at ambient temperature. The efficacy of PEF processing for pasteurization of liquid egg...

  14. Pulsed DC Electric Field–Induced Differentiation of Cortical Neural Precursor Cells

    PubMed Central

    Chang, Hui-Fang; Lee, Ying-Shan; Tang, Tang K.; Cheng, Ji-Yen

    2016-01-01

    We report the differentiation of neural stem and progenitor cells solely induced by direct current (DC) pulses stimulation. Neural stem and progenitor cells in the adult mammalian brain are promising candidates for the development of therapeutic neuroregeneration strategies. The differentiation of neural stem and progenitor cells depends on various in vivo environmental factors, such as nerve growth factor and endogenous EF. In this study, we demonstrated that the morphologic and phenotypic changes of mouse neural stem and progenitor cells (mNPCs) could be induced solely by exposure to square-wave DC pulses (magnitude 300 mV/mm at frequency of 100-Hz). The DC pulse stimulation was conducted for 48 h, and the morphologic changes of mNPCs were monitored continuously. The length of primary processes and the amount of branching significantly increased after stimulation by DC pulses for 48 h. After DC pulse treatment, the mNPCs differentiated into neurons, astrocytes, and oligodendrocytes simultaneously in stem cell maintenance medium. Our results suggest that simple DC pulse treatment could control the fate of NPCs. With further studies, DC pulses may be applied to manipulate NPC differentiation and may be used for the development of therapeutic strategies that employ NPCs to treat nervous system disorders. PMID:27352251

  15. Pulsed magnetic field excitation sensitivity of match-type electric blasting caps

    NASA Astrophysics Data System (ADS)

    Parson, Jonathan; Dickens, James; Walter, John; Neuber, Andreas A.

    2010-10-01

    This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED.

  16. Pulsed magnetic field excitation sensitivity of match-type electric blasting caps.

    PubMed

    Parson, Jonathan; Dickens, James; Walter, John; Neuber, Andreas A

    2010-10-01

    This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED. PMID:21034127

  17. Pulsed DC Electric Field-Induced Differentiation of Cortical Neural Precursor Cells.

    PubMed

    Chang, Hui-Fang; Lee, Ying-Shan; Tang, Tang K; Cheng, Ji-Yen

    2016-01-01

    We report the differentiation of neural stem and progenitor cells solely induced by direct current (DC) pulses stimulation. Neural stem and progenitor cells in the adult mammalian brain are promising candidates for the development of therapeutic neuroregeneration strategies. The differentiation of neural stem and progenitor cells depends on various in vivo environmental factors, such as nerve growth factor and endogenous EF. In this study, we demonstrated that the morphologic and phenotypic changes of mouse neural stem and progenitor cells (mNPCs) could be induced solely by exposure to square-wave DC pulses (magnitude 300 mV/mm at frequency of 100-Hz). The DC pulse stimulation was conducted for 48 h, and the morphologic changes of mNPCs were monitored continuously. The length of primary processes and the amount of branching significantly increased after stimulation by DC pulses for 48 h. After DC pulse treatment, the mNPCs differentiated into neurons, astrocytes, and oligodendrocytes simultaneously in stem cell maintenance medium. Our results suggest that simple DC pulse treatment could control the fate of NPCs. With further studies, DC pulses may be applied to manipulate NPC differentiation and may be used for the development of therapeutic strategies that employ NPCs to treat nervous system disorders. PMID:27352251

  18. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    SciTech Connect

    Guo, Jiquan

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  19. Sterilization of liquid foods by pulsed electric fields–an innovative ultra-high temperature process

    PubMed Central

    Reineke, Kai; Schottroff, Felix; Meneses, Nicolas; Knorr, Dietrich

    2015-01-01

    The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm−1), skim milk (0.3% fat; 5.3 mS cm−1) and fresh prepared carrot juice (7.73 mS cm−1). The combination of moderate preheating (70–90°C) and an insulated PEF-chamber, combined with a holding tube (65 cm) and a heat exchanger for cooling, enabled a rapid heat up to 105–140°C (measured above the PEF chamber) within 92.2–368.9 μs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using computational fluid dynamics (CFD). A preheating of saline water to 70°C with a flow rate of 5 l h−1, a frequency of 150 Hz and an energy input of 226.5 kJ kg−1, resulted in a measured outlet temperature of 117°C and a 4.67 log10 inactivation of B. subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for G. stearothermophilus spores in saline water. A preheating to 95°C and an energy input of 144 kJ kg−1 resulted in an outlet temperature of 126°C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10) was achieved during the thermal treatment. Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring inhomogeneous temperature

  20. Comparison of Transcutaneous Electrical Nerve Stimulation and Pulsed Radiofrequency Sympathectomy for Treating Painful Diabetic Neuropathy

    PubMed Central

    Naderi Nabi, Bahram; Sedighinejad, Abbas; Haghighi, Mohammad; Biazar, Gelareh; Hashemi, Masood; Haddadi, Soodabeh; Fathi, Amirhossein

    2015-01-01

    Background: Painful diabetic peripheral neuropathy (DPN) is a long-term complication of type 1 and type 2 diabetes that majorly impacts quality of life. Its prevalence increases with age and duration of diabetes. It is more common in patients who have suboptimal glycemic control over several years. Because DPN may be resistant to conventional treatments, it is common for patients to only have partial pain relief. Therefore, new therapeutic options are needed for the condition. Objectives: The aim of the present study was to compare the efficacy of transcutaneous electrical nerve stimulation (TENS) and pulsed radiofrequency (PRF) lumbar sympathectomy in treating painful DPN. Patients and Methods: Sixty-five patients with painful DPN refractory to conventional treatment were randomly and evenly assigned to either the TENS or PRF lumbar sympathectomy groups. Pain evaluations were based on the 10-point numerical rating scale (NRS). Subjects were followed for three months and had a total of four study visits (baseline and 1 week, 1 month, and 3 months after treatment). Results: Sixty patients completed all study visits. In both groups, the NRS rating significantly decreased after treatment, with a marked pain reduction observed at the first follow-up evaluation. In the PRF group, the NRS decreased from 6.46 at baseline to 2.76 at the 1 week visit. One and 3 months after treatment, the NRS was 4.30 and 5.13, respectively (P < 0.0001). In the TENS group, the NRS decreased from 6.10 at baseline to 3.96 at the 1 week visit. One and 3 months after treatment, the NRS was 5.23 and 5.90, respectively (P < 0.0001). Unfortunately, the NRS steady increased almost back to baseline levels in the TENS group. The NRS only slightly increased during the follow-up period in the PRF group, but did not reach baseline levels. Conclusions: Both TENS and PRF lumbar sympathectomy are promising pain relief treatments for painful DNP. However, PRF lumbar sympathectomy seems to have a superior

  1. Sterilization of liquid foods by pulsed electric fields-an innovative ultra-high temperature process.

    PubMed

    Reineke, Kai; Schottroff, Felix; Meneses, Nicolas; Knorr, Dietrich

    2015-01-01

    The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm(-1)), skim milk (0.3% fat; 5.3 mS cm(-1)) and fresh prepared carrot juice (7.73 mS cm(-1)). The combination of moderate preheating (70-90°C) and an insulated PEF-chamber, combined with a holding tube (65 cm) and a heat exchanger for cooling, enabled a rapid heat up to 105-140°C (measured above the PEF chamber) within 92.2-368.9 μs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using computational fluid dynamics (CFD). A preheating of saline water to 70°C with a flow rate of 5 l h(-1), a frequency of 150 Hz and an energy input of 226.5 kJ kg(-1), resulted in a measured outlet temperature of 117°C and a 4.67 log10 inactivation of B. subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for G. stearothermophilus spores in saline water. A preheating to 95°C and an energy input of 144 kJ kg(-1) resulted in an outlet temperature of 126°C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10) was achieved during the thermal treatment. Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring inhomogeneous temperature fields

  2. Study on electrical characteristics of barrier-free atmospheric air diffuse discharge generated by nanosecond pulses and long wire electrodes

    SciTech Connect

    Li, Lee Liu, Yun-Long; Teng, Yun; Liu, Lun; Pan, Yuan

    2014-07-15

    In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0 cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.

  3. The secretogranin-II derived peptide secretoneurin modulates electric behavior in the weakly pulse type electric fish, Brachyhypopomus gauderio.

    PubMed

    Pouso, Paula; Quintana, Laura; López, Gabriela C; Somoza, Gustavo M; Silva, Ana C; Trudeau, Vance L

    2015-10-01

    Secretoneurin (SN) in the preoptic area and pituitary of mammals and fish has a conserved close association with the vasopressin and oxytocin systems, members of a peptide family that are key in the modulation of sexual and social behaviors. Here we show the presence of SN-immunoreactive cells and projections in the brain of the electric fish, Brachyhypopomus gauderio. Secretoneurin colocalized with vasotocin (AVT) and isotocin in cells and fibers of the preoptic area. In the rostral pars distalis of the pituitary, many cells were both SN and prolactin-positive. In the hindbrain, at the level of the command nucleus of the electric behavior (pacemaker nucleus; PN), some of SN-positive fibers colocalized with AVT. We also explored the potential neuromodulatory role of SN on electric behavior, specifically on the rate of the electric organ discharge (EOD) that signals arousal, dominance and subordinate status. Each EOD is triggered by the command discharge of the PN, ultimately responsible for the basal EOD rate. SN modulated diurnal basal EOD rate in freely swimming fish in a context-dependent manner; determined by the initial value of EOD rate. In brainstem slices, SN partially mimicked the in vivo behavioral effects acting on PN firing rate. Taken together, our results suggest that SN may regulate electric behavior, and that its effect on EOD rate may be explained by direct action of SN at the PN level through either neuroendocrine and/or endocrine mechanisms. PMID:26141148

  4. Study on AC-DC Electrical Conductivities in Warm Dense Matter Generated by Pulsed-power Discharge with Isochoric Vessel

    NASA Astrophysics Data System (ADS)

    Sasaki, Toru; Ohuchi, Takumi; Takahashi, Takuya; Kawaguchi, Yoshinari; Saito, Hirotaka; Miki, Yasutoshi; Takahashi, Kazumasa; Kikuchi, Takashi; Aso, Tsukasa; Harada, Nob.

    2016-03-01

    To observe AC and DC electrical conductivity in warm dense matter (WDM), we have demonstrated to apply the spectroscopic ellipsometry for a pulsed-power discharge with isochoric vessel. At 10 μs from the beginning of discharge, the generated parameters by using pulsed-power discharge with isochoric vessel are 0.1 ρ s (ρ s: solid density) of density and 4000 K of temperature, respectively. The DC electrical conductivity for above parameters is estimated to be 104 S/m. In order to measure the AC electrical conductivity, we have developed a four-detector spectroscopic ellipsometer with a multichannel spectrometer. The multichannel spectrometer, in which consists of a 16-channel photodiode array, a two-stages voltage adder, and a flat diffraction grating, has 10 MHz of the frequency response with covered visible spectrum. For applying the four-detector spectroscopic ellipsometer, we observe the each observation signal evolves the polarized behavior compared to the ratio as I 1/I 2.

  5. Electric pulses used in electrochemotherapy and electrogene therapy do not significantly change the expression profile of genes involved in the development of cancer in malignant melanoma cells

    PubMed Central

    2009-01-01

    Background Electroporation is a versatile method for in vitro or in vivo delivery of different molecules into cells. However, no study so far has analysed the effects of electric pulses used in electrochemotherapy (ECT pulses) or electric pulses used in electrogene therapy (EGT pulses) on malignant cells. We studied the effect of ECT and EGT pulses on human malignant melanoma cells in vitro in order to understand and predict the possible effect of electric pulses on gene expression and their possible effect on cell behaviour. Methods We used microarrays with 2698 different oligonucleotides to obtain the expression profile of genes involved in apoptosis and cancer development in a malignant melanoma cell line (SK-MEL28) exposed to ECT pulses and EGT pulses. Results Cells exposed to ECT pulses showed a 68.8% average survival rate, while cells exposed to EGT pulses showed a 31.4% average survival rate. Only seven common genes were found differentially expressed in cells 16 h after exposure to ECT and EGT pulses. We found that ECT and EGT pulses induce an HSP70 stress response mechanism, repress histone protein H4, a major protein involved in chromatin assembly, and down-regulate components involved in protein synthesis. Conclusion Our results show that electroporation does not significantly change the expression profile of major tumour suppressor genes or oncogenes of the cell cycle. Moreover, electroporation also does not changes the expression of genes involved in the stability of DNA, supporting current evidence that electroporation is a safe method that does not promote tumorigenesis. However, in spite of being considered an isothermal method, it does to some extent induce stress, which resulted in the expression of the environmental stress response mechanism, HSP70. PMID:19709437

  6. A New Concept for Non-Volatile Memory: The Electric-Pulse Induced Resistive Change Effect in Colossal Magnetoresistive Thin Films

    NASA Technical Reports Server (NTRS)

    Liu, S. Q.; Wu, N. J.; Ignatiev, A.

    2001-01-01

    A novel electric pulse-induced resistive change (EPIR) effect has been found in thin film colossal magnetoresistive (CMR) materials, and has shown promise for the development of resistive, nonvolatile memory. The EPIR effect is induced by the application of low voltage (< 4 V) and short duration (< 20 ns) electrical pulses across a thin film sample of a CMR material at room temperature and under no applied magnetic field. The pulse can directly either increase or decrease the resistance of the thin film sample depending on pulse polarity. The sample resistance change has been shown to be over two orders of magnitude, and is nonvolatile after pulsing. The sample resistance can also be changed through multiple levels - as many as 50 have been shown. Such a device can provide a way for the development of a new kind of nonvolatile multiple-valued memory with high density, fast write/read speed, low power-consumption, and potential high radiation-hardness.

  7. Characterization of phase-change behavior of a Ge2Sb2Te5 thin film using finely controlled electrical pulses for switching

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Cheol; Jeong, Jin Hwan; Choi, Doo Jin

    2016-09-01

    We studied the phase-change behavior of Ge2Sb2Te5, which is a chalcogenide material widely used in phase-change memory, using precisely controlled electrical pulses to improve the efficiency of the switching operation. The electrical pulse is a critical parameter that supplies source energy to reversibly switch the phase of the material between amorphous and crystalline. The electrical pulse conditions are classified into rising time, setting time (ST) and falling time (FT). We investigated the individual influence of each step on the phase of the material with fine nanoscale pulses. We also studied the complex influence of the ratio of ST and FT to investigate the correlation among the steps. The result showed that the state of the phase-change material and electrical properties were significantly determined according to the specific condition of the pulse. Furthermore, we used transmission electron microscopy to observe the cross-sectional images of the material to confirm these phenomena. Finally, retention cycling tests were performed to elucidate the most stable conditions of the material with respect to the specific ratio of the electrical pulses. The results indicated that the FT should be more than double the ST for the SET operation and more than 10% of the ST for the RESET operation.

  8. Multiple pulse-heating experiments with different current to determine total emissivity, heat capacity, and electrical resistivity of electrically conductive materials at high temperatures.

    PubMed

    Watanabe, Hiromichi; Yamashita, Yuichiro

    2012-01-01

    A modified pulse-heating method is proposed to improve the accuracy of measurement of the hemispherical total emissivity, specific heat capacity, and electrical resistivity of electrically conductive materials at high temperatures. The proposed method is based on the analysis of a series of rapid resistive self-heating experiments on a sample heated at different temperature rates. The method is used to measure the three properties of the IG-110 grade of isotropic graphite at temperatures from 850 to 1800 K. The problem of the extrinsic heating-rate effect, which reduces the accuracy of the measurements, is successfully mitigated by compensating for the generally neglected experimental error associated with the electrical measurands (current and voltage). The results obtained by the proposed method can be validated by the linearity of measured quantities used in the property determinations. The results are in reasonably good agreement with previously published data, which demonstrate the suitability of the proposed method, in particular, to the resistivity and total emissivity measurements. An interesting result is the existence of a minimum in the emissivity of the isotropic graphite at around 1120 K, consistent with the electrical resistivity results. PMID:22299976

  9. Noise analysis in fast magnetic resonance electrical impedance tomography (MREIT) based on spoiled multi gradient echo (SPMGE) pulse sequence

    NASA Astrophysics Data System (ADS)

    In Oh, Tong; Jeong, Woo Chul; Kim, Ji Eun; Sajib, Saurav Z. K.; Kim, Hyung Joong; In Kwon, Oh; Woo, Eung Je

    2014-08-01

    Magnetic resonance electrical impedance tomography (MREIT) is a promising non-invasive method to visualize a static cross-sectional conductivity and/or current density image by injecting low frequency currents. MREIT measures one component of the magnetic flux density caused by the injected current using a magnetic resonance (MR) scanner. For practical in vivo implementations of MREIT, especially for soft biological tissues where the MR signal rapidly decays, it is crucial to develop a technique for optimizing the magnetic flux density signal by the injected current while maintaining spatial-resolution and contrast. We design an MREIT pulse sequence by applying a spoiled multi-gradient-echo pulse sequence (SPMGE) to the injected current nonlinear encoding (ICNE), which fully injects the current at the end of the read-out gradient. The applied ICNE-SPMGE pulse sequence maximizes the duration of injected current almost up to a repetition time by measuring multiple magnetic flux density data. We analyze the noise level of measured magnetic flux density with respect to the pulse width of injection current and T_{2}^{*} relaxation time. In due consideration of the ICNE-SPMGE pulse sequence, using a reference information of T_{2}^{*} values in a local region of interest by a short pre-scan data, we predict the noise level of magnetic flux density to be measured for arbitrary repetition time TR. Results from phantom experiment demonstrate that the proposed method can predict the noise level of magnetic flux density for an appropriate TR = 40 ms using a reference scan for TR = 75 ms. The predicted noise level was compared with the noise level of directly measured magnetic flux density data.

  10. Thresholds for Phosphatidylserine Externalization in Chinese Hamster Ovarian Cells following Exposure to Nanosecond Pulsed Electrical Fields (nsPEF)

    PubMed Central

    Vincelette, Rebecca L.; Roth, Caleb C.; McConnell, Maureen P.; Payne, Jason A.; Beier, Hope T.; Ibey, Bennett L.

    2013-01-01

    High-amplitude, MV/m, nanosecond pulsed electric fields (nsPEF) have been hypothesized to cause nanoporation of the plasma membrane. Phosphatidylserine (PS) externalization has been observed on the outer leaflet of the membrane shortly after nsPEF exposure, suggesting local structural changes in the membrane. In this study, we utilized fluorescently-tagged Annexin V to observe the externalization of PS on the plasma membrane of isolated Chinese Hamster Ovary (CHO) cells following exposure to nsPEF. A series of experiments were performed to determine the dosimetric trends of PS expression caused by nsPEF as a function of pulse duration, τ, delivered field strength, ED, and pulse number, n. To accurately estimate dose thresholds for cellular response, data were reduced to a set of binary responses and ED50s were estimated using Probit analysis. Probit analysis results revealed that PS externalization followed the non-linear trend of (τ*ED2)−1 for high amplitudes, but failed to predict low amplitude responses. A second set of experiments was performed to determine the nsPEF parameters necessary to cause observable calcium uptake, using cells preloaded with calcium green (CaGr), and membrane permeability, using FM1-43 dye. Calcium influx and FM1-43 uptake were found to always be observed at lower nsPEF exposure parameters compared to PS externalization. These findings suggest that multiple, higher amplitude and longer pulse exposures may generate pores of larger diameter enabling lateral diffusion of PS; whereas, smaller pores induced by fewer, lower amplitude and short pulse width exposures may only allow extracellular calcium and FM1-43 uptake. PMID:23658665

  11. Thresholds for phosphatidylserine externalization in Chinese hamster ovarian cells following exposure to nanosecond pulsed electrical fields (nsPEF).

    PubMed

    Vincelette, Rebecca L; Roth, Caleb C; McConnell, Maureen P; Payne, Jason A; Beier, Hope T; Ibey, Bennett L

    2013-01-01

    High-amplitude, MV/m, nanosecond pulsed electric fields (nsPEF) have been hypothesized to cause nanoporation of the plasma membrane. Phosphatidylserine (PS) externalization has been observed on the outer leaflet of the membrane shortly after nsPEF exposure, suggesting local structural changes in the membrane. In this study, we utilized fluorescently-tagged Annexin V to observe the externalization of PS on the plasma membrane of isolated Chinese Hamster Ovary (CHO) cells following exposure to nsPEF. A series of experiments were performed to determine the dosimetric trends of PS expression caused by nsPEF as a function of pulse duration, τ, delivered field strength, ED, and pulse number, n. To accurately estimate dose thresholds for cellular response, data were reduced to a set of binary responses and ED50s were estimated using Probit analysis. Probit analysis results revealed that PS externalization followed the non-linear trend of (τ*ED (2))(-1) for high amplitudes, but failed to predict low amplitude responses. A second set of experiments was performed to determine the nsPEF parameters necessary to cause observable calcium uptake, using cells preloaded with calcium green (CaGr), and membrane permeability, using FM1-43 dye. Calcium influx and FM1-43 uptake were found to always be observed at lower nsPEF exposure parameters compared to PS externalization. These findings suggest that multiple, higher amplitude and longer pulse exposures may generate pores of larger diameter enabling lateral diffusion of PS; whereas, smaller pores induced by fewer, lower amplitude and short pulse width exposures may only allow extracellular calcium and FM1-43 uptake. PMID:23658665

  12. Real-Time Observation on Evolution of Droplets Morphology Affected by Electric Current Pulse in Al-Bi Immiscible Alloy

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Wang, Tongmin; Cao, Fei; Fu, Hongwang; Fu, Yanan; Xie, Honglan; Xiao, Tiqiao

    2013-05-01

    The evolution of Bi-rich droplets morphology in a solidifying Al-Bi immiscible alloy was directly observed using a synchrotron microradiography technique. The electric current pulse (ECP) was applied to control the solidification process of Al-Bi immiscible alloy. It was found that the electromagnetic pinch force and Marangoni force induced by ECP and temperature gradient, respectively, can significantly affect the distribution of Bi-rich droplets. The electromagnetic pinch force drove the droplets from the center to side; meanwhile, the Marangoni force lifted the droplets from the bottom to the top. As a result, the droplets finally distributed with a manner of "inverted triangle."

  13. Mitigation of magnetohydrodynamic electromagnetic pulse (MHD-EMP) effects from commerical electric power systems. Power Systems Technology Program

    SciTech Connect

    Barnes, P.R.; Tesche, F.M.; Vance, E.F.

    1992-03-01

    A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth`s magnetic field and produces a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). This can adversely affect electrical power systems. In this report, the effects of this nuclear environment on critical facilities connected to the commercial power system are considered. Methods of mitigating the MHD-EMP impacts are investigated, and recommended protection schemes are presented. Guidelines for testing facilities to determine the effects of MHD-EMP and to validate the mitigation methods also are discussed.

  14. LASER BIOLOGY AND MEDICINE: Effect of repetitive laser pulses on the electrical conductivity of intervertebral disc tissue

    NASA Astrophysics Data System (ADS)

    Omel'chenko, A. I.; Sobol', E. N.

    2009-03-01

    The thermomechanical effect of 1.56-μm fibre laser pulses on intervertebral disc cartilage has been studied using ac conductivity measurements with coaxial electrodes integrated with an optical fibre for laser radiation delivery to the tissue. The observed time dependences of tissue conductivity can be interpreted in terms of hydraulic effects and thermomechanical changes in tissue structure. The laserinduced changes in the electrical parameters of the tissue are shown to correlate with the structural changes, which were visualised using shadowgraph imaging. Local ac conductivity measurements in the bulk of tissue can be used to develop a diagnostic/monitoring system for laser regeneration of intervertebral discs.

  15. Recovering degraded quasi-solid-state dye-sensitized solar cells by applying electrical pulses

    PubMed Central

    Zhang, Xi; Huang, Xuezhen

    2013-01-01

    We discovered a method of applying forward pulsed bias to recover the degradation of quasi-solid-state dye-sensitized solar cells (DSSCs). Up to 30.7% of the power conversion efficiency (η) of a degraded poly (vinylidene fluoride) (PVDF) based DSSC was recovered by a double-pulse. The recovered η remained higher than that before the double-pulse treatment for at least 28 days. It is deduced that the blocking of ion-transport channels in the quasi-solid-state electrolyte causes degradation of the DSSCs. This study will shed light on the efficiency enhancement and long-term stability of quasi-solid-state DSSCs. PMID:23545782

  16. Effect of pulsed electric field treatment during cold maceration and alcoholic fermentation on major red wine qualitative and quantitative parameters.

    PubMed

    El Darra, Nada; Rajha, Hiba N; Ducasse, Marie-Agnès; Turk, Mohammad F; Grimi, Nabil; Maroun, Richard G; Louka, Nicolas; Vorobiev, Eugène

    2016-12-15

    This work studies the effect of pulsed electric field (PEF) treatment at moderate and high field strengths (E=0.8kV/cm & 5kV/cm) prior and during alcoholic fermentation (AF) of red grapes on improving different parameters of pre-treated extracts: pH, °Brix, colour intensity (CI), total polyphenols content (TPI) of Cabernet Sauvignon red wine. Similar trends were observed for treating grapes using moderate and high electric field strength on the enhancement of CI and TPI of the wine after AF. The application of PEF using moderate strengths at different times during cold maceration (CM) (0, 2 and 4days) was more efficient for treatment during CM. The treatment during AF showed lower extraction rate compared to treating during CM and prior to AF. Our results clearly show that the best time for applying the PEF-treatment through the red fermentation is during the CM step. PMID:27451191

  17. Comparison of phenolic compounds of orange juice processed by pulsed electric fields (PEF) and conventional thermal pasteurisation.

    PubMed

    Agcam, E; Akyıldız, A; Akdemir Evrendilek, G

    2014-01-15

    Processing of orange juice by pulsed electric fields (PEF) and thermal pasteurisation was carried out to compare changes in total phenolic concentration, hydroxybenzoic acid, hydroxycinnamic acids, flavonols, flavones and flavonones before and after being stored at 4°C for 180days. Changes in the initial total phenolic concentration of the samples varied depending on the applied electric field intensity and thermal pasteurisation. Hesperidin and chlorogenic acids were detected as the most abounded flavonoid and phenolic acids in the orange juice, respectively. Except for syringic acid and neoeriocitrin, the concentration of the phenolic compounds indentified in the orange juice samples enhanced after the PEF or thermal pasteurisation. The samples treated with PEF had more stable flavonoids and phenolic acids than those treated with the thermal pasteurisation. The PEF-treated samples had higher sensory scores than the heat-treated samples. PMID:24054251

  18. Communication: influence of nanosecond-pulsed electric fields on water and its subsequent relaxation: dipolar effects and debunking memory.

    PubMed

    Avena, Massimiliano; Marracino, Paolo; Liberti, Micaela; Apollonio, Francesca; English, Niall J

    2015-04-14

    Water has many intriguing and anomalous physical properties that have puzzled and titillated the scientific community for centuries, perhaps none more so than the proposition that water may retain some (permanent) "memory" of conditions (e.g., dilution) or electric fields to which it has been subject. Here, we have performed non-equilibrium molecular dynamics simulations of liquid water in external electric-field nanosecond pulses, at 260-310 K, and gauged significant non-thermal field effects in terms of dipolar response. Response of both system- and individual-dipoles has been investigated, and autocorrelation functions of both show more significant effects in stronger fields, with more sluggish relaxation. Crucially, we show that once the field is removed, the dipoles relax, exhibiting no memory or permanent dipolar alignment. We also quantify the time scales for system dynamical-dipolar properties to revert to zero-field equilibrium behaviour. PMID:25877554

  19. Communication: Influence of nanosecond-pulsed electric fields on water and its subsequent relaxation: Dipolar effects and debunking memory

    NASA Astrophysics Data System (ADS)

    Avena, Massimiliano; Marracino, Paolo; Liberti, Micaela; Apollonio, Francesca; English, Niall J.

    2015-04-01

    Water has many intriguing and anomalous physical properties that have puzzled and titillated the scientific community for centuries, perhaps none more so than the proposition that water may retain some (permanent) "memory" of conditions (e.g., dilution) or electric fields to which it has been subject. Here, we have performed non-equilibrium molecular dynamics simulations of liquid water in external electric-field nanosecond pulses, at 260-310 K, and gauged significant non-thermal field effects in terms of dipolar response. Response of both system- and individual-dipoles has been investigated, and autocorrelation functions of both show more significant effects in stronger fields, with more sluggish relaxation. Crucially, we show that once the field is removed, the dipoles relax, exhibiting no memory or permanent dipolar alignment. We also quantify the time scales for system dynamical-dipolar properties to revert to zero-field equilibrium behaviour.

  20. Development of Electrothermal Pulsed Plasma Thrusters for Osaka-Institute-of-Technology Electric-Rocket-Engine onboard Small Space Ship

    SciTech Connect

    Ishii, Yushuke; Yamamoto, Tsuyoshi; Yamada, Minetsugu; Tahara, Hirokazu

    2008-12-31

    The Project of Osaka-Institute-of-Technology Electric-Rocket-Engine onboard Small Space Ship (PROITERES) was started at Osaka Institute of Technology. In PROITERES, a 10-kg small satellite with electrothermal pulsed plasma thrusters (PPTs), named JOSHO, will be launched in 2010. The main mission is powered flight of small satellite by electric thruster itself. Electrothermal PPTs were studied with both experiments and numerical simulations. An electrothermal PPT with a side-fed propellant feeding mechanism achieved a total impulse of 3.6 Ns with a repetitive 10000-shot operation. An unsteady numerical simulation showed the existence of considerable amount of ablation delaying to the discharge. However, it was also shown that this phenomenon should not be regarded as the 'late time ablation' for electrothermal PPTs.

  1. Nanosecond pulsed electric field (nsPEF) enhance cytotoxicity of cisplatin to hepatocellular cells by microdomain disruption on plasma membrane.

    PubMed

    Yin, Shengyong; Chen, Xinhua; Xie, Haiyang; Zhou, Lin; Guo, Danjing; Xu, Yuning; Wu, Liming; Zheng, Shusen

    2016-08-15

    Previous studies showed nanosecond pulsed electric field (nsPEF) can ablate solid tumors including hepatocellular carcinoma (HCC) but its effect on cell membrane is not fully understood. We hypothesized nsPEF disrupt the microdomains on outer-cellular membrane with direct mechanical force and as a result the plasma membrane permeability increases to facilitate the small molecule intake. Three HCC cells were pulsed one pulse per minute, an interval longer than nanopore resealing time. The cationized ferritin was used to mark up the electronegative microdomains, propidium iodide (PI) for membrane permeabilization, energy dispersive X-ray spectroscopy (EDS) for the negative cell surface charge and cisplatin for inner-cellular cytotoxicity. We demonstrated that the ferritin marked-microdomain and negative cell surface charge were disrupted by nsPEF caused-mechanical force. The cell uptake of propidium and cytotoxicity of DNA-targeted cisplatin increased with a dose effect. Cisplatin gains its maximum inner-cellular cytotoxicity when combining with nsPEF stimulation. We conclude that nsPEF disrupt the microdomains on the outer cellular membrane directly and increase the membrane permeabilization for PI and cisplatin. The microdomain disruption and membrane infiltration changes are caused by the mechanical force from the changes of negative cell surface charge. PMID:27375200

  2. Electrochemical reclamation of silver from silver-plating wastewater using static cylinder electrodes and a pulsed electric field.

    PubMed

    Su, Yuan-Bo; Li, Qing-Biao; Wang, Yuan-Peng; Wang, Hai-Tao; Huang, Jia-le; Yang, Xin

    2009-10-30

    Silver was reclaimed from silver-plating wastewater by using a pulsed electric field (PEF) combined with static cylinder electrodes (SCE). The conditions that produced the maximal silver recovery rate (RR(Ag)) (99%) were as follows: average retention time of 10 min, interelectrode gap of 50mm, solution pH of 9.0, temperature of 45 degrees C, initial Ag(I) concentration of 1000 mg L(-1), PEF pulse frequency of 1200 Hz, current density of 5.0 A m(-2) and a pulse duty cycle of 60%. Compared with the conventional direct current (DC) technology, the PEF process exhibited improvements in the silver recovery rate (RR(Ag)), total energy consumption (TEC) and physical properties of the silver deposits, especially for low Ag(I) concentrations, for example, from 500 to 1000 mg L(-1). For an initial Ag(I) concentration of 500 mg L(-1), the PEF process produced an RR(Ag) of up to 99%, and the TEC was 4.56 kWh (kg Ag)(-1). In comparison, the RR(Ag) and TEC were 90% and 5.66 kWh (kg Ag)(-1), respectively, in the DC process. The results of SEM observation and XRD analysis indicated that the silver deposits formed by the PEF process were smaller, denser, and of a higher purity than those produced by the DC process. Therefore, the presented method was effective for reclaiming silver from silver-plating wastewater. PMID:19545945

  3. Effect of adjusting pulse durations of functional electrical stimulation cycling on energy expenditure and fatigue after spinal cord injury.

    PubMed

    Gorgey, Ashraf S; Poarch, Hunter J; Dolbow, David D; Castillo, Teodoro; Gater, David R

    2014-01-01

    The purpose of the current study was to determine the effects of three different pulse durations (200, 350, and 500 microseconds [P200, P350, and P500, respectively]) on oxygen uptake (VO2), cycling performance, and energy expenditure (EE) percentage of fatigue of the knee extensor muscle group immediately and 48 to 72 h after cycling in persons with spinal cord injury (SCI). A convenience sample of 10 individuals with motor complete SCI participated in a repeated-measures design using a functional electrical stimulation (FES) cycle ergometer over a 3 wk period. There was no difference among the three FES protocols on relative VO2 or cycling EE. Delta EE between exercise and rest was 42% greater in both P500 and P350 compared with P200 (p = 0.07), whereas recovery VO2 was 23% greater in P350 compared with P200 (p = 0.03). There was no difference in the outcomes of the three pulse durations on muscle fatigue. Knee extensor torque significantly decreased immediately after (p < 0.001) and 48 to 72 h after (p < 0.001) FES leg cycling. Lengthening pulse duration did not affect submaximal or relative VO2 or EE, total EE, and time to fatigue. Greater recovery VO2 and delta EE were noted in P350 and P500 compared with P200. An acute bout of FES leg cycling resulted in torque reduction that did not fully recover 48 to 72 h after cycling. PMID:25803753

  4. Optimized pulsed laser deposition by wavelength and static electric field control: The case of tetrahedral amorphous carbon films

    NASA Astrophysics Data System (ADS)

    Patsalas, P.; Kaziannis, S.; Kosmidis, C.; Papadimitriou, D.; Abadias, G.; Evangelakis, G. A.

    2007-06-01

    We report on the application of a static (dc) electric field in the plume region during the pulsed Nd doped yttrium aluminum garnet laser deposition (PLD) of tetrahedral amorphous carbon (ta-C) films in vacuum ambient (pressure=10-4-10-3Pa), where the working pressure is exclusively due to ablation vapor. This approach is strikingly different from the plasma- or ion-beam-assisted PLD because the mean free path at this pressure is by far longer than the target to substrate distance. Thus, the electric field interacts with individual ionized species invoking ion acceleration and gas-phase reactions among different ionized species. These phenomena are clearly dependent on the laser wavelength (first, second, or third harmonic, λ =1064, 532, and 355nm, respectively) used for the ablation. We found that the application of the electric field causes surface smoothing (the roughness decreases from about 1to0.4nm) and faster deposition rate (from about 2to7nm/min) for the second and third harmonics. In addition, the phenomena are less intense in the case of the first harmonic due to the low concentration of ionized species in the plume. In addition, in the case of PLD using λ =532nm, the electric field improves the film's density (from 2.60to2.95g/cm3). The correlations found are discussed in terms of the ablated species and the deposition mechanisms of the ta-C.

  5. Spectroscopic and electrical characters of SBD plasma excited by bipolar nanosecond pulse in atmospheric air.

    PubMed

    Zhao, Zi-Lu; Yang, De-Zheng; Wang, Wen-Chun; Yuan, Hao; Zhang, Li; Wang, Sen; Liu, Zhi-Jie; Zhang, Shuai

    2016-05-15

    In this paper, an atmospheric surface barrier discharge (SBD) generated by annular electrodes in quartz tube is presented through employing bipolar nanosecond pulse voltage in air. The discharge images, waveforms of pulse voltage and discharge current, and optical emission spectra emitted from the discharges are recorded and calculated. A spectra simulation method is developed to separate the overlap of the secondary diffraction spectra which are produced by grating in monochromator, and N2 (B(3)Πg→A(3)Σu(+)) and O (3p(5)P→3s(5)S2(o)) are extracted. The effects of pulse voltage and discharge power on the emission intensities of OH (A(2)Σ(+)→X(2)Пi), N2(+) (B(2)Σu(+)→X(2)Σg(+)), N2 (C(3)Πu→B(3)Πg), N2 (B(3)Πg→A(3)Σu(+)), and O (3p(5)P→3s(5)S2(o)) are investigated. It is found that increasing the pulse peak voltage can lead to an easier formation of N2(+) (B(2)Σu(+)) than that of N2 (C(3)Πu). Additionally, vibrational and rotational temperatures of the plasma are determined by comparing the experimental and simulated spectra of N2(+) (B(2)Σu(+)→X(2)Σg(+)), and the results show that the vibrational and rotational temperatures are 3250±20K and 350±5K under the pulse peak voltage of 28kV, respectively. PMID:26924210

  6. Spectroscopic and electrical characters of SBD plasma excited by bipolar nanosecond pulse in atmospheric air

    NASA Astrophysics Data System (ADS)

    Zhao, Zi-Lu; Yang, De-Zheng; Wang, Wen-Chun; Yuan, Hao; Zhang, Li; Wang, Sen; Liu, Zhi-Jie; Zhang, Shuai

    2016-05-01

    In this paper, an atmospheric surface barrier discharge (SBD) generated by annular electrodes in quartz tube is presented through employing bipolar nanosecond pulse voltage in air. The discharge images, waveforms of pulse voltage and discharge current, and optical emission spectra emitted from the discharges are recorded and calculated. A spectra simulation method is developed to separate the overlap of the secondary diffraction spectra which are produced by grating in monochromator, and N2 (B3Πg → A3Σu+) and O (3p5P → 3s5S2o) are extracted. The effects of pulse voltage and discharge power on the emission intensities of OH (A2Σ+ → X2Пi), N2+ (B2Σu+ → X2Σg+), N2 (C3Πu → B3Πg), N2 (B3Πg → A3Σu+), and O (3p5P → 3s5S2o) are investigated. It is found that increasing the pulse peak voltage can lead to an easier formation of N2+ (B2Σu+) than that of N2 (C3Πu). Additionally, vibrational and rotational temperatures of the plasma are determined by comparing the experimental and simulated spectra of N2+ (B2Σu+ → X2Σg+), and the results show that the vibrational and rotational temperatures are 3250 ± 20 K and 350 ± 5 K under the pulse peak voltage of 28 kV, respectively.

  7. Effect of duty cycle on the electrical and optical properties of VOx film deposited by pulsed reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dong, Xiang; Wu, Zhiming; Xu, Xiangdong; Wei, Xiongbang; Jiang, Yadong

    2013-12-01

    Vanadium oxide (VOx) films were deposited onto well cleaned glass substrates by bipolar pulsed reactive magnetron sputtering at room temperature. Dependence of the structure, composition, optical and electrical properties of the films on the pulsed power's duty cycle has been investigated. The results from the X-ray diffraction (XRD) analysis show that there was no remarkable change in the amorphous structure in the films with duty cycle can be observed. But chemical analysis of the surface evaluated with x-ray photoelectron spectroscopy (XPS) indicates that decrease the duty cycle favors to enhance the oxidation of the vanadium. The optical and electrical properties of the films were characterized by spectroscopic ellipsometry and temperature dependent resistivity measurements, respectively. The evolution of the transmittance, optical band gap, optical constants, resistivity and temperature coefficient of resistance (TCR) of the deposited films with duty cycle was analyzed and discussed. In comparison with conventional DC sputtering, under the same discharge atmosphere and power level, these parameters of the VOx films can be modified over a broad range by duty cycle. Therefore adjusting the duty cycle during deposition, which is an effective way to control and optimize the performances of the VOx film for various optoelectronic devices applications.

  8. Electrical stimulation vs. pulsed and continuous-wave optical stimulation of the rat prostate cavernous nerves, in vivo

    NASA Astrophysics Data System (ADS)

    Perkins, William C.; Lagoda, Gwen A.; Burnett, Arthur; Fried, Nathaniel M.

    2015-07-01

    Identification and preservation of the cavernous nerves (CNs) during prostate cancer surgery is critical for post-operative sexual function. Electrical nerve stimulation (ENS) mapping has previously been tested as an intraoperative tool for CN identification, but was found to be unreliable. ENS is limited by the need for electrode-tissue contact, poor spatial precision from electrical current spreading, and stimulation artifacts interfering with detection. Alternatively, optical nerve stimulation (ONS) provides noncontact stimulation, improved spatial selectivity, and elimination of stimulation artifacts. This study compares ENS to pulsed/CW ONS to explore the ONS mechanism. A total of eighty stimulations were performed in 5 rats, in vivo. ENS (4 V, 5 ms, 10 Hz) was compared to ONS using a pulsed diode laser nerve stimulator (1873 nm, 5 ms, 10 Hz) or CW diode laser nerve stimulator (1455 nm). Intracavernous pressure (ICP) response and nerve compound action potentials (nCAPs) were measured. All three stimulation modes (ENS, ONS-CW, ONS-P) produced comparable ICP magnitudes. However, ENS demonstrated more rapid ICP response times and well defined nCAPs compared to unmeasurable nCAPs for ONS. Further experiments measuring single action potentials during ENS and ONS are warranted to further understand differences in the ENS and ONS mechanisms.

  9. Effects of pre-fermentation and pulsed-electric-field treatment of primary sludge in microbial electrochemical cells.

    PubMed

    Ki, Dongwon; Parameswaran, Prathap; Popat, Sudeep C; Rittmann, Bruce E; Torres, César I

    2015-11-01

    The aim of this study was to investigate the combination of two technologies - pulsed electric field (PEF) pre-treatment and semi-continuous pre-fermentation of primary sludge (PS) - to produce volatile fatty acids (VFAs) as the electron donor for microbial electrolysis cells (MECs). Pre-fermentation with a 3-day solids retention time (SRT) led to the maximum generation of VFAs, with or without pretreatment of the PS through pulsed-electric-fields (PEF). PEF treatment before fermentation enhanced the accumulation of the preferred VFA, acetate, by 2.6-fold. Correspondingly, MEC anodes fed with centrate from 3-day pre-fermentation of PEF-treated PS had a maximum current density ∼3.1 A/m(2), which was 2.4-fold greater than the control pre-fermented centrate. Over the full duration of batch MEC experiments, using pre-fermented centrate led to successful performance in terms of Coulombic efficiency (95%), Coulombic recovery (80%), and COD-removal efficiency (85%). PMID:26159378

  10. Effect of pulsed electric field (PEF) on structures and antioxidant activity of soybean source peptides-SHCMN.

    PubMed

    Lin, Songyi; Liang, Rong; Li, Xingfang; Xing, Jie; Yuan, Yuan

    2016-12-15

    Recently, high-intensity pulsed electric field (PEF) has successfully used in improvement of antioxidant activity. Ser-His-Cys-Met-Asn (SHCMN) obtained from soybean protein was chosen to investigate the phenomenon of antioxidant activity improvement. Effects of PEF treatment on antioxidant activity of SHCMN were evaluated by DPPH radical inhibition. Nuclear magnetic resonance (NMR), mid-infrared (MIR), circular dichroism (CD) were used to analyze structures of SHCMN. Two-factor-at-a-time results show that DPPH radical inhibition of SHCMN is significantly (P<0.05) increased to 94.35±0.03% at conditions of electric field intensity of 5kV/cm, pulse frequency of 2400Hz, and retention time of 2h. In addition, MIR and NMR spectra show that the basic structure of peptides SHCMN is stable by PEF treatment. But the secondary structures (α-helix, β-turn, and random coil) can be affected and zeta potential of PEF-treated SHCNM was reduced to 0.59±0.03mV. The antioxidant activity improvement of SHCMN might result from the changes of secondary structures and zeta potential. PMID:27451222

  11. Electrical pulse - mediated enhanced delivery of silver nanoparticles into living suspension cells for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lin, J.; Yu, Y.; Li, B.; Huang, H.; Lin, S.; Li, C.; Su, Y.; Feng, S.; Chen, G.; Li, Y.; Huang, Z.; Zeng, H.; Chen, R.

    2012-03-01

    Electrical pulse-mediated enhanced silver nanoparticles delivery is a much better method for intracellular surface-enhanced Raman spectroscopy (SERS) measurements of suspension cells. Robust and high-quality SERS spectra of living suspension cells were obtained based on an electroporation-SERS method, which can overcomes the shortcoming of non-uniform distribution of silver nanoparticles localized in the cell cytoplasm after electroporation and reduces the amount variance of silver nanoparticles delivered into different cells. The electroporation parameters include three 150 V (375 V/cm) electric pulses of 1, 5, and 5 ms durations respectively. Our results indicate that considerable amount of silver nanoparticles can be rapidly delivered into the human promyelocytic leukemia HL60 cells, and the satisfied SERS spectra were obtained while the viability of the treated cells was highly maintained (91.7%). The electroporation-SERS method offers great potential approach in delivering silver nanoparticles into living suspension cells, which is useful for widely biomedical applications including the real-time intracellular SERS analysis of living cells.

  12. Effect of pulsed electric field on the proteolysis of cold boned beef M. Longissimus lumborum and M. Semimembranosus.

    PubMed

    Suwandy, Via; Carne, Alan; van de Ven, Remy; Bekhit, Alaa El-Din A; Hopkins, David L

    2015-02-01

    The effects of pulsed electric field (PEF) and ageing (3, 7, 14 and 21 days) on the shear force, protein profile, and post-mortem proteolysis of beef loins (M. Longissimus lumborum, LL) and topsides (M. Semimembranosus, SM) were investigated using a range of pulsed electric field treatments [voltages (5 and 10 kV) and frequencies (20, 50, and 90 Hz)]. PEF treatment decreased the shear force of beef LL and SM muscles by up to 19%. The reduction in the shear force in the LL was not affected by the treatment intensity whereas the reduction in the SM was dependent on PEF frequency. PEF treated beef loins showed increased proteolysis, both early post-mortem and during subsequent post-mortem storage reflected by increased degradation of troponin-T and desmin. The most prominent troponin-T degradation was found in samples treated with 5 kV-90 Hz, 10 kV-20 Hz at day 3 and day 7 post-treatment in addition to 10 kV-50 Hz in subsequent post-treatment times. The degradation of desmin in PEF treated beef loins increased with ageing time. PMID:25460129

  13. Inactivation of Escherichia coli, Saccharomyces cerevisiae, and Lactobacillus brevis in Low-fat Milk by Pulsed Electric Field Treatment: A Pilot-scale Study

    PubMed Central

    Han, Bok Kung; Choi, Hyuk Joon; Kang, Shin Ho; Baick, Seung Chun

    2015-01-01

    We investigated the effects of a pulsed electric field (PEF) treatment on microbial inactivation and the physical properties of low-fat milk. Milk inoculated with Escherichia coli, Saccharomyces cerevisiae, or Lactobacillus brevis was supplied to a pilot-scale PEF treatment system at a flow rate of 30 L/h. Pulses with an electric field strength of 10 kV/cm and a pulse width of 30 μs were applied to the milk with total pulse energies of 50-250 kJ/L achieved by varying the pulse frequency. The inactivation curves of the test microorganisms were biphasic with an initial lag phase (or shoulder) followed by a phase of rapid inactivation. PEF treatments with a total pulse energy of 200 kJ/L resulted in a 4.5-log reduction in E. coli, a 4.4-log reduction in L. brevis, and a 6.0-log reduction in S. cerevisiae. Total pulse energies of 200 and 250 kJ/L resulted in greater than 5-log reductions in microbial counts in stored PEF-treated milk, and the growth of surviving microorganisms was slow during storage for 15 d at 4℃. PEF treatment did not change milk physical properties such as pH, color, or particle-size distribution (p<0.05). These results indicate that a relatively low electric-field strength of 10 kV/cm can be used to pasteurize low-fat milk. PMID:26877640

  14. Relationship between Sublethal Injury and Inactivation of Yeast Cells by the Combination of Sorbic Acid and Pulsed Electric Fields▿

    PubMed Central

    Somolinos, M.; García, D.; Condón, S.; Mañas, P.; Pagán, R.

    2007-01-01

    The objective of this study was to investigate the occurrence of sublethal injury after the pulsed-electric-field (PEF) treatment of two yeasts, Dekkera bruxellensis and Saccharomyces cerevisiae, as well as the relation of sublethal injury to the inactivating effect of the combination of PEF and sorbic acid. PEF caused sublethal injury in both yeasts: more than 90% of surviving D. bruxellensis cells and 99% of surviving S. cerevisiae cells were sublethally injured after 50 pulses at 12 kV/cm in buffer at pHs of both 7.0 and 4.0. The proportion of sublethally injured cells reached a maximum after 50 pulses at 12.0 kV/cm (S. cerevisiae) or 16.5 kV/cm (D. bruxellensis), and it kept constant or progressively decreased at greater electric field strengths and with longer PEF treatments. Sublethally PEF-injured cells showed sensitivity to the presence of sorbic acid at a concentration of 2,000 ppm. A synergistic inactivating effect of the combination of PEF and sorbic acid was observed. Survivors of the PEF treatment were progressively inactivated in the presence of 2,000 ppm of sorbic acid at pH 3.8, with the combined treatments achieving more than log10 5 cycles of dead cells under the conditions investigated. This study has demonstrated the occurrence of sublethal injury after exposure to PEF, so yeast inactivation by PEF is not an all-or-nothing event. The combination of PEF and sorbic acid has proven to be an effective method to achieve a higher level of yeast inactivation. This work contributes to the knowledge of the mechanism of microbial inactivation by PEF, and it may be useful for improving food preservation by PEF technology. PMID:17468278

  15. Long Term Effects of Multiple DBD Pulses on Thin Liquid Layers Over Tissue: Reactive Fluences and Electric Fields

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Kushner, Mark J.

    2014-10-01

    Atmospheric dielectric barrier discharges (DBDs) are used in treatment of tissue, often covered by thin liquid layers. The reactivity reaching the tissue depends on the plasma dose, composition and acidification of the liquid, and the cumulative delivery of electric fields through the liquid. In this paper, we report on a computational investigation of the interaction of DBDs with a thin liquid layer covering tissue over many minutes. We used nonPDPSIM, a 2-d model in which Poisson's equation, the electron temperature equation, transport equations for charged and neutral species and radiation transport are solved in both the gas and liquid. The liquid layer, 100's μm thick, is water with dissolved gases [O2aq (aq is aqueous), CO2aq], metal ions (Feaq2+ , Feaq3+) , and organics (RHaq) . Hundreds of pulses at 100 Hz are computed, followed by minutes of afterglow. In the liquid, transient radicals (OHaq, Haq) are produced during the discharge pulse and are consumed during the interpulse period. Terminal species (H2O2aq, O3aq) accumulate and diffuse to the tissue. Ions are dominated by NO3-aq, O2-aq and H3Oaq+.Production of HNO3aq and HOONOaq is assisted by O2aq for the first pulses and then O3aq. Accumulating nitric acid lowers the pH. RHaq consumes most reactive oxygen species in the early plasma treatment leaving Raq. With longer exposure, RHaq can be consumed, enabling more ROS to reach the tissue. The cumulative exposure of electric fields to the tissue depends on the increasing conductivity of the liquid. Work supported by DOE Office of Fusion Energy Science and NSF.

  16. Optical and electrical characterization of pulse-modulated argon atmospheric-pressure inductively coupled microplasma jets

    SciTech Connect

    Tajima, Satomi; Tsuchiya, Shouichi; Matsumori, Masashi; Nakatsuka, Shigeki; Ichiki, Takanori

    2010-10-15

    The critical parameters determining the generation of the pulse-modulated argon atmospheric-pressure inductively coupled plasma (AP-ICP) microjet were studied by varying the power, P, pulse-modulation frequency, f, and duty ratio, DR. The temporal changes in the net output power, P{sub net}, monitored between the very high frequency power supply and matching network by an rf sampler, and ArI 4s{sup '}[1/2]{sub 1}{sup O}-4p{sup '}[1/2]{sub 0} emission from the antenna were measured to elucidate the behavior of this plasma. The AP-ICP microjet, which produces high-density (0.9-1.1x10{sup 15} cm{sup -3}) nonequilibrium plasma, consists of an alumina discharge tube with the inner diameter of 0.8 mm. The generation diagram of the pulse-modulated plasma was created by having f as the horizontal axis and DR as the vertical axis while varying P up to 50 W. At f{<=}10 kHz, the plasma was generated at above the linear lines of f and DR, which indicated the existence of the critical power-off period of approximately 80 {mu}s. At f>10 kHz, the pulse-modulated plasma was produced above constant DR and almost independent of f. The time-averaged power, P, which is the product of P and DR, had to be more than 8-10 W to sustain the pulse-modulated plasma. From the measurement of the temporal changes in the net power and ArI emission, the dynamic behavior of the pulse-modulated plasma was revealed as follows. The prebreakdown period was present for {approx}5 {mu}s after the power was turned on. Once the plasma was generated, the impedance was changed and the reflected power gradually decreased. A strong emission peak was observed immediately after the breakdown, followed by the gradual increase up to the steady state. Finally, the intense afterpeak was observed at 0.8 {mu}s after the power was turned off.

  17. Dipole Model of Electric Pulse Generation Caused by the Relaxation Processes in the Earth's Crust

    NASA Astrophysics Data System (ADS)

    Losseva, T. V.; Spivak, A.; Kuzmicheva, M. Y.

    2011-12-01

    Study of electric and magnetic (EM) signals in the Earth's crust is of interest from a viewpoint of both establishing mechanisms and conditions for generation of geophysical fields and interpreting physical and mechanical characteristics of a hierarchically structured medium. In a previously developed model [1] it was proposed that generation of electromagnetic impulses in the Earth's crust with low water content was a result of a quasi independent displacement of a structural block being relaxed in constrained conditions. A transient electric current system generated on an active side of the structural block due to electric polarization of an inter-block gap content was considered as a source of EM radiation. In a new numerical model we use a set of Hertz's dipoles distributed over the active surface. Time dependence of the dipole moments was defined by displacement of the structural unit. To estimate EM signals the full system of Maxwell equations in a conductive medium was solved. The results of numerical simulations were compared with electric field records in a surface layer of the Earth's crust in the area of influence of the tectonically active Kurai structure (Gornyi Altai) [2]. The amplitudes of electric fields at a distance of 50-100 linear block sizes obtained in numerical simulations are in good agreement with the instrumental observations, which proves the validity of our model for the estimation of electric effects in the low moisture rock medium.

  18. Longitudinally polarized single-cycle terahertz pulses generated with high electric field strengths

    NASA Astrophysics Data System (ADS)

    Cliffe, M. J.; Graham, D. M.; Jamison, S. P.

    2016-05-01

    We demonstrate the generation of single-cycle longitudinally polarized terahertz pulses with field amplitudes in excess of 11 kV/cm using the interferometric recombination of two linearly polarized terahertz beams. High field strength transversely polarized pulses were generated by optical rectification in a matched pair of magnesium-oxide doped stoichiometric lithium niobate (MgO:SLN) crystals with a reversal in the χ333 ( 2 ) orientation. The discontinuity in χ333 ( 2 ) produces a polarity flip in the transverse field; the longitudinal field produced as a consequence of the transverse field discontinuity was measured in the far-field. Both the spatial and temporal profiles of the measured longitudinally polarized terahertz radiation were consistent with the propagation of the transverse discontinuity.

  19. High-fidelity pulse density modulation in neuromorphic electric circuits utilizing natural heterogeneity

    NASA Astrophysics Data System (ADS)

    Utagawa, Akira; Asai, Tetsuya; Amemiya, Yoshihito

    Hospedales et al. have recently proposed a neural network model of the “vestibulo-ocular reflex” (VOR) in which a common input was given to multiple nonidentical spiking neurons that were exposed to uncorrelated temporal noise, and the output was represented by the sum of these neurons. Although the function of the VOR network is equivalent to pulse density modulation, the neurons' non-uniformity and temporal noises given to the neurons were shown to improve the output spike's fidelity to the analog input. In this paper, we propose a CMOS analog circuit for implementing the VOR network that exploits the non-uniformity of real MOS devices. Through extensive laboratory experiments using discrete MOS devices, we show that the output's fidelity to the input pulses is clearly improved by using multiple neuron circuits, in which the non-uniformity is naturally embedded into the devices.

  20. The Chlorella killed by pulsed electrical discharge in liquid with two different reactors

    NASA Astrophysics Data System (ADS)

    Gao, Z. Y.; Sun, B.; Yan, Z. Y.; Zhu, X. M.; Liu, H.; Song, Y. J.; Sato, M.

    2013-03-01

    The application of pulsed high-voltage discharge in liquid has attracted wide attention as an effective water treatment. In this paper, two different liquid high-voltage discharge systems were constructed with plate-hole-plate and needle-plate electrode structures, and the inactivation behaviors of Chlorella were studied in the two reactors. The results show that the killing rates of algae in both reactors all increased significantly with increasing discharge voltage and the killing rates were intensely related to discharge power, instantaneous power and single pulse input energy. Furthermore, the inactivation effect in needle-plate reactor was superior to that in plate-hole-plate reactor under the same experimental conditions.

  1. Electrical and optical characterization of a pulsed discharge in an inverted cylindrical magnetron

    NASA Astrophysics Data System (ADS)

    Vozniy, O. V.; Duday, D.; Luciu, I.; Wirtz, T.

    2014-08-01

    An inverted cylindrical magnetron operating in pulsed mode was developed, with a rotating unbalanced system of magnets. The magnetic field was calculated using the finite integration technique in order to determine the optimal anode-to-cathode distance inside the reactor. A cylindrical titanium target was used for our experiments. The average power input was varied between 500 and 1300 W leading to low power densities varying between 0.9 and 2.4 W cm-2. The frequency was fixed at a low value of 250 Hz, suitable for depositing Ti and TiO2 at low temperatures on polymer substrates. Long on-time pulses (400 µs) were used in order to reach interesting deposition rates (>1 µm h-1). A transition from metallic to oxide mode was observed for all power inputs. Time-resolved optical emission spectroscopy was used for the investigation of plasma dynamics during the on-time pulse in both metallic and reactive regimes. Three phases of discharge evolution were identified in the metallic mode: the Ar-dominated phase, followed by a transition zone and a Ti-dominated phase. The emission of Ti species completely disappeared in the reactive mode, associated with the fact that titanium atoms left the target surface as TiOx molecular fragments. In conclusion, the deposition system and conditions used resulted in a new mode of TiO2 deposition.

  2. Comparison of electrical transients and corrosion responses of pulsed MP35N and 316LVM electrodes.

    PubMed

    Riedy, L W; Walter, J S

    1994-01-01

    Functional neuromuscular stimulation (FNS) is often limited by electrode malfunctions such as corrosion and breakage, particularly for intramuscular and epimysial type electrodes. As a result, the electrochemical charge injection characteristics and corrosion responses of single strand 316LVM stainless steel and MP35N nickel-cobalt alloy electrodes were evaluated in vitro. For charge balance, capacitor coupled monophasic protocols with varying charge injections were employed. Electrodes were evaluated with either positive-first or negative-first pulses, 60 Hz, 100 microsec pulse duration, and stimulation periods from 100 to 240 hours. Charge injection densities ranged from 20 to 80 microC/cm2. For both anodic-first and cathodic-first pulsing, the potential transients for the MP35N electrodes were more extreme than for the 316LVM electrodes over the test period, and increased corrosion was apparent on the MP35N electrodes from both optical and scanning electron microscopy. Therefore, 316LVM, but not MP35N, may be suitable for FNS applications with charge injection densities less than 40 microC/cm2. PMID:8074331

  3. Propagation of the Lightning Electromagnetic Pulse Through the E- and F-region Ionosphere and the Generation of Parallel Electric Fields

    NASA Astrophysics Data System (ADS)

    Rowland, D. E.; Wygant, J. R.; Pfaff, R. F.; Farrell, W. M.; Goetz, K. A.; Monson, S. J.

    2004-05-01

    Sounding rockets launched by Mike Kelley and his group at Cornell demonstrated the existence of transient (1 ms) electric fields associated with lightning strikes at high altitudes above active thunderstorms. These electric fields had a component parallel to the Earth's magnetic field, and were unipolar and large in amplitude. They were thought to be strong enough to energize electrons and generate strong turbulence as the beams thermalized. The parallel electric fields were observed on multiple flights, but high time resolution measurements were not made within 100 km horizontal distance of lightning strokes, where the electric fields are largest. In 2000 the ``Lightning Bolt'' sounding rocket (NASA 27.143) was launched directly over an active thunderstorm to an apogee near 300 km. The sounding rocket was equipped with sensitive electric and magnetic field instruments as well as a photometer and electrostatic analyser for measuring accelerated electrons. The electric and magnetic fields were sampled at 10 million samples per second, letting us fully resolve the structure of the parallel electric field pulse up to and beyond the plasma frequency. We will present results from the Lightning Bolt mission, concentrating on the parallel electric field pulses that arrive before the lower-frequency whistler wave modes. We observe pulses with peak electric fields of a few mV/m lasting for a substantial fraction of a millisecond. Superimposed on this is high-frequency turbulence, comparable in amplitude to the pulse itself. This is the first direct observation of this structure in the parallel electric field, within 100 km horizontal distance of the lightning stroke. We will present evidence for the method of generation of these parallel fields, and discuss their probable effect on ionospheric electrons.

  4. Micro-structural, electrical and spectroscopic investigations of pulsed laser ablated palladium incorporated nanostructured tungsten oxide films.

    PubMed

    Lethy, K J; Beena, D; Pillai, V P Mahadevan; Suresh, K A

    2009-09-01

    Pure and Pd incorporated (0.5, 1 and 5 wt%) WO3 films are prepared on quartz substrates using pulsed laser ablation (PLD) technique in an oxygen ambient of 0.12 mbar, at a substrate temperature (Ts) of 873 K. Palladium incorporation effects on the microstructure, optical and electrical properties of tungsten oxide films are systematically investigated using techniques like X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), micro-Raman spectroscopy, UV-Vis absorption spectroscopy and temperature dependent electrical resistivity measurements. The micro-structural analysis by XRD and micro-Raman indicates that Pd addition can perturb the tungsten oxide lattice and suppress the grain growth. Optical band gap values of the films increases from 3.17 eV for pure WO3 to 3.29 eV for 5 wt% Pd incorporated WO3 films. All the films present high transparency in the visible spectral range. The electrical resistivity studies of the pure and Pd incorporated films done at room temperature and for the range of temperature; 170-450 K reveal that Pd addition can lower the resistivity of the WO3 thin films. Room temperature resistivity as well as activation energy of the film decreases exponentially with Pd incorporation concentration. Highly transparent, nanocrystalline and semiconducting WO3 films with low resistivity obtained by Pd incorporation can make WO3 suitable for microelectronics industry and for gas sensing applications. PMID:19928224

  5. Improved long-term electrical stability of pulsed high-power diodes using dense carbon fiber velvet cathodes

    SciTech Connect

    Yang Jie; Shu Ting; Wang Hui

    2012-07-15

    The influence of fibrous velvet cathodes on the electrical stability of a planar high-power diode powered by a {approx}230 kV, {approx}110 ns pulse has been investigated. The current density was on the order of {approx}123 A/cm{sup 2}. A combination of time-resolved electrical and optical diagnostics has been employed to study the basic phenomenology of the temporal and spatial evolution of the diode plasmas. Additionally, an impedance model was used to extract information about this plasma from voltage and current profiles. The results from the two diagnostics were compared. By comparison with commercial polymer velvet cathode, the dense carbon fiber velvet cathode showed superior long-term electrical stability as judged by the change in cathode turn-on field, ignition delays, diode impedance, and surface plasma characteristics during the voltage flattop, a promising result for applications where reliable operation at high power is required. Finally, it was shown that the interaction of the electron beam with the stainless steel anode did not lead to the formation of anode plasma. These results may be of interest to the high power microwave systems with cold cathodes.

  6. Nanosecond pulsed platelet-rich plasma (nsPRP) improves mechanical and electrical cardiac function following myocardial reperfusion injury.

    PubMed

    Hargrave, Barbara; Varghese, Frency; Barabutis, Nektarios; Catravas, John; Zemlin, Christian

    2016-02-01

    Ischemia and reperfusion (I/R) of the heart is associated with biochemical and ionic changes that result in cardiac contractile and electrical dysfunction. In rabbits, platelet-rich plasma activated using nanosecond pulsed electric fields (nsPRP) has been shown to improve left ventricular pumping. Here, we demonstrate that nsPRP causes a similar improvement in mouse left ventricular function. We also show that nsPRP injection recovers electrical activity even before reperfusion begins. To uncover the mechanism of nsPRP action, we studied whether the enhanced left ventricular function in nsPRP rabbit and mouse hearts was associated with increased expression of heat-shock proteins and altered mitochondrial function under conditions of oxidative stress. Mouse hearts underwent 30 min of global ischemia and 1 h of reperfusion in situ. Rabbit hearts underwent 30 min of ischemia in vivo and were reperfused for 14 days. Hearts treated with nsPRP expressed significantly higher levels of Hsp27 and Hsp70 compared to hearts treated with vehicle. Also, pretreatment of cultured H9c2 cells with nsPRP significantly enhanced the "spare respiratory capacity (SRC)" also referred to as "respiratory reserve capacity" and ATP production in response to the uncoupler FCCP. These results suggest a cardioprotective effect of nsPRP on the ischemic heart during reperfusion. PMID:26908713

  7. Almost sudden perturbation of a quantum system with ultrashort electric pulses

    SciTech Connect

    Lugovskoy, Andrey; Bray, Igor

    2008-02-15

    We present an alternative approach to analyze atomic behavior when an external field perturbation is not sudden for a number of states of the field-free system. It is shown that the probability amplitudes for the system to be in these states can be accurately estimated from the closed set of their integral equations. Numerical examples for an electron in a one-dimensional Coulomb potential interacting with (i) laser and (ii) half-cycle pulses are provided. Comparison with exact calculations indicates the strength of the approach.

  8. Potential of M-Wave Elicited by Double Pulse for Muscle Fatigue Evaluation in Intermittent Muscle Activation by Functional Electrical Stimulation for Motor Rehabilitation

    PubMed Central

    Miura, Naoto; Watanabe, Takashi

    2016-01-01

    Clinical studies on application of functional electrical stimulation (FES) to motor rehabilitation have been increasing. However, muscle fatigue appears early in the course of repetitive movement production training by FES. Although M-wave variables were suggested to be reliable indices of muscle fatigue in long lasting constant electrical stimulation under the isometric condition, the ability of M-wave needs more studies under intermittent stimulation condition, because the intervals between electrical stimulations help recovery of muscle activation level. In this paper, M-waves elicited by double pulses were examined in muscle fatigue evaluation during repetitive movements considering rehabilitation training with surface electrical stimulation. M-waves were measured under the two conditions of repetitive stimulation: knee extension force production under the isometric condition and the dynamic movement condition by knee joint angle control. Amplitude of M-wave elicited by the 2nd pulse of a double pulse decreased during muscle fatigue in both measurement conditions, while the change in M-waves elicited by single pulses in a stimulation burst was not relevant to muscle fatigue in repeated activation with stimulation interval of 1 s. Fatigue index obtained from M-waves elicited by 2nd pulses was suggested to provide good estimation of muscle fatigue during repetitive movements with FES. PMID:27110556

  9. Improved neural representation of vowels in electric stimulation using desynchronizing pulse trains

    NASA Astrophysics Data System (ADS)

    Litvak, Leonid; Delgutte, Bertrand; Eddington, Donald

    2003-10-01

    Current cochlear implant processors poorly represent sound waveforms in the temporal discharge patterns of auditory-nerve fibers (ANFs). A previous study [Litvak et al., J. Acoust. Soc. Am. 114, 2079-2098 (2003)] showed that the temporal representation of sinusoidal stimuli can be improved in a majority of ANFs by encoding the stimuli as small modulations of a sustained, high-rate (5 kpps), desynchronizing pulse train (DPT). Here, these findings are extended to more complex stimuli by recording ANF responses to pulse trains modulated by bandpass filtered vowels. Responses to vowel modulators depended strongly on the discharge pattern evoked by the unmodulated DPT. ANFs that gave sustained responses to the DPT had period histograms that resembled the modulator waveform for low (<5%) modulation depths. Spectra of period histograms contained peaks near the formant frequencies. In contrast, ANFs that gave a transient (<1 min) response to the DPT poorly represented the formant frequencies. A model incorporating a linear modulation filter, a noisy threshold, and neural refractoriness predicts the shapes of period histograms for both types of fibers. These results suggest that a DPT-enhanced strategy may achieve good representation of the stimulus fine structure in the temporal discharge patterns of ANFs for frequencies up to 1000 Hz. It remains to be seen whether these temporal discharge patterns can be utilized by cochlear implant subjects.

  10. High power amplification of a tailored-pulse fiber laser

    NASA Astrophysics Data System (ADS)

    Saby, Julien; Sangla, Damien; Caplette, Stéphane; Boula-Picard, Reynald; Drolet, Mathieu; Reid, Benoit; Salin, François

    2013-02-01

    We demonstrate the amplification of a 1064nm pulse-programmable fiber laser with Large Pitch Rod-Type Fibers of various Mode field diameters from 50 to 70 μm. We have developed a high power fiber amplifier at 1064nm delivering up to 100W/1mJ at 15ns pulses and 30W/300μJ at 2ns with linearly polarized and diffraction limited output beam (M²<1.2). The specific seeder from ESI - Pyrophotonics Lasers used in the experiment allowed us to obtain tailored-pulse programmable on demand at the output from 2ns to 600ns for various repetition rates from 10 to 500 kHz. We could demonstrate square pulses or any other shapes (also multi-pulses) whatever the repetition rate or the pulse duration. We also performed frequency conversion with LBO crystals leading to 50W at 532nm and 25W at 355nm with a diffraction limited output. Similar experiments performed at 1032nm are also reported.

  11. Sterilization of oil-field re-injection water using combination treatment of pulsed electric field and ultrasound.

    PubMed

    Xin, Qing; Zhang, Xingwang; Li, Zhongjian; Lei, Lecheng

    2009-01-01

    It was necessary to sterilize the oil-field re-injection water for biocorrosion inhibition. Saprophytic bacteria, iron bacteria and sulfate reducing bacteria were the three main microorganisms resulting in the microbial contamination. To enhance the sterilization efficiency of oil-field re-injection water by pulsed electric field (PEF), the combined treatment of PEF and ultrasound was explored in the study. Meanwhile, the effects of PEF, ultrasound and the combination treatment on the three bacteria inactivation were investigated. The combination treatment had higher inactivation efficiency than independent PEF as well as ultrasound. Obvious synergistic effects were also observed on the inactivation of saprophytic bacteria and iron bacteria by the combined treatment. PMID:18567526

  12. An investigation into the cumulative breakdown process of polymethylmethacrylate in quasi-uniform electric field under nanosecond pulses

    SciTech Connect

    Zhao, Liang; Cang Su, Jian; Bo Zhang, Xi; Feng Pan, Ya; Min Wang, Li; Peng Fang, Jin; Sun, Xu; Lui, Rui

    2013-08-15

    A group of complete images on the discharge channel developed in PMMA in quasi-uniform electric field under nanosecond pulses are observed with an on-line transmission microscope. The characteristics of the cumulative breakdown process are also generalized, which include initiating from the vicinity of the cathode, developing to the anode with a branch-like shape, and taking on a wormhole appearance when final breakdown occurs. The concluded characteristics are explained by referring to the conceptions of “low density domain” and “free radical” and considering the initial discharge channel as a virtual needle. The characteristics are helpful for designers to enhance the lifetime of insulators employed on a nanosecond time scale.

  13. Electrical property measurements of Cr-N codoped TiO2 epitaxial thin films grown by pulsed laser deposition

    SciTech Connect

    Jacimovic, J; Gaal, R; Magrez, Arnaud; Forro, Laszlo; Regmi, Murari; Eres, Gyula

    2013-01-01

    The temperature dependent resistivity and thermo-electric power of Cr-N codoped TiO2 were compared with that of single element N and Cr doped and undoped TiO2 using epitaxial anatase thin films grown by pulsed laser deposition on (100) LaAlO3 substrates. The resistivity plots and especially the thermoelectric power data confirm that codoping is not a simple sum of single element doping. However, the negative sign of the Seebeck coefficient indicates electron dominated transport independent of doping. The narrowing distinction among the effects of different doping methods combined with increasing resistivity of the films with improving crystalline quality of TiO2 suggest that structural defects play a critical role in the doping process.

  14. Enhanced electrical and noise properties of nanocomposite vanadium oxide thin films by reactive pulsed-dc magnetron sputtering

    SciTech Connect

    Basantani, H. A.; Kozlowski, S.; Lee, Myung-Yoon; Li, J.; Dickey, E. C.; Jackson, T. N.; Bharadwaja, S. S. N.; Horn, M.

    2012-06-25

    Thin films of VO{sub x} (1.3 {<=} x {<=} 2) were deposited by reactive pulsed-dc magnetron sputtering of a vanadium metal target while RF-biasing the substrate. Rutherford back scattering, glancing angle x-ray, and cross-sectional transmission electron microscopy measurements revealed the formation of nanocolumns with nanotwins within VO{sub x} samples. The resistivity of nanotwinned VO{sub x} films ranged from 4 m{Omega}{center_dot}cm to 0.6 {Omega}{center_dot}cm and corresponding temperature coefficient of resistance between -0.1% and -2.6% per K, respectively. The 1/f electrical noise was analyzed in these VO{sub x} samples using the Hooge-Vandamme relation. These VO{sub x} films are comparable or surpass commercial VO{sub x} films deposited by ion beam sputtering.

  15. Annealing effects on the structural and electrical properties of pulsed laser deposited BaPbO3 thin films

    NASA Astrophysics Data System (ADS)

    Satish, B.; Jayaraj, M. K.

    2014-01-01

    Conductive pervoskite BaPbO3 (BPO) films as potential electrodes for ferroelectric / tuneable applications were prepared by pulsed laser deposition technique at 600°C and at 0.1 mbar oxygen partial pressure on fused silica substrates. The structural and electrical properties of the films showed a dependence on annealing temperatures and the high oxygen ambient. XRD and standard four probe method with Hall setup were employed to investigate the dependence of growth conditions on crystal structure, resistivity and the carrier concentration on annealing the BPO thin films. The surface topography was analysed by AFM. The unannealed as deposited films showed the least resistivity of 1.6 × 10-2 ohm cm and a bandgap of 4.1eV.

  16. Enhanced electrical and noise properties of nanocomposite vanadium oxide thin films by reactive pulsed-dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Basantani, H. A.; Kozlowski, S.; Lee, Myung-Yoon; Li, J.; Dickey, E. C.; Jackson, T. N.; Bharadwaja, S. S. N.; Horn, M.

    2012-06-01

    Thin films of VOx (1.3 ≤ x ≤ 2) were deposited by reactive pulsed-dc magnetron sputtering of a vanadium metal target while RF-biasing the substrate. Rutherford back scattering, glancing angle x-ray, and cross-sectional transmission electron microscopy measurements revealed the formation of nanocolumns with nanotwins within VOx samples. The resistivity of nanotwinned VOx films ranged from 4 mΩ.cm to 0.6 Ω.cm and corresponding temperature coefficient of resistance between -0.1% and -2.6% per K, respectively. The 1/f electrical noise was analyzed in these VOx samples using the Hooge-Vandamme relation. These VOx films are comparable or surpass commercial VOx films deposited by ion beam sputtering.

  17. Selective extraction of intracellular components from the microalga Chlorella vulgaris by combined pulsed electric field-temperature treatment.

    PubMed

    Postma, P R; Pataro, G; Capitoli, M; Barbosa, M J; Wijffels, R H; Eppink, M H M; Olivieri, G; Ferrari, G

    2016-03-01

    The synergistic effect of temperature (25-65 °C) and total specific energy input (0.55-1.11 kWh kgDW(-1)) by pulsed electric field (PEF) on the release of intracellular components from the microalgae Chlorella vulgaris was studied. The combination of PEF with temperatures from 25 to 55 °C resulted in a conductivity increase of 75% as a result of cell membrane permeabilization. In this range of temperatures, 25-39% carbohydrates and 3-5% proteins release occurred and only for carbohydrate release a synergistic effect was observed at 55 °C. Above 55 °C spontaneous cell lysis occurred without PEF. Combined PEF-temperature treatment does not sufficiently disintegrate the algal cells to release both carbohydrates and proteins at yields comparable to the benchmark bead milling (40-45% protein, 48-58% carbohydrates). PMID:26722806

  18. Thermal properties of milk fat, xanthine oxidase, caseins and whey proteins in pulsed electric field-treated bovine whole milk.

    PubMed

    Sharma, Pankaj; Oey, Indrawati; Everett, David W

    2016-09-15

    Thermodynamics of milk components (milk fat, xanthine oxidase, caseins and whey proteins) in pulsed electric field (PEF)-treated milk were compared with thermally treated milk (63 °C for 30 min and 73 °C for 15s). PEF treatments were applied at 20 or 26 kV cm(-1) for 34 μs with or without pre-heating of milk (55 °C for 24s), using bipolar square wave pulses in a continuous mode of operation. PEF treatments did not affect the final temperatures of fat melting (Tmelting) or xanthine oxidase denaturation (Tdenaturation), whereas thermal treatments increased both the Tmelting of milk fat and the Tdenaturation for xanthine oxidase by 2-3 °C. Xanthine oxidase denaturation was ∼13% less after PEF treatments compared with the thermal treatments. The enthalpy change (ΔH of denaturation) of whey proteins decreased in the treated-milk, and denaturation increased with the treatment intensity. New endothermic peaks in the calorimetric thermograms of treated milk revealed the formation of complexes due to interactions between MFGM (milk fat globule membrane) proteins and skim milk proteins. Evidence for the adsorption of complexes onto the MFGM surface was obtained from the increase in surface hydrophobicity of proteins, revealing the presence of unfolded hydrophobic regions. PMID:27080877

  19. Reducing Current Spread by Use of a Novel Pulse Shape for Electrical Stimulation of the Auditory Nerve.

    PubMed

    Ballestero, Jimena; Recugnat, Matthieu; Laudanski, Jonathan; Smith, Katie E; Jagger, Daniel J; Gnansia, Daniel; McAlpine, David

    2015-01-01

    Improving the electrode-neuron interface to reduce current spread between individual electrodes has been identified as one of the main objectives in the search for future improvements in cochlear-implant performance. Here, we address this problem by presenting a novel stimulation strategy that takes account of the biophysical properties of the auditory neurons (spiral ganglion neurons, SGNs) stimulated in electrical hearing. This new strategy employs a ramped pulse shape, where the maximum amplitude is achieved through a linear slope in the injected current. We present the theoretical framework that supports this new strategy and that suggests it will improve the modulation of SGNs' activity by exploiting their sensitivity to the rising slope of current pulses. The theoretical consequence of this sensitivity to the slope is a reduction in the spread of excitation within the cochlea and, consequently, an increase in the neural dynamic range. To explore the impact of the novel stimulation method on neural activity, we performed in vitro recordings of SGNs in culture. We show that the stimulus efficacy required to evoke action potentials in SGNs falls as the stimulus slope decreases. This work lays the foundation for a novel, and more biomimetic, stimulation strategy with considerable potential for implementation in cochlear-implant technology. PMID:26721928

  20. Exploring the use of natural antimicrobial agents and pulsed electric fields to control spoilage bacteria during a beer production process.

    PubMed

    Galvagno, M A; Gil, G R; Iannone, L J; Cerrutti, P

    2007-01-01

    Different natural antimicrobials affected viability of bacterial contaminants isolated at critical steps during a beer production process. In the presence of 1 mg/ml chitosan and 0.3 mg/ml hops, the viability of Escherichia coli in an all malt barley extract wort could be reduced to 0.7 and 0.1% respectively after 2 hour- incubation at 4 degrees C. The addition of 0.0002 mg/ml nisin, 0.1 mg/ml chitosan or 0.3 mg/ml hops, selectively inhibited growth of Pediococcus sp. in more than 10,000 times with respect to brewing yeast in a mixed culture. In the presence of 0.1 mg ml chitosan in beer, no viable cells of the thermoresistant strain Bacillus megaterium were detected. Nisin, chitosan and hops increased microbiological stability during storage of a local commercial beer inoculated with Lactobacillus plantarum or Pediococcus sp. isolated from wort. Pulsed Electric Field (PEF) (8 kV/cm, 3 pulses) application enhanced antibacterial activity of nisin and hops but not that of chitosan. The results herein obtained suggest that the use of these antimicrobial compounds in isolation or in combination with PEF would be effective to control bacterial contamination during beer production and storage. PMID:17987854

  1. Reducing Current Spread by Use of a Novel Pulse Shape for Electrical Stimulation of the Auditory Nerve

    PubMed Central

    Ballestero, Jimena; Recugnat, Matthieu; Laudanski, Jonathan; Smith, Katie E.; Jagger, Daniel J.; Gnansia, Daniel

    2015-01-01

    Improving the electrode-neuron interface to reduce current spread between individual electrodes has been identified as one of the main objectives in the search for future improvements in cochlear-implant performance. Here, we address this problem by presenting a novel stimulation strategy that takes account of the biophysical properties of the auditory neurons (spiral ganglion neurons, SGNs) stimulated in electrical hearing. This new strategy employs a ramped pulse shape, where the maximum amplitude is achieved through a linear slope in the injected current. We present the theoretical framework that supports this new strategy and that suggests it will improve the modulation of SGNs’ activity by exploiting their sensitivity to the rising slope of current pulses. The theoretical consequence of this sensitivity to the slope is a reduction in the spread of excitation within the cochlea and, consequently, an increase in the neural dynamic range. To explore the impact of the novel stimulation method on neural activity, we performed in vitro recordings of SGNs in culture. We show that the stimulus efficacy required to evoke action potentials in SGNs falls as the stimulus slope decreases. This work lays the foundation for a novel, and more biomimetic, stimulation strategy with considerable potential for implementation in cochlear-implant technology. PMID:26721928

  2. Pre-breakdown cavitation nanopores in the dielectric fluid in the inhomogeneous, pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Pekker, Mikhail; Shneider, Mikhail N.

    2015-10-01

    This paper discusses the nanopores emerging and developing in a liquid dielectric under the action of the ponderomotive electrostrictive forces in a nonuniform electric field. It is shown that the gradient of the electric field in the vicinity of the rupture (cavitation nanopore) substantially increases and determines whether the rupture grows or collapses. The cavitation rupture in the liquid (nanopore) tends to stretch along the lines of the original field. The mechanism of the breakdown associated with the generation of secondary ruptures in the vicinity of the poles of the nanopore is proposed. The estimations of the extension time for nanopore in water and oil (polar and nonpolar liquids, respectively) are presented. A new mechanism of nano- and subnanosecond breakdown in the insulating (transformer) oil that can be realized in the vicinity of water microdroplets in nanosecond high-voltage devices is considered.

  3. Visualization of Electrical Trees by 80 MHz-band Pulsed Ultrasound

    NASA Astrophysics Data System (ADS)

    Kida, Satoshi; Murakami, Yoshinobu; Nagao, Masayuki; Hozumi, Naohiro

    Power modules are often molded with a resin, such as epoxy, for their protection and downsizing. The resin, which contains inorganic filler, is usually non-transparent. As optical inspection is not realistic, non-destructive inspections using X-ray or ultrasound is being performed. As for cracks and so-called “electrical tree” in the insulation, ultrasound may bring a good contrast, because there is a big difference in acoustic impedance between resin and air. There are some reports on ultrasonic observation for electrical trees, however, as thick specimens were employed, the spatial resolution was very poor due to the limitation of available frequency range. However, the diameter of electrical tree path is as thin as 5 μm. Enough resolution can't be obtained by the measurement with a low frequency range. Based on the above background, we tried to observe a “close but small” tree by ultrasonic imaging. Using the wide-band ultrasonic microscope, it was examined if a tree with 0.5 mm in scale could be observed with its fine structure. An ultrasonic image, in which branching in the tree can be discriminated. The spatial resolution was determined as 40∼50 μm. An image processing was carried out in order to acquire a clearer image. Assuming the Gaussian as a blur function, the original image was deconvolved.

  4. Mechanical and electrical properties of epitaxial Si nanowires grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Obi, D.; Nechache, R.; Harnagea, C.; Rosei, F.

    2012-11-01

    We report on the elastic and piezoresistive properties of individual epitaxial Si-NWs grown on n-doped Si(111) by pulsed laser deposition. Using scanning probe microscopy, we obtained a Young’s modulus between 82 and 900 GPa for the nanowires, unaffected by the nanowire shape. A relative resistivity change is observed in the prestrained (curved) Si-NWs, which we attribute to a large piezoresistance coefficient in the NW along its axis. Assuming that for the bent NWs the effect of longitudinal stress on resistivity is compensated, the piezoresistance coefficient originating in the shear strain alone, we found a piezoresistance gauge factor (GF) of 600, which is close to the values reported in literature for Si-NWs.

  5. Structural, optical, and electrical properties of pulsed laser deposition CIGSS thin films

    NASA Astrophysics Data System (ADS)

    Xu, Yan-Bin; Kang, Y. Zhen-Feng; Fan, Yue; Xiao, Ling-ling; Bo, Qing-Rui; Ding, Tie-Zhu

    2015-12-01

    High-quality CuIn0.75Ga0.25(Se0.75S0.25)2 (CIGSS) thin films were synthesized on the soda-lime glass (SLG) substrates by pulsed laser deposition. The structural and optical properties of CIGSS thin films were studied by experiments and theoretical calculations. XRD result reveals that the films are of chalcopyrite structure. The experiments and theory show that CIGSS is a semiconductor with a direct band gap. The direct band gap energy of the deposited CIGSS thin films are in the solar energy range. The band structure and density of states of the CIGSS crystals were studied by the first principles density functional theory. The experimental data and theoretical data have demonstrated good agreement.

  6. Mechanical and electrical properties of epitaxial Si nanowires grown by pulsed laser deposition.

    PubMed

    Obi, D; Nechache, R; Harnagea, C; Rosei, F

    2012-11-01

    We report on the elastic and piezoresistive properties of individual epitaxial Si-NWs grown on n-doped Si(111) by pulsed laser deposition. Using scanning probe microscopy, we obtained a Young's modulus between 82 and 900 GPa for the nanowires, unaffected by the nanowire shape. A relative resistivity change is observed in the prestrained (curved) Si-NWs, which we attribute to a large piezoresistance coefficient in the NW along its axis. Assuming that for the bent NWs the effect of longitudinal stress on resistivity is compensated, the piezoresistance coefficient originating in the shear strain alone, we found a piezoresistance gauge factor (GF) of 600, which is close to the values reported in literature for Si-NWs. PMID:23033061

  7. Electrical characterization and modeling of pulse-based forming techniques in RRAM arrays

    NASA Astrophysics Data System (ADS)

    Grossi, Alessandro; Zambelli, Cristian; Olivo, Piero; Miranda, Enrique; Stikanov, Valeriy; Walczyk, Christian; Wenger, Christian

    2016-01-01

    The forming process, which corresponds to the activation of the switching filament in Resistive Random Access Memory (RRAM) arrays, has a strong impact on the cells' performances. In this paper we characterize and compare different pulse forming techniques in terms of forming time, yield and cell-to-cell variability on 4 kbits RRAM arrays. Moreover, post-forming modeling during Reset operation of correctly working and over formed cells has been performed. An incremental form and verify technique, based on a sequence of trapezoidal waveforms with increasing voltages followed by a verify operation that terminates when the expected switching behavior has been achieved, showed the best results. This procedure narrows the post-forming current distribution whereas reducing the Reset switching voltage and the operative current. These advantages materialize in a better control of the cell-to-cell variability and in an overall time and energy saving at the system level.

  8. Local Structure and Electrical Performance of Pulsed Laser Deposited CdTe/CdS Thin-Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Nabizadeh, Arya; Lesinski, Darren; Cerqueira, Luis; Sahiner, Mehmet; Sahiner-Amscl Team

    2015-03-01

    The photovoltaic thin films of CdS/CdTe were prepared by pulsed laser deposition (PLD) on indium tin oxide (ITO) coated glass. The local structural variations in the thin films around Cd atom upon variations in the thin film growth parameters were investigated by X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS) and x-ray diffraction. X-ray absorption spectroscopy measurements were performed at the National Synchrotron Light Source of Brookhaven National Laboratory. The effect of the thicknesses of the CdS and CdTe layers, laser energy and the substrate temperature on the local crystal structure and coordination around the Cd atoms were investigated through quantitative multiple scattering analysis and modeling of the x-ray absorption spectroscopy data. The induced local structural modifications upon varying synthesis conditions are correlated with the electrical performance of these photovoltaic thin-films. The quantitative multiple scattering analyses and modeling of X-ray absorption spectroscopy data revealed the local environment around the Cd atoms are highly sensitive to thin film deposition parameters and the variations of the Cd local structure influences interface quality consequently, affect the electrical performance of these photovoltaic thin films. This work is supported by NSF Award #:DMI-0420952 and Research Corporation Award #:CC6405 and New Jersey Space Grant Consortium.

  9. Structural and electrical properties of different vanadium oxide phases in thin film form synthesized using pulsed laser deposition

    SciTech Connect

    Majid, S. S. Rahman, F.; Shukla, D. K.; Choudhary, R. J.; Phase, D. M.

    2015-06-24

    We present here the structural and electrical properties of the thin films of V{sub 2}O{sub 3} (Vanadium sesquioxide) and V{sub 5}O{sub 9}. Both these oxide phases, V{sub 2}O{sub 3} and V{sub 5}O{sub 9}, have beenachieved on (001) orientedSi substrate using the V{sub 2}O{sub 5} target by optimizing the deposition parameters using pulsed laser deposition technique (PLD).Deposited films were characterized by X-ray diffraction(XRD)and four probe temperature dependent resistivity measurements. XRD studies reveal the V{sub 2}O{sub 3} and V{sub 5}O{sub 9} phases and the amount of strain present in both these films. The temperature dependency of electrical resistivity confirmed the characteristic metal-insulator transitions (MIT) for both the films, V{sub 2}O{sub 3} and V{sub 5}O{sub 9}.

  10. Temperature-mediated variations in cellular membrane fatty acid composition of Staphylococcus aureus in resistance to pulsed electric fields.

    PubMed

    Wang, Lang-Hong; Wang, Man-Sheng; Zeng, Xin-An; Liu, Zhi-Wei

    2016-08-01

    Effects of growth temperature on cell membrane fatty acid composition, fluidity and lethal and sublethal injury by pulsed electric fields (PEF) in Staphylococcus aureus ATCC 43300 (S. aureus) in the stationary phase were investigated. Analysis of the membrane fatty acids by gas chromatography-mass spectrometry (GC-MS) revealed that branched chain fatty acids (iso C14:0, iso C15:0, anteiso C15:0 and anteiso C17:0) and straight chain fatty acids (C12:0, C14:0, C16:0, C17:0 and C18:0) were primary constituents in the membrane. The S. aureus changed its membrane fatty acid composition and its overall fluidity when exposed to different temperatures. The PEF lethal and sublethal effects were assessed, and results suggested that the degree of inactivation depended on the cell membrane structure, electric field strength and treatment time. The PEF inactivation kinetics including lethal and sublethal injury fractions were fitted with non-linear Weibull distribution, suggesting that inactivation of the first log cycle of S. aureus population was significantly affected by growth temperature, and the membrane of cells became more fluid, and easier to induce electroportion in low temperatures. Moreover, the morphology of S. aureus cells were investigated by electron microscopy, showing that various temperature-modified cells were distorted to differing extents and some even collapsed due to deep irreversible electroporation after PEF treatment. PMID:27155566

  11. Micro electrical discharge milling of WC-Co using a deionized water spray and a bipolar pulse

    NASA Astrophysics Data System (ADS)

    Song, Ki Young; Chung, Do Kwan; Park, Min Soo; Chu, Chong Nam

    2010-04-01

    Micro electrical discharge milling (ED-milling) is an effective machining process for manufacturing micro structures on hard metals. This method of machining generally uses kerosene or deionized water as the working fluid, both of which are associated with some problems. Kerosene results in considerable electrode wear and deionized water causes electrolytic corrosion in workpieces. In particular, when cemented tungsten carbide (WC-Co), which has superior strength, hardness and wear resistance, is machined by electrical discharge machining (EDM), the problem of electrolytic corrosion arises as a matter of course since the material is very susceptible to electrolyzation. In this study, spray ED-milling with a bipolar pulsed power source and deionized water was conducted to solve the above problems. This method uses a water spray, which is a mixture of compressed air and deionized water. The spray is injected into the machining gap between the electrode and the workpiece. WC-Co was used for the workpiece and micro grooves were machined on the workpiece. As a result, using the spray ED-milling method, high-quality micro grooves were manufactured on the WC-Co workpiece with no electrolytic corrosion and almost-zero electrode wear.

  12. Synergistic effect of nanosecond pulsed electric field combined with low-dose of pingyangmycin on salivary adenoid cystic carcinoma.

    PubMed

    Qi, Wei; Guo, Jinsong; Wu, Shan; Su, Bo; Zhang, Lei; Pan, Jie; Zhang, Jue

    2014-05-01

    Adenoid cystic carcinoma (ACC) is one of the most common malignant neoplasms in salivary glands. To evaluate the therapeutic effects of nanosecond pulsed electric field (nsPEF) combined with pingyangmycin (PYM) on salivary gland adenoid cystic carcinoma (SACC), ACC high metastatic cell line (SACC-LM) and low metastatic cell line (SACC‑83) were tested by CCK-8 assay, cell clonogenic assay, flow cytometry and Transwell assay. Extracellular matrix metalloproteinase inducer (EMMPRIN) expression was tested by western blotting to verify the synergistic mechanism of nsPEF and PYM. The results showed that nsPEF inhibited the cell proliferation of both cell lines, and the inhibitory effect was strongly associated with time and electrical field strength. Moreover, PYM combined with nsPEF may enhance the suppression effect significantly, even at a very low dose (0.01 µg/ml). The synergistic effects may contribute to the downregulation of EMMPRIN expression resulting from the application of nsPEF. For SACC, nsPEF combined with chemotherapy agents may be a valuable strategy not only to improve the treatment effect and prognosis, but also to reduce the side-effects of chemotherapy. PMID:24604118

  13. Behavior of pulsed electric field injured Escherichia coli O157:H7 cells in apple juice amended with pyruvate and catalase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulse Electric Field (PEF) treatment has been used to inactivate bacteria in liquid foods. However, information on the behavior of PEF injured Escherichia coli bacteria in media during storage at 5 and 23C are limited. In this study, we investigated the fate of E. coli O157:H7 cells at 6.8 log CFU/m...

  14. Evaluation of microbial stability, bioactive compounds, physicochemical properties, and consumer acceptance of pomegranate juice processed in a commercial scale pulsed electric field system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper investigated the feasibility for pasteurizing raw pomegranate juice in a commercial scale pulsed electric field (PEF) system. The juice was processed in a commercial scale PEF processing system at 35 and 38 kV/cm for 281 µs at 55 degree C with a flow rate of 100 L/h. Effect of PEF process...

  15. Inactivation of E. coli O157:H7 and nonpathogenic E. coli in strawberry juice by pulsed electric field, sodium benzoate, potassium sorbate, and citric acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Current regulations require that juice processors effect a 5 log CFU/ml reduction of a target pathogen prior to distributing products. Whereas thermal pasteurization reduces the sensory characteristics of juice by altering flavor components, pulsed electric field (PEF) treatment may ...

  16. Selection of surrogate bacteria in place of E. coli O157:H7 and Salmonella Typhimurium for pulsed electric field treatment of orange juice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulsed electric field (PEF) technology has been used as an innovative treatment for the reduction of microorganisms in liquid foods and beverages by the electroporation of bacterial membranes. PEF may be used to pasteurize orange juice at lower temperatures than traditional thermal processes, prese...

  17. Pulsed electric linear dichroism of triphenylmethane dyes adsorbed on montmorillonite K10 in aqueous media

    SciTech Connect

    Yamaoka, Kiwamu; Sasai, Ryo

    2000-05-01

    Electric linear dichroism (ELD) spectra of two cationic triphenylmethane dyes, crystal violet (CV) and malachite green (MG), bound to sodium montmorillonite K10 (MK-10) were studied at 20 C in aqueous media at two mixing ratios, D/S, of 0.10 and 0.24 in the 700- to 400 nm wavelength region and in the applied electric field strength range between 0 and 3 kV/cm. The specific parallel and perpendicular dichroism ({Delta}A{sub {parallel}}/A and {Delta}A{sub {perpendicular}}/A) spectra of dye-adsorbed MK-10 suspension were measured at a fixed field strength with an apparatus equipped with a 512-channel photodiode array detector. By changing the field strength over a wide range, a series of the reduced dichroism values of the bound dyes were measured at a fixed wavelength. By fitting these dichroism values to theoretical orientation functions, the intrinsic reduced dichroism ({Delta}A/A){sub int} spectra at the limiting high fields (ELD spectrum) were determined for CV and MG bound to MK-10. No appreciable difference was observed at the two D/S values. The ELD spectra of these bound dyes are undulatory but never constant, throughout their absorption region; thus, the dye plane does not lie flatly either on the surface or between layers of MK-10 particle.

  18. Nitric Oxide Studies in Low Temperature Plasmas Generated with a Nanosecond Pulse Sphere Gap Electrical Discharge

    NASA Astrophysics Data System (ADS)

    Burnette, David Dean

    This dissertation presents studies of NO kinetics in a plasma afterglow using various nanosecond pulse discharges across a sphere gap. The discharge platform is developed to produce a diffuse plasma volume large enough to allow for laser diagnostics in a plasma that is rich in vibrationally-excited molecules. This plasma is characterized by current and voltage traces as well as ICCD and NO PLIF images that are used to monitor the plasma dimensions and uniformity. Temperature and vibrational loading measurements are performed via coherent anti-Stokes Raman spectroscopy (CARS). Absolute NO concentrations are obtained by laser-induce fluorescence (LIF) measurements, and N and O densities are found using two photon absorption laser-induced fluorescence (TALIF). For all dry air conditions studied, the NO behavior is characterized by a rapid rate of formation consistent with an enhanced Zeldovich process involving electronically-excited nitrogen species that are generated within the plasma. After several microseconds, the NO evolution is entirely controlled by the reverse Zeldovich process. These results show that under the chosen range of conditions and even in extreme instances of vibrational loading, there is no formation channel beyond ~2 musec. Both the NO formation and consumption mechanisms are strongly affected by the addition of fuel species, producing much greater NO concentrations in the afterglow.

  19. Pulse Wave Velocity and Cardiac Output vs. Heart Rate in Patients with an Implanted Pacemaker Based on Electric Impedance Method Measurement

    NASA Astrophysics Data System (ADS)

    Soukup, Ladislav; Vondra, Vlastimil; Viščor, Ivo; Jurák, Pavel; Halámek, Josef

    2013-04-01

    The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

  20. A Comparative Study on the Effects of Millisecond- and Microsecond-Pulsed Electric Field Treatments on the Permeabilization and Extraction of Pigments from Chlorella vulgaris.

    PubMed

    Luengo, Elisa; Martínez, Juan Manuel; Coustets, Mathilde; Álvarez, Ignacio; Teissié, Justin; Rols, Marie-Pierre; Raso, Javier

    2015-10-01

    The interdependencies of the two main processing parameters affecting "electroporation" (electric field strength and pulse duration) while using pulse duration in the range of milliseconds and microseconds on the permeabilization, inactivation, and extraction of pigments from Chlorella vulgaris was compared. While irreversible "electroporation" was observed above 4 kV/cm in the millisecond range, electric field strengths of ≥10 kV/cm were required in the microseconds range. However, to cause the electroporation of most of the 90 % of the population of C. vulgaris in the millisecond (5 kV/cm, 20 pulses) or microsecond (15 kV/cm, 25 pulses) range, the specific energy that was delivered was lower for microsecond treatments (16.87 kJ/L) than in millisecond treatments (150 kJ/L). In terms of the specific energy required to cause microalgae inactivation, treatments in the microsecond range also resulted in greater energy efficiency. The comparison of extraction yields in the range of milliseconds (5 kV, 20 ms) and microseconds (20, 25 pulses) under the conditions in which the maximum extraction was observed revealed that the improvement in the carotenoid extraction was similar and chlorophyll a and b extraction was slightly higher for treatments in the microsecond range. The specific energy that was required for the treatment in the millisecond range (150 kJ/L) was much higher than those required in the microsecond range (30 kJ/L). The comparison of the efficacy of both types of pulses on the extraction enhancement just after the treatment and after a post-pulse incubation period seemed to indicate that PEF in the millisecond range created irreversible alterations while, in the microsecond range, the defects were a dynamic structure along the post-pulse time that caused a subsequent increment in the extraction yield. PMID:25819916

  1. Radiography of magnetically-driven implosions of initially solid beryllium cylindrical shells for equation-of-state studies at the Z pulsed-power facility

    NASA Astrophysics Data System (ADS)

    McBride, Ryan

    2011-06-01

    The Z accelerator delivers approximately 4-MV, 26-MA electrical pulses with adjustable current rise times of 100--600 ns, as well as adjustable pulse waveforms. The magnetic pressure produced is used for various applications, including magnetically-driven implosions. The Z-Beamlet Laser (ZBL) is a pulsed (0.3-1.5 ns), multi-kJ, TW-class Nd:glass laser system that provides x-ray radiography capabilities for Z experiments. This talk focuses primarily on the radiography diagnostic used to study the magnetically-driven implosions of initially solid cylindrical shells (also referred to as ``liners''). Specifically, we discuss the 6.151-keV monochromatic backlighting system and its use in obtaining radiographs of imploding beryllium (Be) liners. The high transmission efficiency of 6.151-keV photons in Be allowed us to obtain radiographs with finite transmission throughout the radial extent of the imploding liners. Abel inverting these data, we have obtained time-resolved measurements of the imploding liner's density as a function of both axial and radial location throughout the field of view. These data are allowing us to study magneto-Rayleigh-Taylor (MRT) growth for inertial-confinement-fusion applications, as well as compression-wave propagation for equation-of-state studies (see talks by R.L. Lemke and M.R. Martin). Additionally, Z's pulse-shaping capabilities have enabled us to obtain data for both shock- and quasi-isentropically-compressed Be. Example data from MRT, shock-compression, and quasi-isentropic-compression experiments will be shown. We will also discuss planned upgrades to 25-keV radiography that will allow us to study materials with opacities beyond that of beryllium. This work was done in collaboration with R.W. Lemke, M.R. Martin, J.-P. Davis, M.D. Knudson, D.B. Sinars, S.A. Slutz, C.A. Jennings, M.E. Cuneo, D.G. Flicker, and M.C. Herrmann. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin company, for the US

  2. Sleep modulates cortical connectivity and excitability in humans: Direct evidence from neural activity induced by single-pulse electrical stimulation.

    PubMed

    Usami, Kiyohide; Matsumoto, Riki; Kobayashi, Katsuya; Hitomi, Takefumi; Shimotake, Akihiro; Kikuchi, Takayuki; Matsuhashi, Masao; Kunieda, Takeharu; Mikuni, Nobuhiro; Miyamoto, Susumu; Fukuyama, Hidenao; Takahashi, Ryosuke; Ikeda, Akio

    2015-11-01

    Sleep-induced changes in human brain connectivity/excitability and their physiologic basis remain unclear, especially in the frontal lobe. We investigated sleep-induced connectivity and excitability changes in 11 patients who underwent chronic implantation of subdural electrodes for epilepsy surgery. Single-pulse electrical stimuli were directly injected to a part of the cortices, and cortico-cortical evoked potentials (CCEPs) and CCEP-related high-gamma activities (HGA: 100-200 Hz) were recorded from adjacent and remote cortices as proxies of effective connectivity and induced neuronal activity, respectively. HGA power during the initial CCEP component (N1) correlated with the N1 size itself across all states investigated. The degree of cortical connectivity and excitability changed during sleep depending on sleep stage, approximately showing dichotomy of awake vs. non-rapid eye movement (REM) [NREM] sleep. On the other hand, REM sleep partly had properties of both awake and NREM sleep, placing itself in the intermediate state between them. Compared with the awake state, single-pulse stimulation especially during NREM sleep induced increased connectivity (N1 size) and neuronal excitability (HGA increase at N1), which was immediately followed by intense inhibition (HGA decrease). The HGA decrease was temporally followed by the N2 peak (the second CCEP component), and then by HGA re-increase during sleep across all lobes. This HGA rebound or re-increase of neuronal synchrony was largest in the frontal lobe compared with the other lobes. These properties of sleep-induced changes of the cortex may be related to unconsciousness during sleep and frequent nocturnal seizures in frontal lobe epilepsy. PMID:26309062

  3. Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

    NASA Astrophysics Data System (ADS)

    Sulaeman, M. Y.; Widita, R.

    2014-09-01

    Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20-100 kV/cm and with shorter duration of pulse than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of -1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation.

  4. Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

    SciTech Connect

    Sulaeman, M. Y.; Widita, R.

    2014-09-30

    Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20–100 kV/cm and with shorter duration of pulse than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of −1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation.

  5. Effects of nanosecond pulsed electrical fields (nsPEFs) on the cell cycle of CHO and Jurkat cells

    NASA Astrophysics Data System (ADS)

    Mahlke, Megan A.; Navara, Christopher; Ibey, Bennett L.

    2014-03-01

    Exposure to nano-second pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. Variations between cell lines in membrane and cytoskeletal structure as well as in survival of nsPEF exposure should correspond to unique line-dependent cell cycle effects. Additionally, phase of cell cycle during exposure may be linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate role of cell cycle phase in survival of nsPEFs. CHO populations recovered similarly to sham populations postnsPEF exposure and did not exhibit a phase-specific change in response. Jurkat cells exhibited considerable apoptosis/necrosis in response to nsPEF exposure and were unable to recover and proliferate in a manner similar to sham exposed cells. Additionally, Jurkat cells appear to be more sensitive to nsPEFs in G2/M phases than in G1/S phases. Recovery of CHO populations suggests that nsPEFs do not inhibit proliferation in CHO cells; however, inhibition of Jurkat cells post-nsPEF exposure coupled with preferential cell death in G2/M phases suggest that cell cycle phase during exposure may be an important factor in determining nsPEF toxicity in certain cell lines. Interestingly, CHO cells have a more robust and rigid cytoskeleton than Jurkat cells which is thought to contribute to their ability to

  6. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact.

    PubMed

    Hart, Robert J; Zhupanska, Olesya I

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens. PMID:26827355

  7. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact

    NASA Astrophysics Data System (ADS)

    Hart, Robert J.; Zhupanska, Olesya I.

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens.

  8. A new pulsed electric field therapy for melanoma disrupts the tumor’s blood supply and causes complete remission without recurrence

    PubMed Central

    Nuccitelli, Richard; Chen, Xinhua; Pakhomov, Andrei G.; Baldwin, Wallace H.; Sheikh, Saleh; Pomicter, Jennifer L.; Ren, Wei; Osgood, Christopher; Swanson, R. James; Kolb, Juergen F.; Beebe, Stephen J.; Schoenbach, Karl H.

    2009-01-01

    We have discovered a new, ultrafast therapy for treating skin cancer that is extremely effective with a total electric field exposure time of only 180 μsec. The application of 300 high-voltage (40 kV/cm), ultrashort (300 nsec) electrical pulses to murine melanomas in vivo triggers both necrosis and apoptosis, resulting in complete tumor remission within an average of 47 days in the 17 animals treated. None of these melanomas recurred during a 4-month period after the initial melanoma had disappeared. These pulses generate small, long-lasting, rectifying nanopores in the plasma membrane of exposed cells, resulting in increased membrane permeability to small molecules and ions, as well as an increase in intracellular Ca2+, DNA fragmentation, disruption of the tumor’s blood supply and the initiation of apoptosis. Apoptosis was indicated by a 3-fold increase in Bad labeling and a 72% decrease in Bcl-2 labeling. In addition, microvessel density within the treated tumors fell by 93%. This new therapy utilizing nanosecond pulsed electric fields has the advantages of highly localized targeting of tumor cells and a total exposure time of only 180 μsec. These pulses penetrate into the interior of every tumor cell and initiate DNA fragmentation and apoptosis while at the same time reducing blood flow to the tumor. This new physical tumor therapy is drug free, highly localized, uses low energy, has no significant side effects and results in very little scarring. PMID:19408306

  9. Radioisotope fueled pulsed power generation system for propulsion and electrical power for deep space missions

    NASA Astrophysics Data System (ADS)

    Howe, Troy

    Space exploration missions to the moon, Mars, and other celestial bodies have allowed for great scientific leaps to enhance our knowledge of the universe; yet the astronomical cost of these missions limits their utility to only a few select agencies. Reducing the cost of exploratory space travel will give rise to a new era of exploration, where private investors, universities, and world governments can send satellites to far off planets and gather important data. By using radioisotope power sources and thermal storage devices, a duty cycle can be introduced to extract large amounts of energy in short amounts of time, allowing for efficient space travel. The same device can also provide electrical power for subsystems such as communications, drills, lasers, or other components that can provide valuable scientific information. This project examines the use of multiple radioisotope sources combined with a thermal capacitor using Phase Change Materials (PCMs) which can collect energy over a period of time. The result of this design culminates in a variety of possible spacecraft with their own varying costs, transit times, and objectives. Among the most promising are missions to Mars which cost less than 17M, missions that can provide power to satellite constellations for decades, or missions that can deliver large, Opportunity-sized (185kg) payloads to mars for less than 53M. All made available to a much wider range of customer with commercially available satellite launches from earth. The true cost of such progress though lies in the sometimes substantial increase in transit times for these missions.

  10. Efficacy of pulsed low-intensity electric neuromuscular stimulation in reducing pain and disability in patients with myofascial syndrome.

    PubMed

    Iodice, P; Lessiani, G; Franzone, G; Pezzulo, G

    2016-01-01

    Myofascial pain syndrome (MPS) is characterized by chronic pain in multiple myofascial trigger points and fascial constrictions. In recent years, the scientific literature has recognized the need to include the patient with MPS in a multidimensional rehabilitation project. At the moment, the most widely recognized therapeutic methods for the treatment of myofascial syndrome include the stretch and spray pressure massage. Microcurrent electric neuromuscular stimulation was proposed in pain management for its effects on normalizing bioelectricity of cells and for its sub-sensory application. In this study, we tested the efficacy of low-intensity pulsed electric neuromuscular stimulus (PENS) on pain in patients with MPS of cervical spine muscles. We carried out a prospective-analytic longitudinal study at an outpatient clinic during two weeks. Forty subjects (mean age 42±13 years) were divided into two groups: treatment (TrGr, n=20) and control group (CtrlGr, n=20). Visual-analog scale (VAS) values, concerning the spontaneous and movement-related pain in the cervical-dorsal region at baseline (T0) and at the end of the study (T1), showed a reduction from 7 to 3.81 (p < 0.001) in TrGr. In the CtrlGr, VAS was reduced from 8.2 to 7.2 (n.s.). Moreover, the pressure pain threshold at T0 was 2.1 vs 4.2 at T1 (p < 0.001) in TrG. In the CtrlGR we observed no significant changes. Modulated low-intensity PENS is an innovative therapy permitting to act on the transmission of pain and on the restoration of tissue homeostasis. It seems to affect the transmission of pain through the stimulation of A-beta fibers. The above results show that low-intensity PENS can be considered as an effective treatment to reduce pain and disability in patients with MPS. PMID:27358158

  11. Effect of heat-assisted pulsed electric fields and bacteriophage on enterohemorrhagic Escherichia coli O157:H7.

    PubMed

    Walkling-Ribeiro, Markus; Anany, Hany; Griffiths, Mansel W

    2015-01-01

    Pulsed electric fields (PEF), heat-assisted PEF (H-PEF), and virulent bacteriophage (VP) are non-thermal techniques for pathogen inactivation in liquids that were investigated individually, and in combination (PEF/VP, H-PEF/VP) to control enterohemorrhagic Escherichia coli (EHEC) O157:H7 in Luria-Bertani broth (LBB) and Ringer's solution (RS). Treated cells were subsequently incubated at refrigeration (4°C) and temperature-abuse conditions (12°C) for 5 days. When EHEC cells grown in LBB were subjected to non-thermal processing and subsequently stored at 12°C for 5 days, reductions in count of between 0.1 and 0.6 log cycles were observed and following storage at 4°C the decrease in counts varied between 0.2 and 1.1 log10 . For bacteria cells suspended in RS values ranged from 0.1 to ≥3.9 log cycles at both storage temperatures. The most effective treatments were H-PEF and H-PEF/VP, both producing a >3.4 log cycle reduction of cells suspended in non-nutrient RS. Analysis of EHEC recovery on selective and non-selective media indicated no occurrence of sub-lethal damage for VP, PEF/VP, and H-PEF/VP-treated cells. The findings indicate that combining PEF and lytic phage may represent a suitable alternative to conventional fluid decontamination following further process optimization. PMID:25376158

  12. Evaluation of the Genetic Response of U937 and Jurkat Cells to 10-Nanosecond Electrical Pulses (nsEP).

    PubMed

    Roth, Caleb C; Glickman, Randolph D; Tolstykh, Gleb P; Estlack, Larry E; Moen, Erick K; Echchgadda, Ibtissam; Beier, Hope T; Barnes, Ronald A; Ibey, Bennett L

    2016-01-01

    Nanosecond electrical pulse (nsEP) exposure activates signaling pathways, produces oxidative stress, stimulates hormone secretion, causes cell swelling and induces apoptotic and necrotic death. The underlying biophysical connection(s) between these diverse cellular reactions and nsEP has yet to be elucidated. Using global genetic analysis, we evaluated how two commonly studied cell types, U937 and Jurkat, respond to nsEP exposure. We hypothesized that by studying the genetic response of the cells following exposure, we would gain direct insight into the stresses experienced by the cell and in turn better understand the biophysical interaction taking place during the exposure. Using Ingenuity Systems software, we found genes associated with cell growth, movement and development to be significantly up-regulated in both cell types 4 h post exposure to nsEP. In agreement with our hypothesis, we also found that both cell lines exhibit significant biological changes consistent with mechanical stress induction. These results advance nsEP research by providing strong evidence that the interaction of nsEPs with cells involves mechanical stress. PMID:27135944

  13. CW and pulsed electrically detected magnetic resonance spectroscopy at 263GHz/12T on operating amorphous silicon solar cells.

    PubMed

    Akhtar, W; Schnegg, A; Veber, S; Meier, C; Fehr, M; Lips, K

    2015-08-01

    Here we describe a new high frequency/high field continuous wave and pulsed electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating at 263GHz and resonance fields between 0 and 12T. Spin dependent transport in illuminated hydrogenated amorphous silicon p-i-n solar cells at 5K and 90K was studied by in operando 263GHz CW and pEDMR alongside complementary X-band CW EDMR. Benefiting from the superior resolution at 263GHz, we were able to better resolve EDMR signals originating from spin dependent hopping and recombination processes. 5K EDMR spectra were found to be dominated by conduction and valence band tail states involved in spin dependent hopping, with additional contributions from triplet exciton states. 90K EDMR spectra could be assigned to spin pair recombination involving conduction band tail states and dangling bonds as the dominating spin dependent transport process, with additional contributions from valence band tail and triplet exciton states. PMID:26112328

  14. Pulsed electric field processing preserves the antiproliferative activity of the milk fat globule membrane on colon carcinoma cells.

    PubMed

    Xu, S; Walkling-Ribeiro, M; Griffiths, M W; Corredig, M

    2015-05-01

    The present work evaluated the effect of processing on the antiproliferative activities of milk fat globule membrane (MFGM) extracts. The antiproliferative activity on human adenocarcinoma HT-29 cells of untreated MFGM extracts were compared with those extracted from pasteurized cream, thermally treated cream, or cream subjected to pulsed electrical field (PEF) processing. The PEF with a 37 kV/cm field strength applied for 1,705μs at 50 and 65°C was applied to untreated cream collected from a local dairy. Heating at 50 or 65°C for 3min (the passage time in the PEF chamber) was also tested to evaluate the heating effect during PEF treatments. The MFGM extracted from pasteurized cream did not show an antiproliferative activity. On the other hand, isolates from PEF-treated cream showed activity similar to that of untreated samples. It was also shown that PEF induced interactions between β-lactoglobulin and MFGM proteins at 65°C, whereas the phospholipid composition remained unaltered. This work demonstrates the potential of PEF not only a means to produce a microbiologically safe product, but also as a process preserving the biofunctionality of the MFGM. PMID:25726115

  15. Evaluation of the Genetic Response of U937 and Jurkat Cells to 10-Nanosecond Electrical Pulses (nsEP)

    PubMed Central

    Glickman, Randolph D.; Tolstykh, Gleb P.; Estlack, Larry E.; Moen, Erick K.; Echchgadda, Ibtissam; Beier, Hope T.; Barnes, Ronald A.; Ibey, Bennett L.

    2016-01-01

    Nanosecond electrical pulse (nsEP) exposure activates signaling pathways, produces oxidative stress, stimulates hormone secretion, causes cell swelling and induces apoptotic and necrotic death. The underlying biophysical connection(s) between these diverse cellular reactions and nsEP has yet to be elucidated. Using global genetic analysis, we evaluated how two commonly studied cell types, U937 and Jurkat, respond to nsEP exposure. We hypothesized that by studying the genetic response of the cells following exposure, we would gain direct insight into the stresses experienced by the cell and in turn better understand the biophysical interaction taking place during the exposure. Using Ingenuity Systems software, we found genes associated with cell growth, movement and development to be significantly up-regulated in both cell types 4 h post exposure to nsEP. In agreement with our hypothesis, we also found that both cell lines exhibit significant biological changes consistent with mechanical stress induction. These results advance nsEP research by providing strong evidence that the interaction of nsEPs with cells involves mechanical stress. PMID:27135944

  16. Electropriming of wheatgrass seeds using pulsed electric fields enhances antioxidant metabolism and the bioprotective capacity of wheatgrass shoots.

    PubMed

    Leong, Sze Ying; Burritt, David John; Oey, Indrawati

    2016-01-01

    The influence of pulsed electric field (PEF) (0.5-2 kV/cm) treatment of wheatgrass (Triticum aestivum L.) seeds, with different water contents, on antioxidant metabolism in the resultant seedlings was investigated. Imbibing seeds to a water content of 45% or greater prior to PEF treatment increased the glutathione level and activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and ascorbate peroxidase in the resultant seedlings, compared to untreated controls. Pre-culture of human intestinal Caco-2 cells with simulated gastrointestinal digests of electrostimulated seedlings enhanced the ability of Caco-2 cells to cope with H2O2-induced oxidative damage, determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays. The Caco-2 cell MTT and LDH assays correlated better with the increases in seedling glutathione content and antioxidant enzyme activities compared to the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) total antioxidant capacity assay, an assay commonly used to determine the ability of plant extracts to protect cells from oxidative damage. These results demonstrate for the first time that PEF treatment of imbibed seeds can stimulate changes in metabolism in the resultant seedlings, increasing the bioprotective potential of their shoots/sprouts and hence value as functional foods. PMID:27147445

  17. Modeling of ultrashort pulsed laser irradiation in the cornea based on parabolic and hyperbolic heat equations using electrical analogy

    NASA Astrophysics Data System (ADS)

    Gheitaghy, A. M.; Takabi, B.; Alizadeh, M.

    2014-03-01

    Hyperbolic and parabolic heat equations are formulated to study a nonperfused homogeneous transparent cornea irradiated by high power and ultrashort pulsed laser in the Laser Thermo Keratoplasty (LTK) surgery. Energy absorption inside the cornea is modeled using the Beer-Lambert law that is incorporated as an exponentially decaying heat source. The hyperbolic and parabolic bioheat models of the tissue were solved by exploiting the mathematical analogy between thermal and electrical systems, by using robust circuit simulation program called Hspice to get the solutions of simultaneous RLC and RC transmission line networks. This method can be used to rapidly calculate the temperature in laser-irradiated tissue at time and space domain. It is found that internal energy gained from the irradiated field results in a rapid rise of temperature in the cornea surface during the early heating period, while the hyperbolic wave model predicts a higher temperature rise than the classical heat diffusion model. In addition, this paper investigates and examines the effect of some critical parameters such as relaxation time, convection coefficient, radiation, tear evaporation and variable thermal conductivity of cornea. Accordingly, it is found that a better accordance between hyperbolic and parabolic models will be achieved by time.

  18. Thresholds for igniting exothermic reactions in Al/Ni multilayers using pulses of electrical, mechanical, and thermal energy

    NASA Astrophysics Data System (ADS)

    Fritz, Gregory M.; Spey, Stephen J.; Grapes, Michael D.; Weihs, Timothy P.

    2013-01-01

    We use pulses of electrical, mechanical, and thermal energy to determine the ignition thresholds of self-propagating reactions in Al/(Ni-7 V) and Al/Inconel multilayers. The energy density and power density required to initiate reactions in a Al/(Ni-7 V) foil with a 50 nm bilayer is compared for all three techniques to demonstrate the importance of heat loss on ignition thresholds and its dependence on the test volume and the surrounding thermal resistance. In addition, ignition is shown to occur at temperatures as low as 232 °C when heat losses are very small suggesting that ignition can be controlled by atomic mixing in the solid state. The experiments demonstrate that the ignition threshold drops with increasing ignition volume, and it rises with increasing bilayer spacing and with increasing intermixed thickness. These trends are also supported by an analytical model we derive to predict the effects of ignition volume, multilayer microstructure, and physical properties on the ignition threshold. We calculate an activation energy of 77.3 ± 1.3 kJ/mol for solid state mixing based on measured ignition temperatures.

  19. Effect of repeated pulsed electric field treatment on the quality of hot-boned beef loins and topsides.

    PubMed

    Bekhit, Alaa El-Din A; Suwandy, Via; Carne, Alan; van de Ven, Remy; Hopkins, David L

    2016-01-01

    The effects of repeated (1×, 2×, 3×) pulsed electric field (PEF) treatment (10 kV, 90 Hz, 20 μs) on the quality of beef loins and topsides were evaluated, including the tenderness, purge loss, cooking loss, myofibrillar protein profile and post-mortem proteolysis. Both muscle types were obtained from each of 12 steers and were processed within 6h. After PEF treatment samples of both muscle types were subjected to 3, 7, 14 and 21 days ageing. The 1× and 2× PEF treatments had no effect on the tenderisation of hot-boned beef Musculus longissimus lumborum muscle for all ageing treatment times, while the 3× treatment reduced the tenderness. The opposite effect was observed in hot-boned beef Musculus semimembranosus muscles where the 3× treatment produced meat with lowest shear force at 3 days post-treatment time, but this beneficial effect disappeared with longer ageing times. An increase in proteolysis of troponin T was seen to the largest extent with 1× PEF treatment and decreased with every extra application of treatment. PMID:26398008

  20. Study and Identification of Microflora for the Preservation of Orange Juice using Pulsed Electric Field (PEF) Processing

    NASA Astrophysics Data System (ADS)

    Ghanshyam, C.; Kaur, Manpreet; Singh, Harjodh; Kapur, Pawan

    2011-12-01

    Pulsed Electric Field (PEF) is an emerging nonthermal food processing technology being effective in microbial inactivation without impairing the food quality. This paper demonstrates characterization of microbiota present in liquid food so that effective range of PEF can be set accordingly thus depicting the type of microorganism present, its morphology and its cell wall chemistry. The investigated microorganisms included E.coli, Staphylococcus aureus and Listeria monocytogenes, isolated from spoiled orange juice samples. These were characterized through a series of biochemical tests following microscopic (SEM) & spectroscopic (FTIR) characterization. The results were confirmed with respect to Standard MTCC (Microbial Type Culture Collection) strains (MTCC 614, MTCC 96, and MTCC 657). In comparison to Gram negative bacteria, the Gram positive bacteria are more resistant towards PEF. Larger microbial cells require less intense field strength to undergo an equivalent inactivation as compared to smaller cells. Cells in the exponential growth phase are more sensitive than the cells in lag or stationary phase, so it is necessary to identify the predominant bacteria in particular liquid foods.

  1. Electropriming of wheatgrass seeds using pulsed electric fields enhances antioxidant metabolism and the bioprotective capacity of wheatgrass shoots

    PubMed Central

    Leong, Sze Ying; Burritt, David John; Oey, Indrawati

    2016-01-01

    The influence of pulsed electric field (PEF) (0.5–2 kV/cm) treatment of wheatgrass (Triticum aestivum L.) seeds, with different water contents, on antioxidant metabolism in the resultant seedlings was investigated. Imbibing seeds to a water content of 45% or greater prior to PEF treatment increased the glutathione level and activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and ascorbate peroxidase in the resultant seedlings, compared to untreated controls. Pre-culture of human intestinal Caco-2 cells with simulated gastrointestinal digests of electrostimulated seedlings enhanced the ability of Caco-2 cells to cope with H2O2-induced oxidative damage, determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays. The Caco-2 cell MTT and LDH assays correlated better with the increases in seedling glutathione content and antioxidant enzyme activities compared to the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) total antioxidant capacity assay, an assay commonly used to determine the ability of plant extracts to protect cells from oxidative damage. These results demonstrate for the first time that PEF treatment of imbibed seeds can stimulate changes in metabolism in the resultant seedlings, increasing the bioprotective potential of their shoots/sprouts and hence value as functional foods. PMID:27147445

  2. Extraction assisted by pulsed electric energy as a potential tool for green and sustainable recovery of nutritionally valuable compounds from mango peels.

    PubMed

    Parniakov, Oleksii; Barba, Francisco J; Grimi, Nabil; Lebovka, Nikolai; Vorobiev, Eugene

    2016-02-01

    The study compares the efficiency of conventional aqueous extraction at different temperatures (20-60 °C) and pH (2.5-11) and extraction assisted by pulsed electric energy (pulsed electric fields, PEF or high voltage electrical discharges, HVED) of nutritionally valuable compounds found in mango peels. Exponential decay pulses with initial electric field strengths of ≈ 13.3 kV/cm and ≈ 40 kV/cm for PEF and HVED treatments were used, respectively. The impact of temperature on aqueous extraction of proteins and carbohydrates was not significant. The highest values of nutritionally valuable and antioxidant compounds (7.5mM TE) were obtained for aqueous extraction (T = 60 °C, pH 6) but extracts were unstable and cloudy. The application of two-stage procedure PEF+supplementary aqueous extraction (+SE) that include PEF-assisted extraction as the first step, and +SE at 50 °C, pH 6 during 3h as the second step, allowed a noticeable enhancement of the yields of TPC (+400%) even at normal pH. PMID:26304419

  3. Can the direct cardiac effects of the electric pulses generated by the TASER X26 cause immediate or delayed sudden cardiac arrest in normal adults?

    PubMed

    Ideker, Raymond E; Dosdall, Derek J

    2007-09-01

    There is only a small amount of experimental data about whether the TASER X26, a nonlethal weapon that delivers a series of brief electrical pulses to cause involuntary muscular contraction to temporarily incapacitate an individual, can initiate ventricular fibrillation to cause sudden cardiac arrest either immediately or sometime after its use. Therefore, this paper uses the fundamental law of electrostimulation and experimental data from the literature to estimate the likelihood of such events. Because of the short duration of the TASER pulses, the large duration of the cardiac cell membrane time constant, the small fraction of current from electrodes on the body surface that passes through the heart, and the resultant high pacing threshold from the body surface, the fundamental law of electrostimulation predicts that the TASER pulses will not stimulate an ectopic beat in the large majority of normal adults. Since the immediate initiation of ventricular fibrillation in a normal heart requires a very premature stimulated ectopic beat and the threshold for such premature beats is higher than less premature beats, it is unlikely that TASER pulses can immediately initiate ventricular fibrillation in such individuals through the direct effect of the electric field generated through the heart by the TASER. In the absence of preexisting heart disease, the delayed development of ventricular fibrillation requires the electrical stimuli to cause electroporation or myocardial necrosis. However, the electrical thresholds for electroporation and necrosis are many times higher than that required to stimulate an ectopic beat. Therefore, it is highly unlikely that the TASER X26 can cause ventricular fibrillation minutes to hours after its use through direct cardiac effects of the electric field generated by the TASER. PMID:17721165

  4. Influence of a Weak Field of Pulsed DC Electricity on the Behavior and Incidence of Injury in Adult Steelhead and Pacific Lamprey, Final Report.

    SciTech Connect

    Mesa, Matthew

    2009-02-13

    electrofishing operations typically use high voltage and amperage settings and a variety of waveforms, pulse widths (PW), and pulse frequencies (PF), depending on conditions and target species. For example, when backpack electrofishing for trout in a small stream, one might use settings such as 500 V pulsed DC, a PW of 1 ms, and a PF of 60 Hz. In contrast, the electrical barrier proposed by SRI will produce electrical conditions significantly lower than those used in electrofishing, particularly for PW and PF (e.g., PW ranging from 300-1,000 {micro}s and PF from 2-3 Hz). Further, voltage gradients (in V/cm) are predicted to be lower in the electric barrier than those produced during typical electrofishing. Although the relatively weak, pulsed DC electric fields to be produced by the barrier may be effective at deterring pinnipeds, little, if anything, is known about the effects of such low intensity electrical fields on fish behavior. For this research, we evaluated the effects of weak, pulsed DC electric currents on the behavior of adult steelhead and Pacific lamprey and the incidence of injury in steelhead only. In a series of laboratory experiments, we: (1) documented the rate of passage of fish over miniature, prototype electric barriers when they were on and off; (2) determined some electric thresholds beyond which fish would not pass over the barrier; and (3) assessed the incidence and severity of injury in steelhead exposed to relatively severe electrical conditions. The results of this study should be useful for making decisions about whether to install electrical barriers in the lower Columbia River, or elsewhere, to reduce predation on upstream migrating salmonids and other fishes by marine pinnipeds.

  5. [The influence of low-frequency pulsed electric and magnetic signals or their combination on the normal and modified fibroblasts (an experimental study)].

    PubMed

    Ulitko, M V; Medvedeva, S Yu; Malakhov, V V

    2016-01-01

    The results of clinical studies give evidence of the beneficial preventive and therapeutic effects of the «Tiline-EM» physiotherapeutic device designed for the combined specific treatment of the skin regions onto which both discomfort and pain sensations are directly projected, reflectively active sites and zones, as well as trigger zones with the use of low-frequency pulsed electric current and magnetic field. The efficient application of the device requires the understanding of the general mechanisms underlying such action on the living systems including those operating at the cellular and subcellular levels. The objective of the present study was the investigation of the specific and complex effects produced by the low-frequency pulses of electric current and magnetic field generated in the physiotherapeutic device «Tiline-EM» on the viability, proliferative activity, and morphofunctional characteristics of normal skin fibroblasts and the transformed fibroblast line K-22. It has been demonstrated that the biological effects of the electric and magnetic signals vary depending on the type of the cell culture and the mode of impact. The transformed fibroblasts proved to be more sensitive to the specific and complex effects of electric and magnetic pulses than the normal skin fibroblasts. The combined action of the electric and magnetic signals was shown to have the greatest influence on both varieties of fibroblasts. It manifests itself in the form of enhanced viability, elevated proliferative and synthetic activity in the cultures of transformed fibroblasts and as the acceleration of cell differentiation in the cultures of normal fibroblasts. The effect of stimulation of dermal fibroblast differentiation in response to the combined treatment by the electric and magnetic signals is of interest from the standpoint of the physiotherapeutic use of the «Tiline-EM» device for the purpose of obtaining fibroblasts cultures to be employed in regenerative therapy and

  6. Efficient generation of 480 fs electrical pulses on transmission lines by photoconductive switching in metalorganic chemical vapor deposited CdTe

    NASA Astrophysics Data System (ADS)

    Nuss, Martin C.; Kisker, D. W.; Smith, P. R.; Harvey, T. E.

    1989-01-01

    Electrical pulses of only 480 fs duration have been generated by photoconductive switching in CdTe grown by ultraviolet-enhanced metalorganic chemical vapor deposition (MOCVD). In addition to the extremely fast switching times, MOCVD CdTe also exhibits a high mobility of 180 sq cm/V s and can be grown on almost any substrate, making it ideal for integration into existing circuits and devices.

  7. Study of Water Purification with Pulsed Power Supply using MOSFET Switches

    NASA Astrophysics Data System (ADS)

    Shimizu, Kazuo; Blajan, Marius; Muramatsu, Shuichi

    A Marx generator using MOSFET switches was built and studied in this paper for water purification. In order to replace the spark gap type of pulse power sources, with miss fire problems and short mechanical lifetime. In case of Marx Generator which generates negative pulses, a maximum output voltage of 3.6 kV, rise time of 40 ns and pulse width of 600 ns, was obtained. Discharge energy of one pulse was about 801 μJ for negative polarity at -2.4 kV. In case of positive pulses, a maximum output voltage of 3.6 kV, rise time of 75 ns and pulse width of 750 ns, was obtained. Discharge energy of one pulse was about 1120 μJ at 2.4 kV. The discharge was generated in bubbling water using a Marx Generator with MOSFET switches. The discoloration of indigo carmine solution was carried out to investigate the feasibility of low voltage discharge in bubbling water. As a result, indigo carmine solution was decolorized, although the discharge voltage was about -2.4 kV. The treatment performance was improved when oxygen was fed in the solution. The discoloration rate was 100 % after treatment time of 15 min with oxygen used as carrier gas. Emission of OH was confirmed and considered to play a role for water purification.

  8. Inactivation of Escherichia coli in a tropical fruit smoothie by a combination of heat and pulsed electric fields.

    PubMed

    Walkling-Ribeiro, M; Noci, F; Cronin, D A; Lyng, J G; Morgan, D J

    2008-10-01

    Moderate heat in combination with pulsed electric fields (PEF) was investigated as a potential alternative to thermal pasteurization of a tropical fruit smoothie based on pineapple, banana, and coconut milk, inoculated with Escherichia coli K12. The smoothie was heated from 25 degrees C to either 45 or 55 degrees C over 60 s and subsequently cooled to 10 degrees C. PEF was applied at electric field strengths of 24 and 34 kV/cm with specific energy inputs of 350, 500, and 650 kJ/L. Both processing technologies were combined using heat (45 or 55 degrees C) and the most effective set of PEF conditions. Bacterial inactivation was estimated on standard and NaCl-supplemented tryptone soy agar (TSA) to enumerate sublethally injured cells. By increasing the temperature from 45 to 55 degrees C, a higher reduction in E. coli numbers (1 compared with 1.7 log(10) colony forming units {CFU} per milliliter, P < 0.05) was achieved. Similarly, as the field strength was increased during stand-alone PEF treatment from 24 to 34 kV/cm, a greater number of E. coli cells were inactivated (2.8 compared with 4.2 log(10) CFU/mL, P < 0.05). An increase in heating temperature from 45 to 55 degrees C during a combined heat/PEF hurdle approach induced a higher inactivation (5.1 compared with 6.9 log(10) CFU/mL, respectively [P < 0.05]) with the latter value comparable to the bacterial reduction of 6.3 log(10) CFU/mL (P> or = 0.05) achieved by thermal pasteurization (72 degrees C, 15 s). A reversed hurdle processing sequence did not affect bacterial inactivation (P> or = 0.05). No differences were observed (P> or = 0.05) between the bacterial counts estimated on nonselective and selective TSA, suggesting that sublethal cell injury did not occur during single PEF treatments or combined heat/PEF treatments. PMID:19019120

  9. Platelet-rich plasma stimulated by pulse electric fields: Platelet activation, procoagulant markers, growth factor release and cell proliferation.

    PubMed

    Frelinger Iii, A L; Torres, A S; Caiafa, A; Morton, C A; Berny-Lang, M A; Gerrits, A J; Carmichael, S L; Neculaes, V B; Michelson, A D

    2016-03-01

    Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications. PMID:26030682

  10. Electric Pulse Stimulation of Myotubes as an In Vitro Exercise Model: Cell-Mediated and Non-Cell-Mediated Effects

    PubMed Central

    Evers-van Gogh, Inkie J.A.; Alex, Sheril; Stienstra, Rinke; Brenkman, Arjan B.; Kersten, Sander; Kalkhoven, Eric

    2015-01-01

    Regular exercise has emerged as one of the best therapeutic strategies to prevent and treat type-2-diabetes. Exercise-induced changes in the muscle secretome, consisting of myokines and metabolites, may underlie the inter-organ communication between muscle and other organs. To investigate this crosstalk, we developed an in vitro system in which mouse C2C12 myotubes underwent electric pulse stimulation (EPS) to induce contraction. Subsequently the effects of EPS-conditioned media (EPS-CM) on hepatocytes were investigated. Here, we demonstrate that EPS-CM induces Metallothionein 1/2 and Slc30a2 gene expression and reduces Cyp2a3 gene expression in rat hepatocytes. When testing EPS-CM that was generated in the absence of C2C12 myotubes (non-cell EPS-CM) no decrease in Cyp2a3 expression was detected. However, similar inductions in hepatic Mt1/2 and Slc30a2 expression were observed. Non-cell EPS-CM were also applied to C2C12 myotubes and compared to C2C12 myotubes that underwent EPS: here changes in AMPK phosphorylation and myokine secretion largely depended on EPS-induced contraction. Taken together, these findings indicate that EPS can alter C2C12 myotube function and thereby affect gene expression in cells subjected to EPS-CM (Cyp2a3). However, EPS can also generate non-cell-mediated changes in cell culture media, which can affect gene expression in cells subjected to EPS-CM too. While EPS clearly represents a valuable tool in exercise research, care should be taken in experimental design to control for non-cell-mediated effects. PMID:26091097

  11. Combination of pulsed electric fields, mild heat and essential oils as an alternative to the ultrapasteurization of liquid whole egg.

    PubMed

    Espina, Laura; Monfort, Silvia; Alvarez, Ignacio; García-Gonzalo, Diego; Pagán, Rafael

    2014-10-17

    The production of microbiologically safe liquid whole egg (LWE) by industrial ultrapasteurization is restricted by the high thermal sensitivity of LWE components. This research proposes an alternative treatment based on the application of pulsed electric fields (PEF) and mild heat, in the presence of natural essential oils (EOs) or their individual components (ICs). The obtained results indicate that the successive application of PEF (25kV/ and 100kJ/kg) followed by heat (60°C during 3.5') to LWE added with 200μL/L of lemon EO would reach 4log10cycles of inactivation of Salmonella Senftenberg 775W and Listeria monocytogenes, when any of these barriers acting alone inactivated less than 1.5log10cycles of either bacteria. Therefore, the synergism between lemon EO and the successive application of PEF and heat would provide a safety level similar to that of ultrapasteurization treatment for Salmonella Senftenberg 775W and L. monocytogenes, but at a lower temperature. To a lesser extent, synergism with the successive application of PEF and heat was also observed in the presence of 200μL/L of carvacrol, citral, (+)-limonene, or mandarin EO, reaching about 3.5log10cycles of inactivation in Salmonella Senftenberg and 3.0log10cycles in L. monocytogenes, respectively. A sensory test on LWE containing 200μL/L of each additive in the form of omelets and sponge cakes revealed that this concentration of mandarin EO, lemon EO, or (+)-limonene did not decrease the sensory acceptability of the LWE-containing products, and lemon EO and mandarin EO even increased the hedonic acceptability of sponge cakes. In conclusion, this process could be applied in the food industry to obtain microbiologically safe LWE, which could be used to produce egg-based products without decreasing (and even increasing) their sensory appeal. PMID:25146463

  12. Effects of ultraviolet irradiation, pulsed electric field, hot water and ethanol vapours treatment on functional properties of mung bean sprouts.

    PubMed

    Goyal, Ankit; Siddiqui, Saleem; Upadhyay, Neelam; Soni, Jyoti

    2014-04-01

    The present investigation was conducted with the objective to study the effects of various treatments and storage conditions on ascorbic acid, total phenols, antioxidant activity and polyphenol oxidase activity of mung bean sprouts. The sprouts subjected to various treatments viz., pulsed electric field (PEF) (10,000 V for 10 s), hot water dip (HWD) (50 °C for 2 min), ethanol vapours (1 h) and UV-Irradiation (10 kJm(-2) in laminar flow chamber for 1 h); and then stored at room (25 ± 1 °C) and low (7 ± 1 °C) temperature conditions. The sprouts were analyzed regularly at 24 h interval till end of shelf life. Different treatments given to sprouts resulted in differential effect on various parameters. The ascorbic acid, total phenols and antioxidant activity were highest in ethanol vapours treated sprouts. There was a general decrease in polyphenol oxidase activity by various treatments. During storage ascorbic acid, total phenols and antioxidant activity of sprouts first increased and then decreased significantly, however, for polyphenol oxidase activity a progressive increase with increase in storage period was observed. The trends were similar at room and low temperature storage conditions. Thus, it can be concluded that the ethanol vapours significantly improved the ascorbic acid content, total phenols and antioxidant activity of mung bean sprouts, both at room as well as low temperature conditions of storage. PMID:24741164

  13. Cellular regulation of extension and retraction of pseudopod-like blebs produced by nanosecond pulsed electric field (nsPEF)

    PubMed Central

    Rassokhin, Mikhail A.; Pakhomov, Andrei G.

    2014-01-01

    Recently we described a new phenomenon of anodotropic pseudopod-like blebbing in U937 cells exposed to nanosecond pulsed electric field (nsPEF). In Ca2+-free buffer such exposure initiates formation of pseudopod-like blebs (PLBs), protrusive cylindrical cell extensions that are distinct from apoptotic and necrotic blebs. PLBs nucleate predominantly on anode-facing cell pole and extend towards anode during nsPEF exposure. Bleb extension depends on actin polymerization and availability of actin monomers. Inhibition of intracellular Ca2+, cell contractility and RhoA produced no effect on PLB initiation. Meanwhile, inhibition of WASP by wiskostatin causes dose-dependent suppression of PLB growth. Soon after the end of nsPEF exposure PLBs lose directionality of growth and then retract. Microtubule toxins nocodazole and paclitaxel did not show immediate effect on PLBs; however, nocodazole increased mobility of intracellular components during PLB extension and retraction. Retraction of PLBs is produced by myosin activation and corresponding increase in PLB cortex contractility. Inhibition of myosin by blebbistatin reduces retraction while inhibition of RhoA-ROCK pathway by Y-27632 completely prevents retraction. Contraction of PLBs can produce cell translocation resembling active cell movement. Overall, the formation, properties, and lifecycle of PLBs share common features with protrusions associated with amoeboid cell migration. PLB lifecycle may be controlled through activation of WASP by its upstream effectors such as Cdc42 and PIP2, and main ROCK activator - RhoA. Parallels between pseudopod-like blebbing and motility blebbing may provide new insights into their underlying mechanisms. PMID:24488232

  14. Evaluation of the anthocyanin release and health-promoting properties of Pinot Noir grape juices after pulsed electric fields.

    PubMed

    Leong, Sze Ying; Burritt, David John; Oey, Indrawati

    2016-04-01

    This study evaluated the health-promoting properties of Pinot Noir juices (Vitis vinifera L.) obtained at different maceration times after pulsed electric fields (PEF) using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and human intestinal Caco-2 cells assays. Juice quality, anthocyanins, total phenolics and vitamin C were also determined. The evaluation of bioprotective capacity of the juice against H2O2-induced oxidative stress in Caco-2 cells was determined using biomarkers for cellular health and integrity: cell viability and lactate dehydrogenase (LDH) leakage. Compared to untreated grape juice, PEF pre-treatment on grapes enhanced the release of the major anthocyanin found in Pinot Noir, i.e. malvidin-3-O-glucoside (+224%). Increase in the content of total phenolic (+61%) and vitamin C (+19%) as well as improvement in the DPPH scavenging activity (+31%) and bioprotective capacity (+25% for cell viability and +30% for LDH leakage) were observed in grape juices following PEF treatment. Bioprotective capacity determined by the cellular biomarkers had significant linear correlations with malvidin-3-O-glucoside content (0.71⩽r⩽0.73) whereas DPPH scavenging activity was not well correlated with malvidin-3-O-glucoside (r=0.30) and total phenolics (r=0.30). Therefore, evaluation of the bioprotective capacities using Caco-2 cell assay performed in this study makes a novel contribution to the current knowledge that demonstrates the capability of PEF technology to produce plant-based foods with better phytochemical composition and exhibiting the capacity to protect cells from oxidative stress. PMID:26593562

  15. Low-intensity pulsed ultrasonography versus electrical stimulation for fracture healing: a systematic review and network meta-analysis

    PubMed Central

    Ebrahim, Shanil; Mollon, Brent; Bance, Sheena; Busse, Jason W.; Bhandari, Mohit

    2014-01-01

    Background To best inform evidence-based patient care, it is often desirable to compare competing therapies. We performed a network meta-analysis to indirectly compare low intensity pulsed ultrasonography (LIPUS) with electrical stimulation (ESTIM) for fracture healing. Methods We searched the reference lists of recent reviews evaluating LIPUS and ESTIM that included studies published up to 2011 from 4 electronic databases. We updated the searches of all electronic databases up to April 2012. Eligible trials were those that included patients with a fresh fracture or an existing delayed union or nonunion who were randomized to LIPUS or ESTIM as well as a control group. Two pairs of reviewers, independently and in duplicate, screened titles and abstracts, reviewed the full text of potentially eligible articles, extracted data and assessed study quality. We used standard and network meta-analytic techniques to synthesize the data. Results Of the 27 eligible trials, 15 provided data for our analyses. In patients with a fresh fracture, there was a suggested benefit of LIPUS at 6 months (risk ratio [RR] 1.17, 95% confidence interval [CI] 0.97–1.41). In patients with an existing nonunion or delayed union, ESTIM had a suggested benefit over standard care on union rates at 3 months (RR 2.05, 95% CI 0.99–4.24). We found very low-quality evidence suggesting a potential benefit of LIPUS versus ESTIM in improving union rates at 6 months (RR 0.76, 95% CI 0.58–1.01) in fresh fracture populations. Conclusion To support our findings direct comparative trials with safeguards against bias assessing outcomes important to patients, such as functional recovery, are required. PMID:24869616

  16. Consumer perception of the use of high-pressure processing and pulsed electric field technologies in food production.

    PubMed

    Nielsen, Henriette Boel; Sonne, Anne-Mette; Grunert, Klaus G; Banati, Diana; Pollák-Tóth, Annamária; Lakner, Zoltán; Olsen, Nina Veflen; Zontar, Tanja Pajk; Peterman, Marjana

    2009-02-01

    The success of new food processing technologies is highly dependent on consumers' acceptance. The purpose of this paper is to study consumers' perceptions of two new processing technologies and food products produced by means of these novel technologies. To accomplish this, a qualitative study on consumer attitudes towards high-pressure processing (HPP) and pulsed electric field (PEF) processing of food was carried out. In all 97 adults between 20 and 71 years of age participated in 12 focus groups conducted in Slovenia, Hungary, Serbia, Slovakia, Norway and Denmark using a common guideline. Participants were introduced to the HPP and PEF technologies and then to the effect of the two new technologies on two specific product categories: juice and baby food. The transcribed data was content analysed and the coded data was transformed into diagrams using UCINET 5 and NETDRAW. The results show that consumers perceived the main advantages of HPP and PEF products to be the products' naturalness, improved taste and their high nutritional value, whereas the main disadvantage was the lack of information about the PEF and HPP products. The results of the participants' evaluation of the PEF and HPP processes showed that environmental friendliness and the more natural products were seen as the main advantages, while they were concerned about body and health, the higher price of the products, the lack of information about the technologies and a general scepticism. The study also shows that North European participants were a bit more sceptical towards PEF and HPP products than the East European participants. PMID:18845196

  17. Cellular regulation of extension and retraction of pseudopod-like blebs produced by nanosecond pulsed electric field (nsPEF).

    PubMed

    Rassokhin, Mikhail A; Pakhomov, Andrei G

    2014-07-01

    Recently we described a new phenomenon of anodotropic pseudopod-like blebbing in U937 cells exposed to nanosecond pulsed electric field (nsPEF). In Ca(2+)-free buffer such exposure initiates formation of pseudopod-like blebs (PLBs), protrusive cylindrical cell extensions that are distinct from apoptotic and necrotic blebs. PLBs nucleate predominantly on anode-facing cell pole and extend toward anode during nsPEF exposure. Bleb extension depends on actin polymerization and availability of actin monomers. Inhibition of intracellular Ca(2+), cell contractility, and RhoA produced no effect on PLB initiation. Meanwhile, inhibition of WASP by wiskostatin causes dose-dependent suppression of PLB growth. Soon after the end of nsPEF exposure PLBs lose directionality of growth and then retract. Microtubule toxins nocodazole and paclitaxel did not show immediate effect on PLBs; however, nocodazole increased mobility of intracellular components during PLB extension and retraction. Retraction of PLBs is produced by myosin activation and the corresponding increase in PLB cortex contractility. Inhibition of myosin by blebbistatin reduces retraction while inhibition of RhoA-ROCK pathway by Y-27632 completely prevents retraction. Contraction of PLBs can produce cell translocation resembling active cell movement. Overall, the formation, properties, and life cycle of PLBs share common features with protrusions associated with ameboid cell migration. PLB life cycle may be controlled through activation of WASP by its upstream effectors such as Cdc42 and PIP2, and main ROCK activator-RhoA. Parallels between pseudopod-like blebbing and motility blebbing may provide new insights into their underlying mechanisms. PMID:24488232

  18. Long-pulse gastric electrical stimulation protects interstitial cells of Cajal in diabetic rats via IGF-1 signaling pathway

    PubMed Central

    Li, Hai; Chen, Yan; Liu, Shi; Hou, Xiao-Hua

    2016-01-01

    AIM: To investigate the effects of different parameters of gastric electrical stimulation (GES) on interstitial cells of Cajal (ICCs) and changes in the insulin-like growth factor 1 (IGF-1) signal pathway in streptozotocin-induced diabetic rats. METHODS: Male rats were randomized into control, diabetic (DM), diabetic with sham GES (DM + SGES), diabetic with GES1 (5.5 cpm, 100 ms, 4 mA) (DM + GES1), diabetic with GES2 (5.5 cpm, 300 ms, 4 mA) (DM + GES2) and diabetic with GES3 (5.5 cpm, 550 ms, 2 mA) (DM + GES3) groups. The expression levels of c-kit, M-SCF and IGF-1 receptors were evaluated in the gastric antrum using Western blot analysis. The distribution of ICCs was observed using immunolabeling for c-kit, while smooth muscle cells and IGF-1 receptors were identified using α-SMA and IGF-1R antibodies. Serum level of IGF-1 was tested using enzyme-linked immunosorbent assay. RESULTS: Gastric emptying was delayed in the DM group but improved in all GES groups, especially in the GES2 group. The expression levels of c-kit, M-SCF and IGF-1R were decreased in the DM group but increased in all GES groups. More ICCs (c-kit+) and smooth muscle cells (α-SMA+/IGF-1R+) were observed in all GES groups than in the DM group. The average level of IGF-1 in the DM group was markedly decreased, but it was up-regulated in all GES groups, especially in the GES2 group. CONCLUSION: The results suggest that long-pulse GES promotes the regeneration of ICCs. The IGF-1 signaling pathway might be involved in the mechanism underlying this process, which results in improved gastric emptying. PMID:27340351

  19. A ‘frozen electric-field’ approach to simulate repetitively pulsed nanosecond plasma discharges and ignition of hydrogen-air mixtures

    NASA Astrophysics Data System (ADS)

    Nagaraja, Sharath; Yang, Vigor

    2014-09-01

    High-fidelity modelling of nanosecond repetitively pulsed discharges (NRPDs) is burdened by the multiple time and length scales and large chemistry mechanisms involved, which prohibit detailed analyses and parametric studies. In the present work, we propose a ‘frozen electric-field’ modelling approach to expedite the NRPD simulations without adverse effects on the solution accuracy. First, a burst of nanosecond voltage pulses is simulated self-consistently until the discharge reaches a stationary state. The calculated spatial distributions and temporal evolution of the electric field, electron density and electron energy during the last pulse are then stored in a library and the electrical characteristics of subsequent pulses are frozen at these values. This strategy allows the timestep for numerical integration to be increased by four orders of magnitude (from 10-13 to 10-9 s), thereby significantly improving the computational efficiency of the process. Reduced calculations of a burst of 50 discharge pulses show good agreement with the predictions from a complete plasma model (electrical characteristics calculated during each pulse). The error in species densities is less than 20% at the centre of the discharge volume and about 30% near the boundaries. The deviations in temperature, however, are much lower, at 5% in the entire domain. The model predictions are in excellent agreement with measured ignition delay times and temperatures in H2-air mixtures subject to dielectric barrier NRPD over a pressure range of 54-144 Torr with equivalence ratios of 0.7-1.2. The OH density increases with pressure and triggers low-temperature fuel oxidation, which leads to rapid temperature rise and ignition. The ignition delay decreases by a factor of 2, with an increase in pressure from 54 to 144 Torr. In contrast, an increase in the H2-air equivalence ratio from 0.7 to 1.2 marginally decreases the ignition delay by about 20%. This behaviour is attributed to the insensitivity

  20. Current pulse shaping of the load current on PTS

    NASA Astrophysics Data System (ADS)

    Xia, Minghe; Li, Fengping; Ji, Ce; Wei, Bing; Feng, Shuping; Wang, Meng; Xie, Weiping

    2016-02-01

    The typical rise time of PTS machine is ˜110 ns with about 10 MA peak current under short pulse mode when all 24 modules discharge simultaneously. By distributing the trigger times of 12 laser beams logically and adjusting the statues of the pulse output switches, longer rise-time pulse can be obtained on the PTS facility. Based on the required pulse shape, whole circuit simulations will be used to calculate the trigger times of each laser triggering gas switch and the status of the pulse output switches. The rise time of the current is determined by the time difference between the first and last trigged laser triggering gas switches. In order to trigger the laser triggering gas switch, sufficient laser power is needed to be sent into the gap of the gas switches. The gas pressure and voltage difference on the two electrodes of the gas switches also affect the triggering of the gas switches, and the voltage added on the gas switch is determined by its transition time. Traditionally the trigger time difference should be less than the transition time of the two neighboring modules. A new simulation model of PTS shows one can break this transition time limits. Series of current pulse shaping experiments have been investigated on the PTS (Primary Test Stand). As results, more than 5 MA peak current were successfully achieved on the load with a rise time of 600 ns. This study and experiments of the pulse shaping on PTS demonstrate the adaptable ability of the PTS for offering different waveform of mega ampere current pulse for different research purpose.

  1. Changes in electrode microstructure and charge efficiency produced by pulsed discharge of electric vehicle lead acid batteries

    SciTech Connect

    Caulder, S.; Dowgiallo, E.; Simon, A.

    1982-08-01

    Comparison of battery plates with invariant vs. pulsed current discharges showed greater electrolyte stratification and a more rapid detrimental change in active material microstructure for the batteries receiving the pulsed discharges. This microstructural change could not be reversed by subsequent invariant current discharges. No significant differences in grid corrosion rate were noted in the two discharge modes.

  2. Comparative Study of Pulp Vitality in Primary and Young Permanent Molars in Human Children with Pulse Oximeter and Electric Pulp Tester

    PubMed Central

    Sood, PB; Sharma, Arun; Madan, Manish; Shahi, Nishat; Gandhi, Geetanjali

    2015-01-01

    ABSTRACT Aim and objective: The purpose of this study was to compare the pulp testing methods (pulse oximetry and electric pulp test) in primary and young permanent teeth of children. Materials and methods: The study included a total of 155 children aged 4 to 15 years. Twenty children formed control group I. Study group included all healthy, 85 primary 2nd molars in group II and 85 permanent 1st molars in group III. Fifty children needing endodontics treatment formed test group IV. The readings were recorded as true positive (TP), false positive (FP), true negative (TN), false negative (FN). Based on this, the sensitivity, specificity, positive predictive value and negative predictive value were calculated for each method. The results were statistically analyzed using Chi-square test. Results: On comparing pulse oximetry with electric pulp test ‘p-value’ was found to be 0.487 and 1.00 for groups 1 and 2 respectively and was statistically not significant. Whereas ‘p-value’ for groups 3 and 4 was < 0.0001 and 0.003 respectively and was statistically highly significant. Conclusion: The present study indicates that pulse oximetry can be used as a routine method for assessing the pulp vitality in primary, young permanent and mature permanent teeth. How to cite this article: Shahi P, Sood PB, Sharma A, Madan M, Shahi N, Gandhi G. Comparative Study of Pulp Vitality in Primary and Young Permanent Molars in Human Children with Pulse Oximeter and Electric Pulp Tester. Int J Clin Pediatr Dent 2015;8(2):94-98. PMID:26379374

  3. Improvement in the statistical operation of a Blumlein pulse forming line in bipolar pulse mode

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. I.; Isakova, Y. I.; Khaylov, I. P.

    2014-07-01

    The paper presents the results of studies on shot-to-shot performance of a water Blumlein pulse forming line of 1-1.2 kJ of stored energy. The experiments were carried using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (150 ns, 250-300 kV) and bipolar-pulse mode with the first negative (300-600 ns, 100-150 kV) followed by a second positive (120 ns, 250-300 kV) pulse. The analysis was carried out for two cases when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. It was found that in bipolar pulse mode the shot-to-shot variation in breakdown voltage of a preliminary spark gap is small, the standard deviation (1σ) does not exceed 2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar-pulse and unipolar pulse mode is 3-4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we changed the regime of its operation from a self-triggered mode to an externally triggered mode. In the new arrangement the first voltage pulse at the output of Blumlein was used to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a good stability of breakdown voltage and thus allowed to stabilize the duration of the first pulse. The standard deviation of the breakdown voltage and duration of the first pulse did not exceed 2% for a set of 50 pulses. The externally triggered mode of the main gap operation also allowed for a decrease in the charging voltage of the Blumlein to a 0.9-0.95 of self-breakdown voltage of the main spark gap while the energy stored in Marx generator was decreased from 4 kJ to 2.5 kJ. At the same time the energy stored in Blumlein remained the same.

  4. Improvement in the statistical operation of a Blumlein pulse forming line in bipolar pulse mode

    SciTech Connect

    Pushkarev, A. I. Isakova, Y. I.; Khaylov, I. P.

    2014-07-15

    The paper presents the results of studies on shot-to-shot performance of a water Blumlein pulse forming line of 1–1.2 kJ of stored energy. The experiments were carried using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (150 ns, 250–300 kV) and bipolar-pulse mode with the first negative (300–600 ns, 100–150 kV) followed by a second positive (120 ns, 250–300 kV) pulse. The analysis was carried out for two cases when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. It was found that in bipolar pulse mode the shot-to-shot variation in breakdown voltage of a preliminary spark gap is small, the standard deviation (1σ) does not exceed 2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar-pulse and unipolar pulse mode is 3–4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we changed the regime of its operation from a self-triggered mode to an externally triggered mode. In the new arrangement the first voltage pulse at the output of Blumlein was used to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a good stability of breakdown voltage and thus allowed to stabilize the duration of the first pulse. The standard deviation of the breakdown voltage and duration of the first pulse did not exceed 2% for a set of 50 pulses. The externally triggered mode of the main gap operation also allowed for a decrease in the charging voltage of the Blumlein to a 0.9–0.95 of self-breakdown voltage of the main spark gap while the energy stored in Marx generator was decreased from 4 kJ to 2.5 kJ. At the same time the energy stored in Blumlein remained the same.

  5. Improvement in the statistical operation of a Blumlein pulse forming line in bipolar pulse mode.

    PubMed

    Pushkarev, A I; Isakova, Y I; Khaylov, I P

    2014-07-01

    The paper presents the results of studies on shot-to-shot performance of a water Blumlein pulse forming line of 1-1.2 kJ of stored energy. The experiments were carried using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (150 ns, 250-300 kV) and bipolar-pulse mode with the first negative (300-600 ns, 100-150 kV) followed by a second positive (120 ns, 250-300 kV) pulse. The analysis was carried out for two cases when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. It was found that in bipolar pulse mode the shot-to-shot variation in breakdown voltage of a preliminary spark gap is small, the standard deviation (1σ) does not exceed 2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar-pulse and unipolar pulse mode is 3-4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we changed the regime of its operation from a self-triggered mode to an externally triggered mode. In the new arrangement the first voltage pulse at the output of Blumlein was used to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a good stability of breakdown voltage and thus allowed to stabilize the duration of the first pulse. The standard deviation of the breakdown voltage and duration of the first pulse did not exceed 2% for a set of 50 pulses. The externally triggered mode of the main gap operation also allowed for a decrease in the charging voltage of the Blumlein to a 0.9-0.95 of self-breakdown voltage of the main spark gap while the energy stored in Marx generator was decreased from 4 kJ to 2.5 kJ. At the same time the energy stored in Blumlein remained the same. PMID:25085130

  6. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    PubMed Central

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  7. Towards pump probe experiments of defect dynamics with short ion beam pulses

    SciTech Connect

    Schenkel, T.; Lidia, S.; Weis, C. D.; Waldron, W. L.; Schwartz, J.; Minor, Andrew; Hosemann, P; Kwan, J. W.

    2013-01-01

    A novel, induction type linear accelerator, the Neutralized Drift Compression eXperiment (NDCX-II), is currently being commissioned at Berkeley Lab. This accelerator is designed to deliver intense (up to 3 1011 ions/pulse), 0.6 to 600 ns duration pulses of 0.05 1.2 MeV lithium ions at a rate of about 2 pulses per minute onto 1 10 mm scale target areas. When focused to mm-diameter spots, the beam is predicted to volumetrically heat micrometer thick foils to temperatures of 30,000 K. At lower beam power densities, the short excitation pulse with tunable intensity and time profile enables pump probe type studies of defect dynamics in a broad range of materials. We briefly describe the accelerator concept and design, present results from beam pulse shaping experiments and discuss examples of pump probe type studies of defect dynamics following irradiation of materials with intense, short ion beam pulses from NDCX-II.

  8. Towards pump-probe experiments of defect dynamics with short ion beam pulses

    NASA Astrophysics Data System (ADS)

    Schenkel, T.; Lidia, S. M.; Weis, C. D.; Waldron, W. L.; Schwartz, J.; Minor, A. M.; Hosemann, P.; Kwan, J. W.

    2013-11-01

    A novel, induction type linear accelerator, the Neutralized Drift Compression eXperiment (NDCX-II), is currently being commissioned at Berkeley Lab. This accelerator is designed to deliver intense (up to 3 × 1011 ions/pulse), 0.6 to ∼600 ns duration pulses of 0.05-1.2 MeV lithium ions at a rate of about 2 pulses per minute onto 1-10 mm scale target areas. When focused to mm-diameter spots, the beam is predicted to volumetrically heat micrometer thick foils to temperatures of ∼30,000 °K. At lower beam power densities, the short excitation pulse with tunable intensity and time profile enables pump-probe type studies of defect dynamics in a broad range of materials. We briefly describe the accelerator concept and design, present results from beam pulse shaping experiments and discuss examples of pump-probe type studies of defect dynamics following irradiation of materials with intense, short ion beam pulses from NDCX-II.

  9. Generation and the role of dislocations in single-crystalline phase-change In2Se3 nanowires under electrical pulses

    NASA Astrophysics Data System (ADS)

    Mafi, Elham; Tao, Xin; Zhu, Wenguang; Gao, Yanfei; Wang, Chongmin; Gu, Yi

    2016-08-01

    We report the observation of the generation of dislocations in single-crystal phase-change In2Se3 nanowires under electrical pulses and the impact of these dislocations on electrical properties. Particularly, we correlated the atomic-scale structural characteristics with local electrical resistance variations, by performing transmission electron microscopy and scanning Kelvin probe microscopy on the same nanowires. By coupling the experimental results with first-principles density functional theory calculations, we show that the immobile dislocations are generated via vacancy condensations. Importantly, these dislocations lead to several orders of magnitude increase in the electrical resistance, while maintaining the single crystallinity of the lattice. These results significantly advance the fundamental understanding of the structure-property relation in this phase-change material under transient electrical excitations. From a practical perspective, the significant increase in the electrical resistance, driven by the formation of dislocations, can be exploited as a new electronic state in the single-crystalline phase in this phase-change material.

  10. Generation and the role of dislocations in single-crystalline phase-change In2Se3 nanowires under electrical pulses.

    PubMed

    Mafi, Elham; Tao, Xin; Zhu, Wenguang; Gao, Yanfei; Wang, Chongmin; Gu, Yi

    2016-08-19

    We report the observation of the generation of dislocations in single-crystal phase-change In2Se3 nanowires under electrical pulses and the impact of these dislocations on electrical properties. Particularly, we correlated the atomic-scale structural characteristics with local electrical resistance variations, by performing transmission electron microscopy and scanning Kelvin probe microscopy on the same nanowires. By coupling the experimental results with first-principles density functional theory calculations, we show that the immobile dislocations are generated via vacancy condensations. Importantly, these dislocations lead to several orders of magnitude increase in the electrical resistance, while maintaining the single crystallinity of the lattice. These results significantly advance the fundamental understanding of the structure-property relation in this phase-change material under transient electrical excitations. From a practical perspective, the significant increase in the electrical resistance, driven by the formation of dislocations, can be exploited as a new electronic state in the single-crystalline phase in this phase-change material. PMID:27389929

  11. Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield

    SciTech Connect

    Vagin, Nikolai P; Ionin, Andrei A; Klimachev, Yu M; Kotkov, A A; Podmar'kov, Yu P; Seleznev, L V; Sinitsyn, D V; Frolov, M P; Yuryshev, Nikolai N; Kochetov, Igor' V; Napartovich, A P; Hager, G D

    2004-09-30

    The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume ({approx}18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts ({approx}1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving {approx}6.5 kJ L{sup -1} atm{sup -1} per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O{sub 2} : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O{sub 2}(a{sup 1{Delta}}{sub g}) and O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O{sub 2}(a{sup 1{Delta}}{sub g}) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value {approx}3% for W {approx} 1.0 kJ L{sup -1} atm{sup -1} is in agreement with the theoretical estimate. Theoretical calculations performed for W {approx} 6.5 kJ L{sup -1} atm{sup -1} at a fixed temperature show that the singlet-oxygen yield may be {approx}20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)

  12. Periodically pulsed wet annealing approach for low-temperature processable amorphous InGaZnO thin film transistors with high electrical performance and ultrathin thickness.

    PubMed

    Kim, Ye Kyun; Ahn, Cheol Hyoun; Yun, Myeong Gu; Cho, Sung Woon; Kang, Won Jun; Cho, Hyung Koun

    2016-01-01

    In this paper, a simple and controllable "wet pulse annealing" technique for the fabrication of flexible amorphous InGaZnO thin film transistors (a-IGZO TFTs) processed at low temperature (150 °C) by using scalable vacuum deposition is proposed. This method entailed the quick injection of water vapor for 0.1 s and purge treatment in dry ambient in one cycle; the supply content of water vapor was simply controlled by the number of pulse repetitions. The electrical transport characteristics revealed a remarkable performance of the a-IGZO TFTs prepared at the maximum process temperature of 150 °C (field-effect mobility of 13.3 cm(2) V(-1) s(-1); Ion/Ioff ratio ≈ 10(8); reduced I-V hysteresis), comparable to that of a-IGZO TFTs annealed at 350 °C in dry ambient. Upon analysis of the angle-resolved x-ray photoelectron spectroscopy, the good performance was attributed to the effective suppression of the formation of hydroxide and oxygen-related defects. Finally, by using the wet pulse annealing process, we fabricated, on a plastic substrate, an ultrathin flexible a-IGZO TFT with good electrical and bending performances. PMID:27198067

  13. Periodically pulsed wet annealing approach for low-temperature processable amorphous InGaZnO thin film transistors with high electrical performance and ultrathin thickness

    PubMed Central

    Kim, Ye Kyun; Ahn, Cheol Hyoun; Yun, Myeong Gu; Cho, Sung Woon; Kang, Won Jun; Cho, Hyung Koun

    2016-01-01

    In this paper, a simple and controllable “wet pulse annealing” technique for the fabrication of flexible amorphous InGaZnO thin film transistors (a-IGZO TFTs) processed at low temperature (150 °C) by using scalable vacuum deposition is proposed. This method entailed the quick injection of water vapor for 0.1 s and purge treatment in dry ambient in one cycle; the supply content of water vapor was simply controlled by the number of pulse repetitions. The electrical transport characteristics revealed a remarkable performance of the a-IGZO TFTs prepared at the maximum process temperature of 150 °C (field-effect mobility of 13.3 cm2 V−1 s−1; Ion/Ioff ratio ≈ 108; reduced I-V hysteresis), comparable to that of a-IGZO TFTs annealed at 350 °C in dry ambient. Upon analysis of the angle-resolved x-ray photoelectron spectroscopy, the good performance was attributed to the effective suppression of the formation of hydroxide and oxygen-related defects. Finally, by using the wet pulse annealing process, we fabricated, on a plastic substrate, an ultrathin flexible a-IGZO TFT with good electrical and bending performances. PMID:27198067

  14. Periodically pulsed wet annealing approach for low-temperature processable amorphous InGaZnO thin film transistors with high electrical performance and ultrathin thickness

    NASA Astrophysics Data System (ADS)

    Kim, Ye Kyun; Ahn, Cheol Hyoun; Yun, Myeong Gu; Cho, Sung Woon; Kang, Won Jun; Cho, Hyung Koun

    2016-05-01

    In this paper, a simple and controllable “wet pulse annealing” technique for the fabrication of flexible amorphous InGaZnO thin film transistors (a-IGZO TFTs) processed at low temperature (150 °C) by using scalable vacuum deposition is proposed. This method entailed the quick injection of water vapor for 0.1 s and purge treatment in dry ambient in one cycle; the supply content of water vapor was simply controlled by the number of pulse repetitions. The electrical transport characteristics revealed a remarkable performance of the a-IGZO TFTs prepared at the maximum process temperature of 150 °C (field-effect mobility of 13.3 cm2 V‑1 s‑1 Ion/Ioff ratio ≈ 108 reduced I-V hysteresis), comparable to that of a-IGZO TFTs annealed at 350 °C in dry ambient. Upon analysis of the angle-resolved x-ray photoelectron spectroscopy, the good performance was attributed to the effective suppression of the formation of hydroxide and oxygen-related defects. Finally, by using the wet pulse annealing process, we fabricated, on a plastic substrate, an ultrathin flexible a-IGZO TFT with good electrical and bending performances.

  15. Investigation of variation of energy of laser beam on structural, electrical and optical properties of pulsed laser deposited CuO thin films

    SciTech Connect

    Dahiya, V. Kumar, A.; Kaur, G.; Mitra, A.

    2014-04-24

    In this paper, copper oxide (CuO) thin films have been deposited successfully by pulsed laser deposition technique using copper metal as target material. Thin films have been prepared under different energy of laser pulses ranging from 100mJ/pulse to 250 mJ/pulse. These films have been characterized for their structural, electrical and optical properties by using X-Ray Diffractometer (XRD), Four probe method and UV spectroscopy. Morphological and structural studies show that there is increase in crystallite size with the increase in energy of laser beam. Thus resulting in improved crystallinity and degree of orientation of the CuO thin films. Optoelectrical properties show direct relation between conductivity and energy of laser beam. Optical analysis of CuO thin films prepared under different energy of laser beam shows good agreement with structural analysis. The prepared CuO thin films show high absorbance in the UV and visible range and thus are suitable candidate for thin films solar cell application.

  16. Characterization of the electrical resistance of high temperature superconductor coated conductors at high currents using ultra-fast regulated current pulses

    NASA Astrophysics Data System (ADS)

    Sirois, Frédéric; Coulombe, Jonathan; Roy, François; Dutoit, Bertrand

    2010-03-01

    This paper focuses on the experimental determination of the electrical resistance (R) of commercial high temperature superconductor (HTS) coated conductors (CCs) at currents well above the critical current. The major novelty of this work rests on the unique experimental capability of applying constant current pulses in the sample (up to 1000 A) for durations as short as 15 µs, which allows very precise control of the amount of energy dissipated in the sample (the Joule effect), as well as the resulting temperature rise. By varying the applied current and the duration of the pulses, we show that we can achieve a relatively accurate characterization of R(I, T) simply from the measured dynamical V-I characteristics of the CCs. The resistance model obtained in this way is very important, as R(I, T) is the most fundamental design parameter in many practical HTS applications, especially in fault current limiters.

  17. Pulsed electric field processing of different fruit juices: impact of pH and temperature on inactivation of spoilage and pathogenic micro-organisms.

    PubMed

    Timmermans, R A H; Nierop Groot, M N; Nederhoff, A L; van Boekel, M A J S; Matser, A M; Mastwijk, H C

    2014-03-01

    Pulsed electrical field (PEF) technology can be used for the inactivation of micro-organisms and therefore for preservation of food products. It is a mild technology compared to thermal pasteurization because a lower temperature is used during processing, leading to a better retention of the quality. In this study, pathogenic and spoilage micro-organisms relevant in refrigerated fruit juices were studied to determine the impact of process parameters and juice composition on the effectiveness of the PEF process to inactivate the micro-organisms. Experiments were performed using a continuous-flow PEF system at an electrical field strength of 20 kV/cm with variable frequencies to evaluate the inactivation of Salmonella Panama, Escherichia coli, Listeria monocytogenes and Saccharomyces cerevisiae in apple, orange and watermelon juices. Kinetic data showed that under the same conditions, S. cerevisiae was the most sensitive micro-organism, followed by S. Panama and E. coli, which displayed comparable inactivation kinetics. L. monocytogenes was the most resistant micro-organism towards the treatment conditions tested. A synergistic effect between temperature and electric pulses was observed at inlet temperatures above 35 °C, hence less energy for inactivation was required at higher temperatures. Different juice matrices resulted in a different degree of inactivation, predominantly determined by pH. The survival curves were nonlinear and could satisfactorily be modeled with the Weibull model. PMID:24418831

  18. Photoconductive circuit element pulse generator

    DOEpatents

    Rauscher, Christen

    1989-01-01

    A pulse generator for characterizing semiconductor devices at millimeter wavelength frequencies where a photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test.

  19. Encoding of the amplitude modulation of pulsatile electrical stimulation in the feline cochlear nucleus by neurons in the inferior colliculus; effects of stimulus pulse rate

    NASA Astrophysics Data System (ADS)

    McCreery, Douglas; Han, Martin; Pikov, Victor; Yadav, Kamal; Pannu, Satinderpall

    2013-10-01

    Objectives. Persons without a functional auditory nerve cannot benefit from cochlear implants, but some hearing can be restored by an auditory brainstem implant (ABI) with stimulating electrodes implanted on the surface of the cochlear nucleus (CN). Most users benefit from their ABI, but speech recognition tends to be poorer than for users of cochlear implants. Psychophysical studies suggest that poor modulation detection may contribute to the limited performance of ABI users. In a cat model, we determined how the pulse rate of the electrical stimulus applied within or on the CN affects temporal and rate encoding of amplitude modulation (AM) by neurons in the central nucleus of the inferior colliculus (ICC). Approach. Stimulating microelectrodes were implanted chronically in and on the cats' CN, and multi-site recording microelectrodes were implanted chronically into the ICC. Encoding of AM pulse trains by neurons in the ICC was characterized as vector strength (VS), the synchrony of neural activity with the AM, and as the mean rate of neuronal action potentials (neuronal spike rate (NSR)). Main results. For intranuclear microstimulation, encoding of AM as VS was up to 3 dB greater when stimulus pulse rate was increased from 250 to 500 pps, but only for neuronal units with low best acoustic frequencies, and when the electrical stimulation was modulated at low frequencies (10-20 Hz). For stimulation on the surface of the CN, VS was similar at 250 and 500 pps, and the dynamic range of the VS was reduced for pulse rates greater than 250 pps. Modulation depth was encoded strongly as VS when the maximum stimulus amplitude was held constant across a range of modulation depth. This ‘constant maximum’ protocol allows enhancement of modulation depth while preserving overall dynamic range. However, modulation depth was not encoded as strongly as NSR. Significance. The findings have implications for improved sound processors for present and future ABIs. The performance of

  20. A frequency and pulse-width co-modulation strategy for transcutaneous neuromuscular electrical stimulation based on sEMG time-domain features

    NASA Astrophysics Data System (ADS)

    Zhou, Yu-Xuan; Wang, Hai-Peng; Bao, Xue-Liang; Lü, Xiao-Ying; Wang, Zhi-Gong

    2016-02-01

    Objective. Surface electromyography (sEMG) is often used as a control signal in neuromuscular electrical stimulation (NMES) systems to enhance the voluntary control and proprioceptive sensory feedback of paralyzed patients. Most sEMG-controlled NMES systems use the envelope of the sEMG signal to modulate the stimulation intensity (current amplitude or pulse width) with a constant frequency. The aims of this study were to develop a strategy that co-modulates frequency and pulse width based on features of the sEMG signal and to investigate the torque-reproduction performance and the level of fatigue resistance achieved with our strategy. Approach. We examined the relationships between wrist torque and two stimulation parameters (frequency and pulse width) and between wrist torque and two sEMG time-domain features (mean absolute value (MAV) and number of slope sign changes (NSS)) in eight healthy volunteers. By using wrist torque as an intermediate variable, customized and generalized transfer functions were constructed to convert the two features of the sEMG signal into the two stimulation parameters, thereby establishing a MAV/NSS dual-coding (MNDC) algorithm. Wrist torque reproduction performance was assessed by comparing the torque generated by the algorithms with that originally recorded during voluntary contractions. Muscle fatigue was assessed by measuring the decline percentage of the peak torque and by comparing the torque time integral of the response to test stimulation trains before and after fatigue sessions. Main Results. The MNDC approach could produce a wrist torque that closely matched the voluntary wrist torque. In addition, a smaller decay in the wrist torque was observed after the MNDC-coded fatigue stimulation was applied than after stimulation using pulse-width modulation alone. Significance. Compared with pulse-width modulation stimulation strategies that are based on sEMG detection, the MNDC strategy is more effective for both voluntary muscle

  1. Electric-pulse discharge as a novel technique to synthesize {beta}-SiC nano-crystallites from liquid-phase organic precursors

    SciTech Connect

    Du Kai; Yang Haibin Wei Ronghui; Li Minghui; Yu Qingjiang; Fu Wuyou; Yang Nan; Zhu Hongyang; Zeng Yi

    2008-01-08

    {beta}-SiC nano-crystallites have been prepared by electric pulses discharged in liquid-phase organic precursors. The composition and crystal structure of the products were characterized by X-ray diffraction, Raman spectroscopy, field emission scanning electronic and transmission electron microscopy. Transmission electron microscopy showed that the sample synthesized from the precursor (hexamethyl disilane) is composed of uniform grains with only 8 nm, while the one synthesize from the other precursor (dimethyl silicone oil) is of better crystalline structure with average grain size 22 nm, which may be attributed to discharge in liquid-phase source and short discharge intervals.

  2. Bipolar pulse generator for intense pulsed ion beam accelerator

    SciTech Connect

    Ito, H.; Igawa, K.; Kitamura, I.; Masugata, K.

    2007-01-15

    A new type of pulsed ion beam accelerator named ''bipolar pulse accelerator'' (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time.

  3. Bipolar pulse generator for intense pulsed ion beam accelerator.

    PubMed

    Ito, H; Igawa, K; Kitamura, I; Masugata, K

    2007-01-01

    A new type of pulsed ion beam accelerator named "bipolar pulse accelerator" (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time. PMID:17503918

  4. Technological characteristics and selected bioactive compounds of Opuntia dillenii cactus fruit juice following the impact of pulsed electric field pre-treatment.

    PubMed

    Moussa-Ayoub, Tamer E; Jaeger, Henry; Youssef, Khaled; Knorr, Dietrich; El-Samahy, Salah; Kroh, Lothar W; Rohn, Sascha

    2016-11-01

    Selected technological characteristics and bioactive compounds of juice pressed directly from the mash of whole Opuntia dillenii cactus fruits have been investigated. The impact of pulsed electric fields (PEF) for a non-thermal disintegration on the important juice characteristics has been evaluated in comparison to microwave heating and use of pectinases. Results showed that the cactus juice exhibited desirable technological characteristics. Besides, it also contained a high amount of phenolic compounds being the major contributors to the overall antioxidant activity of juice. HPLC-DAD/ESI-MS(n) measurements in the fruits' peel and pulp showed that isorhamnetin 3-O-rutinoside was determined as the single flavonol found only in the fruit's peel. Treating fruit mash with a moderate electric field strength increased juice yield and improved juice characteristics. Promisingly, the highest release of isorhamnetin 3-O-rutinoside from fruit's peel into juice was maximally achieved by PEF. PMID:27211645

  5. Electrical system for pulse-width modulated control of a power inverter using phase-shifted carrier signals and related operating methods

    DOEpatents

    Welchko, Brian A.

    2012-02-14

    Systems and methods are provided for pulse-width modulated control of power inverter using phase-shifted carrier signals. An electrical system comprises an energy source and a motor. The motor has a first set of windings and a second set of windings, which are electrically isolated from each other. An inverter module is coupled between the energy source and the motor and comprises a first set of phase legs coupled to the first set of windings and a second set of phase legs coupled to the second set of windings. A controller is coupled to the inverter module and is configured to achieve a desired power flow between the energy source and the motor by modulating the first set of phase legs using a first carrier signal and modulating the second set of phase legs using a second carrier signal. The second carrier signal is phase-shifted relative to the first carrier signal.

  6. Study of the electric-pulse-induced resistive switching effects at Pt/PrBa2Cu3Ox interfaces by multi-electrode method

    NASA Astrophysics Data System (ADS)

    Yue, Ruihong; Sun, Xianwen; Wei, Ling; Yin, Yanfeng; Yin, Jiangtao; Zhang, Weifeng

    2014-04-01

    Polycrystalline PrBa2Cu3Ox (PBCO) ceramic is prepared using the conventional solid-state reaction method and then Pt/PBCO/Pt plane structure device is fabricated. A reversible, non-volatile, and bipolar electric-pulse-induced resistance (EPIR) effect are found in the Pt/PBCO/Pt device. In order to determine the key role that controls the EPIR effect, the electrical properties of the Pt/PBCO interfaces and the temperature dependence of the PBCO bulk resistance are investigated by multi-electrode method. The results indicate that the EPIR effect is mainly induced and dominated by the Pt/PBCO interfaces, rather than the PBCO bulk. By analyzing the I-V characteristics of the contact interfaces, the carrier injection model is inferred to explain the EPIR effect.

  7. Development of a nanosecond pulsed HV atmospheric pressure plasma source: preliminary assessment of its electrical characteristics and degree of thermal nonequilibrium

    NASA Astrophysics Data System (ADS)

    Evans, M. D. G.; Sainct, F. P.; Aristizabal, F.; Bergthorson, J. M.; Coulombe, S.

    2015-06-01

    This paper discusses the development and characteristics of a distributed nanosecond-pulsed glow-like discharge plasma in air at atmospheric pressure. The produced pulse is of 6.4 kV with duration at half maximum of less than 80 ns, and an average pulse repetition frequency of 150 Hz. The discharge operates in air in a concentric electrode configuration. Spectroscopic studies are presented in order to assess the thermal characteristics of the plasma as well as its spatial characteristics. Electrical diagnostics are presented along with time averaged ICCD imaging of the radially distributed plasma. Although variations occur, it is found that the plasma has uniform vibrational and rotational temperatures across the inter electrode gap illustrating a high degree of disequilibrium in the plasma. Band head intensity analysis proves the existence of a negative glow in the near cathode region. Finally, the sensitivity of individual vibrational bands to vibrational and rotational temperatures is presented as a means to most accurately evaluate the uncertainty of spectrally determined temperatures.

  8. Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygen - iodine laser with a large active volume

    SciTech Connect

    Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N

    2010-08-03

    Possibilities for increasing the active medium volume of a chemical oxygen - iodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for CCOILs: low pressure of mixtures containing a strongly electronegative component, low voltage of discharge burning, low specific energy depositions, and long duration of the current pulse. An efficient electrode system is elaborated with the cathode based on an anisotropically-resistive material, which resulted in a stable discharge in the mixtures of iodide (CH{sub 3}I, n-C{sub 3}H{sub 7}I, C{sub 2}H{sub 5}I) with oxygen and nitrogen at the specific energy depositions of {approx}5 J L{sup -1}, pressures of 10 - 25 Torr, and mixture volume of 2.5 L. (lasers)

  9. The midbrain central gray best suppresses chronic pain with electrical stimulation at very low pulse rates in two human cases.

    PubMed

    Hentall, Ian D; Luca, Corneliu C; Widerstrom-Noga, Eva; Vitores, Alberto; Fisher, Letitia D; Martinez-Arizala, Alberto; Jagid, Jonathan R

    2016-02-01

    Deep brain stimulation in the midbrain׳s central gray can relieve neuropathic pain in man, but for unclear reasons sometimes fails intraoperatively or in early weeks. Here we describe continuous bilateral stimulation in the central gray of two subjects with longstanding, severe neuropathic pain from spinal cord injury. Stimulation parameters were recursively adjusted over many weeks to optimize analgesia while minimizing adverse effects. In early weeks, adjustments were made in periodic office visits; subjects later selected ad libitum at home among several blinded choices while rating pain twice daily. Both subjects received significantly better pain relief when stimulus pulse rates were low. The best relief occurred with 2 Hz cycled on for 1s and off for 2s. After inferior parameters were set, pain typically climbed slowly over 1-2 days; superior parameters led to both slow and fast improvements. Over many weeks of stimulation at low pulse rates, both subjects experienced significantly less interference from pain with sleep. One subject, with major pain relief, also showed less interference with social/recreational ability and mood; the other subject, despite minor pain relief, experienced a significantly positive global impression of change. Oscillopsia, the only observed complication of stimulation, disappeared at low mean pulse rates (≤ 3/s). These subjects׳ responses are not likely to be unique even if they are uncommon. Thus daily or more frequent pain assessment, combined with slower periodic adjustment of stimulation parameters that incorporate mean pulse rates about one per second, will likely improve success with this treatment. PMID:26711853

  10. Electrical resistivity change in Al:ZnO thin films dynamically deposited by bipolar pulsed direct-current sputtering and a remote plasma source

    SciTech Connect

    Yang, Wonkyun; Joo, Junghoon

    2010-07-15

    The Al-doped ZnO (AZO) thin films for a transparent conducting oxide in solar cell devices were deposited by bipolar pulsed dc magnetron sputtering. This work was performed in an in-line type system and investigated AZO films in a static deposition mode and dynamic one, which is more important in the practical fields. Because of this dynamic deposition process, the zigzagged columnar structure was observed. This resulted in the decreasing electrical property, optical properties, and surface roughness. As a deposition in the dynamic mode, the resistivity increased from 1.64x10{sup -3} to 2.50x10{sup -3} {Omega} cm, as compared to that in the static mode, and the transmittance also decreased from 83.9% to 78.3%. To recover the disadvantage, a remote plasma source (RPS) was supported between the substrate and target for reducing zigzagged formation during the deposition. The deposition rate decreased by using RPS, but the electrical and optical properties of films got better than only dynamic mode. The resistivity and transmittance in the dynamic mode using RPS were 2.1x10{sup -3} {Omega} cm and 85.5%, respectively. In this study, the authors found the possibility to advance the electrical and optical properties of AZO thin films in the industry mode.

  11. Application of Pulsed Electrical Fields for Advanced Cooling and Water Recovery in Coal-Fired Power Plant

    SciTech Connect

    Young Cho; Alexander Fridman

    2009-04-02

    The overall objective of the present work was to develop technologies to reduce freshwater consumption in a cooling tower of coal-based power plant so that one could significantly reduce the need of make-up water. The specific goal was to develop a scale prevention technology based an integrated system of physical water treatment (PWT) and a novel filtration method so that one could reduce the need for the water blowdown, which accounts approximately 30% of water loss in a cooling tower. The present study investigated if a pulsed spark discharge in water could be used to remove deposits from the filter membrane. The test setup included a circulating water loop and a pulsed power system. The present experiments used artificially hardened water with hardness of 1,000 mg/L of CaCO{sub 3} made from a mixture of calcium chloride (CaCl{sub 2}) and sodium carbonate (Na{sub 2}CO{sub 3}) in order to produce calcium carbonate deposits on the filter membrane. Spark discharge in water was found to produce strong shockwaves in water, and the efficiency of the spark discharge in cleaning filter surface was evaluated by measuring the pressure drop across the filter over time. Results showed that the pressure drop could be reduced to the value corresponding to the initial clean state and after that the filter could be maintained at the initial state almost indefinitely, confirming the validity of the present concept of pulsed spark discharge in water to clean dirty filter. The present study also investigated the effect of a plasma-assisted self-cleaning filter on the performance of physical water treatment (PWT) solenoid coil for the mitigation of mineral fouling in a concentric counterflow heat exchanger. The self-cleaning filter utilized shockwaves produced by pulse-spark discharges in water to continuously remove scale deposits from the surface of the filter, thus keeping the pressure drop across the filter at a relatively low value. Artificial hard water was used in the

  12. Comparison of a synergetic battery pack drive system to a pulse width modulated AC induction motor drive for an electric vehicle

    SciTech Connect

    Davis, A.; Salameh, Z.M.; Eaves, S.S.

    1999-06-01

    A new battery configuration technique and accompanying control circuitry, termed a Synergetic Battery Pack (SBP), is designed to work with Lithium batteries, and can be used as both an inverter for an electric vehicle AC induction motor drive and as a battery charger. In this paper, the performance of a Synergetic Battery Pack during motor drive operation is compared via computer simulation with a conventional motor drive which uses sinusoidal pulse width modulation (SPWM) to determine its effectiveness as a motor drive. The study showed that the drive efficiency was compatible with the conventional system, and offered a significant advantage in the lower frequency operating ranges. The voltage total harmonic distortion (THD) of the SBP was significantly lower than the PWM drive output, but the current THD was slightly higher due to the shape of the harmonic spectrum. In conclusion, the SBP is an effective alternative to a conventional drive, but the real advantage lies in its battery management capabilities and charger operation.

  13. Nonvolatile and tunable switching of lateral photo-voltage triggered by laser and electric pulse in metal dusted metal-oxide-semiconductor structures.

    PubMed

    Zhou, Peiqi; Gan, Zhikai; Huang, Xu; Mei, Chunlian; Huang, Meizhen; Xia, Yuxing; Wang, Hui

    2016-01-01

    Owing to the innate stabilization of built-in potential in p-n junction or metal-oxide-semiconductor structure, the sensitivity and linearity of most lateral photovoltaic effect (LPE) devices is always fixed after fabrication. Here we report a nonvolatile and tunable switching effect of lateral photo-voltage (LPV) in Cu dusted ultrathin metal-oxide-semiconductor structure. With the stimulation of electric pulse and local illumination, the sensitivity and linearity of LPV can be adjusted up and down in a nonvolatile manner. This phenomenon is attributed to a controllable change of the Schottky barrier formed between the metal layer and silicon substrate, including the consequent change of film resistivity. This work may widely improve the performance of existing LPE-based devices and suggest new applications for LPE in other areas. PMID:27535351

  14. Polarization from dielectric-barrier discharges in ferroelectrets: Mapping of the electric-field profiles by means of thermal-pulse tomography

    NASA Astrophysics Data System (ADS)

    Qiu, Xunlin; Holländer, Lars; Suárez, Rosaura Flores; Wirges, Werner; Gerhard, Reimund

    2010-08-01

    A polymer-ferroelectret system is fabricated by attaching two uniform polycarbonate films to a grid produced from double-sided adhesive tape by means of computer-controlled laser cutting. The openings of the grid structure result in well-defined voids inside the three-layer system, which can be internally charged through dielectric barrier discharges. The negatively charged internal void surfaces can be made visible by means of xerographical toner, and the electric-field distribution inside such ferroelectrets can be studied with thermal-pulse tomography. Both techniques exhibit polarization patterns that are consistent with the grid structure. Possible reasons for the observed non-uniform charge distributions are discussed.

  15. Nonvolatile and tunable switching of lateral photo-voltage triggered by laser and electric pulse in metal dusted metal-oxide-semiconductor structures

    PubMed Central

    Zhou, Peiqi; Gan, Zhikai; Huang, Xu; Mei, Chunlian; Huang, Meizhen; Xia, Yuxing; Wang, Hui

    2016-01-01

    Owing to the innate stabilization of built-in potential in p–n junction or metal-oxide-semiconductor structure, the sensitivity and linearity of most lateral photovoltaic effect (LPE) devices is always fixed after fabrication. Here we report a nonvolatile and tunable switching effect of lateral photo-voltage (LPV) in Cu dusted ultrathin metal-oxide-semiconductor structure. With the stimulation of electric pulse and local illumination, the sensitivity and linearity of LPV can be adjusted up and down in a nonvolatile manner. This phenomenon is attributed to a controllable change of the Schottky barrier formed between the metal layer and silicon substrate, including the consequent change of film resistivity. This work may widely improve the performance of existing LPE-based devices and suggest new applications for LPE in other areas. PMID:27535351

  16. Comparison of 2 methods of non-invasive treatment between transcutaneous electrical stimulation and pulsed electromagnetic field stimulation as replacement of invasive manual acupuncture.

    PubMed

    Kim, Soo-Byeong; Kim, Jung-Yoon; Park, Sun-Woo; Lee, Na-Ra; Lee, Seung-Wook; Kim, Young-Ho; Lee, Yong-Heum

    2012-01-01

    The aim of this study was to find the non-invasive optimal alternative method for Manual Acupuncture. Existing