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Sample records for pulsed electrically detected

  1. High Dynamic Range Electric Field Sensor for Electromagnetic Pulse Detection

    CERN Document Server

    Lin, Che-Yun; Lee, Beom Suk; Zhang, Xingyu; Chen, Ray T

    2014-01-01

    We design a high dynamic range electric field sensor based on domain inverted electro-optic (E-O) polymer Y-fed directional coupler for electromagnetic wave detection. This electrode-less, all optical, wideband electrical field sensor is fabricated using standard processing for E-O polymer photonic devices. Experimental results demonstrate effective detection of electric field from 16.7V/m to 750KV/m at a frequency of 1GHz, and spurious free measurement range of 70dB.

  2. Pulsed electric fields

    Science.gov (United States)

    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...

  3. Detection and removal of impurities in nitric oxide generated from air by pulsed electrical discharge.

    Science.gov (United States)

    Yu, Binglan; Blaesi, Aron H; Casey, Noel; Raykhtsaum, Grigory; Zazzeron, Luca; Jones, Rosemary; Morrese, Alexander; Dobrynin, Danil; Malhotra, Rajeev; Bloch, Donald B; Goldstein, Lee E; Zapol, Warren M

    2016-11-30

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation without dilating the systemic circulation. However, the current NO/N2 cylinder delivery system is cumbersome and expensive. We developed a lightweight, portable, and economical device to generate NO from air by pulsed electrical discharge. The objective of this study was to investigate and optimize the purity and safety of NO generated by this device. By using low temperature streamer discharges in the plasma generator, we produced therapeutic levels of NO with very low levels of nitrogen dioxide (NO2) and ozone. Despite the low temperature, spark generation eroded the surface of the electrodes, contaminating the gas stream with metal particles. During prolonged NO generation there was gradual loss of the iridium high-voltage tip (-90 μg/day) and the platinum-nickel ground electrode (-55 μg/day). Metal particles released from the electrodes were trapped by a high-efficiency particulate air (HEPA) filter. Quadrupole mass spectroscopy measurements of effluent gas during plasma NO generation showed that a single HEPA filter removed all of the metal particles. Mice were exposed to breathing 50 parts per million of electrically generated NO in air for 28 days with only a scavenger and no HEPA filter; the mice did not develop pulmonary inflammation or structural changes and iridium and platinum particles were not detected in the lungs of these mice. In conclusion, an electric plasma generator produced therapeutic levels of NO from air; scavenging and filtration effectively eliminated metallic impurities from the effluent gas. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Spin-dependent transport and recombination in solar cells studied by pulsed electrically detected magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Behrends, Jan

    2009-11-11

    This thesis deals with spin-dependent transport and recombination of charge carriers in solar cells. A systematic study on the influence of localized paramagnetic states which act as trapping and recombination centres for photogenerated charge carriers, is presented for three different types of solar cells. The central technique used in this thesis is electrically detected magnetic resonance (EDMR). The capabilities of pulsed (p) EDMR were extended with regard to the detection sensitivity. These improvements allowed pEDMR measurements on fully processed devices from cryogenic to room temperature. The instrumental upgrades also set the stage for pEDMR measurements at different resonance frequencies. In high-efficiency solar cells based on the heterojunction between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si), recombination via performancelimiting interface states could directly be measured electrically for the first time. The identification of these defects could be achieved by exploiting their orientation with regard to the surface. In thin-film solar cells based on hydrogenated microcrystalline silicon ({mu}-Si:H) the situation is more complex due to the heterogeneous and disordered structure of the material itself. In addition, these cells are multilayer-systems comprising three different silicon layers with different doping levels and microstructures. By combining a systematic alteration of the sample structure with the information extracted from deconvoluting spectrally overlapping signals in the time domain, it was possible to assign the spin-dependent signals to defects in the individual layers of the solar cells. Benefiting from the instrumental improvements, recombination via dangling bond states in silicon-based solar cells could be investigated by pEDMR at room temperature for the first time. In organic bulk heterojunction solar cells based on MEH-PPV and PCBM two different spin-dependent mechanisms coexist. Both processes

  5. Pulsed electrically detected magnetic resonance study of spin relaxation and recombination in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fehr, Matthias; Behrends, Jan; Schnegg, Alexander; Lips, Klaus; Rech, Bernd [Helmholtz-Zentrum Berlin, Silizium Photovoltaik, Berlin (Germany); Astakhov, Oleksander; Finger, Friedhelm [Forschungszentrum Juelich (Germany). IEF-5 Photovoltaik

    2009-07-01

    We have investigated the influence of paramagnetic states on electronic transport processes in thin-film pin solar cells with pulsed Electrically Detected Magnetic Resonance (pEDMR) at X-Band frequency and low temperature (10 K). The solar cells consist of an intrinsic microcrystalline absorber layer and amorphous or microcrystalline n/p contacting layers. In addition to the identification of the participating paramagnetic centres by their g-factors, pEDMR can be used to study the dynamics of the electronic processes in detail. We present measurements of modified EPR pulse sequences in order to identify the dominating relaxation mechanisms within correlated solid-state spin-pairs. By this technique a monitoring of the spin and charge motion is possible. In the outlook we present measurements of the electron spin echo envelope and critically discuss modulations in terms of dipolar coupling within the spin-pairs or hyperfine couplings to surrounding nuclei.

  6. Neurostimulation using subnanosecond electric pulses

    Science.gov (United States)

    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.

  7. Cryosurgery with pulsed electric fields.

    Science.gov (United States)

    Daniels, Charlotte S; Rubinsky, Boris

    2011-01-01

    This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

  8. Cryosurgery with pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Charlotte S Daniels

    Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused

  9. Cryosurgery with Pulsed Electric Fields

    Science.gov (United States)

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

    This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

  10. Pulsed plasmoid electric propulsion

    Science.gov (United States)

    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.

  11. Pulsed ELDOR detected NMR

    Science.gov (United States)

    Schosseler, P.; Wacker, Th.; Schweiger, A.

    1994-07-01

    A pulsed EPR method for the determination of small hyperfine interactions in disordered systems is described. A selective preparation pulse of frequency ω mw(1) excites allowed and forbidden transitions, thereby burning spectral holes into the EPR line. The positions of the holes caused by the excitation of forbidden transitions correspond to the nuclear transition frequencies of the spin system. A selective detection pulse of frequency ω mw(2) creates an FID with integrated intensity proportional to the magnetization at frequency ω mw(2). The entire hole pattern is obtained by recording the integrated intensity of the FID while varying the frequency difference Δω mw=ω mw(1)-ω mw(2) step by step.

  12. Neuromuscular disruption with ultrashort electrical pulses

    Science.gov (United States)

    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.

  13. Transport-related triplet states and hyperfine couplings in organic tandem solar cells probed by pulsed electrically detected magnetic resonance spectroscopy.

    Science.gov (United States)

    Kraffert, Felix; Bahro, Daniel; Meier, Christoph; Denne, Maximilian; Colsmann, Alexander; Behrends, Jan

    2017-09-01

    Tandem solar cells constitute the most successful organic photovoltaic devices with power conversion efficiencies comparable to thin-film silicon solar cells. Especially their high open-circuit voltage - only achievable by a well-adjusted layer stacking - leads to their high efficiencies. Nevertheless, the microscopic processes causing the lossless recombination of charge carriers within the recombination zone are not well understood yet. We show that advanced pulsed electrically detected magnetic resonance techniques such as electrically detected (ED)-Rabi nutation measurements and electrically detected hyperfine sublevel correlation (ED-HYSCORE) spectroscopy help to understand the role of triplet excitons in these microscopic processes. We investigate fully working miniaturised organic tandem solar cells and detect current-influencing doublet states in different layers as well as triplet excitons located on the fullerene-based acceptor. We apply ED-HYSCORE in order to study the nuclear spin environment of the relevant electron/hole spins and detect a significant amount of the low abundant (13)C nuclei coupled to the observer spins. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Transport-related triplet states and hyperfine couplings in organic tandem solar cells probed by pulsed electrically detected magnetic resonance spectroscopy

    Science.gov (United States)

    Kraffert, Felix; Bahro, Daniel; Meier, Christoph; Denne, Maximilian; Colsmann, Alexander; Behrends, Jan

    2017-09-01

    Tandem solar cells constitute the most successful organic photovoltaic devices with power conversion efficiencies comparable to thin-film silicon solar cells. Especially their high open-circuit voltage - only achievable by a well-adjusted layer stacking - leads to their high efficiencies. Nevertheless, the microscopic processes causing the lossless recombination of charge carriers within the recombination zone are not well understood yet. We show that advanced pulsed electrically detected magnetic resonance techniques such as electrically detected (ED)-Rabi nutation measurements and electrically detected hyperfine sublevel correlation (ED-HYSCORE) spectroscopy help to understand the role of triplet excitons in these microscopic processes. We investigate fully working miniaturised organic tandem solar cells and detect current-influencing doublet states in different layers as well as triplet excitons located on the fullerene-based acceptor. We apply ED-HYSCORE in order to study the nuclear spin environment of the relevant electron/hole spins and detect a significant amount of the low abundant 13C nuclei coupled to the observer spins.

  15. Pulsed electric field inactivation in a microreactor

    NARCIS (Netherlands)

    Fox, M.B.

    2006-01-01

    Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value ar

  16. Directed cell movement in pulsed electric fields.

    Science.gov (United States)

    Franke, K; Gruler, H

    1994-01-01

    Human granulocytes exposed to pulsed electric guiding fields were investigated. The trajectories were determined from digitized pictures (phase contrast). The basic results are: (i) No directed response was induced by pulsed electric guiding fields having a zero averaged field. (ii) A directed response was induced by pulsed electric guiding fields having a non-zero averaged field. (iii) The directed response was enhanced for pulse sequences having a repetition time of 8 s. (iv) The lag-time between signal recognition and cellular response was 8-10 s. The results are discussed in the framework of a self-ignition model.

  17. Pulsed electric field increases reproduction.

    Science.gov (United States)

    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.

  18. Critical electric field strengths of onion tissues treated by pulsed electric fields.

    Science.gov (United States)

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

    2010-09-01

    The impact of pulsed electric fields (PEF) on cellular integrity and texture of Ranchero and Sabroso onions (Allium cepa L.) was investigated. Electrical properties, ion leakage rate, texture, and amount of enzymatically formed pyruvate were measured before and after PEF treatment for a range of applied field strengths and number of pulses. Critical electric field strengths or thresholds (E(c)) necessary to initiate membrane rupture were different because dissimilar properties were measured. Measurement of electrical characteristics was the most sensitive method and was used to detect the early stage of plasma membrane breakdown, while pyruvate formation by the enzyme alliinase was used to identify tonoplast membrane breakdown. Our results for 100-μs pulses indicate that breakdown of the plasma membrane occurs above E(c)= 67 V/cm for 10 pulses, but breakdown of the tonoplast membrane is above either E(c)= 200 V/cm for 10 pulses or 133 V/cm for 100 pulses. This disparity in field strength suggests there may be 2 critical electrical field strengths: a lower field strength for plasma membrane breakdown and a higher field strength for tonoplast membrane breakdown. Both critical electric field strengths depended on the number of pulses applied. Application of a single pulse at an electric field up to 333 V/cm had no observable effect on any measured properties, while significant differences were observed for n≥10. The minimum electric field strength required to cause a measurable property change decreased with the number of pulses. The results also suggest that PEF treatment may be more efficient if a higher electric field strength is applied for a fewer pulses.

  19. Preliminary Studies on Pulsed Electric Field Breakdown of Lead Azide

    Science.gov (United States)

    1976-10-01

    1/2 OS CO ton NO. S3L TECHNICAL REPORT 4991 PRELIMINARY SUJDfES ON PULSED ELECTRIC FIELD BREAKDOWN OF LEAD AZIDE L AVRAMI M. BUMS D. DOWNS...Introduction Background A. Contact Effects B. Pulsed Electric Field Measurements Experimental A. Contact Effects B. Pulsed Electric Fields Discussion...B. Pulsed Electric Field Measurements The application of pulsed electric fields to lead azide does not exactly simulate the conditions experienced

  20. Pulsed light and pulsed electric field for foods and eggs.

    Science.gov (United States)

    Dunn, J

    1996-09-01

    Two new technologies for use in the food industry are described. The first method discussed uses intense pulse of light. This pulsed light (PureBright) process uses short duration flashes of broad spectrum "white" light to kill all exposed microorganisms, including vegetative bacteria, microbial and fungal spores, viruses, and protozoan oocysts. Each pulse, or flash, of light lasts only a few hundred millionths of a second (i.e., a few hundred microseconds). The intensity of each flash of light is about 20,000 times the intensity of sunlight at the earth's surface. The flashes are typically applied at a rate of about one to tens of flashes per second. For most applications, a few flashes applied in a fraction of a second provide an effective treatment. High microbial kill can be achieved, for example, on the surfaces of packaging materials, on packaging and processing equipment, foods, and medical devices as well as on many other surfaces. In addition, some bulk materials such as water and air that allow penetration of the light can be sterilized. The results of tests to measure the effects of pulsed light on Salmonella enteritiditis on eggs are presented. The second method discussed uses multiple, short duration, high intensity electric field pulses to kill vegetative microorganisms in pumpable products. This pulsed electric field (or CoolPure) process can be applied at modest temperatures at which no appreciable thermal damage occurs and the original taste, color, texture, and functionality of products can be retained.

  1. Schwinger Pair Production in Pulsed Electric Fields

    CERN Document Server

    Kim, Sang Pyo; Ruffini, Remo

    2012-01-01

    We numerically investigate the temporal behavior and the structure of longitudinal momentum spectrum and the field polarity effect on pair production in pulsed electric fields in scalar quantum electrodynamics (QED). Using the evolution operator expressed in terms of the particle and antiparticle operators, we find the exact quantum states under the influence of electric pulses and measure the number of pairs of the Minkowski particle and antiparticle. The number of pairs, depending on the configuration of electric pulses, exhibits rich structures in the longitudinal momentum spectrum and undergoes diverse dynamical behaviors at the onset of the interaction but always either converges to a momentum-dependent constant or oscillates around a momentum-dependent time average after the completion of fields.

  2. Safety of pulsed electric devices.

    Science.gov (United States)

    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.

  3. Pulsed electric field reduces the permeability of potato cell wall.

    Science.gov (United States)

    Galindo, Federico Gómez; Vernier, P Thomas; Dejmek, Petr; Vicente, António; Gundersen, Martin A

    2008-05-01

    The effect of the application of pulsed electric fields to potato tissue on the diffusion of the fluorescent dye FM1-43 through the cell wall was studied. Potato tissue was subjected to field strengths ranging from 30 to 500 V/cm, with one 1 ms rectangular pulse, before application of FM1-43 and microscopic examination. Our results show a slower diffusion of FM1-43 in the electropulsed tissue when compared with that in the non-pulsed tissue, suggesting that the electric field decreased the cell wall permeability. This is a fast response that is already detected within 30 s after the delivery of the electric field. This response was mimicked by exogenous H2O2 and blocked by sodium azide, an inhibitor of the production of H2O2 by peroxidases. (c) 2007 Wiley-Liss, Inc.

  4. Electrically detected ferromagnetic resonance

    NARCIS (Netherlands)

    Goennenwein, S.T.B.; Schink, S.W.; Brandlmaier, A.; Boger, A.; Opel, M.; Gross, R.; Keizer, R.S.; Klapwijk, T.M.; Gupta, A.; Huebl, H.; Bihler, C.; Brandt, M.S.

    2007-01-01

    We study the magnetoresistance properties of thin ferromagnetic CrO2 and Fe3O4 films under microwave irradiation. Both the sheet resistance ρ and the Hall voltage VHall characteristically change when a ferromagnetic resonance (FMR) occurs in the film. The electrically detected ferromagnetic resonanc

  5. Pulsed Electric Field treatment of packaged food

    NARCIS (Netherlands)

    Roodenburg, B.

    2011-01-01

    Food manufacturers are looking for new preservation techniques that don’t influence the fresh-like characteristics of products. Non-thermal pasteurisation of food with Pulsed Electric Fields (often referred to as PEF) is an emerging technology, where the change of the food is less than with thermal

  6. Biofouling prevention with pulsed electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Ghazala, A.; Schoenbach, K.H.

    2000-02-01

    Temporary immobilization of aquatic nuisance species through application of short electric pulses has been explored as a method to prevent biofouling in cooling water systems where untreated lake, river, or sea water is used. In laboratory experiments, electrical pulses with amplitudes on the order of kilovolts/centimeter and submicrosecond duration were found to be most effective in stunning time in a temporal range from minutes to hours. The temporary immobilization is assumed to be caused by reversible membrane breakdown. This assumption is supported by results of measurements of the energy required for stunning. Based on the data obtained in laboratory experiments, field experiments in a tidal water environment have been performed. The flow velocity was such that the residence time of the aquatic nuisance species in the system was approximately half a minute. The results showed that the pulsed electric field method provides full protection against biofouling when pulses of 0.77 {micro}s width and 6 kV/cm amplitude are applied to the water at the inlet of such a cooling water system. Even at amplitudes of 1 kV/cm, the protection is still in the 90% range, at an energy expenditure of 1 kWh for the treatment of 60,000 gallons of water.

  7. Plasma Membrane Permeabilization by Trains of Ultrashort Electric Pulses

    Science.gov (United States)

    2009-01-01

    REFERENCES 1. Beebe, S.J., et al., Nanosecond Pulsed Electric Field (nsPEF) Effects on Cells and Tissues: Apoptosis Induction and Tumor Growth Inhibition...nanosecond pulsed electric field Bioelectromagnetics, 2007. 28: p. 655-663. 13. Gowrishankar, T.R. and J.C. Weaver, Electrical behavior and pore... electric field (nsPEF). Bioelectromagnetics, 2007. 28: p. 655- 663. 19. Nuccitelli, R., et al., A new pulsed electric field therapy for melanoma disrupts

  8. Comparison of pulsed corona plasma and pulsed electric fields for the decontamination of water containing Legionella pneumophila as model organism.

    Science.gov (United States)

    Banaschik, Robert; Burchhardt, Gerhard; Zocher, Katja; Hammerschmidt, Sven; Kolb, Juergen F; Weltmann, Klaus-Dieter

    2016-12-01

    Pulsed corona plasma and pulsed electric fields were assessed for their capacity to kill Legionella pneumophila in water. Electrical parameters such as in particular dissipated energy were equal for both treatments. This was accomplished by changing the polarity of the applied high voltage pulses in a coaxial electrode geometry resulting in the generation of corona plasma or an electric field. For corona plasma, generated by high voltage pulses with peak voltages of +80kV, Legionella were completely killed, corresponding to a log-reduction of 5.4 (CFU/ml) after a treatment time of 12.5min. For the application of pulsed electric fields from peak voltages of -80kV a survival of log 2.54 (CFU/ml) was still detectable after this treatment time. Scanning electron microscopy images of L. pneumophila showed rupture of cells after plasma treatment. In contrast, the morphology of bacteria seems to be intact after application of pulsed electric fields. The more efficient killing for the same energy input observed for pulsed corona plasma is likely due to induced chemical processes and the generation of reactive species as indicated by the evolution of hydrogen peroxide. This suggests that the higher efficacy and efficiency of pulsed corona plasma is primarily associated with the combined effect of the applied electric fields and the promoted reaction chemistry.

  9. Pulsed electrical discharge in conductive solution

    Science.gov (United States)

    Panov, V. A.; Vasilyak, L. M.; Vetchinin, S. P.; Pecherkin, V. Ya; Son, E. E.

    2016-09-01

    Electrical discharge in a conductive solution of isopropyl alcohol in tap water (330 μ S cm-1) has been studied experimentally applying high voltage millisecond pulses (rise time  ˜0.4 μ \\text{s} , amplitude up to 15 kV, positive polarity) to a pin anode electrode. Dynamic current-voltage characteristics synchronized with high-speed images of the discharge were studied. The discharge was found to develop from high electric field region in the anode vicinity where initial conductive current with density  ˜100 A cm-2 results in fast heating and massive nucleation of vapor bubbles. Discharges in nucleated bubbles then produce a highly conductive plasma region and facilitate overheating instability development with subsequent formation of a thermally ionized plasma channel. The measured plasma channel propagation speed was 3-15 m s-1. A proposed thermal model of plasma channel development explains the low observed plasma channel propagation speed.

  10. Hemorrhage control by microsecond electrical pulses

    Science.gov (United States)

    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.

  11. Pulsed electric field assisted assembly of polyaniline

    Science.gov (United States)

    Kumar, Arun; Kazmer, David O.; Barry, Carol M. F.; Mead, Joey L.

    2012-08-01

    Assembling conducting polyaniline (PANi) on pre-patterned nano-structures by a high rate, commercially viable route offers an opportunity for manufacturing devices with nanoscale features. In this work we report for the first time the use of pulsed electric field to assist electrophoresis for the assembly of conducting polyaniline on gold nanowire interdigitated templates. This technique offers dynamic control over heat build-up, which has been a main drawback in the DC electrophoresis and AC dielectrophoresis as well as the main cause of nanowire template damage. The use of this technique allowed higher voltages to be applied, resulting in shorter assembly times (e.g., 17.4 s, assembly resolution of 100 nm). Moreover, the area coverage increases with the increase in number of pulses. A similar trend was observed with the deposition height and the increase in deposition height followed a linear trend with a correlation coefficient of 0.95. When the experimental mass deposited was compared with Hamaker’s theoretical model, the two were found to be very close. The pre-patterned templates with PANi deposition were subsequently used to transfer the nanoscale assembled PANi from the rigid templates to thermoplastic polyurethane using the thermoforming process.

  12. The effect of pulsed electric fields on carotenoids bioaccessibility

    NARCIS (Netherlands)

    Bot, Francesca; Verkerk, Ruud; Mastwijk, Hennie; Anese, Monica; Fogliano, Vincenzo; Capuano, Edoardo

    2018-01-01

    Tomato fractions were subjected to pulsed electric fields treatment combined or not with heating. Results showed that pulsed electric fields and heating applied in combination or individually induced permeabilization of cell membranes in the tomato fractions. However, no changes in β-carotene and

  13. Heredity of Aluminum Melt by Electric Pulse Modification (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    QI Jin-gang; WANG Jian-zhong; DU Hui-ling; CAO Li-yun

    2007-01-01

    Heredity of high pure aluminum melts under different pulse electric field was investigated by means of repetitious remelt experiment. The results indicate that the genetic coefficient by measurement of grain size of cast structure has a close relation with pulse voltage. Moreover, the hereditary law accords with the function of In=1+e-αn+β. The stability of genetic carrier (cluster) comprises in the competition between repetitious cooling and heating impulse and the effect of electric pulse modification.

  14. Electric field measurements in a nanosecond pulse discharge in atmospheric air

    Science.gov (United States)

    Simeni Simeni, Marien; Goldberg, Benjamin M.; Zhang, Cheng; Frederickson, Kraig; Lempert, Walter R.; Adamovich, Igor V.

    2017-05-01

    The paper presents the results of temporally and spatially resolved electric field measurements in a nanosecond pulse discharge in atmospheric air, sustained between a razor edge high-voltage electrode and a plane grounded electrode covered by a thin dielectric plate. The electric field is measured by picosecond four-wave mixing in a collinear phase-matching geometry, with time resolution of approximately 2 ns, using an absolute calibration provided by measurements of a known electrostatic electric field. The results demonstrate electric field offset on the discharge center plane before the discharge pulse due to surface charge accumulation on the dielectric from the weaker, opposite polarity pre-pulse. During the discharge pulse, the electric field follows the applied voltage until ‘forward’ breakdown occurs, after which the field in the plasma is significantly reduced due to charge separation. When the applied voltage is reduced, the field in the plasma reverses direction and increases again, until the weak ‘reverse’ breakdown occurs, producing a secondary transient reduction in the electric field. After the pulse, the field is gradually reduced on a microsecond time scale, likely due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Spatially resolved electric field measurements show that the discharge develops as a surface ionization wave. Significant surface charge accumulation on the dielectric surface is detected near the end of the discharge pulse. Spatially resolved measurements of electric field vector components demonstrate that the vertical electric field in the surface ionization wave peaks ahead of the horizontal electric field. Behind the wave, the vertical field remains low, near the detection limit, while the horizontal field is gradually reduced to near the detection limit at the discharge center plane. These results are consistent with time-resolved measurements of electric field

  15. High-frequency and brief-pulse stimulation pulses terminate cortical electrical stimulation-induced afterdischarges.

    Science.gov (United States)

    Ren, Zhi-Wei; Li, Yong-Jie; Yu, Tao; Ni, Duan-Yu; Zhang, Guo-Jun; Du, Wei; Piao, Yuan-Yuan; Zhou, Xiao-Xia

    2017-06-01

    Brief-pulse stimulation at 50 Hz has been shown to terminate afterdischarges observed in epilepsy patients. However, the optimal pulse stimulation parameters for terminating cortical electrical stimulation-induced afterdischarges remain unclear. In the present study, we examined the effects of different brief-pulse stimulation frequencies (5, 50 and 100 Hz) on cortical electrical stimulation-induced afterdischarges in 10 patients with refractory epilepsy. Results demonstrated that brief-pulse stimulation could terminate cortical electrical stimulation-induced afterdischarges in refractory epilepsy patients. In conclusion, (1) a brief-pulse stimulation was more effective when the afterdischarge did not extend to the surrounding brain area. (2) A higher brief-pulse stimulation frequency (especially 100 Hz) was more likely to terminate an afterdischarge. (3) A low current intensity of brief-pulse stimulation was more likely to terminate an afterdischarge.

  16. [Mechanism of ablation with nanosecond pulsed electric field].

    Science.gov (United States)

    Cen, Chao; Chen, Xin-hua; Zheng, Shu-sen

    2015-11-01

    Nanosecond pulsed electric field ablation has been widely applied in clinical cancer treatment, while its molecular mechanism is still unclear. Researchers have revealed that nanosecond pulsed electric field generates nanopores in plasma membrane, leading to a rapid influx of Ca²⁺; it has specific effect on intracellular organelle membranes, resulting in endoplasmic reticulum injuries and mitochondrial membrane potential changes. In addition, it may also change cellular morphology through damage of cytoskeleton. This article reviews the recent research advances on the molecular mechanism of cell membrane and organelle changes induced by nanosecond pulsed electric field ablation.

  17. Electrical load detection aparatus

    DEFF Research Database (Denmark)

    2010-01-01

    A load detection technique for a load comprising multiple frequency-dependant sub-loads comprises measuring a representation of the impedance characteristic of the load; providing stored representations of a multiplicity of impedance characteristics of the load; each one of the stored representat...

  18. Detection and characterization of pulses in broadband seismometers

    Science.gov (United States)

    Wilson, David; Ringler, Adam; Hutt, Charles R.

    2017-01-01

    Pulsing - caused either by mechanical or electrical glitches, or by microtilt local to a seismometer - can significantly compromise the long‐period noise performance of broadband seismometers. High‐fidelity long‐period recordings are needed for accurate calculation of quantities such as moment tensors, fault‐slip models, and normal‐mode measurements. Such pulses have long been recognized in accelerometers, and methods have been developed to correct these acceleration steps, but considerable work remains to be done in order to detect and correct similar pulses in broadband seismic data. We present a method for detecting and characterizing the pulses using data from a range of broadband sensor types installed in the Global Seismographic Network. The technique relies on accurate instrument response removal and employs a moving‐window approach looking for acceleration baseline shifts. We find that pulses are present at varying levels in all sensor types studied. Pulse‐detection results compared with average daily station noise values are consistent with predicted noise levels of acceleration steps. This indicates that we can calculate maximum pulse amplitude allowed per time window that would be acceptable without compromising long‐period data analysis.

  19. Orientation of the agarose gel matrix in pulsed electric fields.

    OpenAIRE

    Stellwagen, J; Stellwagen, N C

    1989-01-01

    The technique of transient electric birefringence was used to investigate the effect of pulsed electric fields on the orientation of the agarose gel matrix. Orientation of the gel was observed at all electric field strengths. Very slow, time-dependent effects were observed when pulses of 10-100 V/cm were applied to 1% gels for 0.5-2 seconds, indicating that domains of the matrix were being oriented by the electric field. The sign of the birefringence reversed when the direction of the applied...

  20. Model of Pulsed Electrical Discharge Machining (EDM using RL Circuit

    Directory of Open Access Journals (Sweden)

    Ade Erawan Bin Minhat

    2014-10-01

    Full Text Available This article presents a model of pulsed Electrical Discharge Machining (EDM using RL circuit. There are several mathematical models have been successfully developed based on the initial, ignition and discharge phase of current and voltage gap. According to these models, the circuit schematic of transistor pulse power generator has been designed using electrical model in Matlab Simulink software to identify the profile of voltage and current during machining process. Then, the simulation results are compared with the experimental results.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  3. Pulsed electrical discharges for medicine and biology techniques, processes, applications

    CERN Document Server

    Kolikov, Victor

    2015-01-01

    This book presents the application of pulsed electrical discharges in water and water dispersions of metal nanoparticles in medicine (surgery, dentistry, and oncology), biology, and ecology. The intensive electrical and shock waves represent a novel technique to destroy viruses and this way to  prepare anti-virus vaccines. The method of pulsed electrical discharges in water allows to decontaminate water from almost all known bacteria and spores of fungi being present in human beings. The nanoparticles used are not genotoxic and mutagenic. This book is useful for researchers and graduate students.

  4. Review of the Dynamics of Coalescence and Demulsification by High-Voltage Pulsed Electric Fields

    OpenAIRE

    Ye Peng; Tao Liu; Haifeng Gong; Xianming Zhang

    2016-01-01

    The coalescence of droplets in oil can be implemented rapidly by high-voltage pulse electric field, which is an effective demulsification dehydration technological method. At present, it is widely believed that the main reason of pulse electric field promoting droplets coalescence is the dipole coalescence and oscillation coalescence in pulse electric field, and the optimal coalescence pulse electric field parameters exist. Around the above content, the dynamics of high-voltage pulse electric...

  5. Equivalent Resistance in Pulse Electric Current Sintering

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The sintering resistance for conductive TiB2 and non-conductive Al2O3 as well as empty die during pulse current sintering were investigated in this paper.Equivalent resistances were measured by current and valtage during sintering the conductive and non-conductive materials in the same conditions.It is found that the current paths for conductive are different from those for non-conductive materials.For non-conductive materials,sintering resistances are influenced by powder sizes and heating rates,which indicates that pulse current has some interaction with non-conductive powders.For conductive TiB2,sintering resistances are influenced by heating rates and ball-milling time,which indicates the effect of powders activated by spark.

  6. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    Science.gov (United States)

    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.

  7. Numerical Simulation of Nanosecond-Pulse Electrical Discharges

    Science.gov (United States)

    2012-01-01

    were rst investigated.1,2 Activity in the research area waned in the 1970s, with some work on drag reduction using corona discharges appearing in...Aleksandrov et al.38 suggest that in nanosecond pulse discharges at atmospheric pressure at very high values of the reduced electric eld, E=N 1000 Td... atmospheric pressure is of the order of 100 m, which corresponds to an acoustic time of acoustic 0:3 s. Thus, nanosecond-pulse discharge energy

  8. Effects of pulsed electric field on ULQ and RFP plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, M. [Iwate Univ., Morioka (Japan). Faculty of Engineering; Saito, K.; Suzuki, T. [and others

    1997-12-31

    Dynamo activity and self-organization processes are investigated using the application of pulsed poloidal and toroidal electric fields on ULQ and RFP plasmas. Synchronized to the application of the pulsed electric fields, the remarkable responses of the several plasma parameters are observed. The plasma has a preferential magnetic field structure, and the external perturbation activates fluctuation to maintain the structure through dynamo effect. This process changes the total dissipation with the variation of magnetic helicity in the system, showing that self organization accompanies an enhanced dissipation. (author)

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

    Science.gov (United States)

    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.

  10. Electric pulse-mediated gene delivery to various animal tissues

    DEFF Research Database (Denmark)

    Mir, Lluis M; Moller, Pernille H; André, Franck

    2005-01-01

    Electroporation designates the use of electric pulses to transiently permeabilize the cell membrane. It has been shown that DNA can be transferred to cells through a combined effect of electric pulses causing (1) permeabilization of the cell membrane and (2) an electrophoretic effect on DNA...... therapy, termed electrogenetherapy (EGT as well). By transfecting cells with a long lifetime, such as muscle fibers, a very long-term expression of genes can be obtained. A great variety of tissues have been transfected successfully, from muscle as the most extensively used, to both soft (e.g., spleen...

  11. Electric breakdown during the pulsed current spreading in the sand

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyak, L. M., E-mail: vasilyak@ihed.ras.ru; Vetchinin, S. P.; Panov, V. A.; Pecherkin, V. Ya.; Son, E. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2016-03-15

    Processes of spreading of the pulsed current from spherical electrodes and an electric breakdown in the quartz sand are studied experimentally. When the current density on the electrode exceeds the critical value, a nonlinear reduction occurs in the grounding resistance as a result of sparking in the soil. The critical electric field strengths for ionization and breakdown are determined. The ionization-overheating instability is shown to develop on the electrode, which leads to the current contraction and formation of plasma channels.

  12. Generation of short electrical pulses based on bipolar transistorsny

    Directory of Open Access Journals (Sweden)

    M. Gerding

    2004-01-01

    Full Text Available A system for the generation of short electrical pulses based on the minority carrier charge storage and the step recovery effect of bipolar transistors is presented. Electrical pulses of about 90 ps up to 800 ps duration are generated with a maximum amplitude of approximately 7V at 50Ω. The bipolar transistor is driven into saturation and the base-collector and base-emitter junctions become forward biased. The resulting fast switch-off edge of the transistor’s output signal is the basis for the pulse generation. The fast switching of the transistor occurs as a result of the minority carriers that have been injected and stored across the base-collector junction under forward bias conditions. If the saturated transistor is suddenly reverse biased the pn-junction will appear as a low impedance until the stored charge is depleted. Then the impedance will suddenly increase to its normal high value and the flow of current through the junction will turn to zero, abruptly. A differentiation of the output signal of the transistor results in two short pulses with opposite polarities. The differentiating circuit is implemented by a transmission line network, which mainly acts as a high pass filter. Both the transistor technology (pnp or npn and the phase of the transfer function of the differentating circuit influence the polarity of the output pulses. The pulse duration depends on the transistor parameters as well as on the transfer function of the pulse shaping network. This way of generating short electrical pulses is a new alternative for conventional comb generators based on steprecovery diodes (SRD. Due to the three-terminal structure of the transistor the isolation problem between the input and the output signal of the transistor network is drastically simplified. Furthermore the transistor is an active element in contrast to a SRD, so that its current gain can be used to minimize the power of the driving signal.

  13. Nanosecond pulsed electric field ablation of hepatocellular carcinoma.

    Science.gov (United States)

    Beebe, Stephen J; Chen, Xinhua; Liu, Jie A; Schoenbach, Karl H

    2011-01-01

    Hepatocellular carcinoma often evades effective therapy and recurrences are frequent. Recently, nanosecond pulsed electric field (nsPEF) ablation using pulse power technology has emerged as a local-regional, non-thermal, and non-drug therapy for skin cancers. In the studies reported here we use nsPEFs to ablate murine, rat and human HCCs in vitro and an ectopic murine Hepa 1-6 HCC in vivo. Using pulses with 60 or 300 ns and electric fields as high as 60 kV/cm, murine Hepa 1-6, rat N1S1 and human HepG2 HCC are readily eliminated with changes in caspase-3 activity. Interestingly caspase activities increase in the mouse and human model and decrease in the rat model as electric field strengths are increased. In vivo, while sham treated control mice survived an average of 15 days after injection and before humane euthanasia, Hepa 1-6 tumors were eliminated for longer than 50 days with 3 treatments using one hundred pulses with 100 ns at 55 kV/cm. Survival was 40% in mice treated with 30 ns pulses at 55 kV/cm. This study demonstrates that nsPEF ablation is not limited to effectively treating skin cancers and provides a rationale for treating orthotopic hepatocellular carcinoma in pre-clinical applications and ultimately in clinical trials.

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

    Science.gov (United States)

    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...

  15. Pulsed electric field processing for fruit and vegetables

    Science.gov (United States)

    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...

  16. Heredity of Aluminum Melt Caused by Electric Pulse Modification (Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-zhong; QI Jin-gang; DU Hui-ling; ZHANG Zhen-bin

    2007-01-01

    The heredity of aluminum melt under the action of pulse electric field was investigated by means of the remelt experiment. A new hereditary criterion under this condition was proposed; in the meantime, the differential transferability of genetic carrier in activated melt among filial generations was validated with the aid of DSC.

  17. Production of pulsed electric fields using capacitively coupled electrodes

    Science.gov (United States)

    Kendall, B. R. F.; Schwab, F. A. S.

    1980-01-01

    It is shown that pulsed electric fields can be produced over extended volumes by taking advantage of the internal capacitances in a stacked array of electrodes. The design, construction, and performance of practical arrays are discussed. The prototype arrays involved fields of 100-1000 V/cm extending over several centimeters. Scaling to larger physical dimensions is straightforward.

  18. Pulsed electric fields (PEF applications on wine production: A review

    Directory of Open Access Journals (Sweden)

    Ozturk Burcu

    2017-01-01

    Full Text Available Novel techniques have been searched in the last decades as a result of increasing demand for high quality food products. Non-thermal processing technologies, such as pulsed electric fields (PEF have been improved to achieve inhibition of deleterious effects on quality-related compounds. The working principle of PEF is based on the application of pulses of high voltage (typically above 20 kV/cm up to 70 kV/cm to liquid foods placed between two electrodes. Pulsed electric fields technique has also been studied in winemaking process. Certain positive influences of PEF on vinification have been reported as elimination of pathogenic microorganisms, reduction of maceration time, increase in phenolic compounds extraction , acceleration of wine aging and inactivation of oxidative enzymes. The aim of this review is to summarize the potential applications of PEF in winemaking and to express its effects on quality of wine.

  19. Velocity-selected molecular pulses produced by an electric guide

    CERN Document Server

    Sommer, Christian; Chervenkov, Sotir; van Buuren, Laurens D; Zeppenfeld, Martin; Pinkse, Pepijn W H; Rempe, Gerhard

    2010-01-01

    Electrostatic velocity filtering is a technique for the production of continuous guided beams of slow polar molecules from a thermal gas. We extended this technique to produce pulses of slow molecules with a narrow velocity distribution around a tunable velocity. The pulses are generated by sequentially switching the voltages on adjacent segments of an electric quadrupole guide synchronously with the molecules propagating at the desired velocity. This technique is demonstrated for deuterated ammonia (ND$_{3}$), delivering pulses with a velocity in the range of $20-100\\,\\rm{m/s}$ and a relative velocity spread of $(16\\pm 2)\\,%$ at FWHM. At velocities around $60\\,\\rm{m/s}$, the pulses contain up to $10^6$ molecules each. The data are well reproduced by Monte-Carlo simulations, which provide useful insight into the mechanisms of velocity selection.

  20. Dielectric Fluid in Inhomogeneous Pulsed Electric Field

    CERN Document Server

    Shneider, M N

    2013-01-01

    We consider the dynamics of a compressible fluid under the influence of electrostrictive ponderomotive forces in strong inhomogeneous nonstationary electric fields. It is shown that if the fronts of the voltage rise at a sharp, needle-like electrode are rather steep (less than or about nanoseconds), and the region of negative pressure arises, which can reach values at which the fluid loses its continuity with the formation of cavitation ruptures. If the voltage on the electrode is not large enough or the front is flatter, the cavitation in the liquid does not occur. However, a sudden shutdown of the field results in a reverse flow of liquid from the electrode, which leads to appearance of negative pressure, and, possibly, cavitation.

  1. Detection and visualization to Doppler sensitive sonar pulses

    NARCIS (Netherlands)

    Bertrand, D.B.; IJsselmuide, S.P. van; Beerens, S.P.

    2006-01-01

    In anti-submarine warfare, the use of Doppler sensitive sonar pulses is common practice. In particular, the wideband Doppler sensitive PTFM pulse (Pulse Train Frequency Modulation) is a powerful tool for detection in reverberation limited conditions. Nevertheless, this pulse is not operationally

  2. Development of a linear piston-type pulse power electric generator for powering electric guns

    Science.gov (United States)

    Summerfield, Martin

    1993-01-01

    The development of a linear piston-type electric pulse-power generator capable of powering electric guns and EM (rail and coil) guns and ET guns, presently under development, is discussed. The pulse-power generator consists of a cylindrical armature pushed by gases from the combustion of fuel or propellant through an externally produced magnetic field. An arrangement of electrodes and connecting straps serves to extract current from the moving armature and to send it to an external load (the electric gun).

  3. Pulse-driven magnetoimpedance sensor detection of cardiac magnetic activity.

    Directory of Open Access Journals (Sweden)

    Shinsuke Nakayama

    Full Text Available This study sought to establish a convenient method for detecting biomagnetic activity in the heart. Electrical activity of the heart simultaneously induces a magnetic field. Detection of this magnetic activity will enable non-contact, noninvasive evaluation to be made. We improved the sensitivity of a pulse-driven magnetoimpedance (PMI sensor, which is used as an electric compass in mobile phones and as a motion sensor of the operation handle in computer games, toward a pico-Tesla (pT level, and measured magnetic fields on the surface of the thoracic wall in humans. The changes in magnetic field detected by this sensor synchronized with the electric activity of the electrocardiogram (ECG. The shape of the magnetic wave was largely altered by shifting the sensor position within 20 mm in parallel and/or perpendicular to the thoracic wall. The magnetic activity was maximal in the 4th intercostals near the center of the sterna. Furthermore, averaging the magnetic activity at 15 mm in the distance between the thoracic wall and the sensor demonstrated magnetic waves mimicking the P wave and QRS complex. The present study shows the application of PMI sensor in detecting cardiac magnetic activity in several healthy subjects, and suggests future applications of this technology in medicine and biology.

  4. Pulse-driven magnetoimpedance sensor detection of cardiac magnetic activity.

    Science.gov (United States)

    Nakayama, Shinsuke; Sawamura, Kenta; Mohri, Kaneo; Uchiyama, Tsuyoshi

    2011-01-01

    This study sought to establish a convenient method for detecting biomagnetic activity in the heart. Electrical activity of the heart simultaneously induces a magnetic field. Detection of this magnetic activity will enable non-contact, noninvasive evaluation to be made. We improved the sensitivity of a pulse-driven magnetoimpedance (PMI) sensor, which is used as an electric compass in mobile phones and as a motion sensor of the operation handle in computer games, toward a pico-Tesla (pT) level, and measured magnetic fields on the surface of the thoracic wall in humans. The changes in magnetic field detected by this sensor synchronized with the electric activity of the electrocardiogram (ECG). The shape of the magnetic wave was largely altered by shifting the sensor position within 20 mm in parallel and/or perpendicular to the thoracic wall. The magnetic activity was maximal in the 4th intercostals near the center of the sterna. Furthermore, averaging the magnetic activity at 15 mm in the distance between the thoracic wall and the sensor demonstrated magnetic waves mimicking the P wave and QRS complex. The present study shows the application of PMI sensor in detecting cardiac magnetic activity in several healthy subjects, and suggests future applications of this technology in medicine and biology.

  5. Nanosecond electric pulses modulate skeletal muscle calcium dynamics and contraction

    Science.gov (United States)

    Valdez, Chris; Jirjis, Michael B.; Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.

    2017-02-01

    Irreversible electroporation therapy is utilized to remove cancerous tissues thru the delivery of rapid (250Hz) and high voltage (V) (1,500V/cm) electric pulses across microsecond durations. Clinical research demonstrated that bipolar (BP) high voltage microsecond pulses opposed to monophasic waveforms relieve muscle contraction during electroporation treatment. Our group along with others discovered that nanosecond electric pulses (nsEP) can activate second messenger cascades, induce cytoskeletal rearrangement, and depending on the nsEP duration and frequency, initiate apoptotic pathways. Of high interest across in vivo and in vitro applications, is how nsEP affects muscle physiology, and if nuances exist in comparison to longer duration electroporation applications. To this end, we exposed mature skeletal muscle cells to monopolar (MP) and BP nsEP stimulation across a wide range of electric field amplitudes (1-20 kV/cm). From live confocal microscopy, we simultaneously monitored intracellular calcium dynamics along with nsEP-induced muscle movement on a single cell level. In addition, we also evaluated membrane permeability with Yo-PRO-1 and Propidium Iodide (PI) across various nsEP parameters. The results from our findings suggest that skeletal muscle calcium dynamics, and nsEP-induced contraction exhibit exclusive responses to both MP and BP nsEP exposure. Overall the results suggest in vivo nsEP application may elicit unique physiology and field applications compared to longer pulse duration electroporation.

  6. Triggering and guiding electric discharge by a train of UV picosecond pulses combined with a long UV pulse

    CERN Document Server

    Ionin, A A; Levchenko, A O; Seleznev, L V; Shutov, A V; Sinitsyn, D V; Smetanin, I V; Ustinovsky, N N; Zvorykin, V D

    2012-01-01

    Non-self-sustained electric discharge and electric breakdown were triggered and guided by a train of picosecond UV pulses overlapped with a long free-running UV pulse of a hybrid Ti:Sapphire-KrF laser facility. Photocurrent sustained by this train is two orders of magnitude higher, and electric breakdown distance is twice longer than those for the discharge triggered by the long UV pulse only.

  7. Electrical detection of hyperfine interactions in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, Felix

    2012-12-15

    The main focus of this work was the measurement of hyperfine interactions of defects in silicon using EDMR. We combined the high sensitivity of EDMR when compared to conventional ESR with the two most commonly used methods for the measurement of hyperfine interactions: ESEEM and ENDOR. We first demonstrated the electrical detection of ESEEM by measuring the hyperfine interactions of {sup 31}P donors in Si:P with {sup 29}Si nuclear spins. We then apply EDESEEM to P{sub b0} defects at the Si/SiO{sub 2} interface. In isotopically engineered, we observe an ESEEM modulation with a characteristic beating caused by {sup 29}Si nuclei at 4th and 5th nearest neighbor lattice sites. Then we combine pulsed ENDOR with the high sensitivity of EDMR (EDENDOR). First we demonstrate the measurement of {sup 31}P nuclear spin hyperfine transitions and the coherent manipulation and readout of the {sup 31}P nuclear spins under continuous illumination with above bandgap light. We further show that the EDENDOR method can be greatly improved by switching off the illumination during the microwave and rf pulses. This improves the signal-to-noise ratio by two orders of magnitude and removes the non-resonant background induced by the strong rf pulse allowing to measure ENDOR with a sensitivity <3000 nuclear spins. We apply EDENDOR to the {sup 31}P-P{sub b0} spin system and the {sup 31}P-SL1 spin system allowing us to compare the hyperfine interactions of bulk and interface-near donors. The pulsed illumination also makes spectroscopy of the {sup 31}P{sup +} nuclear spin possible, which due to its long coherence time of 18 ms compared to 280 {mu}s for the {sup 31}P{sub 0} nuclear spin, might be a candidate for a nuclear spin memory. In the last part, we devise a scheme for the hyperpolarization of {sup 31}P nuclei by combining pulsed optical excitation and pulsed ENDOR and demonstrate a {sup 31}P nuclear spin polarization of more than 50%. Crucial for these experiments was the development of a

  8. Effects of pulsed electrical field processing on microbial survival, quality change and nutritional characteristics of blueberries

    Science.gov (United States)

    Whole fresh blueberries were treated using a parallel pulsed electric field (PEF) treatment chamber and a sanitizer solution (60 ppm peracetic acid [PAA]) as PEF treatment medium with square wave bipolar pulses at 2 kV/cm electric field strength, 1us pulse width, and 100 pulses per second for 2, 4, ...

  9. The role of nanosecond electric pulse-induced mechanical stress in cellular nanoporation

    Science.gov (United States)

    Roth, Caleb C.

    , fluorescent confocal microscopy, microarray analysis and or real time polymerase chain reaction. To investigate the physical interaction(s) of the electrical pulse with the aqueous environment, optical techniques such as pump-probe imaging, schlieren imaging, and probe beam deflection were used. Finally, electrochemistry was employed to modify the electrical parameters of the exposures such that different biophysical phenomena could be detected. Results: Approximately 500 genes were selectively up-regulated in each of the assayed cells. Validation of the microarray data indicated genes such as the putative transforming gene of avian sarcoma virus 17, commonly known as jun proto-oncogene, and the Finkel--Biskis--Jinkins murine osteosarcoma viral oncogene homolog were significantly up-regulated in response to the exposure. Many of the genes selectively up-regulated in each cell type are biomarkers of mechanical stress. Proteomic analysis indicated proteins responsible for mitigation of reactive oxygen species were produced in response to nanosecond electrical pulse exposure. Analysis using the Probe Beam Deflection Technique identified the generation of an acoustic pressure transient emanating from the electrodes immediately after the application of the pulse. This acoustic pressure transient traveled at approximately 1500 meters per second, had a frequency bandwidth of 2.5 megahertz and was capable of delivering 13 kilopascals of pressure at 5 millimeters distance from the generating electrodes. Visual confirmation of the acoustic pressure transients was accomplished using pump-probe, schlieren and ultrasonic imaging techniques. Modification of the bathing media in which the cells were exposed indicated that acoustic pressure transient formation was directly dependent on the amount of electrical current induced by the exposure. Confocal microscopy revealed that, in the absence of the acoustic pressure transients, nanoporation, as detected by a green fluorescent carbocyanine

  10. Spatial characterization of electric potentials generated by pulsed microelectrode arrays.

    Science.gov (United States)

    Kandagor, V; Cela, C J; Sanders, C A; Greenbaum, E; Lazzi, G; Humayun, M S; Zhou, D M; Castro, R; Gaikwad, S; Little, J

    2010-01-01

    This presentation is a report on the in situ characterization of stimulating microelectrodes in the context of multielectrode retinal prosthetic implants. The experimental system approximately replicates the geometric and electrical parameters of Second Sight Medical Products' Argus II Retinal Implant. Topographic maps of electric potentials have been prepared for a 60 electrode structure in which selected electrodes were stimulated with biphasic repetitively pulsed charge densities at 100 microC·cm(-2). Surface contour maps were prepared using a 10 microm diameter recording electrode.

  11. Pulsed high voltage electric discharge disinfection of microbially contaminated liquids.

    Science.gov (United States)

    Anpilov, A M; Barkhudarov, E M; Christofi, N; Kop'ev, V A; Kossyi, I A; Taktakishvili, M I; Zadiraka, Y

    2002-01-01

    To examine the use of a novel multielectrode slipping surface discharge (SSD) treatment system, capable of pulsed plasma discharge directly in water, in killing micro-organisms. Potable water containing Escherichia coli and somatic coliphages was treated with pulsed electric discharges generated by the SSD. The SSD system was highly efficient in the microbial disinfection of water with a low energy utilization (eta approximately 10-4 kW h l-1). The SSD treatment was effective in the destruction of E. coli and its coliphages through the generation of u.v. radiation, ozone and free radicals. The non-thermal treatment method can be used for the eradication of micro-organisms in a range of contaminated liquids, including milk, negating the use of pasteurization. The method utilizes multipoint electric discharges capable of treating large volumes of liquid under static and flowing regimes.

  12. Nanosecond electric pulses trigger actin responses in plant cells.

    Science.gov (United States)

    Berghöfer, 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.

  13. Acoustic vibration test detects intermittent electrical discontinuities

    Science.gov (United States)

    Grieve, S. M.; Roberts, D. E.

    1970-01-01

    Nondestructive test method detects faulty electrical connections in inaccessible or hidden portions of electronic harness assemblies and connectors. Method employs readily available commercial equipment.

  14. Pulsed electrical discharge in gas bubbles in water

    Science.gov (United States)

    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

  15. Nanoparticle mechanics: deformation detection via nanopore resistive pulse sensing

    Science.gov (United States)

    Darvish, Armin; Goyal, Gaurav; Aneja, Rachna; Sundaram, Ramalingam V. K.; Lee, Kidan; Ahn, Chi Won; Kim, Ki-Bum; Vlahovska, Petia M.; Kim, Min Jun

    2016-07-01

    Solid-state nanopores have been widely used in the past for single-particle analysis of nanoparticles, liposomes, exosomes and viruses. The shape of soft particles, particularly liposomes with a bilayer membrane, can greatly differ inside the nanopore compared to bulk solution as the electric field inside the nanopores can cause liposome electrodeformation. Such deformations can compromise size measurement and characterization of particles, but are often neglected in nanopore resistive pulse sensing. In this paper, we investigated the deformation of various liposomes inside nanopores. We observed a significant difference in resistive pulse characteristics between soft liposomes and rigid polystyrene nanoparticles especially at higher applied voltages. We used theoretical simulations to demonstrate that the difference can be explained by shape deformation of liposomes as they translocate through the nanopores. Comparing our results with the findings from electrodeformation experiments, we demonstrated that the rigidity of liposomes can be qualitatively compared using resistive pulse characteristics. This application of nanopores can provide new opportunities to study the mechanics at the nanoscale, to investigate properties of great value in fundamental biophysics and cellular mechanobiology, such as virus deformability and fusogenicity, and in applied sciences for designing novel drug/gene delivery systems.Solid-state nanopores have been widely used in the past for single-particle analysis of nanoparticles, liposomes, exosomes and viruses. The shape of soft particles, particularly liposomes with a bilayer membrane, can greatly differ inside the nanopore compared to bulk solution as the electric field inside the nanopores can cause liposome electrodeformation. Such deformations can compromise size measurement and characterization of particles, but are often neglected in nanopore resistive pulse sensing. In this paper, we investigated the deformation of various

  16. Inverting polar domains via electrical pulsing in metallic germanium telluride

    Science.gov (United States)

    Nukala, Pavan; Ren, Mingliang; Agarwal, Rahul; Berger, Jacob; Liu, Gerui; Johnson, A. T. Charlie; Agarwal, Ritesh

    2017-04-01

    Germanium telluride (GeTe) is both polar and metallic, an unusual combination of properties in any material system. The large concentration of free-carriers in GeTe precludes the coupling of external electric field with internal polarization, rendering it ineffective for conventional ferroelectric applications and polarization switching. Here we investigate alternate ways of coupling the polar domains in GeTe to external electrical stimuli through optical second harmonic generation polarimetry and in situ TEM electrical testing on single-crystalline GeTe nanowires. We show that anti-phase boundaries, created from current pulses (heat shocks), invert the polarization of selective domains resulting in reorganization of certain 71o domain boundaries into 109o boundaries. These boundaries subsequently interact and evolve with the partial dislocations, which migrate from domain to domain with the carrier-wind force (electrical current). This work suggests that current pulses and carrier-wind force could be external stimuli for domain engineering in ferroelectrics with significant current leakage.

  17. Inverting polar domains via electrical pulsing in metallic germanium telluride

    Science.gov (United States)

    Nukala, Pavan; Ren, Mingliang; Agarwal, Rahul; Berger, Jacob; Liu, Gerui; Johnson, A. T. Charlie; Agarwal, Ritesh

    2017-01-01

    Germanium telluride (GeTe) is both polar and metallic, an unusual combination of properties in any material system. The large concentration of free-carriers in GeTe precludes the coupling of external electric field with internal polarization, rendering it ineffective for conventional ferroelectric applications and polarization switching. Here we investigate alternate ways of coupling the polar domains in GeTe to external electrical stimuli through optical second harmonic generation polarimetry and in situ TEM electrical testing on single-crystalline GeTe nanowires. We show that anti-phase boundaries, created from current pulses (heat shocks), invert the polarization of selective domains resulting in reorganization of certain 71o domain boundaries into 109o boundaries. These boundaries subsequently interact and evolve with the partial dislocations, which migrate from domain to domain with the carrier-wind force (electrical current). This work suggests that current pulses and carrier-wind force could be external stimuli for domain engineering in ferroelectrics with significant current leakage. PMID:28401949

  18. Pulse-compression ghost imaging lidar via coherent detection

    CERN Document Server

    Deng, Chenjin; Han, Shensheng

    2016-01-01

    Ghost imaging (GI) lidar, as a novel remote sensing technique,has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity. Compared with conventional pulsed GI lidar system, pulse-compression GI lidar, without decreasing the range resolution, is easy to obtain high single pulse energy with the use of a long pulse, and the mechanism of coherent detection can eliminate the influence of the stray light, which can dramatically improve the detection sensitivity and detection range.

  19. Pulse-compression ghost imaging lidar via coherent detection.

    Science.gov (United States)

    Deng, Chenjin; Gong, Wenlin; Han, Shensheng

    2016-11-14

    Ghost imaging (GI) lidar, as a novel remote sensing technique, has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity. Compared with conventional pulsed GI lidar system, pulse-compression GI lidar, without decreasing the range resolution, is easy to obtain high single pulse energy with the use of a long pulse, and the mechanism of coherent detection can eliminate the influence of the stray light, which is helpful to improve the detection sensitivity and detection range.

  20. Chemical Detection using Electrically Open Circuits having no Electrical Connections

    Science.gov (United States)

    Woodward, Stanley E.; Olgesby, Donald M.; Taylor, Bryant D.; Shams, Qamar A.

    2008-01-01

    This paper presents investigations to date on chemical detection using a recently developed method for designing, powering and interrogating sensors as electrically open circuits having no electrical connections. In lieu of having each sensor from a closed circuit with multiple electrically connected components, an electrically conductive geometric pattern that is powered using oscillating magnetic fields and capable of storing an electric field and a magnetic field without the need of a closed circuit or electrical connections is used. When electrically active, the patterns respond with their own magnetic field whose frequency, amplitude and bandwidth can be correlated with the magnitude of the physical quantities being measured. Preliminary experimental results of using two different detection approaches will be presented. In one method, a thin film of a reactant is deposited on the surface of the open-circuit sensor. Exposure to a specific targeted reactant shifts the resonant frequency of the sensor. In the second method, a coating of conductive material is placed on a thin non-conductive plastic sheet that is placed over the surface of the sensor. There is no physical contact between the sensor and the electrically conductive material. When the conductive material is exposed to a targeted reactant, a chemical reaction occurs that renders the material non-conductive. The change in the material s electrical resistance within the magnetic field of the sensor alters the sensor s response bandwidth and amplitude, allowing detection of the reaction without having the reactants in physical contact with the sensor.

  1. The effect of pulsed electric fields on carotenoids bioaccessibility: The role of tomato matrix.

    Science.gov (United States)

    Bot, Francesca; Verkerk, Ruud; Mastwijk, Hennie; Anese, Monica; Fogliano, Vincenzo; Capuano, Edoardo

    2018-02-01

    Tomato fractions were subjected to pulsed electric fields treatment combined or not with heating. Results showed that pulsed electric fields and heating applied in combination or individually induced permeabilization of cell membranes in the tomato fractions. However, no changes in β-carotene and lycopene bioaccessibility were found upon combined and individual pulsed electric fields and heating, except in the following cases: (i) in tissue, a significant decrease in lycopene bioaccessibility upon combined pulsed electric fields and heating and heating only was observed; (ii) in chromoplasts, both β-carotene and lycopene bioaccessibility significantly decreased upon combined pulsed electric fields and heating and pulsed electric fields only. The reduction in carotenoids bioaccessibility was attributed to modification in chromoplasts membrane and carotenoids-protein complexes. Differences in the effects of pulsed electric fields on bioaccessibility among different tomato fractions were related to tomato structure complexity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Analysis of Tetracycline Antibiotics Using HPLC with Pulsed Amperometric Detection

    National Research Council Canada - National Science Library

    CHAROENRAKS, Thiraporn; CHUANUWATANAKUL, Suchada; HONDA, Kensuke; YAMAGUCHI, Yoko; CHAILAPAKUL, Orawon

    2005-01-01

    The analysis of tetracycline, oxytetracyline, chlortetracycline and doxycycline by high-performance liquid chromatography with pulsed amperometric detection using an anodized boron-doped diamond thin film (BDD...

  3. Improved Sensing Pulses for Increased Human Head Depth Measurement Sensitivity With Electrical Impedance Spectroscopy

    Science.gov (United States)

    Lev, Michael H.

    2017-01-01

    This paper describes an improved electrical impedance spectroscopy (EIS) stimulus paradigm, based on dual-energy pulses using the stochastic Gabor function (SGF) that may more sensitively assess deep brain tissue impedance than current single-pulse paradigms. The SGF is a uniformly distributed noise, modulated by a Gaussian envelope, with a wide-frequency spectrum representation regardless of the stimuli energy, and is least compact in the sample frequency phase plane. Numerical results obtained using a realistic human head model confirm that two sequential SGF pulses at different energies can improve EIS depth sensitivity when used in a dual-energy subtraction scheme. Specifically, although the two SGF pulses exhibit different tissue current distributions, they maintain the broadband sensing pulse characteristics needed to generate all the frequencies of interest. Moreover, finite-difference time domain simulations show that this dual-energy excitation scheme is capable of reducing the amplitude of weighted current densities surface directly underneath the electrodes by approximately 3 million times versus single stimulation pulses, while maintaining an acceptable tissue conductivity distribution at depth. This increased sensitivity for the detection of small, deep impedance changes might be of value in potential future EIS applications, such as the portable, point-of-care detection of deep brain hemorrhage or infarction. PMID:24043365

  4. Pulsed electrical breakdown of a void-filled dielectric

    Science.gov (United States)

    Anderson, R. A.; Lagasse, R. R.; Schroeder, J. L.

    2002-05-01

    We report breakdown strengths in a void-filled dielectric material, epoxy containing 48 vol % hollow glass microballoon filler, which is stressed with unipolar voltage pulses of the order of 10 μs duration. The microballoon voids had mean diameters of approximately 40 μm and contained SO2 gas at roughly 30% atmospheric pressure. This void-filled material displays good dielectric strength (of the order of 100 kV mm-1) under these short-pulse test conditions. Results from a variety of electrode geometries are reported, including arrangements in which the electric stress is highly nonuniform. Conventional breakdown criteria based on mean or peak electric stress do not account for these data. A statistics-based predictive breakdown model is developed, in which the dielectric is divided into independent, microballoon-sized "discharge cells" and the spontaneous discharge of a single cell is presumed to launch full breakdown of the composite. We obtain two empirical parameters, the mean and standard deviation of the spontaneous discharge field, by fitting breakdown data from two electrode geometries having roughly uniform fields but with greatly differing volumes of electrically stressed material. This model accounts for many aspects of our data, including the inherent statistical scatter and the dependence on the stressed volume, and it provides informative predictions with electrode geometries giving highly nonuniform fields. Issues related to computational spatial resolution and cutoff distance are also discussed.

  5. [Research advances of anti-tumor immune response induced by pulse electric field ablation].

    Science.gov (United States)

    Cui, Guang-ying; Diao, Hong-yan

    2015-11-01

    As a novel tumor therapy, pulse electric field has shown a clinical perspective. This paper reviews the characteristics of tumor ablation by microsecond pulse and nanosecond pulse electric field, and the research advances of anti-tumor immune response induced by pulse electric field ablation. Recent researches indicate that the pulse electric field not only leads to a complete ablation of local tumor, but also stimulates a protective immune response, thereby inhibiting tumor recurrence and metastasis. These unique advantages will show an extensive clinical application in the future. However, the mechanism of anti-tumor immune response and the development of related tumor vaccine need further studies.

  6. Effects of pulsed electric fields on inactivation kinetics of Listeria innocua

    NARCIS (Netherlands)

    Wouters, P.C.; Dutreux, N.; Smelt, J.P.P.M.; Lelieveld, H.L.M.

    1999-01-01

    The effects of pulsed electric field (PEF) treatment and processing factors on the inactivation kinetics of Listeria innocua NCTC 11289 were investigated by using a pilot plant PEF unit with a flow rate of 200 liters/h. The electric field strength, pulse length, number of pulses, and inlet temperatu

  7. Analysis of circular wave packets generated by pulsed electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S., E-mail: shuhei@concord.itp.tuwien.ac.at [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Reinhold, C.O. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6372 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Burgdoerfer, J. [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Wyker, B.; Ye, S.; Dunning, F.B. [Department of Physics and Astronomy and the Rice Quantum Institute, Rice University, Houston, TX 77005-1892 (United States)

    2012-05-15

    We demonstrate that circular wave packets in high Rydberg states generated by a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wave packets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficients.

  8. Analysis of Circular Wave Packets Generated by Pulsed Electric Fields

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S. [Vienna University of Technology, Austria; Reinhold, Carlos O [ORNL; Burgdorfer, J. [Vienna University of Technology, Austria; Wyker, B. [Rice University; Ye, S. [Rice University; Dunning, F. B. [Rice University

    2011-01-01

    We demonstrate that circular wave packets in high Rydberg states generated using a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wavepackets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficient.

  9. Repetitively Pulsed Electric Laser Acoustic Studies. Volume 1.

    Science.gov (United States)

    1983-09-01

    INGARD ET AL. SEP 83 UNCLASSIFIED APHAL-IR-83-2858-VOL-1 F336i5 86-C 2848 F/ 0/ 8, EEEmohEEEomhiE EohEEmhohEEEEE mhhhmmomhhlm...TR-83-2058, Vol 9, 0 REPETITIVELY PULSED ELECTRIC LASER ACOUSTIC STUDIES Volume I K. U. INGARD , CHARLES F. MCMILLAN uDEPARTMENT OF AERONAUTICS AND...CONTRACT OR GRANT NUMBER(s) K.U. Ingard and Charles F. McMillan F33615.80-C-2040 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT

  10. Relaxation Dynamics of Ferroelectric Liquid Crystals in Pulsed Electric Field

    Science.gov (United States)

    Kudreyko, A. A.; Migranov, N. G.; Migranova, D. N.

    2016-11-01

    In this contribution we report a theoretical study of relaxation processes in surface-stabilized ferroelectric liquid crystals with spontaneous polarization. The influence of pulsed electric field on the behavior of ferroelectric liquid crystal in the SmC* phase, which is placed in a thin cell with strong anchoring of SmC* molecules with the boundary substrate, is studied. In the vicinity of the substrate interface, temporal dependence of the azimuthal motion of the director induced by electric field is obtained. The response to the external distortion of ferroelectric liquid crystal confined between two microstructured substrates is the occurrence of periodic temporal formation of solitons connected with the distortion of the director field n in the sample bulk. The interplay between microstructured substrates and director distribution of the ferroelectric SmC* phase is explained by the Frenkel-Kontorova model for a chain of atoms, but adapted for the continuum problem.

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

    Science.gov (United States)

    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.

  12. Nonlinear imaging techniques for the observation of cell membrane perturbation due to pulsed electric field exposure

    Science.gov (United States)

    Moen, Erick K.; Beier, Hope T.; Thompson, Gary L.; Roth, Caleb C.; Ibey, Bennett L.

    2014-03-01

    Nonlinear optical probes, especially those involving second harmonic generation (SHG), have proven useful as sensors for near-instantaneous detection of alterations to orientation or energetics within a substance. This has been exploited to some success for observing conformational changes in proteins. SHG probes, therefore, hold promise for reporting rapid and minute changes in lipid membranes. In this report, one of these probes is employed in this regard, using nanosecond electric pulses (nsEPs) as a vehicle for instigating subtle membrane perturbations. The result provides a useful tool and methodology for the observation of minute membrane perturbation, while also providing meaningful information on the phenomenon of electropermeabilization due to nsEP. The SHG probe Di- 4-ANEPPDHQ is used in conjunction with a tuned optical setup to demonstrate nanoporation preferential to one hemisphere, or pole, of the cell given a single square shaped pulse. The results also confirm a correlation of pulse width to the amount of poration. Furthermore, the polarity of this event and the membrane physics of both hemispheres, the poles facing either electrode, were tested using bipolar pulses consisting of two pulses of opposite polarity. The experiment corroborates findings by other researchers that these types of pulses are less effective in causing repairable damage to the lipid membrane of cells.

  13. A new pulsed electric field microreactor: comparison between the laboratory and microtechnology scale

    NARCIS (Netherlands)

    Fox, Martijn; Esveld, Erik; Luttge, Regina; Boom, Remko

    2005-01-01

    This paper presents a new microreactor dedicated for pulsed electric field treatment (PEF), which is a pasteurization method that inactivates microorganisms with short electric pulses. The PEF microreactor consists of a flow-through channel with a constriction where the electric field is focussed. C

  14. Review of the Dynamics of Coalescence and Demulsification by High-Voltage Pulsed Electric Fields

    Directory of Open Access Journals (Sweden)

    Ye Peng

    2016-01-01

    Full Text Available The coalescence of droplets in oil can be implemented rapidly by high-voltage pulse electric field, which is an effective demulsification dehydration technological method. At present, it is widely believed that the main reason of pulse electric field promoting droplets coalescence is the dipole coalescence and oscillation coalescence in pulse electric field, and the optimal coalescence pulse electric field parameters exist. Around the above content, the dynamics of high-voltage pulse electric field promoting the coalescence of emulsified droplets is studied by researchers domestically and abroad. By review, the progress of high-voltage pulse electric field demulsification technology can get a better understanding, which has an effect of throwing a sprat to catch a whale on promoting the industrial application.

  15. Low Voltage Electrolytic Capacitor Pulse Forming Inductive Network for Electric Weapons

    Science.gov (United States)

    2006-06-01

    reliable high- current, high-energy pulses of many megawatts. Pulsed alternators potentially have the same maintenance issues as other motor...high-energy pulses of many megawatts. Pulsed alternators potentially have the same maintenance issues as other motor-generator sets, so a solid...on an all-electric ship, those challenges are being met. The naval railgun, the army railgun, coilguns , and other electric weapon systems such as

  16. Combination of microsecond and nanosecond pulsed electric field treatments for inactivation of Escherichia coli in water samples.

    Science.gov (United States)

    Žgalin, Maj Kobe; Hodžić, Duša; Reberšek, Matej; Kandušer, Maša

    2012-10-01

    Inactivation of microorganisms with pulsed electric fields is one of the nonthermal methods most commonly used in biotechnological applications such as liquid food pasteurization and water treatment. In this study, the effects of microsecond and nanosecond pulses on inactivation of Escherichia coli in distilled water were investigated. Bacterial colonies were counted on agar plates, and the count was expressed as colony-forming units per milliliter of bacterial suspension. Inactivation of bacterial cells was shown as the reduction of colony-forming units per milliliter of treated samples compared to untreated control. According to our results, when using microsecond pulses the level of inactivation increases with application of more intense electric field strengths and with number of pulses delivered. Almost 2-log reductions in bacterial counts were achieved at a field strength of 30 kV/cm with eight pulses and a 4.5-log reduction was observed at the same field strength using 48 pulses. Extending the duration of microsecond pulses from 100 to 250 μs showed no improvement in inactivation. Nanosecond pulses alone did not have any detectable effect on inactivation of E. coli regardless of the treatment time, but a significant 3-log reduction was achieved in combination with microsecond pulses.

  17. Simulation of the electrically stimulated cochlear neuron: modeling adaptation to trains of electric pulses.

    Science.gov (United States)

    Woo, Jihwan; Miller, Charles A; Abbas, Paul J

    2009-05-01

    The Hodgkin-Huxley (HH) model does not simulate the significant changes in auditory nerve fiber (ANF) responses to sustained stimulation that are associated with neural adaptation. Given that the electric stimuli used by cochlear prostheses can result in adapted responses, a computational model incorporating an adaptation process is warranted if such models are to remain relevant and contribute to related research efforts. In this paper, we describe the development of a modified HH single-node model that includes potassium ion ( K(+)) concentration changes in response to each action potential. This activity-related change results in an altered resting potential, and hence, excitability. Our implementation of K(+)-related changes uses a phenomenological approach based upon K(+) accumulation and dissipation time constants. Modeled spike times were computed using repeated presentations of modeled pulse-train stimuli. Spike-rate adaptation was characterized by rate decrements and time constants and compared against ANF data from animal experiments. Responses to relatively low (250 pulse/s) and high rate (5000 pulse/s) trains were evaluated and the novel adaptation model results were compared against model results obtained without the adaptation mechanism. In addition to spike-rate changes, jitter and spike intervals were evaluated and found to change with the addition of modeled adaptation. These results provide one means of incorporating a heretofore neglected (although important) aspect of ANF responses to electric stimuli. Future studies could include evaluation of alternative versions of the adaptation model elements and broadening the model to simulate a complete axon, and eventually, a spatially realistic model of the electrically stimulated nerve within extracochlear tissues.

  18. Nonlinear imaging of lipid membrane alterations elicited by nanosecond pulsed electric fields

    Science.gov (United States)

    Moen, Erick K.; Beier, Hope T.; Thompson, Gary L.; Armani, Andrea M.; Ibey, Bennett L.

    2015-03-01

    Second Harmonic Generation (SHG) imaging is a useful tool for examining the structure of interfaces between bulk materials. Recently, this technique was applied to detecting subtle perturbations in the structure of cellular membranes following nanosecond pulsed electric field (nsPEF) exposure. Monitoring the cell's outer membrane as it is exposed to nsPEF via SHG has demonstrated that nanoporation is likely the root cause for size-specific, increased cytoplasmic membrane permeabilization. It is theorized that the area of the membrane covered by these pores is tied to pulse intensity or duration. The extent of this effect along the cell's surface, however, has never been measured due to its temporal brevity and minute pore size. By enhancing the SHG technique developed and elucidated previously, we are able to obtain this information. Further, we vary the pulse width and amplitude of the applied stimulus to explore the mechanical changes of the membrane at various sites around the cell. By using this unique SHG imaging technique to directly visualize the change in order of phospholipids within the membrane, we are able to better understand the complex response of living cells to electric pulses.

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

    Science.gov (United States)

    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

  20. The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Catrin F., E-mail: williamscf@cardiff.ac.uk [School of Engineering, Cardiff University, Queen' s Buildings, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales (United Kingdom); Geroni, Gilles M.; Pirog, Antoine; Lees, Jonathan; Porch, Adrian [School of Engineering, Cardiff University, Queen' s Buildings, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); Lloyd, David [School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales (United Kingdom)

    2016-08-29

    Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the “internet of things” is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

  1. The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

    Science.gov (United States)

    Williams, Catrin F.; Geroni, Gilles M.; Pirog, Antoine; Lloyd, David; Lees, Jonathan; Porch, Adrian

    2016-08-01

    Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the "internet of things" is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

  2. Tgf Pulse and Radio Properties Detected at Close Range

    Science.gov (United States)

    Cohen, M.; Gross, N. C.; Zoghzoghy, F. G.; Briggs, M. S.; Stanboro, M.; Fitzpatrick, G.

    2014-12-01

    Terrestrial Gamma-ray Flashes (TGFs) are short (10s to 100s of us) energetic (100s to 10000s of keV) discharges originating from the tops of thunderclouds. TGFs have long been associated with radio pulses detected at VLF receivers, but recent evidence indicates that the radio pulse may be from the TGF itself, rather than from a stroke or pulse that either precedes or follows the TGFs. Unfortunately, subionospheric propagation of VLF/LF smooths the radio pulse and destroys in particular the high frequency content, so that the radio signal looks similar to those from ordinary lightning strokes. Since TGFs have a broad range of durations as detected by satellites, these variations should be apparent in the LF radio pulse from the TGF, which may confirm that the TGF is the dominant source of the associated radio pulse and identify a distinguishing feature of TGF-associated pulses. We report on an effort to detect and characterize the LF radio pulses associated with TGFs at close range (TGF source to the radio source, after accounting for dead time and Compton scattering to interpret the satellite TGF data, as well as propagation of the LF pulse along the ground to the receiver.

  3. [Research progress of nanosecond pulsed electric field applied to intracellular electromanipulation].

    Science.gov (United States)

    Yao, Chenguo; Mo, Dengbin; Sun, Caixin; Chen, Xin; Xiong, Zheng'ai

    2008-10-01

    In recent years, many experts have done some researches on experiment and mechanism of intracellular electromanipulation (IEM) under nanosecond pulsed electric field (nsPEF). The experiment results have shown that nsPEF could not induce electroporation of cell membrane, but could induce intracellular effects such as apoptosis, calcium release, enhancement of gene expression, and fragmentation of DNA and chromosome. In order to account for the phenomenon, researchers believe that when the pulse width of the pulsed electric field is larger than the charging time of plasma membrane, the pulsed electric field mainly targets on the outer membrane of cell; and that the effect of the pulsed electric field on nucleus and nuclear membrane increases with the decrease of the pulse width. It is also believed that the effect of electroporation changes from the outer membrane to intracellular electromanipulation when the pulse width decreases to a value being smaller than the charging time of plasma membrane.

  4. Theory of pulsed reaction yield detected magnetic resonance

    NARCIS (Netherlands)

    Nasibulov, E.A.; Kulik, L.V.; Kaptein, R.; Ivanov, K.L.

    2012-01-01

    We propose pulse sequences for Reaction Yield Detected Magnetic Resonance (RYDMR), which are based on refocusing the zero-quantum coherences in radical pairs by non-selective microwave pulses and using the population of a radical pair singlet spin state as an observable. The new experiments are

  5. Repair of nonunions by electrically pulsed current stimulation.

    Science.gov (United States)

    Zichner, L

    1981-01-01

    Five congenital and 52 acquired nonunions of bone were stimulated using an invasive device. The unit delivered a constant but pulsed right-angled current of positive polarity measuring 20 to 25 muAmps (voltage of 750 mV) and a frequency of 20 Hz. The power pack encapsulated in epoxy resin was implanted at the time of operative fragment stabilization. THe cathode was inserted at the site of the nonunion gap. After two to 12 months, all but two of the acquired nonunions and one of the congenital pseudarthroses healed. In the unsuccessful cases, the bone ends were often totally necrotic. Four cases required reimplantation because of broken wires or expiration of the battery, and two cases failed owing to purulent infection. Electrostimulation is an adjuvant treatment to fragment stabilization in hyporeactive and hypovascular or congenital pseudarthroses. Electrical stimuli may be assumed to simulate conditions which are essential for bone healing.

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

    Energy Technology Data Exchange (ETDEWEB)

    Timoshkin, I V [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); MacGregor, S J [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Fouracre, R A [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Crichton, B H [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Anderson, J G [Robertson Trust Laboratory for Electronic Sterilization Technologies (ROLEST), Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom)

    2006-02-07

    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.

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

    Science.gov (United States)

    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.

  8. C-phycocyanin extraction assisted by pulsed electric field from Artrosphira platensis.

    Science.gov (United States)

    Martínez, Juan Manuel; Luengo, Elisa; Saldaña, Guillermo; Álvarez, Ignacio; Raso, Javier

    2017-09-01

    This paper assesses the application of pulsed electric fields (PEF) to the fresh biomass of Artrhospira platensis in order to enhance the extraction of C-phycocyanin into aqueous media. Electroporation of A. platensis depended on both electric field strength and treatment duration. The minimum electric field intensity for detecting C-phycocyanin in the extraction medium was 15kV/cm after the application of a treatment time 150μs (50 pulses of 3μs). However higher electric field strength were required when shorter treatment times were applied. Response surface methodology was used in order to investigate the influence of electric field strength (15-25kV/cm), treatment time (60-150μs), and temperature of application of PEF (10-40°C) on C-phycocyanin extraction yield (PEY). The increment of the temperature PEF treatment reduced the electric field strength and the treatment time required to obtain a given PEY and, consequently decreased the total specific energy delivered by the treatment. For example, the increment of temperature from 10°C to 40°C permitted to reduce the electric field strength required to extract 100mg/g dw of C-phycocyanin from 25 to 18kV/cm, and the specific energy input from 106.7 to 67.5kJ/Kg. Results obtained in this investigation demonstrated PEF's potential for selectively extraction C-phycocyanin from fresh A. platensis biomass. The purity of the C-phycocyanin extract obtained from the electroporated cells was higher than that obtained using other techniques based on the cell complete destruction. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Cutaneous papilloma and squamous cell carcinoma therapy utilizing nanosecond pulsed electric fields (nsPEF.

    Directory of Open Access Journals (Sweden)

    Dong Yin

    Full Text Available Nanosecond pulsed electric fields (nsPEF induce apoptotic pathways in human cancer cells. The potential therapeutic effective of nsPEF has been reported in cell lines and in xenograft animal tumor model. The present study investigated the ability of nsPEF to cause cancer cell death in vivo using carcinogen-induced animal tumor model, and the pulse duration of nsPEF was only 7 and 14 nano second (ns. An nsPEF generator as a prototype medical device was used in our studies, which is capable of delivering 7-30 nanosecond pulses at various programmable amplitudes and frequencies. Seven cutaneous squamous cell carcinoma cell lines and five other types of cancer cell lines were used to detect the effect of nsPEF in vitro. Rate of cell death in these 12 different cancer cell lines was dependent on nsPEF voltage and pulse number. To examine the effect of nsPEF in vivo, carcinogen-induced cutaneous papillomas and squamous cell carcinomas in mice were exposed to nsPEF with three pulse numbers (50, 200, and 400 pulses, two nominal electric fields (40 KV/cm and 31 KV/cm, and two pulse durations (7 ns and 14 ns. Carcinogen-induced cutaneous papillomas and squamous carcinomas were eliminated efficiently using one treatment of nsPEF with 14 ns duration pulses (33/39 = 85%, and all remaining lesions were eliminated after a 2nd treatment (6/39 = 15%. 13.5% of carcinogen-induced tumors (5 of 37 were eliminated using 7 ns duration pulses after one treatment of nsPEF. Associated with tumor lysis, expression of the anti-apoptotic proteins Bcl-xl and Bcl-2 were markedly reduced and apoptosis increased (TUNEL assay after nsPEF treatment. nsPEF efficiently causes cell death in vitro and removes papillomas and squamous cell carcinoma in vivo from skin of mice. nsPEF has the therapeutic potential to remove human squamous carcinoma.

  10. Changes across time in the temporal responses of auditory nerve fibers stimulated by electric pulse trains.

    Science.gov (United States)

    Miller, Charles A; Hu, Ning; Zhang, Fawen; Robinson, Barbara K; Abbas, Paul J

    2008-03-01

    Most auditory prostheses use modulated electric pulse trains to excite the auditory nerve. There are, however, scant data regarding the effects of pulse trains on auditory nerve fiber (ANF) responses across the duration of such stimuli. We examined how temporal ANF properties changed with level and pulse rate across 300-ms pulse trains. Four measures were examined: (1) first-spike latency, (2) interspike interval (ISI), (3) vector strength (VS), and (4) Fano factor (FF, an index of the temporal variability of responsiveness). Data were obtained using 250-, 1,000-, and 5,000-pulse/s stimuli. First-spike latency decreased with increasing spike rate, with relatively small decrements observed for 5,000-pulse/s trains, presumably reflecting integration. ISIs to low-rate (250 pulse/s) trains were strongly locked to the stimuli, whereas ISIs evoked with 5,000-pulse/s trains were dominated by refractory and adaptation effects. Across time, VS decreased for low-rate trains but not for 5,000-pulse/s stimuli. At relatively high spike rates (>200 spike/s), VS values for 5,000-pulse/s trains were lower than those obtained with 250-pulse/s stimuli (even after accounting for the smaller periods of the 5,000-pulse/s stimuli), indicating a desynchronizing effect of high-rate stimuli. FF measures also indicated a desynchronizing effect of high-rate trains. Across a wide range of response rates, FF underwent relatively fast increases (i.e., within 100 ms) for 5,000-pulse/s stimuli. With a few exceptions, ISI, VS, and FF measures approached asymptotic values within the 300-ms duration of the low- and high-rate trains. These findings may have implications for designs of cochlear implant stimulus protocols, understanding electrically evoked compound action potentials, and interpretation of neural measures obtained at central nuclei, which depend on understanding the output of the auditory nerve.

  11. Intense picosecond pulsed electric fields inhibit proliferation and induce apoptosis of HeLa cells.

    Science.gov (United States)

    Zhang, Min; Xiong, Zheng-Ai; Chen, Wen-Juan; Yao, Cheng-Guo; Zhao, Zhong-Yong; Hua, Yuan-Yuan

    2013-06-01

    A picosecond pulsed electric field (psPEF) is a localized physical therapy for tumors that has been developed in recent years, and that may in the future be utilized as a targeted non‑invasive treatment. However, there are limited studies regarding the biological effects of psPEF on cells. Electric field amplitude and pulse number are the main parameters of psPEF that influence its biological effects. In this study, we exposed HeLa cells to a psPEF with a variety of electric field amplitudes, from 100 to 600 kV/cm, and various pulse numbers, from 1,000 to 3,000. An MTT assay was used to detect the growth inhibition, while flow cytometry was used to determine the occurrence of apoptosis and the cell cycle of the HeLa cells following treatment. The morphological changes during cell apoptosis were observed using transmission electron microscopy (TEM). The results demonstrated that the cell growth inhibition rate gradually increased, in correlation with the increasing electric field amplitude and pulse number, and achieved a plateau of maximum cell inhibition 12 h following the pulses. In addition, typical characteristics of HeLa cell apoptosis in the experimental groups were observed by TEM. The results demonstrated that the rate of apoptosis in the experimental groups was significantly elevated in comparison with the untreated group. In the treatment groups, the rate of apoptosis was greater in the higher amplitude groups than in the lower amplitude groups. The same results were obtained when the variable was the pulse number. Flow cytometric analysis indicated that the cell cycle of the HeLa cells was arrested at the G2/M phase following psPEF treatment. Overall, our results indicated that psPEF inhibited cell proliferation and induced cell apoptosis, and that these effects occurred in a dose-dependent manner. In addition, the results demonstrated that the growth of the HeLa cells was arrested at the G2/M phase following treatment. This study may provide a

  12. Improving carotenoid extraction from tomato waste by pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Elisa eLuengo

    2014-08-01

    Full Text Available In this investigation, the influence of the application of Pulsed Electric Fields (PEF 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.

  13. Toward 6 log10 pulsed electric field inactivation with conductive plastic packaging material

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Ferreira, J.A.; Coronel, P.; Wouters, P.C.; Hatt, V.

    2013-01-01

    Generally, high grade products such as pulsed electric field (PEF) treated fruit juices are packaged after their preservative treatment. However, PEF treatment after packaging could avoid recontamination of the product and becomes feasible when electric field pulses of sufficient magnitude can be ge

  14. Toward 6 log10 pulsed electric field inactivation with conductive plastic packaging material

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Ferreira, J.A.; Coronel, P.; Wouters, P.C.; Hatt, V.

    2013-01-01

    Generally, high grade products such as pulsed electric field (PEF) treated fruit juices are packaged after their preservative treatment. However, PEF treatment after packaging could avoid recontamination of the product and becomes feasible when electric field pulses of sufficient magnitude can be

  15. The effect of electric pulse stimulation to juvenile cod and cod of commercial landing size

    NARCIS (Netherlands)

    Haan, de D.; Fosseidengen, J.E.; Fjelldal, P.G.; Burggraaf, D.

    2011-01-01

    The first pilot study on the effects of electric pulse stimulation on larger cod carried out in 2008 was based on a single nominal setting of the Verburg-Holland UK153 pulse system with the intention to determine the range of pulse characteristics with which injuries to the fish occurred. This study

  16. Waveform sensitivity of electroreceptors in the pulse weakly electric fish Gymnotus omarorum.

    Science.gov (United States)

    Rodríguez-Cattaneo, Alejo; Aguilera, Pedro A; Caputi, Angel A

    2017-02-15

    As in most sensory systems electrosensory images in weakly electric fish are encoded in two parallel pathways, fast and slow. From the work on wave type electric fish these pathways are thought to encode the time and amplitude of electrosensory signals respectively. This article focuses on the primary afferents giving origin to the slow path of the pulse type weakly electric fish Gymnotus omarorum We found that burst duration coders respond with a high-frequency train of spikes to each electric organ discharge. They also show high sensitivity to phase-frequency distortions of the self-generated local electric field. We explored this sensitivity by manipulating the longitudinal impedance of a probe cylinder to modulate the stimulus waveform, while extracellularly recording isolated primary afferents. Resistive loads only affect the amplitude of the re-afferent signals without distorting the waveform. Capacitive loads cause large waveform distortions aside from amplitude changes. Stepping from a resistive to a capacitive load in such a way that the stimulus waveform was distorted, without changing its total energy, caused strong changes in latency, inter-spike interval and number of spikes of primary afferents responses. These burst parameters are well correlated suggesting that they may contribute synergistically in driving downstream neurons. This correlation also suggests that each receptor encodes a single parameter in the stimulus waveform. The finding of waveform distortion sensitivity is relevant because it may contribute to: a) enhance electroreceptive range in the peripheral "electrosensory field", b) a better identification of living preys at the "foveal electrosensory field" and c) to detect the presence and orientation of conspecifics. Our results also suggest a revision of the classical view of amplitude and time encoding by fast and slow pathways in pulse type electric fish.

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

    Science.gov (United States)

    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(2+)), is important to action potential firing and regulates many ion channels. However, uncontrolled hyper-excitability of neurons leads to Ca(2+) 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(2+) influx using Calcium Green. The ED50 for a single 600 ns pulse, necessary to cause uptake of extracellular Ca(2+), 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(2+) channel blocker, failed to prevent Ca(2+) uptake suggesting that observed influx is likely due to nanoporation. These data demonstrate that moderate amplitude single nsPEF exposures result in rapid Ca(2+) influx that may be capable of controllably modulating neurological function.

  18. Shaped pulse electric-field construction and interferometric characterization: The SPECIFIC method

    CERN Document Server

    Coughlan, Matthew A; Weber, Stefan M; Bowlan, Pamela; Trebino, Rick; Levis, Robert J

    2009-01-01

    A method is reported for creating, generating, and measuring parametrically shaped pulses for time-bandwidth product >>5, which consists of a parametric pulse-shaping algorithm, a spatial light modulation system and a single shot interferometric characterization scheme (SEA TADPOLE) . The utilization of these tools marks the inception of a new method called SPECIFIC, shaped-pulse electric-field construction and interferometric characterization, capable of producing complex shaped laser pulses for coherent control experiments.

  19. Special nuclear material detection using pulsed neutron interrogation

    Science.gov (United States)

    Ruddy, Frank H.; Seidel, John G.; Flammang, Robert W.

    2007-04-01

    Pulsed neutron interrogation methods for detection of Special Nuclear Materials are being developed. Fast prompt neutrons from thermal neutron-induced fissions are detected in the time intervals following 100-μs neutron bursts from a pulsed D-T neutron generator operating at 1000 pulses per second. Silicon Carbide semiconductor neutron detectors are used to detect fission neutrons in the 30-840 μs time intervals following each 14-MeV D-T neutron pulse. Optimization of the neutron detectors has led to dramatic reduction of detector background and improvement of the signal-to-noise ratio for Special Nuclear Material detection. Detection of Special Nuclear Materials in the presence of lead, cadmium and plywood shielding has been demonstrated. Generally, the introduction of shielding leads to short thermal neutron die-away times of 100-200 μs or less. The pulsed neutron interrogation method developed allows detection of the neutron signal even when the die-away time is less than 100 μs.

  20. Detection of pulsed neutrons with solid-state electronics

    Science.gov (United States)

    Chatzakis, J.; Rigakis, I.; Hassan, S. M.; Clark, E. L.; Lee, P.

    2016-09-01

    Measurements of the spatial and time-resolved characteristics of pulsed neutron sources require large area detection materials and fast circuitry that can process the electronic pulses readout from the active region of the detector. In this paper, we present a solid-state detector based on the nuclear activation of materials by neutrons, and the detection of the secondary particle emission of the generated radionuclides’ decay. The detector utilizes a microcontroller that communicates using a modified SPI protocol. A solid-state, pulse shaping filter follows a charge amplifier, and it is designed as an inexpensive, low-noise solution for measuring pulses measured by a digital counter. An imaging detector can also be made by using an array of these detectors. The system can communicate with an interface unit and pass an image to a personal computer.

  1. Commercial scale pulsed electric field processing of tomato juice.

    Science.gov (United States)

    Min, Seacheol; Jin, Z Tony; Zhang, Q Howard

    2003-05-21

    Effects of commercial scale pulsed electric field (PEF) processing on the quality of tomato juice were studied and compared with those of thermal processing. Tomato juice was prepared by hot break at 88 degrees C for 2 min or by cold break at 68 degrees C for 2 min and then thermally processed at 92 degrees C for 90 s or PEF processed at 40 kV/cm for 57 micros. Thermally processed, PEF processed, and unprocessed control juices were packed into 50 mL sterilized polypropylene tubes in a sanitary glovebox and stored at 4 degrees C for 112 days. Both thermally and PEF processed juices showed microbial shelf life at 4 degrees C for 112 days. The lipoxygenase activities of thermally and PEF processed juices were 0 and 47%, respectively. PEF processed juice retained more ascorbic acid than thermally processed juice at 4 degrees C for 42 days (p Brix, pH, or viscosity between thermally and PEF processed juices during the storage (p > 0.05). Sensory evaluations indicated that flavor and overall acceptability of PEF processed juice were preferred to those of thermally processed juice (p < 0.05).

  2. Repetition rate tunable ultra-short optical pulse generation based on electrical pattern generator

    Institute of Scientific and Technical Information of China (English)

    Xin Fu; Hongming Zhang; Meng Yan; Minyu Yao

    2009-01-01

    @@ An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator.By changing the repetition rate of the electrical patterns applied on the in-cavity modulator, the repetition rate of the output optical pulse sequences changes accordingly while the pulse width of the optical pulse train remains almost constant.In other words, the output ultra-short pulse train has a tunable duty cycle.In a proof-of-principle experiment, optical pulses with repetition rates of 10, 5, 2.5 and 1.25 GHz are obtained by adjusting the electrical pattern applied on the in-cavity modulator while their pulse widths remain almost unchanged.

  3. Electrostrictive limit and focusing effects in pulsed photoacoustic detection

    Science.gov (United States)

    Heritier, J.-M.

    1983-01-01

    We give an analytical solution in the time and frequency domain for the cylindrical pressure wave generated by a laser pulse traveling in a liquid, which is valid over a wide range of laser beam dimensions and pulse durations. This leads to a simple prediction of the ultimate limitation set by the electrostrictive coupling and an easy analysis of the focusing effects on the photoacoustic signal. Two separate detection schemes were considered and show different behavior.

  4. Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

    Science.gov (United States)

    Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

    2013-05-01

    In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity.

  5. Probe beam-free detection of terahertz wave by electroluminescence induced by intense THz pulse

    Science.gov (United States)

    Shin, J.; Jin, Z.; Nosaka, Y.; Nakazawa, T.; Kodama, R.

    2016-03-01

    Recently, a table-top fs laser system can generate MW terahertz (THz) pulse with its electric field higher than 100 kV/cm can be generated by several schemes. Such a strong THz field can directly drive electrons inside various materials. Here, we demonstrated a direct THz electric field detection method by measuring the electroluminescence induced by intense THz pulse inside commonly available light emitting diode. An intense THz wave obtained by the two-color laser scheme was focused onto LED along with an external DC bias to induce luminescence which we found proportional to the amplitude of the incident THz field. The scheme can be useful to realize a low-cost, probe-free THz detection and imaging system.

  6. Pulsed electric field assisted sol-gel preparation of TiO2 nanoparticles

    Science.gov (United States)

    Mani, Rajaboopathi; Han, Bing; Louhi-Kultanen, Marjatta

    2016-10-01

    This work studies the effect of a pulsed electric field (PEF) on the precipitation and properties of TiO2 nanoparticles. TiO2 nanoparticles were prepared using pulsed DC electric field assisted sol-gel method. The duration of the PEF treatment was varied to investigate its effect on the particle size of TiO2 nanoparticles. The nanoparticles were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, UV diffuse reflectance spectroscopy (UV-DRS) and transmission electron microscopy (TEM). It was found that TiO2 particles prepared with pulsed electric field assisted sol-gel method had enhanced average crystallite size due to the effect of the pulsed electric field on primary nucleation. The effect of electric field on nanoparticle preparation is interesting which can be used to control the grain and crystallite size of nanoparticle.

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

    Science.gov (United States)

    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.

  8. Nanosecond pulsed electric fields and the cell cycle

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Stephen J Beebe

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  11. Campo elétrico pulsado Pulsed electric field

    Directory of Open Access Journals (Sweden)

    Mirella Lima Binoti

    2012-05-01

    Full Text Available Campos elétricos pulsados de alta intensidade (CEPAI constituem um método não-térmico de conservação para alimentos em substituição à pasteurização tradicional. Em comparação ao processamento térmico, os CEPAI, além de serem eficientes na eliminação de micro-organismos e na inativação de enzimas, também minimizam as perdas de sabor, cor, textura, nutrientes e componentes termolábeis dos alimentos. O objetivo desse trabalho foi levantar dados bibliográficos atuais sobre o tema CEPAI, abordando: definição do processo, instalação experimental, efeito da ruptura dielétrica do alimento, efeito sobre micro-organismo, enzimas e constituintes dos alimentos. Os dados encontrados na literatura apontam o tratamento por CEPAI como alternativa promissora para a conservação de alimentos, podendo ser utilizado como tecnologia única ou como complemento aos processamentos térmicos.Pulsed electric fields of high intensity (HIPEF is a non-thermal food conservation to replace traditional thermal pasteurization. Compared to thermal processing, the HIPEF as well as being effective in removing microorganisms and inactivate enzymes also minimize the loss of flavor, color, texture, nutrients and labile components of food. The aim of this work was to gather bibliographic data current HIPEF on the subject, covering: experimental setup, effects of dielectric breakdown of food, effect on microorganisms, enzymes and constituents of food. The data found in the literature indicate treatment of HIPEF as a promising alternative for food conservation and it could be used as a single technology or in addition to thermal processing.

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

    Science.gov (United States)

    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.

  13. Using electric fields for pulse compression and group velocity control

    CERN Document Server

    Li, Qian; Thuresson, Axel; Rippe, Lars; Kröll, Stefan

    2016-01-01

    In this article, we experimentally demonstrate a new way of controlling the group velocity of an optical pulse by using a combination of spectral hole burning, slow light effect and linear Stark effect in a rare-earth-ion-doped crystal. The group velocity can be changed continuously by a factor of 20 without significant pulse distortion or absorption of the pulse energy. With a similar technique, an optical pulse can also be compressed in time. Theoretical simulations were developed to simulate the group velocity control and the pulse compression processes. The group velocity as well as the pulse reshaping are solely controlled by external voltages which makes it promising in quantum information and quantum communication processes. It is also proposed that the group velocity can be changed even more in an Er doped crystal while at the same time having a transmission band matching the telecommunication wavelength.

  14. Histopathology of normal skin and melanomas after nanosecond pulsed electric field treatment.

    Science.gov (United States)

    Chen, Xinhua; James Swanson, R; Kolb, Juergen F; Nuccitelli, Richard; Schoenbach, Karl H

    2009-12-01

    Nanosecond pulsed electric fields (nsPEFs) can affect the intracellular structures of cells in vitro. This study shows the direct effects of nsPEFs on tumor growth, tumor volume, and histological characteristics of normal skin and B16-F10 melanoma in SKH-1 mice. A melanoma model was set up by injecting B16-F10 into female SKH-1 mice. After a 100-pulse treatment with an nsPEF (40-kV/cm field strength; 300-ns duration; 30-ns rise time; 2-Hz repetition rate), tumor growth and histology were studied using transillumination, light microscopy with hematoxylin and eosin stain and transmission electron microscopy. Melanin and iron within the melanoma tumor were also detected with specific stains. After nsPEF treatment, tumor development was inhibited with decreased volumes post-nsPEF treatment compared with control tumors (Pcell contraction and nuclear shrinkage while concurrently, but not permanently, damaging peripheral healthy skin tissue in the treated area, which we attribute to the highly localized electric fields surrounding the needle electrodes.

  15. Single Pulse Electrical Stimulation to identify epileptogenic cortex: Clinical information obtained from early evoked responses

    NARCIS (Netherlands)

    Mouthaan, B.E.; van 't Klooster, M.A.; Keizer, D.; Hebbink, Gerrit Jan; Leijten, F.S.; Ferrier, C.H.; van Putten, Michel Johannes Antonius Maria; Zijlmans, M.; Huiskamp, G.J.

    2016-01-01

    Objective Single Pulse Electrical Stimulation (SPES) probes epileptogenic cortex during electrocorticography. Two SPES responses are described: pathological delayed responses (DR, >100 ms) associated with the seizure onset zone (SOZ) and physiological early responses (ER, <100 ms) that map cortical

  16. Single pulse electrical stimulation to identify epileptogenic cortex: Clinical information obtained from early evoked responses

    NARCIS (Netherlands)

    Mouthaan, B.E.; van 't Klooster, M.A.; Keizer, D.; Hebbink, Gerrit Jan; Leijten, F.S.S.; Ferrier, C.H.; van Putten, Michel Johannes Antonius Maria; Zijlmans, M.; Huiskamp, G.J.M.

    Objective: Single Pulse Electrical Stimulation (SPES) probes epileptogenic cortex during electrocorticography. Two SPES responses are described: pathological delayed responses (DR, >100 ms) associated with the seizure onset zone (SOZ) and physiological early responses (ER, <100 ms) that map cortical

  17. Effect of melt pulse electric current and thermal treatment on A356 alloy

    Institute of Scientific and Technical Information of China (English)

    何树先; 王俊; 江莞; 孙宝德; 周尧和

    2003-01-01

    Effects of the melt pulse electric current and thermal treatment on solidification structures of A356 alloywere investigated. In the experiments, the low temperature melt(953 K and 903 K) treated by pulse electric currentwas mixed with high temperature melt(1 223 K). By the control experiments, the results show that the solidificationstructure of A356 alloy is refined apparently by the pulse electric current togeth er with melt thermal treatmentprocess, and the mechanical properties, especially the elongation ratio of the specimen treated is improved greatly.The structure change of the melt by pulse electric current and melt thermal treatment is the main reason for the re-finement of the solidification structure of A356 alloy.

  18. Ultra-wideband short-pulse radar with range accuracy for short range detection

    Science.gov (United States)

    Rodenbeck, Christopher T; Pankonin, Jeffrey; Heintzleman, Richard E; Kinzie, Nicola Jean; Popovic, Zorana P

    2014-10-07

    An ultra-wideband (UWB) radar transmitter apparatus comprises a pulse generator configured to produce from a sinusoidal input signal a pulsed output signal having a series of baseband pulses with a first pulse repetition frequency (PRF). The pulse generator includes a plurality of components that each have a nonlinear electrical reactance. A signal converter is coupled to the pulse generator and configured to convert the pulsed output signal into a pulsed radar transmit signal having a series of radar transmit pulses with a second PRF that is less than the first PRF.

  19. A Comparison between Electrical and Optical Chromatic Dispersion Compensation in Wavelength Divison Multiplexing Network Regarding to Electrical Pulse Shapes

    Directory of Open Access Journals (Sweden)

    Mohammad S. Ab-Rahman

    2012-01-01

    Full Text Available Problem statement: Besides of some impairment that has been inherited form single channel, specialists confronted with new obstacles in WDM implementation which bared them for achieving desired performance. Although Chromatic Dispersion (CD exists in single channel too, it can worsens new nonlinearities which are occurs just in WDM systems. So CD compensation in WDM is even more vital than single channel one. Approach: A wide range of optical and electrical CD compensation techniques have been represented. In this study we evaluate the efficiency of feed Forward-Decision Feedback Equalizer (FFE-DFE as one type of electrical compensation methods and Dispersion Compensation Fiber as one type of optical compensator. Also we will look how electrical pulse shapes induced by pulse generator in transmitter, can impact on the performance of the either optical or electrical compensations. Results: After implementation, it was revealed that overall optical compensation with DCF gives us better performance than electrical equalizer and NRZ is more vulnerable than two other pulse shapes. Conclusion: Chromatic compensation was implemented with different pulse shapes and RZ pulse shape with optical compensation showed the best performance.

  20. Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

    Science.gov (United States)

    Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng

    2005-04-01

    This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

  1. Growth of pulsed electric field exposed Escherichia coli in relation to inactivation and environmental factors.

    Science.gov (United States)

    Aronsson, Kristina; Borch, Elisabeth; Stenlöf, Bo; Rönner, Ulf

    2004-05-15

    Pulsed electric fields (PEF) have been proven to inactivate microorganisms during nonthermal conditions and have the potential to replace thermal processing as a method for food preservation. However, there is a need to understand the recovery and growth of survivors and potentially injured microorganisms following PEF processing. The purpose of this investigation was to study the growth of Escherichia coli at 10 degrees C following exposure to electrical field strengths (15, 22.5 and 30 kV/cm) in relation to inactivation and the amount of potentially sublethally injured cells. One medium was used as both a treatment medium and an incubation medium, to study the influence of environmental factors on the inactivation and the growth of the surviving population. The pH (5.0, 6.0 and 7.0) and water activity (1.00, 0.985 and 0.97) of the medium was varied by adding HCl and glycerol, respectively. Growth was followed continuously by measuring the optical density. The time-to-detection (td) and the maximum specific growth rate (micromax) were calculated from these data. Results showed that the PEF process did not cause any obvious sublethal injury to the E. coli cells. The number of survivors was a consequence of the combination of electrical field strength and environmental factors, with pH being the most prominent. Interestingly, the micromax of subsequent growth was influenced by the applied electrical field strength during the process, with an increased micromax at more intense electrical field strengths. In addition, the micromax was also influenced by the pH and water activity. The td, which could theoretically be considered as an increase in shelf life, was found to depend on a complex correlation between electrical field strength, pH and water activity. That could be explained by the fact that the td is a combination of the number of survivors, the recovery of sublethal injured cells and the growth rate of the survivors.

  2. The Influence of Electrical Pulses on Thick Film (Du Pont 1421 Birox) Resistors

    OpenAIRE

    Tancula, M.; Kozlowski, J. M.

    1982-01-01

    This paper presents data on the effect of electric pulses on thick film resistors made using Du Pont 1421 Birox resistor pastes.Resistance changes during the application of the electric pulses were investigated. Two types of change were observed: reversible and irreversible (i.e. catastrophic).In order to illustrate the causes of these changes, observations of the film on a scanning electron microscope were made. Microcracks were observed in the film, which were mostly responsible for the per...

  3. Hypersonic Flow over a Cylinder with a Nanosecond Pulse Electrical Discharge

    Science.gov (United States)

    2014-03-01

    Hypersonic Flow over a Cylinder with a Nanosecond Pulse Electrical Discharge Nicholas J. Bisek∗ and Jonathan Poggie† U.S. Air Force Research...pulsed at nanosecond time scales and it rapidly added thermal energy to the flow, creating a shock wave that traveled away from the pulse source. As the...volumetric energy deposition model [14]. The approach was based on the assumption that the primary flow control mechanism of the ns-DBD is rapid thermal

  4. Detection of diamond in ore using pulsed laser Raman spectroscopy

    CSIR Research Space (South Africa)

    Lamprecht, GH

    2007-10-01

    Full Text Available The viability of using pulsed laser excited Raman spectroscopy as a method for diamond detection from ore, has been investigated. In this method the spontaneous Stokes Raman signal is used as indicator of diamond, and a dual channel system...

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

    Science.gov (United States)

    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 (...

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

    Science.gov (United States)

    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. ARRAY PULSED EDDY CURRENT IMAGING SYSTEM USED TO DETECT CORROSION

    Institute of Scientific and Technical Information of China (English)

    Yang Binfeng; Luo Feilu; Cao Xiongheng; Xu Xiaojie

    2005-01-01

    A theory model is established to describe the voltage-current response function. The peak amplitude and the zero-crossing time of the transient signal is extracted as the imaging features, array pulsed eddy current (PEC) imaging is proposed to detect corrosion. The test results show that this system has the advantage of fast scanning speed, different imaging mode and quantitative detection, it has a broad application in the aviation nondestructive testing.

  8. Compact electrically detected magnetic resonance setup

    Directory of Open Access Journals (Sweden)

    Michael Eckardt

    2015-04-01

    Full Text Available Electrically detected magnetic resonance (EDMR is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a “large-scale” state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule.

  9. Two modes of cell death caused by exposure to nanosecond pulsed electric field.

    Directory of Open Access Journals (Sweden)

    Olga N Pakhomova

    Full Text Available High-amplitude electric pulses of nanosecond duration, also known as nanosecond pulsed electric field (nsPEF, are a novel modality with promising applications for cell stimulation and tissue ablation. However, key mechanisms responsible for the cytotoxicity of nsPEF have not been established. We show that the principal cause of cell death induced by 60- or 300-ns pulses in U937 cells is the loss of the plasma membrane integrity ("nanoelectroporation", leading to water uptake, cell swelling, and eventual membrane rupture. Most of this early necrotic death occurs within 1-2 hr after nsPEF exposure. The uptake of water is driven by the presence of pore-impermeable solutes inside the cell, and can be counterbalanced by the presence of a pore-impermeable solute such as sucrose in the medium. Sucrose blocks swelling and prevents the early necrotic death; however the long-term cell survival (24 and 48 hr does not significantly change. Cells protected with sucrose demonstrate higher incidence of the delayed death (6-24 hr post nsPEF. These cells are more often positive for the uptake of an early apoptotic marker dye YO-PRO-1 while remaining impermeable to propidium iodide. Instead of swelling, these cells often develop apoptotic fragmentation of the cytoplasm. Caspase 3/7 activity increases already in 1 hr after nsPEF and poly-ADP ribose polymerase (PARP cleavage is detected in 2 hr. Staurosporin-treated positive control cells develop these apoptotic signs only in 3 and 4 hr, respectively. We conclude that nsPEF exposure triggers both necrotic and apoptotic pathways. The early necrotic death prevails under standard cell culture conditions, but cells rescued from the necrosis nonetheless die later on by apoptosis. The balance between the two modes of cell death can be controlled by enabling or blocking cell swelling.

  10. Two modes of cell death caused by exposure to nanosecond pulsed electric field.

    Science.gov (United States)

    Pakhomova, Olga N; Gregory, Betsy W; Semenov, Iurii; Pakhomov, Andrei G

    2013-01-01

    High-amplitude electric pulses of nanosecond duration, also known as nanosecond pulsed electric field (nsPEF), are a novel modality with promising applications for cell stimulation and tissue ablation. However, key mechanisms responsible for the cytotoxicity of nsPEF have not been established. We show that the principal cause of cell death induced by 60- or 300-ns pulses in U937 cells is the loss of the plasma membrane integrity ("nanoelectroporation"), leading to water uptake, cell swelling, and eventual membrane rupture. Most of this early necrotic death occurs within 1-2 hr after nsPEF exposure. The uptake of water is driven by the presence of pore-impermeable solutes inside the cell, and can be counterbalanced by the presence of a pore-impermeable solute such as sucrose in the medium. Sucrose blocks swelling and prevents the early necrotic death; however the long-term cell survival (24 and 48 hr) does not significantly change. Cells protected with sucrose demonstrate higher incidence of the delayed death (6-24 hr post nsPEF). These cells are more often positive for the uptake of an early apoptotic marker dye YO-PRO-1 while remaining impermeable to propidium iodide. Instead of swelling, these cells often develop apoptotic fragmentation of the cytoplasm. Caspase 3/7 activity increases already in 1 hr after nsPEF and poly-ADP ribose polymerase (PARP) cleavage is detected in 2 hr. Staurosporin-treated positive control cells develop these apoptotic signs only in 3 and 4 hr, respectively. We conclude that nsPEF exposure triggers both necrotic and apoptotic pathways. The early necrotic death prevails under standard cell culture conditions, but cells rescued from the necrosis nonetheless die later on by apoptosis. The balance between the two modes of cell death can be controlled by enabling or blocking cell swelling.

  11. Evaluation of Pulse Counting for the Mars Organic Mass Analyzer (MOMA) Ion Trap Detection Scheme

    Science.gov (United States)

    Van Amerom, Friso H.; Short, Tim; Brinckerhoff, William; Mahaffy, Paul; Kleyner, Igor; Cotter, Robert J.; Pinnick, Veronica; Hoffman, Lars; Danell, Ryan M.; Lyness, Eric I.

    2011-01-01

    The Mars Organic Mass Analyzer is being developed at Goddard Space Flight Center to identify organics and possible biological compounds on Mars. In the process of characterizing mass spectrometer size, weight, and power consumption, the use of pulse counting was considered for ion detection. Pulse counting has advantages over analog-mode amplification of the electron multiplier signal. Some advantages are reduced size of electronic components, low power consumption, ability to remotely characterize detector performance, and avoidance of analog circuit noise. The use of pulse counting as a detection method with ion trap instruments is relatively rare. However, with the recent development of high performance electrical components, this detection method is quite suitable and can demonstrate significant advantages over analog methods. Methods A prototype quadrupole ion trap mass spectrometer with an internal electron ionization source was used as a test setup to develop and evaluate the pulse-counting method. The anode signal from the electron multiplier was preamplified. The an1plified signal was fed into a fast comparator for pulse-level discrimination. The output of the comparator was fed directly into a Xilinx FPGA development board. Verilog HDL software was written to bin the counts at user-selectable intervals. This system was able to count pulses at rates in the GHz range. The stored ion count nun1ber per bin was transferred to custom ion trap control software. Pulse-counting mass spectra were compared with mass spectra obtained using the standard analog-mode ion detection. Prelin1inary Data Preliminary mass spectra have been obtained for both analog mode and pulse-counting mode under several sets of instrument operating conditions. Comparison of the spectra revealed better peak shapes for pulse-counting mode. Noise levels are as good as, or better than, analog-mode detection noise levels. To artificially force ion pile-up conditions, the ion trap was overfilled

  12. Energy detection UWB system based on pulse width modulation

    Directory of Open Access Journals (Sweden)

    Song Cui

    2014-05-01

    Full Text Available A new energy detection ultra-wideband system based on pulse width modulation is proposed. The bit error rate (BER performance of this new system is slightly worst than that of a pulse position modulation (PPM system in additive white Gaussian noise channels. In multipath channels, this system does not suffer from cross-modulation interference as PPM, so it can achieve better BER performance than PPM when cross-modulation interference occurs. In addition, when synchronisation errors occur, this system is more robust than PPM.

  13. Detection of early dental caries with short pulse laser

    Energy Technology Data Exchange (ETDEWEB)

    Okubo, Nahoko; Goto, Shigeru [Osada Research Inst., Ltd., Tokyo (Japan); Tanaka, Hiroshi; Ohzu, Akira; Arisawa, Takashi [Japan Atomic Energy Research Inst., Kansai Research Establishment, Advanced Photon Research Center, Kyoto (Japan)

    2002-07-01

    Differences in the optical properties of polarization and photoluminescence between caries lesion and noncaries (sound) enamel have been investigated by focusing a pulsed Nd:YAG laser of 532 nm on the surface of teeth. Significant difference in the polarization property of the scattered light from the surface can be observed with some carious samples. For photoluminescence spectral lines which appear at around 650 nm, the intensity of caries lesion has been approximately two times higher than that of sound one. A discussion is presented in which early are potentially detectable by the pulsed laser. (author)

  14. Electron-Positron Pair Production in Structured Pulses of Electric Fields

    CERN Document Server

    Kohlfürst, Christian

    2012-01-01

    The non-perturbative electron-positron pair production in time-dependent electric fields is investigated. The quantum kinetic formalism is employed in order to calculate the electron density for various field configurations. The corresponding set of first order, ordinary differential equations is analyzed and numerically solved. The focus of this study lies on the dynamically assisted Schwinger effect in pulsed electric fields with at least two different time scales. Furthermore, interference effects arising in setups with multiple pulses are examined and first results for an optimization of the particle number yield by pulse-shaping are given.

  15. Eradication of multidrug-resistant A. baumannii in burn wounds by antiseptic pulsed electric field.

    Science.gov (United States)

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

    2014-06-01

    Emerging bacterial resistance to multiple drugs is an increasing problem in burn wound management. New non-pharmacologic interventions are needed for burn wound disinfection. Here we report on a novel physical method for disinfection: antiseptic pulsed electric field (PEF) applied externally to the infected burns. In a mice model, we show that PEF can reduce the load of multidrug resistant Acinetobacter baumannii present in a full thickness burn wound by more than four orders of magnitude, as detected by bioluminescence imaging. Furthermore, using a finite element numerical model, we demonstrate that PEF provides non-thermal, homogeneous, full thickness treatment for the burn wound, thus, overcoming the limitation of treatment depth for many topical antimicrobials. These modeling tools and our in vivo results will be extremely useful for further translation of the PEF technology to the clinical setting, as they provide the essential elements for planning of electrode design and treatment protocol.

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

    Science.gov (United States)

    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.

  17. The Basics of Electric Weapons and Pulsed-Power Technologies

    Science.gov (United States)

    2012-01-01

    shown in Figure 2. Electrical energy can be stored in many ways, such as a battery (actually a chemical storage ). A car battery has about a...becomes less attractive. Energy storage for electric weapons can also be done with chem- ical explosive energy , where an explosive force is converted...into electrical energy using techniques such as flux compression. Energy can be stored in the inertia of rotating machines and flywheels , but the

  18. Platelet activation using electric pulse stimulation: growth factor profile and clinical implications.

    Science.gov (United States)

    Torres, Andrew S; Caiafa, Antonio; Garner, Allen L; Klopman, Steve; LaPlante, Nicole; Morton, Christine; Conway, Kenneth; Michelson, Alan D; Frelinger, Andrew L; Neculaes, V Bogdan

    2014-09-01

    Autologous platelet gel therapy using platelet-rich plasma has emerged as a promising alternative for chronic wound healing, hemostasis, and wound infection control. A critical step for this therapeutic approach is platelet activation, typically performed using bovine thrombin (BT) and calcium chloride. However, exposure of humans to BT can stimulate antibody formation, potentially resulting in severe hemorrhagic or thrombotic complications. Electric pulse stimulation using nanosecond PEFs (pulse electric fields) is an alternative, nonbiochemical platelet activation method, thereby avoiding exposure to xenogeneic thrombin and associated risks. In this study, we identified specific requirements for a clinically relevant activator instrument by dynamically measuring current, voltage, and electric impedance for platelet-rich plasma samples. From these samples, we investigated the profile of growth factors released from human platelets with electric pulse stimulation versus BT, specifically platelet-derived growth factor, transforming growth factor β, and epidermal growth factor, using commercial enzyme-linked immunosorbent assay kits. Electric pulse stimulation triggers growth factor release from platelet α-granules at the same or higher level compared with BT. Electric pulse stimulation is a fast, inexpensive, easy-to-use platelet activation method for autologous platelet gel therapy.

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

    Science.gov (United States)

    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 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 situ microscopic evaluation of onion cells, as they were pulsed with electric fields at different frequencies, to determine whether frequency was an important parameter. We illustrate that membranes were more effectively broken at lower frequencies as compared to higher frequencies. Application of this information will allow for improved design of PEF systems for more energy efficient dehydration or extraction of

  20. Pulsed electric field technology: Modeling of electric field and temperature distributions within continuous flow PEF treatment chamber

    OpenAIRE

    Salengke, dkk

    2012-01-01

    Innovations and technology developments in the field of food pasteurization and sterilization are continuously evolving. These include innovations in thermal processing technologies such as aseptic processing, ohmic technology, and microwave technology, as well as non-thermal processing technologies which include pulsed electric field technology and high pressure processing technology. This paper discussed the results of a study on mathematical modeling of electric field and temperature distr...

  1. An integrated CMOS detection system for optical short-pulse

    Science.gov (United States)

    Kim, Chang-Gun; Hong, Nam-Pyo; Choi, Young-Wan

    2014-03-01

    We present design of a front-end readout system consisting of charge sensitive amplifier (CSA) and pulse shaper for detection of stochastic and ultra-small semiconductor scintillator signal. The semiconductor scintillator is double sided silicon detector (DSSD) or avalanche photo detector (APD) for high resolution and peak signal reliability of γ-ray or X-ray spectroscopy. Such system commonly uses low noise multichannel CSA. Each CSA in multichannel includes continuous reset system based on tens of MΩ and charge-integrating capacitor in feedback loop. The high value feedback resistor requires large area and huge power consumption for integrated circuits. In this paper, we analyze these problems and propose a CMOS short pulse detection system with a novel CSA. The novel CSA is composed of continuous reset system with combination of diode connected PMOS and 100 fF. This structure has linearity with increased input charge quantity from tens of femto-coulomb to pico-coulomb. Also, the front-end readout system includes both slow and fast shapers for detecting CSA output and preventing pile-up distortion. Shaping times of fast and slow shapers are 150 ns and 1.4 μs, respectively. Simulation results of the CMOS detection system for optical short-pulse implemented in 0.18 μm CMOS technology are presented.

  2. Predicting the threshold of pulse-train electrical stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

    Science.gov (United States)

    Xu, Yifang; Collins, Leslie M

    2004-04-01

    The incorporation of low levels of noise into an electrical stimulus has been shown to improve auditory thresholds in some human subjects (Zeng et al., 2000). In this paper, thresholds for noise-modulated pulse-train stimuli are predicted utilizing a stochastic neural-behavioral model of ensemble fiber responses to bi-phasic stimuli. The neural refractory effect is described using a Markov model for a noise-free pulse-train stimulus and a closed-form solution for the steady-state neural response is provided. For noise-modulated pulse-train stimuli, a recursive method using the conditional probability is utilized to track the neural responses to each successive pulse. A neural spike count rule has been presented for both threshold and intensity discrimination under the assumption that auditory perception occurs via integration over a relatively long time period (Bruce et al., 1999). An alternative approach originates from the hypothesis of the multilook model (Viemeister and Wakefield, 1991), which argues that auditory perception is based on several shorter time integrations and may suggest an NofM model for prediction of pulse-train threshold. This motivates analyzing the neural response to each individual pulse within a pulse train, which is considered to be the brief look. A logarithmic rule is hypothesized for pulse-train threshold. Predictions from the multilook model are shown to match trends in psychophysical data for noise-free stimuli that are not always matched by the long-time integration rule. Theoretical predictions indicate that threshold decreases as noise variance increases. Theoretical models of the neural response to pulse-train stimuli not only reduce calculational overhead but also facilitate utilization of signal detection theory and are easily extended to multichannel psychophysical tasks.

  3. Pulsed Direct Current Electric Fields Enhance Osteogenesis in Adipose-Derived Stromal Cells

    OpenAIRE

    Hammerick, Kyle E.; James, Aaron W.; Huang, Zubin; Prinz, Fritz B.; Michael T. Longaker

    2009-01-01

    Adipose-derived stromal cells (ASCs) constitute a promising source of cells for regenerative medicine applications. Previous studies of osteogenic potential in ASCs have focused on chemicals, growth factors, and mechanical stimuli. Citing the demonstrated role electric fields play in enhancing healing in bone fractures and defects, we investigated the ability of pulsed direct current electric fields to drive osteogenic differentiation in mouse ASCs. Employing 50 Hz direct current electric fie...

  4. Damage Detection in Electrically Conductive Structures

    Science.gov (United States)

    Anderson, Todd A.

    2002-12-01

    High-technology systems are in need of structures that perform with increased functionality and a reduction in weight, while simultaneously maintaining a high level of performance and reliability. To accomplish this, structural elements must be designed more efficiently and with increased functionality, thereby creating multifunctional structures (MFS). Through the addition of carbon fibers, nanotubes, or particles, composite structures can be made electrically conductive while simultaneously increasing their strength and stiffness to weight ratios. Using the electrical properties of these structures for the purpose of damage detection and location for health and usage monitoring is of particular interest for aerospace structures. One such method for doing this is Electrical Impedance Tomography (EIT). With EIT, an electric current is applied through a pair of electrodes and the electric potential is recorded at other monitoring electrodes around the area of study. An inverse solution of the governing Maxwell equations is then required to determine the conductivities of discrete areas within the region of interest. However, this method is nearly ill-posed and computationally intensive as it focuses on imaging small changes in conductivity within the region of interest. For locating damage in a medium with an otherwise homogeneous conductivity, an alternative approach is to search for parameters such as the damage location and size. Towards those ends, this study develops an Artificial Neural Network (ANN) to determine the state of an electrically conductive region based on applied reference current and electrical potentials at electrodes around the periphery of the region. A significant benefit of the ANN approach is that once trained, the solution of an inverse problem does not require costly computations of the inverse problem. This method also takes advantage of the pattern recognition abilities of neural networks and is a robust solution method in the presence

  5. Metal release in a stainless steel Pulsed Electric Field (PEF) system Part I. Effect of different pulse shapes; theory and experimental method

    NARCIS (Netherlands)

    Roodenburg, B.; Morren, J.; Berg, H.E.; Haan, S.W.H.de

    2005-01-01

    Liquid pumpable food is mostly pasteurised by heat treatment. In the last decennia there is an increasing interest in so-called Pulsed Electric Field (PEF) treatment. During this treatment food is pumped between two metal electrodes and exposed to short high electric field pulses, typical 2-4 kV mm-

  6. Detection of secular acceleration pulses from magnetic observatory data

    Science.gov (United States)

    Soloviev, Anatoly; Chulliat, Arnaud; Bogoutdinov, Shamil

    2017-09-01

    Geomagnetic secular variation (SV) models for the epochs before the space era are based on magnetic observatory data, which represent relatively rough and noisy time series due to magnetic storms, anthropogenic spikes and gaps. These models are often strongly regularized in time, so that fast variations in the SV are smoothed out. However, recent studies show that at least some of the geomagnetic jerks observed at the Earth's surface emanate from increasing and decreasing phases of secular acceleration (SA) pulses at the core surface. The latter ones are direct manifestation of the dynamic processes taking place in the liquid core. They were first detected from satellite data, which are both of higher quality and more homogeneous in terms of geographical coverage than ground data. Herein we attempt to carry out similar studies based on observatory data available for a longer period. The proposed method of SV modeling and recognition of SA pulses relies on a new technique of processing time series based on fuzzy mathematics. Comparison with the SV modeling results derived from satellite data shows their high conformity with the proposed method. Stability and reliability of the SA pulse recognition are demonstrated by the examples of well-studied SA pulses in 2006, 2009 and 2012. Moreover, several new SA pulses around 1996, 1999, 2002 and 2014 are discovered as a result of the new approach application to multi-observatory data analysis. The latter provides a basis for applying the method to older historical data and investigate SA pulses and geomagnetic jerks further back in time.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. A Real-time Single Pulse Detection Algorithm for GPUs

    CERN Document Server

    Adámek, Karel

    2016-01-01

    The detection of non-repeating events in the radio spectrum has become an important area of study in radio astronomy over the last decade due to the discovery of fast radio bursts (FRBs). We have implemented a single pulse detection algorithm, for NVIDIA GPUs, which use boxcar filters of varying widths. Our code performs the calculation of standard deviation, matched filtering by using boxcar filters and thresholding based on the signal-to-noise ratio. We present our parallel implementation of our single pulse detection algorithm. Our GPU algorithm is approximately 17x faster than our current CPU OpenMP code (NVIDIA Titan XP vs Intel E5-2650v3). This code is part of the AstroAccelerate project which is a many-core accelerated time-domain signal processing code for radio astronomy. This work allows our AstroAccelerate code to perform a single pulse search on SKA-like data 4.3x faster than real-time.

  10. Effect of electric current pulse on grain growth in superplastic deformation of 2091 Al-Li alloy

    Institute of Scientific and Technical Information of China (English)

    刘志义; 许晓嫦; 崔建忠

    2003-01-01

    The effect of electric current pulse on the grain growth in the superplastic deformation of 2091 Al-Li alloy was investigated. Optical metallographic microstructure observation and average linear intercept measuring results show that at same strain, the grain size in the superplastic deformation loaded with electric current pulse is smaller than that unemploying electric current pulse, and so does the grain growth rate. TEM observation shows that the dislocation density at grain boundary in the superplastic deformation applied with electric current pulse is lower than that unemploying electric current pulse.It indicates that electric current pulse increases the rate of dislocation slip and climb in grain boundary, which leads to a decrease of both the density of the dislocation slipping across grain boundary at same strain rate and the driving force for grain growth, therefore the rate of grain growth decreases.The established model for grain growth shows an exponential relation of grain size with strain.

  11. A single molecule detection method for understanding mechanisms of electric field-mediated interstitial transport of genes.

    Science.gov (United States)

    Henshaw, Joshua W; Zaharoff, David A; Mossop, Brian J; Yuan, Fan

    2006-10-01

    The interstitial space is a rate limiting physiological barrier to non-viral gene delivery. External pulsed electric fields have been proposed to increase DNA transport in the interstitium, thereby improving non-viral gene delivery. In order to characterize and improve the interstitial transport, we developed a reproducible single molecule detection method to observe the electromobility of DNA in a range of pulsed, high field strength electric fields typically used during electric field-mediated gene delivery. Using agarose gel as an interstitium phantom, we investigated the dependence of DNA electromobility on field magnitude, pulse duration, pulse interval, and pore size in the interstitial space. We observed that the characteristic electromobility behavior, exhibited under most pulsing conditions, consisted of three distinct phases: stretching, reptation, and relaxation. Electromobility depended strongly on the field magnitude, pulse duration, and pulse interval of the applied pulse sequences, as well as the pore size of the fibrous matrix through which the DNA migrated. Our data also suggest the existence of a minimum pulse amplitude required to initiate electrophoretic transport. These results are useful for understanding the mechanisms of DNA electromobility and improving interstitial transport of genes during electric field-mediated gene delivery.

  12. Automatic Detection of Electric Power Troubles (ADEPT)

    Science.gov (United States)

    Wang, Caroline; Zeanah, Hugh; Anderson, Audie; Patrick, Clint; Brady, Mike; Ford, Donnie

    1988-01-01

    Automatic Detection of Electric Power Troubles (A DEPT) is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system. It is designed for two modes of operation: real time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a laser printer. This system consists of a simulated space station power module using direct-current power supplies for solar arrays on three power buses. For tests of the system's ablilty to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three buses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modeling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base.

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

    Science.gov (United States)

    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.

  14. Electric field simulation and measurement of a pulse line ion accelerator

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiao-Kang; ZHANG Zi-Min; CAO Shu-Chun; ZHAO Hong-Wei; WANG Bo; SHEN Xiao-Li; ZHAO Quan-Tang; LIU Ming; JING Yi

    2012-01-01

    An oil dielectric helical pulse line to demonstrate the principles of a Pulse Line Ion Accelerator (PL1A) has been designed and fabricated.The simulation of the axial electric field of an accelerator with CST code has been completed and the simulation results show complete agreement with the theoretical calculations.To fully understand the real value of the electric field excited from the helical line in PLIA,an optical electric integrated electric field measurement system was adopted.The measurement result shows that the real magnitude of axial electric field is smaller than that calculated,probably due to the actual pitch of the resister column which is much less than that of helix.

  15. Teraelectronvolt pulsed emission from the Crab pulsar detected by MAGIC

    CERN Document Server

    Ahnen, M L; Antonelli, L A; Antoranz, P; Babic, A; Banerjee, B; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Buson, S; Carmona, E; Carosi, A; Chatterjee, A; Clavero, R; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Wilhelmi, E de Oña; Mendez, C Delgado; Di Pierro, F; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Glawion, D Eisenacher; Elsaesser, D; Fernández-Barral, A; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giammaria, P; Godinović, N; Muñoz, A González; Gora, D; Guberman, D; Hadasch, D; Hahn, A; Hanabata, Y; Hayashida, M; Herrera, J; Hose, J; Hrupec, D; Hughes, G; Idec, W; Kodani, K; Konno, Y; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lindfors, E; Lombardi, S; Longo, F; López, M; López-Coto, R; Lorenz, E; Majumdar, P; Makariev, M; Mallot, K; Maneva, G; Manganaro, M; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Moretti, E; Nakajima, D; Neustroev, V; Niedzwiecki, A; Rosillo, M Nievas; Nilsson, K; Nishijima, K; Noda, K; Orito, R; Overkemping, A; Paiano, S; Palacio, J; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Pedaletti, G; Persic, M; Poutanen, J; Moroni, P G Prada; Prandini, E; Puljak, I; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Saito, T; Satalecka, K; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Stamerra, A; Steinbring, T; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Torres, D F; Toyama, T; Treves, A; Verguilov, V; Vovk, I; Ward, J E; Will, M; Wu, M H; Zanin, R

    2015-01-01

    Aims: To investigate the extension of the very-high-energy spectral tail of the Crab pulsar at energies above 400 GeV. Methods: We analyzed $\\sim$320 hours of good quality data of Crab with the MAGIC telescope, obtained from February 2007 until April 2014. Results: We report the most energetic pulsed emission ever detected from the Crab pulsar reaching up to 1.5 TeV. The pulse profile shows two narrow peaks synchronized with the ones measured in the GeV energy range. The spectra of the two peaks follow two different power-law functions from 70 GeV up to 1.5 TeV and connect smoothly with the spectra measured above 10 GeV by the Large Area Telescope (LAT) on board of the Fermi satellite. When making a joint fit of the LAT and MAGIC data, above 10 GeV, the photon indices of the spectra differ by 0.5$\\pm$0.1. Conclusions: We measured with the MAGIC telescopes the most energetic pulsed photons from a pulsar to date. Such TeV pulsed photons require a parent population of electrons with a Lorentz factor of at least ...

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

    Science.gov (United States)

    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

  17. Growth and apoptosis of HeLa cells induced by intense picosecond pulsed electric field

    Directory of Open Access Journals (Sweden)

    Yuan-yuan HUA

    2011-07-01

    Full Text Available Objective To investigate the growth and apoptosis of HeLa cells induced by intense picosecond pulsed electric field(PEF in vitro.Methods HeLa cells cultured in vitro were divided into experimental group and control group(with or without intense picosecond PEF.With constant pulse width,frequency and voltage,the cells in experimental group were divided into 6 sub-groups according to the number of pulse(100,200,500,1000,1500,2000,the growth inhibition of HeLa cells by PEF and the dose-effect relationship were analyzed by MTT.Caspase 3 protein activity was detected in the cells in 500,1000 and 2000 sub-groups.Mitochondrial transmembrane potential was detected by rhodamine 123 staining with the cells in 2000 sub-groups.Results MTT assay demonstrated that intense picosecond PEF significantly inhibited the proliferation of HeLa cells in dose-dependent manner.The survival rates of cells declined along with the increase in pulse number,and were 96.23%±0.76%,94.11%±2.42%,90.31%±1.77%,64.59%±1.59%,32.95%±0.73%,23.85%±2.38% and 100%,respectively,in 100,200,500,1000,1500,2000 sub-groups and control group(P < 0.01.The Caspase 3 protein activity was significantly enhanced by intense picosecond PEF,and the absorbancy indexes(A were 0.174±0.012,0.232±0.017,0.365±0.016 and 0.122±0.011,respectively,in 500,1000,2000 sub-groups and control group(P < 0.05.The mitochondrial transmembrane potential of HeLa cells was significantly inhibited by intense picosecond PEF,and the fluorescence intensity in 2000 sub-group(76.66±13.38 was much lower than that in control group(155.81±2.33,P < 0.05.Conclusion Intense picosecond PEF may significantly inhibit the growth of HeLa cells,and induce cell apoptosis via mitochondrial pathway.

  18. Electrical pulse fabrication of graphene nanopores in electrolyte solution

    Energy Technology Data Exchange (ETDEWEB)

    Kuan, Aaron T.; Szalay, Tamas [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Lu, Bo [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Xie, Ping [Oxford Nanopore Technologies, One Kendall Square, Cambridge, Massachusetts 02139 (United States); Golovchenko, Jene A., E-mail: golovchenko@physics.harvard.edu [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2015-05-18

    Nanopores in graphene membranes can potentially offer unprecedented spatial resolution for single molecule sensing, but their fabrication has thus far been difficult, poorly scalable, and prone to contamination. We demonstrate an in-situ fabrication method that nucleates and controllably enlarges nanopores in electrolyte solution by applying ultra-short, high-voltage pulses across the graphene membrane. This method can be used to rapidly produce graphene nanopores with subnanometer size accuracy in an apparatus free of nanoscale beams or tips.

  19. A novel application of pulsed electric field (PEF) processing for improving glutathione (GSH) antioxidant activity.

    Science.gov (United States)

    Wang, Jia; Wang, Ke; Wang, Ying; Lin, Songyi; Zhao, Ping; Jones, Gregory

    2014-10-15

    Glutathione (GSH) was treated by pulsed electric field (PEF) processing to investigate its effect on antioxidant activity. The antioxidant activity of GSH was evaluated using 2,2-diphenyl-1-picrylhydrazy (DPPH) radical inhibition. A Box-Behnken design (BBD) with three independent variables, which were concentration, electric field intensity and pulse frequency was used to establish the regression equation of second-order response surface. Optimal conditions were as follows: GSH concentration 8.86mg/mL, electric field intensity 9.74kV/cm and pulse frequency 2549.08Hz. The DPPH radical inhibition increased from 81.83% to 97.40%. Near-infrared spectroscopy (NIR) and mid-infrared spectroscopy (MIR) were used to analyse the change of structure and functional groups of GSH.

  20. Alternate pulses of ultrasound and electricity enhanced electrochemical process for p-nitrophenol degradation.

    Science.gov (United States)

    Xie, Fengchun; Xu, Yun; Xia, Kunyuan; Jia, Caixia; Zhang, Pin

    2016-01-01

    A novel alternated ultrasonic and electric pulse enhanced electrochemical process was developed and used for investigating its effectiveness on the degradation of p-nitrophenol (PNP) in an aqueous solution. The impacts of pulse mode, pH, cell voltage, supporting electrolyte concentration, ultrasonic power and the initial concentration of PNP on the performance of PNP degradation were evaluated. Possible pathway of PNP degradation in this system was proposed based on the intermediates identified by GC-MS. Experimental results showed that 94.1% of PNP could be removed at 2h in the dual-pulse ultrasound enhanced electrochemical (dual-pulse US-EC) process at mild operating conditions (i.e., pulse mode of electrochemical pulse time (TEC)=50 ms and ultrasonic pulse time (T US)=100 ms, initial pH of 3.0, cell voltage of 10 V, Na2SO4 concentration of 0.05 M, ultrasonic powder of 48.8 W and initial concentration of PNP of 100mg/L), compared with 89.0%, 58.9%, 2.4% in simultaneous ultrasound enhanced electrochemical (US-EC) process, pulsed electrochemical (EC) process and pulsed ultrasound (US), respectively. Moreover, energy used in the dual-pulse US-EC process was reduced by 50.4% as compared to the US-EC process. The degradation of PNP in the pulsed EC process, US-EC process and dual-pulse process followed pseudo-first-order kinetics. Therefore, the dual-pulse US-EC process was found to be a more effective technique for the degradation of PNP and would have a promising application in wastewater treatment.

  1. All-optical DAC using counter-propagating optical and electrical pulses in a Mach-Zehnder modulator.

    Science.gov (United States)

    Lowery, Arthur James

    2014-10-20

    A novel method of converting binary-level electrical pulses into multi-level optical pulses using only a conventional traveling-wave optical modulator is presented. The method provides low inter-pulse interference due to the counter-propagating pulses, low amplitude noise, and a timing jitter determined chiefly by the quality of the optical pulse source. The method only requires one electrical drive per modulator and provides low-jitter variable-amplitude optical pulses that are suitable for shaping into a wide variety of modulation formats using a programmable optical filter.

  2. Near-Field Propagation of Sub-Nanosecond Electric Pulses into Amorphous Masses

    Science.gov (United States)

    2012-02-01

    delivered at 10 Hz, the cell membrane becomes more permeable : it shows a higher leakage current compared with the cell that is not pulsed. The leakage...plication, to allow enough time for dialysis of the cytoplasm with the pipette solution. Whole-cell currents were probed by stepping the membrane...constant, were found to cause cell death and a change in membrane permeability . For the electric pulse con- dition, 200 ps, 25 kV/cm, using 1.8 million

  3. Influence of the Thomson effect on the pulse heating of high-current electrical contacts

    Science.gov (United States)

    Merkushev, A. G.; Pavleino, M. A.; Pavleino, O. M.; Pavlov, V. A.

    2014-09-01

    Pulse heating of high-current contacts is notable for the presence of considerable temperature gradients in the contact area, which cause the Thomson effect—the appearance of thermoelectric currents. The amount of this effect against conventional Joule heat release is quantitatively estimated. Pulse heating of electrical contacts is numerically simulated with the use of the Comsol program package. It is demonstrated that thermoelectric currents make a negligible contribution to heating in the case of copper contacts.

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

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2015-03-01

    Full Text Available 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.

  5. Casting structure of pure aluminum by electric pulse modification at different superheated temperatures

    Institute of Scientific and Technical Information of China (English)

    Jingang Qi; Jianzhong Wang; Xingjiang Liu; Bing Wang; Daqiang Cang

    2005-01-01

    Electric pulse modification (EPM) is a novel technique that reduces grain size by altering the structure of a melt. It was investigated that the response of the casting structure of high pure aluminum to EPM in different superheated melts. The results indicate that the grain refining effect of a given pulse electric field holds an optimal temperature range, moreover, a lower or higher superheated temperature will both disadvantage the improvements of casting structure. It essentially lies in the cooperative action between the distorted absorption of clusters and the activated capability of atoms in the aluminum melt.

  6. Effects of High-voltage Pulse Electric Field Treatment on the Structure Stability of Konjac Glucomannan

    Institute of Scientific and Technical Information of China (English)

    YAO Min-Na; FAN Lin-Lin; LIU Ya-Nan; CHEN Qing-Ai; ZENG Yuan; JIAN Wen-Jie; PANG Jie

    2011-01-01

    Structures of KGM treated in two high-voltage pulse electric fields were characterized by infrared spectroscopy,Raman spectroscopy,X-ray diffraction and so on.The results showed that intermolecular hydrogen bonding interactions of KGM were reduced after being treated with high-voltage pulse electric field,but there was no significant effect on its fiber chain form and thermal characteristics.Results of the study can provide a useful reference for further study on the structure and property of KGM,and especially can provide theoretical basis for the effect of physical field on the foodstuff deep processing related to KGM.

  7. Electrical and mechanical characteristics of nanosecond pulsed sliding dielectric barrier discharges with different electrode gaps

    Science.gov (United States)

    Bayoda, K. D.; Benard, N.; Moreau, E.

    2015-10-01

    This study proposes the characterization of a surface sliding discharge that extends over a length of 80 mm. The gas ionization is caused by series of high voltage pulses with nanosecond rising and decaying times while ion drift is forced by a negative DC component. Different plasma diagnostics such as electrical measurements, iCCD visualizations and strioscopy have been performed. They highlight that a threshold mean electric field between both air-exposed electrodes is required to fully establish a sliding discharge. Compared to a single nanosecond pulsed dielectric barrier discharge, the sliding discharge results in an energy consumption increase. Moreover, the pressure wave induced by the discharge is strongly impacted.

  8. A scheme of pulse compression lidar with enhanced modulated bandwidth for detection through scattering media

    Science.gov (United States)

    Yang, Cheng-hua; Zhang, Yong; Jin, Chen-fei; Xu, Lu; Yang, Xu; Wang, Qiang; Liu, Yue-hao; Zhao, Yuan

    2016-12-01

    This paper presents a scheme of pulse compression lidar with enhanced electrical modulated bandwidth. An ultra-wideband linear frequency modulated signal with a bandwidth of 50 GHz is generated using femtosecond laser and superimposed linear chirp fiber Bragg gratings in the transmitter, which separates the echo of the target from the backward scattered noise with low modulated frequency. An optical pulse compression system based on a negative dispersion fiber Bragg grating is used to compress the ultra-wideband linear frequency modulated signal in the receiver. SNR and range resolution of the proposed scheme are numerically simulated to prove its feasibility. The simulation results indicate that an enhancement of SNR by 15.8 dB can be achieved using the scheme, and the range resolution of the scheme increases from 0.68 m to 0.0027 m. It is therefore concluded that the proposed scheme is suitable for detection through scattering media.

  9. Pulsed and streamer discharges in air above breakdown electric field

    NARCIS (Netherlands)

    Sun, A.B.; Teunissen, H.J.; Ebert, U.

    2013-01-01

    A 3D particle model is developed to investigate the streamer formation in electric fields above the breakdown threshold, in atmospheric air (1bar, 300 Kelvin). Adaptive particle management, adaptive mesh refinement and parallel computing techniques are used in the code. Photoionization and electron

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

    Science.gov (United States)

    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.

  11. Numerical simulation of high voltage electric pulse comminution of phosphate ore

    Institute of Scientific and Technical Information of China (English)

    Razavian Seyed Mohammad; Rezai Bahram; Irannajad Mehdi; Ravanji Mohammad Hasan

    2015-01-01

    Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was used to numerically simulate the effect of ore compositions in this study. Regarding phos-phate ore particles shape and composition, the effects of mineral composition, particle size, particle shape and electrodes distance were investigated on the electrical field intensity and distribution. The results show that the induced electrical field is significantly dependent on the electrical properties of minerals, the feed particle size and the location of conductive minerals in ores. The angle of material contact sur-face with the discharge electrode is also an important factor in the intensity of electrical field. Moreover, it is found that the specific liberation effect at the disintegration of phosphate ore by electrical pulses is due to the locality of the electrical field at the interface of mineral components of the phosphate ore aggregates with different permittivities. However, the intensity of the electrical field increases with shar-pening the contact angle. Besides, the electrical discharge in the samples is converted to the elec-trohydraulic discharge across the surrounding water by changing the distance between the discharge electrode and sample surface.

  12. High impact ionization rate in silicon by sub-picosecond THz electric field pulses (Conference Presentation)

    DEFF Research Database (Denmark)

    Tarekegne, Abebe Tilahun; Iwaszczuk, Krzysztof; Hirori, Hideki

    2017-01-01

    Summary form only given. Metallic antenna arrays fabricated on high resistivity silicon are used to localize and enhance the incident THz field resulting in high electric field pulses with peak electric field strength reaching several MV/cm on the silicon surface near the antenna tips. In such high...... electric field strengths high density of carriers are generated in silicon through impact ionization process. The high density of generated carriers induces a change of refractive index in silicon. By measuring the change of reflectivity of tightly focused 800 nm light, the local density of free carriers...... near the antenna tips is measured. Using the NIR probing technique, we observed that the density of carriers increases by over 8 orders of magnitude in a time duration of approximately 500 fs with an incident THz pulse of peak electric field strength 700 kV/cm. This shows that a single impact...

  13. Pulsed electrical discharges in water for removal of organic pollutants: a comparative study

    OpenAIRE

    Dang, T.H.; Denat, A.; Lesaint, O.; Teissedre, G.

    2009-01-01

    Abstract In this study, the efficiency of different types of pulsed electrical discharges for the removal of organic pollutants from wastewater has been determined. Three discharge types, either in the water volume or in close proximity to the water surface are studied. The production of hydrogen peroxide in pure water, and the degradation of two typical pollutants (4-chlorophenol and 4-nitrophenol) is measured together with the amount of electrical energy d...

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

    Science.gov (United States)

    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

  15. Effects of Pulsed Electric Fields on DNA Synthesis in an Osteoblast-Like Cell Line (UMR-106)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The study of the bioeffects of electromagnetic fields (EMFs) is an important national task in biological physics. Using EMFs to treat bone diseases involves electrical technology, biology, and medicine. But the effects of EMFs are still controversial and the mechanisms are not yet clear. Therefore, more effect is needed to detect the effects at the cellular and molecular levels. This paper investigates the effects of low-energy, low-frequency pulsed capacitively coupled electric fields (PCCEFs) on DNA synthesis in UMR-106 osteoblast-like cells. The equipment can generate 25250Hz frequency, 0300V amplitude and 0.2ms pulse width signal. DNA synthesis is judged by the uptake of 3H-thymidine (3H-TdR). The results showed that the response of UMR-106 cells to electric field exposure are characterized by: (a) a frequency window for increased DNA synthesis, with a peak near 125Hz; (b) decreased synthesis with increasing electric intensity with repression at 100V/cm and 25Hz.

  16. High Specific Energy Pulsed Electric Discharge Laser Research.

    Science.gov (United States)

    1975-12-01

    drop out excess water, filtered, dried, filtered again, and then pumped up to the storage bottle pressure (Fig. 47). At the exit of the high...pressure pump, an oil filter was used to remove any oil that may have been introduced by the compressor. Bottles were pumped up to 2000 psig...Lowder, R. S. , "Air-Combustion Product N2-C02 Electric Laser, " J. Appl. Phys. Lett. 26, 373 (1975). 5. Miller, D. J. and Millikan , R. C

  17. Fabrication, electrical characterization, and detection application of graphene-sheet-based electrical circuits.

    Science.gov (United States)

    Peng, Yitian; Lei, Jianping

    2014-01-01

    The distribution of potential, electric field, and gradient of square of electric field was simulated via a finite element method for dielectrophoresis (DEP) assembly. Then reduced graphene oxide sheets (RGOS)- and graphene oxide sheets (GOS)-based electrical circuits were fabricated via DEP assembly. The mechanically exfoliated graphene sheets (MEGS)-based electrical circuit was also fabricated for comparison. The electrical transport properties of three types of graphene-based electrical circuits were measured. The MEGS-based electrical circuit possesses the best electrical conductivity, and the GOS-based electrical circuit has the poorest electrical conductivity among all three circuits. The three types of electrical circuits were applied for the detection of copper ions (Cu(2+)). The RGOS-based electrical circuit can detect the Cu(2+) when the concentration of Cu(2+) was as low as 10 nM in solution. The GOS-based electrical circuit can only detect Cu(2+) after chemical reduction. The possible mechanism of electron transfer was proposed for the detection. The facile fabrication method and excellent performance imply the RGOS-based electrical circuit has great potential to be applied to metal ion sensors.

  18. Improved Pulse Detection from Head Motions Using DCT

    DEFF Research Database (Denmark)

    Irani, Ramin; Nasrollahi, Kamal; Moeslund, Thomas B.

    2014-01-01

    . To measure it, physicians traditionally, either sense the pulsations of some blood vessels or install some sensors on the body. In either case, there is a need for a physical contact between the sensor and the body to obtain the heartbeat rate. This might not be always feasible, for example, for applications...... like remote patient monitoring. In such cases, contactless sensors, mostly based on computer vision techniques, are emerging as interesting alternatives. This paper proposes such a system, in which the heartbeats (pulses) are detected by subtle motions that appear on the face due to blood circulation...

  19. Evidence that pulsed electric field treatment enhances the cell wall porosity of yeast cells.

    Science.gov (United States)

    Ganeva, Valentina; Galutzov, Bojidar; Teissie, Justin

    2014-02-01

    The application of rectangular electric pulses, with 0.1-2 ms duration and field intensity of 2.5-4.5 kV/cm, to yeast suspension mediates liberation of cytoplasmic proteins without cell lysis. The aim of this study was to evaluate the effect of pulsed electric field with similar parameters on cell wall porosity of different yeast species. We found that electrically treated cells become more susceptible to lyticase digestion. In dependence on the strain and the electrical conditions, cell lysis was obtained at 2-8 times lower enzyme concentration in comparison with control untreated cells. The increase of the maximal lysis rate was between two and nine times. Furthermore, when applied at low concentration (1 U/ml), the lyticase enhanced the rate of protein liberation from electropermeabilized cells without provoking cell lysis. Significant differences in the cell surface of control and electrically treated cells were revealed by scanning electron microscopy. Data presented in this study allow us to conclude that electric field pulses provoke not only plasma membrane permeabilization, but also changes in the cell wall structure, leading to increased wall porosity.

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

    Science.gov (United States)

    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.

  1. Cavitation in dielectric fluid in inhomogeneous pulsed electric field

    CERN Document Server

    Shneider, M N

    2013-01-01

    This paper proposes a method for studying the early stages of the cavitation development in arbitrary, non-stationary conditions. This method is based on the comparison of the results of calculations in the framework of a theoretical model of the liquid dielectrics motion in a strong non-uniform electric field and experiments with controlled parameters. This approach allows us to find the critical negative pressure, at which cavitation begins to develop, and to determine the values of the constants in the classical models of cavitation.

  2. Estimating of pulsed electric fields using optical measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Timothy McGuire; Chantler, Gary.

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  7. Rapid hardening induced by electric pulse annealing in nanostructured pure aluminum

    DEFF Research Database (Denmark)

    Zeng, Wei; Shen, Yao; Zhang, Ning

    2012-01-01

    Nanostructured pure aluminum was fabricated by heavy cold-rolling and then subjected to recovery annealing either by applying electric pulse annealing or by traditional air furnace annealing. Both annealing treatments resulted in an increase in yield strength due to the occurrence of a “dislocation...

  8. Conductive plastic film electrodes for Pulsed Electric Field (PEF) treatment : A proof of principle

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Boxtel, L.B.J. van; Hatt, V.; Wouters, P.C.; Coronel, P.; Ferreira, J.A.

    2010-01-01

    Nowadays Pulsed Electric Field (PEF) treatment of food needs to be performed prior to packaging, either hygienic or aseptic packaging is necessary. New techniques for PEF treatment after packaging can be considered when plastic conductive (film) electrodes can be integrated within the package, so th

  9. The effects of high-voltage pulse electric discharges on ion adsorption on activated carbons

    Science.gov (United States)

    Gafurov, M. M.; Sveshnikova, D. A.; Larin, S. V.; Rabadanov, K. Sh.; Shabanova, Z. E.; Yusupova, A. A.; Ramazanov, A. Sh.

    2008-07-01

    The effects of high-voltage pulse electric discharges (HPED) on sorption of boron and sulfate ions on activated carbons of different kinds (KM-2, BAU, DAK) were investigated. The effect of HPED activation on the sorption characteristics of the systems was found to be similar to the temperature effect.

  10. Conductive plastic film electrodes for Pulsed Electric Field (PEF) treatment : A proof of principle

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Boxtel, L.B.J. van; Hatt, V.; Wouters, P.C.; Coronel, P.; Ferreira, J.A.

    2010-01-01

    Nowadays Pulsed Electric Field (PEF) treatment of food needs to be performed prior to packaging, either hygienic or aseptic packaging is necessary. New techniques for PEF treatment after packaging can be considered when plastic conductive (film) electrodes can be integrated within the package, so

  11. Pulsed Electric Field for protein release of the microalgae Chlorella vulgaris and Neochloris oleoabundans

    NARCIS (Netherlands)

    Lam, 't Gerard; Postma, P.R.; Fernandes, D.A.; Timmermans, R.A.H.; Vermuë, M.H.; Barbosa, M.J.; Eppink, M.H.; Wijffels, R.H.; Olivieri, G.

    2017-01-01

    Pulsed Electric Field (PEF) is currently discussed as promising technology for mild and scalable cell disintegration of microalgae. In this study Chlorella vulgaris and Neochloris oleoabundans have been subjected to batch and continuous PEF treatments under a wide range of operating conditions

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  14. Inactivation of microorganisms within collagen gel biomatrices using pulsed electric field treatment.

    Science.gov (United States)

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

    2012-02-01

    Pulsed electric field (PEF) treatment was examined as a potential decontamination method for tissue engineering biomatrices by determining the susceptibility of a range of microorganisms whilst within a collagen gel. High intensity pulsed electric fields were applied to collagen gel biomatrices containing either Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, Candida albicans, Saccharomyces cerevisiae or the spores of Aspergillus niger. The results established varying degrees of microbial PEF susceptibility. When high initial cell densities (10(6)-10(7) CFU ml(-1)) were PEF treated with 100 pulses at 45 kV cm(-1), the greatest log reduction was achieved with S. cerevisiae (~6.5 log(10) CFU ml(-1)) and the lowest reduction achieved with S. epidermidis (~0.5 log(10) CFU ml(-1)). The results demonstrate that inactivation is influenced by the intrinsic properties of the microorganism treated. Further investigations are required to optimise the microbial inactivation kinetics associated with PEF treatment of collagen gel biomatrices.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cortese, Pietro; Dellacasa, Giuseppe; Gemme, Roberto [Department of Science and Advanced Technology, Eastern Piedmont University, Viale Teresa Michel 11, 15121-Alessandria (Italy); Bonetta, Sara; Bonetta, Silvia; Carraro, Elisabetta; Motta, Francesca [Department of Environmental and Life Science, Eastern Piedmont University, Viale Teresa Michel 11, 15121-Alessandria (Italy); Paganoni, Marco; Pizzichemi, Marco [Physics Department G. Occhialini, University of Milano-Bicocca, Piazza della Scienza 3, 20126-Milano (Italy)

    2011-06-15

    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 Universita 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{sup 9} Cfu/ml concentration suspended in a McIlvaine buffer (pH 7.2).

  16. Pre-breakdown cavitation development in the dielectric fluid in the inhomogeneous, pulsed electric fields

    CERN Document Server

    Shneider, Mikhail N

    2014-01-01

    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 ...

  17. Control of predators in industrial scale microalgae cultures with Pulsed Electric Fields.

    Science.gov (United States)

    Rego, D; Redondo, L M; Geraldes, V; Costa, L; Navalho, J; Pereira, M T

    2015-06-01

    This work describes the utilization of Pulsed Electric Fields to control the protozoan contamination of a microalgae culture, in an industrial 2.7 m(3) microalgae photobioreactor. The contaminated culture was treated with Pulsed Electric Fields, PEF, for 6h with an average of 900 V/cm, 65 μs pulses of 50 Hz. Working with recirculation, all the culture was uniformly exposed to the PEF throughout the assay. The development of the microalgae and protozoan populations was followed and the results showed that PEF is effective on the selective elimination of protozoa from microalgae cultures, inflicting on the protozoa growth halt, death or cell rupture, without affecting microalgae productivity. Specifically, the results show a reduction of the active protozoan population of 87% after 6h treatment and 100% after few days of normal cultivation regime. At the same time, microalgae growth rate remained unaffected.

  18. The neuronal response to electrical constant-amplitude pulse train stimulation: additive Gaussian noise.

    Science.gov (United States)

    Matsuoka, A J; Abbas, P J; Rubinstein, J T; Miller, C A

    2000-11-01

    Experimental results from humans and animals show that electrically evoked compound action potential (EAP) responses to constant-amplitude pulse train stimulation can demonstrate an alternating pattern, due to the combined effects of highly synchronized responses to electrical stimulation and refractory effects (Wilson et al., 1994). One way to improve signal representation is to reduce the level of across-fiber synchrony and hence, the level of the amplitude alternation. To accomplish this goal, we have examined EAP responses in the presence of Gaussian noise added to the pulse train stimulus. Addition of Gaussian noise at a level approximately -30 dB relative to EAP threshold to the pulse trains decreased the amount of alternation, indicating that stochastic resonance may be induced in the auditory nerve. The use of some type of conditioning stimulus such as Gaussian noise may provide a more 'normal' neural response pattern.

  19. An analogue sum and threshold neuron based on the quantum tunnelling amplification of electrical pulses

    Energy Technology Data Exchange (ETDEWEB)

    Samardak, A; Taylor, S [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom); Nogaret, A; Austin, J [Department of Computer Science, University of York, Heslington, York YO10 5DD (United Kingdom); Farrer, I; Ritchie, D A [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)], E-mail: A.R.Nogaret@bath.ac.uk

    2008-08-15

    We demonstrate a spatial neuron that sums and regenerates electrical pulses in real time. The neuron uses a monolithic web of micro-transmission lines to propagate electrical pulses to a 'soma' where they are regenerated via quantum tunnelling amplification. The gain of the neuron follows a sigmoid curve similar to the one that controls the firing of real neurons. We report on the dependence of the regeneration threshold on bias parameters and obtain a good fit of the measured threshold by computing the stability diagram of the soma. The neuron is shown to regenerate coincident pulses with a timing sensitivity of 10 {mu}s compared to milliseconds for real neurons. The present design demonstrates that the physics underpinning analogue computation in biological neurons has an equivalent in modern semiconductor structures.

  20. Self-resonant Coil for Contactless Electrical Conductivity Measurement under Pulsed Ultra-high Magnetic Fields

    CERN Document Server

    Nakamura, Daisuke; Takeyama, Shojiro

    2014-01-01

    In this study, we develop experimental apparatus for contactless electrical conductivity measurements under pulsed high magnetic fields over 100 T using a self-resonant-type high-frequency circuit. The resonant power spectra were numerically analyzed, and the conducted simulations showed that the apparatus is optimal for electrical conductivity measurements of materials with high electrical conductivity. The newly developed instruments were applied to a high-temperature cuprate superconductor La$_{2-x}$Sr$_x$CuO$_4$ to show conductivity changes in magnetic fields up to 102 T with a good signal-to-noise ratio. The upper critical field was determined with high accuracy.

  1. Electrical conductivity induced in insulators by pulsed radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ahrens, T.J.; Wooten, F.

    1976-06-01

    The minimum prompt photoconductivity induced by pulses of x rays, gamma rays, and energetic electrons in various amorphous and disordered insulating organic and inorganic materials is predicted on the basis of data for the scattering of hot electrons in solids and the band gap for insulators. For total doses of 3 x 10/sup 4/ to 30 x 10/sup 4/ rad or greater, the minimum prompt photoconductivity is predicted to be linear with dose rate, ..gamma.., and is given by sigma(..cap omega../sup -1/cm/sup -1/) = 5 x 10/sup -19/ rho/sub 0/..gamma../E/sup 2//sub g/, where rho/sub 0/ is the density (g/cm/sup 3/) and E/sub g/ is the optical band gap (eV). This formula agrees well with data for a variety of plastics, mica, and borosilicate glass under widely different irradiation conditions. The formula considerably underestimates absolute values of prompt conductivities observed for Al/sub 2/O/sub 3/, MgO, and certain plastics, because the model does not hold for ordered materials.

  2. Electric Insulation Detection Method for High-voltage Insulators

    Directory of Open Access Journals (Sweden)

    Wang Jiajun

    2013-07-01

    Full Text Available The principle of partial discharge detection is that through partial bridged discharge under high voltage electric field, it detects the inner air-filled cavity of high-voltage insulators. And it is a nondestructive detection method based on discharge magnitude to judge the insulation quality. The detecting system that adopts the partial discharge detection is more rigorous than testing system for electricity products, which must have small discharge capacity and higher sensitivity. This paper describes the principles of partial discharge detection and analysis insulation detection.

  3. Electrical Addressing and Temporal Tweezing of Localized Pulses in Passively Mode-Locked Semiconductor Lasers

    CERN Document Server

    Camelin, P; Marconi, M; Giudici, M

    2016-01-01

    We show that the pumping current is a convenient parameter for manipulating the temporal Localized Structures (LSs), also called localized pulses, found in passively mode-locked Vertical-Cavity Surface-Emitting Lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing to control the position and the dynamics of LSs. We show that the localized pulses drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on an finite timescale and breaks the parity invariance along the cavity, thus leading to a new paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. ...

  4. Strategies, Protections and Mitigations for Electric Grid from Electromagnetic Pulse Effects

    Energy Technology Data Exchange (ETDEWEB)

    Foster, Rita Ann [Idaho National Lab. (INL), Idaho Falls, ID (United States); Frickey, Steven Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Foster, Rita Ann [Idaho National Lab. (INL), Idaho Falls, ID (United States); Frickey, Steven Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    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. Size separation of DNA molecules by pulsed electric field dielectrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Nedelcu, S [National Institute for R and D in Microtechnologies, Str. Erou Iancu Nicolae 32B, PO Box 38-160, 023573 Bucharest (Romania); Watson, J H P [School of Physics and Astronomy, University of Southampton, Highfield, SO17 1BJ, Southampton (United Kingdom)

    2004-08-07

    In this paper we propose an electrode design and a switching pattern of the applied DC electrode potentials for a microfluidic device to be used in size separation of DNA molecules. Estimates on the separation resolution, which are based on numerical solutions of a Newton-type equation on time-averaged quantities, are presented for an input batch sample of DNA fragments with sizes up to 220 base pairs (bp). The active area of the device (which can be microfabricated by standard photolitographic techniques) is a channel 6 {mu}m wide, 8 {mu}m deep and 150 {mu}m in length, flanked by 23 plane parallel integrated electrodes, individually addressed with low DC voltages, up to {+-} 25 V. In the active area a time-dependent non-uniform electric field, or a travelling dielectrophoretic wave (TDW) is being produced. In order to enhance the separation resolution, the polarization DC potentials are switched with a relatively high frequency ({approx} 10{sup -7} s), which is chosen accordingly with the buffer conductivity and dielectric constants of the fluid and particles. Since the external field is of DC type, we put forward an explanatory model of the dielectric response of the DNA to the time-dependent applied field. We then numerically investigate the size-dependent response of the DNA in a low conductivity buffer ({approx}0.01 {omega}{sup -1} m{sup -1}) under the influence of the electric field, which is calculated by means of the method of moments. The results of the computer modelling indicate the existence of a threshold value for the size of the successfully transported molecules, which can be adjusted by varying the velocity of the dielectrophoretic wave produced by the system. The estimated error in selecting a chosen group of molecules with sizes above a specified value is about 5 bp, while the processing times are of the order of hundred of seconds.

  7. High-efficiency gene transfer into skeletal muscle mediated by electric pulses

    DEFF Research Database (Denmark)

    Mir, L M; Bureau, M F; Gehl, J;

    1999-01-01

    Gene delivery to skeletal muscle is a promising strategy for the treatment of muscle disorders and for the systemic secretion of therapeutic proteins. However, present DNA delivery technologies have to be improved with regard to both the level of expression and interindividual variability. We...... report very efficient plasmid DNA transfer in muscle fibers by using square-wave electric pulses of low field strength (less than 300 V/cm) and of long duration (more than 1 ms). Contrary to the electropermeabilization-induced uptake of small molecules into muscle fibers, plasmid DNA has to be present...... in the tissue during the electric pulses, suggesting a direct effect of the electric field on DNA during electrotransfer. This i.m. electrotransfer method increases reporter and therapeutic gene expression by several orders of magnitude in various muscles in mouse, rat, rabbit, and monkey. Moreover, i...

  8. Investigating membrane nanoporation induced by bipolar pulsed electric fields via second harmonic generation

    Science.gov (United States)

    Moen, E. K.; Ibey, B. L.; Beier, H. T.; Armani, A. M.

    2016-09-01

    Electric pulses have become an effective tool for transporting cargo (DNA, drugs, etc.) across cell membranes. This enhanced transport is believed to occur through temporary pores formed in the plasma membrane. Traditionally, millisecond duration, monopolar (MP) pulses are used for electroporation, but bipolar (BP) pulses have proven equally effective as MP pulses with the added advantage of less cytotoxicity. With the goal of further reducing cytotoxic effects and inducing non-thermal, intra-cellular effects, researchers began investigating reduced pulse durations, pushing into the nanosecond regime. Cells exposed to these MP, nanosecond pulsed electric fields (nsPEFs) have shown increased repairable membrane permeability and selective channel activation. However, attempts to improve this further by moving to the BP pulse regime has proven unsuccessful. In the present work, we use second harmonic generation imaging to explore the structural effects of bipolar nsPEFs on the plasma membrane. By varying the temporal spacing between the pulse phases over several orders of magnitude and comparing the response to a single MP case, we systematically examine the disparity in cellular response. Our circuit-based model predicts that, as the temporal spacing increases several orders of magnitude, nanoporation increases and eventually exceeds the MP case. On the whole, our experimental data agree with this assertion; however, a detailed analysis of the data sets demonstrates that biological processes may play a larger role in the observed response than previously thought, dominating the effect for temporal spacing up to 5 μs. These findings could ultimately lead to understanding the biophysical mechanism underlying all electroporation.

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

    Science.gov (United States)

    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%.

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

    Science.gov (United States)

    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.

  11. Electrochemical reaction and oxidation of lecithin under pulsed electric fields (PEF) processing.

    Science.gov (United States)

    Zhao, Wei; Yang, Ruijin; Liang, Qi; Zhang, Wenbin; Hua, Xiao; Tang, Yali

    2012-12-12

    Pulsed electric fields (PEF) processing is a promising nonthermal food preservation technology, which is ongoing from laboratory and pilot plant scale levels to the industrial level. Currently, greater attention has been paid to side effects occurring during PEF treatment and the influences on food qualities and food components. The present study investigated the electrochemical reaction and oxidation of lecithin under PEF processing. Results showed that electrochemical reaction of NaCl solutions at different pH values occurred during PEF processing. Active chlorine, reactive oxygen, and free radicals were detected, which were related to the PEF parameters and pH values of the solution. Lecithin extracted from yolk was further selected to investigate the oxidation of food lipids under PEF processing, confirming the occurrence of oxidation of lecithin under PEF treatment. The oxidative agents induced by PEF might be responsible for the oxidation of extracted yolk lecithin. Moreover, this study found that vitamin C as a natural antioxidant could effectively quench free radicals and inhibit the oxidation of lipid in NaCl and lecithin solutions as model systems under PEF processing, representing a way to minimize the impact of PEF treatment on food qualities.

  12. Study of Cellular Experiment of Electric Pulse Imposed on Cancer Cell

    Institute of Scientific and Technical Information of China (English)

    XIONGLan; HUYa; 等

    2002-01-01

    The objective of the study is the cytocidal and inhibitory effect of energy-controllable pulse on ovarian cancer cell line SKOV3.Ovarian cancer cell suspension were treated by electric pulse with different parameters,.The inhibitory rate(IR) was assayed by modified colorimetric MTT methods,the growth curves of two test groups and one control group were also measured.and the ultrasturctureal changes were observed under electron microscopy(EM) and scan electron microscopy (SEM),It was found that the treated SKOV3 cell proliferated more slowly.IR was increased with the enhancement of pulse paramters,The ultrastructural study showed that morphological changes occured obviously.Swollen mitochondria,fracutured ridges,cytoplasmic vacuoles and membrane holes appeard in most of the processed cells,and a part of bilayer membrane was ruptured.It is indicated that irreversible electric breakdown occurred in some of the treated cells,and the electric pulse could kill cancer cell and inhibit its recovery and growth.

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

    Science.gov (United States)

    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 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.

  14. Electrical detection of spin coherence in microcrystalline pin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Behrends, Jan [Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Berlin (Germany); Department of Physics, University of Utah, Salt Lake City, UT (United States); Boehme, Christoph; Lips, Klaus [Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Berlin (Germany); Haas, Stefan [Institute of Photovoltaics, Forschungszentrum Juelich, Juelich (Germany); Rech, Bernd [Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Berlin (Germany); Institute of Photovoltaics, Forschungszentrum Juelich, Juelich (Germany)

    2007-07-01

    Defects in the band gap of hydrogenated microcrystalline silicon ({mu}cSi:H) pin solar cells, even at low concentrations, can act as recombination centres and thus, they can influence the electronic properties of the device significantly. A powerful technique to investigate these recombination processes is pulsed electrically detected magnetic resonance (pEDMR). This method is based on transient photocurrent measurements after varying specific recombination or transport rates and reveals information about the microscopic mechanisms of recombination and transport that involve paramagnetic states. In this study we report on the application of pEDMR on state-of-the-art {mu}c-Si:H pin solar cells prepared on ZnO coated glass. An adapted contact structure allows the observation of Rabi oscillations in the photocurrent at low temperatures (T=10 K) reflecting coherent spin motion. The coherence time is found to be on the order of several hundred nanoseconds and is determined by recombination. A Fourier analysis of the observed Rabi oscillations allows a distinction between the involved recombination processes. A discussion on the different recombination mechanisms in {mu}c-Si:H cells is given.

  15. Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Linscott, Ivan; Strauss, David; Lauben, David [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Srama, Ralf; Mocker, Anna; Bugiel, Sebastian [Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart (Germany)

    2013-09-15

    Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (∼10{sup 28} m{sup −3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

  16. Exploring the Effects of Pulsed Electric Field Processing Parameters on Polyacetylene Extraction from Carrot Slices

    Directory of Open Access Journals (Sweden)

    Ingrid Aguiló-Aguayo

    2015-03-01

    Full Text Available The effects of various pulsed electric field (PEF parameters on the extraction of polyacetylenes from carrot slices were investigated. Optimised conditions with regard to electric field strength (1–4 kV/cm, number of pulses (100–1500, pulse frequency (10–200 Hz and pulse width (10–30 μs were identified using response surface methodology (RSM to maximise the extraction of falcarinol (FaOH, falcarindiol (FaDOH and falcarindiol-3-acetate (FaDOAc from carrot slices. Data obtained from RSM and experiments fitted significantly (p < 0.0001 the proposed second-order response functions with high regression coefficients (R2 ranging from 0.82 to 0.75. Maximal FaOH (188%, FaDOH (164.9% and FaDOAc (166.8% levels relative to untreated samples were obtained from carrot slices after applying PEF treatments at 4 kV/cm with 100 number of pulses of 10 μs at 10 Hz. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E% ranging from 0.68% to 3.58%.

  17. Exploring the effects of pulsed electric field processing parameters on polyacetylene extraction from carrot slices.

    Science.gov (United States)

    Aguiló-Aguayo, Ingrid; Abreu, Corina; Hossain, Mohammad B; Altisent, Rosa; Brunton, Nigel; Viñas, Inmaculada; Rai, Dilip K

    2015-03-02

    The effects of various pulsed electric field (PEF) parameters on the extraction of polyacetylenes from carrot slices were investigated. Optimised conditions with regard to electric field strength (1-4 kV/cm), number of pulses (100-1500), pulse frequency (10-200 Hz) and pulse width (10-30 μs) were identified using response surface methodology (RSM) to maximise the extraction of falcarinol (FaOH), falcarindiol (FaDOH) and falcarindiol-3-acetate (FaDOAc) from carrot slices. Data obtained from RSM and experiments fitted significantly (p < 0.0001) the proposed second-order response functions with high regression coefficients (R2) ranging from 0.82 to 0.75. Maximal FaOH (188%), FaDOH (164.9%) and FaDOAc (166.8%) levels relative to untreated samples were obtained from carrot slices after applying PEF treatments at 4 kV/cm with 100 number of pulses of 10 μs at 10 Hz. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E%) ranging from 0.68% to 3.58%.

  18. Comparison of phenolic compounds of orange juice processed by pulsed electric fields (PEF) and conventional thermal pasteurisation.

    Science.gov (United States)

    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.

  19. Is pulsed electric field still effective for RNA separation in capillary electrophoresis?

    Science.gov (United States)

    Li, Zhenqing; Dou, Xiaoming; Ni, Yi; Chen, Qinmiao; Cheng, Shuyi; Yamaguchi, Yoshinori

    2012-03-16

    Pulsed field capillary electrophoresis (PFCE) is a predominant technique to cope with difficulties in resolving large DNA strands, yet it is still unclear whether pulsed electric field is effective for the separation of higher mass RNA. In this paper we focused on the role of pulsed electric field in large RNA fragments analysis by comparing RNA separation performance in PFCE with that in constant field CE. Separation performance in terms of migration mobility, plate numbers, resolution, and selectivity has been tested for the analysis of RNA from 0.1 to 10.0 kilo nucleotide (knt) under different electrophoretic conditions. Denaturation, important to obtain uniform and identifiable peaks, was accomplished by heating the sample in 4.0M urea prior to analysis and the presence of 4.0M urea in the electrophoresis buffer. Results demonstrate that unlike DNA in PFCE, the pulsed electric field mainly affects the separation performance of RNA between 0.4 and 2.0 knt. The migration mobility of long RNA fragments is not a strong function of modulation depth and pulsed frequency. Moreover, the logarithm of RNA mobility is almost inversely proportional to the logarithm of molecule size up to 6.0 knt with correlation coefficient higher than 0.99 in all the polymer concentrations measured here. Resonance frequency of RNA in PFCE was also observed. While these initial experiments show no distinct advantages of using PFCE for RNA separation, they do take further step toward characterizing the migration behavior of RNA under pulsed field conditions.

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

    Science.gov (United States)

    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.

  1. Influence of laser pulse on the autocorrelation function of H in a strong electric field

    Institute of Scientific and Technical Information of China (English)

    Lifei Wang; Guangcan Yang

    2009-01-01

    The autocorrelation function of electronic wave packet of hydrogen atom in a strong electric field below the zero-field ionization threshold is investigated in the formalism of semiclassical theory. It is found that the autocorrelation depends on the applied laser pulse significantly. In the case of narrow laser pulse, the reviving peaks in the autocorrelation can be attributed to the closed orbits of electrons, which are related to the classical dynamics of the system. But this correspondence is wiped out with increasing the laser width because of the interference among the adjacent reviving peaks.

  2. Exponentially Decaying Electric Pulses for Improving Radioactive Iodine uptake in human thyroid cancer cells

    Directory of Open Access Journals (Sweden)

    Amr A. Abd-Elghany

    2016-09-01

    Full Text Available Radioactive iodine (radioiodine is an effective nuclear medicine treatment used to eradicate thyroid cancer cells. The problem was the inability of thyroid cells to retain radioiodine which causes the thyroid cancer cells to be resistant to radioactive iodine treatment. Therefore, there are different methods that have been established to enhance the radioiodine uptake within the thyroid cancer cells for therapeutic purposes. Exposure of human cells to exponentially decaying high intensity, short duration electric pulses permeabilizes the plasma membrane to impermeable molecules. Electroporation is a physical modality that involves high intensity, short duration electric pulses to facilitate the entry of impermeable molecules by increasing the plasma membrane permeability. The purpose of this study was to use exponentially decaying high intensity, short duration electric pulses in incorporating radioactive iodine into non-iodine retaining follicular thyroid carcinoma cell line FTC133. Results showed that the uptake of radioiodine by electroporation has a dependence on the electric field, external concentration of the iodine, time and the temperature of incubation. The incorporated radioiodine was retained over a period of 24 h. The permanent concentration of the incorporated iodine may have a significant effect on the tumoricidal properties if approved in vivo.

  3. Detection of vacuum birefringence using intense laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Luiten, Andre N. [School of Physics M013, University of Western Australia, Nedlands, Western Australia 6009 (Australia)]. E-mail: andre@physics.uwa.edu.au; Petersen, Jesse C. [School of Physics M013, University of Western Australia, Nedlands, Western Australia 6009 (Australia)

    2004-10-04

    We propose a novel technique that promises hope of being the first to directly detect a polarization of the quantum electrodynamic (QED) vacuum. The technique exploits the high fields associated with ultra-short pulses of light stored in low dispersion optical resonators. We show that the technique circumvents the need for large-scale liquid helium cooled magnets, and more importantly avoids the experimental pitfalls that plague existing experimental approaches that use these magnets. The new technique has a predicted birefringence measurement sensitivity of {delta}n{approx}10-20 in a 1 s measurement. Currently available optics and lasers will enable observation of vacuum polarization in an experiment of only a few days in duration.

  4. Detection of vacuum birefringence using intense laser pulses

    Science.gov (United States)

    Luiten, Andre N.; Petersen, Jesse C.

    2004-10-01

    We propose a novel technique that promises hope of being the first to directly detect a polarization of the quantum electrodynamic (QED) vacuum. The technique exploits the high fields associated with ultra-short pulses of light stored in low dispersion optical resonators. We show that the technique circumvents the need for large-scale liquid helium cooled magnets, and more importantly avoids the experimental pitfalls that plague existing experimental approaches that use these magnets. The new technique has a predicted birefringence measurement sensitivity of Δn∼10 in a 1 s measurement. Currently available optics and lasers will enable observation of vacuum polarization in an experiment of only a few days in duration.

  5. Improvements in detection system for pulse radiolysis facility

    CERN Document Server

    Rao, V N; Manimaran, P; Mishra, R K; Mohan, H; Mukherjee, T; Nadkarni, S A; Sapre, A V; Shinde, S J; Toley, M

    2002-01-01

    This report describes the improvements made in the detection system of the pulse radiolysis facility based on a 7 MeV Linear Electron Accelerator (LINAC) located in the Radiation Chemistry and Chemical Dynamics Division of Bhabha Atomic Research Centre. The facility was created in 1986 for kinetic studies of transient species whose absorption lies between 200 and 700 nm. The newly developed detection circuits consist of a silicon (Si) photodiode (PD) detector for the wavelength range 450-1100 nm and a germanium (Ge) photodiode detector for the wavelength range 900-1600 nm. With these photodiode-based detection set-up, kinetic experiments are now routinely carried out in the wavelength range 450-1600 nm. The performance of these circuits has been tested using standard chemical systems. The rise time has been found to be 150 ns. The photo-multiplier tube (PMT) bleeder circuit has been modified. A new DC back-off circuit has been built and installed in order to avoid droop at longer time scales. A steady baselin...

  6. Analysis of tetracycline antibiotics using HPLC with pulsed amperometric detection.

    Science.gov (United States)

    Charoenraks, Thiraporn; Chuanuwatanakul, Suchada; Honda, Kensuke; Yamaguchi, Yoko; Chailapakul, Orawon

    2005-03-01

    The analysis of tetracycline, oxytetracyline, chlortetracycline and doxycycline by high-performance liquid chromatography with pulsed amperometric detection using an anodized boron-doped diamond thin film (BDD) electrode is originally reported. The analyses were carried out using the mobile phase, phosphate buffer (0.01 M, pH 2.5)-acetonitrile (80:20; v/v), on a C18 column (250 x 4.6 mm i.d., 5 microm) at a flow rate of 1.0 mL/min. The optimal PAD waveform parameters at the anodized BDD were 1.5 V (versus Ag/AgCl) detection potential (E(det)) for 290 ms (200 ms delay time and 90 ms integration time), 2.0 V (versus Ag/AgCl) oxidation potential (E(oxd)) for 200 ms oxidation time (t(oxd)) and 0.4 V (versus Ag/AgCI) reduction potential (E(red)) for 200 ms reduction time (t(red)). The proposed method showed the simultaneous determination of tetracycline, oxytetracyline, chlortetracycline and doxycycline with a linear range of 0.1 - 100 microg/mL, detection limits of 0.05 - 0.1 microg/mL and recoveries of 70.8 - 96.0%. The application of this method to real samples was demonstrated and validated using a shrimp sample.

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

    Science.gov (United States)

    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

  8. Pulsed direct current electric fields enhance osteogenesis in adipose-derived stromal cells.

    Science.gov (United States)

    Hammerick, Kyle E; James, Aaron W; Huang, Zubin; Prinz, Fritz B; Longaker, Michael T

    2010-03-01

    Adipose-derived stromal cells (ASCs) constitute a promising source of cells for regenerative medicine applications. Previous studies of osteogenic potential in ASCs have focused on chemicals, growth factors, and mechanical stimuli. Citing the demonstrated role electric fields play in enhancing healing in bone fractures and defects, we investigated the ability of pulsed direct current electric fields to drive osteogenic differentiation in mouse ASCs. Employing 50 Hz direct current electric fields in concert with and without osteogenic factors, we demonstrated increased early osteoblast-specific markers. We were also able to establish that commonly reported artifacts of electric field stimulation are not the primary mediators of the observed effects. The electric fields caused marked changes in the cytoskeleton. We used atomic force microscopy-based force spectroscopy to record an increase in the cytoskeletal tension after treatment with electric fields. We abolished the increased cytoskeletal stresses with the rho-associated protein kinase inhibitor, Y27632, and did not see any decrease in osteogenic gene expression, suggesting that the pro-osteogenic effects of the electric fields are not transduced via cytoskeletal tension. Electric fields may show promise as candidate enhancers of osteogenesis of ASCs and may be incorporated into cell-based strategies for skeletal regeneration.

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

    Directory of Open Access Journals (Sweden)

    Caroline Garcia Forlim

    Full Text Available 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.

  10. The kinetics of inactivation of spheroidal microbial cells by pulsed electric fields

    CERN Document Server

    Lebovka, Nikolai

    2007-01-01

    The nature of non-exponential kinetics in microbial cells inactivation by pulsed electric fields (PEF) is discussed. It was demonstrated that possible mechanism of non-exponential kinetics can be related to orientational disorder in suspension of microbial cells of anisotropic form. A numerical studies of spheroidal cell suspensions was carried out. The most pronounced deviations from the exponential kinetics were observed for disordered suspensions of prolate spheroids at small electric field strength $E$ or at large aspect ratio $a$. For partially oriented suspensions, efficiency of inactivation enhances with increasing of order parameter and field strength. A possibility of the PEF-induced orientational ordering in microbial suspensions is discussed.

  11. Fast phase transitions induced by picosecond electrical pulses on phase change memory cells

    Science.gov (United States)

    Wang, W. J.; Shi, L. P.; Zhao, R.; Lim, K. G.; Lee, H. K.; Chong, T. C.; Wu, Y. H.

    2008-07-01

    The reversible and fast phase transitions induced by picosecond electrical pulses are observed in the nanostructured GeSbTe materials, which provide opportunities in the application of high speed nonvolatile random access memory devices. The mechanisms for fast phase transition are discussed based on the investigation of the correlation between phase transition speed and material size. With the shrinkage of material dimensions, the size effects play increasingly important roles in enabling the ultrafast phase transition under electrical activation. The understanding of how the size effects contribute to the phase transition speed is of great importance for ultrafast phenomena and applications.

  12. Optimisation extraction of chondroitin sulfate from fish bone by high intensity pulsed electric fields.

    Science.gov (United States)

    He, Guidan; Yin, Yongguang; Yan, Xiaoxia; Yu, Qingyu

    2014-12-01

    High intensity pulsed electric fields (PEF) was used to extract chondroitin sulphate (CS) from fish bone. Results show that PEF extraction speed is much faster, and the content of CS is much higher compared with traditional methods. Variation of PEF parameters and the content of CS were determined by single factor experiments. The processing conditions were optimised by quadratic general rotary unitised design experiments. The maximum yield of 6.92 g/L was achieved under the following conditions: material-liquid ratio of 1:15 g/mL, electric field intensity of 16.88 kV/cm, pulse number of 9, and NaOH concentration of 3.24%. The purity of CS was analysed by agarose gel electrophoresis. CS purity was high, and the extract did not contain any other glycosaminoglycans. PEF can be widely used to extract CS with non-thermal performance, high speed, and low pollution.

  13. The influence of size and shape of microorganism on pulsed electric field inactivation.

    Science.gov (United States)

    El-Hag, Ayman H; Jayaram, Shesha H; Gonzalez, Oscar Rodriguez; Griffiths, M W

    2011-09-01

    In this paper the effect of microorganism size and shape on the killing efficiency of pulsed electric field (PEF) is investigated both experimentally and using a transient finite element program. The effect of cell size, membrane thickness, cell shape (spherical, elliptical, and cylindrical) on the calculated transmembrane voltage is studied. It has been found that both the cell size and cell membrane thickness have significant effect on the induced field across the cell membrane. The findings of the simulation results have been evaluated by comparing the trends with some experimental results. Five different types of microorganisms that have different shapes and dimensions have been inoculated with water at a conductivity level of 100 μS/cm and have been treated with the application of a pulsed electric field of 70 kV/cm. Significant difference in bacteria reduction was noticed between the treated cells which could be attributed to the cell size and shape.

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

    Science.gov (United States)

    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, 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.

  15. analysis of large electromagnetic pulse simulators using the electric field integral equation method in time domain

    CERN Document Server

    Jamali, J; Moini, R; Sadeghi, H

    2002-01-01

    A time-domain approach is presented to calculate electromagnetic fields inside a large Electromagnetic Pulse (EMP) simulator. This type of EMP simulator is used for studying the effect of electromagnetic pulses on electrical apparatus in various structures such as vehicles, a reoplanes, etc. The simulator consists of three planar transmission lines. To solve the problem, we first model the metallic structure of the simulator as a grid of conducting wires. The numerical solution of the governing electric field integral equation is then obtained using the method of moments in time domain. To demonstrate the accuracy of the model, we consider a typical EMP simulator. The comparison of our results with those obtained experimentally in the literature validates the model introduced in this paper.

  16. Noise signals and carrier modulation arising in electrical cables during nuclear pulse irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Both, E.; Bruemmer, H. P.; Lascaro, C. P.; Newberg, J.; Schlosser, W.

    1963-03-15

    Electrical noise signals generated in coaxial and other cables by pulsed nuclear radiation were measured as a function of applied voltage and exposure history. In consecutive exposures the signal magnitude and polarity was found to be strongly affected by training and memory effects. Unexpectedly large signals in the cable shield were identified as the cause for oscillatory signals in the center conductor and for the occurrence of parasitic leakage currents in nearby conductors. A r-f signal transmitted through RG62 A/U cable undergoes a temporary attenuation during the radiation pulse while it passes through RG59 B/U without measurable degradation. Definite rules are given for minimizing cable noise signals in nuclear pulse radiation measurements. (auth)

  17. Measurements of Electric Field in a Nanosecond Pulse Discharge by 4-WAVE Mixing

    Science.gov (United States)

    Baratte, Edmond; Adamovich, Igor V.; Simeni Simeni, Marien; Frederickson, Kraig

    2017-06-01

    Picosecond four-wave mixing is used to measure temporally and Picosecond four-wave mixing is used to measure temporally and spatially resolved electric field in a nanosecond pulse dielectric discharge sustained in room air and in an atmospheric pressure hydrogen diffusion flame. Measurements of the electric field, and more precisely the reduced electric field (E/N) in the plasma is critical for determination rate coefficients of electron impact processes in the plasma, as well as for quantifying energy partition in the electric discharge among different molecular energy modes. The four-wave mixing measurements are performed using a collinear phase matching geometry, with nitrogen used as the probe species, at temporal resolution of about 2 ns . Absolute calibration is performed by measurement of a known electrostatic electric field. In the present experiments, the discharge is sustained between two stainless steel plate electrodes, each placed in a quartz sleeve, which greatly improves plasma uniformity. Our previous measurements of electric field in a nanosecond pulse dielectric barrier discharge by picosecond 4-wave mixing have been done in air at room temperature, in a discharge sustained between a razor edge high-voltage electrode and a plane grounded electrode (a quartz plate or a layer of distilled water). Electric field measurements in a flame, which is a high-temperature environment, are more challenging because the four-wave mixing signal is proportional to the to square root of the difference betwen the populations of N2 ground vibrational level (v=0) and first excited vibrational level (v=1). At high temperatures, the total number density is reduced, thus reducing absolute vibrational level populations of N2. Also, the signal is reduced further due to a wider distribution of N2 molecules over multiple rotational levels at higher temperatures, while the present four-wave mixing diagnostics is using spectrally narrow output of a ps laser and a high

  18. Dose-Dependent Thresholds of 10-ns Electric Pulse Induced Plasma Membrane Disruption and Cytotoxicity in Multiple Cell Lines

    Science.gov (United States)

    2011-01-01

    SJ, Fox PM, Rec LJ, Somers K, Stark RH, et al. (2002) Nanosecond Pulsed Electric Field (nsPEF) Effects on Cells and Tissues: Apoptosis Induction and...and a case report of intense nanosecond pulsed electric field as a local therapy for human malignancies. Int J Cancer 121: 675–682. 22. Nuccitelli R...Chen X, Pakhomov AG, Baldwin WH, Sheikh S, et al. (2009) A new pulsed electric field therapy for melanoma disrupts the tumor’s blood supply and causes

  19. Effects of combined exposure of Micrococcus luteus to nisin and pulsed electric fields

    NARCIS (Netherlands)

    Dutreux, N.; Notermans, S.; Góngora-Nieto, M.M.; Barbosa-Cánovas, G.V.; Swanson, B.G.

    2000-01-01

    Death and injury following exposure of Micrococcus luteus to nisin and pulsed electric field (PEF) treatment were investigated in phosphate buffer (pH 6.8, σ = 4.8 ms/cm at 20°C). Four types of experiment were carried out, a single treatment with nisin (100 IU/ml at 20°C for 2 h), a single PEF treat

  20. A comparison of electrical and photonic pulse generation for IR-UWB on fiber links

    DEFF Research Database (Denmark)

    Rodes Lopez, Roberto; Caballero Jambrina, Antonio; Yu, Xianbin

    2010-01-01

    We present and compare experimental results for electrical and photonic generation of 2-Gb/s pulses for impulse radio ultra-wideband on fiber transmission systems based on direct current modulation of a semiconductor laser diode and external optical injection of a semiconductor laser diode......, respectively. We assess the performance of the two generation approaches in terms of bit-error rate after propagation over 20 km of optical fiber followed by wireless transmission....

  1. Unidirectional optical pulse propagation equation for materials with both electric and magnetic responses

    Science.gov (United States)

    Kinsler, Paul

    2010-02-01

    I derive unidirectional wave equations for fields propagating in materials with both electric and magnetic dispersion and nonlinearity. The derivation imposes no conditions on the pulse profile except that the material modulates the propagation slowly, that is, that loss, dispersion, and nonlinearity have only a small effect over the scale of a wavelength. It also allows a direct term-to-term comparison of the exact bidirectional theory with its approximate unidirectional counterpart.

  2. Compaction of tool steels by pulsed electric current (PECS) sintering process

    OpenAIRE

    Postal, Stefano

    2014-01-01

    This study had two major purposes: the microstructural investigation of High Chromium White Iron (HCWI) sintered with Pulsed Electric Current Sintering (PECS) and the evaluation of the abrasion resistance of high chromium white iron mixed with different amounts of Hadfield Steel. The objective was to obtain dense high chromium white iron compacts with fine and uniform carbide and grain structure. The materials included in the study were gas atomized high chromium white iron (2.60 wt% C, 19.48...

  3. Electrical detection of spin coherence in silicon.

    Science.gov (United States)

    Boehme, Christoph; Lips, Klaus

    2003-12-12

    Experimental evidence is presented showing that photocurrents in silicon can be used as highly sensitive readout probes for coherent spin states of localized electrons, the prime candidates for quantum bits in various semiconductor based quantum computer concepts. Conduction electrons are subjected to fast Rabi oscillation induced by means of pulsed electron spin resonance. The collective spin motion of the charge carrier ensemble is reflected by a spin-dependent recombination rate and therefore by the sample conductivity. Because of inhomogeneities, the Rabi oscillation dephases rapidly. However, a microwave induced rephasing is possible causing an echo effect whose intensity contains information about the charge carrier spin state and the coherence decay.

  4. Regeneration and control of human fibroblast cell density by intermittently delivered pulsed electric fields.

    Science.gov (United States)

    Golberg, Alexander; Bei, Marianna; Sheridan, Robert L; Yarmush, Martin L

    2013-06-01

    Proliferative scarring is a human disease with neither available effective treatment nor relevant animal model. One of the hypotheses for scar formation involves deregulation of fibroblast signaling and delayed apoptosis. Here, we introduce a new chemical-free method for fibroblast density control in culture by intermittently delivered pulsed electric fields (IDPEF), which cause irreversible damage to cell membranes. Using 5-100 pulses with electric field strength of 150 V/mm, pulse duration 70 µs, and frequency of 1 Hz, we investigated the effects of PEF application on growth, death, and regeneration of normal human dermal fibroblasts in culture. We found that the fraction of fibroblasts that survive depends on the number of pulses applied and follows a Weibull distribution. We have successfully developed an IDPEF protocol that controls fibroblasts density in culture. Specifically, through application of IDPEF every 72 h for 12 days, we maintain a normal human dermal fibroblast density in the 3.1 ± 0.2 × 10(5) -1.4 ± 0.2 × 10(5)  cell/mL range. Our results suggest that IDPEFs may prove useful as a non-chemical method for fibroblast density control in human wound healing.

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

    Directory of Open Access Journals (Sweden)

    Tiago André Fontoura de MELO

    2016-01-01

    Full Text Available Abstract 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.

  6. Fast Change Point Detection for Electricity Market Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Berkeley, UC; Gu, William; Choi, Jaesik; Gu, Ming; Simon, Horst; Wu, Kesheng

    2013-08-25

    Electricity is a vital part of our daily life; therefore it is important to avoid irregularities such as the California Electricity Crisis of 2000 and 2001. In this work, we seek to predict anomalies using advanced machine learning algorithms. These algorithms are effective, but computationally expensive, especially if we plan to apply them on hourly electricity market data covering a number of years. To address this challenge, we significantly accelerate the computation of the Gaussian Process (GP) for time series data. In the context of a Change Point Detection (CPD) algorithm, we reduce its computational complexity from O($n^{5}$) to O($n^{2}$). Our efficient algorithm makes it possible to compute the Change Points using the hourly price data from the California Electricity Crisis. By comparing the detected Change Points with known events, we show that the Change Point Detection algorithm is indeed effective in detecting signals preceding major events.

  7. Effect of pulsed electric field on the rheological and colour properties of soy milk.

    Science.gov (United States)

    Xiang, Bob Y; Simpson, Marian V; Ngadi, Michael O; Simpson, Benjamin K

    2011-12-01

    The effects of pulsed electric field (PEF) treatments on rheological and colour properties of soy milk were evaluated. Flow behaviour, viscosity and rheological parameters of PEF-treated soy milk were monitored using a controlled stress rheometer. For PEF treatments, electric field intensity of 18, 20 and 22 kV cm(-1) and number of pulses of 25, 50, 75 and 100 were used. For the measurements of rheological properties of soy milk shear rates between 0 and 200 s(-1) was used. The rheological behaviour of control and the PEF-treated soy milk were described using a power law model. The PEF treatments affected the rheological properties of soy milk. Apparent viscosity of soy milk increased from 6.62 to 7.46 (10(-3) Pa s) with increase in electric field intensity from 18 to 22 kV cm(-1) and increase in the number of pulses from 0 to 100. The consistency index (K) of soy milk also changed with PEF treatments. Lightness (L*), red/greenness (a*) and yellowness/blueness (b*) of soy milk were affected by PEF treatments.

  8. An assessment of potential applications with pulsed electric field in wines

    Directory of Open Access Journals (Sweden)

    Drosou Foteini

    2017-01-01

    Full Text Available Pulsed electric fields (PEF is a non-thermal processing technology that uses instantaneous, pulses of high voltage for a short period in the range of milliseconds to microseconds; the application of high intensity electric field on toasted wood chips leads to a quick diffusion of extractable molecules. Currently most PEF studies, in the field of oenology, have been focusing on the application of PEF as a pretreatment of grape musts by examining the microbial inactivation and the enhancement of polyphenol extraction. In this study a post-treatment of wine is introduced as method to enhance the wood flavor in the wine with a green noninvasive technology. Major phenolic aldehydes that have been identified as the characteristic compounds of oak volatile compounds were selected as markers and were analyzed instrumentally to compare the influence of PEF processing to non-treated samples. PEF treated samples brought about higher concentrations of the examined oak compounds in the samples treated with PEF, which may explain the advantages of its application. The modulation of the intensity of the electric field and the period of pulses influenced the concentrations of the volatile phenols that were leached out. Differences found between the assayed treatments indicate that PEF application could be a potential practice for a rapid extraction of volatile compounds from oak.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  10. EET research on the Al-22%Si alloy under the action of electric pulses

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the empirical electron theory of solids and molecules (EET), the phase valence electron structure parameters of Al-22%Si alloy are calculated, and the sensitivity of the bond network of Al-Si alloy melt to temperature (energy) and the effect of the sensitivity on the morphology are studied. The results show that the Si-Si clusters with larger nA in the slightly superheated Al-Si alloy melt supply the nucleation core to the primary silicon phase in the hypereutectic Al-22%Si alloy, and strongly generate the drag-like effect for the Al-Si clusters around them; that the variation of temperature significantly affects the stability of bonds of the core so that the solidified structure is changed; that the electric pulse applied to the alloy melt can irrecoverably alter the stability of Si-Si clusters, then the modifica- tion of the solidified structure morphology of alloys is generated; that the higher the energy of the electric pulse, the less stable the Si-Si clusters, and the more significant the electric pulse modification.

  11. Coherent time evolution of highly excited Rydberg states in pulsed electric field Opening a stringent way to selectively field-ionize the highly excited states

    CERN Document Server

    Tada, M; Ogawa, I; Funahashi, H; Yamamoto, K; Matsuki, S

    2000-01-01

    Coherent time evolution of highly excited Rydberg states in Rb (98 < n < 150) under pulsed electric field in high slew-rate regime was investigated with the field ionization detection. The electric field necessary to ionize the Rydberg states was found to take discrete values successively depending on the slew rate. Specifically the slew-rate dependence of the ionization field varies with the quantum defect value of the states, i.e. with the energy position of the states relative to the adjacent manifold. This discrete transitional behavior of the ionization field observed for the first time is considered to be a manifestation of the strong coherence effect in the time evolution of the Rydberg states in pulsed electric field and opens a new effective way to stringently select a low-l state from the nearby states by field ionization.

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

    Science.gov (United States)

    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.

  13. Detection of UV Pulse from Insulators and Application in Estimating the Conditions of Insulators

    Science.gov (United States)

    Wang, Jingang; Chong, Junlong; Yang, Jie

    2014-10-01

    Solar radiation in the band of 240-280 nm is absorbed by the ozone layer in the atmosphere, and corona discharges from high-voltage apparatus emit in air mainly in the 230-405 nm range of ultraviolet (UV), so the band of 240-280 nm is called UV Solar Blind Band. When the insulators in a string deteriorate or are contaminated, the voltage distribution along the string will change, which causes the electric fields in the vicinity of insulators change and corona discharge intensifies. An UV pulse detection method to check the conditions of insulators is presented based on detecting the UV pulse among the corona discharge, then it can be confirmed that whether there exist faulty insulators and whether the surface contamination of insulators is severe for the safe operation of power systems. An UV-I Insulator Detector has been developed, and both laboratory tests and field tests have been carried out which demonstrates the practical viability of UV-I Insulator Detector for online monitoring.

  14. Finite pulse effects on $e^{+}e^{-}$ pair creation from strong electric fields

    CERN Document Server

    Taya, Hidetoshi; Itakura, Kazunori

    2014-01-01

    We investigate electron-positron pair creation from the vacuum in a pulsed electric background field. Employing the Sauter-type pulsed field $E(t) = E_0 {\\rm sech}^2(t/\\tau)$ with height $E_0$ and width $\\tau$, we demonstrate explicitly the interplay between the non-perturbative and perturbative aspects of the pair creation in the background field. In the constant field limit (the long pulse limit), Schwinger's non-perturbative formula is reproduced, while in the short pulse limit the leading-order perturbative treatment is justified. We show that two dimensionless parameters $eE_0 \\tau^2$ and $eE_0 \\tau /m_e$ characterize the importance of multiple interactions with the fields and the transition from the perturbative to the non-perturbative regime. We also reveal that pair creation is enhanced compared to Schwinger's formula when the field strength is relativity weak $|eE_0|/m_e^2 \\lesssim 1$ and the pulse duration is relatively short $m\\tau \\lesssim 1$ and that the enhancement is predominantly described by ...

  15. Effect of pulsed electric fields on microbial inactivation and physico-chemical properties of whole porcine blood.

    Science.gov (United States)

    Boulaaba, Annika; Egen, Nathalie; Klein, Günter

    2014-04-01

    The objective of this study was to determine the lethal effectiveness of pulsed electric fields on the inactivation of the porcine blood endogenous microflora. Furthermore, the impact of pulsed electric field application on physico-chemical and sensory properties in this medium should be proved. Blood samples from a commercial abattoir in Germany were processed by a continuous pilot plant-pulsed electric field system at electric field strength of 11 kV/cm for treatment times of 163 and 209 µs. The applied pulse frequencies of 134 and 175 Hz correspond to an energy input of 91 and 114 kJ/kg, respectively. In these conditions, the effectiveness of pulsed electric field processing on microbial inactivation was limited: 1.35 log10 CFU/mL reduction of total aerobic plate count (p growth of total aerobic plate count (p electric field-treated blood samples. Pulsed electric field processing leads to a complete hemolysis of the red blood cells, in addition significant decreased L* (lightness), a* (redness) and b* (yellowness) values (p < 0.0001) were observed. Furthermore, changes in the sensory attributes color (changed from red to dark brown) and odor (changed from fresh to musty and tangy) were noticed.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. Developing nucleic acid-based electrical detection systems

    Directory of Open Access Journals (Sweden)

    Gabig-Ciminska Magdalena

    2006-03-01

    Full Text Available Abstract Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and requirements for an ideal detector suitable for nucleic acid analysis include high sensitivity and high specificity protocol that can be completed in a relatively short time offering at the same time low detection limit. Moreover, systems that can be miniaturized and automated present a significant advantage over conventional technology, especially if detection is needed in the field. Electrical system technology for nucleic acid-based detection is an enabling mode for making miniaturized to micro- and nanometer scale bio-monitoring devices via the fusion of modern micro- and nanofabrication technology and molecular biotechnology. The electrical biosensors that rely on the conversion of the Watson-Crick base-pair recognition event into a useful electrical signal are advancing rapidly, and recently are receiving much attention as a valuable tool for microbial pathogen detection. Pathogens may pose a serious threat to humans, animal and plants, thus their detection and analysis is a significant element of public health. Although different conventional methods for detection of pathogenic microorganisms and their toxins exist and are currently being applied, improvements of molecular-based detection methodologies have changed these traditional detection techniques and introduced a new era of rapid, miniaturized and automated electrical chip detection technologies into pathogen identification sector. In this review some developments and current directions in

  19. Electrical stimulation vs. pulsed and continuous-wave optical stimulation of the rat prostate cavernous nerves, in vivo

    Science.gov (United States)

    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.

  20. Electricity Price Forecasting Based on AOSVR and Outlier Detection

    Institute of Scientific and Technical Information of China (English)

    Zhou Dianmin; Gao Lin; Gao Feng

    2005-01-01

    Electricity price is of the first consideration for all the participants in electric power market and its characteristics are related to both market mechanism and variation in the behaviors of market participants. It is necessary to build a real-time price forecasting model with adaptive capability; and because there are outliers in the price data, they should be detected and filtrated in training the forecasting model by regression method. In view of these points, this paper presents an electricity price forecasting method based on accurate on-line support vector regression (AOSVR) and outlier detection. Numerical testing results show that the method is effective in forecasting the electricity prices in electric power market.

  1. Optoelectronics Generation and Detection of Intense Terahertz Electromagnetic Pulses.

    Science.gov (United States)

    2007-11-02

    GaAs p-i-n diodes 19 C. Study of the physical mechanism of THz generation in bulk GaAs 19 D. Observation of Gunn Oscillation by triggering a vertical... Gunn diode with 25 femtosecond optical pulses IV. Tunable narrowband THz radiation 26 A. Chirped pulse beating 27 1. Optical cross-correlation...appropriately biased vertical transferred electron device ( Gunn diode ) with femtosecond optical pulses. " Investigation of the dynamics of photoinjected

  2. Pulse

    Science.gov (United States)

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

  3. [Effects of high pulsed electric field on the secondary and tertiary structure of lipoxygenase].

    Science.gov (United States)

    Zhong, Kui; Hu, Xiao-Song; Wu, Ji-Hong; Chen, Fang; Liao, Xiao-Jun

    2009-03-01

    The effect of pulsed electric field (PEF) on the secondary and tertiary structure of lipoxygenase (LOX) in a buffer solution was analyzed using far UV-circular dichroism (CD) and fluorescence spectrophotometry, respectively. The secondary and tertiary structure of LOX changed after PEF treatment. The CD spectra of LOX also changed, with the intensity of two negative peaks and the content of alpha-helix significantly decreased (p electric field strength. The fluorescence intensity of LOX increased, and the relative fluorescence intensity of the two characteristic peaks of LOX emission spectra at 337 nm and 583 nm also showed a good linear correlation with the electric field strength. These results showed that the activity inactivation of LOX may be due to the alteration in secondary structure, and both had a good relation.

  4. Hydrodynamical flows in dielectric liquid in strong inhomogeneous pulsed electric field

    Science.gov (United States)

    Tereshonok, Dmitry V.; Babaeva, Natalia Yu; Naidis, George V.; Smirnov, Boris M.

    2016-12-01

    We consider a hydrodynamical flow of dielectric liquid near a high voltage needle-shaped electrode in a strong inhomogeneous pulsed electric field. It was shown that under a small rise time, a negative pressure area (pressure is less than critical pressure) appears near the electrode leading to the formation of a cavity in which electric breakdown can develop. A comparison of the dependence of the velocity of fluid near an electrode for two cases (taking into account the dependence of dielectric permeability of the liquid on the electric field and without taking it into account) was made. A field-dependent dielectric coefficient leads to the appearance of two local maximums of the velocities and increases the minimum pressure, thus lowering the possibility of cavitation. While under the constant value of dielectric permeability only one local maximum appears.

  5. The cluster size transformation model of molten alloy under pulse electric field

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZhenBin; WANG JianZhong; QI JinGang; WANG Bing; HE LiJia; CANG DaQiang

    2008-01-01

    Based on the electric dipole theory,the coupled field distribution of pulse electric field (PEF) with electric dipole field around the cluster in superheated molten alloy is simulated under the effect of PEF. For the difference of electro-migration,the atom of solute and solution will accumulate around the cluster,and then the smaller cluster may reorganize and grow up under the action of the coupled field.We also apply the electrostatic induction theory to analyze the bearing behavior of the half side of the cluster. The bigger the cluster is,the stronger the electrostatic force is,therefore,the bigger cluster's stability is weak apparently. The study indicates that the cluster in the superheated molten has the homogeneous tendency under the effect of PEF.

  6. Damage of cellular material under simultaneous application of pressure and pulsed electric field

    CERN Document Server

    Bazhal, M I; Vorobev, E I

    2000-01-01

    Influence of pulsed electric field (PEF) simultaneous to pressure treatment on moisture expression from fine-cut cellular raw material has been investigated. Dependencies of specific conductivity $\\sigma$, liquid yield $Y$, instantaneous flow rate $v$ and qualitative juice characteristics at different modes of PEF treatment are discussed. Three main consolidation phases were observed in a case of mechanical expression. A unified approach is proposed for liquid yield data analysis allowing to reduce the data scattering caused by differences in the quality of samples. Simultaneous application of pressure and PEF treatment allows to reveal a passive form of electrical damage. Pressure provokes the damage of defected cells, enhances diffusion migration of moisture in porous cellular material and depresses the cell resealing processes. PEF application at a moment when a sample specific electrical conductivity reaches minimum and pressure achieves its constant value seemed to be the most optimal.

  7. Comparison of two models of a Double Inlet Miniature Pulse Tube Refrigerator - Part B Electrical Analogy

    CERN Document Server

    Bailly, Y; Bailly, Yannick; Nika, Philippe

    2002-01-01

    The design of a Double Inlet Pulse Tube Refrigerator is investigated by means of an analogy with an electric circuit. The results obtained with the electric scheme are compared with both those of the thermodynamic model (Part A) and experiments. The basic formulation of equivalent electronic components is discussed and a few improvements are proposed to adjust the theoretical expressions of the electrical impedances of capillaries and regenerator in order to consider additional effects such pressure drops due to geometrical singularities at different internal flow regimes. A simplified formulation for the regenerator inefficiency is deduced from considerations on its harmonic functioning. The main purpose of this analysis considers especially the design of miniature cryocoolers dedicated to electronic applications. These models are applied to a commercial miniature refrigerator. A discussion of their relevance is achieved and a few suggestions on the refrigerator design are proposed to improve the cooling pro...

  8. The cluster size transformation model of molten alloy under pulse electric field

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the electric dipole theory, the coupled field distribution of pulse electric field (PEF) with electric dipole field around the cluster in superheated molten alloy is simulated under the effect of PEF. For the difference of electro-migration, the atom of solute and solution will accumulate around the cluster, and then the smaller cluster may reorganize and grow up under the action of the coupled field. We also apply the electrostatic induction theory to analyze the bearing behavior of the half side of the cluster. The bigger the cluster is, the stronger the electrostatic force is, therefore, the bigger cluster’s stability is weak apparently. The study indi- cates that the cluster in the superheated molten has the homogeneous tendency under the effect of PEF.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Liling, E-mail: lilingtang@yahoo.com.cn [State Key Laboratory of Power Transmission Equipment and System and New Technology, Chongqing University, Chongqing 400044 (China); Key Laboratory of Biorheological Science and Technology, Chongqing University, Ministry of Education, Chongqing 400044 (China); College of Bioengineering, Chongqing University, Chongqing 400044 (China); Yao, Chenguo; Sun, Caixin [State Key Laboratory of Power Transmission Equipment and System and New Technology, Chongqing University, Chongqing 400044 (China)

    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.

  11. Microstructure and Temperature Distribution in ZnAl2O4 Sintered Body by Pulse Electric Current

    Institute of Scientific and Technical Information of China (English)

    Dongming ZHANG; Zhengyi FU; Jingkun GUO

    2003-01-01

    Microstructure of reaction sintering of ZnAl2O4 at 1500℃ by hot-pressing(HP) and pulse electric current was investigated. The results indicated that the existed cracks in sintered body were caused by structure mismatch. lt is the evidence that periodical temperature field existed during pulse electric current sintering of nonconductive materials.The distance between high temperature areas was related to die diameter.

  12. DETECTING TECHNIQUE OF WEAK PERIODIC PULSE SIGNAL VIA SYNTHESIS OF CROSS-CORRELATION AND CHAOTIC SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Li Yue; Yang Baojun; Lu Peng; Li Shizhe

    2003-01-01

    In this letter, with the synthesis of usual cross-correlation detecting method andchaotic detecting method, a new detecting system for the weak periodic pulse signal is constituted,in which the two methods can play respective preponderance. Theoretical analyses and simulationstudies have shown that the detecting system is very sensitive to the periodic pulse signal understrong noise background and has exceedingly powerful capability of suppressing complex noise.

  13. Using a Calculated Pulse Rate with an Artificial Neural Network to Detect Irregular Interbeats.

    Science.gov (United States)

    Yeh, Bih-Chyun; Lin, Wen-Piao

    2016-03-01

    Heart rate is an important clinical measure that is often used in pathological diagnosis and prognosis. Valid detection of irregular heartbeats is crucial in the clinical practice. We propose an artificial neural network using the calculated pulse rate to detect irregular interbeats. The proposed system measures the calculated pulse rate to determine an "irregular interbeat on" or "irregular interbeat off" event. If an irregular interbeat is detected, the proposed system produces a danger warning, which is helpful for clinicians. If a non-irregular interbeat is detected, the proposed system displays the calculated pulse rate. We include a flow chart of the proposed software. In an experiment, we measure the calculated pulse rates and achieve an error percentage of pulse rates to detect irregular interbeats, we find such irregular interbeats in eight participants.

  14. Sensitive detection of chlorine in iron oxide by single pulse and dual pulse laser-induced breakdown spectroscopy

    Science.gov (United States)

    Pedarnig, J. D.; Haslinger, M. J.; Bodea, M. A.; Huber, N.; Wolfmeir, H.; Heitz, J.

    2014-11-01

    The halogen chlorine is hard to detect in laser-induced breakdown spectroscopy (LIBS) mainly due to its high excited state energies of 9.2 and 10.4 eV for the most intense emission lines at 134.72 nm and 837.59 nm, respectively. We report on sensitive detection of Cl in industrial iron oxide Fe2O3 powder by single-pulse (SP) and dual-pulse (DP) LIBS measurements in the near infrared range in air. In compacted powder measured by SP excitation (Nd:YAG laser, 532 nm) Cl was detected with limit of detection LOD = 440 ppm and limit of quantitation LOQ = 720 ppm. Orthogonal DP LIBS was studied on pressed Fe2O3 pellets and Fe3O4 ceramics. The transmission of laser-induced plasma for orthogonal Nd:YAG 1064 nm and ArF 193 nm laser pulses showed a significant dependence on interpulse delay time (ipd) and laser wavelength (λL). The UV pulses (λL = 193 nm) were moderately absorbed in the plasma and the Cl I emission line intensity was enhanced while IR pulses (λL = 1064 nm) were not absorbed and Cl signals were not enhanced at ipd = 3 μs. The UV laser enhancement of Cl signals is attributed to the much higher signal/background ratio for orthogonal DP excitation compared to SP excitation and to the increased plasma temperature and electron number density. This enabled measurement at a very short delay time of td ≥ 0.1 μs with respect to the re-excitation pulse and detection of the very rapidly decaying Cl emission with higher efficiency.

  15. Neuronal excitation and permeabilization by 200-ns pulsed electric field: An optical membrane potential study with FluoVolt dye.

    Science.gov (United States)

    Pakhomov, Andrei G; Semenov, Iurii; Casciola, Maura; Xiao, Shu

    2017-07-01

    Electric field pulses of nano- and picosecond duration are a novel modality for neurostimulation, activation of Ca(2+) signaling, and tissue ablation. However it is not known how such brief pulses activate voltage-gated ion channels. We studied excitation and electroporation of hippocampal neurons by 200-ns pulsed electric field (nsPEF), by means of time-lapse imaging of the optical membrane potential (OMP) with FluoVolt dye. Electroporation abruptly shifted OMP to a more depolarized level, which was reached within 10s), so cells remained above the resting OMP level for at least 20-30s. Activation of voltage-gated sodium channels (VGSC) enhanced the depolarizing effect of electroporation, resulting in an additional tetrodotoxin-sensitive OMP peak in 4-5ms after nsPEF. Omitting Ca(2+) in the extracellular solution did not reduce the depolarization, suggesting no contribution of voltage-gated calcium channels (VGCC). In 40% of neurons, nsPEF triggered a single action potential (AP), with the median threshold of 3kV/cm (range: 1.9-4kV/cm); no APs could be evoked by stimuli below the electroporation threshold (1.5-1.9kV/cm). VGSC opening could already be detected in 0.5ms after nsPEF, which is too fast to be mediated by the depolarizing effect of electroporation. The overlap of electroporation and AP thresholds does not necessarily reflect the causal relation, but suggests a low potency of nsPEF, as compared to conventional electrostimulation, for VGSC activation and AP induction. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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) 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Shneider, Mikhail N., E-mail: m.n.shneider@gmail.com [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Pekker, Mikhail [MMSolution, 6808 Walker Street, Philadelphia, Pennsylvania 19135 (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. Effects of Electric Pulse Current on the Aging Kinetics of 2219 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Jiao Zhang

    2014-01-01

    Full Text Available The conventional aging experiments and the low density electric pulse current (LDEPC for short added aging experiments, with the self-made positive and negative alternating pulse power equipment, were conducted to study the influence of LDEPC on the dynamics of phase transformation in 2219 aluminum alloy by means of measuring the variation of hardness with aging time. The results showed that the hardness in both aging systems increased with the increasing of aging time until it reached the peak value; then it gradually reduced. The hardness of LDEPC added aging is generally greater than the conventional one before the peak aging time. The Avrami dynamics equation of conventional isothermal aging was obtained based on the hardness evolution law. The effects of electromigration and ponderomotive force were introduced into the Avrami empirical equation; in turn, the dynamics equation of LDEPC added aging was established. At last, the isothermal transformation curves of both the regular aging and the LDEPC added aging were derived which revealed that the nucleation rate, as well as the growth rate, was promoted by electric pulse current. The research work provided the theoretical support for the regulation of the coupling energy field on the dynamics of phase transformation in 2219 aluminum alloy.

  1. Novel Method of Unambiguous Moving Target Detection in Pulse-Doppler Radar with Random Pulse Repetition Interval

    Directory of Open Access Journals (Sweden)

    Liu Zhen

    2012-03-01

    Full Text Available Blind zones and ambiguities in range and velocity measurement are two important issues in traditional pulse-Doppler radar. By generating random deviations with respect to a mean Pulse Repetition Interval (PRI, this paper proposes a novel algorithm of Moving Target Detection (MTD based on the Compressed Sensing (CS theory, in which the random deviations of the PRIare converted to the Restricted Isometry Property (RIP of the observing matrix. The ambiguities of range and velocity are eliminated by designing the signal parameters. The simulation results demonstrate that this scheme has high performance of detection, and there is no ambiguity and blind zones as well. It can also shorten the coherent processing interval compared to traditional staggered PRI mode because only one pulse train is needed instead of several trains.

  2. Electrical addressing and temporal tweezing of localized pulses in passively-mode-locked semiconductor lasers

    Science.gov (United States)

    Camelin, P.; Javaloyes, J.; Marconi, M.; Giudici, M.

    2016-12-01

    We show that the pumping current is a convenient parameter for manipulating the temporal localized structures (LSs), also called localized pulses, found in passively-mode-locked vertical-cavity surface-emitting lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing one to control the position and the dynamics of LSs. We show that the localized pulse drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on a finite time scale and breaks the parity invariance along the cavity, thus leading to a different paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. Starting from a generic model of passive mode locking based upon delay differential equations, we deduce the effective equations of motion for these LSs in a time-dependent current landscape.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  5. Selective susceptibility to nanosecond pulsed electric field (nsPEF) across different human cell types.

    Science.gov (United States)

    Gianulis, Elena C; Labib, Chantelle; Saulis, Gintautas; Novickij, Vitalij; Pakhomova, Olga N; Pakhomov, Andrei G

    2017-05-01

    Tumor ablation by nanosecond pulsed electric fields (nsPEF) is an emerging therapeutic modality. We compared nsPEF cytotoxicity for human cell lines of cancerous (IMR-32, Hep G2, HT-1080, and HPAF-II) and non-cancerous origin (BJ and MRC-5) under strictly controlled and identical conditions. Adherent cells were uniformly treated by 300-ns PEF (0-2000 pulses, 1.8 kV/cm, 50 Hz) on indium tin oxide-covered glass coverslips, using the same media and serum. Cell survival plotted against the number of pulses displayed three distinct regions (initial resistivity, logarithmic survival decline, and residual resistivity) for all tested cell types, but with differences in LD50 spanning as much as nearly 80-fold. The non-cancerous cells were less sensitive than IMR-32 neuroblastoma cells but more vulnerable than the other cancers tested. The cytotoxic efficiency showed no apparent correlation with cell or nuclear size, cell morphology, metabolism level, or the extent of membrane disruption by nsPEF. Increasing pulse duration to 9 µs (0.75 kV/cm, 5 Hz) produced a different selectivity pattern, suggesting that manipulation of PEF parameters can, at least for certain cancers, overcome their resistance to nsPEF ablation. Identifying mechanisms and cell markers of differential nsPEF susceptibility will critically contribute to the proper choice and outcome of nsPEF ablation therapies.

  6. Dynamic changes of [Ca2+]i in cerebellar granule cells exposed to pulsed electric fields

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Intracellular free Ca2+ concentration ([Ca2+]i) in embryonic chick cerebellar granule cells loaded with fluo-3/AM and exposed to a single pulsed electric field was investigated using a confocal laser scanning microscope and fluorescent microscope equipped with CCD video imaging system.The results showed that [Ca2+]i increased immediately and rose to the peak rapidly as the cells exposed to a single pulsed electric field.The amplitude and rate of the increases of [Ca2+]i depend on the intensity of external electric field.In the presence of Ca2+ chelant EGTA or Ca2+ channels blocker La3+ in the pulsation solutions,the increase of [Ca2+]i was still observable.It was also observed that [Ca2+]i of different intracellular areas in the cell elevated simultaneously while the peak of the increase of [Ca2+]i in the poles of the cell preceded to the peak in its somata and recovered to a plateau within a short time.

  7. Dynamic changes of [Ca2+]i in cerebellar granule cells exposed to pulsed electric fields

    Institute of Scientific and Technical Information of China (English)

    陈雅; 王彦; 孙彤; 张锦珠; 景向红; 李瑞午

    2000-01-01

    Intracellular free Ca2+ concentration ([Ca2+]i) in embryonic chick cerebellar granule cells loaded with fluo-3/AM and exposed to a single pulsed electric field was investigated using a confocal laser scanning microscope and fluorescent microscope equipped with CCD video imaging system. The results showed that [Ca2+]i increased immediately and rose to the peak rapidly as the cells exposed to a single pulsed electric field. The amplitude and rate of the increases of [Ca2+]i depend on the intensity of external electric field. In the presence of Ca2+ chelant EGTA or Ca2+ channels blocker La3+ in the pulsation solutions, the increase of [Ca2+]i was still observable. It was also observed that [Ca2+]i of different intracellular areas in the cell elevated simultaneously while the peak of the increase of [Ca2+]i in the poles of the cell preceded to the peak in its somata and recovered to a plateau within a short time.

  8. Monopole patch antenna for in vivo exposure to nanosecond pulsed electric fields.

    Science.gov (United States)

    Merla, C; Apollonio, F; Paffi, A; Marino, C; Vernier, P T; Liberti, M

    2016-07-15

    To explore the promising therapeutic applications of short nanosecond electric pulses, in vitro and in vivo experiments are highly required. In this paper, an exposure system based on monopole patch antenna is reported to perform in vivo experiments on newborn mice with both monopolar and bipolar nanosecond signals. Analytical design and numerical simulations of the antenna in air were carried out as well as experimental characterizations in term of scattering parameter (S 11) and spatial electric field distribution. Numerical dosimetry of the setup with four newborn mice properly placed in proximity of the antenna patch was carried out, exploiting a matching technique to decrease the reflections due to dielectric discontinuities (i.e., from air to mouse tissues). Such technique consists in the use of a matching dielectric box with dielectric permittivity similar to those of the mice. The average computed electric field inside single mice was homogeneous (better than 68 %) with an efficiency higher than 20 V m(-1) V(-1) for the four exposed mice. These results demonstrate the possibility of a multiple (four) exposure of small animals to short nanosecond pulses (both monopolar and bipolar) in a controlled and efficient way.

  9. [Spectral analysis of polyphenol oxidase (PPO) and lipoxygenase (LOX) treated by pulsed electric field].

    Science.gov (United States)

    Luo, Wei; Zhang, Ruo-Bing; Chen, Jie; Wang, Li-Ming; Guan, Zhi-Cheng; Jia, Zhi-Dong

    2009-08-01

    Inactivation effect of pulsed electric field (PEF) on polyphenol oxidase (PPO) and lipoxygenase (LOX) was investigated using a laboratory PEF system with a coaxial treatment chamber. Circular dichroism (CD) and fluorescence analysis were used to study the conformation change of the protein. The experimental results show that PPO and LOX can be effectively inactivated by the PEF treatment. Inactivation effect of PPO and LOX increases with the increase in the applied electric strength and the treatment time. Activity of PPO and LOX can be reduced by 60.3% and 21.7% at 20 kV x cm(-1) after being treated for 320 micros respectively. The decrease of the negative peaks (208 and 215 nm in PPO spectra, 208 nm and 218 nm in LOX spectra) in CD spectra of PPO and LOX shows that PEF treatment caused a loss of alpha-helix and increase in beta-sheet content, indicating that conformation changes occur in the secondary structure of PPO and LOX enzyme. This effect was strengthened as the applied electric field increased: alpha-helical content of PPO and LOX was 56% and 29% after being treated at 8 kV x cm(-1), however, when the electric field was increased up to 20 kV x cm(-1), alpha-helical content of PPO and LOX decreased to 21% and 16% respectively. The decrease rate of alpha-helix and increase rate of beta-sheet in PPO are higher than LOX, indicating that the second conformation of PPO is less resistant to PEF treatment than LOX. The fluorescence intensity of LOX increases after PEF treatment. At the same time, increasing the applied pulsed electric field increases the fluorescence intensity emitted. Fluorescence measurements confirm that tertiary conformation changes occur in the local structure of LOX. However the possible mechanism of the conformation change induced by the PEF treatment is beyond the scope of the present investigation.

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

    Science.gov (United States)

    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.

  11. Effect of high hydrostatic pressure, ultrasound and pulsed electric fields on milk composition and characteristics

    Directory of Open Access Journals (Sweden)

    Irena Jeličić

    2012-03-01

    Full Text Available High hydrostatic pressure, ultrasonication and pulsed eletrcic fields (PEF belong to novel food processing methods which are mostly implemented in combination with moderate temperatures and/ or in combination with each other in order to provide adequate microbiological quality with minimal losses of nutritional value. All of three mentioned methods have been intensively investigated for the purpose of inactivation and reduction of foodborne microorganisms present in milk and dairy products. However, a large number of scientific researches have been dedicated to investigation of impact of these methods on changes in constituents like milk fat, milk proteins and lactose as well as changes in mechanisms like renneting properties and coagulation of milk. The aim of this research was to give an overview of changes in milk constituents induced by high hydrostatic pressure, ultrasonification and pulsed electric field treatments as well as to suggest how these changes could improve conventional processes in the dairy industry.

  12. Novel passive element circuits for microdosimetry of nanosecond pulsed electric fields.

    Science.gov (United States)

    Merla, C; Denzi, A; Paffi, A; Casciola, M; d'Inzeo, G; Apollonio, F; Liberti, M

    2012-08-01

    Microdosimetric models for biological cells have assumed increasing significance in the development of nanosecond pulsed electric field technology for medical applications. In this paper, novel passive element circuits, able to take into account the dielectric dispersion of the cell, are provided. The circuital analyses are performed on a set of input pulses classified in accordance with the current literature. Accurate data in terms of transmembrane potential are obtained in both time and frequency domains for different cell models. In addition, a sensitivity study of the transfer function for the cell geometrical and dielectric parameters has been carried out. This analysis offers a new, simple, and efficient tool to characterize the nsPEFs' action at the cellular level.

  13. Quantification of propidium iodide delivery with millisecond electric pulses: A model study

    CERN Document Server

    Yu, Miao

    2014-01-01

    A model study of propidium iodide delivery with millisecond electric pulses is presented; this work is a companion of the experimental efforts by Sadik et al. [1]. Both membrane permeabilization and delivery are examined with respect to six extra-cellular conductivities. The transmembrane potential of the permeabilized regions exhibits a consistent value, which corresponds to a bifurcation point in the pore-radius-potential relation. Both the pore area density and membrane conductance increase with an increasing extra-cellular conductivity. On the other hand, the inverse correlation between propidium iodide delivery and extra-cellular conductivity as observed in the experiments is quantitatively captured by the model. This agreement confirms that this behavior is primarily mediated by electrophoretic transport during the pulse. The results suggest that electrophoresis is important even for the delivery of small molecules such as propidium iodide. The direct comparison between model prediction and experimental...

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

    Science.gov (United States)

    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).

  15. Terahertz pulse detection by the GaAs Schottky diodes

    Science.gov (United States)

    Laperashvili, Tina; Kvitsiani, Orest; Imerlishvili, Ilia; Laperashvili, David

    2010-06-01

    We present the results of experimental studies of physical properties of the detection process of GaAs Schottky diodes for terahertz frequency radiation. The development of technology in the THz frequency band has a rapid progress recently. Considered as an extension of the microwave and millimeter wave bands, the THz frequency offers greater communication bandwidth than is available at microwave frequencies. The Schottky barrier contact has an important role in the operation of many GaAs devices. GaAs Schottky diodes have been the primary nonlinear device used in millimeter and sub millimeter wave detectors and receivers. GaAs Schottky diodes are especially interesting due to their high mobility transport characteristics, which allows for a large reduction of the resistance-capacitance (RC) time constant and thermal noise. In This work are investigated the electrical and photoelectric properties of GaAs Schottky diodes. Samples were obtained by deposition of different metals (Au, Ni, Pt, Pd, Fe, In, Ga, Al) on semiconductor. For fabrication metal-semiconductor (MS) structures is used original method of metal electrodepositing. In this method electrochemical etching of semiconductor surface occurs just before deposition of metal from the solution, which contains etching material and metal ions together. For that, semiconductor surface cleaning processes and metal deposition carries out in the same technological process. In the experiments as the electrolyte was used aqueous solution of chlorides. Metal deposition was carried out at room temperature.

  16. Design and Experiments of the High Voltage Pulsed Electric Fields Sterilization System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xihai; FANG Junlong; SHEN Weizheng

    2008-01-01

    This experiment designed the pulsed electric fields (PEF) of high intensity of 100 kV. cml sterilization system. Fluorescent pseudomonas as target cell was operated 180 s in the PEF. By observing the difference of the bacteria before and after the disposal by TEM, it is found that the cell wails of the treated bacteria were broken. Irreversible perforations were formed on the cell membrane. The cell inclusions and cell fragments were leaked. The cell died as a result. The results showed that the PEF sterilization system designed can be used for liquid food sterilization experiments.

  17. Effect of pulsed electric field on the germination of barley seeds

    DEFF Research Database (Denmark)

    Dymek, Katarzyna; Dejmek, Petr; Panarese, Valentina;

    2012-01-01

    This study explores metabolic responses of germinating barley seeds upon the application of pulsed electric fields (PEF). Malting barley seeds were steeped in aerated water for 24 h and PEF-treated at varying voltages (0 (control), 110, 160, 240, 320, 400 and 480 V). The seeds were then allowed...... to finish germination in saturated air. It is shown that exposure of germinating barley to PEF affects radicle emergence without significantly affecting the seeds’ gross metabolic activity, as quantified by isothermal calorimetry. An exploration of protein 2-DE profiles of both the embryo and the starchy...

  18. Enhanced methane production from pig slurry with pulsed electric field pre-treatment.

    Science.gov (United States)

    Safavi, Seyedeh Masoumeh; Unnthorsson, Runar

    2017-03-08

    Intensive amount of manure produced in pig breeding sectors represents negative impact on the environment and requires optimal management. Anaerobic digestion as a well-known manure management process was optimized in this experimental study by pulsed electric field (PEF) pre-treatment. The effect of PEF on methane production was investigated at three different intensities (15, 30 and 50 kWh/m(3)). The results indicate that the methane production and chemical oxygen demand (COD) removal was improved by continuous escalation of applied intensity, up to 50 kWh/m(3). In comparison with untreated slurry, methane production and COD removal were increased up to 58% and 44%, respectively.

  19. Development of a balanced detector with biased synchronous detection and application to near shot noise limited noise cancelling of supercontinuum pulse light.

    Science.gov (United States)

    Seto, Keisuke; Tsukada, Toshiaki; Okuda, Yoshinao; Tokunaga, Eiji; Kobayashi, Takayoshi

    2014-02-01

    We report on the development of a balanced detector suited for multicolor imaging. The source pulsed light is split into probe and reference pulsed light. The reference pulse is delayed through an optical path and the probe and reference pulses are detected by a single photodetector. The signs of the detected signals of the probe and reference pulses are flipped based on a signal synchronous to the light source. Then, the signals are averaged through a low-pass filter. The output signal is proportional to the intensity difference between the probe and the reference. This balanced detector has two features: (1) both the probe and reference pulsed lights are detected by a single photodetector and (2) a voltage bias on the sign flipping compensates for the optical-intensity unbalance between the probe and reference pulsed lights. The first feature enables the probe and reference pulses to travel along a common optical path from a sample through a spectrograph to the photodetector, which minimizes the intensity unbalance between the probe and reference pulses during imaging and spectroscopy. The second feature ensures the complete balanced-detection in whole wavelength range by compensating for the optical unbalance created by deviations in the splitting ratios of the probe and reference lights at different wavelengths. Although a higher signal to noise ratio (SNR) reached to near shot noise limited SNR is attained by attaching a resonator to the photodetector for pulse repetition, the electrical bias cannot compensate for the optical balance. This unbalance is, however, corrected by adjusting the phase of the synchronous signal. We applied the present balanced detection to a stimulated Raman microscope with supercontinuum probe light and demonstrated its noise cancelling performance through capturing polystyrene beads.

  20. Detection of elastic and electric conductivity anomalies in Potassium Sulphamate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Varughese, George, E-mail: gvushakoppara@yahoo.co.i [Department of Physics, Catholicate College, Pathanamthitta, Kerala 689645 (India); Santhosh Kumar, A. [SPAP, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Louis, Godfrey [Department of Physics, Cochin University of Science and Technology, Cochin 22 (India)

    2010-04-01

    Elastic anomalies in Potassium Sulphamate, (KNH{sub 2}SO{sub 3}), above room temperature were detected from temperature variation of elastic constants measured by ultrasonic Pulse Echo Overlap technique. Potassium Sulphamate has been reported to be a ferroelectric and piezo electric material. The elastic constants C{sub 11}, C{sub 44}, C{sub 55} and C{sub 66} have exhibited weak anomalies around 350 K. The DC conductivity measurement along a, b, and c axes also supports this conclusion.

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

    Science.gov (United States)

    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 (melt the crack tip and increase the strength of the damaged material. The experimental study shows an increase in the stress intensity factor up to 76% for sintered aluminum PM compacts and up to 116% for sintered aluminum MMC PM compacts due to application of high-density electric pulses during transverse rapture testing.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  4. Evaluation of the Athermal Effect of Electric Pulsing on the Recovery Behavior of Magnesium Alloy

    Science.gov (United States)

    Kim, Se-Jong; Kim, Sung-Dae; Yoo, Donghoon; Lee, Jinwoo; Rhyim, Youngmok; Kim, Daeyong

    2016-12-01

    It is still unclear whether the effects of the electric current on the mechanical behavior can be attributed exclusively to Joule heating. To evaluate athermal effect of electropulsing on recovery, we compared mechanical behavior, dislocation density, and hardness of a pre-tensioned magnesium alloy after treatment of electric pulses (EP) and annealing in an oil bath. The analysis reveals that the athermal effect of EP on the recovery is not clearly identified under a given set of conditions in this study, although EP treatment appears more efficient than conventional heat treatment. This is further supported by the in situ transmission electron microscopy results that little dislocation rearrangement was observed even during the high current density of 4000 A/mm2 as long as temperature remains low.

  5. Kinetic model for the inactivation of Lactobacillus plantarum by pulsed electric fields.

    Science.gov (United States)

    Rodrigo, D; Ruíz, P; Barbosa-Cánovas, G V; Martínez, A; Rodrigo, M

    2003-03-25

    The kinetics of Lactobacillus plantarum inactivation by pulsed electric fields (PEF) was studied in two different growth stages (exponential and stationary), but in the same reference medium (0.6% peptone water). Electric field intensity and treatment time varied from 20 to 28 kV/cm and 30 to 240 micros, respectively. The experimental data showed that cells in the exponential growth stage were more sensitive to PEF treatment than those in the stationary stage. The inactivation data were adjusted to the Bigelow and Hülsheger models and the Weibull frequency distribution function, and constants were calculated for both growth stages in each model. The models were tested and their accuracy was assessed by using the Accuracy Factor. According to this parameter, the Weibull frequency distribution function gave better fittings for the inactivation by PEF than Bigelow or Hülsheger models. On the other hand, the Bigelow model gave a good accuracy factor and is simpler.

  6. Dislocation-templated amorphization of Ge2Sb2Te5 nanowires under electric pulses: A theoretical model

    Science.gov (United States)

    Ji, Xiang-Ying; Feng, Xi-Qiao

    2013-06-01

    Owing to their unique phase change property, GeSbTe alloys hold promise for applications as a candidate material for nonvolatile electronic data storage. In this paper, we theoretically investigate the dislocation mechanisms underlying the phase change phenomenon of GeSbTe alloys under electric pulses. On the basis of the recent experiments by Nam et al. (Science 336, 1561-1566 (2012)), a theoretical model is presented to rationalize the dislocation-templated amorphization process under the action of electric pulses. The physical mechanisms of the nucleation, movement, and multiplication of dislocations in the electric field are analyzed. Using the model, the evolutions of temperature and dislocation density in a Ge2Sb2Te5 nanowire under electric pulses are computed and the critical voltage of amorphization is predicted.

  7. Basic principles of thermo-acoustic energy and temporal profile detection of microwave pulses

    CERN Document Server

    Andreev, V G; Vdovin, V A

    2001-01-01

    Basic principles of a thermo-acoustic method developed for the detection of powerful microwave pulses of nanosecond duration are discussed.A proposed method is based on the registration of acoustic pulse profile originated from the thermal expansion of the volume where microwave energy was absorbed.The amplitude of excited acoustic transient is proportional to absorbed microwave energy and its temporal profile resembles one of a microwave pulse when certain conditions are satisfied.The optimal regimes of microwave pulse energy detection and sensitivity of acoustic transient registration with piezo-transducer are discussed.It was demonstrated that profile of a microwave pulse could be detected with temporal resolution of 1 - 3 nanosecond.

  8. Coherent control of magnetization precession in electrically detected time domain ferromagnetic resonance

    Directory of Open Access Journals (Sweden)

    O. Wid

    2015-11-01

    Full Text Available We demonstrate coherent control of time domain ferromagnetic resonance by all electrical excitation and detection. Using two ultrashort magnetic field steps with variable time delay we control the induction decay in yttrium iron garnet (YIG. By setting suitable delay times between the two steps the precession of the magnetization can either be enhanced or completely stopped. The method allows for a determination of the precession frequency within a few precession periods and with an accuracy much higher than can be achieved using fast fourier transformation. Moreover it holds the promise to massively increase precession amplitudes in pulsed inductive microwave magnetometry (PIMM using low amplitude finite pulse trains. Our experiments are supported by micromagnetic simulations which nicely confirm the experimental results.

  9. Coherent control of magnetization precession in electrically detected time domain ferromagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Wid, O.; Wahler, M.; Homonnay, N.; Richter, T. [Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 (Germany); Schmidt, G., E-mail: georg.schmidt@physik.uni-halle.de [Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 (Germany); IZM, Martin-Luther-Universität Halle-Wittenberg, D-06099 (Germany)

    2015-11-15

    We demonstrate coherent control of time domain ferromagnetic resonance by all electrical excitation and detection. Using two ultrashort magnetic field steps with variable time delay we control the induction decay in yttrium iron garnet (YIG). By setting suitable delay times between the two steps the precession of the magnetization can either be enhanced or completely stopped. The method allows for a determination of the precession frequency within a few precession periods and with an accuracy much higher than can be achieved using fast fourier transformation. Moreover it holds the promise to massively increase precession amplitudes in pulsed inductive microwave magnetometry (PIMM) using low amplitude finite pulse trains. Our experiments are supported by micromagnetic simulations which nicely confirm the experimental results.

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

    Science.gov (United States)

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

    2016-09-01

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, Juan J. [Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada al Ser Humano, Universitat Politècnica de València, Valencia 46022 (Spain); Pérez-Cajaraville, Juan J. [Pain Unit and Department of Anesthesia and Critical Care, Clínica Universidad de Navarra, University of Navarra, Pamplona 31008 (Spain); Muñoz, Víctor [Neurotherm Spain, Barcelona 08303 (Spain); Berjano, Enrique, E-mail: eberjano@eln.upv.es [Biomedical Synergy, Electronic Engineering Department, Universitat Politècnica de València 46022 (Spain)

    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

  15. Evaluation of cell-disruption effects of pulsed-electric-field treatment of Synechocystis PCC 6803.

    Science.gov (United States)

    Sheng, Jie; Vannela, Raveender; Rittmann, Bruce E

    2011-04-15

    In order to use Synechocystis PCC 6803 as feedstock of nonpetroleum-based diesel fuel, pulsed electric field (PEF) technology was used for cell disruption prior to extraction of intracellular lipids. Severe cell disruption was evident after PEF treatment, especially with treatment intensity (TI) > 35 kWh/m(3). Temperature increase during the treatment brought about most of the destruction of autofluorescence compounds, as well as a fraction of inactivation and the destruction of the plasma and thylakoid membranes. However, the forces associated with the pulsing electric field caused significant damage to the plasma membrane, cell wall, and thylakoid membrane, and it even led to complete disruption of some cells into fragments, which resulted in biomass loss. Treatment by PEF enhanced the potential for the low-toxicity solvent isopropanol to access lipid molecules during subsequent solvent extraction, leading to lower usage of isopropanol for the same extraction efficiency. Thus, PEF shows promise for lowering the costs and environmental effects of the lipid-extraction step.

  16. Analysis of DPPH inhibition and structure change of corn peptides treated by pulsed electric field technology.

    Science.gov (United States)

    Wang, Ke; Wang, Ying; Lin, Songyi; Liu, Xuye; Yang, Shuailing; Jones, Gregory S

    2015-07-01

    In this study, the effects on antioxidant activity and structure change of corn peptides (CPS) with 10 to 30 kDa molecular weight (MW) treated by pulsed electric field (PEF) technology were investigated. 2, 2-diphenyl-1-picrylhydrazyl (DPPH) inhibition was used to evaluate the antioxidant activity of CPS. Response surface methodology (RSM) was used to investigate the effects of PEF treatment parameters on antioxidant activity of CPS. The optimal conditions were as follows: concentration of CPS 10 mg mL(-1), electric field intensity 15 kV cm(-1), and pulse frequency 2,000 Hz. Under the optimized conditions, the DPPH inhibition of CPS increased 32.1 %, compared to the sample untreated. And mid-infrared spectroscopy (MIR) was used for analyzing the structure change of CPS. The results showed that PEF technology could obviously increase the DPPH inhibition of CPS under the optimized conditions (P < 0.05).

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

    Science.gov (United States)

    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%.

  18. Transient suppression of gap junctional intercellular communication after exposure to 100-nanosecond pulsed electric fields.

    Science.gov (United States)

    Steuer, Anna; Schmidt, Anke; Labohá, Petra; Babica, Pavel; Kolb, Juergen F

    2016-12-01

    Gap junctional intercellular communication (GJIC) is an important mechanism that is involved and affected in many diseases and injuries. So far, the effect of nanosecond pulsed electric fields (nsPEFs) on the communication between cells was not investigated. An in vitro approach is presented with rat liver epithelial WB-F344 cells grown and exposed in a monolayer. In order to observe sub-lethal effects, cells were exposed to pulsed electric fields with a duration of 100ns and amplitudes between 10 and 20kV/cm. GJIC strongly decreased within 15min after treatment but recovered within 24h. Gene expression of Cx43 was significantly decreased and associated with a reduced total amount of Cx43 protein. In addition, MAP kinases p38 and Erk1/2, involved in Cx43 phosphorylation, were activated and Cx43 became hyperphosphorylated. Immunofluorescent staining of Cx43 displayed the disassembly of gap junctions. Further, a reorganization of the actin cytoskeleton was observed whereas tight junction protein ZO-1 was not significantly affected. All effects were field- and time-dependent and most pronounced within 30 to 60min after treatment. A better understanding of a possible manipulation of GJIC by nsPEFs might eventually offer a possibility to develop and improve treatments.

  19. COMBINING MODERATE PULSED ELECTRIC FIELDS WITH TEMPERATURE AND WITH ORGANIC ACIDS TO INACTIVATE ESCHERICHIA COLI SUSPENSIONS

    Directory of Open Access Journals (Sweden)

    Henri EL ZAKHEM

    2010-09-01

    Full Text Available The aim of this work was to study the efficiency of inactivation of Escherichia coli cells in aqueous suspensions using combined moderate pulsed electric field (PEF and thermal treatments. The inactivation kinetics of E. coli cells in aqueous suspensions (1 wt% was monitored using conductometric technique. The electric field strength E was within 5-7.5 kV/cm, the effective PEF treatment time was within 0-0.75 s, the pulse duration ti was within 0.3-1 ms, the medium temperature was 30-50°C, and the time of thermal treatment tT was within 0-7000 s. The organic acid concentration was within 0-0.5 g/L.The damage of E. coli was accompanied by release of intracellular components. The synergy between the PEF and thermal treatments in E. coli inactivation was clearly demonstrated. The damage efficiency was noticeably improved by addition of organic acids, especially lactic acid.

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

    Directory of Open Access Journals (Sweden)

    Linying Liu

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  2. Finite pulse effects on fermion pair creation from strong electric fields

    Science.gov (United States)

    Taya, Hidetoshi; Fujii, Hirotsugu; Itakura, Kazunori

    2014-09-01

    In the early stage of heavy ion collisions, there appear extraordinarily strong (color) EM fields. In the presence of such strong fields, we encounter essentially new phenomena that are not observed in the vacuum: Among those is fermion pair creation from the vacuum. In this talk, we consider fermion pair creation from the vacuum in a strong electric field with finite duration. Employing the Sauter-type pulsed electric field with height E0 and width τ, we demonstrate explicitly the interplay between the non-perturbative and perturbative aspects of the pair creation in a strong field with finite duration. We identify that two dimensionless parameters ν = | g E0 | τ2 and γ = | g E0 | τ / m characterize the importance of multiple interactions with the field and the transition from the perturbative to the non-perturbative regime. We also show that the pair creation is enhanced compared to Schwinger's formula when the field strength is relativity weak | g E0 | / m2 < 1 and the pulse duration is relatively short mτ < 1 , and reveal that the enhancement is predominantly described by the lowest order perturbation with a single photon. We also discuss some recent developments and applications.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  5. Lipid vesicles in pulsed electric fields: Fundamental principles of the membrane response and its biomedical applications.

    Science.gov (United States)

    Perrier, Dayinta L; Rems, Lea; Boukany, Pouyan E

    2017-04-28

    The present review focuses on the effects of pulsed electric fields on lipid vesicles ranging from giant unilamellar vesicles (GUVs) to small unilamellar vesicles (SUVs), from both fundamental and applicative perspectives. Lipid vesicles are the most popular model membrane systems for studying biophysical and biological processes in living cells. Furthermore, as vesicles are made from biocompatible and biodegradable materials, they provide a strategy to create safe and functionalized drug delivery systems in health-care applications. Exposure of lipid vesicles to pulsed electric fields is a common physical method to transiently increase the permeability of the lipid membrane. This method, termed electroporation, has shown many advantages for delivering exogenous molecules including drugs and genetic material into vesicles and living cells. In addition, electroporation can be applied to induce fusion between vesicles and/or cells. First, we discuss in detail how research on cell-size GUVs as model cell systems has provided novel insight into the basic mechanisms of cell electroporation and associated phenomena. Afterwards, we continue with a thorough overview how electroporation and electrofusion have been used as versatile methods to manipulate vesicles of all sizes in different biomedical applications. We conclude by summarizing the open questions in the field of electroporation and possible future directions for vesicles in the biomedical field. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2016-03-18

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Mali Vyacheslav

    2011-01-01

    Full Text Available Abstract 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.

  9. Elasticity and tumorigenic characteristics of cells in a monolayer after nanosecond pulsed electric field exposure.

    Science.gov (United States)

    Steuer, A; Wende, K; Babica, P; Kolb, J F

    2017-09-01

    Nanosecond pulsed electric fields (nsPEFs) applied to cells can induce different biological effects depending on pulse duration and field strength. One known process is the induction of apoptosis whereby nsPEFs are currently investigated as a novel cancer therapy. Another and probably related change is the breakdown of the cytoskeleton. We investigated the elasticity of rat liver epithelial cells WB-F344 in a monolayer using atomic force microscopy (AFM) with respect to the potential of cells to undergo malignant transformation or to develop a potential to metastasize. We found that the elastic modulus of the cells decreased significantly within the first 8 min after treatment with 20 pulses of 100 ns and with a field strength of 20 kV/cm but was still higher than the elasticity of their tumorigenic counterpart WB-ras. AFM measurements and immunofluorescent staining showed that the cellular actin cytoskeleton became reorganized within 5 min. However, both a colony formation assay and a cell migration assay revealed no significant changes after nsPEF treatment, implying that cells seem not to adopt malignant characteristics associated with metastasis formation despite the induced transient changes to elasticity and cytoskeleton that can be observed for up to 1 h.

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

    Science.gov (United States)

    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 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.

  11. Exploring the use of natural antimicrobial agents and pulsed electric fields to control spoilage bacteria during a beer production process.

    Science.gov (United States)

    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.

  12. X-ray emission from a nanosecond-pulse discharge in an inhomogeneous electric field at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Cheng; Shao Tao; Ren Chengyan; Zhang Dongdong [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Tarasenko, Victor; Kostyrya, Igor D. [Institute of High Current Electronics, Russian Academy of Science, Tomsk 634055 (Russian Federation); Ma Hao [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Yan Ping [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

    2012-12-15

    This paper describes experimental studies of the dependence of the X-ray intensity on the anode material in nanosecond high-voltage discharges. The discharges were generated by two nanosecond-pulse generators in atmospheric air with a highly inhomogeneous electric field by a tube-plate gap. The output pulse of the first generator (repetitive pulse generator) has a rise time of about 15 ns and a full width at half maximum of 30-40 ns. The output of the second generator (single pulse generator) has a rise time of about 0.3 ns and a full width at half maximum of 1 ns. The electrical characteristics and the X-ray emission of nanosecond-pulse discharge in atmospheric air are studied by the measurement of voltage-current waveforms, discharge images, X-ray count and dose. Our experimental results showed that the anode material rarely affects electrical characteristics, but it can significantly affect the X-ray density. Comparing the density of X-rays, it was shown that the highest x-rays density occurred in the diffuse discharge in repetitive pulse mode, then the spark discharge with a small air gap, and then the corona discharge with a large air gap, in which the X-ray density was the lowest. Therefore, it could be confirmed that the bremsstrahlung at the anode contributes to the X-ray emission from nanosecond-pulse discharges.

  13. [Fluorescence polarization used to investigate the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field].

    Science.gov (United States)

    Zhang, Ying; Zeng, Xin-An; Wen, Qi-Biao; Li, Lin

    2008-01-01

    To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased with the increase in the electric field strength and the extension of treatment time. Even in a quite lower electric field of 5 kV x cm(-1) with a tiny microorganism lethal level, the increase in UV absorption value and the decrease in fluidity were significant. It was demonstrated that the cell membrane fluidity decreases with the increase in lethal ratio and cell membrane permeability. The viscosity of cell membrane increases with the decrease in fluidity. These phenomena indicated that cell membrane is one of the most key sites during the pulsed electric field treatment, and the increased membrane permeability and the decreased cell membrane fluidity contribute to the cell death.

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

    Science.gov (United States)

    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.

  15. Quality stability and sensory attributes of apple juice processed by thermosonication, pulsed electric field and thermal processing.

    Science.gov (United States)

    Sulaiman, Alifdalino; Farid, Mohammed; Silva, Filipa Vm

    2017-04-01

    Worldwide, apple juice is the second most popular juice, after orange juice. It is susceptible to enzymatic browning spoilage by polyphenoloxidase, an endogenous enzyme. In this study, Royal Gala apple juice was treated by thermosonication (TS: 1.3 W/mL, 58 ℃, 10 min), pulsed electric field (PEF: 24.8 kV/cm, 60 pulses, 169 µs treatment time, 53.8 ℃) and heat (75 ℃, 20 min) and stored at 3.0 ℃ and 20.0 ℃ for 30 days. A sensory analysis was carried out after processing. The polyphenoloxidase activity, antioxidant activity and total color difference of the apple juice were determined before and after processing and during storage. The sensory analysis revealed that thermosonication and pulsed electric field juices tasted differently from the thermally treated juice. Apart from the pulsed electric field apple juice stored at room temperature, the processed juice was stable during storage, since the pH and soluble solids remained constant and fermentation was not observed. Polyphenoloxidase did not reactivate during storage. Along storage, the juices' antioxidant activity decreased and total color difference increased (up to 6.8). While the antioxidant activity increased from 86 to 103% with thermosonication and was retained after pulsed electric field, thermal processing reduced it to 67%. The processing increased the total color difference slightly. No differences in the total color difference of the juices processed by the three methods were registered after storage. Thermosonication and pulsed electric field could possibly be a better alternative to thermal preservation of apple juice, but refrigerated storage is recommended for pulsed electric field apple juice.

  16. Selective detection of ordered sodium signals by a jump-and-return pulse sequence

    Science.gov (United States)

    Lee, Jae-Seung; Regatte, Ravinder R.; Jerschow, Alexej

    2009-09-01

    A simple pulse sequence, derived from the shaped pulse optimally exciting the central transition of a spin 3/2, can be used to selectively detect ordered sodium with a given quadrupolar coupling. The pulse sequence consists of two pulses with opposite phases and separated by a delay, called a quadrupolar jump-and-return (QJR) sequence. This QJR sequence is tested with a phantom made of sodium ions in bacteriophage and in aqueous solution and its feasibility for contrast modification based on the quadrupolar coupling is demonstrated.

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

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; McConnell, B.W.; Van Dyke, J.W. [Oak Ridge National Lab., TN (United States); Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Vance, E.F. [Vance (E.F.), Fort Worth, TX (United States)

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

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; McConnell, B.W.; Van Dyke, J.W. (Oak Ridge National Lab., TN (United States)); Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Vance, E.F. (Vance (E.F.), Fort Worth, TX (United States))

    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.

  19. Verification and Analysis of Implementing Virtual Electric Devices in Circuit Simulation of Pulsed DC Electrical Devices in the NI MULTISIM 10.1 Environment

    Directory of Open Access Journals (Sweden)

    V. A. Solov'ev

    2015-01-01

    Full Text Available The paper presents the analysis results of the implementation potential and evaluation of the virtual electric devices reliability when conducting circuit simulation of pulsed DC electrical devices in the NI Multisim 10.1environment. It analyses metrological properties of electric measuring devices and sensors of the NI Multisim 10.1environment. To calculate the reliable parameters of periodic non-sinusoidal electrical values based on their physical feasibility the mathematical expressions have been defined.To verify the virtual electric devices a circuit model of the power section of buck DC converter with enabled devices under consideration at its input and output is used as a consumer of pulse current of trapezoidal or triangular form. It is used as an example to show a technique to verify readings of virtual electric measuring devices in the NI Multisim 10.1environment.It is found that when simulating the pulsed DC electric devices to measure average and RMS voltage supply and current consumption values it is advisable to use the probe. Electric device power consumption read from the virtual power meter is equal to its average value, and its displayed power factor is inversely proportional to the input current form factor. To determine the RMS pulsed DC current by ammeter and multi-meter it is necessary to measure current by these devices in DC and AC modes, and then determine the RMS value of measurement results.Virtual electric devices verification has proved the possibility of their application to determine the energy performance of transistor converters for various purposes in the circuit simulation in the NI 10.1 Multisim environment, thus saving time of their designing.

  20. A blind transform based approach for the detection of isolated astrophysical pulses

    Science.gov (United States)

    Alkhweldi, Marwan; Schmid, Natalia A.; Prestage, Richard M.

    2017-06-01

    This paper presents a blind algorithm for the automatic detection of isolated astrophysical pulses. The detection algorithm is applied to spectrograms (also known as "filter bank data" or "the (t,f) plane"). The detection algorithm comprises a sequence of three steps: (1) a Radon transform is applied to the spectrogram, (2) a Fourier transform is applied to each projection parametrized by an angle, and the total power in each projection is calculated, and (3) the total power of all projections above 90° is compared to the total power of all projections below 90° and a decision in favor of an astrophysical pulse present or absent is made. Once a pulse is detected, its Dispersion Measure (DM) is estimated by fitting an analytically developed expression for a transformed spectrogram containing a pulse, with varying value of DM, to the actual data. The performance of the proposed algorithm is numerically analyzed.

  1. Therapeutic effect of low-frequency pulsed electrical stimulation on melanoma in mice and its injurious effect on myocardium

    Directory of Open Access Journals (Sweden)

    Sha WU

    2015-01-01

    Full Text Available Objective To assess the inhibitory effects of pulsed electrical stimulation at different low frequencies on B16-F10 melanoma, and evaluate its influence on the structure and function of heart in mice. Methods BALB/C mice were inoculation with melanoma cell B16F10 to reproduce melanoma. These mice were randomly divided into four groups: rats in three treatment groups received of pulsed electrical stimulation of 10, 20Hz and 25Hz respectively, with a 1-ms pulse width, field strength of 20 V/cm, and duration of 30 min/d, and no electrical stimulation was given to the control group (10 each. ECG change in each group was recorded. Seven days later, tumor volume and survival rate were recorded. The changes in tumor and myocardial morphology were examined using HE staining. The expression of S-100B protein in tumor was assessed by immunohistochemical method. The serum levels of troponin T (cTnT and creatine kinase isoenzyme (CK-MB were determined by ELISA. Results After being treated with pulsed electrical stimulation for 15 days, tumor volume in 10, 20Hz and 25Hz group (463.0±33.0, 248.6±34.6, 29.9±15.9mm3, respectively, was significantly smaller than that in control group (2027.0±133.4mm3, P0.05. Conclusions Low-frequency pulsed electrical stimulation has a suppressive effect on the growth of B16F10 melanoma in mice, and the pulsed electric stimulation at 20 V/cm, 20 Hz and 1 ms are proved to be the most effective in suppressing the growth of tumor without affecting the normal electrical activity in mice or causing myocardial damage. DOI: 10.11855/j.issn.0577-7402.2014.12.05

  2. Guiding of Long-Distance Electric Discharges by Combined Femtosecond and Nanosecond Pulses Emitted by Hybrid KrF Laser System

    Science.gov (United States)

    2014-01-30

    laser pulse initiated HV discharge with a time delay of tens nanoseconds – evidently it is developing due to an avalanche -like growth of electron...AFRL-AFOSR-UK-TR-2014-0040 Guiding of long-distance electric discharges by combined femtosecond and nanosecond pulses emitted by...and guiding electric discharge , KrF laser, femtosecond pulse , nanosecond pulse , filamentation, plasma channel, lightning control, laser control of

  3. Investigation of low-voltage pulse parameters on electroporation and electrical lysis using a microfluidic device with interdigitated electrodes.

    Science.gov (United States)

    Morshed, Bashir I; Shams, Maitham; Mussivand, Tofy

    2014-03-01

    Electroporation (EP) of biological cells leads to the exchange of materials through the permeabilized cell membrane, while electrical lysis (EL) irreversibly disrupts the cell membrane. We report a microfluidic device to study these two phenomena with low-voltage excitation for lab-on-a-chip (LOC) applications. For systematic study of EP, we have employed a quantification metric: flow Index (FI) of EP. Simulation and experimental results with the microfluidic device containing interdigitated, coplanar, integrated electrodes to electroporate, and rapidly lyse biological cells are presented. H&E stained human buccal cells were subjected to various pulse magnitudes, pulsewidths, and number of pulses. Simulations show that an electric field of 25 kV/cm with a 20 V applied potential produced 1.3 (°)C temperature rise for a 5 s of excitation. For a 20 V pulse-excitation with pulse-widths between 0.5 to 5 s, EL was observed, whereas for lower excitations, only EP was observed. FI of EP is found to be a direct function of pulse magnitudes, pulsewidths, and numbers of pulses. To release DNA from nucleus, excitation-pulses of 5 s were required. Quantification of EP would be useful for systematic study of EP toward optimization with various excitation pulses, while low-voltage requirement and high yield of EP and EL are critical to develop LOC for drug delivery and cell-sample preparation, respectively.

  4. Evaluation of Pulsed Power Architectures for Active Detection

    Science.gov (United States)

    2013-06-01

    kV capacitors, a thyratron switch and a 10:1 iron-core pulse transformer, and is insulated by 30 psig SF6. Each is capable of charging four...Figure 8. ACLIA cell output from 2-D TL model . A layout for the accelerator is sketched in Fig. 9. Seven cells provide 8.75 MeV of

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

    Directory of Open Access Journals (Sweden)

    Nedialko I Krouchev

    Full Text Available 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

  6. Outlook for the use of focused shock waves and pulsed electric fields in the complex treatment of malignant neoplasms.

    Science.gov (United States)

    Garilevich, B A; Andrianov, Yu V; Olefir, Yu V; Zubkov, A D; Rotov, A E

    2006-01-01

    The experimental studies the synchronous action of electric field microsecond range with amplitude within the range of 1-7 kV/sm and shock waves with pressure before 100 MPa on cells membrane permeability of the mouse's ascitic tumors in vitro have shown the intensification the efficiency of the forming the irreversible pores under synchronous action. Thereby, enabling the electric field in the compression phase of shock wave pulse which can essentially reduce the electric field intensity required for breakdown cell membrane. In usual condition at amplitude of electric field, specified above, electric breakdown membrane carries basically reversible nature. At the same time in the pressure field tension phase of shock-wave pulse reversible pores, created by electric field, can grow before sizes, under which wholeness membrane is not restored. Under simultaneous action on cellular suspension the shock wave and electric field with moderate intensity cells survival is reduced in 5 once in contrast with occuring at different time's action, and in 10 once in contrast with checking. The most sensitive to influence by under study fields are cells in phase of the syntheses DNA, preparation to fission and in phase of the mitosis. Thereby, continuation of the studies on use synchronous action shock waves and pulsed electric fields in complex treatment of the tumors introduces perspective.

  7. Effect of two-channel gastric electrical stimulation with trains of pulses on gastric motility

    Institute of Scientific and Technical Information of China (English)

    Bin Yang; Xiao-Hua Hou; Geng-Qing Song; Jin-Song Liu; Jiande DZ Chen

    2009-01-01

    AIM: To investigate the effect of two-channel gastric electrical stimulation (GES) with trains of pulses on gastric emptying and slow waves. METHODS: Seven dogs implanted with four pairs of electrodes and equipped with a duodenal cannula were involved in this study. Two experiments were performed. The first experiment included a series of sessions in the fasting state with trains of short or long pulses, each lasted 10 min. A 5-min recording without pacing was made between two sessions. The second experiment was performed in three sessions (control, single-channel GES, and two-channel GES). The stimulus was applied via the 1st pair of electrodes for single-channel GES (GES via one pair of electrodes located at 14 cm above the pylorus), and simultaneously via the 1st and 3rd channels for two-channel GES (GES via two pairs of electrodes located at 6 and 14 cm above the pylorus). Gastric liquid emptying was collected every 15 min via the cannula for 90 min. RESULTS: GES with trains of pulses at a pulse width of 4 ms or higher was able to entrain gastric slow waves. Two-channel GES was about 50% more efficient than single-channel GES in entraining gastric slow waves. Two channel but not single-channel GES with trains of pulses was capable of accelerating gastric emptying in healthy dogs. Compared with the control session, two-channel GES significantly increased gastric emptying of liquids at 15 min (79.0% ± 6.4% vs 61.3% ± 6.1%, P < 0.01), 30 min (83.2% ± 6.3 % vs 68.2% ± 6.9%, P < 0.01),60 min (86.9% ± 5.5 % vs 74.1% ± 5.9%, P < 0.01),and 90 min (91.0% ± 3.4% vs 76.5% ± 5.9%, P < 0.01).CONCLUSION: Two-channel GES with trains of pulses accelerates gastric emptying in healthy dogs and may have a therapeutic potential for the treatment of gastric motility disorders.

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

    Science.gov (United States)

    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%.

  9. Comparative analysis of short and long GPR pulses for landmine detection

    Science.gov (United States)

    Temlioǧlu, Eyyup; Nazlı, Hakkı; Aksoy, Serkan

    2016-05-01

    Ground Penetrating Radar (GPR) is one of the most popular subsurface sensing devices. It has a wide range of applications such as landmine detection, archeological investigations, road condition survey and so on. Hardware and software requirements of the GPR system are strongly dependent on type of applications. Principally, lower frequencies provide deeper penetration and low resolution, but higher frequencies are able to detect shallow objects with high resolution. As a fundamental design criterion, there is a trade-off between penetration depth and vertical resolution. In impulse radar, pulse duration (frequency related) is a key parameter because it affects the system detection performance. Specially, optimization of the pulse duration is a challenging problem for landmine detection because the GPR performance has been strongly affected from mine types, varying terrain and environmental conditions. In this work, two GPR systems with pulse durations of 650 ps and 870 ps are compared for evaluation of their detection performance. The pulses are tested with extensive data sets collected from different soil types by using surrogate mines and other objects. Receiver Operating Characteristic (ROC) curves of the system is also calculated. It seems that the 650 ps pulse duration gives better performance than the 870 ps pulse duration for the shallow landmine detection.

  10. Time-resolved detection of relative intensity squeezed nanosecond pulses in a 87Rb vapor

    CERN Document Server

    Agha, Imad H; Messin, Gaetan; Grangier, Philippe

    2010-01-01

    We present experimental studies on the generation and detection of pulsed, relative-intensity squeezed light in a warm rubidium vapor. The noise correlations between a pulsed probe beam and its conjugate -generated through nearly-degenerate four-wave mixing in a double-lambda system- are studied via time-resolved balanced detection. We observe -0.96 dB of time-resolved relative intensity squeezing with 50 nanosecond pulses at 1 MHz repetition rate. (-1.34 dB corrected for loss).

  11. Time-resolved detection of relative intensity squeezed nanosecond pulses in a Rb87 vapor

    CERN Document Server

    Agha, Imad H; Glorieux, Quentin; Coudreau, Thomas; Grangier, Philippe; Messin, Gaetan

    2011-01-01

    We present theoretical and experimental results on the generation and detection of pulsed, relative-intensity squeezed light in a hot Rb87 vapor. The intensity noise correlations between a pulsed probe beam and its conjugate, generated through nearly-degenerate four-wave mixing in a double-lambda system, are studied numerically and measured experimentally via time-resolved balanced detection. We predict and observe about -1 dB of time-resolved relative intensity squeezing with 50 nanosecond pulses at 1 MHz repetition rate. (-1.34 dB corrected for loss).

  12. A Novel Teletaction Control System for Detection of Human Pulse Wave with Applications in Teleoperations

    Directory of Open Access Journals (Sweden)

    Javad Dargahi

    2008-01-01

    Full Text Available The design of a smart medical tool that can detect the human pulse and transfer its data to a remote location is presented. The resulting control system can be used to detect the pulse wave of human obtained from the wrist area. Fabrication of the tactile sensor and its calibration procedure are discussed as well. Additionally, the design of the pulse display system and that of its control system along with the position feedback control are accomplished. The experimental results of the position feedback control system are compared with the modeling and good agreement is obtained.

  13. The density broadening in a sodium F=2 condensate detected by a pulse train

    Directory of Open Access Journals (Sweden)

    Jianing Han

    2011-09-01

    Full Text Available The dipole-blockaded sodium clock transition has been detected by high resolution microwave spectroscopy, the multiple-pulse spectroscopy. This spectroscopic technique has been first used to detect the density broadening and shifting in a Sodium Bose Einstein Condensate (BEC by probing the sodium clock-transition. Moreover, by narrowing the pulse-width of the pulses, some of the broadening mechanisms can be partially reduced. The results reported here are essential steps toward the ground-state quantum computing, few-body spectroscopy, spin squeezing and quantum metrology.

  14. Inactivation of Pseudomonas putida by pulsed electric field treatment: a study on the correlation of treatment parameters and inactivation efficiency in the short-pulse range.

    Science.gov (United States)

    Frey, Wolfgang; Gusbeth, Christian; Schwartz, Thomas

    2013-10-01

    An important issue for an economic application of the pulsed electric field treatment for bacterial decontamination of wastewater is the specific treatment energy needed for effective reduction of bacterial populations. The present experimental study performed in a field amplitude range of 40 > E > 200 kV/cm and for a suspension conductivity of 0.01 = κ(e) > 0.2 S/m focusses on the application of short pulses, 25 ns > T > 10 μs, of rectangular, bipolar and exponential shape and was made on Pseudomonas putida, which is a typical and widespread wastewater microorganism. The comparison of inactivation results with calculations of the temporal and azimuthal membrane charging dynamics using the model of Pauly and Schwan revealed that for efficient inactivation, membrane segments at the cell equator have to be charged quickly and to a sufficiently high value, on the order of 0.5 V. After fulfilling this basic condition by an appropriate choice of pulse field strength and duration, the log rate of inactivation for a given suspension conductivity of 0.2 S/m was found to be independent of the duration of individual pulses for constant treatment energy expenditure. Moreover, experimental results suggest that even pulse shape plays a minor role in inactivation efficiency. The variation of the suspension conductivity resulted in comparable inactivation performance of identical pulse parameters if the product of pulse duration and number of pulses was the same, i.e., required treatment energy can be linearly downscaled for lower conductivities, provided that pulse amplitude and duration are selected for entire membrane surface permeabilization.

  15. Detection System Design of Electric Vehicle Wiring Harness

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-Xin; LI Xiao-Peng

    2015-01-01

    This paper introduces a method of harness testing system for electric vehicle wiring harness wiring .The system has implemented some commonly used electric wiring harness state detection using the way of the upper machine and lower machine communicate with each other, Such as normal, open circuit, short circuit, fault, etc. And then the lower machine send the wiring harness status to the upper machine, and then the upper machine parses the line state, and at the same time shows the test results, And then stores the test results in the database. After all, we can call at any time to check the date and the results of detection. It changes the traditional manual test mode of operation and Implements the detection process of automation and intellectualization.

  16. Numerical evaluation of lactoperoxidase inactivation during continuous pulsed electric field processing.

    Science.gov (United States)

    Buckow, Roman; Semrau, Julius; Sui, Qian; Wan, Jason; Knoerzer, Kai

    2012-01-01

    A computational fluid dynamics (CFD) model describing the flow, electric field and temperature distribution of a laboratory-scale pulsed electric field (PEF) treatment chamber with co-field electrode configuration was developed. The predicted temperature increase was validated by means of integral temperature studies using thermocouples at the outlet of each flow cell for grape juice and salt solutions. Simulations of PEF treatments revealed intensity peaks of the electric field and laminar flow conditions in the treatment chamber causing local temperature hot spots near the chamber walls. Furthermore, thermal inactivation kinetics of lactoperoxidase (LPO) dissolved in simulated milk ultrafiltrate were determined with a glass capillary method at temperatures ranging from 65 to 80 °C. Temperature dependence of first order inactivation rate constants was accurately described by the Arrhenius equation yielding an activation energy of 597.1 kJ mol(-1). The thermal impact of different PEF processes on LPO activity was estimated by coupling the derived Arrhenius model with the CFD model and the predicted enzyme inactivation was compared to experimental measurements. Results indicated that LPO inactivation during combined PEF/thermal treatments was largely due to thermal effects, but 5-12% enzyme inactivation may be related to other electro-chemical effects occurring during PEF treatments.

  17. Physical and electrical characteristics of NiFe thin films using ultrasonic assisted pulse electrodeposition

    Science.gov (United States)

    Asa Deepthi, K.; Balachandran, R.; Ong, B. H.; Tan, K. B.; Wong, H. Y.; Yow, H. K.; Srimala, S.

    2016-01-01

    Nickel iron (NiFe) thin films were prepared on the copper substrate by ultrasonic assisted pulse electrodeposition under galvanostatic mode. Careful control of the thin films deposition is essential as the electrical properties of the films could be greatly affected, particularly if low quality films are produced. The preparation of NiFe/Cu thin films was aimed to reduce the grain size of NiFe particles, surface roughness and electrical resistivity of the copper substrates. Various parameters were systematically studied including current magnitude, deposition time and ultrasonic bath temperature. The optimized conditions to obtain NiFe permalloy, which subsequently applied to all investigated samples, were found at a current magnitude of 70 mA deposited for a duration of 2 min under ultrasonic bath temperature of 27 °C. The composition of NiFe permalloy was as close as Ni 80.71% and Fe 19.29% and the surface roughness was reduced from 12.76 nm to 2.25 nm. The films electrical resistivity was decreased nearly sevenfold from an initial value of 67.32 μΩ cm to 9.46 μΩ cm.

  18. Carrier-envelope Phase Drift Detection of Picosecond Pulses

    Directory of Open Access Journals (Sweden)

    Cormier E.

    2013-03-01

    Full Text Available A bandwidth-independent, linear and scalable method for carrier-envelope phase drift measurement demonstrated. Our experiments reveal that carrier-envelope phase drift of a picosecond pulse train can be directly obtained from the spectrally resolved interference pattern of a length-stabilized multiple-beam interferometer. The retrieved phase from the pattern correlates well with the strongly CEP-sensitive coupling signal between the frequency combs of the picosecond oscillator and an ultra-high finesse Fabry-Perot interferometer. Our results can lead to the generation of a robust CEP-stabilized seed pulse train for high resolution comb spectroscopy as well as to compact Compton X-ray and gamma-ray sources

  19. Dapsone Induced Methaemoglobinemia: Early Intraoperative Detection by Pulse Oximeter Desaturation

    Directory of Open Access Journals (Sweden)

    Mahmood Rafiq

    2008-01-01

    Case signifies the importance of knowledge of any preoperative drug intake and its anaesthetic implications. Also patients on dapsone therapy especially children should be monitored for methaemoglobin levels. Since children with immune thrombocy-topenic purpura are being treated with dapsone these days and many of these patients would be planned for splenectomy, monitoring of preoperative methaemoglobin levels and methaemoglobinemia as a cause of intraoperative pulse oximeter desaturation should be kept in mind.

  20. Detecting Fleeting MRI Signals with Frequency-Modulated Pulses

    Science.gov (United States)

    Kobayashi, Naoharu; Idiyatullin, Djaudat; Corum, Curtis; Moeller, Steen; Chamberlain, Ryan; O'Connell, Robert; Nixdorf, Donald R.; Garwood, Michael

    2012-01-01

    We describe a fundamentally different approach to MRI referred to as SWIFT (sweep imaging with Fourier transformation). SWIFT exploits time-shared RF excitation and signal acquisition, allowing capture of signal from spins with extremely short transverse relaxation time, T2*. The MR signal is acquired in gaps inserted into a broadband frequency-swept excitation pulse, which results in acquisition delays of only 1 – 2 microseconds. In SWIFT, 3D k-space is sampled in a radial manner, whereby one projection of the object is acquired in the gaps of each frequency-swept pulse, allowing a repetition time (TR) on the order of the pulse length (typically 1 – 3 milliseconds). Since the orientation of consecutive projections varies in a smooth manner (i.e., only small increments in the values of the x, y, z gradients occur from view to view), SWIFT scanning is close to inaudible and is insensitive to gradient timing errors and eddy currents. SWIFT images can be acquired in scan times similar to and sometimes faster than conventional 3D gradient echo techniques. With its ability to capture signals from ultrashort T2* spins, SWIFT promises to expand the role of MRI in areas of research where MRI previously played no or negligible role. In this article, we show wood and tooth images obtained with SWIFT as examples of materials with ultrashort T2*. Early experience suggests SWIFT can play a role in materials science and porous media research. PMID:22661791

  1. Waveform descriptor for pulse onset detection of intracranial pressure signal.

    Science.gov (United States)

    Yang, Li; Zhao, Mingxi; Peng, Chenglin; Hu, Xiao; Feng, Hua; Ji, Zhong

    2012-03-01

    We present an algorithm to identify the onset of intracranial pressure (ICP) pulses. The algorithm creates a waveform descriptor to extract the feature of each local minimum of the waveform and then identifies the onset by comparing the feature with a customized template. The waveform descriptor is derived by transforming the vectors connecting a given point and the local waveform samples around it into log-polar coordinates and ranking them into uniform bins. Using an ICP dataset consisting of 40933 normal beats and 306 segments of artifacts and noise, we investigated the performance of our algorithm (waveform descriptor, WD), global minimum within a sliding window (GM) and two other algorithms originally proposed for arterial blood pressure (ABP) signal (slope sum function, SSF and pulse waveform delineator, PUD). As a result, all the four algorithms showed good performance and WD showed overall better one. At a tolerance level of 30 ms (i.e., the predicted onset and ground truth were considered as correctly matched if the distance between the two was equal or less than 30 ms), WD achieved a sensitivity of 0.9723 and PPV of 0.9475, GM achieved a sensitivity of 0.9226 and PPV of 0.8968, PUD achieved a sensitivity of 0.9599 and PPV of 0.9327 and SSF, a sensitivity of 0.9720 and PPV of 0.9136. The evaluation indicates that the algorithms are effective for identifying the onset of ICP pulses.

  2. Detection of Underwater Carrier-Free Pulse based on Time-Frequency Analysis

    Directory of Open Access Journals (Sweden)

    Yunlu Ni

    2013-01-01

    Full Text Available Carrier-free short pulse widely employed in UWB radar is brought into high-resolution sonar system, which has unique advantages: attaining more target information, restraining fluctuation of reverberation envelop efficiently in short-range detection and achieving accurate estimation. In essence such pulse is transiently short in time domain and wide in frequency domain, and as such it is difficult to separate signal to noise based on Fourier Transform spectrum. So as to seek for detection methods of short pulse, minor differences of energy distribution of time-frequency characteristics are presented on three time-frequency methods such as Short Time Fourier Transform, Wavelet Transform and Hilbert-Huang Transform. With these results, a tri-channel detector is established for such underwater short pulse in noise environment, which is generally suitable not only for detection module of underwater sonar system but also that of radar system.

  3. Formation of Structure in Hard-Alloy Coatings from Powders Under Passage of a Powerful Pulse of Electric Current

    Science.gov (United States)

    Novikov, S. V.; Peretyagin, P. Yu.; Dolzhikova, E. Yu.; Torrecillas, R.

    2016-01-01

    A method of ultrafast deposition of hard-alloy coatings from powders upon passage of a powerful pulse of electric current is considered. The structure of the coatings obtained by the electric-pulse and standard processes is studied by metallographic, electron microscope and x-ray diffraction analyses. The physical, mechanical and cutting properties of the hard-alloy coatings are determined. The endurance of the cutting tools with hard-alloy coatings is estimated under the conditions of large-scale and pilot productions. The possibility of creation of tools with enhanced operating characteristics is demonstrated.

  4. Electrical detection of magnetization reversal without auxiliary magnets

    Science.gov (United States)

    Olejník, K.; Novák, V.; Wunderlich, J.; Jungwirth, T.

    2015-05-01

    First-generation magnetic random access memories based on anisotropic magnetoresistance required magnetic fields for both writing and reading. Modern all-electrical read/write memories use instead nonrelativistic spin transport connecting the storing magnetic layer with a reference ferromagnet. Recent studies have focused on electrical manipulation of magnetic moments by relativistic spin torques requiring no reference ferromagnet. Here we report the observation of a counterpart magnetoresistance effect in such a relativistic system which allows us to electrically detect the sign of the magnetization without an auxiliary magnetic field or ferromagnet. We observe the effect in a geometry in which the magnetization of a uniaxial (Ga,Mn)As epilayer is set either parallel or antiparallel to a current-induced nonequilibrium spin polarization of carriers. In our structure, this linear-in-current magnetoresistance reaches 0.2% at current density of 106Acm -2 .

  5. Structural and Electrical Properties of Heteroepitaxial Magnetic Oxide Junction Diode Fabricated by Pulsed Laser Deposition

    Science.gov (United States)

    Li, M. K.; Wong, K. H.

    2010-11-01

    Heteroepitaxial junctions formed by p-type strontium doped lanthanum manganite and n-type cobalt doped titanium dioxide were fabricated on LaAlO3 (100) substrates by pulsed laser deposition. The La0.7Sr0.3MnO3 (LSMO) layers were grown at 650° C and under 150 mTorr ambient oxygen pressure. They showed room temperature ferromagnetism and metallic-like electrical conduction with a resistivity of 0.015 ohm cm at 300 K. The CoxTi1-xO2[x = 0.05 and 0.1] (CTO), which, at anatase phase, was reported as a wide-band-gap dilute magnetic semiconductor, was deposited on the LSMO film surface at 600° C with an ambient oxygen pressure of 20 mTorr. The as-grown CTO films exhibited pure anatase crystalline phase and semiconductor-like conduction. Under optimized fabrication conditions the CTO/LSMO junction revealed a heteroepitaxial relationship of (004)CTO‖‖(001)LSMO‖‖(001)LAO. Electrical characterization of these p-n junctions yielded excellent rectifying characteristics with a current rectifying ratio over 1000 at room temperature. The electrical transport across these diodes was dominated by diffusion current at low current (low bias voltage) regime and by recombination current at high current (high bias voltage) regime. Our results have demonstrated an all-oxide spintronic junction diode with good transport property. The simultaneous of electrical and magnetic modulation in a diode junction is therefore potentially realizable.

  6. Pulsed electric field-assisted modification of pectin from sugar beet pulp.

    Science.gov (United States)

    Ma, Sen; Wang, Zhong-he

    2013-02-15

    This current work is concerned with the modification of sugar beet pulp (SBP) pectin assisted by pulsed electric filed (PEF) without solvent. Pectin-arachates with degree of esterification (DE) ranging from 49 to 84 were prepared in one-step modification. The results showed that the DE of pectin derivatives increased significantly with the PEF intensity from 18 to 30 kV cm((1) and total specific energy input from 124 to 345 J mL((1). Evidence of modification of pectin was provided by FT-IR, X-ray diffraction patterns and NMR spectra. Thermogravimetric investigation of modified pectin indicated a higher thermal stability than the untreated one. Results revealed that PEF technology is a promising method for industrial manufacture of pectin derivatives.

  7. Spectral representation of the particle production out of equilibrium - Schwinger mechanism in pulsed electric fields

    CERN Document Server

    Fukushima, Kenji

    2014-01-01

    We develop a formalism to describe the particle production out of equilibrium in terms of dynamical spectral functions, i.e. Wigner transformed Pauli-Jordan's and Hadamard's functions. We take an explicit example of a spatially homogeneous scalar theory under pulsed electric fields and investigate the time evolution of the spectral functions. In the out-state we find an oscillatory peak in Hadamard's function as a result of the mixing between positive- and negative-energy waves. The strength of this peak is of the linear order of the Bogoliubov mixing coefficient, whereas the peak corresponding to the Schwinger mechanism is of the quadratic order. Between the in- and the out-states we observe a continuous flow of the spectral peaks together with two transient oscillatory peaks. We also discuss the medium effect at finite temperature and density. We emphasise that the entire structure of the spectral functions conveys rich information on real-time dynamics including the particle production.

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

    Science.gov (United States)

    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.

  9. Electrical characterization of gadolinia doped ceria films grown by pulsed laser deposition

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Heiroth, Sebastian; Lundberg, Mats

    2010-01-01

    Electrical characterization of 10 mol% gadolinia doped ceria (CGO10) films of different thicknesses prepared on MgO(100) substrates by pulsed laser deposition is presented. Dense, polycrystalline and textured films characterized by fine grains (grain sizes ... thickness. The conductivity of the nanocrystalline films is lower (7.0×10−4 S/cm for the 20-nm film and 3.6×10−3 S/cm for the 435-nm film, both at 500°C) than that of microcrystalline, bulk samples ( S/cm at 500°C). The activation energy for the conduction is found to be 0.83 eV for the bulk material, while...

  10. Changes of intracellular Na~+ concentration in erythrocytes caused by pulsed electrical field

    Institute of Scientific and Technical Information of China (English)

    张锦珠; 孙彤; 陈雅; 周淑华; 陈云俊; 庞素珍

    1997-01-01

    Changes of sodium ionic concentration of human erythrocytes applied to pulsed electrical field (PEF) were studied by using shift reagent and NMR spectroscopy. The results show that the concentration of intracellular Na+ increases with the increasing intensity of PEF when the erythrocytes are applied to PEF with higher intensities. The relationship between intracellular Na concentrations and the intensities of PEF does not follow linear or exponen-tial behavior. As the intensities increase, the intracellular Na+ concentrations increase even faster by an exponential curve. However under effects of PEF at lower intensities, intracellular Na+ concentration decreases. Ouabain can in-hibit the decrease of intracellular Na concentration, and the inhibition increases with the increasing concentration of ouabain, suggesting that Na , K -ATPase on cell membrane can be activated by PEF at lower intensities. Direct measurement of activities of the enzyme by using Malachite green method has confirmed this observatio

  11. The biological response of cells to nanosecond pulsed electric fields is dependent on plasma membrane cholesterol.

    Science.gov (United States)

    Cantu, Jody C; Tarango, Melissa; Beier, Hope T; Ibey, Bennett L

    2016-11-01

    Previous work from our laboratory demonstrated nanopore formation in cell membranes following exposure to nanosecond pulsed electric fields (nsPEF). We observed differences in sensitivity to nsPEF in both acute membrane injury and 24h lethality across multiple cells lines. Based on these data, we hypothesize that the biological response of cells to nsPEF is dependent on the physical properties of the plasma membrane (PM), including regional cholesterol content. Results presented in this paper show that depletion of membrane cholesterol disrupts the PM and increases the permeability of cells to small molecules, including propidium iodide and calcium occurring after fewer nsPEF. Additionally, cholesterol depletion concurrently decreases the "dose" of nsPEF required to induce lethality. In summary, the results of the current study suggest that the PM cholesterol composition is an important determinant in the cellular response to nsPEF. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    Seung Ho Kim

    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 sul-fides 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.

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

    Science.gov (United States)

    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.

  15. Stacked Blumlein devices generating high-power, nanosecond-wide electrical pulses

    Science.gov (United States)

    Borovina, Dan Lucretiu

    1997-11-01

    Many important advances in modern technology will require input powers which are too high to deliver continuously. Fortunately, constant operation is not necessary for some applications. In those cases, electrical input power can be delivered in pulses with specifically tailored characteristics. The most demanding applications create the need for particular combinations of operating parameters that are important in high-energy lasers, advanced accelerators and the generation of high-power microwaves; and those lie at the focus of this work. Conventional devices had been able to provide some of the parameters in the same arrangement, but none could deliver all of them at once. In 1993, when this work was initiated, the concept of a high-voltage solid state switch capable of being triggered on demand held promise for a solution, despite traditional obstacles. Initially, all common solid-state materials, including GaAs and Si, had been designed for low-power applications, and attempts to extend their performance to higher powers created some problems. For high-voltage operation, these switches required some sort of isolation from the command circuit. Optical triggering solved these problems in a device known as a photoconductive switch. However, for some modern applications, which require pulses with very fast risetimes, conventional photoconductive switch technology was limited by the time required to produce enough charge carriers for commutation. Carrier generation could be accomplished in one of two ways. The first involved the use of an intense laser pulse with a fast risetime to produce all carriers through photon absorption. In this case, the necessary laser had to be large and expensive, and required its own high-power pulser, similar to the one being built, making this approach impractical. The second method involved the initiation of a fast, non- linear, avalanche process within the semiconductor, using a more conventional light pulse. This technique

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

    Science.gov (United States)

    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.

  17. Impact of pulsed-electric field and high-voltage electrical discharges on red wine microbial stabilization and quality characteristics.

    Science.gov (United States)

    Delsart, C; Grimi, N; Boussetta, N; Miot Sertier, C; Ghidossi, R; Vorobiev, E; Mietton Peuchot, M

    2016-01-01

    In this study, pulsed-electric fields (PEF) and high-voltage electrical discharges (HVED) are proposed as new techniques for the microbial stabilization of red wines before bottling. The efficiency of the treatment was then evaluated. PEF and HVED-treatments have been applied to wine for the inactivation of Oenococcus oeni CRBO 9304, O. oeni CRBO 0608, Pediococcus parvulus CRBO 2.6 and Brettanomyces bruxellensis CB28. Different treatment times (1, 2, 4, 6, 8 and 10 ms) were used at 20 kV cm(-1) for the PEF treatments and at 40 kV for the HVED treatments, which correspond to applied energies from 80 to 800 kJ l(-1) . The effects of the treatments on the microbial inactivation rate and on various characteristics of red wines (phenolic composition, chromatic characteristics and physico-chemical parameters) were measured. The application of PEF or HVED treatments on red wine allowed the inactivation of alteration yeasts (B. bruxellensis CB28) and bacteria (O. oeni CRBO 9304, O. oeni CRBO 0608 and P. parvulus CRBO 2.6). The electric discharges at 40 kV were less effective than the PEF even after 10 ms of treatments. Indeed, 4 ms of PEF treatment at 20 kV cm(-1) were sufficient to inactivate all micro-organisms present in the wines. Also, the use of PEF had no negative impact on the composition of wines compared to the HVED treatments. Contrary to PEF, the phenolics compounds were degraded after the HVED treatment and the physico-chemical composition of wine were modified with HVED. PEF technology seems to be an interesting alternative to stabilize microbiologically wines before bottling and without modifying their composition. This process offers many advantages for winemakers: no chemical inputs, low energy consumption (320 kJ l(-1) ), fast (treatment time of 4 ms) and athermal (ΔT ≈ 10°C). © 2015 The Society for Applied Microbiology.

  18. Attosecond streaking measurement of extreme ultraviolet pulses using a long-wavelength electric field

    Science.gov (United States)

    Saito, Nariyuki; Ishii, Nobuhisa; Kanai, Teruto; Watanabe, Shuntaro; Itatani, Jiro

    2016-01-01

    Long-wavelength lasers have great potential to become a new-generation drive laser for tabletop coherent light sources in the soft X-ray region. Because of the significantly low conversion efficiency from a long-wavelength light field to high-order harmonics, their pulse characterization has been carried out by measuring the carrier-envelope phase and/or spatial dependences of high harmonic spectra. However, these photon detection schemes, in general, have difficulty in obtaining information on the spectral phases, which is crucial to determine the temporal structures of high-order harmonics. Here, we report the first attosecond streaking measurement of high harmonics generated by few-cycle optical pulses at 1.7 μm from a BiB3O6–based optical parametric chirped-pulse amplifier. This is also the first demonstration of time-resolved photoelectron spectroscopy using high harmonics from a long-wavelength drive laser other than Ti:sapphire lasers, which paves the way towards ultrafast soft X-ray photoelectron spectroscopy. PMID:27752115

  19. Attosecond streaking measurement of extreme ultraviolet pulses using a long-wavelength electric field

    Science.gov (United States)

    Saito, Nariyuki; Ishii, Nobuhisa; Kanai, Teruto; Watanabe, Shuntaro; Itatani, Jiro

    2016-10-01

    Long-wavelength lasers have great potential to become a new-generation drive laser for tabletop coherent light sources in the soft X-ray region. Because of the significantly low conversion efficiency from a long-wavelength light field to high-order harmonics, their pulse characterization has been carried out by measuring the carrier-envelope phase and/or spatial dependences of high harmonic spectra. However, these photon detection schemes, in general, have difficulty in obtaining information on the spectral phases, which is crucial to determine the temporal structures of high-order harmonics. Here, we report the first attosecond streaking measurement of high harmonics generated by few-cycle optical pulses at 1.7 μm from a BiB3O6-based optical parametric chirped-pulse amplifier. This is also the first demonstration of time-resolved photoelectron spectroscopy using high harmonics from a long-wavelength drive laser other than Ti:sapphire lasers, which paves the way towards ultrafast soft X-ray photoelectron spectroscopy.

  20. Postnatal brain development of the pulse type, weakly electric gymnotid fish Gymnotus omarorum.

    Science.gov (United States)

    Iribarne, Leticia; Castelló, María E

    2014-01-01

    Teleosts are a numerous and diverse group of fish showing great variation in body shape, ecological niches and behaviors, and a correspondent diversity in brain morphology, usually associated with their functional specialization. Weakly electric fish are a paradigmatic example of functional specialization, as these teleosts use self-generated electric fields to sense the nearby environment and communicate with conspecifics, enabling fish to better exploit particular ecological niches. We analyzed the development of the brain of the pulse type gymnotid Gymnotus omarorum, focusing on the brain regions involved directly or indirectly in electrosensory information processing. A morphometric analysis has been made of the whole brain and of brain regions of interest, based on volumetric data obtained from 3-D reconstructions to study the growth of the whole brain and the relative growth of brain regions, from late larvae to adulthood. In the smallest studied larvae some components of the electrosensory pathway appeared to be already organized and functional, as evidenced by tract-tracing and in vivo field potential recordings of electrosensory-evoked activity. From late larval to adult stages, rombencephalic brain regions (cerebellum and electrosensory lateral line lobe) showed a positive allometric growth, mesencephalic brain regions showed a negative allometric growth, and the telencephalon showed an isometric growth. In a first step towards elucidating the role of cell proliferation in the relative growth of the analyzed brain regions, we also studied the spatial distribution of proliferation zones by means of pulse type BrdU labeling revealed by immunohistochemistry. The brain of G. omarorum late larvae showed a widespread distribution of proliferating zones, most of which were located at the ventricular-cisternal lining. Interestingly, we also found extra ventricular-cisternal proliferation zones at in the rombencephalic cerebellum and electrosensory lateral line

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

    Energy Technology Data Exchange (ETDEWEB)

    Veda Prakash, G.; Kumar, R.; Saurabh, K.; Nasir,; Anitha, V. P.; Chowdhuri, M. B.; Shyam, A. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2016-01-15

    A comparative study of electrical breakdown properties of deionized water (H{sub 2}O) and heavy water (D{sub 2}O) 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.

  2. Induction of Cell Death Mechanisms and Apoptosis by Nanosecond Pulsed Electric Fields (nsPEFs

    Directory of Open Access Journals (Sweden)

    Nova M. Sain

    2013-03-01

    Full Text Available Pulse power technology using nanosecond pulsed electric fields (nsPEFs offers a new stimulus to modulate cell functions or induce cell death for cancer cell ablation. New data and a literature review demonstrate fundamental and basic cellular mechanisms when nsPEFs interact with cellular targets. NsPEFs supra-electroporate cells creating large numbers of nanopores in all cell membranes. While nsPEFs have multiple cellular targets, these studies show that nsPEF-induced dissipation of ΔΨm closely parallels deterioration in cell viability. Increases in intracellular Ca2+ alone were not sufficient for cell death; however, cell death depended of the presence of Ca2+. When both events occur, cell death ensues. Further, direct evidence supports the hypothesis that pulse rise-fall times or high frequency components of nsPEFs are important for decreasing ΔΨm and cell viability. Evidence indicates in Jurkat cells that cytochrome c release from mitochondria is caspase-independent indicating an absence of extrinsic apoptosis and that cell death can be caspase-dependent and –independent. The Ca2+ dependence of nsPEF-induced dissipation of ΔΨm suggests that nanoporation of inner mitochondria membranes is less likely and effects on a Ca2+-dependent protein(s or the membrane in which it is embedded are more likely a target for nsPEF-induced cell death. The mitochondria permeability transition pore (mPTP complex is a likely candidate. Data demonstrate that nsPEFs can bypass cancer mutations that evade apoptosis through mechanisms at either the DISC or the apoptosome.

  3. Disassembly of actin structures by nanosecond pulsed electric field is a downstream effect of cell swelling.

    Science.gov (United States)

    Pakhomov, Andrei G; Xiao, Shu; Pakhomova, Olga N; Semenov, Iurii; Kuipers, Marjorie A; Ibey, Bennett L

    2014-12-01

    Disruption of the actin cytoskeleton structures was reported as one of the characteristic effects of nanosecond-duration pulsed electric field (nsPEF) in both mammalian and plant cells. We utilized CHO cells that expressed the monomeric fluorescent protein (mApple) tagged to actin to test if nsPEF modifies the cell actin directly or as a consequence of cell membrane permeabilization. A train of four 600-ns pulses at 19.2 kV/cm (2 Hz) caused immediate cell membrane poration manifested by YO-PRO-1 dye uptake, gradual cell rounding and swelling. Concurrently, bright actin features were replaced by dimmer and uniform fluorescence of diffuse actin. To block the nsPEF-induced swelling, the bath buffer was isoosmotically supplemented with an electropore-impermeable solute (sucrose). A similar addition of a smaller, electropore-permeable solute (adonitol) served as a control. We demonstrated that sucrose efficiently blocked disassembly of actin features by nsPEF, whereas adonitol did not. Sucrose also attenuated bleaching of mApple-tagged actin in nsPEF-treated cells (as integrated over the cell volume), although did not fully prevent it. We conclude that disintegration of the actin cytoskeleton was a result of cell swelling, which, in turn, was caused by cell permeabilization by nsPEF and transmembrane diffusion of solutes which led to the osmotic imbalance.

  4. Pulsed-electric-field-assisted extraction of anthocyanins from purple-fleshed potato.

    Science.gov (United States)

    Puértolas, Eduardo; Cregenzán, Oliver; Luengo, Elisa; Alvarez, Ignacio; Raso, Javier

    2013-02-15

    The influence of pulsed electric field (PEF) treatment on the anthocyanin extraction yield (AEY) from purple-fleshed potato (PFP) at different extraction times (60-480 min) and temperatures (10-40°C) using water and ethanol (48% and 96%) as solvents has been investigated. Response surface methodology was used to determine optimal PEF treatment and optimise anthocyanin extraction. A PEF treatment of 3.4 kV/cm and 105 μs (35 pulses of 3 μs) resulted in the highest cell disintegration index (Z(p)=1) at the lowest specific energy requirements (8.92 kJ/kg). This PEF treatment increased the AEY, the effect being higher at lower extraction temperature with water as solvent. After 480 min at 40°C, the AEY obtained for the untreated sample using 96% ethanol as the solvent (63.9 mg/100 g fw) was similar to that obtained in the PEF-treated sample using water (65.8 mg/100 g fw). Therefore, PEF was possible with water, a more environmental-friendly solvent than ethanol, without decreasing the AEY from PFP.

  5. Single Pulse Electrical Stimulation to identify epileptogenic cortex: Clinical information obtained from early evoked responses.

    Science.gov (United States)

    Mouthaan, B E; van 't Klooster, M A; Keizer, D; Hebbink, G J; Leijten, F S S; Ferrier, C H; van Putten, M J A M; Zijlmans, M; Huiskamp, G J M

    2016-02-01

    Single Pulse Electrical Stimulation (SPES) probes epileptogenic cortex during electrocorticography. Two SPES responses are described: pathological delayed responses (DR, >100 ms) associated with the seizure onset zone (SOZ) and physiological early responses (ER, 80 Hz, in the SOZ and seizure propagation areas. We used data from 12 refractory epilepsy patients. SPES consisted of 10 pulses of 1 ms, 4-8 mA and 5s interval on adjacent electrodes pairs. Data were available at 2048 samples/s for six and 512 samples/s (22 bits) for eight patients and analyzed in the time-frequency (TF) and time-domain (TD). Electrodes with ERs were stronger associated with SOZ than non-SOZ electrodes. ERs with frequency content >80 Hz exist and are specific for SOZ channels. ERs evoked by stimulation of seizure onset electrodes were associated with electrodes involved in seizure propagation. Analysis of ERs can reveal aspects of pathology, manifested by association with seizure propagation and areas with high ER numbers that coincide with the SOZ. Not only DRs, but also ERs could have clinical value for mapping epileptogenic cortex and help to unravel aspects of the epileptic network. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  6. Theoretical study of rectangular pulse electrical stimulation (RPES) onskin cells (in vivo) under conforming electrodes.

    Science.gov (United States)

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

    1993-01-01

    Our previous in vivo experimental results have shown RPES can enhance skin wound healing by using conforming electrodes. Based on an equation of polarization transmembrane voltage [Cole, K. S. 1972], two equations were derived to describe the peak RPES intensity on skin cells in vivo: (1) U = 1.5 a J/sigma, (2) Jm = 1.5 a (J/sigma) (Cm/tau). Where U: polarization transmembrane voltage. a: radius (R) for spherical cells or semi-length (L) for long fibers parallel to the electrical field. J: external imposed pulse current density under the electrode. sigma: average conductivity of skin tissue. Jm: transmembrane displacement current density. Cm: membrane capacitance per unit area and tau: time constant. Calculations indicated that the sensory fibers (SF) would receive the strongest stimulation compared to other cells in skin since generally LSF > or = 100 R. The sensitivity of SF to the stimulation could enhance skin wound healing as well as protect normal skin cells from harmful electroporation. From these theoretical calculations. We proposed a theoretical range of the pulse current density as: U1 sigma/(1.5 L) < or = J < or = U2 sigma/(1.5 L), where U1 and U2 are the excitation threshold voltage (about 0.01 V) and polarization electroporation voltage (about 0.1 V) for a SF respectively, for RPES to enhance skin wound healing.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-01-05

    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.

  9. Receiving and Detection of Ultra-Wideband Microwave Signals Radiated by Pulsed Excitation of Monopole Antennas

    Directory of Open Access Journals (Sweden)

    Steponas AŠMONTAS

    2014-06-01

    Full Text Available Pulsed excitation of small size monopole antennas for generating wideband electromagnetic pulses was used. The monopoles were excited by electrical pulses having rise times of 600 ps, 200 ps, 70 ps and voltages 100 V, 15 V, and 0.4 V respectively. Antennas spanning (0.3 – 26 GHz bandwidth, including broadband horns with coaxial outputs, were employed to receive signals, which were investigated using (0 – 26 GHz passband sampling oscilloscope. It was found that waveforms of signals, received by the antennas, mostly depend on the pulse rise time and on the details of geometry of monopoles. The electromagnetic pulses have relatively long duration of about 30 ns and spectral harmonics up to 22 GHz. Therefore they can be attributed to pulses with large base. The results show that the upper frequencies of the spectrum most probably are cut off by existing arrangement. Usage of such pulses can find wide practical application when they are received after transmission trough different media by a number of antennas having different operational frequency ranges, followed by digital signal processing. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6330

  10. Practical photon number detection with electric field-modulated silicon avalanche photodiodes.

    Science.gov (United States)

    Thomas, O; Yuan, Z L; Shields, A J

    2012-01-24

    Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current.

  11. Electrical detection of spin hyperpolarization in InP

    Science.gov (United States)

    Caspers, Christian; Ansermet, Jean-Philippe

    2014-09-01

    The electrical detection of surface spin polarization in Indium Phosphide (InP) is demonstrated. Using a planar four-terminal architecture on top of semi-insulating Fe:InP (001) wafers, optical orientation is separated from electrical detection. Spin filter tunnel contacts consisting of InP/oxide/Co reveal significant asymmetries in the differential resistance upon helicity change of the optical pumping. The iron-rich tunnel oxide provides the main spin selection mechanism. A reproducible helicity-dependent asymmetry as high as 18% could be observed at T = 55 K and an external induction field μ0H = 1 T. At room temperature and zero external field, a helicity-dependent asymmetry of 6% suggests the stand-alone applicability of the device either as an electronic spin sensor or as an optical helicity sensor.

  12. Electrical detection of spin hyperpolarization in InP

    Energy Technology Data Exchange (ETDEWEB)

    Caspers, Christian; Ansermet, Jean-Philippe [Laboratoire de Physique des Matériaux Nanostructurés, École Polytechnique Fédérale de Lausanne EPFL, 1015 Lausanne (Switzerland)

    2014-09-29

    The electrical detection of surface spin polarization in Indium Phosphide (InP) is demonstrated. Using a planar four-terminal architecture on top of semi-insulating Fe:InP (001) wafers, optical orientation is separated from electrical detection. Spin filter tunnel contacts consisting of InP/oxide/Co reveal significant asymmetries in the differential resistance upon helicity change of the optical pumping. The iron-rich tunnel oxide provides the main spin selection mechanism. A reproducible helicity-dependent asymmetry as high as 18% could be observed at T = 55 K and an external induction field μ{sub 0}H = 1 T. At room temperature and zero external field, a helicity-dependent asymmetry of 6% suggests the stand-alone applicability of the device either as an electronic spin sensor or as an optical helicity sensor.

  13. Electric Field Detection in Sawfish and Shovelnose Rays

    Science.gov (United States)

    Wueringer, Barbara E.; Jnr, Lyle Squire; Kajiura, Stephen M.; Tibbetts, Ian R.; Hart, Nathan S.; Collin, Shaun P.

    2012-01-01

    In the aquatic environment, living organisms emit weak dipole electric fields, which spread in the surrounding water. Elasmobranchs detect these dipole electric fields with their highly sensitive electroreceptors, the ampullae of Lorenzini. Freshwater sawfish, Pristis microdon, and two species of shovelnose rays, Glaucostegus typus and Aptychotrema rostrata were tested for their reactions towards weak artificial electric dipole fields. The comparison of sawfishes and shovelnose rays sheds light on the evolution and function of the elongated rostrum (‘saw’) of sawfish, as both groups evolved from a shovelnose ray-like ancestor. Electric stimuli were presented both on the substrate (to mimic benthic prey) and suspended in the water column (to mimic free-swimming prey). Analysis of around 480 behavioural sequences shows that all three species are highly sensitive towards weak electric dipole fields, and initiate behavioural responses at median field strengths between 5.15 and 79.6 nVcm−1. The response behaviours used by sawfish and shovelnose rays depended on the location of the dipoles. The elongation of the sawfish’s rostrum clearly expanded their electroreceptive search area into the water column and enables them to target free-swimming prey. PMID:22848543

  14. Developing nucleic acid-based electrical detection systems

    OpenAIRE

    Gabig-Ciminska Magdalena

    2006-01-01

    Abstract Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and r...

  15. Developing nucleic acid-based electrical detection systems

    OpenAIRE

    Gabig-Ciminska Magdalena

    2006-01-01

    Abstract Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and r...

  16. The change of electric potentials in the oral cavity after application of extremely low frequency pulsed magnetic field

    Directory of Open Access Journals (Sweden)

    Piotr Skomro

    2012-12-01

    Full Text Available Electric potentials occurring in the oral cavity deserve attention as they may cause various diseases and subjective feelings, which are very difficult to treat. The aim of this study was to evaluate the electric potentials within the oral cavity in patients with metal fillings and metal prosthetic restorations, after using a pulsed electromagnetic field. The study was carried out on 84 patients. The Viofor JPS Classic device was used in the treatment. It generates a pulsed electromagnetic field with low induction of the extremely low frequency (ELF range. Average values of electric potentials in the preliminary test were about the same in both groups; they were 148.8 mV and 145.5 mV. After another appliance of ELF fields there was found a steady decline in the average value of electric potentials in the study group. This decrease was statistically highly significant, while mean values of electric potentials in the control group were characterized by a slightly upward tendency. The obtained statistically significant reduction of electric potentials in the oral cavity of patients having metal fillings and metal prosthetic restorations, after application of the Viofor JPS Classic device, implies a huge impact of ELF pulsed electromagnetic field on inhibition of electrochemical processes, as well as on inhibition of dental alloy corrosion. 

  17. The change of electric potentials in the oral cavity after application of extremely low frequency pulsed magnetic field.

    Science.gov (United States)

    Skomro, Piotr; Lietz-Kijak, Danuta; Kijak, Edward; Bogdziewicz-Wałęsa, Olga; Opalko, Krystyna

    2012-12-11

    Electric potentials occurring in the oral cavity deserve attention as they may cause various diseases and subjective feelings, which are very difficult to treat. The aim of this study was to evaluate the electric potentials within the oral cavity in patients with metal fillings and metal prosthetic restorations, after using a pulsed electromagnetic field. The study was carried out on 84 patients. The Viofor JPS Classic device was used in the treatment. It generates a pulsed electromagnetic field with low induction of the extremely low frequency (ELF) range. Average values of electric potentials in the preliminary test were about the same in both groups; they were 148.8 mV and 145.5 mV. After another appliance of ELF fields there was found a steady decline in the average value of electric potentials in the study group. This decrease was statistically highly significant, while mean values of electric potentials in the control group were characterized by a slightly upward tendency. The obtained statistically significant reduction of electric potentials in the oral cavity of patients having metal fillings and metal prosthetic restorations, after application of the Viofor JPS Classic device, implies a huge impact of ELF pulsed electromagnetic field on inhibition of electrochemical processes, as well as on inhibition of dental alloy corrosion. 

  18. Electrical detection of magnetization dynamics via spin rectification effects

    Science.gov (United States)

    Harder, Michael; Gui, Yongsheng; Hu, Can-Ming

    2016-11-01

    The purpose of this article is to review the current status of a frontier in dynamic spintronics and contemporary magnetism, in which much progress has been made in the past decade, based on the creation of a variety of micro and nanostructured devices that enable electrical detection of magnetization dynamics. The primary focus is on the physics of spin rectification effects, which are well suited for studying magnetization dynamics and spin transport in a variety of magnetic materials and spintronic devices. Intended to be intelligible to a broad audience, the paper begins with a pedagogical introduction, comparing the methods of electrical detection of charge and spin dynamics in semiconductors and magnetic materials respectively. After that it provides a comprehensive account of the theoretical study of both the angular dependence and line shape of electrically detected ferromagnetic resonance (FMR), which is summarized in a handbook format easy to be used for analysing experimental data. We then review and examine the similarity and differences of various spin rectification effects found in ferromagnetic films, magnetic bilayers and magnetic tunnel junctions, including a discussion of how to properly distinguish spin rectification from the spin pumping/inverse spin Hall effect generated voltage. After this we review the broad applications of rectification effects for studying spin waves, nonlinear dynamics, domain wall dynamics, spin current, and microwave imaging. We also discuss spin rectification in ferromagnetic semiconductors. The paper concludes with both historical and future perspectives, by summarizing and comparing three generations of FMR spectroscopy which have been developed for studying magnetization dynamics.

  19. Electrical biomolecule detection using nanopatterned silicon via block copolymer lithography.

    Science.gov (United States)

    Jeong, Chang Kyu; Jin, Hyeong Min; Ahn, Jae-Hyuk; Park, Tae Jung; Yoo, Hyeon Gyun; Koo, Min; Choi, Yang-Kyu; Kim, Sang Ouk; Lee, Keon Jae

    2014-01-29

    An electrical biosensor exploiting a nanostructured semiconductor is a promising technology for the highly sensitive, label-free detection of biomolecules via a straightforward electronic signal. The facile and scalable production of a nanopatterned electrical silicon biosensor by block copolymer (BCP) nano-lithography is reported. A cost-effective and large-area nanofabrication, based on BCP self-assembly and single-step dry etching, is developed for the hexagonal nanohole patterning of thin silicon films. The resultant nanopatterned electrical channel modified with biotin molecules successfully detects the two proteins, streptavidin and avidin, down to nanoscale molarities (≈1 nm). The nanoscale pattern comparable to the Debye screening length and the large surface area of the three-dimensional silicon nanochannel enable excellent sensitivity and stability. A device simulation confirms that the nanopatterned structure used in this work is effective for biomolecule detection. This approach relying on the scalable self-assembly principle offers a high-throughput manufacturing process for clinical lab-on-a-chip diagnoses and relevant biomolecular studies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Electrical discharge machining (EDM) of Inconel 718 by using copper electrode at higher peak current and pulse duration

    Science.gov (United States)

    Ahmad, S.; Lajis, M. A.

    2013-12-01

    This experimental work is an attempt to investigate the performance of Copper electrode when EDM of Nickel Based Super Alloy, Inconel 718 is at higher peak current and pulse duration. Peak current, Ip and pulse duration (pulse on-time), ton are selected as the most important electrical pulse parameters. In addition, their influence on material removal rate (MRR), electrode wear rate (EWR), and surface roughness (Ra) are experimentally investigated. The ranges of 10 mm diameter of Copper electrode are used to EDM of Inconel 718. After the experiments, MRR, EWR, and Ra of the machined surfaces need to be measured in order to evaluate the performance of the EDM process. In order to obtain high MRR, higher peak current in range of 20A to 40A and pulse duration in range of 200μs to 400μs were used. Experimental results have shown that machining at a highest peak current used of 40A and the lowest pulse duration of 200μs used for the experiment yields the highest material removal rate (MRR) with value 34.94 mm3/min, whereas machining at a peak current of 20A and pulse duration of 400μs yields the lowest electrode wear rate (EWR) with value -0.0101 mm3/min. The lowest surface roughness (Ra) is 8.53 μm achieved at a lowest peak current used of 20A and pulse duration of 200μs.

  1. Double-pulse standoff laser-induced breakdown spectroscopy for versatile hazardous materials detection

    Energy Technology Data Exchange (ETDEWEB)

    Gottfried, Jennifer L. [U.S. Army Research Laboratory, AMSRD-ARL-WM-BD, Aberdeen Proving Ground, MD, 21005-5069 (United States)], E-mail: jennifer.gottfried@arl.army.mil; De Lucia, Frank C.; Munson, Chase A.; Miziolek, Andrzej W. [U.S. Army Research Laboratory, AMSRD-ARL-WM-BD, Aberdeen Proving Ground, MD, 21005-5069 (United States)

    2007-12-15

    We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate.

  2. Optimised NQR pulse technique for the effective detection of Heroin Base.

    Science.gov (United States)

    Rudakov, T N; Hayes, P A; Flexman, J H

    2008-03-01

    The nuclear quadrupole resonance (NQR) method has been applied to Heroin Base (HB) to find an optimised multi-pulse technique for effective detection of HB. Experimental results of applying the proposed spin-locking multi-pulse (SLMP) technique to nitrogen-14 NQR in this sample are presented and convincingly demonstrate as a path towards efficient detection. A detection using a sequence of this character could be achieved over real-world scan volumes for screening of goods. All experiments were carried out at room temperature.

  3. Detection of acrolein and acrylonitrile with a pulsed room temperature quantum cascade laser

    Science.gov (United States)

    Manne, J.; Jäger, W.; Tulip, J.

    2010-06-01

    We investigated the use of a pulsed, distributed feedback quantum cascade laser centered at 957 cm-1 in combination with an astigmatic Herriot cell with 250 m path length for the detection of acrolein and acrylonitrile. These molecules have been identified as hazardous air-pollutants because of their adverse health effects. The spectrometer utilizes the intra-pulse method, where a linear frequency down-chirp, that is induced when a top-hat current pulse is applied to the laser, is used for sweeping across the absorption line. Up to 450 ns long pulses were used for these measurements which resulted in a spectral window of ~2.2 cm-1. A room temperature mercury-cadmium-telluride detector was used, resulting in a completely cryogen free spectrometer. We demonstrated detection limits of ~3 ppb for acrylonitrile and ~6 ppb for acrolein with ~10 s averaging time. Laser characterization and optimization of the operational parameters for sensitivity improvement are discussed.

  4. Effects of Pulsed Electric Field (PEF) Treatment on Enhancing Activity and Conformation of α-Amylase.

    Science.gov (United States)

    Tian, Mei-ling; Fang, Ting; Du, Mu-ying; Zhang, Fu-sheng

    2016-04-01

    To explore an efficient, safe, and speedy application of pulsed electric field (PEF) technology for enzymatic modification, effects of PEF treatment on the enzymatic activity, property and kinetic parameters of α-amylase were investigated. Conformational transitions were also studied with the aid of circular dichroism (CD) and fluorescence spectra. The maximum enzymatic activity of α-amylase was obtained under 15 kV/cm electric field intensity and 100 mL/min flow velocity PEF treatment, in which the enzymatic activity increased by 22.13 ± 1.14% compared with control. The activation effect could last for 18 h at 4 °C. PEF treatment could widen the range of optimum temperature for α-amylase, however, it barely exerted any effect on the optimum pH. On the other hand, α-amylase treated by PEF showed an increase of Vmax, t1/2 and ΔG, whereas a decrease of Km and k were observed. Furthermore, it can be observed from fluorescence and CD spectra that PEF treatment had increased the number of amino acid residues, especially that of tryptophan, on α-amylase surface with enhanced α-helices by 34.76% and decreased random coil by 12.04% on α-amylase when compared with that of untreated. These changes in structure had positive effect on enhancing α-amylase activity and property.

  5. Nanosecond pulsed sliding dielectric barrier discharge plasma actuator for airflow control: Electrical, optical, and mechanical characteristics

    Science.gov (United States)

    Bayoda, K. D.; Benard, N.; Moreau, E.

    2015-08-01

    Plasma actuators used for active flow control are widely studied because they could replace mechanical actuators. Industrial applications of these plasma actuators sometimes require a large surface plasma sheet in view of increasing the interaction region between the discharge and the incoming flow. Instead of using a typical two-electrode nanosecond pulsed dielectric barrier discharge for which the interaction region is limited to about 20 mm, this study proposes to characterize a nanosecond sliding discharge based on a three-electrode geometry in order to increase the extension length up to the electrode gap. This sliding discharge is compared to the typical nanosecond dielectric barrier discharge by means of electrical, optical, and mechanical diagnostics. Electrical characterization reveals that the deposited energy can be widely increased. Time-resolved Intensified Charge Coupled Device (iCCD) images of the discharge development over the dielectric surface highlight that the intensity and the propagation velocity of streamers are strongly affected by the DC voltage applied at the third electrode. Finally, qualitative and quantitative characterizations of the pressure wave due to the surrounding gas heating are proposed by means of Schlieren visualizations and high frequency pressure measurements, respectively.

  6. Structural and electrical properties of tantalum oxide films grown by photo-assisted pulsed laser deposition

    Science.gov (United States)

    Zhang, Jun-Ying; Boyd, Ian W.

    2002-01-01

    We describe the growth of thin films of Ta 2O 5 on quartz and silicon (1 0 0) substrates by an in situ photo-assisted pulsed laser deposition (photo-PLD) using radiation from a Nd:YAG laser (wavelength, λ=532 nm) to stimulate the ablation, and from an excimer lamp to excite additional photochemistry. The layers grown were investigated by Fourier transform infrared (FT-IR) spectroscopy, UV spectrophotometry, atomic force microscopy (AFM), ellipsometry and electrical measurements. We have found that they exhibit a significant improvement in microstructure, and optical and electrical properties compared with conventional PLD films prepared under, otherwise, identical conditions. For example, FT-IR results showed that the suboxide content in the as-grown films deposited by the photo-PLD process is less, while the leakage current density was an order of magnitude less at around 10 -6 A/cm 2 at a bias of 1 V. These results indicate that this photo-PLD process approach can be advantageous for dielectric and optical oxide film growth.

  7. Photobiomodulation laser and pulsed electrical field increase the viability of the musculocutaneous flap in diabetic rats.

    Science.gov (United States)

    Leite, Gabriella de Paula Marcondes Ferreira; das Neves, Lais Mara Siqueira; Silva, Carlos Alberto; Guirro, Rinaldo Roberto de Jesus; de Souza, Thamires Rodrigues; de Souza, Ana Karina; Garcia, Sérgio Britto; Guirro, Elaine Caldeira de Oliveira

    2017-04-01

    The purpose of this study is to investigate the effect of pulsed electrical field (PEF) and photobiomodulation laser (PBM) on the viability of the TRAM flap in diabetic rats. Fifty Wistar rats were divided into five homogeneous groups: Group 1-control; Group 2-diabetics; Group 3-diabetics + PEF; Group 4-diabetic + laser 660 nm, 10 J/cm(2), 0.27 J; Group 5-diabetic + laser 660 nm, 140 J/cm(2), 3.9 J. The percentage of necrotic area was evaluated using software Image J®. The peripheral circulation of the flap was evaluated by infrared thermography FLIR T450sc (FLIR® Systems-Oregon USA). The thickness of the epidermis (haematoxylin-eosin), mast cell (toluidine blue), leukocytes, vascular endothelial growth factor, fibroblast and newly formed blood vessels were evaluated. For the statistical analysis, the Kruskal-Wallis test was applied followed by Dunn and ANOVA test followed by Tukey with critical level of 5% (p electrical field increase the viability of the musculocutaneous flap in diabetic rats.

  8. Reducing Viscosity of Liquid Suspensions by pulsed electric or magnetic field

    Science.gov (United States)

    Tao, R.

    2007-03-01

    Viscosity of liquid suspensions is of great importance. Controlling the viscosity is vital in science and engineering. In electrorheological (ER) or magentorheological (MR) fluids, electric or magnetic field is used to increase the viscosity. However, in most cases we need to lower the viscosity. For example, reducing blood's viscosity improves circulation and prevents cardiovascular events. Lowering the viscosity of crude oil is the key to transporting offshore oil via undersea pipelines. Unfortunately, to date there are no effective methods for reducing the viscosity except by changing the temperature. In case that changing temperature is not an option, such as in the above examples, reducing the viscosity becomes formidable. Here we present a theory and experimental results showing that application of a suitable electric or magnetic field pulse can significantly reduce the viscosity of liquid suspensions for several hours with no change of temperature. The field induces dipolar interactions between the suspended particles and forces them to aggregate into large particles. The aggregation changes the rheological properties of the fluids and reduces the effective viscosity. Positive experimental results with MR fluids and crude oil indicate that this method, developed from the basic mechanism of viscosity, is universal and powerful for all liquid suspensions with broad applications.

  9. Electric pulse stimulation of cultured murine muscle cells reproduces gene expression changes of trained mouse muscle.

    Directory of Open Access Journals (Sweden)

    Nathalie Burch

    Full Text Available Adequate levels of physical activity are at the center of a healthy lifestyle. However, the molecular mechanisms that mediate the beneficial effects of exercise remain enigmatic. This gap in knowledge is caused by the lack of an amenable experimental model system. Therefore, we optimized electric pulse stimulation of muscle cells to closely recapitulate the plastic changes in gene expression observed in a trained skeletal muscle. The exact experimental conditions were established using the peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1alpha as a marker for an endurance-trained muscle fiber. We subsequently compared the changes in the relative expression of metabolic and myofibrillar genes in the muscle cell system with those observed in mouse muscle in vivo following either an acute or repeated bouts of treadmill exercise. Importantly, in electrically stimulated C2C12 mouse muscle cells, the qualitative transcriptional adaptations were almost identical to those in trained muscle, but differ from the acute effects of exercise on muscle gene expression. In addition, significant alterations in the expression of myofibrillar proteins indicate that this stimulation could be used to modulate the fiber-type of muscle cells in culture. Our data thus describe an experimental cell culture model for the study of at least some of the transcriptional aspects of skeletal muscle adaptation to physical activity. This system will be useful for the study of the molecular mechanisms that regulate exercise adaptation in muscle.

  10. Electropermeabilization by uni- or bipolar nanosecond electric pulses: The impact of extracellular conductivity.

    Science.gov (United States)

    Gianulis, Elena C; Casciola, Maura; Xiao, Shu; Pakhomova, Olga N; Pakhomov, Andrei G

    2017-08-25

    Cellular effects caused by nanosecond electric pulses (nsEP) can be reduced by an electric field reversal, a phenomenon known as bipolar cancellation. The reason for this cancellation effect remains unknown. We hypothesized that assisted membrane discharge is the mechanism for bipolar cancellation. CHO-K1 cells bathed in high (16.1mS/cm; HCS) or low (1.8mS/cm; LCS) conductivity solutions were exposed to either one unipolar (300-ns) or two opposite polarity (300+300-ns; bipolar) nsEP (4-40kV/cm) with increasing interpulse intervals (0.1-50μs). Time-lapse YO-PRO-1 (YP) uptake revealed enhanced membrane permeabilization in LCS compared to HCS at all tested voltages. The time-dependence of bipolar cancellation was similar in both solutions, using either identical (22kV/cm) or isoeffective nsEP treatments (12 and 32kV/cm for LCS and HCS, respectively). However, cancellation was significantly stronger in LCS when the bipolar nsEP had no, or very short (bipolar cancellation was still present with interpulse intervals as long as 50μs, beyond the time expected for membrane discharge. Our findings do not support assisted membrane discharge as the mechanism for bipolar cancellation. Instead they exemplify the sustained action of nsEP that can be reversed long after the initial stimulus. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

  12. Synthesis of Electrical Conductive Silica Nanofiber/Gold Nanoparticle Composite by Laser Pulses and Sputtering Technique

    Science.gov (United States)

    Hamza, Sarah; Ignaszak, Anna; Kiani, Amirkianoosh

    2017-06-01

    Biocompatible-sensing materials hold an important role in biomedical applications where there is a need to translate biological responses into electrical signals. Increasing the biocompatibility of these sensing devices generally causes a reduction in the overall conductivity due to the processing techniques. Silicon is becoming a more feasible and available option for use in these applications due to its semiconductor properties and availability. When processed to be porous, it has shown promising biocompatibility; however, a reduction in its conductivity is caused by its oxidization. To overcome this, gold embedding through sputtering techniques are proposed in this research as a means of controlling and further imparting electrical properties to laser induced silicon oxide nanofibers. Single crystalline silicon wafers were laser processed using an Nd:YAG pulsed nanosecond laser system at different laser parameters before undergoing gold sputtering. Controlling the scanning parameters (e.g., smaller line spacings) was found to induce the formation of nanofibrous structures, whose diameters grew with increasing overlaps (number of laser beam scanning through the same path). At larger line spacings, nano and microparticle formation was observed. Overlap (OL) increases led to higher light absorbance's by the wafers. The gold sputtered samples resulted in greater conductivities at higher gold concentrations, especially in samples with smaller fiber sizes. Overall, these findings show promising results for the future of silicon as a semiconductor and a biocompatible material for its use and development in the improvement of sensing applications.

  13. Electro-stimulation of Saccharomyces cerevisiae wine yeasts by Pulsed Electric Field and its effect on fermentation performance

    CERN Document Server

    Mattar, J; Nonus, M; Lebovka, N I; Zakhem, H El; Vorobiev, E

    2013-01-01

    The batch fermentation process, inoculated by pulsed electric field (PEF) treated wine yeasts (S. cerevisiae Actiflore F33), was studied. PEF treatment was applied to the aqueous yeast suspensions (0.12 % wt.) at the electric field strengths of E=100 and 6000 V/cm using the same pulse protocol (number of pulses of n=1000, pulse duration of ti=100 mks, and pulse repetition time of dt=100 ms). Electro-stimulation was confirmed by the observed growth of electrical conductivity of suspensions. The fermentation was running at 30{\\deg}C for 150 hours in an incubator with synchronic agitation. The obtained results clearly evidence the positive impact of PEF treatment on the batch fermentation process. Electro-stimulation resulted in improvement of such process characteristics as mass losses, consumption of soluble matter content ({\\deg}Brix) and synthesis of proteins. It also resulted in a noticeable acceleration of consumption of sugars at the initial stage of fermentation in the lag phase. At the end of the lag ph...

  14. Detection and analysis of multi-dimensional pulse wave based on optical coherence tomography

    Science.gov (United States)

    Shen, Yihui; Li, Zhifang; Li, Hui; Chen, Haiyu

    2014-11-01

    Pulse diagnosis is an important method of traditional Chinese medicine (TCM). Doctors diagnose the patients' physiological and pathological statuses through the palpation of radial artery for radial artery pulse information. Optical coherence tomography (OCT) is an useful tool for medical optical research. Current conventional diagnostic devices only function as a pressure sensor to detect the pulse wave - which can just partially reflect the doctors feelings and lost large amounts of useful information. In this paper, the microscopic changes of the surface skin above radial artery had been studied in the form of images based on OCT. The deformation of surface skin in a cardiac cycle which is caused by arterial pulse is detected by OCT. The patient's pulse wave is calculated through image processing. It is found that it is good consistent with the result conducted by pulse analyzer. The real-time patient's physiological and pathological statuses can be monitored. This research provides a kind of new method for pulse diagnosis of traditional Chinese medicine.

  15. Pulsed photothermal interferometry for spectroscopic gas detection with hollow-core optical fibre

    Science.gov (United States)

    Lin, Yuechuan; Jin, Wei; Yang, Fan; Ma, Jun; Wang, Chao; Ho, Hoi Lut; Liu, Yang

    2016-12-01

    Gas detection with hollow-core photonic bandgap fibre (HC-PBF) and pulsed photothermal (PT) interferometry spectroscopy are studied theoretically and experimentally. A theoretical model is developed and used to compute the gas-absorption-induced temperature and phase modulation in a HC-PBF filled with low-concentration of C2H2 in nitrogen. The PT phase modulation dynamics for different pulse duration, peak power and energy of pump beam are numerically modelled, which are supported by the experimental results obtained around the P(9) absorption line of C2H2 at 1530.371 nm. Thermal conduction is identified as the main process responsible for the phase modulation dynamics. For a constant peak pump power level, the phase modulation is found to increase with pulse duration up to ~1.2 μs, while it increases with decreasing pulse duration for a constant pulse energy. It is theoretically possible to achieve ppb level detection of C2H2 with ~1 m length HC-PBF and a pump beam with ~10 ns pulse duration and ~100 nJ pulse energy.

  16. Sensitive detection of acrolein and acrylonitrile with a pulsed quantum-cascade laser

    Science.gov (United States)

    Manne, J.; Lim, A.; Tulip, J.; Jäger, W.

    2012-05-01

    We report on spectroscopic measurements of acrolein and acrylonitrile at atmospheric pressure using a pulsed distributed feedback quantum-cascade laser in combination with intra- and inter-pulse techniques and compare the results. The measurements were done in the frequency region around 957 cm-1. In the inter-pulse technique, the laser is excited with short current pulses (5-10 ns), and the pulse amplitude is modulated with an external current ramp resulting in a ˜2.3 cm-1 frequency scan. In the intra-pulse technique, a linear frequency down-chirp during the pulse is used for sweeping across the absorption line. Long current pulses up to 500 ns were used for these measurements which resulted in a spectral window of ˜2.2 cm-1 during the down-chirp. These comparatively wide spectral windows facilitated the measurements of the relatively broad absorption lines (˜1 cm-1) of acrolein and acrylonitrile. The use of a room-temperature mercury-cadmium-telluride detector resulted in a completely cryogen-free spectrometer. We demonstrate ppb level detection limits within a data acquisition time of ˜10 s with these methodologies.

  17. Detecting Electric Dipoles Interaction at the Interface of Ferroelectric and Electrolyte Using Graphene Field Effect Transistors.

    Science.gov (United States)

    Ma, Chunrui; Lu, Rongtao; Hu, Guangliang; Han, Jinsheng; Liu, Ming; Li, Jun; Wu, Judy

    2017-02-01

    Graphene was inserted into the interface between electric dipole layers from DEME-TFSI ionic liquid (top-gate) and ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT, back-gate) to probe the interface dipole-dipole interaction in response to DC and pulsed gate voltages. A highly complicated behavior of the interface dipole-dipole interaction has been revealed as a combination of electrostatic and electrochemical effects. The interfacial polar molecules in the DEME-TFSI electrical double layer are pinned with assistance from the PLZT back-gate in response to a DC top-gate pump, leading to strong nonlinear electrochemical behavior. In contrast, depinning of these molecules can be facilitated by a faster pulsed top-gate pump, which results in a characteristic linear electrostatic behavior. This result not only sheds light on the dynamic dipole-dipole interactions on the interface between functional materials but also prototypes a unique pump and probe approach using graphene field effect transistors to detect the interface dipole-dipole interaction.

  18. Electrical breakdown detection system for dielectric elastomer actuators

    Science.gov (United States)

    Ghilardi, Michele; Busfield, James J. C.; Carpi, Federico

    2017-04-01

    Electrical breakdown of dielectric elastomer actuators (DEAs) is an issue that has to be carefully addressed when designing systems based on this novel technology. Indeed, in some systems electrical breakdown might have serious consequences, not only in terms of interruption of the desired function but also in terms of safety of the overall system (e.g. overheating and even burning). The risk for electrical breakdown often cannot be completely avoided by simply reducing the driving voltages, either because completely safe voltages might not generate sufficient actuation or because internal or external factors might change some properties of the actuator whilst in operation (for example the aging or fatigue of the material, or an externally imposed deformation decreasing the distance between the compliant electrodes). So, there is the clear need for reliable, simple and cost-effective detection systems that are able to acknowledge the occurrence of a breakdown event, making DEA-based devices able to monitor their status and become safer and "selfaware". Here a simple solution for a portable detection system is reported that is based on a voltage-divider configuration that detects the voltage drop at the DEA terminals and assesses the occurrence of breakdown via a microcontroller (Beaglebone Black single-board computer) combined with a real-time, ultra-low-latency processing unit (Bela cape an open-source embedded platform developed at Queen Mary University of London). The system was used to both generate the control signal that drives the actuator and constantly monitor the functionality of the actuator, detecting any breakdown event and discontinuing the supplied voltage accordingly, so as to obtain a safer controlled actuation. This paper presents preliminary tests of the detection system in different scenarios in order to assess its reliability.

  19. Edge Detection System using Pulse Mode Neural Network for Image Enhancement

    Directory of Open Access Journals (Sweden)

    S.Jagadeesh Babu

    2012-04-01

    Full Text Available Edge detection of an image reduces significantly the amount of data and filters out information that may be regarded as less irrelevant. Edge detection is efficient in medical imaging. Pulse mode neural networks are becoming an attractive solution for function approximation based on frequency modulation. Early pulse mode implementation suffers from some network constraints due to weight range limitations. To provide the best edge detection, the basic algorithm is modified to have pulse mode operations for effective hardware implementation. In this project a new pulse mode network architecture using floating point operations is used in the activation function. By using floating point number system for synapse weight value representation, any function can be approximated by the network. The proposed pulse mode MNN is used to detect the edges in images forming a heterogeneous data base. It shows good learning capability. In addition, four edge detection techniques have been compared. The coding is written in verilog and the final result have been simulated using Xilinx ISE simulator.

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

    Science.gov (United States)

    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) ...

  1. Effect of pulsed electric fields on the activity of neutral trehalase from beer yeast and RSM analysis.

    Science.gov (United States)

    Ye, Haiqing; Jin, Yan; Lin, Songyi; Liu, Mingyuan; Yang, Yi; Zhang, Meishuo; Zhao, Ping; Jones, Gregory

    2012-06-01

    The trehalase activity plays an important role in extraction of trehalose from beer yeast. In this study, the effect of pulsed electric field processing on neutral trehalase activity in beer yeast was investigated. In order to develop and optimize a pulsed electric field (PEF) mathematical model for activating the neutral trehalase, we have investigated three variables, including electric field intensity (10-50 kV/cm), pulse duration (2-10 μs) and liquid-solid ratio (20-50 ml/g) and subsequently optimized them by response surface methodology (RSM). The experimental data were fitted to a second-order polynomial equation and profiled into the corresponding contour plots. Optimal condition obtained by RSM is as follows: electric field intensity 42.13 kV/cm, liquid-solid ratio 30.12 ml/g and pulse duration 5.46 μs. Under these conditions, with the trehalose decreased 8.879 mg/L, the PEF treatment had great effect on activating neutral trehalase in beer yeast cells.

  2. Double-Pulse Spectra and Closed-Orbits: Photodetachment of H-in Parallel Electric and Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    DU Meng-Li

    2003-01-01

    We derive a formula for double-pulse spectra from closed-orbit theory. We then calculate the double-pulsephotodetachment spectra of H- in the presence of parallel electric and magnetic fields. We analyze the spectra in termsof closed-orbits of the system. We suggest a method for the measurement of a phase associated with each closed-orbit.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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....

  5. Selective extraction of intracellular components from the microalga Chlorella vulgaris by combined pulsed electric field-temperature treatment

    NARCIS (Netherlands)

    Postma, P.R.; Pataro, G.; Capitoli, M.; Barbosa, M.J.; Wijffels, R.H.; Eppink, M.H.M.; Olivieri, G.; Ferrari, G.

    2016-01-01

    The synergistic effect of temperature (25-65°C) and total specific energy input (0.55-1.11kWhkgDW -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 2

  6. Calcium Phosphate Coating on Al2 O3 Ceramics by a Biomimetic Method Using Electric Pulse Technique

    Institute of Scientific and Technical Information of China (English)

    JIN Zhengguo; SHI Yong; GUO Wenli; WANG Ying; QIU Jijun

    2005-01-01

    The preparation of calcium phosphate (CP) coating on alumina ceramics using electric pulse stimulating method has been investigated. The cup-shaped alumina ceramics were soaked in a simulated body fluid (SBF), and a square pulse potential with frequency of 1 Hz and voltage of 110 V was applied between the inner and outer surfaces of the alumina cup. Surface morphology of CP coatings during different deposition periods was observed by a Philips XL-30 scanning electron microscope (SEM). Compositional analysis was examined by EDAX. The mechanism of nucleation and growth of CP coating was discussed. SEM result indicates that the coating comprises of a large number of tiny needle-like grains and has a porous microstructure. There is a strong bond between the deposited layer and Al2O3 substrate, which may be due to the gentle growth of the biomimetic method. The EDAX analysis indicates that main composition of the coating is calcium and phosphor. The formation of CP coating may be contributed to the stimulation of electric pulse and the high ions concentration which is 1.5 times of the concentration of SBF solution (1.5SBF solution). Such surface functionalization method by electric pulse potential can be used to prepare CP coating on various electric-insulating bioinert materials for improving their bioactive character.

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

    Science.gov (United States)

    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 ...

  8. Selective extraction of intracellular components from the microalga Chlorella vulgaris by combined pulsed electric field-temperature treatment

    NARCIS (Netherlands)

    Postma, P.R.; Pataro, G.; Capitoli, M.; Barbosa, M.J.; Wijffels, R.H.; Eppink, M.H.M.; Olivieri, G.; Ferrari, G.

    2016-01-01

    The synergistic effect of temperature (25-65°C) and total specific energy input (0.55-1.11kWhkgDW -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

  9. Evaluation of energy transfer and utilization efficiency of azo dye removal by different pulsed electrical discharge modes

    Institute of Scientific and Technical Information of China (English)

    SHEN YongJun; LEI LeCheng; ZHANG XingWang

    2008-01-01

    The degradation of an azo dye, acid orange 7 (AO7), caused by different high voltage pulsed electrical discharge modes (spark, streamer and corona discharge) induced by the various initial conductivities was investigated. A new type of pulsed high voltage source with thyratron switch and Blumlein pulse forming net (BPFN) was used. The typical discharge waveforms of voltage, current, power, pulse en-ergy and the pictures of spark, streamer and corona discharge modes were presented. The results in-dicated that pulsed electrical discharges led to complete decolorization and substantial decrease of the chemical oxygen demand (COD) of the dye solution. The main intermediate products were monitored by GC-MS. The discharge modes changed from spark to streamer and to corona discharge, and the streamer length decreased with the liquid conductivity increasing. At a constant input power, the peak voltage, peak current, peak power and energy per pulse of the three discharge modes ranked in the following order: spark > streamer > corona. The effective energy transfer efficiency of AO7 removal was higher for spark discharge (57.2%) than for streamer discharge (40.4%) and corona discharge (27.6%). Moreover, the energy utilization efficiency of AO7 removal for spark discharge was 1.035×109 mol/J, and for streamer and corona discharge they were 0.646×10-8 and 0.589×10-9mol/J. Both the energy transfer efficiency and the energy utilization efficiency of spark discharge were the highest.

  10. Coal seam hazard detection using synthetic-pulse radar

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, J.C.; Hale, S.D.

    1981-04-01

    The development of ground-probing radar for mapping coal seams has proceeded in two different directions. The first is short-pulse radar which is principally used in a reflecton mode. The second is CW radar which is used with geotomographic interpretation methods. Each has disadvantages when implemented for mining applications. The authors present a new method which combines advantages of the reflection techniques with penetration distances of CW radar. Results of laboratory field testing of the new system are presented. The system holds promise of being able to map obstacles in the coal seam to distances in excess of 200 ft. A prototype field system which will be portable and easy to handle is now under construction. It is designed for operation anywhere in the coal mine and will have a small processor to present a quick display of reflection data.

  11. Cationic peptide exposure enhances pulsed-electric-field-mediated membrane disruption.

    Directory of Open Access Journals (Sweden)

    Stephen M Kennedy

    Full Text Available 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.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.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 current advancements in cell targeting techniques will be

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

    Science.gov (United States)

    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

  13. Metal release in a stainless steel pulsed electric field (PEF) system Part II. The treatment of orange juice; related to legislation and treatment chamber lifetime

    NARCIS (Netherlands)

    Roodenburg, B.; Morren, J.; Berg, H.E.; Haan, S.W.H.de

    2005-01-01

    In the last decennia, there is an increasing interest in pulsed electric field (PEF) treatment. The product is often treated in a continuous flow treatment chamber with stainless steel electrodes and exposed to short pulsed electric fields, typically 2-4 kV mm-1 during 1-10 μs. Due to direct contact

  14. Metal release in a stainless steel pulsed electric field (PEF) system Part II. The treatment of orange juice; related to legislation and treatment chamber lifetime

    NARCIS (Netherlands)

    Roodenburg, B.; Morren, J.; Berg, H.E.; Haan, S.W.H.de

    2005-01-01

    In the last decennia, there is an increasing interest in pulsed electric field (PEF) treatment. The product is often treated in a continuous flow treatment chamber with stainless steel electrodes and exposed to short pulsed electric fields, typically 2-4 kV mm-1 during 1-10 μs. Due to direct contact

  15. A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives

    Science.gov (United States)

    Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert; Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin; Lane, Stephen

    2011-12-01

    AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at ˜10-50 Hz and emits ˜106n/pulse at a peak current of 100 kA. Both sources emit 2.45±0.1 MeV (DD) neutron pulses of ˜25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm3 in volume.

  16. A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert [Alameda Applied Sciences Corporation, 3077 Teagarden Street, San Leandro, CA 94577 (United States); Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin [XIA LLC, 31057 Genstar Road, Hayward, CA 94544 (United States); Lane, Stephen [NSF Center for Biophotonics and School of Medicine, University of California Davis, Sacramento CA, 95817 (United States)

    2011-12-13

    AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at {approx}10-50 Hz and emits {approx}10{sup 6}n/pulse at a peak current of 100 kA. Both sources emit 2.45{+-}0.1 MeV(DD) neutron pulses of {approx}25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm{sup 3} in volume.

  17. Effect of low-frequency pulse percutaneous electric stimulation on peripheral nerve injuries at different sites

    Institute of Scientific and Technical Information of China (English)

    Jinwu Wang; Liye Chen; Qi Li; Weifeng Ni; Min Zhang; Shangchun Guo; Bingfang Zeng

    2006-01-01

    BACKGROUND: The postoperative recovery of nerve function in patients with peripheral nerve injury is always an important problem to solve after treatment. The electric stimulation induced electromagnetic field can nourish nerve, postpone muscular atrophy, and help the postoperative neuromuscular function.OBJECTIVE: To observe the effects of low-frequency pulse percutaneous electric stimulation on the functional recovery of postoperative patients with peripheral nerve injury, and quantitatively evaluate the results of electromyogram (EMG) examination before and after treatment.DESIGN: A retrospective case analysis.SETTING: The Sixth People's Hospital affiliated to Shanghai Jiaotong University.PARTICIPANTS: Nineteen postoperative inpatients with peripheral nerve injury were selected from the Department of Orthopaedics, the Sixth People's Hospital affiliated to Shanghai Jiaotong University from June 2005 to January 2006, including 13 males and 6 females aged 24-62 years with an average of 36 years old.There were 3 cases of brachial plexus nerve injury, 3 of median nerve injury, 7 of radial nerve injury, 3 of ulnar nerve injury and 3 of common peroneal nerve injury, and all the patients received probing nerve fiber restoration. Their main preoperative manifestations were dennervation, pain in limbs, motor and sensory disturbances. All the 19 patients were informed with the therapeutic program and items for evaluation.METHODS : ① Low-frequency pulse percutaneous electric stimulation apparatus: The patients were given electric stimulation with the TERESA cantata instrument (TERESA-0, Shanghai Teresa Health Technology, Co.,Ltd.). The patients were stimulated with symmetric square waves of 1-111 Hz, and the intensity was 1.2-5.0 mA, and it was gradually adjusted according to the recovered conditions of neural regeneration following the principle that the intensity was strong enough and the patients felt no obvious upset. They were treated for 4-24 weeks, 10-30 minutes

  18. Low-background detection of fission neutrons produced by pulsed neutron interrogation

    Science.gov (United States)

    Ruddy, Frank H.; Flammang, Robert W.; Seidel, John G.

    2009-01-01

    Measurements designed to detect shielded Special Nuclear Materials (SNM) have been carried out using a pulsed 8.5-MeV neutron source. Fission-neutron counts were detected as a function of time in the intervals between 100-μs neutron bursts at burst frequencies of 500, 1000, and 2000 Hz. The pulse timing sequences were chosen to optimize detection of fission neutrons produced by thermal-neutron-induced fission in the SNM. Fission neutrons were detected directly as proton, carbon, and silicon recoils in silicon carbide (SiC) semiconductor fast neutron detectors. SiC detectors recorded neutron counts during and immediately following the source neutron bursts, allowing detection of fission neutrons with short (120 μs) die-away times. The SiC detectors demonstrated excellent background discrimination with more than 2000 neutron counts observed in time intervals where zero background counts were detected.

  19. Technical specifications manual for the MARK-1 pulsed ionizing radiation detection system. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, R.S.; Harker, Y.D.; Jones, J.L.; Hoggan, J.M.

    1993-03-01

    The MARK-1 detection system was developed by the Idaho National Engineering Laboratory for the US Department of Energy Office of Arms Control and Nonproliferation. The completely portable system was designed for the detection and analysis of intense photon emissions from pulsed ionizing radiation sources. This manual presents the technical design specifications for the MARK-1 detection system and was written primarily to assist the support or service technician in the service, calibration, and repair of the system. The manual presents the general detection system theory, the MARK-1 component design specifications, the acquisition and control software, the data processing sequence, and the system calibration procedure. A second manual entitled: Volume 2: Operations Manual for the MARK-1 Pulsed Ionizing Radiation Detection System (USDOE Report WINCO-1108, September 1992) provides a general operational description of the MARK-1 detection system. The Operations Manual was written primarily to assist the field operator in system operations and analysis of the data.

  20. Electrical detection of liquid lithium leaks from pipe jointsa)

    Science.gov (United States)

    Schwartz, J. A.; Jaworski, M. A.; Mehl, J.; Kaita, R.; Mozulay, R.

    2014-11-01

    A test stand for flowing liquid lithium is under construction at Princeton Plasma Physics Laboratory. As liquid lithium reacts with atmospheric gases and water, an electrical interlock system for detecting leaks and safely shutting down the apparatus has been constructed. A defense in depth strategy is taken to minimize the risk and impact of potential leaks. Each demountable joint is diagnosed with a cylindrical copper shell electrically isolated from the loop. By monitoring the electrical resistance between the pipe and the copper shell, a leak of (conductive) liquid lithium can be detected. Any resistance of less than 2 kΩ trips a relay, shutting off power to the heaters and pump. The system has been successfully tested with liquid gallium as a surrogate liquid metal. The circuit features an extensible number of channels to allow for future expansion of the loop. To ease diagnosis of faults, the status of each channel is shown with an analog front panel LED, and monitored and logged digitally by LabVIEW.

  1. Effect of pulsed electric fields on the flavour profile of red-fleshed sweet cherries (Prunus avium var. Stella).

    Science.gov (United States)

    Sotelo, Kristine Ann Gualberto; Hamid, Nazimah; Oey, Indrawati; Gutierrez-Maddox, Noemi; Ma, Qianli; Leong, Sze Ying

    2015-03-23

    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.

  2. Fabrication Of YSZ Thin Film By Electrochemical Deposition Method And The Effect Of The Pulsed Electrical Fields For Morphology Control

    Directory of Open Access Journals (Sweden)

    Fujita T.

    2015-06-01

    Full Text Available In this study, surface morphology control ions in a precursor solution and patterning the YSZ film has been carried out during deposition of thin film from a precursor solution by applying the electrical field for deposition and the pulsed electrical field. The precursor solution was mixed them of ZrO(NO34, Y(NO33-6H2O into deionized water, and then was controlled nearly pH3 by adding NH3(aq. The thin film was deposited on the glass substrate of the minus electrode side by applying the electrical field of 3.0 V for 20 min. In addition, another pulsed voltage was applied to the electrical field along the perdicular direction to the film deposition direction. After annealing samples at 773 K for 6 h in air, the film was crystallized and obtained YSZ film. In the limited condition, the linear patterns of YSZ films due to the frequency of the applied electrical field were observed. It is expected that ions in a precursor solution are controlled by applying the pulsed voltage and the YSZ film is patterned on the substrate.

  3. Predicting dynamic range and intensity discrimination for electrical pulse-train stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

    Science.gov (United States)

    Xu, Yifang; Collins, Leslie M

    2005-06-01

    This work investigates dynamic range and intensity discrimination for electrical pulse-train stimuli that are modulated by noise using a stochastic auditory nerve model. Based on a hypothesized monotonic relationship between loudness and the number of spikes elicited by a stimulus, theoretical prediction of the uncomfortable level has previously been determined by comparing spike counts to a fixed threshold, Nucl. However, no specific rule for determining Nucl has been suggested. Our work determines the uncomfortable level based on the excitation pattern of the neural response in a normal ear. The number of fibers corresponding to the portion of the basilar membrane driven by a stimulus at an uncomfortable level in a normal ear is related to Nucl at an uncomfortable level of the electrical stimulus. Intensity discrimination limens are predicted using signal detection theory via the probability mass function of the neural response and via experimental simulations. The results show that the uncomfortable level for pulse-train stimuli increases slightly as noise level increases. Combining this with our previous threshold predictions, we hypothesize that the dynamic range for noise-modulated pulse-train stimuli should increase with additive noise. However, since our predictions indicate that intensity discrimination under noise degrades, overall intensity coding performance may not improve significantly.

  4. Accuracy of pulse oximeters in detecting hypoxemia in patients with chronic thromboembolic pulmonary hypertension.

    Directory of Open Access Journals (Sweden)

    Tomoki Kohyama

    Full Text Available Pulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO2. When oxygen saturation by pulse oximeter (SpO2 overestimates SaO2, hypoxemia may be overlooked. We compared the SpO2 - SaO2 differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH who spent their daily lives in a poor oxygen state.This prospective observational study recruited 32 patients with CTEPH undergoing elective cardiac catheterization. As we collected arterial blood samples in the catheter laboratory, SpO2 values were simultaneously recorded. Three pulse oximeters were used on each patient, and SpO2 values were compared with oximetry readings using a blood gas analyzer. To determine the optimal SpO2 value by which to detect hypoxemia (SaO2≦90%, we generated receiver operating characteristic (ROC curves for each pulse oximeter.The root mean square of each pulse oximeter was 1.79 (OLV-3100, 1.64 (N-BS, and 2.50 (Masimo Radical. The mean bias (SpO2 - SaO2 for the 90%-95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001. The optimal SpO2 value to detect hypoxemia (SaO2≦90% was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical.We found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO2 should be determined for each pulse oximeter.

  5. Calcium-independent disruption of microtubule dynamics by nanosecond pulsed electric fields in U87 human glioblastoma cells

    Science.gov (United States)

    Carr, Lynn; Bardet, Sylvia M.; Burke, Ryan C.; Arnaud-Cormos, Delia; Leveque, Philippe; O’Connor, Rodney P.

    2017-01-01

    High powered, nanosecond duration, pulsed electric fields (nsPEF) cause cell death by a mechanism that is not fully understood and have been proposed as a targeted cancer therapy. Numerous chemotherapeutics work by disrupting microtubules. As microtubules are affected by electrical fields, this study looks at the possibility of disrupting them electrically with nsPEF. Human glioblastoma cells (U87-MG) treated with 100, 10 ns, 44 kV/cm pulses at a frequency of 10 Hz showed a breakdown of their interphase microtubule network that was accompanied by a reduction in the number of growing microtubules. This effect is temporally linked to loss of mitochondrial membrane potential and independent of cellular swelling and calcium influx, two factors that disrupt microtubule growth dynamics. Super-resolution microscopy revealed microtubule buckling and breaking as a result of nsPEF application, suggesting that nsPEF may act directly on microtubules. PMID:28117459

  6. A bacterial spore model of pulsed electric fields on spore morphology change revealed by simulation and SEM.

    Science.gov (United States)

    Qiu, Xing; Lee, Yin Tung; Yung, Pun To

    2014-01-01

    A two-layered spore model was proposed to analyze morphological change of bacterial spores subjected under pulsed electric fields. The outer layer, i.e. spore coat, was defined by Mooney-Rivlin hyper-elastic material model. The inner layer, i.e. peptidoglycan and spore core, was modeled by applying additional adhesion forces. The effect of pulsed electric fields on surface displacement was simulated in COMSOL Multiphysics and verified by SEM. The electro-mechanical theory, considering spore coat as a capacitor, was used to explain concavity; and the thin viscoelastic film theory, considering membrane bilayer as fluctuating surfaces, was used to explain leakage forming. Mutual interaction of external electric fields, charged spores, adhesion forces and ions movement were all predicted to contribute to concavity and leakage.

  7. Calcium-independent disruption of microtubule dynamics by nanosecond pulsed electric fields in U87 human glioblastoma cells.

    Science.gov (United States)

    Carr, Lynn; Bardet, Sylvia M; Burke, Ryan C; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

    2017-01-24

    High powered, nanosecond duration, pulsed electric fields (nsPEF) cause cell death by a mechanism that is not fully understood and have been proposed as a targeted cancer therapy. Numerous chemotherapeutics work by disrupting microtubules. As microtubules are affected by electrical fields, this study looks at the possibility of disrupting them electrically with nsPEF. Human glioblastoma cells (U87-MG) treated with 100, 10 ns, 44 kV/cm pulses at a frequency of 10 Hz showed a breakdown of their interphase microtubule network that was accompanied by a reduction in the number of growing microtubules. This effect is temporally linked to loss of mitochondrial membrane potential and independent of cellular swelling and calcium influx, two factors that disrupt microtubule growth dynamics. Super-resolution microscopy revealed microtubule buckling and breaking as a result of nsPEF application, suggesting that nsPEF may act directly on microtubules.

  8. An integrated ultrasonic-inductive pulse sensor for wear debris detection

    Science.gov (United States)

    Du, Li; Zhe, Jiang

    2013-02-01

    One approach to detect signs of potential machine failure is to detect wear debris in the lubrication oil of a rotating or reciprocating machine because the size and the concentration of wear debris particles in the oil show a direct relationship with the level of wear. In this article, a proof-of-principle integrated wear debris sensor consisting of an ultrasonic pulse sensor and an inductive pulse sensor for detecting wear debris in lubrication oil is presented. The ultrasonic pulse sensor detects all solid debris (metallic and non-metallic debris). A flow recess structure is utilized to ensure that all wear debris passes the acoustic focal region so that all debris can be accurately counted and sized. The inductive pulse sensor detects and counts all metallic debris (ferrous and non-ferrous) based on the inductive Coulter counting principle. By comparing the results from the two sensing components, the sensor is capable of differentiating and detecting non-metallic debris, ferrous metallic debris and non-ferrous metallic debris.

  9. Increasing sensitivity of pulse EPR experiments using echo train detection schemes

    Science.gov (United States)

    Mentink-Vigier, F.; Collauto, A.; Feintuch, A.; Kaminker, I.; Tarle, V.; Goldfarb, D.

    2013-11-01

    Modern pulse EPR experiments are routinely used to study the structural features of paramagnetic centers. They are usually performed at low temperatures, where relaxation times are long and polarization is high, to achieve a sufficient Signal/Noise Ratio (SNR). However, when working with samples whose amount and/or concentration are limited, sensitivity becomes an issue and therefore measurements may require a significant accumulation time, up to 12 h or more. As the detection scheme of practically all pulse EPR sequences is based on the integration of a spin echo - either primary, stimulated or refocused - a considerable increase in SNR can be obtained by replacing the single echo detection scheme by a train of echoes. All these echoes, generated by Carr-Purcell type sequences, are integrated and summed together to improve the SNR. This scheme is commonly used in NMR and here we demonstrate its applicability to a number of frequently used pulse EPR experiments: Echo-Detected EPR, Davies and Mims ENDOR (Electron-Nuclear Double Resonance), DEER (Electron-Electron Double Resonance|) and EDNMR (Electron-Electron Double Resonance (ELDOR)-Detected NMR), which were combined with a Carr-Purcell-Meiboom-Gill (CPMG) type detection scheme at W-band. By collecting the transient signal and integrating a number of refocused echoes, this detection scheme yielded a 1.6-5 folds SNR improvement, depending on the paramagnetic center and the pulse sequence applied. This improvement is achieved while keeping the experimental time constant and it does not introduce signal distortion.

  10. Rotational state detection of electrically trapped polyatomic molecules

    CERN Document Server

    Glöckner, Rosa; Rempe, Gerhard; Zeppenfeld, Martin

    2014-01-01

    Detecting the internal state of polar molecules is a substantial challenge when standard techniques such as resonance-enhanced multi photon ionization (REMPI) or laser-induced fluorescense (LIF) do not work. As this is the case for most polyatomic molecule species, we here investigate an alternative based on state selective removal of molecules from an electrically trapped ensemble. Specifically, we deplete molecules by driving rotational and/or vibrational transitions to untrapped states. Fully resolving the rotational state with this method can be a considerable challenge as the frequency differences between various transitions is easily substantially less than the Stark broadening in an electric trap. However, making use of a unique trap design providing homogeneous fields in a large fraction of the trap volume, we successfully discriminate all rotational quantum numbers, including the rotational M-substate.

  11. Primary pathways of intracellular Ca(2+) mobilization by nanosecond pulsed electric field.

    Science.gov (United States)

    Semenov, Iurii; Xiao, Shu; Pakhomov, Andrei G

    2013-03-01

    Permeabilization of cell membranous structures by nanosecond pulsed electric field (nsPEF) triggers transient rise of cytosolic Ca(2+) concentration ([Ca(2+)](i)), which determines multifarious downstream effects. By using fast ratiometric Ca(2+) imaging with Fura-2, we quantified the external Ca(2+) uptake, compared it with Ca(2+) release from the endoplasmic reticulum (ER), and analyzed the interplay of these processes. We utilized CHO cells which lack voltage-gated Ca(2+) channels, so that the nsPEF-induced [Ca(2+)](i) changes could be attributed primarily to electroporation. We found that a single 60-ns pulse caused fast [Ca(2+)](i) increase by Ca(2+) influx from the outside and Ca(2+) efflux from the ER, with the E-field thresholds of about 9 and 19kV/cm, respectively. Above these thresholds, the amplitude of [Ca(2+)](i) response increased linearly by 8-10nM per 1kV/cm until a critical level between 200 and 300nM of [Ca(2+)](i) was reached. If the critical level was reached, the nsPEF-induced Ca(2+) signal was amplified up to 3000nM by engaging the physiological mechanism of Ca(2+)-induced Ca(2+)-release (CICR). The amplification was prevented by depleting Ca(2+) from the ER store with 100nM thapsigargin, as well as by blocking the ER inositol-1,4,5-trisphosphate receptors (IP(3)R) with 50μM of 2-aminoethoxydiphenyl borate (2-APB). Mobilization of [Ca(2+)](i) by nsPEF mimicked native Ca(2+) signaling, but without preceding activation of plasma membrane receptors or channels. NsPEF stimulation may serve as a unique method to mobilize [Ca(2+)](i) and activate downstream cascades while bypassing the plasma membrane receptors.

  12. Fluence dependent electrical conductivity in aluminium thin films grown by infrared pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rebollar, Esther, E-mail: e.rebollar@csic.es [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 19, 28006 Madrid (Spain); Martínez-Tong, Daniel E. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Sanz, Mikel; Oujja, Mohamed; Marco, José F. [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 19, 28006 Madrid (Spain); Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Castillejo, Marta [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 19, 28006 Madrid (Spain)

    2016-11-30

    Highlights: • IR pulsed laser ablation of aluminium gives rise to smooth layers of several tens of nanometers. • Irradiation at fluences around 2.7 J/cm{sup 2} and above 7 J/cm{sup 2} resulted in deposition of amorphous aluminium oxide films and metallic aluminium films respectively. • Highly ionized species are more abundant in the ablation plumes generated at higher fluences. • It is possible to control by PLD the metal or dielectric character of the films. - Abstract: We studied the effect of laser fluence on the morphology, composition, structure and electric conductivity of deposits generated by pulsed laser ablation of a metallic aluminium target in vacuum using a Q-switched Nd:YAG laser (1064 nm, 15 ns). Upon irradiation for one hour at a repetition rate of 10 Hz, a smooth layer of several tens of nanometres, as revealed by atomic force microscopy (AFM) was deposited on glass. Surface chemical composition was determined by X-ray photoelectron spectroscopy, and to study the conductivity of deposits both I–V curves and conductive-AFM measurements were performed. Irradiation at fluences around 2.7 J/cm{sup 2} resulted in deposition of amorphous aluminium oxide films. Differently, at higher fluences above 7 J/cm{sup 2}, the films are constituted by metallic aluminium. Optical emission spectroscopy revealed that highly ionized species are more abundant in the ablation plumes generated at higher fluences. The results demonstrate the possibility to control by PLD the metal or dielectric character of the films.

  13. Surface Crack Detection for Carbon Fiber Reinforced Plastic Materials Using Pulsed Eddy Current Based on Rectangular Differential Probe

    OpenAIRE

    Jialong Wu; Deqiang Zhou; Jun Wang

    2014-01-01

    Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed ed...

  14. 46 CFR 108.407 - Detectors for electric fire detection system.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Detectors for electric fire detection system. 108.407... DRILLING UNITS DESIGN AND EQUIPMENT Fire Extinguishing Systems § 108.407 Detectors for electric fire detection system. (a) Each detector in an electric fire detection system must be located where— (1)...

  15. Pulse saturation recovery, pulse ELDOR, and free induction decay electron paramagnetic resonance detection using time-locked subsampling

    Science.gov (United States)

    Froncisz, W.; Camenisch, Theodore G.; Ratke, Joseph J.; Hyde, James S.

    2001-03-01

    Time locked subsampling (TLSS) in electron paramagnetic resonance (EPR) involves the steps of (i) translation of the signal from a microwave carrier to an intermediate frequency (IF) carrier where the (IF) offset between the signal oscillator and local oscillator frequencies is synthesized, (ii) sampling the IF carrier four times in an odd number of cycles, say 4 in 3, where the analog-to-digital (A/D) converter is driven by a frequency synthesizer that has the same clock input as the IF synthesizer, (iii) signal averaging as required for adequate signal to noise, (iv) separating the even and odd digitized words into two separate signal channels, which correspond to signals in phase and in quadrature with respect to the IF carrier, i.e., I and Q, and (v) detecting the envelope of I and also of Q by changing the signs of alternate words in each of the two channels. TLSS detection has been demonstrated in three forms of pulse EPR spectroscopy at X band: saturation recovery, pulse electron-electron double resonance, and free induction decay. The IF was 187.5 MHz, the A/D converter frequency was 250 MHz, the overall bandwidth was 125 MHz, and the bandwidths for the separate I and Q channels were each 62.5 MHz. Experiments were conducted on nitroxide radical spin labels. The work was directed towards development of methodology to monitor bimolecular collisions of oxygen with spin labels in a context of site-directed spin labeling.

  16. Homogenization optics to improve detectability of a fluorescence response to a single laser pulse: Detection of feces on apples

    Science.gov (United States)

    Fecal contamination of produce is a known food safety risk. Measuring fluorescence responses to UV excitation is an established method for detecting such contamination. One measurement system utilizes a pulsed UV laser to induce a fluorescence response from fecal material and a gated intensified cam...

  17. Detection of pulsed gamma-ays above 25 GeV from the Crab pulsar

    CERN Document Server

    Aliu, E

    2008-01-01

    One fundamental unanswered question about pulsars concerns the mechanism of their pulsed electromagnetic radiation. Measuring the high end region of a pulsar's spectrum would shed light on this question, but has challenged ground- based experiments for three decades. By developing a new type of electronic trigger, we could lower the threshold of the MAGIC Cherenkov telescope to 25 GeV, a major breakthrough for this kind of instrument. We detected pulsed gamma-ays from the Crab above 25 GeV, revealing a relatively high energy cut-off in the phase-averaged spectrum. This indicates that emission happens far out in the magnetosphere. Also, the main-pulse and secondary pulse have similar amplitudes at 25 GeV. These results exclude the polar cap model and challenge the slot gap emission model for Crab.

  18. Analysis of shot noise in the detection of ultrashort optical pulse trains

    CERN Document Server

    Quinlan, Franklyn; Jiang, Haifeng; Diddams, Scott A

    2013-01-01

    We present a frequency domain model of shot noise in the photodetection of ultrashort optical pulse trains using a time-varying analysis. Shot noise-limited photocurrent power spectral densities, signal-to-noise expressions, and shot noise spectral correlations are derived that explicitly include the finite response of the photodetector. It is shown that the strength of the spectral correlations in the shot noise depends on the optical pulse width, and that these correlations can create orders-of-magnitude imbalance between the shot noise-limited amplitude and phase noise of photonically generated microwave carriers. It is also shown that only by accounting for spectral correlations can shot noise be equated with the fundamental quantum limit in the detection of optical pulse-to-pulse timing jitter.

  19. Detection of coincident radiations in a single transducer by pulse shape analysis

    Science.gov (United States)

    Warburton, William K [Menlo Park, CA

    2008-03-11

    Pulse shape analysis determines if two radiations are in coincidence. A transducer is provided that, when it absorbs the first radiation produces an output pulse that is characterized by a shorter time constant and whose area is nominally proportional to the energy of the absorbed first radiation and, when it absorbs the second radiation produces an output pulse that is characterized by a longer time constant and whose area is nominally proportional to the energy of the absorbed second radiation. When radiation is absorbed, the output pulse is detected and two integrals are formed, the first over a time period representative of the first time constant and the second over a time period representative of the second time constant. The values of the two integrals are examined to determine whether the first radiation, the second radiation, or both were absorbed in the transducer, the latter condition defining a coincident event.

  20. Electric Field Stress Simulation of Plasma Membrane Under Steep Pulsed Electric Field%陡脉冲电场作用下细胞电场力的仿真计算

    Institute of Scientific and Technical Information of China (English)

    姚陈果; 罗霄; 李成祥

    2009-01-01

    The basic characteristic of electric field is that the substance in the field is in operation by the stress.Under external electric fields,there is strong distribution of electric fields on the inside and outside surfaces of cell membrane.In virtue of the difference of the permittivity among membrane,cytoplasm and extracellular medium,there must he electric field stress on the surface of the membrane.The goal of the study is to research the irreversible electrical breakdown (IRE) mechanism of the malignant tumor cells under steep pulsed electric field (SPEF) from the views of mechanics.Electric field stress of plasma membrane under steep pulsed electric field is calculated and simulated both on malignant tumor cells and on the normal cells.The calculation results show that,in addition to a compressive stress normal to the membrane plane,transverse traction stresses are generated in the lateral plane of the membrane.The lateral stress will reduce the membrane tension significantly,leading to electroporation and rupture.At the same electric field strength,the transverse traction stress on malignant cell membrane is greatly larger than the one on normal cell membrane.Therefore,compared with the normal cells,the malignant tumor cells are more sensitive under the steep pulsed electric field.Namely,steep pulsed electric field can selectively destroy the malignant tumor cells,which proved the safety of treating malignant tumors by steep pulsed electric field.

  1. Detection and Characterization of Flaws in Sprayed on Foam Insulation with Pulsed Terahertz Frequency Electromagnetic Waves

    Science.gov (United States)

    Winfree, William P.; Madaras, Eric I.

    2005-01-01

    The detection and repair of flaws such as voids and delaminations in the sprayed on foam insulation of the external tank reduces the probability of foam debris during shuttle ascent. The low density of sprayed on foam insulation along with it other physical properties makes detection of flaws difficult with conventional techniques. An emerging technology that has application for quantitative evaluation of flaws in the foam is pulsed electromagnetic waves at terahertz frequencies. The short wavelengths of these terahertz pulses make them ideal for imaging flaws in the foam. This paper examines the application of terahertz pulses for flaw detection in foam characteristic of the foam insulation of the external tank. Of particular interest is the detection of voids and delaminations, encapsulated in the foam or at the interface between the foam and a metal backing. The technique is shown to be capable of imaging small voids and delaminations through as much as 20 cm of foam. Methods for reducing the temporal responses of the terahertz pulses to improve flaw detection and yield quantitative characterizations of the size and location of the flaws are discussed.

  2. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility

    Energy Technology Data Exchange (ETDEWEB)

    Grills, David C., E-mail: dcgrills@bnl.gov; Farrington, Jaime A.; Layne, Bobby H.; Preses, Jack M.; Wishart, James F. [Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000 (United States); Bernstein, Herbert J. [Department of Mathematics and Computer Science, Dowling College, 1300 William Floyd Parkway, Shirley, New York 11967 (United States)

    2015-04-15

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330 to 1051 cm{sup −1}. The response time of the TRIR detection setup is ∼40 ns, with a typical sensitivity of ∼100 μOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. This new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.

  3. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility.

    Science.gov (United States)

    Grills, David C; Farrington, Jaime A; Layne, Bobby H; Preses, Jack M; Bernstein, Herbert J; Wishart, James F

    2015-04-01

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330 to 1051 cm(-1). The response time of the TRIR detection setup is ∼40 ns, with a typical sensitivity of ∼100 μOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. This new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.

  4. Internal structure control of the TiO2 nanotubes and polysiloxane nanocomposites by nanosecond pulsed electric field

    Directory of Open Access Journals (Sweden)

    Ji-Won Lee

    2014-06-01

    Full Text Available A facile technique has been introduced for incorporating TiO2 nanotubes (TNTs in amorphous polysiloxane-based nanocomposite films and for linear and dense assembling of these TNTs (LATNTs under application of nanosecond pulse electric field. The use of a nanosecond electrical pulse enables the application of high electric power without causing dielectric breakdown, which occurs when DC/AC electric field is used, and the formation of LATNTs which anchor the resulting composite film planes. The properties of the nanocomposites were investigated using X-ray micro CT scanning, digital micrographs, UV–vis spectroscopy and electrical resistivity measurements. More than 5.5-fold UV–vis transmittance improvement was obtained by the polymer composite containing LATNTs (TNT 5.0 wt%. Such a composite exhibited a decreased electric resistivity of 3.08 × 107 Ω m compared to the case for randomly distributed TNTs (3.25 × 108 Ω m.

  5. EARLY DETECTION OF CRITICAL CONGENITAL HEART DISEASE IN NEW BORNS USING PULSE OXIMETRY SCREENING

    Directory of Open Access Journals (Sweden)

    ShahForum,Chatterjee Rajib, PatelPrashant C, Kunkulol Rahul R

    2015-01-01

    Full Text Available Background: Congenital heart diseases which are dependent on the ductusarteriosus to maintain adequate oxygenation or systemic blood flow are termed as a critical congenital heart disease (CCHD. Delay in the diagnosis of CCHD is the major cause leading to morbidity and mortality in newborn infants. Clinical evaluation is likely to miss the diagnosis in first few hours of hospital stay after birth due to absence of signs and symptoms of CCHD. In the absence of clinical findings during early neonatal period, the best parameter that can be assessed is the detection of hypoxemia by pulse oximetry screening. Objectives: To record the value of Pulse Oximetry within 24 hours of birth and evaluate Pulse Oximetry as screening tool for early diagnosis of CCHD. &Methods: Longitudinal descriptive study was conducted on total 700 intramural neonates, satisfying the inclusion and exclusion criteria, who were evaluated within 24 hours of birth with currently available pulse oximeter, after the Institutional Ethical Committee approval. The study was conducted over a period of 4 months. Part-A: Neonatal Case Record, Part-B: Pulse Oximetry Screening Record, Part-C: Clinical Examination Record, Part-D: Echocardiography Record. Results and Conclusion: Total 700 neonates were screened by pulse oximeter with consecutive sampling method. 4 (0.57% subjects were detected to have positive screen and the diagnosis was confirmed by echocardiography. Study revealed that Pulse Oximetry Screening can be an important primary screening tool in routine neonatal care for early detection of Critical Congenital Heart Diseases particularly in rural setup

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

    Science.gov (United States)

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

    2016-08-22

    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.

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

    Science.gov (United States)

    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.

  8. Pulsed electric field treatment enhanced stilbene content in Graciano, Tempranillo and Grenache grape varieties.

    Science.gov (United States)

    López-Alfaro, Isabel; González-Arenzana, Lucía; López, Noelia; Santamaría, Pilar; López, Rosa; Garde-Cerdán, Teresa

    2013-12-15

    The purpose of this paper was to study the effect of pulsed electric fields (PEF) on the stilbene content of three grape varieties. For this purpose, four different PEF treatments were applied using a continuous system over three varieties, Graciano, Tempranillo and Grenache, destemmed and crushed. In addition, the influence of PEF on their physicochemical composition was studied. PEF treatments did not affect the pH or total acidity of Graciano, however, musts from Tempranillo and Grenache had higher pH values and lower total acidity. In the three varieties, all treatments resulted in an increase of potassium content, deeper colour intensity and total polyphenol index and lower tonality, more pronounced in the treatments with higher time and energy. The stilbene content of the must significantly increased with respect to the control. This increase depended on the variety and the treatment applied. Tempranillo increased up 200% the total stilbene concentration, Grenache 60% and Graciano 50%. For the three varieties, the treatment with the highest time and energy was the most effective on the total stilbene extraction. These results indicate that PEF could be a suitable technology for obtaining musts with deeper colour and higher phenolic content, including resveratrol and piceid.

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

    Directory of Open Access Journals (Sweden)

    Ou Yun

    2016-08-01

    Full Text Available 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.

  10. Nanosecond pulsed electric field induced cytoskeleton, nuclear membrane and telomere damage adversely impact cell survival.

    Science.gov (United States)

    Stacey, M; Fox, P; Buescher, S; Kolb, J

    2011-10-01

    We investigated the effects of nanosecond pulsed electric fields (nsPEF) on three human cell lines and demonstrated cell shrinkage, breakdown of the cytoskeleton, nuclear membrane and chromosomal telomere damage. There was a differential response between cell types coinciding with cell survival. Jurkat cells showed cytoskeleton, nuclear membrane and telomere damage that severely impacted cell survival compared to two adherent cell lines. Interestingly, disruption of the actin cytoskeleton in adherent cells prior to nsPEF exposure significantly reduced cell survival. We conclude that nsPEF applications are able to induce damage to the cytoskeleton and nuclear membrane. Telomere sequences, regions that tether and stabilize DNA to the nuclear membrane, are severely compromised as measured by a pan-telomere probe. Internal pore formation following nsPEF applications has been described as a factor in induced cell death. Here we suggest that nsPEF induced physical changes to the cell in addition to pore formation need to be considered as an alternative method of cell death. We suggest nsPEF electrochemical induced depolymerization of actin filaments may account for cytoskeleton and nuclear membrane anomalies leading to sensitization.

  11. The Effects of Theine Content of Pu’er Tea in Hige Pulsed Electric Field

    Directory of Open Access Journals (Sweden)

    Zhao Yan

    2014-10-01

    Full Text Available This essay is based on the experiment of comparing the theine content of sample Yunnan Mengku large-leaf-variety Pu’er tea before and after the treatment of Hige Pulsed Electric Field (HPEF. During this experiment, the differences of content of theine are measured based on different processing techniques of tea (fermented and not fermented, different producing years and different HPEF. The results of the experiments are as follows. First, the difference of the content of theine is notable between fermented and not fermented tea produced in the same year and the theine content of non-fermented tea is larger than that in fermented tea. Second, the content of theine is decreasing with the increase of the length of storage. Third, the content of theine is reduced drastically in samples treated by different conditions of HPEF. The decrease of the content of theine and the major index of quality of Pu’er tea in samples treated by HPEF is consistent with that of natural-aging Pu’er tea. The results of this experiment provide theoretical foundation to further research of aging tea by HPEF.

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

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2016-06-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2016-06-22

    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 (13)C 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.

  14. The influence of pulsed electric field on hematological parameters in rat.

    Science.gov (United States)

    Coskun, Ozlem; Comlekci, Selcuk

    2013-10-01

    The aim of the present study is to investigate whether or not pulsed electric field (PEF) affects some hematological parameters in rats. Sixteen healthy male Wistar rats weighting 150-200 g were used and were randomly divided into two groups. Exposure group (n = 8) was exposed to a PEF (10 kV m⁻¹ for 1 h d⁻¹) for 10 consecutive days. The control group rats (n = 8) were not exposed to PEF. The following hematological parameters were measured in both the groups: white blood cells (WBCs), red blood cells (RBCs), hemoglobin (Hb), hematocrit (Ht) and platelets (PLTs). Some of the hematological parameters under investigation were similar in both the groups. Exposure group, exposed for 1 h d⁻¹ during 10 consecutive days, induced a significant increase in the rates of WBC (p < 0.05), RBC (p < 0.05), Hb (p < 0.05), Ht (p < 0.05) and PLTs (p < 0.05) in blood when compared with control. These results suggest that PEFs affect the hematological parameters in rat. Results of the parameters are statistically significant.

  15. Release of Mannoproteins during Saccharomyces cerevisiae Autolysis Induced by Pulsed Electric Field.

    Science.gov (United States)

    Martínez, Juan M; Cebrián, Guillermo; Álvarez, Ignacio; Raso, Javier

    2016-01-01

    The potential of the application of pulsed electric fields (PEF) to induce accelerate autolysis of a commercial strain of Saccharomyces cerevisiae for winemaking use was evaluated. The influence of PEF treatments of different intensity (5-25 kV/cm for 30-240 μs) on cell viability, cytoplasmic membrane permeabilization and release of mannoproteins and compounds absorbing at 260 and 280 nm has been investigated. After 8 days of incubation at 25°C the Abs600 of the suspension containing the control cells was kept constant while the Abs600 of the suspension containing the cells treated by PEF decreased. The measurement of the absorbance at 260 and 280 nm revealed no release of UV absorbing material from untreated cells after 8 days of incubation but the amount of UV absorbing material released drastically increased in the samples that contained cells treated by PEF after the same storage period. After 18 days of storage the amount of mannoproteins released from the untreated cell was negligible. Conversely, mannoprotein concentration increased linearly for the samples containing cells of S. cerevisiae treated by PEF. After 18 days of incubation the concentration of mannoproteins in the supernatant increased 4.2 times for the samples containing cells treated by PEF at 15 and 25 kV/cm for 45 and 150 μs. Results obtained in this study indicates that PEF could be used in winemaking to accelerate the sur lie aging or to obtain mannoproteins from yeast cultures.

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

    Science.gov (United States)

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

    2015-03-06

    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.

  17. Release of Mannoproteins during Saccharomyces cerevisiae Autolysis Induced by Pulsed Electric Field

    Science.gov (United States)

    Martínez, Juan M.; Cebrián, Guillermo; Álvarez, Ignacio; Raso, Javier

    2016-01-01

    The potential of the application of pulsed electric fields (PEF) to induce accelerate autolysis of a commercial strain of Saccharomyces cerevisiae for winemaking use was evaluated. The influence of PEF treatments of different intensity (5–25 kV/cm for 30–240 μs) on cell viability, cytoplasmic membrane permeabilization and release of mannoproteins and compounds absorbing at 260 and 280 nm has been investigated. After 8 days of incubation at 25°C the Abs600 of the suspension containing the control cells was kept constant while the Abs600 of the suspension containing the cells treated by PEF decreased. The measurement of the absorbance at 260 and 280 nm revealed no release of UV absorbing material from untreated cells after 8 days of incubation but the amount of UV absorbing material released drastically increased in the samples that contained cells treated by PEF after the same storage period. After 18 days of storage the amount of mannoproteins released from the untreated cell was negligible. Conversely, mannoprotein concentration increased linearly for the samples containing cells of S. cerevisiae treated by PEF. After 18 days of incubation the concentration of mannoproteins in the supernatant increased 4.2 times for the samples containing cells treated by PEF at 15 and 25 kV/cm for 45 and 150 μs. Results obtained in this study indicates that PEF could be used in winemaking to accelerate the sur lie aging or to obtain mannoproteins from yeast cultures. PMID:27672386

  18. Electrical properties of Si-doped GaN prepared using pulsed sputtering

    Science.gov (United States)

    Arakawa, Yasuaki; Ueno, Kohei; Imabeppu, Hideyuki; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2017-01-01

    In this study, we investigated the basic electrical properties of Si-doped wurtzite GaN films prepared using a low-temperature pulsed sputtering deposition (PSD) process. We found that the electron concentration can be controlled in the range between 1.5 × 1016 and 2.0 × 1020 cm-3. For lightly Si-doped GaN ([Si] = 2.1 × 1016 cm-3), the room temperature (RT) electron mobility was as high as 1008 cm2 V-1 s-1, which was dominantly limited by polar optical phonon scattering. Moreover, we found that heavily Si-doped GaN prepared using PSD exhibited an RT mobility as high as 110 cm2 V-1 s-1 at an electron concentration of 2 × 1020 cm-3, which indicated that the resistivity of this film was almost as small as those of typical transparent conductive oxides such as indium tin oxide. At lower temperatures, the electron mobility increased to 1920 cm2 V-1 s-1 at 136 K, and the temperature dependence was well explained by conventional scattering models. These results indicate that Si-doped GaN prepared using PSD is promising not only for the fabrication of GaN-based power devices but also for use as epitaxial transparent electrode materials for nitride based optical devices.

  19. Wurtzite-type ZnS nanoparticles by pulsed electric discharge

    Science.gov (United States)

    Omurzak, Emil; Mashimo, Tsutomu; Sulaimankulova, Saadat; Takebe, Shintaro; Chen, Liliang; Abdullaeva, Zhypargul; Iwamoto, Chihiro; Oishi, Yudai; Ihara, Hirotaka; Okudera, Hiroki; Yoshiasa, Akira

    2011-09-01

    The synthesis of wurtzite-type ZnS nanoparticles by an electric discharge submerged in molten sulfur is reported. Using a pulsed plasma between two zinc electrodes of diameter 5 mm in molten sulfur, we have synthesized high-temperature phase (wurtzite-type) ZnS nanocrystals with an average size of about 20 nm. The refined lattice parameters of the synthesized wurtzite-type ZnS nanoparticles were found to be larger than those of the reported ZnS (JCPDS card no 36-1450). Synthesis of ZnMgS (solid solution of ZnS and MgS) was achieved by using ZnMg alloys as both cathode and anode electrodes. UV-visible absorption spectroscopy analysis showed that the absorption peak of the as-prepared ZnS sample (319 nm) displays a blue-shift compared to the bulk ZnS (335 nm). Photoluminescence spectra of the samples revealed peaks at 340, 397, 423, 455 and 471 nm, which were related to excitonic emission and stoichiometric defects.

  20. Fluence dependent electrical conductivity in aluminium thin films grown by infrared pulsed laser deposition

    Science.gov (United States)

    Rebollar, Esther; Martínez-Tong, Daniel E.; Sanz, Mikel; Oujja, Mohamed; Marco, José F.; Ezquerra, Tiberio A.; Castillejo, Marta

    2016-11-01

    We studied the effect of laser fluence on the morphology, composition, structure and electric conductivity of deposits generated by pulsed laser ablation of a metallic aluminium target in vacuum using a Q-switched Nd:YAG laser (1064 nm, 15 ns). Upon irradiation for one hour at a repetition rate of 10 Hz, a smooth layer of several tens of nanometres, as revealed by atomic force microscopy (AFM) was deposited on glass. Surface chemical composition was determined by X-ray photoelectron spectroscopy, and to study the conductivity of deposits both I-V curves and conductive-AFM measurements were performed. Irradiation at fluences around 2.7 J/cm2 resulted in deposition of amorphous aluminium oxide films. Differently, at higher fluences above 7 J/cm2, the films are constituted by metallic aluminium. Optical emission spectroscopy revealed that highly ionized species are more abundant in the ablation plumes generated at higher fluences. The results demonstrate the possibility to control by PLD the metal or dielectric character of the films.