High-Speed, high-power, switching transistor

NASA Technical Reports Server (NTRS)

Carnahan, D.; Ohu, C. K.; Hower, P. L.

1979-01-01

Silicon transistor rate for 200 angstroms at 400 to 600 volts combines switching speed of transistors with ruggedness, power capacity of thyristor. Transistor introduces unique combination of increased power-handling capability, unusally low saturation and switching losses, and submicrosecond switching speeds. Potential applications include high power switching regulators, linear amplifiers, chopper controls for high frequency electrical vehicle drives, VLF transmitters, RF induction heaters, kitchen cooking ranges, and electronic scalpels for medical surgery.

Evaluation of electrical conductivity of Cu and Al through sub microsecond underwater electrical wire explosion

NASA Astrophysics Data System (ADS)

Sheftman, D.; Shafer, D.; Efimov, S.; Krasik, Ya. E.

2012-03-01

Sub-microsecond timescale underwater electrical wire explosions using Cu and Al materials have been conducted. Current and voltage waveforms and time-resolved streak images of the discharge channel, coupled to 1D magneto-hydrodynamic simulations, have been used to determine the electrical conductivity of the metals for the range of conditions between hot liquid metal and strongly coupled non-ideal plasma, in the temperature range of 10-60 KK. The results of these studies showed that the conductivity values obtained are typically lower than those corresponding to modern theoretical electrical conductivity models and provide a transition between the conductivity values obtained in microsecond time scale explosions and those obtained in nanosecond time scale wire explosions. In addition, the measured wire expansion shows good agreement with equation of state tables.

Thermoacoustic imaging of fresh prostates up to 6-cm diameter

NASA Astrophysics Data System (ADS)

Patch, S. K.; Hanson, E.; Thomas, M.; Kelly, H.; Jacobsohn, K.; See, W. A.

2013-03-01

Thermoacoustic (TA) imaging provides a novel contrast mechanism that may enable visualization of cancerous lesions which are not robustly detected by current imaging modalities. Prostate cancer (PCa) is the most notorious example. Imaging entire prostate glands requires 6 cm depth penetration. We therefore excite TA signal using submicrosecond VHF pulses (100 MHz). We will present reconstructions of fresh prostates imaged in a well-controlled benchtop TA imaging system. Chilled glycine solution is used as acoustic couplant. The urethra is routinely visualized as signal dropout; surgical staples formed from 100-micron wide wire bent to 3 mm length generate strong positive signal.

Flash X-Ray Apparatus With Spectrum Control Functions For Medical Use And Fuji Computed Radiography

NASA Astrophysics Data System (ADS)

Isobe, H.; Sato, E.; Hayasi, Y.; Suzuki, M.; Arima, H.; Hoshino, F.

1985-02-01

Flash radiographic bio-medical studies at sub-microsecond intervals were performed by using both a new type of flash X-ray(FX) apparatus with spectrum control functions and Fuji Computed Radiography(FCR). This single flasher tends to have a comparatively long exposure time and the electric pulse width of the FX wave form is about 0.3,usec. The maximum FX dose is about 50mR at 1m per pulse, and the effective focal spot varies according to condenser charging voltage, A-C distance, etc., ranging from 1.0 to 3.0mm in diameter, but in the low dose rate region it can be reduced to less than 1.0mm in diameter. The FX dose is determined by the condenser charging voltage and the A-C distance, while the FX spectrum is determined by the average voltage of the FX tube and filters. Various clear FX images were obtained by controlling the spectrum and dose. FCR is a new storage medium for medical radiography developed by the Fuji Photo Film Co., Ltd. and this apparatus has various image forming functions: low dose radiography, film density control, image contrast control, subtraction management and others. We have used this new apparatus in conjunction with our FX radiography and have obtained some new and interesting biomedical radiograms: the edge enhancement image, the instantaneous enlarged image, and the single exposure energy subtraction image using the FX spectrum distribution.

Generator and Setup for Emulating Exposures of Biological Samples to Lightning Strokes.

PubMed

Rebersek, Matej; Marjanovic, Igor; Begus, Samo; Pillet, Flavien; Rols, Marie-Pierre; Miklavcic, Damijan; Kotnik, Tadej

2015-10-01

We aimed to develop a system for controlled exposure of biological samples to conditions they experience when lightning strikes their habitats. We based the generator on a capacitor charged via a bridge rectifier and a dc-dc converter, and discharged via a relay, delivering arcs similar to natural lightning strokes in electric current waveform and similarly accompanied by acoustic shock waves. We coupled the generator to our exposure chamber described previously, measured electrical and acoustic properties of arc discharges delivered, and assessed their ability to inactivate bacterial spores. Submicrosecond discharges descended vertically from the conical emitting electrode across the air gap, entering the sample centrally and dissipating radially toward the ring-shaped receiving electrode. In contrast, longer discharges tended to short-circuit the electrodes. Recording at 341 000 FPS with Vision Research Phantom v2010 camera revealed that initial arc descent was still vertical, but became accompanied by arcs leaning increasingly sideways; after 8-12 μs, as the first of these arcs formed direct contact with the receiving electrode, it evolved into a channel of plasmified air and short-circuited the electrodes. We eliminated this artefact by incorporating an insulating cylinder concentrically between the electrodes, precluding short-circuiting between them. While bacterial spores are highly resistant to electric pulses delivered through direct contact, we showed that with arc discharges accompanied by an acoustic shock wave, spore inactivation is readily obtained. The presented system allows scientific investigation of effects of arc discharges on biological samples. This system will allow realistic experimental studies of lightning-triggered horizontal gene transfer and assessment of its role in evolution.

Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis Relevant to Artificial Photosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujita, Etsuko; Grills, David C.; Polyansky, Dmitry E.

Taking inspiration from natural photosystems, the goal of artificial photosynthesis is to harness solar energy to convert abundant materials, such as CO 2 and H 2O, into solar fuels. Catalysts are required to ensure that the necessary redox half-reactions proceed in the most energy-efficient manner. It is thus critical to gain a detailed mechanistic understanding of these catalytic reactions in order to develop new and improved catalysts. Many of the key catalytic intermediates are short-lived transient species, requiring time-resolved spectroscopic techniques for their observation. The two main methods for rapidly generating such species on the sub-microsecond timescale are laser flashmore » photolysis and pulse radiolysis. These methods complement one another, and both can provide important spectroscopic and kinetic information. However, pulse radiolysis proves to be superior in systems with significant spectroscopic overlap between photosensitizer and other species present during the reaction. In this paper, we review the pulse radiolysis technique and how it has been applied to mechanistic investigations of half-reactions relevant to artificial photosynthesis.« less

Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis Relevant to Artificial Photosynthesis

DOE PAGES

Fujita, Etsuko; Grills, David C.; Polyansky, Dmitry E.

2017-09-12

Taking inspiration from natural photosystems, the goal of artificial photosynthesis is to harness solar energy to convert abundant materials, such as CO 2 and H 2O, into solar fuels. Catalysts are required to ensure that the necessary redox half-reactions proceed in the most energy-efficient manner. It is thus critical to gain a detailed mechanistic understanding of these catalytic reactions in order to develop new and improved catalysts. Many of the key catalytic intermediates are short-lived transient species, requiring time-resolved spectroscopic techniques for their observation. The two main methods for rapidly generating such species on the sub-microsecond timescale are laser flashmore » photolysis and pulse radiolysis. These methods complement one another, and both can provide important spectroscopic and kinetic information. However, pulse radiolysis proves to be superior in systems with significant spectroscopic overlap between photosensitizer and other species present during the reaction. In this paper, we review the pulse radiolysis technique and how it has been applied to mechanistic investigations of half-reactions relevant to artificial photosynthesis.« less

Submicrosecond linear pulse transformer for 800 kV voltage with modular low-inductance primary power supply

NASA Astrophysics Data System (ADS)

Bykov, Yu. A.; Krastelev, E. G.; Popov, G. V.; Sedin, A. A.; Feduschak, V. F.

2016-12-01

A pulsed power source with voltage amplitude up to 800 kV for fast charging (350-400 ns) of the forming line of a high-current nanosecond accelerator is developed. The source includes capacitive energy storage and a linear pulse transformer. The linear transformer consists of a set of 20 inductors with circular ferromagnetic cores surrounded by primary windings inside of which a common stock adder of voltage with film-glycerol insulation is placed. The primary energy storage consists of ten modules, each of which is a low-inductance assembly of two capacitors with a capacitance of 0.35 μF and one gas switch mounted in the same frame. The total energy stored in capacitors is 5.5 kJ at the operating voltage of 40 kV. According to test results, the parameters of the equivalent circuit of the source are the following: shock capacitance = 17.5 nF, inductance = 2 μH, resistance = 3.2 Ω.

Submicrosecond linear pulse transformer for 800 kV voltage with modular low-inductance primary power supply

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bykov, Yu. A.; Krastelev, E. G., E-mail: ekrastelev@yandex.ru; Popov, G. V.

A pulsed power source with voltage amplitude up to 800 kV for fast charging (350–400 ns) of the forming line of a high-current nanosecond accelerator is developed. The source includes capacitive energy storage and a linear pulse transformer. The linear transformer consists of a set of 20 inductors with circular ferromagnetic cores surrounded by primary windings inside of which a common stock adder of voltage with film-glycerol insulation is placed. The primary energy storage consists of ten modules, each of which is a low-inductance assembly of two capacitors with a capacitance of 0.35 μF and one gas switch mounted inmore » the same frame. The total energy stored in capacitors is 5.5 kJ at the operating voltage of 40 kV. According to test results, the parameters of the equivalent circuit of the source are the following: shock capacitance = 17.5 nF, inductance = 2 μH, resistance = 3.2 Ω.« less

Lightning leader models of terrestrial gamma-ray flashes

NASA Astrophysics Data System (ADS)

Dwyer, J. R.; Liu, N.; Ihaddadene, K. M. A.

2017-12-01

Terrestrial gamma-ray flashes (TGFs) are bright sub-millisecond bursts of gamma rays that originate from thunderstorms. Because lightning leaders near the ground have been observed to emit x-rays, presumably due to runaway electron production in the high-field regions near the leader tips, models of TGFs have been developed by several groups that assume a similar production mechanism of runaway electrons from lightning leaders propagating through thunderclouds. However, it remains unclear exactly how and where these runaway electrons are produced, since lightning propagation at thunderstorm altitudes remains poorly understood. In addition, it is not obvious how to connect the observed behavior of the x-ray production from lightning near the ground with the properties of TGFs. For example, it is not clear how to relate the time structure of the x-ray emission near the ground to that of TGFs, since x-rays from stepped leaders near the ground are usually produced in a series of sub-microsecond bursts, but TGFs are usually observed as much longer pulses without clear substructures, at sub-microsecond timescales or otherwise. In this presentation, spacecraft observations of TGFs, ground-based observations of x-rays from lightning and laboratory sparks, and Monte Carlo and PIC simulations of runaway electron and gamma ray production and propagation will be used to constrain the lightning leader models of TGFs.

Multiple Velocity Profile Measurements in Hypersonic Flows using Sequentially-Imaged Fluorescence Tagging

NASA Technical Reports Server (NTRS)

Bathel, Brett F.; Danehy, Paul M.; Inmian, Jennifer A.; Jones, Stephen B.; Ivey, Christopher B.; Goyne, Christopher P.

2010-01-01

Nitric-oxide planar laser-induced fluorescence (NO PLIF) was used to perform velocity measurements in hypersonic flows by generating multiple tagged lines which fluoresce as they convect downstream. For each laser pulse, a single interline, progressive scan intensified CCD camera was used to obtain separate images of the initial undelayed and delayed NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond acquisition of both images, resulting in sub-microsecond temporal resolution as well as sub-mm spatial resolution (0.5-mm x 0.7-mm). Determination of axial velocity was made by application of a cross-correlation analysis of the horizontal shift of individual tagged lines. Quantification of systematic errors, the contribution of gating/exposure duration errors, and influence of collision rate on fluorescence to temporal uncertainty were made. Quantification of the spatial uncertainty depended upon the analysis technique and signal-to-noise of the acquired profiles. This investigation focused on two hypersonic flow experiments: (1) a reaction control system (RCS) jet on an Orion Crew Exploration Vehicle (CEV) wind tunnel model and (2) a 10-degree half-angle wedge containing a 2-mm tall, 4-mm wide cylindrical boundary layer trip. The experiments were performed at the NASA Langley Research Center's 31-inch Mach 10 wind tunnel.

Dynamics of near-surface electric discharges and mechanisms of their interaction with the airflow

NASA Astrophysics Data System (ADS)

Leonov, Sergey B.; Adamovich, Igor V.; Soloviev, Victor R.

2016-12-01

The main focus of the review is on dynamics and kinetics of near-surface discharge plasmas, such as surface dielectric barrier discharges sustained by AC and repetitively pulsed waveforms, pulsed DC discharges, and quasi-DC discharges, generated in quiescent air and in the airflow. A number of technical issues related to plasma flow control applications are discussed in detail, including discharge development via surface ionization waves, charge transport and accumulation on dielectric surface, discharge contraction, different types of flow perturbations generated by surface discharges, and effect of high-speed flow on discharge dynamics. In the first part of the manuscript, plasma morphology and results of electrical and optical emission spectroscopy measurements are discussed. Particular attention is paid to dynamics of surface charge accumulation and dissipation, both in diffuse discharges and during development of ionization instabilities resulting in discharge contraction. Contraction leads to significant increase of both the surface area of charge accumulation and the energy coupled to the plasma. The use of alternating polarity pulse waveforms accelerates contraction of surface dielectric barrier discharges and formation of filamentary plasmas. The second part discusses the interaction of discharge plasmas with quiescent air and the external airflow. Four major types of flow perturbations have been identified: (1) low-speed near-surface jets generated by electrohydrodynamic interaction (ion wind); (2) spanwise and streamwise vortices formed by both electrohydrodynamic and thermal effects; (3) weak shock waves produced by rapid heating in pulsed discharges on sub-microsecond time scale; and (4) near-surface localized stochastic perturbations, on sub-millisecond time, detected only recently. The mechanism of plasma-flow interaction remains not fully understood, especially in filamentary surface dielectric barrier discharges. Localized quasi-DC surface discharges sustained in a high-speed flow are discussed in the third part of the review. Although dynamics of this type of the discharge is highly transient, due to its strong interaction with the flow, the resultant flow structure is stationary, including the oblique shock and the flow separation region downstream of the discharge. The oblique shock is attached to a time-averaged, wedge-shaped, near-wall plasma layer, with the shock angle controlled by the discharge power, which makes possible changing the flow structure and parameters in a controlled way. Finally, unresolved and open-ended issues are discussed in the summary.

Electric-field effects in the twist-bend nematic phase

NASA Astrophysics Data System (ADS)

Meyer, Claire; Dozov, Ivan; Davidson, Patrick; Luckhurst, Geoffrey R.; Dokli, Irena; Knezevic, Anamarija; Lesac, Andreja

2018-02-01

In the recently discovered Twist-Bend Nematic (NTB) phase, the nematic director is spontaneously distorted and twisted along a conical helix with an extremely short pitch, 10 nm. We have investigated the behavior of the NTB phase subject to an electric-field. We show that, due to the periodic NTB structure, the electro-optic effects are not nematic-like but are close analogs to those in the smectic and cholesteric phases. In particular, we have studied the fast (sub-microsecond) flexoelectrically-induced rotation of the optic axis, which is similar to the electroclinic effect in the SmA* phase and the flexoelectric response of short-pitch cholesterics. We discuss the possible applications of the fast NTB electro-optic effects.

Development and experimental study of oil-free capacitor module for plasma focus device

NASA Astrophysics Data System (ADS)

Sharma, Ravindra Kumar; Sharma, Archana

2017-03-01

This development is concerned with the compact capacitor module for a plasma focus device. Oil-free, non-standard geometry capacitors are designed and developed for high current delivery in sub-microseconds time. Metalized dielectric film based pulse capacitor becomes progressively less viable at currents above 10 kA. It is due to reliability and energy scaling difficulties, based on effects such as vaporization, high resistivity, and end connection. Bipolar electrolytic capacitors are also not preferred due to their limited life and comparatively low peak current delivery. Bi-axially oriented polypropylene (BOPP) film with extended aluminum foil is a combination to deliver moderately high power. But, electrically weak points, relative permittivity, and the edge gap margins have made its adoption difficult. A concept has been developed in lab for implementing the above combination in a less complex and costly manner. This paper concerns the development and testing process techniques for quite different hollow cylindrical, oil-free capacitors (4 μ F , 10 kV, 20 nH). Shot life of 1000 has been experimentally performed on the test bed at its rated energy density level. The technological methods and engineering techniques are now available and utilized for manufacturing and testing of BOPP film based oil-free capacitors.

Specific Localization of High-Voltage Discharge in Vicinity of Two Gases

NASA Astrophysics Data System (ADS)

Leonov, Sergey; Shurupov, Michail; Shneider, Michail; Napartovich, Anatoly; Kochetov, Igor

2011-10-01

A subject of paper is the appearance and dynamics of sub-microsecond long filamentary high-voltage discharge generated in atmosphere, and in non-homogeneous gaseous media. Typical discharge parameters are: maximal current 1-3kA, breakdown voltage >100 kV, duration 30-100 ns, gap distance 50-100mm. The effect of discharge specific localization within mixing layer of two gases is particularly discussed. The second discussed idea is the filamentary discharge movement within a region with concentration gradient of different components. For the short-pulse discharge the physical mechanism appears as the following. The first stage of the spark breakdown is the multiple streamers propagation from the high-voltage electrode toward the grounded one. In case of high-power electrical source those streamers occupy a huge volume of the gas, covering all possible paths for the further development. The next phase consists of the real selection of the discharge path among the multiple channels with non-zero conductivity. Experiments and calculations are presented for Air-CO2 and Air-C2H4 pairs. The effects found are supposed to be applied for lightning prediction/protection, and for high-speed mixing acceleration. The work was funded through EOARD-ISTC project #3793p. Some part of this work was supported by RFBR grant #10-08-00952.

Development and experimental study of oil-free capacitor module for plasma focus device.

PubMed

Sharma, Ravindra Kumar; Sharma, Archana

2017-03-01

This development is concerned with the compact capacitor module for a plasma focus device. Oil-free, non-standard geometry capacitors are designed and developed for high current delivery in sub-microseconds time. Metalized dielectric film based pulse capacitor becomes progressively less viable at currents above 10 kA. It is due to reliability and energy scaling difficulties, based on effects such as vaporization, high resistivity, and end connection. Bipolar electrolytic capacitors are also not preferred due to their limited life and comparatively low peak current delivery. Bi-axially oriented polypropylene (BOPP) film with extended aluminum foil is a combination to deliver moderately high power. But, electrically weak points, relative permittivity, and the edge gap margins have made its adoption difficult. A concept has been developed in lab for implementing the above combination in a less complex and costly manner. This paper concerns the development and testing process techniques for quite different hollow cylindrical, oil-free capacitors (4 μF, 10 kV, 20 nH). Shot life of 1000 has been experimentally performed on the test bed at its rated energy density level. The technological methods and engineering techniques are now available and utilized for manufacturing and testing of BOPP film based oil-free capacitors.

A review of natural lightning - Experimental data and modeling

NASA Technical Reports Server (NTRS)

Uman, M. A.; Krider, E. P.

1982-01-01

A critical review is presented of the currents and the electric and magnetic fields characteristic of each of the salient discharge processes which make up cloud-to-ground and intracloud lightning. Emphasis is placed on the more recent work in which measured waveform variation is in the microsecond and submicrosecond range, since it is this time-scale that is of primary importance in lightning/aircraft interactions. The state-of-the-art of the modeling of lightning currents and fields is discussed in detail. A comprehensive bibliography is given of all literature relating to both lightning measurements and models.

A platform for exploding wires in different media

NASA Astrophysics Data System (ADS)

Han, Ruoyu; Wu, Jiawei; Qiu, Aici; Zhou, Haibin; Wang, Yanan; Yan, Jiaqi; Ding, Weidong

2017-10-01

A platform SWE-2 used for single wire explosion experiments has been designed, established, and commissioned. This paper describes the design and initial experiments of SWE-2. In summary, two pulsed current sources based on pulse capacitors and spark gaps are adopted to drive sub-microsecond and microsecond time scale wire explosions in a gaseous/liquid medium, respectively. In the initial experiments, a single copper wire was exploded in air, helium, and argon with a 0.1-0.3 MPa ambient pressure as well as tap water with a 283-323 K temperature, 184-11 000 μ S/cm conductivity, or 0.1-0.9 MPa hydrostatic pressure. In addition, the diagnostic system is introduced in detail. Energy deposition, optical emission, and shock wave characteristics are briefly discussed based on experimental results. The platform was demonstrated to operate successfully with a single wire load. These results provide the potential for further applications of this platform, such as plasma-matter interactions, shock wave effects, and reservoir simulations.

Multiple Velocity Profile Measurements in Hypersonic Flows Using Sequentially-Imaged Fluorescence Tagging

NASA Technical Reports Server (NTRS)

Bathel, Brett F.; Danehy, Paul M.; Inman, Jennifer A.; Jones, Stephen B.; Ivey,Christopher b.; Goyne, Christopher P.

2010-01-01

Nitric-oxide planar laser-induced fluorescence (NO PLIF) was used to perform velocity measurements in hypersonic flows by generating multiple tagged lines which fluoresce as they convect downstream. For each laser pulse, a single interline, progressive scan intensified CCD (charge-coupled device) camera was used to obtain two sequential images of the NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond acquisition of both images, resulting in sub-microsecond temporal resolution as well as sub-mm spatial resolution (0.5-mm horizontal, 0.7-mm vertical). Determination of axial velocity was made by application of a cross-correlation analysis of the horizontal shift of individual tagged lines. A numerical study of measured velocity error due to a uniform and linearly-varying collisional rate distribution was performed. Quantification of systematic errors, the contribution of gating/exposure duration errors, and the influence of collision rate on temporal uncertainty were made. Quantification of the spatial uncertainty depended upon the signal-to-noise ratio of the acquired profiles. This velocity measurement technique has been demonstrated for two hypersonic flow experiments: (1) a reaction control system (RCS) jet on an Orion Crew Exploration Vehicle (CEV) wind tunnel model and (2) a 10-degree half-angle wedge containing a 2-mm tall, 4-mm wide cylindrical boundary layer trip. The experiments were performed at the NASA Langley Research Center's 31-Inch Mach 10 Air Tunnel.

Ultra-Thin Solid-State Nanopores: Fabrication and Applications

NASA Astrophysics Data System (ADS)

Kuan, Aaron Tzeyang

Solid-state nanopores are a nanofluidic platform with unique advantages for single-molecule analysis and filtration applications. However, significant improvements in device performance and scalable fabrication methods are needed to make nanopore devices competitive with existing technologies. This dissertation investigates the potential advantages of ultra-thin nanopores in which the thickness of the membrane is significantly smaller than the nanopore diameter. Novel, scalable fabrication methods were first developed and then utilized to examine device performance for water filtration and single molecule sensing applications. Fabrication of nanometer-thin pores in silicon nitride membranes was achieved using a feedback-controlled ion beam method in which ion sputtering is arrested upon detection of the first few ions that drill through the membrane. Performing fabrication at liquid nitrogen temperatures prevents surface atom rearrangements that have previously complicated similar processes. A novel cross-sectional imaging method was also developed to allow careful examination of the full nanopore geometry. Atomically-thin graphene nanopores were fabricated via an electrical pulse method in which sub-microsecond electrical pulses applied across a graphene membrane in electrolyte solution are used to create a defect in the membrane and controllably enlarge it into a nanopore. This method dramatically increases the accuracy and reliability of graphene nanopore production, allowing consistent production of single nanopores down to subnanometer sizes. In filtration applications in which nanopores are used to selectively restrict the passage of dissolved contaminants, ultra-thin nanopores minimize the flow resistance, increasing throughput and energy-efficiency. The ability of graphene nanopores to separate different ions was characterized via ionic conductance and reversal potential measurements. Graphene nanopores were observed to conduct cations preferentially over anions with selectivity ratios of 100 or higher for pores as large as 20 nm in diameter, suggesting that porous graphene membranes can be used to create highly effective cation exchange membranes for electrodialysis filtration. These surprisingly high selectivities cannot be explained by current models of ionic conduction in graphene nanopores, motivating the development of a new model in which elevated concentrations of mobile cations near the graphene surface generate additional ion selectivity.

Dental hard tissue modification and removal using sealed transverse excited atmospheric-pressure lasers operating at lambda=9.6 and 10.6 um

NASA Astrophysics Data System (ADS)

Fried, Daniel; Ragadio, Jerome N.; Akrivou, Maria; Featherstone, John D.; Murray, Michael W.; Dickenson, Kevin M.

2001-04-01

Pulsed CO2 lasers have been shown to be effective for both removal and modification of dental hard tissue for the treatment of dental caries. In this study, sealed transverse excited atmospheric pressure (TEA) laser systems optimally tuned to the highly absorbed 9.6 micrometers wavelength were investigated for application on dental hard tissue. Conventional TEA lasers produce an initial high energy spike at the beginning of the laser pulse of submicrosecond duration followed by a long tail of about 1 - 4 microsecond(s) . The pulse duration is well matched to the 1 - 2 microsecond(s) thermal relaxation time of the deposited laser energy at 9.6 micrometers and effectively heats the enamel to the temperatures required for surface modification at absorbed fluences of less than 0.5 J/cm2. Thus, the heat deposition in the tooth and the corresponding risk of pulpal necrosis from excessive heat accumulation is minimized. At higher fluences, the high peak power of the laser pulse rapidly initiates a plasma that markedly reduces the ablation rate and efficiency, severely limiting applicability for hard tissue ablation. By lengthening the laser pulse to reduce the energy distributed in the initial high energy spike, the plasma threshold can be raised sufficiently to increase the ablation rate by an order of magnitude. This results in a practical and efficient CO2 laser system for caries ablation and surface modification.

Coherent pulse interrogation system for fiber Bragg grating sensing of strain and pressure in dynamic extremes of materials.

PubMed

Rodriguez, George; Jaime, Marcelo; Balakirev, Fedor; Mielke, Chuck H; Azad, Abul; Marshall, Bruce; La Lone, Brandon M; Henson, Bryan; Smilowitz, Laura

2015-06-01

A 100 MHz fiber Bragg grating (FBG) interrogation system is described and applied to strain and pressure sensing. The approach relies on coherent pulse illumination of the FBG sensor with a broadband short pulse from a femtosecond modelocked erbium fiber laser. After interrogation of the FBG sensor, a long multi-kilometer run of single mode fiber is used for chromatic dispersion to temporally stretch the spectral components of the reflected pulse from the FBG sensor. Dynamic strain or pressure induced spectral shifts in the FBG sensor are detected as a pulsed time domain waveform shift after encoding by the chromatic dispersive line. Signals are recorded using a single 35 GHz photodetector and a 50 G Samples per second, 25 GHz bandwidth, digitizing oscilloscope. Application of this approach to high-speed strain sensing in magnetic materials in pulsed magnetic fields to ~150 T is demonstrated. The FBG wavelength shifts are used to study magnetic field driven magnetostriction effects in LaCoO₃. A sub-microsecond temporal shift in the FBG sensor wavelength attached to the sample under first order phase change appears as a fractional length change (strain: ΔL/L<10^-4) in the material. A second application used FBG sensing of pressure dynamics to nearly 2 GPa in the thermal ignition of the high explosive PBX-9501 is also demonstrated. Both applications demonstrate the use of this FBG interrogation system in dynamical extreme conditions that would otherwise not be possible using traditional FBG interrogation approaches that are deemed too slow to resolve such events.

Lambda Probe Measurements of Laboratory Spheromaks

NASA Astrophysics Data System (ADS)

Jorne, E.; Bellan, P. M.; Hsu, S. C.; Moynihan, C.

2003-10-01

A combined current and magnetic probe (lambda probe) has been constructed and is being tested for the purpose of investigating the behavior of spheromaks formed by the Caltech planar spheromak gun. The probe consists of a 1.5cm diameter, 52 turn Rogowski coil and a single loop magnetic coil, housed in a ceramic shell attached to a 95cm long hollow, steel shaft. A high voltage power supply was used to test the probe's ability to measure pulsed currents with submicrosecond rise times. A calibrated current pulse was provided by a 1μF capacitor discharged by a krytron switch to a low inductance circuit. Magnetic calibration was obtained by using the capacitor bank to power a 16cm diameter Helmholtz coil. Both magnetic and current calibration were in good agreement with estimates based on geometry. An existing steel shaft will be replaced by a ceramic shaft in order to minimize undesired effects on the plasma by a conductor. Once sealed with epoxy, the probe will be ready for insertion into the vacuum chamber and used to measure the magnetic field and parallel current during spheromak formation.

Origin of temperature plateaus in laser-heated diamond anvil cell experiments

NASA Astrophysics Data System (ADS)

Geballe, Zachary M.; Jeanloz, Raymond

2012-06-01

Many high-pressure high-temperature studies using laser-heated diamond cells have documented plateaus in the increase of temperature with increasing laser power or with time. By modeling heat transfer in typical laser-heated diamond anvil cell experiments, we demonstrate that latent heat due to melting or other phase transformation is unlikely to be the source of observed plateaus in any previously published studies, regardless of whether pulsed or continuous lasers were used. Rather, large increases (˜10-fold) in thermal conductivity can explain some of the plateaus, and modest increases in reflectivity (tens of percent) can explain any or all of them. Modeling also shows that the sub-microsecond timescale of heating employed in recent pulsed heating experiments is fast enough compared to heat transport into and through typical insulations, but too slow compared to heat transport into metallic laser absorbers themselves to allow the detection of a large plateau due to latent heat of fusion. Four new designs are suggested for future experiments that could use the simple observation of a latent heat-induced plateau to provide reliable high-pressure melting data.

A high power microwave triggered RF opening switch.

PubMed

Beeson, S; Dickens, J; Neuber, A

2015-03-01

A 4-port S-band waveguide structure was designed and fabricated such that a signal of any amplitude (less than 1 MW) can be switched from a normally closed state, <0.5 dB insertion loss (IL), to an open state >30 dB IL by initiating plasma in a gas cell situated at the junction of this waveguide and one propagating a megawatt level magnetron pulse. The 90/10 switching time is as low as 20 ns with a delay of ∼30 ns between the onset of the high power microwave pulse and the initial drop of the signal. Two ports of this device are for the high power triggering pulse while the other two ports are for the triggered signal in a Moreno-like coupler configuration. In order to maintain high isolation, these two sets of waveguides are rotated 90° from each other with a TE111 resonator/plasma cell located at the intersection. This manuscript describes the design and optimization of this structure using COMSOL 4.4 at the design frequency of 2.85 GHz, comparison of simulated scattering parameters with measured "cold tests" (testing without plasma), and finally the temporal waveforms of this device being used to successfully switch a low power CW signal from 2 W to <5 mW on a sub-microsecond timescale.

Versatile microsecond movie camera

NASA Astrophysics Data System (ADS)

Dreyfus, R. W.

1980-03-01

A laboratory-type movie camera is described which satisfies many requirements in the range 1 microsec to 1 sec. The camera consists of a He-Ne laser and compatible state-of-the-art components; the primary components are an acoustooptic modulator, an electromechanical beam deflector, and a video tape system. The present camera is distinct in its operation in that submicrosecond laser flashes freeze the image motion while still allowing the simplicity of electromechanical image deflection in the millisecond range. The gating and pulse delay circuits of an oscilloscope synchronize the modulator and scanner relative to the subject being photographed. The optical table construction and electronic control enhance the camera's versatility and adaptability. The instant replay video tape recording allows for easy synchronization and immediate viewing of the results. Economy is achieved by using off-the-shelf components, optical table construction, and short assembly time.

Rapid Two-Millisecond Interrogation of Electrochemical, Aptamer-Based Sensor Response Using Intermittent Pulse Amperometry.

PubMed

Santos-Cancel, Mirelis; Lazenby, Robert A; White, Ryan J

2018-06-22

In this manuscript, we employ the technique intermittent pulse amperometry (IPA) to interrogate equilibrium and kinetic target binding to the surface of electrochemical, aptamer-based (E-AB) sensors, achieving as fast as 2 ms time resolution. E-AB sensors comprise an electrode surface modified with a flexible nucleic acid aptamer tethered at the 3'-terminus with a redox-active molecule. The introduction of a target changes the conformation and flexibility of the nucleic acid, which alters the charge transfer rate of the appended redox molecule. Typically, changes in charge transfer rate within this class of sensor are monitored via voltammetric methods. Here, we demonstrate that the use of IPA enables the detection of changes in charge transfer rates (i.e., current) at times <100 μs after the application of a potential pulse. Changes in sensor current are quantitatively related to target analyte concentration and can be used to create binding isotherms. Furthermore, the application of IPA enables rapid probing of the electrochemical surface with a time resolution equivalent to as low as twice the applied potential pulse width, not previously demonstrated with traditional voltammetric techniques employed with E-AB sensors (alternating current, square wave, cyclic). To visualize binding, we developed false-color plots analogous to those used in the field of fast-scan cyclic voltammetry. The use of IPA is universal, as demonstrated with two representative small molecule E-AB sensors directed against the aminoglycoside antibiotic tobramycin and adenosine triphosphate (ATP). Intermittent pulse amperometry exhibits an unprecedented sub-microsecond temporal response and is a general method for measuring rapid sensor performance.

Coherent pulse interrogation system for fiber Bragg grating sensing of strain and pressure in dynamic extremes of materials

DOE PAGES

Rodriguez, George; Jaime, Marcelo; Balakirev, Fedor; ...

2015-05-21

A 100 MHz fiber Bragg grating (FBG) interrogation system is described and applied to strain and pressure sensing. The approach relies on coherent pulse illumination of the FBG sensor with a broadband short pulse from a femtosecond modelocked erbium fiber laser. After interrogation of the FBG sensor, a long multi-kilometer run of single mode fiber is used for chromatic dispersion to temporally stretch the spectral components of the reflected pulse from the FBG sensor. Dynamic strain or pressure induced spectral shifts in the FBG sensor are detected as a pulsed time domain waveform shift after encoding by the chromatic dispersivemore » line. Signals are recorded using a single 35 GHz photodetector and a 50 GSamples per second, 25 GHz bandwidth, digitizing oscilloscope. Application of this approach to high-speed strain sensing in magnetic materials in pulsed magnetic fields to ~150 T is demonstrated. The FBG wavelength shifts are used to study magnetic field driven magnetostriction effects in LaCoO₃. A sub-microsecond temporal shift in the FBG sensor wavelength attached to the sample under first order phase change appears as a fractional length change (strain: ΔL/L<10⁻⁴) in the material. A second application used FBG sensing of pressure dynamics to nearly 2 GPa in the thermal ignition of the high explosive PBX-9501 is also demonstrated. In conclusion, both applications demonstrate the use of this FBG interrogation system in dynamical extreme conditions that would otherwise not be possible using traditional FBG interrogation approaches that are deemed too slow to resolve such events.« less

Excimer-laser-induced shock wave and its dependence on atmospheric environment

NASA Astrophysics Data System (ADS)

Krueger, Ronald R.; Krasinski, Jerzy S.; Radzewicz, Czeslaw

1993-06-01

High speed shadow photography is performed on excimer laser ablated porcine corneas and rubber stoppers to capture the excimer laser induced shock waves at various time delays between 40 and 320 nanoseconds. The shock waves in air, nitrogen, and helium are recorded by tangentially illuminating the ablated surface with a tunable dye laser, the XeCl excimer laser pulse. The excimer laser ablates the specimen and excites the dye laser, which is then passed through an optical delay line before illuminating the specimen. The shadow of the shock wave produced during ablation is then cast on a screen and photographed with a CCD video camera. The system is pulsed at 30 times per second to allow a video recording of the shock wave at a fixed time delay. We conclude that high energy acoustic waves and gaseous particles are liberated during excimer laser corneal ablation, and dissipate on a submicrosecond time scale. The velocity of their dissipation is dependent on the atmospheric environment and can be increased two-fold when the ablation is performed in a helium atmosphere. Therefore, local temperature increases due to the liberation of high energy gases may be reduced by using helium during corneal photoablation.

Identification of gram-negative and gram-positive bacteria by fluorescence studies

NASA Astrophysics Data System (ADS)

Demchak, Jonathan; Calabrese, Joseph; Tzolov, Marian

2011-03-01

Several type strains of bacteria including Vibrio fischeri, Azotobacter vinelandii, Enterobacter cloacae, and Corynebacterium xerosis, were cultured in the laboratory following standard diagnostic protocol based on their individual metabolic strategies. The bacterial cultures were not further treated and they were studied in their pristine state (pure culture - axenic). The fluorescent studies were applied using a continuous wave and a pulsed excitation light sources. Emission and excitation spectra were recorded for the continuous wave excitation and they all show similar spectral features with the exception of the gram positive bacteria showing vibronic structures. The vibrational modes involved in these vibronic bands have energy typical for carbon-carbon vibrations. The fluorescence is quenched in addition of water, even a very thin layer, which confirms that the observed spectral features originate from the outer parts of the bacteria. These results allow to conclude that the fluorescence spectroscopy can be used as a method for studying the membranes of the bacteria and eventually to discriminate between gram positive and gram negative bacteria. The pulsed experiments show that the fluorescence lifetime is in the sub-microsecond range. The results indicate that the observed spectra are superposition of the emission with different lifetimes.

Pink-beam serial crystallography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meents, A.; Wiedorn, M. O.; Srajer, V.

Serial X-ray crystallography allows macromolecular structure determination at both X-ray free electron lasers (XFELs) and, more recently, synchrotron sources. The time resolution for serial synchrotron crystallography experiments has been limited to millisecond timescales with monochromatic beams. The polychromatic, “pink”, beam provides a more than two orders of magnitude increased photon flux and hence allows accessing much shorter timescales in diffraction experiments at synchrotron sources. Here we report the structure determination of two different protein samples by merging pink-beam diffraction patterns from many crystals, each collected with a single 100 ps X-ray pulse exposure per crystal using a setup optimized formore » very low scattering background. In contrast to experiments with monochromatic radiation, data from only 50 crystals were required to obtain complete datasets. The high quality of the diffraction data highlights the potential of this method for studying irreversible reactions at sub-microsecond timescales using high-brightness X-ray facilities.« less

Pink-beam serial crystallography

DOE PAGES

Meents, A.; Wiedorn, M. O.; Srajer, V.; ...

2017-11-03

Serial X-ray crystallography allows macromolecular structure determination at both X-ray free electron lasers (XFELs) and, more recently, synchrotron sources. The time resolution for serial synchrotron crystallography experiments has been limited to millisecond timescales with monochromatic beams. The polychromatic, “pink”, beam provides a more than two orders of magnitude increased photon flux and hence allows accessing much shorter timescales in diffraction experiments at synchrotron sources. Here we report the structure determination of two different protein samples by merging pink-beam diffraction patterns from many crystals, each collected with a single 100 ps X-ray pulse exposure per crystal using a setup optimized formore » very low scattering background. In contrast to experiments with monochromatic radiation, data from only 50 crystals were required to obtain complete datasets. The high quality of the diffraction data highlights the potential of this method for studying irreversible reactions at sub-microsecond timescales using high-brightness X-ray facilities.« less

Experimental study of microwave-induced thermoacoustic imaging

NASA Astrophysics Data System (ADS)

Jacobs, Ryan T.

Microwave-Induced Thermoacoustic Imaging (TAI) is a noninvasive hybrid modality which improves contrast by using thermoelastic wave generation induced by microwave absorption. Ultrasonography is widely used in medical practice as a low-cost alternative and supplement to magnetic resonance imaging (MRI). Although ultrasonography has relatively high image resolution (depending on the ultrasonic wavelength at diagnostic frequencies), it suffers from low image contrast of soft tissues. In this work samples are irradiated with sub-microsecond electromagnetic pulses inducing acoustic waves in the sample that are then detected with an unfocused transducer. The advantage of this hybrid modality is the ability to take advantage of the microwave absorption coefficients which provide high contrast in tissue samples. This in combination with the superior spatial resolution of ultrasound waves is important to providing a low-cost alternative to MRI and early breast cancer detection methods. This work describes the implementation of a thermoacoustic experiment using a 5 kW peak power microwave source.

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

PubMed

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.

A compact submicrosecond, high current generator

NASA Astrophysics Data System (ADS)

Kovalchuk, B. M.; Kharlov, A. V.; Zorin, V. B.; Zherlitsyn, A. A.

2009-08-01

Pulsed current generator was developed for experiments with current carrying pulsed plasma. Main parts of the generator are capacitor bank, low inductive current driving lines, and central load part. Generator consists of four identical sections, connected in parallel to one load. Capacitor bank is assembled from 24 capacitor blocks (100 kV, 80 nF), connected in parallel. It stores 9.6 kJ at 100 kV charging voltage. Each capacitor block incorporates a multigap spark switch, which is able to commute by six parallel channels. Switches operate in dry air at atmospheric pressure. The generator was tested with an inductive load and a liner load. At 17.5 nH inductive load and 100 kV of charging voltage it provides 650 kA of current amplitude with 390 ns rise time with 0.6 Ω damping resistors in discharge circuit of each capacitor block. The net generator inductance without a load was optimized to be as low as 15 nH, which results in extremely low impedance of the generator (˜0.08 Ω). It ensures effective energy coupling with a low impedance load such as Z pinch. The generator operates reliably without any adjustments in 70-100 kV range of charging voltage. Jitter in delay between output pulse and triggering pulse is less than 5 ns at 70-100 kV charging voltage. Operation and handling are very simple, because no oil or purified gases are required for the generator. The generator has dimensions 5.24×1.2×0.18 m3 and total weight about 1400 kg, thus manifesting itself as simple, robust, and cost effective apparatus.

From mitochondrial ion channels to arrhythmias in the heart: computational techniques to bridge the spatio-temporal scales

PubMed Central

Plank, Gernot; Zhou, Lufang; Greenstein, Joseph L; Cortassa, Sonia; Winslow, Raimond L; O'Rourke, Brian; Trayanova, Natalia A

2008-01-01

Computer simulations of electrical behaviour in the whole ventricles have become commonplace during the last few years. The goals of this article are (i) to review the techniques that are currently employed to model cardiac electrical activity in the heart, discussing the strengths and weaknesses of the various approaches, and (ii) to implement a novel modelling approach, based on physiological reasoning, that lifts some of the restrictions imposed by current state-of-the-art ionic models. To illustrate the latter approach, the present study uses a recently developed ionic model of the ventricular myocyte that incorporates an excitation–contraction coupling and mitochondrial energetics model. A paradigm to bridge the vastly disparate spatial and temporal scales, from subcellular processes to the entire organ, and from sub-microseconds to minutes, is presented. Achieving sufficient computational efficiency is the key to success in the quest to develop multiscale realistic models that are expected to lead to better understanding of the mechanisms of arrhythmia induction following failure at the organelle level, and ultimately to the development of novel therapeutic applications. PMID:18603526

VLF and X-ray Instruments for Stratospheric Balloons: ABOVE2 and EPEx

NASA Astrophysics Data System (ADS)

Cully, C. M.; Galts, D.; Patrick, M.; Duffin, C.; Jang, A. C.; Pitzel, J.; Trumpour, T.; McCarthy, M.; Milling, D. K.

2017-12-01

The ABOVE2 (2016) and EPEx (2018) stratospheric balloon missions are designed to study energetic electrons precipitating from the radiation belts into the atmosphere. The payloads include instruments that measure Very Low Frequency (VLF) magnetic and electric fields, and bremsstrahlung X-rays. The ABOVE2 VLF instrument is an FPGA-based design with >200 kHz sampling rates, sub-microsecond timing accuracy and onboard spectral processing, designed in a Cubesat-friendly format. The EPEx X-ray instrument is a hard X-ray imaging system, also in a Cubesat-friendly format, incorporating a commercially-available Cadmium-Zinc-Telluride module. The imager is sufficiently lightweight that we can launch it on-demand with low-volume latex balloons. I will discuss the design and performance of both instruments, and present data from the ABOVE2 flights.

Evaluation of sub-microsecond recovery resonators for In Vivo Electron Paramagnetic Resonance Imaging

PubMed Central

F, Hyodo; S, Subramanian; N, Devasahayam; R, Murugesan; K, Matsumoto; JB, Mitchell; MC, Krishna

2008-01-01

Time-domain (TD) electron paramagnetic resonance (EPR) imaging at 300 MHz for in vivo applications requires resonators with recovery times less than 1 microsecond after pulsed excitation to reliably capture the rapidly decaying free induction decay (FID). In this study, we tested the suitability of the Litz foil coil resonator (LCR), commonly used in MRI, for in vivo EPR/EPRI applications in the TD mode and compared with parallel coil resonator (PCR). In TD mode, the sensitivity of LCR was lower than that of the PCR. However, in continuous wave (CW) mode, the LCR showed better sensitivity. The RF homogeneity was similar in both the resonators. The axis of the RF magnetic field is transverse to the cylindrical axis of the LCR, making the resonator and the magnet co-axial. Therefore, the loading of animals, and placing of the anesthesia nose cone and temperature monitors was more convenient in the LCR compared to the PCR whose axis is perpendicular to the magnet axis. PMID:18042414

The dE/dt and E Waveforms Radiated by Leader Steps Just Before the First Return Stroke in Cloud-to-Ocean Lightning

NASA Astrophysics Data System (ADS)

Krider, E. P.; Baffou, G.; Murray, N. D.; Willett, J. C.

2004-12-01

We have analyzed the shapes and other characteristics of the electric field, E, and dE/dt waveforms that were radiated by leader steps just before the first return stroke in cloud-to-ocean lightning. dE/dt waveforms were recorded using an 8-bit digitizer sampling at 100 MHz, and an integrated waveform, Eint, was computed by numerically integrating dE/dt and comparing the result with an analog E waveform digitized at 10 MHz. All signals were recorded under conditions where the lightning locations were known and there was minimal distortion in the fields due to the effects of ground-wave propagation. The dE/dt waveforms radiated by leader steps tend to fall into three categories: (1) "simple" - an isolated negative peak that is immediately followed by a positive overshoot (where negative polarity follows the normal physics convention), (2) "double" - two simple waveforms that occur at almost the same time, and (3) "burst" - a complex cluster of pulses with a total duration of about one microsecond. In this paper, we will give examples of each of these waveform types, and we will summarize their characteristics on a submicrosecond time-scale. For example, in an interval starting 9 μ s before to 4 μ s before the largest, negative (dominant) peak in dE/dt peak in the return stroke, 131 first strokes produced a total of 296 impulses with a peak amplitude greater than 10% of the dominant peak, and the average amplitude of these pulses was 0.21 of the dominant peak. The last leader step in a 12 μ s interval before the dominant peak was a simple waveform in 51 first strokes, and in these cases, the average time-interval between the peak dE/dt of the step and the dominant peak of the stroke was 5.8 ± 1.7 μ s, a value that is in good agreement with prior measurements. The median full-width-at-half-maximum (FWHM) of 274 simple Eint signatures was 141 ns, and the associated mean and standard deviation were 187 ± 131 ns.

Langmuir probe diagnostic suite in the C-2 field-reversed configuration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roche, T., E-mail: troche@trialphaenergy.com; Armstrong, S.; Knapp, K.

2014-11-15

Several in situ probes have been designed and implemented into the diagnostic array of the C-2 field-reversed configuration (FRC) at Tri Alpha Energy [M. Tuszewski et al. (the TAE Team), Phys. Rev. Lett. 108, 255008 (2012)]. The probes are all variations on the traditional Langmuir probe. They include linear arrays of triple probes, linear arrays of single-tipped swept probes, a multi-faced Gundestrup probe, and an ion-sensitive probe. The probes vary from 5 to 7 mm diameter in size to minimize plasma perturbations. They also have boron nitride outer casings that prevent unwanted electrical breakdown and reduce the introduction of impurities.more » The probes are mounted on motorized linear-actuators allowing for programmatic scans of the various plasma parameters over the course of several shots. Each probe has a custom set of electronics that allows for measurement of the desired signals. High frequency ( > 5MHz) analog optical-isolators ensure that plasma parameters can be measured at sub-microsecond time scales while providing electrical isolation between machine and data acquisition systems. With these probes time-resolved plasma parameters (temperature, density, spatial potential, flow, and electric field) can be directly/locally measured in the FRC jet and edge/scrape-off layer.« less

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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

2016-06-01

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

Transmembrane potential measurements on plant cells using the voltage-sensitive dye ANNINE-6.

PubMed

Flickinger, Bianca; Berghöfer, Thomas; Hohenberger, Petra; Eing, Christian; Frey, Wolfgang

2010-11-01

The charging of the plasma membrane is a necessary condition for the generation of an electric-field-induced permeability increase of the plasmalemma, which is usually explained by the creation and the growth of aqueous pores. For cells suspended in physiological buffers, the time domain of membrane charging is in the submicrosecond range. Systematic measurements using Nicotiana tabacum L. cv. Bright Yellow 2 (BY-2) protoplasts stained with the fast voltage-sensitive fluorescence dye ANNINE-6 have been performed using a pulsed laser fluorescence microscopy setup with a time resolution of 5 ns. A clear saturation of the membrane voltage could be measured, caused by a strong membrane permeability increase, commonly explained by enhanced pore formation, which prevents further membrane charging by external electric field exposure. The field strength dependence of the protoplast's transmembrane potential V (M) shows strong asymmetric saturation characteristics due to the high resting potential of the plants plasmalemma. At the pole of the hyperpolarized hemisphere of the cell, saturation starts at an external field strength of 0.3 kV/cm, resulting in a measured transmembrane voltage shift of ∆V(M) = -150 mV, while on the cathodic (depolarized) cell pole, the threshold for enhanced pore formation is reached at a field strength of approximately 1.0 kV/cm and ∆V(M) = 450 mV, respectively. From this asymmetry of the measured maximum membrane voltage shifts, the resting potential of BY-2 protoplasts at the given experimental conditions can be determined to V(R) = -150 mV. Consequently, a strong membrane permeability increase occurs when the membrane voltage diverges |V(M)| = 300 mV from the resting potential of the protoplast. The largest membrane voltage change at a given external electric field occurs at the cell poles. The azimuthal dependence of the transmembrane potential, measured in angular intervals of 10° along the circumference of the cell, shows a flattening and a slight decrease at higher fields at the pole region due to enhanced pore formation. Additionally, at the hyperpolarized cell pole, a polarization reversal could be observed at an external field range around 1.0 kV/cm. This behavior might be attributed to a fast charge transfer through the membrane at the hyperpolarized pole, e.g., by voltage-gated channels.

Dielectric Barrier Discharges: Pulsed Breakdown, Electrical Characterization and Chemistry

DTIC Science & Technology

2013-06-01

DIELECTRIC BARRIER DISCHARGES : PULSED BREAKDOWN, ELECTRICAL CHARACTERIZATION AND CHEMISTRY  R. Brandenburg, H. Höft, T. Hoder, A. Pipa, R...for pulsed driven Dielectric Barrier Discharges (DBDs) in particular. Fast electrical, optical and spectroscopic methods enable the study of...2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Dielectric Barrier Discharges : Pulsed Breakdown, Electrical Characterization

Submicrosecond characteristics of lightning return-stroke currents

NASA Technical Reports Server (NTRS)

Leteinturier, Christiane; Hamelin, Joel H.; Eybert-Berard, Andre

1991-01-01

The authors describe the experimental results obtained during 1987 and 1988 triggered-lightning experiments in Florida. Seventy-four simultaneous submicrosecond time-resolved measurements of triggered return-stroke current (I) and current derivative (dI/dt) were made in Florida in 1987 and 1988. Peak currents ranged from about 5 to 76 kA, peak dI/dt amplitude from 13 to 411 kA/microsec and rise time from 90 to 1000 ns. The mean peak dI/dt values of 110 kA/microsec were 2-3 times higher than data from instrumented towers and peak I and dI/dt appear to be positively correlated. These data confirm previous experiments and conclusions supported by forty measurements. They are important in order to define, for example, standards for lightning protection. Present standards give a dI/dt maximum of 140 kA/microsec.

Submicrosecond electro-optic switching in the liquid-crystal smectic A phase: The soft-mode ferroelectric effect

NASA Astrophysics Data System (ADS)

Andersson, G.; Dahl, I.; Keller, P.; Kuczyński, W.; Lagerwall, S. T.; Skarp, K.; Stebler, B.

1987-08-01

A new liquid-crystal electro-optic modulating device similar to the surface-stabilized ferroelectric liquid-crystal device is described. It uses the same kind of ferroelectric chiral smectics and the same geometry as that device (thin sample in the ``bookshelf '' layer arrangement) but instead of using a tilted smectic phase like the C* phase, it utilizes the above-lying, nonferroelectric A phase, taking advantage of the electroclinic effect. The achievable optical intensity modulation that can be detected through the full range of the A phase is considerably lower than for the surface-stabilized device, but the response is much faster. Furthermore, the response is strictly linear with respect to the applied electric field. The device concept is thus appropriate for modulator rather than for display applications. We describe the underlying physics and present measurements of induced tilt angle, of light modulation depth, and of rise time.

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

USDA-ARS?s Scientific Manuscript database

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, ...

Prefire identification for pulse-power systems

DOEpatents

Longmire, J.L.; Thuot, M.E.; Warren, D.S.

1982-08-23

Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

Prefire identification for pulse power systems

DOEpatents

Longmire, Jerry L.; Thuot, Michael E.; Warren, David S.

1985-01-01

Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

Optically activated switches for the generation of complex electrical waveforms with multigigahertz bandwidth

NASA Astrophysics Data System (ADS)

Skeldon, Mark D.; Okishev, Andrey V.; Letzring, Samuel A.; Donaldson, William R.; Green, Kenton; Seka, Wolf D.; Fuller, Lynn F.

1995-01-01

An electrical pulse-generation system using two optically activated Si photoconductive switches can generate shaped electrical pulses with multigigahertz bandwidth. The Si switches are activated by an optical pulse whose leading edge is steepened by stimulated Brillouin scattering (SBS) in CCl4. With the bandwidth generated by the SBS process, a laser having a 1- to 3-ns pulse width is used to generate electrical pulses with approximately 80-ps rise times (approximately 4-GHz bandwidth). Variable impedance microstrip lines are used to generate complex electrical waveforms that can be transferred to a matched load with minimal loss of bandwidth.

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

PubMed

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

2015-12-01

Electroporation of cells is successfully used in biology, biotechnology and medicine. Practical problems still arise in the electroporation of cells in suspension. For example, the determination of cell electroporation is still a demanding and time-consuming task. Electric pulses also cause contamination of the solution by the metal released from the electrodes and create local enhancements of the electric field, leading to the occurrence of electrochemical reactions at the electrode/electrolyte interface. In our study, we investigated the possibility of assessing modifications to the cell environment caused by pulsed electric fields using electrochemical impedance spectroscopy. We designed an experimental protocol to elucidate the mechanism by which a pulsed electric field affects the electrode state in relation to different electrolyte conductivities at the interface. The results show that a pulsed electric field affects electrodes and its degree depends on the electrolyte conductivity. Evolution of the electrochemical reaction rate depends on the initial free charges and those generated by the pulsed electric field. In the presence of biological cells, the initial free charges in the medium are reduced. The electrical current path at low frequency is longer, i.e., conductivity is decreased, even in the presence of increased permeability of the cell membrane created by the pulsed electric field. Copyright © 2015 Elsevier B.V. All rights reserved.

Using electric pulse and laser to trigger a sharp and nonvolatile change of lateral photovoltage in nano-carbon film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gan, Zhikai; Zhou, Peiqi; Huang, Xu

A greatly enhanced lateral photovoltage (LPV) triggered by electric pulse has been observed in nano-carbon oxide semiconductor (COS) structures. The original maximal output signal of lateral photovoltage achieved in these structures is 9.8 mV. However, by combining the application of a 60 V voltage pulse with laser illumination, the LPV can reach a very high value of 183 mV and the change ratio after 60 V pulse is nearly 1800%. In addition, the states of these light and electric-pulse triggered COSs are permanently changed, showing a non-volatile characteristic. We attribute this phenomenon to the trapping effect of stimulated electrons in COSs. The work suggestsmore » an approach for tailoring LPV-based devices by electric pulse and will be useful for the development of electric pulse modulated photodetectors.« less

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

DOEpatents

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

2005-02-08

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

Current density imaging sequence for monitoring current distribution during delivery of electric pulses in irreversible electroporation.

PubMed

Serša, Igor; Kranjc, Matej; Miklavčič, Damijan

2015-01-01

Electroporation is gaining its importance in everyday clinical practice of cancer treatment. For its success it is extremely important that coverage of the target tissue, i.e. treated tumor, with electric field is within the specified range. Therefore, an efficient tool for the electric field monitoring in the tumor during delivery of electroporation pulses is needed. The electric field can be reconstructed by the magnetic resonance electric impedance tomography method from current density distribution data. In this study, the use of current density imaging with MRI for monitoring current density distribution during delivery of irreversible electroporation pulses was demonstrated. Using a modified single-shot RARE sequence, where four 3000 V and 100 μs long pulses were included at the start, current distribution between a pair of electrodes inserted in a liver tissue sample was imaged. Two repetitions of the sequence with phases of refocusing radiofrequency pulses 90° apart were needed to acquire one current density image. For each sample in total 45 current density images were acquired to follow a standard protocol for irreversible electroporation where 90 electric pulses are delivered at 1 Hz. Acquired current density images showed that the current density in the middle of the sample increased from first to last electric pulses by 60%, i.e. from 8 kA/m2 to 13 kA/m2 and that direction of the current path did not change with repeated electric pulses significantly. The presented single-shot RARE-based current density imaging sequence was used successfully to image current distribution during delivery of short high-voltage electric pulses. The method has a potential to enable monitoring of tumor coverage by electric field during irreversible electroporation tissue ablation.

Spatial Acuity and Prey Detection in Weakly Electric Fish

PubMed Central

Babineau, David; Lewis, John E; Longtin, André

2007-01-01

It is well-known that weakly electric fish can exhibit extreme temporal acuity at the behavioral level, discriminating time intervals in the submicrosecond range. However, relatively little is known about the spatial acuity of the electrosense. Here we use a recently developed model of the electric field generated by Apteronotus leptorhynchus to study spatial acuity and small signal extraction. We show that the quality of sensory information available on the lateral body surface is highest for objects close to the fish's midbody, suggesting that spatial acuity should be highest at this location. Overall, however, this information is relatively blurry and the electrosense exhibits relatively poor acuity. Despite this apparent limitation, weakly electric fish are able to extract the minute signals generated by small prey, even in the presence of large background signals. In fact, we show that the fish's poor spatial acuity may actually enhance prey detection under some conditions. This occurs because the electric image produced by a spatially dense background is relatively “blurred” or spatially uniform. Hence, the small spatially localized prey signal “pops out” when fish motion is simulated. This shows explicitly how the back-and-forth swimming, characteristic of these fish, can be used to generate motion cues that, as in other animals, assist in the extraction of sensory information when signal-to-noise ratios are low. Our study also reveals the importance of the structure of complex electrosensory backgrounds. Whereas large-object spacing is favorable for discriminating the individual elements of a scene, small spacing can increase the fish's ability to resolve a single target object against this background. PMID:17335346

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

PubMed

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. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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.

The Study for Shortening the Process Time at Soy Food Production by using the Pulsed Electric Field

NASA Astrophysics Data System (ADS)

Saito, Tsukasa; Jinushi, Makoto; Minamitani, Yasushi

We investigated method to osmose water and seasoner to dried soybeans fast by pulsed electric field, in order to make soybeans a processed food fast. By applying the pulsed electric field to the dried soybeans in water, osmosis time of water to the soybean became approximately half. Then the emission of the discharge was observed on dried soybean. The color of coffee permeated more into the soybean treated than no-treated by the pulsed electric field.

Electroclinic effect in the chiral lamellar α phase of a lyotropic liquid crystal

NASA Astrophysics Data System (ADS)

Harjung, Marc D.; Giesselmann, Frank

2018-03-01

In thermotropic chiral Sm -A* phases, an electric field along the smectic layers breaks the D∞ symmetry of the Sm -A* phase and induces a tilt of the liquid crystal director. This so-called electroclinic effect (ECE) was first reported by Garoff and Meyer in 1977 and attracted substantial scientific and technological interest due to its linear and submicrosecond electro-optic response [S. Garoff and R. B. Meyer, Phys. Rev. A 19, 338 (1979), 10.1103/PhysRevA.19.338]. We now report the observation of an ECE in the pretransitional regime from a lyotropic chiral lamellar Lα* phase into a lyo-Sm -C* phase, the lyotropic analog to the thermotropic Sm -C* phase which was recently discovered by Bruckner et al. [Angew. Chem. Int. Ed. 52, 8934 (2013), 10.1002/anie.201303344]. We further show that the observed ECE has all signatures of its thermotropic counterpart, namely (i) the effect is chiral in nature and vanishes in the racemic Lα phase, (ii) the effect is essentially linear in the sign and magnitude of the electric field, and (iii) the magnitude of the effect diverges hyperbolically as the temperature approaches the critical temperature of the second order tilting transition. Specific deviations between the ECEs in chiral lamellar and chiral smectic phases are related to the internal field screening effect of electric double layers formed by inevitable ionic impurities in lyotropic phases.

Critical Infrastructure Protection: EMP Impacts on the U.S. Electric Grid

NASA Astrophysics Data System (ADS)

Boston, Edwin J., Jr.

The purpose of this research is to identify the United States electric grid infrastructure systems vulnerabilities to electromagnetic pulse attacks and the cyber-based impacts of those vulnerabilities to the electric grid. Additionally, the research identifies multiple defensive strategies designed to harden the electric grid against electromagnetic pulse attack that include prevention, mitigation and recovery postures. Research results confirm the importance of the electric grid to the United States critical infrastructures system and that an electromagnetic pulse attack against the electric grid could result in electric grid degradation, critical infrastructure(s) damage and the potential for societal collapse. The conclusions of this research indicate that while an electromagnetic pulse attack against the United States electric grid could have catastrophic impacts on American society, there are currently many defensive strategies under consideration designed to prevent, mitigate and or recover from an electromagnetic pulse attack. However, additional research is essential to further identify future target hardening opportunities, efficient implementation strategies and funding resources.

Experimental characterization and numerical modeling of tissue electrical conductivity during pulsed electric fields for irreversible electroporation treatment planning.

PubMed

Neal, Robert E; Garcia, Paulo A; Robertson, John L; Davalos, Rafael V

2012-04-01

Irreversible electroporation is a new technique to kill cells in targeted tissue, such as tumors, through a nonthermal mechanism using electric pulses to irrecoverably disrupt the cell membrane. Treatment effects relate to the tissue electric field distribution, which can be predicted with numerical modeling for therapy planning. Pulse effects will change the cell and tissue properties through thermal and electroporation (EP)-based processes. This investigation characterizes these changes by measuring the electrical conductivity and temperature of ex vivo renal porcine tissue within a single pulse and for a 200 pulse protocol. These changes are incorporated into an equivalent circuit model for cells and tissue with a variable EP-based resistance, providing a potential method to estimate conductivity as a function of electric field and pulse length for other tissues. Finally, a numerical model using a human kidney volumetric mesh evaluated how treatment predictions vary when EP- and temperature-based electrical conductivity changes are incorporated. We conclude that significant changes in predicted outcomes will occur when the experimental results are applied to the numerical model, where the direction and degree of change varies with the electric field considered.

Effect of Shock Waves Generated by Pulsed Electric Discharges in Water on Yeast Cells and Virus Particles

NASA Astrophysics Data System (ADS)

Girdyuk, A. E.; Gorshkov, A. N.; Egorov, V. V.; Kolikov, V. A.; Snetov, V. N.; Shneerson, G. A.

2018-02-01

The aim of this study is to determine the optimal parameters of the electric pulses and shock waves generated by them for the soft destruction of the virus and yeast envelopes with no changes in the structure of antigenic surface albumin and in the cell morphology in order to use them to produce antivirus vaccines and in biotechnology. The pulse electric discharges in water have been studied for different values of amplitude, pulse duration and the rate of the rise in the current. A mathematical model has been developed to estimate the optimal parameters of pulsed electric charges and shock waves for the complete destruction of the yeast cell envelopes and virus particles at a minimum of pulses.

Cell Fragmentation and Permeabilization by a 1 ns Pulse Driven Triple-Point Electrode

PubMed Central

Li, Joy; Cho, Michael

2018-01-01

Ultrashort electric pulses (ns-ps) are useful in gaining understanding as to how pulsed electric fields act upon biological cells, but the electric field intensity to induce biological responses is typically higher than longer pulses and therefore a high voltage ultrashort pulse generator is required. To deliver 1 ns pulses with sufficient electric field but at a relatively low voltage, we used a glass-encapsulated tungsten wire triple-point electrode (TPE) at the interface among glass, tungsten wire, and water when it is immersed in water. A high electric field (2 MV/cm) can be created when pulses are applied. However, such a high electric field was found to cause bubble emission and temperature rise in the water near the electrode. They can be attributed to Joule heating near the electrode. Adherent cells on a cover slip treated by the combination of these stimuli showed two major effects: (1) cells in a crater (<100 μm from electrode) were fragmented and the debris was blown away. The principal mechanism for the damage is presumed to be shear forces due to bubble collapse; and (2) cells in the periphery of the crater were permeabilized, which was due to the combination of bubble movement and microstreaming as well as pulsed electric fields. These results show that ultrashort electric fields assisted by microbubbles can cause significant cell response and therefore a triple-point electrode is a useful ablation tool for applications that require submillimeter precision. PMID:29744357

Electric converters of electromagnetic strike machine with battery power

NASA Astrophysics Data System (ADS)

Usanov, K. M.; Volgin, A. V.; Kargin, V. A.; Moiseev, A. P.; Chetverikov, E. A.

2018-03-01

At present, the application of pulse linear electromagnetic engines to drive strike machines for immersion of rod elements into the soil, strike drilling of shallow wells, dynamic probing of soils is recognized as quite effective. The pulse linear electromagnetic engine performs discrete consumption and conversion of electrical energy into mechanical work. Pulse dosing of a stream transmitted by the battery source to the pulse linear electromagnetic engine of the energy is provided by the electrical converter. The electric converters with the control of an electromagnetic strike machine as functions of time and armature movement, which form the unipolar supply pulses of voltage and current necessary for the normal operation of a pulse linear electromagnetic engine, are proposed. Electric converters are stable in operation, implement the necessary range of output parameters control determined by the technological process conditions, have noise immunity and automatic disconnection of power supply in emergency modes.

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

PubMed

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

2012-01-01

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

The Role of Additional Pulses in Electropermeabilization Protocols

PubMed Central

Suárez, Cecilia; Soba, Alejandro; Maglietti, Felipe; Olaiz, Nahuel; Marshall, Guillermo

2014-01-01

Electropermeabilization (EP) based protocols such as those applied in medicine, food processing or environmental management, are well established and widely used. The applied voltage, as well as tissue electric conductivity, are of utmost importance for assessing final electropermeabilized area and thus EP effectiveness. Experimental results from literature report that, under certain EP protocols, consecutive pulses increase tissue electric conductivity and even the permeabilization amount. Here we introduce a theoretical model that takes into account this effect in the application of an EP-based protocol, and its validation with experimental measurements. The theoretical model describes the electric field distribution by a nonlinear Laplace equation with a variable conductivity coefficient depending on the electric field, the temperature and the quantity of pulses, and the Penne's Bioheat equation for temperature variations. In the experiments, a vegetable tissue model (potato slice) is used for measuring electric currents and tissue electropermeabilized area in different EP protocols. Experimental measurements show that, during sequential pulses and keeping constant the applied voltage, the electric current density and the blackened (electropermeabilized) area increase. This behavior can only be attributed to a rise in the electric conductivity due to a higher number of pulses. Accordingly, we present a theoretical modeling of an EP protocol that predicts correctly the increment in the electric current density observed experimentally during the addition of pulses. The model also demonstrates that the electric current increase is due to a rise in the electric conductivity, in turn induced by temperature and pulse number, with no significant changes in the electric field distribution. The EP model introduced, based on a novel formulation of the electric conductivity, leads to a more realistic description of the EP phenomenon, hopefully providing more accurate predictions of treatment outcomes. PMID:25437512

Effect of Fixed Versus Adjusted Transcutaneous Electrical Nerve Stimulation Amplitude on Chronic Mechanical Low Back Pain.

PubMed

Elserty, Noha; Kattabei, Omaima; Elhafez, Hytham

2016-07-01

This study aimed to investigate the effect of adjusting pulse amplitude of transcutaneous electrical nerve stimulation versus fixed pulse amplitude in treatment of chronic mechanical low back pain. Randomized clinical trial. El-sahel Teaching Hospital, Egypt. Forty-five patients with chronic low back pain assigned to three equal groups. Their ages ranged from 20 to 50 years. The three groups received the same exercise program. Group A received transcutaneous electrical nerve stimulation with fixed pulse amplitude for 40 minutes. Group B received transcutaneous electrical nerve stimulation with adjusted pulse amplitude for 40 minutes, with the pulse amplitude adjusted every 5 minutes. Group C received exercises only. Treatment sessions were applied three times per week for 4 weeks for the three groups. A visual analogue scale was used to assess pain severity, the Oswestry Disability Index was used to assess functional level, and a dual inclinometer was used to measure lumbar range of motion. Evaluations were performed before and after treatment. Visual analogue scale, Oswestry Disability Index, and back range of motion significantly differed between the two groups that received transcutaneous electrical nerve stimulation and the control group and did not significantly differ between fixed and adjusted pulse amplitude of transcutaneous electrical nerve stimulation. Adjusting pulse amplitude of transcutaneous electrical nerve stimulation does not produce a difference in the effect of transcutaneous electrical nerve stimulation used to treat chronic low back pain.

Electrochemical system and method for electropolishing superconductive radio frequency cavities

DOEpatents

Taylor, E. Jennings; Inman, Maria E.; Hall, Timothy

2015-04-14

An electrochemical finishing system for super conducting radio frequency (SCRF) cavities including a low viscosity electrolyte solution that is free of hydrofluoric acid, an electrode in contact with the electrolyte solution, the SCRF cavity being spaced apart from the electrode and in contact with the electrolyte solution and a power source including a first electrical lead electrically coupled to the electrode and a second electrical lead electrically coupled to the cavity, the power source being configured to pass an electric current between the electrode and the workpiece, wherein the electric current includes anodic pulses and cathodic pulses, and wherein the cathodic pulses are interposed between at least some of the anodic pulses. The SCRF cavity may be vertically oriented during the finishing process.

Energy-Saving Sintering of Electrically Conductive Powders by Modified Pulsed Electric Current Heating Using an Electrically Nonconductive Die

NASA Astrophysics Data System (ADS)

Ito, Mikio; Kawahara, Kenta; Araki, Keita

2014-04-01

Sintering of Cu and thermoelectric Ca3Co4O9 was tried using a modified pulsed electric current sintering (PECS) process, where an electrically nonconductive die was used instead of a conventional graphite die. The pulsed electric current flowed through graphite punches and sample powder, which caused the Joule heating of the powder compact itself, resulting in sintering under smaller power consumption. Especially for the Ca3Co4O9 powder, densification during sintering was also accelerated by this modified PECS process.

Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

DOEpatents

Thompson, D.O.; Hsu, D.K.

1993-12-14

The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses. 25 figures.

Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

DOEpatents

Thompson, Donald O.; Hsu, David K.

1993-12-14

The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

Automated pulse discrimination of two freely-swimming weakly electric fish and analysis of their electrical behavior during dominance contest.

PubMed

Guariento, Rafael T; Mosqueiro, Thiago S; Matias, Paulo; Cesarino, Vinicius B; Almeida, Lirio O B; Slaets, Jan F W; Maia, Leonardo P; Pinto, Reynaldo D

2016-10-01

Electric fishes modulate their electric organ discharges with a remarkable variability. Some patterns can be easily identified, such as pulse rate changes, offs and chirps, which are often associated with important behavioral contexts, including aggression, hiding and mating. However, these behaviors are only observed when at least two fish are freely interacting. Although their electrical pulses can be easily recorded by non-invasive techniques, discriminating the emitter of each pulse is challenging when physically similar fish are allowed to freely move and interact. Here we optimized a custom-made software recently designed to identify the emitter of pulses by using automated chirp detection, adaptive threshold for pulse detection and slightly changing how the recorded signals are integrated. With these optimizations, we performed a quantitative analysis of the statistical changes throughout the dominance contest with respect to Inter Pulse Intervals, Chirps and Offs dyads of freely moving Gymnotus carapo. In all dyads, chirps were signatures of subsequent submission, even when they occurred early in the contest. Although offs were observed in both dominant and submissive fish, they were substantially more frequent in submissive individuals, in agreement with the idea from previous studies that offs are electric cues of submission. In general, after the dominance is established the submissive fish significantly changes its average pulse rate, while the pulse rate of the dominant remained unchanged. Additionally, no chirps or offs were observed when two fish were manually kept in direct physical contact, suggesting that these electric behaviors are not automatic responses to physical contact. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photoconductive circuit element pulse generator

DOEpatents

Rauscher, Christen

1989-01-01

A pulse generator for characterizing semiconductor devices at millimeter wavelength frequencies where a photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test.

Developing Si(Li) nuclear radiation detectors by pulsed electric field treatment

NASA Astrophysics Data System (ADS)

Muminov, R. A.; Radzhapov, S. A.; Saimbetov, A. K.

2009-08-01

Fabrication of Si(Li) nuclear radiation detectors using lithium ion drift under the action of a pulsed electric field is considered. Optimum treatment regime parameters are determined, including the pulse amplitude, duration, and repetition rate. Experimental data are presented, which show that the ion drift in a pulsed electric field decreases the semiconductor bulk compensation time by a factor of two to four and significantly increases the efficiency of detectors.

Optimized extraction of polysaccharides from corn silk by pulsed electric field and response surface quadratic design.

PubMed

Zhao, Wenzhu; Yu, Zhipeng; Liu, Jingbo; Yu, Yiding; Yin, Yongguang; Lin, Songyi; Chen, Feng

2011-09-01

Corn silk is a traditional Chinese herbal medicine, which has been widely used for treatment of some diseases. In this study the effects of pulsed electric field on the extraction of polysaccharides from corn silk were investigated. Polysaccharides in corn silk were extracted by pulsed electric field and optimized by response surface methodology (RSM), based on a Box-Behnken design (BBD). Three independent variables, including electric field intensity (kV cm(-1) ), ratio of liquid to raw material and pulse duration (µs), were investigated. The experimental data were fitted to a second-order polynomial equation and also profiled into the corresponding 3-D contour plots. Optimal extraction conditions were as follows: electric field intensity 30 kV cm(-1) , ratio of liquid to raw material 50, and pulse duration 6 µs. Under these condition, the experimental yield of extracted polysaccharides was 7.31% ± 0.15%, matching well with the predicted value. The results showed that a pulsed electric field could be applied to extract value-added products from foods and/or agricultural matrix. Copyright © 2011 Society of Chemical Industry.

Electrical control of calcium oscillations in mesenchymal stem cells using microsecond pulsed electric fields.

PubMed

Hanna, Hanna; Andre, Franck M; Mir, Lluis M

2017-04-20

Human mesenchymal stem cells are promising tools for regenerative medicine due to their ability to differentiate into many cellular types such as osteocytes, chondrocytes and adipocytes amongst many other cell types. These cells present spontaneous calcium oscillations implicating calcium channels and pumps of the plasma membrane and the endoplasmic reticulum. These oscillations regulate many basic functions in the cell such as proliferation and differentiation. Therefore, the possibility to mimic or regulate these oscillations might be useful to regulate mesenchymal stem cells biological functions. One or several electric pulses of 100 μs were used to induce Ca 2+ spikes caused by the penetration of Ca 2+ from the extracellular medium, through the transiently electropermeabilized plasma membrane, in human adipose mesenchymal stem cells from several donors. Attached cells were preloaded with Fluo-4 AM and exposed to the electric pulse(s) under the fluorescence microscope. Viability was also checked. According to the pulse(s) electric field amplitude, it is possible to generate a supplementary calcium spike with properties close to those of calcium spontaneous oscillations, or, on the contrary, to inhibit the spontaneous calcium oscillations for a very long time compared to the pulse duration. Through that inhibition of the oscillations, Ca 2+ oscillations of desired amplitude and frequency could then be imposed on the cells using subsequent electric pulses. None of the pulses used here, even those with the highest amplitude, caused a loss of cell viability. An easy way to control Ca 2+ oscillations in mesenchymal stem cells, through their cancellation or the addition of supplementary Ca 2+ spikes, is reported here. Indeed, the direct link between the microsecond electric pulse(s) delivery and the occurrence/cancellation of cytosolic Ca 2+ spikes allowed us to mimic and regulate the Ca 2+ oscillations in these cells. Since microsecond electric pulse delivery constitutes a simple technology available in many laboratories, this new tool might be useful to further investigate the role of Ca 2+ in human mesenchymal stem cells biological processes such as proliferation and differentiation.

Compact submicrosecond, high current generator for wire explosion experiments

NASA Astrophysics Data System (ADS)

Aranchuk, L. E.; Chuvatin, A. S.; Larour, J.

2004-01-01

The PIAF generator was designed for low total energy and high energy density experiments with liners, X-pinch or fiber Z-pinch loads. These studies are of interest for such applications as surface and material science, microscopy of biological specimens, lithography of x-ray sensitive resists, and x-ray backlighting of pulsed-power plasmas. The generator is based on an RLC circuit that includes six NWL 180 nF-50 kV capacitors that store up to 1.3 kJ. The capacitors are connected in parallel to a single multispark switch designed to operate at atmospheric pressure. The switch allows reaching a time delay between the trigger pulse and the current pulse of less than 80 ns and has jitter of 6 ns. The total inductance without a load compartment was optimized to be as low as 16 nH, which leads to extremely low impedance of ˜0.12 Ω. A 40 kV initial voltage provides 250 kA maximum current in a 6 nH inductive load with a 180 ns current rise time. PIAF has dimensions of 660×660×490 mm and weight of less than 100 kg, thus manifesting itself as robust, simple to operate, and cost effective. A description of the PIAF generator and the initial experimental results on PIAF with an X-pinch type load are reported. The generator was demonstrated to operate successfully with an X-pinch type load. The experiments first started with investigation of the previously unexplored X-pinch conduction time range, 100 ns-1 μs. A single short radiation pulse was obtained that came from a small, point-like plasma. The following x-ray source characteristics were achieved: typical hot spot size of 50-100 μm, radiation pulse duration of 1.5-2 ns, and radiation yield of about 250-500 mJ in the softer spectral range (hν⩾700 eV) and 50-100 mJ in the harder one (hν⩾1 keV). These results provide the potential for further application of this source, such as use as a backlight diagnostic tool.

Pulse shaping system

DOEpatents

Skeldon, Mark D.; Letzring, Samuel A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Pulse shaping system

DOEpatents

Skeldon, M.D.; Letzring, S.A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

NASA Astrophysics Data System (ADS)

Novickij, Vitalij; Grainys, Audrius; Lastauskienė, Eglė; Kananavičiūtė, Rūta; Pamedytytė, Dovilė; Kalėdienė, Lilija; Novickij, Jurij; Miklavčič, Damijan

2016-09-01

Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2-3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100-250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation.

Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

PubMed Central

Novickij, Vitalij; Grainys, Audrius; Lastauskienė, Eglė; Kananavičiūtė, Rūta; Pamedytytė, Dovilė; Kalėdienė, Lilija; Novickij, Jurij; Miklavčič, Damijan

2016-01-01

Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2–3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100–250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation. PMID:27634482

[Mechanism of ablation with nanosecond pulsed electric field].

PubMed

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.

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

NASA Astrophysics Data System (ADS)

Roth, Caleb C.

Background: Exposures of cells to very short (less than 1 microsecond) electric pulses in the megavolt/meter range have been shown to cause a multitude of effects, both physical and molecular in nature. Physically, nanosecond electrical pulse exposure can disrupt the plasma membrane, leading to a phenomenon known as nanoporation. Nanoporation is the production of nanometer sized holes (less than 2 nanometers in diameter) that can persist for up to fifteen minutes, allowing the flow of ions into and out of the cell. Nanoporation can lead to secondary physical effects, such as cellular swelling, shrinking and blebbing. Molecularly, nanosecond electrical pulses have been shown to activate signaling pathways, produce oxidative stress, stimulate hormone secretion and induce both apoptotic and necrotic death. The mechanism by which nanosecond electrical pulses cause molecular changes is unknown; however, it is thought the flow of ions, such as calcium, into the cell via nanopores, could be a major cause. The ability of nanosecond electrical pulses to cause membranes to become permeable and to induce apoptosis makes the technology a desirable modality for cancer research; however, the lack of understanding regarding the mechanisms by which nanosecond electrical pulses cause nanoporation impedes further development of this technology. This dissertation documents the genomic and proteomic responses of cells exposed to nanosecond electrical pulses and describes in detail the biophysical effects of these electrical pulses, including the demonstration for the first time of the generation of acoustic pressure transients capable of disrupting plasma membranes and possibly contributing to nanoporation. Methods: Jurkat, clone E6-1 (human lymphocytic cell line), U937 (human lymphocytic cell line), Chinese hamster ovarian cells and adult primary human dermal fibroblasts exposed to nanosecond electrical pulses were subjected to a variety of molecular assays, including flow cytometry, 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 nucleic acid stain, was greatly enhanced. Conclusions: We found several genes, some of which are mechanosensitive, were selectively up-regulated due to nanosecond electrical pulse exposure. The source of this apparent mechanical stress was likely the acoustic pressure transients generated by the nanosecond electrical pulse exposure interacting with the plasma membrane of exposed cells. Contrary to our original hypothesis that these acoustic pressure transients enhance nanoporation, it appears that the opposite is true. Acoustic pressure transients generated by nanosecond electrical pulses inhibit nanoporation (or at least are negatively correlated with nanopore formation). This finding is substantiated by other reports in the literature, which indicate shock waves produced by electrical exposures inhibit gene transfection. General Significance: This work provides strong evidence that cells exposed to nanosecond electrical pulses experience a mechanical stress which by some unknown mechanism inhibits nanoporation. The findings in this dissertation are not only poised to cause a paradigm shift in how researchers understand electrical pulses cause electropermeabilization, but also will help fill in a gap in the knowledge concerning this technology, thus enabling its further development as a potential cancer therapy.

Electrical Switching of Perovskite Thin-Film Resistors

NASA Technical Reports Server (NTRS)

Liu, Shangqing; Wu, Juan; Ignatiev, Alex

2010-01-01

Electronic devices that exploit electrical switching of physical properties of thin films of perovskite materials (especially colossal magnetoresistive materials) have been invented. Unlike some related prior devices, these devices function at room temperature and do not depend on externally applied magnetic fields. Devices of this type can be designed to function as sensors (exhibiting varying electrical resistance in response to varying temperature, magnetic field, electric field, and/or mechanical pressure) and as elements of electronic memories. The underlying principle is that the application of one or more short electrical pulse(s) can induce a reversible, irreversible, or partly reversible change in the electrical, thermal, mechanical, and magnetic properties of a thin perovskite film. The energy in the pulse must be large enough to induce the desired change but not so large as to destroy the film. Depending on the requirements of a specific application, the pulse(s) can have any of a large variety of waveforms (e.g., square, triangular, or sine) and be of positive, negative, or alternating polarity. In some applications, it could be necessary to use multiple pulses to induce successive incremental physical changes. In one class of applications, electrical pulses of suitable shapes, sizes, and polarities are applied to vary the detection sensitivities of sensors. Another class of applications arises in electronic circuits in which certain resistance values are required to be variable: Incorporating the affected resistors into devices of the present type makes it possible to control their resistances electrically over wide ranges, and the lifetimes of electrically variable resistors exceed those of conventional mechanically variable resistors. Another and potentially the most important class of applications is that of resistance-based nonvolatile-memory devices, such as a resistance random access memory (RRAM) described in the immediately following article, Electrically Variable Resistive Memory Devices (MFS-32511-1).

Cryosurgery with pulsed electric fields.

PubMed

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 ablate cells in the high subzero freezing region of a cryosurgical lesion.

Time-resolved processes in a pulsed electrical discharge in argon bubbles in water

NASA Astrophysics Data System (ADS)

Gershman, S.; Belkind, A.

2010-12-01

A phenomenological picture of a pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging characterization methods. The discharge is generated by applying 1 μ s pulses of 5 to 20 kV between a needle and a disk electrode submerged in water. An Ar gas bubble surrounds the tip of the needle electrode. Imaging, electrical characteristics, and time-resolved optical emission spectroscopic data suggest a fast streamer propagation mechanism and the formation of a plasma channel in the bubble. Comparing the electrical and imaging data for consecutive pulses applied to the bubble 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 the presence of long-lived chemical species, such as ozone and oxygen. Imaging and electrical data show the presence of two discharge events during each applied voltage pulse, a forward discharge near the beginning of the applied pulse depositing charge on the surface of the bubble and a reverse discharge removing the accumulated charge from the water/gas interface when the applied voltage is turned off. The pd value of ~ 300-500 torr cm, the 1 μs long pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique compared to the traditional corona or dielectric barrier discharges.

Petawatt pulsed-power accelerator

DOEpatents

Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

2010-03-16

A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

Bottom-Up Tri-gate Transistors and Submicrosecond Photodetectors from Guided CdS Nanowalls.

PubMed

Xu, Jinyou; Oksenberg, Eitan; Popovitz-Biro, Ronit; Rechav, Katya; Joselevich, Ernesto

2017-11-08

Tri-gate transistors offer better performance than planar transistors by exerting additional gate control over a channel from two lateral sides of semiconductor nanowalls (or "fins"). Here we report the bottom-up assembly of aligned CdS nanowalls by a simultaneous combination of horizontal catalytic vapor-liquid-solid growth and vertical facet-selective noncatalytic vapor-solid growth and their parallel integration into tri-gate transistors and photodetectors at wafer scale (cm 2 ) without postgrowth transfer or alignment steps. These tri-gate transistors act as enhancement-mode transistors with an on/off current ratio on the order of 10 8 , 4 orders of magnitude higher than the best results ever reported for planar enhancement-mode CdS transistors. The response time of the photodetector is reduced to the submicrosecond level, 1 order of magnitude shorter than the best results ever reported for photodetectors made of bottom-up semiconductor nanostructures. Guided semiconductor nanowalls open new opportunities for high-performance 3D nanodevices assembled from the bottom up.

Efficient Suppression of Electron–Hole Recombination in Oxygen-Deficient Hydrogen-Treated TiO2 Nanowires for Photoelectrochemical Water Splitting

PubMed Central

2013-01-01

There is an increasing level of interest in the use of black TiO2 prepared by thermal hydrogen treatments (H:TiO2) due to the potential to enhance both the photocatalytic and the light-harvesting properties of TiO2. Here, we examine oxygen-deficient H:TiO2 nanotube arrays that have previously achieved very high solar-to-hydrogen (STH) efficiencies due to incident photon-to-current efficiency (IPCE) values of >90% for photoelectrochemical water splitting at only 0.4 V vs RHE under UV illumination. Our transient absorption (TA) mechanistic study provides strong evidence that the improved electrical properties of oxygen-deficient TiO2 enables remarkably efficient spatial separation of electron–hole pairs on the submicrosecond time scale at moderate applied bias, and this coupled to effective suppression of microsecond to seconds charge carrier recombination is the primary factor behind the dramatically improved photoelectrochemical activity. PMID:24376902

Plasma Membrane Permeabilization by Trains of Ultrashort Electric Pulses

PubMed Central

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

2010-01-01

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

Unitary scintillation detector and system

DOEpatents

McElhaney, Stephanie A.; Chiles, Marion M.

1994-01-01

The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations.

High power solid state laser modulator

DOEpatents

Birx, Daniel L.; Ball, Don G.; Cook, Edward G.

2004-04-27

A multi-stage magnetic modulator provides a pulse train of .+-.40 kV electrical pulses at a 5-7 kHz repetition rate to a metal vapor laser. A fractional turn transformer steps up the voltage by a factor of 80 to 1 and magnetic pulse compression is used to reduce the pulse width of the pulse train. The transformer is fabricated utilizing a rod and plate stack type of construction to achieve a high packing factor. The pulses are controlled by an SCR stack where a plurality of SCRs are electrically connected in parallel, each SCR electrically connected to a saturable inductor, all saturable inductors being wound on the same core of magnetic material for enhanced power handling characteristics.

Unitary scintillation detector and system

DOEpatents

McElhaney, S.A.; Chiles, M.M.

1994-05-31

The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations. 10 figs.

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Y.; Liu, S.; Lindenberg, A. M.

There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈ 10 11 K/s) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO 3 occurring on few picosecond time scales. Here, we explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on amore » ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO 3 and BaTiO 3. Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.« less

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

DOE PAGES

Qi, Y.; Liu, S.; Lindenberg, A. M.; ...

2018-01-30

There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈ 10 11 K/s) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO 3 occurring on few picosecond time scales. Here, we explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on amore » ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO 3 and BaTiO 3. Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.« less

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

NASA Astrophysics Data System (ADS)

Qi, Y.; Liu, S.; Lindenberg, A. M.; Rappe, A. M.

2018-01-01

There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈1011 K /s ) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO3 occurring on few picosecond time scales. We explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on a ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO3 and BaTiO3 . Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.

The second phase of bipolar, nanosecond-range electric pulses determines the electroporation efficiency.

PubMed

Pakhomov, Andrei G; Grigoryev, Sergey; Semenov, Iurii; Casciola, Maura; Jiang, Chunqi; Xiao, Shu

2018-03-29

Bipolar cancellation refers to a phenomenon when applying a second electric pulse reduces ("cancels") cell membrane damage by a preceding electric pulse of the opposite polarity. Bipolar cancellation is a reason why bipolar nanosecond electric pulses (nsEP) cause weaker electroporation than just a single unipolar phase of the same pulse. This study was undertaken to explore the dependence of bipolar cancellation on nsEP parameters, with emphasis on the amplitude ratio of two opposite polarity phases of a bipolar pulse. Individual cells (CHO, U937, or adult mouse ventricular cardiomyocytes (VCM)) were exposed to either uni- or bipolar trapezoidal nsEP, or to nanosecond electric field oscillations (NEFO). The membrane injury was evaluated by time-lapse confocal imaging of the uptake of propidium (Pr) or YO-PRO-1 (YP) dyes and by phosphatidylserine (PS) externalization. Within studied limits, bipolar cancellation showed little or no dependence on the electric field intensity, pulse repetition rate, chosen endpoint, or cell type. However, cancellation could increase for larger pulse numbers and/or for longer pulses. The sole most critical parameter which determines bipolar cancellation was the phase ratio: maximum cancellation was observed with the 2nd phase of about 50% of the first one, whereas a larger 2nd phase could add a damaging effect of its own. "Swapping" the two phases, i.e., delivering the smaller phase before the larger one, reduced or eliminated cancellation. These findings are discussed in the context of hypothetical mechanisms of bipolar cancellation and electroporation by nsEP. Copyright © 2018 Elsevier B.V. All rights reserved.

Ozone and dinitrogen monoxide production in atmospheric pressure air dielectric barrier discharge plasma effluent generated by nanosecond pulse superimposed alternating current voltage

NASA Astrophysics Data System (ADS)

Takashima, Keisuke; Kaneko, Toshiro

2017-06-01

The effects of nanosecond pulse superposition to alternating current voltage (NS + AC) on the generation of an air dielectric barrier discharge (DBD) plasma and reactive species are experimentally studied, along with measurements of ozone (O3) and dinitrogen monoxide (N2O) in the exhausted gas through the air DBD plasma (air plasma effluent). The charge-voltage cycle measurement indicates that the role of nanosecond pulse superposition is to induce electrical charge transport and excess charge accumulation on the dielectric surface following the nanosecond pulses. The densities of O3 and N2O in NS + AC DBD are found to be significantly increased in the plasma effluent, compared to the sum of those densities generated in NS DBD and AC DBD operated individually. The production of O3 and N2O is modulated significantly by the phase in which the nanosecond pulse is superimposed. The density increase and modulation effects by the nanosecond pulse are found to correspond with the electrical charge transport and the excess electrical charge accumulation induced by the nanosecond pulse. It is suggested that the electrical charge transport by the nanosecond pulse might result in the enhancement of the nanosecond pulse current, which may lead to more efficient molecular dissociation, and the excess electrical charge accumulation induced by the nanosecond pulse increases the discharge coupling power which would enhance molecular dissociation.

Avoiding the side effects of electric current pulse application to electroporated cells in disposable small volume cuvettes assures good cell survival.

PubMed

Grys, Maciej; Madeja, Zbigniew; Korohoda, Włodzimierz

2017-01-01

The harmful side effects of electroporation to cells due to local changes in pH, the appearance of toxic electrode products, temperature increase, and the heterogeneity of the electric field acting on cells in the cuvettes used for electroporation were observed and discussed in several laboratories. If cells are subjected to weak electric fields for prolonged periods, for example in experiments on cell electrophoresis or galvanotaxis the same effects are seen. In these experiments investigators managed to reduce or eliminate the harmful side effects of electric current application. For the experiments, disposable 20 μl cuvettes with two walls made of dialysis membranes were constructed and placed in a locally focused electric field at a considerable distance from the electrodes. Cuvettes were mounted into an apparatus for horizontal electrophoresis and the cells were subjected to direct current electric field (dcEF) pulses from a commercial pulse generator of exponentially declining pulses and from a custom-made generator of double and single rectangular pulses. More than 80% of the electroporated cells survived the dcEF pulses in both systems. Side effects related to electrodes were eliminated in both the flow through the dcEF and in the disposable cuvettes placed in the focused dcEFs. With a disposable cuvette system, we also confirmed the sensitization of cells to a dcEF using procaine by observing the loading of AT2 cells with calceine and using a square pulse generator, applying 50 ms single rectangular pulses. We suggest that the same methods of avoiding the side effects of electric current pulse application as in cell electrophoresis and galvanotaxis should also be used for electroporation. This conclusion was confirmed in our electroporation experiments performed in conditions assuring survival of over 80% of the electroporated cells. If the amplitude, duration, and shape of the dcEF pulse are known, then electroporation does not depend on the type of pulse generator. This knowledge of the characteristics of the pulse assures reproducibility of electroporation experiments using different equipment.

Effect of applied voltage and inter-pulse delay in spark-assisted LIBS

NASA Astrophysics Data System (ADS)

Robledo-Martinez, A.; Sobral, H.; Garcia-Villarreal, A.

2018-06-01

We report the results obtained in an investigation on the effect of the time delay between the laser and electrical pulses in a spark-assisted laser-induced breakdown spectroscopy (LIBS) experiment. The electrical discharge is produced by the discharge of a charged coaxial cable. This arrangement produces a fast unipolar current pulse (500 ns) that applies high power ( 600 kW) to the laser ablation plasma. The delay between the laser pulse and the electric pulse can be controlled at will in order to find the optimal time in terms of enhancement of the emitted lines. It was found that the application of the high voltage pulse enhances the ionic lines emitted by up to two orders of magnitude. An additional enhancement by a factor of 2-4 can be obtained delaying the application of the electric pulse by a time of 0.6-20 μs. In the tests it was noticed that the ionic lines were found to be clearly responsive to increments in the applied electric energy while the neutral lines did so marginally. Our results show that the intensification of the lines is mainly due to reheating of the ablation plasma as the application of the electrical pulse increments the temperature of the ablation plasma by about 50%. It is demonstrated that the present technique is an efficient way of intensifying the lines emitted without incurring in additional damage to the sample.

Interaction of an electron with coherent dipole radiation: Role of convergence and anti-dephasing

NASA Astrophysics Data System (ADS)

Robinson, A. P. L.; Arefiev, A. V.

2018-05-01

The impact of longitudinal electric fields that are present in intense focusing and defocusing electromagnetic pulses on electron acceleration is investigated. These fields are typically much weaker than the transverse fields, but it is shown that they can have a profound effect on electron energy gain. It is shown that the longitudinal electric field of a defocusing pulse is directed backward along the trajectory of an accelerated electron, which leads to a continuous net energy gain. At the same time, the effect of the transverse oscillating electric field in a defocusing pulse is to reduce the electron energy over multiple oscillations. In contrast to a well-known interaction with a plane wave, the electron is able to retain a substantial amount of energy following its interaction with a defocusing pulse. The roles of the transverse and longitudinal electric fields are reversed in a focusing pulse, which leads to a reduction in the energy retention. The present analysis underscores the importance of relatively weak oscillating electric fields in focusing and defocusing pulses.

Wind farm electrical system

DOEpatents

Erdman, William L.; Lettenmaier, Terry M.

2006-07-04

An approach to wind farm design using variable speed wind turbines with low pulse number electrical output. The output of multiple wind turbines are aggregated to create a high pulse number electrical output at a point of common coupling with a utility grid network. Power quality at each individual wind turbine falls short of utility standards, but the aggregated output at the point of common coupling is within acceptable tolerances for utility power quality. The approach for aggregating low pulse number electrical output from multiple wind turbines relies upon a pad mounted transformer at each wind turbine that performs phase multiplication on the output of each wind turbine. Phase multiplication converts a modified square wave from the wind turbine into a 6 pulse output. Phase shifting of the 6 pulse output from each wind turbine allows the aggregated output of multiple wind turbines to be a 24 pulse approximation of a sine wave. Additional filtering and VAR control is embedded within the wind farm to take advantage of the wind farm's electrical impedence characteristics to further enhance power quality at the point of common coupling.

Transmembrane molecular transport during versus after extremely large, nanosecond electric pulses.

PubMed

Smith, Kyle C; Weaver, James C

2011-08-19

Recently there has been intense and growing interest in the non-thermal biological effects of nanosecond electric pulses, particularly apoptosis induction. These effects have been hypothesized to result from the widespread creation of small, lipidic pores in the plasma and organelle membranes of cells (supra-electroporation) and, more specifically, ionic and molecular transport through these pores. Here we show that transport occurs overwhelmingly after pulsing. First, we show that the electrical drift distance for typical charged solutes during nanosecond pulses (up to 100 ns), even those with very large magnitudes (up to 10 MV/m), ranges from only a fraction of the membrane thickness (5 nm) to several membrane thicknesses. This is much smaller than the diameter of a typical cell (∼16 μm), which implies that molecular drift transport during nanosecond pulses is necessarily minimal. This implication is not dependent on assumptions about pore density or the molecular flux through pores. Second, we show that molecular transport resulting from post-pulse diffusion through minimum-size pores is orders of magnitude larger than electrical drift-driven transport during nanosecond pulses. While field-assisted charge entry and the magnitude of flux favor transport during nanosecond pulses, these effects are too small to overcome the orders of magnitude more time available for post-pulse transport. Therefore, the basic conclusion that essentially all transmembrane molecular transport occurs post-pulse holds across the plausible range of relevant parameters. Our analysis shows that a primary direct consequence of nanosecond electric pulses is the creation (or maintenance) of large populations of small pores in cell membranes that govern post-pulse transmembrane transport of small ions and molecules. Copyright © 2011 Elsevier Inc. All rights reserved.

Transmembrane molecular transport during versus after extremely large, nanosecond electric pulses

PubMed Central

Smith, Kyle C.; Weaver, James C.

2012-01-01

Recently there has been intense and growing interest in the non-thermal biological effects of nanosecond electric pulses, particularly apoptosis induction. These effects have been hypothesized to result from the widespread creation of small, lipidic pores in the plasma and organelle membranes of cells (supra-electroporation) and, more specifically, ionic and molecular transport through these pores. Here we show that transport occurs overwhelmingly after pulsing. First, we show that the electrical drift distance for typical charged solutes during nanosecond pulses (up to 100 ns), even those with very large magnitudes (up to 10 MV/m), ranges from only a fraction of the membrane thickness (5 nm) to several membrane thicknesses. This is much smaller than the diameter of a typical cell (~16 μm), which implies that molecular drift transport during nanosecond pulses is necessarily minimal. This implication is not dependent on assumptions about pore density or the molecular flux through pores. Second, we show that molecular transport resulting from post-pulse diffusion through minimum-size pores is orders of magnitude larger than electrical drift-driven transport during nanosecond pulses. While field-assisted charge entry and the magnitude of flux favor transport during nanosecond pulses, these effects are too small to overcome the orders of magnitude more time available for post-pulse transport. Therefore, the basic conclusion that essentially all transmembrane molecular transport occurs post-pulse holds across the plausible range of relevant parameters. Our analysis shows that a primary direct consequence of nanosecond electric pulses is the creation (or maintenance) of large populations of small pores in cell membranes that govern post-pulse transmembrane transport of small ions and molecules. PMID:21756883

Electric field-mediated transport of plasmid DNA in tumor interstitium in vivo.

PubMed

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

2007-11-01

Local pulsed electric field application is a method for improving non-viral gene delivery. Mechanisms of the improvement include electroporation and electrophoresis. To understand how electrophoresis affects pDNA delivery in vivo, we quantified the magnitude of electric field-induced interstitial transport of pDNA in 4T1 and B16.F10 tumors implanted in mouse dorsal skin-fold chambers. Four different electric pulse sequences were used in this study, each consisted of 10 identical pulses that were 100 or 400 V/cm in strength and 20 or 50 ms in duration. The interval between consecutive pulses was 1 s. The largest distance of transport was obtained with the 400 V/cm and 50 ms pulse, and was 0.23 and 0.22 microm/pulse in 4T1 and B16.F10 tumors, respectively. There were no significant differences in transport distances between 4T1 and B16.F10 tumors. Results from in vivo mapping and numerical simulations revealed an approximately uniform intratumoral electric field that was predominantly in the direction of the applied field. The data in the study suggested that interstitial transport of pDNA induced by a sequence of ten electric pulses was ineffective for macroscopic delivery of genes in tumors. However, the induced transport was more efficient than passive diffusion.

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

PubMed

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.

Automatic Realistic Real Time Stimulation/Recording in Weakly Electric Fish: Long Time Behavior Characterization in Freely Swimming Fish and Stimuli Discrimination

PubMed Central

Forlim, Caroline G.; Pinto, Reynaldo D.

2014-01-01

Weakly electric fish are unique model systems in neuroethology, that allow experimentalists to non-invasively, access, central nervous system generated spatio-temporal electric patterns of pulses with roles in at least 2 complex and incompletely understood abilities: electrocommunication and electrolocation. Pulse-type electric fish alter their inter pulse intervals (IPIs) according to different behavioral contexts as aggression, hiding and mating. Nevertheless, only a few behavioral studies comparing the influence of different stimuli IPIs in the fish electric response have been conducted. We developed an apparatus that allows real time automatic realistic stimulation and simultaneous recording of electric pulses in freely moving Gymnotus carapo for several days. We detected and recorded pulse timestamps independently of the fish’s position for days. A stimulus fish was mimicked by a dipole electrode that reproduced the voltage time series of real conspecific according to previously recorded timestamp sequences. We characterized fish behavior and the eletrocommunication in 2 conditions: stimulated by IPIs pre-recorded from other fish and random IPI ones. All stimuli pulses had the exact Gymontus carapo waveform. All fish presented a surprisingly long transient exploratory behavior (more than 8 h) when exposed to a new environment in the absence of electrical stimuli. Further, we also show that fish are able to discriminate between real and random stimuli distributions by changing several characteristics of their IPI distribution. PMID:24400122

Modified Johnson-Cook model incorporated with electroplasticity for uniaxial tension under a pulsed electric current

NASA Astrophysics Data System (ADS)

Kim, Moon-Jo; Jeong, Hye-Jin; Park, Ju-Won; Hong, Sung-Tae; Han, Heung Nam

2018-01-01

An empirical expression describing the electroplastic deformation behavior is suggested based on the Johnson-Cook (JC) model by adding several functions to consider both thermal and athermal electric current effects. Tensile deformation behaviors are carried out for an AZ31 magnesium alloy and an Al-Mg-Si alloy under pulsed electric current at various current densities with a fixed duration of electric current. To describe the flow curves under electric current, a modified JC model is proposed to take the electric current effect into account. Phenomenological descriptions of the adopted parameters in the equation are made. The modified JC model suggested in the present study is capable of describing the tensile deformation behaviors under pulsed electric current reasonably well.

Cryosurgery with Pulsed Electric Fields

PubMed Central

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 ablate cells in the high subzero freezing region of a cryosurgical lesion. PMID:22087224

An "Off-the-Shelf" System for Intraprocedural Electrical Current Evaluation and Monitoring of Irreversible Electroporation Therapy.

PubMed

Neal, Robert E; Kavnoudias, Helen; Thomson, Kenneth R

2015-06-01

Irreversible electroporation (IRE) ablation uses a series of brief electric pulses to create nanoscale defects in cell membranes, killing the cells. It has shown promise in numerous soft-tissue tumor applications. Larger voltages between electrodes will increase ablation volume, but exceeding electrical limits may risk damage to the patient, cause ineffective therapy delivery, or require generator restart. Monitoring electrical current for these conditions in real-time enables managing these risks. This capacity is not presently available in clinical IRE generators. We describe a system using a Tektronix TCP305 AC/DC Current Probe connected to a TCPA300 AC/DC Current Probe Amplifier, which is read on a computer using a Protek DSO-2090 USB computer-interfacing oscilloscope. Accuracy of the system was tested with a resistor circuit and by comparing measured currents with final outputs from the NanoKnife clinical electroporation pulse generator. Accuracy of measured currents was 1.64 ± 2.4 % relative to calculations for the resistor circuit and averaged 0.371 ± 0.977 % deviation from the NanoKnife. During clinical pulse delivery, the system offers real-time evaluation of IRE procedure progress and enables a number of methods for identifying approaching issues from electrical behavior of therapy delivery, facilitating protocol changes before encountering therapy delivery issues. This system can monitor electrical currents in real-time without altering the electric pulses or modifying the pulse generator. This facilitates delivering electric pulse protocols that remain within the optimal range of electrical currents-sufficient strength for clinically relevant ablation volumes, without the risk of exceeding safe electric currents or causing inadequate ablation.

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

PubMed

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

2015-02-01

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

Electrical pulse generator

DOEpatents

Norris, Neil J.

1979-01-01

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

Recommended E3 HEMP Heave Electric Field Waveform for the Critical Infrastructures. Volume 2

DTIC Science & Technology

2017-07-31

OF THE COMMISSION TO ASSESS THE THREAT TO THE UNITED STATES FROM ELECTROMAGNETIC PULSE (EMP) ATTACK The cover photo depicts Fishbowl Starfish...Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack. The Commission was established by Congress in the FY2001 National...Department of Defense E electric field EMP electromagnetic pulse EPRI Electric Power Research Institute FERC Federal Energy Regulatory Commission GMD

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

PubMed

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

2016-03-01

Biofilm formation is a significant problem, accounting for over eighty percent of microbial infections in the body. Biofilm eradication is problematic due to increased resistance to antibiotics and antimicrobials as compared to planktonic cells. The purpose of this study was to investigate the effect of Pulsed Electric Fields (PEF) on biofilm-infected mesh. Prolene mesh was infected with bioluminescent Pseudomonas aeruginosa and treated with PEF using a concentric electrode system to derive, in a single experiment, the critical electric field strength needed to kill bacteria. The effect of the electric field strength and the number of pulses (with a fixed pulse length duration and frequency) on bacterial eradication was investigated. For all experiments, biofilm formation and disruption were confirmed with bioluminescent imaging and Scanning Electron Microscopy (SEM). Computation and statistical methods were used to analyze treatment efficiency and to compare it to existing theoretical models. In all experiments 1500 V are applied through a central electrode, with pulse duration of 50 μs, and pulse delivery frequency of 2 Hz. We found that the critical electric field strength (Ecr) needed to eradicate 100-80% of bacteria in the treated area was 121 ± 14 V/mm when 300 pulses were applied, and 235 ± 6.1 V/mm when 150 pulses were applied. The area at which 100-80% of bacteria were eradicated was 50.5 ± 9.9 mm(2) for 300 pulses, and 13.4 ± 0.65 mm(2) for 150 pulses. 80% threshold eradication was not achieved with 100 pulses. The results indicate that increased efficacy of treatment is due to increased number of pulses delivered. In addition, we that showed the bacterial death rate as a function of the electrical field follows the statistical Weibull model for 150 and 300 pulses. We hypothesize that in the clinical setting, combining systemic antibacterial therapy with PEF will yield a synergistic effect leading to improved eradication of mesh infections. © 2015 Wiley Periodicals, Inc.

Radiation-induced insulator discharge pulses in the CRRES internal discharge monitor satellite experiment

NASA Technical Reports Server (NTRS)

Frederickson, A. R.; Mullen, E. G.; Brautigam, D. H.; Kerns, K. J.

1992-01-01

The Internal Discharge Monitor (IDM) was designed to observe electrical pulses from common electrical insulators in space service. The sixteen insulator samples included twelve planar printed circuit boards and four cables. The samples were fully enclosed, mutually isolated, and space radiation penetrated 0.02 cm of aluminum before striking the samples. Pulsing began on the seventh orbit, the maximum pulse rate occurred on the seventeenth orbit when 13 pulses occurred, and the pulses slowly diminished to about one per 3 orbits six months later. After 8 months, the radiation belts abruptly increased and the pulse rates attained a new high. These pulse rates were in agreement with laboratory experience on shorter time scales. Several of the samples never pulsed. If the pulses were not confined within IDM, the physical processes could spread to become a full spacecraft anomaly. The IDM results indicate the rate at which small insulator pulses occur. Small pulses are the seeds of larger satellite electrical anomalies. The pulse rates are compared with space radiation intensities, L shell location, and spectral distributions from the radiation spectrometers on the Combined Release and Radiation Effects Satellite.

Effects of interaural time differences in fine structure and envelope on lateral discrimination in electric hearing.

PubMed

Majdak, Piotr; Laback, Bernhard; Baumgartner, Wolf-Dieter

2006-10-01

Bilateral cochlear implant (CI) listeners currently use stimulation strategies which encode interaural time differences (ITD) in the temporal envelope but which do not transmit ITD in the fine structure, due to the constant phase in the electric pulse train. To determine the utility of encoding ITD in the fine structure, ITD-based lateralization was investigated with four CI listeners and four normal hearing (NH) subjects listening to a simulation of electric stimulation. Lateralization discrimination was tested at different pulse rates for various combinations of independently controlled fine structure ITD and envelope ITD. Results for electric hearing show that the fine structure ITD had the strongest impact on lateralization at lower pulse rates, with significant effects for pulse rates up to 800 pulses per second. At higher pulse rates, lateralization discrimination depended solely on the envelope ITD. The data suggest that bilateral CI listeners benefit from transmitting fine structure ITD at lower pulse rates. However, there were strong interindividual differences: the better performing CI listeners performed comparably to the NH listeners.

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

PubMed

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

2016-08-01

For this systematic review, 203 published reports on effects of electroporation using nanosecond high-voltage electric pulses (nsEP) on eukaryotic cells (human, animal, plant) in vitro were analyzed. A field synopsis summarizes current published data in the field with respect to publication year, cell types, exposure configuration, and pulse duration. Published data were analyzed for effects observed in eight main target areas (plasma membrane, intracellular, apoptosis, calcium level and distribution, survival, nucleus, mitochondria, stress) and an additional 107 detailed outcomes. We statistically analyzed effects of nsEP with respect to three pulse duration groups: A: 1-10ns, B: 11-100ns and C: 101-999ns. The analysis confirmed that the plasma membrane is more affected with longer pulses than with short pulses, seen best in uptake of dye molecules after applying single pulses. Additionally, we have reviewed measurements of nsEP and evaluations of the electric fields to which cells were exposed in these reports, and we provide recommendations for assessing nanosecond pulsed electric field effects in electroporation studies. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Interaction of excitable waves emitted from two defects by pulsed electric fields

NASA Astrophysics Data System (ADS)

Chen, Jiang-Xing; Zhang, Han; Qiao, Li-Yan; Liang, Hong; Sun, Wei-Gang

2018-01-01

In response to a pulsed electric field, spatial distributed heterogeneities in excitable media can serve as nucleation sites for the generation of intramural electrical waves, a phenomenon called as ;wave emission from heterogeneities; (WEH effect). Heterogeneities in cardiac tissue strongly influence each other in the WEH effect. We study the WEH effect in a medium possessing two defects. The role of two defects and their interaction by pulsed DC electric fields (DEF) and rotating electric fields (REF) are investigated. The direction of the applied electric field plays a major role not only in the minimum electrical field necessary to originate wave propagation, but also in the degree of influences of nearby defects. The distance between two defects, i.e. the density of defects, also play an important role in the WEH effect. Generally, the REF is better than the DEF when pulsed electric fields are applied. These results may contribute to the improved application of WEH, especially in older patients with fibrosis and scarring, which are accompanied by a higher incidence of conductivity discontinuities.

Triplet Excitation Transfer between Carotenoids in the LH2 Complex from Photosynthetic Bacterium Rhodopseudomonas palustris.

PubMed

Feng, Juan; Wang, Qian; Wu, Yi-Shi; Ai, Xi-Cheng; Zhang, Xu-Jia; Huang, You-Guo; Zhang, Xing-Kang; Zhang, Jian-Ping

2004-01-01

We have studied, by means of sub-microsecond time-resolved absorption spectroscopy, the triplet-excited state dynamics of carotenoids (Cars) in the intermediate-light adapted LH2 complex (ML-LH2) from Rhodopseudomonas palustris containing Cars with different numbers of conjugated double bonds. Following pulsed photo-excitation at 590 nm at room temperature, rapid spectral equilibration was observed either as a red shift of the isosbestic wavelength on a time scale of 0.6-1.0 mus, or as a fast decay in the shorter-wavelength side of the T(n)<--T(1) absorption of Cars with a time constant of 0.5-0.8 mus. Two major spectral components assignable to Cars with 11 and 12 conjugated double bonds were identified. The equilibration was not observed in the ML-LH2 at 77 K, or in the LH2 complex from Rhodobacter sphaeroides G1C containing a single type of Car. The unique spectral equilibration was ascribed to temperature-dependent triplet excitation transfer among different Car compositions. The results suggest that Cars of 11 and 12 conjugated bonds, both in close proximity of BChls, may coexist in an alpha,beta-subunit of the ML-LH2 complex.

Real-time method and apparatus for measuring the temperature of a fluorescing phosphor

DOEpatents

Britton, Jr., Charles L.; Beshears, David L.; Simpson, Marc L.; Cates, Michael R.; Allison, Steve W.

1999-01-01

A method for determining the temperature of a fluorescing phosphor is provided, together with an apparatus for performing the method. The apparatus includes a photodetector for detecting light emitted by a phosphor irradiated with an excitation pulse and for converting the detected light into an electrical signal. The apparatus further includes a differentiator for differentiating the electrical signal and a zero-crossing discrimination circuit that outputs a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero. The width of the output pulse signal is proportional to the decay-time constant of the phosphor.

Validation of a pulsed electric field process to pasteurize strawberry puree

USDA-ARS?s Scientific Manuscript database

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...

Broadband tunable integrated CMOS pulser with 80-ps minimum pulse width for gain-switched semiconductor lasers.

PubMed

Chen, Shaoqiang; Diao, Shengxi; Li, Pengtao; Nakamura, Takahiro; Yoshita, Masahiro; Weng, Guoen; Hu, Xiaobo; Shi, Yanling; Liu, Yiqing; Akiyama, Hidefumi

2017-07-31

High power pulsed lasers with tunable pulse widths are highly favored in many applications. When combined with power amplification, gain-switched semiconductor lasers driven by broadband tunable electric pulsers can meet such requirements. For this reason, we designed and produced a low-cost integrated CMOS pulse generator with a minimum pulse width of 80 ps and a wide tuning range of up to 270 ns using a 40-nm microelectronic process technique. We used this pulser to drive a 1.3-µm semiconductor laser diode directly, and thereafter investigated the gain-switching properties of the laser system. The optical pulses consist of a spike followed by a steady state region. Tuning the width of the electrical pulse down to approximately 1.5 ns produces optical pulses consisting only of the spike, which has a minimum pulse-width of 100 ps. Moreover, the duration of the steady state can be tuned continuously by tuning the electrical pulse width, with a peak power of approximately 5 mW. The output voltage of the electric pulser has a tuning range of 0.8-1.5 V that can be used to directly drive semiconductor laser diodes with wavelengths in the near-infrared spectrum, which are suitable for power amplification with rare-earth doped fiber amplifiers.

Repetitive transcranial magnetic stimulator with controllable pulse parameters

NASA Astrophysics Data System (ADS)

Peterchev, Angel V.; Murphy, David L.; Lisanby, Sarah H.

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

Repetitive transcranial magnetic stimulator with controllable pulse parameters.

PubMed

Peterchev, Angel V; Murphy, David L; Lisanby, Sarah H

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

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

DOEpatents

Bartholomew, David B.

2006-11-14

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

Modeling digital pulse waveforms by solving one-dimensional Navier-stokes equations.

PubMed

Fedotov, Aleksandr A; Akulova, Anna S; Akulov, Sergey A

2016-08-01

Mathematical modeling for composition distal arterial pulse wave in the blood vessels of the upper limbs was considered. Formation of distal arterial pulse wave is represented as a composition of forward and reflected pulse waves propagating along the arterial vessels. The formal analogy between pulse waves propagation along the human arterial system and the propagation of electrical oscillations in electrical transmission lines with distributed parameters was proposed. Dependencies of pulse wave propagation along the human arterial system were obtained by solving the one-dimensional Navier-Stokes equations for a few special cases.

Pulsed source ion implantation apparatus and method

DOEpatents

Leung, Ka-Ngo

1996-01-01

A new pulsed plasma-immersion ion-implantation apparatus that implants ions in large irregularly shaped objects to controllable depth without overheating the target, minimizing voltage breakdown, and using a constant electrical bias applied to the target. Instead of pulsing the voltage applied to the target, the plasma source, for example a tungsten filament or a RF antenna, is pulsed. Both electrically conducting and insulating targets can be implanted.

Electric field measurements in nanosecond pulse discharges in air over liquid water surface

NASA Astrophysics Data System (ADS)

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

2018-01-01

Electric field in nanosecond pulse discharges in ambient air is measured by picosecond four-wave mixing, with absolute calibration by a known electrostatic field. The measurements are done in two geometries, (a) the discharge between two parallel cylinder electrodes placed inside quartz tubes, and (b) the discharge between a razor edge electrode and distilled water surface. In the first case, breakdown field exceeds DC breakdown threshold by approximately a factor of four, 140 ± 10 kV cm-1. In the second case, electric field is measured for both positive and negative pulse polarities, with pulse durations of ˜10 ns and ˜100 ns, respectively. In the short duration, positive polarity pulse, breakdown occurs at 85 kV cm-1, after which the electric field decreases over several ns due to charge separation in the plasma, with no field reversal detected when the applied voltage is reduced. In a long duration, negative polarity pulse, breakdown occurs at a lower electric field, 30 kV cm-1, after which the field decays over several tens of ns and reverses direction when the applied voltage is reduced at the end of the pulse. For both pulse polarities, electric field after the pulse decays on a microsecond time scale, due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Measurements 1 mm away from the discharge center plane, ˜100 μm from the water surface, show that during the voltage rise, horizontal field component (Ex ) lags in time behind the vertical component (Ey ). After breakdown, Ey is reduced to near zero and reverses direction. Further away from the water surface (≈0.9 mm), Ex is much higher compared to Ey during the entire voltage pulse. The results provide insight into air plasma kinetics and charge transport processes near plasma-liquid interface, over a wide range of time scales.

[Intracellular free calcium changes of mouse oocytes during activation induced by ethanol or electrical stimulations and parthenogenetic development].

PubMed

Deng, M Q; Fan, B Q

1994-09-01

Oocytes collected 18-19 h after HCG injection were stimulated with 7-8% ethanol or electrical pulses (1.7 KV/cm field strength, 80-100 microseconds duration, 3-4 times, 5-6 min interval). The parthenogenetic embryos derived from the above-mentioned methods developed to blastocyst stage just like those developed from fertilized eggs. Mouse oocytes were rather sensitive to ethanol stimulation. More than 95% of the treated oocytes were activated after stimulation of 7-8% ethanol for 5 min. Multiple electrical stimulations induced higher activation percentages of oocytes than only single electrical stimulation (71.5% vs. 63.6%). Intact oocytes were loaded with fluorescent Ca2+ indicator fura-2 and intracellular free calcium changes during artificial activation were measured by fluorescence detector. The results showed that ethanol could induce repetitive transient Ca2+ concentration increase in activated oocytes. Single electrical stimulation only induced single free calcium concentration elevation in oocyte while multiple electrical pulses could induce repetitive Ca2+ increase (each electrical pulse elicited the corresponding Ca2+ concentration peak). The pronuclei were not observed in the oocytes which had not exhibited calcium concentration rise during activation. Apart from electrical stimulation parameter, sufficient amount of Ca2+ in electric medium was crucial to mouse oocyte activation when stimulated with electrical pulses. The oocytes were hardly activated by electrical stimulations in a medium without Ca2+ even with longer pulse duration and the intracellular free calcium concentration in the oocytes showed no elevation. This indicates that the inflow of extracellular Ca2+ from tiny pores across the oocyte membrane caused by electrical stimulation is the main source of intracellular free calcium increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Nanopore formation in neuroblastoma cells following ultrashort electric pulse exposure

NASA Astrophysics Data System (ADS)

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

2011-03-01

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

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

PubMed

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.

Real-time method and apparatus for measuring the decay-time constant of a fluorescing phosphor

DOEpatents

Britton, Jr., Charles L.; Beshears, David L.; Simpson, Marc L.; Cates, Michael R.; Allison, Steve W.

1999-01-01

A method for determining the decay-time constant of a fluorescing phosphor is provided, together with an apparatus for performing the method. The apparatus includes a photodetector for detecting light emitted by a phosphor irradiated with an excitation pulse and for converting the detected light into an electrical signal. The apparatus further includes a differentiator for differentiating the electrical signal and a zero-crossing discrimination circuit that outputs a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero. The width of the output pulse signal is proportional to the decay-time constant of the phosphor.

Photonuclear Contributions to SNS Pulse Shapes

DOE Office of Scientific and Technical Information (OSTI.GOV)

McClanahan, Tucker C.; Iverson, Erik B.; Gallmeier, Franz X.

Short-pulsed sources like the Spallation Neutron Source (SNS) and ISIS produce bursts of neutron pulses at rates of 10-60 Hz, with sub-microsecond proton pulses impacting on high-Z target materials. Moderators are grouped around the target to receive the fast neutrons generated from spallation reactions to moderate them effciently to thermal and sub-thermal energies and to feed narrow neutron pulses to neutron scattering instruments. The scattering instruments use the neutrons as a probe for material investigations, and make use of time-of-flight (TOF) methods for resolving the neutron energy. The energy resolution of scattering instruments depends on the narrow time-structure of themore » neutron pulses, while neutrons in the long tail of the emission time distributions can degrade the instrument performance and add undesired background to measurements. The SNS neutronics team is investigating a possible source term impacting the background at short-pulsed spallation sources. The ISIS TS2 project claims to have significantly reduced neutron scattering instrument background levels by the elimination or reduction of iron shielding in the target-moderator-reflector assembly. An alternative hypothesis, also proposed by ISIS, suggests that this apparent reduction arises from moving beamline shielding away from the neutron guide channels, reducing albedo down the beamlines. In both hypotheses, the background neutrons in question are believed to be generated by photonuclear reactions. If the background neutrons are indeed generated via photonuclear channels, then they are generated in a time-dependent fashion, since most of the high-energy photons capable of inducing photonuclear production are gone within a few microseconds following the proton pulse. To evaluate this e ect, we have enabled photonuclear reactions in a series of studies for the SNS first target station (FTS) taking advantage of its Monte Carlo model. Using a mixture of ENDF/B VII.0 and TENDL-2014 photonuclear cross sections available and the CEM03 physics model within MCNPX 2.6.0 in the simulation, we are able to estimate the impact of photoneutron production on both overall neutron production and delayed neutron production. We find that a significant number of photon-induced neutrons are produced a few milliseconds after the proton pulse, following prompt gamma emission through the capture of neutrons in the slowing-down and thermalization processes. We name these "slowing-down delayed neutrons" to distinguish them from either "activation-delayed neutrons" or "beta-delayed neutrons." The beta-delayed and activation-delayed neutrons were not part of this study, and will be addressed elsewhere. While these other delayed neutron channels result in the time-independent (constant) production of fast neutrons outside of the prompt pulse, the slowing-down delayed neutrons also a ect the shape of the pulses. Although numerically insignificant in most cases, we describe a set of scenarios related to T0-chopper operation in which the slowing-down delayed neutrons may be important.« less

Effect of pulsed electric fields on the activity of neutral trehalase from beer yeast and RSM analysis.

PubMed

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. Copyright © 2012 Elsevier B.V. All rights reserved.

Pulsed source ion implantation apparatus and method

DOEpatents

Leung, K.N.

1996-09-24

A new pulsed plasma-immersion ion-implantation apparatus that implants ions in large irregularly shaped objects to controllable depth without overheating the target, minimizing voltage breakdown, and using a constant electrical bias applied to the target. Instead of pulsing the voltage applied to the target, the plasma source, for example a tungsten filament or a RF antenna, is pulsed. Both electrically conducting and insulating targets can be implanted. 16 figs.

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

PubMed

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kia, Kaveh Kazemi; Bonabi, Fahimeh

A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 {mu}s. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through themore » 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.« less

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

NASA Astrophysics Data System (ADS)

Kia, Kaveh Kazemi; Bonabi, Fahimeh

2012-12-01

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

[Rapid measurement of trace mercury in aqueous solutions with optical-electrical dual pulse LIBS technique].

PubMed

Zhang, Qian; Xiong, Wei; Chen, Yu-Qi; Li, Run-Hua

2011-02-01

A wood slice was used as absorber to transfer liquid sample to solid sample in order to solve the problems existing in directly analyzing aqueous solutions with laser-induced breakdown spectroscopy (LIBS). An optical-electrical dual pulse LIBS (OEDP-LIBS) technique was first used to enhance atomic emission of mercury in laser-induced plasma. The calibration curves of mercury were obtained by typical single pulse LIBS and OEDP-LIBS techniques. The limit of detection (LOD) of mercury in these two techniques reaches 2.4 and 0.3 mg x L(-1), respectively. Under current experimental conditions, the time-integrated a tomic emission of mercury at 253.65 nm was enhanced 50 times and the LOD of mercury was improved by one order, if comparing OEDP-LIBS to single pulse LIBS. The required time for a whole analysis process is less than 5 minutes. As the atomic emission of mercury decays slowly while increasing the delay time between electrical pulse and laser pulse, increasing the electrical pulse width can further enhance the time integrated intensity of mercury emission and improve the detection sensitivity of mercury by OEDP-LIBS technique.

ELECTRICAL PULSE COUNTER APPARATUS

DOEpatents

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

1962-09-01

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

PULSE SORTER

DOEpatents

Wade, E.J.

1958-07-29

An apparatus is described for counting and recording the number of electrical pulses occurring in each of a timed sequence of groups of pulses. The particular feature of the invention resides in a novel timing circuit of the univibrator type which provides very accurately timed pulses for opening each of a series of coincidence channels in sequence. The univibrator is shown incorporated in a pulse analyzing system wherein a series of pulse counting channels are periodically opened in order, one at a time, for a predetermtned open time interval, so that only one channel will be open at the time of occurrence of any of the electrical pulses to be sorted.

Fast quantum logic gates with trapped-ion qubits

NASA Astrophysics Data System (ADS)

Schäfer, V. M.; Ballance, C. J.; Thirumalai, K.; Stephenson, L. J.; Ballance, T. G.; Steane, A. M.; Lucas, D. M.

2018-03-01

Quantum bits (qubits) based on individual trapped atomic ions are a promising technology for building a quantum computer. The elementary operations necessary to do so have been achieved with the required precision for some error-correction schemes. However, the essential two-qubit logic gate that is used to generate quantum entanglement has hitherto always been performed in an adiabatic regime (in which the gate is slow compared with the characteristic motional frequencies of the ions in the trap), resulting in logic speeds of the order of 10 kilohertz. There have been numerous proposals of methods for performing gates faster than this natural ‘speed limit’ of the trap. Here we implement one such method, which uses amplitude-shaped laser pulses to drive the motion of the ions along trajectories designed so that the gate operation is insensitive to the optical phase of the pulses. This enables fast (megahertz-rate) quantum logic that is robust to fluctuations in the optical phase, which would otherwise be an important source of experimental error. We demonstrate entanglement generation for gate times as short as 480 nanoseconds—less than a single oscillation period of an ion in the trap and eight orders of magnitude shorter than the memory coherence time measured in similar calcium-43 hyperfine qubits. The power of the method is most evident at intermediate timescales, at which it yields a gate error more than ten times lower than can be attained using conventional techniques; for example, we achieve a 1.6-microsecond-duration gate with a fidelity of 99.8 per cent. Faster and higher-fidelity gates are possible at the cost of greater laser intensity. The method requires only a single amplitude-shaped pulse and one pair of beams derived from a continuous-wave laser. It offers the prospect of combining the unrivalled coherence properties, operation fidelities and optical connectivity of trapped-ion qubits with the submicrosecond logic speeds that are usually associated with solid-state devices.

Fast quantum logic gates with trapped-ion qubits.

PubMed

Schäfer, V M; Ballance, C J; Thirumalai, K; Stephenson, L J; Ballance, T G; Steane, A M; Lucas, D M

2018-02-28

Quantum bits (qubits) based on individual trapped atomic ions are a promising technology for building a quantum computer. The elementary operations necessary to do so have been achieved with the required precision for some error-correction schemes. However, the essential two-qubit logic gate that is used to generate quantum entanglement has hitherto always been performed in an adiabatic regime (in which the gate is slow compared with the characteristic motional frequencies of the ions in the trap), resulting in logic speeds of the order of 10 kilohertz. There have been numerous proposals of methods for performing gates faster than this natural 'speed limit' of the trap. Here we implement one such method, which uses amplitude-shaped laser pulses to drive the motion of the ions along trajectories designed so that the gate operation is insensitive to the optical phase of the pulses. This enables fast (megahertz-rate) quantum logic that is robust to fluctuations in the optical phase, which would otherwise be an important source of experimental error. We demonstrate entanglement generation for gate times as short as 480 nanoseconds-less than a single oscillation period of an ion in the trap and eight orders of magnitude shorter than the memory coherence time measured in similar calcium-43 hyperfine qubits. The power of the method is most evident at intermediate timescales, at which it yields a gate error more than ten times lower than can be attained using conventional techniques; for example, we achieve a 1.6-microsecond-duration gate with a fidelity of 99.8 per cent. Faster and higher-fidelity gates are possible at the cost of greater laser intensity. The method requires only a single amplitude-shaped pulse and one pair of beams derived from a continuous-wave laser. It offers the prospect of combining the unrivalled coherence properties, operation fidelities and optical connectivity of trapped-ion qubits with the submicrosecond logic speeds that are usually associated with solid-state devices.

Electric pulses used in electrochemotherapy and electrogene therapy do not significantly change the expression profile of genes involved in the development of cancer in malignant melanoma cells.

PubMed

Mlakar, Vid; Todorovic, Vesna; Cemazar, Maja; Glavac, Damjan; Sersa, Gregor

2009-08-26

Electroporation is a versatile method for in vitro or in vivo delivery of different molecules into cells. However, no study so far has analysed the effects of electric pulses used in electrochemotherapy (ECT pulses) or electric pulses used in electrogene therapy (EGT pulses) on malignant cells. We studied the effect of ECT and EGT pulses on human malignant melanoma cells in vitro in order to understand and predict the possible effect of electric pulses on gene expression and their possible effect on cell behaviour. We used microarrays with 2698 different oligonucleotides to obtain the expression profile of genes involved in apoptosis and cancer development in a malignant melanoma cell line (SK-MEL28) exposed to ECT pulses and EGT pulses. Cells exposed to ECT pulses showed a 68.8% average survival rate, while cells exposed to EGT pulses showed a 31.4% average survival rate. Only seven common genes were found differentially expressed in cells 16 h after exposure to ECT and EGT pulses. We found that ECT and EGT pulses induce an HSP70 stress response mechanism, repress histone protein H4, a major protein involved in chromatin assembly, and down-regulate components involved in protein synthesis. Our results show that electroporation does not significantly change the expression profile of major tumour suppressor genes or oncogenes of the cell cycle. Moreover, electroporation also does not changes the expression of genes involved in the stability of DNA, supporting current evidence that electroporation is a safe method that does not promote tumorigenesis. However, in spite of being considered an isothermal method, it does to some extent induce stress, which resulted in the expression of the environmental stress response mechanism, HSP70.

21 CFR 870.3680 - Cardiovascular permanent or temporary pacemaker electrode.

Code of Federal Regulations, 2010 CFR

2010-04-01

... applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator. (2... end connected to an implantable pacemaker pulse generator and the other end applied to the heart. The...

21 CFR 870.3680 - Cardiovascular permanent or temporary pacemaker electrode.

Code of Federal Regulations, 2013 CFR

2013-04-01

... applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator. (2... end connected to an implantable pacemaker pulse generator and the other end applied to the heart. The...

21 CFR 870.3680 - Cardiovascular permanent or temporary pacemaker electrode.

Code of Federal Regulations, 2011 CFR

2011-04-01

... applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator. (2... end connected to an implantable pacemaker pulse generator and the other end applied to the heart. The...

21 CFR 870.3680 - Cardiovascular permanent or temporary pacemaker electrode.

Code of Federal Regulations, 2012 CFR

2012-04-01

... applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator. (2... end connected to an implantable pacemaker pulse generator and the other end applied to the heart. The...

21 CFR 870.3680 - Cardiovascular permanent or temporary pacemaker electrode.

Code of Federal Regulations, 2014 CFR

2014-04-01

... applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator. (2... end connected to an implantable pacemaker pulse generator and the other end applied to the heart. The...

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

USDA-ARS?s Scientific Manuscript database

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 (...

Experiments and Computational Theory for Electrical Breakdown in Critical Components: THz Imaging of Electronic Plasmas.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zutavern, Fred J.; Hjalmarson, Harold P.; Bigman, Verle Howard

This report describes the development of ultra-short pulse laser (USPL) induced terahertz (THz) radiation to image electronic plasmas during electrical breakdown. The technique uses three pulses from two USPLs to (1) trigger the breakdown, (2) create a 2 picosecond (ps, 10 -12 s), THz pulse to illuminate the breakdown, and (3) record the THz image of the breakdown. During this three year internal research program, sub-picosecond jitter timing for the lasers, THz generation, high bandwidth (BW) diagnostics, and THz image acquisition was demonstrated. High intensity THz radiation was optically-induced in a pulse-charged gallium arsenide photoconductive switch. The radiation was collected,more » transported, concentrated, and co-propagated through an electro-optic crystal with an 800 nm USPL pulse whose polarization was rotated due to the spatially varying electric field of the THz image. The polarization modulated USPL pulse was then passed through a polarizer and the resulting spatially varying intensity was detected in a high resolution digital camera. Single shot images had a signal to noise of %7E3:1. Signal to noise was improved to %7E30:1 with several experimental techniques and by averaging the THz images from %7E4000 laser pulses internally and externally with the camera and the acquisition system (40 pulses per readout). THz shadows of metallic films and objects were also recorded with this system to demonstrate free-carrier absorption of the THz radiation and improve image contrast and resolution. These 2 ps THz pulses were created and resolved with 100 femtosecond (fs, 10 -15 s) long USPL pulses. Thus this technology has the capability to time-resolve extremely fast repetitive or single shot phenomena, such as those that occur during the initiation of electrical breakdown. The goal of imaging electrical breakdown was not reached during this three year project. However, plans to achieve this goal as part of a follow-on project are described in this document. Further modifications to improve the THz image contrast and resolution are proposed, and after they are made, images of photo-induced carriers in gallium arsenide and silicon will be acquired to evaluate image sensitivity versus carrier density. Finally electrical breakdown will be induced with the first USPL pulse, illuminated with THz radiation produced with the second USPL pulse and recorded with the third USPL pulse.« less

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

USGS Publications Warehouse

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

2003-01-01

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

Charged particle mobility refrigerant analyzer

DOEpatents

Allman, S.L.; Chunghsuan Chen; Chen, F.C.

1993-02-02

A method for analyzing a gaseous electronegative species comprises the steps of providing an analysis chamber; providing an electric field of known potential within the analysis chamber; admitting into the analysis chamber a gaseous sample containing the gaseous electronegative species; providing a pulse of free electrons within the electric field so that the pulse of free electrons interacts with the gaseous electronegative species so that a swarm of electrically charged particles is produced within the electric field; and, measuring the mobility of the electrically charged particles within the electric field.

Charged particle mobility refrigerant analyzer

DOEpatents

Allman, Steve L.; Chen, Chung-Hsuan; Chen, Fang C.

1993-01-01

A method for analyzing a gaseous electronegative species comprises the steps of providing an analysis chamber; providing an electric field of known potential within the analysis chamber; admitting into the analysis chamber a gaseous sample containing the gaseous electronegative species; providing a pulse of free electrons within the electric field so that the pulse of free electrons interacts with the gaseous electronegative species so that a swarm of electrically charged particles is produced within the electric field; and, measuring the mobility of the electrically charged particles within the electric field.

Repetitive Transcranial Magnetic Stimulator with Controllable Pulse Parameters

PubMed Central

Peterchev, Angel V; Murphy, David L; Lisanby, Sarah H

2013-01-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10–310 μs and positive/negative phase amplitude ratio of 1–56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation by up to 82% and 57%, and decreases coil heating by up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3,000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications, and could lead to clinical applications with potentially enhanced potency. PMID:21540487

High resolution time interval counter

DOEpatents

Condreva, Kenneth J.

1994-01-01

A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

High resolution time interval counter

DOEpatents

Condreva, K.J.

1994-07-26

A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

Modified Blumlein pulse-forming networks for bioelectrical applications.

PubMed

Romeo, Stefania; Sarti, Maurizio; Scarfì, Maria Rosaria; Zeni, Luigi

2010-07-01

Intense nanosecond pulsed electric fields (nsPEFs) have been shown to induce, on intracellular structures, interesting effects dependent on electrical exposure conditions (pulse length and amplitude, repetition frequency and number of pulses), which are known in the literature as "bioelectrical effects" (Schoenbach et al., IEEE Trans Plasma Sci 30:293-300, 2002). In particular, pulses with a shorter width than the plasma membrane charging time constant (about 100 ns for mammalian cells) can penetrate the cell and trigger effects such as permeabilization of intracellular membranes, release of Ca(2+) and apoptosis induction. Moreover, the observed effects have led to exploration of medical applications, like the treatment of melanoma tumors (Nuccitelli et al., Biochem Biophys Res Commun 343:351-360, 2006). Pulsed electric fields allowing such effects usually range from several tens to a few hundred nanoseconds in duration and from a few to several tens of megavolts per meter in amplitude (Schoenbach et al., IEEE Trans Diel Elec Insul 14:1088-1109, 2007); however, the biological effects of subnanosecond pulses have been also investigated (Schoenbach et al., IEEE Trans Plasma Sci 36:414-422, 2008). The use of such a large variety of pulse parameters suggests that highly flexible pulse-generating systems, able to deliver wide ranges of pulse durations and amplitudes, are strongly required in order to explore effects and applications related to different exposure conditions. The Blumlein pulse-forming network is an often-employed circuit topology for the generation of high-voltage electric pulses with fixed pulse duration. An innovative modification to the Blumlein circuit has been recently devised which allows generation of pulses with variable amplitude, duration and polarity. Two different modified Blumlein pulse-generating systems are presented in this article, the first based on a coaxial cable configuration, matching microscopic slides as a pulse-delivery system, and the other based on microstrip transmission lines and designed to match cuvettes for the exposure of cell suspensions.

Lightning Injuries

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Internal Bleeding

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Lizard Bites

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Urethral Injuries

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Rib Fractures

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Ear Injury

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Plasma-enhanced mixing and flameholding in supersonic flow

PubMed Central

Firsov, Alexander; Savelkin, Konstantin V.; Yarantsev, Dmitry A.; Leonov, Sergey B.

2015-01-01

The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure Pst=160–250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of Wpl=3–24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air–fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. PMID:26170434

DC Stark addressing for quantum memory in Tm:YAG

NASA Astrophysics Data System (ADS)

Gerasimov, Konstantin; Minnegaliev, Mansur; Urmancheev, Ravil; Moiseev, Sergey

2017-10-01

We observed a linear DC Stark effect for 3H6 - 3H4 optical transition of Tm3+ ions in Y3Al5O12. We observed that application of electric field pulse suppresses the two-pulse photon echo signal. If we then apply a second electric pulse of opposite polarity the echo signal is restored again, which indicates the linear nature of the observed effect. The effect is present despite the D2 symmetry of the Tm3+ sites that prohibits a linear Stark effect. Experimental data analysis shows that the observed electric field influence can be attributed to defects that break the local crystal field symmetry near Tm3+ ions. Using this effect we demonstrate selective retrieval of light pulses in two-pulse photon echo.

Nonfreezing Tissue Injuries

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Directed Field Ionization: A Genetic Algorithm for Evolving Electric Field Pulses

NASA Astrophysics Data System (ADS)

Kang, Xinyue; Rowley, Zoe A.; Carroll, Thomas J.; Noel, Michael W.

2017-04-01

When an ionizing electric field pulse is applied to a Rydberg atom, the electron's amplitude traverses many avoided crossings among the Stark levels as the field increases. The resulting superposition determines the shape of the time resolved field ionization spectrum at a detector. An engineered electric field pulse that sweeps back and forth through avoided crossings can control the phase evolution so as to determine the electron's path through the Stark map. In the region of n = 35 in rubidium there are hundreds of potential avoided crossings; this yields a large space of possible pulses. We use a genetic algorithm to search this space and evolve electric field pulses to direct the ionization of the Rydberg electron in rubidium. We present the algorithm along with a comparison of simulated and experimental results. This work was supported by the National Science Foundation under Grants No. 1607335 and No. 1607377 and used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number OCI-1053575.

Measurement of electroosmotic and electrophoretic velocities using pulsed and sinusoidal electric fields

PubMed Central

Sadek, Samir H.; Pimenta, Francisco; Pinho, Fernando T.

2017-01-01

In this work, we explore two methods to simultaneously measure the electroosmotic mobility in microchannels and the electrophoretic mobility of micron‐sized tracer particles. The first method is based on imposing a pulsed electric field, which allows to isolate electrophoresis and electroosmosis at the startup and shutdown of the pulse, respectively. In the second method, a sinusoidal electric field is generated and the mobilities are found by minimizing the difference between the measured velocity of tracer particles and the velocity computed from an analytical expression. Both methods produced consistent results using polydimethylsiloxane microchannels and polystyrene micro‐particles, provided that the temporal resolution of the particle tracking velocimetry technique used to compute the velocity of the tracer particles is fast enough to resolve the diffusion time‐scale based on the characteristic channel length scale. Additionally, we present results with the pulse method for viscoelastic fluids, which show a more complex transient response with significant velocity overshoots and undershoots after the start and the end of the applied electric pulse, respectively. PMID:27990654

Electric fence standards comport with human data and AC limits.

PubMed

Kroll, Mark W; Perkins, Peter E; Panescu, Dorin

2015-08-01

The ubiquitous electric fence is essential to modern agriculture and has saved lives by reducing the number of livestock automobile collisions. Modern safety standards such as IEC 60335-2-76 and UL 69 have played a role in this positive result. However, these standards are essentially based on energy and power (RMS current), which have limited direct relationship to cardiac effects. We compared these standards to bioelectrically more relevant units of charge and average current in view of recent work on VF (ventricular fibrillation) induction and to existing IEC AC current limits. There are 3 limits for normal (low) pulsing rate: IEC energy limit, IEC current limit, and UL current limit. We then calculated the delivered charge allowed for each pulse duration for these limits and then compared them to a charge-based safety model derived from published human ventricular-fibrillation induction data. Both the IEC and UL also allow for rapid pulsing for up to 3 minutes. We calculated maximum outputs for various pulse durations assuming pulsing at 10, 20, and 30 pulses per second. These were then compared to standard utility power safety (AC) limits via the conversion factor of 7.4 to convert average current to RMS current for VF risk. The outputs of TASER electrical weapons (typically < 100 μC and ~100 μs duration) were also compared. The IEC and UL electric fence energizer normal rate standards are conservative in comparison with actual human laboratory experiments. The IEC and UL electric fence energizer rapid-pulsing standards are consistent with accepted IEC AC current limits for commercially used pulse durations.

Ion heating and characteristics of ST plasma used by double-pulsing CHI on HIST

NASA Astrophysics Data System (ADS)

Hanao, Takafumi; Hirono, Hidetoshi; Hyobu, Takahiro; Ito, Kengo; Matsumoto, Keisuke; Nakayama, Takashi; Oki, Nobuharu; Kikuchi, Yusuke; Fukumoto, Naoyuki; Nagata, Masayoshi

2013-10-01

Multi-pulsing Coaxial Helicity Injection (M-CHI) is an efficient current drive and sustainment method used in spheromak and spherical torus (ST). We have observed plasma current/flux amplification by double pulsing CHI. Poloidal ion temperature measured by Ion Doppler Spectrometer (IDS) has a peak at plasma core region. In this region, radial electric field has a negative peak. At more inboard side that is called separatrix between closed flux region and inner open flux region, poloidal flow has a large shear and radial electric field changes the polarity. After the second CHI pulse, we observed sharp and rapid ion heating at plasma core region and separatrix. In this region, the poloidal ion temperature is selective heating because electron temperature is almost uniform. At this time, flow shear become larger and radial electric field is amplified at separatorix. These effects produce direct heating of ion through the viscous flow damping. Furthermore, we observed decrease of electron density at separatrix. Decreased density makes Hall dynamo electric field as two-fluid effect. When the ion temperature is increasing, dynamo electric field is observed at separatrix. It may have influence with the ion heating. We will discuss characteristic of double pulsing CHI driven ST plasmas and correlation of direct heating of ion with dynamo electric field and any other parameters.

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

NASA Astrophysics Data System (ADS)

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

2015-11-01

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

Overview of Head Injuries

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

Cerebral Contusions and Lacerations

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

A double-pulse approach for electrotransfection.

PubMed

Pasquet, L; Bellard, E; Golzio, M; Rols, M P; Teissie, J

2014-12-01

Gene transfer and expression can be obtained by delivering calibrated electric pulses on cells in the presence of plasmids coding for the activity of interest. The electric treatment affects the plasma membrane and induces the formation of a transient complex between nucleic acids and the plasma membrane. It results in a delivery of the plasmid in the cytoplasm. Expression is only obtained if the plasmid is translocated inside the nucleus. This is a key limit in the process. We previously showed that delivery of a high-field short-duration electric pulse was inducing a structural alteration of the nuclear envelope. This study investigates if the double-pulse approach (first pulse to transfer the plasmid to the cytoplasm, and second pulse to induce the structural alteration of the envelope) was a way to enhance the protein expression using the green fluorescent protein as a reporter. We observed that not only the double-pulse approach induced the transfection of a lower number of cells but moreover, these transfected cells were less fluorescent than the cells treated only with the first pulse.

High precision electric gate for time-of-flight ion mass spectrometers

NASA Technical Reports Server (NTRS)

Sittler, Edward C. (Inventor)

2011-01-01

A time-of-flight mass spectrometer having a chamber with electrodes to generate an electric field in the chamber and electric gating for allowing ions with a predetermined mass and velocity into the electric field. The design uses a row of very thin parallel aligned wires that are pulsed in sequence so the ion can pass through the gap of two parallel plates, which are biased to prevent passage of the ion. This design by itself can provide a high mass resolution capability and a very precise start pulse for an ion mass spectrometer. Furthermore, the ion will only pass through the chamber if it is within a wire diameter of the first wire when it is pulsed and has the right speed so it is near all other wires when they are pulsed.

Spark gaps synchronization using electrical trigger pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agarwal, Ritu; Saroj, P.C.; Sharma, Archana

In pulse power systems, it is required to have synchronized triggering of two or more high voltage spark gaps capable of switching large currents, using electrical trigger pulses. This paper intends to study the synchronization of spark gaps using electrical trigger. The trigger generator consists of dc supply, IGBT switch and driver circuit which generates 8kV, 400ns (FWHM) pulses. The experiment was carried out using two 0.15uF/50kV energy storage capacitors charged to 12kV and discharged through stainless steel spark gaps of diameter 9 mm across 10 ohm non inductive load. The initial experiment shows that synchronization has been achieved withmore » jitter of 50 to 100ns. Further studies carried out to reduce the jitter time by varying various electrical parameters will be presented. (author)« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, Rita Ann; Frickey, Steven Jay

2016-01-01

The mission of DOE’s Office of Electricity Delivery and Energy Reliability (OE) is to lead national efforts to modernize the electricity delivery system, enhance the security and reliability of America’s energy infrastructure and facilitate recovery from disruptions to the energy supply. One of the threats OE is concerned about is a high-altitude electro-magnetic pulse (HEMP) from a nuclear explosion and eletro-magnetic pulse (EMP) or E1 pulse can be generated by EMP weapons. DOE-OE provides federal leadership and technical guidance in addressing electric grid issues. The Idaho National Laboratory (INL) was chosen to conduct the EMP study for DOE-OE due tomore » 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.« less

Liquid Dielectrics in an Inhomogeneous Pulsed Electric Field

NASA Astrophysics Data System (ADS)

Shneider, M. N.; Pekker, M.

2016-08-01

This book comprehensively describes the phenomena that occur in liquid dielectrics under the influence of an inhomogeneous pulsed electric field. Written by leading experts in the field, it is the first of its kind to address numerous potential applications such as the technology of high-voltage insulation in pulsed inhomogeneous fields, and applications related to cavitation development in liquid dielectrics, plasma treatment of different materials and plasma medicine dealing with living cells. Liquid Dielectrics in an Inhomogeneous Pulsed Electric Field is intended for a broad audience, from students to engineers and scientists, who are interested in current research questions in electrodynamics and hydrodynamics of liquid dielectrics. Part of the IOP Plasma Physics Series

Personnel electronic neutron dosimeter

DOEpatents

Falk, R.B.; Tyree, W.H.

1982-03-03

A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

Personnel electronic neutron dosimeter

DOEpatents

Falk, Roger B.; Tyree, William H.

1984-12-18

A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

Fractures of the Jaw and Midface

MedlinePlus

... Prevent Falls (News) A Dangerous New Twist on Cyberbullying (News) Electrical Pulses May Ease Pain From 'Slipped' ... Falls News HealthDay A Dangerous New Twist on Cyberbullying News HealthDay Electrical Pulses May Ease Pain From ' ...

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

DTIC Science & Technology

2014-01-30

AFRL-AFOSR-UK-TR-2014-0040 Guiding of long-distance electric discharges by combined femtosecond and nanosecond pulses emitted by...To) 27 September 2010 – 31 December 2013 4. TITLE AND SUBTITLE Guiding of long-distance electric discharges by combined femtosecond and...plasma channels in the atmosphere and laser guiding of high-voltage electric discharges . 15. SUBJECT TERMS EOARD, triggering

Potential of M-Wave Elicited by Double Pulse for Muscle Fatigue Evaluation in Intermittent Muscle Activation by Functional Electrical Stimulation for Motor Rehabilitation

PubMed Central

Miura, Naoto; Watanabe, Takashi

2016-01-01

Clinical studies on application of functional electrical stimulation (FES) to motor rehabilitation have been increasing. However, muscle fatigue appears early in the course of repetitive movement production training by FES. Although M-wave variables were suggested to be reliable indices of muscle fatigue in long lasting constant electrical stimulation under the isometric condition, the ability of M-wave needs more studies under intermittent stimulation condition, because the intervals between electrical stimulations help recovery of muscle activation level. In this paper, M-waves elicited by double pulses were examined in muscle fatigue evaluation during repetitive movements considering rehabilitation training with surface electrical stimulation. M-waves were measured under the two conditions of repetitive stimulation: knee extension force production under the isometric condition and the dynamic movement condition by knee joint angle control. Amplitude of M-wave elicited by the 2nd pulse of a double pulse decreased during muscle fatigue in both measurement conditions, while the change in M-waves elicited by single pulses in a stimulation burst was not relevant to muscle fatigue in repeated activation with stimulation interval of 1 s. Fatigue index obtained from M-waves elicited by 2nd pulses was suggested to provide good estimation of muscle fatigue during repetitive movements with FES. PMID:27110556

Nondestructive acoustic electric field probe apparatus and method

DOEpatents

Migliori, Albert

1982-01-01

The disclosure relates to a nondestructive acoustic electric field probe and its method of use. A source of acoustic pulses of arbitrary but selected shape is placed in an oil bath along with material to be tested across which a voltage is disposed and means for receiving acoustic pulses after they have passed through the material. The received pulses are compared with voltage changes across the material occurring while acoustic pulses pass through it and analysis is made thereof to determine preselected characteristics of the material.

Comparison of the efficacy of a custom-made pulse oximeter probe with digital electric pulp tester, cold spray, and rubber cup for assessing pulp vitality.

PubMed

Dastmalchi, Nafiseh; Jafarzadeh, Hamid; Moradi, Saeed

2012-09-01

The ideal technique for the evaluation of pulp vitality should be noninvasive, painless, objective, reliable, and reproducible. To achieve this, the most routine tests are sensitivity tests. However, a major shortcoming with these tests is that they indirectly indicate pulp vitality by measuring a neural response. Pulse oximetry is a well-established oxygen saturation monitoring technique broadly used in medicine. However, its efficacy as the pulp vitality test should be evaluated. The aim of this study was to design and build a custom-made pulse oximeter dental probe and to evaluate its efficacy in comparison with electric pulp tester, cold spray, and a rubber cup in pulp vitality testing. Twenty-four single-canal mandibular premolars needing endodontic treatment were selected. The patients did not have systemic disease and did not consume drugs. Also, they had no clinically relevant signs of necrosis. The selected teeth were pulpally tested with 4 kinds of tests including pulse oximetry, the electric test, cold spray, and the rubber cup. After endodontic treatment of these teeth, which revealed the actual status of the pulp, the results were analyzed by the kappa test to show the efficacy of these tests. When comparing electric, cold, heat, and pulse oximeter tests with the gold standard, the kappa agreement coefficient was 18%, 18%, 14%, and 91%, respectively. The sensitivity of pulse oximetry, a rubber cup, electric test, and cold spray was 0.93, 0.60, 0.60, and 0.53, respectively. The specificity of these tests was 1.00, 0.55, 0.22, and 0.66, respectively. Pulp testing by using pulse oximetry is more reliable than the electric test, rubber cup, and cold spray. The custom-made pulse oximeter dental probe is an effective and objective method for pulp vitality assessment. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

NASA Astrophysics Data System (ADS)

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

2015-05-01

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

The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walsh, D. A., E-mail: david.walsh@stfc.ac.uk; Snedden, E. W.; Jamison, S. P.

The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immunemore » to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.« less

A Dielectric Rod Antenna for Picosecond Pulse Stimulation of Neurological Tissue

PubMed Central

Petrella, Ross A.; Schoenbach, Karl H.; Xiao, Shu

2016-01-01

A dielectrically loaded wideband rod antenna has been studied as a pulse delivery system to subcutaneous tissues. Simulation results applying 100 ps electrical pulse show that it allows us to generate critical electric field for biological effects, such as brain stimulation, in the range of several centimeters. In order to reach the critical electric field for biological effects, which is approximately 20 kV/cm, at a depth of 2 cm, the input voltage needs to be 175 kV. The electric field spot size in the brain at this position is approximately 1 cm2. Experimental studies in free space with a conical antenna (part of the antenna system) with aluminum nitride as the dielectric have confirmed the accuracy of the simulation. These results set the foundation for high voltage in situ experiments on the complete antenna system and the delivery of pulses to biological tissue. PMID:27563160

Characterization of carbon fiber polymer matrix composites subjected to simultaneous application of electric current pulse and low velocity impact

NASA Astrophysics Data System (ADS)

Hart, Robert James

2011-12-01

The use of composite materials in aerospace, electronics, and wind industries has become increasingly common, and these composite components are required to carry mechanical, electrical, and thermal loads simultaneously. A unique property of carbon fiber composites is that when an electric current is applied to the specimen, the mechanical strength of the specimen increases. Previous studies have shown that the higher the electric current, the greater the increase in impact strength. However, as current passes through the composite, heat is generated through Joule heating. This Joule heating can cause degradation of the composite and thus a loss in strength. In order to minimize the negative effects of heating, it is desired to apply a very high current for a very short duration of time. This thesis investigated the material responses of carbon fiber composite plates subjected to electrical current pulse loads of up to 1700 Amps. For 32 ply unidirectional IM7/977-3 specimens, the peak impact load and absorbed energy increased slightly with the addition of a current pulse at the time of an impact event. In 16 ply cross-ply IM7/977-2 specimens, the addition of the current pulse caused detrimental effects due to electrical arcing at the interface between the composite and electrodes. Further refinement of the experimental setup should minimize the risk of electrical arcing and should better elucidate the effects of a current pulse on the impact strength of the specimens.

100 GHz pulse waveform measurement based on electro-optic sampling

NASA Astrophysics Data System (ADS)

Feng, Zhigang; Zhao, Kejia; Yang, Zhijun; Miao, Jingyuan; Chen, He

2018-05-01

We present an ultrafast pulse waveform measurement system based on an electro-optic sampling technique at 1560 nm and prepare LiTaO3-based electro-optic modulators with a coplanar waveguide structure. The transmission and reflection characteristics of electrical pulses on a coplanar waveguide terminated with an open circuit and a resistor are investigated by analyzing the corresponding time-domain pulse waveforms. We measure the output electrical pulse waveform of a 100 GHz photodiode and the obtained rise times of the impulse and step responses are 2.5 and 3.4 ps, respectively.

Sub-5-ps optical pulse generation from a 1.55-µm distributed-feedback laser diode with nanosecond electric pulse excitation and spectral filtering.

PubMed

Chen, Shaoqiang; Sato, Aya; Ito, Takashi; Yoshita, Masahiro; Akiyama, Hidefumi; Yokoyama, Hiroyuki

2012-10-22

This paper reports generation of sub-5-ps Fourier-transform limited optical pulses from a 1.55-µm gain-switched single-mode distributed-feedback laser diode via nanosecond electric excitation and a simple spectral-filtering technique. Typical damped oscillations of the whole lasing spectrum were observed in the time-resolved waveform. Through a spectral-filtering technique, the initial relaxation oscillation pulse and the following components in the output pulse can be well separated, and the initial short pulse can be selectively extracted by filtering out the short-wavelength components in the spectrum. Short pulses generated by this simple method are expected to have wide potential applications comparable to mode-locking lasers.

Feasibility of Interfacing a Microcomputer with a Multichannel Analyzer to Perform Gamma Ray Spectroscopy.

DTIC Science & Technology

1981-03-01

David Hardin. Many members and students of the Electrical Engineering department helped as I was assembling and testing hardware, but I wish to...in a detector and produce electrical pulses with amplitude proportional to the energy of the gamma ray absorbed. The electrical pulses are amplified...accomplished : t ges. First, the electrical outputs available Cron the 6 multichannel analyzer were determined. Then, a microcomputer was selected from those

The evolutionary development of high specific impulse electric thruster technology

NASA Technical Reports Server (NTRS)

Sovey, James S.; Hamley, John A.; Patterson, Michael J.; Rawlin, Vincent K.; Myers, Roger M.

1992-01-01

Electric propulsion flight and technology demonstrations conducted in the USA, Europe, Japan, China, and USSR are reviewed with reference to the major flight qualified electric propulsion systems. These include resistojets, ion thrusters, ablative pulsed plasma thrusters, stationary plasma thrusters, pulsed magnetoplasmic thrusters, and arcjets. Evolutionary mission applications are presented for high specific impulse electric thruster systems. The current status of arcjet, ion, and magnetoplasmadynamic thrusters and their associated power processor technologies are summarized.

Electric pulses used in electrochemotherapy and electrogene therapy do not significantly change the expression profile of genes involved in the development of cancer in malignant melanoma cells

PubMed Central

2009-01-01

Background Electroporation is a versatile method for in vitro or in vivo delivery of different molecules into cells. However, no study so far has analysed the effects of electric pulses used in electrochemotherapy (ECT pulses) or electric pulses used in electrogene therapy (EGT pulses) on malignant cells. We studied the effect of ECT and EGT pulses on human malignant melanoma cells in vitro in order to understand and predict the possible effect of electric pulses on gene expression and their possible effect on cell behaviour. Methods We used microarrays with 2698 different oligonucleotides to obtain the expression profile of genes involved in apoptosis and cancer development in a malignant melanoma cell line (SK-MEL28) exposed to ECT pulses and EGT pulses. Results Cells exposed to ECT pulses showed a 68.8% average survival rate, while cells exposed to EGT pulses showed a 31.4% average survival rate. Only seven common genes were found differentially expressed in cells 16 h after exposure to ECT and EGT pulses. We found that ECT and EGT pulses induce an HSP70 stress response mechanism, repress histone protein H4, a major protein involved in chromatin assembly, and down-regulate components involved in protein synthesis. Conclusion Our results show that electroporation does not significantly change the expression profile of major tumour suppressor genes or oncogenes of the cell cycle. Moreover, electroporation also does not changes the expression of genes involved in the stability of DNA, supporting current evidence that electroporation is a safe method that does not promote tumorigenesis. However, in spite of being considered an isothermal method, it does to some extent induce stress, which resulted in the expression of the environmental stress response mechanism, HSP70. PMID:19709437

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

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

Predicting non-isometric fatigue induced by electrical stimulation pulse trains as a function of pulse duration

PubMed Central

2013-01-01

Background Our previous model of the non-isometric muscle fatigue that occurs during repetitive functional electrical stimulation included models of force, motion, and fatigue and accounted for applied load but not stimulation pulse duration. Our objectives were to: 1) further develop, 2) validate, and 3) present outcome measures for a non-isometric fatigue model that can predict the effect of a range of pulse durations on muscle fatigue. Methods A computer-controlled stimulator sent electrical pulses to electrodes on the thighs of 25 able-bodied human subjects. Isometric and non-isometric non-fatiguing and fatiguing knee torques and/or angles were measured. Pulse duration (170–600 μs) was the independent variable. Measurements were divided into parameter identification and model validation subsets. Results The fatigue model was simplified by removing two of three non-isometric parameters. The third remained a function of other model parameters. Between 66% and 77% of the variability in the angle measurements was explained by the new model. Conclusion Muscle fatigue in response to different stimulation pulse durations can be predicted during non-isometric repetitive contractions. PMID:23374142

A New Concept for Non-Volatile Memory: The Electric-Pulse Induced Resistive Change Effect in Colossal Magnetoresistive Thin Films

NASA Technical Reports Server (NTRS)

Liu, S. Q.; Wu, N. J.; Ignatiev, A.

2001-01-01

A novel electric pulse-induced resistive change (EPIR) effect has been found in thin film colossal magnetoresistive (CMR) materials, and has shown promise for the development of resistive, nonvolatile memory. The EPIR effect is induced by the application of low voltage (< 4 V) and short duration (< 20 ns) electrical pulses across a thin film sample of a CMR material at room temperature and under no applied magnetic field. The pulse can directly either increase or decrease the resistance of the thin film sample depending on pulse polarity. The sample resistance change has been shown to be over two orders of magnitude, and is nonvolatile after pulsing. The sample resistance can also be changed through multiple levels - as many as 50 have been shown. Such a device can provide a way for the development of a new kind of nonvolatile multiple-valued memory with high density, fast write/read speed, low power-consumption, and potential high radiation-hardness.

Pulsed electric fields for pasteurization: defining processing conditions

USDA-ARS?s Scientific Manuscript database

Application of pulsed electric fields (PEF) technology in food pasteurization has been extensively studied. Optimal PEF treatment conditions for maximum microbial inactivation depend on multiple factors including PEF processing conditions, production parameters and product properties. In order for...

High-speed pulse-shape generator, pulse multiplexer

DOEpatents

Burkhart, Scott C.

2002-01-01

The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

NEXUS Scalable and Distributed Next-Generation Avionics Bus for Space Missions

NASA Technical Reports Server (NTRS)

He, Yutao; Shalom, Eddy; Chau, Savio N.; Some, Raphael R.; Bolotin, Gary S.

2011-01-01

A paper discusses NEXUS, a common, next-generation avionics interconnect that is transparently compatible with wired, fiber-optic, and RF physical layers; provides a flexible, scalable, packet switched topology; is fault-tolerant with sub-microsecond detection/recovery latency; has scalable bandwidth from 1 Kbps to 10 Gbps; has guaranteed real-time determinism with sub-microsecond latency/jitter; has built-in testability; features low power consumption (< 100 mW per Gbps); is lightweight with about a 5,000-logic-gate footprint; and is implemented in a small Bus Interface Unit (BIU) with reconfigurable back-end providing interface to legacy subsystems. NEXUS enhances a commercial interconnect standard, Serial RapidIO, to meet avionics interconnect requirements without breaking the standard. This unified interconnect technology can be used to meet performance, power, size, and reliability requirements of all ranges of equipment, sensors, and actuators at chip-to-chip, board-to-board, or box-to-box boundary. Early results from in-house modeling activity of Serial RapidIO using VisualSim indicate that the use of a switched, high-performance avionics network will provide a quantum leap in spacecraft onboard science and autonomy capability for science and exploration missions.

ELECTRIC PULSE GENERATOR

DOEpatents

Buntenbach, R.W.

1959-06-01

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

Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

NASA Astrophysics Data System (ADS)

Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf, Marc

2017-01-01

Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning.

Effects of duration of electric pulse on in vitro development of cloned cat embryos with human artificial chromosome vector.

PubMed

Do, Ltk; Wittayarat, M; Terazono, T; Sato, Y; Taniguchi, M; Tanihara, F; Takemoto, T; Kazuki, Y; Kazuki, K; Oshimura, M; Otoi, T

2016-12-01

The current applications for cat cloning include production of models for the study of human and animal diseases. This study was conducted to investigate the optimal fusion protocol on in vitro development of transgenic cloned cat embryos by comparing duration of electric pulse. Cat fibroblast cells containing a human artificial chromosome (HAC) vector were used as genetically modified nuclear donor cells. Couplets were fused and activated simultaneously with a single DC pulse of 3.0 kV/cm for either 30 or 60 μs. Low rates of fusion and embryo development to the blastocyst stage were observed in the reconstructed HAC-transchromosomic embryos, when the duration of fusion was prolonged to 60 μs. In contrast, the prolongation of electric pulse duration improved the embryo development and quality in the reconstructed control embryos without HAC vector. Our results suggested that the optimal parameters of electric pulses for fusion in cat somatic cell nuclear transfer vary among the types used for donor cells. © 2016 Blackwell Verlag GmbH.

Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

PubMed Central

Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf , Marc

2017-01-01

Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning. PMID:28053312

Overvoltage effect on electrical discharge type in medium-conductivity water in inhomogeneous pulsed electric field

NASA Astrophysics Data System (ADS)

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

2018-01-01

The transition between thermal and streamer discharges has been observed experimentally in water solution with conductivity 100 μS/cm applying positive voltage pulses to pin-to-rod electrodes. The transition happens at five-fold pulse amplitude. Considering streamer propagation as an ionization wave helped to establish relation between the parameters governing transition from one to another discharge mechanism.

Attosecond electronic recollision as field detector

NASA Astrophysics Data System (ADS)

Carpeggiani, P. A.; Reduzzi, M.; Comby, A.; Ahmadi, H.; Kühn, S.; Frassetto, F.; Poletto, L.; Hoff, D.; Ullrich, J.; Schröter, C. D.; Moshammer, R.; Paulus, G. G.; Sansone, G.

2018-05-01

We demonstrate the complete reconstruction of the electric field of visible–infrared pulses with energy as low as a few tens of nanojoules. The technique allows for the reconstruction of the instantaneous electric field vector direction and magnitude, thus giving access to the characterization of pulses with an arbitrary time-dependent polarization state. The technique combines extreme ultraviolet interferometry with the generation of isolated attosecond pulses.

Precision measurement of electric organ discharge timing from freely moving weakly electric fish.

PubMed

Jun, James J; Longtin, André; Maler, Leonard

2012-04-01

Physiological measurements from an unrestrained, untethered, and freely moving animal permit analyses of neural states correlated to naturalistic behaviors of interest. Precise and reliable remote measurements remain technically challenging due to animal movement, which perturbs the relative geometries between the animal and sensors. Pulse-type electric fish generate a train of discrete and stereotyped electric organ discharges (EOD) to sense their surroundings actively, and rapid modulation of the discharge rate occurs while free swimming in Gymnotus sp. The modulation of EOD rates is a useful indicator of the fish's central state such as resting, alertness, and learning associated with exploration. However, the EOD pulse waveforms remotely observed at a pair of dipole electrodes continuously vary as the fish swims relative to the electrodes, which biases the judgment of the actual pulse timing. To measure the EOD pulse timing more accurately, reliably, and noninvasively from a free-swimming fish, we propose a novel method based on the principles of waveform reshaping and spatial averaging. Our method is implemented using envelope extraction and multichannel summation, which is more precise and reliable compared with other widely used threshold- or peak-based methods according to the tests performed under various source-detector geometries. Using the same method, we constructed a real-time electronic pulse detector performing an additional online pulse discrimination routine to enhance further the detection reliability. Our stand-alone pulse detector performed with high temporal precision (<10 μs) and reliability (error <1 per 10(6) pulses) and permits longer recording duration by storing only event time stamps (4 bytes/pulse).

Inactivation of Escherichia coli, Saccharomyces cerevisiae, and Lactobacillus brevis in Low-fat Milk by Pulsed Electric Field Treatment: A Pilot-scale Study

PubMed Central

Han, Bok Kung; Choi, Hyuk Joon; Kang, Shin Ho; Baick, Seung Chun

2015-01-01

We investigated the effects of a pulsed electric field (PEF) treatment on microbial inactivation and the physical properties of low-fat milk. Milk inoculated with Escherichia coli, Saccharomyces cerevisiae, or Lactobacillus brevis was supplied to a pilot-scale PEF treatment system at a flow rate of 30 L/h. Pulses with an electric field strength of 10 kV/cm and a pulse width of 30 μs were applied to the milk with total pulse energies of 50-250 kJ/L achieved by varying the pulse frequency. The inactivation curves of the test microorganisms were biphasic with an initial lag phase (or shoulder) followed by a phase of rapid inactivation. PEF treatments with a total pulse energy of 200 kJ/L resulted in a 4.5-log reduction in E. coli, a 4.4-log reduction in L. brevis, and a 6.0-log reduction in S. cerevisiae. Total pulse energies of 200 and 250 kJ/L resulted in greater than 5-log reductions in microbial counts in stored PEF-treated milk, and the growth of surviving microorganisms was slow during storage for 15 d at 4℃. PEF treatment did not change milk physical properties such as pH, color, or particle-size distribution (p<0.05). These results indicate that a relatively low electric-field strength of 10 kV/cm can be used to pasteurize low-fat milk. PMID:26877640

Inactivation of Escherichia coli, Saccharomyces cerevisiae, and Lactobacillus brevis in Low-fat Milk by Pulsed Electric Field Treatment: A Pilot-scale Study.

PubMed

Lee, Gun Joon; Han, Bok Kung; Choi, Hyuk Joon; Kang, Shin Ho; Baick, Seung Chun; Lee, Dong-Un

2015-01-01

We investigated the effects of a pulsed electric field (PEF) treatment on microbial inactivation and the physical properties of low-fat milk. Milk inoculated with Escherichia coli, Saccharomyces cerevisiae, or Lactobacillus brevis was supplied to a pilot-scale PEF treatment system at a flow rate of 30 L/h. Pulses with an electric field strength of 10 kV/cm and a pulse width of 30 μs were applied to the milk with total pulse energies of 50-250 kJ/L achieved by varying the pulse frequency. The inactivation curves of the test microorganisms were biphasic with an initial lag phase (or shoulder) followed by a phase of rapid inactivation. PEF treatments with a total pulse energy of 200 kJ/L resulted in a 4.5-log reduction in E. coli, a 4.4-log reduction in L. brevis, and a 6.0-log reduction in S. cerevisiae. Total pulse energies of 200 and 250 kJ/L resulted in greater than 5-log reductions in microbial counts in stored PEF-treated milk, and the growth of surviving microorganisms was slow during storage for 15 d at 4℃. PEF treatment did not change milk physical properties such as pH, color, or particle-size distribution (p<0.05). These results indicate that a relatively low electric-field strength of 10 kV/cm can be used to pasteurize low-fat milk.

Microsecond-scale electric field pulses in cloud lightning discharges

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

3D noninvasive ultrasound Joule heat tomography based on acousto-electric effect using unipolar pulses: a simulation study

PubMed Central

Yang, Renhuan; Li, Xu; Song, Aiguo; He, Bin; Yan, Ruqiang

2012-01-01

Electrical properties of biological tissues are highly sensitive to their physiological and pathological status. Thus it is of importance to image electrical properties of biological tissues. However, spatial resolution of conventional electrical impedance tomography (EIT) is generally poor. Recently, hybrid imaging modalities combining electric conductivity contrast and ultrasonic resolution based on acouto-electric effect has attracted considerable attention. In this study, we propose a novel three-dimensional (3D) noninvasive ultrasound Joule heat tomography (UJHT) approach based on acouto-electric effect using unipolar ultrasound pulses. As the Joule heat density distribution is highly dependent on the conductivity distribution, an accurate and high resolution mapping of the Joule heat density distribution is expected to give important information that is closely related to the conductivity contrast. The advantages of the proposed ultrasound Joule heat tomography using unipolar pulses include its simple inverse solution, better performance than UJHT using common bipolar pulses and its independence of any priori knowledge of the conductivity distribution of the imaging object. Computer simulation results show that using the proposed method, it is feasible to perform a high spatial resolution Joule heat imaging in an inhomogeneous conductive media. Application of this technique on tumor scanning is also investigated by a series of computer simulations. PMID:23123757

Endovascular Electrodes for Electrical Stimulation of Blood Vessels for Vasoconstriction - a Finite Element Simulation Study

NASA Astrophysics Data System (ADS)

Kezurer, Noa; Farah, Nairouz; Mandel, Yossi

2016-08-01

Hemorrhagic shock accounts for 30-40 percent of trauma mortality, as bleeding may sometimes be hard to control. Application of short electrical pulses on blood vessels was recently shown to elicit robust vasoconstriction and reduction of blood loss following vascular injury. In this study we present a novel approach for vasoconstriction based on endovascular application of electrical pulses for situations where access to the vessel is limited. In addition to ease of access, we hypothesize that this novel approach will result in a localized and efficient vasoconstriction. Using computer modeling (COMSOL Multiphysics, Electric Currents Module), we studied the effect of endovascular pulsed electrical treatment on abdominal aorta of pigs, and compared the efficiency of different electrodes configurations on the electric field amplitude, homogeneity and locality when applied on a blood vessel wall. Results reveal that the optimal configuration is the endovascular approach where four electrodes are used, spaced 13 mm apart. Furthermore, computer based temperature investigations (bio-heat model, COMSOL Multiphysics) show that the maximum expected temperature rise is of 1.2 degrees; highlighting the safety of the four endovascular electrodes configuration. These results can aid in planning the application of endovascular pulsed electrical treatment as an efficient and safe vasoconstriction approach.

Endovascular Electrodes for Electrical Stimulation of Blood Vessels for Vasoconstriction – a Finite Element Simulation Study

PubMed Central

Kezurer, Noa; Farah, Nairouz; Mandel, Yossi

2016-01-01

Hemorrhagic shock accounts for 30–40 percent of trauma mortality, as bleeding may sometimes be hard to control. Application of short electrical pulses on blood vessels was recently shown to elicit robust vasoconstriction and reduction of blood loss following vascular injury. In this study we present a novel approach for vasoconstriction based on endovascular application of electrical pulses for situations where access to the vessel is limited. In addition to ease of access, we hypothesize that this novel approach will result in a localized and efficient vasoconstriction. Using computer modeling (COMSOL Multiphysics, Electric Currents Module), we studied the effect of endovascular pulsed electrical treatment on abdominal aorta of pigs, and compared the efficiency of different electrodes configurations on the electric field amplitude, homogeneity and locality when applied on a blood vessel wall. Results reveal that the optimal configuration is the endovascular approach where four electrodes are used, spaced 13 mm apart. Furthermore, computer based temperature investigations (bio-heat model, COMSOL Multiphysics) show that the maximum expected temperature rise is of 1.2 degrees; highlighting the safety of the four endovascular electrodes configuration. These results can aid in planning the application of endovascular pulsed electrical treatment as an efficient and safe vasoconstriction approach. PMID:27534438

Two-dimensional nanosecond electric field mapping based on cell electropermeabilization.

PubMed

Chen, Meng-Tse; Jiang, Chunqi; Vernier, P Thomas; Wu, Yu-Hsuan; Gundersen, Martin A

2009-11-11

Nanosecond, megavolt-per-meter electric pulses cause permeabilization of cells to small molecules, programmed cell death (apoptosis) in tumor cells, and are under evaluation as a treatment for skin cancer. We use nanoelectroporation and fluorescence imaging to construct two-dimensional maps of the electric field associated with delivery of 15 ns, 10 kV pulses to monolayers of the human prostate cancer cell line PC3 from three different electrode configurations: single-needle, five-needle, and flat-cut coaxial cable. Influx of the normally impermeant fluorescent dye YO-PRO-1 serves as a sensitive indicator of membrane permeabilization. The level of fluorescence emission after pulse exposure is proportional to the applied electric field strength. Spatial electric field distributions were compared in a plane normal to the center axis and 15-20 mum from the tip of the center electrode. Measurement results agree well with models for the three electrode arrangements evaluated in this study. This live-cell method for measuring a nanosecond pulsed electric field distribution provides an operationally meaningful calibration of electrode designs for biological applications and permits visualization of the relative sensitivities of different cell types to nanoelectropulse stimulation. PACS Codes: 87.85.M-

Biomedical ultrasonoscope

NASA Technical Reports Server (NTRS)

Lee, R. D. (Inventor)

1979-01-01

The combination of a "C" mode scan electronics in a portable, battery powered biomedical ultrasonoscope having "A" and "M" mode scan electronics, the latter including a clock generator for generating clock pulses, a cathode ray tube having X, Y and Z axis inputs, a sweep generator connected between the clock generator and the X axis input of the cathode ray tube for generating a cathode ray sweep signal synchronized by the clock pulses, and a receiver adapted to be connected to the Z axis input of the cathode ray tube. The "C" mode scan electronics comprises a plurality of transducer elements arranged in a row and adapted to be positioned on the skin of the patient's body for converting a pulsed electrical signal to a pulsed ultrasonic signal, radiating the ultrasonic signal into the patient's body, picking up the echoes reflected from interfaces in the patient's body and converting the echoes to electrical signals; a plurality of transmitters, each transmitter being coupled to a respective transducer for transmitting a pulsed electrical signal thereto and for transmitting the converted electrical echo signals directly to the receiver, a sequencer connected between the clock generator and the plurality of transmitters and responsive to the clock pulses for firing the transmitters in cyclic order; and a staircase voltage generator connected between the clock generator and the Y axis input of the cathode ray tube for generating a staircase voltage having steps synchronized by the clock pulses.

Acoustic microscope surface inspection system and method

DOEpatents

Khuri-Yakub, Butrus T.; Parent, Philippe; Reinholdtsen, Paul A.

1991-01-01

An acoustic microscope surface inspection system and method in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respected to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations.

Experimental characterization of intrapulse tissue conductivity changes for electroporation.

PubMed

Neal, Robert E; Garcia, Paulo A; Robertson, John L; Davalos, Rafael V

2011-01-01

Cells exposed to short electric pulses experience a change in their transmembrane potential, which can lead to increased membrane permeability of the cell. When the energy of the pulses surpasses a threshold, the cell dies in a non-thermal manner known as irreversible electroporation (IRE). IRE has shown promise in the focal ablation of pathologic tissues. Its non-thermal mechanism spares sensitive structures and facilitates rapid lesion resolution. IRE effects depend on the electric field distribution, which can be predicted with numerical modeling. When the cells become permeabilized, the bulk tissue properties change, affecting this distribution. For IRE to become a reliable and successful treatment of diseased tissues, robust predictive treatment planning methods must be developed. It is vital to understand the changes in tissue properties undergoing the electric pulses to improve numerical models and predict treatment volumes. We report on the experimental characterization of these changes for kidney tissue. Tissue samples were pulsed between plate electrodes while intrapulse voltage and current data were measured to determine the conductivity of the tissue during the pulse. Conductivity was then established as a function of the electric field to which the tissue is exposed. This conductivity curve was used in a numerical model to demonstrate the impact of accounting for these changes when modeling electric field distributions to develop treatment plans.

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

PubMed

Woo, Jun-Myung; Kim, Seok Hyang; Chun, Honnggu; Kim, Sung Jae; Ahn, Jinhong; Park, Young June

2013-09-21

In this paper, we investigate the effect of electrical pulse bias on DNA hybridization events in a biosensor platform, using a Carbon Nanotube Network (CNN) and Gold Nano Particles (GNP) as an electrical channel. The scheme provides both hybridization rate enhancement of bio molecules, and electrical measurement in a transient state to avoid the charge screening effect, thereby significantly improving the sensitivity. As an example, the probe DNA molecules oscillate with pulse trains, resulting in the enhancement of DNA hybridization efficiency, and accordingly of the sensor performances in Tris-EDTA (TE) buffer solution, by as much as over three times, compared to the non-biasing conditions. More importantly, a wide dynamic range of 10(6) (target-DNA concentration from 5 pM to 5 μM) is achieved in human serum. In addition, the pulse biasing method enables one to obtain the conductance change, before the ions within the Electrical Double Layer (EDL) are redistributed, to avoid the charge screening effect, leading to an additional sensitivity enhancement.

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

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

Circuit for detecting initial systole and dicrotic notch. [for monitoring arterial pressure

NASA Technical Reports Server (NTRS)

Gebben, V. D.; Webb, J. A., Jr. (Inventor)

1974-01-01

Circuitry is disclosed for processing an arterial pressure waveform to produce during any one cycle a pulse corresponding to the initial systole and a pulse corresponding to the dicrotic notch. In a first channel, an electrical analog of the arterial pressure waveform is filtered and then compared to the original waveform to produce an initial systole signal. In a second channel, the analog is differentiated, filtered, and fed through a gate controlled by pulses from the first channel to produce an electrical pulse corresponding to the dicrotic notch.

Nanosecond Plasma Enhanced H2/O2/N2 Premixed Flat Flames

DTIC Science & Technology

2014-01-01

Simulations are conducted with a one-dimensional, multi-scale, pulsed -discharge model with detailed plasma-combustion kinetics to develop additional insight... model framework. The reduced electric field, E/N, during each pulse varies inversely with number density. A significant portion of the input energy is...dimensional numerical model [4, 12] capable of resolving electric field transients over nanosecond timescales (during each discharge pulse ) and radical

Rotation Detection Using the Precession of Molecular Electric Dipole Moment

NASA Astrophysics Data System (ADS)

Ke, Yi; Deng, Xiao-Bing; Hu, Zhong-Kun

2017-11-01

We present a method to detect the rotation by using the precession of molecular electric dipole moment in a static electric field. The molecular electric dipole moments are polarized under the static electric field and a nonzero electric polarization vector emerges in the molecular gas. A resonant radio-frequency pulse electric field is applied to realize a 90° flip of the electric polarization vector of a particular rotational state. After the pulse electric field, the electric polarization vector precesses under the static electric field. The rotation induces a shift in the precession frequency which is measured to deduce the angular velocity of the rotation. The fundamental sensitivity limit of this method is estimated. This work is only a proposal and does not involve experimental results.

Neuromuscular Electrical Stimulation for Skeletal Muscle Function

PubMed Central

Doucet, Barbara M.; Lam, Amy; Griffin, Lisa

2012-01-01

Lack of neural innervation due to neurological damage renders muscle unable to produce force. Use of electrical stimulation is a medium in which investigators have tried to find a way to restore movement and the ability to perform activities of daily living. Different methods of applying electrical current to modify neuromuscular activity are electrical stimulation (ES), neuromuscular electrical stimulation (NMES), transcutaneous electrical nerve stimulation (TENS), and functional electrical stimulation (FES). This review covers the aspects of electrical stimulation used for rehabilitation and functional purposes. Discussed are the various parameters of electrical stimulation, including frequency, pulse width/duration, duty cycle, intensity/amplitude, ramp time, pulse pattern, program duration, program frequency, and muscle group activated, and how they affect fatigue in the stimulated muscle. PMID:22737049

Project FOOTPRINT: Substation modeling and simulations for E1 pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Scott D.; Larson, D. J.; Kirkendall, B. A.

This report includes a presentation with an: Introduction to CW coupling; Introduction to single-pulse coupling; Description of E1 waveforms; Structures in a substation yard --articulated (as part of the substation's defined electrical functionality)--unarticulated (not as part of the substation's defined electrical functionality); Coupling --electrical coupling (capacitive coupling) --magnetic coupling (inductive coupling); Connectivity to long-line transmission lines; Control infrastructure; Summary; and References.

Multiplex electric discharge gas laser system

NASA Technical Reports Server (NTRS)

Laudenslager, James B. (Inventor); Pacala, Thomas J. (Inventor)

1987-01-01

A multiple pulse electric discharge gas laser system is described in which a plurality of pulsed electric discharge gas lasers are supported in a common housing. Each laser is supplied with excitation pulses from a separate power supply. A controller, which may be a microprocessor, is connected to each power supply for controlling the application of excitation pulses to each laser so that the lasers can be fired simultaneously or in any desired sequence. The output light beams from the individual lasers may be combined or utilized independently, depending on the desired application. The individual lasers may include multiple pairs of discharge electrodes with a separate power supply connected across each electrode pair so that multiple light output beams can be generated from a single laser tube and combined or utilized separately.

Pulsed Artificial Electrojet Generation

NASA Astrophysics Data System (ADS)

Papadopoulos, K.

2008-12-01

Traditional techniques for generating low frequency signals in the ULF/ELF range (.1-100 Hz) and rely on ground based Horizontal Electric Dipole (HED) antennas. It is, furthermore, well known that a Vertical Electric Dipole (VED) is by more than 50 dB more efficient than a HED with the same dipole current moment. However, the prohibitively long length of VED antennas in the ELF/ULF range coupled with voltage limitations due to corona discharge in the atmosphere make them totally impracticable. In this paper we discuss a novel concept, inspired by the physics of the equatorial electrojet, that allows for the conversion of a ground based HED to a VED in the E-region of the equatorial ionosphere with current moment comparable to the driving HED. The paper focuses in locations near the dip-equator, where the earth's magnetic is in predominantly in the horizontal direction. The horizontal electric field associated with a pulsed HED drives a large Hall current in the ionospheric E-region, resulting in a vertical current. It is shown that the pulsed vertical current in the altitude range 80-130 km, driven by a horizontal electric field of, approximately, .1 mV/m at 100 km altitude, is of the order of kA. This results in a pulsed VED larger than 106 A-m. Such a pulsed VED will drive ELF/ULF pulses with amplitude in excess of .1 nT at a lateral range larger than few hundred kilometers. This is by three orders of magnitude larger than the one expected by a HED with comparable current moment. The paper will conclude with the description of a sneak-through technique that allows for creating pulsed electric fields in the ionosphere much larger than expected from steady state oscillatory HED antennas.

Plasma-enhanced mixing and flameholding in supersonic flow.

PubMed

Firsov, Alexander; Savelkin, Konstantin V; Yarantsev, Dmitry A; Leonov, Sergey B

2015-08-13

The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure P(st)=160-250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of W(pl)=3-24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air-fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Application of Filters for High-Altitude Electromagnetic Pulse Protection

DTIC Science & Technology

1981-04-01

The application of filters for the protection of electrical equipment from electrical transient signals induced by high-altitude electromagnetic ... pulse (HEMP) is discussed, and the application of filters to ac and dc power supplies and analog and digital signal inputs is described. The application

OCE NEMP PROGRAM DEVELOPMENT OF CRITERIA FOR PROTECTION OF NIKE-X POWER PLANT AND FACILITIES ELECTRICAL SYSTEMS AGAINST NUCLEAR ELECTROMAGNETIC PULSE EFFECTS.

DTIC Science & Technology

technical backup material for the OCE NEMP PROGRAM, Development of Criteria for Protection of NIKE-X Power Plant and Facilities Electrical Systems Against Nuclear Electromagnetic Pulse Effects, Protective MEASURES. (Author)

Demonstration of the Protein Involvement in Cell Electropermeabilization using Confocal Raman Microspectroscopy

PubMed Central

Azan, Antoine; Untereiner, Valérie; Gobinet, Cyril; Sockalingum, Ganesh D.; Breton, Marie; Piot, Olivier; Mir, Lluis M.

2017-01-01

Confocal Raman microspectroscopy was used to study the interaction between pulsed electric fields and live cells from a molecular point of view in a non-invasive and label-free manner. Raman signatures of live human adipose-derived mesenchymal stem cells exposed or not to pulsed electric fields (8 pulses, 1 000 V/cm, 100 μs, 1 Hz) were acquired at two cellular locations (nucleus and cytoplasm) and two spectral bands (600–1 800 cm−1 and 2 800–3 100 cm−1). Vibrational modes of proteins (phenylalanine and amide I) and lipids were found to be modified by the electropermeabilization process with a statistically significant difference. The relative magnitude of four phenylalanine peaks decreased in the spectra of the pulsed group. On the contrary, the relative magnitude of the amide I band at 1658 cm−1 increased by 40% when comparing pulsed and control group. No difference was found between the control and the pulsed group in the high wavenumber spectral band. Our results reveal the modification of proteins in living cells exposed to pulsed electric fields by means of confocal Raman microspectroscopy. PMID:28102326

Numerical simulation of Trichel pulses of negative DC corona discharge based on a plasma chemical model

NASA Astrophysics Data System (ADS)

Chen, Xiaoyue; Lan, Lei; Lu, Hailiang; Wang, Yu; Wen, Xishan; Du, Xinyu; He, Wangling

2017-10-01

A numerical simulation method of negative direct current (DC) corona discharge based on a plasma chemical model is presented, and a coaxial cylindrical gap is adopted. There were 15 particle species and 61 kinds of collision reactions electrons involved, and 22 kinds of reactions between ions are considered in plasma chemical reactions. Based on this method, continuous Trichel pulses are calculated on about a 100 us timescale, and microcosmic physicochemical process of negative DC corona discharge in three different periods is discussed. The obtained results show that the amplitude of Trichel pulses is between 1-2 mA, and that pulse interval is in the order of 10-5 s. The positive ions produced by avalanche ionization enhanced the electric field near the cathode at the beginning of the pulse, then disappeared from the surface of cathode. The electric field decreases and the pulse ceases to develop. The negative ions produced by attachment slowly move away from the cathode, and the electric field increases gradually until the next pulse begins to develop. The positive and negative ions with the highest density during the corona discharge process are O4+ and O3- , respectively.

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

PubMed

Owens, Thomas L

2008-03-01

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

Development of a statistical model for cervical cancer cell death with irreversible electroporation in vitro.

PubMed

Yang, Yongji; Moser, Michael A J; Zhang, Edwin; Zhang, Wenjun; Zhang, Bing

2018-01-01

The aim of this study was to develop a statistical model for cell death by irreversible electroporation (IRE) and to show that the statistic model is more accurate than the electric field threshold model in the literature using cervical cancer cells in vitro. HeLa cell line was cultured and treated with different IRE protocols in order to obtain data for modeling the statistical relationship between the cell death and pulse-setting parameters. In total, 340 in vitro experiments were performed with a commercial IRE pulse system, including a pulse generator and an electric cuvette. Trypan blue staining technique was used to evaluate cell death after 4 hours of incubation following IRE treatment. Peleg-Fermi model was used in the study to build the statistical relationship using the cell viability data obtained from the in vitro experiments. A finite element model of IRE for the electric field distribution was also built. Comparison of ablation zones between the statistical model and electric threshold model (drawn from the finite element model) was used to show the accuracy of the proposed statistical model in the description of the ablation zone and its applicability in different pulse-setting parameters. The statistical models describing the relationships between HeLa cell death and pulse length and the number of pulses, respectively, were built. The values of the curve fitting parameters were obtained using the Peleg-Fermi model for the treatment of cervical cancer with IRE. The difference in the ablation zone between the statistical model and the electric threshold model was also illustrated to show the accuracy of the proposed statistical model in the representation of ablation zone in IRE. This study concluded that: (1) the proposed statistical model accurately described the ablation zone of IRE with cervical cancer cells, and was more accurate compared with the electric field model; (2) the proposed statistical model was able to estimate the value of electric field threshold for the computer simulation of IRE in the treatment of cervical cancer; and (3) the proposed statistical model was able to express the change in ablation zone with the change in pulse-setting parameters.

Linear Self-Referencing Techiques for Short-Optical-Pulse Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorrer, C.; Kang, I.

2008-04-04

Linear self-referencing techniques for the characterization of the electric field of short optical pulses are presented. The theoretical and practical advantages of these techniques are developed. Experimental implementations are described, and their performance is compared to the performance of their nonlinear counterparts. Linear techniques demonstrate unprecedented sensitivity and are a perfect fit in many domains where the precise, accurate measurement of the electric field of an optical pulse is required.

Design, characterization and experimental validation of a compact, flexible pulsed power architecture for ex vivo platelet activation

PubMed Central

Caiafa, Antonio; Jiang, Yan; Klopman, Steve; Morton, Christine; Torres, Andrew S.; Loveless, Amanda M.; Neculaes, V. Bogdan

2017-01-01

Electric pulses can induce various changes in cell dynamics and properties depending upon pulse parameters; however, pulsed power generators for in vitro and ex vivo applications may have little to no flexibility in changing the pulse duration, rise- and fall-times, or pulse shape. We outline a compact pulsed power architecture that operates from hundreds of nanoseconds (with the potential for modification to tens of nanoseconds) to tens of microseconds by modifying a Marx topology via controlling switch sequences and voltages into each capacitor stage. We demonstrate that this device can deliver pulses to both low conductivity buffers, like standard pulsed power supplies used for electroporation, and higher conductivity solutions, such as blood and platelet rich plasma. We further test the effectiveness of this pulse generator for biomedical applications by successfully activating platelets ex vivo with 400 ns and 600 ns electric pulses. This novel bioelectrics platform may provide researchers with unprecedented flexibility to explore a wide range of pulse parameters that may induce phenomena ranging from intracellular to plasma membrane manipulation. PMID:28746392

Voyager Uranus encounter 0.2lbf T/VA short pulse test report

NASA Technical Reports Server (NTRS)

1986-01-01

The attitude control thrusters on the Voyager spacecraft were tested for operation at electrical pulse widths of less than the current 10-millisecond minimum to reduce impulse bit and, therefore, reduce image smear of pictures taken during the Uranus encounter. Thrusters with the identical configuration of the units on the spacecraft were fired in an altitude chamber to characterize impulse bit and impulse bit variations as a function of electrical pulse widths and to determine if the short pulses decreased thruster life. Pulse widths of 4.0 milliseconds provide approximately 45 percent of the impulse provided by a 10-ms pulse, and thruster-to-thruster and pulse-to-pulse variation is approximately plus or minus 10 percent. Pulse widths shorter than 4 ms showed wide variation, and no pulse was obtained at 3 ms. Three thrusters were each subjected to 75,000 short pulses of 4 ms or less without performance degradation. A fourth thruster exhibited partial flow blockage after 13,000 short pulses, but this was attributed to prevous test history and not short pulse exposure. The Voyager attitude control thrusters should be considered flight qualified for short pulse operation at pulse widths of 4.0 ms or more.

An analytical model for the calculation of the change in transmembrane potential produced by an ultrawideband electromagnetic pulse.

PubMed

Hart, Francis X; Easterly, Clay E

2004-05-01

The electric field pulse shape and change in transmembrane potential produced at various points within a sphere by an intense, ultrawideband pulse are calculated in a four stage, analytical procedure. Spheres of two sizes are used to represent the head of a human and the head of a rat. In the first stage, the pulse is decomposed into its Fourier components. In the second stage, Mie scattering analysis (MSA) is performed for a particular point in the sphere on each of the Fourier components, and the resulting electric field pulse shape is obtained for that point. In the third stage, the long wavelength approximation (LWA) is used to obtain the change in transmembrane potential in a cell at that point. In the final stage, an energy analysis is performed. These calculations are performed at 45 points within each sphere. Large electric fields and transmembrane potential changes on the order of a millivolt are produced within the brain, but on a time scale on the order of nanoseconds. The pulse shape within the brain differs considerably from that of the incident pulse. Comparison of the results for spheres of different sizes indicates that scaling of such pulses across species is complicated. Published 2004 Wiley-Liss, Inc.

Air and water cooled modulator

DOEpatents

Birx, Daniel L.; Arnold, Phillip A.; Ball, Don G.; Cook, Edward G.

1995-01-01

A compact high power magnetic compression apparatus and method for delivering high voltage pulses of short duration at a high repetition rate and high peak power output which does not require the use of environmentally unacceptable fluids such as chlorofluorocarbons either as a dielectric or as a coolant, and which discharges very little waste heat into the surrounding air. A first magnetic switch has cooling channels formed therethrough to facilitate the removal of excess heat. The first magnetic switch is mounted on a printed circuit board. A pulse transformer comprised of a plurality of discrete electrically insulated and magnetically coupled units is also mounted on said printed board and is electrically coupled to the first magnetic switch. The pulse transformer also has cooling means attached thereto for removing heat from the pulse transformer. A second magnetic switch also having cooling means for removing excess heat is electrically coupled to the pulse transformer. Thus, the present invention is able to provide high voltage pulses of short duration at a high repetition rate and high peak power output without the use of environmentally unacceptable fluids and without discharging significant waste heat into the surrounding air.

Mission Assessment of the Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD)

NASA Technical Reports Server (NTRS)

Dankanich, John W.; Polzin, Kurt A.

2008-01-01

Pulsed inductive thrusters have typically been considered for future, high-power, missions requiring nuclear electric propulsion. These high-power systems, while promising equivalent or improved performance over state-of-the-art propulsion systems, presently have no planned missions for which they are well suited. The ability to efficiently operate an inductive thruster at lower energy and power levels may provide inductive thrusters near term applicability and mission pull. The Faraday Accelerator with Radio-frequency Assisted Discharge concept demonstrated potential for a high-efficiency, low-energy pulsed inductive thruster. The added benefits of energy recapture and/or pulse compression are shown to enhance the performance of the pulsed inductive propulsion system, yielding a system that con compete with and potentially outperform current state-of-the-art electric propulsion technologies. These enhancements lead to mission-level benefits associated with the use of a pulsed inductive thruster. Analyses of low-power near to mid-term missions and higher power far-term missions are undertaken to compare the performance of pulsed inductive thrusters with that delivered by state-of-the-art and development-level electric propulsion systems.

Sub-nanosecond resolution electric field measurements during ns pulse breakdown in ambient air

NASA Astrophysics Data System (ADS)

Simeni Simeni, Marien; Goldberg, Ben; Gulko, Ilya; Frederickson, Kraig; Adamovich, Igor V.

2018-01-01

Electric field during ns pulse discharge breakdown in ambient air has been measured by ps four-wave mixing, with temporal resolution of 0.2 ns. The measurements have been performed in a diffuse plasma generated in a dielectric barrier discharge, in plane-to-plane geometry. Absolute calibration of the electric field in the plasma is provided by the Laplacian field measured before breakdown. Sub-nanosecond time resolution is obtained by using a 150 ps duration laser pulse, as well as by monitoring the timing of individual laser shots relative to the voltage pulse, and post-processing four-wave mixing signal waveforms saved for each laser shot, placing them in the appropriate ‘time bins’. The experimental data are compared with the analytic solution for time-resolved electric field in the plasma during pulse breakdown, showing good agreement on ns time scale. Qualitative interpretation of the data illustrates the effects of charge separation, charge accumulation/neutralization on the dielectric surfaces, electron attachment, and secondary breakdown. Comparison of the present data with more advanced kinetic modeling is expected to provide additional quantitative insight into air plasma kinetics on ~ 0.1-100 ns scales.

Pulse propagation, dispersion, and energy in magnetic materials.

PubMed

Scalora, Michael; D'Aguanno, Giuseppe; Mattiucci, Nadia; Akozbek, Neset; Bloemer, Mark J; Centini, Marco; Sibilia, Concita; Bertolotti, Mario

2005-12-01

We discuss pulse propagation effects in generic, electrically and magnetically dispersive media that may display large material discontinuities, such as a surface boundary. Using the known basic constitutive relations between the fields, and an explicit Taylor expansion to describe the dielectric susceptibility and magnetic permeability, we derive expressions for energy density and energy dissipation rates, and equations of motion for the coupled electric and magnetic fields. We then solve the equations of motion in the presence of a single interface, and find that in addition to the now-established negative refraction process an energy exchange occurs between the electric and magnetic fields as the pulse traverses the boundary.

Acoustic microscope surface inspection system and method

DOEpatents

Khuri-Yakub, B.T.; Parent, P.; Reinholdtsen, P.A.

1991-02-26

An acoustic microscope surface inspection system and method are described in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respect to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations. 7 figures.

Electrical characterization of a Mapham inverter using pulse testing techniques

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

Temperature-Dependent Electrical Conductivity of GeTe-Based RF Switches

DTIC Science & Technology

2015-03-31

Short, high temperature pulses result in a melt -quench cycle, amorphizing the GeTe and leaving the switch in the electrically insulating OFF state...Longer, lower temperature pulses result in the recrystallization of the GeTe, leaving the switch in the electrically conductive ON state. The...shown to vary only weakly with temperature. OFF-state S-parameters also exhibit slight temperature variation, with an inflection point of ~175

Pulsed electric field processing for fruit and vegetables

USDA-ARS?s Scientific Manuscript database

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...

A coaxial-output capacitor-loaded annular pulse forming line.

PubMed

Li, Rui; Li, Yongdong; Su, Jiancang; Yu, Binxiong; Xu, Xiudong; Zhao, Liang; Cheng, Jie; Zeng, Bo

2018-04-01

A coaxial-output capacitor-loaded annular pulse forming line (PFL) is developed in order to reduce the flat top fluctuation amplitude of the forming quasi-square pulse and improve the quality of the pulse waveform produced by a Tesla-pulse forming network (PFN) type pulse generator. A single module composed of three involute dual-plate PFNs is designed, with a characteristic impedance of 2.44 Ω, an electrical length of 15 ns, and a sustaining voltage of 60 kV. The three involute dual-plate PFNs connected in parallel have the same impedance and electrical length. Due to the existed small inductance and capacitance per unit length in each involute dual-plate PFN, the upper cut-off frequency of the PFN is increased. As a result, the entire annular PFL has better high-frequency response capability. Meanwhile, the three dual-plate PFNs discharge in parallel, which is much closer to the coaxial output. The series connecting inductance between adjacent two modules is significantly reduced when the annular PFL modules are connected in series. The pulse waveform distortion is reduced when the pulse transfers along the modules. Finally, the shielding electrode structure is applied on both sides of the module. The electromagnetic field is restricted in the module when a single module discharges, and the electromagnetic coupling between the multi-stage annular PFLs is eliminated. Based on the principle of impedance matching between the multi-stage annular PFL and the coaxial PFL, the structural optimization design of a mixed PFL in a Tesla type pulse generator is completed with the transient field-circuit co-simulation method. The multi-stage annular PFL consists of 18 stage annular PFL modules in series, with the characteristic impedance of 44 Ω, the electrical length of 15 ns, and the sustaining voltage of 1 MV. The mixed PFL can generate quasi-square electrical pulses with a pulse width of 43 ns, and the fluctuation ratio of the pulse flat top is less than 8% when the pulse rise time is about 5 ns.

A coaxial-output capacitor-loaded annular pulse forming line

NASA Astrophysics Data System (ADS)

Li, Rui; Li, Yongdong; Su, Jiancang; Yu, Binxiong; Xu, Xiudong; Zhao, Liang; Cheng, Jie; Zeng, Bo

2018-04-01

A coaxial-output capacitor-loaded annular pulse forming line (PFL) is developed in order to reduce the flat top fluctuation amplitude of the forming quasi-square pulse and improve the quality of the pulse waveform produced by a Tesla-pulse forming network (PFN) type pulse generator. A single module composed of three involute dual-plate PFNs is designed, with a characteristic impedance of 2.44 Ω, an electrical length of 15 ns, and a sustaining voltage of 60 kV. The three involute dual-plate PFNs connected in parallel have the same impedance and electrical length. Due to the existed small inductance and capacitance per unit length in each involute dual-plate PFN, the upper cut-off frequency of the PFN is increased. As a result, the entire annular PFL has better high-frequency response capability. Meanwhile, the three dual-plate PFNs discharge in parallel, which is much closer to the coaxial output. The series connecting inductance between adjacent two modules is significantly reduced when the annular PFL modules are connected in series. The pulse waveform distortion is reduced when the pulse transfers along the modules. Finally, the shielding electrode structure is applied on both sides of the module. The electromagnetic field is restricted in the module when a single module discharges, and the electromagnetic coupling between the multi-stage annular PFLs is eliminated. Based on the principle of impedance matching between the multi-stage annular PFL and the coaxial PFL, the structural optimization design of a mixed PFL in a Tesla type pulse generator is completed with the transient field-circuit co-simulation method. The multi-stage annular PFL consists of 18 stage annular PFL modules in series, with the characteristic impedance of 44 Ω, the electrical length of 15 ns, and the sustaining voltage of 1 MV. The mixed PFL can generate quasi-square electrical pulses with a pulse width of 43 ns, and the fluctuation ratio of the pulse flat top is less than 8% when the pulse rise time is about 5 ns.

Creating Rydberg electron wave packets using terahertz pulses

NASA Astrophysics Data System (ADS)

Bromage, Jake

1999-10-01

In this thesis I present experiments in which we excited classical-limit states of an atom using terahertz pulses. In a classical-limit state, an atom's outer electron is confined to a wave packet that orbits the core along a classical trajectory. Researchers have excited states with classical traits, but wave packets localized in all three dimensions have proved elusive. Theoretical studies have shown such states can be created using terahertz pulses. Using these techniques, we created a linear-orbit wave packet (LOWP), that is three-dimensionally localized and orbits along a line on one side of the atom's core. Terahertz pulses are sub-picosecond bursts of far- infrared radiation. Unlike ultrashort optical pulses, the electric field of terahertz pulses barely completes a single cycle. Our simulations of the atom-pulse interaction show that this electric field profile is critical in determining the quality of the wave packet. To characterize our terahertz pulses, we invented dithered-edge sampling which time- resolves the electric field using a photoconductive receiver and a triggered attenuator. We also studied how pulses are distorted after propagating through metallic structures, and used our findings to design our atomic experiments. We excited wave packets in atomic sodium using a two-step process. First, we used tunable, nanosecond dye lasers to excite an extreme Stark state. Next, we used a terahertz pump pulse to coherently redistribute population among extreme Stark states in neighboring manifolds. Interference between the final states produces a localized, dynamic LOWP. To analyze the LOWP, we ionized it with a stronger terahertz probe pulse, varying the pump-probe delay to map out its motion. We observed two strong LOWP signatures. Changing the static electric field produced small changes (2%) in the orbital period that agreed with our theoretical predictions. Secondly, because the LOWP scatters off the core, the pump-probe signal depended on the direction of the kick the LOWP received from the robe pulse. These observations, combined with our detailed simulations that used sodium parameters and the actual shape of the terahertz pulse, lead us to conclude that we excited a LOWP.

Excitability and optical pulse generation in semiconductor lasers driven by resonant tunneling diode photo-detectors.

PubMed

Romeira, Bruno; Javaloyes, Julien; Ironside, Charles N; Figueiredo, José M L; Balle, Salvador; Piro, Oreste

2013-09-09

We demonstrate, experimentally and theoretically, excitable nanosecond optical pulses in optoelectronic integrated circuits operating at telecommunication wavelengths (1550 nm) comprising a nanoscale double barrier quantum well resonant tunneling diode (RTD) photo-detector driving a laser diode (LD). When perturbed either electrically or optically by an input signal above a certain threshold, the optoelectronic circuit generates short electrical and optical excitable pulses mimicking the spiking behavior of biological neurons. Interestingly, the asymmetric nonlinear characteristic of the RTD-LD allows for two different regimes where one obtain either single pulses or a burst of multiple pulses. The high-speed excitable response capabilities are promising for neurally inspired information applications in photonics.

High-spatial-frequency periodic surface structures on steel substrate induced by subnanosecond laser pulses

NASA Astrophysics Data System (ADS)

Hikage, Haruki; Nosaka, Nami; Matsuo, Shigeki

2017-11-01

By irradiation with 0.5 ns laser pulses at a wavelength λ = 1.064 µm, laser-induced periodic surface structures (LIPSS) were fabricated on a steel substrate. In addition to low-spatial-frequency LIPSS (LSFL), a high-spatial-frequency LIPSS (HSFL) of period Λ ∼ 0.4λ with two-dimensional expansion was formed, although it is generally recognized that HSFL are formed only by ultrafast laser pulses. The wavevector of the observed HSFL was perpendicular to the electric field of the irradiated laser pulse (each ridge/groove of the HSFL was parallel to the electric field). We discuss the relationship between the formation of HSFL and the pulse duration.

Multiple frequency optical mixer and demultiplexer and apparatus for remote sensing

NASA Technical Reports Server (NTRS)

Chen, Jeffrey R. (Inventor)

2010-01-01

A pulsed laser system includes a modulator module configured to provide pulsed electrical signals and a plurality of solid-state seed sources coupled to the modulator module and configured to operate, responsive to the pulsed electrical signals, in a pulse mode. Each of the plurality of solid-state seed sources is tuned to a different frequency channel separated from any adjacent frequency channel by a frequency offset. The pulsed laser system also includes a combiner that combines outputs from each of the solid state seed sources into a single optical path and an optical doubler and demultiplexer coupled to the single optical path and providing each doubled seed frequency on a separate output path.

Subcellular Biological Effects of Nanosecond Pulsed Electric Fields

NASA Astrophysics Data System (ADS)

Kolb, Juergen F.; Stacey, Michael

Membranes of biological cells can be charged by exposure to pulsed electric fields. After the potential difference across the barrier reaches critical values on the order of 1 V, pores will form. For moderate pulse parameters of duration and amplitude, the effect is limited to the outer cell membrane. With the exposure to nanosecond pulses of several tens of kilovolts per centimeter, a similar effect is also expected for subcellular membranes and structures. Cells will respond to the disruption by different biochemical processes. This offers possibilities for the development of novel medical therapies, the manipulation of cells and microbiological decontamination.

Electric field detection of phase-locked near-infrared pulses using photoconductive antenna.

PubMed

Katayama, I; Akai, R; Bito, M; Matsubara, E; Ashida, M

2013-07-15

We have demonstrated that a photoconductive antenna gated with 5-fs ultrashort laser pulses can detect electric field transients of near-infrared pulses at least up to 180 THz. Measured sensitivity spectrum of the antenna shows a good agreement with a simple calculation, demonstrating the promising capability of the antenna to near infrared spectroscopy. Using this setup, near-infrared time-domain spectroscopy and characterization of phase controlled near-infrared pulses are demonstrated. Observed absorption spectrum of a polystyrene film and complex refractive index dispersion of a fused silica plate both agree well with those obtained by the conventional methods.

Preliminary Breakdown: Physical Mechanisms and Potential for Energetic Emissions

NASA Astrophysics Data System (ADS)

Petersen, D.; Beasley, W. H.

2014-12-01

Observations and analysis of the preliminary breakdown phase of virgin negative cloud-to-ground (-CG) lightning strokes will be presented. Of primary interest are the physical processes responsible for the fast electric field "characteristic" pulses that are often observed during this phase. The pulse widths of characteristic pulses are shown to occur as a superposed bimodal distribution, with the short and long modes having characteristic timescales on the order of 1 microsecond and 10 microseconds, respectively. Analysis of these pulses is based on comparison with laboratory observations of long spark discharge processes and with recently acquired high-speed video observations of a single -CG event. It will be argued that the fast electric field bimodal distribution is the result of conventional discharge processes operating in an extensive strong ambient electric field environment. An important related topic will also be discussed, where it will be argued that preliminary breakdown discharges are capable of generating energetic electrons and may therefore seed relativistic electron avalanches that go on to produce pulsed energetic photon emissions.

First-principles simulation for strong and ultra-short laser pulse propagation in dielectrics

NASA Astrophysics Data System (ADS)

Yabana, K.

2016-05-01

We develop a computational approach for interaction between strong laser pulse and dielectrics based on time-dependent density functional theory (TDDFT). In this approach, a key ingredient is a solver to simulate electron dynamics in a unit cell of solids under a time-varying electric field that is a time-dependent extension of the static band calculation. This calculation can be regarded as a constitutive relation, providing macroscopic electric current for a given electric field applied to the medium. Combining the solver with Maxwell equations for electromagnetic fields of the laser pulse, we describe propagation of laser pulses in dielectrics without any empirical parameters. An important output from the coupled Maxwell+TDDFT simulation is the energy transfer from the laser pulse to electrons in the medium. We have found an abrupt increase of the energy transfer at certain laser intensity close to damage threshold. We also estimate damage threshold by comparing the transferred energy with melting and cohesive energies. It shows reasonable agreement with measurements.

Experimental investigation of SDBD plasma actuator driven by AC high voltage with a superimposed positive pulse bias voltage

NASA Astrophysics Data System (ADS)

Qi, Xiao-Hua; Yan, Hui-Jie; Yang, Liang; Hua, Yue; Ren, Chun-Sheng

2017-08-01

In this work, a driven voltage consisting of AC high voltage with a superimposed positive pulse bias voltage ("AC+ Positive pulse bias" voltage) is adopted to study the performance of a surface dielectric barrier discharge plasma actuator under atmospheric conditions. To compare the performance of the actuator driven by single-AC voltage and "AC+ Positive pulse bias" voltage, the actuator-induced thrust force and power consumption are measured as a function of the applied AC voltage, and the measured results indicate that the thrust force can be promoted significantly after superimposing the positive pulse bias voltage. The physical mechanism behind the thrust force changes is analyzed by measuring the optical properties, electrical characteristics, and surface potential distribution. Experimental results indicate that the glow-like discharge in the AC voltage half-cycle, next to the cycle where a bias voltage pulse has been applied, is enhanced after applying the positive pulse bias voltage, and this perhaps is the main reason for the thrust force increase. Moreover, surface potential measurement results reveal that the spatial electric field formed by the surface charge accumulation after positive pulse discharge can significantly affect the applied external electric field, and this perhaps can be responsible for the experimental phenomenon that the decrease of thrust force is delayed by pulse bias voltage action after the filament discharge occurs in the glow-like discharge region. The schlieren images further verify that the actuator-induced airflow velocity increases with the positive pulse voltage.

The structure and properties of pulsed dc magnetron sputtered nanocrystalline TiN films for electrodes of alkali metal thermal-to-electric conversion systems.

PubMed

Chun, Sung-Yong

2013-03-01

Titanium nitride films used as an important electrode material for the design of alkali metal thermal-to-electric conversion (AMTEC) system have been prepared using dc (direct current) and asymmetric-bipolar pulsed dc magnetron sputtering. The pulse frequency and the duty cycle were varied from 5 to 50 kHz and 50 to 95%, respectively. The deposition rate, grain size and resistivity of pulsed dc sputtered films were decreased when the pulse frequency increased, while the nano hardness of titanium nitride films increased. We present in detail coatings (e.g., deposition rate, grain size, prefer-orientation, resistivity and hardness). Our studies show that titanium nitride coatings with superior properties can be prepared using asymmetric-bipolar pulsed dc sputtering.

Current-level triggered plasma-opening switch

DOEpatents

Mendel, C.W.

1987-06-29

An opening switch for very high power electrical pulses uses a slow magnetic field to confine a plasma across a gap between two electrodes. The plasma conducts the electric pulse across the gap while the switch is closed. A magnetic field generated by the pulse repels the slow magnetic field from the negative electrode to push the plasma from the electrode, opening the switch. A plurality of radial vanes may be used to enhance the slow magnetic field. 5 figs.

Current-level triggered plasma-opening switch

DOEpatents

Mendel, Clifford W.

1989-01-01

An opening switch for very high power electrical pulses uses a slow magnetic field to confine a plasma across a gap between two electrodes. The plasma conducts the electric pulse across the gap while the switch is closed. A magnetic field generated by the pulse repels the slow magnetic field from the negative electrode to push the plasma from the electrode, opening the switch. A plurality of radial vanes may be used to enhance the slow magnetic field.

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

USDA-ARS?s Scientific Manuscript database

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 ...

Enhancing Food Processing by Pulsed and High Voltage Electric Fields: Principles and Applications.

PubMed

Wang, Qijun; Li, Yifei; Sun, Da-Wen; Zhu, Zhiwei

2018-02-02

Improvements in living standards result in a growing demand for food with high quality attributes including freshness, nutrition and safety. However, current industrial processing methods rely on traditional thermal and chemical methods, such as sterilization and solvent extraction, which could induce negative effects on food quality and safety. The electric fields (EFs) involving pulsed electric fields (PEFs) and high voltage electric fields (HVEFs) have been studied and developed for assisting and enhancing various food processes. In this review, the principles and applications of pulsed and high voltage electric fields are described in details for a range of food processes, including microbial inactivation, component extraction, and winemaking, thawing and drying, freezing and enzymatic inactivation. Moreover, the advantages and limitations of electric field related technologies are discussed to foresee future developments in the food industry. This review demonstrates that electric field technology has a great potential to enhance food processing by supplementing or replacing the conventional methods employed in different food manufacturing processes. Successful industrial applications of electric field treatments have been achieved in some areas such as microbial inactivation and extraction. However, investigations of HVEFs are still in an early stage and translating the technology into industrial applications need further research efforts.

An explanation for parallel electric field pulses observed over thunderstorms

NASA Astrophysics Data System (ADS)

Kelley, M. C.; Barnum, B. H.

2009-10-01

Every electric field instrument flown on sounding rockets over a thunderstorm has detected pulses of electric fields parallel to the Earth's magnetic field associated with every strike. This paper describes the ionospheric signatures found during a flight from Wallops Island, Virginia, on 2 September 1995. The electric field results in a drifting Maxwellian corresponding to energies up to 1 eV. The distribution function relaxes because of elastic and inelastic collisions, resulting in electron heating up to 4000-5000 K and potentially observable red line emissions and enhanced ISR electron temperatures. The field strength scales with the current in cloud-to-ground strikes and falls off as r -1 with distance. Pulses of both polarities are found, although most electric fields are downward, parallel to the magnetic field. The pulse may be the reaction of ambient plasma to a current pulse carried at the whistler packet's highest group velocity. The charge source required to produce the electric field is very likely electrons of a few keV traveling at the packet velocity. We conjecture that the current source is the divergence of the current flowing at mesospheric heights, the phenomenon called an elve. The whistler packet's effective radiated power is as high as 25 mW at ionospheric heights, comparable to some ionospheric heater transmissions. Comparing the Poynting flux at the base of the ionosphere with flux an equal distance away along the ground, some 30 db are lost in the mesosphere. Another 10 db are lost in the transition from free space to the whistler mode.

Characteristics of Currents and Electric Fields Associated with the Initial Stage of Upward Lightning

NASA Astrophysics Data System (ADS)

Watanabe, N.; Nag, A.; Diendorfer, G.; Pichler, H.; Schulz, W.

2017-12-01

There is increasing interest in understanding processes associated with the initiation of upward lightning from tall structures. Characterization of such processes is essential for the development of appropriate models. We examine current and electric field waveforms for 15 negative upward flashes occurring in 2007-2009 initiated from the Gaisberg Tower located in Salzburg, Austria. Current was measured at the top of the tower using a 0.25 mΩ shunt. Electric field was measured simultaneously at close (170 m from the tower) and far (79 km from the tower in 2007 and 109 km in 2008-2009) distances. The initial stage (IS) of these flashes comprised of relatively slowly varying "background" current (having durations ranging from 132 to 692 ms), with faster, more impulsive current variations (pulses having durations ranging from 4.7 µs to 22.9 ms) overlaid on this background current. In five of the 15 (33%) flashes, this IS background current was negative while in the other ten (67%) flashes, the current was bipolar (changing between negative and positive values). 150 current pulses occurred during the IS of these 15 flashes, of which 28 (19%) were positive bipolar (positive initial polarity with a negative opposite polarity overshoot), 5 (3.3%) were positive unipolar (positive initial polarity with no opposite polarity overshoot), and 117 (78%) were negative unipolar. No negative bipolar pulses were found. The median peak current and risetime for the 28 bipolar pulses were 0.74 kA and 2.8 µs, respectively, and those for the 122 unipolar pulses were 0.87 kA and 70 µs, respectively. Generally speaking, majority of the pulses occurring at the beginning of the initial stage were lower-amplitude positive bipolar, while higher-amplitude unipolar pulses were more likely to occur at later times. These 150 IS current pulses produced 133 detectable electric field change signatures at the near station and 59 at the far station (all recorded at 79 km in 12 flashes occurring in 2007). We will examine in detail the characteristics of these electric field pulses in order to gain insights into the mechanisms of the underlying processes.

Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulaeman, M. Y.; Widita, R.

2014-09-30

Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20–100 kV/cm and with shorter duration of pulsemore » than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of −1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation.« less

Target charging in short-pulse-laser-plasma experiments.

PubMed

Dubois, J-L; Lubrano-Lavaderci, F; Raffestin, D; Ribolzi, J; Gazave, J; Compant La Fontaine, A; d'Humières, E; Hulin, S; Nicolaï, Ph; Poyé, A; Tikhonchuk, V T

2014-01-01

Interaction of high-intensity laser pulses with solid targets results in generation of large quantities of energetic electrons that are the origin of various effects such as intense x-ray emission, ion acceleration, and so on. Some of these electrons are escaping the target, leaving behind a significant positive electric charge and creating a strong electromagnetic pulse long after the end of the laser pulse. We propose here a detailed model of the target electric polarization induced by a short and intense laser pulse and an escaping electron bunch. A specially designed experiment provides direct measurements of the target polarization and the discharge current in the function of the laser energy, pulse duration, and target size. Large-scale numerical simulations describe the energetic electron generation and their emission from the target. The model, experiment, and numerical simulations demonstrate that the hot-electron ejection may continue long after the laser pulse ends, enhancing significantly the polarization charge.

Low Voltage Electrolytic Capacitor Pulse Forming Inductive Network for Electric Weapons

DTIC Science & Technology

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...Rotating Flywheel) Pulse Forming Network Compensated Pulsed Alternators, or Compulsators as they are called, are essentially large motor -generator

Sub-threshold depolarizing pre-pulses can enhance the efficiency of biphasic stimuli in transcutaneous neuromuscular electrical stimulation.

PubMed

Vargas Luna, Jose Luis; Mayr, Winfried; Cortés-Ramirez, Jorge-Armando

2018-06-09

There is multiple evidence in the literature that a sub-threshold pre-pulse, delivered immediately prior to an electrical stimulation pulse, can alter the activation threshold of nerve fibers and motor unit recruitment characteristics. So far, previously published works combined monophasic stimuli with sub-threshold depolarizing pre-pulses (DPPs) with inconsistent findings-in some studies, the DPPs decreased the activation threshold, while in others it was increased. This work aimed to evaluate the effect of DPPs during biphasic transcutaneous electrical stimulation and to study the possible mechanism underlying those differences. Sub-threshold DPPs between 0.5 and 15 ms immediately followed by biphasic or monophasic pulses were administered to the tibial nerve; the electrophysiological muscular responses (motor-wave, M-wave) were monitored via electromyogram (EMG) recording from the soleus muscle. The data show that, under the specific studied conditions, DPPs tend to lower the threshold for nerve fiber activation rather than elevating it. DPPs with the same polarity as the leading phase of biphasic stimuli are more effective to increase the sensitivity. This work assesses for the first time the effect of DPPs on biphasic pulses, which are required to achieve charge-balanced stimulation, and it provides guidance on the effect of polarity and intensity to take full advantage of this feature. Graphical abstract In this work, the effect of sub-threshold depolarizing pre-pulses (DPP) is investigated in a setup with transcutaneous electrical stimulation. We found that, within the tested 0-15 ms DPP duration range, the DPPs administered immediately before biphasic pulses proportionally increase the nerve excitability as visible in the M-waves recorded from the soleus muscle. Interestingly, these findings oppose published results, where DPPs, administered immediately before monophasic stimuli via implanted electrodes, led to decrease of nerve excitability.

Separation of large DNA molecules by applying pulsed electric field to size exclusion chromatography-based microchip

NASA Astrophysics Data System (ADS)

Azuma, Naoki; Itoh, Shintaro; Fukuzawa, Kenji; Zhang, Hedong

2018-02-01

Through electrophoresis driven by a pulsed electric field, we succeeded in separating large DNA molecules with an electrophoretic microchip based on size exclusion chromatography (SEC), which was proposed in our previous study. The conditions of the pulsed electric field required to achieve the separation were determined by numerical analyses using our originally proposed separation model. From the numerical results, we succeeded in separating large DNA molecules (λ DNA and T4 DNA) within 1600 s, which was approximately half of that achieved under a direct electric field in our previous study. Our SEC-based electrophoresis microchip will be one of the effective tools to meet the growing demand of faster and more convenient separation of large DNA molecules, especially in the field of epidemiological research of infectious diseases.

Miniature piezo electric vacuum inlet valve

DOEpatents

Keville, Robert F.; Dietrich, Daniel D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

Picosecond Electric-Field-Induced Threshold Switching in Phase-Change Materials.

PubMed

Zalden, Peter; Shu, Michael J; Chen, Frank; Wu, Xiaoxi; Zhu, Yi; Wen, Haidan; Johnston, Scott; Shen, Zhi-Xun; Landreman, Patrick; Brongersma, Mark; Fong, Scott W; Wong, H-S Philip; Sher, Meng-Ju; Jost, Peter; Kaes, Matthias; Salinga, Martin; von Hoegen, Alexander; Wuttig, Matthias; Lindenberg, Aaron M

2016-08-05

Many chalcogenide glasses undergo a breakdown in electronic resistance above a critical field strength. Known as threshold switching, this mechanism enables field-induced crystallization in emerging phase-change memory. Purely electronic as well as crystal nucleation assisted models have been employed to explain the electronic breakdown. Here, picosecond electric pulses are used to excite amorphous Ag_{4}In_{3}Sb_{67}Te_{26}. Field-dependent reversible changes in conductivity and pulse-driven crystallization are observed. The present results show that threshold switching can take place within the electric pulse on subpicosecond time scales-faster than crystals can nucleate. This supports purely electronic models of threshold switching and reveals potential applications as an ultrafast electronic switch.

A train of electrical pulses applied to the primary auditory cortex evokes a conditioned response in guinea pigs.

PubMed

Okuda, Yuji; Shikata, Hiroshi; Song, Wen-Jie

2011-09-01

As a step to develop auditory prosthesis by cortical stimulation, we tested whether a single train of pulses applied to the primary auditory cortex could elicit classically conditioned behavior in guinea pigs. Animals were trained using a tone as the conditioned stimulus and an electrical shock to the right eyelid as the unconditioned stimulus. After conditioning, a train of 11 pulses applied to the left AI induced the conditioned eye-blink response. Cortical stimulation induced no response after extinction. Our results support the feasibility of auditory prosthesis by electrical stimulation of the cortex. Copyright © 2011 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Lock-in detection for pulsed electrically detected magnetic resonance

NASA Astrophysics Data System (ADS)

Hoehne, Felix; Dreher, Lukas; Behrends, Jan; Fehr, Matthias; Huebl, Hans; Lips, Klaus; Schnegg, Alexander; Suckert, Max; Stutzmann, Martin; Brandt, Martin S.

2012-04-01

We show that in pulsed electrically detected magnetic resonance (pEDMR) signal modulation in combination with a lock-in detection scheme can reduce the low-frequency noise level by one order of magnitude and in addition removes the microwave-induced non-resonant background. This is exemplarily demonstrated for spin-echo measurements in phosphorus-doped silicon. The modulation of the signal is achieved by cycling the phase of the projection pulse used in pEDMR for the readout of the spin state.

Peculiarities of the Short-Pulse Dielectric Strength of Vacuum Insulation

NASA Astrophysics Data System (ADS)

Nefedtsev, E. V.; Onischenko, S. A.; Batrakov, A. V.

2017-12-01

Results of a study of the short-pulse dielectric strength of millimeter plane vacuum gaps with electrodes that have been treated with an electron beam are presented. It is shown that the electric field strength of the first breakdown of vacuum gaps with pure metal electrodes is determined to a significant extent by the crystal structure of the metal. The development of the first short-pulse breakdown is accompanied by a very abrupt growth of the electric current. The short duration of the test pulses rules out the influence of all well-known inertial mechanisms of breakdown with characteristic action times greater than 20 ns. Some general assumptions regarding the nature of the factors stimulating the short-pulse breakdown of vacuum gaps are considered.

Mitochondrial respiration inhibition after exposure to UWB pulses as a possible mechanism of antitumor action

NASA Astrophysics Data System (ADS)

Zharkova, L.; Romanchenko, I.; Bolshakov, M.; Rostov, V.

2017-05-01

The respiration of isolated mice liver mitochondria after exposure to nanosecond UWB pulses (0.15 - 36 kV/cm, 0.6 - 1.0 GHz centre frequency, 3 - 20 ns pulse duration) has been investigated. The respiratory control (RC, the ratio of oxygen consumption) was estimated. The possibility of mitochondrial membrane electroporation was detected as the decrease in the electrical resistance, according to the β-dispersion of the electric current. The monotonous decrease of RC after 1000 UWB pulses from 0.15 kV/cm was observed, the ohmic resistance of mitochondria suspension was reduced. The obtained data indicate the inhibitory effect of UWB pulses on a state of irradiated mitochondria and its membrane.

Burst stimulation improves hemodynamics during resuscitation after prolonged ventricular fibrillation.

PubMed

Walcott, Gregory; Melnick, Sharon; Killingsworth, Cheryl; Ideker, Raymond

2009-02-01

Although return of spontaneous circulation (ROSC) is frequently achieved during resuscitation for sudden cardiac arrest, systolic blood pressure can then decrease, requiring additional myocardial support. Previous studies have shown that a series of 1-ms electrical pulses delivered through the defibrillation patches during ventricular fibrillation (VF) can stimulate the autonomic nervous system to increase myocardial function following defibrillation. We hypothesized that a similar series of electrical pulses could increase myocardial function and blood pressure during the early post-resuscitation period. Six swine were studied that underwent 6-7 min. Each animal received 5, 10, 15, or 20 pulse packets consisting of 6 10 A, 1-ms pulses every 3-4 s in random order whenever systolic blood pressure became less than 50 mmHg. All four sets of pulse packets were delivered to each animal. Systolic blood pressure and cardiac function (left ventricular +dP/dt) were increased to pre-stimulation levels or above by all four sets of pulse packets. The increases were significantly greater for the longer than the shorter number of pulse packets. The mean+/-SD duration of the time that the systolic pressure remained above 50 mmHg following pulse delivery was 4.2+/-2.5 min. Electrical stimulation during regular rhythm following prolonged VF and resuscitation can increase blood pressure and cardiac function to above prestimulation levels.

Burst Stimulation Improves Hemodynamics During Resuscitation after Prolonged Ventricular Fibrillation

PubMed Central

Walcott, Gregory; Melnick, Sharon; Killingsworth, Cheryl; Ideker, Raymond

2009-01-01

Background Although return of spontaneous circulation (ROSC) is frequently achieved during resuscitation for sudden cardiac arrest, systolic blood pressure can then decrease, requiring additional myocardial support. Previous studies have shown that a series of 1-ms electrical pulses delivered through the defibrillation patches during ventricular fibrillation (VF) can stimulate the autonomic nervous system to increase myocardial function following defibrillation. We hypothesized that a similar series of electrical pulses could increase myocardial function and blood pressure during the early post-resuscitation period. Methods and Results Six swine were studied that underwent 6–7 min. Each animal received 5, 10, 15, or 20 pulse packets consisting of 6 10 A, 1-ms pulses every 3–4 s in random order whenever systolic blood pressure became less than 50 mmHg. All four sets of pulse packets were delivered to each animal. Systolic blood pressure and cardiac function (left ventricular +dP/dt) were increased to pre-stimulation levels or above by all four sets of pulse packets. The increases were significantly greater for the longer than the shorter number of pulse packets. The mean±SD duration of the time that the systolic pressure remained above 50 mmHg following pulse delivery was 4.2±2.5 min. Conclusions Electrical stimulation during regular rhythm following prolonged VF and resuscitation can increase blood pressure and cardiac function to above pre-arrest levels. PMID:19655042

An ultrafast programmable electrical tester for enabling time-resolved, sub-nanosecond switching dynamics and programming of nanoscale memory devices.

PubMed

Shukla, Krishna Dayal; Saxena, Nishant; Manivannan, Anbarasu

2017-12-01

Recent advancements in commercialization of high-speed non-volatile electronic memories including phase change memory (PCM) have shown potential not only for advanced data storage but also for novel computing concepts. However, an in-depth understanding on ultrafast electrical switching dynamics is a key challenge for defining the ultimate speed of nanoscale memory devices that demands for an unconventional electrical setup, specifically capable of handling extremely fast electrical pulses. In the present work, an ultrafast programmable electrical tester (PET) setup has been developed exceptionally for unravelling time-resolved electrical switching dynamics and programming characteristics of nanoscale memory devices at the picosecond (ps) time scale. This setup consists of novel high-frequency contact-boards carefully designed to capture extremely fast switching transient characteristics within 200 ± 25 ps using time-resolved current-voltage measurements. All the instruments in the system are synchronized using LabVIEW, which helps to achieve various programming characteristics such as voltage-dependent transient parameters, read/write operations, and endurance test of memory devices systematically using short voltage pulses having pulse parameters varied from 1 ns rise/fall time and 1.5 ns pulse width (full width half maximum). Furthermore, the setup has successfully demonstrated strikingly one order faster switching characteristics of Ag 5 In 5 Sb 60 Te 30 (AIST) PCM devices within 250 ps. Hence, this novel electrical setup would be immensely helpful for realizing the ultimate speed limits of various high-speed memory technologies for future computing.

An ultrafast programmable electrical tester for enabling time-resolved, sub-nanosecond switching dynamics and programming of nanoscale memory devices

NASA Astrophysics Data System (ADS)

Shukla, Krishna Dayal; Saxena, Nishant; Manivannan, Anbarasu

2017-12-01

Recent advancements in commercialization of high-speed non-volatile electronic memories including phase change memory (PCM) have shown potential not only for advanced data storage but also for novel computing concepts. However, an in-depth understanding on ultrafast electrical switching dynamics is a key challenge for defining the ultimate speed of nanoscale memory devices that demands for an unconventional electrical setup, specifically capable of handling extremely fast electrical pulses. In the present work, an ultrafast programmable electrical tester (PET) setup has been developed exceptionally for unravelling time-resolved electrical switching dynamics and programming characteristics of nanoscale memory devices at the picosecond (ps) time scale. This setup consists of novel high-frequency contact-boards carefully designed to capture extremely fast switching transient characteristics within 200 ± 25 ps using time-resolved current-voltage measurements. All the instruments in the system are synchronized using LabVIEW, which helps to achieve various programming characteristics such as voltage-dependent transient parameters, read/write operations, and endurance test of memory devices systematically using short voltage pulses having pulse parameters varied from 1 ns rise/fall time and 1.5 ns pulse width (full width half maximum). Furthermore, the setup has successfully demonstrated strikingly one order faster switching characteristics of Ag5In5Sb60Te30 (AIST) PCM devices within 250 ps. Hence, this novel electrical setup would be immensely helpful for realizing the ultimate speed limits of various high-speed memory technologies for future computing.

Kinetics of ultraweak light emission from human erythroleukemia K562 cells upon electroporation.

PubMed

Maccarrone, M; Fantini, C; Agrò, A F; Rosato, N

1998-11-11

Electroporation involves the application of an electric pulse that creates transient aqueous channels (electropores) across the lipid bilayer membranes. Here, we describe an instrument set up suitable to record ultraweak light emission from human erythroleukemia K562 cells during and immediately after delivery of electric pulses. Most of light was emitted in the first seconds after each pulse, following a complex decay which can be fitted by a double exponential equation characterized by two different time constants (T1 and T2), both in the order of seconds. T1 was approximately 10-fold shorter than T2 and both time constants were dependent on field strength of the electric pulse. The effect of various antioxidants on the amount of emitted photons and on T1 and T2 values was investigated, in order to shed some light on the chemical species responsible for cellular luminescence.

Assessment and Calibration of a Crimp Tool Equipped with Ultrasonic Analysis Features

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor); Perey, Daniel F. (Inventor); Cramer, K. Elliott (Inventor)

2013-01-01

A method is provided for calibrating ultrasonic signals passed through a crimp formed with respect to a deformable body via an ultrasonically-equipped crimp tool (UECT). The UECT verifies a crimp quality using the ultrasonic signals. The method includes forming the crimp, transmitting a first signal, e.g., a pulse, to a first transducer of the UECT, and converting the first signal, using the first transducer, into a second signal which defines an ultrasonic pulse. This pulse is transmitted through the UECT into the crimp. A second transducer converts the second signal into a third signal, which may be further conditioned, and the ultrasonic signals are calibrated using the third signal or its conditioned variant. An apparatus for calibrating the ultrasonic signals includes a pulse module (PM) electrically connected to the first and second transducers, and an oscilloscope or display electrically connected to the PM for analyzing an electrical output signal therefrom.

Runaway breakdown and hydrometeors in lightning initiation.

PubMed

Gurevich, A V; Karashtin, A N

2013-05-03

The particular electric pulse discharges are observed in thunderclouds during the initiation stage of negative cloud-to-ground lightning. The discharges are quite different from conventional streamers or leaders. A detailed analysis reveals that the shape of the pulses is determined by the runaway breakdown of air in the thundercloud electric field initiated by extensive atmospheric showers (RB-EAS). The high amplitude of the pulse electric current is due to the multiple microdischarges at hydrometeors stimulated and synchronized by the low-energy electrons generated in the RB-EAS process. The series of specific pulse discharges leads to charge reset from hydrometeors to the free ions and creates numerous stretched ion clusters, both positive and negative. As a result, a wide region in the thundercloud with a sufficiently high fractal ion conductivity is formed. The charge transport by ions plays a decisive role in the lightning leader preconditioning.

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

PubMed

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.

Gastric electrical stimulation with short pulses reduces vomiting but not dysrhythmias in dogs.

PubMed

Chen, Jiande D Z; Qian, Liwei; Ouyang, Hui; Yin, Jieyun

2003-02-01

The aim of this study was to investigate the acute effects of 3 different methods of electrical stimulation in the prevention of vasopressin-induced emetic response and gastric dysrhythmias. Seven female hound dogs chronically implanted with 4 pairs of electrodes on gastric serosa were used in a 5-session study. Saline and vasopressin were infused in sessions 1 and 2, respectively. In the other 3 sessions with vasopressin infusion, 3 different methods of electrical stimulation (short-pulse stimulation, long-pulse stimulation, and electroacupuncture) were applied. Gastric slow waves and vomiting and behaviors suggestive of nausea were recorded in each session. In a separate study, additional experiments were performed in 5 vagotomized dogs to investigate vagally mediated mechanisms. Vasopressin induced gastric dysrhythmias, uncoupling of slow waves, and vomiting and behaviors suggestive of nausea (P < 0.02, analysis of variance). Long-pulse stimulation, but not short-pulse stimulation or electroacupuncture, was capable of preventing vasopressin-induced gastric dysrhythmias and gastric slow wave uncoupling. Short-pulse stimulation and electroacupuncture, but not long-pulse stimulation, prevented vomiting and significantly reduced the symptom scores, which was not noted in the dogs with truncal vagotomy. Long-pulse stimulation normalizes vasopressin-induced slow wave abnormalities with no improvement in vomiting and behaviors suggestive of nausea. Short-pulse stimulation and electroacupuncture prevent vomiting and behaviors suggestive of nausea induced by vasopressin but have no effects on slow waves, and their effects are vagally mediated.

Microscopic histological characteristics of soft tissue sarcomas: analysis of tissue features and electrical resistance.

PubMed

Tosi, A L; Campana, L G; Dughiero, F; Forzan, M; Rastrelli, M; Sieni, E; Rossi, C R

2017-07-01

Tissue electrical conductivity is correlated with tissue characteristics. In this work, some soft tissue sarcomas (STS) excised from patients have been evaluated in terms of histological characteristics (cell size and density) and electrical resistance. The electrical resistance has been measured using the ex vivo study on soft tissue tumors electrical characteristics (ESTTE) protocol proposed by the authors in order to study electrical resistance of surgical samples excised by patients in a fixed measurement setup. The measurement setup includes a voltage pulse generator (700 V, 100 µs long at 5 kHz, period 200 µs) and an electrode with 7 needles, 20 mm-long, with the same distance arranged in a fixed hexagonal geometry. In the ESTTE protocol, the same voltage pulse sequence is applied to each different tumor mass and the corresponding resistance has been evaluated from voltage and current recorded by the equipment. For each tumor mass, a histological sample of the volume treated by means of voltage pulses has been taken for histological analysis. Each mass has been studied in order to identify the sarcoma type. For each histological sample, an image at 20× or 40× of magnification was acquired. In this work, the electrical resistance measured for each tumor has been correlated with tissue characteristics like the type, size and density of cells. This work presents a preliminary study to explore possible correlations between tissue characteristics and electrical resistance of STS. These results can be helpful to adjust the pulse voltage intensity in order to improve the electrochemotherapy efficacy on some histotype of STS.

Osmotic dehydration of blueberries pretreated with pulsed electric fields: Effects on drying rate, and microbiological and nutritional qualities

USDA-ARS?s Scientific Manuscript database

Fresh blueberries were treated by pulsed electric fields (PEF) at 2 kV/cm before osmotic dehydration in 70% sugar syrup. The changes in water loss, solids gain, populations of native microorganisms, antioxidant activity, contents of anthocyanins, predominant phenolic acids and flavonols, and total p...

Applications of Pulsed Power in Advanced Oxidation and Reduction Processes for Pollution Control

DTIC Science & Technology

1993-06-01

electrical driver pulse width and rise time, electrical drive circuit coupling to plasma cells, and the role of UV light in the plasma chemistry and...will permit industrial service. Basic understanding of the plasma chemistry has evolved to the point where trends and equipment scaling can be

Five years of full-scale utility demonstration of pulsed energization of electric precipitators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz, S.A.; Jacobus, P.L.; Casey, P.J.

1996-11-01

In a conventional electrostatic precipitator (ESP) the applied dc voltage fulfills three functions: (1) generation of negative ions, (2) charging of particles, and (3) transport of the charged particles to the collecting plates. In the case of high resistivity fly-ash (often associated with the burning of low sulfur coal) the dc voltage is limited by repeated electrical discharges and in extreme cases by back-corona. Lowering the applied dc voltage reduces sparking and back-corona, but also reduces the field on the discharge wires and leads to poorly distributed ion generation as well as reduced charging and particle transport forces. Pulsed energization,more » which consists of superimposing high voltage pulses of short duration onto the existing base dc voltage, offers an attractive way to improve the collection efficiency of ESPs suffering from poor energization. The superimposed pulses become responsible for uniform ion generation while the underlying dc field continues to fulfill the function of particle charging and transport. This paper describes the five-year test of the ESP at Madison Gas and Electric`s Blount Station.« less

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

PubMed

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.

Calorimetric system and method

DOEpatents

Gschneidner, Jr., Karl A.; Pecharsky, Vitalij K.; Moorman, Jack O.

1998-09-15

Apparatus for measuring heat capacity of a sample where a series of measurements are taken in succession comprises a sample holder in which a sample to be measured is disposed, a temperature sensor and sample heater for providing a heat pulse thermally connected to the sample, and an adiabatic heat shield in which the sample holder is positioned and including an electrical heater. An electrical power supply device provides an electrical power output to the sample heater to generate a heat pulse. The electrical power from a power source to the heat shield heater is adjusted by a control device, if necessary, from one measurement to the next in response to a sample temperature-versus-time change determined before and after a previous heat pulse to provide a subsequent sample temperature-versus-time change that is substantially linear before and after the subsequent heat pulse. A temperature sensor is used and operable over a range of temperatures ranging from approximately 3K to 350K depending upon the refrigerant used. The sample optionally can be subjected to dc magnetic fields such as from 0 to 12 Tesla (0 to 120 kOe).

Enhancing the lycopene in vitro bioaccessibility of tomato juice synergistically applying thermal and non-thermal processing technologies.

PubMed

Jayathunge, K G L R; Stratakos, Alexandros Ch; Cregenzán-Albertia, Oliver; Grant, Irene R; Lyng, James; Koidis, Anastasios

2017-04-15

The influence of moderate intensity pulsed electric field pre-processing on increasing the lycopene bioaccessibility of tomato fruit, and the combined effect of blanching, ultrasonic and high intensity pulsed electric field processing on further enhancement of the lycopene bioaccessibility after juicing were investigated. Maximum total lycopene bioaccessibility (9.6%) of the tomato fruit was achieved by a 4μs pre-processed treatment after 24h holding period and further processing results revealed that all treatments were effective to increase the total lycopene. Most of juice processing treatments decreased the release of lycopene from the tomato matrix during digestion. Only the treatment of blanching followed by high intensity pulsed electric field showed a significant release of trans-(4.01±0.48) and cis-(5.04±0.26μg/g) lycopene, achieving 15.6% total lycopene bioaccessibility. Thus, processing of pre-blanched juice using high intensity pulsed electric field, derived from pre-processed tomato was the best overall process to achieve the highest nutritive value. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of electric barrier on passage and physical condition of juvenile and adult rainbow trout

USGS Publications Warehouse

Layhee, Megan J.; Sepulveda, Adam; Shaw, Amy; Smuckall, Matthew; Kapperman, Kevin; Reyes, Alejandro

2016-01-01

Electric barriers can inhibit passage and injure fish. Few data exist on electric barrier parameters that minimize these impacts and on how body size affects susceptibility, especially to nontarget fish species. The goal of this study was to determine electric barrier voltage and pulse-width settings that inhibit passage of larger bodied rainbow trout Oncorhynchus mykiss (215–410 mm fork length) while allowing passage of smaller bodied juvenile rainbow trout (52–126 mm) in a static laboratory setting. We exposed rainbow trout to 30-Hz pulsed-direct current voltage gradients (0.00–0.45 V cm−1) and pulse widths (0.0–0.7 ms) and recorded their movement, injury incidence, and mortality. No settings tested allowed all juveniles to pass while impeding all adult passage. Juvenile and adult rainbow trout avoided the barrier at higher pulse widths, and fewer rainbow trout passed the barrier at 0.7-ms pulse width compared to 0.1 ms and when the barrier was turned off. We found no effect of voltage gradient on fish passage. No mortality occurred, and we observed external bruising in 5 (7%) juvenile rainbow trout and 15 (21%) adult rainbow trout. This study may aid managers in selecting barrier settings that allow for increased juvenile passage.

Experimental study of electrical discharge drilling of stainless steel UNS S30400

NASA Astrophysics Data System (ADS)

Hanash, E. A. H.; Ali, M. Y.

2018-01-01

In this study, overcut and taper angle were investigated in machining of stainless steel UNS S30400 against three different electrical discharge machining parameters which are electric current (Ip), pulse on-time (Ton) and pulse off-time (Toff). The electrode used was of 1 mm diameter with aspect ratio of 10. Dimensional accuracy was measured by evaluating overcut and taper angle. Those two measurements were performed using optical microscope model (Olympus BX41M, Japan). The experimentation planning, evaluation, analysis and optimization have been carried out using DOE software version 10.0.3 RSM based method with total number of twenty experiments. The research reveals that, discharge current was found to have the most significant effect on overcut and taper angle followed by pulse on-time and pulse off-time. As the discharge current and pulse on-time increase, overcut and taper angle are increased. However, when pulse off-time increases, overcut and taper angle decrease. The outcome result of this study will be very useful in the manufacturing industry to select the appropriate parameters for the selected work material. The model has shown a great accuracy with percentage error of less than 5%.

Air and water cooled modulator

DOEpatents

Birx, D.L.; Arnold, P.A.; Ball, D.G.; Cook, E.G.

1995-09-05

A compact high power magnetic compression apparatus and method are disclosed for delivering high voltage pulses of short duration at a high repetition rate and high peak power output which does not require the use of environmentally unacceptable fluids such as chlorofluorocarbons either as a dielectric or as a coolant, and which discharges very little waste heat into the surrounding air. A first magnetic switch has cooling channels formed therethrough to facilitate the removal of excess heat. The first magnetic switch is mounted on a printed circuit board. A pulse transformer comprised of a plurality of discrete electrically insulated and magnetically coupled units is also mounted on said printed board and is electrically coupled to the first magnetic switch. The pulse transformer also has cooling means attached thereto for removing heat from the pulse transformer. A second magnetic switch also having cooling means for removing excess heat is electrically coupled to the pulse transformer. Thus, the present invention is able to provide high voltage pulses of short duration at a high repetition rate and high peak power output without the use of environmentally unacceptable fluids and without discharging significant waste heat into the surrounding air. 9 figs.

Subfemtosecond directional control of chemical processes in molecules

NASA Astrophysics Data System (ADS)

Alnaser, Ali S.; Litvinyuk, Igor V.

2017-02-01

Laser pulses with a waveform-controlled electric field and broken inversion symmetry establish the opportunity to achieve directional control of molecular processes on a subfemtosecond timescale. Several techniques could be used to break the inversion symmetry of an electric field. The most common ones include combining a fundamental laser frequency with its second harmonic or with higher -frequency pulses (or pulse trains) as well as using few-cycle pulses with known carrier-envelope phase (CEP). In the case of CEP, control over chemical transformations, typically occurring on a timescale of many femtoseconds, is driven by much faster sub-cycle processes of subfemtosecond to few-femtosecond duration. This is possible because electrons are much lighter than nuclei and fast electron motion is coupled to the much slower nuclear motion. The control originates from populating coherent superpositions of different electronic or vibrational states with relative phases that are dependent on the CEP or phase offset between components of a two-color pulse. In this paper, we review the recent progress made in the directional control over chemical processes, driven by intense few-cycle laser pulses a of waveform-tailored electric field, in different molecules.

Effect of high-hydrostatic pressure and moderate-intensity pulsed electric field on plum.

PubMed

García-Parra, J; González-Cebrino, F; Delgado-Adámez, J; Cava, R; Martín-Belloso, O; Élez-Martínez, P; Ramírez, R

2018-03-01

Moderate intensity pulse electric fields were applied in plum with the aim to increase bioactive compounds content of the fruit, while high-hydrostatic pressure was applied to preserve the purées. High-hydrostatic pressure treatment was compared with an equivalent thermal treatment. The addition of ascorbic acid during purée manufacture was also evaluated. The main objective of this study was to assess the effects on microorganisms, polyphenoloxidase, color and bioactive compounds of high-hydrostatic pressure, or thermal-processed plum purées made of moderate intensity pulse electric field-treated or no-moderate intensity pulse electric field-treated plums, after processing during storage. The application of moderate intensity pulse electric field to plums slightly increased the levels of anthocyanins and the antioxidant activity of purées. The application of Hydrostatic-high pressure (HHP) increased the levels of bioactive compounds in purées, while the thermal treatment preserved better the color during storage. The addition of ascorbic acid during the manufacture of plum purée was an important factor for the final quality of purées. The color and the bioactive compounds content were better preserved in purées with ascorbic acid. The no inactivation of polyphenoloxidase enzyme with treatments applied in this study affected the stability purées. Probably more intense treatments conditions (high-hydrostatic pressure and thermal treatment) would be necessary to reach better quality and shelf life during storage.

Feasibility of employing model-based optimization of pulse amplitude and electrode distance for effective tumor electropermeabilization.

PubMed

Sel, Davorka; Lebar, Alenka Macek; Miklavcic, Damijan

2007-05-01

In electrochemotherapy (ECT) electropermeabilization, parameters (pulse amplitude, electrode setup) need to be customized in order to expose the whole tumor to electric field intensities above permeabilizing threshold to achieve effective ECT. In this paper, we present a model-based optimization approach toward determination of optimal electropermeabilization parameters for effective ECT. The optimization is carried out by minimizing the difference between the permeabilization threshold and electric field intensities computed by finite element model in selected points of tumor. We examined the feasibility of model-based optimization of electropermeabilization parameters on a model geometry generated from computer tomography images, representing brain tissue with tumor. Continuous parameter subject to optimization was pulse amplitude. The distance between electrode pairs was optimized as a discrete parameter. Optimization also considered the pulse generator constraints on voltage and current. During optimization the two constraints were reached preventing the exposure of the entire volume of the tumor to electric field intensities above permeabilizing threshold. However, despite the fact that with the particular needle array holder and pulse generator the entire volume of the tumor was not permeabilized, the maximal extent of permeabilization for the particular case (electrodes, tissue) was determined with the proposed approach. Model-based optimization approach could also be used for electro-gene transfer, where electric field intensities should be distributed between permeabilizing threshold and irreversible threshold-the latter causing tissue necrosis. This can be obtained by adding constraints on maximum electric field intensity in optimization procedure.

Inverting polar domains via electrical pulsing in metallic germanium telluride

PubMed Central

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

Nanosecond electrical and optical pulses and self phase conjugation from photorefractive lithium niobate fibers and crystals

NASA Astrophysics Data System (ADS)

Kukhtarev, N.; Kukhtareva, T.; Curley, M.; Jaenisch, H. M.; Edwards, M. E.; Gu, M.; Zhou, Z.; Guo, R.

2007-09-01

We have observed nanosecond electrical and optical pulsations from photorefractive lithium-niobate optical fibers using CW green and blue low-power lasers. Fourier spectra of the pulsations have a maximum at ~900 MHz with peaks separated by ~30MHz. We consider free-space and fiber supported illumination of the fiber crystal. Strong nonlinear enhanced backscattering with phase conjugation was observed from bulk crystals and crystal fibers along the C-axis. Model of transformation of CW laser irradiation of ferroelectric crystals into periodic nanosecond electrical and optical pulsations is suggested. This model includes combinations of photorefractive, pyroelectric, piezoelectric, and photogalvanic mechanisms of the holographic grating formation and crystal electrical charging. Possible applications of these short photo-induced electrical pulses for modulation of holographic beam coupling, pulsed electrolysis, electrophoresis, focused electron beams, X-ray and neutron generation, and hand-held micro X-ray devices for localized oncology imaging and treatment based on our advanced sensor work are discussed.

Electronic enhancement of tear secretion

NASA Astrophysics Data System (ADS)

Brinton, Mark; Lim Chung, Jae; Kossler, Andrea; Kook, Koung Hoon; Loudin, Jim; Franke, Manfred; Palanker, Daniel

2016-02-01

Objective. To study electrical stimulation of the lacrimal gland and afferent nerves for enhanced tear secretion, as a potential treatment for dry eye disease. We investigate the response pathways and electrical parameters to safely maximize tear secretion. Approach. We evaluated the tear response to electrical stimulation of the lacrimal gland and afferent nerves in isofluorane-anesthetized rabbits. In acute studies, electrical stimulation was performed using bipolar platinum foil electrodes, implanted beneath the inferior lacrimal gland, and a monopolar electrode placed near the afferent ethmoid nerve. Wireless microstimulators with bipolar electrodes were implanted beneath the lacrimal gland for chronic studies. To identify the response pathways, we applied various pharmacological inhibitors. To optimize the stimulus, we measured tear secretion rate (Schirmer test) as a function of pulse amplitude (1.5-12 mA), duration (0.1-1 ms) and repetition rate (10-100 Hz). Main results. Stimulation of the lacrimal gland increased tear secretion by engaging efferent parasympathetic nerves. Tearing increased with stimulation amplitude, pulse duration and repetition rate, up to 70 Hz. Stimulation with 3 mA, 500 μs pulses at 70 Hz provided a 4.5 mm (125%) increase in Schirmer score. Modulating duty cycle further increased tearing up to 57%, compared to continuous stimulation in chronically implanted animals (36%). Ethmoid (afferent) nerve stimulation increased tearing similar to gland stimulation (3.6 mm) via a reflex pathway. In animals with chronically implanted stimulators, a nearly 6 mm increase (57%) was achieved with 12-fold less charge density per pulse (0.06-0.3 μC mm-2 with 170-680 μs pulses) than the damage threshold (3.5 μC mm-2 with 1 ms pulses). Significance. Electrical stimulation of the lacrimal gland or afferent nerves may be used as a treatment for dry eye disease. Clinical trials should validate this approach in patients with aqueous tear deficiency, and further optimize electrical parameters for maximum clinical efficacy.

Auditory-nerve single-neuron thresholds to electrical stimulation from scala tympani electrodes.

PubMed

Parkins, C W; Colombo, J

1987-12-31

Single auditory-nerve neuron thresholds were studied in sensory-deafened squirrel monkeys to determine the effects of electrical stimulus shape and frequency on single-neuron thresholds. Frequency was separated into its components, pulse width and pulse rate, which were analyzed separately. Square and sinusoidal pulse shapes were compared. There were no or questionably significant threshold differences in charge per phase between sinusoidal and square pulses of the same pulse width. There was a small (less than 0.5 dB) but significant threshold advantage for 200 microseconds/phase pulses delivered at low pulse rates (156 pps) compared to higher pulse rates (625 pps and 2500 pps). Pulse width was demonstrated to be the prime determinant of single-neuron threshold, resulting in strength-duration curves similar to other mammalian myelinated neurons, but with longer chronaxies. The most efficient electrical stimulus pulse width to use for cochlear implant stimulation was determined to be 100 microseconds/phase. This pulse width delivers the lowest charge/phase at threshold. The single-neuron strength-duration curves were compared to strength-duration curves of a computer model based on the specific anatomy of auditory-nerve neurons. The membrane capacitance and resulting chronaxie of the model can be varied by altering the length of the unmyelinated termination of the neuron, representing the unmyelinated portion of the neuron between the habenula perforata and the hair cell. This unmyelinated segment of the auditory-nerve neuron may be subject to aminoglycoside damage. Simulating a 10 micron unmyelinated termination for this model neuron produces a strength-duration curve that closely fits the single-neuron data obtained from aminoglycoside deafened animals. Both the model and the single-neuron strength-duration curves differ significantly from behavioral threshold data obtained from monkeys and humans with cochlear implants. This discrepancy can best be explained by the involvement of higher level neurologic processes in the behavioral responses. These findings suggest that the basic principles of neural membrane function must be considered in developing or analyzing electrical stimulation strategies for cochlear prostheses if the appropriate stimulation of frequency specific populations of auditory-nerve neurons is the objective.

Pulse generator using transistors and silicon controlled rectifiers produces high current pulses with fast rise and fall times

NASA Technical Reports Server (NTRS)

Woolfson, M. G.

1966-01-01

Electrical pulse generator uses power transistors and silicon controlled rectifiers for producing a high current pulse having fast rise and fall times. At quiescent conditions, the standby power consumption of the circuit is equal to zero.

Ultrafast Manipulation of Magnetic Order with Electrical Pulses

NASA Astrophysics Data System (ADS)

Yang, Yang

During the last 30 years spintronics has been a very rapidly expanding field leading to lots of new interesting physics and applications. As with most technology-oriented fields, spintronics strives to control devices with very low energy consumption and high speed. The combination of spin and electronics inherent to spintronics directly tackles energy efficiency, due to the non-volatility of magnetism. However, speed of operation of spintronic devices is still rather limited ( nanoseconds), due to slow magnetization precessional frequencies. Ultrafast magnetism (or opto-magnetism) is a relatively new field that has been very active in the last 20 years. The main idea is that intense femtosecond laser pulses can be used in order to manipulate the magnetization at very fast time-scales ( 100 femtoseconds). However, the use of femtosecond lasers poses great application challenges such as diffraction limited optical spot sizes which hinders device density, and bulky and expensive integration of femtosecond lasers into devices. In this thesis, our efforts to combine ultrafast magnetism and spintronics are presented. First, we show that the magnetization of ferrimagnetic GdFeCo films can be switched by picosecond electronic heat current pulses. This result shows that a non-thermal distribution of electrons directly excited by laser is not necessary for inducing ultrafast magnetic dynamics. Then, we fabricate photoconductive switch devices on a LT-GaAs substrate, to generate picosecond electrical pulses. Intense electrical pulses with 10ps (FWHM) duration and peak current up to 3A can be generated and delivered into magnetic films. Distinct magnetic dynamics in CoPt films are found between direct optical heating and electrical heating. More importantly, by delivering picosecond electrical pulses into GdFeCo films, we are able to deterministically reverse the magnetization of GdFeCo within 10ps. This is more than one order of magnitude faster than any other electrically controlled magnetic switching. Our results present a fundamentally new switching mechanism electrically, without requirement for any spin polarized current or spin transfer/orbit torques. Our discovery that ultrafast magnetization switching can be achieved with electrical pulses will launch a new frontier of spintronics science and herald a new generation of spintronic devices that operate at high speed with low energy consumption. At last, to push ultrafast spintronics to practical use, ultrafast switching of a ferromagnetic film is desired. By exploiting the exchange interaction between GdFeCo and ferromagnetic Co/Pt layer, we achieved ultrafast (sub 10ps) switching of ferromagnetic film with a single laser pulse. This result will open up the possibility to control ferromagnetic materials at ultrafast time scale, critical for practical applications.

In vivo real-time monitoring system of electroporation mediated control of transdermal and topical drug delivery.

PubMed

Blagus, Tanja; Markelc, Bostjan; Cemazar, Maja; Kosjek, Tina; Preat, Veronique; Miklavcic, Damijan; Sersa, Gregor

2013-12-28

Electroporation (EP) is a physical method for the delivery of molecules into cells and tissues, including the skin. In this study, in order to control the degree of transdermal and topical drug delivery, EP at different amplitudes of electric pulses was evaluated. A new in vivo real-time monitoring system based on fluorescently labeled molecules was developed, for the quantification of transdermal and topical drug delivery. EP of the mouse skin was performed with new non-invasive multi-array electrodes, delivering different amplitudes of electric pulses ranging from 70 to 570 V, between the electrode pin pairs. Patches, soaked with 4 kDa fluorescein-isothiocyanate labeled dextran (FD), doxorubicin (DOX) or fentanyl (FEN), were applied to the skin before and after EP. The new monitoring system was developed based on the delivery of FD to and through the skin. FD relative quantity was determined with fluorescence microscopy imaging, in the treated region of the skin for topical delivery and in a segment of the mouse tail for transdermal delivery. The application of electric pulses for FD delivery resulted in enhanced transdermal delivery. Depending on the amplitude of electric pulses, it increased up to the amplitude of 360 V, and decreased at higher amplitudes (460 and 570 V). Topical delivery steadily enhanced with increasing the amplitude of the delivered electric pulses, being even higher than after tape stripping used as a positive control. The non-invasive monitoring of the delivery of DOX, a fluorescent chemotherapeutic drug, qualitatively and quantitatively confirmed the effects of EP at 360 and 570 V pulse amplitudes on topical and transdermal drug delivery. Delivery of FEN at 360 and 570 V pulse amplitudes verified the observed effects as obtained with FD and DOX, by the measured physiological responses of the mice as well as FEN plasma concentration. This study demonstrates that with the newly developed non-invasive multi-array electrodes and with the varying electric pulse amplitude, the amount of topical and transdermal drug delivery to the skin can be controlled. Furthermore, the newly developed monitoring system provides a tool for rapid real-time determination of both, transdermal and topical delivery, when the delivered molecule is fluorescent. © 2013 Elsevier B.V. All rights reserved.

Experimental study of atmospheric-pressure micro-plasmas for the ambient sampling of conductive materials

NASA Astrophysics Data System (ADS)

Duan, Zhengchao; He, Feng; Si, Xinlu; Bradley, James W.; Ouyang, Jiting

2018-02-01

Conductive solid material sampling by micro-plasma under ambient atmosphere was studied experimentally. A high-voltage pulse generator was utilized to drive discharge between a tungsten needle and metal samples. The effects of pulse width on discharge, micro-plasma and sampling were investigated. The electrical results show that two discharge current pulses can be formed in one voltage pulse. The duration of the first current pulse is of the order of 100 ns. The duration of the second current pulse depends on the width of the voltage pulse. The electrical results also show that arc micro-plasma was generated during both current pulses. The results of the emission spectra of different sampled materials indicate that the relative emission intensity of elemental metal ions will increase with pulse width. The excitation temperature and electron density of the arc micro-plasmas increase with the voltage pulse width, which contributes to the increase of relative emission intensity of metal ions. The optical images and energy dispersive spectroscopy results of the sampling spots on metal surfaces indicate that discharge with a short voltage pulse can generate a small sputtering crater.

Missile’s Guidance Head Anti-Nuclear Electromagnetic Pulse Reinforcement,

DTIC Science & Technology

1996-11-18

electromagnetic pulse bomb is one of them. This kind of nuclear bomb is mainly used to interfere or damage un-reinforced electric and electronic... electromagnetic pulse , the damaging mechanism of the nuclear electromagnetic pulse to the guidance head, and the response of electronic devices to...the nuclear electromagnetic pulse , at last introduces the guidance heads defense method to the nuclear electromagnetic pulse .

An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Jiancang; Zhang, Xibo; Li, Rui

A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW andmore » a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.« less

An 8-GW long-pulse generator based on Tesla transformer and pulse forming network.

PubMed

Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

2014-06-01

A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

Transdermal delivery of therapeutic agent

NASA Technical Reports Server (NTRS)

Kwiatkowski, Krzysztof C. (Inventor); Hayes, Ryan T. (Inventor); Magnuson, James W. (Inventor); Giletto, Anthony (Inventor)

2008-01-01

A device for the transdermal delivery of a therapeutic agent to a biological subject that includes a first electrode comprising a first array of electrically conductive microprojections for providing electrical communication through a skin portion of the subject to a second electrode comprising a second array of electrically conductive microprojections. Additionally, a reservoir for holding the therapeutic agent surrounding the first electrode and a pulse generator for providing an exponential decay pulse between the first and second electrodes may be provided. A method includes the steps of piercing a stratum corneum layer of skin with two arrays of conductive microprojections, encapsulating the therapeutic agent into biocompatible charged carriers, surrounding the conductive microprojections with the therapeutic agent, generating an exponential decay pulse between the two arrays of conductive microprojections to create a non-uniform electrical field and electrokinetically driving the therapeutic agent through the stratum corneum layer of skin.

Synergistic Combination of Electrolysis and Electroporation for Tissue Ablation.

PubMed

Stehling, Michael K; Guenther, Enric; Mikus, Paul; Klein, Nina; Rubinsky, Liel; Rubinsky, Boris

2016-01-01

Electrolysis, electrochemotherapy with reversible electroporation, nanosecond pulsed electric fields and irreversible electroporation are valuable non-thermal electricity based tissue ablation technologies. This paper reports results from the first large animal study of a new non-thermal tissue ablation technology that employs "Synergistic electrolysis and electroporation" (SEE). The goal of this pre-clinical study is to expand on earlier studies with small animals and use the pig liver to establish SEE treatment parameters of clinical utility. We examined two SEE methods. One of the methods employs multiple electrochemotherapy-type reversible electroporation magnitude pulses, designed in such a way that the charge delivered during the electroporation pulses generates the electrolytic products. The second SEE method combines the delivery of a small number of electrochemotherapy magnitude electroporation pulses with a low voltage electrolysis generating DC current in three different ways. We show that both methods can produce lesion with dimensions of clinical utility, without the need to inject drugs as in electrochemotherapy, faster than with conventional electrolysis and with lower electric fields than irreversible electroporation and nanosecond pulsed ablation.

Synergistic Combination of Electrolysis and Electroporation for Tissue Ablation

PubMed Central

Mikus, Paul; Klein, Nina; Rubinsky, Liel; Rubinsky, Boris

2016-01-01

Electrolysis, electrochemotherapy with reversible electroporation, nanosecond pulsed electric fields and irreversible electroporation are valuable non-thermal electricity based tissue ablation technologies. This paper reports results from the first large animal study of a new non-thermal tissue ablation technology that employs “Synergistic electrolysis and electroporation” (SEE). The goal of this pre-clinical study is to expand on earlier studies with small animals and use the pig liver to establish SEE treatment parameters of clinical utility. We examined two SEE methods. One of the methods employs multiple electrochemotherapy-type reversible electroporation magnitude pulses, designed in such a way that the charge delivered during the electroporation pulses generates the electrolytic products. The second SEE method combines the delivery of a small number of electrochemotherapy magnitude electroporation pulses with a low voltage electrolysis generating DC current in three different ways. We show that both methods can produce lesion with dimensions of clinical utility, without the need to inject drugs as in electrochemotherapy, faster than with conventional electrolysis and with lower electric fields than irreversible electroporation and nanosecond pulsed ablation. PMID:26866693

Electrothermal Action of the Pulse of the Current of a Short Artificial-Lightning Stroke on Test Specimens of Wires and Cables of Electric Power Objects

NASA Astrophysics Data System (ADS)

Baranov, M. I.; Rudakov, S. V.

2018-03-01

The authors have given results of investigations of the electrothermal action of aperiodic pulses of temporal shape 10/350 μs of the current of a short artificial-lightning stroke on test specimens of electric wires and cables with copper and aluminum cores and sheaths with polyvinylchloride and polyethylene insulations of power circuits of industrial electric power objects. It has been shown that the thermal stability of such wires and cables is determined by the action integral of the indicated current pulse. The authors have found the maximum permissible and critical densities of this pulse in copper and aluminum current-carrying parts of the wires and cables. High-current experiments conducted under high-voltage laboratory conditions on a unique generator of 10/350 μs pulses of an artificial-lightning current with amplitude-time parameters normalized according to the existing requirements of international and national standards and with tolerances on them have confirmed the reliability of the proposed calculated estimate for thermal lightning resistance of cabling and wiring products.

Transient luminescence induced by electrical refilling of charge carrier traps of dislocation network at hydrophilically bonded Si wafers interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bondarenko, Anton; Vyvenko, Oleg

2014-02-21

Dislocation network (DN) at hydrophilically bonded Si wafers interface is placed in space charge region (SCR) of a Schottky diode at a depth of about 150 nm from Schottky electrode for simultaneous investigation of its electrical and luminescent properties. Our recently proposed pulsed traps refilling enhanced luminescence (Pulsed-TREL) technique based on the effect of transient luminescence induced by refilling of charge carrier traps with electrical pulses is further developed and used as a tool to establish DN energy levels responsible for D1 band of dislocation-related luminescence in Si (DRL). In present work we do theoretical analysis and simulation of trapsmore » refilling kinetics dependence on refilling pulse magnitude (Vp) in two levels model: shallow and deep. The influence of initial charge state of deep level on shallow level occupation-Vp dependence is discussed. Characteristic features predicted by simulations are used for Pulsed-TREL experimental results interpretation. We conclude that only shallow (∼0.1 eV from conduction and valence band) energetic levels in the band gap participate in D1 DRL.« less

Electrothermal Action of the Pulse of the Current of a Short Artificial-Lightning Stroke on Test Specimens of Wires and Cables of Electric Power Objects

NASA Astrophysics Data System (ADS)

Baranov, M. I.; Rudakov, S. V.

2018-05-01

The authors have given results of investigations of the electrothermal action of aperiodic pulses of temporal shape 10/350 μs of the current of a short artificial-lightning stroke on test specimens of electric wires and cables with copper and aluminum cores and sheaths with polyvinylchloride and polyethylene insulations of power circuits of industrial electric power objects. It has been shown that the thermal stability of such wires and cables is determined by the action integral of the indicated current pulse. The authors have found the maximum permissible and critical densities of this pulse in copper and aluminum current-carrying parts of the wires and cables. High-current experiments conducted under high-voltage laboratory conditions on a unique generator of 10/350 μs pulses of an artificial-lightning current with amplitude-time parameters normalized according to the existing requirements of international and national standards and with tolerances on them have confirmed the reliability of the proposed calculated estimate for thermal lightning resistance of cabling and wiring products.

Electric breakdown during the pulsed current spreading in the sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasilyak, L. M., E-mail: vasilyak@ihed.ras.ru; Vetchinin, S. P.; Panov, V. A.

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.

Effects of pulsed electric fields pretreatment and drying method on drying characteristics and nutritive quality of blueberries

USDA-ARS?s Scientific Manuscript database

Fresh blueberries were pretreated with pulsed electric fields (PEF) at 2 kV/cm and then dried at 45, 60 and 75 degrees C by conventional hot air or vacuum drying. Drying characteristics and changes in contents of moisture, anthocyanin, total phenolics, vitamin C, and antioxidant activity in the blu...

Inactivation of E. coli O157:H7 and nonpathogenic E. coli in strawberry juice by pulsed electric field, sodium benzoate, potassium sorbate, and citric acid

USDA-ARS?s Scientific Manuscript database

Introduction: Current regulations require that juice processors effect a 5 log CFU/ml reduction of a target pathogen prior to distributing products. Whereas thermal pasteurization reduces the sensory characteristics of juice by altering flavor components, pulsed electric field (PEF) treatment may ...

Plasma discharge self-cleaning filtration system

DOEpatents

Cho, Young I.; Fridman, Alexander; Gutsol, Alexander F.; Yang, Yong

2014-07-22

The present invention is directed to a novel method for cleaning a filter surface using a plasma discharge self-cleaning filtration system. The method involves utilizing plasma discharges to induce short electric pulses of nanoseconds duration at high voltages. These electrical pulses generate strong Shockwaves that disintegrate and dislodge particulate matter located on the surface of the filter.

Miniature piezo electric vacuum inlet valve

DOEpatents

Keville, R.F.; Dietrich, D.D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability is disclosed. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three. 6 figs.

Nanosecond pulsed power generator for a voltage amplitude up to 300 kV and a repetition rate up to 16 Hz for fine disintegration of quartz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krastelev, E. G., E-mail: ekrastelev@yandex.ru; Sedin, A. A.; Tugushev, V. I.

2015-12-15

A generator of high-power high-voltage nanosecond pulses is intended for electrical discharge disintegration of mineral quartz and other nonconducting minerals. It includes a 320 kV Marx pulsed voltage generator, a high-voltage glycerin-insulated coaxial peaking capacitor, and an output gas spark switch followed by a load, an electric discharge disintegration chamber. The main parameters of the generator are as follows: a voltage pulse amplitude of up to 300 kV, an output impedance of ≈10 Ω, a discharge current amplitude of up to 25 kA for a half-period of 80–90 ns, and a pulse repetition rate of up to 16 Hz.

Observations of double layer-like and soliton-like structures in the ionosphere

NASA Technical Reports Server (NTRS)

Boehm, M. H.; Carlson, C. W.; Mcfadden, J.; Mozer, F. S.

1984-01-01

Two types of large electric field signatures, individual pulses and pulse trains, were observed on a sounding rocket launched into the afternoon auroral zone on January 21, 1982. The typical electric fields in the individual pulses were 50 mV/m or larger, aligned mostly parallel to B, and the corresponding potentials were at leat 100 mV (kT approximately 0.3 eV). A lower limit of 15 km/sec can be set on the velocity of these structures, indicating that they were not ion acoustic double layers. The pulse trains, each consisting of on the order of 100 pulses, were observed in close association with intense plasma frequency waves. This correlation is consistent with the interpretation of these trains as Langmuir solitons. The pulse trains correlate better with the intensity of the field-aligned currents than with the energetic electron flux.

Photoconductive circuit element reflectometer

DOEpatents

Rauscher, Christen

1990-01-01

A photoconductive reflectometer for characterizing semiconductor devices at millimeter wavelength frequencies where a first photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short first laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test. Second PCEs are connected along the transmission line to sample the signals on the transmission line when excited into conductance by short second laser light pulses, spaced apart in time a variable period from the first laser light pulses. Electronic filters connected to each of the second PCEs act as low-pass filters and remove parasitic interference from the sampled signals and output the sampled signals in the form of slowed-motion images of the signals on the transmission line.

Photoconductive circuit element reflectometer

DOEpatents

Rauscher, C.

1987-12-07

A photoconductive reflectometer for characterizing semiconductor devices at millimeter wavelength frequencies where a first photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short first laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test. Second PCEs are connected along the transmission line to sample the signals on the transmission line when excited into conductance by short second laser light pulses, spaced apart in time a determinable period from the first laser light pulses. Electronic filters connected to each of the second PCEs act as low-pass filters and remove parasitic interference from the sampled signals and output the sampled signals in the form of slowed-motion images of the signals on the transmission line. 4 figs.

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

PubMed Central

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

2016-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2001-06-25

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

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

Integrating solids and gases for attosecond pulse generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, T. J.; Monchoce, Sylvain; Zhang, Chunmei

Here, control of the field of few-cycle optical pulses has had an enormous impact on attosecond science. Subcycle pulses open the potential for non-adiabatic phase matching while concentrating the electric field so it can be used most efficiently. However, subcycle field transients have been difficult to generate. We exploit the perturbative response of a sub-100 µm thick monocrystalline quartz plate irradiated by an intense few-cycle 1.8 µm pulse, which creates a phase-controlled supercontinuum spectrum. Within the quartz, the pulse becomes space–time coupled as it generates a parallel second harmonic. Vacuum propagation naturally leads to a subcycle electric-field transient whose envelopemore » is sculpted by the carrier envelope phase of the incident radiation. We show that a second medium (either gas or solid) can generate isolated attosecond pulses in the extreme ultraviolet region. With no optical elements between the components, the process is scalable to very high energy pulses and allows the use of diverse media.« less

Integrating solids and gases for attosecond pulse generation

DOE PAGES

Hammond, T. J.; Monchoce, Sylvain; Zhang, Chunmei; ...

2017-08-21

Here, control of the field of few-cycle optical pulses has had an enormous impact on attosecond science. Subcycle pulses open the potential for non-adiabatic phase matching while concentrating the electric field so it can be used most efficiently. However, subcycle field transients have been difficult to generate. We exploit the perturbative response of a sub-100 µm thick monocrystalline quartz plate irradiated by an intense few-cycle 1.8 µm pulse, which creates a phase-controlled supercontinuum spectrum. Within the quartz, the pulse becomes space–time coupled as it generates a parallel second harmonic. Vacuum propagation naturally leads to a subcycle electric-field transient whose envelopemore » is sculpted by the carrier envelope phase of the incident radiation. We show that a second medium (either gas or solid) can generate isolated attosecond pulses in the extreme ultraviolet region. With no optical elements between the components, the process is scalable to very high energy pulses and allows the use of diverse media.« less

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

NASA Astrophysics Data System (ADS)

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.

Discharge pulse phenomenology

NASA Technical Reports Server (NTRS)

Frederickson, A. R.

1985-01-01

A model was developed which places radiation induced discharge pulse results into a unified conceptual framework. Only two phenomena are required to interpret all space and laboratory results: (1) radiation produces large electrostatic fields inside insulators via the trapping of a net space charge density; and (2) the electrostatic fields initiate discharge streamer plasmas similar to those investigated in high voltage electrical insulation materials; these streamer plasmas generate the pulsing phenomena. The apparent variability and diversity of results seen is an inherent feature of the plasma streamer mechanism acting in the electric fields which is created by irradiation of the dielectrics. The implications of the model are extensive and lead to constraints over what can be done about spacecraft pulsing.

High intensity, plasma-induced electron emission from large area carbon nanotube array cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao Qingliang; Yang Ya; Qi Junjie

2010-02-15

The plasma-induced electron emission properties of large area carbon nanotube (CNT) array cathodes under different pulse electric fields were investigated. The formation and expansion of cathode plasmas were proved; in addition, the cathodes have higher emission current in the double-pulse mode than that in the single-pulse mode due to the expansion of plasma. Under the double-pulse electric field of 8.16 V/mum, the plasma's expansion velocity is about 12.33 cm/mus and the highest emission current density reached 107.72 A/cm{sup 2}. The Cerenkov radiation was used to diagnose the distribution of electron beams, and the electron beams' generating process was plasma-induced emission.

Numerical Simulation of Non-Thermal Food Preservation

NASA Astrophysics Data System (ADS)

Rauh, C.; Krauss, J.; Ertunc, Ö.; Delgado, a.

2010-09-01

Food preservation is an important process step in food technology regarding product safety and product quality. Novel preservation techniques are currently developed, that aim at improved sensory and nutritional value but comparable safety than in conventional thermal preservation techniques. These novel non-thermal food preservation techniques are based for example on high pressures up to one GPa or pulsed electric fields. in literature studies the high potential of high pressures (HP) and of pulsed electric fields (PEF) is shown due to their high retention of valuable food components as vitamins and flavour and selective inactivation of spoiling enzymes and microorganisms. for the design of preservation processes based on the non-thermal techniques it is crucial to predict the effect of high pressure and pulsed electric fields on the food components and on the spoiling enzymes and microorganisms locally and time-dependent in the treated product. Homogenous process conditions (especially of temperature fields in HP and PEF processing and of electric fields in PEF) are aimed at to avoid the need of over-processing and the connected quality loss and to minimize safety risks due to under-processing. the present contribution presents numerical simulations of thermofluiddynamical phenomena inside of high pressure autoclaves and pulsed electric field treatment chambers. in PEF processing additionally the electric fields are considered. Implementing kinetics of occurring (bio-) chemical reactions in the numerical simulations of the temperature, flow and electric fields enables the evaluation of the process homogeneity and efficiency connected to different process parameters of the preservation techniques. Suggestions to achieve safe and high quality products are concluded out of the numerical results.

Pulsed Electric Propulsion Thrust Stand Calibration Method

NASA Technical Reports Server (NTRS)

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

2011-01-01

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

Laser lift-off scribing of the CZTSe thin-film solar cells at different pulse durations

DOE PAGES

Markauskas, Edgaras; Gečys, Paulius; Repins, Ingrid; ...

2017-04-27

Here, the transition to fully sized solar modules requires additional three-step laser structuring processes to preserve small-scale cell efficiencies over the large areas. The adjacent cell isolation (the P3 scribe) was found to be the most sensitive process in the case of laser induced damage. The laser induced layer lift-off mechanism seems to be a very attractive process for the P3 patterning, since almost all the laser affected material is removed by mechanical spallation. However, a laser induced layer spallation behavior together with scribe electrical validation under the different laser pulse durations was not investigated extensively in the past. Therefore,more » we report our novel results on the P2 and P3 laser lift-off processing of the Cu 2ZnSn(S, Se 4) (CZTSe) thin-film solar cells covering the pulse duration range from 300 fs to 60 ps. Shorter sub-ps pulses enabled us to process smaller P2 and P3 craters, although the lift-off threshold fluences were higher compared to the longer ps pulses. In the case of the layer lift-off, the laser radiation had to penetrate through the layer stack down to the CZTSe/Mo interface. At shorter sub-ps pulses, the nonlinear effects triggered absorption of the laser radiation in the bulk of the material, resulting in increased damage of the CZTSe layer. The Raman measurements confirmed the CZTSe surface stoichiometry changes for shorter pulses. Furthermore, shorter pulses induced higher electrical conductivity of a scribe, resulting in lower photo-electrical efficiency during the mini-module simulation. In the case of the P3 lift-off scribing, the 10 ps pulses were more favorable than shorter femtosecond pulses.« less

Laser lift-off scribing of the CZTSe thin-film solar cells at different pulse durations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Markauskas, Edgaras; Gečys, Paulius; Repins, Ingrid

Here, the transition to fully sized solar modules requires additional three-step laser structuring processes to preserve small-scale cell efficiencies over the large areas. The adjacent cell isolation (the P3 scribe) was found to be the most sensitive process in the case of laser induced damage. The laser induced layer lift-off mechanism seems to be a very attractive process for the P3 patterning, since almost all the laser affected material is removed by mechanical spallation. However, a laser induced layer spallation behavior together with scribe electrical validation under the different laser pulse durations was not investigated extensively in the past. Therefore,more » we report our novel results on the P2 and P3 laser lift-off processing of the Cu 2ZnSn(S, Se 4) (CZTSe) thin-film solar cells covering the pulse duration range from 300 fs to 60 ps. Shorter sub-ps pulses enabled us to process smaller P2 and P3 craters, although the lift-off threshold fluences were higher compared to the longer ps pulses. In the case of the layer lift-off, the laser radiation had to penetrate through the layer stack down to the CZTSe/Mo interface. At shorter sub-ps pulses, the nonlinear effects triggered absorption of the laser radiation in the bulk of the material, resulting in increased damage of the CZTSe layer. The Raman measurements confirmed the CZTSe surface stoichiometry changes for shorter pulses. Furthermore, shorter pulses induced higher electrical conductivity of a scribe, resulting in lower photo-electrical efficiency during the mini-module simulation. In the case of the P3 lift-off scribing, the 10 ps pulses were more favorable than shorter femtosecond pulses.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Catrin F., E-mail: williamscf@cardiff.ac.uk; School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales; Geroni, Gilles M.

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. Separatedmore » 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.« less

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

NASA Astrophysics Data System (ADS)

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.

Pulsed Laser Deposition of High Temperature Protonic Films

NASA Technical Reports Server (NTRS)

Dynys, Fred W.; Berger, M. H.; Sayir, Ali

2006-01-01

Pulsed laser deposition has been used to fabricate nanostructured BaCe(0.85)Y(0.15)O3- sigma) films. Protonic conduction of fabricated BaCe(0.85)Y(0.15)O(3-sigma) films was compared to sintered BaCe(0.85)Y(0.15)O(3-sigma). Sintered samples and laser targets were prepared by sintering BaCe(0.85)Y(0.15)O(3-sigma) powders derived by solid state synthesis. Films 1 to 8 micron thick were deposited by KrF excimer laser on porous Al2O3 substrates. Thin films were fabricated at deposition temperatures of 700 to 950 C at O2 pressures up to 200 mTorr using laser pulse energies of 0.45 - 0.95 J. Fabricated films were characterized by X-ray diffraction, electron microscopy and electrical impedance spectroscopy. Single phase BaCe(0.85)Y(0.15)O(3-sigma) films with a columnar growth morphology are observed with preferred crystal growth along the [100] or [001] direction. Results indicate [100] growth dependence upon laser pulse energy. Electrical conductivity of bulk samples produced by solid state sintering and thin film samples were measured over a temperature range of 100 C to 900 C. Electrical conduction behavior was dependent upon film deposition temperature. Maximum conductivity occurs at deposition temperature of 900 oC; the electrical conductivity exceeds the sintered specimen. All other deposited films exhibit a lower electrical conductivity than the sintered specimen. Activation energy for electrical conduction showed dependence upon deposition temperature, it varied

Nanosecond electric pulses modulate skeletal muscle calcium dynamics and contraction

NASA Astrophysics Data System (ADS)

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.

Waveform synthesizer

DOEpatents

Franks, Larry A.; Nelson, Melvin A.

1981-01-01

A method of producing optical and electrical pulses of desired shape. An optical pulse of arbitrary but defined shape illuminates one end of an array of optical fiber waveguides of differing lengths to time differentiate the input pulse. The optical outputs at the other end of the array are combined to form a synthesized pulse of desired shape.

[Rehabilitative treatment of patients with ureterolithiasis using pulsed vacuum depression, pulsed low-frequency electric current, and radon therapy].

PubMed

Li, A A; Karpukhin, I V; Korchazhkina, N B; Gusarov, I I; Kotenko, K V; Slepushkina, T G; Dubovskiĭ, A V

2009-01-01

The authors report results of the treatment of 60 patients with ureterolithiasis using a combination of pulsed vacuum depression (local vibrotherapy), low-frequency pulsed (alternating sinusoidal) current, radon water and radon baths. Clinical efficiency of combined therapy is estimated at 93.3%.

Irreversible electroporation ablation area enhanced by synergistic high- and low-voltage pulses.

PubMed

Yao, Chenguo; Lv, Yanpeng; Dong, Shoulong; Zhao, Yajun; Liu, Hongmei

2017-01-01

Irreversible electroporation (IRE) produced by a pulsed electric field can ablate tissue. In this study, we achieved an enhancement in ablation area by using a combination of short high-voltage pulses (HVPs) to create a large electroporated area and long low-voltage pulses (LVPs) to ablate the electroporated area. The experiments were conducted in potato tuber slices. Slices were ablated with an array of four pairs of parallel steel electrodes using one of the following four electric pulse protocols: HVP, LVP, synergistic HVP+LVP (SHLVP) or LVP+HVP. Our results showed that the SHLVPs more effectively necrotized tissue than either the HVPs or LVPs, even when the SHLVP dose was the same as or lower than the HVP or LVP doses. The HVP and LVP order mattered and only HVPs+LVPs (SHLVPs) treatments increased the size of the ablation zone because the HVPs created a large electroporated area that was more susceptible to the subsequent LVPs. Real-time temperature change monitoring confirmed that the tissue was non-thermally ablated by the electric pulses. Theoretical calculations of the synergistic effects of the SHLVPs on tissue ablation were performed. Our proposed SHLVP protocol provides options for tissue ablation and may be applied to optimize the current clinical IRE protocols.

Irreversible electroporation ablation area enhanced by synergistic high- and low-voltage pulses

PubMed Central

2017-01-01

Irreversible electroporation (IRE) produced by a pulsed electric field can ablate tissue. In this study, we achieved an enhancement in ablation area by using a combination of short high-voltage pulses (HVPs) to create a large electroporated area and long low-voltage pulses (LVPs) to ablate the electroporated area. The experiments were conducted in potato tuber slices. Slices were ablated with an array of four pairs of parallel steel electrodes using one of the following four electric pulse protocols: HVP, LVP, synergistic HVP+LVP (SHLVP) or LVP+HVP. Our results showed that the SHLVPs more effectively necrotized tissue than either the HVPs or LVPs, even when the SHLVP dose was the same as or lower than the HVP or LVP doses. The HVP and LVP order mattered and only HVPs+LVPs (SHLVPs) treatments increased the size of the ablation zone because the HVPs created a large electroporated area that was more susceptible to the subsequent LVPs. Real-time temperature change monitoring confirmed that the tissue was non-thermally ablated by the electric pulses. Theoretical calculations of the synergistic effects of the SHLVPs on tissue ablation were performed. Our proposed SHLVP protocol provides options for tissue ablation and may be applied to optimize the current clinical IRE protocols. PMID:28253331

Giant lipid vesicles under electric field pulses assessed by non invasive imaging.

PubMed

Mauroy, Chloé; Portet, Thomas; Winterhalder, Martin; Bellard, Elisabeth; Blache, Marie-Claire; Teissié, Justin; Zumbusch, Andreas; Rols, Marie-Pierre

2012-10-01

We present experimental results regarding the effects of electric pulses on giant unilamellar vesicles (GUVs). We have used phase contrast and coherent anti-Stokes Raman scattering (CARS) microscopy as relevant optical approaches to gain insight into membrane changes under electropermeabilization. No addition of exogenous molecules (lipid analogue, fluorescent dye) was needed. Therefore, experiments were performed on pure lipid systems avoiding possible artefacts linked to their use. Structural membrane changes were assessed by loss of contrast inside the GUVs due to sucrose and glucose mixing. Our observations, performed at the single vesicle level, indicate these changes are under the control of the number of pulses and field intensity. Larger number of pulses enhances membrane alterations. A threshold value of the field intensity must be applied to allow exchange of molecules between GUVs and the external medium. This threshold depends on the size of the vesicles, the larger GUVs being affected at lower electric field strengths than the smaller ones. Our experimental data are well described by a simple model in which molecule entry is driven by direct exchange. The CARS microscopic study of the effect of pulse duration confirms that pulses, in the ms time range, induce loss of lipids and membrane deformations facing the electrodes. Copyright © 2012 Elsevier B.V. All rights reserved.

How transient alterations of organelles in mammalian cells submitted to electric field may explain some aspects of gene electrotransfer process.

PubMed

Phez, Emilie; Gibot, Laure; Rols, Marie-Pierre

2016-12-01

Electric pulses can be used to transiently permeabilize the cell plasma membrane. This method is nowadays employed as a safe and efficient means to deliver therapeutic molecules into target cells and tissues. Despite the large bulk of literature on this topic, there is a lack of knowledge about the mechanism(s) of molecule delivery. The behavior of the cells both while the field is on and after its application is indeed not well described. Questions about cell organelle alterations remain unanswered. We report here evidence for a number of ultrastructural alterations in mammalian cells exposed to electric pulses. Specifically, CHO cells were subjected to trains of 10 pulses lasting 5ms using an electric field of 800V/cm, i.e. under conditions leading both to membrane permeabilization, gene transfer and expression. Cells were observed to undergo morphological alterations of the mitochondria and nucleus. These modifications, detected in the minutes following pulse delivery, were transient. They may have direct consequences on molecule delivery and therefore may explain various aspects of the mechanisms of DNA electrotransfer. Copyright © 2016 Elsevier B.V. All rights reserved.

Calorimetric system and method

DOEpatents

Gschneidner, K.A. Jr.; Pecharsky, V.K.; Moorman, J.O.

1998-09-15

Apparatus is described for measuring heat capacity of a sample where a series of measurements are taken in succession comprises a sample holder in which a sample to be measured is disposed, a temperature sensor and sample heater for providing a heat pulse thermally connected to the sample, and an adiabatic heat shield in which the sample holder is positioned and including an electrical heater. An electrical power supply device provides an electrical power output to the sample heater to generate a heat pulse. The electrical power from a power source to the heat shield heater is adjusted by a control device, if necessary, from one measurement to the next in response to a sample temperature-versus-time change determined before and after a previous heat pulse to provide a subsequent sample temperature-versus-time change that is substantially linear before and after the subsequent heat pulse. A temperature sensor is used and operable over a range of temperatures ranging from approximately 3K to 350K depending upon the refrigerant used. The sample optionally can be subjected to dc magnetic fields such as from 0 to 12 Tesla (0 to 120 kOe). 18 figs.

Room-temperature coupling between electrical current and nuclear spins in OLEDs

NASA Astrophysics Data System (ADS)

Malissa, H.; Kavand, M.; Waters, D. P.; van Schooten, K. J.; Burn, P. L.; Vardeny, Z. V.; Saam, B.; Lupton, J. M.; Boehme, C.

2014-09-01

The effects of external magnetic fields on the electrical conductivity of organic semiconductors have been attributed to hyperfine coupling of the spins of the charge carriers and hydrogen nuclei. We studied this coupling directly by implementation of pulsed electrically detected nuclear magnetic resonance spectroscopy in organic light-emitting diodes (OLEDs). The data revealed a fingerprint of the isotope (protium or deuterium) involved in the coherent spin precession observed in spin-echo envelope modulation. Furthermore, resonant control of the electric current by nuclear spin orientation was achieved with radiofrequency pulses in a double-resonance scheme, implying current control on energy scales one-millionth the magnitude of the thermal energy.

Real time determination of the laser ablated mass by means of electric field-perturbation measurement

NASA Astrophysics Data System (ADS)

Pacheco, P.; Álvarez, J.; Sarmiento, R.; Bredice, F.; Sánchez-Aké, C.; Villagrán-Muniz, M.; Palleschi, V.

2018-04-01

A Nd:YAG ns-pulsed laser was used to ablate Al, Cd and Zn targets, which were placed between the plates of a planar charged capacitor. The plasma generates a transient redistribution of the electrical charges on the plates that can be measured as a voltage drop across a resistor connected to the ground plate. This signal is proportional to the capacitor applied voltage, the distance between the plates and the total number of ions produced in the ablation process which in turn is related to the laser energy and the ablated mass. After a series of pulses, the targets were weighed on a thermogravimetric balance to measure the ablated mass. Our results show that the electrical signal measured on the resistor is univocally related to the ablated mass from the target. Therefore, after a proper calibration depending on the material and the experimental geometry, the electrical signal can be used for real time quantitative measurement of the ablated mass in pulsed laser generated plasma experiments. The experiments were repeated on an aluminum target, with and without the presence of the external electric field in order to determine the possible influence of the applied electric field on the ablated mass.

Autonomous data transmission apparatus

DOEpatents

Kotlyar, Oleg M.

1997-01-01

A autonomous borehole data transmission apparatus for transmitting measurement data from measuring instruments at the downhole end of a drill string by generating pressure pulses utilizing a transducer longitudinally responsive to magnetic field pulses caused by electrical pulses corresponding to the measured downhole parameters.

Ultrafast magnetization reversal by picosecond electrical pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yang; Wilson, Richard B.; Gorchon, Jon

The field of spintronics involves the study of both spin and charge transport in solid-state devices. Ultrafast magnetism involves the use of femtosecond laser pulses to manipulate magnetic order on subpicosecond time scales. Here, we unite these phenomena by using picosecond charge current pulses to rapidly excite conduction electrons in magnetic metals. We observe deterministic, repeatable ultrafast reversal of the magnetization of a GdFeCo thin film with a single sub–10-ps electrical pulse. The magnetization reverses in ~10 ps, which is more than one order of magnitude faster than any other electrically controlled magnetic switching, and demonstrates a fundamentally new electricalmore » switching mechanism that does not require spin-polarized currents or spin-transfer/orbit torques. The energy density required for switching is low, projecting to only 4 fJ needed to switch a (20 nm) 3 cell. This discovery introduces a new field of research into ultrafast charge current–driven spintronic phenomena and devices.« less

Electrical Characterization of Temperature Dependent Resistive Switching in Pr0.7C0.3MnO3

NASA Astrophysics Data System (ADS)

Lopez, Melinda; Salvo, Christopher; Tsui, Stephen

2012-02-01

Resistive switching offers a non-volatile and reversible means to possibly create a more physically compact yet larger access capacity in memory technology. While there has been a great deal of research conducted on this electrical property in oxide materials, there is still more to be learned about this at both high voltage pulsing and cryogenic temperatures. In this work, the electrical properties of a PCMO-metal interface switch were examined after application of voltage pulsing varying from 100 V to 1000 V and at temperatures starting at 293 K and lowered to 80 K. What was discovered was that below temperatures of 150 K, the resistive switching began to decrease across all voltage pulsing and that at all temperatures before this cessation, the change in resistive switching increased with higher voltage pulsing. We suggest that a variable density of charge traps at the interface is a likely mechanism, and work continues to extract more details.

Effects of High-Rate Pulse Trains on Electrode Discrimination in Cochlear Implant Users

PubMed Central

Runge-Samuelson, Christina L.

2009-01-01

Overcoming issues related to abnormally high neural synchrony in response to electrical stimulation is one aspect in improving hearing with a cochlear implant. Desynchronization of electrical stimuli have shown benefits in neural encoding of electrical signals and improvements in psychophysical tasks. In the present study, 10 participants with either CII or HiRes 90k Advanced Bionics devices were tested for the effects of desynchronizing constant-amplitude high-rate (5,000 Hz) pulse trains on electrode discrimination of sinusoidal stimuli (1,000 Hz). When averaged across the sinusoidal dynamic range, overall improvements in electrode discrimination with high-rate pulses were found for 8 of 10 participants. This effect was significant for the group (p = .003). Nonmonotonic patterns of electrode discrimination as a function of sinusoidal stimulation level were observed. By providing additional spectral channels, it is possible that clinical implementation of constant-amplitude high-rate pulse trains in a signal processing strategy may improve performance with the device. PMID:19447763

Ultrafast magnetization reversal by picosecond electrical pulses

DOE PAGES

Yang, Yang; Wilson, Richard B.; Gorchon, Jon; ...

2017-11-03

The field of spintronics involves the study of both spin and charge transport in solid-state devices. Ultrafast magnetism involves the use of femtosecond laser pulses to manipulate magnetic order on subpicosecond time scales. Here, we unite these phenomena by using picosecond charge current pulses to rapidly excite conduction electrons in magnetic metals. We observe deterministic, repeatable ultrafast reversal of the magnetization of a GdFeCo thin film with a single sub–10-ps electrical pulse. The magnetization reverses in ~10 ps, which is more than one order of magnitude faster than any other electrically controlled magnetic switching, and demonstrates a fundamentally new electricalmore » switching mechanism that does not require spin-polarized currents or spin-transfer/orbit torques. The energy density required for switching is low, projecting to only 4 fJ needed to switch a (20 nm) 3 cell. This discovery introduces a new field of research into ultrafast charge current–driven spintronic phenomena and devices.« less

On the Origin of Pulsations of Sub-THz Emission from Solar Flares

NASA Astrophysics Data System (ADS)

Zaitsev, V. V.; Stepanov, A. V.; Kaufmann, P.

2014-08-01

We propose a model to explain fast pulsations in sub-THz emission from solar flares. The model is based on the approach of a flaring loop as an equivalent electric circuit and explains the pulse-repetition rate, the high-quality factor, Q≥103, low modulation depth, pulse synchronism at different frequencies, and the dependence of the pulse-repetition rate on the emission flux, observed by Kaufmann et al. ( Astrophys. J. 697, 420, 2009). We solved the nonlinear equation for electric current oscillations using a Van der Pol method and found the steady-state value for the amplitude of the current oscillations. Using the pulse rate variation during the flare on 4 November 2003, we found a decrease of the electric current from 1.7×1012 A in the flare maximum to 4×1010 A just after the burst. Our model is consistent with the plasma mechanism of sub-THz emission suggested recently by Zaitsev, Stepanov, and Melnikov ( Astron. Lett. 39, 650, 2013).

Submicrosecond phospholipid dynamics using a long-lived fluorescence emission anisotropy probe.

PubMed Central

Davenport, L; Targowski, P

1996-01-01

The use of the long-lived fluorescence probe coronene (mean value of tau(FL) approximately 200 ns) is described for investigating submicrosecond lipid dynamics in DPPC model bilayer systems occurring below the lipid phase transition. Time-resolved fluorescence emission anisotropy decay profiles, measures as a function of increasing temperature toward the lipid-phase transition temperature (T(C)), for coronene-labeled DPPC small unilamellar vesicles (SUVs), are best described in most cases by three rotational decay components (phi(i = 3)). We have interpreted these data using two dynamic lipid bilayer models. In the first, a compartmental model, the long correlation time (phi(N)) is assigned to immobilized coronene molecules located in "gel-like" or highly ordered lipid phases (S-->1) of the bilayer, whereas a second fast rotational time (phi(F) approximately 2-5 ns) is associated with probes residing in more "fluid-like" regions (with corresponding lower ordering, S-->0). Interests here have focused on the origins of an intermediate correlation time (50-100 ns), the associated amplitude (beta(G)) of which increases with increasing temperature. Such behavior suggests a changing rotational environment surrounding the coronene molecules, arising from fluidization of gel lipid. The observed effective correlation time (phi(EFF)) thus reflects a discrete gel-fluid lipid exchange rate (k(FG)). A refinement of the compartmental model invokes a distribution of gel-fluid exchange rates (d(S,T)) corresponding to a distribution of lipid order parameters and is based on an adapted Landau expression for describing "gated" packing fluctuations. A total of seven parameters (five thermodynamic quantities, defined by the free energy versus temperature expansion; one gating parameter (gamma) defining a cooperative "melting" requirement; one limiting diffusion rate (or frequency factor: d(infinity))) suffice to predict complete anisotropy decay curves measured for coronene at several temperatures below the phospholipid T(C). The thermodynamic quantities are associated with the particular lipid of interest (in this case DPPC) and have been determined previously from ultrasound studies, thus representing fixed constants. Hence resolved variables are r(O), temperature-dependent gate parameters (gamma), and limiting diffusion rates (d(infinity)). This alternative distribution model is attractive because it provides a general probe-independent expression for distributed lipid fluctuation-induced probe rotational rates occurring within bilayer membranes below the phospholipid phase transition on the submicrosecond time scale. PMID:8889160

Losses analysis of soft magnetic ring core under sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) excitations

NASA Astrophysics Data System (ADS)

Gao, Hezhe; Li, Yongjian; Wang, Shanming; Zhu, Jianguo; Yang, Qingxin; Zhang, Changgeng; Li, Jingsong

2018-05-01

Practical core losses in electrical machines differ significantly from those experimental results using the standardized measurement method, i.e. Epstein Frame method. In order to obtain a better approximation of the losses in an electrical machine, a simulation method considering sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) waveforms is proposed. The influence of the pulse width modulation (PWM) parameters on the harmonic components in SPWM and SVPWM is discussed by fast Fourier transform (FFT). Three-level SPWM and SVPWM are analyzed and compared both by simulation and experiment. The core losses of several ring samples magnetized by SPWM, SVPWM and sinusoidal alternating current (AC) are obtained. In addition, the temperature rise of the samples under SPWM, sinusoidal excitation are analyzed and compared.

Ultrasonic unipolar pulse/echo instrument

DOEpatents

Hughes, M.J.; Hsu, D.K.; Thompson, D.O.; Wormley, S.J.

1993-04-06

An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Ultrasonic unipolar pulse/echo instrument

DOEpatents

Hughes, Michael S.; Hsu, David K.; Thompson, Donald O.; Wormley, Samuel J.

1993-01-01

An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Pulsed Corona Discharge Generated By Marx Generator

NASA Astrophysics Data System (ADS)

Sretenovic, G. B.; Obradovic, B. M.; Kovacevic, V. V.; Kuraica, M. M.; Puric J.

2010-07-01

The pulsed plasma has a significant role in new environmental protection technologies. As a part of a pulsed corona system for pollution control applications, Marx type repetitive pulse generator was constructed and tested in arrangement with wire-plate corona reactor. We performed electrical measurements, and obtained voltage and current signals, and also power and energy delivered per pulse. Ozone formation by streamer plasma in air was chosen to monitor chemical activity of the pulsed corona discharge.

Distributed electrical time domain reflectometry (ETDR) structural sensors: design models and proof-of-concept experiments

NASA Astrophysics Data System (ADS)

Stastny, Jeffrey A.; Rogers, Craig A.; Liang, Chen

1993-07-01

A parametric design model has been created to optimize the sensitivity of the sensing cable in a distributed sensing system. The system consists of electrical time domain reflectometry (ETDR) signal processing equipment and specially designed sensing cables. The ETDR equipment sends a high-frequency electric pulse (in the giga hertz range) along the sensing cable. Some portion of the electric pulse will be reflected back to the ETDR equipment as a result of the variation of the cable impedance. The electric impedance variation in the sensing cable can be related to its mechanical deformation, such as cable elongation (change in the resistance), shear deformation (change in the capacitance), corrosion of the cable or the materials around the cable (change in inductance and capacitance), etc. The time delay, amplitude, and shape of the reflected pulse provides the means to locate, determine the magnitude, and indicate the nature of the change in the electrical impedance, which is then related to the distributed structural deformation. The sensing cables are an essential part of the health-monitoring system. By using the parametric design model, the optimum cable parameters can be determined for specific deformation. Proof-of-concept experiments also are presented in the paper to demonstrate the utility of an electrical TDR system in distributed sensing applications.

Liberation of a pinned spiral wave by a rotating electric pulse

NASA Astrophysics Data System (ADS)

Chen, Jiang-Xing; Peng, Liang; Ma, Jun; Ying, He-Ping

2014-08-01

Spiral waves may be pinned to anatomical heterogeneities in the cardiac tissue, which leads to monomorphic ventricular tachycardia. Wave emission from heterogeneities (WEH) induced by electric pulses in one direction (EP) is a promising method for liberating such waves by using heterogeneities as internal virtual pacing sites. Here, based on the WEH effect, a new mechanism of liberation by means of a rotating electric pulse (REP) is proposed in a generic model of excitable media. Compared with the EP, the REP has the advantage of opening wider time window to liberate pinned spiral. The influences of rotating direction and frequency of the REP, and the radius of the obstacles on this new mechanism are studied. We believe this strategy may improve manipulations with pinned spiral waves in heart experiments.

System and Method for Tensioning a Robotically Actuated Tendon

NASA Technical Reports Server (NTRS)

Reiland, Matthew J. (Inventor); Diftler, Myron A. (Inventor)

2013-01-01

A tendon tensioning system includes a tendon having a proximal end and a distal end, an actuator, and a motor controller. The actuator may include a drive screw and a motor, and may be coupled with the proximal end of the tendon and configured to apply a tension through the tendon in response to an electrical current. The motor controller may be electrically coupled with the actuator, and configured to provide an electrical current having a first amplitude to the actuator until a stall tension is achieved through the tendon; provide a pulse current to the actuator following the achievement of the stall tension, where the amplitude of the pulse current is greater than the first amplitude, and return the motor to a steady state holding current following the conclusion of the pulse current.

Picosecond electric-field-induced threshold switching in phase-change materials [THz-induced threshold switching and crystallization of phase-change materials

DOE PAGES

Zalden, Peter; Shu, Michael J.; Chen, Frank; ...

2016-08-05

Many chalcogenide glasses undergo a breakdown in electronic resistance above a critical field strength. Known as threshold switching, this mechanism enables field-induced crystallization in emerging phase-change memory. Purely electronic as well as crystal nucleation assisted models have been employed to explain the electronic breakdown. Here, picosecond electric pulses are used to excite amorphous Ag 4In 3Sb 67Te 26. Field-dependent reversible changes in conductivity and pulse-driven crystallization are observed. The present results show that threshold switching can take place within the electric pulse on subpicosecond time scales—faster than crystals can nucleate. As a result, this supports purely electronic models of thresholdmore » switching and reveals potential applications as an ultrafast electronic switch.« less

Time-to-space mapping of femtosecond pulses.

PubMed

Nuss, M C; Li, M; Chiu, T H; Weiner, A M; Partovi, A

1994-05-01

We report time-to-space mapping of femtosecond light pulses in a temporal holography setup. By reading out a temporal hologram of a short optical pulse with a continuous-wave diode laser, we accurately convert temporal pulse-shape information into a spatial pattern that can be viewed with a camera. We demonstrate real-time acquisition of electric-field autocorrelation and cross correlation of femtosecond pulses with this technique.

Prediction and control of neural responses to pulsatile electrical stimulation

NASA Astrophysics Data System (ADS)

Campbell, Luke J.; Sly, David James; O'Leary, Stephen John

2012-04-01

This paper aims to predict and control the probability of firing of a neuron in response to pulsatile electrical stimulation of the type delivered by neural prostheses such as the cochlear implant, bionic eye or in deep brain stimulation. Using the cochlear implant as a model, we developed an efficient computational model that predicts the responses of auditory nerve fibers to electrical stimulation and evaluated the model's accuracy by comparing the model output with pooled responses from a group of guinea pig auditory nerve fibers. It was found that the model accurately predicted the changes in neural firing probability over time to constant and variable amplitude electrical pulse trains, including speech-derived signals, delivered at rates up to 889 pulses s-1. A simplified version of the model that did not incorporate adaptation was used to adaptively predict, within its limitations, the pulsatile electrical stimulus required to cause a desired response from neurons up to 250 pulses s-1. Future stimulation strategies for cochlear implants and other neural prostheses may be enhanced using similar models that account for the way that neural responses are altered by previous stimulation.

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

DOEpatents

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.

Kilohertz and Low-Frequency Electrical Stimulation With the Same Pulse Duration Have Similar Efficiency for Inducing Isometric Knee Extension Torque and Discomfort.

PubMed

Medeiros, Flávia Vanessa; Bottaro, Martim; Vieira, Amilton; Lucas, Tiago Pires; Modesto, Karenina Arrais; Bo, Antonio Padilha L; Cipriano, Gerson; Babault, Nicolas; Durigan, João Luiz Quagliotti

2017-06-01

To test the hypotheses that, as compared with pulsed current with the same pulse duration, kilohertz frequency alternating current would not differ in terms of evoked-torque production and perceived discomfort, and as a result, it would show the same current efficiency. A repeated-measures design with 4 stimuli presented in random order was used to test 25 women: (1) 500-microsecond pulse duration, (2) 250-microsecond pulse duration, (3) 500-microsecond pulse duration and low carrier frequency (1 kHz), (4) 250-microsecond pulse duration and high carrier frequency (4 kHz). Isometric peak torque of quadriceps muscle was measured using an isokinetic dynamometer. Discomfort was measured using a visual analog scale. Currents with long pulse durations induced approximately 21% higher evoked torque than short pulse durations. In addition, currents with 500 microseconds delivered greater amounts of charge than stimulation patterns using 250-microsecond pulse durations (P < 0.05). All currents presented similar discomfort. There was no difference on stimulation efficiency with the same pulse duration. Both kilohertz frequency alternating current and pulsed current, with the same pulse duration, have similar efficiency for inducing isometric knee extension torque and discomfort. However, neuromuscular electrical stimulation (NMES) with longer pulse duration induces higher NMES-evoked torque, regardless of the carrier frequency. Pulse duration is an important variable that should receive more attention for an optimal application of NMES in clinical settings.

A flash-lamp based device for fluorescence detection and identification of individual pollen grains.

PubMed

Kiselev, Denis; Bonacina, Luigi; Wolf, Jean-Pierre

2013-03-01

We present a novel optical aerosol particle detector based on Xe flash lamp excitation and spectrally resolved fluorescence acquisition. We demonstrate its performances on three natural pollens acquiring in real-time scattering intensity at two wavelengths, sub-microsecond time-resolved scattering traces of the particles' passage in the focus, and UV-excited fluorescence spectra. We show that the device gives access to a rather specific detection of the bioaerosol particles.

Burst-mode manipulation of magnonic vortex crystals

NASA Astrophysics Data System (ADS)

Hänze, Max; Adolff, Christian F.; Weigand, Markus; Meier, Guido

2015-03-01

The manipulation of polarization states in 4 ×4 vortex crystals using sinusoidal magnetic field bursts is investigated by means of a broadband ferromagnetic-resonance setup. Magnetic field excitation with the proper amplitude and frequency allows tuning different polarization states, which are observed in the measured absorption spectra. The variation of the sinusoidal burst width consecutively identifies the time scale of the underlying process. A memorylike polarization state writing process is demonstrated on the submicrosecond time scale.

An Investigation of the Sub-Microsecond Features of Dynamic Crack Propagation in PMMA and the Rdx-Based Explosive PBX 9205

NASA Astrophysics Data System (ADS)

Washabaugh, P. D.; Hill, L. G.

2007-12-01

A dynamic crack propagating in a brittle material releases enough thermal energy to produce visible light. The dynamic fracture of even macroscopically amorphous materials becomes unsteady as the crack propagation velocity approaches the material wave-speeds. The heat generated at a crack-tip, especially as it jumps, may be a mechanism to initiate a self-sustaining reaction in an energetic material. Experiments were conducted in specimens to simulate an infinite plate for ˜10 μs. The initial specimens were 152 mm square by 6 mm thick acrylic sheets, and were fabricated to study non-steady near-wave-speed crack propagation. A variant of this specimen embedded a 25 mm×3 mm PBX 9205 pellet to explore the influence of dynamic Mode-I cracks in these materials. The crack was initiated by up to 0.24 g of Detasheet placed along a precursor 50 mm long notch, with a shield to contain the reaction products and prevent propagation along the fractured surfaces. The crack was studied by means of a streak camera and a Fourier-filter of the light reflecting off the newly minted surfaces. The sub-microsecond behavior of holes initiating, preceding and coalescing with the main crack were observed in the PMMA samples. The embedding and mechanical loading of explosives by this technique did not initiate a self-sustaining reaction in preliminary testing.

An initial investigation of the sub-microsecond features of dynamic crack propagation in PMMA and the RDX-based explosive PBX 9205

NASA Astrophysics Data System (ADS)

Washabaugh, Peter; Hill, Larry

2007-06-01

A dynamic crack propagating in a brittle material releases enough thermal energy to produce visible light. The dynamic fracture of even macroscopically amorphous materials becomes unsteady as the crack propagation velocity approaches the material wave-speeds. The heat generated at a crack-tip, especially as it jumps, may be a mechanism to initiate a self-sustaining reaction in an energetic material. Experiments were conducted in specimens to simulate an infinite plate for 20 μs. The initial specimens were 152 mm square by 6 mm thick acrylic sheets, and were fabricated to study non-steady near-wave-speed crack propagation. A variant of this specimen embedded a 25 mm x 3 mm PBX 9205 pellet to explore the influence of dynamic Mode-I cracks in these materials. The crack was initiated by up to 0.2 g of Detasheet placed along a precursor 50 mm long notch, with a shield to contain the reaction products and prevent propagation along the fractured surfaces. The crack was studied by means of a streak camera and a Fourier-filter of the light reflecting off the newly minted surfaces. The sub-microsecond behavior of holes initiating, preceding and coalescing with the main crack were observed in the PMMA samples. The embedding and mechanical loading of explosives by this technique did not initiate a self-sustaining reaction in preliminary testing.

New conducted electrical weapons: Electrical safety relative to relevant standards.

PubMed

Panescu, Dorin; Nerheim, Max; Kroll, Mark W; Brave, Michael A

2017-07-01

We have previously published about TASER ® conducted electrical weapons (CEW) compliance with international standards. CEWs deliver electrical pulses that can inhibit a person's neuromuscular control or temporarily incapacitate. An eXperimental Rotating-Field (XRF) waveform CEW and the X2 CEW are new 2-shot electrical weapon models designed to target a precise amount of delivered charge per pulse. They both can deploy 1 or 2 dart pairs, delivered by 2 separate cartridges. Additionally, the XRF controls delivery of incapacitating pulses over 4 field vectors, in a rotating sequence. As in our previous study, we were motivated by the need to understand the cardiac safety profile of these new CEWs. The goal of this paper is to analyze the nominal electrical outputs of TASER XRF and X2 CEWs in reference to provisions of all relevant international standards that specify safety requirements for electrical medical devices and electrical fences. Although these standards do not specifically mention CEWs, they are the closest electrical safety standards and hence give very relevant guidance. The outputs of several TASER XRF and X2 CEWs were measured under normal operating conditions. The measurements were compared against manufacturer specifications. CEWs electrical output parameters were reviewed against relevant safety requirements of UL 69, IEC 60335-2-76 Ed 2.1, IEC 60479-1, IEC 60479-2, AS/NZS 60479.1, AS/NZS 60479.2, IEC 60601-1 and BS EN 60601-1. Our study confirmed that the nominal electrical outputs of TASER XRF and X2 CEWs lie within safety bounds specified by relevant standards.

Pulse shape optimization for electron-positron production in rotating fields

NASA Astrophysics Data System (ADS)

Fillion-Gourdeau, François; Hebenstreit, Florian; Gagnon, Denis; MacLean, Steve

2017-07-01

We optimize the pulse shape and polarization of time-dependent electric fields to maximize the production of electron-positron pairs via strong field quantum electrodynamics processes. The pulse is parametrized in Fourier space by a B -spline polynomial basis, which results in a relatively low-dimensional parameter space while still allowing for a large number of electric field modes. The optimization is performed by using a parallel implementation of the differential evolution, one of the most efficient metaheuristic algorithms. The computational performance of the numerical method and the results on pair production are compared with a local multistart optimization algorithm. These techniques allow us to determine the pulse shape and field polarization that maximize the number of produced pairs in computationally accessible regimes.

Sodium benzoate, potassium sorbate, and citric acid induce sublethal injury and enhance pulsed electric field inactivation of E. coli O157:H7 and nonpathogenic surrogate E. coli in strawberry juice

USDA-ARS?s Scientific Manuscript database

Current FDA regulations require that juice processors effect a 5 log CFU/ml reduction of a target pathogen prior to distributing products. Whereas thermal pasteurization reduces the sensory characteristics of juice by altering flavor components, pulsed electric field (PEF) treatment can be conducte...

Electrical Breakdown Phenomena Involving Material Interfaces

DTIC Science & Technology

2013-06-01

create ozone through chemical reactions involving reactive species created by the electrical discharge [3]. The glow discharge breakdown in such...2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Investigation Of Pre-Ionization And Atmospheric Pulsed Discharge Plasma 5a...growth of the air discharge in the form of a conductive filament consisting of electrons and ions. This filament is created by temporal pulse that

Pulsed electrical discharge in gas bubbles in water

NASA Astrophysics Data System (ADS)

Gershman, Sophia

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

Cellular effects of acute exposure to high peak power microwave systems: Morphology and toxicology.

PubMed

Ibey, Bennett L; Roth, Caleb C; Ledwig, Patrick B; Payne, Jason A; Amato, Alayna L; Dalzell, Danielle R; Bernhard, Joshua A; Doroski, Michael W; Mylacraine, Kevin S; Seaman, Ronald L; Nelson, Gregory S; Woods, Clifford W

2016-03-15

Electric fields produced by advanced pulsed microwave transmitter technology now readily exceed the Institute of Electrical and Electronic Engineers (IEEE) C.95.1 peak E-field limit of 100 kV/m, highlighting a need for scientific validation of such a specific limit. Toward this goal, we exposed Jurkat Clone E-6 human lymphocyte preparations to 20 high peak power microwave (HPPM) pulses (120 ns duration) with a mean peak amplitude of 2.3 MV/m and standard deviation of 0.1 with the electric field at cells predicted to range from 0.46 to 2.7 MV/m, well in excess of current standard limit. We observed that membrane integrity and cell morphology remained unchanged 4 h after exposure and cell survival 24 h after exposure was not statistically different from sham exposure or control samples. Using flow cytometry to analyze membrane disruption and morphological changes per exposed cell, no changes were observed in HPPM-exposed samples. Current IEEE C95.1-2005 standards for pulsed radiofrequency exposure limits peak electric field to 100 kV/m for pulses shorter than 100 ms [IEEE (1995) PC95.1-Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic and Electromagnetic Fields, 0 Hz to 300 GHz, Institute of Electrical and Electronic Engineers: Piscataway, NJ, USA]. This may impose large exclusion zones that limit HPPM technology use. In this study, we offer evidence that maximum permissible exposure of 100 kV/m for peak electric field may be unnecessarily restrictive for HPPM devices. Bioelectromagnetics. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Electrical method and apparatus for impelling the extruded ejection of high-velocity material jets

DOEpatents

Weingart, Richard C.

1989-01-01

A method and apparatus (10, 40) for producing high-velocity material jets provided. An electric current pulse generator (14, 42) is attached to an end of a coaxial two-conductor transmission line (16, 44) having an outer cylindrical conductor (18), an inner cylindrical conductor (20), and a solid plastic or ceramic insulator (21) therebetween. A coxial, thin-walled metal structure (22, 30) is conductively joined to the two conductors (18, 20) of the transmission line (16, 44). An electrical current pulse applies magnetic pressure to and possibly explosively vaporizes metal structure (22), thereby collapsing it and impelling the extruded ejection of a high-velocity material jet therefrom. The jet is comprised of the metal of the structure (22), together with the material that comprises any covering layers (32, 34) disposed on the structure. An electric current pulse generator of the explosively driven magnetic flux compression type or variety (42) may be advantageously used in the practice of this invention.

A review of electric propulsion systems and mission applications

NASA Technical Reports Server (NTRS)

Vondra, R.; Nock, K.; Jones, R.

1984-01-01

The satisfaction of growing demands for access to space resources will require new developments related to advanced propulsion and power technologies. A key technology in this context is concerned with the utilization of electric propulsion. A brief review of the current state of development of electric propulsion systems on an international basis is provided, taking into account advances in the USSR, the U.S., Japan, West Germany, China and Brazil. The present investigation, however, is mainly concerned with the U.S. program. The three basic types of electric thrusters are considered along with the intrinsic differences between chemical and electric propulsion, the resistojet, the augmented hydrazine thruster, the arcjet, the ion auxiliary propulsion system flight test, the pulsed plasma thruster, magnetoplasmadynamic propulsion, a pulsed inductive thruster, and rail accelerators. Attention is also given to the applications of electric propulsion.

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

PubMed

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 foundation for further in vivo experiments, and for the potential clinical application of psPEF in the treatment of cervical cancer.

Sequentially pulsed traveling wave accelerator

DOEpatents

Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

2009-08-18

A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

PIC simulations of post-pulse field reversal and secondary ionization in nanosecond argon discharges

NASA Astrophysics Data System (ADS)

Kim, H. Y.; Gołkowski, M.; Gołkowski, C.; Stoltz, P.; Cohen, M. B.; Walker, M.

2018-05-01

Post-pulse electric field reversal and secondary ionization are investigated with a full kinetic treatment in argon discharges between planar electrodes on nanosecond time scales. The secondary ionization, which occurs at the falling edge of the voltage pulse, is induced by charge separation in the bulk plasma region. This process is driven by a reverse in the electric field from the cathode sheath to the formerly driven anode. Under the influence of the reverse electric field, electrons in the bulk plasma and sheath regions are accelerated toward the cathode. The electron movement manifests itself as a strong electron current generating high electron energies with significant electron dissipated power. Accelerated electrons collide with Ar molecules and an increased ionization rate is achieved even though the driving voltage is no longer applied. With this secondary ionization, in a single pulse (SP), the maximum electron density achieved is 1.5 times higher and takes a shorter time to reach using 1 kV 2 ns pulse as compared to a 1 kV direct current voltage at 1 Torr. A bipolar dual pulse excitation can increase maximum density another 50%–70% above a SP excitation and in half the time of RF sinusoidal excitation of the same period. The first field reversal is most prominent but subsequent field reversals also occur and correspond to electron temperature increases. Targeted pulse designs can be used to condition plasma density as required for fast discharge applications.

Autonomous data transmission apparatus

DOEpatents

Kotlyar, O.M.

1997-03-25

A autonomous borehole data transmission apparatus is described for transmitting measurement data from measuring instruments at the downhole end of a drill string by generating pressure pulses utilizing a transducer longitudinally responsive to magnetic field pulses caused by electrical pulses corresponding to the measured downhole parameters. 4 figs.

Laser-excited pulse propagation in a crystallized complex plasma

NASA Astrophysics Data System (ADS)

Nosenko, V.; Nunomura, S.; Goree, J.

2000-10-01

A complex plasma, so-called in analogy with complex fluids, is an ionized gas containing small solid particles. This medium is also called a dusty plasma. The particles acquire a large negative electric charge. In an experiment, polymer microspheres were shaken into a parallel-plate rf plasma. The particles were levitated by the electric field in the sheath above the lower electrode. The particles settled in a single horizontal layer, and were arranged in a hexagonal lattice. They were imaged using a video camera to record the particle motion. Like any crystal, this so-called ``plasma crystal'' sustains compressional sound waves, which can be launched as a pulse. By modulating an argon laser beam directed tangentially at the lattice, we launched a pulsed wave in the lattice. We evaluated the pulse shape and propagation speed, while varying the pulse power and duration. This allowed a test for dispersion and nonlinearity, as well as a test of whether the pulse has the properties of a shock.

Higher-order power harmonics of pulsed electrical stimulation modulates corticospinal contribution of peripheral nerve stimulation.

PubMed

Chen, Chiun-Fan; Bikson, Marom; Chou, Li-Wei; Shan, Chunlei; Khadka, Niranjan; Chen, Wen-Shiang; Fregni, Felipe

2017-03-03

It is well established that electrical-stimulation frequency is crucial to determining the scale of induced neuromodulation, particularly when attempting to modulate corticospinal excitability. However, the modulatory effects of stimulation frequency are not only determined by its absolute value but also by other parameters such as power at harmonics. The stimulus pulse shape further influences parameters such as excitation threshold and fiber selectivity. The explicit role of the power in these harmonics in determining the outcome of stimulation has not previously been analyzed. In this study, we adopted an animal model of peripheral electrical stimulation that includes an amplitude-adapted pulse train which induces force enhancements with a corticospinal contribution. We report that the electrical-stimulation-induced force enhancements were correlated with the amplitude of stimulation power harmonics during the amplitude-adapted pulse train. In an exploratory analysis, different levels of correlation were observed between force enhancement and power harmonics of 20-80 Hz (r = 0.4247, p = 0.0243), 100-180 Hz (r = 0.5894, p = 0.0001), 200-280 Hz (r = 0.7002, p < 0.0001), 300-380 Hz (r = 0.7449, p < 0.0001), 400-480 Hz (r = 0.7906, p < 0.0001), 500-600 Hz (r = 0.7717, p < 0.0001), indicating a trend of increasing correlation, specifically at higher order frequency power harmonics. This is a pilot, but important first demonstration that power at high order harmonics in the frequency spectrum of electrical stimulation pulses may contribute to neuromodulation, thus warrant explicit attention in therapy design and analysis.

Structural and phase transformations in zinc and brass wires under heating with high-density current pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pervikov, A. V.

The work is focused on revealing the mechanism of structure and phase transformations in the metal wires under heating with a high-density current pulse (the electric explosion of wires, EEWs). It has been demonstrated on the example of brass and zinc wires that the transition of a current pulse with the density of j ≈ 3.3 × 10{sup 7} A/cm{sup 2} results in homogeneous heating of the crystalline structure of the metal/alloy. It has been determined that under heating with a pulse of high-density current pulse, the electric resistance of the liquid phases of zinc and brass decreases as the temperature increases. The results obtainedmore » allow for a conclusion that the presence of the particles of the condensed phase in the expanding products of EEW is the result of overheating instabilities in the liquid metal.« less

Effect of electromagnetic pulse on avoidance behavior and electroencephalogram of a rhesus monkey.

PubMed

Mattsson, J L; Oliva, S A

1976-06-01

A 12-kg male rhesus monkey was exposed to electromagnetic pulse (EMP) at 266 kv/m, 5 pulses/s, for 1 h (18,700 pulses). The effects of EMP on Sidman avoidance behavior and on post-exposure electroencephalogram were evaluated, and no significant changes were detected. An analysis of an EMP showed that it contained various frequency components extending from 0 Hz to 10(9) Hz. However, the pulse configuration was such that its power was mainly confined to the longer wave-lengths (less than 30 MHz). The lack of biologic effect was attributed to the fact that the wavelengths were long relative to the size of the monkey, and little energy deposition was likely to occur. In addition, the electric field was evenly distributed across all lower frequencies so that only a very small electric field component existed at any specific low frequency.

Agricultural and Food Processing Applications of Pulsed Power Technology

NASA Astrophysics Data System (ADS)

Takaki, Koichi; Ihara, Satoshi

Recent progress of agricultural and food processing applications of pulsed power is described in this paper. Repetitively operated compact pulsed power generators with a moderate peak power have been developed for the agricultural and the food processing applications. These applications are mainly based on biological effects and can be categorized as decontamination of air and liquid, germination promotion, inhabitation of saprophytes growth, extraction of juice from fruits and vegetables, and fertilization of liquid medium, etc. Types of pulsed power that have biological effects are caused with gas discharges, water discharges, and electromagnetic fields. The discharges yield free radicals, UV radiation, intense electric field, and shock waves. Biologically based applications of pulsed power are performed by selecting the type that gives the target objects the adequate result from among these agents or byproducts. For instance, intense electric fields form pores on the cell membrane, which is called electroporation, or influence the nuclei.

Apparatus and method for compensating for clock drift in downhole drilling components

DOEpatents

Hall, David R [Provo, UT; Pixton, David S [Lehi, UT; Johnson, Monte L [Orem, UT; Bartholomew, David B [Springville, UT; Hall, Jr., H. Tracy

2007-08-07

A precise downhole clock that compensates for drift includes a prescaler configured to receive electrical pulses from an oscillator. The prescaler is configured to output a series of clock pulses. The prescaler outputs each clock pulse after counting a preloaded number of electrical pulses from the oscillator. The prescaler is operably connected to a compensator module for adjusting the number loaded into the prescaler. By adjusting the number that is loaded into the prescaler, the timing may be advanced or retarded to more accurately synchronize the clock pulses with a reference time source. The compensator module is controlled by a counter-based trigger module configured to trigger the compensator module to load a value into the prescaler. Finally, a time-base logic module is configured to calculate the drift of the downhole clock by comparing the time of the downhole clock with a reference time source.

Pulsed high voltage electric discharge disinfection of microbially contaminated liquids.

PubMed

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.

Electrical switching in cadmium boracite single crystals

NASA Technical Reports Server (NTRS)

Takahashi, T.; Yamada, O.

1981-01-01

Cadmium boracite single crystals at high temperatures ( 300 C) were found to exhibit a reversible electric field-induced transition between a highly insulative and a conductive state. The switching threshold is smaller than a few volts for an electrode spacing of a few tenth of a millimeter corresponding to an electric field of 100 to 1000 V/cm. This is much smaller than the dielectric break-down field for an insulator such as boracite. The insulative state reappears after voltage removal. A pulse technique revealed two different types of switching. Unstable switching occurs when the pulse voltage slightly exceeds the switching threshold and is characterized by a pre-switching delay and also a residual current after voltage pulse removal. A stable type of switching occurs when the voltage becomes sufficiently high. Possible device applications of this switching phenomenon are discussed.

Electrically Variable Resistive Memory Devices

NASA Technical Reports Server (NTRS)

Liu, Shangqing; Wu, Nai-Juan; Ignatiev, Alex; Charlson, E. J.

2010-01-01

Nonvolatile electronic memory devices that store data in the form of electrical- resistance values, and memory circuits based on such devices, have been invented. These devices and circuits exploit an electrically-variable-resistance phenomenon that occurs in thin films of certain oxides that exhibit the colossal magnetoresistive (CMR) effect. It is worth emphasizing that, as stated in the immediately preceding article, these devices function at room temperature and do not depend on externally applied magnetic fields. A device of this type is basically a thin film resistor: it consists of a thin film of a CMR material located between, and in contact with, two electrical conductors. The application of a short-duration, low-voltage current pulse via the terminals changes the electrical resistance of the film. The amount of the change in resistance depends on the size of the pulse. The direction of change (increase or decrease of resistance) depends on the polarity of the pulse. Hence, a datum can be written (or a prior datum overwritten) in the memory device by applying a pulse of size and polarity tailored to set the resistance at a value that represents a specific numerical value. To read the datum, one applies a smaller pulse - one that is large enough to enable accurate measurement of resistance, but small enough so as not to change the resistance. In writing, the resistance can be set to any value within the dynamic range of the CMR film. Typically, the value would be one of several discrete resistance values that represent logic levels or digits. Because the number of levels can exceed 2, a memory device of this type is not limited to binary data. Like other memory devices, devices of this type can be incorporated into a memory integrated circuit by laying them out on a substrate in rows and columns, along with row and column conductors for electrically addressing them individually or collectively.

Circuit for monitoring temperature of high-voltage equipment

DOEpatents

Jacobs, Martin E.

1976-01-01

This invention relates to an improved circuit for measuring temperature in a region at high electric potential and generating a read-out of the same in a region at lower potential. The circuit is specially designed to combine high sensitivity, stability, and accuracy. A major portion of the circuit situated in the high-potential region can take the form of an integrated circuit. The preferred form of the circuit includes an input section which is situated in the high-potential region and comprises a temperature-compensated thermocouple circuit for sensing temperature, an oscillator circuit for generating a train of ramp voltages whose rise time varies inversely with the thermocouple output, a comparator and switching circuit for converting the oscillator output to pulses whose frequency is proportional to the thermocouple output, and a light-emitting diode which is energized by these pulses. An optical coupling transmits the light pulses generated by the diode to an output section of the circuit, situated in a region at ground. The output section comprises means for converting the transmitted pulses to electrical pulses of corresponding frequency, means for amplifying the electrical pulses, and means for displaying the frequency of the same. The preferred embodiment of the overall circuit is designed so that the frequency of the output signal in hertz and tenths of hertz is equal to the sensed temperature in degrees and tenths of degrees.

Miniaturized two-stack Blumlein pulser with a variable repetition-rate for non-thermal irreversible-electroporation experiments

NASA Astrophysics Data System (ADS)

Min, Sun-Hong; Kwon, Ohjoon; Sattorov, Matlabjon; Baek, In-Keun; Kim, Seontae; Jeong, Jin-Young; Hong, Dongpyo; Park, Seunghyuk; Park, Gun-Sik

2017-01-01

Non-thermal irreversible electroporation (NTIRE) to avoid thermal damage to cells during intense DC ns pulsed electric fields (nsPEFs) is a recent modality for medical applications. This mechanism, related to bioelectrical dynamics of the cell, is linked to the effect of a DC electric field and a threshold effect with an electrically stimulated membrane for the charge distribution in the cell. To create the NTIRE condition, the pulse width of the nsPEF should be shorter than the charging time constant of the membrane related to the cell radius, membrane capacitance, cytoplasm resistivity, and medium resistivity. It is necessary to design and fabricate a very intense nanosecond DC electric field pulser that is capable of producing voltages up to the level of 100 kV/cm with an artificial pulse width (˜ns) with controllable repetition rates. Many devices to generate intense DC nsPEF using various pulse-forming line technologies have been introduced thus far. However, the previous Blumlein pulse-generating devices are clearly inefficient due to the energy loss between the input voltage and the output voltage. An improved two-stage stacked Blumlein pulse-forming line can overcome this limitation and decrease the energy loss from a DC power supply. A metal oxide silicon field-effect transistor switch with a fast rise and fall time would enable a high repetition rate (max. 100 kHz) and good endurance against very high voltages (DC ˜ 30 kV). The load is designed to match the sample for exposure to cell suspensions consisting of a 200 Ω resistor matched with a Blumlein circuit and two electrodes without the characteristic RC time effect of the circuit (capacitance =0.174 pF).

The Crossed-Dipole Structure of Aircraft in an Electromagnetic Pulse Environment

DTIC Science & Technology

1974-09-01

The crossed-dipole receiving antenna has been used as a representative model to approximate electromagnetic pulse effects on aircraft. This paper...receiving antenna is excited by a broad spectrum electromagnetic pulse , certain important electrical resonances occur: that is, at specific single...dipole are presented which give insight into methods of analyzing aircraft in an electromagnetic pulse environment.

A trial of ignition innovation of gasoline engine by nanosecond pulsed low temperature plasma ignition

NASA Astrophysics Data System (ADS)

Shiraishi, Taisuke; Urushihara, Tomonori; Gundersen, Martin

2009-07-01

Application of nanosecond pulsed low temperature plasma as an ignition technique for automotive gasoline engines, which require a discharge under conditions of high back pressure, has been studied experimentally using a single-cylinder engine. The nanosecond pulsed plasma refers to the transient (non-equilibrated) phase of a plasma before the formation of an arc discharge; it was obtained by applying a high voltage with a nanosecond pulse (FWHM of approximately 80 or 25 ns) between coaxial cylindrical electrodes. It was confirmed that nanosecond pulsed plasma can form a volumetric multi-channel streamer discharge at an energy consumption of 60 mJ cycle-1 under a high back pressure of 1400 kPa. It was found that the initial combustion period was shortened compared with the conventional spark ignition. The initial flame visualization suggested that the nanosecond pulsed plasma ignition results in the formation of a spatially dispersed initial flame kernel at a position of high electric field strength around the central electrode. It was observed that the electric field strength in the air gap between the coaxial cylindrical electrodes was increased further by applying a shorter pulse. It was also clarified that the shorter pulse improved ignitability even further.

The detailed characteristics of positive corona current pulses in the line-to-plane electrodes

NASA Astrophysics Data System (ADS)

Xuebao, LI; Dayong, LI; Qian, ZHANG; Yinfei, LI; Xiang, CUI; Tiebing, LU

2018-05-01

The corona current pulses generated by corona discharge are the sources of the radio interference from transmission lines and the detailed characteristics of the corona current pulses from conductor should be investigated in order to reveal their generation mechanism. In this paper, the line-to-plane electrodes are designed to measure and analyze the characteristics of corona current pulses from positive corona discharges. The influences of inter-electrode gap and line diameters on the detail characteristics of corona current pulses, such as pulse amplitude, rise time, duration time and repetition frequency, are carefully analyzed. The obtained results show that the pulse amplitude and the repetition frequency increase with the diameter of line electrode when the electric fields on the surface of line electrodes are same. With the increase of inter-electrode gap, the pulse amplitude and the repetition frequency first decrease and then turn to be stable, while the rise time first increases and finally turns to be stable. The distributions of electric field and space charges under the line electrodes are calculated, and the influences of inter-electrode gap and line electrode diameter on the experimental results are qualitatively explained.

Study of Conical Pulsed Inductive Thruster with Multiple Modes of Operation

NASA Technical Reports Server (NTRS)

Miller, Robert; Eskridge, Richard; Martin, Adam; Rose, Frank

2008-01-01

An electrodeless, pulsed, inductively coupled thruster has several advantages over current electric propulsion designs. The efficiency of a pulsed inductive thruster is dependent upon the pulse characteristics of the device. Therefore, these thrusters are throttleable over a wide range of thrust levels by varying the pulse rate without affecting the thruster efficiency. In addition, by controlling the pulse energy and the mass bit together, the ISP of the thruster can also be varied with minimal efficiency loss over a wide range of ISP levels. Pulsed inductive thrusters will work with a multitude of propellants, including ammonia. Thus, a single pulsed inductive thruster could be used to handle a multitude of mission needs from high thrust to high ISP with one propulsion solution that would be variable in flight. A conical pulsed inductive lab thruster has been built to study this form of electric propulsion in detail. This thruster incorporates many advantages that are meant to enable this technology as a viable space propulsion technology. These advantages include incorporation of solid state switch technology for all switching needs of the thruster and pre-ionization of the propellant gas prior to acceleration. Pre-ionizing will significantly improve coupling efficiency between drive and bias fields and the plasma. This enables lower pulse energy levels without efficiency reduction. Pre-ionization can be accomplished at a small fraction of the drive pulse energy.

Behavior of pulsed electric field injured Escherichia coli O157:H7 cells in apple juice amended with pyruvate and catalase

USDA-ARS?s Scientific Manuscript database

Pulse Electric Field (PEF) treatment has been used to inactivate bacteria in liquid foods. However, information on the behavior of PEF injured Escherichia coli bacteria in media during storage at 5 and 23C are limited. In this study, we investigated the fate of E. coli O157:H7 cells at 6.8 log CFU/m...

Evaluation of microbial stability, bioactive compounds, physicochemical properties, and consumer acceptance of pomegranate juice processed in a commercial scale pulsed electric field system

USDA-ARS?s Scientific Manuscript database

This paper investigated the feasibility for pasteurizing raw pomegranate juice in a commercial scale pulsed electric field (PEF) system. The juice was processed in a commercial scale PEF processing system at 35 and 38 kV/cm for 281 µs at 55 degree C with a flow rate of 100 L/h. Effect of PEF process...

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

PubMed

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

2007-01-01

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

Electrically Stimulated Adipose Stem Cells on Polypyrrole-Coated Scaffolds for Smooth Muscle Tissue Engineering.

PubMed

Björninen, Miina; Gilmore, Kerry; Pelto, Jani; Seppänen-Kaijansinkko, Riitta; Kellomäki, Minna; Miettinen, Susanna; Wallace, Gordon; Grijpma, Dirk; Haimi, Suvi

2017-04-01

We investigated the use of polypyrrole (PPy)-coated polymer scaffolds and electrical stimulation (ES) to differentiate adipose stem cells (ASCs) towards smooth muscle cells (SMCs). Since tissue engineering lacks robust and reusable 3D ES devices we developed a device that can deliver ES in a reliable, repeatable, and cost-efficient way in a 3D environment. Long pulse (1 ms) or short pulse (0.25 ms) biphasic electric current at a frequency of 10 Hz was applied to ASCs to study the effects of ES on ASC viability and differentiation towards SMCs on the PPy-coated scaffolds. PPy-coated scaffolds promoted proliferation and induced stronger calponin, myosin heavy chain (MHC) and smooth muscle actin (SMA) expression in ASCs compared to uncoated scaffolds. ES with 1 ms pulse width increased the number of viable cells by day 7 compared to controls and remained at similar levels to controls by day 14, whereas shorter pulses significantly decreased viability compared to the other groups. Both ES protocols supported smooth muscle expression markers. Our results indicate that electrical stimulation on PPy-coated scaffolds applied through the novel 3D ES device is a valid approach for vascular smooth muscle tissue engineering.

Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping

NASA Astrophysics Data System (ADS)

Peterchev, Angel V.; DʼOstilio, Kevin; Rothwell, John C.; Murphy, David L.

2014-10-01

Objective. This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with a lower voltage rating than prior cTMS devices. Main results. cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (\\lt 10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in ten healthy volunteers. Significance. The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool.

Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping

PubMed Central

D’Ostilio, Kevin; Rothwell, John C; Murphy, David L

2014-01-01

Objective This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with lower voltage rating than prior cTMS devices. Main results cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (<10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in 10 healthy volunteers. Significance The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool. PMID:25242286

An apoptosis targeted stimulus with nanosecond pulsed electric fields (nsPEFs) in E4 squamous cell carcinoma.

PubMed

Ren, Wei; Beebe, Stephen J

2011-04-01

Stimuli directed towards activation of apoptosis mechanisms are an attractive approach to eliminate evasion of apoptosis, a ubiquitous cancer hallmark. In these in vitro studies, kinetics and electric field thresholds for several apoptosis characteristics are defined in E4 squamous carcinoma cells (SCC) exposed to ten 300 ns pulses with increasing electric fields. Cell death was >95% at the highest electric field and coincident with phosphatidylserine externalization, caspase and calpain activation in the presence and absence of cytochrome c release, decreases in Bid and mitochondria membrane potential (Δψm) without apparent changes reactive oxygen species levels or in Bcl2 and Bclxl levels. Bid cleavage was caspase-dependent (55-60%) and calcium-dependent (40-45%). Intracellular calcium as an intrinsic mechanism and extracellular calcium as an extrinsic mechanism were responsible for about 30 and 70% of calcium dependence for Bid cleavage, respectively. The results reveal electric field-mediated cell death induction and progression, activating pro-apoptotic-like mechanisms and affecting plasma membrane and intracellular functions, primarily through extrinsic-like pathways with smaller contributions from intrinsic-like pathways. Nanosecond second pulsed electric fields trigger heterogeneous cell death mechanisms in E4 SCC populations to delete them, with caspase-associated cell death as a predominant, but not an unaccompanied event.

Effect of electrical stimulation on beta-adrenergic receptor population and cyclic amp production in chicken and rat skeletal muscle cell cultures

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Strietzel, C. J.

2000-01-01

Expression of the beta-adrenergic receptor (betaAR) and its coupling to cyclic AMP (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the betaAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically, chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the betaAR population was not significantly affected by electrical stimulation; however, the ability of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the betaAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.

Effect of Electrical Stimulation on Beta-Adrenergic Receptor Population and Cyclic AMP Production in Chicken and Rat Skeletal Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, Kristin Y.; Strietzel, Catherine J.

2000-01-01

Expression of the beta-adrenergic receptor (PAR) and its coupling to Adenosine 3'5' Cyclic Monophosphate (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the PAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture, were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the PAR population was not significantly affected by electrical stimulation; however, the ability, of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the PAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.

Definition of Shifts of Optical Transitions Frequencies due to Pulse Perturbation Action by the Photon Echo Signal Form

NASA Astrophysics Data System (ADS)

Lisin, V. N.; Shegeda, A. M.; Samartsev, V. V.

2015-09-01

A relative phase shift between the different groups of excited dipoles, which appears as result of its frequency splitting due to action of a pulse of electric or magnetic fields, depends on a time, if the pulse overlaps in time with echo-pulse. As а consequence, the echo waveform is changed. The echo time form is modulated. The inverse modulation period well enough approximates Zeeman and pseudo-Stark splitting in the cases of magnetic and, therefore, electrical fields. Thus the g-factors of ground 4I15/2 and excited 4F9/2 optical states of Er3+ ion in LuLiF4 and YLiF4 have been measured and pseudo-Stark shift of R1 line in ruby has been determined.

Electrochemical system and method for electropolishing hollow metal bodies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, E. Jennings; Inman, Maria E.; Hall, Timothy

A method and system for electrochemically machining a hollow body of a metal or a metal alloy. An electrode is positioned within a hollow body including a metal or metal alloy, where the hollow body has a variable internal diameter. The hollow body is oriented vertically, with the electrode oriented vertically therein. The hollow body is at least partially filled with an aqueous, acidic electrolyte solution, the electrolyte solution being devoid of hydrofluoric acid and having a viscosity less than 15 cP. An electric current is passed between the hollow body and the electrode, where the electric current includes amore » plurality of anodic pulses and a plurality of cathodic pulses, and where the cathodic pulses are interposed between at least some of the anodic pulses.« less

Latching Solenoid-Operated Ball Valve

NASA Technical Reports Server (NTRS)

Brudnicki, Myron

1994-01-01

Proposed solenoid-operated ball valve latches in open or closed position until energized to change position. Electrical energy consumed only during opening or closing motion. Valve ball contains central channel through which fluid could flow. Made of highly magnetically permeable steel. When appropriate coil(s) energized by brief pulse (or pulses) of electrical current at appropriate polarity, ball rotates clockwise until permanent magnets come to rest against hard stops in housing, and inlet and outlet ports aligned with central channel so fluid flows through valve. Magnets adhere to stops by magnetic attraction, latching valve in open position. To close valve, appropriate coil(s) energized by pulse (or pulses) of appropriate polarity to generate magnetic forces rotating ball counterclockwise until magnets make contact with hard stops, and inlet and outlet ports sealed.

Characterizing inner-shell with spectral phase interferometry for direct electric-field reconstruction

PubMed Central

Mashiko, Hiroki; Yamaguchi, Tomohiko; Oguri, Katsuya; Suda, Akira; Gotoh, Hideki

2014-01-01

In many atomic, molecular and solid systems, Lorentzian and Fano profiles are commonly observed in a broad research fields throughout a variety of spectroscopies. As the profile structure is related to the phase of the time-dependent dipole moment, it plays an important role in the study of quantum properties. Here we determine the dipole phase in the inner-shell transition using spectral phase interferometry for direct electric-field reconstruction (SPIDER) with isolated attosecond pulses (IAPs). In addition, we propose a scheme for pulse generation and compression by manipulating the inner-shell transition. The electromagnetic radiation generated by the transition is temporally compressed to a few femtoseconds in the extreme ultraviolet (XUV) region. The proposed pulse-compression scheme may provide an alternative route to producing attosecond pulses of light. PMID:25510971

Inductive gas line for pulsed lasers

DOEpatents

Benett, William J.; Alger, Terry W.

1985-01-01

A gas laser having a metal inlet gas feed line assembly shaped as a coil, to function as an electrical inductance and therefore high impedance to pulses of electric current applied to electrodes at opposite ends of a discharge tube of a laser, for example. This eliminates a discharge path for the laser through the inlet gas feed line. A ferrite core extends through the coil to increase the inductance of the coil and provide better electric isolation. By elimination of any discharge breakdown through the gas supply, efficiency is increased and a significantly longer operating lifetime of the laser is provided.

Inductive gas line for pulsed lasers

DOEpatents

Benett, W.J.; Alger, T.W.

1982-09-29

A gas laser having a metal inlet gas feed line assembly shaped as a coil, to function as an electrical inductance and therefore high impedance to pulses of electric current applied to electrodes at opposite ends of a discharge tube of a laser, for example. This eliminates a discharge path for the laser through the inlet gas feed line. A ferrite core extends through the coil to increase the inductance of the coil and provide better electric isolation. By elimination of any discharge breakdown through the gas supply, efficiency is increased and a significantly longer operating lifetime of the laser is provided.

Determining which mechanisms lead to activation in the motor cortex: a modeling study of transcranial magnetic stimulation using realistic stimulus waveforms and sulcal geometry1

PubMed Central

Salvador, R.; Silva, S.; Basser, P. J.; Miranda, P. C.

2010-01-01

Objective To determine which mechanisms lead to activation of neurons in the motor cortex during transcranial magnetic stimulation (TMS) with different current directions and pulse waveforms. Methods The total electric field induced in a simplified model of a cortical sulcus by a figure-eight coil was calculated using the finite element method (FEM). This electric field was then used as the input to determine the response of compartmental models of several types of neurons. Results The modeled neurons were stimulated at different sites: fiber bends for pyramidal tract neurons, axonal terminations for cortical interneurons and axon collaterals, and a combination of both for pyramidal association fibers. All neurons were more easily stimulated by a PA directed electric field, except association fibers. Additionally, the second phase of a biphasic pulse was found to be more efficient than the first phase of either monophasic or biphasic pulses. Conclusion The stimulation threshold for different types of neurons depends on the pulse waveform and current direction. The reported results might account for the range of responses obtained in TMS of the motor cortex when using different stimulation parameters. Significance Modeling studies combining electric field calculations and neuronal models may lead to a deeper understanding of the effect of the TMS-induced electric field on cortical tissue, and may be used to evaluate improvements in TMS coil and waveform design. PMID:21035390

Unusual lightning electric field waveforms observed in Kathmandu, Nepal, and Uppsala, Sweden

NASA Astrophysics Data System (ADS)

Adhikari, Pitri Bhakta; Sharma, Shriram; Baral, Kedarnath; Rakov, Vladimir A.

2017-11-01

Unusual lightning events have been observed in Uppsala, Sweden, and Kathmandu, Nepal, using essentially the same electric field measuring system developed at Uppsala University. They occurred in the storms that also generated ;normal; lightning events. The unusual events recorded in Uppsala occurred on one thunderstorm day. Similar events were observed in Kathmandu on multiple thunderstorm days. The unusual events were analyzed in this study assuming them to be positive ground flashes (+CGs), although we cannot rule out the possibility that some or most of them were actually cloud discharges (ICs). The unusual events were each characterized by a relatively slow, negative (atmospheric electricity sign convention) electric field waveform preceded by a pronounced opposite-polarity pulse whose duration was some tens of microseconds. To the best of our knowledge, such unusual events have not been reported in the literature. The average amplitudes of the opposite-polarity pulses with respect to those of the following main waveform were found to be about 33% in Uppsala (N = 31) and about 38% in Kathmandu (N = 327). The average durations of the main waveform and the preceding opposite-polarity pulse in Uppsala were 8.24 ms and 57.1 μs, respectively, and their counterparts in Kathmandu were 421 μs and 39.7 μs. Electric field waveforms characteristic of negative ground flashes (-CGs) were also observed, and none of them exhibited an opposite-polarity pulse prior to the main waveform. Possible origins of the unusual field waveforms are discussed.

ELECTRIC CURRENT FILAMENTATION AT A NON-POTENTIAL MAGNETIC NULL-POINT DUE TO PRESSURE PERTURBATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jelínek, P.; Karlický, M.; Murawski, K., E-mail: pjelinek@prf.jcu.cz

2015-10-20

An increase of electric current densities due to filamentation is an important process in any flare. We show that the pressure perturbation, followed by an entropy wave, triggers such a filamentation in the non-potential magnetic null-point. In the two-dimensional (2D), non-potential magnetic null-point, we generate the entropy wave by a negative or positive pressure pulse that is launched initially. Then, we study its evolution under the influence of the gravity field. We solve the full set of 2D time dependent, ideal magnetohydrodynamic equations numerically, making use of the FLASH code. The negative pulse leads to an entropy wave with amore » plasma density greater than in the ambient atmosphere and thus this wave falls down in the solar atmosphere, attracted by the gravity force. In the case of the positive pressure pulse, the plasma becomes evacuated and the entropy wave propagates upward. However, in both cases, owing to the Rayleigh–Taylor instability, the electric current in a non-potential magnetic null-point is rapidly filamented and at some locations the electric current density is strongly enhanced in comparison to its initial value. Using numerical simulations, we find that entropy waves initiated either by positive or negative pulses result in an increase of electric current densities close to the magnetic null-point and thus the energy accumulated here can be released as nanoflares or even flares.« less

Protect Yourself and Others from Electrical Hazards after a Disaster

MedlinePlus

... emergency medical help . Turn off the source of electricity if possible. If not, move the source away ... the person is free of the source of electricity, check the person’s breathing and pulse. If either ...

Ultrashort pulse high intensity laser illumination of a simple metal

NASA Astrophysics Data System (ADS)

Milchberg, H. M.; Freeman, R. R.; Davey, S. C.

1988-10-01

We have observed the self-reflection of intense, sub-picosecond 308 nm light pulse incident on a planar Al target and have inferred the electrical conductivity of solid density Al. The pulse lengths were sufficiently short that no significant expansion of the target occurred during the measurement.

Behavior Of A Simple Metal Under Ultrashort Pulse High Intensity Laser Illumination

NASA Astrophysics Data System (ADS)

Milchberg, H. M.; Freeman, R. R.; Davey, S. C.

1988-07-01

We have observed the self-reflection of intense, sub-picosecond 308 nm light pulse incident on a planar AI target and have inferred the electrical conductivity of solid density AI. The pulse lengths were sufficiently short that no significant expansion of the target occurred during the measurement.

Blocking and guiding adult sea lamprey with pulsed direct current from vertical electrodes

USGS Publications Warehouse

Johnson, Nicholas S.; Thompson, Henry T.; Holbrook, Christopher M.; Tix, John A.

2014-01-01

Controlling the invasion front of aquatic nuisance species is of high importance to resource managers. We tested the hypothesis that adult sea lamprey (Petromyzon marinus), a destructive invasive species in the Laurentian Great Lakes, would exhibit behavioral avoidance to dual-frequency pulsed direct current generated by vertical electrodes and that the electric field would not injure or kill sea lamprey or non-target fish. Laboratory and in-stream experiments demonstrated that the electric field blocked sea lamprey migration and directed sea lamprey into traps. Rainbow trout (Oncorhynchus mykiss) and white sucker (Catostomus commersoni), species that migrate sympatrically with sea lamprey, avoided the electric field and had minimal injuries when subjected to it. Vertical electrodes are advantageous for fish guidance because (1) the electric field produced varies minimally with depth, (2) the electric field is not grounded, reducing power consumption to where portable and remote deployments powered by solar, wind, hydro, or a small generator are feasible, and (3) vertical electrodes can be quickly deployed without significant stream modification allowing rapid responses to new invasions. Similar dual-frequency pulsed direct current fields produced from vertical electrodes may be advantageous for blocking or trapping other invasive fish or for guiding valued fish around dams.

Respiratory analysis system and method

NASA Technical Reports Server (NTRS)

Liu, F. F. (Inventor)

1973-01-01

A system is described for monitoring the respiratory process in which the gas flow rate and the frequency of respiration and expiration cycles can be determined on a real time basis. A face mask is provided with one-way inlet and outlet valves where the gas flow is through independent flowmeters and through a mass spectrometer. The opening and closing of a valve operates an electrical switch, and the combination of the two switches produces a low frequency electrical signal of the respiratory inhalation and exhalation cycles. During the time a switch is operated, the corresponsing flowmeter produces electric pulses representative of the flow rate; the electrical pulses being at a higher frequency than that of the breathing cycle and combined with the low frequency signal. The high frequency pulses are supplied to conventional analyzer computer which also receives temperature and pressure inputs and computes mass flow rate and totalized mass flow of gas. From the mass spectrometer, components of the gas are separately computed as to flow rate. The electrical switches cause operation of up-down inputs of a reversible counter. The respective up and down cycles can be individually monitored and combined for various respiratory measurements.

Electrically stimulated contractions of Vorticella convallaria

NASA Astrophysics Data System (ADS)

Kantha, Deependra; van Winkle, David

2009-03-01

The contraction of Vorticella convallaria was triggered by applying a voltage pulse in its host culturing medium. The 50V, 1ms wide pulse was applied across platinum wires separated by 0.7 cm on a microscope slide. The contractions were recorded as cines (image sequences) by a Phantom V5 camera (Vision Research) on a bright field microscope with 20X objective, with the image size of 256 pixels x 128 pixels at 7352 pictures per second. The starting time of the cines was synchronized with the starting of the electrical pulse. We recorded five contractions of each of 12 organisms. The cines were analyzed to obtain the initiation time, defined as the difference in time between the leading edge of the electrical pulse and the first frame showing zooid movement. From multiple contractions of same organism, we found the initiation time is reproducible. In comparing different organisms, we found the average initiation time of 1.73 ms with a standard deviation of 0.63 ms. This research is supported by the state of Florida (MARTECH) and Research Corporation.

Saturable inductor and transformer structures for magnetic pulse compression

DOEpatents

Birx, Daniel L.; Reginato, Louis L.

1990-01-01

Saturable inductor and transformer for magnetic compression of an electronic pulse, using a continuous electrical conductor looped several times around a tightly packed core of saturable inductor material.

THE NATURE OF ENERGY TRANSFER TO ELECTRODES IN A PULSE DISCHARGE WITH SMALL GAPS,

DTIC Science & Technology

SPARK MACHINING, ELECTRIC DISCHARGES), (*ELECTROMAGNETIC PULSES, SPARK MACHINING), ELECTROEROSIVE MACHINING, ENERGY, ELECTRON IRRADIATION, ION BOMBARDMENT, THERMAL CONDUCTIVITY, FILMS, KINETIC ENERGY, ZONE MELTING, USSR

Method and apparatus for characterizing reflected ultrasonic pulses

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor); Cantrell, John H., Jr. (Inventor)

1991-01-01

The invention is a method of and apparatus for characterizing the amplitudes of a sequence of reflected pulses R1, R2, and R3 by converting them into corresponding electric signals E1, E2, and E3 to substantially the same value during each sequence thereby restoring the reflected pulses R1, R2, and R3 to their initial reflection values by timing means, an exponential generator, and a time gain compensator. Envelope and baseline reject circuits permit the display and accurate location of the time spaced sequence of electric signals having substantially the same amplitude on a measurement scale on a suitable video display or oscilloscope.

The effect of high-frequency electrical pulses on organic tissue in root canals.

PubMed

Lendini, M; Alemanno, E; Migliaretti, G; Berutti, E

2005-08-01

To evaluate debris and smear layer scores after application of high-frequency electrical pulses produced by the Endox Endodontic System (Lysis Srl, Nova Milanese, Italy) on intact pulp tissue and organic and inorganic residues after endodontic instrumentation. The study comprised 75 teeth planned for extraction. The teeth were randomly divided into two groups (60 teeth) and a control group (15 teeth): group 1 (30 teeth) was not subjected to instrumentation; group 2 (30 teeth) was instrumented by Hero Shaper instruments and apical stops were prepared to size 40. Each group was subdivided into subgroups A and B (15 teeth); two electrical pulses were applied to subgroups 1A and 2A (one in the apical third and one in the middle third, respectively, at 3 and 6 mm from the root apices); four electrical pulses were applied to subgroups 1B and 2B (two in the apical third, two in the middle third). The control group (15 teeth) was prepared with Hero Shapers and irrigated with 5 mL of EDTA (10%) and 5 mL of 5% NaOCl at 50 degrees C but not subjected to the electrical pulse treatment. Roots were split longitudinally and canal walls were examined at 80x, 200x, 750x, 1500x and 15,000x magnifications, using a scanning electron microscope. Smear layer and debris scores were recorded at the 3 and 6 mm levels using a five-step scoring scale and a 200-microm grid. Means were tested for significance using the one-way anova model and the Bonferroni post-hoc test. The differences between groups were considered to be statistically significant when P < 0.05. The mean value for debris scores for the three groups varied from 1.80 (+/-0.77) to 4.50 (+/-0.68). The smear layer scores for group 2 and the control specimens varied from 2.00 (+/-0.91) to 2.33 (+/-0.99). A significant difference was found in mean debris scores at the 3 and 6 mm levels between the three groups (P < 0.001). The Bonferroni post-hoc test confirmed that the difference was due to group 1. In the two subgroups treated with four high-frequency pulses (1B and 2B) a substantial reduction in mean debris scores was found at the 3 and 6 mm level; subgroup 2B was practically free of organic residue. No significant differences for mean smear layer and debris scores were recorded between group 2 and the control group at the two levels; a significant difference was found only for mean smear layer scores at the 3 mm level between subgroup 2B and the control group (P < 0.05). The Endox device used with four electrical pulses had optimal efficacy when used after mechanical instrumentation. Traditional canal shaping and cleaning was essential to ensure an effective use of high-frequency electrical pulses in eliminating residues of pulp tissue and inorganic debris.

Waveform synthesizer

DOEpatents

Franks, L.A.; Nelson, M.A.

1979-12-07

The invention is a method by which an optical pulse of an arbitrary but defined shape may be transformed into a virtual multitude of optical or electrical output pulse shapes. Since the method is not limited to any particular input pulse shape, the output pulse shapes that can be generated thereby are virtually unlimited. Moreover, output pulse widths as narrow as about 0.1 nsec can be readily obtained since optical pulses of less than a few picoseconds are available for use as driving pulses. The range of output pulse widths obtainable is very large, the limiting factors being the driving source energy and the particular shape of the desired output pulse.

Avoiding neuromuscular stimulation in liver irreversible electroporation using radiofrequency electric fields

NASA Astrophysics Data System (ADS)

Castellví, Quim; Mercadal, Borja; Moll, Xavier; Fondevila, Dolors; Andaluz, Anna; Ivorra, Antoni

2018-02-01

Electroporation-based treatments typically consist of the application of high-voltage dc pulses. As an undesired side effect, these dc pulses cause electrical stimulation of excitable tissues such as motor nerves. The present in vivo study explores the use of bursts of sinusoidal voltage in a frequency range from 50 kHz to 2 MHz, to induce irreversible electroporation (IRE) whilst avoiding neuromuscular stimulation. A series of 100 dc pulses or sinusoidal bursts, both with an individual duration of 100 µs, were delivered to rabbit liver through thin needles in a monopolar electrode configuration, and thoracic movements were recorded with an accelerometer. Tissue samples were harvested three hours after treatment and later post-processed to determine the dimensions of the IRE lesions. Thermal damage due to Joule heating was ruled out via computer simulations. Sinusoidal bursts with a frequency equal to or above 100 kHz did not cause thoracic movements and induced lesions equivalent to those obtained with conventional dc pulses when the applied voltage amplitude was sufficiently high. IRE efficacy dropped with increasing frequency. For 100 kHz bursts, it was estimated that the electric field threshold for IRE is about 1.4 kV cm-1 whereas that of dc pulses is about 0.5 kV cm-1.

Analysis of the transfer function for layered piezoelectric ultrasonic sensors

NASA Astrophysics Data System (ADS)

Gutiérrrez-Reyes, E.; García-Segundo, C.; García-Valenzuela, A.; Reyes-Ramírez, B.; Gutiérrez-Juárez, G.; Guadarrama-Santana, A.

2017-06-01

We model theoretically the voltage response to an acoustic pulse of a multilayer system forming a low noise capacitive sensor including a Polyvinylidene Fluoride piezoelectric film. First we model a generic piezoelectric detector consisting of a piezoelectric film between two metallic electrodes that are the responsible to convert the acoustic signal into a voltage signal. Then we calculate the pressure-to-voltage transfer function for a N-layer piezo-electric capacitor detector, allowing to study the effects of the electrode and protective layers thickness in typical layered piezoelectric sensors. The derived transfer function, when multiplied by the Fourier transform of the incident acoustic pulse, gives the voltage electric response in the frequency domain. An important concern regarding the transfer function is that it may have zeros at specific frequencies, and thus inverting the voltage Fourier transform of the pulse to recover the pressure signal in the time domain is not always, in principle, possible. Our formulas can be used to predict the existence and locations of such zeroes. We illustrate the use of the transfer function by predicting the electric signal generated at a multilayer piezoelectric sensor to an ultrasonic pulse generated photoacoustically by a laser pulse at a three media system with impedance mismatch. This theoretical calculations are compared with our own experimental measurements.

Nanosecond pulsed electric field induced changes in cell surface charge density.

PubMed

Dutta, Diganta; Palmer, Xavier-Lewis; Asmar, Anthony; Stacey, Michael; Qian, Shizhi

2017-09-01

This study reports that the surface charge density changes in Jurkat cells with the application of single 60 nanosecond pulse electric fields, using atomic force microscopy. Using an atomic force microscope tip and Jurkat cells on silica in a 0.01M KCl ionic concentration, we were able to measure the interfacial forces, while also predicting surface charge densities of both Jurkat cell and silica surfaces. The most important finding is that the pulsing conditions varyingly reduced the cells' surface charge density. This offers a novel way in which to examine cellular effects of pulsed electric fields that may lead to the identification of unique mechanical responses. Compared to a single low field strength NsPEF (15kV/cm) application, exposure of Jurkat cells to a single high field strength NsPEF (60kV/cm) resulted in a further reduction in charge density and major morphological changes. The structural, physical, and chemical properties of biological cells immensely influence their electrostatic force; we were able to investigate this through the use of atomic force microscopy by measuring the surface forces between the AFM's tip and the Jurkat cells under different pulsing conditions as well as the interfacial forces in ionic concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Avoiding nerve stimulation in irreversible electroporation: a numerical modeling study

NASA Astrophysics Data System (ADS)

Mercadal, Borja; Arena, Christopher B.; Davalos, Rafael V.; Ivorra, Antoni

2017-10-01

Electroporation based treatments consist in applying one or multiple high voltage pulses to the tissues to be treated. As an undesired side effect, these pulses cause electrical stimulation of excitable tissues such as nerves and muscles. This increases the complexity of the treatments and may pose a risk to the patient. To minimize electrical stimulation during electroporation based treatments, it has been proposed to replace the commonly used monopolar pulses by bursts of short bipolar pulses. In the present study, we have numerically analyzed the rationale for such approach. We have compared different pulsing protocols in terms of their electroporation efficacy and their capability of triggering action potentials in nerves. For that, we have developed a modeling framework that combines numerical models of nerve fibers and experimental data on irreversible electroporation. Our results indicate that, by replacing the conventional relatively long monopolar pulses by bursts of short bipolar pulses, it is possible to ablate a large tissue region without triggering action potentials in a nearby nerve. Our models indicate that this is possible because, as the pulse length of these bipolar pulses is reduced, the stimulation thresholds raise faster than the irreversible electroporation thresholds. We propose that this different dependence on the pulse length is due to the fact that transmembrane charging for nerve fibers is much slower than that of cells treated by electroporation because of their geometrical differences.

Pulsed Electric Fields for Biological Weapons Defense

DTIC Science & Technology

2008-09-30

multifunctional biological transporters and near - infrared agents for selective cancer cell destruction. Proc Natl Acad Sci U S A 102, 11600-5. 45. Heller, D. A...controlled biochemical manipulation. Nanotechnology 14,551-556. 47. Cherukuri, P., Bachilo, S. M., Litovsky, S. H., and Weisman, R. B. (2004). Near - infrared ...Pulsed Electric Fields for Biological Weapons Defense AFOSR Grant No. FA9550-05-1-0081 P.I. Martin Gundersen atrophaeus and isolates from dental patients

Apparatus for processing electromagnetic radiation and method

NASA Technical Reports Server (NTRS)

Gatewood, George D. (Inventor)

1983-01-01

Measuring apparatus including a ruled member having alternate transparent and opaque zones. An optical coupler connecting the ruled member with electromagnetic radiation-conversion apparatus. The conversion apparatus may include a photomultiplier and a discriminator. Radiation impinging on the ruled member will, in part, be converted to electrical pulses which correspond to the intensity of the radiation. A method of processing electromagnetic radiation includes providing a member having alternating dark and light zones, establishing movement of the member through the beam of electromagnetic radiation with the dark zones interrupting passage of radiation through the rule, providing an optical coupler to connect a portion of the radiation with a conversion station where the radiation portion is converted into an electrical pulse which is related to the intensity of the radiation received at the conversion station. The electrical pulses may be counted and the digitized signals stored or permanently recorded to produce positional information.

Electrical characteristics of thin Ta2O5 films deposited by reactive pulsed direct-current magnetron sputtering

NASA Astrophysics Data System (ADS)

Kim, J.-Y.; Nielsen, M. C.; Rymaszewski, E. J.; Lu, T.-M.

2000-02-01

Room temperature deposition of tantalum oxide films on metallized silicon substrates was investigated by reactive pulsed magnetron sputtering of Ta in an Ar/O2 ambient. The dielectric constant of the tantalum oxide ranged from 19 to 31 depending on the oxygen percentage [P(%)=PO2/(PO2+PAr)] used during sputtering. The leakage current density was less than 10 nA/cm2 at 0.5 MV/cm electric field and the dielectric breakdown field was greater than 3.8 MV/cm for P=60%. A charge storage as high as 3.3 μF/cm2 was achieved for 70-Å-thick film. Pulse frequency variation (from 20 to 200 kHz) did not give a significant effect in the electrical properties (dielectric constant or leakage current density) of the Ta2O5 films.

Multiphoton imaging reveals that nanosecond pulsed electric fields collapse tumor and normal vascular perfusion in human glioblastoma xenografts.

PubMed

Bardet, Sylvia M; Carr, Lynn; Soueid, Malak; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

2016-10-04

Despite the biomedical advances of the last century, many cancers including glioblastoma are still resistant to existing therapies leaving patients with poor prognoses. Nanosecond pulsed electric fields (nsPEF) are a promising technology for the treatment of cancer that have thus far been evaluated in vitro and in superficial malignancies. In this paper, we develop a tumor organoid model of glioblastoma and apply intravital multiphoton microscopy to assess their response to nsPEFs. We demonstrate for the first time that a single 10 ns, high voltage electric pulse (35-45 kV/cm), collapses the perfusion of neovasculature, and also alters the diameter of capillaries and larger vessels in normal tissue. These results contribute to the fundamental understanding of nsPEF effects in complex tissue environments, and confirm the potential of nsPEFs to disrupt the microenvironment of solid tumors such as glioblastoma.

[Observation on non-invasive electrode pulse electric stimulation for treatment of Bell's palsy].

PubMed

Guo, Qing-Hua; Yan, Jian-Zhen; Yan, Wu-Shen; Xiao, Mei-Zhen

2006-12-01

To explore non-invasive therapy for treatment of Bell palsy. Two hundred and seventy-six were randomly divided into two groups, a treatment group and a control group, 138 cases in each group. The treatment group were treated with non-invasive electrode pulse electric stimulation at Taiyang (EX-HN 5), Sibai (ST 2), Qianzheng (Extra), Dicang (ST 4), and the control group with routine medicine (prednisone, dibazol, vitamine B complex and Qianzheng Powder), once each day, 10 days constituting one course. After two courses, their therapeutic effects were compared. The cured rate and the effective rate were 83.3% and 99.3% in the treatment group, and 48.5% and 88.4% in the control group respectively with a significant difference between the two groups (P < 0.05). Non-invasive electrode pulse electric stimulation at facial points has obvious therapeutic effect on Bell palsy.

9 CFR 307.7 - Safety requirements for electrical stimulating (EST) equipment.

Code of Federal Regulations, 2012 CFR

2012-01-01

... requirements for electrical stimulating (EST) equipment. (a) General. Electrical stimulating (EST) equipment is... of facilitating blood removal. These provisions do not apply to electrical equipment used to stun and... generate pulsed DC or AC voltage for stimulation and is separate from the equipment used to apply the...

9 CFR 307.7 - Safety requirements for electrical stimulating (EST) equipment.

Code of Federal Regulations, 2014 CFR

2014-01-01

... requirements for electrical stimulating (EST) equipment. (a) General. Electrical stimulating (EST) equipment is... of facilitating blood removal. These provisions do not apply to electrical equipment used to stun and... generate pulsed DC or AC voltage for stimulation and is separate from the equipment used to apply the...

Frequency-time coherence for all-optical sampling without optical pulse source

PubMed Central

Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

2016-01-01

Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift. PMID:27687495

Electric field controlled emulsion phase contactor

DOEpatents

Scott, Timothy C.

1995-01-01

A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

Method of using an electric field controlled emulsion phase contactor

DOEpatents

Scott, Timothy C.

1993-01-01

A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

Electric field controlled emulsion phase contactor

DOEpatents

Scott, T.C.

1995-01-31

A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figs.

Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

PubMed Central

Liu, Chong; Dobrynin, Danil; Fridman, Alexander

2014-01-01

In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field.

PubMed

Liu, Chong; Dobrynin, Danil; Fridman, Alexander

2014-06-25

In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge.

Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

PubMed

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic.

In vitro analysis of various cell lines responses to electroporative electric pulses by means of electrical impedance spectroscopy.

PubMed

García-Sánchez, Tomás; Bragós, Ramon; Mir, Lluis M

2018-06-07

This paper reports the comparative analysis, by means of electric impedance spectroscopy measurements, of three different cell lines subjected to electroporative pulses. The multifrequency information is recorded simultaneously at 21 frequency values in the range between 5 kHz and 1.3 MHz using a multisine based measuring approach. The analysis of the pre-electroporation impedance spectra shows how the system is able to detect differences and similarities between the cell lines under analysis. Particularly, a good agreement is found between the average cell diameter and the characteristic frequency (the frequency corresponding to a maximum in the imaginary part of the impedance). The measurements performed during electroporation at three different electric field intensities show how the impedance spectra changes dynamically between the consecutive pulses of a train of 8,100 µs pulses delivered at 1 Hz repetition rate. There are clear differences between the changes in the impedance measured at low and high frequency. The multifrequency information has been fitted to an electrical equivalent model in order to understand the different contributions in the observed impedance changes (mainly separate between membrane permeabilization and the conductivity changes in the extracellular medium). Finally, a ratio of the low and high frequency impedance information is used to estimate the accumulated impedance decay and to compare it to the internalization of a fluorescent permeabilization reporter. The comparison between both techniques at the three electroporation electric field intensities assayed confirms the ability of impedance measurements to detect in a precise way the level of membrane permeabilization. Additionally, this study demonstrates how the real time information obtained thanks to impedance measurements can provide a more precise quantification of the membrane permeabilization extent. Copyright © 2018 Elsevier B.V. All rights reserved.

[Exposure to electrocution by automotive ignition system in the work environment of car service employees].

PubMed

Fryśkowski, Bernard; Swiatek-Fryśkowska, Dorota

2014-01-01

Automotive ignition system diagnostic procedures involve a specific kind of action due to the presence of high voltage pulses rated of roughly several dozen kilovolts. Therefore, the repairers employed at car service coming into direct contact with electrical equipment of ignition systems are exposed to risk of electric shock. Typically, the electric discharge energy of automotive ignition systems is not high enough to cause fibrillation due to the electric effect on the heart. Nevertheless, there are drivers and car service employees who use electronic cardiac pacemakers susceptible to high voltage pulses. The influence of high-voltage ignition systems on the human body, especially in case of electric injury, has not been comprehensively elucidated. Therefore, relatively few scientific papers address this problem. The aim of this paper is to consider the electrical injury danger from automotive ignition systems, especially in people suffering from cardiac diseases. Some examples of the methods to reduce electric shock probability during diagnostic procedures of spark-ignition combustion engines are presented and discussed.

The seizure, not electricity, is essential in convulsive therapy: the flurothyl experience.

PubMed

Fink, Max

2014-06-01

For more than 50 years, research in convulsive therapy has been focused on the impact of electricity and seizures on memory and not on brain chemistry or neurophysiology. Brief pulse and ultra-brief pulse currents replaced sinusoidal currents. Electrode placements were varied, energy dosing was altered, and electricity was replaced by magnetic currents. The published experiences and archival records of seizures induced by camphor, pentylenetetrazol, and flurothyl are reviewed and compared with the changes induced by electricity. The clinical efficacy of chemically induced seizures is equal to that of electrical inductions. Seizure durations are longer, and impairment of cognition and memory is less. Electroconvulsive therapy replaced chemical treatments for ease of use, not for greater efficacy or safety. The brain seizure, not the method of induction, is the essential element in the efficacy of convulsive therapy. Seizure induction with chemicals avoids the direct effects of electricity on brain functions with lesser effects on cognition. Reexamination of chemical inductions of seizures as replacements for electricity is encouraged.

Comparative Study of Pulp Vitality in Primary and Young Permanent Molars in Human Children with Pulse Oximeter and Electric Pulp Tester.

PubMed

Shahi, Prinka; Sood, P B; Sharma, Arun; Madan, Manish; Shahi, Nishat; Gandhi, Geetanjali

2015-01-01

The purpose of this study was to compare the pulp testing methods (pulse oximetry and electric pulp test) in primary and young permanent teeth of children. The study included a total of 155 children aged 4 to 15 years. Twenty children formed control group I. Study group included all healthy, 85 primary 2nd molars in group II and 85 permanent 1st molars in group III. Fifty children needing endodontics treatment formed test group IV. The readings were recorded as true positive (TP), false positive (FP), true negative (TN), false negative (FN). Based on this, the sensitivity, specificity, positive predictive value and negative predictive value were calculated for each method. The results were statistically analyzed using Chi-square test. On comparing pulse oximetry with electric pulp test 'p-value' was found to be 0.487 and 1.00 for groups 1 and 2 respectively and was statistically not significant. Whereas 'p-value' for groups 3 and 4 was < 0.0001 and 0.003 respectively and was statistically highly significant. The present study indicates that pulse oximetry can be used as a routine method for assessing the pulp vitality in primary, young permanent and mature permanent teeth. How to cite this article: Shahi P, Sood PB, Sharma A, Madan M, Shahi N, Gandhi G. Comparative Study of Pulp Vitality in Primary and Young Permanent Molars in Human Children with Pulse Oximeter and Electric Pulp Tester. Int J Clin Pediatr Dent 2015;8(2):94-98.

Some Aspects of PDC Electrolysis

NASA Astrophysics Data System (ADS)

Poláčik, Ján; Pospíšil, Jiří

2016-10-01

In this paper, aspects of pulsed direct current (PDC) water splitting are described. Electrolysis is a simple and well-known method to produce hydrogen. The efficiency is relatively low in normal conditions using conventional DC. PDC in electrolysis brings about many advantages. It increases efficiency of hydrogen production, and performance of the electrolyser may be smoothly controlled without compromising efficiency of the process. In our approach, ultra-short pulses are applied. This method enhances efficiency of electrical energy in the process of decomposition of water into hydrogen and oxygen. Efficiency depends on frequency, shape and width of the electrical pulses. Experiments proved that efficiency was increased by 2 to 8 per cent. One of the prospects of PDC electrolysis producing hydrogen is in increase of efficiency of energy storage efficiency in the hydrogen. There are strong efforts to make the electrical grid more efficient and balanced in terms of production by installing electricity storage units. Using hydrogen as a fuel decreases air pollution and amount of carbon dioxide emissions in the air. In addition to energy storage, hydrogen is also important in transportation and chemical industry.

Consolidation of materials by pulse-discharge processes

NASA Astrophysics Data System (ADS)

Strizhakov, E. L.; Nescoromniy, S. V.

2017-07-01

The article presents the research and the analysis of the pulse-discharge processes of capacitor discharge sintering: CD Stud Welding, capacitor discharge percussion welding (CDPW), high-voltage capacitor welding with an inductive-dynamic drive (HVCW with IDD), pulse electric current sintering (PECS) of powders. The comparative analysis of the impact parameter is presented.

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

NASA Astrophysics Data System (ADS)

Kar, S.; Ahmed, H.; Nersisyan, G.; Brauckmann, S.; Hanton, F.; Giesecke, A. L.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

2016-05-01

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ˜20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Nersisyan, G.

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from amore » laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.« less

Highly Efficient Vector-Inversion Pulse Generators

NASA Technical Reports Server (NTRS)

Rose, Franklin

2004-01-01

Improved transmission-line pulse generators of the vector-inversion type are being developed as lightweight sources of pulsed high voltage for diverse applications, including spacecraft thrusters, portable x-ray imaging systems, impulse radar systems, and corona-discharge systems for sterilizing gases. In this development, more than the customary attention is paid to principles of operation and details of construction so as to the maximize the efficiency of the pulse-generation process while minimizing the sizes of components. An important element of this approach is segmenting a pulse generator in such a manner that the electric field in each segment is always below the threshold for electrical breakdown. One design of particular interest, a complete description of which was not available at the time of writing this article, involves two parallel-plate transmission lines that are wound on a mandrel, share a common conductor, and are switched in such a manner that the pulse generator is divided into a "fast" and a "slow" section. A major innovation in this design is the addition of ferrite to the "slow" section to reduce the size of the mandrel needed for a given efficiency.

Novel ultra-wideband (UWB) photonic generation through photodetection and cross-absorption modulation in a single electroabsorption modulator.

PubMed

Wu, Tsu-Hsiu; Wu, Jui-pin; Chiu, Yi-Jen

2010-02-15

We propose and demonstrate, by proof of concept, a novel method of ultra-wide band (UWB) photonic generation using photodetection and cross-absorption modulation (XAM) of multiple quantum wells (MQW) in a single short-terminated electroabsorption modulator (SEAM). As an optical pump pulse excite the MQWs of SEAM waveguide, the probe light pulse with the same polarity can be generated through XAM, simultaneously creating photocurrent pulse propagating along the waveguide. Using the short termination of SEAM accompanied by the delayed microwave line, the photocurrent pulse can be reversed in polarity and re-modulated the waveguide, forming a monocycle UWB optical pulse. An 89 ps cycle of monocycle pulse with 114% fractional bandwidth is obtained, where the electrical power spectrum centered at 4 GHz of frequency ranges from 0.1 GHz to 8 GHz for -10 dB drops. Meanwhile, the generation processing is also confirmed by observing the same cycle of monocycle electrical pulse from the photodetection of SEAM. The whole optical processing is performed inside a compact semiconductor device, suggesting the optoelectronic integration template has a potential for the application of UWB photonic generation.

Needle-array to Plate DBD Plasma Using Sine AC and Nanosecond Pulse Excitations for Purpose of Improving Indoor Air Quality

PubMed Central

Zhang, Li; Yang, Dezheng; Wang, Wenchun; Wang, Sen; Yuan, Hao; Zhao, Zilu; Sang, Chaofeng; Jia, Li

2016-01-01

In this study, needle-array to plate electrode configuration was employed to generate an atmospheric air diffuse discharge using both nanosecond pulse and sine AC voltage as excitation voltage for the purpose of improving indoor air quality. Different types of voltage sources and electrode configurations are employed to optimize electrical field distribution and improve discharge stability. Discharge images, electrical characteristics, optical emission spectra, and plasma gas temperatures in both sine AC discharge and nanosecond pulse discharge were compared and the discharge stability during long operating time were discussed. Compared with the discharge excited by sine AC voltage, the nanosecond pulsed discharge is more homogenous and stable, besides, the plasma gas temperature of nanosecond pulse discharge is much lower. Using packed-bed structure, where γ- Al2O3 pellets are filled in the electrode gap, has obvious efficacy in the production of homogenous discharge. Furthermore, both sine AC discharge and nanosecond pulse discharge were used for removing formaldehyde from flowing air. It shows that nanosecond pulse discharge has a significant advantage in energy cost. And the main physiochemical processes for the generation of active species and the degradation of formaldehyde were discussed. PMID:27125663

Correlation between electric field pulse induced long-lived permeabilization and fusogenicity in cell membranes.

PubMed Central

Teissié, J; Ramos, C

1998-01-01

Electric field pulses have been reported to induce long-lived permeabilization and fusogenicity on cell membranes. The two membrane property alterations are under the control of the field strength, the pulse duration, and the number of pulses. Experiments on mammalian cells pulsed by square wave form pulses and then brought into contact randomly through centrifugation revealed an even stronger analogy between the two processes. Permeabilization was known to affect well-defined regions of the cell surface. Fusion can be obtained only when permeabilized surfaces on the two partners were brought into contact. Permeabilization was under the control of the pulse duration and of the number of pulses. A similar relationship was observed as far as fusion is concerned. But a critical level of local permeabilization must be present for fusion to take place when contacts are created. The same conclusions are obtained from previous experiments on ghosts subjected to exponentially decaying field pulses and then brought into contact by dielectrophoresis. These observations are in agreement with a model of membrane fusion in which the merging of local random defects occurs when the two membranes are brought into contact. The local defects are considered part of the structural membrane reorganization induced by the external field. Their density is dependent on the pulse duration and number of pulses. They support the long-lived permeabilization. Their number must be very large to support the occurrence of membrane fusion. PMID:9545050

Correlation between electric field pulse induced long-lived permeabilization and fusogenicity in cell membranes.

PubMed

Teissié, J; Ramos, C

1998-04-01

Electric field pulses have been reported to induce long-lived permeabilization and fusogenicity on cell membranes. The two membrane property alterations are under the control of the field strength, the pulse duration, and the number of pulses. Experiments on mammalian cells pulsed by square wave form pulses and then brought into contact randomly through centrifugation revealed an even stronger analogy between the two processes. Permeabilization was known to affect well-defined regions of the cell surface. Fusion can be obtained only when permeabilized surfaces on the two partners were brought into contact. Permeabilization was under the control of the pulse duration and of the number of pulses. A similar relationship was observed as far as fusion is concerned. But a critical level of local permeabilization must be present for fusion to take place when contacts are created. The same conclusions are obtained from previous experiments on ghosts subjected to exponentially decaying field pulses and then brought into contact by dielectrophoresis. These observations are in agreement with a model of membrane fusion in which the merging of local random defects occurs when the two membranes are brought into contact. The local defects are considered part of the structural membrane reorganization induced by the external field. Their density is dependent on the pulse duration and number of pulses. They support the long-lived permeabilization. Their number must be very large to support the occurrence of membrane fusion.

21 CFR 870.3600 - External pacemaker pulse generator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... power supply and electronic circuits that produce a periodic electrical pulse to stimulate the heart. This device, which is used outside the body, is used as a temporary substitute for the heart's...

21 CFR 870.3600 - External pacemaker pulse generator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... power supply and electronic circuits that produce a periodic electrical pulse to stimulate the heart. This device, which is used outside the body, is used as a temporary substitute for the heart's...

21 CFR 870.3600 - External pacemaker pulse generator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... power supply and electronic circuits that produce a periodic electrical pulse to stimulate the heart. This device, which is used outside the body, is used as a temporary substitute for the heart's...

21 CFR 870.3600 - External pacemaker pulse generator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... power supply and electronic circuits that produce a periodic electrical pulse to stimulate the heart. This device, which is used outside the body, is used as a temporary substitute for the heart's...

21 CFR 870.3600 - External pacemaker pulse generator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... power supply and electronic circuits that produce a periodic electrical pulse to stimulate the heart. This device, which is used outside the body, is used as a temporary substitute for the heart's...

NASA Tech Briefs, March 2006

NASA Technical Reports Server (NTRS)

2006-01-01

Topics covered include: Medical Signal-Conditioning and Data-Interface System; Instruments for Reading Direct-Marked Data-Matrix Symbols; Processing EOS MLS Level-2 Data; Ground Processing of Data From the Mars Exploration Rovers; Estimating Total Electron Content Using 1,000+ GPS Receivers; NASA Solar Array Demonstrates Commercial Potential; Improved Control of Charging Voltage for Li-Ion Battery; Programmable Pulse-Position-Modulation Encoder; Wavelength-Agile External-Cavity Diode Laser for DWDM; Pattern-Recognition Processor Using Holographic Photopolymer; Submicrosecond Power-Switching Test Circuit; Three-Function Logic Gate Controlled by Analog Voltage; Integrated System for Autonomous Science; Montage Version 3.0; Utilizing AI in Temporal, Spatial, and Resource Scheduling; Satellite Image Mosaic Engine; Architecture for Control of the K9 Rover; HFGMC Enhancement of MAC/GMC; Automated Activation and Deactivation of a System Under Test; Cleaning Carbon Nanotubes by Use of Mild Oxygen Plasmas; Generating Aromatics From CO2 on Mars or Natural Gas on Earth; Attaching Thermocouples by Peening or Crimping; Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates; Generating Breathable Air Through Dissociation of N2O; High-Performance Scanning Acousto-Ultrasonic System; Correction for Thermal EMFs in Thermocouple Feedthroughs; Using Quasiparticle Poisoning To Detect Photons; Estimating Resolution Lengths of Hybrid Turbulence Models; Education and Training Module in Alertness Management; Cargo-Positioning System for Next-Generation Spacecraft; Micro-Imagers for Spaceborne Cell-Growth Experiments; Holographic Solar Photon Thrusters; Plasma-Based Detector of Outer-Space Dust Particles; and Generation of Data-Rate Profiles of Ka-Band Deep-Space Links.

Power electromagnetic strike machine for engineering-geological surveys

NASA Astrophysics Data System (ADS)

Usanov, K. M.; Volgin, A. V.; Chetverikov, E. A.; Kargin, V. A.; Moiseev, A. P.; Ivanova, Z. I.

2017-10-01

When implementing the processes of dynamic sensing of soils and pulsed nonexplosive seismic exploration, the most common and effective method is the strike one, which is provided by a variety of structure and parameters of pneumatic, hydraulic, electrical machines of strike action. The creation of compact portable strike machines which do not require transportation and use of mechanized means is important. A promising direction in the development of strike machines is the use of pulsed electromagnetic actuator characterized by relatively low energy consumption, relatively high specific performance and efficiency, and providing direct conversion of electrical energy into mechanical work of strike mass with linear movement trajectory. The results of these studies allowed establishing on the basis of linear electromagnetic motors the electromagnetic pulse machines with portable performance for dynamic sensing of soils and land seismic pulse of small depths.

MULTI-CHANNEL PULSE HEIGHT ANALYZER

DOEpatents

Boyer, K.; Johnstone, C.W.

1958-11-25

An improved multi-channel pulse height analyzer of the type where the device translates the amplitude of each pulse into a time duration electrical quantity which is utilized to control the length of a train of pulses forwarded to a scaler is described. The final state of the scaler for any one train of pulses selects the appropriate channel in a magnetic memory in which an additional count of one is placed. The improvement consists of a storage feature for storing a signal pulse so that in many instances when two signal pulses occur in rapid succession, the second pulse is preserved and processed at a later time.

DIRECT COUPLED PROGRESSIVE STAGE PULSE COUNTER APPARATUS

DOEpatents

Kaufman, W.M.

1962-08-14

A progressive electrical pulse counter circuit was designed for the counting of a chain of input pulses of random width and/or frequency. The circuit employs an odd and even pulse input line alternately connected to a series of directly connected bistable counting stages. Each bistable stage has two d-c operative states which stage, when in its rnrtial state, prevents the next succeeding stage from changing its condition when the latter stage is pulsed. Since only altennate stages are pulsed for each incoming pulse, only one stage will change its state for each input pulse thereby providing prog essive stage by stage counting. (AEC)

Migration of cell surface concanavalin A receptors in pulsed electric fields.

PubMed Central

Lin-Liu, S; Adey, W R; Poo, M M

1984-01-01

Concanavalin A (con A) receptors on the surface of cultured Xenopus myoblasts redistributed in response to monopolar, pulsed electric fields. The prefield uniform distribution of the receptors became asymmetrical, and was polarized toward the cathodal pole, in the same way as in DC fields. The extent of asymmetry depended on the duration of field exposure, pulse width (or alternatively, interpulse interval), frequency, and intensity. This relationship was most conveniently expressed by using duty cycle, a quantity determined by both pulse width and frequency. Pulses of average intensity 1.5 V/cm induced detectable asymmetry within 5 min. At the lowest average field intensity used, 0.8 V/cm, significant asymmetry was detected at 150 min. For pulses of high duty cycle (greater than 25%), steady state was reached after 30 min exposure and the steady state asymmetry was dependent on average field intensity. For low duty cycle fields, the time required to reach steady state was prolonged (greater than 50 min). Before reaching a steady state, effectiveness of the pulses, as compared with DC fields of equivalent intensity, was a function of duty cycle. A low duty cycle field (fixed number of pulses at low frequency or long interpulse interval) was less effective than high duty cycle fields or DC. PMID:6743751

Social interactions between live and artificial weakly electric fish: Electrocommunication and locomotor behavior of Mormyrus rume proboscirostris towards a mobile dummy fish

PubMed Central

Kirschbaum, Frank; von der Emde, Gerhard

2017-01-01

Mormyrid weakly electric fish produce short, pulse-type electric organ discharges for actively probing their environment and to communicate with conspecifics. Animals emit sequences of pulse-trains that vary in overall frequency and temporal patterning and can lead to time-locked interactions with the discharge activity of other individuals. Both active electrolocation and electrocommunication are additionally accompanied by stereotypical locomotor patterns. However, the concrete roles of electrical and locomotor patterns during social interactions in mormyrids are not well understood. Here we used a mobile fish dummy that was emitting different types of electrical playback sequences to study following behavior and interaction patterns (electrical and locomotor) between individuals of weakly electric fish. We confronted single individuals of Mormyrus rume proboscirostris with a mobile dummy fish designed to attract fish from a shelter and recruit them into an open area by emitting electrical playbacks of natural discharge sequences. We found that fish were reliably recruited by the mobile dummy if it emitted electrical signals and followed it largely independently of the presented playback patterns. While following the dummy, fish interacted with it spatially by displaying stereotypical motor patterns, as well as electrically, e.g. through discharge regularizations and by synchronizing their own discharge activity to the playback. However, the overall emission frequencies of the dummy were not adopted by the following fish. Instead, social signals based on different temporal patterns were emitted depending on the type of playback. In particular, double pulses were displayed in response to electrical signaling of the dummy and their expression was positively correlated with an animals' rank in the dominance hierarchy. Based on additional analysis of swimming trajectories and stereotypical locomotor behavior patterns, we conclude that the reception and emission of electrical communication signals play a crucial role in mediating social interactions in mormyrid weakly electric fish. PMID:28902915

A Compact 700-KV Erected Pulse Forming Network for HPM Applications (Postprint)

DTIC Science & Technology

2011-04-28

previously investigated for driving rail guns , electric launchers, or other nonlinear loads albeit for much longer pulse lengths [8]. In this version...The output of the generator was connected to a coaxial CuS04 resistor through 100-ft of coaxial high-voltage cable. The current pulse on the cable was...shown in Figure 6. This pulse was delivered to a 50-ohm cable and measured by a coaxial inline CVR at the generator output. Typical pulse

Microwave-triggered laser switch

DOEpatents

Piltch, M.S.

1982-05-19

A high-repetition rate switch is described for delivering short duration, high-powered electrical pulses from a pulsed-charged dc power supply. The present invention utilizes a microwave-generating device such as a magnetron that is capable of producing high-power pulses at high-pulse repetition rates and fast-pulse risetimes for long periods with high reliability. The rail-gap electrodes provide a large surface area that reduces induction effects and minimizes electrode erosion. Additionally, breakdown is initiated in a continuous geometric fashion that also increases operating lifetime of the device.

Microwave-triggered laser switch

DOEpatents

Piltch, Martin S.

1984-01-01

A high-repetition rate switch for delivering short duration, high-power electrical pulses from a pulsed-charged dc power supply. The present invention utilizes a microwave-generating device such as a magnetron that is capable of producing high-power pulses at high-pulse repetition rates and fast-pulse risetimes for long periods with high reliability. The rail-gap electrodes provide a large surface area that reduces induction effects and minimizes electrode erosion. Additionally, breakdown is initiated in a continuous geometric fashion that also increases operating lifetime of the device.

Origin, Emission, and Propagation of P-H Pulses

NASA Astrophysics Data System (ADS)

Kikuchi, H.

2007-05-01

Origin, Emission, and Propagation of P-H Pulses H. Kikuchi Institute for Environmental Electromagnetics 3-8-18, Komagome, Toshima-ku, Tokyo 170, Japan e-mail: hkikuchi@mars.dti.ne.jp Abstract According to Pulinets, characters of P-H pulses is following. The registered emission has not continuous but pulsed character and has very wide frequency spectrum from kHz to more than hundred MHz. These two facts imply that should be the electric discharge-like emission similar to thunderstorm flashes emission. The emission is connected in some way with seismic activity and the emission intensity increases 12-24 hour before the seismic shock. Another intriguing factor is that emission is registered at large distances up to 500 km (some witness claim up to 1500 km). Taking into account that emission is registered at VHF band also, the source of emission cannot be situated on the ground. This paper puts forwards a model of P-H pulses generation based on "dust dynamics". Rotating ions ascending, for instance erupped metalic ions in the earth's crust into the atmosphere incorporating aerosols might be captured by diffuse dust layers which may exist below or beyond the electric mirror point produced by quadrupole-like thunder- cloud configurations or even form a portion of dust layers and could be a source-origin of P-H pulses that might be emitted by local electric discharges within diffuse dust layers somewhat similar to thundercloud discharges, though emission frequencies and characters are quite different, namely P-H pulses are over a wide range of frequencies, say from kHz to more than hundred MHz with pulsed character in contrast to lightning emission with more continuous character whose frequencies are 1 to 10 kHz. Such diffuse dust layers could be formed over a wide range of height in the troposphere, stratosphere, mesosphere and the thermosphere. Propagation distance of P-H pulses are very large up to 500-1500 km.

Rapid pulse annealing of CdZnTe detectors for reducing electronic noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voss, Lars; Conway, Adam; Nelson, Art

A combination of doping, rapid pulsed optical and/or thermal annealing, and unique detector structure reduces or eliminates sources of electronic noise in a CdZnTe (CZT) detector. According to several embodiments, methods of forming a detector exhibiting minimal electronic noise include: pulse-annealing at least one surface of a detector comprising CZT for one or more pulses, each pulse having a duration of .about.0.1 seconds or less. The at least one surface may optionally be ion-implanted. In another embodiment, a CZT detector includes a detector surface with two or more electrodes operating at different electric potentials and coupled to the detector surface;more » and one or more ion-implanted CZT surfaces on or in the detector surface, each of the one or more ion-implanted CZT surfaces being independently connected to one of the two or more electrodes and the surface of the detector. At least two of the ion-implanted surfaces are in electrical contact.« less

Technique of electrical stimulation of the vestibular analyzer under clinical conditions

NASA Technical Reports Server (NTRS)

Khechinashvili, S. N.; Zargaryan, B. M.; Karakozov, K. G.

1980-01-01

Vestibular reactions appear under the action of direct current (dc) on the labyrinth of man and animals. A decrease of the stimulation effect of dc on the extralabyrinthine nervous formations in the suggested method is achieved by the use of electric pulses with steep front and back parts, as well as by previous anesthetization of the skin in the electrode application area by means of novocain solution electrophoresis. For this purpose a pulse producer giving trapezoid pulses with smoothly changing fronts and duration was constructed. With the help of an interrupter it is possible to stop the current increase instantly, and stimulation is performed at the level of the pulse 'plateau'. To induce vestibular reactions under monopolar stimulation, it is necessary to apply the current twice as high as that with bipolar electrode position. The use of short pulses with steep front and back parts for electrode stimulation of the vestibular analyzer is considered to be inexpedient.

Photovoltaic Pixels for Neural Stimulation: Circuit Models and Performance.

PubMed

Boinagrov, David; Lei, Xin; Goetz, Georges; Kamins, Theodore I; Mathieson, Keith; Galambos, Ludwig; Harris, James S; Palanker, Daniel

2016-02-01

Photovoltaic conversion of pulsed light into pulsed electric current enables optically-activated neural stimulation with miniature wireless implants. In photovoltaic retinal prostheses, patterns of near-infrared light projected from video goggles onto subretinal arrays of photovoltaic pixels are converted into patterns of current to stimulate the inner retinal neurons. We describe a model of these devices and evaluate the performance of photovoltaic circuits, including the electrode-electrolyte interface. Characteristics of the electrodes measured in saline with various voltages, pulse durations, and polarities were modeled as voltage-dependent capacitances and Faradaic resistances. The resulting mathematical model of the circuit yielded dynamics of the electric current generated by the photovoltaic pixels illuminated by pulsed light. Voltages measured in saline with a pipette electrode above the pixel closely matched results of the model. Using the circuit model, our pixel design was optimized for maximum charge injection under various lighting conditions and for different stimulation thresholds. To speed discharge of the electrodes between the pulses of light, a shunt resistor was introduced and optimized for high frequency stimulation.

Time-resolved observation of coherent excitonic nonlinear response with a table-top narrowband THz pulse wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uchida, K.; Hirori, H., E-mail: hirori@icems.kyoto-u.ac.jp; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012

2015-11-30

By combining a tilted-pulse-intensity-front scheme using a LiNbO{sub 3} crystal and a chirped-pulse-beating method, we generated a narrowband intense terahertz (THz) pulse, which had a maximum electric field of more than 10 kV/cm at around 2 THz, a bandwidth of ∼50 GHz, and frequency tunability from 0.5 to 2 THz. By performing THz-pump and near-infrared-probe experiments on GaAs quantum wells, we observed that the resonant excitation of the intraexcitonic 1s-2p transition induces a clear and large Autler-Townes splitting. Our time-resolved measurements show that the splitting energy observed in the rising edge region of electric field is larger than in the constant region.more » This result implies that the splitting energy depends on the time-averaged THz field over the excitonic dephasing time rather than that at the instant of the exciton creation by a probe pulse.« less

Method and system for powering and cooling semiconductor lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Telford, Steven J; Ladran, Anthony S

A semiconductor laser system includes a diode laser tile. The diode laser tile includes a mounting fixture having a first side and a second side opposing the first side and an array of semiconductor laser pumps coupled to the first side of the mounting fixture. The semiconductor laser system also includes an electrical pulse generator thermally coupled to the diode bar and a cooling member thermally coupled to the diode bar and the electrical pulse generator.

Effects of electrical stimulus composition on cardiac electrophysiology in a rodent model of electroconvulsive therapy.

PubMed

Singh, Nagendra Madan; Sathyaprabha, T N; Thirthalli, Jagadisha; Andrade, Chittaranjan

2018-01-01

No electroconvulsive therapy (ECT) study on humans or in animal models has so far examined whether differently composed electrical stimuli exert different cardiac electrophysiological effects at constant electrical dose. The subject is important because cardiac electrophysiological changes may provide indirect information about ECT seizure quality as modulated by stimulus composition. Adult female Wistar rats ( n = 20/group) received fixed, moderately suprathreshold (18 mC) electrical stimuli. This stimulus in each of eight groups was formed by varying pulse amplitude, pulse width, pulse frequency, and stimulus duration. The electrocardiogram was recorded, and time and frequency domain variables were examined in 30 s epochs in preictal (30 s before electroconvulsive shock [ECS]), early postictal (starting 15 s after stimulation), and late postictal (5 h after ECS) periods. Alpha for statistical significance was set at P < 0.01 to adjust for multiple hypothesis testing. Cardiac electrophysiological indices in the eight groups did not differ significantly at baseline. At both early and late postictal time points, almost no analysis yielded statistically significant differences between groups for four time domain variables, including heart rate and standard deviation of R-R intervals, and for six frequency domain variables, including low-frequency power, high-frequency power, and total power. Cardiac electrophysiological measures may not be helpful to identify differences in seizure quality that are driven by differences in the composition of electrical stimuli at constant, moderately suprathreshold electrical dose. The generalization of this conclusion to threshold electrical doses and to human contexts requires a study.

Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

NASA Astrophysics Data System (ADS)

Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

2015-03-01

The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.