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Sample records for pulsed field slab

  1. Optimization of separation and detection schemes for DNA with pulsed field slab gel and capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, David A. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    The purpose of the Human Genome Project is outlined followed by a discussion of electrophoresis in slab gels and capillaries and its application to deoxyribonucleic acid (DNA). Techniques used to modify electroosmotic flow in capillaries are addressed. Several separation and detection schemes for DNA via gel and capillary electrophoresis are described. Emphasis is placed on the elucidation of DNA fragment size in real time and shortening separation times to approximate real time monitoring. The migration of DNA fragment bands through a slab gel can be monitored by UV absorption at 254 nm and imaged by a charge coupled device (CCD) camera. Background correction and immediate viewing of band positions to interactively change the field program in pulsed-field gel electrophoresis are possible throughout the separation. The use of absorption removes the need for staining or radioisotope labeling thereby simplifying sample preparation and reducing hazardous waste generation. This leaves the DNA in its native state and further analysis can be performed without de-staining. The optimization of several parameters considerably reduces total analysis time. DNA from 2 kb to 850 kb can be separated in 3 hours on a 7 cm gel with interactive control of the pulse time, which is 10 times faster than the use of a constant field program. The separation of ΦX174RF DNA-HaeIII fragments is studied in a 0.5% methyl cellulose polymer solution as a function of temperature and applied voltage. The migration times decreased with both increasing temperature and increasing field strength, as expected. The relative migration rates of the fragments do not change with temperature but are affected by the applied field. Conditions were established for the separation of the 271/281 bp fragments, even without the addition of intercalating agents. At 700 V/cm and 20°C, all fragments are separated in less than 4 minutes with an average plate number of 2.5 million per meter.

  2. A generalized slab-wise framework for parallel transmit multiband RF pulse design

    Science.gov (United States)

    Wu, Xiaoping; Schmitter, Sebastian; Auerbach, Edward J.; Uğurbil, Kâmil; de Moortele, Pierre-François Van

    2015-01-01

    Purpose We propose a new slab-wise framework to design parallel transmit multi-band pulses for volumetric simultaneous multi-slice imaging with a large field of view along the slice direction (FOVs). Theory and Methods The slab-wise framework divides FOVs into a few contiguous slabs and optimizes pulses for each slab. Effects of relevant design parameters including slab number and transmit B1 (B1+) mapping slice placement were investigated for human brain imaging by designing pulses with global or local SAR control based on electromagnetic simulations of a 7T head RF array. Pulse design using in-vivo B1+ maps was demonstrated and evaluated with Bloch simulations. Results RF performance with respect to SAR reduction or B1+ homogenization across the entire human brain improved with increasing slabs; however, this improvement was non-linear and leveled off at ~12 slabs when the slab thickness reduced to ~12 mm. The impact of using different slice placements for B1+ mapping was small. Conclusion Compared to slice-wise approaches where each of the many imaging slices requires both B1+ mapping and pulse optimization, the proposed slab-wise design framework is shown to attain comparable RF performance while drastically reducing the number of required pulses; therefore, it can be used to increase time efficiency for B1+ mapping, pulse calculation and sequence preparation. PMID:25994797

  3. Superluminal pulse reflection from a weakly absorbing dielectric slab

    CERN Document Server

    Wang, L G; Wang, Li-Gang; Zhu, Shi-Yao

    2006-01-01

    Group delay for a reflected light pulse from a weakly absorbing dielectric slab is theoretically investigated, and large negative group delay is found for weak absorption near a resonance of the slab ($Re(kd)=m\\pi$). The group delays for both the reflected and transmitted pulses will be saturated with the increase of the absorption.

  4. A modularized pulse forming line using glass-ceramic slabs.

    Science.gov (United States)

    Wang, Songsong; Shu, Ting; Yang, Hanwu

    2012-08-01

    In our lab, a kind of glass-ceramic slab has been chosen to study the issues of applying solid-state dielectrics to pulse forming lines (PFLs). Limited by the manufacture of the glass-ceramic bulk with large sizes, a single ceramic slab is hard to store sufficient power for the PFL. Therefore, a modularized PFL design concept is proposed in this paper. We regard a single ceramic slab as a module to form each single Blumlein PFL. We connect ceramic slabs in series to enlarge pulse width, and stack the ceramic Blumlein PFLs in parallel to increase the output voltage amplitude. Testing results of a single Blumlein PFL indicate that one ceramic slab contributes about 11 ns to the total pulse width which has a linear relation to the number of the ceramic slabs. We have developed a prototype facility of the 2-stage stacked Blumlein PFL with a length of 2 ceramic slabs. The PFL is dc charged up to 5 kV, and the output voltage pulse of 10 kV, 22 ns is measured across an 8 Ω load. Simulation and experiment results in good agreement demonstrate that the modularized design is reasonable.

  5. Pulsed electric fields

    Science.gov (United States)

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

  6. Time for pulse traversal through slabs of dispersive and negative ($\\epsilon$, $\\mu$) materials

    CERN Document Server

    Nanda, Lipsa

    2007-01-01

    The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity ($\\epsilon$) and magnetic permeability ($\\mu$) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-P\\'{e}rot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wigner delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon polariton modes in frequency ranges with negative $\\epsilon$ or $\\mu$ is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulse propagatin...

  7. Cross-field flow and electric potential in a plasma slab

    Directory of Open Access Journals (Sweden)

    J. De Keyser

    2013-08-01

    Full Text Available We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment.

  8. Excitation of the classical electromagnetic field in a cavity containing a thin slab with a time-dependent conductivity

    CERN Document Server

    Dodonov, V V

    2016-01-01

    An exact infinite set of coupled ordinary differential equations, describing the evolution of the modes of the classical electromagnetic field inside an ideal cavity, containing a thin slab with the time-dependent conductivity $\\sigma(t)$ and dielectric permittivity $\\varepsilon(t)$, is derived for the dispersion-less media. This problem is analyzed in connection with the attempts to simulate the so called Dynamical Casimir Effect in three-dimensional electromagnetic cavities, containing a thin semiconductor slab, periodically illuminated by strong laser pulses. Therefore it is assumed that functions $\\sigma(t)$ and $\\delta\\varepsilon(t)=\\varepsilon(t)-\\varepsilon(0)$ are different from zero during short time intervals (pulses) only. The main goal is to find the conditions, under which the initial nonzero classical field could be amplified after a single pulse (or a series of pulses). Approximate solutions to the dynamical equations are obtained in the cases of "small" and "big" maximal values of the function...

  9. Spreading pulses of the Tyrrhenian Sea during narrowing of the Calabrian slab

    Science.gov (United States)

    Guillaume, Benjamin; Funiciello, Francesca; Faccenna, Claudio; Martinod, Joseph; Olivetti, Valerio

    2010-05-01

    The opening of the Tyrrhenian Sea has been punctuated by short-lived episodes of oceanic accretion on separate small backarc basins during early Pliocene (Vavilov basin) and early Pleistocene (Marsili basin). These spreading pulses have been related to the rollback of the Ionian slab. They occurred following the reduction of the subduction zone width by the horizontal propagation of slab detachments, forming the narrow Calabrian arc. Nevertheless, the mechanisms leading to the episodic and transient behavior of the backarc region are hitherto unclear. To investigate the long term and transient effects of the reduction of slab width on the subduction kinematics, we perform dynamically self-consistent laboratory models consisting in a two-layer linearly viscous system simulating the roll-back of a fixed subducting plate (simulated using silicone putty) into the upper mantle (simulated using glucose syrup). We first show, with a set of experiments in which slab width is kept constant throughout experiment, that a six times increase in slab width (from 300 to 1800 km) produces a reduction of trench velocity of about 30%. We also observe that the abrupt reduction of the subducting plate width (from 1800 to 600 km) during experiment results in a pulse of acceleration of the trench retreat velocity of about 50%, as the balance between driving and resisting forces acting on the slab is temporarily modified. The Tyrrhenian acceleration phase can be reproduced if the slab is two to three orders of magnitude stronger than the uppermost part of the mantle, giving a range of mantle viscosity between 1019-1020 Pa s. Those values are low but reasonable as they may represent the shallow (first 100-200 km) and hot asthenosphere wedge expected in backarc regions. We propose that the fast and short pulses of spreading of the Tyrrhenian Sea resulted from the abrupt fragmentation of the subducting lithosphere, forming large windows. This model can be exported to other settings where

  10. Pulse Field Gel Electrophoresis.

    Science.gov (United States)

    Sharma-Kuinkel, Batu K; Rude, Thomas H; Fowler, Vance G

    2016-01-01

    Pulse Field Gel Electrophoresis (PFGE) is a powerful genotyping technique used for the separation of large DNA molecules (entire genomic DNA) after digesting it with unique restriction enzymes and applying to a gel matrix under the electric field that periodically changes direction. PFGE is a variation of agarose gel electrophoresis that permits analysis of bacterial DNA fragments over an order of magnitude larger than that with conventional restriction enzyme analysis. It provides a good representation of the entire bacterial chromosome in a single gel with a highly reproducible restriction profile, providing clearly distinct and well-resolved DNA fragments.

  11. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy

    2011-09-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  12. Near-field imaging of out-of-plane light scattering in photonic crystal slabs

    DEFF Research Database (Denmark)

    Volkov, Valentyn; Bozhevolnyi, Sergey; Taillaert, Dirk

    2003-01-01

    A collection scanning near-field optical microscope (SNOM) is used to image the propagating of light at telecommunication wavelengths (1520-1570 nm) along photonic crystal (PC) slabs, which combine slab waveguides with in-plane PCs consisting of one- and two-dimensional gratings. The efficient out...

  13. Slab stress field in the Hellenic subduction zone as inferred from intermediate depth earthquakes

    Science.gov (United States)

    Rontogianni, S.; Konstantinou, K.; Melis, N. S.; Evangelidis, C.

    2010-12-01

    In this study we investigate the stress regime of the subducting slab beneath the Hellenic Arc aiming to answer two fundamental questions; a) How does the slab deformation vary horizontally and vertically along this large curvature arc? b) Which are the mechanisms inferred from global observations that can explain this deformation and have not been identified previously due to dataset limitations. The data are selected from various seismic networks, global and local seismic catalogues and the newly established Hellenic broadband seismic network (http://bbnet.gein.noa.gr/). An updated view of the geometry of the Hellenic Wadati-Benioff zone (WBZ) is gained by the spatial distribution of intermediate depth earthquakes (40 km≤ depth ≤ 180km). Stress tensor inversion is performed on 100 fault plane solutions of intermediate depth earthquakes after quality control has been applied. The stress field parameters are determined along the arc for several depth ranges. The slab is divided into four subsets, each containing enough focal mechanisms for stress inversion to be performed successfully. The Peloponnese segment shows for depths 50-80 km σ1 almost normal to the slab and σ3 steeper than the slab dip that might indicate suction force-the component of the slab pull force that is unbalanced by the subduction resistance. The Kithira-Western Crete segment shows for depths 50-100 km a biaxial deviatoric compression or a state of confined compression with the σ1 along strike. The stress regime in this section of the slab might be related to its complex shape and geometry (width, curvature) reflecting changes in the slab dip between the Peloponnese-Kithira strait and the Crete region as has also been identified by teleseimic receiver functions. The third segment below Crete shows σ1 along strike and σ3 almost subvertical to slab direction. The stress field for the forth segment below Karpathos and Rhodos has been divided into two depth ranges. The shallow subset (50

  14. Research of electromagnetic field in different length left-handed material slab

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Finite-difference time-domain (FDTD) method is used to simulate the propagation of electromagnetic wave in left-handed material slab (LHMs) with cold plasma model The effects of optical propagation in the left-handed material compared to convex lens are discussed. The wider the LHMs is, the stronger electric field of focusing image in left-handed material slab is confirmed by the simulation with various slab length. However, the outer image point location would slightly moves to the LHMs side when the length of LHMs is reduced.

  15. Cryosurgery with pulsed electric fields.

    Science.gov (United States)

    Daniels, Charlotte S; Rubinsky, Boris

    2011-01-01

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

  16. Cryosurgery with pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Charlotte S Daniels

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

  17. Cryosurgery with Pulsed Electric Fields

    Science.gov (United States)

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

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

  18. A compact diode-pumped pulsed Nd:YAG slab laser based on a master oscillator power amplifier configuration

    Science.gov (United States)

    Maleki, A.; Kavosh Tehrani, M.; Saghafifar, H.; Moghtader Dindarlu, M. H.; Ebadian, H.

    2016-02-01

    In this paper, the design and construction of a pulsed Nd:YAG laser is described. The structure of this laser is based on a master oscillator power amplifier system. A master oscillator is an electro-optical Q-switched Nd:YAG rod laser. Face-pumping is used for the excitation of the slab structure, and a double-pass method is designed for the amplification stages. Two Nd:YAG zigzag slabs are utilized as power amplification stages in this laser. The laser diodes are stacked in a compact configuration and are used for rod and slabs pumping. The total pump energy in the amplifier stages is 3200 mJ at 808 nm. The output pulse energy achieved at 1064 nm is about 850 mJ of 10 ns pulse duration corresponding to 26.5% optical-to-optical conversion efficiency. Moreover, this laser can generate pulse energies around 430 mJ at 532 nm. The dependence of the output energy of MOPA and second harmonic generation operations on different pulse repetition rates (PRRs) from 1 to 100 Hz has been investigated. Experimental results show that the maximum fluctuations of the output energies are about 2.5 and 4% for 1064 and 532 nm, respectively.

  19. Casimir force between two parallel semiconductor slabs: Magnetic field effects in the Voigt geometry

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Serrano, R.; Palomino-Ovando, M. [Facultad de Ciencias Fisico-Matematicas, Universidad Autonoma de Puebla, Puebla (Mexico); Martinez, G.; Hernandez, P.H.; Cocoletzi, Gregorio H. [Instituto de Fisica, Universidad Autonoma de Puebla, Puebla (Mexico)

    2009-06-15

    We investigate the Casimir force F between two parallel semiconductor slabs taking into account magnetoplasmon effects. For our calculations we consider an external magnetic field applied in the Voigt geometry. Studies are carried out using the formula of F, which is written in terms of the reflectivities of the incident electromagnetic (EM) waves onto the surfaces of the semiconductor slabs, in the vacuum gap between slabs. Results show that the Casimir force depends strongly on the slab thickness as well as on the magnetic-field strength (or equivalently on the cyclotron frequency). At a constant cyclotron frequency and for small slab thickness F/F{sub 0} (F{sub 0} is the ideal force) displays a dip at small separation distances L between slabs. F/F{sub 0} increases with L up to saturation as the slab thickness increases. The curve with the strongest value of F/F{sub 0} corresponds to the semi-infinite medium geometry. For a constant slab thickness and small cyclotron frequency, F/F{sub 0} as a function of L shows a monotonic increase as L increases, and eventually reaches saturation. At high cyclotron frequency F/F{sub 0} displays a dip. The curve of F/F{sub 0} with no applied external field corresponds to the one with the strongest Casimir force. Therefore, magnetoplasmon effects, with an applied magnetic field in the Voigt geometry may inhibit the Casimir force. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Effect of nozzle outlet angle on flow and temperature field in a slab continuous casting mould

    Directory of Open Access Journals (Sweden)

    L. Sowa

    2011-04-01

    Full Text Available The mathematical and numerical simulation model of the growth of the solid metal phase within a continuous cast slab is presented in thispaper. The problem was treated as a complex one. The velocity fields are obtained by solving the momentum equations and the continuityequation, whereas the thermal fields are calculated by solving the conduction equation with the convection term. One takes intoconsideration in the mathematical model the changes of thermophysical parameters depending on the temperature and the solid phasevolume fractions in the mushy zone. The problem was solved by the finite element method. A numerical simulation of the cast slabsolidification process was made for different cases of continuous casting mould pouring by molten metal. The effect of nozzle outlet angle on the velocity fields in liquid phase and the solid phase growth kinetics of the cast slab were investigated, because these magnitudes have essential an influence on high-quality of a continuous steel cast slab.

  1. NUMERICAL SIMULATION OF TEMPERATURE FIELDS IN ELECTROSLAG REMELTING SLAB INGOTS

    Institute of Scientific and Technical Information of China (English)

    L.Z.Chang; B.Z.Li

    2008-01-01

    The method based on transient heat transfer model is adopted to simulate electro-slag remelting process.The calculated results of the model show that the process is in the quasi-steady state,and the shape of pool remains unchanged when the height of ingot is approximately 2.5-3 times the thickness of slab ingot.The change in the shape of pool is found to be strongly dependent on the pattern of melting rate,and hence,the power input;the depth of the molten pool increases with the increase in melting speed. It is concluded that a transient heat transfer model has to be used to obtain reliable input information for the entire operating time.

  2. Numerical calculation of superheating magnetic fields and currents for superconducting slabs

    Science.gov (United States)

    Landau, I. L.; Rinderer, L.

    1995-08-01

    Numerical calculations of superheating magnetic fields and superheating currents for superconducting slabs for a wide range of the sample thickness are presented. The calculations were made for low values of Ginzburg-Landau parameter κ, i.e., for type-1 superconductors. We propose also experimental procedures to measure superheating fields and currents in films and bulk samples.

  3. Stress field evolution above the Peruvian flat-slab (Cordillera Blanca, northern Peru)

    Science.gov (United States)

    Margirier, A.; Audin, L.; Robert, X.; Pêcher, A.; Schwartz, S.

    2017-08-01

    In subduction settings, the tectonic regime of the overriding plate is closely related to the geometry of the subducting plate. Flat-slab segments are supposed to increase coupling at the plate interface in the Andes, resulting in an increase and eastward migration of the shortening in the overriding plate. Above the Peruvian flat-slab, a 200 km-long normal fault trend parallel to the range and delimits the western flank of the Cordillera Blanca. In a context of flat subduction, expected to produce shortening, the presence of the Cordillera Blanca normal fault (CBNF) is surprising. We performed a systematic inversion of striated fault planes in the Cordillera Blanca region to better characterize the stress field above the Peruvian flat-slab. It evidences the succession of different tectonic regimes. NE-SW extension is predominant in most of the sites indicating a regional extension. We suggest that the Peruvian flat-slab trigger extension in the Western Cordillera while the shortening migrated eastward. Finally, we propose that flat-slab segments do not increase the coupling at the trench neither the shortening in the overriding plate but only favor shortening migration backward. However, the stress field of the overriding plate arises from the evolution of plate interface properties through time due to bathymetric anomaly migration.

  4. Theory of Pulsed Four-Wave-Mixing in One-dimensional Silicon Photonic Crystal Slab Waveguides

    CERN Document Server

    Lavdas, Spyros

    2015-01-01

    We present a comprehensive theoretical analysis and computational study of four-wave mixing (FWM) of optical pulses co-propagating in one-dimensional silicon photonic crystal waveguides (Si-PhCWGs). Our theoretical analysis describes a very general set-up of the interacting optical pulses, namely we consider nondegenerate FWM in a configuration in which at each frequency there exists a superposition of guiding modes. We incorporate in our theoretical model all relevant linear optical effects, including waveguide loss, free-carrier (FC) dispersion and FC absorption, nonlinear optical effects such as self- and cross-phase modulation (SPM, XPM), two-photon absorption (TPA), and cross-absorption modulation (XAM), as well as the coupled dynamics of FCs and optical field. In particular, our theoretical analysis based on the coupled-mode theory provides rigorously derived formulae for linear dispersion coefficients of the guiding modes, linear coupling coefficients between these modes, as well as the nonlinear waveg...

  5. Electric Field Enhancement in {\\epsilon}-near-zero Slabs under TM-Polarized Oblique Incidence

    CERN Document Server

    Campione, Salvatore; Vincenti, Maria Antonietta; Scalora, Michael; Capolino, Filippo

    2012-01-01

    We investigate local field enhancement phenomena in subwavelength, {\\epsilon}-near-zero (ENZ) slabs that do not exploit Fabry-P\\'erot resonances. In particular, we study the linear response of engineered metamaterial slabs of finite thickness based on plasmonic nanoshells that show an ENZ band in the visible range, and naturally occurring materials (e.g., SiO2) that also display ENZ properties, under oblique, TM-polarized plane wave incidence. We then introduce active gain material in engineered metamaterial slabs that adds peculiar spectral and angular features to transmission, reflection, and absorption properties, and leads to a further local field enhancement. These findings are supported by two theoretical studies: First, a simple interface between two semi-infinite media, namely free space and a generic ENZ medium; then, an ENZ slab of finite thickness, with the aim of understanding the system's behavior when varying the ENZ properties as well as the incident angle. For either case we report three disti...

  6. Pulsed electric field increases reproduction.

    Science.gov (United States)

    Panagopoulos, Dimitris J

    2016-01-01

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

  7. Directed cell movement in pulsed electric fields.

    Science.gov (United States)

    Franke, K; Gruler, H

    1994-01-01

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

  8. Electromagnetic absorption in a multilayered slab model of tissue under near-field exposure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, I.; Hagmann, M.J.; Gandhi, O.P.

    1980-01-01

    The electromagnetic energy deposited in a semi-infinite slab model consisting of skin, fat, and muscle layers is calculated for both plane-wave and near-field exposures. The plane-wave spectrum (PWS) approach is used to calculate the energy deposited in the model by fields present due to leakage from equipment using electromagnetic energy. This analysis applies to near-field exposures where coupling of the target to the leakage source can be neglected. Calculations were made for 2,450 MHz, at which frequency the layered slab adequately models flat regions of the human body. Resonant absorption due to layering is examined as a function of the skin and fat thicknesses for plane-wave exposure and as a function of the physical extent of the near-field distribution. Calculations show that for fields that are nearly constant over at least a free-space wavelength, the energy deposition (for skin, fat, and muscle combination that gives resonant absorption) is equal to or less than that resulting from plane-wave exposure, but is appreciably greater than that obtained for a homogeneous muscle slab model.

  9. Phase-resolved pulse propagation through metallic photonic crystal slabs: plasmonic slow light.

    Science.gov (United States)

    Schönhardt, Anja; Nau, Dietmar; Bauer, Christina; Christ, André; Gräbeldinger, Hedi; Giessen, Harald

    2017-03-28

    We characterized the electromagnetic field of ultra-short laser pulses after propagation through metallic photonic crystal structures featuring photonic and plasmonic resonances. The complete pulse information, i.e. the envelope and phase of the electromagnetic field, was measured using the technique of cross-correlation frequency resolved optical gating. In good agreement, measurements and scattering matrix simulations show a dispersive behaviour of the spectral phase at the position of the resonances. Asymmetric Fano-type resonances go along with asymmetric phase characteristics. Furthermore, the spectral phase is used to calculate the dispersion of the sample and possible applications in dispersion compensation are investigated. Group refractive indices of 700 and 70 and group delay dispersion values of 90 000 fs(2) and 5000 fs(2) are achieved in transverse electric and transverse magnetic polarization, respectively. The behaviour of extinction and spectral phase can be understood from an intuitive model using the complex transmission amplitude. An associated depiction in the complex plane is a useful approach in this context. This method promises to be valuable also in photonic crystal and filter design, for example, with regards to the symmetrization of the resonances.This article is part of the themed issue 'New horizons for nanophotonics'. © 2017 The Author(s).

  10. Effects of magnetic field on the interaction between terahertz wave and non-uniform plasma slab

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Yuan; Han, YiPing; Guo, LiXin [School of physics and optoelectronic engineering, Xidian University, Xi' an 710071 (China); Ai, Xia [National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical, Beijing 100076 (China)

    2015-10-15

    In this paper, the interaction between terahertz electromagnetic wave and a non-uniform magnetized plasma slab is investigated. Different from most of the published literatures, the plasma employed in this work is inhomogeneous in both collision frequency and electron density. Profiles are introduced to describe the non-uniformity of the plasma slab. At the same time, magnetic field is applied to the background of the plasma slab. It came out with an interesting phenomenon that there would be a valley in the absorption band as the plasma's electromagnetic characteristic is affected by the magnetic field. In addition, the valley located just near the middle of the absorption peak. The cause of the valley's appearance is inferred in this paper. And the influences of the variables, such as magnetic field strength, electron density, and collision frequency, are discussed in detail. The objective of this work is also pointed out, such as the applications in flight communication, stealth, emissivity, plasma diagnose, and other areas of plasma.

  11. Theory of pulsed four-wave mixing in one-dimensional silicon photonic crystal slab waveguides

    Science.gov (United States)

    Lavdas, Spyros; Panoiu, Nicolae C.

    2016-03-01

    We present a comprehensive theoretical analysis and computational study of four-wave mixing (FWM) of optical pulses co-propagating in one-dimensional silicon photonic crystal waveguides (Si-PhCWGs). Our theoretical analysis describes a very general setup of the interacting optical pulses, namely we consider nondegenerate FWM in a configuration in which at each frequency there exists a superposition of guiding modes. We incorporate in our theoretical model all relevant linear optical effects, including waveguide loss, free-carrier (FC) dispersion and FC absorption, nonlinear optical effects such as self- and cross-phase modulation (SPM, XPM), two-photon absorption (TPA), and cross-absorption modulation (XAM), as well as the coupled dynamics of free-carriers FCs and optical field. In particular, our theoretical analysis based on the coupled-mode theory provides rigorously derived formulas for linear dispersion coefficients of the guiding modes, linear coupling coefficients between these modes, as well as the nonlinear waveguide coefficients describing SPM, XPM, TPA, XAM, and FWM. In addition, our theoretical analysis and numerical simulations reveal key differences between the characteristics of FWM in the slow- and fast-light regimes, which could potentially have important implications to the design of ultracompact active photonic devices.

  12. High field rf superconductivity: to pulse or not to pulse

    Energy Technology Data Exchange (ETDEWEB)

    Campisi, I.E.

    1984-10-01

    Experimental data on the behavior of superconductors under the application of rf fields of amplitude comparable to their critical fields are sporadic and not always consistent. In many cases the field level at which breakdown in superconducting rf cavities should be expected has not been clearly established. Tests conducted with very short (approx. 1 ..mu..s) rf pulses indicate that in this mode of operation fields close to the critical values can be consistently reached in superconducting cavities without breakdown. The advantages and disadvantages of the pulsed method are discussed compared to those of the more standard continuous wave (cw) systems. 60 references.

  13. Pulsed electric field inactivation in a microreactor

    NARCIS (Netherlands)

    Fox, M.B.

    2006-01-01

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

  14. Engineering the near-field imaging of a rectangular-lattice photonic-crystal slab in the second band

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Imaging properties of a two-dimensional rectangular-lattice photonic crystal (PC) slab consisting of air holes immersed in a dielectric are studied in this work. The field patterns of electromagnetic waves radiated from a point source through the PC slab are calculated with the finite-difference time-domain method. Comparing the field patterns with the corresponding equifrequency-surface contours simulated by the plane-wave expansion method, we find that an excellent-quality near-field image may be formed through the PC slab by the mechanisms of the simultaneous action of the self-collimation effect and the negative-refraction effect. Near-field imaging may be obtained within two different frequency regions in two vertical directions of the PC slab.

  15. Engineering the near-field imaging of a rectangular-lattice photonic-crystal slab in the second band

    Institute of Scientific and Technical Information of China (English)

    FENG Shuai; AO Ling; WANG YiQuan

    2009-01-01

    Imaging properties of a two-dimensional rectangular-lattice photonic crystal (PC) slab consisting of air holes immersed in a dielectric are studied in this work. The field patterns of electromagnetic waves radiated from a point source through the PC slab are calculated with the finite-difference time-domain method. Comparing the field patterns with the corresponding equifrequency-surface contours simu-lated by the plane-wave expansion method, we find that an excellent-quality near-field image may be formed through the PC slab by the mechanisms of the simultaneous action of the self-collimation effect and the negative-refraction effect. Near-field imaging may be obtained within two different frequency regions in two vertical directions of the PC slab.

  16. Nonstationary Axisymmetric Temperature Field in a Two-Layer Slab Under Mixed Heating Conditions

    Science.gov (United States)

    Turchin, I. N.; Timar, I.; Kolodii, Yu. A.

    2015-09-01

    With the use of the Laguerre and Hankel integral transforms, the solution of a two-dimensional initial-boundary-value heat conduction problem for a two-layer slab under mixed boundary conditions is constructed: one of the surfaces is heated by a heat flux distributed axisymmetrically in a circle of radius R and is cooled by the Newton law outside this circle. The solution of the problem is reduced to a sequence of infinite quasi-regular systems of algebraic equations. The results of numerical analysis of the temperature field in the two-layer slab made from an aluminum alloy and ceramicsare presented depending on the relative geometric properties of the components and cooling intensity.

  17. Angular Spectrum Simulation of Pulsed Ultrasound Fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2009-01-01

    The optimization of non-linear ultrasound imaging should in a first step be based on simulation, as this makes parameter studies considerably easier than making transducer prototypes. Such a simulation program should be capable of simulating non-linear pulsed fields for arbitrary transducer...... geometries for any kind of focusing and apodization. The Angular Spectrum Approach (ASA) is capable of simulating monochromatic non-linear acoustic wave propagation. However, for ultrasound imaging the time response of each specific point in space is required, and a pulsed ASA simulation with multi temporal....... The RMS error of the pulses for all points in the simulated plane is 10.9%. The good agreement between ASA and Field II simulation for the pulsed ultrasound fields obtained in this paper makes it possible to expand Field II to non-linear pulsed fields....

  18. Magnetization reversal in ultrashort magnetic field pulses

    CERN Document Server

    Bauer, M; Fassbender, J; Hillebrands, B

    2000-01-01

    We report the switching properties of a thin magnetic film subject to an ultrashort, laterally localized magnetic field pulse, obtained by numerical investigations. The magnetization distribution in the film is calculated on a grid assuming Stoner-like coherent rotation within the grid square size. Perpendicularly and in-plane magnetized films exhibit a magnetization reversal due to a 4 ps magnetic field pulse. Outside the central region the pulse duration is short compared to the precession period. In this area the evolution of the magnetization during the field pulse does not depend strongly on magnetic damping and/or pulse shape. However, the final magnetization distribution is affected by the magnetic damping. Although the pulse duration is short compared to the precession period, the time needed for the relaxation of the magnetization to the equilibrium state is rather large. The influence of the different magnetic anisotropy contributions and the magnetic damping parameter enters into the magnetization ...

  19. Improving clinical examination in acute tibial fractures by enhancing visual cues: the case for always 'cutting back' a tibial back-slab and marking the dorsalis pedis pulse.

    Science.gov (United States)

    Thomas, Alasdair; Kimber, Cheryl; Bramwell, Donald; Jaarsma, Ruurd

    2016-08-01

    Look, feel, move is a simple and widely taught sequence to be followed when undertaking a clinical examination in orthopaedics (Maher et al., 1994; McRae, 1999; Solomon et al., 2010). The splinting of an acute tibial fracture with a posterior back-slab is also common practice; with the most commonly taught design involving covering the dorsum of the foot with bandaging (Charnley, 1950; Maher et al., 1994; McRae, 1989). We investigated the effect of the visual cues provided by exposing the dorsum of the foot and marking the dorsalis pedis pulse. We used a clinical simulation in which we compared the quality of the recorded clinical examination undertaken by 30 nurses. The nurses were randomly assigned to assess a patient with either a traditional back-slab or one in which the dorsal bandaging had been cut back and the dorsalis pedis pulse marked. We found that the quality of the recorded clinical examination was significantly better in the cut-back group. Previous studies have shown that the cut-back would not alter the effectiveness of the back-slab as a splint (Zagorski et al., 1993). We conclude that all tibial back-slabs should have the bandaging on the dorsum of the foot cut back and the location of the dorsalis pedis pulse marked. This simple adaptation will improve the subsequent clinical examinations undertaken and recorded without reducing the back-slab's effectiveness as a splint.

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

    Science.gov (United States)

    Dunn, J

    1996-09-01

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

  1. Strong and superstrong pulsed magnetic fields generation

    CERN Document Server

    Shneerson, German A; Krivosheev, Sergey I

    2014-01-01

    Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.

  2. Pulsed field gel electrophoresis a practical guide

    CERN Document Server

    Birren, Bruce

    1993-01-01

    Pulsed Field Gel Electrophoresis: A Practical Guide is the first laboratory manual to describe the theory and practice of this technique. Based on the authors' experience developing pulsed field gel instruments and teaching procedures, this book provides everything a researcher or student needs to know in order to understand and carry out pulsed field gel experiments. Clear, well-tested protocols assume only that users have a basic familiarity with molecular biology. Thorough coverage of useful data, theory, and applications ensures that this book is also a lasting resource for more adv

  3. Short pulse diode-pumped Tm:YAG slab laser electro-optically Q-switched by RbTiOPO4 crystal

    Science.gov (United States)

    Jin, Lin; Liu, Pian; Huang, Haitao; Liu, Xuan; Shen, Deyuan

    2016-10-01

    In this paper, a laser diode end pumped RbTiOPO4 (RTP) electro-optically Q-switched Tm:YAG slab laser was demonstrated. Stable Q-switched pulse with the shortest pulse width of 58 ns and an average output power of 7.5 W were realized at the repetition rate of 1 KHz, corresponding to the slope efficiency of 21.7%.

  4. Wuhan pulsed high magnetic field center

    OpenAIRE

    Li, Liang; Peng, Tao; Ding, Honfa; Han, Xiaotao; Ding, Tonghai; Chen, Jin; Wang, Junfeng; Xie, Jianfeng; Wang, Shaoliang; Duan, Xianzhong; Wang, Cheng; Herlach, Fritz; Vanacken, Johan; Pan, Yuan

    2008-01-01

    Wuhan pulsed high magnetic field facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies consists of a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank is under construction. Five magnets wound with CuNb wire and copper wire reinforced internally with Zylon fiber composites and externally with stainless steel shells have be...

  5. Wuhan pulsed high magnetic field center

    OpenAIRE

    Li, Liang; Peng, Tao; Ding, Honfa; Han, Xiaotao; Ding, Tonghai; Chen, Jin; Wang, Junfeng; Xie, Jianfeng; Wang, Shaoliang; DUAN, Xianzhong; Wang, Cheng; Herlach, Fritz; Vanacken, Johan; Pan, Yuan

    2008-01-01

    Wuhan pulsed high magnetic field facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies consists of a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank is under construction. Five magnets wound with CuNb wire and copper wire reinforced internally with Zylon fiber composites and externally with stainless steel shells have be...

  6. Reversed propagation dynamics of vortex field in a left-handed material slab

    CERN Document Server

    Luo, Hailu

    2007-01-01

    On the basis of angular spectrum representation, a formalism describing reversed propagation dynamics of vortex field in an isotropic left-handed material (LHM) slab is presented. Because of the negative refractive index of LHM slab, the reversed Gouy-phase shift and the reversed Rayleigh length in a paraxial Laguerre-Gaussian beam are proposed. The negative phase velocity and reversed Gouy-phase shift caused inverse screw of wave-front, inverse spiral of Poynting vector, and reversed rotation of optical vortex. It is found that the positive mode ($l>0$) Laguerre-Gaussian beam in LHM will present the same fashion of rotation as the negative mode ($l<0$) one in RHM. It is shown that the phase difference caused by the Gouy-phase shift in regular right-handed material (RHM) can be compensated by that caused by the inverse Gouy phase shift in LHM. If certain matching conditions are satisfied, the intensity and phase distributions of the vortex field at object plane can be completely reconstructed at the image ...

  7. Temporal Skewness of Electromagnetic Pulsed Waves Propagating Through Random Media with Embedded Irregularity Slab

    Institute of Scientific and Technical Information of China (English)

    许正文; 吴健; 霍文平; 吴振森

    2003-01-01

    Electromagnetic pulsed waves can be distorted in the propagation through random media, and their energy dis tributions change along the leading and trailing edge of the waveform, which can be presented by the temporal skewness. The skewness presents asymmetry and is treated by the third-order temporal moment, in which an analytic solution for the two-frequency mutual coherence function is obtained recently. Then, transionospheric pulses are discussed in details. Both theoretical analysis and numerical computation indicate that the contri butions from scattering and dispersion of irregularities dominate over those of background, so the latter can be neglected in most cases. Also, the temporal skewness of a transionospheric pulse is negative and energy is shifted to the leading edge.

  8. LASER PERCUSSION DRILLING ON THIN MILD STEEL SHEET BASED ON THE DUTY CYCLE VARIATIONS OF A PULSED RF SLAB CO2 LASER

    OpenAIRE

    R. CORTES; Villagomez, R; Lopez, R.; V. Coello

    2008-01-01

    In this work, the influence of laser pulse trains on thin mild steel sheet blades is investigated. The method is based on varying the duty cycle (DC) of a pulsed RF slab CO2 laser during the process of laser percussion drilling. Here, an experimental methodology to correlate laser parameters and their effects on the characteristics of the melting material ejected was carried out. In the experiments, the interaction time such that of 5%, 10%, and 15% DC were considered for the pulse trains. Re...

  9. Field mapping of ballistic pressure pulse sources

    Directory of Open Access Journals (Sweden)

    Rad Abtin Jamshidi

    2015-09-01

    Full Text Available Ballistic pressure pulse sources are used since late 1990s for the extracorporeal treatment of chronic Enthesitis. Newly indications are found in trigger-point-therapy for the treatment of musculoskeletal disorders. In both applications excellent results without relevant side effects were found in clinical trials. The technical principle of pressure pulse source is based on the same techniques used in air guns. A projectile is accelerated by pressurized air and hits the applicator with high kinetic energy. By this a compression wave travels through the material and induces a fast (4..5μs, almost singular pressure pulse of 2..10 MPa, which is followed by an equally short rarefaction phase of about the same amplitude. It is assumed that the pressure pulse accounts for the biomedical effects of the device. The slower inertial motion of the waveguide is damped by elastic stoppers, but still can be measured several micro seconds after the initial pressure pulse. In order to characterize the pressure pulse devices, field mapping is performed on several radial pressure pulse sources using the fiber optic hydrophone and a polyvinylidenfluorid (PVDF piezoelectric hydrophone. It could be shown that the current standard (IEC 61846 is not appropriate for characterization of ballistic pressure pulse sources.

  10. Magnetic Linear Birefringence Measurements Using Pulsed Fields

    CERN Document Server

    Berceau, Paul; Battesti, Remy; Rizzo, Carlo

    2011-01-01

    In this paper we present the accomplishment of the further step towards the vacuum magnetic birefringence measurement based on pulsed fields. After describing our BMV experiment, we report the calibration of our apparatus with nitrogen gas and we discuss the precision of our measurement giving a detailed error budget. Our best present vacuum sensitivity is 2.1x 10^-19 T^-2 per 5 ms magnetic pulse. We finally discuss the perspectives to reach our final goal.

  11. Large field enhancement obtained by combining Fabry-Perot resonance and Rayleigh anomaly in photonic crystal slabs

    CERN Document Server

    Dossou, Kokou B

    2016-01-01

    By applying the properties of Fabry-Perot resonance and Rayleigh anomaly, we have showed that a photonic crystal slab can scatter the light from an incident plane wave into a diffracted light with a very large reflection or transmission coefficient. The enhanced field is either a propagating diffraction order (with a grazing angle of diffraction) or a weakly evanescent order, so it can be particularly useful for applications requiring an enhanced propagating field (or an enhanced field with a low attenuation). An efficient effective medium technique is developed for the design of the resonant photonic crystal slabs. Numerical simulations have shown that photonic crystal slabs with low index contrast, such as the ones found in the cell wall of diatoms, can enhance the intensity of the incident light by four orders of magnitude.

  12. Optical pulse shaper with integrated slab waveguide for arbitrary waveform generation using optical gradient force

    Science.gov (United States)

    Liao, Sha-Sha; Min, Shu-Cun; Dong, Jian-Ji

    2014-12-01

    Integrated optical pulse shaper opens up possibilities for realizing the ultra high-speed and ultra wide-band linear signal processing with compact size and low power consumption. We propose a silicon monolithic integrated optical pulse shaper using optical gradient force, which is based on the eight-path finite impulse response. A cantilever structure is fabricated in one arm of the Mach—Zehnder interferometer (MZI) to act as an amplitude modulator. The phase shift feature of waveguide is analyzed with the optical pump power, and five typical waveforms are demonstrated with the manipulation of optical force. Unlike other pulse shaper schemes based on thermo—optic effect or electro—optic effect, our scheme is based on a new degree of freedom manipulation, i.e., optical force, so no microelectrodes are required on the silicon chip, which can reduce the complexity of fabrication. Besides, the chip structure is suitable for commercial silicon on an insulator (SOI) wafer, which has a top silicon layer of about 220 nm in thickness.

  13. Schwinger Pair Production in Pulsed Electric Fields

    CERN Document Server

    Kim, Sang Pyo; Ruffini, Remo

    2012-01-01

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

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

    Science.gov (United States)

    1976-10-01

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

  15. Control of transmission of right circularly polarized laser light in overdense plasma by applied magnetic field pulses.

    Science.gov (United States)

    Ma, Guangjin; Yu, Wei; Yu, M Y; Luan, Shixia; Wu, Dong

    2016-05-01

    The effect of a transient magnetic field on right-hand circularly polarized (RHCP) laser light propagation in overcritical-density plasma is investigated. When the electron gyrofrequency is larger than the wave frequency, RHCP light can propagate along the external magnetic field in an overcritical density plasma without resonance or cutoff. However, when the magnetic field falls to below the cyclotron resonance point, the propagating laser pulse will be truncated and the local plasma electrons resonantly heated. Particle-in-cell simulation shows that when applied to a thin slab, the process can produce intense two-cycle light pulses as well as long-lasting self-magnetic fields.

  16. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M., E-mail: marco.caresana@polimi.it [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Denker, A. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Esposito, A. [IFNF-LNF, FISMEL, via E. Fermi 40, 00044 Frascati (Italy); Ferrarini, M. [CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Golnik, N. [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland); Hohmann, E. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Leuschner, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Luszik-Bhadra, M. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Manessi, G. [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Mayer, S. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Ott, K. [Helmholtz-Zentrum Berlin, BESSYII, Albert-Einstein-Str.15, 12489 Berlin (Germany); Röhrich, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Trompier, F. [Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay aux Roses (France); Volnhals, M.; Wielunski, M. [Helmholtz Zentrum München, Ingolstädter Landstr. 1, D-85764 Neuherberg (Germany)

    2014-02-11

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  17. Pulsed Electric Field treatment of packaged food

    NARCIS (Netherlands)

    Roodenburg, B.

    2011-01-01

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

  18. Near-field imaging of a square-lattice metallic photonic-crystal slab at the second band

    Institute of Scientific and Technical Information of China (English)

    Feng Shuai; Feng Zhi-Fang; Ren Kun; Ren Cheng; Li Zhi-Yuan; Cheng Bing-Ying; Zhang Dao-Zhong

    2006-01-01

    Imaging properties of a two-dimensional photonic crystal slab lens are investigated through the finite-difference time-domain method. In this paper, we consider the photonic crystal slab consisting of a square lattice of square metallic rods immersed in a dielectric background. Through the analysis of the equifrequency-surface contours and the field patterns of a point source placed in the vicinity of the photonic crystal slab, we find that a good-quality image can form at the frequencies in the second TM-polarized photonic band. Comparing the images formed at different frequencies, we can clearly see that an excellent-quality image is formed by the mechanisms of simultaneous action of the self-collimation effect and the negative-refraction effect.

  19. Numerical simulation of flow and heat transfer of continous cast steel slab under traveling magnetic field

    Directory of Open Access Journals (Sweden)

    Gong Haijun

    2013-03-01

    Full Text Available A unified numerical model for simulating solidification transport phenomena (STP of steel slab in electromagnetic continuous casting (EMCC process was developed. In order to solve the multi-physics fields coupled problem conveniently, the complicated bidirectional coupled process between EM and STP was simplified as a unidirectional one, and a FEM/FVM-combined numerical simulation technique was adopted. The traveling magnetic fields (TMFs applied to the EMCC process were calculated using the ANSYS11.0 software, and then the EM-data output by ANSYS were converted to FVM-format using a data-format conversion program developed previously. Thereafter, the governing equations were solved using a pressure-based Direct-SIMPLE algorithm. The simulation results of the STP in CC-process show that, due to the influences of Lorentz force and Joule heat, the two strong circulating flows and the temperature field can be obviously damped and changed once TMF with one pair of poles (1-POPs or 2-POPs is applied, which would accordingly improve the quality of casting. It was found in the present research that the integrated actions of 2-POPs TMF are superior to 1-POPs. All the computations indicate that the present numerical model of EM-STP as well as the FEM/FVM-combined technique is successful.

  20. Biofouling prevention with pulsed electric fields

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-02-01

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

  1. Tunable Lamb wave band gaps in two-dimensional magnetoelastic phononic crystal slabs by an applied external magnetostatic field.

    Science.gov (United States)

    Zhou, Changjiang; Sai, Yi; Chen, Jiujiu

    2016-09-01

    This paper theoretically investigates the band gaps of Lamb mode waves in two-dimensional magnetoelastic phononic crystal slabs by an applied external magnetostatic field. With the assumption of uniformly oriented magnetization, an equivalent piezomagnetic material model is used. The effects of magnetostatic field on phononic crystals are considered carefully in this model. The numerical results indicate that the width of the first band gap is significantly changed by applying the external magnetic field with different amplitude, and the ratio between the maximum and minimum gap widths reaches 228%. Further calculations demonstrate that the orientation of the magnetic field obviously affects the width and location of the first band gap. The contactless tunability of the proposed phononic crystal slabs shows many potential applications of vibration isolation in engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. High Field Pulse Magnets with New Materials

    Science.gov (United States)

    Li, L.; Lesch, B.; Cochran, V. G.; Eyssa, Y.; Tozer, S.; Mielke, C. H.; Rickel, D.; van Sciver, S. W.; Schneider-Muntau, H. J.

    2004-11-01

    High performance pulse magnets using the combination of CuNb conductor and Zylon fiber composite reinforcement with bore sizes of 24, 15 and 10 mm have been designed, manufactured and tested to destruction. The magnets successfully reached the peak fields of 64, 70 and 77.8 T respectively with no destruction. Failures occurred near the end flanges at the layer. The magnet design, manufacturing and testing, and the mode of the failure are described and analyzed.

  3. Pulsed photoelectric field emission from needle cathodes

    CERN Document Server

    Hernandez-Garcia, C

    2002-01-01

    Experiments have been carried out to measure the current emitted by tungsten needles with 1-mu m tip radius operated up to 50 kV. This corresponds to electric fields in the order of 10 sup 9 to 10 sup 1 sup 0 V/m. The needles were illuminated with 10-ns laser pulses at 532, 355 and 266 nm. The laser intensity was varied from 10 sup 1 sup 0 to 10 sup 1 sup 2 W/m sup 2 , limited by damage to the needle tip. The observed quantum efficiency depends on the wavelength and the electric field, approaching unity at the highest electric fields when illuminated at 266 nm. Peak currents up to 100 mA were observed in nanosecond pulses, corresponding to an estimated brightness of 10 sup 1 sup 6 A/m sup 2 sr. Since the current is controlled by the laser intensity, with only a weak voltage dependence, these cathodes can be used for infrared and ultraviolet tabletop free-electron lasers and other applications that demand short electron-beam pulses with high brightness.

  4. Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

    DEFF Research Database (Denmark)

    Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.

    2015-01-01

    An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration.......An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....

  5. The Pali Aike Volcanic Field, Patagonia: slab-window magmatism near the tip of South America

    Science.gov (United States)

    D'Orazio, Massimo; Agostini, Samuele; Mazzarini, Francesco; Innocenti, Fabrizio; Manetti, Piero; Haller, Miguel J.; Lahsen, Alfredo

    2000-06-01

    The Pali Aike Volcanic Field (PAVF) represents the southernmost occurrence of the Cenozoic back-arc Patagonian Plateau Lavas. Its activity (Pliocene-Recent) started forming tabular lavas followed by the growth of about 470 essentially monogenetic volcanic centers (tuff-rings, maars, spatter and scoria cones). Azimuths of cone alignment, cone elongation and morphologic lineations show prevailing ENE-WSW and NW-SE trends. Erupted products consist mainly of alkaline basalt and basanite, with minor olivine basalt. PAVF rocks are quite primitive in composition (average Mg#=66, Ni=220 ppm and Cr=313 ppm) with relatively high TiO 2 (average 3.0 wt.%). Ultramafic garnet- and/or spinel-bearing xenoliths are found within PAVF volcanics. Chondrite-normalized REE patterns are significantly LREE-enriched and almost rectilinear [(La/Yb) N=10.9-21.0]. Primordial mantle-normalized distributions of incompatible trace elements, as well as Sr and Nd isotope ratios ( 87Sr/ 86Sr=0.70317-0.70339, 143Nd/ 144Nd=0.51290-0.51294), show values typical of intra-plate basalts, despite the fact that these rocks occur only 200 km east of the Andean Cordillera. Primary magmas were generated from a fertile garnet-bearing asthenospheric source at P=1.9-2.9 GPa and T=1420-1470°C. The data suggest a geodynamic model that implies sub-slab asthenosphere flow through a slab window, which started opening below this sector of South America 14 m.y. ago as a consequence of the collision of the Chile Ridge with the Chile Trench. The trailing edge of the Nazca Plate crossed below the Pali Aike area at 9-10 Ma, that is 6-5 m.y. before the onset of the volcanic activity. We hypothesize that this time delay resulted from changes in the kinematics of the South America-Scotia transform plate boundary which only allowed the Pali Aike magmas to rise after about 4 m.y.

  6. Full-field dye concentration measurement within saturated/unsaturated thin slabs of porous media

    Energy Technology Data Exchange (ETDEWEB)

    Norton, D.L. [Arizona Univ., Tucson, AZ (United States). Dept. of Hydrology; Glass, R.J. [Sandia National Labs., Albuquerque, NM (United States)

    1992-12-31

    This paper presents a full-field dye concentration measurement technique that extends our experimental capabilities to the measurement of transient dye concentration fields within steady state flow fields under unsaturated or saturated conditions. Simple light absorption theory provides a basis for translating images into high resolution dye concentration fields. A series of dye pulse experiments that demonstrate the combined use of the full-field saturation and dye concentration techniques was conducted at four different degrees of saturation. Each of these experimental sequences was evaluated with respect to mass balance, the results being within 5% of the known dye mass input. An image windowing technique allowed us to see increased dispersion due to decreasing moisture content, tailing of concentration at the rear of the dye pulse and slight velocity changes of the dispersive front due to changes in moisture content. The exceptional resolution of dye concentration in space and time provided by this laboratory technique allows systematic experimentation for examining basic processes affecting solute transport within saturated/unsaturated porous media. Future challenges for this work will be to use these techniques to analyze more complex systems involving heterogeneities, scaling laws, and detailed investigations of the relationship between transverse and longitudinal dispersion in unsaturated media.

  7. Pulsed-field magnetometry for rock magnetism

    Science.gov (United States)

    Kodama, Kazuto

    2015-07-01

    An improved method is proposed for measuring dynamic magnetizations of bulk volcanic rock samples induced by a pulsed-field of 0.7 T and a duration of 10 ms. The transient magnetization is measured by a sensing system that consists of a pair of inductive differential coils, an analog preamplifier and integrator, and a high-speed digital storage scope. The system was calibrated using a paramagnetic salt (Gd2O3) and was tested to different kinds of volcanic rocks with their magnetic properties well-documented previously. The results were comparable with those measured by a quasi-static method using a vibrating sample magnetometer, although there were small discrepancies in hysteresis parameters suggesting the time-dependence of the magnetic properties. The proposed system provides not only the magnetization over the short interval of a pulse but also the rapid (~3 ms) exponential decay after a pulse. The decay time constant was different among the samples under study, indicating the variations of their magnetic relaxation time. Although the present system is not sensitive enough to characterize varieties of natural samples including sediments, it has the potential as a versatile and convenient tool for rock magnetism.

  8. Optical bistability and multistability driven by external magnetic field in a dielectric slab doped with nanodiamond nitrogen vacancy centres

    Science.gov (United States)

    Nasehi, R.; Norouzi, F.

    2016-08-01

    The theoretical investigation of controlling the optical bistability (OB) and optical multistability (OM) in a dielectric medium doped with nanodiamond nitrogen vacancy centres under optical excitation are reported. The shape of the OB curve from dielectric slab can be tuned by changing the external magnetic field and polarization of the control beam. The effect of the intensity of the control laser field and the frequency detuning of probe laser field on the OB and OM behaviour are also discussed in this paper. The results obtained can be used for realizing an all-optical bistable switching or development of nanoelectronic devices.

  9. A Bonner Sphere Spectrometer for pulsed fields.

    Science.gov (United States)

    Aza, E; Dinar, N; Manessi, G P; Silari, M

    2016-02-01

    The use of conventional Bonner Sphere Spectrometers (BSS) in pulsed neutron fields (PNF) is limited by the fact that proportional counters, usually employed as the thermal neutron detectors, suffer from dead time losses and show severe underestimation of the neutron interaction rate, which leads to strong distortion of the calculated spectrum. In order to avoid these limitations, an innovative BSS, called BSS-LUPIN, has been developed for measuring in PNF. This paper describes the physical characteristics of the device and its working principle, together with the results of Monte Carlo simulations of its response matrix. The BSS-LUPIN has been tested in the stray neutron field at the CERN Proton Synchrotron, by comparing the spectra obtained with the new device, the conventional CERN BSS and via Monte Carlo simulations.

  10. Pulsed electric field assisted assembly of polyaniline

    Science.gov (United States)

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

    2012-08-01

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

  11. Dynamic pulsed-field-gradient NMR

    CERN Document Server

    Sørland, Geir Humborstad

    2014-01-01

    Dealing with the basics, theory and applications of dynamic pulsed-field-gradient NMR NMR (PFG NMR), this book describes the essential theory behind diffusion in heterogeneous media that can be combined with NMR measurements to extract important information of the system being investigated. This information could be the surface to volume ratio, droplet size distribution in emulsions, brine profiles, fat content in food stuff, permeability/connectivity in porous materials and medical applications currently being developed. Besides theory and applications it will provide the readers with background knowledge on the experimental set-ups, and most important, deal with the pitfalls that are numerously present in work with PFG-NMR. How to analyze the NMR data and some important basic knowledge on the hardware will be explained, too.

  12. Deficiencies of active electronic radiation protection dosimeters in pulsed fields.

    Science.gov (United States)

    Ankerhold, U; Hupe, O; Ambrosi, P

    2009-07-01

    Nowadays nearly all radiation fields used for X-ray diagnostics are pulsed. These fields are characterised by a high dose rate during the pulse and a short pulse duration in the range of a few milliseconds. The use of active electronic dosimeters has increased in the past few years, but these types of dosimeters might possibly not measure reliably in pulsed radiation fields. Not only personal dosimeters but also area dosimeters that are used mainly for dose rate measurements are concerned. These cannot be substituted by using passive dosimeter types. The characteristics of active electronic dosimeters determined in a continuous radiation field cannot be transferred to those in pulsed fields. Some provisional measurements with typical electronic dosimeters in pulsed radiation fields are presented to reveal this basic problem.

  13. Influence of cladding layer field of slab waveguide on M2 factor

    Institute of Scientific and Technical Information of China (English)

    Bin Lin(林斌); Xuejin Wen(文学金); Fuyuan Guo(郭福源)

    2003-01-01

    Based on the theory of semiconductor laser pattern and the non-paraxial vectorial moment theory of lightbeam propagation, the beam quality factor M2 of TE0 propagating mode is analyzed and calculated.The result shows that when both core layer and cladding layer are considered, M2 > 1 is always obtained.Moreover, by analyzing the characteristic of real beams, this result is generalized to the multilayer isotropiclinear slab waveguides.

  14. Frequency-selective near-field radiative heat transfer between photonic crystal slabs: a computational approach for arbitrary geometries and materials.

    Science.gov (United States)

    Rodriguez, Alejandro W; Ilic, Ognjen; Bermel, Peter; Celanovic, Ivan; Joannopoulos, John D; Soljačić, Marin; Johnson, Steven G

    2011-09-09

    We demonstrate the possibility of achieving enhanced frequency-selective near-field radiative heat transfer between patterned (photonic-crystal) slabs at designable frequencies and separations, exploiting a general numerical approach for computing heat transfer in arbitrary geometries and materials based on the finite-difference time-domain method. Our simulations reveal a tradeoff between selectivity and near-field enhancement as the slab-slab separation decreases, with the patterned heat transfer eventually reducing to the unpatterned result multiplied by a fill factor (described by a standard proximity approximation). We also find that heat transfer can be further enhanced at selective frequencies when the slabs are brought into a glide-symmetric configuration, a consequence of the degeneracies associated with the nonsymmorphic symmetry group.

  15. 平板中的Lamb波波场研究%Study on Lamb wave field in the slab

    Institute of Scientific and Technical Information of China (English)

    李梦雅; 张成伟

    2015-01-01

    The paper studied the Lamb wave field in the slab,analyzed fd number,correlation between the phase and body wave velosities when the normal displacement of the free surface particle is zero in different model.%对平板中的Lamb波波场进行了研究,着重分析了不同模式下,使得板自由面质点法向位移为零时fd(f为频率, d板厚度)的大小及兰姆波相速度与体波速度之间的关系.

  16. Bag model for DNA migration during pulsed-field electrophoresis.

    OpenAIRE

    Chu, G

    1991-01-01

    A model for pulsed-field electrophoresis was developed by picturing large DNA as a deformable "bag" that (i) moves with limiting mobility in a continuous electric field, (ii) adopts an orientation aligned with the field direction, and (iii) reorients after a change in field direction in a size-dependent manner. The model correctly predicted the resolution of large DNA in a pulsed field including the surprising phenomena of mobility inversion, lateral band spreading, and improved resolution fo...

  17. Weibel instability in the field of a short laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2013-03-15

    The growth rate of Weibel instability in a plasma interacting with a high-frequency pulse with a duration less or comparable with the electron mean free time is determined. The growth rate is shown to decrease with decreasing pulse duration. It is found that instability can develop after the short pulse is switched off and the generated magnetic field no longer affects electron motion in the high-frequency field.

  18. Field Theory for Coherent Optical Pulse Propagation

    CERN Document Server

    Park, Q H

    1997-01-01

    We introduce a new notion of "matrix potential" to nonlinear optical systems. In terms of a matrix potential $g$, we present a gauge field theoretic formulation of the Maxwell-Bloch equation that provides a semiclassical description of the propagation of optical pulses through resonant multi-level media. We show that the Bloch part of the equation can solved identically through $g$ and the remaining Maxwell equation becomes a second order differential equation with reduced set of variables due to the gauge invariance of the system. Our formulation clarifies the (nonabelian) symmetry structure of the Maxwell-Bloch equations for various multi-level media in association with symmetric spaces $G/H$. In particular, we associate nondegenerate two-level system for self-induced transparency with $G/H=SU(2)/U(1)$ and three-level $\\L $- or V-systems with $G/H = SU(3)/U(2)$. We give a detailed analysis for the two-level case in the matrix potential formalism, and address various new properties of the system including so...

  19. The effect of pulsed electric fields on carotenoids bioaccessibility

    NARCIS (Netherlands)

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

    2018-01-01

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

  20. Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

    Science.gov (United States)

    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.

  1. Strong-field short-pulse nondipole dynamics

    DEFF Research Database (Denmark)

    Dimitrovski, Darko; Førre, Morten; Madsen, Lars Bojer

    2009-01-01

    We present a quantitative investigation of strong-field short-pulse nondipole dynamics in laser-matter interactions. We find excellent agreement between ab initio numerical and analytic results obtained using the Magnus expansion. We show that in the short-pulse limit, ultrafast transfer and cont......We present a quantitative investigation of strong-field short-pulse nondipole dynamics in laser-matter interactions. We find excellent agreement between ab initio numerical and analytic results obtained using the Magnus expansion. We show that in the short-pulse limit, ultrafast transfer...

  2. Isolated Attosecond Pulses using a Detuned Second-harmonic Field

    Energy Technology Data Exchange (ETDEWEB)

    Merdji, Hamed; /Saclay /SLAC, PULSE; Auguste, Thierry; Boutu, Willem; Caumes, J.-Pascal; Carre, Bertrand; /Saclay; Pfeifer, Thomas; Jullien, Aurelie; Neumark, Daniel M.; Leone, Stephen R.; /UC, Berkeley /LBL, Berkeley

    2007-11-07

    Calculations are presented for the generation of an isolated attosecond pulse in a multicycle two-color strong-field regime. We show that the recollision of the electron wave packet can be confined to half an optical cycle using pulses of up to 40 fs in duration. The scheme is proven to be efficient using two intense beams, one producing a strong field at {omega} and the other a strong field detuned from 2{omega}. The slight detuning {delta}{omega} of the second harmonic is used to break the symmetry of the electric field over many optical cycles and provides a coherent control for the formation of an isolated attosecond pulse.

  3. Design of Pulsed Strong Magnetic Fields Generator and Preliminary Application

    Institute of Scientific and Technical Information of China (English)

    WEN Jun; QU Xue-min; WANG Xi-gang; LONG Kai-ping

    2015-01-01

    Objective: This paper aims to designing a pulsed strong magnetic fields generator. Methods: A large value capacitor was used to store electric energy, coil was used for producing magnetic fields, main control, circuit control charge, sampling, discharge, etc. Results: The generator provided a pulsed magnetic field with the ampli-tude of intensity from 0.1-2 T and variable time interval of pulse from 4 s-1 min. It was not only to be operated easily but also performed reliably. Conclusion:The generator will be applied in special clinical diagnosis, therapy and other fields.

  4. Out-of-plane resonances in terahertz photonic crystal slabs modulated by optical pumping.

    Science.gov (United States)

    Shi, Yulei; Zhou, Qing-Li; Liu, Wei; Zhang, Cunlin

    2011-10-10

    This paper describes detailed optical-pump-terahertz-probe studies of two-dimensional photonic crystal slabs for propagation perpendicular to the slabs. When the slabs are excited by an 800 nm pump pulse and the effect of shielding by photocarriers is removed, we find that the decaying tail in the transmitted terahertz radiation is strikingly enhanced. The photocarriers weaken guided resonances, but they also greatly enhance the excitation efficiency of guided resonances and the ability of the guided resonances to transfer energy back to the radiation field. This increases the resonance-assisted contribution to transmitted field. The photoinduced resonant extremes agree well with the Fano model.

  5. A 46-W Laser Diode Stack End-Pumped Slab Amplifier with a Pulse Duration of Picoseconds

    Institute of Scientific and Technical Information of China (English)

    YAN Ying; FAN Zhong-Wei; NIU Gang; YU Jin; ZHANG Heng-Li

    2012-01-01

    A 46-W laser diode end-pumped amplifier is demonstrated by using a SESAM passively mode-locked oscillator and a compact LD stack end-pumped slab amplifier.For the oscillator,a 5-W picosecond mode-locked laser with a repetition frequency of 79MHz is obtained with beam quality factors of M2 < 1.3.A beam shaping system made up of cylindrical lens is designed according to different sizes of the active medium in both directions,and a plane-plane cavity is used in the amplifier for high efficiency.At the absorbed pumping power of 174 W,the highest output power of 46 W is obtained with the slope efficiency of 29.5%.The beam quality factors M2 in both directions are measured to be 1.43 and 1.76,respectively.

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

    Science.gov (United States)

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

    2015-11-01

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

  7. Pulse-train control of photofragmentation at constant field energy

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Henriksen, Niels Engholm

    2014-01-01

    We consider a phaselocked two-pulse sequence applied to photofragmentation in the weak-field limit. The two pulses are not overlapping in time, i.e., the energy of the pulse-train is constant for all time delays. It is shown that the relative yield of excited Br* in the nonadiabatic process: I + Br......*←IBr → I + Br, changes as a function of time delay when the two excited wave packets interfere. The underlying mechanisms are analyzed and the change in the branching ratio as a function of time delay is only a reflection of a changing frequency distribution of the pulse train; the branching ratio does...

  8. Negative Refraction and Near-Field Imaging of an Elliptical-Rod Photonic Crystal Slab in the Second Band

    Institute of Scientific and Technical Information of China (English)

    FENG Shuai; AO Ling; WANG Yi-Quan; LI Zhi-Yuan; ZHANG Dao-Zhong

    2007-01-01

    Negative refraction and imaging properties of the electromagnetic wave through a two-dimensional photonic crystal (PC) slab, which consists of a square lattice of elliptical dielectric rods immersed in the air background,is studied by the plane-wave expansion method and the finite-difference time-domain method. A point source placed in the vicinity of the PC slab can form a good-quality image spot through the PC slab for the incident frequencies within the second photonic band. The calculated result also shows that negative refraction occurs in this kind of PC slab.

  9. Pulsed field gel electrophoresis on frozen tumour tissue sections.

    OpenAIRE

    Boultwood, J; Kaklamanis, L.; Gatter, K C; Wainscoat, J S

    1992-01-01

    The application of pulsed field gel electrophoresis (PFGE) to the molecular genetic analysis of solid tumours has been restricted by the requirement for whole single cells as a DNA source. A simple technique which allows for the direct analysis of histologically characterised solid tumour material by pulsed field gel electrophoresis was developed. Single frozen tissue sections obtained from colonic carcinoma specimens were embedded without further manipulation in molten, low melting temperatu...

  10. Successful suppression of magnetization precession after short field pulses

    OpenAIRE

    Bauer, Martin; Lopusnik, Radek; Fassbender, Jürgen; Hillebrands, Burkard; Dötsch, H.

    2000-01-01

    For the next generation of high data rate magnetic recording above 1 Gbit/s, a better understanding of the switching processes for both recording heads and media will be required. In order to maximize the switch-ing speed for such devices, the magnetization precession after the magnetic field pulse termination needs to be suppressed to a maximum degree. It is demonstrated experimentally for ferrite films that the appropriate adjustment of the field pulse parameters and/or the static applied f...

  11. Quantification of Vapor Intrusion Pathways into a Slab-on-Ground Building: an Integration of Mathematical Modeling and Field Experiments

    Science.gov (United States)

    Li, Y.; Akbariyeh, S.; Patterson, B.

    2014-12-01

    Vapor intrusion of volatile organic compounds into buildings can be a significant source of human exposure to hazardous materials. Field assessment is essential to evaluate the vapor intrusion pathways, which has been recognized to be challenging due to the heterogeneity of sites and uncontrolled site environments. Modeling of vapor intrusion processes can predict subsurface vapor and oxygen concentrations and indoor air concentration under various environmental site conditions. However, detailed experimental quantification for model validation is typically unavailable. In this work, we report our efforts to quantifying vapor intrusion pathways into a slab-on-ground building by integrating mathematical modeling with well-controlled field measurements under three different pressure and ventilation site conditions. Comparisons between modeling and field measurements include indoor air concentration, contaminant and oxygen distribution profile beneath and inside the building, diffusive and advective flux under different pressure and air vitalization conditions. In addition to typically identified key factors influencing vapor intrusion (e.g. the building construction, the properties of compounds, and depth to the source), we found several additional parameters, such as anisotropic property of surface soil, locations of crack, and dependency of reaction rates on oxygen concentration, are critical to evaluate vapor intrusion pathways.

  12. Development of advanced radiation monitors for pulsed neutron fields

    CERN Document Server

    AUTHOR|(CDS)2081895

    The need of radiation detectors capable of efficiently measuring in pulsed neutron fields is attracting widespread interest since the 60s. The efforts of the scientific community substantially increased in the last decade due to the increasing number of applications in which this radiation field is encountered. This is a major issue especially at particle accelerator facilities, where pulsed neutron fields are present because of beam losses at targets, collimators and beam dumps, and where the correct assessment of the intensity of the neutron fields is fundamental for radiation protection monitoring. LUPIN is a neutron detector that combines an innovative acquisition electronics based on logarithmic amplification of the collected current signal and a special technique used to derive the total number of detected neutron interactions, which has been specifically conceived to work in pulsed neutron fields. Due to its special working principle, it is capable of overcoming the typical saturation issues encountere...

  13. Pulse transient hot strip technique adapted for slab sample geometry to study anisotropic thermal transport properties of μm-thin crystalline films.

    Science.gov (United States)

    Ma, Y; Gustavsson, J S; Haglund, A; Gustavsson, M; Gustafsson, S E

    2014-04-01

    A new method based on the adaptation of the Pulse Transient Hot Strip technique to slab sample geometry has been developed for studying thermal conductivity and thermal diffusivity of anisotropic thin film materials (conductivity in the 0.01-100 W/mK range, deposited on thin substrates (i.e., wafers). Strength of this technique is that it provides a well-controlled thermal probing depth, making it possible to probe a predetermined depth of the sample layer and thereby avoiding the influence from material(s) deeper down in the sample. To verify the technique a series of measurements were conducted on a y-cut single crystal quartz wafer. A Hot Strip sensor (32-μm wide, 3.2-mm long) was deposited along two orthogonal crystallographic (x- and z-) directions and two independent pulse transients were recorded. Thereafter, the data was fitted to our theoretical model, and the anisotropic thermal transport properties were determined. Using a thermal probing depth of only 30 μm, we obtained a thermal conductivity along the perpendicular (parallel) direction to the z-, i.e., optic axis of 6.48 (11.4) W/mK, and a thermal diffusivity of 3.62 (6.52) mm(2)/s. This yields a volumetric specific heat of 1.79 MJ/mK. These values agree well with tabulated data on bulk crystalline quartz supporting the accuracy of the technique, and the obtained standard deviation of less than 2.7% demonstrates the precision of this new measurement technique.

  14. Numeric modeling of synchronous laser pulsing and voltage pulsing field evaporation

    CERN Document Server

    Zhao, L; Houard, J; Blum, I; Delaroche, F; Vurpillot, F

    2016-01-01

    We have recently proposed an atom probe design based on a femtosecond time-resolved pump-probe setup. This setup unlocks the limitation of voltage pulsed mode atom probe thanks to the occurrence of local photoconductive switching effect . In this paper, we have used a numerical model to simulate the field evaporation process triggered by the synchronous two pulses. The model takes into account the local photoconductive effect and the temperature rise caused by the laser application and the voltage pulse distortion due to the RC effect.

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

    OpenAIRE

    Stellwagen, J; Stellwagen, N C

    1989-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

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

  17. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    Science.gov (United States)

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

    2015-05-01

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

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

    Science.gov (United States)

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

    2008-05-01

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

  19. Production of pulsed electric fields using capacitively coupled electrodes

    Science.gov (United States)

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

    1980-01-01

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

  20. Microscopic Faraday rotation measurement system using pulsed magnetic fields.

    Science.gov (United States)

    Egami, Shigeki; Watarai, Hitoshi

    2009-09-01

    Microscopic Faraday rotation measurement system using a pulsed magnetic field has been constructed, which can be applied to micron sized diamagnetic and paramagnetic materials. A pulsed magnetic coil could generate a maximum magnetic flux density of about 12 T. The performance of the microscopic Faraday rotation apparatus was demonstrated by the measurement of the Verdet constant V of a polystyrene particle, after the calibration of the pulsed magnetic flux density using a glass plate as a standard material. Also, the magneto-optical rotation dispersion of some diamagnetic substances have been measured and analyzed with V=alambda(-2)+b. The values of a and b were compared to their magnetic susceptibilities.

  1. Ho:YLF & Ho:LuLF slab amplifier system delivering 200 mJ, 2 µm single-frequency pulses

    CSIR Research Space (South Africa)

    Strauss, HJ

    2011-07-01

    Full Text Available A single-frequency single-pass amplifier based on Ho:YLF and Ho:LuLF in a scalable slab architecture delivering up to 210 mJ at 2064 nm is demonstrated. The amplifier was end-pumped by a 1890 nm Tm:YLF slab laser and was seeded with a 69 mJ single...

  2. Investigation of an angular spectrum approach for pulsed ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2013-01-01

    sources are compared to the Field II simulated and hydroph one measure dpulses, respectively. The total relative root mean squar e(RMS)errors of the pulsed ASA are investigated by using different time-point, zero-padding factors, spatial sampling interval and temporal sampling frequency in the sim ulation....... Optim al parameters for the ASA are found in the simulation .The RMS error of the ASA simulation is reduced from 10.9% to 2.4% for the optimal parameters when comparing to Field II simulation s. The comparison between the ASA calculated and measured pulses are illustrated and the corresponding RMS error......An Angular Spectrum Approach (ASA)is formulated and employed to simulate linear pulsed ultra sound fields for high bandwidth signals. Ageometrically focused piston transducer is used as the acoustic source. Signals are cross-correlated to findthe true sound speed during the measurement to make...

  3. Penetration dynamics of a magnetic field pulse into high-? superconductors

    Science.gov (United States)

    Meerovich, V.; Sinder, M.; Sokolovsky, V.; Goren, S.; Jung, G.; Shter, G. E.; Grader, G. S.

    1996-12-01

    The penetration of a magnetic field pulse into a high-0953-2048/9/12/004/img9 superconducting plate is investigated experimentally and theoretically. It follows from our experiments that the threshold of penetration increases with increasing amplitude and/or decreasing duration of the applied pulse. The penetrating field continues to grow as the applied magnetic field decreases. The peculiarities observed are explained in the framework of the extended critical state model. It appears that the deviations from Bean's classical critical state model are characterized by a parameter equal to the square of the ratio of plate thickness to skin depth. The applicability of the classical critical state model is restricted by the condition that this parameter is much less than 1. This condition is also the criterion for the applicability of pulse methods of critical current measurements.

  4. Heat pulse propagation in chaotic 3-dimensional magnetic fields

    CERN Document Server

    del-Castillo-Negrete, D

    2014-01-01

    Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The role of reversed shear configurations on pulse propagation. In all the cases considered there are no magnetic flux surfaces. However, radial transport is observed to depend strongly on $\\epsilon$ due to the presence of high-order magnetic islands and Cantori that act as quasi-transport barriers that preclude the radial penetration of heat pulses within physically relevant time scale. The dependence of the magnetic field connection length, $\\ell_B$, on $\\epsilon$ is studied in detail. The decay rate of the temperature maximum...

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

    Science.gov (United States)

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

    2010-09-01

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

  6. Two-photon Compton process in pulsed intense laser fields

    CERN Document Server

    Seipt, D

    2012-01-01

    Based on strong-field QED in the Furry picture we use the Dirac-Volkov propagator to derive a compact expression for the differential emission probability of the two-photon Compton process in a pulsed intense laser field. The relation of real and virtual intermediate states is discussed, and the natural regularization of the on-shell contributions due to the finite laser pulse is highlighted. The inclusive two-photon spectrum is two orders of magnitude stronger than expected from a perturbative estimate.

  7. Dielectric Fluid in Inhomogeneous Pulsed Electric Field

    CERN Document Server

    Shneider, M N

    2013-01-01

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

  8. Prediction of the spatial occurrence of fire induced spalling in concrete slabs using random fields

    Directory of Open Access Journals (Sweden)

    Van Coile R.

    2013-09-01

    Full Text Available As the loss of concrete cover can significantly influence the reliability of concrete elements during fire, spalling should be taken into account when performing reliability calculations. However, the occurrence and spatial variation of spalling are highly uncertain. A first step towards a probabilistic analysis of spalling is made by combining existing deterministic models with a stochastic representation of the concrete tensile strength and by using random fields to model the tensile strength spatial variation.

  9. Nanosecond pulsed electric field ablation of hepatocellular carcinoma.

    Science.gov (United States)

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

    2011-01-01

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

  10. Electronic structure and its external electric field modulation of PbPdO2 ultrathin slabs with (002) and (211) preferred orientations.

    Science.gov (United States)

    Yang, Yanmin; Zhong, Kehua; Xu, Guigui; Zhang, Jian-Min; Huang, Zhigao

    2017-07-31

    The Electronic structure of PbPdO2 with (002) and (211) preferred orientations were investigated using first-principles calculation. The calculated results indicate that, (002) and (211) orientations exhibit different electric field dependence of band-gap and carrier concentration. The small band gap and more sensitive electric field modulation of band gap were found in (002) orientation. Moreover, the electric field modulation of the resistivity up to 3-4 orders of magnitude is also observed in (002) slab, which reveals that origin of colossal electroresistance. Lastly, electric field modulation of band gap is well explained. This work should be significant for repeating the colossal electroresistance.

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

    Directory of Open Access Journals (Sweden)

    Ozturk Burcu

    2017-01-01

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

  12. Prediction of electric field frequency correlations for randomly scattering slabs in the nondiffusive regime with the scalar Bethe-Salpeter equation.

    Science.gov (United States)

    Gaind, Vaibhav; San, Aung K; Lin, Dergan; Webb, Kevin J

    2014-01-01

    We show that a scalar Bethe-Salpeter equation model captures the measured copolarized electric field frequency correlation magnitude for randomly scattering slabs in the weakly scattering, nondiffusive regime. Consequently, the model could be used to form images of tissue on the millimeter and submillimeter length scale, and for environmental sensing with comparable scatter, as dictated by the optical scattering length in relation to the scattering domain size.

  13. Transcranial pulsed electromagnetic fields for multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Tran, Marie Thi Dao; Skovbjerg, Sine; Arendt-Nielsen, Lars

    2013-01-01

    . The symptoms may have severe impact on patients' lives, but an evidence-based treatment for the condition is nonexisting. The pathophysiology is unclarified, but several indicators point towards abnormal processing of sensory signals in the central nervous system. Pulsed electromagnetic fields (PEMF) offer...

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

    Science.gov (United States)

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

  15. Pulsed electric field processing for fruit and vegetables

    Science.gov (United States)

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

  16. Pulsed-field gel electrophoresis typing of Staphylococcus aureus isolates

    Science.gov (United States)

    Pulsed-field gel electrophoresis (PFGE) is the most applied and effective genetic typing method for epidemiological studies and investigation of foodborne outbreaks caused by different pathogens, including Staphylococcus aureus. The technique relies on analysis of large DNA fragments generated by th...

  17. Transcranial pulsed electromagnetic fields for multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Tran, Marie Thi Dao; Skovbjerg, Sine; Arendt-Nielsen, Lars

    2013-01-01

    . The symptoms may have severe impact on patients' lives, but an evidence-based treatment for the condition is nonexisting. The pathophysiology is unclarified, but several indicators point towards abnormal processing of sensory signals in the central nervous system. Pulsed electromagnetic fields (PEMF) offer...

  18. Average Number of Coherent Modes for Pulse Random Fields

    CERN Document Server

    Lazaruk, A M; Lazaruk, Alexander M.; Karelin, Nikolay V.

    1997-01-01

    Some consequences of spatio-temporal symmetry for the deterministic decomposition of complex light fields into factorized components are considered. This enables to reveal interrelations between spatial and temporal coherence properties of wave. An estimation of average number of the decomposition terms is obtained in the case of statistical ensemble of light pulses.

  19. Efficacy in Microbial Sterilization of Pulsed Magnetic Field Treatment

    Science.gov (United States)

    Sterilization effects of the pulsed magnetic field with a maximum intensity of 11.37 Tesla were investigated on Escherichia coli AS 1.129, Staphylococcus aureus AS 1.89, Saccharomyces cerevisiae ATTC 7552 and Bacillus subtilis AS 1.921. The well-regulated fluctuations of sterilization effects with m...

  20. Band diagrams and field distribution of squarely-modulated slab metallic gratings

    Directory of Open Access Journals (Sweden)

    Jih-Yin Lee

    2016-12-01

    Full Text Available The optical transmission properties of squarely-modulated metallic gratings has been widely investigated. This study used rigorous-coupled wave analysis (RCWA to re-examine in detail the band structure of a laminated metal film with squarely-modulated metallic gratings located at the top. The top structure was shown to modify the long-range surface plasmon polariton modes (LRSPP at both interfaces of the thin metal film. When the thickness of the intact metal film was altered, the coupling between the two interfaces presented intriguing behavior. If the thickness of the metallic film was 30nm, the field achieved strong coupling similar to that of a two-level system. When the thickness was decreased to 10nm, the band branch possessing negative group velocity was dominant. Our results also verify that the first-order Fourier expansion of the gratings determined the energy position of bands at k||=0, whereas the second-order term caused band gap opening. Introducing an asymmetrical component to the grating profile intensified the opening effect at k||=0 due to an increase in the amplitude of the second-order Fourier component.

  1. Trapped magnetic field measurements on HTS bulk by peak controlled pulsed field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Ida, Tetsuya; Watasaki, Masahiro [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Kimura, Yosuke [Kawasaki Heavy Industries, Ltd. Technical Institute System Technology Development Centre 1-1, Kawasaki-cho, Akashi-shi, Hyogo 673-8666 (Japan); Miki, Motohiro; Izumi, Mitsuru, E-mail: ida@hiroshima-cmt.ac.j [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)

    2010-06-01

    For the past several years, we have studied the high-temperature superconducting (HTS) synchronous motor assembled with melt-textured Gd-Ba-Cu-O bulk magnets. If the single pulse field magnetizes a bulk effectively, size of electrical motor will become small for the strong magnetic field of the HTS magnets without reducing output power of motor. In the previous study, we showed that the HTS bulk was magnetized to excellent cone-shape magnetic field distribution by using the waveform control pulse magnetization (WCPM) method. The WCPM technique made possible the active control of the waveform on which magnetic flux motion depended. We generated the pulse waveform with controlled risetime for HTS bulk magnetization to suppress the magnetic flux motion which decreases magnetization efficiency. The pulsed maximum magnetic flux density with slow risetime is not beyond the maximum magnetic flux density which is trapped by the static field magnetization. But, as for applying the pulse which has fast risetime, the magnetic flux which exceed greatly the threshold penetrates the bulk and causes the disorder of the trapped magnetic distribution. This fact suggests the possibility that the threshold at pulsed magnetization influences the dynamic magnetic flux motion. In this study, Gd-Ba-Cu-O bulk is magnetized by the controlled arbitrary trapezoidal shape pulse, of which the maximum magnetic flux density is controlled not to exceed the threshold. We will present the trapped magnetic characteristics and the technique to generate the controlled pulsed field.

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

    OpenAIRE

    Ye Peng; Tao Liu; Haifeng Gong; Xianming Zhang

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

  4. Miniature coils for producing pulsed inplane magnetic fields for nanospintronics

    Energy Technology Data Exchange (ETDEWEB)

    Pawliszak, Łukasz; Zgirski, Maciej [Institute of Physics, Polish Academy of Sciences, al.Lotnikow 32/46, PL 02-668 Warszawa (Poland); Tekielak, Maria [Faculty of Physics, University of Białystok, ul.Lipowa 41, PL 15-424 Białystok (Poland)

    2015-03-15

    Nanospintronic and related research often requires the application of quickly rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-millimeter-sized coils capable of delivering pulses of the magnetic field up to ∼500 Oe in the plane of the sample with the rise time of the order of 10 ns. The placement of the sample above the coil allows for easy access to its surface with manipulators or light beams for, e.g., Kerr microscopy. We use the fabricated coil to drive magnetic domain walls in 1 μm wide permalloy wires and measure magnetic domain wall velocity as a function of the applied magnetic field.

  5. Effective field theory for coherent optical pulse propagation

    CERN Document Server

    Park, Q H; Park, Q Han

    1996-01-01

    Hidden nonabelian symmetries in nonlinear interactions of radiation with matter are clarified. In terms of a nonabelian potential variable, we construct an effective field theory of self-induced transparency, a phenomenon of lossless coherent pulse propagation, in association with Hermitian symmetric spaces G/H. Various new properties of self-induced transparency, e.g. soliton numbers, effective potential energy, gauge symmetry and discrete symmetries, modified pulse area, conserved U(1)-charge etc. are addressed and elaborated in the nondegenerate two-level case where G/H = SU(2)/U(1). Using the U(1)-charge conservation, a new type of analysis on pulse stability is given which agrees with earlier numerical results.

  6. Maximum trapped field of a ring bulk superconductor by low pulsed field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchimoto, M. [Hokkaido Institute of Technology, 7-15 Maeda, Teine-ku, Sapporo 006-8585 (Japan)], E-mail: tsuchi@hit.ac.jp; Kamijo, H. [Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji, Tokyo 185-8540 (Japan)

    2007-10-01

    Pulsed field magnetization is an important technique for a bulk superconducting magnet, which is one practical application of a bulk high T{sub c} superconductor (HTS). Full magnetization of a ring HTS is effective to obtain large trapped field for low pulsed field magnetization. In this study, trapped field in a ring bulk superconductor by the low pulsed field magnetization is numerically analyzed under assumption of variable shielding current by the temperature control. Differences between one-dimensional Bean model and axisymmetric three-dimensional numerical solution are discussed through the analysis. There is maximum trapped field in the axisymmetric three-dimensional model because of finite thickness of the ring HTS. The shielding current density and inner radius of the ring HTS are discussed to obtain the maximum trapped field.

  7. Effect of pulsed electromagnetic fields on orthodontic tooth movement.

    Science.gov (United States)

    Stark, T M; Sinclair, P M

    1987-02-01

    The purpose of this study was to determine whether the application of a simple surgically noninvasive, pulsed electromagnetic field could increase both the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the electromagnetic field's effects on bony physiology and metabolism and to search for possible systemic side effects. Laterally directed orthodontic force was applied to the maxillary central incisors of a sample of 40 young male, Hartley guinea pigs (20 experimental, 20 control) by means of a standardized intraoral coil spring inserted under constricting pressure into holes drilled in the guinea pigs' two maxillary central incisors. During the experimental period, the guinea pigs were placed in specially constructed, plastic animal holders with their heads positioned in an area of uniform electromagnetic field. Control animals were placed in similar plastic holders that did not carry the electrical apparatus. The application of a pulsed electromagnetic field to the experimental animals significantly increased both the rate and final amount of orthodontic tooth movement observed over the 10-day experimental period. The experimental animals also demonstrated histologic evidence of significantly greater amounts of bone and matrix deposited in the area of tension between the orthodontically moved maxillary incisors. This increase in cellular activity was also reflected by the presence of significantly greater numbers of osteoclasts in the alveolar bone surrounding the maxillary incisors of the experimental animals. After a 10-day exposure to pulsed electromagnetic field, minor changes in serologic parameters relating to protein metabolism and muscle activity were noted. The results of this study suggest that it is possible to increase the rate of orthodontic tooth movement and bone deposition through the application of a noninvasive, pulsed electromagnetic field.

  8. Pulsed beams as field probes for precision measurement

    OpenAIRE

    Hudson, J. J.; Ashworth, H. T.; Kara, D. M.; Tarbutt, M. R.; Sauer, B.E.; Hinds, E. A.

    2007-01-01

    We describe a technique for mapping the spatial variation of static electric, static magnetic, and rf magnetic fields using a pulsed atomic or molecular beam. The method is demonstrated using a beam designed to measure the electric dipole moment of the electron. We present maps of the interaction region, showing sensitivity to (i) electric field variation of 1.5 V/cm at 3.3 kV/cm with a spatial resolution of 15 mm; (ii) magnetic field variation of 5 nT with 25 mm resolution; (iii) radio-frequ...

  9. LUPIN, a new instrument for pulsed neutron fields

    Science.gov (United States)

    Caresana, M.; Ferrarini, M.; Manessi, G. P.; Silari, M.; Varoli, V.

    2013-06-01

    A number of studies focused in the last decades on the development of survey meters to be used in pulsed radiation fields. This is a topic attracting widespread interest for applications such as radiation protection and beam diagnostics in accelerators. This paper describes a new instrument specifically conceived for applications in pulsed neutron fields (PNF). The detector, called LUPIN, is a rem counter type instrument consisting of a 3He proportional counter placed inside a spherical moderator. It works in current mode with a front-end electronics consisting of a current-voltage logarithmic amplifier, whose output signal is acquired with an ADC and processed on a PC. This alternative signal processing allows the instrument to be used in PNF without being affected by saturation effects. Moreover, it has a measurement capability ranging over many orders of burst intensity. Despite the fact that it works in current mode, it can measure a single neutron interaction. The LUPIN was first calibrated in CERN's calibration laboratory with a PuBe source. Measurements were carried out under various experimental conditions at the Helmholtz-Zentrum in Berlin, in the stray field at various locations of the CERN Proton Synchrotron complex and around a radiotherapy linear accelerator at the S. Raffaele hospital in Milan. The detector can withstand single bursts with values of H*(10) up to 16 nSv/burst without showing any saturation effect. It efficiently works in pulsed stray fields, where a conventional rem-counter underestimates by a factor of 2. It is also able to reject the very intense and pulsed photon contribution that often accompanies the neutron field with good reliability.

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

    Science.gov (United States)

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

  11. Long-pulse magnetic field facility at Zaragoza

    Science.gov (United States)

    Algarabel, P. A.; del Moral, A.; Martín, C.; Serrate, D.; Tokarz, W.

    2006-11-01

    The long-pulse magnetic field facility of the Laboratorio de Magnetismo - Instituto de Ciencia de Materiales de Aragón (Universidad de Zaragoza-CSIC) produces magnetic fields up to 31, with a pulse duration of 2.2s. Experimental set-ups for measurements of magnetization, magnetostriction and magnetoresistance are available. The temperature can be controlled between 1.4 and 335 K, being the inner bore of the He cryostat of 22.5 mm. Magnetization is measured using the mutual induction technique, the magnetostriction is determined with the strain-gage and the capacitive cantilever methods, and the magnetoresistance is measured by means of the aclock-in technique in the 4-probes geometry. An overview of the facility will be presented and the presently available experimental techniques will be discussed.

  12. Detachment of Conductive Coatings by Pulsed Electromagnetic Field

    OpenAIRE

    Mironov, V.; Tatarinov, A.; Kolbe, M; Gluschenkov, V.

    2016-01-01

    The paper presents results of studies on the detachment of conductive coatings from the metal substrate by pulsed electromagnetic field (PEMF). It is known that at the boundary of a metal substrate and an electrically conductive coating having different electrical conductivities sharp changes of PEMF strength arise. This effect has been used to remove a copper layer from a steel substrate. Experimental studies were carried out in the Riga Technical University (Latvia), West Sax...

  13. Pulsed field magnetization in rare-earth kagome systems

    Science.gov (United States)

    Hoch, M. J. R.; Zhou, H. D.; Mun, E.; Harrison, N.

    2016-02-01

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd3+ is a Kramers ion while Pr3+ is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  14. Pulsed field magnetization in rare-earth kagome systems.

    Science.gov (United States)

    Hoch, M J R; Zhou, H D; Mun, E; Harrison, N

    2016-02-03

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd(3+) is a Kramers ion while Pr(3+) is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  15. Trapped field measurements of Gd-Ba-Cu-O bulk superconductor in controlled pulse field magnetizing

    Energy Technology Data Exchange (ETDEWEB)

    Ida, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Kimura, Y; Sano, T; Yamaguchi, K; Izumi, M [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Miki, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan)], E-mail: ida@hiroshima-cmt.ac.jp

    2008-02-01

    For large-scale electric power application of the melt-processed high temperature superconductor (HTS) bulks, especially at rotating machine, development of trapping much higher magnetic fields by using pulsed magnetization technique is essential. It is difficult to use static field cooling (FCM) technique that is most effective magnetizing method for the general industrial HTS applications, because the FCM requires large-scale superconducting magnets. Because the rise in temperature due to the magnetic flux motion decreases the pinning force, we controlled the magnetic flux penetrating to the bulk for the effective magnetization. A couple of vortex-type copper coils applied a magnetic field to a Gd-Ba-Cu-O bulk, which dimension was 45mm in diameter and 19 mm in thickness. HTS bulk was magnetized by the controlled pulse field without passive LCR pulse. We controlled waveform by using the discharge current that IGBT chopper in pulse magnetizer intermitted. We applied the pulse magnetic field with the various risetime to the HTS bulk in liquid nitrogen. The various conditions of the controlled waveform pulse to trap well-dressed profile magnetized the Gd-Ba-Cu-O bulk, strongly at 77K. In the present study, we show several properties which was measured in the PFM of the HTS bulk.

  16. Clinical update of pulsed electromagnetic fields on osteoporosis

    Institute of Scientific and Technical Information of China (English)

    HUANG Li-qun; HE Hong-chen; HE Cheng-qi; CHEN Jian; YANG Lin

    2008-01-01

    Objective To understand the effects of low-frequency pulsed electromagnetic fields (PEMFs) on chronic bony pain,bone mineral density (BMD), bone strength and biochemical markers of bone metabolism in the patients of osteoporosis.Data sources Using the key words "pulsed electromagnetic fields" and "osteoporosis", we searched the PubMed for related studies published in English from January 1996 to December 2007. We also searched the China National Knowledge Infrastructure (CNKI) for studies published in Chinese from January 1996 to December 2007.Study selection Inclusion criteria: (1) all articles which referred to the effects of low-frequency pulsed magnetic fields on osteoporosis either in primary osteoporosis or secondary osteoporosis; (2) either observational studies or randomized controlled studies. Exclusion criteria: (1) articles on experimental studies about osteoporosis; (2) repetitive studies; (3)case reports; (4) meta analysis.Results Totally 111 related articles were collected, 101 of them were published in Chinese, 10 were in English.Thirty-four were included and the remaining 84 were excluded.Conclusions Low-frequency PEMFs relieves the pain of primary osteoporosis quickly and efficiently, enhances bone formation and increases BMD of secondary osteoporosis. But the effects of PEMFs on bone mineral density of primary osteoporosis and bone resorption were controversial.

  17. Effects of Pulsed Electromagnetic Fields on Osteoporosis Model

    Science.gov (United States)

    Xiaowei, Yang; Liming, Wang; Guan, Z. C.; Yaou, Zhang; Xiangpeng, Wang

    The purpose of this paper was to investigate the preventive effects and long term effects of extremely low frequency pulsed electromagnetic fields (PEMFs), generated by circular coils and pulsed electromagnetic fields stimulators, on osteoporosis in bilaterally ovariectomized rats. In preventive experiment, thirty three-month old female Sprague-Dawley rats were randomly divided into three different groups: sham (SHAM), ovariectomy (OVX), PEMFs stimulation (PEMFs). All rats were subjected to bilaterally ovariectomy except those in SHAM group. The PEMFs group was exposed to pulsed electromagnetic fields with frequency 15 Hz, peak magnetic induction density 2.2mT and exposure time 2 hours per day. The bone mineral density (BMD) of vertebra and left femur were measured by dual energy X-ray absorptiometry at eighth week, twelfth week and sixteenth week after surgery. In long term effects experiment, forty four rats were randomly divided into sham (14 rats, SHAM), ovariectomy group (10 rats, OVX), 15Hz PEMFs group(10 rats, 15Hz) and 30Hz PEMFs group(10 rats, 30Hz) at twenty-sixth week after surgery. Rats in PEMFs groups were stimulated sixteen weeks. In preventive experiment, the Corrected BMD of vertebra and femur was significantly higher than that of OVX group after 16 weeks (Ptreatment of osteoporosis.

  18. Electrochemotherapy by pulsed electromagnetic field treatment (PEMF in mouse melanoma B16F10 in vivo

    Directory of Open Access Journals (Sweden)

    Kranjc Simona

    2016-03-01

    Full Text Available Pulsed electromagnetic field (PEMF induces pulsed electric field, which presumably increases membrane permeabilization of the exposed cells, similar to the conventional electroporation. Thus, contactless PEMF could represent a promising approach for drug delivery.

  19. Effects of an external magnetic field in pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, T. [Universidad Autonoma de la Ciudad de Mexico (UACM), Prolongacion San Isidro 151, Col. San Lorenzo Tezonco, C.P. 09790, Mexico DF (Mexico)], E-mail: tupacgarcia@yahoo.com; Posada, E. de [CINVESTAV-IPN Unidad Merida, Applied Physics Department, A.P. 73, Cordemex, C.P. 97130 Merida, Yuc. (Mexico); Villagran, M. [CCADET, Universidad Nacional Autonoma de Mexico (UNAM), A.P. 70-186, C.P. 04510, Mexico DF (Mexico); Ll, J.L. Sanchez [Laboratorio de Magnetismo, Facultad de Fisica-IMRE, Universidad de La Habana, La Habana 10400 (Cuba); Bartolo-Perez, P.; Pena, J.L. [CINVESTAV-IPN Unidad Merida, Applied Physics Department, A.P. 73, Cordemex, C.P. 97130 Merida, Yuc. (Mexico)

    2008-12-30

    Thin films were grown by pulsed laser deposition, PLD, on Si (1 0 0) substrates by the ablation of a sintered ceramic SrFe{sub 12}O{sub 19} target with and without the presence of a nonhomogeneous magnetic field of {mu}{sub 0}H = 0.4 T perpendicular to substrate plane and parallel to the plasma expansion axis. The field was produced by a rectangular-shaped Nd-Fe-B permanent magnet and the substrate was just placed on the magnet surface (Aurora method). An appreciable increment of optical emission due to the presence of the magnetic field was observed, but no film composition change or thickness increment was obtained. It suggests that the increment of the optical emission is due mainly to the electron confinement rather than confinement of ionic species.

  20. Generation and measurement of pulsed high magnetic field

    CERN Document Server

    Jana, S

    2000-01-01

    Pulsed magnetic field has been generated by discharging a capacitor bank through a 5-layer air-core solenoid. The strength of the magnetic field at its peak has been measured using the voltage induced in various pick-up coils, and also from the Zeeman splitting of an ion having a known g value. Synchronizing a xenon flash at the peak of the magnetic field, this lab-made instrument has been made well suited to study the Zeeman effect, etc. at a temperature of 25 K. As an application of this setup, we have investigated the Zeeman splitting of the sup 4 I sub 9 sub / sub 2-> sup 4 G sub 5 sub / sub 2 transition of the Nd sup 3 sup + -doped CsCdCl sub 3 crystal at 7.8 T, and determined the splitting factors.

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

    Science.gov (United States)

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

    2016-11-01

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

  2. Pulsed neutron fields measurements around a synchrotron storage ring

    Science.gov (United States)

    Caresana, Marco; Ballerini, Marcello; Ulfbeck, David Garf; Hertel, Niels; Manessi, Giacomo Paolo; Søgaard, Carsten

    2017-09-01

    A measurement campaign was performed for characterizing the neutron ambient dose equivalent, H*(10), in selected positions at ISA, Aarhus, Denmark, around the ASTRID and ASTRID2 storage rings. The neutron stray radiation field is characterized here by very intense radiation bursts with a low repetition rate, which result in a comparatively low average H*(10) rate. As a consequence, devices specifically conceived for operating in pulsed neutron fields must be employed for efficiently measuring in this radiation environment, in order to avoid severe underestimations of the H*(10) rate. The measurements were performed with the ELSE NUCLEAR LUPIN 5401 BF3-NP rem counter, a detector characterized by an innovative working principle that is not affected by dead time losses. This allowed characterizing both the H*(10) and the time structure of the radiation field in the pre-selected positions.

  3. Relationship Between Far Field Stresses, Fluid Flow and High-Pressure Deserpentinization in Subducting Slabs: a Case Study From the Almirez Ultramafic Massif

    Science.gov (United States)

    Dilissen, Nicole; Hidas, Károly; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Kahl, Wolf-Achim; Padrón-Navarta, José Alberto; Jesús Román-Alpiste, Manuel

    2017-04-01

    Serpentinite dehydration during prograde metamorphism plays a crucial role in subduction dynamics. Observations from exhumed paleo-subduction metamorphic terranes suggest that the discharge of deserpentinization fluids from the subducting slab takes place along different pathways and mechanisms [e.g. 1-3]. Analysis of intermediate-depth focal solutions in active subduction zones indicates that slabs are subjected to different principal stress fields characterized primarily by downdip compression and downdip tension [4]. Although it is well known that far field stresses play a crucial role on fluid flow channeling, their potential impact on the kinetics of serpentinite dehydration and subsequent fluid escape in subducting slabs is still poorly understood. Here, we present a detailed structural and microstructural study to investigate the relationships between far field stresses, fluid flow and high-pressure deserpentinization in the Almirez ultramafic massif (Betic Cordillera, SE Spain) [1, 2]. This massif preserves the high-pressure breakdown of antigorite (Atg-) serpentinite to prograde chlorite (Chl-) harzburgite, which are separated by a sharp isograd [2, 5]. The Chl-harzburgite reaction products show either a granofels or spinifex-like texture indicating crystallization under different overstepping of the Atg-out reaction. The two different textural types of Chl-harzburgite occur below the Atg-out isograd as alternating, meter-wide lenses with either a granofels or spinifex texture. From field measurements, we infer that during antigorite dehydration the minimum compressive stress was subnormal to the dehydration front and the paleo-slab surface. This stress field is consistent with subduction zones with slabs under downdip compression at intermediate depths [4]. The detailed microstructural study —combining µ-CT and EBSD-SEM [6]— of Chl-harzburgite across a c. 15 m wide lens reveals that the SPO and CPO of olivines with contrasting textures are strongly

  4. Pulsed-field gel electrophoresis of bacterial chromosomes.

    Science.gov (United States)

    Mawer, Julia S P; Leach, David R F

    2013-01-01

    The separation of fragments of DNA by agarose gel electrophoresis is integral to laboratory life. Nevertheless, standard agarose gel electrophoresis cannot resolve fragments bigger than 50 kb. Pulsed-field gel electrophoresis is a technique that has been developed to overcome the limitations of standard agarose gel electrophoresis. Entire linear eukaryotic chromosomes, or large fragments of a chromosome that have been generated by the action of rare-cutting restriction endonucleases, can be separated using this technique. As a result, pulsed-field gel electrophoresis has many applications, from karyotype analysis of microbial genomes, to the analysis of chromosomal strand breaks and their repair intermediates, to the study of DNA replication and the identification of origins of replication. This chapter presents a detailed protocol for the preparation of Escherichia coli chromosomal DNA that has been embedded in agarose plugs, digested with the rare-cutting endonuclease NotI, and separated by contour-clamped homogeneous field electrophoresis. The principles in this protocol can be applied to the separation of all fragments of DNA whose size range is between 40 kb and 1 Mb.

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

    Science.gov (United States)

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

    2016-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-05-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-01

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

  8. CHARACTERIZATION OF PATHOGENIC FUNGI GENOMES USING PULSED FIELD GEL ELECTROPHORESIS

    Institute of Scientific and Technical Information of China (English)

    吴绍熙; 郭宁如; 殷正男; 柴建华

    1996-01-01

    Pulsed field gel eleetrophoresis (PFGE) has been firstly introdueed in characterization of the pathogenic fungi Pericillium marneffei and Exophiata dermatitidis genomes. The numbers and sizes of their chromosomes have been detected. Polymorphism was identified on the smallest chromosome of E.derntatitidis. The result shows that PFGE for characterization of large molecular DNA pathogenic fungi is very suitable, it is more simple and more efficacy. The result also shows the diversity of pathogenic fungi is relative common even in rare occurred pathogeafie fungi such as E. dermatitidis.

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

    Science.gov (United States)

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

    2018-02-01

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

  10. Low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments affect degeneration of cultured articular cartilage explants

    NARCIS (Netherlands)

    Tan, Lijun; Ren, Yijin; Kooten, van Theo G.; Grijpma, Dirk W.; Kuijer, Roel

    2015-01-01

    Purpose: Articular cartilage has some capacity for self-repair. Clinically used low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments were compared in their potency to prevent degeneration using an explant model of porcine cartilage. Methods: Explants of porcine

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

    NARCIS (Netherlands)

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

    1999-01-01

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

  12. Vacuum magnetic linear birefringence using pulsed fields: the BMV experiment

    CERN Document Server

    Cadène, A; Fouché, M; Battesti, R; Rizzo, C

    2013-01-01

    In this letter we present the measurement of the vacuum magnetic birefringence obtained using the first generation setup of the BMV experiment. In particular, we detail our procedure of data acquisition and our analysis which takes into account the symmetry properties of raw data with respect to the orientation of the magnetic field and the sign of the cavity birefringence. Our current value of vacuum magnetic linear birefringence k_CM was obtained with about 100 magnetic pulses and a maximum field of 6.5 T. We get k_CM = (-7.4 \\pm 8.7).10^{-21} T^{-2} at 3 sigma confidence level. Our result is a clear validation of our innovative experimental method.

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

    Science.gov (United States)

    Cui, Guang-ying; Diao, Hong-yan

    2015-11-01

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

  14. Effects of pulsed electromagnetic fields on benign prostate hyperplasia.

    Science.gov (United States)

    Giannakopoulos, Xenophon K; Giotis, Christos; Karkabounas, Spyridon Ch; Verginadis, Ioannis I; Simos, Yannis V; Peschos, Dimitrios; Evangelou, Angelos M

    2011-12-01

    Benign prostate hyperplasia (BPH) has been treated with various types of electromagnetic radiation methods such as transurethral needle ablation (TUNA), interstitial laser therapy (ILC), holmium laser resection (HoLRP). In the present study, the effects of a noninvasive method based on the exposure of patients with BPH to a pulsative EM Field at radiofrequencies have been investigated. Twenty patients with BPH, aging 68-78 years old (y.o), were enrolled in the study. Patients were randomly divided into two groups: the treatment group (10 patients, 74.0 ± 5.7 y.o) treated with the α-blocker Alfusosin, 10 mg/24 h for at least 4 weeks, and the electromagnetic group (10 patients, 73.7 ± 6.3 y.o) exposed for 2 weeks in a very short wave duration, pulsed electromagnetic field at radiofrequencies generated by an ion magnetic inductor, for 30 min daily, 5 consecutive days per week. Patients of both groups were evaluated before and after drug and EMF treatment by values of total PSA and prostatic PSA fraction, acid phosphate, U/S estimation of prostate volume and urine residue, urodynamic estimation of urine flow rate, and International Prostate Symptom Score (IPSS). There was a statistically significant decrease before and after treatment of IPSS (P < 0.02), U/S prostate volume (P < 0.05), and urine residue (P < 0.05), as well as of mean urine flow rate (P < 0.05) in patients of the electromagnetic group, in contrast to the treatment group who had only improved IPSS (P < 0.05). There was also a significant improvement in clinical symptoms in patients of the electromagnetic group. Follow-up of the patients of this group for one year revealed that results obtained by EMFs treatment are still remaining. Pulsed electromagnetic field at radiofrequencies may benefit patients with benign prostate hyperplasia treated by a non-invasive method.

  15. Experimental Study of SO2 Removal by Pulsed DBD Along with the Application of Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    RONG Ming-zhe; LIU Ding-xin; WANG Xiao-hua; WANG Jun-hua

    2007-01-01

    Dielectric barrier discharge (DBD) for SO2 removal from indoor air is investigated.In order to improve the removal efficiency,two novel methods are combined in this paper,namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field.For SO2 removal efficiency,different matches of electric field and magnetic field are discussed.And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared.It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted,and electrical field and magnetic field should be applied in an appropriate match.

  16. Gravitational properties of light - The gravitational field of a laser pulse

    CERN Document Server

    Rätzel, Dennis; Menzel, Ralf

    2015-01-01

    The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are associated with the emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experien...

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

    Directory of Open Access Journals (Sweden)

    Ye Peng

    2016-01-01

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

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

    Science.gov (United States)

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

    2008-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-02-07

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

  20. Analytical solution of precessional switching in nanomagnets driven by hard-axis field pulses

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M., E-mail: daquino@uniparthenope.it [Engineering Department, University of Naples “Parthenope”, 80143 Naples (Italy); Perna, S.; Serpico, C. [DIETI, University of Naples Federico II, 80125 Naples (Italy); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD, 20742 (United States); Quercia, A. [DIETI, University of Naples Federico II, 80125 Naples (Italy)

    2016-04-01

    The precessional switching process of a magnetic nanoparticle subject to external field pulses applied along the hard-axis is considered. The critical field pulse amplitude necessary to realize the switching is determined. Then, the analytical solution of magnetization switching dynamics is derived in the lossless limit by using elliptic functions. Moreover, expressions for the field pulse duration tolerances which guarantee successful switching are also obtained. The theoretical predictions are verified by macrospin numerical simulations of ultra-fast magnetization switching.

  1. GROWTH, INSTABILITY AND FORECASTING OF PIGEON PEA, CHICKPEA AND FIELD PEA PULSE PRODUCTION IN BANGLADESH

    OpenAIRE

    Rahman, Niaz Md. Farhat; Imam, M. F.

    2008-01-01

    The study tried to find out the appropriate models using latest model selection criteria that could describe the best growth pattern of pigeon pea, chickpea and field pea pulse production. The study also tried to measure the instability, growth rates of pigeon pea, chickpea and field pea pulse production and to determine the efficient time series models, to forecast the future pigeon pea, chickpea and field pea pulse production in Bangladesh. Forecasting attempts have been made to achieve the...

  2. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    Science.gov (United States)

    Huang, Zhen; Ruiz, H. S.; Coombs, T. A.

    2017-03-01

    High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied under the same experimental conditions, what results in about three times larger magnetic pole areas but with an average drop on the peaks of trapped magnetic field of about 50%.

  3. Observation of enhanced field-free molecular alignment by two laser pulses

    DEFF Research Database (Denmark)

    Bisgaard, Christer; Poulsen, Mikael Dahlerup; Peronne, Emmanuel

    2004-01-01

    We show experimentally that field-free alignment of iodobenzene molecules, induced by a single, intense, linearly polarized 1.4-ps-long laser pulse, can be strongly enhanced by dividing the pulse into two optimally synchronized pulses of the same duration. For a given total energy of the two...

  4. Fast magnetic field annihilation driven by two laser pulses in underdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y. J.; Kumar, D.; Weber, S.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); Klimo, O. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); FNSPE, Czech Technical University in Prague, 11519 Prague (Czech Republic); Bulanov, S. V.; Esirkepov, T. Zh. [Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan)

    2015-10-15

    Fast magnetic annihilation is investigated by using 2.5-dimensional particle-in-cell simulations of two parallel ultra-short petawatt laser pulses co-propagating in underdense plasma. The magnetic field generated by the laser pulses annihilates in a current sheet formed between the pulses. Magnetic field energy is converted to an inductive longitudinal electric field, which efficiently accelerates the electrons of the current sheet. This new regime of collisionless relativistic magnetic field annihilation with a timescale of tens of femtoseconds can be extended to near-critical and overdense plasma with the ultra-high intensity femtosecond laser pulses.

  5. Manipulating antiferromagnets with magnetic fields: Ratchet motion of multiple domain walls induced by asymmetric field pulses

    Science.gov (United States)

    Gomonay, O.; Kläui, M.; Sinova, J.

    2016-10-01

    Future applications of antiferromagnets (AFs) in many spintronics devices rely on the precise manipulation of domain walls. The conventional approach using static magnetic fields is inefficient due to the low susceptibility of AFs. Recently proposed electrical manipulation with spin-orbit torques is restricted to metals with a specific crystal structure. Here, we propose an alternative, broadly applicable approach: using asymmetric magnetic field pulses to induce controlled ratchet motion of AF domain walls. The efficiency of this approach is based on three peculiarities of AF dynamics. First, a time-dependent magnetic field couples with an AF order parameter stronger than a static magnetic field, which leads to higher mobility of the domain walls. Second, the rate of change of the magnetic field couples with the spatial variation of the AF order parameter inside the domain, and this enables a synchronous motion of multiple domain walls with the same structure. Third, tailored asymmetric field pulses in combination with static friction can prevent backward motion of domain walls and thus lead to the desired controlled ratchet effect. The proposed use of an external field, rather than internal spin-orbit torques, avoids any restrictions on size, conductivity, and crystal structure of the AF material. We believe that our approach paves a way for the development of AF-based devices based on the controlled motion of AF domain walls.

  6. Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaobin, E-mail: yangxb@lzu.edu.cn; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo

    2017-04-15

    Highlights: • The differential equation including temperature and magnetic field was derived for a long cylindrical superconductor. • Thermal stress and electromagnetic stress were studied at the same time under pulse field magnetizing. • The distributions of the magnetic field, the temperature and stresses are studied and compared for two pulse fields of the different duration. • The Role thermal stress and electromagnetic stress play in the process of pulse field magnetizing is discussed. - Abstract: A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

  7. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    CERN Document Server

    Caresana, M; Esposito, A; Ferrarini, M; Golnik, N; Hohmann, E; Leuschner, A; Luszik-Bhadra, M; Manessi, G; Mayer, S; Ott, K; Röhrich, J; Silari, M; Trompier, F; Volnhals, M; Wielunski, M

    2014-01-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instru...

  8. In vitro exposure of human chondrocytes to pulsed electromagnetic fields

    Directory of Open Access Journals (Sweden)

    V Nicolin

    2009-08-01

    Full Text Available The effect of pulsed electromagnetic fields (PEMFs on the proliferation and survival of matrix-induced autologous chondrocyte implantation (MACI®-derived cells was studied to ascertain the healing potential of PEMFs. MACI-derived cells were taken from cartilage biopsies 6 months after surgery and cultured. No dedifferentiation towards the fibroblastic phenotype occurred, indicating the success of the surgical implantation. The MACI-derived cultured chondrocytes were exposed to 12 h/day (short term or 4 h/day (long term PEMFs exposure (magnetic field intensity, 2 mT; frequency, 75 Hz and proliferation rate determined by flow cytometric analysis. The PEMFs exposure elicited a significant increase of cell number in the SG2M cell cycle phase. Moreover, cells isolated from MACI® scaffolds showed the presence of collagen type II, a typical marker of chondrocyte functionality. The results show that MACI® membranes represent an optimal bioengineering device to support chondrocyte growth and proliferation in surgical implants. The surgical implant of MACI® combined with physiotherapy is suggested as a promising approach for a faster and safer treatment of cartilage traumatic lesions.

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

    CERN Document Server

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

    2009-01-01

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

  10. Pulsed Field Waveforms for Magnetization of HTS Gd-Ba-Cu-O Bulk Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ida, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Matsuzaki, H [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Morita, E [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Sakashita, H [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Harada, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Ogata, H [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Kimura, Y [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Miki, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Kitano, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Izumi, M [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)

    2006-06-01

    Progress in pulse magnetization technique for high-temperature superconductor bulks of melt-textured RE-Ba-Cu-O with large diameter is important for the realization of power applications. We studied the pulsed power source and pulsed field waveforms to enhance to improve the magnetization properties for Gd-Ba-Cu-O bulk. The risetime and duration of pulse waveform effectively varied distribution of magnetic flux.

  11. Effect of pulse magnetic field on solidification structure and properties of pure copper

    Institute of Scientific and Technical Information of China (English)

    LIAO Xi-liang; GONG Yong-yong; LI Ren-xing; CHEN Wen-jie; ZHAI Qi-jie

    2007-01-01

    The application of pulse magnetic field to metal solidification is an advanced technique which can remarkably refine solidification structure. In this paper, the effect of pulse magnetic field on solidification structure,mechanical properties and conductivity of pure copper was experimentally investigated. The results showed that the solidification structure transformed from coarse columnar crystal to fine globular crystal with increasing pulse voltage.Increasing pulse voltage also improved the tensile strength. However, with the increase of pulse voltage, the elongation and electrical resistivity firstly decreased, then increased when the pulse voltage beyond a critical value. Moreover,in some conditions, pulse magnetic field can simultaneously improve the conductivity and mechanical property of pure copper.

  12. Slab-derived metasomatism in the Carpathian-Pannonian mantle revealed by investigations of mantle xenoliths from the Bakony-Balaton Highland Volcanic Field

    Science.gov (United States)

    Créon, Laura; Delpech, Guillaume; Rouchon, Virgile; Guyot, François

    2017-08-01

    A suite of fifteen peridotite xenoliths from the Bakony-Balaton Highland Volcanic Field (BBHVF, Pannonian Basin, Central Europe) that show abundant petrographic evidence of fluid and melt percolation were studied in order to decipher the formation of their melt pockets and veins. The suite mainly consists of ;fertile; lherzolites (5.8-19.9 vol.% clinopyroxene) and a few harzburgites (1.9-5.4 vol.% clinopyroxene) from well-known localities (Szentbékkálla, Szigliget) and two previously unreported localities (Füzes-tó and Mindszentkálla). Major and trace element data indicate that most of the peridotites record variable degrees of partial melt extraction, up to > 15% for the harzburgites. Subsequently, the xenoliths experienced at least two stages of metasomatic modification. The first stage was associated with percolation of a volatile-bearing silicate melt and resulted in crystallization of amphibole, enrichment in the most incompatible trace elements (Ba, Th, U, Sr), and development of negative Nb-Ta anomalies in clinopyroxene. The second and last metasomatic event, widespread beneath the BBHVF, is associated with the formation of silicate melt pockets, physically connected to a network of melt veins, with large and abundant CO2 vesicles. The glass in these veins has sub-alkaline trachy-andesitic composition and displays an OIB-like trace element signature. Its composition attests to the migration through a supra-subduction zone mantle wedge of silicic melt highly enriched in volatiles (CO2, H2O, Cl, F), LILE, REE and HFSE and consistent with compositions of natural and experimental examples of slab melting-derived magma. In the present case, however, melt was likely derived from melting of oceanic crust and carbonated sediments under conditions where Nb-rich mineral phases were not stable in the residue. A likely scenario for the origin such melts involves melting after subduction ceased as the slab thermally equilibrated with the asthenosphere. Melt

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

    Directory of Open Access Journals (Sweden)

    Elisa eLuengo

    2014-08-01

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

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

    CERN Document Server

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

    2016-01-01

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

  15. Topological Susceptibility from Slabs

    CERN Document Server

    Bietenholz, Wolfgang; Gerber, Urs

    2015-01-01

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility chi_t. In principle it seems straightforward to measure chi_t by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure chi_t even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of chi_t, as we demonstrate with numerical results for non-linear sigma-models.

  16. Pulsed-field capillary electrophoresis: optimizing separation parameters with model mixtures of sulfonated polystyrenes.

    Science.gov (United States)

    Sudor, J; Novotny, M V

    1994-07-01

    The electrophoretic transport of high molecular weight charged solutes, both flexible and stiff polymers, has been studied by capillary electrophoresis under constant-field and pulsed-field conditions. Sulfonated polystyrenes were used as model solutes in different entangled polymer solutions. First, changes of the end-to-end distance vectors of flexible polymers were examined through the mobility/potential-gradient curves. Under pulsed-field conditions, the influence of different pulse shapes, frequencies, and amplitudes of forward and backward pulses on the electrophoretic mobilities of model solutes was studied. Resolution of the mixture components was strongly affected by changes in frequency of both sine-wave and square-wave pulses. The experimental results obtained under pulse-field conditions are roughly in agreement with the existing theories of electrophoretic transport.

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

    Science.gov (United States)

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

    2003-05-21

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

  18. Effects of pulsed electromagnetic fields on postmenopausal osteoporosis.

    Science.gov (United States)

    Zhu, Siyi; He, Hongchen; Zhang, Chi; Wang, Haiming; Gao, Chengfei; Yu, Xijie; He, Chengqi

    2017-09-01

    Postmenopausal osteoporosis (PMOP) is considered to be a well-defined subject that has caused high morbidity and mortality. In elderly women diagnosed with PMOP, low bone mass and fragile bone strength have been proven to significantly increase risk of fragility fractures. Currently, various anabolic and anti-resorptive therapies have been employed in an attempt to retain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs), first applied in treating patients with delayed fracture healing and nonunions, may turn out to be another potential and effective therapy for PMOP. PEMFs can enhance osteoblastogenesis and inhibit osteoclastogenesis, thus contributing to an increase in bone mass and strength. However, accurate mechanisms of the positive effects of PEMFs on PMOP remain to be further elucidated. This review attempts to summarize recent advances of PEMFs in treating PMOP based on clinical trials, and animal and cellular studies. Possible mechanisms are also introduced, and the future possibility of application of PEMFs on PMOP are further explored and discussed. Bioelectromagnetics. 38:406-424, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  19. Epidemiological Typing of Moraxella Catarrhalis by Pulsed Field Gel Electrophoresis

    Directory of Open Access Journals (Sweden)

    Susan M Davison

    1995-01-01

    Full Text Available Pulsed field gel electrophoresis (pfge was used to compare 59 strains of Moraxella catarrhalis to evaluate pfge for the epidemiological typing of this organism. pfge-generated patterns were compared with those obtained by small fragment restriction enzyme analysis (rea and species-specific probe hybridization. The strains used in the study were isolated from various geographic locations and included proven epidemiologically related strains. pfge yielded more unique patterns than dna-dna hybridization – 30 versus 18, respectively – but fewer than rea, which generated 45 unique patterns. Strains that demonstrated the same rea pattern or dna-dna hybridization pattern did not always demonstrate the same pfge pattern. For example, in 23 epidemiologically unrelated strains that shared six rea patterns, pfge differentiated the isolates into 12 patterns. Conversely, strains that demonstrated the same pfge pattern did not always demonstrate the same rea pattern or hybridization pattern. For example, in 42 strains that shared 13 pfge patterns, rea differentiated the isolates into 31 patterns and dna-dna hybridization differentiated them into 16 patterns. However, compared with rea, pfge yielded less complex patterns that were more easily comparable, and compared with dna-dna hybridization, pfge was technically easier.

  20. Research on Nanosecond Pulse Corona Discharge with Cross Magnetic Field Applied

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-hao; YU Fu-sheng; HU Feng; YUAN Yun; GUO Li-na; LI Jin

    2007-01-01

    An application of magnetic field to the nanosecond pulse corona discharge is investigated.A cylinder reactor with different corona electodes is set up for experimental study.A manetic field with its direction perpendicular to the corona discharge is applied.Different discharge images are taken under single nanosecond pulse with a high sensitive UV-visible light imagine recorder.Experimental results show that with a cross magnetic field the nanosecond out the magnetic field. The results may lead to a possibility to apply a cross magnetic field on nanosecond pulse corona discharge for getting higher desulfurization effciency.

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

    NARCIS (Netherlands)

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

    2005-01-01

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

  2. Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions

    Science.gov (United States)

    2009-12-01

    FINAL REPORT Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions ESTCP Project WP-200212...PROGRAM ELEMENT NUMBER Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions 6. AUTHOR(S) 5d. PROJECT

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

    NARCIS (Netherlands)

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

    2013-01-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  5. The influence of laser pulse on the photoabsorption spectra of Li atom in strong external field

    Institute of Scientific and Technical Information of China (English)

    WANG; Dehua; LIN; Shenglu

    2006-01-01

    Using the time-dependent perturbation theory and the calculation formula of the single- and double-pulse absorption spectra of the atom in strong external fields, we calculate the single- and double-pulse absorption spectra of Li atom in strong magnetic field for different pulse widths. The results show that a pulse of some width can reduce the contribution of the short period closed orbits and eliminate the contribution of the long period orbits. Compared with the single-pulse absorption spectra, we found that for some phase differences, the double-pulse laser absorption spectra are strengthened; while for others, they are reduced. Therefore, we can use the pulse laser to control the oscillation of the absorption spectra and obtain the optimization object.

  6. A general framework to quantify the effect of restricted diffusion on the NMR signal with applications to double pulsed field gradient NMR experiments.

    Science.gov (United States)

    Ozarslan, Evren; Shemesh, Noam; Basser, Peter J

    2009-03-14

    Based on a description introduced by Robertson, Grebenkov recently introduced a powerful formalism to represent the diffusion-attenuated NMR signal for simple pore geometries such as slabs, cylinders, and spheres analytically. In this work, we extend this multiple correlation function formalism by allowing for possible variations in the direction of the magnetic field gradient waveform. This extension is necessary, for example, to incorporate the effects of imaging gradients in diffusion-weighted NMR imaging scans and in characterizing anisotropy at different length scales via double pulsed field gradient (PFG) experiments. In cylindrical and spherical pores, respectively, two- and three-dimensional vector operators are employed whose form is deduced from Grebenkov's results via elementary operator algebra for the case of cylinders and the Wigner-Eckart theorem for the case of spheres. The theory was validated by comparison with known findings and with experimental double-PFG data obtained from water-filled microcapillaries.

  7. Pulse

    Science.gov (United States)

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

  8. A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

    Science.gov (United States)

    Hu, Guangyue; Liang, Yihan; Song, Falun; Yuan, Peng; Wang, Yulin; Zhao, Bin; Zheng, Jian

    2015-02-01

    A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast (~230 ns), 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device (ICCD) detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.

  9. Considerations concerning the use of counting active personal dosimeters in pulsed fields of ionising radiation.

    Science.gov (United States)

    Ambrosi, Peter; Borowski, Markus; Iwatschenko, Michael

    2010-06-01

    Active personal electronic dosimeters (APDs) exhibit limitations in pulsed radiation fields, which cannot be overcome without the use of new detection technology. As an interim solution, this paper proposes a method by which some conventional dosimeters can be operated in a way such that, based on the basic knowledge about the pulsed radiation field, any dosimetric failure of the dosimeter is signalised by the instrument itself. This method is not applicable to all combinations of APD and pulsed radiation field. The necessary requirements for the APD and for the parameters of the pulsed radiation field are given in the paper. Up to now, all such requirements for APDs have not been tested or verified in a type test. The suitability of the method is verified for the use of one APD used in two clinical pulsed fields.

  10. Nanosecond pulsed electric fields and the cell cycle

    Science.gov (United States)

    Mahlke, Megan A.

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

  11. Tailored RF pulse optimization for magnetization inversion at ultra high field

    CERN Document Server

    Hurley, Aaron C; Li, Bai; Aickelin, Uwe; Coxon, Ron; Glover, Paul; Gowland, Penny A

    2010-01-01

    The radiofrequency (RF) transmit field is severely inhomogeneous at ultrahigh field due to both RF penetration and RF coil design issues. This particularly impairs image quality for sequences that use inversion pulses such as magnetization prepared rapid acquisition gradient echo and limits the use of quantitative arterial spin labeling sequences such as flow-attenuated inversion recovery. Here we have used a search algorithm to produce inversion pulses tailored to take into account the heterogeneity of the RF transmit field at 7 T. This created a slice selective inversion pulse that worked well (good slice profile and uniform inversion) over the range of RF amplitudes typically obtained in the head at 7 T while still maintaining an experimentally achievable pulse length and pulse amplitude in the brain at 7 T. The pulses used were based on the frequency offset correction inversion technique, as well as time dilation of functions, but the RF amplitude, frequency sweep, and gradient functions were all generate...

  12. Generation of flat-top pulsed magnetic fields with feedback control approach

    CERN Document Server

    Kohama, Yoshimitsu

    2015-01-01

    We describe the construction of a simple, compact, and cost-effective feedback system that produces flat-top field profiles in pulsed magnetic fields. This system is designed for use in conjunction with a typical capacitor-bank driven pulsed magnet, and was tested using a 60-T pulsed magnet. With the developed feedback controller, we have demonstrated flat-top magnetic fields as high as 60.64 T with an excellent field stability of +-0.005 T. The result indicates that the flat-top pulsed magnetic field produced features high field stability and an accessible field strength. These features make this system useful for improving the resolution of data with signal averaging.

  13. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhen, E-mail: zhen.huang@sjtu.edu.cn [Academy of Information Technology and Electrical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Ruiz, H.S., E-mail: dr.harold.ruiz@le.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Coombs, T.A., E-mail: tac1000@cam.ac.uk [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2017-03-15

    Highlights: • Different compositions of the magnetic poles have been obtained depending on the relative orientation of the magnetizing coil and the surfaces of the columns of bulks that conform a magnetic pole. • Two bidimensional models accounting for the electromagnetic response of the top and lateral cross sections of three columns of HTS bulks subjected to multiple pulsed magnetic fields have been created. • An extended PFM strategy has been proposed by considering the magnetization of at least three successive columns of HTS bulks per pole. In the extended PFM strategy the area of each one of the poles can be seen increased by a factor of 200%-400% - Abstract: High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied

  14. Control of the polarization of attosecond pulses using a two-color field

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Camilo; Hoffmann, David J; Torres, Ricardo; Chipperfield, Luke E; Marangos, Jonathan P [Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom)], E-mail: camilo@usal.es

    2009-11-15

    Control over the polarization of an attosecond pulse train (APT) is demonstrated theoretically using orthogonally polarized two-color fields. The carrier envelope phase of the two pulses is used as a control parameter to generate both an APT with linear polarization in two nearly perpendicular planes or a train of elliptically polarized pulses of alternating helicity. By using few-cycle driving laser fields an isolated attosecond pulse with elliptical polarization is shown to be generated after selecting the cut-off region of the harmonic spectrum. The control mechanism is explained in terms of classical trajectories.

  15. Investigation of the behavior of protection elements against field radiated line coupled UWB-pulses

    Directory of Open Access Journals (Sweden)

    R. Krzikalla

    2006-01-01

    Full Text Available To protect electronic systems against electromagnetic interferences in general nonlinear protection circuits are used. These protection circuits are optimized mostly against special transient interferences such as lightning electromagnetic pulses (LEMP or electromagnetic pulses caused by nuclear explosions (NEMP. Previous investigations have shown that these protection elements could be undermined by so-called ultra wideband (UWB pulses. Thereby a direct charge of the UWB-pulse to the elements has been assumed. This assumption was a worst case approximation because in practice UWB-pulses only get into systems by coupling effects. In this investigation the behavior of typical nonlinear protection elements has been tested with field radiated line coupled UWB-pulses. For that line coupled UWB-pulses have been defined depending on the coupling behavior of typical electronic systems and a possibility of generation of this kind of pulses is presented. After it typical nonlinear protection elements such as spark gaps, varistors and protection diodes have been tested with the previously defined test pulses. Finally the measured behavior of the elements has been compared with the behavior by direct charged UWB-pulses and the protection effect of the elements against field radiated line coupled UWB-pulses is re-evaluated.

  16. Analysis of Graphite Morphology of Gray Cast Iron in Pulse Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    LI Qiu-shu; LIU Li-qiang; ZHAI Qi-jie

    2005-01-01

    By self-made pulse electrical source and strong magnetic field solidification tester,the effect of strong pulse magnetic field on graphite morphology and solidification structure of gray cast iron was studied.The results show that the structure is remarkably refined after treated by pulse magnetic field,and the width of graphite flakes is decreased while the length is increased after a slight decrease.The solidification temperature and eutectic temperature are increased and the undercooling degree of eutectic transformation is decreased by magnetic field.

  17. Campo elétrico pulsado Pulsed electric field

    Directory of Open Access Journals (Sweden)

    Mirella Lima Binoti

    2012-05-01

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

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

    Science.gov (United States)

    Yogesh, K

    2016-02-01

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

  19. Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance.

    Science.gov (United States)

    Sjolander, Tobias F; Tayler, Michael C D; King, Jonathan P; Budker, Dmitry; Pines, Alexander

    2016-06-30

    We use low-amplitude, ultralow frequency pulses to drive nuclear spin transitions in zero and ultralow magnetic fields. In analogy to high-field NMR, a range of sophisticated experiments becomes available as these allow narrow-band excitation. As a first demonstration, pulses with excitation bandwidths 0.5-5 Hz are used for population redistribution, selective excitation, and coherence filtration. These methods are helpful when interpreting zero- and ultralow-field NMR spectra that contain a large number of transitions.

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

    Science.gov (United States)

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

    2013-05-01

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

  1. Effects of spectral linewidth of ultrashort pulses on the spa-tiotemporal distribution of diffraction fields

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The spatiotemporal characteristics of electromagnetic pulses with ultrabroad spectral bandwidth in the far field are analyzed by using classical scalar diffraction theory. The effects of the ratio of the frequency width to the central frequency on the diffraction spatial distribution are discussed. It is concluded that the diffraction spatial dis-tribution of the pulsed radiation gets narrower than a mono-chromatic wave when the frequency width of the pulse is comparable to or larger than its central frequency.

  2. Investigating DNA Migration in Pulsed Fields Using a Miniaturized Field Inversion Gel Electrophoresis System

    Science.gov (United States)

    Chen, Xiaojia; Ugaz, Victor M.

    2010-01-01

    Pulsed field gel electrophoresis (PFGE) is a well-established technique for fractionation of DNA fragments ranging from kilobases to megabases in length. But many of these separations require an undesirable combination of long experiment times (often approaching tens of hours) and application of high voltages (often approaching tens of kV). Here we present a simple miniaturized field inversion gel electrophoresis (FIGE) apparatus capable of separating DNA fragments up to 32.5 kb in length within 3 hours using a modest applied potential of 20 V. The device is small enough to be imaged under a fluorescence microscope, permitting the migrating DNA bands to be observed during the course of the separation run. We use this capability to investigate how separation performance is affected by parameters including the ratio of forward and backward voltage, pulse time, and temperature. We also characterize the dependence of DNA mobility on fragment size N, and observe a scaling in the vicinity of N−0.5 over the size range investigated. The high speed, low power consumption, and simple design of this system may help enable future studies of DNA migration in PFGE to be performed quickly and inexpensively. PMID:19053074

  3. Sausage oscillations of coronal plasma slabs

    Science.gov (United States)

    Hornsey, C.; Nakariakov, V. M.; Fludra, A.

    2014-07-01

    Context. Sausage oscillations are observed in plasma non-uniformities of the solar corona as axisymmetric perturbations of the non-uniformity. Often, these non-uniformities can be modelled as field-aligned slabs of the density enhancement. Aims: We perform parametric studies of sausage oscillations of plasma slabs, aiming to determine the dependence of the oscillation period on its parameters, and the onset of leaky and trapped regimes of the oscillations. Methods: Slabs with smooth transverse profiles of the density of a zero-beta plasma are perturbed by an impulsive localised perturbation of the sausage symmetry. In particular, the slab can contain an infinitely thin current sheet in its centre. The initial value problem is then solved numerically. The numerical results are subject to spectral analysis. The results are compared with analytical solutions for a slab with a step-function profile and also with sausage oscillations of a plasma cylinder. Results: We established that sausage oscillations in slabs generally have the same properties as in plasma cylinders. In the trapped regime, the sausage oscillation period increases with the increase in the longitudinal wavelength. In the leaky regime, the dependence of the period on the wavelength experiences saturation, and the period becomes independent of the wavelength in the long-wavelength limit. In the leaky regime the period is always longer than in the trapped regime. The sausage oscillation period in a slab is always longer than in a cylinder with the same transverse profile. In slabs with steeper transverse profiles, sausage oscillations have longer periods. The leaky regime occurs at shorter wavelengths in slabs with smoother profiles.

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

    Science.gov (United States)

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

    2017-05-01

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

  5. Temporal and Spectral Properties of Subcycle THz Pulses in Near-Field Zone

    Institute of Scientific and Technical Information of China (English)

    YANG Yu-Ping; YAN Wei; XU Xin-Long; SHI Yu-Lei; WANG Li

    2005-01-01

    @@ In a novel generation and detection configuration of terahertz (THz) radiation, we investigate experimentally and numerically the properties of sub-cycle THz pulses in the near field. It is found that the sub-cycle THz pulses experience significant spectral and temporal deformation in the near-field zone. The variations of both the pulse waveform and spectral distribution of the THz electric field are clearly observed in our experiments when the spot size of source is changed. Numerical simulations based on Gaussian distribution are performed to explain the details of the data and lead to an excellent agreement with the experimental results.

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

    CERN Document Server

    Kohlfürst, Christian

    2012-01-01

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

  7. 5 × 5 cm2 silicon photonic crystal slabs on glass and plastic foil exhibiting broadband absorption and high-intensity near-fields

    Science.gov (United States)

    Becker, C.; Wyss, P.; Eisenhauer, D.; Probst, J.; Preidel, V.; Hammerschmidt, M.; Burger, S.

    2014-07-01

    Crystalline silicon photonic crystal slabs are widely used in various photonics applications. So far, the commercial success of such structures is still limited owing to the lack of cost-effective fabrication processes enabling large nanopatterned areas (>> 1 cm2). We present a simple method for producing crystalline silicon nanohole arrays of up to 5 × 5 cm2 size with lattice pitches between 600 and 1000 nm on glass and flexible plastic substrates. Exclusively up-scalable, fast fabrication processes are applied such as nanoimprint-lithography and silicon evaporation. The broadband light trapping efficiency of the arrays is among the best values reported for large-area experimental crystalline silicon nanostructures. Further, measured photonic crystal resonance modes are in good accordance with light scattering simulations predicting strong near-field intensity enhancements greater than 500. Hence, the large-area silicon nanohole arrays might become a promising platform for ultrathin solar cells on lightweight substrates, high-sensitive optical biosensors, and nonlinear optics.

  8. 5 × 5 cm² silicon photonic crystal slabs on glass and plastic foil exhibiting broadband absorption and high-intensity near-fields.

    Science.gov (United States)

    Becker, C; Wyss, P; Eisenhauer, D; Probst, J; Preidel, V; Hammerschmidt, M; Burger, S

    2014-07-30

    Crystalline silicon photonic crystal slabs are widely used in various photonics applications. So far, the commercial success of such structures is still limited owing to the lack of cost-effective fabrication processes enabling large nanopatterned areas (≫ 1 cm(2)). We present a simple method for producing crystalline silicon nanohole arrays of up to 5 × 5 cm(2) size with lattice pitches between 600 and 1000 nm on glass and flexible plastic substrates. Exclusively up-scalable, fast fabrication processes are applied such as nanoimprint-lithography and silicon evaporation. The broadband light trapping efficiency of the arrays is among the best values reported for large-area experimental crystalline silicon nanostructures. Further, measured photonic crystal resonance modes are in good accordance with light scattering simulations predicting strong near-field intensity enhancements greater than 500. Hence, the large-area silicon nanohole arrays might become a promising platform for ultrathin solar cells on lightweight substrates, high-sensitive optical biosensors, and nonlinear optics.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Stephen J Beebe

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  14. Pulsed electromagnetic field radiation from a narrow slot antenna with a dielectric layer

    NARCIS (Netherlands)

    Štumpf, M.; De Hoop, A.T.; Lager, I.E.

    2010-01-01

    Analytic time domain expressions are derived for the pulsed electromagnetic field radiated by a narrow slot antenna with a dielectric layer in a two‐dimensional model configuration. In any finite time window of observation, exact pulse shapes for the propagated, reflected, and refracted wave constit

  15. Effects of change in slab geometry on the mantle flow and slab fabric in Southern Peru

    Science.gov (United States)

    Knezevic Antonijevic, Sanja; Wagner, Lara S.; Beck, Susan L.; Long, Maureen D.; Zandt, George; Tavera, Hernando

    2016-10-01

    The effects of complex slab geometries on the surrounding mantle flow field are still poorly understood. Here we combine shear wave velocity structure with Rayleigh wave phase anisotropy to examine these effects in southern Peru, where the slab changes its geometry from steep to flat. To the south, where the slab subducts steeply, we find trench-parallel anisotropy beneath the active volcanic arc that we attribute to the mantle wedge and/or upper portions of the subducting plate. Farther north, beneath the easternmost corner of the flat slab, we observe a pronounced low-velocity anomaly. This anomaly is caused either by the presence of volatiles and/or flux melting that could result from southward directed, volatile-rich subslab mantle flow or by increased temperature and/or decompression melting due to small-scale vertical flow. We also find evidence for mantle flow through the tear north of the subducting Nazca Ridge. Finally, we observe anisotropy patterns associated with the fast velocity anomalies that reveal along strike variations in the slab's internal deformation. The change in slab geometry from steep to flat contorts the subducting plate south of the Nazca Ridge causing an alteration of the slab petrofabric. In contrast, the torn slab to the north still preserves the primary (fossilized) petrofabric first established shortly after plate formation.

  16. Anomalous spectral behaviour of diffracted chirped Gaussian pulses in the near field

    Institute of Scientific and Technical Information of China (English)

    Pan Liu-Zhan; L(u) Bai-Da

    2004-01-01

    By using the Fourier transform method, analytical expressions for the axial power spectrum and near-field intensity in the spacetime domain of chirped Gaussian pulses diffracted at an aperture are derived, which permit us to study changes in spectral and temporal profiles of the chirped Gaussian pulses both analytically and numerically. Detailed numerical results and physical analysis show that spectral anomalies take place in the neighbourhood of certain critical distances, and the shifting of maximum and splitting of temporal intensity profiles appear. In particular, for ultrashort chirped pulses, there exists also spectral switch. Besides the truncation parameter, the chirp parameter and pulse duration affect the behaviour of spectral switches.

  17. Generation of elliptically polarized nitrogen-ion laser fields using two-color femtosecond laser pulses

    CERN Document Server

    Li, Ziting; Chu, Wei; Xie, Hongqiang; Yao, Jinping; Li, Guihua; Qiao, Lingling; Wang, Zhanshan; Cheng, Ya

    2015-01-01

    We experimentally investigate generation of molecular nitrogen-ion lasers with two femtosecond laser pulses at different wavelengths. The first pulse serves as the pump which ionizes the nitrogen molecules and excites the molecular ions to excited electronic states. The second pulse serves as the probe which leads to stimulated emission from the excited molecular ions. We observe that changing the angle between the polarization directions of the two pulses gives rise to elliptically polarized molecular nitrogen-ion laser fields, which is interpreted as a result of strong birefringence of the gain medium near the wavelengths of the molecular nitrogen-ion laser.

  18. Strong Field Molecular Ionization in the Impulsive Limit: Freezing Vibrations with Short Pulses

    CERN Document Server

    Sándor, Péter; Zhao, Arthur; Rozgonyi, Tamás; Ruckenbauer, Matthias; Marquetand, Philipp; Weinacht, Thomas

    2016-01-01

    We study strong-field molecular ionization as a function of pulse duration. Experimental measurements of the photoelectron yield for a number of molecules reveal competition between different ionization continua (cationic states) which depends strongly on pulse duration. Surprisingly, in the limit of short pulse duration, we find that a single ionic continuum dominates the yield, whereas multiple continua are produced for longer pulses. Using calculations which take vibrational dynamics into account, we interpret our results in terms of nuclear motion and non-adiabatic dynamics during the ionization process.

  19. Loudness of tone pulses in a free field

    DEFF Research Database (Denmark)

    Poulsen, Torben

    1981-01-01

    ) of about 200 ms near and at the threshold, whereas tau is about 100 ms at levels well above threshold. Discrepancies exist, nevertheless, between this single-time-constant model and the experimental data obtained for the pulses of shortest duration. To account for this, a model is proposed comprising...

  20. Nuclear forward scattering of synchrotron radiation in pulsed high magnetic fields.

    Science.gov (United States)

    Strohm, C; Van der Linden, P; Rüffer, R

    2010-02-26

    We report the demonstration of nuclear forward scattering of synchrotron radiation from 57Fe in ferromagnetic alpha iron in pulsed high magnetic fields up to 30 T. The observed magnetic hyperfine field follows the calculated high field bulk magnetization within 1%, establishing the technique as a precise tool for the study of magnetic solids in very high magnetic fields. To perform these experiments in pulsed fields, we have developed a detection scheme for fully time resolved nuclear forward scattering applicable to other pump probe experiments.

  1. Angular spectrum approach for fast simulation of pulsed non-linear ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2011-01-01

    The paper presents an Angular Spectrum Approach (ASA) for simulating pulsed non-linear ultrasound fields. The source of the ASA is generated by Field II, which can simulate array transducers of any arbitrary geometry and focusing. The non-linear ultrasound simulation program - Abersim, is used...... the fundamental and keep the second harmonic field, since Abersim simulates non-linear fields with all harmonic components. ASA and Abersim are compared for the pulsed fundamental and second harmonic fields in the time domain at depths of 30 mm, 40 mm (focal depth) and 60 mm. Full widths at -6 dB (FWHM) are f0...

  2. Effect of temperature field on solidification structure of pure Al under pulse magneto-oscillation

    Directory of Open Access Journals (Sweden)

    Li Bo

    2011-05-01

    Full Text Available This article discusses the effect of temperature field on the Pulse Magneto-Oscillation (PMO induced solidification refinement of pure aluminium to provide more information for the industrial application of the PMO solidification technology. The temperature field is altered mainly by applied variable cooling conditions and pulse parameters. Experimental results show that the refinement effect in the case of full sand mould applied is weakened with the decreasing of cooling rate, however, in the alternative case, the sand mould whose sand bottom was replaced by a graphite block is favorable to the survival of equiaxed nucleus. The refinement mechanism is discussed in terms of the relationship between temperature field and the formation process of solidified structure. The formation or survival of nucleus depends on both temperature field and Joule heat produced by PMO, both low pulse frequency and high pulse current were experimentally confirmed to be effective; and PMO was demonstrated high potential in industrial application.

  3. Amplified fragment length polymorphism and pulsed field gel electrophoresis for subspecies differentiation of Serpulina pilosicoli

    DEFF Research Database (Denmark)

    Møller, Kristian; Jensen, Tim Kåre; Boye, Mette

    1999-01-01

    Pulsed field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) were compared for their ability to differentiate between 50 porcine Serpulina pilosicoli isolates. Both techniques were highly sensitive, dividing the isolates into 36 and 38 groups, respectively. Due...

  4. Orientationally invariant metrics of apparent compartment eccentricity from double pulsed field gradient diffusion experiments

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Lundell, Henrik; Sønderby, Casper Kaae

    2013-01-01

    Pulsed field gradient diffusion sequences (PFG) with multiple diffusion encoding blocks have been indicated to offer new microstructural tissue information, such as the ability to detect nonspherical compartment shapes in macroscopically isotropic samples, i.e. samples with negligible directional...

  5. Effect of temperature field on solidification structure of pure Al under pulse magneto-oscillation

    OpenAIRE

    Li Bo; Yin Zhenxing; Gong Yongyong

    2011-01-01

    This article discusses the effect of temperature field on the Pulse Magneto-Oscillation (PMO) induced solidification refinement of pure aluminium to provide more information for the industrial application of the PMO solidification technology. The temperature field is altered mainly by applied variable cooling conditions and pulse parameters. Experimental results show that the refinement effect in the case of full sand mould applied is weakened with the decreasing of cooling rate, however, in ...

  6. Experimental studies of axial magnetic fields generated in ultrashort-pulse laser-plasma interaction

    Institute of Scientific and Technical Information of China (English)

    李玉同; 张杰; 陈黎明; 赵理曾; 夏江帆; 魏志义; 江文勉

    2000-01-01

    The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.

  7. Metamagnetic transitions of DyAg in pulsed high magnetic field

    Science.gov (United States)

    Yamagishi, A.; Yonenobu, K.; Kondo, O.; Morin, P.; Date, M.

    1990-12-01

    Metamagnetic transitions of a single crystal DyAg are investigated by using pulsed magnetic fields up to 410 kOe. Four step-magnetizations are found with the field along the [111] direction. These transitions are well understood by introducing a new model that the quadrupole order is quenched under high magnetic field.

  8. Metamagnetic transitions of DyAg in pulsed high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yamagishi, A.; Yonenobu, K.; Kondo, O.; Date, M. (Research Center for Extreme Materials, Osaka Univ. (Japan)); Morin, P. (Lab. Louis Neel, CNRS, 38 - Grenoble (France))

    1990-12-01

    Metamagnetic transitions of a single crystal DyAg are investigated by using pulsed magnetic fields up to 410 kOe. Four step-magnetizations are found with the field along the (111) direction. These transitions are well understood by introducing a new model that the quadrupole order is quenched under high magnetic field. (orig.).

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

    Science.gov (United States)

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

    2011-01-01

    Pulsed electric fields (PEF) nonthermally induce cell membrane permeabilization and thereby improve dehydration and extraction efficiencies in food plant materials. Effects of electrical field strength and number of pulses on plant tissue integrity have been studied extensively. Two previous studies on the effect of pulse frequency, however, did not provide a clear view: one study suggested no effect of frequency, while the other found a greater impact on tissue integrity at lower frequency. This study establishes the effect of pulse frequency on integrity of onion tissues. Changes in electrical characteristics, ion leakage, texture parameters, and percent weight loss were quantified for a wide range of pulse frequencies under conditions of fixed field strength and pulse number. Optical microscopy and viable-cell staining provided direct visualization of effects on individual cells. The key finding is that lower frequencies (f plant tissue. We hypothesize that cytoplasmic streaming plays a significant role in moving conductive ionic species from permeabilized cells to the intercellular space between plant cells, making subsequent pulses more efficacious at sufficiently low frequencies. The results suggest that decreasing the pulse frequency in PEF may minimize the number of pulses needed to achieve a desired amount of permeabilization, thus lowering the total energy consumption. Practical Application: PEF cause pores to be formed in plant cell membranes, thereby improve moisture removal and potential extraction of desirable components. This study used in situ microscopic evaluation of onion cells, as they were pulsed with electric fields at different frequencies, to determine whether frequency was an important parameter. We illustrate that membranes were more effectively broken at lower frequencies as compared to higher frequencies. Application of this information will allow for improved design of PEF systems for more energy efficient dehydration or extraction of

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

  12. Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in a conductor

    Directory of Open Access Journals (Sweden)

    Ilmārs Grants

    2016-06-01

    Full Text Available Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.

  13. Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in a conductor

    Science.gov (United States)

    Grants, Ilmārs; Bojarevičs, Andris; Gerbeth, Gunter

    2016-06-01

    Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.

  14. Single-shot spatiotemporal measurements of high-field terahertz pulses

    Energy Technology Data Exchange (ETDEWEB)

    van Tilborg, Jeroen; Schroeder, Carl; Toth, Csaba; Geddes, Cameron; Esarey, Eric; Leemans, Wim

    2011-06-17

    The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laser-wakefield-accelerated electron bunches, are studied. The near-single-cycle THz pulses are measured with two single-shot techniques in the temporal and spatial domains. Spectra of 0-6 THz and peak fields up to {approx_equal} 0.4 MV cm{sup -1} are observed. The measured field substructure demonstrates the manifestation of spatiotemporal coupling at focus, which affects the interpretation of THz radiation as a bunch diagnostic and in high-field pump-probe experiments.

  15. Tomographic reconstruction of transient acoustic fields recorded by pulsed TV holography.

    Science.gov (United States)

    Gren, P; Schedin, S; Li, X

    1998-02-10

    Pulsed TV holography combined with computerized tomography (CT) are used to evaluate the three-dimensional distribution of transient acoustic fields in air. Experiments are performed with an electrical discharge between two electrodes as the sound source. Holograms from several directions of the acoustic field are recorded directly onto a CCD detector by use of a double-pulsed ruby laser as the light source. Phase maps, representing projections of the acoustic field, are evaluated quantitatively from the recorded holograms. The projections are used for the CT reconstruction to evaluate the pressure-field distribution in any cross section of the measured volume of air.

  16. Improving the accuracy of pulsed field gradient NMR diffusion experiments: Correction for gradient non-uniformity

    Science.gov (United States)

    Connell, Mark A.; Bowyer, Paul J.; Adam Bone, P.; Davis, Adrian L.; Swanson, Alistair G.; Nilsson, Mathias; Morris, Gareth A.

    2009-05-01

    Pulsed field gradient NMR is a well-established technique for the determination of self-diffusion coefficients. However, a significant source of systematic error exists in the spatial variation of the applied pulsed field gradient. Non-uniform pulsed field gradients cause the decay of peak amplitudes to deviate from the expected exponential dependence on gradient squared. This has two undesirable effects: the apparent diffusion coefficient will deviate from the true value to an extent determined by the choice of experimental parameters, and the error estimated by the nonlinear least squares fitting will contain a significant systematic contribution. In particular, the apparent diffusion coefficient determined by exponential fitting of the diffusional attenuation of NMR signals will depend both on the exact pulse widths used and on the range of gradient amplitudes chosen. These problems can be partially compensated for if experimental attenuation data are fitted to a function corrected for the measured spatial dependence of the gradient and signal strength. This study describes a general alternative to existing methods for the calibration of NMR diffusion measurements. The dominant longitudinal variation of the pulsed field gradient amplitude and the signal strength are mapped by measuring pulsed field gradient echoes in the presence of a weak read gradient. These data are then used to construct a predicted signal decay function for the whole sample, which is parameterised as the exponential of a power series. Results are presented which compare diffusion coefficients obtained using the new calibration method with previous literature values.

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

    NARCIS (Netherlands)

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

    2005-01-01

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

  18. Pulsed field probe of real time magnetization dynamics in magnetic nanoparticle systems

    Science.gov (United States)

    Foulkes, T.; Syed, M.; Taplin, T.

    2015-05-01

    Magnetic nanoparticles (MNPs) are extensively used in biotechnology. These applications rely on magnetic properties that are a keen function of MNP size, distribution, and shape. Various magneto-optical techniques, including Faraday Rotation (FR), Cotton-Mouton Effect, etc., have been employed to characterize magnetic properties of MNPs. Generally, these measurements employ AC or DC fields. In this work, we describe the results from a FR setup that uses pulsed magnetic fields and an analysis technique that makes use of the entire pulse shape to investigate size distribution and shape anisotropy. The setup employs a light source, polarizing components, and a detector that are used to measure the rotation of light from a sample that is subjected to a pulsed magnetic field. This magnetic field "snapshot" is recorded alongside the intensity pulse of the sample's response. This side by side comparison yields useful information about the real time magnetization dynamics of the system being probed. The setup is highly flexible with variable control of pulse length and peak magnitude. Examining the raw data for the response of bare Fe3O4 and hybrid Au and Fe3O4 nanorods reveals interesting information about Brownian relaxation and the hydrodynamic size of these nanorods. This analysis exploits the self-referencing nature of this measurement to highlight the impact of an applied field on creating a field induced transparency for a longitudinal measurement. Possible sources for this behavior include shape anisotropy and field assisted aggregate formation.

  19. Study on technology of high-frequency pulsed magnetic field strength measurement.

    Science.gov (United States)

    Chen, Yi-Mei; Liu, Zhi-Peng; Yin, Tao

    2012-01-01

    High-frequency transient weak magnetic field is always involved in researches about biomedical engineering field while common magnetic-field sensors cannot work properly at frequencies as high as MHz. To measure the value of MHz-level weak pulsed magnetic-field strength accurately, this paper designs a measurement and calibration method for pulsed magnetic-field. In this paper, a device made of Nonferromagnetic material was independently designed and applied to pulsed magnetic field measurement. It held an accurately relative position between the magnetic field generating coil and the detecting coil. By applying a sinusoidal pulse to the generator, collecting the induced electromotive force of the detector, the final magnetic field strength was worked out through algorithms written in Matlab according to Faraday's Law. Experiments were carried out for measurement and calibration. Experiments showed that, under good stability and consistency, accurate measurement of magnetic-field strength of a sinepulse magnetic-field can be achieved, with frequency at 0.5, 1, 1.5 MHz and strength level at micro-Tesla. Calibration results carried out a measuring relative error about 2.5%.

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

    Science.gov (United States)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

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

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

    Science.gov (United States)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

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

  2. SLAB symmetric dielectric micron scale structures for high gradient electron acceleration.

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, J. B.; Schoessow, P. V.

    1999-06-12

    A class of planar microstructure is proposed which provide high accelerating gradients when excited by an infrared laser pulse. These structures consist of parallel dielectric slabs separated by a vacuum gap; the dielectric or the outer surface coating are spatially modulated at the laser wavelength along the beam direction so as to support a standing wave accelerating field. We have developed numerical and analytic models of the accelerating mode fields in the structure. We show an optimized coupling scheme such that this mode is excited resonantly with a large quality factor. The status of planned experiments on fabricating and measuring these planar structures will be described.

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

    Science.gov (United States)

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

    2016-03-01

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

  4. Effects of Pulsed Current and Pulsed Magnetic Field Complex Pretreatment on Martensite Transformation of Cr5 Steel during Continuous Cooling

    Institute of Scientific and Technical Information of China (English)

    Qing-chun LI; Li-juan LI; Guo-wei CHANG; Qi-jie ZHAI

    2015-01-01

    Carbide precipitation and martensite transformation in Cr5 steel have been observed in situ by high-temper-ature confocal laser-scanning microscopy.In this way,the influences of pulsed current and pulsed magnetic field complex pretreatment on carbide precipitation and martensite transformation during continuous cooling have been studied.The results show that the electropulsing complex pretreatment promotes the precipitation of M7 C3-type car-bides at high temperature,increases the start and finish temperatures of martensite transformation,and extends the phase transformation time.Martensite prefers to nucleate in the austenite with less precipitation of carbides due to the chemically homogeneous distribution of solute atoms.

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

    CERN Document Server

    Taya, Hidetoshi; Itakura, Kazunori

    2014-01-01

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

  6. Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

    Science.gov (United States)

    Yang, Xiaobin; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo

    2017-04-01

    A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

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

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2015-03-01

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

  8. Generation of an isolated sub-30 attosecond pulse in a two-color laser field and a static electric field

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang-Tai; Bai Ting-Ting; Zhang Mei-Guang

    2012-01-01

    We theoretically investigate high-order harmonic generation(HHG)from a helium ion model in a two-color laser field,which is synthesized by a fundamental pulse and its second harmonic pulse.It is shown that a supercontinuum spectrum can be generated in the two-color field.However,the spectral intensity is very low,limiting the application of the generated attosecond(as)pulse.By adding a static electric field to the synthesized two-color field,not only is the ionization yield of electrons contributing to the harmonic emission remarkably increased,but also the quantum paths of the HHG can be significantly modulated.As a result,the extension and enhancement of the supercontinuum spectrum are achieved,producing an intense isolated 26-as pulse with a bandwidth of about 170.5 eV.In particular,we also analyse the influence of the laser parameters on the ultrabroad supercontinuum spectrum and isolated sub-30-as pulse generation.

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

    OpenAIRE

    Salengke, dkk

    2012-01-01

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

  10. The Late Pliocene mafic lavas from the Camusú Aike volcanic field (˜50°S, Argentina): Evidence for geochemical variability in slab window magmatism

    Science.gov (United States)

    D'Orazio, M.; Innocenti, F.; Manetti, P.; Haller, M. J.; Di Vincenzo, G.; Tonarini, S.

    2005-01-01

    The Camusú Aike volcanic field (CAVF), part of the discontinuous N-S-trending belt of Cenozoic mafic lava formations that occur in a backarc position along extra-Andean Patagonia, is located in southern Patagonia (˜50°S, Santa Cruz province), approximately 70 km east of the extensive Meseta de las Vizcachas and just south of the upper Río Santa Cruz valley. The CAVF volcanics cover a surface of ˜200 km 2 and occur mainly as lava flows and scoria cones. They are subdivided into two groups: Group I volcanics are high-TiO 2, low-Mg# olivine-hypersthene-normative basalts and trachybasalts that erupted at about 2.9 Ma; Group II lavas are much less abundant, more primitive basaltic andesites that erupted at about 2.5 Ma. Both groups show a within-plate geochemical signature, though it is more marked in Group I lavas. The main geochemical characteristics, age, and location of CAVF volcanics are consistent with the slab window opening model proposed by different authors for the genesis of the Miocene-Recent mafic magmatism of Patagonia south of 46.5°S. The whole-rock geochemical and Sr-Nd isotope features of Group I lavas ( 87Sr/ 86Sr=0.7035-0.7037; 143Nd/ 144Nd=0.51288-0.51291) indicate a genetic link between these lavas and the primitive basalts in southernmost Patagonia (Pali Aike volcanic field and Estancia Glencross area), which have been interpreted as melting products of an isotopically depleted asthenosphere. The relatively evolved compositions of the erupted Group I magmas are modeled by a polybaric crystal fractionation process without significant involvement of crustal contamination. The more primitive Group II lavas are strongly depleted in incompatible elements, have slightly higher (LREE+Ba+Th+U)/HFSE ratios, and have more enriched Sr-Nd isotope compositions ( 87Sr/ 86Sr≈0.7039; 143Nd/ 144Nd≈0.51277) that are more akin to the Patagonian basalts farther to the north. The most likely explanation for the geochemical features of Group II lavas is the

  11. Switching field dependence on heating pulse duration in thermally assisted magnetic random access memories

    Energy Technology Data Exchange (ETDEWEB)

    Papusoi, C. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)], E-mail: cristian_papusoi@yahoo.com; Conraux, Y.; Prejbeanu, I.L. [Crocus Technology, 5 Robert Schumann, BP 1510, 38025 Grenoble (France); Sousa, R.; Dieny, B. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)

    2009-08-15

    The minimum applied field H{sub SW} required to reverse the magnetic moment of the ferromagnetic/antiferromagnetic storage layer of a thermally assisted magnetic random access memory (TA-MRAM) device during the application of a heating electric pulse is investigated as a function of pulse power P{sub HP} and duration {delta}. For the same power of the heating pulse P{sub HP} (or, equivalently, for the same temperature of the storage layer), H{sub SW} increases with decreasing heating time {delta}. This behavior is consistently interpreted by a thermally activated propagating domain-wall switching model, corroborated by a real-time study of switching. The increase of H{sub SW} with decreasing pulse width introduces a constraint for the minimum power consumption of a TA-MRAM where writing combines heating and magnetic field application.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  13. Modulated heat pulse propagation and partial transport barriers in chaotic magnetic fields

    CERN Document Server

    del-Castillo-Negrete, D

    2016-01-01

    Direct numerical simulations of the time dependent parallel heat transport equation modeling heat pulses driven by power modulation in 3-dimensional chaotic magnetic fields are presented. The numerical method is based on the Fourier formulation of a Lagrangian-Green's function method that provides an accurate and efficient technique for the solution of the parallel heat transport equation in the presence of harmonic power modulation. The numerical results presented provide conclusive evidence that even in the absence of magnetic flux surfaces, chaotic magnetic field configurations with intermediate levels of stochasticity exhibit transport barriers to modulated heat pulse propagation. In particular, high-order islands and remnants of destroyed flux surfaces (Cantori) act as partial barriers that slow down or even stop the propagation of heat waves at places where the magnetic field connection length exhibits a strong gradient. Results on modulated heat pulse propagation in fully stochastic fields and across m...

  14. 25 Tesla pulsed-high-magnetic-field system for soft X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, M., E-mail: mhaya@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Narumi, Y.; Nojiri, H. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Nakamura, T.; Hirono, T.; Kinoshita, T. [JASRI/SPring-8, Sayo, Hyogo 679-5198 (Japan); Kodama, K. [Department of Mechanical Engineering, Nara National College of Technology, Nara 639-1080 (Japan); Kindo, K. [Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan)

    2011-04-15

    Research highlights: {yields} We have developed a 25 T pulsed magnetic field system for soft X-ray MCD. {yields} The new capacitor bank can generate a field in the bipolar mode. {yields} We measured the Soft X-ray MCD of paramagnetic Gd{sub 2}O{sub 3} up to 25 T. - Abstract: We have developed a 25 T pulsed high magnetic field system for soft X-ray Magnetic Circular Dichroism: XMCD. The ultra-high vacuum chamber with a pulse magnet coil is installed. By using a newly developed bipolar capacitor bank, the XMCD of paramagnetic Gd{sub 2}O{sub 3} at the M{sub 5} and the M{sub 4} edges was clearly observed at low temperatures. The present system is capable of measuring XMCD of field induced moments in various compounds including paramagnets and antiferromagnets.

  15. Sub-10 nm near-field localization by plasmonic metal nanoaperture arrays with ultrashort light pulses.

    Science.gov (United States)

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2015-12-02

    Near-field localization by ultrashort femtosecond light pulses has been investigated using simple geometrical nanoapertures. The apertures employ circular, rhombic, and triangular shapes to localize the distribution of surface plasmon. To understand the geometrical effect on the localization, aperture length and period of the nanoapertures were varied. Aperture length was shown to affect the performance more than aperture period due mainly to intra-aperture coupling of near-fields. Triangular apertures provided the strongest spatial localization below 10 nm in size as well as the highest enhancement of field intensity by more than 7000 times compared to the incident light pulse. Use of ultrashort pulses was found to allow much stronger light localization than with continuous-wave light. The results can be used for super-localization sensing and imaging applications where spatially localized fields can break through the limits in achieving improved sensitivity and resolution.

  16. Nonlinear propagation of strong-field THz pulses in doped semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2012-01-01

    We report on nonlinear propagation of single-cycle THz pulses with peak electric fields reaching 300 kV/cm in n-type semiconductors at room temperature. Dramatic THz saturable absorption effects are observed in GaAs, GaP, and Ge, which are caused by the nonlinear electron transport in THz fields....

  17. Cu-Ag alloy Bitter type magnet for repeating pulsed field

    Energy Technology Data Exchange (ETDEWEB)

    Motokawa, M.; Nojiri, H.; Mitsudo, S. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research; Arai, M.; Ubukata, K.; Fujita, M.; Arakawa, T.; Inamura, Y. [Kobe Univ. (Japan). Dept. of Physics

    1996-07-01

    Cu-Ag alloy is used for the repeating pulsed field magnets. It is found that fields up to 22 T or more will be available for this purpose instead of 16 T which is obtained with normal copper magnet used at present. This result is a big advantage for neutron diffraction experiments.

  18. Photodissociation dynamics of triatomic molecule in presence of pulsed and bichromatic laser field

    Science.gov (United States)

    Ahamed Khan, Basir

    2014-04-01

    The photodissociation dynamics of a triatomic molecule in the presence of pulsed and bichromatic electric field have been investigated. We have considered MgH2 molecule in its ground state potential energy surface. The time-dependent Fourier Grid Hamiltonian method is invoked to follow the dissociation dynamics as a function of field strength, frequency, phase difference, etc.

  19. Pulse Localization and Fourier Analysis in the Mathematical Model of Acoustic Transient Field

    Directory of Open Access Journals (Sweden)

    Lukas Koudela

    2016-01-01

    Full Text Available The numerical model of a semi-cylindrical acoustic diffuser in planar transient acoustic field is discussed. The finite element method was used for the solution of the model. From the computed waveforms the straight and the reflected pulses were automatically extracted using cross-correlation. The harmonic decomposition was performed on the obtained pulses and the results were plotted in the polar pattern.

  20. Pulsed-field Gel Electrophoresis for Salmonella Infection Surveillance, Texas, USA, 2007

    Centers for Disease Control (CDC) Podcasts

    2010-06-14

    This podcast describes monitoring of the use of pulsed-field gel electrophoresis for Salmonella surveillance in Houston, Texas. CDC microbiologist Peter Gerner-Smidt discusses the importance of the PulseNet national database in surveillance of food-borne infections.  Created: 6/14/2010 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 6/14/2010.

  1. A numerical solution algorithm and its application to studies of pulsed light fields propagation

    Science.gov (United States)

    Banakh, V. A.; Gerasimova, L. O.; Smalikho, I. N.; Falits, A. V.

    2016-08-01

    A new method for studies of pulsed laser beams propagation in a turbulent atmosphere was proposed. The algorithm of numerical simulation is based on the solution of wave parabolic equation for complex spectral amplitude of wave field using method of splitting into physical factors. Examples of the use of the algorithm in the case the propagation pulsed Laguerre-Gaussian beams of femtosecond duration in the turbulence atmosphere has been shown.

  2. Molecular alignment and orientation in short pulse laser fields

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm

    1999-01-01

    An analytical expression for the propagator associated with impulsive excitation is derived based on the Magnus expansion. We apply this expression to the excitation of angular motion out of a rotational eigenstate for a linear polar molecule in a plane polarized electromagnetic field. We show...... that with properly chosen field parameters, the motion of the molecule alternates between orientations in the forward and backward hemisphere, respectively, with respect to the polarization axis of the field. (C) 1999 Elsevier Science B.V. All rights reserved....

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

    CERN Document Server

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

    2014-01-01

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

  4. Estimating of pulsed electric fields using optical measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Timothy McGuire; Chantler, Gary.

    2013-09-01

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

  5. The impacts of magnetic field on repetitive nanosecond pulsed dielectric barrier discharge in air

    Science.gov (United States)

    Liu, Yidi; Qi, Haicheng; Fan, Zhihui; Yan, Huijie; Ren, ChunSheng

    2016-11-01

    In this paper, the impacts of the parallel magnetic field on the repetitive nanosecond pulsed dielectric barrier discharge (DBD) are experimentally investigated by optical and electrical measurements. The DBD is generated between two parallel-plate electrodes in the ambient air with the stationary magnetic field on the order of 1 T. The experimental results show that additional microdischarge channels are generated and the photocurrent intensity of the plasma is increased by the magnetic field. The microdischarge channels develop along the magnetic field lines and the diffuse background emission of the discharge is stronger in the DBD with the magnetic field. As the pulse repetition frequency decreases from 1200 Hz to 100 Hz, only the photocurrent intensity of the third discharge that occurred at about 500 ns is noticeably increased by the additional magnetic field. It is believed that the enhancement of the memory effect and the confinement of the magnetic field on electrons are the main reasons.

  6. NMR in pulsed high-field magnets and application to high-T(C) superconductors.

    Science.gov (United States)

    Stork, H; Bontemps, P; Rikken, G L J A

    2013-09-01

    This article deals with the implementation of Nuclear Magnetic Resonance (NMR) experiments in pulsed magnetic fields at the pulsed-field facility of the Laboratoire National des Champs Magnétiques Intenses and its application to the high-T(C) superconductor YBa2Cu3O6.51. The experimental setup is described in detail, including a low-temperature probe head adapted for pulsed fields. An entire paragraph is dedicated to the discussion of NMR in pulsed field and the introduction of an advanced deconvolution technique making use of the induction voltage in an additional pick-up coil. The (63)Cu/(65)Cu NMR experiments on an YBa2Cu3O6.51 single crystal were performed at 2.5K during a field pulse of 46.8-T-amplitude. In the recorded spectrum the (63)Cu center line and high-frequency satellites as well as the (65)Cu center line are identified and are compared with results in literature.

  7. Sterilization of Escherichia coli cells by the application of pulsed magnetic field

    Institute of Scientific and Technical Information of China (English)

    LI Mei; QU Jiu-hui; PENG Yong-zhen

    2004-01-01

    The inactivation of microorganisms by pulsed magnetic field was studied. It was improved that theapplication of electromagnetic pulses evidently causes a lethal effect on E. coli cells suspended in phosphate buffersolution Na2 HPO4 / NaH2 PO4 (0.334/0.867 mmol/L). Experimental results indicated that the survivability( N/N0; whereN0 and N are the number of cells survived per milliliter before and after electromagnetic pulses application,respectively) of E. coli decreased with magnetic field intensity B and treatment time t. It was also found that themedium temperatures, the frequencies of pulse f, and the initial bacterial cell concentrations have determinateinfluences in destruction of E. coli cells by the application of magnetic pulses. The application of an magneticintensity B = 160 mT at pulses frequency f = 62 kHz and treatment time t = 16 h result in a considerable destructionlevels of E. coli cells ( N/N0 = 10-4 ). Possible mechanisms involved in sterilization of the magnetic field treatmentwere discussed. In order to shorten the treatment time, many groups of parallel inductive coil were used. Thepracticability test showed that the treatment time was shortened to 4 h with the application of three groups of parallelcoil when the survivability of E. coli cells was less than 0.01%; and the power consumption was about 0.2 kWh/m3 .

  8. Investigation of compression wave propagating in slab track tunnel of high-speed railway. 1st Report. Field test and one-dimensional numerical analysis; Kosoku tetsudo no slab kido tunnel nai wo denpasuru asshukuha no kaiseki. 1. Genchi sokutei to ichijigen suchi kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, T.; Iida, M.; Maeda, T. [Railway Technical Research Institute, Tokyo (Japan); Maeno, K. [Chiba University, Chiba (Japan). Faculty of Engineering; Honma, H. [Chiba University, Chiba (Japan)

    1998-05-25

    An impulsive pressure wave which is called a `micro-pressure wave` or a `tunnel sonic boom` radiating from a tunnel exit is one of the important environmental problems in high-speed railways. The strength of the impulsive wave depends on the waveform of the compression wave at the tunnel exit. In this study, the distortion of the compression wave during its propagation through the tunnel is investigated by field measurement and numerical analysis. The field measurement is conducted in the concrete slab (ballastless) track tunnel of the Shinkansen. The numerical analysis is also carried out on one-dimensional compressible flow using upwind TVD scheme. It takes account of steady and unsteady wall friction and of heat transfer to the tunnel wall. Our original numerical analysis method is based on Galilei transformation of the coordinate system moving with the compression wave. The results show that the agreement of the numerical analysis and the field measurement is good. 12 refs., 11 figs.

  9. Inverse problem of pulsed eddy current field of ferromagnetic plates

    Science.gov (United States)

    Chen, Xing-Le; Lei, Yin-Zhao

    2015-03-01

    To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters, it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate. Project supported by the National Defense Basic Technology Research Program of China (Grant No. Z132013T001).

  10. Complex envelope control of pulsed accelerating fields in superconducting cavities

    CERN Document Server

    Czarski, T

    2010-01-01

    A digital control system for superconducting cavities of a linear accelerator is presented in this work. FPGA (Field Programmable Gate Arrays) based controller, managed by MATLAB, was developed to investigate a novel firmware implementation. The LLRF - Low Level Radio Frequency system for FLASH project in DESY is introduced. Essential modeling of a cavity resonator with signal and power analysis is considered as a key approach to the control methods. An electrical model is represented by the non-stationary state space equation for the complex envelope of the cavity voltage driven by the current generator and the beam loading. The electromechanical model of the superconducting cavity resonator including the Lorentz force detuning has been developed for a simulation purpose. The digital signal processing is proposed for the field vector detection. The field vector sum control is considered for multiple cavities driven by one klystron. An algebraic, complex domain model is proposed for the system analysis. The c...

  11. Pulsed Field Magnetostriction and Metamagnetism in UPt3

    Energy Technology Data Exchange (ETDEWEB)

    Shivaram, B. [Univ. of Virginia, Charlottesville, VA (United States); Weickert, Dagmar Franziska [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jaime, Marcelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-01

    Metamagnetism (MM) characterized by a sudden rise in the magnetization at a critical field is a well established phenomenon in the hexagonal system UPt3, first noted at H = 20 T nearly three decades ago. However recent detailed measurements of the nonlinear magnetic susceptibility has raised new questions. With a careful analysis of the existing data and utilizing a phenomenological single energy scale (SES) model developed in this context one of us (BSS) was able to show that there is a distinct possibility of a second MM transition at a higher field. Depending upon the parameters chosen in the model this transition is predicted to occur in the range of 60 T-100 T. Thus measurements of the magnetic and magnetoelastic properties of UPt3 in the highest available fields is desirable.

  12. Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Seipt, Daniel

    2012-12-20

    The purpose of this thesis is to advance the understanding of strong-field QED processes in short laser pulses. The processes of non-linear one-photon and two-photon Compton scattering are studied, that is the scattering of photons in the interaction of relativistic electrons with ultra-short high-intensity laser pulses. These investigations are done in view of the present and next generation of ultra-high intensity optical lasers which are supposed to achieve unprecedented intensities of the order of 10{sup 24} W/cm{sup 2} and beyond, with pulse lengths in the order of some femtoseconds. The ultra-high laser intensity requires a non-perturbative description of the interaction of charged particles with the laser field to allow for multi-photon interactions, which is beyond the usual perturbative expansion of QED organized in powers of the fine structure constant. This is achieved in strong-field QED by employing the Furry picture and non-perturbative solutions of the Dirac equation in the presence of a background laser field as initial and final state wave functions, as well as the laser dressed Dirac-Volkov propagator. The primary objective is a realistic description of scattering processes with regard to the finite laser pulse duration beyond the common approximation of infinite plane waves, which is made necessary by the ultra-short pulse length of modern high-intensity lasers. Non-linear finite size effects are identified, which are a result of the interplay between the ultra-high intensity and the ultra-short pulse length. In particular, the frequency spectra and azimuthal photon emission spectra are studied emphasizing the differences between pulsed and infinite laser fields. The proper description of the finite temporal duration of the laser pulse leads to a regularization of unphysical infinities (due to the infinite plane-wave description) of the laser-dressed Dirac-Volkov propagator and in the second-order strong-field process of two-photon Compton

  13. Research on the Pulsed Magnetic Field Device for Sterilization of Fruit and Vegetable Equipment

    Directory of Open Access Journals (Sweden)

    Liu Mingdan

    2013-04-01

    Full Text Available In view of the requests of the sterilization device of the fruit and vegetable that integrate cleaning and juicing together, and combined with the electromagnetic theory and the cold sterilization technology which is in common use in modern food industry, circuits are designed for the pulsed magnetic field sterilization device of the integrated machine .This circuits chose a linear solenoid in which r= 30mm, l= 200 mm. The experiment shows that the pulsed magnetic field produced by the device can achieve a better effect in killing bacillus coli, beer yeast and staphylococcus aurous, etc. Compared with the traditional sterilization device, the bactericidal effect of the pulsed magnetic field sterilization device is more obvious so that it will be the direction of the development of food equipments. [1]  

  14. Interactions of Low-Frequency, Pulsed Electromagnetic Fields with Living Tissue: Biochemical Responses and Clinical Results

    DEFF Research Database (Denmark)

    Rahbek, Ulrik L.; Tritsaris, Katerina; Dissing, Steen

    2005-01-01

    In recent years many studies have demonstrated stimulatory effects of pulsed electromagnetic fields (PEMF) on biological tissue. However, controversies have also surrounded the research often due to the lack of knowledge of the different physical consequences of static versus pulsed electromagnetic...... fields. PEMF is widely used for treating fractures and non-unions as well as for treating diseases of the joints. Furthermore, new research has suggested that the technology can be used for nerve regeneration and wound healing although conclusive clinical trials, besides those for fracture healing......, are still lacking. Despite the apparent success of the PEMF technology very little is known regarding the coupling between pulsed electrical fields and biochemical events leading to cellular responses. Insight into this research area is therefore of great importance. In this review we describe the physical...

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

    Science.gov (United States)

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

    2014-10-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-15

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

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

    CERN Document Server

    Shneider, Mikhail N

    2014-01-01

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

  18. A 3He Cryostat for Scientific Measurements in Pulsed High Magnetic Fields

    Science.gov (United States)

    Wang, Shaoliang; Li, Liang; Liu, Mengyu; Zuo, Huakun; Peng, Tao

    A top loading 3He cryostat has been developed for scientific experiments with a 60 T pulsed magnetic field facility at Wuhan National High Magnetic Field Center. The cryostat consists of a 4He bath cryostat, a 3He insert and a closed circulation system for 3He gas handling. To eliminate the eddy current heating during the pulse, the tail of the 3He insert with a vacuum space at the bottom is made from fiberglass tubing coated with epoxy. The 3He bath is separated from the 4He bath with the vacuum space. The 4He bath cryostat provides cooling power to condense 3He gas by a neck tube on top of the tail. Experimental results have shown that the sample can be cooled down to 385 mK and kept cold for more than 150 second by one-shot cooling, which is sufficiently long for an experiment in a pulsed high magnetic field.

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Characterisation of practical high temperature superconductors in pulsed magnetic fields and development of associated technology

    CERN Document Server

    Saleh, P M

    2000-01-01

    including a innovative design of a 100ms pulsed magnet solenoid. Critical current measurements on state of the art practical high temperature superconductors are presented. Bi sub 2 Sr sub 2 CaCu sub 2 O silver-alloy matrix powder-in-tube and silver-alloy substrate dip-coated tapes, formed into various geometries, have been tested in pulsed magnetic fields of various pulse lengths. These measurements have been compared to tests performed in continuous magnetic fields. A distinct discrepancy between pulsed and continuous measurements has been observed in these silver-alloy, high temperature superconductor composites. The critical current measured in pulsed fields is depressed compared to those measured in continuous fields. Evidence is provided to strongly suggest that eddy current heating in the silver-alloy substrate/sheath of the conductor is responsible for this discrepancy. A model is presented to predict the temperature rise due to eddy current heating. This model shows good agreement with observations. ...

  1. Slab Leaf Bowls

    Science.gov (United States)

    Suitor, Cheryl

    2012-01-01

    In science class, fourth graders investigate the structure of plants and leaves from trees and how the process of photosynthesis turns sunlight into sugar proteins. In this article, the author fuses art and science for a creative and successful clay slab project in her elementary art classroom. (Contains 1 online resource.)

  2. Slab Leaf Bowls

    Science.gov (United States)

    Suitor, Cheryl

    2012-01-01

    In science class, fourth graders investigate the structure of plants and leaves from trees and how the process of photosynthesis turns sunlight into sugar proteins. In this article, the author fuses art and science for a creative and successful clay slab project in her elementary art classroom. (Contains 1 online resource.)

  3. Tomographic imaging of the effects of Peruvian flat slab subduction on the Nazca slab and surrounding mantle under central and southern Peru

    Science.gov (United States)

    Scire, A. C.; Zandt, G.; Beck, S. L.; Bishop, B.; Biryol, C. B.; Wagner, L. S.; Long, M. D.; Minaya, E.; Tavera, H.

    2014-12-01

    The modern central Peruvian Andes are dominated by a laterally extensive region of flat slab subduction. The Peruvian flat slab extends for ~1500 km along the strike of the Andes, correlating with the subduction of the Nazca Ridge in the south and the theorized Inca Plateau in the north. We have used data from the CAUGHT and PULSE experiments for finite frequency teleseismic P- and S-wave tomography to image the Nazca slab in the upper mantle below 95 km depth under central Peru between 10°S and 18°S as well as the surrounding mantle. Since the slab inboard of the subducting Nazca Ridge is mostly aseismic, our results provide important constraints on the geometry of the subducting Nazca slab in this region. Our images of the Nazca slab suggest that steepening of the slab inboard of the subducting Nazca Ridge locally occurs ~100 km further inland than was indicated in previous studies. The region where we have imaged the steepening of the Nazca slab inboard of the Nazca Ridge correlates with the location of the Fitzcarrald Arch, a long wavelength upper plate topographic feature which has been suggested to be a consequence of ridge subduction. When the slab steepens inboard of the flat slab region, it does so at a very steep (~70°) angle. The transition from the Peruvian flat slab to the more normally dipping slab south of 16°S below Bolivia is characterized by an abrupt bending of the slab anomaly in the mantle in response to the shift from flat to normal subduction. The slab anomaly appears to be intact south of the Nazca Ridge with no evidence for tearing of the slab in response to the abrupt change in slab dip. A potential tear in the slab is inferred from an observed offset in the slab anomaly north of the Nazca Ridge extending subparallel to the ridge axis between 130 and 300 km depth. A high amplitude (-5-6%) slow S-wave velocity anomaly is observed below the projection of the Nazca Ridge. This anomaly appears to be laterally confined to the mantle

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

    NARCIS (Netherlands)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2012-03-16

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

  6. Quantum ring states in magnetic field and delayed half-cycle pulses

    Indian Academy of Sciences (India)

    KRITI BATRA; HIRA JOSHI; VINOD PRASAD

    2016-08-01

    The present work is dedicated to the time evolution of excitation of a quantum ring in external electric and magnetic fields. Such a ring of mesoscopic dimensions in an external magnetic field is known to exhibit a wide variety of interesting physical phenomena. We have studied the dynamics of the single electron quantum ring in the presence of a static magnetic field and a combination of delayed half-cycle pulse pair. Detailed calculations have been worked out and the impact on dynamics by variation in the ring radius, intensity of external electric field, delay between the two pulses, and variation in magnetic field have been reported. A total of 19 states have been taken and the population transfer in the single electron quantum ring is studied by solving the time-dependent Schrödinger equation (TDSE), using the efficient fourth-order Runge--Kutta method. Many interesting features have been observed in the transition probabilities with the variation of magnetic field, delay between pulses and ring dimensions. A very important aspect of the present work is the persistent current generation in a quantum ring in the presence of external magnetic flux and its periodic variation with the magnetic flux, ring dimensions and pulse delay.

  7. Pulsed magnetic field excitation sensitivity of match-type electric blasting caps.

    Science.gov (United States)

    Parson, Jonathan; Dickens, James; Walter, John; Neuber, Andreas A

    2010-10-01

    This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED.

  8. A compact field-portable double-pulse laser system to enhance laser induced breakdown spectroscopy

    Science.gov (United States)

    Li, Shuo; Liu, Lei; Yan, Aidong; Huang, Sheng; Huang, Xi; Chen, Rongzhang; Lu, Yongfeng; Chen, Kevin

    2017-02-01

    This paper reports the development of a compact double-pulse laser system to enhance laser induced breakdown spectroscopy (LIBS) for field applications. Pumped by high-power vertical-surface emitting lasers, the laser system that produces 16 ns pulse at 12 mJ/pulse with total weight less than 10 kg is developed. The inter-pulse delay can be adjusted from 0 μ s with 0.5 μ s increment. Several LIBS experiments were carried out on NIST standard aluminum alloy samples. Comparing with the single-pulse LIBS, up to 9 times enhancement in atomic emission line was achieved with continuum background emission reduced by 70%. This has led to up to 10 times improvement in the limit of detection. Signal stability was also improved by 128% indicating that a more robust and accurate LIBS measurement can be achieved using a compact double-pulse laser system. This paper presents a viable and field deployable laser tool to dramatically improve the sensitivity and applicability of LIBS for a wide array of applications.

  9. Pulsed laser deposition of graphite in air and in vacuum for field emission studies

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Harshada; Singh, A.K.; Sinha, Sucharita, E-mail: ssinha@barc.gov.in

    2015-07-15

    A comparative study of pulsed laser deposition (PLD) based carbon films when deposited either, in atmospheric air, or under vacuum, has been performed. Micro-structural characterization of deposited films was carried out employing X-ray diffraction and Raman spectroscopic techniques. While, nanocrystalline graphite phase was observed in carbon films deposited in air, PLD films deposited under vacuum were largely amorphous in nature. Field emission (FE) properties of films deposited in air and under vacuum were investigated. Superior FE behavior characterized by a lower turn-on field (2.72 V/μm) and high field enhancement factor (∼2580) was observed for PLD films deposited in air. This improved field emission demonstrated by carbon films deposited via PLD in air can be attributed to presence of nanocrystalline graphite aggregates in such carbon films and local field enhancement near the sp{sup 2} sites. Our results therefore, establish PLD in air as a simple technique for deposition of carbon films having good field emission capability. - Highlights: • Pulsed laser deposition of graphite films, deposited in air and in vacuum. • Micro-structural, X-ray diffraction and micro-Raman spectroscopic characterization of deposited films. • Field emission properties of deposited films investigated. • Superior field emission behavior observed for films deposited in air than in vacuum. • Pulsed laser deposition in air leads to carbon films with excellent field emission capability.

  10. Use of a probing pulsed magnetic field for determining plasma parameters

    Science.gov (United States)

    Rousskikh, A. G.; Oreshkin, V. I.; Zhigalin, A. S.; Yushkov, G. Yu.

    2016-11-01

    A novel, simple, and readily usable method is proposed for measuring the electrical conductivity and temperature of a plasma. The method is based on the interaction of the test plasma with a pulsed magnetic field. The electric signals induced by the magnetic field in the circuits of two probes (miniature solenoids), one immersed in the test plasma and the other placed outside the plasma, provide data for estimating the plasma parameters. The method was verified experimentally by determining the parameters of the plasma flows generated in the cathode spots high-current pulsed vacuum arcs that were used to form cylindrical shells of bismuth Z-pinch plasma.

  11. Unipolar magnetic field pulses as transient signals prior to the 2009 Aquila earthquake shock

    CERN Document Server

    Nenovski, Petko

    2016-01-01

    Unipolar pre-seismic magnetic field pulses have been observed first by Bleier et al. (2009) and Villante et al. (2010) and Nenovski et al. (2013). In the present study a detailed analysis of the pulses is conducted looking for signatures of transient signals similar to that recorded at the 2009 Aquila earthquake main shock (Nenovski, 2015). Various magnetic field data around the Aquila earthquake provide an instrumental basis for such an analysis. In addition to fluxgate magnetometer data (already examined in previous studies), overhauser magnetometer data are involved. The result is a detection and discrimination of transient signals of diffusive form that appear prior to the earthquake main shock.

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

    Institute of Scientific and Technical Information of China (English)

    Lifei Wang; Guangcan Yang

    2009-01-01

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

  13. Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

    Science.gov (United States)

    Zou, Shengnan; Zermeño, Víctor M. R.; Baskys, A.; Patel, A.; Grilli, Francesco; Glowacki, B. A.

    2017-01-01

    High temperature superconducting bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electromagnetic-thermal coupled model with comprehensive temperature dependent parameters is used to simulate a stack of CCs magnetized by successive magnetic pulses. An overall picture is built to show how the trapped field and flux evolve with different pulse sequences and the evolution patterns are analyzed. Based on the discussion, an operable magnetization strategy of PFM with successive pulses is suggested to provide more trapped field and flux. Finally, experimental results of a stack of CCs magnetized by typical pulse sequences are presented for demonstration.

  14. Size separation of DNA molecules by pulsed electric field dielectrophoresis

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-08-07

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

  15. Magnetohydrodynamic Waves in an Asymmetric Magnetic Slab

    Science.gov (United States)

    Allcock, Matthew; Erdélyi, Robert

    2017-02-01

    Analytical models of solar atmospheric magnetic structures have been crucial for our understanding of magnetohydrodynamic (MHD) wave behaviour and in the development of the field of solar magneto-seismology. Here, an analytical approach is used to derive the dispersion relation for MHD waves in a magnetic slab of homogeneous plasma enclosed on its two sides by non-magnetic, semi-infinite plasma with different densities and temperatures. This generalises the classic magnetic slab model, which is symmetric about the slab. The dispersion relation, unlike that governing a symmetric slab, cannot be decoupled into the well-known sausage and kink modes, i.e. the modes have mixed properties. The eigenmodes of an asymmetric magnetic slab are better labelled as quasi-sausage and quasi-kink modes. Given that the solar atmosphere is highly inhomogeneous, this has implications for MHD mode identification in a range of solar structures. A parametric analysis of how the mode properties (in particular the phase speed, eigenfrequencies, and amplitudes) vary in terms of the introduced asymmetry is conducted. In particular, avoided crossings occur between quasi-sausage and quasi-kink surface modes, allowing modes to adopt different properties for different parameters in the external region.

  16. Nonadiabatic dynamics and multiphoton resonances in strong field molecular ionization with few cycle laser pulses

    CERN Document Server

    Tagliamonti, Vincent; Zhao, Arthur; Rozgonyi, Tamás; Marquetand, Philipp; Weinacht, Thomas

    2016-01-01

    We study strong field molecular ionization using few- (four to ten) cycle laser pulses. Employing a supercontinuum light source, we are able to tune the optical laser wavelength (photon energy) over a range of about $\\sim$200 nm (500 meV). We measure the photoelectron spectrum for a series of different molecules as a function of laser intensity, frequency, and bandwidth and illustrate how the ionization dynamics vary with these parameters. We find that multiphoton resonances and nonadiabatic dynamics (internal conversion) play an important role and result in ionization to different ionic continua. Interestingly, while nuclear dynamics can be "frozen" for sufficiently short laser pulses, we find that resonances strongly influence the photoelectron spectrum and final cationic state of the molecule regardless of pulse duration -- even for pulses that are less than four cycles in duration.

  17. Pulse width effect on the dissociation probability of CH4+ in the intense femtosecond laser field

    Institute of Scientific and Technical Information of China (English)

    WANG Gao; SONG Di; LIU Yuyan; KONG Fan'ao

    2006-01-01

    The laser pulse width effect on the dissociation probability of CH4+ irradiated by an ultrafast laser has been investigated experimentally and theoretically. The femtosecond laser at 800 nm with an intensity of 8.0 × 1013 W/cm2 was used. The observed relative yield of the primary fragment ion CH3+ increases with increasing pulse width and tends to saturate when the pulse width is longer than 120 fs. The field-assisted dissociation (FAD) model and quasi-classical trajectory (QCT) calculation were applied to predicting the dissociation probability of CH4+.The calculated probability is corrected with the molecular orientation effect and the spatial distribution of laser intensity. The modified results show that the dissociation requires at least 23 fs and saturates with long pulse widths (≥100 rs). The result is approximately consistent with the experimental observation.

  18. Nine Channel Mid-Power Bipolar Pulse Generator Based on a Field Programmable Gate Array

    CERN Document Server

    Haylock, Ben; Kasture, Sachin; Fisher, Paul; Streed, Erik W; Lobino, Mirko

    2016-01-01

    Many channel arbitrary pulse sequence generation is required for the electro-optic reconfiguration of optical waveguide networks in Lithium Niobate. Here we describe a scalable solution to the requirement for mid-power bipolar parallel outputs, based on pulse patterns generated by an externally clocked field programmable gate array (FPGA). Positive and negative pulses can be generated at repetition rates from up to 80~MHz with pulse width adjustable in increments of 1.6~ns across nine independent outputs. Each channel can provide 1.5W of RF power and it can be synchronised with the operation of other components in an optical network such as light sources and detectors through an external clock with adjustable delay.

  19. Flux motion in Y-Ba-Cu-O bulk superconductors during pulse field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizawa, K [Department of Physics, College of Humanities and Sciences, Nihon University, 3-25-40 Sakura-Josui, Setagaya-ku, Tokyo 156-8550 (Japan); Nariki, S [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Sakai, N [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Murakami, M [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Hirabayasi, I [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Takizawa, T [Department of Physics, College of Humanities and Sciences, Nihon University, 3-25-40 Sakura-Josui, Setagaya-ku, Tokyo 156-8550 (Japan)

    2004-02-01

    We have studied the relationship between the magnetization and temperature change in Y-Ba-Cu-O bulk superconductor during pulse field magnetization (PFM). The flux motion was monitored using both Hall sensors and pick-up coils that are placed on a surface of a Y-Ba-Cu-O disc having dimensions of 15 mm in diameter and 0.95 mm in thickness. The peak value of the field was varied from 0.2 to 0.8 T. The effect of the static bias field was also studied in the range of 0-3 T. The temperature of the sample surface was measured using a resistance temperature sensor. The temperature increased with the magnitude of the applied pulsed magnetic field, and the amount of temperature rise decreased with increasing static bias field.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  1. A game of RF and gradient pulses: Obtaining an efficient homogeneous flip angle with strong inhomogeneous B1 fields

    NARCIS (Netherlands)

    van Kalleveen, IML

    2016-01-01

    Adiabatic RF pulses are useful pulses for inhomogeneous B1 fields caused by surface RF coils, however the increase in SAR will lengthen the TR, and possibly also the TE if the adiabatic pulses become too long. Using the superadiabaticity theorem the increase in SAR can already be reduced, making it

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

    Science.gov (United States)

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

    2013-06-01

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

  3. An Optimization of Pulsed ElectroMagnetic Fields Study

    Science.gov (United States)

    Goodwin, Thomas J.

    2006-01-01

    To date, in our research we have focused on the use of normal human neuronal progenitor (NHNP) cells because of their importance in human nervous system regeneration, development and maintenance, but we have developed 2-D and 3-D bioreactors that can accommodate any cell line. In this Project, we will include the use of tissues important for physiological regeneration: Human osteoblasts or chondrocytes, and vascular cells. Our initial results with the NHNP cells were quite startling using extremely low-level electromagnetic fields (5 microtesla at 10Hz; 6mA). The low-amplitude, rapidly time-varying electromagnetic fields exert a very potent effect on the proliferation, morphology, and gene expression of the cells in culture, both in standard 2-dimensional culture plates as well as cells organized into 3-dimensional tissue-like assemblies (TLAs) in a 3D bioreactor. We have replicated our preliminary results many, many times, have analyzed the gene expression using gene arrays (followed by Luminex analysis for protein production), and have monitored cell proliferation, orientation, morphology, and glucose metabolism, and we are confident that we have a stable and reliable model to study the control of high-level cellular processes by application of low-amplitude, time varying electromagnetic fields (TVEMF) (1, 2). In additional studies at the University of Michigan, we have been able to generate functional in vitro engineered mammalian skeletal muscle, and have employed nerve-muscle co-culture techniques to promote axonal sprouting. We believe that nearly all tissues, in particular, neural, are susceptible to the influences of low-level TVEMF.

  4. Field trial of a pulsed limestone diversion well

    Science.gov (United States)

    Sibrell, Philip L.; Denholm, C.; Dunn, Margaret

    2013-01-01

    The use of limestone diversion wells to treat acid mine drainage (AMD) is well-known, but in many cases, acid neutralization is not as complete as would be desired. Reasons for this include channeling of the water through the limestone bed, and the slow reaction rate of the limestone gravel. A new approach to improve the performance of the diversion well was tested in the field at the Jennings Environmental Education Center, near Slippery Rock, PA. In this approach, a finer size distribution of limestone was used so as to allow fluidization of the limestone bed, thus eliminating channeling and increasing particle surface area for faster reaction rates. Also, water flow was regulated through the use of a dosing siphon, so that consistent fluidization of the limestone sand could be achieved. Testing began late in the summer of 2010, and continued through November of 2011. Initial system performance during the 2010 field season was good, with the production of net alkaline water, but hydraulic problems involving air release and limestone sand retention were observed. In the summer of 2011, a finer size of limestone sand was procured for use in the system. This material fluidized more readily, but acid neutralization tapered off after several days. Subsequent observations indicated that the hydraulics of the system was compromised by the formation of iron oxides in the pipe leading to the limestone bed, which affected water distribution and flow through the bed. Although results from the field trial were mixed, it is believed that without the formation of iron oxides and plugging of the pipe, better acid neutralization and treatment would have occurred. Further tests are being considered using a different hydraulic configuration for the limestone sand fluidized bed.

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

    Science.gov (United States)

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

    2016-08-01

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

  6. Pulsed mixed n, {gamma} radiation fields for electronic testing

    Energy Technology Data Exchange (ETDEWEB)

    Nurdin, G.; Becret, C.; Jaureguy, J.C. [Etablissement Technique Central de l`Armement (ETCA), 94 - Arcueil (France); Vie, M.; Baboulet, J.P.; Lapeyre, P.; Ramisse, D. [D.G.A., 46 - Gramat (France)

    1994-12-31

    For combined n, {gamma} TREE testing we have modified the CALIBAN Fast Burst Reactor Field with CdO/Epoxy converters to cover the range [10{sup 11} -10{sup 12}] n.cm{sup -2} (1 MeV Si), [10{sup 7} - 10{sup 8}] cGy(Si).s{sup -1}. Activation and fission {sigma} {phi}vector, 1 MeV(Si) fluences, neutron spectra, total exposures and dose rates were predicted with good agreement by n, {gamma} photon transport codes. (author). 12 refs., 2 figs., 1 tab.

  7. Cavitation in dielectric fluid in inhomogeneous pulsed electric field

    CERN Document Server

    Shneider, M N

    2013-01-01

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

  8. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    Science.gov (United States)

    Sajadi, Mohsen; Wolf, Martin; Kampfrath, Tobias

    2014-03-01

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ˜1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  9. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sajadi, Mohsen, E-mail: sajadi@fhi-berlin.mpg.de; Wolf, Martin; Kampfrath, Tobias [Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2014-03-03

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ∼1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  10. Simulation and experiments of Stacks of High Temperature Superconducting Coated Conductors Magnetized by Pulsed Field Magnetization with Multi-Pulse Technique

    CERN Document Server

    Zou, Shengnan; Baskys, A; Patel, A; Grilli, Francesco; Glowacki, B A

    2016-01-01

    High temperature superconducting (HTS) bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (<2 T), so they show potential for improving the performance of many electrical applications that use permanent magnets like rotating machines. Towards practical or commercial use of TFMs, effective in situ magnetization is one of the key issues. The pulsed field magnetization (PFM) is among the most promising magnetization methods in virtue of its compactness, mobility and low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electrom...

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

    Science.gov (United States)

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

    2012-02-01

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

  12. A high-field pulsed magnet system for x-ray scattering studies in Voigt geometry

    CERN Document Server

    Islam, Zahirul; Ruff, Jacob P C; Das, Ritesh K; Trakhtenberg, Emil; Nojiri, Hiroyuki; Narumi, Yasuo; Canfield, Paul C

    2011-01-01

    We present a new pulsed-magnet system that enables x-ray single-crystal diffraction in addition to powder and spectroscopic studies in Voigt geometry. The apparatus consists of a large-bore solenoid, cooled by liquid nitrogen. A second independent closed-cycle cryostat is used for cooling samples near liquid helium temperatures. Pulsed magnetic fields up to ~30 T with a minimum of ~6 ms in total duration are generated by discharging a 40 kJ capacitor bank into the magnet coil. The unique characteristic of this instrument is the preservation of maximum scattering angle (~23.6 deg.) through the magnet bore by virtue of a novel double-funnel insert. This instrument would facilitate x-ray diffraction and spectroscopic studies that are impractical, if not impossible, to perform using conventional split-pair magnets and offers a practical solution for preserving optical access in future higher-field pulsed magnets.

  13. Pulsed high field magnets. An efficient way of shaping laser accelerated proton beams for application

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Florian; Schramm, Ulrich [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany); Technische Universitaet Dresden, 01062 Dresden (Germany); Bagnoud, Vincent; Blazevic, Abel; Busold, Simon [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Helmholtz Institut Jena, 07734 Jena (Germany); Brabetz, Christian; Schumacher, Dennis [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Deppert, Oliver; Jahn, Diana; Roth, Markus [Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Karsch, Leonhard; Masood, Umar [OncoRay-National Center for Radiation Research in Oncology, TU Dresden, 01307 Dresden (Germany); Kraft, Stephan [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany)

    2015-07-01

    Compact laser-driven proton accelerators are a potential alternative to complex, expensive conventional accelerators, enabling unique beam properties, like ultra-high pulse dose. Nevertheless, they still require substantial development in reliable beam generation and transport. We present experimental studies on capture, shape and transport of laser and conventionally accelerated protons via pulsed high-field magnets. These magnets, common research tools in the fields of solid state physics, have been adapted to meet the demands of laser acceleration experiments.Our work distinctively shows that pulsed magnet technology makes laser acceleration more suitable for application and can facilitate compact and efficient accelerators, e.g. for material research as well as medical and biological purposes.

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

    Science.gov (United States)

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

    2015-06-01

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

  15. Ultra-fast ballistic magnetization reversal triggered by a single magnetic field pulse

    Energy Technology Data Exchange (ETDEWEB)

    Horley, Paul P; Gonzalez Hernandez, Jesus [Centro de Investigacion en Materiales Avanzados S.C., Chihuahua/Monterrey, Av. Miguel de Cervantes 120, 31109 Chihuahua, Chihuahua (Mexico); Vieira, Vitor R; Dugaev, Vitalii K [Centro de Fisica das Interaccoes Fundamentais, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Gorley, Peter [Department of Physics, Yuri Fedkovych Chernivtsi National University, 2 Kotsyubynsky Street, 58012 Chernivtsi (Ukraine); Barnas, Jozef, E-mail: paul.horley@cimav.edu.m [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznan (Poland)

    2009-12-21

    Performance of devices such as magnetic random access memories crucially depends on magnetic switching time. By numerical simulations we show that ultra-fast (in the sub-nanosecond range) magnetic reversal in nanoparticles can be achieved with a single pulse of magnetic field oriented at some specific angles with respect to the magnetic moment. These angles form the areas of ballistic reversal (with no magnetization ringing). We show that the size of these areas increases with decreasing pulse duration, which allows reaching of the sub-nanosecond reversal for a pulse duration of the order of dozen(s) of ps. When changing the magnetic field, the areas of ballistic reversal move along the equator of the unitary sphere, and eventually merge with each other. For appropriate choice of the azimuthal angle, one can reach magnetic reversal along a trajectory located in or out of the easy plane.

  16. Strong-field ionization inducing multi-electron-hole coherence probed by attosecond pulses

    CERN Document Server

    Zhao, Jing; Zhao, Zengxiu

    2015-01-01

    We propose a new scenario to apply IR-pump-XUV-probe schemes to resolving strong field ionization induced and attosecond pulse driven electron-hole dynamics and coherence in real time. The coherent driving of both the infrared laser and the attoscond pulse correlates the dynamics of the core-hole and the valence-hole which leads to the otherwise forbidden absorption and emission of XUV photon. An analytical model is developed based on the strong-field approximation by taking into account of the essential multielectron configurations. The emission spectra from the core-valence transition and the core-hole recombination are found modulating strongly as functions of the time delay between the two pulses, which provides a unique insight into the instantaneous ionization and the interplay of the multi-electron-hole coherence.

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

    Science.gov (United States)

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-04-01

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

  18. All-optical control of unipolar pulse generation in spatially extended arrays of optical oscillators with nonlinear field coupling

    CERN Document Server

    Pakhomov, A V; Babushkin, I V; Arkhipov, M V; Tolmachev, Yu A; Rosanov, N N

    2016-01-01

    We study the optical response of a resonant medium possessing the nonlinear coupling to external field under excitation by few-cycle pump pulses. A theoretical approach is developed, allowing to analyze unipolar half-cycle pulse generation in such a geometry. Our approach is applicable for the arbitrary coupling functions as well as arbitrarily curved pump pulse wavefronts and defines a general framework to produce unipolar pulses of desired form.

  19. Improved convection compensating pulsed field gradient spin-echo and stimulated-echo methods.

    Science.gov (United States)

    Sørland, G H; Seland, J G; Krane, J; Anthonsen, H W

    2000-02-01

    The need for convection compensating methods in NMR has been manifested through an increasing number of publications related to the subject over the past few years (J. Magn. Reson. 125, 372 (1997); 132, 13 (1998); 131, 126 (1998); 118, 50 (1996); 133, 379 (1998)). When performing measurements at elevated temperature, small convection currents may give rise to erroneous values of the diffusion coefficient. In work with high resolution NMR spectroscopy, the application of magnetic field gradients also introduces an eddy-current magnetic field which may result in errors in phase and baseline in the FFT-spectra. The eddy current field has been greatly suppressed by the application of bipolar magnetic field gradients. However, when introducing bipolar magnetic field gradients, the pulse sequence is lengthened significantly. This has recently been pointed out as a major drawback because of the loss of coherence and of NMR-signal due to transverse relaxation processes. Here we present modified convection compensating pulsed field gradient double spin echo and double stimulated echo sequences which suppress the eddy-current magnetic field without increasing the duration of the pulse sequences.

  20. Evaluation and interpretation of bubble size distributions in pulsed megasonic fields

    Science.gov (United States)

    Hauptmann, M.; Struyf, H.; De Gendt, S.; Glorieux, C.; Brems, S.

    2013-05-01

    The occurrence of acoustic cavitation is incorporating a multitude of interdependent effects that strongly depend on the bubble size. Therefore, bubble size control would be beneficial for biological and industrial processes that rely on acoustic cavitation. A pulsed acoustic field can result in bubble size control and the repeated dissolution and reactivation ("recycling") of potentially active bubbles. As a consequence, a pulsed field can strongly enhance cavitation activity. In this paper, we present a modified methodology for the evaluation of the active bubble size distribution by means of a combination of cavitation noise measurements and ultrasonic pulsing. The key component of this modified methodology is the definition of an upper size limit, below which bubbles—in between subsequent pulses—have to dissolve, in order to be sustainably recycled. This upper limit makes it possible to explain and link the enhancement of cavitation activity to a bubble size distribution. The experimentally determined bubble size distributions for different power densities are interpreted in the frame of numerical calculations of the oscillatory responses of the bubbles to the intermittent driving sound field. The distributions are found to be shaped by the size dependent interplay between bubble pulsations, rectified diffusion, coalescence, and the development of parametrically amplified shape instabilities. Also, a phenomenological reactivation-deactivation model is proposed to explain and quantify the observed enhancement of cavitation activity under pulsed, with respect to continuous sonication. In this model, the pulse-duration determines the magnitude of the reactivation of partially dissolved bubbles and the deactivation of activated bubbles by coalescence. It is shown that the subsequent recycling of previously active bubbles leads to an accumulation of cavitation activity, which saturates after a certain number of pulses. The model is fitted to the experimental

  1. Isolated attosecond pulses generation from coherent superposition state of helium ion in static electric fields and spatial nonhomogeneous fields

    Science.gov (United States)

    Liu, Hao; Zhang, Zhengzhong; Wu, Yangjiang; Jiang, Shicheng; Yu, Chao

    2016-09-01

    We present a systematic study of high-order harmonic generation (HHG) from helium ion with the initial state prepared as a coherent superposition of electronic ground state and an excited state. As a result, the conversion efficiency of the harmonic spectrum is significantly enhanced. When we add a static electric field in fundamental field, the supercontinuum region of the harmonic spectrum is distinctly extended and an isolated 100 as pulse can be generated. Moreover, we use a spatial nonhomogeneous field to increase the cutoff energy in high-order harmonic generation spectrum, which can be extended to about 700 eV, and an isolated 50 as pulse can be obtained directly by the superposition of the supercontinuum harmonics.

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2015-07-01

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  5. Microstructure refinement of AZ91D alloy solidified with pulsed magnetic field

    Institute of Scientific and Technical Information of China (English)

    WANG Bin; YANG Yuan-sheng; ZHOU Ji-xue; TONG Wen-hui

    2008-01-01

    The effects of pulsed magnetic field on the solidified microstructure of an AZ91D magnesium alloy were investigated. The experimental results show that the remarkable microstructural refinement is achieved when the pulsed magnetic field is applied in the solidification of AZ91D alloy. The average grain size of the as-cast microstructure of AZ91D alloy is refined to 104μm. Besides the grain refinement, the morphology of the primary α-Mg is changed from dendritic to rosette, then to globular shape with changing the parameters of the pulsed magnetic field. The pulsed magnetic field causes melt convection during solidification, which makes the temperature of the whole melt homogenized, and produces an undercooling zone in front of the liquid/solid interface by the magnetic pressure, which makes the nucleation rate increased and big dendrites prohibited. In addition, primary α-Mg dendrites break into fine crystals, resulting in a refined solidification structure of the AZ91D alloy. The Joule heat effect induced in the melt also strengthens the grain refinement effect and spheroidization of dendrite arms.

  6. Transcranial low voltage pulsed electromagnetic fields in patients with treatment-resistant depression

    DEFF Research Database (Denmark)

    Martiny, Klaus Per Juul; Lunde, Marianne; Bech, Per

    2010-01-01

    of a new principle using low-intensity transcranially applied pulsed electromagnetic fields (T-PEMF) in combination with antidepressants in patients with treatment-resistant depression. METHODS: This was a sham-controlled double-blind study comparing 5 weeks of active or sham T-PEMF in patients...

  7. Comparison of restriction enzymes for pulsed-field gel electrophoresis typing of Moraxella catarrhalis.

    Science.gov (United States)

    Marti, Sara; Puig, Carmen; Domenech, Arnau; Liñares, Josefina; Ardanuy, Carmen

    2013-07-01

    NotI, the most prevalent restriction enzyme used for typing Moraxella catarrhalis, failed to digest genomic DNA from respiratory samples. An improved pulsed-field gel electrophoresis (PFGE) methodology determined SpeI as the best choice for typing this bacterial species, with a good restriction of clinical samples and a good clustering correlation with NotI.

  8. Trial Application of Pulse-Field Magnetization to Magnetically Levitated Conveyor System

    Directory of Open Access Journals (Sweden)

    Yoshihito Miyatake

    2012-01-01

    Full Text Available Magnetically levitated conveyor system using superconductors is discussed. The system is composed of a levitated conveyor, magnetic rails, a linear induction motor, and some power supplies. In the paper, pulse-field magnetization is applied to the system. Then, the levitation height and the dynamics of the conveyor are controlled. The static and dynamic characteristics of the levitated conveyor are discussed.

  9. Spin-orbit interaction in chiral carbon nanotubes probed in pulsed magnetic fields

    NARCIS (Netherlands)

    Jhang, S.H.; Marganska, M.; Skourski, Y.; Preusche, D.; Witkamp, B.; Grifoni, M.; Van der Zant, H.; Wosnitza, J.; Strunk, C.

    2010-01-01

    The magnetoconductance of an open carbon nanotube (CNT)-quantum wire was measured in pulsed magnetic fields. At low temperatures, we find a peculiar split magnetoconductance peak close to the chargeneutrality point. Our analysis of the data reveals that this splitting is intimately connected to the

  10. REMANENCE MEASUREMENTS ON INDIVIDUAL MAGNETOTACTIC BACTERIA USING A PULSED MAGNETIC-FIELD

    NARCIS (Netherlands)

    PENNINGA, Ietje; Waard , de Hendrik; MOSKOWITZ, BM; BAZYLINSKI, DA; FRANKEL, RB

    1995-01-01

    We describe pulsed-magnetic-field remanence measurements of individual, killed, undisrupted cells of three different types of magnetotactic bacteria. The measurement technique involved the observation of aligned, individual magnetotactic bacteria with a light microscope as they were subjected to mag

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  13. [Effect of pulsed electromagnetic field on orthodontic tooth movement through transmission electromicroscopy].

    Science.gov (United States)

    Chen, Q

    1991-01-01

    This experiment is to observe the effect of pulsed electromagnetic field (PEMF) on orthodontic tooth movement of guinea pigs through transmission electron microscope (TEM). 14-days observations indicate that PEMF could accelerate the rate of orthodontic tooth movement as a result of the increase in quantity of active cell without changing the ultrastructures of cells and have no unfavorable effects on periodontal tissues.

  14. Field and laboratory simulations of storm water pulses: Behavioural avoidance by marine epifauna

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, David A. [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052 (Australia)], E-mail: d.roberts@student.unsw.edu.au; Johnston, Emma L.; Mueller, Stefanie; Poore, Alistair G.B. [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052 (Australia)

    2008-03-15

    Epifaunal communities associated with macroalgae were exposed to storm water pulses using a custom made irrigation system. Treatments included Millipore freshwater, freshwater spiked with trace metals and seawater controls to allow for the relative importance of freshwater inundation, trace metals and increased flow to be determined. Experimental pulses created conditions similar to those that occur following real storm water events. Brief storm water pulses reduced the abundance of amphipods and gastropods. Freshwater was the causative agent as there were no additional effects of trace metals on the assemblages. Laboratory assays indicated that neither direct nor latent mortality was likely following experimental pulses and that epifauna readily avoid storm water. Indirect effects upon epifauna through salinity-induced changes to algal habitats were not found in field recolonisation experiments. Results demonstrate the importance of examining the effects of pulsed contaminants under realistic exposure conditions and the need to consider ecologically relevant endpoints. - Brief storm water pulses trigger avoidance response in mobile epifauna due to the inundation of freshwater.

  15. Numerical simulation of temperature field in K9 glass irradiated by ultraviolet pulse laser

    Science.gov (United States)

    Wang, Xi; Fang, Xiaodong

    2015-10-01

    The optical component of photoelectric system was easy to be damaged by irradiation of high power pulse laser, so the effect of high power pulse laser irradiation on K9 glass was researched. A thermodynamic model of K9 glass irradiated by ultraviolet pulse laser was established using the finite element software ANSYS. The article analyzed some key problems in simulation process of ultraviolet pulse laser damage of K9 glass based on ANSYS from the finite element models foundation, meshing, loading of pulse laser, setting initial conditions and boundary conditions and setting the thermal physical parameters of material. The finite element method (FEM) model was established and a numerical analysis was performed to calculate temperature field in K9 glass irradiated by ultraviolet pulse laser. The simulation results showed that the temperature of irradiation area exceeded the melting point of K9 glass, while the incident laser energy was low. The thermal damage dominated in the damage mechanism of K9 glass, the melting phenomenon should be much more distinct.

  16. Coherent addition of gratings for chirped-pulse-amplified lasers based on near-field and far-field measurements

    Institute of Scientific and Technical Information of China (English)

    Yuchuan Yang; Hui Luo; Xiao Wang; Fuquan Li; Xiaojun Huang; Bin Feng; Feng Jing

    2011-01-01

    @@ The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers.Almost all systems have adopted a tiled-grating approach to meet the size require-ments for the compression gratings.We present a computer-control test system utilizing near-field interfer-ence and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT)of the individual inteiference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference.Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.%The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers. Almost all systems have adopted a tiled-grating approach to meet the size requirements for the compression gratings. We present a computer-control test system utilizing near-field interference and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT)of the individual inter ference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference. Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.

  17. Charge and spin current oscillations in a tunnel junction induced by magnetic field pulses

    Science.gov (United States)

    Dartora, C. A.; Nobrega, K. Z.; Cabrera, G. G.

    2016-08-01

    Usually, charge and spin transport properties in tunnel junctions are studied in the DC bias regime and/or in the adiabatic regime of time-varying magnetic fields. In this letter, the temporal dynamics of charge and spin currents in a tunnel junction induced by pulsed magnetic fields is considered. At low bias voltages, energy and momentum of the conduction electrons are nearly conserved in the tunneling process, leading to the description of the junction as a spin-1/2 fermionic system coupled to time-varying magnetic fields. Under the influence of pulsed magnetic fields, charge and spin current can flow across the tunnel junction, displaying oscillatory behavior, even in the absence of DC bias voltage. A type of spin capacitance function, in close analogy to electric capacitance, is predicted.

  18. Carrier field shock formation of long wavelength femtosecond pulses in dispersive media

    CERN Document Server

    Panagiotopoulos, Paris; Kolesik, Miroslav; Moloney, Jerome V

    2015-01-01

    We numerically demonstrate the formation of carrier field shocks in various dispersive media for a wide variety of input conditions using two different electric field propagation models. In addition, an investigation of the impact of numerous physical effects on carrier wave shock is performed. It is shown that in many cases a field shock is essentially unavoidable and therefore extremely important in the propagation of intense long wavelength pulses in weakly dispersive nonlinear media such as noble gases, air, and single-crystal diamond. The results presented here are expected to have a significant impact in the field of ultrashort nonlinear optics, attosecond pulse generation, and wavepacket synthesis where the use of mid-IR wavelengths is becoming increasingly more important.

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ingrid Aguiló-Aguayo

    2015-03-01

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

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

    Science.gov (United States)

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

    2015-03-02

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

  2. Compact short-pulse laser for near-field range-gated imaging

    Science.gov (United States)

    Zutavern, Fred J.; Helgeson, Wesley D.; Loubriel, Guillermo M.; Yates, George J.; Gallegos, Robert A.; McDonald, Thomas E., Jr.

    1997-05-01

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 100 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight, System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory and high gain, PCSS-driven LDAs developed at Sandia National Laboratories. The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

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

    Science.gov (United States)

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

    2014-03-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-29

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

  6. Selective Strong-Field Enhancement and Suppression of Ionization with Short Laser Pulses

    CERN Document Server

    Hart, Nathan A; Kolomenskii, Alexandre A; Paulus, Gerhard G; Bauer, Dieter; Schuessler, Hans A

    2015-01-01

    We experimentally demonstrate robust selective excitation and attenuation of atomic Rydberg level populations in sodium vapor (Na I) using intense laser pulses in the strong field limit ($> 10^{12} W/cm^{2}$). The coherent control of the atomic population and related ionization channels is realized for intensities above the over-the-barrier ionization intensity. A qualitative model predicts that this strong field coherent control arises through the manifestation of a Freeman resonance.

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

    OpenAIRE

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  9. Development of a 50-T pulsed magnetic field facility by using an 1.5-MJ capacitor bank

    Science.gov (United States)

    Shin, Y. H.; Kim, Yongmin

    2015-09-01

    Because DC magnets consume a huge amount of electricity (resistive DC magnet) or liquid helium (superconducting magnet), a capacitor-bank-driven pulsed magnet is known to be a cost-effective way of generating high magnetic fields. This type of pulsed magnet is normally operated at liquid nitrogen temperature and consumes little electric power to generate over 50 tesla (T) during a short transient time of less than 50 millisecond (ms). With modern fast data acquisition systems, almost all kinds of physical quantities, such as photoluminescence, magnetization or resistance can be measured during a short magnetic field pulse. We report a recently home-built capacitor-bankdriven pulsed magnetic field facility, in which a capacitor bank of 1.5-MJ maximum stored energy is utilized to generate pulsed magnetic fields up to 50 T with transient pulse time of 22 ms.

  10. Generation of isolated attosecond extreme ultraviolet pulses employing nanoplasmonic field enhancement: optimization of coupled ellipsoids

    Energy Technology Data Exchange (ETDEWEB)

    Stebbings, S L; Suessmann, F; Yang, Y-Y; Kling, M F [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strass e 1, 85748 Garching (Germany); Scrinzi, A [Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, 80333 Muenchen (Germany); Durach, M; Rusina, A; Stockman, M I, E-mail: sarah.stebbings@mpq.mpg.de, E-mail: mstockman@gsu.edu, E-mail: matthias.kling@mpq.mpg.de [Department of Physics and Astronomy, Georgia State University, 29 Peachtree Center Avenue, Atlanta, GA 30303 (United States)

    2011-07-15

    The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schroedinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.

  11. Generation of isolated attosecond extreme ultraviolet pulses employing nanoplasmonic field enhancement: optimization of coupled ellipsoids

    Science.gov (United States)

    Stebbings, S. L.; Süßmann, F.; Yang, Y.-Y.; Scrinzi, A.; Durach, M.; Rusina, A.; Stockman, M. I.; Kling, M. F.

    2011-07-01

    The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schrödinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.

  12. Effects of Pulsed Electromagnetic Field on Differentiation of HUES-17 Human Embryonic Stem Cell Line

    Directory of Open Access Journals (Sweden)

    Yi-Lin Wu

    2014-08-01

    Full Text Available Electromagnetic fields are considered to potentially affect embryonic development, but the mechanism is still unknown. In this study, human embryonic stem cell (hESC line HUES-17 was applied to explore the mechanism of exposure on embryonic development to pulsed electromagnetic field (PEMF for 400 pulses at different electric field intensities and the differentiation of HUES-17 cells was observed after PEMF exposure. The expression of alkaline phosphatase (AP, stage-specific embryonic antigen-3 (SSEA-3, SSEA-4 and the mRNA level and protein level of Oct4, Sox2 and Nanog in HUES-17 cells remained unchanged after PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m. Four hundred pulses PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m did not affect the differentiation of HUES-17 cells. The reason why electromagnetic fields affect embryonic development may be due to other mechanisms rather than affecting the differentiation of embryonic stem cells.

  13. High-Order Temporal Corrected Fields of Ultra-Short Laser Pulses and Laser-Driven Acceleration

    Institute of Scientific and Technical Information of China (English)

    XIE Yong-Jie; HUO Yu-Kun; KONG Qing; WANG Ping-Xiao; CHEN Zhao; LIU Jing-Ru

    2006-01-01

    @@ Up to third-order temporal correction in terms of a small dimensionless temporal parameter ε = 1/(ω0t0) (ω0 =ck0 the central oscillatory frequency, t0 the pulse duration of half period), the field expressions of ultra-short focused laser pulses are explicitly presented. To evaluate the correction efficacy, electric amplitudes of zeroth-order and higher-order corrected fields are compared for different pulse durations. Furthermore, electron interaction with ultra-short laser pulses is simulated using both the zeroth-order and higher-order corrected field equations.

  14. Optical field ionization of atoms and ions using ultrashort laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Fittinghoff, D.N.

    1993-12-01

    This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He{sup +2}, Ne{sup +2} and Ar{sup +2}. The ion yields for He{sup +l}, Ne{sup +l} and Ar{sup +l} agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of the ionization indicates that the enhancements are consistent with a nonsequential ionization mechanism in which the linearly polarized field drives the electron wavefunction back toward the ion core and causes double ionization through inelastic e-2e scattering. These investigations have initiated a number of other studies by other groups and are of current scientific interest in the fields of high-irradiance laser-matter interactions and production of high-density plasmas. This work involved: (1) Understanding the characteristic nature of the ion yields produced by tunneling ionization through investigation of analytic solutions for tunneling at optical frequencies. (2) Extensive characterization of the pulses produced by 614-nm and 800-ran ultrashort pulse lasers. Absolute calibration of the irradiance scale produced shows the practicality of the inverse problem--measuring peak laser irradiance using ion yields. (3) Measuring the ion yields for three noble gases using linear, circular and elliptical polarizations of laser pulses at 614-nm and 800-nm. The measurements are some of the first measurements for pulse widths as low as 120-fs.

  15. Interaction of an ion bunch with a plasma slab

    Energy Technology Data Exchange (ETDEWEB)

    Krasovitskiy, V. B., E-mail: krasovit@mail.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Turikov, V. A. [Peoples’ Friendship University of Russia (Russian Federation)

    2016-11-15

    Charge neutralization of a short ion bunch passing through a plasma slab is studied by means of numerical simulation. It is shown that a fraction of plasma electrons are trapped by the bunch under the action of the collective charge separation field. The accelerated electrons generated in this process excite beam−plasma instability, thereby violating the trapping conditions. The process of electron trapping is also strongly affected by the high-frequency electric field caused by plasma oscillations at the slab boundaries. It is examined how the degree of charge neutralization depends on the parameters of the bunch and plasma slab.

  16. Electromagnetic Tunneling and Resonances in Pseudochiral Omega Slabs

    Science.gov (United States)

    Razzaz, Faroq; Alkanhal, Majeed A. S.

    2017-01-01

    This paper presents theoretical investigation of the electromagnetic wave tunneling and anomalous transmission around the trapped modes in a pseudochiral omega slab. The dispersion relation, the conditions of the trapped modes, and the evanescent wave coupling and tunneling in two different reciprocal pseudochiral omega slab structures are derived. The Berreman’s matrix method is applied to obtain the transmission coefficients across the pseudochiral omega slab. When the structure is perturbed, a resonance phenomenon is detected around the trapped modes. This resonance results in transmission anomalies (total transmission and total reflection) and dramatic field amplifications around the trapped modes. The number of the discrete trapped modes and then the resonance frequencies are prescribed by the parameters of the pseudochiral omega slab such as the value of the omega parameter and its orientation and the slab thickness. PMID:28165058

  17. Electromagnetic Tunneling and Resonances in Pseudochiral Omega Slabs.

    Science.gov (United States)

    Razzaz, Faroq; Alkanhal, Majeed A S

    2017-02-06

    This paper presents theoretical investigation of the electromagnetic wave tunneling and anomalous transmission around the trapped modes in a pseudochiral omega slab. The dispersion relation, the conditions of the trapped modes, and the evanescent wave coupling and tunneling in two different reciprocal pseudochiral omega slab structures are derived. The Berreman's matrix method is applied to obtain the transmission coefficients across the pseudochiral omega slab. When the structure is perturbed, a resonance phenomenon is detected around the trapped modes. This resonance results in transmission anomalies (total transmission and total reflection) and dramatic field amplifications around the trapped modes. The number of the discrete trapped modes and then the resonance frequencies are prescribed by the parameters of the pseudochiral omega slab such as the value of the omega parameter and its orientation and the slab thickness.

  18. Amp\\`ere-Class Pulsed Field Emission from Carbon-Nanotube Cathodes in a Radiofrequency Resonator

    CERN Document Server

    Mihalcea, D; Hartzell, J; Panuganti, H; Boucher, S M; Murokh, A; Piot, P; Thangaraj, J C T

    2015-01-01

    Pulsed field emission from cold carbon-nanotube cathodes placed in a radiofrequency resonant cavity was observed. The cathodes were located on the backplate of a conventional $1+\\frac{1}{2}$-cell resonant cavity operating at 1.3-GHz and resulted in the production of bunch train with maximum average current close to 0.7 Amp\\`ere. The measured Fowler-Nordheim characteristic, transverse emittance, and pulse duration are presented and, when possible, compared to numerical simulations. The implications of our results to high-average-current electron sources are briefly discussed.

  19. Trapped fields up to 2 T in a 12 mm square stack of commercial superconducting tape using pulsed field magnetization

    Science.gov (United States)

    Patel, A.; Hopkins, S. C.; Glowacki, B. A.

    2013-03-01

    The ability of superconductors to sustain persistent currents has been well exploited with (RE)BCO superconducting bulks, which can be magnetized to form a compact source of high magnetic field. However, thin films can also sustain persistent currents, which can be utilized by stacking them in layers to create a type of composite bulk. Such a stack is capable of trapping higher fields than a bulk, as reported in this paper. 12 mm wide, 55 μm thick commercial (RE)BCO tape from Superpower Inc was cut into 12 mm by 12 mm squares, stacked together and magnetized at temperatures between 10 and 77.4 K using a sequence of pulsed magnetic fields. The results are compared to a commercial 14 mm diameter YBCO bulk, showing that the stack of tapes outperformed the bulk at temperatures below approximately 60 K. Particularly high trapped fields were achieved below 50 K, with a maximum of 2.0 T at 10 K measured 0.8 mm from the stack surface. The maximum trapped field possible for a stack of tapes increases significantly with decreasing temperature down to 10 K, rather than saturating at a higher temperature as in the case of a bulk, due to superior thermal stability. The Jc, thermal and mechanical properties of commercial (RE)BCO tapes give them great potential for use as trapped field magnets activated by pulsed magnetic fields.

  20. Enhanced trapped field performance of bulk high-temperature superconductors using split coil, pulsed field magnetization with an iron yoke

    Science.gov (United States)

    Ainslie, M. D.; Fujishiro, H.; Mochizuki, H.; Takahashi, K.; Shi, Y.-H.; Namburi, D. K.; Zou, J.; Zhou, D.; Dennis, A. R.; Cardwell, D. A.

    2016-07-01

    Investigating and predicting the magnetization of bulk superconducting materials and developing practical magnetizing techniques is crucial to using them as trapped field magnets in engineering applications. The pulsed field magnetization (PFM) technique is considered to be a compact, mobile and relative inexpensive way to magnetize bulk samples, requiring shorter magnetization times (on the order of milliseconds) and a smaller and less complicated magnetization fixture; however, the trapped field produced by PFM is generally much smaller than that of slower zero field cooling or field cooling techniques, particularly at lower operating temperatures. In this paper, the PFM of two, standard Ag-containing Gd-Ba-Cu-O samples is carried out using two types of magnetizing coils: (1) a solenoid coil, and (2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field. It is shown that a significantly higher trapped field can be achieved using a split coil with an iron yoke, and in order to explain these how this arrangement works in detail, numerical simulations using a 2D axisymmetric finite element method based on the H -formulation are carried to qualitatively reproduce and analyze the magnetization process from both electromagnetic and thermal points of view. It is observed that after the pulse peak significantly less flux exits the bulk when the iron core is present, resulting in a higher peak trapped field, as well as more overall trapped flux, after the magnetization process is complete. The results have important implications for practical applications of bulk superconductors as such a split coil arrangement with an iron yoke could be incorporated into the design of a portable, high magnetic field source/magnet to enhance the available magnetic field or in an axial gap-type bulk superconducting electric machine, where iron can be incorporated into the stator windings to (1) improve the trapped field from the magnetization process

  1. Mid-infrared strong-field ionization of clusters using two-cycle pulses

    CERN Document Server

    Schütte, Bernd; Austin, Dane R; Brahms, Christian; Strüber, Christian; Witting, Tobias; Tisch, John W G; Marangos, Jonathan P

    2016-01-01

    We study mid-infrared strong-field ionization of rare-gas clusters ($10^3$ to $10^5$ atoms) in the impulsive limit using 12 fs laser pulses. The emission of fast electrons with kinetic energies exceeding 3 keV is observed at 1.8 $\\mu$m and an intensity of $1\\times 10^{15}$ W/cm$^2$, whereas only electrons below 500 eV are observed at 800 nm using a similar intensity and pulse duration. Fast electrons are preferentially emitted along the laser polarization direction, indicating that they are driven out from the cluster by the laser field via direct and rescattering processes within a few femtoseconds. In contrast to previous near-infrared strong-field ionization experiments in clusters using 200-1000 fs laser pulses, the yield of fast electrons decreases with increasing pulse duration. Scaling to longer wavelengths is expected to result in a highly directional current of hot electrons on a few-femtosecond timescale.

  2. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    Science.gov (United States)

    Kodama, Kazuto

    2015-02-01

    This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder) as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM). These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization-field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization) at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

  3. Spectrum of fast electrons in a dense gas in the presence of a nonuniform pulsed field

    Science.gov (United States)

    Tkachev, A. N.; Yakovlenko, S. I.

    2007-01-01

    The problems of gas preionization in discharges related to laser physics are considered. The propagation of fast electrons injected from the cathode in the presence of a nonuniform nonstationary field and the motion of multiplying electrons at the edge of the avalanche in the presence of a nonuniform nonstationary field are simulated. The effect of the voltage pulse steepness and the field nonuniformity on the mean propagation velocity of fast electrons and their energy distribution is demonstrated. At certain combinations of the voltage pulse rise time and amplitude and at a certain time interval, the center of gravity of the electron cloud can move in the opposite direction relative to the direction of force acting upon electrons. It is also demonstrated that the number of hard particles (and, hence, the hard component of the x-ray bremsstrahlung) increases with both an increase in the voltage amplitude and a decrease in the pulse rise time. For nonoptimal conditions of the picosecond voltage pulse, an assumption is formulated: an electron beam in gas is formed due to the electrons at the edge of the avalanche rather than the background multiplication wave approaching the anode.

  4. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    Directory of Open Access Journals (Sweden)

    Kazuto eKodama

    2015-02-01

    Full Text Available This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM. These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization–field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

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

    Science.gov (United States)

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

    2010-08-01

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

  6. Nonmonotonous variation of DNA angular separation during asymmetric pulsed field electrophoresis.

    Science.gov (United States)

    Nazemifard, Neda; Bhattacharjee, Subir; Masliyah, Jacob H; Harrison, D Jed

    2013-09-01

    Asymmetric pulsed field electrophoresis within crystalline arrays is used to generate angular separation of DNA molecules. Four regimes of the frequency response are observed, a low frequency rise in angular separation, a plateau, a subsequent decline, and a second plateau at higher frequencies. It is shown that the frequency response for different sized DNA is governed by the relation between pulse time and the reorientation time of DNA molecules. The decline in angular separation at higher frequencies has not previously been analyzed. Real-time videos of single DNA molecules migrating under high frequency-pulsed electric field show the molecules no longer follow the head to tail switching, ratchet mechanism seen at lower frequencies. Once the pulse period is shorter than the reorientation time, the migration mechanism changes significantly. The molecule reptates along the average direction of the two electric fields, which reduces the angular separation. A freely jointed chain model of DNA is developed where the porous structure is represented with a hexagonal array of obstacles. The model qualitatively predicts the variation of DNA angular separation with respect to frequency.

  7. Near and intermediate fields of an ultrashort pulse transmitted through Young’s double-slit experiment

    NARCIS (Netherlands)

    Nugrowati, A.M.; Pereira, S.F.; Van de Nes, A.S.

    2008-01-01

    We present a systematic study of the transmitted field of an ultrashort pulse through Young’s double slit. We show how the spatial-temporal distribution of the field in the near and intermediate zone is affected by the input polarization state of the pulse. The analysis has been separated to study t

  8. Near and intermediate fields of an ultrashort pulse transmitted through Young’s double-slit experiment

    NARCIS (Netherlands)

    Nugrowati, A.M.; Pereira, S.F.; Van de Nes, A.S.

    2008-01-01

    We present a systematic study of the transmitted field of an ultrashort pulse through Young’s double slit. We show how the spatial-temporal distribution of the field in the near and intermediate zone is affected by the input polarization state of the pulse. The analysis has been separated to study

  9. Mantle Response to a Slab Gap and Three-dimensional Slab Interaction in Central America

    Science.gov (United States)

    Jadamec, M. A.; Fischer, K. M.

    2013-12-01

    southern Cocos slab edge and a separate region of toroidal flow around the northern Nazca slab edge, together leading to east directed mantle flow through the slab gap. The geodynamic models suggest the counterclockwise toroidal flow around the southern Cocos plate may provide a solid state mantle flow framework leading to the observed northward decrease in anomalous isotopic signatures in the Costa Rican-Nicaraguan volcanic front. Adding a third slab into the models, the west-dipping Antilles slab, further modulates the mantle flow field, leading to increased eastward directed slab entrained flow beneath the Caribbean plate and enhancing the east-directed flow of the mantle through the Cocos-Nazca slab gap. The incorporation of the Antilles slab also leads to an increase in the east-directed surface velocity of the overriding Caribbean plate, suggesting coupling between the interior of the Caribbean plate and the mantle, and that the observed eastward motion of the Caribbean plate in geodetic studies (Lopez et al., 2006) is due in part to mantle flow related to subduction of the Antilles slab.

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

    Science.gov (United States)

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

    2011-09-01

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

  11. Fast simulation of non-linear pulsed ultrasound fields using an angular spectrum approach

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Jørgen Arendt

    2013-01-01

    . The accuracy of the nonlinear ASA is compared to the non-linear simulation program – Abersim, which is a numerical solution to the Burgers equation based on the OSM. Simulations are performed for a linear array transducer with 64 active elements, focus at 40 mm, and excitation by a 2-cycle sine wave......A fast non-linear pulsed ultrasound field simulation is presented. It is implemented based on an angular spectrum approach (ASA), which analytically solves the non-linear wave equation. The ASA solution to the Westervelt equation is derived in detail. The calculation speed is significantly...... increased compared to a numerical solution using an operator splitting method (OSM). The ASA has been modified and extended to pulsed non-linear ultrasound fields in combination with Field II, where any array transducer with arbitrary geometry, excitation, focusing and apodization can be simulated...

  12. Neutron investigations of magnetic properties of crystal substances with use of a pulsed magnetic field

    CERN Document Server

    Nitts, V V

    2001-01-01

    Bases for neutron researches of magnetic properties of crystal substances with use of a pulsed magnetic field and analysis of possible application of various neutron sources in this area are submitted. The review of the most interesting physical results is presented. Main investigations on pulsed reactors of JINR are researches on kinetics of the first order reorientational phase transitions induced in single crystals, and also measurements of antiferromagnetic ordering induced by an external magnetic field. Magnetic phase transitions, induced by a field up to 160 kOe in several magnetic ordering substances, were studied in KEK (Japan). Experiment on observation of spin-flop transition in MnF sub 2 was carried out on TRIGA-reactor in a mode of single flashes of power

  13. Composite NDE using full-field pulse-echo ultrasonic propagation imaging system

    Science.gov (United States)

    Hong, Seung-Chan; Lee, Jung-Ryul; Park, Jongwoon

    2016-04-01

    In this paper, a novel ultrasonic propagation imaging system, called a full-field pulse-echo ultrasonic propagation imaging (FF PE UPI) system is presented. The coincided laser beams for ultrasonic sensing and generation are scanned and pulse-echo mode laser ultrasounds are captured. This procedure makes it possible to generate full-field ultrasound in through-the-thickness direction as large as the scan area. The system nondestructively inspected targets with two-axis translation stages. Various structural inspection results in the form of full-field ultrasonic wave propagation videos are introduced, which are an aluminum honeycomb sandwich, ailerons and carbon fiber reinforced plastic (CFRP) honeycomb sandwich structures including various defects.

  14. Determination of relevant parameters for the use of electronic dosemeters in pulsed fields of ionising radiation.

    Science.gov (United States)

    Zutz, H; Hupe, O; Ambrosi, P; Klammer, J

    2012-09-01

    Active electronic dosemeters using counting techniques are used for radioprotection purposes in pulsed radiation fields in X-ray diagnostics or therapy. The disadvantage of the limited maximum measurable dose rate becomes significant in these radiation fields and leads to some negative effects. In this study, a set of relevant parameters for a dosemeter is described, which can be used to decide whether it is applicable in a given radiation field or not. The determination of these relevant parameters-maximum measurable dose rate in the radiation pulse, dead time of the dosemeter, indication per counting event and measurement cycle time-is specified. The results of the first measurements on the determination of these parameters for an electronic personal dosemeter of the type Thermo Fisher Scientific EPD Mk2 are shown.

  15. In vitro stimulation with a strongly pulsed electromagnetic field on rat basophilic leukemia cells

    Science.gov (United States)

    Choi, J. W.; Shin, S. C.; Kim, S.; Chung, E. R.; Bang, J. H.; Cho, G. I.; Choi, S. D.; Park, Y. S.; Jang, T. S.; Yoo, Y. M.; Lee, S. S.; Hwang, D. G.

    2010-05-01

    In this study, the effects of pulsed electromagnetic field stimulation with a strong magnetic field on rat basophilic leukemia (RBL-2H3) cells were investigated to confirm the efficacy of the magnetic stimulator for biomedical applications. The maximum intensity of the magnetic field generated from the stimulation coil was 0.203 T, and the transition time was 126 μs. The oscillation time and frequency of the pulsed field were almost 0.1 ms and 8 kHz, respectively. The cell count as well as the mRNA expression and DNA sequence of the cytokine genes, such as the tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4), of the stimulated RBL-2H3 cells were analyzed with a hemocytometer and via reverse transcriptase polymerase chain reaction to determine the physiological response under a strong pulse field. After 12 h stimulation, cell death was observed at an increasing scale with the increase in the stimulation time. On the other hand, the cells that were stimulated for 10 min almost doubled as the interval time between the stimulations was extended.

  16. The effects of samarium-cobalt magnets and pulsed electromagnetic fields on tooth movement.

    Science.gov (United States)

    Darendeliler, M A; Sinclair, P M; Kusy, R P

    1995-06-01

    The purpose of this study was to determine whether the application of either samarium cobalt magnets or pulsed electromagnetic fields could increase the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the effect of a magnetic field on bony physiology and metabolism and to monitor for possible systemic side effects. Fifteen grams of laterally directed orthodontic force were applied to move the maxillary central incisors of a sample of 18 young male Hartley guinea pigs divided into three groups: group 1, an orthodontic coil spring was used to move the incisors; group 2, a pair of samarium-cobalt magnets provided the tooth moving force; and group 3, a coil spring was used in combination with a pulsed electromagnetic field. The results showed that both the static magnetic field produced by the samarium-cobalt magnets and the pulsed electromagnetic field used in combination with the coil spring were successful in increasing the rate of tooth movement over that produced by the coil springs alone. The mechanism producing this effect appears to have involved a reduction in the "lag" phase often seen in orthodontic tooth movement. Both magnetically stimulated groups also showed increases in both the organization and amount of new bone deposited in the area of tension between the orthodontically moved maxillary incisors.

  17. Restructuring of plasmonic nanoparticle aggregates with arbitrary particle size distribution in pulsed laser fields

    Science.gov (United States)

    Ershov, A. E.; Gavrilyuk, A. P.; Karpov, S. V.; Polyutov, S. P.

    2016-11-01

    We have studied processes of interaction of pulsed laser radiation with resonant groups of plasmonic nanoparticles (resonant domains) in large colloidal nanoparticle aggregates having different interparticle gaps and particle size distributions. These processes are responsible for the origin of nonlinear optical effects and photochromic reactions in multiparticle aggregates. To describe photo-induced transformations in resonant domains and alterations in their absorption spectra remaining after the pulse action, we introduce the factor of spectral photomodification. Based on calculation of changes in thermodynamic, mechanical, and optical characteristics of the domains, the histograms of the spectrum photomodification factor have been obtained for various interparticle gaps, an average particle size, and the degree of polydispersity. Variations in spectra have been analyzed depending on the intensity of laser radiation and various combinations of size characteristics of domains. The obtained results can be used to predict manifestation of photochromic effects in composite materials containing different plasmonic nanoparticle aggregates in pulsed laser fields.

  18. Non-contact wide-field hemodynamic imaging reveals the inverted jugular venous pulse waveform

    CERN Document Server

    Amelard, Robert; Greaves, Danielle K; Pfisterer, Kaylen J; Leung, Jason; Clausi, David A; Wong, Alexander

    2016-01-01

    Cardiovascular disease is the leading cause of death globally. Cardiovascular monitoring is important to prevent diseases from progressing. The jugular venous pressure waveform (JVP) is able to provide important information about cardiac health. Factors such as mechanical deformations, electric abnormalities, and irregular external forces change the fundamental shape of the JVP. However, current methods for measuring the JVP require invasive catheter insertion, or subjective qualitative visual inspection of the patient's jugular pulse. Thus, JVP are not routinely performed, and are scheduled only when there is probable cause for catheterisation. Non-invasive monitoring methods would benefit JVP monitoring. Recently, there has been a surge in focus on photoplethysmographic imaging (PPGI) systems. These systems are non-contact wide-field imaging systems able to assess blood pulse waveforms across a large area of the body. However, PPGI has not been previously explored for measuring jugular venous pulse. In this...

  19. Low-noise pulsed current source for magnetic-field measurements of magnets for accelerators

    Science.gov (United States)

    Omelyanenko, M. M.; Borisov, V. V.; Donyagin, A. M.; Khodzhibagiyan, H. G.; Kostromin, S. A.; Makarov, A. A.; Shemchuk, A. V.

    2017-01-01

    The schematic diagram, design, and technical characteristics of the pulsed current source developed and produced for the magnetic-field measurement system of superconducting magnets for accelerators are described. The current source is based on the current regulator with pass transistor bank in the linear mode. Output current pulses (0-100 A) are produced by utilizing the energy of the preliminarily charged capacitor bank (5-40 V), which is additionally charged between pulses. The output current does not have the mains frequency and harmonics ripple. The relative noise level is less than-100 dB (or 10-5) of RMS value (it is defined as the ratio of output RMS noise current to a maximal output current of 100 A within the operating bandwidth, expressed in dB). The work was performed at the Veksler and Baldin Laboratory of High Energy Physics, Joint Institute for Nuclear Research (JINR).

  20. Enhancing strong-field induced molecular vibration with femtosecond pulse shaping

    CERN Document Server

    Bitter, Martin; Milner, Valery

    2012-01-01

    This work investigates the utility of femtosecond pulse shaping in increasing the efficiency of Raman excitation of molecules in the strong-field interaction regime. We study experimentally and theoretically the effect of pulse shaping on the strength of non-resonant coherent anti-Stokes Raman scattering in iodine vapor at laser intensities exceeding $10^{13}$ W/cm$^2$. We show that unlike the perturbative case, shaping strong non-resonant laser pulses can increase the signal strength beyond that observed with the transform-limited excitation. Both adiabatic and non-adiabatic schemes of excitation are explored, and the differences of their potential in increasing the excitation efficiency are discussed.

  1. Spectral enhancement of single attosecond pulses by time-delayed control field

    CERN Document Server

    Chu, Wei-Chun

    2012-01-01

    An optical coherent control scheme has been proposed where an extreme ultraviolet single attosecond pulse (SAP) propagates through a dense helium gas dressed by a time-delayed femtosecond laser pulse. The laser pulse couples the 2s2p(^1P) and 2s^2(^1S) autoionizing states when the SAP excites the 2s2p state. After going through the gas, the spectral and temporal profiles of the SAP are strongly distorted. A narrowed but enhanced spike in the spectrum shows up for specific intensities and time delays of the laser, which exemplifies the control of a broadband photon wave packet by an ultrashort dressing field for the first time. We analyze the photon and electron dynamics and conclude on the dressing condition that maximizes this enhancement. The result demonstrates new possibilities of attosecond optical control.

  2. Atlas Pulsed Power System: a Driver for Multi-Megagauss Fields

    Energy Technology Data Exchange (ETDEWEB)

    Cochrane, J.C.; Bartsch, R.R.; Bennett, G.A.; Bowman, D.W.; Davis, H.A.; Ekdahl, C.A.; Gribble, R.F.; Kimerly, H.J.; Nielsen, K.E.; Parsons, W.M.; Paul, J.D.; Scudder, D.W.; Trainor, R.J.; Thompson, M.C.; Watt, R.G.

    1998-10-18

    Atlas is a pulsed power machine designed for hydrodynamic experiments for the Los Alamos High Energy Density Physics Experimental program. It is presently under construction and should be operational in late 2000. Atlas will store 23 MJ at an erected voltage of 240 kV. This will produce a current of 30 MA into a static load and as much as 32 MA into a dynamic load. The current pulse will have a rise time of {approximately}5{micro}s and will produce a magnetic field driving the impactor liner of several hundred Tesla at the target radius of one to two centimeters. The collision can produce shock pressures of {approximately}15 megabars. Design of the pulsed power system will be presented along with data obtained from the Atlas prototype Marx module.

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

    Directory of Open Access Journals (Sweden)

    Dong Yin

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

  4. Membrane permeabilization of mammalian cells using bursts of high magnetic field pulses

    Directory of Open Access Journals (Sweden)

    Vitalij Novickij

    2017-04-01

    Full Text Available Background Cell membrane permeabilization by pulsed electromagnetic fields (PEMF is a novel contactless method which results in effects similar to conventional electroporation. The non-invasiveness of the methodology, independence from the biological object homogeneity and electrical conductance introduce high flexibility and potential applicability of the PEMF in biomedicine, food processing, and biotechnology. The inferior effectiveness of the PEMF permeabilization compared to standard electroporation and the lack of clear description of the induced transmembrane transport are currently of major concern. Methods The PEMF permeabilization experiments have been performed using a 5.5 T, 1.2 J pulse generator with a multilayer inductor as an applicator. We investigated the feasibility to increase membrane permeability of Chinese Hamster Ovary (CHO cells using short microsecond (15 µs pulse bursts (100 or 200 pulses at low frequency (1 Hz and high dB/dt (>106 T/s. The effectiveness of the treatment was evaluated by fluorescence microscopy and flow cytometry using two different fluorescent dyes: propidium iodide (PI and YO-PRO®-1 (YP. The results were compared to conventional electroporation (single pulse, 1.2 kV/cm, 100 µs, i.e., positive control. Results The proposed PEMF protocols (both for 100 and 200 pulses resulted in increased number of permeable cells (70 ± 11% for PI and 67 ± 9% for YP. Both cell permeabilization assays also showed a significant (8 ± 2% for PI and 35 ± 14% for YP increase in fluorescence intensity indicating membrane permeabilization. The survival was not affected. Discussion The obtained results demonstrate the potential of PEMF as a contactless treatment for achieving reversible permeabilization of biological cells. Similar to electroporation, the PEMF permeabilization efficacy is influenced by pulse parameters in a dose-dependent manner.

  5. Evanescent field interaction of tapered fiber with graphene oxide in generation of wide-bandwidth mode-locked pulses

    Science.gov (United States)

    Ahmad, H.; Faruki, M. J.; Razak, M. Z. A.; Tiu, Z. C.; Ismail, M. F.

    2017-02-01

    Pulses with picosecond pulse widths are highly desired for high precision laser applications. A mode-locked pulse laser utilizing evanescent field interaction of a tapered fiber with graphene oxide (GO) is demonstrated. A homemade fabrication stage was used to fabricate the tapered fiber using systematic flame brushing and a GO solution was used to coat the microfiber using optical deposition technique. Pulse trains with a pulse width of 3.46 ps, a 3 dB optical bandwidth of 11.82 nm and a repetition rate of 920 kHz were obtained. The system has substantial potential for many crucial medical, communication, bio processing, military, and industrial applications.

  6. Continuous reversal of Hanle resonances of counter-propagating pulse and continuous-wave field

    CERN Document Server

    Dimitrijević, Jelena; Jelenković, Branislav M

    2013-01-01

    In this work we study propagation dynamics of the two counter-propagating lasers, the continuous-wave (CW) laser and the pulse of another laser, when both lasers are tuned to the $F_{g}=2 \\rightarrow F_{e}=1$ transition in $^{87}$Rb, and therefore can develop Hanle electromagnetically induced transparency (EIT) in Rb vapor. We calculate transmission of both lasers as a function of applied magnetic field, and investigate how the propagation of the pulse affects the transmission of the CW laser. And vice versa, we have found conditions when the Gaussian pulse can either pass unchanged, or be significantly absorbed in the vacuum Rb cell. This configuration is therefore suitable for the convenient control of the pulse propagation and the system is of interest for optically switching of the laser pulses. In terms of the corresponding shapes of the coherent Hanle resonances, this is equivalent to turning the coherent resonance from Hanle EIT into electromagnetically induced absorption (EIA) peak. There is the range...

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

    CERN Document Server

    Lebovka, Nikolai

    2007-01-01

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

  8. Ultrafast electron field emission from gold resonant antennas studied by two terahertz pulse experiments

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Zalkovskij, Maksim; Strikwerda, Andrew C.;

    2015-01-01

    Summary form only given. Ultrafast electron field emission from gold resonant antennas induced by strong terahertz (THz) transient is investigated using two THz pulse experiments. It is shown that UV emission from nitrogen plasma generated by liberated electrons is a good indication of the local...... electric field at the antenna tip. Using this method resonant properties of antennas fabricated on high resistivity silicon are investigated in the strong field regime. Decrease of antenna Q-factor due to ultrafast carrier multiplication in the substrate is observed....

  9. Temperature field at time of pulse current discharge in metal structure with elliptical embedding crack

    Institute of Scientific and Technical Information of China (English)

    FU Yu-ming; TIAN Zhen-guo; ZHENG Li-juan; LI Wei

    2008-01-01

    Theoretical analysis is made on the temperature field at the time of pulse current discharge in a metal structure with an elliptical embedding crack. In finding the temperature field, analogy between the current flow through an elliptical embedding crack and the fluid flow through a barrier is made based on the similarity principle. Boundary conditions derived from this theory are introduced so that the distribution of current density and the temperature field expressions can be obtained. The study provides a theoretic basis to the applications of stopping spatial crack with electromagnetic heating.

  10. Pulsed magnetic field study of the spin gap in intermediate valence compound SmB 6

    Science.gov (United States)

    Flachbart, K.; Bartkowiak, M.; Demishev, S.; Gabani, S.; Glushkov, V.; Herrmannsdorfer, T.; Moshchalkov, V.; Shitsevalova, N.; Sluchanko, N.

    2009-10-01

    In this work, we report the behavior of electrical resistivity of SmB 6 at temperatures between 2.2 and 70 K in pulsed magnetic fields up to 54 T. A strong negative magnetoresistance was detected with increasing magnetic field, when lowering the temperature in the range T30 K is discussed within the framework of exciton-polaron model of local charge fluctuations in SmB 6 proposed by Kikoin and Mishchenko. It seems that these exciton-polaron in-gap states are influenced both by temperature and magnetic field.

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

    CERN Document Server

    Nakamura, Daisuke; Takeyama, Shojiro

    2014-01-01

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

  12. Modelling and comparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed field magnetization

    Science.gov (United States)

    Ainslie, M. D.; Fujishiro, H.; Ujiie, T.; Zou, J.; Dennis, A. R.; Shi, Y.-H.; Cardwell, D. A.

    2014-06-01

    The ability to generate a permanent, stable magnetic field unsupported by an electromotive force is fundamental to a variety of engineering applications. Bulk high temperature superconducting (HTS) materials can trap magnetic fields of magnitude over ten times higher than the maximum field produced by conventional magnets, which is limited practically to rather less than 2 T. In this paper, two large c-axis oriented, single-grain YBCO and GdBCO bulk superconductors are magnetized by the pulsed field magnetization (PFM) technique at temperatures of 40 and 65 K and the characteristics of the resulting trapped field profile are investigated with a view of magnetizing such samples as trapped field magnets (TFMs) in situ inside a trapped flux-type superconducting electric machine. A comparison is made between the temperatures at which the pulsed magnetic field is applied and the results have strong implications for the optimum operating temperature for TFMs in trapped flux-type superconducting electric machines. The effects of inhomogeneities, which occur during the growth process of single-grain bulk superconductors, on the trapped field and maximum temperature rise in the sample are modelled numerically using a 3D finite-element model based on the H-formulation and implemented in Comsol Multiphysics 4.3a. The results agree qualitatively with the observed experimental results, in that inhomogeneities act to distort the trapped field profile and reduce the magnitude of the trapped field due to localized heating within the sample and preferential movement and pinning of flux lines around the growth section regions (GSRs) and growth sector boundaries (GSBs), respectively. The modelling framework will allow further investigation of various inhomogeneities that arise during the processing of (RE)BCO bulk superconductors, including inhomogeneous Jc distributions and the presence of current-limiting grain boundaries and cracks, and it can be used to assist optimization of

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

    Science.gov (United States)

    Frey, Wolfgang; Gusbeth, Christian; Schwartz, Thomas

    2013-10-01

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

  14. Electrochemotherapy by pulsed electromagnetic field treatment (PEMF) in mouse melanoma B16F10 in vivo

    Science.gov (United States)

    Kranjc, Simona; Kranjc, Matej; Scancar, Janez; Jelenc, Jure; Sersa, Gregor

    2016-01-01

    Introduction Pulsed electromagnetic field (PEMF) induces pulsed electric field, which presumably increases membrane permeabilization of the exposed cells, similar to the conventional electroporation. Thus, contactless PEMF could represent a promising approach for drug delivery. Materials and methods Noninvasive electroporation was performed by magnetic field pulse generator connected to an applicator consisting of round coil. Subcutaneous mouse B16F10 melanoma tumors were treated with intravenously injection of cisplatin (CDDP) (4 mg/kg), PEMF (480 bipolar pulses, at frequency of 80 Hz, pulse duration of 340 μs) or with the combination of both therapies (electrochemotherapy − PEMF + CDDP). Antitumor effectiveness of treatments was evaluated by tumor growth delay assay. In addition, the platinum (Pt) uptake in tumors and serum, as well as Pt bound to the DNA in the cells and Pt in the extracellular fraction were measured by inductively coupled plasma mass spectrometry. Results The antitumor effectiveness of electrochemotherapy with CDDP mediated by PEMF was comparable to the conventional electrochemotherapy with CDDP, with the induction of 2.3 days and 3.0 days tumor growth delay, respectively. The exposure of tumors to PEMF only, had no effect on tumor growth, as well as the injection of CDDP only. The antitumor effect in combined treatment was related to increased drug uptake into the electroporated tumor cells, demonstrated by increased amount of Pt bound to the DNA. Approximately 2-fold increase in cellular uptake of Pt was measured. Conclusions The obtained results in mouse melanoma model in vivo demonstrate the possible use of PEMF induced electroporation for biomedical applications, such as electrochemotherapy. The main advantages of electroporation mediated by PEMF are contactless and painless application, as well as effective electroporation compared to conventional electroporation. PMID:27069448

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

    Science.gov (United States)

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

    2015-06-01

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

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

    Science.gov (United States)

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

    2013-06-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

  19. Field-swept pulsed electron paramagnetic resonance of Cr{sup 3+}-doped ZBLAN fluoride glass

    Energy Technology Data Exchange (ETDEWEB)

    Drew, S.C. [School of Physics and Materials Engineering, Monash University, VIC (Australia)]. E-mail: simon.drew@spme.monash.edu.au; Pilbrow, J.R. [School of Physics and Materials Engineering, Monash University, VIC (Australia); Newman, P.J.; MacFarlane, D.R. [Department of Chemistry, Monash University, VIC (Australia)

    2001-10-07

    Field-swept pulsed electron paramagnetic resonance (EPR) spectra of a ZBLAN fluoride glass doped with a low concentration of Cr{sup 3+} are obtained using echo-detected EPR and hole-burning free induction decay detection. We review the utility of the pulsed EPR technique in generating field-swept EPR spectra, as well as some of the distorting effects that are peculiar to the pulsed detection method. The application of this technique to Cr{sup 3+}-doped ZBLAN reveals that much of the broad resonance extending from g{sup eff}=5.1 to g{sup eff}=1.97, characteristic of X-band continuous wave EPR of Cr{sup 3+} in glasses, is absent. We attribute this largely to the variation in nutation frequencies across the spectrum that result from sites possessing large fine structure interactions. The description of the spin dynamics of such sites is complicated and we discuss some possible approaches to the simulation of the pulsed EPR spectra. (author)

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

    Directory of Open Access Journals (Sweden)

    Drosou Foteini

    2017-01-01

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

  1. Pulsed magnetic field measurement system based on colossal magnetoresistance-B-scalar sensors for railgun investigation.

    Science.gov (United States)

    Stankevič, T; Medišauskas, L; Stankevič, V; Balevičius, S; Żurauskienė, N; Liebfried, O; Schneider, M

    2014-04-01

    A high pulsed magnetic field measurement system based on the use of CMR-B-scalar sensors was developed for the investigations of the electrodynamic processes in electromagnetic launchers. The system consists of four independent modules (channels) which are controlled by a personal computer. Each channel is equipped with a CMR-B-scalar sensor connected to the measurement device-B-scalar meter. The system is able to measure the magnitude of pulsed magnetic fields from 0.3 T to 20 T in the range from DC up to 20 kHz independently of the magnetic field direction. The measurement equipment circuit is electrically separated from the ground and shielded against low and high frequency electromagnetic noise. The B-scalar meters can be operated in the presence of ambient pulsed magnetic fields with amplitudes up to 0.2 T and frequencies higher than 1 kHz. The recorded signals can be transmitted to a personal computer in a distance of 25 m by means of a fiber optic link. The system was tested using the electromagnetic railgun RAFIRA installed at the French-German Research Institute of Saint-Louis, France.

  2. Simultaneous measurement of magnetization and magnetostriction in 50 T pulsed high magnetic fields.

    Science.gov (United States)

    Doerr, M; Lorenz, W; Neupert, T; Loewenhaupt, M; Kozlova, N V; Freudenberger, J; Bartkowiak, M; Kampert, E; Rotter, M

    2008-06-01

    To simultaneously perform magnetization and magnetostriction measurements in high magnetic fields, a miniaturized device was developed that combines an inductive magnetometer with a capacitive dilatometer and, therefore, it is called "dilamagmeter." This combination of magnetic and magnetoelastic investigations is a new step to a complex understanding of solid state properties. The whole system can be mounted in a 12 mm clear bore of any cryostat usually used in nondestructive pulsed high field magnets. The sensitivity of both methods is about 10(-5) A m(2) for magnetization and 10(-5) relative changes in length for striction measurements. Measurements on a GdSi single crystal, which are corrected by the background signal of the experimental setup, agree well with the results of steady field experiments. All test measurements, which are up until now performed in the temperature range of 4-100 K, confirm the perfect usability and high stability in pulsed fields up to 50 T with a pulse duration of 10 ms.

  3. General planar transverse domain walls realized by optimized transverse magnetic field pulses in magnetic biaxial nanowires

    Science.gov (United States)

    Li, Mei; Wang, Jianbo; Lu, Jie

    2017-02-01

    The statics and field-driven dynamics of transverse domain walls (TDWs) in magnetic nanowires (NWs) have attracted continuous interests because of their theoretical significance and application potential in future magnetic logic and memory devices. Recent results demonstrate that uniform transverse magnetic fields (TMFs) can greatly enhance the wall velocity, meantime leave a twisting in the TDW azimuthal distribution. For application in high-density NW devices, it is preferable to erase the twisting so as to minimize magnetization frustrations. Here we report the realization of a completely planar TDW with arbitrary tilting attitude in a magnetic biaxial NW under a TMF pulse with fixed strength and well-designed orientation profile. We smooth any twisting in the TDW azimuthal plane thus completely decouple the polar and azimuthal degrees of freedom. The analytical differential equation describing the polar angle distribution is derived and the resulting solution is not the Walker-ansatz form. With this TMF pulse comoving, the field-driven dynamics of the planar TDW is investigated with the help of the asymptotic expansion method. It turns out the comoving TMF pulse increases the wall velocity under the same axial driving field. These results will help to design a series of modern magnetic devices based on planar TDWs.

  4. Time resolved dosimetry of human brain exposed to low frequency pulsed magnetic fields

    Science.gov (United States)

    Paffi, Alessandra; Camera, Francesca; Lucano, Elena; Apollonio, Francesca; Liberti, Micaela

    2016-06-01

    An accurate dosimetry is a key issue to understanding brain stimulation and related interaction mechanisms with neuronal tissues at the basis of the increasing amount of literature revealing the effects on human brain induced by low-level, low frequency pulsed magnetic fields (PMFs). Most literature on brain dosimetry estimates the maximum E field value reached inside the tissue without considering its time pattern or tissue dispersivity. Nevertheless a time-resolved dosimetry, accounting for dispersive tissues behavior, becomes necessary considering that the threshold for an effect onset may vary depending on the pulse waveform and that tissues may filter the applied stimulatory fields altering the predicted stimulatory waveform’s size and shape. In this paper a time-resolved dosimetry has been applied on a realistic brain model exposed to the signal presented in Capone et al (2009 J. Neural Transm. 116 257-65), accounting for the broadband dispersivity of brain tissues up to several kHz, to accurately reconstruct electric field and current density waveforms inside different brain tissues. The results obtained by exposing the Duke’s brain model to this PMF signal show that the E peak in the brain is considerably underestimated if a simple monochromatic dosimetry is carried out at the pulse repetition frequency of 75 Hz.

  5. Experimental studies on extremely low frequency pulsed magnetic field inhibiting sarcoma and enhancing cellular immune functions

    Institute of Scientific and Technical Information of China (English)

    张沪生; 叶晖; 张传清; 曾繁清; 黄兴鼎; 张晴川; 李宗山; 杜碧

    1997-01-01

    The previous observation with an electron microscope showed that extremely low frequency (ELF) pulsed magnetic field (PMF) (with the maximum intensity of 0. 6-2. 0 T, gradient of 10-100 T. M-1, pulse width of 20-200 ms and frequency of 0. 16-1. 34 Hz) inhibited the growth of S-180 sarcoma in mice and enhanced the ability of immune cell’s dissolving sarcoma cells. In this study, the DNA contents of nuclei were assayed by using Faulgen Staining method. With an electron microscope and cell stereoscopy technology it was observed that magnetic field affected the sarcoma cell’s metabolism, lowered its malignancy, and restrained its rapid and heteromorphic growth. The magnetic field enhanced the cellular immune ability and the reaction of lymphocytes and plasma. Since ELF pulsed magnetic fields can inhibit the growth of sarcomas and enhance the cellular immune ability, it is possible to use it as a new method to treat cancer.

  6. Active split-ring metamaterial slabs for magnetic resonance imaging

    CERN Document Server

    Lopez, Marcos A; Freire, Manuel J; Behr, Volker C; Jakob, Peter M; Marques, Ricardo

    2011-01-01

    In this work, it is analyzed the ability of split-ring metamaterial slabs with zero/high permeability to reject/confine the radiofrequency magnetic field in magnetic resonance imaging systems. Using an homogenization procedure, split-ring slabs have been designed and fabricated to work in a 1.5T system. Active elements consisting of pairs of crossed diodes are inserted in the split-rings. With these elements, the permeability of the slabs can be automatically switched between a unity value when interacting with the strong excitation field of the transmitting body coil, and zero or high values when interacting with the weak field produced by protons in tissue. Experiments are shown for different configurations where these slabs can help to locally increase the signal-to-noise-ratio.

  7. Fault modeling of the Mw 7.0 shallow intra-slab strike-slip earthquake occurred on 2011 July 10th using near-field tsunami record

    Science.gov (United States)

    Kubota, T.; Hino, R.; Iinuma, T.

    2014-12-01

    On 2011 July 10th, an earthquake of Mw 7.0 occurred in the shallow part of the Pacific slab beneath the large coseismic slip area of the 2011 Tohoku-Oki earthquake. This event has a strike-slip focal mechanism with steep dipping nodal planes. Near the epicenter, aftershocks determined by OBS deployment formed clear two orthogonal lineaments with identical strikes of the focal mechanism solution, suggesting that the aftershock activity occurred along the two conjugate faults. The strikes of these faults were almost parallel to the direction of the magnetic lineations and the fracture zones of the incoming Pacific plate, suggesting that the earthquake was the re-rupture of congenital fractures under the extensional stress induced by the Tohoku-Oki earthquake. It is of great interest to know the down-dip size of the source fault not only to understand the mechanical nature of the slab but also the post-2011 stress state. Coseismic seafloor deformation and tsunami associated with the earthquake were observed by ocean bottom pressure gauges deployed within ~ 100 km from the epicenter. We estimated the finite fault model of this event to discuss the rupture properties of the earthquake. We sought the source model assuming a rectangular fault with a uniform slip assuming the strike of the fault to be one of those of two nodal planes of the focal mechanism. The two preferable source models corresponding to the two nodal planes explained the observed data equally well. For either model, the depth of the downdip end exceeds 40 km below the plate boundary, meaning the fault widths (down-dip size) were much larger than the depth extent of the aftershock distribution (~ 15 km). We sought another source model assuming the simultaneous rupture of the conjugate faults and found that the width of the fault model was more consistent with the aftershock distribution than the single rupture plane models. The 2011 intraslab strike-slip earthquake might be a compound rupture of the

  8. Zylon-reinforced high magnetic field coils for the K.U. Leuven pulsed field laboratory

    Science.gov (United States)

    Rosseel, K.; Herlach, F.; Boon, W.; Bruynseraede, Y.

    2001-01-01

    PBO Zylon ® fibers have been used for the internal reinforcement of pulsed magnets. Due to the very high packing density (80%) of these fibers, vacuum impregnation of Zylon reinforced coils is difficult. Impregnation test were performed using pressure-vacuum impregnation and wet winding. A prototype series of coils for 60-70 T with 1-2 ms pulse duration was designed and wound, using wet winding for both the internal Zylon and external carbon fiber reinforcement. Special precautions were taken to avoid insulation breakdown at the transitions between conductor layers. Furthermore, axial movement of the conductor wires was restrained by strong axial compression of the coil with a steel shell casing. These modifications were incorporated into an 80 T coil made of Zylon and soft Cu. The design, construction and performance of this coil are discussed.

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

    Science.gov (United States)

    Taya, Hidetoshi; Fujii, Hirotsugu; Itakura, Kazunori

    2014-09-01

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

  10. A portable magnetic field of >3 T generated by the flux jump assisted, pulsed field magnetization of bulk superconductors

    Science.gov (United States)

    Zhou, Difan; Ainslie, Mark D.; Shi, Yunhua; Dennis, Anthony R.; Huang, Kaiyuan; Hull, John R.; Cardwell, David A.; Durrell, John H.

    2017-02-01

    A trapped magnetic field of greater than 3 T has been achieved in a single grain GdBa2Cu3O7-δ (GdBaCuO) bulk superconductor of diameter 30 mm by employing pulsed field magnetization. The magnet system is portable and operates at temperatures between 50 K and 60 K. Flux jump behaviour was observed consistently during magnetization when the applied pulsed field, Ba, exceeded a critical value (e.g., 3.78 T at 60 K). A sharp dBa/dt is essential to this phenomenon. This flux jump behaviour enables the magnetic flux to penetrate fully to the centre of the bulk superconductor, resulting in full magnetization of the sample without requiring an applied field as large as that predicted by the Bean model. We show that this flux jump behaviour can occur over a wide range of fields and temperatures, and that it can be exploited in a practical quasi-permanent magnet system.

  11. Transformation of the frequency-modulated continuous-wave field into a train of short pulses by resonant filters

    CERN Document Server

    Shakhmuratov, R N

    2016-01-01

    The resonant filtering method transforming frequency modulated radiation field into a train of short pulses is proposed to apply in optical domain. Effective frequency modulation can be achieved by electro-optic modulator or by resonant frequency modulation of the filter with a narrow absorption line. Due to frequency modulation narrow-spectrum CW radiation field is seen by the resonant filter as a comb of equidistant spectral components separated by the modulation frequency. Tuning narrow-bandwidth filter in resonance with $n$-th spectral component of the comb transforms the radiation field into bunches of pulses with $n$ pulses in each bunch. The transformation is explained by the interference of the coherently scattered resonant component of the field with the whole comb. Constructive interference results in formation of pulses, while destructive interference is seen as dark windows between pulses. It is found that the optimal thickness of the resonant filter is several orders of magnitude smaller than the...

  12. Hypercapnic normalization of BOLD fMRI: comparison across field strengths and pulse sequences

    DEFF Research Database (Denmark)

    Cohen, Eric R.; Rostrup, Egill; Sidaros, Karam

    2004-01-01

    size, as well as experimental, such as pulse sequence and static magnetic field strength (B(0)). Thus, it is difficult to compare task-induced fMRI signals across subjects, field strengths, and pulse sequences. This problem can be overcome by normalizing the neural activity-induced BOLD fMRI response...... by a global hypercapnia-induced BOLD signal. To demonstrate the effectiveness of the BOLD normalization approach, gradient-echo BOLD fMRI at 1.5, 4, and 7 T and spin-echo BOLD fMRI at 4 T were performed in human subjects. For neural stimulation, subjects performed sequential finger movements at 2 Hz, while...... for global stimulation, subjects breathed a 5% CO(2) gas mixture. Under all conditions, voxels containing primarily large veins and those containing primarily active tissue (i.e., capillaries and small veins) showed distinguishable behavior after hypercapnic normalization. This allowed functional activity...

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Irena Jeličić

    2012-03-01

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

  15. Electron emission properties of gated silicon field emitter arrays driven by laser pulses

    Science.gov (United States)

    Shimawaki, Hidetaka; Nagao, Masayoshi; Neo, Yoichiro; Mimura, Hidenori; Wakaya, Fujio; Takai, Mikio

    2016-10-01

    We report optically modulated electron emission from gated p-type silicon field emitter arrays (Si-FEAs). The device's "volcano" structure is designed to control the photoexcitation of electrons by transmitting light through the small gate aperture, thereby minimizing the photogeneration of slow diffusion carriers outside the depletion region in the tip. Compared to that in the dark, the emission current was enhanced by more than three orders of magnitude in the high field region when irradiated with blue laser pulses. Results from the time-resolved measurements of photoassisted electron emission showed that these possess the same response as the laser pulse with no discernible delay. These results indicate that the volcano device structure is effective at eliminating the generation of diffusion carriers and that a fully optimized FEA is promising as a photocathode for producing high-speed modulated electron beams.

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

    Science.gov (United States)

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

    2005-04-01

    Nanosecond, high intensity pulsed electric fields [nsPEFs] that are below the plasma membrane [PM] charging time constant have decreasing effects on the PM and increasing effects on intracellular structures and functions as the pulse duration decreases. When human cell suspensions were exposed to nsPEFs where the electric fields were sufficiently intense [10-300ns, platelets. These included Ca2+ mobilization from intracellular stores [endoplasmic reticulum] and subsequently through store-operated Ca2+ channels in the PM. In addition, platelet activation measured as aggregation responses were observed in human platelets. Finally, when nsPEF conditions followed classical electroporation-mediated transfection, the expression intensity and number of GFP-expressing cells were enhanced above cells exposed to electroporation conditions alone. These studies demonstrate that application of nsPEFs to cells or tissues can modulate cell-signaling mechanisms with possible applications as a new basic science tool, cancer treatment, wound healing, and gene therapy.

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

    CERN Document Server

    Jamali, J; Moini, R; Sadeghi, H

    2002-01-01

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

  18. Mechanical Studies on Treatment of Malignant Tumour by Ultralow Frequency Pulsed- Gradient Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    Deng Ren-qing; Liu Qing-hua; Zhang Hu-sheng

    2003-01-01

    Ultralow frequency (ULF) pulsed-gradient magnetic field (with the maximum intensity of 0. 6-2. 0 T,gradient of 10-100 T @ m-1 , pulse width of 20-200 ms and frequency of 0. 16-1. 34 Hz) treatment of mice can inhibit murine malignant tumour growth and can induce apoptosis of cancer cell. The apoptotic cancer cell contracted, became rounder and divorced from adjacent cells; the heterochromatin condensed and coagulated together along the inner side of the nuclear membrane; the endoplasmic reticulums expanded and fused with the cellular membrane; many apoptotic bodies which were packed by the cellular membrane appeared and were devoured by some lymphocytes and plasma. By Lorentz force the magnetic field keeps the moving ions within bounds of Larmor radius. Thus, penetrating capability of the positive and negative ions through the cell membrane was affected,even the role on the cell membrane formed.

  19. Nanograting formation in air through plasmonic near-field ablation induced by femtosecond laser pulses

    Science.gov (United States)

    Miyaji, Godai; Miyazaki, Kenzo

    2017-02-01

    Superimposed multiple shots of low-fluence femtosecond (fs) laser pulses form a periodic nanostructure on solid surfaces through ablation. We have demonstrated that the self-organization process of nanostructuring can be regulated to fabricate a homogeneous nanograting on the target surface in air. A simple two-step ablation process and an ablation technique using interfering fs laser beams were developed to control plasmonic near-fields generated by fs laser pulses. The results have shown the nature of a single spatial standing wave mode of surface plasmon polaritons of which periodically enhanced near-fields ablate the target surface, to fabricate the nanograting on gallium nitride (GaN) and metals such as stainless steel (SUS) and titanium (Ti).

  20. Numerical Simulation of a Dual Pulse Solid Rocket Motor Flow Field

    Directory of Open Access Journals (Sweden)

    Afroz Javed

    2012-11-01

    Full Text Available Numerical simulations are carried out for the internal flow field of a dual pulse solid rocket motor port to understand the flow behaviour. Three dimensional Reynolds Averaged Navier Stokes equations are solved alongwith shear stress transport turbulence model using commercial code. The combustion gas is assumed as a mixture of alumina and gases and single phase flow calculations are done with the thermo chemical properties provided for the mixture. The simulation captures all the essential features of the flow field. The flow accelerates through the pulse separation device (PSD port and high temperature and high velocity gas is seen to impinge the motor wall near the PSD port. The overall total pressure drop through motor port and through PSD is found to be moderate.Defence Science Journal, 2012, 62(6, pp.369-374, DOI:http://dx.doi.org/10.14429/dsj.62.1418

  1. The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

    CERN Document Server

    Yokoyama, K; Murahari, P; Wang, K; Dunstan, D J; Waller, S P; McPhail, D J; Hillier, A D; Henson, J; Harper, M R; Heathcote, P; Drew, A J

    2016-01-01

    A high power pulsed laser system has been installed on the high magnetic field muon instrument (HiFi) at the ISIS pulsed neutron and muon source, situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade enables one to perform light-pump muon-probe experiments under a high field, which opens up a brand-new area in the muon spin spectroscopy. In this report we overview the principle of the HiFi Laser system, and describe the newly developed techniques and devices that enable a controlled photoexcitation in the muon instrument. A demonstration experiment illustrates the unique combination of the photoexcited system and avoided level crossing technique.

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

    Science.gov (United States)

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

    2012-10-01

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

  3. Experiences in the epidemiological surveillance of foodborne pathogens by Pulsed field Gel Electophoresis (PFGE) in Peru

    OpenAIRE

    Zamudio, María Luz; Laboratorio de Referencia Nacional de Enteropatógenos, Centro Nacional de Salud Pública, Instituto Nacional de Salud, Lima, Perú. Bióloga.; Meza, Ana; Laboratorio de Referencia Nacional de Enteropatógenos, Centro Nacional de Salud Pública, Instituto Nacional de Salud, Lima, Perú. Técnico Especializado en Laboratorio.; Bailón, Henri; Laboratorio de Biotecnología y Biología Molecular, Centro Nacional de Salud Pública, Instituto Nacional de Salud, Lima, Perú. Bióloga.; Martínez-Urtaza, Jaime; Instituto de Acuicultura, Universidad de Santiago de Compostela, Santiago de Compostela, España. Doctor en Ciencias Biológicas.; Campos, Josefina; Servicio de Enterobacteria. ANLIS. Instituto “Carlos G. Malbrán”, Buenos Aires, Argentina. Bioquímica.

    2011-01-01

    Foodborne diseases and other enteric infections often occur as outbreaks and cause morbidity and mortality all over the world. In Perú, they represent a serious public health problem, and are caused by a great variety of infectious agents. For epidemiological research, a wide array of typification methods are used. One of the most important tools for the molecular subtyping of bacterial pathogens is the Pulsed Field Gel Electrophoresis (PFGE), which is a highly precise method that allows ...

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

    NARCIS (Netherlands)

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

    2000-01-01

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

  5. Effect of pulsed electromagnetic field on inflammatory pathway markers in RAW 264.7 murine macrophages

    Directory of Open Access Journals (Sweden)

    Ross CL

    2013-03-01

    Full Text Available Christina L Ross,1,2 Benjamin S Harrison2 1Akamai University, Department of Energy Medicine, Hilo, HI, USA; 2Wake Forest Institute for Regenerative Medicine, Wake Forest Baptist Health, Winston-Salem, NC, USA Abstract: In the treatment of bacterial infections, antibiotics have proven to be very effective, but the way in which antibiotics are dosed can create a lag time between the administration of the drug and its absorption at the site of insult. The time it takes an antibiotic to reach therapeutic levels can often be significantly increased if the vascular system is compromized. Bacteria can multiply pending the delivery of the drug, therefore, developing treatments that can inhibit the inflammatory response while waiting for antibiotics to take effect could help prevent medical conditions such as septic shock. The aim of this study was to examine the effect of a pulsed electromagnetic field on the production of inflammatory markers tumor necrosis factor (TNF, transcription factor nuclear factor kappa B (NFkB, and the expression of the A20 (tumor necrosis factor-alpha-induced protein 3, in an inflamed-cell model. Lipopolysaccharide-challenged cells were exposed to a pulsed electromagnetic field at various frequencies in order to determine which, if any, frequency would affect the TNF-NFkB-A20 inflammatory response pathway. Our study revealed that cells continuously exposed to a pulsed electromagnetic field at 5 Hz demonstrated significant changes in the downregulation of TNF-α and NFkB and also showed a trend in the down regulation of A20, as compared with controls. This treatment could be beneficial in modulating the immune response, in the presence of infection. Keyword: TNFAIP3, pulsed electromagnetic field, macrophages, TNF, NFkB

  6. Fifth-Order Harmonic Generation using a Coherent Controlled Two-Pulsed Optical Field

    Institute of Scientific and Technical Information of China (English)

    刘婷婷; 王大威; 陆伟新; 孙泉; 杨宏; 蒋红兵; 龚旗煌

    2002-01-01

    We have experimentally studied the characteristics of fifth-order harmonic radiation produced by two coherent femtosecond laser pulses with a changeable relative phase. The intensities of harmonic generation are found to increase vith the coherent degree. In one optical period, the temporal variation of harmonics exhibits an asymmetric characteristic, vhich is interpreted in terms of ionization theory and the deformation of the wave packets of fundamental field contribution to harmonic generation.

  7. Laser-Induced Continuum Structure of NO Molecules in Two-Colour Femtosecond Pulsed Laser Fields

    Institute of Scientific and Technical Information of China (English)

    WANG Sen-Ming; YUAN Kai-Jun; CONG Shu-Lin

    2006-01-01

    The method of quantum wave packet dynamics is used to study the multiphoton ionization of NO molecules via a two-photon Raman coupling and a laser-induced continuum structure (LICS) state in two-colour strong femtosecond pulsed laser fields.Time-and energy-resolved photoelectron energy spectra are calculated for describing three photoionization channels.The population transfers through the LICS and the Raman coupling passages and discussed.

  8. Time-dependent density functional theory for strong-field ionization by circularly polarized pulses

    Science.gov (United States)

    Chirilă, Ciprian C.; Lein, Manfred

    2017-03-01

    By applying time-dependent density functional theory to a two-dimensional multielectron atom subject to strong circularly polarized light pulses, we confirm that the ionization of p orbitals with defined angular momentum depends on the sense of rotation of the applied field. A simple ad-hoc modification of the adiabatic local-density exchange-correlation functional is proposed to remedy its unphysical behavior under orbital depletion.

  9. Molecular characterization of Clostridium tetani strains by pulsed-field gel electrophoresis and colony PCR.

    Science.gov (United States)

    Plourde-Owobi, Lucile; Seguin, Delphine; Baudin, Marie-Anne; Moste, Catherine; Rokbi, Bachra

    2005-09-01

    Pulsed-field gel electrophoresis and PCR were applied for the first time to the molecular characterization of Clostridium tetani. Among five strains tested, one (CN1339) turned out to contain a mixture of two genetically different clones and two (D11 and G761) to contain bacteria differing by the presence or absence of the 74-kb plasmid harboring the tetX gene.

  10. Fringe integral equation method for a truncated grounded dielectric slab

    DEFF Research Database (Denmark)

    Jørgensen, Erik; Maci, S.; Toccafondi, A.

    2001-01-01

    The problem of scattering by a semi-infinite grounded dielectric slab illuminated by an arbitrary incident TMz polarized electric field is studied by solving a new set of “fringe” integral equations (F-IEs), whose functional unknowns are physically associated to the wave diffraction processes...... occurring at the truncation. The F-IEs are obtained by subtracting from the surface/surface integral equations pertinent to the truncated slab, an auxiliary set of equations obtained for the canonical problem of an infinite grounded slab illuminated by the same source. The F-IEs are solved by the method...

  11. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    Energy Technology Data Exchange (ETDEWEB)

    Shlapakovski, A. S.; Beilin, L.; Krasik, Ya. E. [Physics Department, Technion 32000 Haifa (Israel); Hadas, Y. [Department of Applied Physics, Rafael, POBox 2250, Haifa 31021 (Israel); Schamiloglu, E. [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-07-15

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

  12. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    Science.gov (United States)

    Shlapakovski, A. S.; Beilin, L.; Hadas, Y.; Schamiloglu, E.; Krasik, Ya. E.

    2015-07-01

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

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

    Science.gov (United States)

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

    2016-07-01

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

  14. Nonperturbative measurement of the local magnetic field using pulsed polarimetry for fusion reactor conditions (invited).

    Science.gov (United States)

    Smith, Roger J

    2008-10-01

    A novel diagnostic technique for the remote and nonperturbative sensing of the local magnetic field in reactor relevant plasmas is presented. Pulsed polarimetry [Patent No. 12/150,169 (pending)] combines optical scattering with the Faraday effect. The polarimetric light detection and ranging (LIDAR)-like diagnostic has the potential to be a local B(pol) diagnostic on ITER and can achieve spatial resolutions of millimeters on high energy density (HED) plasmas using existing lasers. The pulsed polarimetry method is based on nonlocal measurements and subtle effects are introduced that are not present in either cw polarimetry or Thomson scattering LIDAR. Important features include the capability of simultaneously measuring local T(e), n(e), and B(parallel) along the line of sight, a resiliency to refractive effects, a short measurement duration providing near instantaneous data in time, and location for real-time feedback and control of magnetohydrodynamic (MHD) instabilities and the realization of a widely applicable internal magnetic field diagnostic for the magnetic fusion energy program. The technique improves for higher n(e)B(parallel) product and higher n(e) and is well suited for diagnosing the transient plasmas in the HED program. Larger devices such as ITER and DEMO are also better suited to the technique, allowing longer pulse lengths and thereby relaxing key technology constraints making pulsed polarimetry a valuable asset for next step devices. The pulsed polarimetry technique is clarified by way of illustration on the ITER tokamak and plasmas within the magnetized target fusion program within present technological means.

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

    Science.gov (United States)

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

    2013-06-01

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

  16. Effects of Multipolar Radiofrequency and Pulsed Electromagnetic Field Treatment for Face and Neck Rejuvenation

    Science.gov (United States)

    de Oliveira, Thais Cristina Ferraz; Rocha, Sheyla de Fatima Soares; Ramos, Daniel Gontijo; Ramos, Camila Gontijo; Carvalho, Michelle Vanessa dos Anjos

    2017-01-01

    Skin aging is a gradual process that leads to wrinkle formation, laxity, and overall changes in skin appearance. In recent years, the demands to noninvasive treatments for facial rejuvenation increased, along with a variety of technologies and devices, such as radiofrequency. The present study aimed to evaluate the clinical effects of a multipolar radiofrequency and pulsed electromagnetic field treatment for face and neck rejuvenation. Eleven patients with mild to moderate grades of photoaging underwent eight radiofrequency and pulsed electromagnetic field treatment sessions, once a week. Clinical photographs were taken before and a week after the end of the treatment, and improvement of facial skin parameters was evaluated by two different investigators. Significant improvement in skin laxity was observed in all eleven patients (100%). Improvement in facial contour was noted in 73% and 100% of patients when analyzed by investigators A and B, respectively. The score for overall improvement in skin condition was 3 ± 0.78 for investigator A and 3.6 ± 0.67 for investigator B. All patients were satisfied with the procedure and noted significant improvement in the skin. The combined multipolar radiofrequency and pulsed electromagnetic field device is effective and safe for treatment of aged skin in Brazilian patients. PMID:28373880

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

    Science.gov (United States)

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

    2011-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-14

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

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

    Science.gov (United States)

    Shneider, Mikhail N.; Pekker, Mikhail

    2015-06-01

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

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

    Science.gov (United States)

    Ganeva, Valentina; Galutzov, Bojidar; Teissie, Justin

    2014-02-01

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

  1. Effects of Multipolar Radiofrequency and Pulsed Electromagnetic Field Treatment for Face and Neck Rejuvenation

    Directory of Open Access Journals (Sweden)

    Thais Cristina Ferraz de Oliveira

    2017-01-01

    Full Text Available Skin aging is a gradual process that leads to wrinkle formation, laxity, and overall changes in skin appearance. In recent years, the demands to noninvasive treatments for facial rejuvenation increased, along with a variety of technologies and devices, such as radiofrequency. The present study aimed to evaluate the clinical effects of a multipolar radiofrequency and pulsed electromagnetic field treatment for face and neck rejuvenation. Eleven patients with mild to moderate grades of photoaging underwent eight radiofrequency and pulsed electromagnetic field treatment sessions, once a week. Clinical photographs were taken before and a week after the end of the treatment, and improvement of facial skin parameters was evaluated by two different investigators. Significant improvement in skin laxity was observed in all eleven patients (100%. Improvement in facial contour was noted in 73% and 100% of patients when analyzed by investigators A and B, respectively. The score for overall improvement in skin condition was 3 ± 0.78 for investigator A and 3.6 ± 0.67 for investigator B. All patients were satisfied with the procedure and noted significant improvement in the skin. The combined multipolar radiofrequency and pulsed electromagnetic field device is effective and safe for treatment of aged skin in Brazilian patients.

  2. A Cryogen-free Cryostat for Scientific Experiment in Pulsed High Magnetic Fields

    Science.gov (United States)

    Wang, Shaoliang; Li, Liang; Zuo, Huakun; Liu, Mengyu; Peng, Tao

    Traditional cryostats for scientific experiments in pulsed high magnetic fields use liquid helium as the cooling source. To reduce the running cost and to increase the operational efficiency, a cryogen-free cryostat based on a GM cryocooler has been developed for a 60 T pulsed field measurement cell at Wuhan National High Magnetic Field Center. A double layer temperature-control insert was designed to obtain a stable temperature in the sample chamber of the cryostat. In order to eliminate the sample temperature fluctuation caused by the eddy current heating during the pulse, the inner layer is made from a fiberglass tubing with an epoxy coating. Different from the traditional cryostat, the sample and the temperature controller are not immerged in the 4He bath. Instead, they are separated by helium gas under sub-atmospheric pressure, which makes the heat transfer smoother. At the sample position, a resistance heater wound with antiparallel wires is mounted on the inner layer to heat the sample. Using the temperature-control insert, the temperature can be controlled with an accuracy of ±0.01 K in the range of 1.4 K-20 K, and ±0.05 K between 20 K and 300 K.

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

    Institute of Scientific and Technical Information of China (English)

    ZHU Li-nan; MA Jun; YANG Shi-dong

    2007-01-01

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

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

    Science.gov (United States)

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

    2017-09-01

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

  5. AC measurement of heat capacity and magnetocaloric effect for pulsed magnetic fields

    OpenAIRE

    2010-01-01

    International audience; A new calorimeter for measurements of the heat capacity and magnetocaloric effect of small samples in pulsed magnetic fields is discussed for the exploration of thermal and thermodynamic properties at temperatures down to 2 K. We tested the method up to 0H=50 T, but it could be extended to higher fields. For these measurements we used carefully calibrated bare-chip Cernox® and RuO2 thermometers, and we present a comparison of their performances. The monotonic temperatu...

  6. Effects of ultrasonic field in pulse electrodeposition of NiFe film on Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, R. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia); Yow, H.K. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia)], E-mail: hkyow@mmu.edu.my; Ong, B.H. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia); Manickam, R. [Electronics Faculty, Tyndale Education Group Pte Ltd., 188942 (Singapore); Saaminathan, V. [School of Material Science and Engineering, Nanyang Technological University, 639798 (Singapore); Tan, K.B. [Department of Chemistry, Universiti Putra Malaysia, Serdang, 43400 (Malaysia)

    2009-07-29

    NiFe film was pulse electrodeposited on conductive Cu substrate under galvanostatic mode in the presence of an ultrasonic field. The NiFe film electrodeposited was subjected to structural and surface analyses by X-ray diffraction, energy dispersive X-ray spectroscopy, surface profiling and scanning electron microscopy, respectively. The results show that the ultrasonic field has significantly improved the surface roughness, reduced the spherical grain size in the range from 490-575 nm to 90-150 nm, and increased the Ni content from 76.08% to 79.74% in the NiFe film electrodeposited.

  7. Casimir effect for two lossy dispersive dielectric slabs

    Science.gov (United States)

    Matloob, R.; Keshavarz, A.; Sedighi, D.

    1999-11-01

    The electromagnetic field is quantized using the Green's-function method for the geometry of a Fabry-Perot cavity, made up of two identical lossy dispersive slabs of finite thickness. The dielectric functions of the slabs are assumed to be an arbitrary complex function of frequency obeying causality requirements. The attractive Casimir force between the two slabs is calculated by the help of the latter field operators, via evaluating the difference between the vacuum pressures on both sides of each slab. Special attention is paid to the limiting case of the Casimir effect for two conducting plates. The Lorentz model of the dielectric function is used to demonstrate the variation of the force in terms of plasma frequency. The Casimir force expression is also related to the imaginary part of the response function. The latter expression is used to introduce the repulsive Casimir force between two conducting plates located inside a Fabry-Perot cavity.

  8. Hot dense magnetized ultrarelativistic spinor matter in a slab

    CERN Document Server

    Sitenko, Yu A

    2016-01-01

    Properties of hot dense ultrarelativistic spinor matter in a slab of finite width, placed in a transverse uniform magnetic field, are studied. The admissible set of boundary conditions is determined by the requirement that spinor matter be confined inside the slab. In thermal equilibrium, the chiral separation effect in the slab is shown to depend both on temperature and chemical potential; this is distinct from the unrealistic case of the magnetic field filling the unbounded (infinite) medium, when the effect is temperature-independent. In the realistic case of the slab, a stepwise behaviour of the axial current density at zero temperature is smoothed out as temperature increases, turning into a linear behaviour at infinitely large temperature. A choice of boundary conditions can facilitate either augmentation or attenuation of the chiral separation effect; in particular, the effect can persist even at zero chemical potential, if temperature is nonzero. Thus the boundary condition can serve as a source that ...

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

    Science.gov (United States)

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

    2013-03-01

    The persistent influx of ions through nanopores created upon cellular exposure to nanosecond pulse electric fields (nsPEF) could be used to modulate neuronal function. One ion, calcium (Ca(2+)), is important to action potential firing and regulates many ion channels. However, uncontrolled hyper-excitability of neurons leads to Ca(2+) overload and neurodegeneration. Thus, to prevent unintended consequences of nsPEF-induced neural stimulation, knowledge of optimum exposure parameters is required. We determined the relationship between nsPEF exposure parameters (pulse width and amplitude) and nanopore formation in two cell types: rodent neuroblastoma (NG108) and mouse primary hippocampal neurons (PHN). We identified thresholds for nanoporation using Annexin V and FM1-43, to detect changes in membrane asymmetry, and through Ca(2+) influx using Calcium Green. The ED50 for a single 600 ns pulse, necessary to cause uptake of extracellular Ca(2+), was 1.76  kV/cm for NG108 and 0.84  kV/cm for PHN. At 16.2  kV/cm, the ED50 for pulse width was 95 ns for both cell lines. Cadmium, a nonspecific Ca(2+) channel blocker, failed to prevent Ca(2+) uptake suggesting that observed influx is likely due to nanoporation. These data demonstrate that moderate amplitude single nsPEF exposures result in rapid Ca(2+) influx that may be capable of controllably modulating neurological function.

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

    Science.gov (United States)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2017-05-01

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

  12. The therapeutic effect of a pulsed electromagnetic field on the reproductive patterns of male Wistar rats exposed to a 2.45-GHz microwave field

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar

    2011-01-01

    Full Text Available INTRODUCTION: Environmental exposure to man-made electromagnetic fields has been steadily increasing with the growing demand for electronic items that are operational at various frequencies. Testicular function is particularly susceptible to radiation emitted by electromagnetic fields. OBJECTIVES: This study aimed to examine the therapeutic effects of a pulsed electromagnetic field (100 Hz on the reproductive systems of male Wistar rats (70 days old. METHODS: The experiments were divided into five groups: microwave sham, microwave exposure (2.45 GHz, pulsed electromagnetic field sham, pulsed electromagnetic field (100 Hz exposure, and microwave/pulsed electromagnetic field exposure. The animals were exposed for 2 hours/day for 60 days. After exposure, the animals were sacrificed, their sperm was used for creatine and caspase assays, and their serum was used for melatonin and testosterone assays. RESULTS: The results showed significant increases in caspase and creatine kinase and significant decreases in testosterone and melatonin in the exposed groups. This finding emphasizes that reactive oxygen species (a potential inducer of cancer are the primary cause of DNA damage. However, pulsed electromagnetic field exposure relieves the effect of microwave exposure by inducing Faraday currents. CONCLUSIONS: Electromagnetic fields are recognized as hazards that affect testicular function by generating reactive oxygen species and reduce the bioavailability of androgen to maturing spermatozoa. Thus, microwave exposure adversely affects male fertility, whereas pulsed electromagnetic field therapy is a non-invasive, simple technique that can be used as a scavenger agent to combat oxidative stress.

  13. Trapping and breaking of in vivo nicked DNA during pulsed field gel electrophoresis.

    Science.gov (United States)

    Khan, Sharik R; Kuzminov, Andrei

    2013-12-15

    Pulsed field gel electrophoresis (PFGE) offers a high-resolution approach to quantify chromosomal fragmentation in bacteria, measured as percentage of chromosomal DNA entering the gel. The degree of separation in pulsed field gel (PFG) depends on the size of DNA as well as various conditions of electrophoresis such as electric field strength, time of electrophoresis, switch time, and buffer composition. Here we describe a new parameter, the structural integrity of the sample DNA itself, that influences its migration through PFGs. We show that subchromosomal fragments containing both spontaneous and DNA damage-induced nicks are prone to breakage during PFGE. Such breakage at single-strand interruptions results in artifactual decrease in molecular weight of linear DNA making accurate determination of the number of double-strand breaks difficult. Although breakage of nicked subchromosomal fragments is field strength independent, some high-molecular-weight subchromosomal fragments are also trapped within wells under the standard PFGE conditions. This trapping can be minimized by lowering the field strength and increasing the time of electrophoresis. We discuss how breakage of nicked DNA may be mechanistically linked to trapping. Our results suggest how to optimize conditions for PFGE when quantifying chromosomal fragmentation induced by DNA damage. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Field-free molecular orientation induced by single-cycle THz pulses: the role of resonance and quantum interference

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2013-01-01

    We consider the rotational excitation of molecules induced by asymmetric (“half-cycle”) as well as symmetric single-cycle THz pulses, leading to field-free time-dependent orientation. We show that the basic excitation mechanisms are very similar for the two types of pulses; i.e., the frequency...

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

  18. Pulsed, High Power Microwave Processing of Field Emission in Superconducting Cavities

    Energy Technology Data Exchange (ETDEWEB)

    I.E. Campisi

    1992-08-03

    The phenomenon of field emission is very well known: electrons are extracted from within the solid state potential well of a metal and are emitted from the metal's surface under the presence of an accelerating potential. In many accelerators, electromagnetic energy is delivered to charged particles by means of microwave cavities excited in modes with electric field components aligned along the particles trajectory. If the mode used is of the TM type (most accelerators operate in the TM{sub 010} mode), then a surface electric field inside the cavities exists which can produce field emitted electrons when allowed by the phase of the fields. These field emitted currents can cause considerable current loading and bremsstrahlung radiation in normal conducting cavities (mostly copper), but in superconducting cavities they have the additional effect of locally heating the superconducting material above its transition temperature and causing performance degradation of the cavities and eventually quenches (transition to the normal conducting state). At present this phenomenon constitutes the limiting factor in superconducting cavity performance, and is receiving a great deal of attention. Several diagnostic methods have been developed to detect, locate and characterize the sources of field-emitted electrons. Methods have also been proposed and tested which decrease the incidence of field emission sites on metal surfaces, but the most effective method to date requires high temperature firing of the superconducting structures in an ultra high vacuum. This can be done only if the cavities are completely removed from their cryostat, a lengthy and costly process. In this paper the properties and advantages are examined of a different method for field emission processing, which does not require a cavity disassembly and which can be performed in situ. The method described makes use of short, high peak power RF pulses to reach high electric fields for a short time. At the same

  19. Curling probe measurement of large-volume pulsed plasma confined by surface magnetic field

    Science.gov (United States)

    Pandey, Anil; Sakakibara, Wataru; Matsuoka, Hiroyuki; Nakamura, Keiji; Sugai, Hideo; Chubu University Team; DOWA Thermotech Collaboration

    2015-09-01

    Curling probe (CP) has recently been developed which enables the local electron density measurement even in plasma for non-conducting film CVD. The electron density is obtained from a shift of resonance frequency of spiral antenna in discharge ON and OFF monitored by a network analyzer (NWA). In case of a pulsed glow discharge, synchronization of discharge pulse with frequency sweep of NWA must be established. In this paper, we report time and space-resolved CP measurement of electron density in a large volume plasma (80 cm diameter, 110 cm length) confined by surface magnetic field (multipole cusp field ~0.03 T). For plasma-aided modification of metal surface, the plasma is produced by 1 kV glow discharge at pulse frequency of 0.3 - 25 kHz with various duty ratio in gas (Ar, N2, C2H2) at pressure ~ 1 Pa. A radially movable CP revealed a remarkable effect of surface magnetic confinement: detach of plasma from the vessel wall and a fairly uniform plasma in the central region. In afterglow phase, the electron density was observed to decrease much faster in C2H2 discharge than in Ar discharge.

  20. Interaction of CO2 laser pulses with solid targets in magnetic fields

    Science.gov (United States)

    Loter, N. G.; Halverson, W.; Lax, B.

    1981-08-01

    High-temperature plasmas were generated by focussing 225-J gain-switched CO2 laser pulses onto planar solid targets within the bore of a Bitter solenoid magnet. DC magnetic fields up to 100 kG were applied parallel to the laser propagation vector, partially confining a long plasma column streaming away from the target. Target materials included teflon (CF2), graphite, and Al. Soft x-ray diagnostics, including a dual-channel, time-resolving TAP crystal spectrometer, a pinhole camera, and differentially-filtered p-i-n diodes, were used to determine electron density, electron temperature, and axial and radial expansion characteristics of the plasma. From these measurements, it was deduced that effects of refraction became increasingly important as B was increased; furthermore, these effects were strongly dependent on target material. For all targets, refraction occurred late in the pulse when the radially confined plasmas left the focal volume. For teflon and aluminum targets, but not for the lower Z graphite targets, it was inferred that significant side scattering also occurred early in the pulse with sufficiently strong magnetic fields.

  1. Strong-field ionization inducing multi-electron-hole coherence probed by attosecond pulses

    Science.gov (United States)

    Zhao, Jing; Yuan, Jianmin; Zhao, Zengxiu

    2016-05-01

    Recent advances in attosecond spectroscopy has enabled resolving electron-hole dynamics in real time. The correlated electron-hole dynamics and the resulted coherence are directly related to how fast the ionization is completed. How the laser-induced electron-hole coherence evolves and whether it can be utilized to probe the core dynamics are among the key questions in attosecond physics or even attosecond chemistry. In this work, we propose a new scenario to apply IR-pump-XUV-probe schemes to resolving strong field ionization induced and attosecond pulse driven electron-hole dynamics and coherence in real time. The coherent driving of both the infrared laser and the attosecond pulse correlates the dynamics of the core-hole and the valence-hole which leads to the otherwise forbidden absorption and emission of XUV photon. An analytical model is developed based on the strong-field approximation by taking into account of the essential multielectron configurations. The emission spectra from the core-valence transition and the core-hole recombination are found modulating strongly as functions of the time delay between the two pulses, which provides a unique insight into the instantaneous ionization and the interplay of the multi-electron-hole coherence.

  2. The effect of long-term pulsing electromagnetic field stimulation on experimental osteoporosis of rats.

    Science.gov (United States)

    Mishima, S

    1988-03-01

    The author performed experiments in order to investigate what biological effect on the bone would be produced by long-term pulsing electromagnetic field (PEMF) systemic stimulation. In some of the mature female rats used as experimental animals, bilateral ovariectomy and right sciatic neurectomy were performed in order to make a model osteoporosis. PEMF stimulation was produced by repetitive pulse burst (RPB) waves at a positive amplitude of 25 mV, negative amplitude of 62.5 mV, burst width of 4.2 ms, pulse width of 230 microseconds and 12 Hz, with the magnetic field strength within a cage being set at 3-10 Gauss. PEMF stimulation over 6 months did not produce any effects on the physiologically aged bones. PEMF stimulation also did not produce any effects on losed cortical bone in osteoporotic hindlegs. On the other hand, an increase of bone volume and bone formation activity was observed in the cancellous bone of osteoporotic hindlegs. These findings suggested that PEMF stimulation exerted a preventive effect against bone loss of osteoporotic hindlegs. Furthermore, an observed increase in bone marrow blood flow seemed to be related with this increase of bone volume and bone formation activity.

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

    Science.gov (United States)

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

    2012-01-01

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

  4. Low-field microwave absorption in pulse laser deposited FeSi thin film

    Energy Technology Data Exchange (ETDEWEB)

    Gavi, H. [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa); Ngom, B.D. [Groupe d Laboratoires de Physique des Solid et des Materiaux, Faculte deSciences et Techniques, Universite Cheikh Anta de Dakar, BP 25114 Dakar-Fann, Daka 16996 (Senegal); Institut National de la Recherche Scientifique Centre-Energie Materiaux, Telecommunications 1650, Boulevard Lionel Boulet Varennes (Quebec), Canada J3X 1S2 (Canada); Beye, A.C. [Groupe d Laboratoires de Physique des Solid et des Materiaux, Faculte deSciences et Techniques, Universite Cheikh Anta de Dakar, BP 25114 Dakar-Fann, Daka 16996 (Senegal); Strydom, A.M. [Department of Physics, University of Johannesburg, Johannesburg 2006 (South Africa); Srinivasu, V.V., E-mail: vallavs@unisa.ac.za [Department of Physics, University of South Africa, Pretoria 0003 (South Africa); Chaker, M. [Institut National de la Recherche Scientifique Centre-Energie Materiaux, Telecommunications 1650, Boulevard Lionel Boulet Varennes (Quebec), Canada J3X 1S2 (Canada); Manyala, N., E-mail: ncholu.manyala@up.ac.za [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa)

    2012-03-15

    Low field microwave absorption (LFMA) measurements at 9.4 GHz (X-band), were carried out on pulse laser deposited (PLD) polycrystalline B20 cubic structure FeSi thin film grown on Si (111) substrate. The LFMA properties of the films were investigated as a function of DC field, temperature, microwave power and the orientation of DC field with respect to the film surface. The LFMA signal is very strong when the DC field is parallel to the film surface and vanishes at higher angles. The LFMA signal strength increases as the microwave power is increased. The LFMA signal disappears around 340 K, which can be attributed to the disappearance of ferromagnetic state well above room temperature in these films. We believe that domain structure evolution in low fields, which in turn modifies the low field permeability as well as the anisotropy, could be the origin of the LFMA observed in these films. The observation of LFMA opens the possibility of the FeSi films to be used as low magnetic field sensors in the microwave and rf frequency regions. - Highlights: Black-Right-Pointing-Pointer B20 crystalline FeSi thin film shows low field microwave absorption. Black-Right-Pointing-Pointer Usual ferromagnic resonance typical of magnetic materials is observed in FeSi film. Black-Right-Pointing-Pointer FeSi film can be used for low magnetic field sensors.

  5. Terminating Ventricular Fibrillation Using Pulsed Far-Field Stimulation in Whole Rabbit Hearts

    Science.gov (United States)

    Squires, Amgad; Hornung, Daniel; Bittihn, Philip; Xia Wu, Dong; Krinsky, Valentin; Zabel, Markus; Bodenschatz, Eberhard; Luther, Stefan

    2010-03-01

    During life-threatening cardiac fibrillation, chaotic spatio-temporal dynamics is mediated by vortex-like rotating waves. Current defibrillation strategies rely on global control through high-energy shocks, which may have severe side-effects including traumatic pain and tissue damage. Far-field antifibrillation pacing terminates fibrillation using a train of low-energy electric pulses [1,2]. Using optical mapping in isolated rabbit heart preparations, we evaluate the efficiency and robustness of this approach. We found that a series of pulses at low energies (ventricular fibrillation with a success rate of 95%. We will discuss the physical mechanisms involved.[4pt] [1] F.H. Fenton et al, Circulation 120 467-476 (2009).[0pt] [2] A. Pumir et al., Phys. Rev. Lett. 99, 208101 (2007).

  6. Internal Magnetic Field, Temperature and Density Measurements on Magnetized HED plasmas using Pulsed Polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Roger J. [Univ. of Washington, Seattle, WA (United States)

    2016-10-20

    The goals were to collaborate with the MSX project and make the MSX platform reliable with a performance where pulsed polarimetry would be capable of adding a useful measurement and then to achieve a first measurement using pulsed polarimetry. The MSX platform (outside of laser blow off plasmas adjacent to magnetic fields which are low beta) is the only device that can generate high beta magnetized collisionless supercritical shocks, and with a large spatial size of ~10 cm. Creating shocks at high Mach numbers and investigating the dynamics of the shocks was the main goal of the project. The MSX shocks scale to astrophysical magnetized shocks and potentially throw light on the generation of highly energetic particles via a mechanism like the Fermi process.

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

    Science.gov (United States)

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

    2012-08-01

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

  8. General implementation of the ERETIC method for pulsed field gradient probe heads.

    Science.gov (United States)

    Ziarelli, Fabio; Viel, Stéphane; Caldarelli, Stefano; Sobieski, Daniel N; Augustine, Matthew P

    2008-10-01

    A capacitive coupling between a secondary radiofrequency (rf) channel and the gradient coil of a standard commercially available high resolution NMR spectrometer and probe head is described and used to introduce a low level exponentially damped rf signal near the frequency of the primary rf channel to serve as an external concentration standard, in analogy to the so-called ERETIC method. The stability of this inexpensive and simple to implement method, here referred to as the Pulse Into the Gradient (PIG) approach, is superb over a 14-h period and both gradient tailored water suppression and one-dimensional imaging applications are provided. Since the low level signal is introduced via the pulsed field gradient coil, the coupling is identical to that for a free induction signal and thus the method proves to be immune (within 5%) to sample ionic strength effects up to the 2M NaCl solutions explored here.

  9. Inactivation of Bacteria in Oil Field Injected Water by a Pulsed Plasma Discharge Process

    Science.gov (United States)

    Xin, Qing; Li, Zhongjian; Lei, Lecheng; Yang, Bin

    2016-09-01

    Pulsed plasma discharge was employed to inactivate bacteria in the injection water for an oil field. The effects of water conductivity and initial concentration of bacteria on elimination efficiency were investigated in the batch and continuous flow modes. It was demonstrated that Fe2+ contained in injection water could enhance the elimination efficiency greatly. The addition of reducing agent glutathione (GSH) indicated that active radicals generated by pulsed plasma discharges played an important role in the inactivation of bacteria. Moreover, it was found that the microbial inactivation process for both batch and continuous flow mode well fitted the model based on the Weibull's survival function. supported by Zhejiang Province Welfare Technology Applied Research Project of China (No. 2014C31137), National Natural Science Foundation of China (Nos. 21436007 and U1462201), and the Fundamental Research Funds for the Central Universities of China (No. 2015QNA4032)

  10. [Design and implementation of the pulse wave generator with field programmable gate array based on windkessel model].

    Science.gov (United States)

    Wang, Hao; Fu, Quanhai; Xu, Lisheng; Liu, Jia; He, Dianning; Li, Qingchun

    2014-10-01

    Pulse waves contain rich physiological and pathological information of the human vascular system. The pulse wave diagnosis systems are very helpful for the clinical diagnosis and treatment of cardiovascular diseases. Accurate pulse waveform is necessary to evaluate the performances of the pulse wave equipment. However, it is difficult to obtain accurate pulse waveform due to several kinds of physiological and pathological conditions for testing and maintaining the pulse wave acquisition devices. A pulse wave generator was designed and implemented in the present study for this application. The blood flow in the vessel was simulated by modeling the cardiovascular system with windkessel model. Pulse waves can be generated based on the vascular systems with four kinds of resistance. Some functional models such as setting up noise types and signal noise ratio (SNR) values were also added in the designed generator. With the need of portability, high speed dynamic response, scalability and low power consumption for the system, field programmable gate array (FPGA) was chosen as hardware platform, and almost all the works, such as developing an algorithm for pulse waveform and interfacing with memory and liquid crystal display (LCD), were implemented under the flow of system on a programmable chip (SOPC) development. When users input in the key parameters through LCD and touch screen, the corresponding pulse wave will be displayed on the LCD and the desired pulse waveform can be accessed from the analog output channel as well. The structure of the designed pulse wave generator is simple and it can provide accurate solutions for studying and teaching pulse waves and the detection of the equipments for acquisition and diagnosis of pulse wave.

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

    Science.gov (United States)

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

    2017-04-28

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

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

    Science.gov (United States)

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

    2017-06-01

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

  13. Decoupling of excitation and receive coils in pulsed magnetic resonance using sinusoidal magnetic field modulation

    Science.gov (United States)

    Tseytlin, Mark; Epel, Boris; Sundramoorthy, Subramanian; Tipikin, Dmitriy; Halpern, Howard J.

    2016-11-01

    In pulsed magnetic resonance, the excitation power is many orders of magnitude larger than that induced by the spin system in the receiving coil or resonator. The receiver must be protected during and immediately after the excitation pulse to allow for the energy stored in the resonator to dissipate to a safe level. The time during which the signal is not detected, the instrumental dead-time, can be shortened by using magnetically decoupled excitation and receive coils. Such coils are oriented, with respect to each other, in a way that minimizes the total magnetic flux produced by one coil in the other. We suggest that magnetically decoupled coils can be isolated to a larger degree by tuning them to separate frequencies. Spins are excited at one frequency, and the echo signal is detected at another. Sinusoidal magnetic field modulation that rapidly changes the Larmor frequency of the spins between the excitation and detection events is used to ensure the resonance conditions for both coils. In this study, the relaxation times of trityl-CD3 were measured in a field-modulated pulsed EPR experiment and compared to results obtained using a standard spin echo method. The excitation and receive coils were tuned to 245 and 256.7 MHz, respectively. Using an available rapid-scan, cross-loop EPR resonator, we demonstrated an isolation improvement of approximately 20-30 dB due to frequency decoupling. Theoretical analysis, numerical simulations, and proof-of-concept experiments demonstrated that substantial excitation-detection decoupling can be achieved. A pulsed L-band system, including a small volume bi-modal resonator equipped with modulation coils, was constructed to demonstrate fivefold dead-time reduction in comparison with the standard EPR experiment. This was achieved by detuning of the excitation and receive coils by 26 MHz and using sinusoidal modulation at 480 kHz.

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

    Science.gov (United States)

    Boulaaba, Annika; Egen, Nathalie; Klein, Günter

    2014-04-01

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

  15. The imprint of the crustal magnetic field on the thermal spectra and pulse profiles of isolated neutron stars

    CERN Document Server

    Perna, Rosalba; Pons, Jose' A; Rea, Nanda

    2013-01-01

    Isolated neutron stars (NSs) show a bewildering variety of astrophysical manifestations, presumably shaped by the magnetic field strength and topology at birth. Here, using state-of-the art calculations of the coupled magnetic and thermal evolution of NSs, we compute the thermal spectra and pulse profiles expected for a variety of initial magnetic field configurations. In particular, we contrast models with purely poloidal magnetic fields to models dominated by a strong internal toroidal component. We find that, while the former displays double peaked profiles and very low pulsed fractions, in the latter, the anisotropy in the surface temperature produced by the toroidal field often results in a single pulse profile, with pulsed fractions that can exceed the 50-60% level even for perfectly isotropic local emission. We further use our theoretical results to generate simulated "observed" spectra, and show that blackbody (BB) fits result in inferred radii that can be significantly smaller than the actual NS radi...

  16. Reduced field-of-view excitation using second-order gradients and spatial-spectral radiofrequency pulses.

    Science.gov (United States)

    Ma, Chao; Xu, Dan; King, Kevin F; Liang, Zhi-Pei

    2013-02-01

    The performance of multidimensional spatially selective radiofrequency (RF) pulses is often limited by their long duration. In this article, high-order, nonlinear gradients are exploited to reduce multidimensional RF pulse length. Specifically, by leveraging the multidimensional spatial dependence of second-order gradients, a two-dimensional spatial-spectral RF pulse is designed to achieve three-dimensional spatial selectivity, i.e., to excite a circular region-of-interest in a thin slice for reduced field-of-view imaging. Compared to conventional methods that use three-dimensional RF pulses and linear gradients, the proposed method requires only two-dimensional RF pulses, and thus can significantly shorten the RF pulses and/or improve excitation accuracy. The proposed method has been validated through Bloch equation simulations and phantom experiments on a commercial 3.0T MRI scanner.

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

    Science.gov (United States)

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

    2017-09-01

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

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

    Science.gov (United States)

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

    2010-03-01

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

  19. Re-evaluation, optimization, and multilaboratory validation of the PulseNet-standardized pulsed-field gel electrophoresis protocol for Listeria monocytogenes.

    Science.gov (United States)

    Halpin, Jessica L; Garrett, Nancy M; Ribot, Efrain M; Graves, Lewis M; Cooper, Kara L

    2010-03-01

    The PulseNet Methods Development and Validation Laboratory began a re-evaluation of the standardized pulsed-field gel electrophoresis (PFGE) protocols with the goal of optimizing their overall performance and robustness. Herein, we describe a stepwise evaluation of the PulseNet-standardized PFGE protocol for Listeria monocytogenes that led to the modification of several steps which significantly improved the overall appearance and reproducibility of the resulting PFGE data. These improvements included the following: (1) reducing the cell suspension concentration, (2) increasing lysozyme incubation temperature from 37 degrees C to 56 degrees C, and (3) decreasing the number of units of restriction enzymes AscI and ApaI. These changes were incorporated into a proposed protocol that was evaluated by 16 PulseNet participating laboratories, including 2 international participants. Results from the validation study indicated that the updated L. monocytogenes protocol is more robust than the original PulseNet-standardized protocol established in 1998 and this resulted in the official adoption of the new protocol into the PulseNet system in the spring of 2008. The modifications not only represent an improvement to the protocol but also describe procedural improvements that could be potentially applied to the PFGE analysis of other Gram-positive organisms.

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

    Science.gov (United States)

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

    2009-03-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

  2. AC measurement of heat capacity and magnetocaloric effect for pulsed magnetic fields.

    Science.gov (United States)

    Kohama, Yoshimitsu; Marcenat, Christophe; Klein, Thierry; Jaime, Marcelo

    2010-10-01

    A new calorimeter for measurements of the heat capacity and magnetocaloric effect of small samples in pulsed magnetic fields is discussed for the exploration of thermal and thermodynamic properties at temperatures down to 2 K. We tested the method up to μ(0)H=50 T, but it could be extended to higher fields. For these measurements we used carefully calibrated bare-chip Cernox(®) and RuO(2) thermometers, and we present a comparison of their performances. The monotonic temperature and magnetic field dependences of the magnetoresistance of RuO(2) allow thermometry with a precision as good as ±4 mK at T=2 K. To test the performance of our calorimeter, heat capacity and magnetocaloric effect for the spin-dimer compound Sr(3)Cr(2)O(8) and the triangular lattice antiferromagnet RbFe(MoO(4))(2) are presented.

  3. Irreversible magnetoporation of micro-organisms in high pulsed magnetic fields.

    Science.gov (United States)

    Novickij, Vitalij; Grainys, Audrius; Novickij, Jurij; Markovskaja, Svetlana

    2014-09-01

    Electroporation is an appealing way of stimulating living cells, which causes permanent or temporary nanoporosities in the structure of the biological objects. However, the technique has a disadvantage such as a requirement of contact between the electrodes and the cell medium. In this review, a methodology of contactless treatment of the biological objects using pulsed magnetic fields is proposed. The eukaryotic micro-organisms Achlya americana and Saprolegnia diclina have been used in the study and magnetic fields up to 7 T were applied, which caused effects similar to irreversible electroporation resulting in the death of the species. The proposed technique is applicable for different types of the biological cells or micro-organisms and possibly can be used in the area of cancer, antifungal treatment and other biotechnological fields.

  4. Studies on antioxidant enzymes in mice exposed to pulsed electromagnetic fields.

    Science.gov (United States)

    Eraslan, Gokhan; Bilgili, Ali; Akdogan, Mehmet; Yarsan, Ender; Essiz, Dinc; Altintas, Levent

    2007-02-01

    In this study, 56 female albino mice weighing 30-35 g were used. The animals were divided into a control and an experimental group. The animals in the experimental group were subjected to a pulsed electromagnetic field (PEMF) with a field magnitude of 50 Hz and 2 mT for 8h each day between 0900 and 1700 for 90 days. In both control and experimental groups, blood was sampled at 45, 60, and 90 days in heparinized tubes and erythrocyte malondialdehyde levels, and superoxide dismutase, glutathione peroxidase, catalase, and glucose-6-phosphate dehydrogenase activities were determined. The results revealed that the PEMF applied chronically within the given period and field magnitude does not cause oxidative damage.

  5. Field emission properties of amorphous GaN ultrathin films fabricated by pulsed laser deposition

    Institute of Scientific and Technical Information of China (English)

    WANG FengYing; WANG RuZhi; ZHAO Wei; SONG XueMei; WANG Bo; YAN Hui

    2009-01-01

    Amorphous gallium nitride (a-GaN) films with thicknesses of 5 and 300 nm are deposited on n-Si (100) substrates by pulsed laser deposition (PLD), and their field emission (FE) properties are studied. It shows that compared with thicker (300 nm) a-GaN film, better FE performance is obtained on ultrathin (5 nm) a-GaN film with a threshold field of 0.78 V/μm, which is the lowest value ever reported. Furthermore, the current density reaches 42 mA/cm~2 when the applied field is 3.72 V/μm. These experimental results unambiguously confirm Binh's theoretical analysis (Birth et al. Phys Rev Lett, 2000, 85(4): 864-867) that the FE performance would be prominently enhanced with the coating of an ultra-thin wide band-gap semiconductor film.

  6. Effect of structural steel ion plasma nitriding on material durability in pulsed high magnetic fields

    Science.gov (United States)

    Spirin, A. V.; Krutikov, V. I.; Koleukh, D. S.; Mamaev, A. S.; Paranin, S. N.; Gavrilov, N. V.; Kaigorodov, A. S.

    2017-05-01

    The work was aimed to study the influence of plasma nitriding on electrical and mechanical properties of structural steels and their durability in pulsed high magnetic field. The plates and cylindrical magnetic flux concentrators were made of several steel grades (30KhGS, 40Kh, 50KhGA, 38Kh2MYuA, and U8A), heat-treated, and subjected to the low-temperature (400, 500°C) plasma nitriding. Electrical and mechanical properties of materials, phase composition of steel surface layer, microstructure and microhardness profiles were investigated on the plates before and after plasma treatment. Microstructure and microhardness profiles across the subsurface layer of plasma treated and untreated concentrators applied for high magnetic field generation were also studied. Magnetic field of 50 T under tens of microseconds in duration inside the flux concentrators was generated by long-life outer coil.

  7. Nanoseconds field emitted current pulses from ZrC needles and field emitter arrays

    CERN Document Server

    Ganter, R; Betemps, R; Dehler, M; Gerber, T; Gobrecht, J; Gough, C; Johnson, M; Kirk, E; Knopp, G; Le Pimpec, F; Li, K; Paraliev, M; Pedrozzi, M; Rivkin, L; Schulz, L; Sehr, H; Wrulich, A F

    2006-01-01

    The properties of the electron source define the ultimate limit of the beam quality in linear accelerators like Free Electron Lasers (FEL). The goal is to develop an electron gun delivering beam emittance lower than current state of the art. Such a gun should reduce the cost and size of an X-ray Free Electron Laser (XFEL). In this paper we present two concepts of field emitter cathodes which could potentially produce low emittance beam. The first challenging parameter for such cathode is to emit peak current as high as 5 A. This is the minimum current requirement for the XFEL concept from Paul Scherrer Institut.1 Maximum current of 0.12 A and 0.58 A have been reached respectively with field emitter arrays (FEA) and single needle cathodes. Laser assisted field emission gave encouraging results to reach even higher peak current and to pre-bunch the beam.

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

    Science.gov (United States)

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

    2014-12-01

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

  9. Treatment of bone marrow edema of the talus with pulsed electromagnetic fields: outcomes in six patients.

    Science.gov (United States)

    Martinelli, Nicolò; Bianchi, Alberto; Sartorelli, Elena; Dondi, Alessandra; Bonifacini, Carlo; Malerba, Francesco

    2015-01-01

    Bone marrow edema (BME) of the talus is a rare, mostly self-limiting cause of foot and ankle pain. We sought to investigate in patients with idiopathic BME of the talus the effectiveness of pulsed electromagnetic fields and to determine the effect of this therapy on magnetic resonance imaging findings. Six patients with BME of the talus confirmed by magnetic resonance imaging were enrolled. Pain was quantified with a visual analog scale from 0 (no pain) to 10 (the worst pain imaginable). The clinical outcome was assessed using the American Orthopaedic Foot and Ankle Society scoring system. Treatment consisted of pulsed electromagnetic field stimulation 8 h/d for 30 days. The device used generated pulses 1.3 milliseconds in duration, with a frequency of 75 Hz and a mean ± SD induced electric field of 3.5 ± 0.5 mV. The mean American Orthopaedic Foot and Ankle Society score improved from 59.4 (range, 40-66) before treatment to 94 (range, 80-100) at the last follow-up. The visual analog scale score decreased significantly from 5.6 (range, 4-7) before treatment to 1 (range, 0-2) at the last follow-up. Magnetic resonance imaging showed that BME improved after 1 month of treatment and resolved completely within 3 months in 5 patients, with normal signal intensity and no signs of progression to avascular necrosis. A significant reduction in BME area was associated with a significant decrease in pain within 3 months of beginning treatment.

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

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    陈雅; 王彦; 孙彤; 张锦珠; 景向红; 李瑞午

    2000-01-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Linying Liu

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

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Flux jumps in high-J c MgB2 bulks during pulsed field magnetization

    Science.gov (United States)

    Fujishiro, H.; Mochizuki, H.; Naito, T.; Ainslie, M. D.; Giunchi, G.

    2016-03-01

    Pulsed field magnetization (PFM) of a high-J c MgB2 bulk disk has been investigated at 20 K, in which flux jumps frequently occur for high pulsed fields. Using a numerical simulation of the PFM procedure, we estimated the time dependence of the local magnetic field and temperature during PFM. We analyzed the electromagnetic and thermal instability of the high-J c MgB2 bulk to avoid flux jumps using the time dependence of the critical thickness, d c(t), which shows the upper safety thickness to stabilize the superconductor magnetically, and the minimum propagation zone length, l m(t), to obtain dynamical stability. The values of d c(t) and l m(t) change along the thermally-stabilized direction with increasing temperature below the critical temperature, T c. However, the flux jump can be qualitatively understood by the local temperature, T(t), which exceeds T c in the bulk. Finally, possible solutions to avoid flux jumps in high-J c MgB2 bulks are discussed.

  16. Switching of chiral magnetic skyrmions by picosecond magnetic field pulses via transient topological states

    Science.gov (United States)

    Heo, Changhoon; Kiselev, Nikolai S.; Nandy, Ashis Kumar; Blügel, Stefan; Rasing, Theo

    2016-06-01

    Magnetic chiral skyrmions are vortex like spin structures that appear as stable or meta-stable states in magnetic materials due to the interplay between the symmetric and antisymmetric exchange interactions, applied magnetic field and/or uniaxial anisotropy. Their small size and internal stability make them prospective objects for data storage but for this, the controlled switching between skyrmion states of opposite polarity and topological charge is essential. Here we present a study of magnetic skyrmion switching by an applied magnetic field pulse based on a discrete model of classical spins and atomistic spin dynamics. We found a finite range of coupling parameters corresponding to the coexistence of two degenerate isolated skyrmions characterized by mutually inverted spin structures with opposite polarity and topological charge. We demonstrate how for a wide range of material parameters a short inclined magnetic field pulse can initiate the reliable switching between these states at GHz rates. Detailed analysis of the switching mechanism revealed the complex path of the system accompanied with the excitation of a chiral-achiral meron pair and the formation of an achiral skyrmion.

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

    Science.gov (United States)

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

    2009-12-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  19. Influence of Pulsed Electromagnetic Field on Plant Growth, Nutrient Absorption and Yield of Durum Wheat

    Directory of Open Access Journals (Sweden)

    Nikolaos KATSENIOS

    2015-12-01

    Full Text Available Researchers have adopted the use of magnetic field as a new pre-sowing, environmental friendly technique. Enhancements on plant characteristics with economic impact on producer’s income could be the future of a modern, organic and sustainable agriculture. A field experiment was established at Soil Science Institute of Athens, Lycovrissi, Greece, in the winter of 2014. Two durum wheat cultivars were used. It was a pot experiment with 6 treatments (2 cultivars with 3 magnetic field time exposure. The seeds were treated using a PAPIMI electromagnetic field generator for 0, 30 and 45 minutes one day before planting. The experiment followed a completely randomized design with six treatments and 30 replications. The aim of this study was to evaluate the positive effect of magnetic field pre-sowing treatment in a wide range of plant measurements, including yield. The influence of pulsed electromagnetic field on two varieties of durum wheat seeds showed some statistically significant differences at the 0.05 level in growth measurements, physiological measurements and root growth measurements. Plant tissue analysis showed that magnetic field treatments had higher values than control in total nitrogen, phosphorus, potassium, magnesium, copper (only MF-45, zinc (only MF-30 and boron content, although values showed statistically significant differences only in total nitrogen. The results indicate that this innovative technique can increase the yield of durum wheat, through enhanced absorption of nutrients. Pre-sowing treatment of the seeds leads to vigorous plant growth that are more productive.

  20. Amplification of 126 nm femtosecond seed pulses in optical-field-induced Ar plasma filamentation

    Science.gov (United States)

    Kubodera, Shoichi; Deshimaru, Naoyuki; Kaku, Masanori; Katto, Masahito

    2014-10-01

    We have observed amplification of femtosecond (fs) VUV coherent seed beam at 126 nm by utilizing an optical-field-induced ionization (OFI) high-pressure Ar plasma filamentation. We have produced a low-temperature and high-density Ar plasma filamentation inside a high-pressure Ar cell by irradiating a high-intensity laser with an intensity of approximately 1014 W cm-2. Argon excimer molecules (Ar2*) as an amplifier medium were produced inside the high-pressure cell and were used to amplify a weak VUV ultrashort seed pulse at 126 nm, which was generated by harmonic generation of another short pulse infrared laser at 882 nm. We have measured the amplification characteristics and the OFI plasma diagnosis by utilizing the fs VUV pulses at 126 and 882 nm, respectively. The maximum optical gain value of 1.1 cm-1 was observed. Temporal behaviors of the plasma temperature and density in the nano-second time scale indicated a high-density and low-temperature plasma produced by using the OFI. These plasma behaviors were utilized to reproduce the optical amplification characteristics with our OFI excimer simulation code.