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Sample records for micro electrical field

  1. Electric fields in micro-gravity can replace gravity

    NASA Astrophysics Data System (ADS)

    Gorgolewski, S.

    The influence of the world-wide atmospheric electric field on the growth of plants seems to have been neglected. The confirmation of the existence of electrotropism shows effects on some plants similar to gravity. I propose space ex eriments withp plants that grow in microgravity but are exposed to different electric field configurations with various field strengths and polarity. The electric field in terrestrial environment shows strong effects on some plants that can be regarded as due to phototropism. In microgravity we have full control of light and electric field, and thus we can practically eliminate the effects of gravity and we can study to what degree the electric field can replace the gravitational effects on plants. In this way we can create a new habitat for some plants and study its role in the rate of growth as well as in the sensing of free space for growth of plants in absence of gravity. By varying the strength and direction of illumination of plants we can also study the relative role of phototropism and electrotropism on different plants. This should enable us to select the most suitable plants for Advanced Life Support systems (ALS) for long-duration missions in microgravity environment. Some simple space experiments for verification of these assumptions are described that should answer the basic questions how should we design the ALS for the future high performance space stations and long duration manned space flights. The selection of the suitable plants for such ALS may go along two approaches: the self supporting electrotropic plants using the optimal electric field strength and its range of variation, non electrotropic plants that creep along the "ground" or other supporting plants or special structures. Ground based fitotron experiments have shown that several kV/m electric fields overwhelm the gravity better than clinostats can do. It happens in case of electrotropic plants but also after several days for non-electrotropic plants

  2. Electric micro fields in simulated two component plasmas

    SciTech Connect

    Calisti, A.; Talin, B.; Ferri, S.; Mosse, C.; Lisitsa, V.; Bureyeva, L.; Gigosos, M. A.; Gonzalez, M. A.; Rio Gaztelurrutia, T. del

    2008-10-22

    The statistical properties of local electric fields in an classical plasma are investigated by molecular dynamics (MD) simulation. Two-component plasma simulations of neutral hydrogen, protons and electrons for intermediate plasma coupling conditions, typically N{sub e}{approx_equal}10{sup 18}cm{sup -3}, T{sub e}{approx_equal}1eV, have been carried out. These simulations appear as a possible and very useful way to generate relevant microfield sample-sets appropriate for ion emitter lineshape simulations for plasma spectroscopy and to provide guidance for line shape modeling.

  3. High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm.

    PubMed

    Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

    2015-10-28

    The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection.

  4. High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm

    PubMed Central

    Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

    2015-01-01

    The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection. PMID:26507680

  5. High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm

    NASA Astrophysics Data System (ADS)

    Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

    2015-10-01

    The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection.

  6. Electric-field-driven Phenomena for Manipulating Particles in Micro-Devices

    NASA Technical Reports Server (NTRS)

    Khusid, Boris; Acrivos, Andreas

    2004-01-01

    Compared to other available methods, ac dielectrophoresis is particularly well-suited for the manipulation of minute particles in micro- and nano-fluidics. The essential advantage of this technique is that an ac field at a sufficiently high frequency suppresses unwanted electric effects in a liquid. To date very little has been achieved towards understanding the micro-scale field-and shear driven behavior of a suspension in that, the concepts currently favored for the design and operation of dielectrophoretic micro-devices adopt the approach used for macro-scale electric filters. This strategy considers the trend of the field-induced particle motions by computing the spatial distribution of the field strength over a channel as if it were filled only with a liquid and then evaluating the direction of the dielectrophoretic force, exerted on a single particle placed in the liquid. However, the exposure of suspended particles to a field generates not only the dielectrophoretic force acting on each of these particles, but also the dipolar interactions of the particles due to their polarization. Furthermore, the field-driven motion of the particles is accompanied by their hydrodynamic interactions. We present the results of our experimental and theoretical studies which indicate that, under certain conditions, these long-range electrical and hydrodynamic interparticle interactions drastically affect the suspension behavior in a micro-channel due to its small dimensions.

  7. Accelerated Detection of Viral Particles by Combining AC Electric Field Effects and Micro-Raman Spectroscopy

    PubMed Central

    Tomkins, Matthew Robert; Liao, David Shiqi; Docoslis, Aristides

    2015-01-01

    A detection method that combines electric field-assisted virus capture on antibody-decorated surfaces with the “fingerprinting” capabilities of micro-Raman spectroscopy is demonstrated for the case of M13 virus in water. The proof-of-principle surface mapping of model bioparticles (protein coated polystyrene spheres) captured by an AC electric field between planar microelectrodes is presented with a methodology for analyzing the resulting spectra by comparing relative peak intensities. The same principle is applied to dielectrophoretically captured M13 phage particles whose presence is indirectly confirmed with micro-Raman spectroscopy using NeutrAvidin-Cy3 as a labeling molecule. It is concluded that the combination of electrokinetically driven virus sampling and micro-Raman based signal transduction provides a promising approach for time-efficient and in situ detection of viruses. PMID:25580902

  8. Micro-resonator-based electric field sensors with long durations of sensitivity

    NASA Astrophysics Data System (ADS)

    Ali, Amir R.

    2017-05-01

    In this paper, we present a new fabrication method for the whispering gallery mode (WGM) micro-sphere based electric field sensor that which allows for longer time periods of sensitivity. Recently, a WGM-based photonic electric field sensor was proposed using a coupled dielectric microsphere-beam. The external electric field imposes an electrtrostriction force on the dielectric beam, deflecting it. The beam, in turn compresses the sphere causing a shift in its WGM. As part of the fabrication process, the PDMS micro-beams and the spheres are curied at high-temperature (100oC) and subsequently poled by exposing to strong external electric field ( 8 MV/m) for two hours. The poling process allows for the deposition of surface charges thereby increasing the electrostriction effect. This methodology is called curing-then-poling (CTP). Although the sensors do become sufficiently sensitive to electric field, they start de-poling after a short period (within 10 minutes) after poling, hence losing sensitivity. In an attempt to mitigate this problem and to lock the polarization for a longer period, we use an alternate methodology whereby the beam is poled and cured simultaneously (curing-while-poling or CWP). The new fabrication method allows for the retention of polarization (and hence, sensitivity to electric field) longer ( 1500 minutes). An analysis is carried out along with preliminary experiments. Results show that electric fields as small as 100 V/m can be detected with a 300 μm diameter sphere sensor a day after poling.

  9. Micro bubble condensation in micro channel controlled by local electrical field method

    NASA Astrophysics Data System (ADS)

    Ohata, Shunsuke; Kawai, Akira

    2009-12-01

    Micro bubbles in several tens micrometer diameter can act as effective structural elements of micro devices. In this study, the micro device employing the bubble motion is characterized. It has been experimentally revealed that bubble motion in micro channel is trapped at the channel branches. The local electrodes are set at a part of micro channel in order to control the bubble motion. Negatively charged bubble surface is received a certain force due to Coulomb's effect. This study will provide effective information to bioscience, medical science and agriculture engineering.

  10. Effects of electric field on micro-scale flame properties of biobutanol fuel

    PubMed Central

    Xu, Tao; Chen, Qinglin; Zhang, Bingjian; Lu, Shushen; Mo, Dongchuan; Zhang, Zhengguo; Gao, Xuenong

    2016-01-01

    With the increasing need of smaller power sources for satellites, energy systems and engine equipment, microcombustion pose a potential as alternative power source to conventional batteries. As the substitute fuel source for gasoline, biobutanol shows more promising characteristics than ethanol. In this study, the diffusion microflame of liquid biobutanol under electric field have been examined through in-lab experiment and numerical simulation. It is found that traditional gas jet diffusion flame theory shows significant inconsistency with the experimental results of micro scale flame in electric field. The results suggest that with the increase of electric field intensity, the quenching flow rate decrease first and increase after it reach its minimum, while the flame height and highest flame temperature increase first and drop after its peak value. In addition, it was also observed that the flame height and highest temperature for smaller tube can reach its maximum faster. Therefore, the interaction between microscale effect and electric field plays a significant role on understanding the microcombustion of liquid fuel. Therefore, FLUENT simulation was adopted to understand and measure the impacts of microflame characteristic parameters. The final numerical results are consistent with the experimental data and show a high reliability. PMID:27609428

  11. Effects of electric field on micro-scale flame properties of biobutanol fuel

    NASA Astrophysics Data System (ADS)

    Xu, Tao; Chen, Qinglin; Zhang, Bingjian; Lu, Shushen; Mo, Dongchuan; Zhang, Zhengguo; Gao, Xuenong

    2016-09-01

    With the increasing need of smaller power sources for satellites, energy systems and engine equipment, microcombustion pose a potential as alternative power source to conventional batteries. As the substitute fuel source for gasoline, biobutanol shows more promising characteristics than ethanol. In this study, the diffusion microflame of liquid biobutanol under electric field have been examined through in-lab experiment and numerical simulation. It is found that traditional gas jet diffusion flame theory shows significant inconsistency with the experimental results of micro scale flame in electric field. The results suggest that with the increase of electric field intensity, the quenching flow rate decrease first and increase after it reach its minimum, while the flame height and highest flame temperature increase first and drop after its peak value. In addition, it was also observed that the flame height and highest temperature for smaller tube can reach its maximum faster. Therefore, the interaction between microscale effect and electric field plays a significant role on understanding the microcombustion of liquid fuel. Therefore, FLUENT simulation was adopted to understand and measure the impacts of microflame characteristic parameters. The final numerical results are consistent with the experimental data and show a high reliability.

  12. Effects of electric field on micro-scale flame properties of biobutanol fuel.

    PubMed

    Xu, Tao; Chen, Qinglin; Zhang, Bingjian; Lu, Shushen; Mo, Dongchuan; Zhang, Zhengguo; Gao, Xuenong

    2016-09-09

    With the increasing need of smaller power sources for satellites, energy systems and engine equipment, microcombustion pose a potential as alternative power source to conventional batteries. As the substitute fuel source for gasoline, biobutanol shows more promising characteristics than ethanol. In this study, the diffusion microflame of liquid biobutanol under electric field have been examined through in-lab experiment and numerical simulation. It is found that traditional gas jet diffusion flame theory shows significant inconsistency with the experimental results of micro scale flame in electric field. The results suggest that with the increase of electric field intensity, the quenching flow rate decrease first and increase after it reach its minimum, while the flame height and highest flame temperature increase first and drop after its peak value. In addition, it was also observed that the flame height and highest temperature for smaller tube can reach its maximum faster. Therefore, the interaction between microscale effect and electric field plays a significant role on understanding the microcombustion of liquid fuel. Therefore, FLUENT simulation was adopted to understand and measure the impacts of microflame characteristic parameters. The final numerical results are consistent with the experimental data and show a high reliability.

  13. Vibrations of micro-beams actuated by an electric field via Parameter Expansion Method

    NASA Astrophysics Data System (ADS)

    Sedighi, Hamid M.; Shirazi, Kourosh H.

    2013-04-01

    This paper presents a new asymptotic procedure to predict the nonlinear vibrational behavior of micro-beams pre-deformed by an electric field. The nonlinear equation of motion includes both even and odd nonlinearities. A powerful analytical method called Parameter Expansion Method (PEM) is employed to obtain the approximated solution and frequency-amplitude relationship. It is demonstrated that the first two terms in series expansions are sufficient to produce an acceptable solution of mentioned system. The obtained results from numerical methods verify the soundness of the analytical procedure. Finally, the influences of basic parameters on pull-in instability and natural frequency are investigated.

  14. Measurement of electric fields in a helium micro-hollow cathode discharge by forbidden transitions

    NASA Astrophysics Data System (ADS)

    Namba, Shinichi; Maki, Daisuke; Takiyama, Ken

    2013-09-01

    Micro-hollow cathode discharges operated at high pressure has been attracting a great deal of interest for various application, such as, excimer light sources, medical/biological fields and microchemical reactor. In the plasmas, the electric (E) field in the sheath region plays an important role to generate and sustain the plasmas. In order to determine the E field in the He microplasma, the emissions of allowed (He I 2P-4D: 492.19 nm) and forbidden (2P-4F: 492.06 nm) lines were observed. The cathode and anode were both made of brass, and ceramic disks were used to electrically insulate the electrodes. The cathode disk had inner hole diameter of 1.0 mm (length: 2.0 mm). The gas with a flow rate was 1.0 L/min. The discharge was operated at voltages of 250 V, currents of 8 mA and gas pressures up to 100 kPa. The plasmas in the cathode opening were observed using a visible spectrometer. The forbidden line associated with the level mixing of upper levels was observed in the cathode surface, indicating that the high E field was formed. As the intensity ratio of forbidden to the allowed lines is a function of the E field which is calculated by perturtabation theory, we derived the field strength of 18 kV/cm at 1.0 mm cathode surface.

  15. Electric Field Induced Stable Micro Rotor in Nematic Liquid Crystal Drops Constrained on Thin Cellulosic Fibers

    NASA Astrophysics Data System (ADS)

    Godinho, Maria Helena; Geng, Yong; Almeida, Pedro; Figueirinhas, João; Terentjev, Eugene

    2012-02-01

    We directly visualize the response of nematic liquid crystal drops of toroidal topology constrained on thin fibers, suspended in air, to an AC applied electric field E. This new localized liquid crystal system can exhibit non-trivial point defects, which may become energetically unstable against expanding into ring disclinations depending on the fiber constraining geometries. The director anchoring tangential near the fiber surface and homeotropic at the air interface, making a hybrid shell distribution that in turn causes a ring of disclination line around the main axis of the fiber at the center of the droplet. Upon application of E, the disclination ring first expands and slightly moves along the fiber main axis, followed by the appearance of a stable ``spherical particle'' orbiting around the fiber at the center of the liquid crystal drop. The rotation speed of this particle was found to vary linearly with the applied voltage. This constrained liquid crystal geometry seems to meet the essential requirements in which soliton like particles can develop and exhibit stable orbiting in three dimensions upon application of an external electric field. This is another example of a soft energy transducer system which allows, at the micro scale, the transfer in a continuous way of electrical to mechanical energy.

  16. On the electric micro-field in plasmas: statistics of the spatial derivatives

    SciTech Connect

    Guerricha, S.; Chihi, S.; Meftah, M. T.

    2008-10-22

    Using the Monte-Carlo simulation we calculated for some specific plasmas, the distribution functions of the derivatives of the micro-field components. Some of them are compared to those calculated earlier by other authors.

  17. Zeta-potential Analyses using Micro Electrical Field Flow Fractionation with Fluorescent Nanoparticles

    PubMed Central

    Chang, Moon-Hwan; Dosev, Dosi; Kennedy, Ian M.

    2007-01-01

    Increasingly growing application of nanoparticles in biotechnology requires fast and accessible tools for their manipulation and for characterization of their colloidal properties. In this work we determine the zeta-potentials for polystyrene nanoparticles using micro electrical field flow fractionation (μ–EFFF) which is an efficient method for sorting of particles by size. The data obtained by μ–EFFF were compared to zeta potentials determined by standard capillary electrophoresis. For proof of concept, we used polystyrene nanoparticles of two different sizes, impregnated with two different fluorescent dyes. Fluorescent emission spectra were used to evaluate the particle separation in both systems. Using the theory of electrophoresis, we estimated the zeta-potentials as a function of size, dielectric permittivity, viscosity and electrophoretic mobility. The results obtained by the μ–EFFF technique were confirmed by the conventional capillary electrophoresis measurements. These results demonstrate the applicability of the μ–EFFF method not only for particle size separation but also as a simple and inexpensive tool for measurements of nanoparticles zeta potentials. PMID:18542710

  18. Laser micro-machinability of borosilicate glass surface-modified by electric field-assisted ion-exchange method

    NASA Astrophysics Data System (ADS)

    Matsusaka, S.; Kobayakawa, T.; Hidai, H.; Morita, N.

    2012-08-01

    In order to improve the laser micro-machinability of borosilicate glass, the glass surface was doped with metal (silver or copper) ions by an electric field-assisted ion-exchange method. Doped ions drifted and diffused into the glass substrate under a DC electric field. The concentration of metal ions within the doped area was approximately constant because the ion penetration was caused by substitution between dopant metal and inherent sodium ions. Nanosecond ultraviolet laser irradiation of metal-containing regions produced flat, smooth and defect-free holes. However, the shapes of holes were degraded when the processed hole bottoms reached ion penetration depths. A numerical analysis of ionic drift-diffusion behaviour in glass material under an electric field was also carried out. The calculated results for penetration depth and ionic flux showed good agreement with the measured values.

  19. Micro-ARES, an electric-field sensor for ExoMars 2016: Electric fields modelling, sensitivity evaluations and end-to-end tests.

    NASA Astrophysics Data System (ADS)

    Déprez, Grégoire; Montmessin, Franck; Witasse, Olivier; Lapauw, Laurent; Vivat, Francis; Abbaki, Sadok; Granier, Philippe; Moirin, David; Trautner, Roland; Hassen-Khodja, Rafik; d'Almeida, Éric; Chardenal, Laurent; Berthelier, Jean-Jacques; Esposito, Francesca; Debei, Stefano; Rafkin, Scott; Barth, Erika

    2014-05-01

    For the past few years, LATMOS has been involved in the development of micro-ARES, an electric field sensor part of the science payload (DREAMS) of the ExoMars 2016 Schiaparelli entry, descent and landing demonstrator. It is dedicated to the very first measurement and characterization of the Martian atmospheric electricity which is suspected to be at the very basis of various phenomenon such as dust lifting, formation of oxidizing agents or Schumann resonances. Although the data collection will be restricted to a few days of operations, these first results will be of importance to understand the Martian dust cycle, the electrical environment and possibly relevant to atmospheric chemistry. The instrument, a compact version of the ARES instrument for the ExoMars Humboldt payload, is composed of an electronic board, with an amplification line and a real-time data processing DSP, which handles the electric signal measured between the spherical electrode (located at the top of a 27-cm high antenna) that adjusts itself to the local atmospheric potential, and the lander chassis, connected to the mechanical ground. Since the electric fields on Mars have never been measured before, we can rely on two sources in order to know their expected order of magnitude. The first one is the measurement of the atmospheric electric fields on Earth, at the surface (in dust storms or the so-called dust-devils) or in the high atmosphere (closer to the Martian temperature and pressure conditions). The second one is the computer simulation of the phenomenon, that we obtained by combining two models. On the one hand, the mesoscale PRAMS model, developed at SwRI, which has the ability to simulate the dust transportation, and on the other hand the implementation made at LATMOS of Farell's 2005 dust-triboelectricity equations. Those models allowed us to simulate electric fields up to tens or even hundreds of kilo-volts per meter inside dust devils, which corresponds to the observations made on

  20. Composite electric field guided assembly of nano/bio materials: Fluidics controlled regime for micro/nano assembly

    NASA Astrophysics Data System (ADS)

    Chung, Jaehyun

    Nanoscale particles exhibit unique phenomena that enable extremely sensitive sensors and molecular electronic devices. The immobilization of nano/bio materials on electrodes is an essential issue needed to be addressed in order to accomplish such devices. Also, the devices often need to be assembled through the use of micromachining technology to facilitate the implementation of mechanical/electrical/chemical functions in the nano- and/or micro-dimension. Based on this concept, an array assembly method involving an electric field was accomplished through the work presented in this thesis. The technique developed here was successfully applied to multi-walled carbon nanotubes (MWCNTs), single walled carbon nanotubes (SWCNTs) and DNA molecules. A composite electric field guided assembly method (CEGA) was developed to integrate individual MWCNTs on electrodes and to stretch a single strand lambda-DNA molecule on a gap. The CEGA approach, combining an ac with a dc e-field, was found to successfully manipulate and control the dielectrophoretic and drag force. The fabrication of nanoscale electrodes is another issue relevant to molecular devices. A technique for the fabrication of nanoscale electrodes, using a MWCNT as a shadow mask, was developed to create a ˜20nm gap. Individual MWCNTs were assembled on the nanoscale electrode by taking advantage of the CEGA method, and its highest packing density was compared with other CNT assembly technologies. As a potential application of the CEGA approach, a gas sensor using a multi-walled carbon nanotube (MWCNT) was developed. The electrical resistances of large diameter MWCNTs were found to decrease in the presence of air, after experiencing electrical breakdown, while pristine MWCNTs were not appreciably sensitive. Also, a glucose sensor was developed to specifically detect hydrogen gas (H2) diffused from a glucose oxidation reaction. The sensor was composed of metallic MWCNT bundles deposited using an ac electric field

  1. Micro electric propulsion feasibility

    NASA Technical Reports Server (NTRS)

    Aston, Graeme; Aston, Martha

    1992-01-01

    , minimal detectability and low cost are requirements. All these miniature spacecraft share a common characteristic: because of their on-board electronic equipment they have, by design, solar order 50-100 W. In a relative sense, such spacecraft are power rich when compared to other larger spacecraft. This power rich situation is offset by very tight mass budgets, which make reductions in propellant mass requirements a key issue in meeting overall spacecraft minimum mass goals. In principle, power rich and propellant poor brilliant pebbles class spacecraft can benefit from using high specific impulse electric propulsion to reduce chemical propellant mass requirements. However, at power levels of order 50 W, arcjets cannot be made to function, ion thrusters are too complex and heavy and resistojets have too low a specific impulse. Recognizing these capability limitations in existing electric propulsion technology, the SDIO/IST sponsored the Phase I SBIR Micro Electric Propulsion (MEP) thruster study described in this report. The objective of this study was to examine the feasibility of developing a very simple, low mass and small volume, electric thruster for operation on hydrazine at less than 100 W of input power. The feasibility of developing such a MEP thruster was successfully demonstrated by EPL by the discovery of a novel plasma acceleration process. The sections in this report summarize the approach, test results and major accomplishments of this proof-of-concept program.

  2. Micro electric propulsion feasibility

    NASA Astrophysics Data System (ADS)

    Aston, Graeme; Aston, Martha

    1992-11-01

    , minimal detectability and low cost are requirements. All these miniature spacecraft share a common characteristic: because of their on-board electronic equipment they have, by design, solar order 50-100 W. In a relative sense, such spacecraft are power rich when compared to other larger spacecraft. This power rich situation is offset by very tight mass budgets, which make reductions in propellant mass requirements a key issue in meeting overall spacecraft minimum mass goals. In principle, power rich and propellant poor brilliant pebbles class spacecraft can benefit from using high specific impulse electric propulsion to reduce chemical propellant mass requirements. However, at power levels of order 50 W, arcjets cannot be made to function, ion thrusters are too complex and heavy and resistojets have too low a specific impulse. Recognizing these capability limitations in existing electric propulsion technology, the SDIO/IST sponsored the Phase I SBIR Micro Electric Propulsion (MEP) thruster study described in this report. electric thruster for operation on hydrazine at less than 100 W of input power. &The feasibility of developing such a MEP thruster was successfully demonstrated by EPL by the discovery of a novel plasma acceleration process. The sections in this report summarize the approach, test results and major accomplishments of this proof-of-concept program.

  3. Pulsed electric field processing of different fruit juices: impact of pH and temperature on inactivation of spoilage and pathogenic micro-organisms.

    PubMed

    Timmermans, R A H; Nierop Groot, M N; Nederhoff, A L; van Boekel, M A J S; Matser, A M; Mastwijk, H C

    2014-03-03

    Pulsed electrical field (PEF) technology can be used for the inactivation of micro-organisms and therefore for preservation of food products. It is a mild technology compared to thermal pasteurization because a lower temperature is used during processing, leading to a better retention of the quality. In this study, pathogenic and spoilage micro-organisms relevant in refrigerated fruit juices were studied to determine the impact of process parameters and juice composition on the effectiveness of the PEF process to inactivate the micro-organisms. Experiments were performed using a continuous-flow PEF system at an electrical field strength of 20 kV/cm with variable frequencies to evaluate the inactivation of Salmonella Panama, Escherichia coli, Listeria monocytogenes and Saccharomyces cerevisiae in apple, orange and watermelon juices. Kinetic data showed that under the same conditions, S. cerevisiae was the most sensitive micro-organism, followed by S. Panama and E. coli, which displayed comparable inactivation kinetics. L. monocytogenes was the most resistant micro-organism towards the treatment conditions tested. A synergistic effect between temperature and electric pulses was observed at inlet temperatures above 35 °C, hence less energy for inactivation was required at higher temperatures. Different juice matrices resulted in a different degree of inactivation, predominantly determined by pH. The survival curves were nonlinear and could satisfactorily be modeled with the Weibull model.

  4. Electric Field Imaging Project

    NASA Technical Reports Server (NTRS)

    Wilcutt, Terrence; Hughitt, Brian; Burke, Eric; Generazio, Edward

    2016-01-01

    NDE historically has focused technology development in propagating wave phenomena with little attention to the field of electrostatics and emanating electric fields. This work is intended to bring electrostatic imaging to the forefront of new inspection technologies, and new technologies in general. The specific goals are to specify the electric potential and electric field including the electric field spatial components emanating from, to, and throughout volumes containing objects or in free space.

  5. Histopathological follow-up by tissue micro-array in a survival study after melanoma treated by nanosecond pulsed electric fields (nsPEF).

    PubMed

    Chen, Xinhua; Chen, Xinmei; Swanson, R James; Schoenbach, Karl H; Yin, Shengyong; Zheng, Shusen

    2011-06-01

    A recent study has shown that nanosecond pulsed electric fields (nsPEF) can affect the intracellular structures of melanoma within weeks. nsPEF is a non-drug, non-thermal treatment using ultrashort, intense pulsed electric fields with nanosecond durations. In the current study we followed up melanoma histopathology and metastasis with tissue micro-array 5 months post-nsPEF. After nsPEF treatment, tumor growth, tumor histology, metastasis, peri-tumor vessel and micro-vessel density were examined for the effect of nsPEF treatment on melanoma in vivo. The 17 nsPEF-treated mice were tumor-free for 169 days, significantly longer than those 19 control mice bearing melanoma without nsPEF. Histopathology follow-up showed that melanoma did not recur to the primary injection place after complete elimination. Compared with the control tumor, nsPEF-treated tumors present decreased micro-vessel density in a time-course manner in this survival study. Treatment with nsPEF caused continuous histopathological changes in melanomas, eliminated melanoma without recurrence at the primary site and prolonged animal survival time by inhibiting tumor blood supply and leading to tumor infarction. Thus, nsPEF could be applied in a non-ionizing therapeutic approach, without other agents, to locally treat tumors within a defined boundary.

  6. The role of electro-osmosis and dielectrophoresis in collection of micro/nano size particles in low frequency AC electric field

    NASA Astrophysics Data System (ADS)

    Wei, Chehung; Hsu, Che-Wei; Wang, Ching-Chieh

    2007-09-01

    The collecting and sorting micro size particles by electric force is easy to integrate with other bioassays. There are many forms of electric forces such as electrophoresis, dielectrophoresis and electroosmosis which can be used to manipulate particles. In an attempt to understand the role of electroosmosis and dielectrophoresis in the collection of micro size particles, a small device made of two parallel plates is used to study the particle movement under AC electric field. The device is fabricated by a top electrode and a bottom electrode separated by a spacer. The top electrode is made from an ITO glass where the bottom electrode is made of Corning 1737 glass sputtered with chromium. A dielectric layer is fabricated by spin coating a thin photo-resist (0.5~1μm) on the bottom electrode and a spacer made of curing PDMS is utilized to separate these electrodes. A 900μm × 900μm collecting chamber is fabricated on the bottom electrode via photolithography. The amine-modified polystyrene fluorescent particles whose average size is 1 μm were used for collection experiments. Different frequency and power were applied to generate the non-uniform electric field. It was found that frequency is the critical factor for electroosmotic velocity. There seems to be an optimum frequency that leads to largest particle velocity. The underlying mechanism is believed to the competing forces among dielectrophoresis and electroosmosis. This device demonstrates that the electroosmosis force is suitable for collecting bio-particles in AC electric field.

  7. E. coli electroeradication on a closed loop circuit by using milli-, micro- and nanosecond pulsed electric fields: comparison between energy costs.

    PubMed

    Guionet, Alexis; David, Fabienne; Zaepffel, Clément; Coustets, Mathilde; Helmi, Karim; Cheype, Cyril; Packan, Denis; Garnier, Jean-Pierre; Blanckaert, Vincent; Teissié, Justin

    2015-06-01

    One of the different ways to eradicate microorganisms, and particularly bacteria that might have an impact on health consists in the delivery of pulsed electric fields (PEFs). The technologies of millisecond (ms) or microsecond (μs) PEF are still well known and used for instance in the process of fruit juice sterilization. However, this concept is costly in terms of delivered energy which might be too expensive for some other industrial processes. Nanosecond pulsed electric fields (nsPEFs) might be an alternative at least for lower energetic cost. However, only few insights were available and stipulate a gain in cost and in efficiency as well. Using Escherichia coli, the impact of frequency and low rate on eradication and energy consumption by msPEF, μsPEF and nsPEF have been studied and compared. While a 1 log10 was reached with an energy cost of 100 and 158 kJ/L with micro- and millisecond PEFs respectively, nsPEF reached the reduction for similar energy consumption. The best condition was obtained for a 1 log10 deactivation in 0.5h, for energy consumption of 143 kJ/L corresponding to 0.04 W · h when the field was around 100 kV/cm. Improvement can also be expected by producing a generator capable to increase the electric field.

  8. Pulsed electric fields

    USDA-ARS?s Scientific Manuscript database

    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...

  9. Distillation under electric fields

    SciTech Connect

    Shah, V.M.; Blankenship, K.D.; Tsouris, C.

    1997-11-01

    Distillation Is the most common separation process used in the chemical and petroleum industry. Major limitations in the applicability and efficiency of distillation come from thermodynamic equilibria, that is, vapor-liquid equilibria (VLE), and heat and mass transfer rates. In this work, electric fields are used to manipulate the VLE of mixtures. VLE experiments are performed for various binary mixtures in the presence of electric fields on the order of a few kilovolts per centimeter. The results show that the VLE is changed by electric fields, with changes in the separation factor as high as 10% being observed. Batch distillation experiments are also carried out for binary mixtures of 2-propanol and water with and without an applied electric field. Results show enhanced distillation rates and separation efficiency in the presence of an electric field but decreased separation enhancement when the electric current is increased. The latter phenomenon is caused by the formation at the surface of the liquid mixture of microdroplets that are entrained by the vapor. These observations suggest that there should be an electric field strength for each system for which the separation enhancement is maximum.

  10. Nanomechanical electric and electromagnetic field sensor

    DOEpatents

    Datskos, Panagiotis George; Lavrik, Nickolay

    2015-03-24

    The present invention provides a system for detecting and analyzing at least one of an electric field and an electromagnetic field. The system includes a micro/nanomechanical oscillator which oscillates in the presence of at least one of the electric field and the electromagnetic field. The micro/nanomechanical oscillator includes a dense array of cantilevers mounted to a substrate. A charge localized on a tip of each cantilever interacts with and oscillates in the presence of the electric and/or electromagnetic field. The system further includes a subsystem for recording the movement of the cantilever to extract information from the electric and/or electromagnetic field. The system further includes a means of adjusting a stiffness of the cantilever to heterodyne tune an operating frequency of the system over a frequency range.

  11. Current characteristics of λ-DNA molecules/polystyrene nanoparticles in TBE buffer solution through micro/nanofluidic capillaries under DC electric field

    NASA Astrophysics Data System (ADS)

    Duan, Yifei; Zhao, Wei; Xue, Jing; Sun, Dan; Wang, Kaige; Wang, Guiren; Li, Junjie; Bai, Jintao; Gu, Changzhi

    2017-03-01

    In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate single bio-molecules and analyze their characteristics. To accurately and flexibly control the movement of single-molecule within micro/nanofluidic channels which are the basic components of Lab-chips, the current signals in micro/nanocapillaries filled with solutions of DNA molecules or polystyrene (PS) nanoparticles are systematically studied. Experimental results indicate that the current response along the micro/nanocapillaries can be significantly influenced by the diameter of the capillaries and the pH value of the solutions. Specifically, when there is only a pure (TBE) solution, the electric conductance does not monotonically decrease with decreasing the diameter of the capillaries, but slightly increases with decreasing the capillary diameter. When λ-DNA molecules or PS nanoparticles are added into the TBE buffer, the size effect on the electric conductance of the solutions are quite different. Although in the former, the electric conductance behaves differently from that in the pure TBE solution and decreases with the decreasing diameter, in the latter, the change is similar to that in the pure TBE solution. Besides, an abnormal ‘falling’ of the electric conductance is observed in a capillary with diameter of 200 nm. The investigation will significantly enhance the understanding on the electric properties of the solutions of biomolecules and particles in micro/nanofluidics. This is especially helpful for designing functional Lab-chip devices.

  12. Electric and magnetic fields

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Robinson, R. S.; Etters, R. D.

    1982-01-01

    A number of energy momentum anomalies are described that result from the use of Abraham-Lorentz electromagnetic theory. These anomalies have in common the motion of charged bodies or current carrying conductors relative to the observer. The anomalies can be avoided by using the nonflow approach, based on internal energy of the electromagnetic field. The anomalies can also be avoided by using the flow approach, if all contributions to flow work are included. The general objective of this research is a fundamental physical understanding of electric and magnetic fields which, in turn, might promote the development of new concepts in electric space propulsion. The approach taken is to investigate quantum representations of these fields.

  13. Electric field imaging

    NASA Astrophysics Data System (ADS)

    Smith, Joshua Reynolds

    The physical user interface is an increasingly significant factor limiting the effectiveness of our interactions with and through technology. This thesis introduces Electric Field Imaging, a new physical channel and inference framework for machine perception of human action. Though electric field sensing is an important sensory modality for several species of fish, it has not been seriously explored as a channel for machine perception. Technological applications of field sensing, from the Theremin to the capacitive elevator button, have been limited to simple proximity detection tasks. This thesis presents a solution to the inverse problem of inferring geometrical information about the configuration and motion of the human body from electric field measurements. It also presents simple, inexpensive hardware and signal processing techniques for makin the field measurements, and several new applications of electric field sensing. The signal processing contribution includes synchronous undersampling, a narrowband, phase sensitive detection technique that is well matched to the capabilities of contemporary microcontrollers. In hardware, the primary contributions are the School of Fish, a scalable network of microcontroller-based transceive electrodes, and the LazyFish, a small footprint integrated sensing board. Connecting n School of Fish electrodes results in an array capable of making heterodyne measurements of any or all n(n - 1) off-diagonal entries in the capacitance matrix. The LazyFish uses synchronous undersampling to provide up to 8 high signal- to-noise homodyne measurements in a very small package. The inverse electrostatics portion of the thesis presents a fast, general method for extracting geometrical information about the configuration and motion of the human body from field measurements. The method is based on the Sphere Expansion, a novel fast method for generating approximate solutions to the Laplace equation. Finally, the thesis describes a variety

  14. Electric potential and electric field imaging

    NASA Astrophysics Data System (ADS)

    Generazio, E. R.

    2017-02-01

    The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field made be used for "illuminating" volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e-Sensor enhancements (ephemeral e-Sensor) are discussed. Demonstrations for structural, electronic, human, and memory applications are shown. This new EFI capability is demonstrated to reveal characterization of electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, crime scene forensics, design and materials selection for advanced sensors, dielectric morphology of structures, tether integrity, organic molecular memory, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

  15. Overview - Electric fields. [in magnetosphere

    NASA Technical Reports Server (NTRS)

    Cauffman, D. P.

    1979-01-01

    The electric fields session is designed to review progress in observation, theory, and modeling of magnetospheric electric fields, and to expose important new results. The present report comments on the state and prospects of electric field research, with particular emphasis on relevance to quantitative modeling of the magnetospheric processes. Attention is given to underlying theories and models. Modeling philosophy is discussed relative to explanatory models and representative models. Modeling of magnetospheric electric fields, while in its infancy, is developing rapidly on many fronts employing a variety of approaches. The general topic of magnetospheric electric fields is becoming of prime importance in understanding space plasmas.

  16. Magnetospheric electric fields and currents

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Zanetti, L. J.

    1987-01-01

    The progress made in the years 1983-1986 in understanding the character and operation of magnetospheric electric fields and electric currents is discussed, with emphasis placed on the connection with the interior regions. Special attention is given to determinations of global electric-field configurations, measurements of the response of magnetospheric particle populations to the electric-field configurations, and observations of the magnetospheric currents at high altitude and during northward IMF. Global simulations of current distributions are discussed, and the sources of global electric fields and currents are examined. The topics discussed in the area of impulsive and small-scale phenomena include substorm current systems, impulsive electric fields and associated currents, and field-aligned electrodynamics. A key finding of these studies is that the electric fields and currents are interrelated and cannot be viewed as separate entities.

  17. Electric field controlled emulsion phase contactor

    DOEpatents

    Scott, T.C.

    1995-01-31

    A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figs.

  18. Electric field controlled emulsion phase contactor

    DOEpatents

    Scott, Timothy C.

    1995-01-01

    A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

  19. Cryosurgery with Pulsed Electric Fields

    PubMed Central

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

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

  20. Occurrence of sublethal injury after pulsed electric fields depending on the micro-organism, the treatment medium ph and the intensity of the treatment investigated.

    PubMed

    García, D; Gómez, N; Mañas, P; Condón, S; Raso, J; Pagán, R

    2005-01-01

    The objective was to investigate the occurrence of sublethal injury after pulsed electric field (PEF) depending on the treatment time, the electric field strength and the pH of the treatment media in two Gram-positive (Bacillus subtilis ssp. niger, Listeria monocytogenes) and six Gram-negative (Escherichia coli, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella serotype Senftenberg 775W, Salmonella serotype Typhimurium, Yersinia enterocolitica) bacterial strains. A characteristic behaviour was observed for the Gram-positive and Gram-negative bacteria studied. Whereas Gram-positive bacteria showed a higher PEF resistance at pH 7.0, the Gram-negative were more resistant at pH 4.0. In these conditions, in which bacteria showed their maximum resistance, a large proportion of sublethally injured cells were detected. In most cases, the longer the treatment time and the higher the electric field applied, the greater the proportion of sublethally injured cells that were detected. No sublethal injury was detected when Gram-positive bacteria were treated at pH 4.0 and Gram-negative at pH 7.0. Sublethal injury was detected after PEF so, bacterial inactivation by PEF is not an 'all or nothing' event. This work could be useful for improving food preservation by PEF.

  1. Electric Field Containerless Processing Technology

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Rhim, W. K.

    1985-01-01

    The objective of this task is to develop the science and technology base required to design and construct a high temperature electric field positioning module that could be used by materials scientists to conduct containerless science experiments in a low gravity environment. Containerless science modules that employ electric fields to position and manipulate samples offer several advantages over acoustic or electromagnetic systems. The electric field system will operate not only at atmospheric pressures but also in a vacuum, in contrast to the acoustic modules which can only operate in atmosphere where the acoustic forces are sufficient. The electric field technique puts minimum energy into the sample, whereas the electromagnetic system can deposit energy into the sample through eddy current heat as well as physical mixing in the sample. Two types of electric field modules have been constructed and tested to date. One employs a charged sample and uses electrostatic forces to position and control the sample. The second type of module induces electrical polarization of the sample and electric field gradients to position and control the sample.

  2. Electric field in neutron stars

    SciTech Connect

    Adam, R. I. Sulaksono, A.

    2016-04-19

    In a compact star, an electric field is generated by the charge polarization effect. We investigate the charge polarization effect due to a significant difference of core and crust densities in the form of a combination of two Gaussian functions. The results indicate that the electric field only occurs significantly on the crust of the compact star. As a consequence, the mass-radius relationship only affects compact stars with mass ≤ 1.0 M{sub ⊙}.

  3. Introducing electric fields

    NASA Astrophysics Data System (ADS)

    Roche, John

    2016-09-01

    The clear introduction of basic concepts and definitions is crucial for teaching any topic in physics. I have always found it difficult to teach fields. While searching for better explanations I hit on an approach of reading foundational texts and electromagnetic textbooks in ten year lots, ranging from 1840 to the present. By combining this with modern techniques of textual interpretation I attempt to clarify three introductory concepts: how the field is defined; the principle of superposition and the role of the electrostatic field in a circuit.

  4. Revisiting the Corotation Electric Field

    NASA Astrophysics Data System (ADS)

    Rothwell, P. L.

    2001-05-01

    The rotation of the Earth's dipole magnetic field produces a corotation electric field in the nonrotating frame of reference. A quick calculation implies that this field might arise from the relative motion of an observer in the nonrotating frame and the motion of rotating magnetic field lines. However, upon applying Faraday's Law one finds that total time rate of change of the magnetic field as seen in the nonrotating frame is zero due to the azimuthal symmetry of the dipole. Therefore, classical EM theory(1) predicts a zero corotation electric field in the nonrotating frame for a vacuum. This conundrum has been traditionally treated in the following manner(2,3). 1) Start with a vacuum state with no conductors and plasma present. The transformation between E (the electric field in the nonrotating frame) and E' (the electric field in the rotating frame)implies that in the rotating frame E' is nonzero while E = 0. 2) In the presence of a thin conducting spherical shell (the ionosphere) polarization charges form in the shell due to the magnetic force on the electrons. A polarization electric field Ep is created such that in the idealized case the shell has a uniform electric potential. This Ep has a component along the magnetic field lines outside the shell. 3) Plasma will polarize along B, thus canceling the parallel component of Ep which allows the potential on the shell to be mapped along the magnetic field lines setting E' = 0. From the transformation equation E is now nonzero. This is the electric field required in the nonrotating frame for the plasma to corotate with the dipole. The presence of the corotation electric field is not a local result, but a nonlocal effect that requires the presence of an ionosphere and a conducting plasma. (1) W.K.H. Panofsky and M. Phillips, Classical Electricity and Magnetism, Addison-Wesley, 1956. (2) H. Alfven and C.-G. Falthammar, Cosmical Electrodynamics, 2nd ed., Oxford Press, 1963. (3) E.W.Hones and J.E.Bergeson, J. Geophys

  5. THOR Electric Field Instrument - EFI

    NASA Astrophysics Data System (ADS)

    Khotyaintsev, Yuri; Bale, Stuart D.; Bonnell, John W.; Lindqvist, Per-Arne; Phal, Yamuna; Rothkaehl, Hanna; Soucek, Jan; Vaivads, Andris; Åhlen, Lennart

    2016-04-01

    Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. The Electric Field Instrument (EFI) will measure the vector electric field from 0 to 200 kHz. EFI consists of two sets of sensors: Spin-plane Double Probes (EFI-SDP) providing high sensitivity DC electric field in the spacecraft spin plane (2D), and the High-Frequency Antenna (EFI-HFA) providing 3D electric field at frequencies above ~1 kHz. EFI-SDP consists of 4 biased spherical probes extended on 50 m long wire booms, 90 degrees apart in the spin plane, giving a 100 m baseline for each of the two spin-plane electric field components. EFI-HFA consists of 6 x 1.25 m long monopoles, forming 3 dipolar antennas crossed at 90 degrees to each other. In addition to the sensors, EFI contains HFA and SDP pre-amplifiers, as well as bias electronics boards (BEBs) hosted in the man electronics box of the Field and Wave processor (FWP). As THOR spacecraft has a sun-pointing spin axis, EFI-SDP measures the electric field in the plane approximately orthogonal to the sun using long wire booms. The sun-pointing attitude greatly reduces errors due to wake effects and asymmetric photoelectron clouds, enabling the highly accurate in comparison to earlier missions ±0.1 mV/m near-DC electric field measurements. Interferometry using the electric field probes can be used to infer wavelengths and scale sizes at the smallest scales in the plasma. EFI also measures the floating potential of the satellite, which can be used to estimate the plasma density at very high time resolution (up to a few hundred Hz). The sun-pointing attitude greatly reduces changes in the illuminated area, and hence the associated spin-dependent errors. In combination with densities derived from the observed plasma frequency emission line, EFI monitors the plasma density from DC to a few hundred Hz. EFI measurements characterize electric field and density variations associated with kinetic scale plasma

  6. THOR Electric Field Instrument - EFI

    NASA Astrophysics Data System (ADS)

    Khotyaintsev, Yuri; Bale, Stuart D.; Rothkaehl, Hanna; Bonnell, John; Åhlen, Lennart; Vaivads, Andris; Lindqvist, Per-Arne; Ivchenko, Nickolay; Soucek, Jan

    2017-04-01

    Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. The Electric Field Instrument (EFI) is to measure the electric field vector in the frequency range 0-200 kHz. EFI consists of two sets of sensors: Spin-plane Double Probes (EFI-SDP) providing high sensitivity DC electric field in the spacecraft spin plane (2D), and the High-Frequency Antenna (EFI-HFA) providing 3D electric field at frequencies above 1 kHz. EFI-SDP consists of 4 biased spherical probes extended on 50 m long wire booms, 90 degrees apart in the spin plane, giving a 100 m baseline for each of the two spin-plane electric field components. EFI-HFA consists of 6 x 1.25 m long monopoles, forming 3 dipolar antennas crossed at 90 degrees to each other. In addition to the sensors, EFI contains HFA and SDP pre-amplifiers, as well as bias electronics boards (BEBs) hosted in the man electronics box of the Field and Wave processor (FWP). As THOR spacecraft has a sun-pointing spin axis, EFI-SDP measures the electric field in the plane approximately orthogonal to the sun using long wire booms. The sun-pointing attitude greatly reduces errors due to wake effects and asymmetric photoelectron clouds, enabling the highly accurate in comparison to earlier missions ±0.1 mV/m near-DC electric field measurements. Interferometry using the electric field probes can be used to infer wavelengths and scale sizes at the smallest scales in the plasma. EFI also measures the floating potential of the satellite, which can be used to estimate the plasma density at very high time resolution (up to a few hundred Hz). The sun-pointing attitude greatly reduces changes in the illuminated area, and hence the associated spin-dependent errors. In combination with densities derived from the observed plasma frequency emission line, EFI monitors the plasma density from DC to a few hundred Hz. EFI measurements characterize electric field and density variations associated with kinetic

  7. Electric fields and quantum wormholes

    NASA Astrophysics Data System (ADS)

    Engelhardt, Dalit; Freivogel, Ben; Iqbal, Nabil

    2015-09-01

    Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a "quantum wormhole." We demonstrate within low-energy effective field theory that there is a precise sense in which electric fields can also thread such quantum wormholes. We define a nonperturbative "wormhole susceptibility" that measures the ease of passing an electric field through any sort of wormhole. The susceptibility of a quantum wormhole is suppressed by powers of the U (1 ) gauge coupling relative to that for a classical wormhole but can be made numerically equal with a sufficiently large amount of entangled matter.

  8. Synaptic Effects of Electric Fields

    NASA Astrophysics Data System (ADS)

    Rahman, Asif

    Learning and sensory processing in the brain relies on the effective transmission of information across synapses. The strength and efficacy of synaptic transmission is modifiable through training and can be modulated with noninvasive electrical brain stimulation. Transcranial electrical stimulation (TES), specifically, induces weak intensity and spatially diffuse electric fields in the brain. Despite being weak, electric fields modulate spiking probability and the efficacy of synaptic transmission. These effects critically depend on the direction of the electric field relative to the orientation of the neuron and on the level of endogenous synaptic activity. TES has been used to modulate a wide range of neuropsychiatric indications, for various rehabilitation applications, and cognitive performance in diverse tasks. How can a weak and diffuse electric field, which simultaneously polarizes neurons across the brain, have precise changes in brain function? Designing therapies to maximize desired outcomes and minimize undesired effects presents a challenging problem. A series of experiments and computational models are used to define the anatomical and functional factors leading to specificity of TES. Anatomical specificity derives from guiding current to targeted brain structures and taking advantage of the direction-sensitivity of neurons with respect to the electric field. Functional specificity originates from preferential modulation of neuronal networks that are already active. Diffuse electric fields may recruit connected brain networks involved in a training task and promote plasticity along active synaptic pathways. In vitro, electric fields boost endogenous synaptic plasticity and raise the ceiling for synaptic learning with repeated stimulation sessions. Synapses undergoing strong plasticity are preferentially modulated over weak synapses. Therefore, active circuits that are involved in a task could be more susceptible to stimulation than inactive circuits

  9. A new probe for measuring small electric fields in plasmas

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1991-01-01

    A dipolar double probe has been developed for in situ measurements of small electric fields in laboratory plasmas. The probe measures dc to ac electric fields (f values between 0 and 20 MHz) with high sensitivity (Emin about 10 microV/cm) and responds to both space charge electric fields and inductive electric fields. Using voltage-to-frequency conversion, the probe signal is obtained free of errors and loading effects by a transmission line. Various examples of useful applications for the new probe are presented, such as measurements of dc ambipolar fields, ac space-charge fields of ion acoustic waves, ac inductive fields of whistler waves, and mixed inductive and space-charge electric fields in current-carrying magnetoplasmas.

  10. Electric fields in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

    Two techniques, tracking the motions of Ba(+) clouds and measuring the differences in floating potential between symmetric double probes, were successful in: (1) demonstrating the basic convective nature of magnetospheric electric fields, (2) mapping global patterns of convection at upper ionosphere levels, and (3) revealing the physics of electric currents in the ionosphere and the importance of magnetosphere-ionosphere feedback in altering the imposed convection.

  11. Microstickies agglomeration by electric field.

    PubMed

    Du, Xiaotang Tony; Hsieh, Jeffery S

    2016-01-01

    Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied.

  12. Apparatuses and methods for generating electric fields

    DOEpatents

    Scott, Jill R; McJunkin, Timothy R; Tremblay, Paul L

    2013-08-06

    Apparatuses and methods relating to generating an electric field are disclosed. An electric field generator may include a semiconductive material configured in a physical shape substantially different from a shape of an electric field to be generated thereby. The electric field is generated when a voltage drop exists across the semiconductive material. A method for generating an electric field may include applying a voltage to a shaped semiconductive material to generate a complex, substantially nonlinear electric field. The shape of the complex, substantially nonlinear electric field may be configured for directing charged particles to a desired location. Other apparatuses and methods are disclosed.

  13. Electrophoresis in strong electric fields.

    PubMed

    Barany, Sandor

    2009-01-01

    Two kinds of non-linear electrophoresis (ef) that can be detected in strong electric fields (several hundred V/cm) are considered. The first ("classical" non-linear ef) is due to the interaction of the outer field with field-induced ionic charges in the electric double layer (EDL) under conditions, when field-induced variations of electrolyte concentration remain to be small comparatively to its equilibrium value. According to the Shilov theory, the non-linear component of the electrophoretic velocity for dielectric particles is proportional to the cubic power of the applied field strength (cubic electrophoresis) and to the second power of the particles radius; it is independent of the zeta-potential but is determined by the surface conductivity of particles. The second one, the so-called "superfast electrophoresis" is connected with the interaction of a strong outer field with a secondary diffuse layer of counterions (space charge) that is induced outside the primary (classical) diffuse EDL by the external field itself because of concentration polarization. The Dukhin-Mishchuk theory of "superfast electrophoresis" predicts quadratic dependence of the electrophoretic velocity of unipolar (ionically or electronically) conducting particles on the external field gradient and linear dependence on the particle's size in strong electric fields. These are in sharp contrast to the laws of classical electrophoresis (no dependence of V(ef) on the particle's size and linear dependence on the electric field gradient). A new method to measure the ef velocity of particles in strong electric fields is developed that is based on separation of the effects of sedimentation and electrophoresis using videoimaging and a new flowcell and use of short electric pulses. To test the "classical" non-linear electrophoresis, we have measured the ef velocity of non-conducting polystyrene, aluminium-oxide and (semiconductor) graphite particles as well as Saccharomice cerevisiae yeast cells as a

  14. Electric field divertor plasma pump

    DOEpatents

    Schaffer, M.J.

    1994-10-04

    An electric field plasma pump includes a toroidal ring bias electrode positioned near the divertor strike point of a poloidal divertor of a tokamak, or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix of the poloidal divertor contacts the ring electrode, which then also acts as a divertor plate. A plenum or other duct near the electrode includes an entrance aperture open to receive electrically-driven plasma. The electrode is insulated laterally with insulators, one of which is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode and a vacuum vessel wall, with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E [times] B/B[sup 2] drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable. 11 figs.

  15. Electric field divertor plasma pump

    DOEpatents

    Schaffer, Michael J.

    1994-01-01

    An electric field plasma pump includes a toroidal ring bias electrode (56) positioned near the divertor strike point of a poloidal divertor of a tokamak (20), or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix (40) of the poloidal divertor contacts the ring electrode (56), which then also acts as a divertor plate. A plenum (54) or other duct near the electrode (56) includes an entrance aperture open to receive electrically-driven plasma. The electrode (56) is insulated laterally with insulators (63,64), one of which (64) is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode (56) and a vacuum vessel wall (22), with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E.times.B/B.sup.2 drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable.

  16. Linear electric field mass spectrometry

    DOEpatents

    McComas, David J.; Nordholt, Jane E.

    1992-01-01

    A mass spectrometer and methods for mass spectrometry. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field.

  17. Linear electric field mass spectrometry

    DOEpatents

    McComas, D.J.; Nordholt, J.E.

    1992-12-01

    A mass spectrometer and methods for mass spectrometry are described. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field. 8 figs.

  18. Micro Electro Discharge Machining of Electrically Nonconductive Ceramics

    SciTech Connect

    Schubert, A.; Zeidler, H.; Hackert, M.; Wolf, N.

    2011-05-04

    EDM is a known process for machining of hard and brittle materials. Due to its noncontact and nearly forceless behaviour, it has been introduced into micro manufacturing and through constant development it is now an important means for producing high-precision micro geometries. One restriction of EDM is its limitation to electrically conducting materials.Today many applications, especially in the biomedical field, make use of the benefits of ceramic materials, such as high strength, very low wear and biocompatibility. Common ceramic materials such as Zirconium dioxide are, due to their hardness in the sintered state, difficult to machine with conventional cutting techniques. A demand for the introduction of EDM to these materials could so far not be satisfied because of their nonconductive nature.At the Chemnitz University of Technology and the Fraunhofer IWU, investigations in the applicability of micro-EDM for the machining of nonconductive ceramics are being conducted. Tests are undertaken using micro-EDM drilling with Tungsten carbide tool electrodes and ZrO{sub 2} ceramic workpieces. A starting layer, in literature often referred to as 'assisting electrode' is used to set up a closed electric circuit to start the EDM process. Combining carbon hydride based dielectric and a specially designed low-frequency vibration setup to excite the workpiece, the process environment can be held within parameters to allow for a constant EDM process even after the starting layer is machined. In the experiments a cylindrical 120 {mu}m diameter Tungsten carbide tool electrode and Y{sub 2}O{sub 3}- and MgO- stabilized ZrO{sub 2} worpieces are used. The current and voltage signals of the discharges within the different stages of the process (machining of the starting layer, machining of the base material, transition stage) are recorded and their characteristics compared to discharges in metallic material. Additionally, the electrode feed is monitored. The influences of the

  19. Micro Electro Discharge Machining of Electrically Nonconductive Ceramics

    NASA Astrophysics Data System (ADS)

    Schubert, A.; Zeidler, H.; Wolf, N.; Hackert, M.

    2011-05-01

    EDM is a known process for machining of hard and brittle materials. Due to its noncontact and nearly forceless behaviour, it has been introduced into micro manufacturing and through constant development it is now an important means for producing high-precision micro geometries. One restriction of EDM is its limitation to electrically conducting materials. Today many applications, especially in the biomedical field, make use of the benefits of ceramic materials, such as high strength, very low wear and biocompatibility. Common ceramic materials such as Zirconium dioxide are, due to their hardness in the sintered state, difficult to machine with conventional cutting techniques. A demand for the introduction of EDM to these materials could so far not be satisfied because of their nonconductive nature. At the Chemnitz University of Technology and the Fraunhofer IWU, investigations in the applicability of micro-EDM for the machining of nonconductive ceramics are being conducted. Tests are undertaken using micro-EDM drilling with Tungsten carbide tool electrodes and ZrO2 ceramic workpieces. A starting layer, in literature often referred to as `assisting electrode' is used to set up a closed electric circuit to start the EDM process. Combining carbon hydride based dielectric and a specially designed low-frequency vibration setup to excite the workpiece, the process environment can be held within parameters to allow for a constant EDM process even after the starting layer is machined. In the experiments a cylindrical 120 μm diameter Tungsten carbide tool electrode and Y2O3- and MgO- stabilized ZrO2 worpieces are used. The current and voltage signals of the discharges within the different stages of the process (machining of the starting layer, machining of the base material, transition stage) are recorded and their characteristics compared to discharges in metallic material. Additionally, the electrode feed is monitored. The influences of the process parameters are

  20. Assembly of LIGA using Electric Fields

    SciTech Connect

    FEDDEMA, JOHN T.; WARNE, LARRY K.; JOHNSON, WILLIAM A.; OGDEN, ALLISON J.; ARMOUR, DAVID L.

    2002-04-01

    The goal of this project was to develop a device that uses electric fields to grasp and possibly levitate LIGA parts. This non-contact form of grasping would solve many of the problems associated with grasping parts that are only a few microns in dimensions. Scaling laws show that for parts this size, electrostatic and electromagnetic forces are dominant over gravitational forces. This is why micro-parts often stick to mechanical tweezers. If these forces can be controlled under feedback control, the parts could be levitated, possibly even rotated in air. In this project, we designed, fabricated, and tested several grippers that use electrostatic and electromagnetic fields to grasp and release metal LIGA parts. The eventual use of this tool will be to assemble metal and non-metal LIGA parts into small electromechanical systems.

  1. Assembly of LIGA Using Electric Fields

    NASA Astrophysics Data System (ADS)

    Feddema, J. T.; Warne, L. K.; Johnson, W. A.; Ogden, A. J.; Armour, D. L.

    2002-04-01

    The goal of this project was to develop a device that uses electric fields to grasp and possibly levitate LlGA parts. This non-contact form of grasping would solve many of the problems associated with grasping parts that are only a few microns in dimensions. Scaling laws show that for parts this size, electrostatic and electromagnetic forces are dominant over gravitational forces. This is why micro-parts often stick to mechanical tweezers. If these forces can be controlled under feedback control, the parts could be levitated, possibly even rotated in air. In this project, we designed, fabricated, and tested several grippers that use electrostatic and electromagnetic fields to grasp and release metal LlGA parts. The eventual use of this tool will be to assemble metal and non-metal LlGA parts into small electromechanical systems.

  2. A field operational test on valve-regulated lead-acid absorbent-glass-mat batteries in micro-hybrid electric vehicles. Part II. Results based on multiple regression analysis and tear-down analysis

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Karspeck, T.; Ott, C.; Weirather-Koestner, D.; Stoermer, A. O.

    2011-03-01

    In the first part of this work [1] a field operational test (FOT) on micro-HEVs (hybrid electric vehicles) and conventional vehicles was introduced. Valve-regulated lead-acid (VRLA) batteries in absorbent glass mat (AGM) technology and flooded batteries were applied. The FOT data were analyzed by kernel density estimation. In this publication multiple regression analysis is applied to the same data. Square regression models without interdependencies are used. Hereby, capacity loss serves as dependent parameter and several battery-related and vehicle-related parameters as independent variables. Battery temperature is found to be the most critical parameter. It is proven that flooded batteries operated in the conventional power system (CPS) degrade faster than VRLA-AGM batteries in the micro-hybrid power system (MHPS). A smaller number of FOT batteries were applied in a vehicle-assigned test design where the test battery is repeatedly mounted in a unique test vehicle. Thus, vehicle category and specific driving profiles can be taken into account in multiple regression. Both parameters have only secondary influence on battery degradation, instead, extended vehicle rest time linked to low mileage performance is more serious. A tear-down analysis was accomplished for selected VRLA-AGM batteries operated in the MHPS. Clear indications are found that pSoC-operation with periodically fully charging the battery (refresh charging) does not result in sulphation of the negative electrode. Instead, the batteries show corrosion of the positive grids and weak adhesion of the positive active mass.

  3. Optical measurement of electric fields

    NASA Astrophysics Data System (ADS)

    Steiger, Andreas; de la Rosa, M. I.; Perez, Conception; Gemisic, Minja; Gruetzmacher, Klaus; Seidel, Joachim

    2003-05-01

    Local electric field strengths in low density plasmas can be measured directly by Doppler-free two-photon spectroscopy of atomic hydrogen mostly present in such discharges. This method is based on the Stark-splitting of the atomic resonance lines and causes no significant perturbation to the discharge. For this purpose, we take advantage of our advanced pulsed UV-laser spectrometers which provide not only the peak power needed for two-photon excitation but also the high spectral resolution to resolve the atomic hyperfine splitting. In a first experiment with opto-galvanic detection, atomic hydrogen was produced by thermal dissociation in a small cell filled with hydrogen gas and the Stark-splitting of the 1S-2S and the 1S-3S/D transition was measured. Electric fields as low as 200 V/cm and 30 V/cm respectively could be determined in accordance with theory. In addition, we have performed measurements in a hollow cathode discharge which provides higher electric fields in its cathode fall region and the 1S-2S spectrum was detected spatially resolved by means of opto-galvanic and polarization spectroscopy as well. Selected experimental results will be presented which clearly demonstrate the high potential of this optical method.

  4. GROUNDWATER AND SOIL REMEDIATION USING ELECTRICAL FIELD

    EPA Science Inventory

    Enhancements of contaminants removal and degradation in low permeability soils by electrical fields are achieved by the processes of electrical heating, electrokinetics, and electrochemical reactions. Electrical heating increases soil temperature resulting in the increase of cont...

  5. GROUNDWATER AND SOIL REMEDIATION USING ELECTRICAL FIELD

    EPA Science Inventory

    Enhancements of contaminants removal and degradation in low permeability soils by electrical fields are achieved by the processes of electrical heating, electrokinetics, and electrochemical reactions. Electrical heating increases soil temperature resulting in the increase of cont...

  6. Pulsed electric field increases reproduction.

    PubMed

    Panagopoulos, Dimitris J

    2016-01-01

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

  7. Full-field optical micro-angiography

    NASA Astrophysics Data System (ADS)

    Wang, Mingyi; Zeng, Yaguang; Liang, Xianjun; Lu, Xuanlong; Feng, Guanping; Han, Dingan; Yang, Guojian

    2014-02-01

    We present a detailed description of full-field optical micro-angiography on the basis of frequency-domain laser speckle imaging with intensity fluctuation modulation (LSI-IFM). The imaging approach works based on the instantaneous local intensity fluctuation realized via the combination of short exposure and low sampling rate of a camera and appropriate magnification of a microscope. In vivo experiments on mouse ear verify the theoretical description we made for the imaging mechanism and demonstrate the ability of LSI-IFM as optical micro-angiography. By introducing a fundus camera into LSI-IFM system, our approach has a potential application in label-free retina optical micro-angiography.

  8. Electric Field Induced Interfacial Instabilities

    NASA Technical Reports Server (NTRS)

    Kusner, Robert E.; Min, Kyung Yang; Wu, Xiao-lun; Onuki, Akira

    1999-01-01

    The study of the interface in a charge-free, critical and near-critical binary fluid in the presence of an externally applied electric field is presented. At sufficiently large fields, the interface between the two phases of the binary fluid should become unstable and exhibit an undulation with a predefined wavelength on the order of the capillary length. As the critical point is approached, this wavelength is reduced, potentially approaching length-scales such as the correlation length or critical nucleation radius. At this point the critical properties of the system may be affected. In this paper, the flat interface of a marginally polar binary fluid mixture is stressed by a perpendicular alternating electric field and the resulting instability is characterized by the critical electric field E(sub c) and the pattern observed. The character of the surface dynamics at the onset of instability is found to be strongly dependent on the frequency f of the field applied. The plot of E(sub c) vs. f for a fixed temperature shows a sigmoidal shape, whose low and high frequency limits are well described by a power-law relationship, E(sub c) = epsilon(exp zeta) with zeta = 0.35 and zeta = 0.08, respectively. The low-limit exponent compares well with the value zeta = 4 for a system of conducting and non-conducting fluids. On the other hand, the high-limit exponent coincides with what was first predicted by Onuki. The instability manifests itself as the conducting phase penetrates the non-conducting phase. As the frequency increases, the shape of the pattern changes from an array of bifurcating strings to an array of column-like (or rod-like) protrusions, each of which spans the space between the plane interface and one of the electrodes. For an extremely high frequency, the disturbance quickly grows into a parabolic cone pointing toward the upper plate. As a result, the interface itself changes its shape from that of a plane to that of a high sloping pyramid.

  9. Cell separation using electric fields

    NASA Technical Reports Server (NTRS)

    Mangano, Joseph (Inventor); Eppich, Henry (Inventor)

    2009-01-01

    The present invention involves methods and devices which enable discrete objects having a conducting inner core, surrounded by a dielectric membrane to be selectively inactivated by electric fields via irreversible breakdown of their dielectric membrane. One important application of the invention is in the selection, purification, and/or purging of desired or undesired biological cells from cell suspensions. According to the invention, electric fields can be utilized to selectively inactivate and render non-viable particular subpopulations of cells in a suspension, while not adversely affecting other desired subpopulations. According to the inventive methods, the cells can be selected on the basis of intrinsic or induced differences in a characteristic electroporation threshold, which can depend, for example, on a difference in cell size and/or critical dielectric membrane breakdown voltage. The invention enables effective cell separation without the need to employ undesirable exogenous agents, such as toxins or antibodies. The inventive method also enables relatively rapid cell separation involving a relatively low degree of trauma or modification to the selected, desired cells. The inventive method has a variety of potential applications in clinical medicine, research, etc., with two of the more important foreseeable applications being stem cell enrichment/isolation, and cancer cell purging.

  10. Cell separation using electric fields

    NASA Technical Reports Server (NTRS)

    Mangano, Joseph A. (Inventor); Eppich, Henry M. (Inventor)

    2003-01-01

    The present invention involves methods and devices which enable discrete objects having a conducting inner core, surrounded by a dielectric membrane to be selectively inactivated by electric fields via irreversible breakdown of their dielectric membrane. One important application of the invention is in the selection, purification, and/or purging of desired or undesired biological cells from cell suspensions. According to the invention, electric fields can be utilized to selectively inactivate and render non-viable particular subpopulations of cells in a suspension, while not adversely affecting other desired subpopulations. According to the inventive methods, the cells can be selected on the basis of intrinsic or induced differences in a characteristic electroporation threshold, which can depend, for example, on a difference in cell size and/or critical dielectric membrane breakdown voltage. The invention enables effective cell separation without the need to employ undesirable exogenous agents, such as toxins or antibodies. The inventive method also enables relatively rapid cell separation involving a relatively low degree of trauma or modification to the selected, desired cells. The inventive method has a variety of potential applications in clinical medicine, research, etc., with two of the more important foreseeable applications being stem cell enrichment/isolation, and cancer cell purging.

  11. Silicon-based metallic micro grid for electron field emission

    NASA Astrophysics Data System (ADS)

    Kim, Jaehong; Jeon, Seok-Gy; Kim, Jung-Il; Kim, Geun-Ju; Heo, Duchang; Shin, Dong Hoon; Sun, Yuning; Lee, Cheol Jin

    2012-10-01

    A micro-scale metal grid based on a silicon frame for application to electron field emission devices is introduced and experimentally demonstrated. A silicon lattice containing aperture holes with an area of 80 × 80 µm2 and a thickness of 10 µm is precisely manufactured by dry etching the silicon on one side of a double-polished silicon wafer and by wet etching the opposite side. Because a silicon lattice is more rigid than a pure metal lattice, a thin layer of Au/Ti deposited on the silicon lattice for voltage application can be more resistant to the geometric stress caused by the applied electric field. The micro-fabrication process, the images of the fabricated grid with 88% geometric transparency and the surface profile measurement after thermal feasibility testing up to 700 °C are presented.

  12. Controlling flow direction in nanochannels by electric field strength

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Zhao, Tianshou; Li, Zhigang

    2015-08-01

    Molecular dynamics simulations are conducted to study the flow behavior of CsF solutions in nanochannels under external electric fields E . It is found that the channel surface energy greatly affects the flow behavior. In channels of high surface energy, water molecules, on average, move in the same direction as that of the electric field regardless of the strength of E . In low surface energy channels, however, water transports in the opposite direction to the electric field at weak E and the flow direction is changed when E becomes sufficiently large. The direction change of water flow is attributed to the coupled effects of different water-ion interactions, inhomogeneous water viscosity, and ion distribution changes caused by the electric field. The flow direction change observed in this work may be employed for flow control in complex micro- or nanofluidic systems.

  13. A field operational test on valve-regulated lead-acid absorbent-glass-mat batteries in micro-hybrid electric vehicles. Part I. Results based on kernel density estimation

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Karspeck, T.; Ott, C.; Weckler, M.; Stoermer, A. O.

    2011-03-01

    In March 2007 the BMW Group has launched the micro-hybrid functions brake energy regeneration (BER) and automatic start and stop function (ASSF). Valve-regulated lead-acid (VRLA) batteries in absorbent glass mat (AGM) technology are applied in vehicles with micro-hybrid power system (MHPS). In both part I and part II of this publication vehicles with MHPS and AGM batteries are subject to a field operational test (FOT). Test vehicles with conventional power system (CPS) and flooded batteries were used as a reference. In the FOT sample batteries were mounted several times and electrically tested in the laboratory intermediately. Vehicle- and battery-related diagnosis data were read out for each test run and were matched with laboratory data in a data base. The FOT data were analyzed by the use of two-dimensional, nonparametric kernel estimation for clear data presentation. The data show that capacity loss in the MHPS is comparable to the CPS. However, the influence of mileage performance, which cannot be separated, suggests that battery stress is enhanced in the MHPS although a battery refresh function is applied. Anyway, the FOT demonstrates the unsuitability of flooded batteries for the MHPS because of high early capacity loss due to acid stratification and because of vanishing cranking performance due to increasing internal resistance. Furthermore, the lack of dynamic charge acceptance for high energy regeneration efficiency is illustrated. Under the presented FOT conditions charge acceptance of lead-acid (LA) batteries decreases to less than one third for about half of the sample batteries compared to new battery condition. In part II of this publication FOT data are presented by multiple regression analysis (Schaeck et al., submitted for publication [1]).

  14. Electric Field Induced Interfacial Instabilities

    NASA Technical Reports Server (NTRS)

    Kusner, Robert E.; Min, Kyung Yang; Wu, Xiao-Lun; Onuki, Akira

    1996-01-01

    The study of the interface in a charge-free, nonpolar, critical and near-critical binary fluid in the presence of an externally applied electric field is presented. At sufficiently large fields, the interface between the two phases of the binary fluid should become unstable and exhibit an undulation with a predefined wavelength on the order of the capillary length. As the critical point is approached, this wavelength is reduced, potentially approaching length-scales such as the correlation length or critical nucleation radius. At this point the critical properties of the system may be affected. In zero gravity, the interface is unstable at all long wavelengths in the presence of a field applied across it. It is conjectured that this will cause the binary fluid to break up into domains small enough to be outside the instability condition. The resulting pattern formation, and the effects on the critical properties as the domains approach the correlation length are of acute interest. With direct observation, laser light scattering, and interferometry, the phenomena can be probed to gain further understanding of interfacial instabilities and the pattern formation which results, and dimensional crossover in critical systems as the critical fluctuations in a particular direction are suppressed by external forces.

  15. Electric Dipole Moment Experiment Systematic from Electric Field Discharge Current

    NASA Astrophysics Data System (ADS)

    Feinberg, B.; Gould, Harvey

    2014-09-01

    A magnetic field, in the direction of the electric field and synchronous with the electric field reversal, will mimic an EDM signal. One might expect a discharge across the electric field plates to produce magnetic fields with only small or vanishing components parallel to the electric field, minimizing its systematic effect. Our experimental model, using simulated discharge currents, found otherwise: the discharge current may be at an angle to the normal, and thus generate a normal magnetic field. Comparison of data from the experimental model with the results from calculations will be presented, along with estimates of the time-averaged normal magnetic field seen by atoms in an electron EDM experiment using a fountain of laser-cooled francium, as a function of discharge current.

  16. Electric Mars: The first survey of Martian parallel electric fields.

    NASA Astrophysics Data System (ADS)

    Collinson, G.; Mitchell, D. L.; Glocer, A.; Grebowsky, J. M.; Peterson, W. K.; Connerney, J. E. P.; Andersson, L.; Espley, J. R.; Mazelle, C. X.; Savaud, J. A.; Fedorov, A.; Ma, Y.; Bougher, S. W.; Lillis, R. J.; Ergun, R. E.; Jakosky, B. M.

    2015-12-01

    We present the results of the first survey of parallel electric fields at Mars, using electron measurements from the MAVEN Solar Wind Electron Analyzer (SWEA), and the Magnetometer (MAG). We discuss three fields: (1) The first upper limit on the strength of the "Polar Wind" ambipolar electric field; (2) The "trans-terminator" field, a newly discovered electric force accelerating ions on closed field lines from day to nightside, and (3) possible signatures of very high strength electrostatic mirroring during the passage of a Coronal Mass Ejection.

  17. Pair-production in inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Xue, She-Sheng

    2008-01-01

    This is a preliminary study on the rate of electron-positron pair production in spatially inhomogeneous electric fields. We study the rate in the Sauter field and compare it to the rate in the homogeneous field.

  18. Charged Hadron Properties in Background Electric Fields

    SciTech Connect

    William Detmold, Brian C. Tiburzi, Andre Walker-Loud

    2010-02-01

    We report on a lattice calculation demonstrating a novel new method to extract the electric polarizability of charged pseudo-scalar mesons by analyzing two point correlation functions computed in classical background electric fields.

  19. Electric-field guiding of magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Pramey; Yu, Guoqiang; Amiri, Pedram Khalili; Wang, Kang L.

    2015-10-01

    We theoretically study equilibrium and dynamic properties of nanosized magnetic skyrmions in thin magnetic films with broken inversion symmetry, where an electric field couples to magnetization via spin-orbit coupling. Based on a symmetry-based phenomenology and micromagnetic simulations we show that this electric-field coupling, via renormalizing the micromagnetic energy, modifies the equilibrium properties of the skyrmion. This change, in turn, results in a significant alteration of the current-induced skyrmion motion. Particularly, the speed and direction of the skyrmion can be manipulated by designing a desired energy landscape electrically, which we describe within Thiele's analytical model and demonstrate in micromagnetic simulations including electric-field-controlled magnetic anisotropy. We additionally use this electric-field control to construct gates for controlling skyrmion motion exhibiting a transistorlike and multiplexerlike function. The proposed electric-field effect can thus provide a low-energy electrical knob to extend the reach of information processing with skyrmions.

  20. Flexible intramuscular micro tube electrode combining electrical and chemical interface.

    PubMed

    Tian, Hong-Chang; Liu, Jing-Quan; Du, Jing-Cheng; Kang, Xiao-Yang; Zhang, Chuan; Yang, Bin; Chen, Xiang; Yang, Chun-Sheng

    2014-01-01

    With the rapidly developed micromachining technology, various kinds of sophisticated microelectrodes integrated with micro fluidic channels are design and fabricated for not only electrophysiological recording and stimulation, but also chemical drug delivery. As many efforts have been devoted to develop rigid microprobes for neural research of brain, few researchers concentrate on fabrication of flexible microelectrodes for intramuscular electrophysiology and chemical interfacing. Since crude wire electrodes still prevail in functional electrical stimulation (FES) and electromyography (EMG) recording of muscle, here we introduce a flexible micro tube electrode combining electrical and chemical pathway. The proposed micro tube electrode is manufactured based on polymer capillary, which provide circumferential electrode site contacting with electro-active tissue and is easy to manufactured with low cost.

  1. Compact Electric- And Magnetic-Field Sensor

    NASA Technical Reports Server (NTRS)

    Winterhalter, Daniel; Smith, Edward

    1994-01-01

    Compact sensor measures both electric and magnetic fields. Includes both short electric-field dipole and search-coil magnetometer. Three mounted orthogonally providing triaxial measurements of electromagnetic field at frequencies ranging from near 0 to about 10 kHz.

  2. Imaging electric field dynamics with graphene optoelectronics

    PubMed Central

    Horng, Jason; Balch, Halleh B.; McGuire, Allister F.; Tsai, Hsin-Zon; Forrester, Patrick R.; Crommie, Michael F.; Cui, Bianxiao; Wang, Feng

    2016-01-01

    The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena. PMID:27982125

  3. Imaging electric field dynamics with graphene optoelectronics

    NASA Astrophysics Data System (ADS)

    Horng, Jason; Balch, Halleh B.; McGuire, Allister F.; Tsai, Hsin-Zon; Forrester, Patrick R.; Crommie, Michael F.; Cui, Bianxiao; Wang, Feng

    2016-12-01

    The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.

  4. Entanglement generation by electric field background

    SciTech Connect

    Ebadi, Zahra Mirza, Behrouz

    2014-12-15

    The quantum vacuum is unstable under the influence of an external electric field and decays into pairs of charged particles, a process which is known as the Schwinger pair production. We propose and demonstrate that this electric field can generate entanglement. Using the Schwinger pair production for constant and pulsed electric fields, we study entanglement for scalar particles with zero spins and Dirac fermions. One can observe the variation of the entanglement produced for bosonic and fermionic modes with respect to different parameters.

  5. The electron signature of parallel electric fields

    NASA Astrophysics Data System (ADS)

    Burch, J. L.; Gurgiolo, C.; Menietti, J. D.

    1990-12-01

    Dynamics Explorer I High-Altitude Plasma Instrument electron data are presented. The electron distribution functions have characteristics expected of a region of parallel electric fields. The data are consistent with previous test-particle simulations for observations within parallel electric field regions which indicate that typical hole, bump, and loss-cone electron distributions, which contain evidence for parallel potential differences both above and below the point of observation, are not expected to occur in regions containing actual parallel electric fields.

  6. Development of new atomic scale defect identification schemes in micro / nanoelectronics incorporating digital signal processing methods for investigating zero/low field spin dependent transport and passage effects in electrically detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Cochrane, Corey J.

    This work focuses on the development of new techniques for the study of spin dependent transport and trapping centers in fully processed micro and nanoelectronics. The first, and most interesting, technique offers a very low cost means to study spin dependent transport in microelectronics as an alternative to electrically detected magnetic resonance (EDMR). EDMR measurements generally require strong static magnetic fields, typically 3 kG or greater, and high frequency oscillating electromagnetic fields, typically 9 GHz or higher. In this work, it is demonstrated that large spin dependent recombination and tunneling signals can be detected in the absence of the oscillating electromagnetic field at zero magnetic field. The physics behind this technique is based upon the mixing of singlet and triplet energy states of the electron spin pairs involved in the spin dependent processes. In this study, we show that this technique can be applied to Si and SiC based devices. Theoretically, it can be applicable to devices of all material systems in which defects play a role in spin dependent transport, some of which include CdTe and GaN. Although the resolution of the g value is sacrificed in this new measurement, the technique can detect electron-nuclear hyperfine interactions and possibly dipolar and exchange interactions. The technique also has great promise in microelectronic device reliability studies as it is directly applicable to time dependent dielectric breakdown in thin film dielectrics and bias temperature instabilities in transistors. Other applications of this new physics include self-calibrating magnetometers, spin based memories, quantum computation, and miniature EDMR spectrometers for wafer probing stations. The second technique involves the utilization of passage effects that arise when performing magnetic field modulation in EDMR. When certain conditions are met, the higher order harmonics of the spin dependent signal can contain much useful information

  7. Plasma heating by electric field compression.

    PubMed

    Avinash, K; Kaw, P K

    2014-05-09

    Plasma heating by compression of electric fields is proposed. It is shown that periodic cycles of external compression followed by the free expansion of electric fields in the plasma cause irreversible, collisionless plasma heating and corresponding entropy generation. As a demonstration of general ideas and scalings, the heating is shown in the case of a dusty plasma, where electric fields are created due to the presence of charged dust. The method is expected to work in the cases of compression of low frequency or dc electric fields created by other methods. Applications to high power laser heating of plasmas using this scheme are discussed.

  8. Electrically small, complementary electric-field-coupled resonator antennas

    NASA Astrophysics Data System (ADS)

    Odabasi, H.; Teixeira, F. L.; Guney, D. O.

    2013-02-01

    We study the radiation properties of electrically small resonant antennas (ka <1) composed of electric-field-coupled (ELC) and complementary electric-field-coupled (CELC) resonators and a monopole antenna. We use such parasitic ELC and CELC "metaresonators" to design various electrically small antennas. In particular, monopole-excited and bent-monopole-excited CELC resonator antennas are proposed that provide very low profiles on the order of λ0/20. We compare the performance of the proposed ELC and CELC antennas against more conventional designs based upon split-ring resonators.

  9. The Electric Field of a Weakly Electric Fish

    NASA Astrophysics Data System (ADS)

    Rasnow, Brian K.

    Freshwater fish of the genus Apteronotus (family Gymnotidae) generate a weak, high frequency electric field (<100 mV/cm, 0.5-10 kHz) which permeates their local environment. These nocturnal fish are acutely sensitive to perturbations in their electric field caused by other electric fish, and nearby objects whose impedance is different from the surrounding water. This thesis presents high temporal and spatial resolution maps of the electric potential and field on and near Apteronotus. The fish's electric field is a complicated and highly stable function of space and time. Its characteristics, such as spectral composition, timing, and rate of attenuation, are examined in terms of physical constraints, and their possible functional roles in electroreception. Temporal jitter of the periodic field is less than 1 musec. However, electrocyte activity is not globally synchronous along the fish's electric organ. The propagation of electrocyte activation down the fish's body produces a rotation of the electric field vector in the caudal part of the fish. This may assist the fish in identifying nonsymmetrical objects, and could also confuse electrosensory predators that try to locate Apteronotus by following its fieldlines. The propagation also results in a complex spatiotemporal pattern of the EOD potential near the fish. Visualizing the potential on the same and different fish over timescales of several months suggests that it is stable and could serve as a unique signature for individual fish. Measurements of the electric field were used to calculate the effects of simple objects on the fish's electric field. The shape of the perturbation or "electric image" on the fish's skin is relatively independent of a simple object's size, conductivity, and rostrocaudal location, and therefore could unambiguously determine object distance. The range of electrolocation may depend on both the size of objects and their rostrocaudal location. Only objects with very large dielectric

  10. Electric field soundings through thunderstorms

    NASA Technical Reports Server (NTRS)

    Marshall, Thomas C.; Rust, W. D.

    1991-01-01

    Twelve balloon soundings of the electric field in thunderstorms are reported. The maximum magnitude of E in the storms averaged 96 +/-28 kV/m, with the largest being 146 kV/m. The maximum was usually observed between vertically adjacent regions of opposite charge. Using a 1D approximation to Gauss' law, four to ten charge regions in the storms are inferred. The magnitude of the density in the charge regions varied between 0.2 and 13 nC/cu m. The vertical extent of the charge regions ranged from 130 to 2100 m. None of the present 12 storms had charge distributions that fit the long-accepted model of Simpson et al. (1937, 1941) of a lower positive charge, a main negative charge, and an upper positive charge. In addition to regions similar to the Simpson model, the present storms had screening layers at the upper and lower cloud boundaries and extra charge regions, usually in the lower part of the cloud.

  11. Electric fields in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.

    1975-01-01

    F-region drift velocities, measured by incoherent-scatter radar were analyzed in terms of diurnal, seasonal, magnetic activity, and solar cycle effects. A comprehensive electric field model was developed that includes the effects of the E and F-region dynamos, magnetospheric sources, and ionospheric conductivities, for both the local and conjugate regions. The E-region dynamo dominates during the day but at night the F-region and convection are more important. This model provides much better agreement with observations of the F-region drifts than previous models. Results indicate that larger magnitudes occur at night, and that daily variation is dominated by the diurnal mode. Seasonal variations in conductivities and thermospheric winds indicate a reversal in direction in the early morning during winter from south to northward. On magnetic perturbed days and the drifts deviate rather strongly from the quiet days average, especially around 13 L.T. for the northward and 18 L.T. for the westward component.

  12. Electric field soundings through thunderstorms

    NASA Technical Reports Server (NTRS)

    Marshall, Thomas C.; Rust, W. D.

    1991-01-01

    Twelve balloon soundings of the electric field in thunderstorms are reported. The maximum magnitude of E in the storms averaged 96 +/-28 kV/m, with the largest being 146 kV/m. The maximum was usually observed between vertically adjacent regions of opposite charge. Using a 1D approximation to Gauss' law, four to ten charge regions in the storms are inferred. The magnitude of the density in the charge regions varied between 0.2 and 13 nC/cu m. The vertical extent of the charge regions ranged from 130 to 2100 m. None of the present 12 storms had charge distributions that fit the long-accepted model of Simpson et al. (1937, 1941) of a lower positive charge, a main negative charge, and an upper positive charge. In addition to regions similar to the Simpson model, the present storms had screening layers at the upper and lower cloud boundaries and extra charge regions, usually in the lower part of the cloud.

  13. Modeling the electric field of weakly electric fish.

    PubMed

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

    2006-09-01

    Weakly electric fish characterize the environment in which they live by sensing distortions in their self-generated electric field. These distortions result in electric images forming across their skin. In order to better understand electric field generation and image formation in one particular species of electric fish, Apteronotus leptorhynchus, we have developed three different numerical models of a two-dimensional cross-section of the fish's body and its surroundings. One of these models mimics the real contour of the fish; two other geometrically simple models allow for an independent study of the effects of the fish's body geometry and conductivity on electric field and image formation. Using these models, we show that the fish's tapered body shape is mainly responsible for the smooth, uniform field in the rostral region, where most electroreceptors are located. The fish's narrowing body geometry is also responsible for the relatively large electric potential in the caudal region. Numerical tests also confirm the previous hypothesis that the electric fish body acts approximately like an ideal voltage divider; this is true especially for the tail region. Next, we calculate electric images produced by simple objects and find they vary according to the current density profile assigned to the fish's electric organ. This explains some of the qualitative differences previously reported for different modeling approaches. The variation of the electric image's shape as a function of different object locations is explained in terms of the fish's geometrical and electrical parameters. Lastly, we discuss novel cues for determining an object's rostro-caudal location and lateral distance using these electric images.

  14. Estimating Electric Fields from Vector Magnetogram Sequences

    NASA Astrophysics Data System (ADS)

    Fisher, George H.; Welsch, B. T.; Abbett, W. P.; Bercik, D. J.

    2009-05-01

    We describe a new technique for estimating the three-dimensional vector electric field in the solar atmosphere by using a time-sequence of vector magnetograms to find an electric field distribution that obeys all 3 components of Faraday's law. The technique uses a ``poloidal-toroidal'' decomposition (PTD) to describe the electric field in terms of two scalar functions. The ``inductive'' PTD solutions to Faraday's Law are not unique, however, since additional contributions to the electric field from a potential function have no effect on Faraday's law. We then describe how estimates for the total electric field including both the inductive and potential components can be made by using variational techniques. The variational approach we develop is similar to Longcope's ``Minimum Energy Fit'' technique, in that the electric field obeys the vertical component of the magnetic induction equation, while also minimizing a positive definite functional. The purely potential part of the electric field can then be recovered by subtracting the PTD electric field from the total field.

  15. Electric-field and magnetic-field sensors

    NASA Astrophysics Data System (ADS)

    Wieckowski, T. W.

    1993-05-01

    Analysis of double-loaded loop antennas and their properties has led to the design of new measuring sensors which enable has led to determination of both electric field strength and magnetic field strength. Sensors of the design proposed are applicable to a quasipoint measurement providing independent determination of the electric and magnetic component of the field.

  16. Method of using an electric field controlled emulsion phase contactor

    DOEpatents

    Scott, T.C.

    1993-11-16

    A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figures.

  17. Method of using an electric field controlled emulsion phase contactor

    DOEpatents

    Scott, Timothy C.

    1993-01-01

    A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

  18. Electric Potential and Electric Field Imaging with Applications

    NASA Technical Reports Server (NTRS)

    Generazio, Ed

    2016-01-01

    The technology and techniques for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field may be used for (illuminating) volumes to be inspected with EFI. The baseline sensor technology, electric field sensor (e-sensor), and its construction, optional electric field generation (quasistatic generator), and current e-sensor enhancements (ephemeral e-sensor) are discussed. Demonstrations for structural, electronic, human, and memory applications are shown. This new EFI capability is demonstrated to reveal characterization of electric charge distribution, creating a new field of study that embraces areas of interest including electrostatic discharge mitigation, crime scene forensics, design and materials selection for advanced sensors, dielectric morphology of structures, inspection of containers, inspection for hidden objects, tether integrity, organic molecular memory, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

  19. Electric Field Generation in Martian Dust Devils

    NASA Technical Reports Server (NTRS)

    Barth, Erika L.; Farrell, William M.; Rafkin, Scot C. R.

    2015-01-01

    Terrestrial dust devils are known to generate electric fields from the vertical separation of charged dust particles. The particles present within the dust devils on Mars may also be subject to similar charging processes and so likely contribute to electric field generation there as well. However, to date, no Marsin situ instrumentation has been deployed to measure electric field strength. In order to explore the electric environment of dust devils on Mars, the triboelectric dust charging physics from the MacroscopicTriboelectric Simulation (MTS) code has been coupled to the Mars Regional Atmospheric ModelingSystem (MRAMS). Using this model, we examine how macroscopic electric fields are generated within martian dust disturbances and attempt to quantify the time evolution of the electrodynamical system.Electric fields peak for several minutes within the dust devil simulations. The magnitude of the electric field is a strong function of the size of the particles present, the average charge on the particles and the number of particles lifted. Varying these parameters results in peak electric fields between tens of millivolts per meter and tens of kilovolts per meter.

  20. Electric Field Generation in Martian Dust Devils

    NASA Technical Reports Server (NTRS)

    Barth, Erika L.; Farrell, William M.; Rafkin, Scot C. R.

    2015-01-01

    Terrestrial dust devils are known to generate electric fields from the vertical separation of charged dust particles. The particles present within the dust devils on Mars may also be subject to similar charging processes and so likely contribute to electric field generation there as well. However, to date, no Marsin situ instrumentation has been deployed to measure electric field strength. In order to explore the electric environment of dust devils on Mars, the triboelectric dust charging physics from the MacroscopicTriboelectric Simulation (MTS) code has been coupled to the Mars Regional Atmospheric ModelingSystem (MRAMS). Using this model, we examine how macroscopic electric fields are generated within martian dust disturbances and attempt to quantify the time evolution of the electrodynamical system.Electric fields peak for several minutes within the dust devil simulations. The magnitude of the electric field is a strong function of the size of the particles present, the average charge on the particles and the number of particles lifted. Varying these parameters results in peak electric fields between tens of millivolts per meter and tens of kilovolts per meter.

  1. Electric field generation in martian dust devils

    NASA Astrophysics Data System (ADS)

    Barth, Erika L.; Farrell, William M.; Rafkin, Scot C. R.

    2016-04-01

    Terrestrial dust devils are known to generate electric fields from the vertical separation of charged dust particles. The particles present within the dust devils on Mars may also be subject to similar charging processes and so likely contribute to electric field generation there as well. However, to date, no Mars in situ instrumentation has been deployed to measure electric field strength. In order to explore the electric environment of dust devils on Mars, the triboelectric dust charging physics from the Macroscopic Triboelectric Simulation (MTS) code has been coupled to the Mars Regional Atmospheric Modeling System (MRAMS). Using this model, we examine how macroscopic electric fields are generated within martian dust disturbances and attempt to quantify the time evolution of the electrodynamical system. Electric fields peak for several minutes within the dust devil simulations. The magnitude of the electric field is a strong function of the size of the particles present, the average charge on the particles and the number of particles lifted. Varying these parameters results in peak electric fields between tens of millivolts per meter and tens of kilovolts per meter.

  2. The dust nature of micro field emitters in accelerators

    NASA Astrophysics Data System (ADS)

    Volkov, V.; Petrov, V. M.

    2016-11-01

    Field emission currents emitted by micro-emitters are a limiting factor for the operational gradients of accelerating radio frequency (rf) cavities. Within the rf field emission theory the existence of needle like micro field emitters with very high length relative to the radius and corresponding high enhancement factor (β) is assumed. In this article the hypothesis that micro field emitters consists of long chains of conductive micro-particles is considered. Five different forces acting onto the particles in a high rf field are considered and the respective equations are derived. Some experimental observations and their explanation within this hypothesis are discussed.

  3. Off-Grid Electricity Access and its Impact on Micro-Enterprises: Evidence from Rural Uganda

    NASA Astrophysics Data System (ADS)

    Muhoro, Peter N.

    The history of development shows convincingly that no country has substantially reduced poverty without massively increasing the use of electricity. The development of micro-enterprises in rural areas of Uganda is linked with increased access and use of electricity services. In this study, I combine quantitative and qualitative methods, including informal surveys, intra-business energy allocation studies and historical analysis, to analyze off-grid electricity access among micro-enterprises in rural western Uganda. I explore the linkages between of grid electricity access and the influence it has on micro- enterprises. Data is obtained from 56 micro-enterprises located in 11 village-towns within 3 districts in Uganda. In studying the micro-enterprises. the focus is on the services that are provided by electricity from modern energy carriers. The type of equipment used, forms of transportation, technical support, level of understanding and education of the entrepreneur, financing for energy equipment, and the role of donors are discussed in this thesis. Qualitative methods are used to allow for new insights and prioritization of concepts to emerge from the field rattier than from theory. Micro-enterprises in rural Uganda create income for the poor; they are resources for poverty reduction. With price adjustments, it becomes possible for those who live below the poverty line, nominally less than $1 a day, to afford the products and services and therefore mitigating the vicious cycle of poverty. Energy consumption among the micro-enterprises is at an average of 0.13kWh/day. The cost of accessing this amount of electricity attributes to about 50% of total revenue. I find that the "practices" used in off-grid electricity access lead to situations where the entrepreneurs have to evaluate pricing and output of products and services to generate higher profits. Such numbers indicate the need for appropriate technologies and profitable policies to be implemented. The data

  4. Horizontal electric fields from lightning return strokes

    NASA Technical Reports Server (NTRS)

    Thomson, E. M.; Medelius, P. J.; Rubinstein, M.; Uman, M. A.; Johnson, J.

    1988-01-01

    An experiment to measure simultaneously the wideband horizontal and vertical electric fields from lightning return strokes is described. Typical wave shapes of the measured horizontal and vertical fields are presented, and the horizontal fields are characterized. The measured horizontal fields are compared with calculated horizontal fields obtained by applying the wavetilt formula to the vertical fields. The limitations and sources of error in the measurement technique are discussed.

  5. Interaction Between Flames and Electric Fields Studied

    NASA Technical Reports Server (NTRS)

    Yuan, Zeng-Guang; Hegde, Uday

    2003-01-01

    The interaction between flames and electric fields has long been an interesting research subject that has theoretical importance as well as practical significance. Many of the reactions in a flame follow an ionic pathway: that is, positive and negative ions are formed during the intermediate steps of the reaction. When an external electric field is applied, the ions move according to the electric force (the Coulomb force) exerted on them. The motion of the ions modifies the chemistry because the reacting species are altered, it changes the velocity field of the flame, and it alters the electric field distribution. As a result, the flame will change its shape and location to meet all thermal, chemical, and electrical constraints. In normal gravity, the strong buoyant effect often makes the flame multidimensional and, thus, hinders the detailed study of the problem.

  6. Fiber-Optic Electric-Field Meter

    NASA Technical Reports Server (NTRS)

    Johnston, A. R.

    1986-01-01

    Sensor for measuring electric-field strength does not greatly alter field in which placed. Sensor used to map fields in electric power substation or under high-voltage transmission line. Also used for laboratory measurements. Fused-silica fibers guide light from source to photometer. Light emerges from tip of source fiber, passes through curved coupler, and enters tip of photometer fiber. Attenuation of coupler changes with distance between fiber tips.

  7. Molecular dynamics in high electric fields

    NASA Astrophysics Data System (ADS)

    Apostol, M.; Cune, L. C.

    2016-06-01

    Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two particular cases are analyzed, corresponding to strong and weak fields. In both cases the classical motion of the dipoles consists of rotations and vibrations about equilibrium positions; this motion may exhibit parametric resonances. For strong fields a large macroscopic electric polarization may appear. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid. The dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes appear for a spontaneous macroscopic electric polarization (these modes are tentatively called "dipolons"); one of the polarization modes is related to parametric resonances. The extension of these considerations to magnetic dipoles is briefly discussed. The treatment is extended to strong electric fields which oscillate with a high frequency, as those provided by high-power lasers. It is shown that the effect of such fields on molecular dynamics is governed by a much weaker, effective, renormalized, static electric field.

  8. Electric field replaces gravity in laboratory

    NASA Astrophysics Data System (ADS)

    Gorgolewski, S.

    For several years experiments in physical laboratories and in the fitotron have shown that one can replace gravitational field with electrical fields for plants. First obvious experiments in strong electrical fields in the MV/m regi on show that any materials and living plants respond immediately to Coulomb forces. Such fields are found in nature during thunderstorms. One has to be very careful in handling such strong fields for safety reasons. The fair weather global electrical field is about 20,000 times weaker. The coulomb forces are proportional to the square of the field strength and are thus 400 milion times weaker for a field of the order of 100 V/m.Yet it was found that some plants respond to such "weak" fields. We must remember that the electrical field is a factor of 10 38 times stronger than gravitational interaction. In plants we have dissociated in water mineral salts and the ions are subject to such ernormous forces. It was shown and published that the positive charges in the air in fields of the order of 3kV/m enhance lettuce growth by a factor of four relative to fields about 30 times weaker (100V/m). Reversal of the field polarity reverses the direction of plant growth and retards the plant's growth. Such fields overpower the gravitropism in the laboratory. More so horizontal electrical field is othogonal to gravity, now the fields do not see each other. Lettuce now growth horizontally ignoring the gravitational field. We can thus select the plants whose electrotropism even in the laboratory overwhelms gravity. This is important for the long space flights that we must grow vegetarian food for the crew. The successful harvesting of wheat in orbit does not contradict our experimental findings because wheat is not electrotropic like all plants from the grass family. The results of fitotron experiments with kV/m electrical fields are richly illustrated with colour digital photographs. We also subjected the candle flame to very strong horizontal

  9. Experimental study of micro electrical discharge machining discharges

    SciTech Connect

    Braganca, I. M. F.; Rosa, P. A. R.; Martins, P. A. F.; Dias, F. M.; Alves, L. L.

    2013-06-21

    Micro electrical discharge machining ({mu}EDM) is an atmospheric-pressure plasma-assisted technology that uses point-to-plane discharges in liquid dielectrics to remove microscopic quantities of electrically conductive materials. In this work, an innovative {mu}EDM prototype machine was specifically designed and fabricated to produce and control single spark discharges, thus, resolving the typical limitations of (multi-discharge) commercial machines. The work analyses the type of discharge and the micro-plasma electron-density values obtained for 0.5-38 {mu}m gap sizes, 3-10 000 {mu}s pulse durations, 75-250 V low breakdown voltages, and 1-20 A discharge currents, using different combinations of metallic electrodes in oil and in water. Results allow fitting, for micro-scale and low voltages, an empirical law between the maximum gap-size for breakdown, the breakdown voltage, and the effective stress-time. The electron density n{sub e} is obtained by optical emission spectroscopy diagnostics of the H{sub {alpha}}-line Stark broadening (yielding n{sub e}{approx}10{sup 16}-10{sup 17} cm{sup -3}, i.e., ionization degrees of {approx}2 Multiplication-Sign 10{sup -5}-10{sup -4}) and by a semi-empirical resistive plasma model. The model uses the experimental values of several electrical and geometrical quantities, and of the gas pressure estimated as {approx}60 bar-2 kbar from measurements of the plasma mechanical action, obtained using a force sensor. The quantitative information of this phenomenological study can assist the optimization of this micro-fabrication technique.

  10. Experimental study of micro electrical discharge machining discharges

    NASA Astrophysics Data System (ADS)

    Bragança, I. M. F.; Rosa, P. A. R.; Dias, F. M.; Martins, P. A. F.; Alves, L. L.

    2013-06-01

    Micro electrical discharge machining (μEDM) is an atmospheric-pressure plasma-assisted technology that uses point-to-plane discharges in liquid dielectrics to remove microscopic quantities of electrically conductive materials. In this work, an innovative μEDM prototype machine was specifically designed and fabricated to produce and control single spark discharges, thus, resolving the typical limitations of (multi-discharge) commercial machines. The work analyses the type of discharge and the micro-plasma electron-density values obtained for 0.5-38 μm gap sizes, 3-10 000 μs pulse durations, 75-250 V low breakdown voltages, and 1-20 A discharge currents, using different combinations of metallic electrodes in oil and in water. Results allow fitting, for micro-scale and low voltages, an empirical law between the maximum gap-size for breakdown, the breakdown voltage, and the effective stress-time. The electron density ne is obtained by optical emission spectroscopy diagnostics of the Hα-line Stark broadening (yielding ne˜1016-1017 cm-3, i.e., ionization degrees of ˜2×10-5-10-4) and by a semi-empirical resistive plasma model. The model uses the experimental values of several electrical and geometrical quantities, and of the gas pressure estimated as ˜60 bar-2 kbar from measurements of the plasma mechanical action, obtained using a force sensor. The quantitative information of this phenomenological study can assist the optimization of this micro-fabrication technique.

  11. Control of magnetism by electric fields.

    PubMed

    Matsukura, Fumihiro; Tokura, Yoshinori; Ohno, Hideo

    2015-03-01

    The electrical manipulation of magnetism and magnetic properties has been achieved across a number of different material systems. For example, applying an electric field to a ferromagnetic material through an insulator alters its charge-carrier population. In the case of thin films of ferromagnetic semiconductors, this change in carrier density in turn affects the magnetic exchange interaction and magnetic anisotropy; in ferromagnetic metals, it instead changes the Fermi level position at the interface that governs the magnetic anisotropy of the metal. In multiferroics, an applied electric field couples with the magnetization through electrical polarization. This Review summarizes the experimental progress made in the electrical manipulation of magnetization in such materials, discusses our current understanding of the mechanisms, and finally presents the future prospects of the field.

  12. Physics and Chemistry in High Electric Fields

    DTIC Science & Technology

    1992-10-06

    in heterogeneous catalysis and in chemical vapor deposition, may be established. To discuss field effects qualitatively, we look, in Fig. 1, at a...fields thus opening up new reaction pathways in heterogeneous catalysis . Most work so far has been concentrating on static electric fields; how- ever

  13. Control of magnetism in Co by an electric field

    NASA Astrophysics Data System (ADS)

    Chiba, D.; Ono, T.

    2013-05-01

    In this paper, we review the recent experimental developments on electric-field switching of ferromagnetism in ultra-thin Co films. The application of an electric field changes the electron density at the surface of the Co film, which results in modulation of its Curie temperature. A capacitor structure consisting of a gate electrode, a solid-state dielectric insulator and a Co bottom electrode is used to observe the effect. To obtain a larger change in the electron density, we also fabricated an electric double-layer capacitor structure using an ionic liquid. A large change in the Curie temperature of ∼100 K across room temperature is achieved with this structure. The application of the electric field influences not only the Curie temperature but also the domain-wall motion. A change in the velocity of a domain wall prepared in a Co micro-wire of more than one order of magnitude is observed. Possible mechanisms to explain the above-mentioned electric-field effects in Co ultra-thin films are discussed.

  14. Electric field imaging of single atoms

    NASA Astrophysics Data System (ADS)

    Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

    2017-05-01

    In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures.

  15. Electric field imaging of single atoms

    PubMed Central

    Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

    2017-01-01

    In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629

  16. Electric field imaging of single atoms.

    PubMed

    Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

    2017-05-30

    In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures.

  17. Electrically tunable micro-lens with a strain-enhanced polymer nanocomposite actuator (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Costache, Florenta A.; Pawlik, Boscij; Rieck, Andreas

    2017-02-01

    A fluid-filled micro-lens concept with an electrically driven polymer actuator was developed in view of optimization of its variation in focal length. The high strain electrostrictive terpolymer P(VDF-TrFE-CFE) was first used in the actuator design for this purpose. Our study showed that the electric field-induced strain in polymer thin films could be even further enhanced by mixing high-k BaTiO3 nanoparticles in the terpolymer. A newly developed nanocomposite P(VDF-TrFE-CFE) / BaTiO3 ring-shaped actuator was implemented into the 3 mm aperture, liquid-filled micro-lens concept. The micro-lens was fabricated in a wafer-level process flow, which included micromachining of fluidic chambers on silicon wafers, thin film nanocomposite actuator processing, assembly through wafer bonding and chip filling with liquids. Particular characteristics of the nanocomposite were taken into account such as the homogeneous nanoparticle dispersion into the thin film with impact on thin film dielectric breakdown, electrode adherence as well as nanocomposite film etching. Variable focal length micro-lenses conceps with a single fluidic chamber but also with two fluidic chambers (a design, which can potentially improve the lens membrane stability) were fabricated and characterized. We could demonstrate a wide focal length variation of tens of diopters first for a single chamber plano-convex micro-lens obtained by adjusting the voltage applied on the integrated actuator.

  18. Electric field control of the magnetocaloric effect.

    PubMed

    Gong, Yuan-Yuan; Wang, Dun-Hui; Cao, Qing-Qi; Liu, En-Ke; Liu, Jian; Du, You-Wei

    2015-02-04

    Through strain-mediated magnetoelectric coupling, it is demonstrated that the magnetocaloric effect of a ferromagnetic shape-memory alloy can be controlled by an electric field. Large hysteresis and the limited operating temperature region are effectively overcome by applying an electric field on a laminate comprising a piezoelectric and the alloy. Accordingly, a model for an active magnetic refrigerator with high efficiency is proposed in principle.

  19. Pulsed Electric Fields for Biological Weapons Defense

    DTIC Science & Technology

    2002-01-01

    studies of Bacillus atrophaeus (formerly Bacillus subtilis var. niger). 15. SUBJECT TERMS nanosecond high-field electric pulse, electroperturbation...sterility monitoring kit, which utilizes spores of Bacillus atrophaeus (formerly Bacillus subtilis var. niger) deposited on paper in glassine envelopes, has...report a study of the application of ultra- short high-field electric pulses (5 MV/m, 100-ns pulse width, 4-ns rise time) to Bacillus atrophaeus spores

  20. Microwave ovens: mapping the electrical field distribution.

    PubMed

    Ng, K H

    1991-07-01

    Uniformity of electric field intensity of microwaves within the microwave oven cavity is necessary to ensure even load-heating, and is particularly important in pathology procedures where small volume irradiation is carried out. A simple and rapid method for mapping electric field distribution, using reversible thermographic paint, is described. Spatial heating patterns for various positions, and the effects of introducing dummy loads to modify heating distributions, have been obtained for a dedicated microwave processor, and comparison made with a domestic microwave oven.

  1. Tendon Fibroplasia Induction by Exogenous Electrical Fields.

    DTIC Science & Technology

    1986-08-10

    AD-A172 279 TENDON FIEROPLASIA INDUCTION BY EXOGENOUS ELECTRICAL 1/𔃻 FIELDS(U) MEDICAL COLL OF VIRGINIA RICHMOND DEPT OF PHYSIOLOGY AND BIOPHYSICS S...Security Classification) Tendon Fibroplasia Induction by Exogenous Electrical Fields l2dAL 9I F.; Liu, Li-Ming. 134. TYPE PF REPORT 13b. TIME COVERED 14... tendon explant fibroplasia, collagen synthesis and oriented migration. Independent variables are: pulse repetition rate, pulse duration, peak current

  2. Geological applications using an electrical micro imaging tool

    SciTech Connect

    Eubanks, D.; Seiler, D.; Russell, B.

    1995-11-20

    The resistivity micro imaging tool introduced by Halliburton produces electrical images that are being used in a variety of geological applications. The tool is a microresistivity-type imaging device with six independent articulating arms extending from the main body.Each arm is mounted with a pad containing a 25-electrode scanning array. The EMI tool and all other micro imaging devices measure changes in resistivity along the borehole wall that correspond to subtle changes in rock composition, grain texture, and fluid properties. High-end graphics software processes the data to produce highly visual 2D and 3D images of the borehole. The paper describes the use of this tool in fault analysis, fracture analysis, rock texture, strata dip analysis, and thin-bed analysis.

  3. Electric/magnetic field sensor

    SciTech Connect

    Schill, Jr., Robert A.; Popek, Marc

    2009-01-27

    A UNLV novel electric/magnetic dot sensor includes a loop of conductor having two ends to the loop, a first end and a second end; the first end of the conductor seamlessly secured to a first conductor within a first sheath; the second end of the conductor seamlessly secured to a second conductor within a second sheath; and the first sheath and the second sheath positioned adjacent each other. The UNLV novel sensor can be made by removing outer layers in a segment of coaxial cable, leaving a continuous link of essentially uncovered conductor between two coaxial cable legs.

  4. Electric field measurements with stratospheric balloons

    NASA Technical Reports Server (NTRS)

    Iversen, I. B.

    1989-01-01

    Electric fields and currents in the middle atmosphere are important elements of the modern picture of this region. Balloon instruments, reaching the level of the stratosphere, were used extensively for the experimental work. The research has shown good progress, both in the MAP period and in the years before and after. The knowledge was increased about, e.g., the upper atmosphere potential, the electric properties of the medium itself and about the coupling with magnetospheric (ionospheric) fields and currents. Also various measurements have brought about a discussion of the possible existence of hitherto unknown sources. Throughout the MAP period the work on a possible definition of an electric index has continued.

  5. Crystal growth under external electric fields

    SciTech Connect

    Uda, Satoshi; Koizumi, Haruhiko; Nozawa, Jun; Fujiwara, Kozo

    2014-10-06

    This is a review article concerning the crystal growth under external electric fields that has been studied in our lab for the past 10 years. An external field is applied electrostatically either through an electrically insulating phase or a direct injection of an electric current to the solid-interface-liquid. The former changes the chemical potential of both solid and liquid and controls the phase relationship while the latter modifies the transport and partitioning of ionic solutes in the oxide melt during crystallization and changes the solute distribution in the crystal.

  6. Adaptive electric field control of epileptic seizures.

    PubMed

    Gluckman, B J; Nguyen, H; Weinstein, S L; Schiff, S J

    2001-01-15

    We describe a novel method of adaptively controlling epileptic seizure-like events in hippocampal brain slices using electric fields. Extracellular neuronal activity is continuously recorded during field application through differential extracellular recording techniques, and the applied electric field strength is continuously updated using a computer-controlled proportional feedback algorithm. This approach appears capable of sustained amelioration of seizure events in this preparation when used with negative feedback. Seizures can be induced or enhanced by using fields of opposite polarity through positive feedback. In negative feedback mode, such findings may offer a novel technology for seizure control. In positive feedback mode, adaptively applied electric fields may offer a more physiological means of neural modulation for prosthetic purposes than previously possible.

  7. Rotating Capacitor Measures Steady Electric Fields

    NASA Technical Reports Server (NTRS)

    Johnston, A. R.; Kirkham, H.; Eng, B.

    1986-01-01

    Portable sensor measures electric fields created by dc powerlines or other dc-high-voltage sources. Measures fields from 70 to 50,000 V/m with linearity of 2 percent. Sensor used at any height above ground. Measures both magnitude and direction of field and provides signals representing these measurements to remote readout device. Sensor functions with minimal disturbance of field it is measuring.

  8. Midday reversal of equatorial ionospheric electric field

    NASA Astrophysics Data System (ADS)

    Rastogi, R. G.

    1997-10-01

    A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956-1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

  9. Magnetospheric electric fields and auroral oval

    NASA Technical Reports Server (NTRS)

    Laakso, Harri; Pedersen, Arne; Craven, John D.; Frank, L. A.

    1992-01-01

    DC electric field variations in a synchronous orbit (GEOS 2) during four substorms in the time sector 19 to 01 LT were investigated. Simultaneously, the imaging photometer on board DE 1 provided auroral images that are also utilized. Substorm onset is defined here as a sudden appearance of large electric fields. During the growth phase, the orientation of the electric field begins to oscillate some 30 min prior to onset. About 10 min before the onset GEOS 2 starts moving into a more tenuous plasma, probably due to a thinning of the current sheet. The onset is followed by a period of 10 to 15 min during which large electric fields occur. This interval can be divided into two intervals. During the first interval, which lasts 4 to 8 min, very large fields of 8 to 20 mV/m are observed, while the second interval contains relatively large fields (2 to 5 mV/m). A few min after the onset, the spacecraft returns to a plasma region of higher electron fluxes which are usually larger than before substorm. Some 30 min after onset, enhanced activity, lasting about 10 min, appears in the electric field. One of the events selected offers a good opportunity to study the formation and development of the Westward Traveling Surge (WST). During the traversal of the leading edge of the WTS (approximately 8 min) a stable wave mode at 5.7 mHz is detected.

  10. Biological effects of electric fields: EPRI's role

    SciTech Connect

    Kavet, R.

    1982-07-01

    Since 1973 the Electric Power Research Institute (EPRI) has supported research to evaluate the biological effects which may result from exposure to electric fields produced by AC overhead transmission lines; more recently, EPRI has also begun DC research. Through 1981 EPRI will have expended $8.7M on these efforts. Ongoing AC projects are studying a variety of lifeforms exposed to electric fields; these include humans, miniature swine, rats, honeybees, chick embryos, and crops. The status of these projects is discussed. The DC program has not as yet produced data. These studies will add to the current data base so as to enable a more complete assessment of health risks which may be associated with exposure to electric fields at power frequencies.

  11. Electric field induced spin-polarized current

    DOEpatents

    Murakami, Shuichi; Nagaosa, Naoto; Zhang, Shoucheng

    2006-05-02

    A device and a method for generating an electric-field-induced spin current are disclosed. A highly spin-polarized electric current is generated using a semiconductor structure and an applied electric field across the semiconductor structure. The semiconductor structure can be a hole-doped semiconductor having finite or zero bandgap or an undoped semiconductor of zero bandgap. In one embodiment, a device for injecting spin-polarized current into a current output terminal includes a semiconductor structure including first and second electrodes, along a first axis, receiving an applied electric field and a third electrode, along a direction perpendicular to the first axis, providing the spin-polarized current. The semiconductor structure includes a semiconductor material whose spin orbit coupling energy is greater than room temperature (300 Kelvin) times the Boltzmann constant. In one embodiment, the semiconductor structure is a hole-doped semiconductor structure, such as a p-type GaAs semiconductor layer.

  12. Stability of Spherical Vesicles in Electric Fields

    PubMed Central

    2010-01-01

    The stability of spherical vesicles in alternating (ac) electric fields is studied theoretically for asymmetric conductivity conditions across their membranes. The vesicle deformation is obtained from a balance between the curvature elastic energies and the work done by the Maxwell stresses. The present theory describes and clarifies the mechanisms for the four types of morphological transitions observed experimentally on vesicles exposed to ac fields in the frequency range from 500 to 2 × 107 Hz. The displacement currents across the membranes redirect the electric fields toward the membrane normal to accumulate electric charges by the Maxwell−Wagner mechanism. These accumulated electric charges provide the underlying molecular mechanism for the morphological transitions of vesicles as observed on the micrometer scale. PMID:20575588

  13. Evolution of tachyon kink with electric field

    NASA Astrophysics Data System (ADS)

    Cho, Inyong; Kwon, O.-Kab; Lee, Chong Oh

    2007-04-01

    We investigate the decay of an inhomogeneous D1-brane wrapped on a S1 with an electric field. The model that we consider consists of an array of tachyon kink and anti-kink with a constant electric flux. Beginning with an initially static configuration, we numerically evolve the tachyon field with some perturbations under a fixed boundary condition at diametrically opposite points on the circle S1. When the electric flux is smaller than the critical value, the tachyon kink becomes unstable; the tachyon field rolls down the potential, and the lower dimensional D0- and bar D0-brane become thin, which resembles the caustic formation known for this type of the system in the literature. For the supercritical values of the electric flux, the tachyon kink remains stable.

  14. Rotationally Vibrating Electric-Field Mill

    NASA Technical Reports Server (NTRS)

    Kirkham, Harold

    2008-01-01

    A proposed instrument for measuring a static electric field would be based partly on a conventional rotating-split-cylinder or rotating-split-sphere electric-field mill. However, the design of the proposed instrument would overcome the difficulty, encountered in conventional rotational field mills, of transferring measurement signals and power via either electrical or fiber-optic rotary couplings that must be aligned and installed in conjunction with rotary bearings. Instead of being made to rotate in one direction at a steady speed as in a conventional rotational field mill, a split-cylinder or split-sphere electrode assembly in the proposed instrument would be set into rotational vibration like that of a metronome. The rotational vibration, synchronized with appropriate rapid electronic switching of electrical connections between electric-current-measuring circuitry and the split-cylinder or split-sphere electrodes, would result in an electrical measurement effect equivalent to that of a conventional rotational field mill. A version of the proposed instrument is described.

  15. Electrically polarized micro-arc oxidized TiO2 coatings with enhanced surface hydrophilicity.

    PubMed

    Ma, Chufan; Nagai, Akiko; Yamazaki, Yuko; Toyama, Takeshi; Tsutsumi, Yusuke; Hanawa, Takao; Wang, Wei; Yamashita, Kimihiro

    2012-02-01

    The use of micro-arc oxidation titania (MAO TiO2) coatings to modify titanium surfaces improves the biocompatibility of implant surfaces. To obtain hydrophilic MAO TiO2 coating surfaces electric polarization, which induces surface electric fields in the materials and produces surface charges, was performed in this study. Electric polarization of the MAO TiO2 coatings was confirmed by measuring the thermally stimulated depolarization current. After electric polarization treatment the MAO TiO2 coatings did not exhibit any obvious changes in surface roughness, morphology, or phase components. X-ray photoelectron spectroscopy results indicated that electric polarization resulted in oxidation of the cathodic-faced surfaces and reduction of the anodic-faced surfaces. This result suggests that the existence of a concentration gradient of oxide ions/oxygen vacancies produced the stored space charge in the coatings. Reduction of the deionized water contact angle on the polarized MAO TiO2 surfaces was maintained for longer periods compared with the non-polarized surface. Our study demonstrated that metastable electric fields across the MAO TiO2 coating produced by electric polarization made it durably wettable by reducing the interfacial surface tension between the material and water.

  16. Magnetospheric electric field measurements during sudden commencements

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Skillman, T. L.

    1973-01-01

    Direction measurements of electric fields were made in the outer magnetosphere during two sudden commencements in 1972. These measurements were observed with the double floating probe experiment carried aboard the IMP 6 satellite. The initial variations of the measured electric field consisted of an increase from a background of about 1 mv/meter to some 10 mv/meter at about 7 rE (earth radi) and to some 4 mv/meter at 3 rE. These initial electric field disturbances were longitudinal, oriented counter clockwise about an axis pointed north. A solution of Maxwell's third equation is derived for these measurements using a quasi-static version of Mead's model of the magnetosphere B (t). This solution seems to describe well the magnitude and direction of the initial perturbation of the electric field vectors observed during these two sudden commencements. After the initial increase, the measured electric field rings several times with periods of the order of minutes. This observed oscillatory behavior correlates with magnetic observatory records taken near the foot of the magetic field line passing through the satellite.

  17. Electric field measurements from Halley, Antarctica

    NASA Astrophysics Data System (ADS)

    Nicoll, Keri; Harrison, R. Giles

    2016-04-01

    Antarctica is a unique location for the study of atmospheric electricity. Not only is it one of the most pollutant free places on Earth, but its proximity to the south magnetic pole means that it is an ideal location to study the effects of solar variability on the atmospheric electric field. This is due to the reduced shielding effect of the geomagnetic field at the poles which leads to a greater flux of incoming Galactic Cosmic Rays (GCRs) as well as an increased probability of energetic particle precipitation from SEPs and relativistic electrons. To investigate such effects, two electric field mills of different design were installed at the British Antarctic Survey Halley base in February 2015 (75. 58 degrees south, 26.66 degrees west). Halley is situated on the Brunt Ice Shelf in the south east of the Weddell Sea and has snow cover all year round. Preliminary analysis has focused on selection of fair weather criteria using wind speed and visibility measurements which are vital to assess the effects of falling snow, blowing snow and freezing fog on the electric field measurements. When the effects of such adverse weather conditions are removed clear evidence of the characteristic Carnegie Curve diurnal cycle exists in the Halley electric field measurements (with a mean value of 50V/m and showing a 40% peak to peak variation in comparison to the 34% variation in the Carnegie data). Since the Carnegie Curve represents the variation in thunderstorm activity across the Earth, its presence in the Halley data confirms the presence of the global atmospheric electric circuit signal at Halley. The work presented here will discuss the details of the Halley electric field dataset, including the variability in the fair weather measurements, with a particular focus on magnetic field fluctuations.

  18. Magnetoexciton in nanotube under external electric field

    NASA Astrophysics Data System (ADS)

    Garcia Russi, L. F.; Paredes Gutiérrez, H.; Santos, Y. F.; Mikhailov, I. D.

    2016-08-01

    We study the Aharonov-Bohm oscillation of the energy levels of an electron-hole pair confined in a narrow nanotube in the presence of the magnetic field applied along the symmetry axis. We show that the electric field applied at the same direction makes the oscillation more pronounced.

  19. On interplanetary electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Alekseev, I. I.; Kropotkin, A. P.; Veselovskii, I. S.

    1982-08-01

    A kinematic model of the stationary electromagnetic fields in interplanetary space with finite conductivity is considered. The electrodynamic problem is solved for a medium with uniform conductivity and radial plasma outflow from a spherical source. Simple analytical formulae are obtained for electric and magnetic fields, currents and charges in the case of a uniformly-magnetized rotating sphere.

  20. Stratospheric electric field measurements with transmediterranean balloons

    NASA Astrophysics Data System (ADS)

    de La Morena, B. A.; Alberca, L. F.; Curto, J. J.; Holzworth, R. H.

    1993-01-01

    The horizontal component of the stratospheric electric field was measured using a balloon in the ODISEA Campaign of Transmediterranean Balloon Program. The balloon flew between Trapani (Sicily) and El Arenosillo (Huelva, Spain) along the 39 deg N parallel at a height between 34 and 24 km. The high values found for the field on fair-weather and its quasi-turbulent variation, both in amplitude and direction, are difficult to explain with the classical electric field source. A new source, first described by Holzworth (1989), is considered as possibly causing them.

  1. A model for polar cap electric fields

    NASA Technical Reports Server (NTRS)

    Dangelo, N.

    1976-01-01

    A model is proposed relating polar cap ionospheric electric fields to the parameters of the solar wind near the orbit of the earth. The model ignores the notion of field line merging. An essential feature is the role played by velocity shear instabilities in regions of the outer magnetosphere, in which mapping of the magnetosheath electric field would produce sunward convection. The anomalous resistivity which arises from velocity shear turbulence, suffices to essentially disconnect the magnetosphere from the magnetosheath, at any place where that resistivity is large enough. The magnetosheath-magnetosphere system, as a consequence, acts as a kind of diode or rectifier for the magnetosheath electric fields. Predictions of the model are compared with several observations related to polar cap convection.

  2. Electric fields associated with dipolarization fronts

    NASA Astrophysics Data System (ADS)

    Sun, Wei-Jie; Fu, Suiyan; Parks, George K.; Pu, Zuyin; Zong, Qiu-Gang; Liu, Jiang; Yao, Zhonghua; Fu, Huishan; Shi, Quanqi

    2014-07-01

    Electric fields associated with dipolarization fronts (DFs) have been investigated in the magnetotail plasma sheet using Cluster observations. We have studied each term in the generalized Ohm's law using data obtained from the multispacecraft Cluster. Our results show that in the plasma flow frame, electric fields are directed normal to the DF in the magnetic dip region ahead of the DF as well as in the DF layer but in opposite directions. Case and statistical studies show that the Hall electric field is important while the electron pressure gradient term is much smaller. The ions decouple from the magnetic field in the DF layer and dip region (E + Vi×B ≠ 0), whereas electrons remain frozen-in (E + Ve×B=∇pe/nee).

  3. Studying electric fields in dipolarization fronts

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2014-11-01

    In Earth's magnetotail, sharp increases in the magnetic field known as dipolarization fronts are associated with high-speed plasma flows that connect Earth's ionosphere via electric currents. Some aspects of these dipolarization fronts have puzzled scientists; in particular, the dip in magnetic field that occurs just ahead of the dipolarization front layer is not well understood. Sun et al. analyze observations made using the Cluster satellites to elucidate the details of electric fields associated with dipolarization fronts. The study shows that a type of electric current known as a Hall current dominates in the dipolarization front region and in the region where the magnetic field dips, but this current flows in opposite directions in these two regions.

  4. Electric fields, weighting fields, signals and charge diffusion in detectors including resistive materials

    NASA Astrophysics Data System (ADS)

    Riegler, W.

    2016-11-01

    In this report we discuss static and time dependent electric fields in detector geometries with an arbitrary number of parallel layers of a given permittivity and weak conductivity. We derive the Green's functions i.e. the field of a point charge, as well as the weighting fields for readout pads and readout strips in these geometries. The effect of `bulk' resistivity on electric fields and signals is investigated. The spreading of charge on thin resistive layers is also discussed in detail, and the conditions for allowing the effect to be described by the diffusion equation is discussed. We apply the results to derive fields and induced signals in Resistive Plate Chambers, MICROMEGAS detectors including resistive layers for charge spreading and discharge protection as well as detectors using resistive charge division readout like the MicroCAT detector. We also discuss in detail how resistive layers affect signal shapes and increase crosstalk between readout electrodes.

  5. Electroforming of metallic bipolar plates with micro-featured flow field

    NASA Astrophysics Data System (ADS)

    Lee, Shuo-Jen; Chen, Yu-Pang; Huang, Ching-Han

    In addition to mechanical properties, uniform fuel dispersion, efficient removal of water and high electric conductivity are also important functions of a bipolar plate. The capillary effect of micro-featured flow field may attract water from the carbonic diffusion layer and promote more evenly dispersion of fuels into the diffusion layer. Thus, it may improve the performance of proton exchange membrane (PEM) fuel cells. In this research, the Lithography Galvanik Abformung (LIGA) manufacturing processes with electroforming technology are investigated for the production of micro-featured flow field of the metallic bipolar plates. The micro-features are designed in conjunction with the existing flow channel to form an integrated flow field system. Instead of silicon wafer, a 4 in. wafer size SS304 stainless steel plate is used as the substrate. The LIGA processes of photo masking, spin coating, exposure and development are employed to create electric conducting die with flow field pattern. Electroforming of this metallic plate coated with flow field patterned photo resist will result in the main flow channel on the SS304 plate. The same processes were conducted for the second iteration to form micro-features. Thus, metallic bipolar plates with micro-features are produced using the electroforming technology. A single cell with total cell area of 16 cm 2 and reaction area of 4 cm 2 was produced. It has micro-features of 100 and 200 μm width and of 50 μm depth. The dimensions of the main flow channel were 300 μm in width and 200 μm in depth. Single cell tests were conducted to evaluate its performance. The cell performance of the single cell with SS304 metallic bipolar plates exceeds similar size single cell with silicon or glass fiber substrates. The electroforming is a promising technology for metallic bipolar plates with micro-features and micro-fuel cell.

  6. Microwave electric field sensing with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Stack, Daniel T.; Kunz, Paul D.; Meyer, David H.; Solmeyer, Neal

    2016-05-01

    Atoms form the basis of precise measurement for many quantities (time, acceleration, rotation, magnetic field, etc.). Measurements of microwave frequency electric fields by traditional methods (i.e. engineered antennas) have limited sensitivity and can be difficult to calibrate properly. Highly-excited (Rydberg) neutral atoms have very large electric-dipole moments and many dipole allowed transitions in the range of 1 - 500 GHz. It is possible to sensitively probe the electric field in this range using the combination of two quantum interference phenomena: electromagnetically induced transparency and the Autler-Townes effect. This technique allows for very sensitive field amplitude, polarization, and sub-wavelength imaging measurements. These quantities can be extracted by measuring properties of a probe laser beam as it passes through a warm rubidium vapor cell. Thus far, Rydberg microwave electrometry has relied upon the absorption of the probe laser. We report on our use of polarization rotation, which corresponds to the real part of the susceptibility, for measuring the properties of microwave frequency electric fields. Our simulations show that when a magnetic field is present and directed along the optical propagation direction a polarization rotation signal exists and can be used for microwave electrometry. One central advantage in using the polarization rotation signal rather than the absorption signal is that common mode laser noise is naturally eliminated leading to a potentially dramatic increase in signal-to-noise ratio.

  7. Electric-field-stimulated protein mechanics.

    PubMed

    Hekstra, Doeke R; White, K Ian; Socolich, Michael A; Henning, Robert W; Šrajer, Vukica; Ranganathan, Rama

    2016-12-15

    The internal mechanics of proteins-the coordinated motions of amino acids and the pattern of forces constraining these motions-connects protein structure to function. Here we describe a new method combining the application of strong electric field pulses to protein crystals with time-resolved X-ray crystallography to observe conformational changes in spatial and temporal detail. Using a human PDZ domain (LNX2(PDZ2)) as a model system, we show that protein crystals tolerate electric field pulses strong enough to drive concerted motions on the sub-microsecond timescale. The induced motions are subtle, involve diverse physical mechanisms, and occur throughout the protein structure. The global pattern of electric-field-induced motions is consistent with both local and allosteric conformational changes naturally induced by ligand binding, including at conserved functional sites in the PDZ domain family. This work lays the foundation for comprehensive experimental study of the mechanical basis of protein function.

  8. Quasi-Static Electric Field Generator

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R. (Inventor)

    2017-01-01

    A generator for producing an electric field for with an inspection technology system is provided. The generator provides the required variable magnitude quasi-static electric fields for the "illumination" of objects, areas and volumes to be inspected by the system, and produces human-safe electric fields that are only visible to the system. The generator includes a casing, a driven, non-conducting and triboelectrically neutral rotation shaft mounted therein, an ungrounded electrostatic dipole element which works in the quasi-static range, and a non-conducting support for mounting the dipole element to the shaft. The dipole element has a wireless motor system and a charging system which are wholly contained within the dipole element and the support that uses an electrostatic approach to charge the dipole element.

  9. Electric field induced deformation of sessile drops

    NASA Astrophysics Data System (ADS)

    Corson, Lindsey; Tsakonas, Costas; Duffy, Brian; Mottram, Nigel; Brown, Carl; Wilson, Stephen

    2014-11-01

    The ability to control the shape of a drop with the application of an electric field has been exploited for many technological applications including measuring surface tension, producing an optical display device, and optimising the optical properties of microlenses. In this work we consider, both theoretically and experimentally, the deformation of pinned sessile drops with contact angles close to either 0° or 90° resting on the lower substrate inside a parallel plate capacitor due to an A.C. electric field. Using both asymptotic and numerical approaches we obtain predictive equations for the static and dynamic drop shape deformations as functions of the key experimental parameters (drop size, capacitor plate separation, electric field magnitude and contact angle). The asymptotic results agree well with the experimental results for a range of liquids. We gratefully acknowledge the financial support of EPSRC via research Grants EP/J009865 and EP/J009873.

  10. Synergistic effect of electrical and chemical factors on endocytosis in micro-discharge plasma gene transfection

    NASA Astrophysics Data System (ADS)

    Jinno, M.; Ikeda, Y.; Motomura, H.; Isozaki, Y.; Kido, Y.; Satoh, S.

    2017-06-01

    We have developed a new micro-discharge plasma (MDP)-based gene transfection method, which transfers genes into cells with high efficiency and low cytotoxicity; however, the mechanism underlying the method is still unknown. Studies revealed that the N-acetylcysteine-mediated inhibition of reactive oxygen species (ROS) activity completely abolished gene transfer. In this study, we used laser-produced plasma to demonstrate that gene transfer does not occur in the absence of electrical factors. Our results show that both electrical and chemical factors are necessary for gene transfer inside cells by microplasma irradiation. This indicates that plasma-mediated gene transfection utilizes the synergy between electrical and chemical factors. The electric field threshold required for transfection was approximately 1 kV m-1 in our MDP system. This indicates that MDP irradiation supplies sufficient concentrations of ROS, and the stimulation intensity of the electric field determines the transfection efficiency in our system. Gene transfer by plasma irradiation depends mainly on endocytosis, which accounts for at least 80% of the transfer, and clathrin-mediated endocytosis is a dominant endocytosis. In plasma-mediated gene transfection, alterations in electrical and chemical factors can independently regulate plasmid DNA adhesion and triggering of endocytosis, respectively. This implies that plasma characteristics can be adjusted according to target cell requirements, and the transfection process can be optimized with minimum damage to cells and maximum efficiency. This may explain how MDP simultaneously achieves high transfection efficiency with minimal cell damage.

  11. Microfluidic Screening of Electric Fields for Electroporation

    NASA Astrophysics Data System (ADS)

    Garcia, Paulo A.; Ge, Zhifei; Moran, Jeffrey L.; Buie, Cullen R.

    2016-02-01

    Electroporation is commonly used to deliver molecules such as drugs, proteins, and/or DNA into cells, but the mechanism remains poorly understood. In this work a rapid microfluidic assay was developed to determine the critical electric field threshold required for inducing bacterial electroporation. The microfluidic device was designed to have a bilaterally converging channel to amplify the electric field to magnitudes sufficient to induce electroporation. The bacterial cells are introduced into the channel in the presence of SYTOX®, which fluorescently labels cells with compromised membranes. Upon delivery of an electric pulse, the cells fluoresce due to transmembrane influx of SYTOX® after disruption of the cell membranes. We calculate the critical electric field by capturing the location within the channel of the increase in fluorescence intensity after electroporation. Bacterial strains with industrial and therapeutic relevance such as Escherichia coli BL21 (3.65 ± 0.09 kV/cm), Corynebacterium glutamicum (5.20 ± 0.20 kV/cm), and Mycobacterium smegmatis (5.56 ± 0.08 kV/cm) have been successfully characterized. Determining the critical electric field for electroporation facilitates the development of electroporation protocols that minimize Joule heating and maximize cell viability. This assay will ultimately enable the genetic transformation of bacteria and archaea considered intractable and difficult-to-transfect, while facilitating fundamental genetic studies on numerous diverse microbes.

  12. Microfluidic Screening of Electric Fields for Electroporation

    PubMed Central

    Garcia, Paulo A.; Ge, Zhifei; Moran, Jeffrey L.; Buie, Cullen R.

    2016-01-01

    Electroporation is commonly used to deliver molecules such as drugs, proteins, and/or DNA into cells, but the mechanism remains poorly understood. In this work a rapid microfluidic assay was developed to determine the critical electric field threshold required for inducing bacterial electroporation. The microfluidic device was designed to have a bilaterally converging channel to amplify the electric field to magnitudes sufficient to induce electroporation. The bacterial cells are introduced into the channel in the presence of SYTOX®, which fluorescently labels cells with compromised membranes. Upon delivery of an electric pulse, the cells fluoresce due to transmembrane influx of SYTOX® after disruption of the cell membranes. We calculate the critical electric field by capturing the location within the channel of the increase in fluorescence intensity after electroporation. Bacterial strains with industrial and therapeutic relevance such as Escherichia coli BL21 (3.65 ± 0.09 kV/cm), Corynebacterium glutamicum (5.20 ± 0.20 kV/cm), and Mycobacterium smegmatis (5.56 ± 0.08 kV/cm) have been successfully characterized. Determining the critical electric field for electroporation facilitates the development of electroporation protocols that minimize Joule heating and maximize cell viability. This assay will ultimately enable the genetic transformation of bacteria and archaea considered intractable and difficult-to-transfect, while facilitating fundamental genetic studies on numerous diverse microbes. PMID:26893024

  13. Microfluidic Screening of Electric Fields for Electroporation.

    PubMed

    Garcia, Paulo A; Ge, Zhifei; Moran, Jeffrey L; Buie, Cullen R

    2016-02-19

    Electroporation is commonly used to deliver molecules such as drugs, proteins, and/or DNA into cells, but the mechanism remains poorly understood. In this work a rapid microfluidic assay was developed to determine the critical electric field threshold required for inducing bacterial electroporation. The microfluidic device was designed to have a bilaterally converging channel to amplify the electric field to magnitudes sufficient to induce electroporation. The bacterial cells are introduced into the channel in the presence of SYTOX(®), which fluorescently labels cells with compromised membranes. Upon delivery of an electric pulse, the cells fluoresce due to transmembrane influx of SYTOX(®) after disruption of the cell membranes. We calculate the critical electric field by capturing the location within the channel of the increase in fluorescence intensity after electroporation. Bacterial strains with industrial and therapeutic relevance such as Escherichia coli BL21 (3.65 ± 0.09 kV/cm), Corynebacterium glutamicum (5.20 ± 0.20 kV/cm), and Mycobacterium smegmatis (5.56 ± 0.08 kV/cm) have been successfully characterized. Determining the critical electric field for electroporation facilitates the development of electroporation protocols that minimize Joule heating and maximize cell viability. This assay will ultimately enable the genetic transformation of bacteria and archaea considered intractable and difficult-to-transfect, while facilitating fundamental genetic studies on numerous diverse microbes.

  14. Velocity modulation of microtubules in electric fields.

    PubMed

    Dujovne, Irene; van den Heuvel, Martin; Shen, Yi; de Graaff, Martijn; Dekker, Cees

    2008-12-01

    We show that the speed of microtubules gliding over a kinesin-coated surface can be controlled over a wide range of values by the application of an electric field. The speed can be increased by up to a factor of 5 compared to the speed at zero field when assisting forces are applied and slowed down to zero velocity for opposing fields. Sideways applied fields also induce significant motion. The kinesin surface density impacts the rate of velocity change, whereas the ATP concentration does not seem to play a major role, provided that it is nonzero. A simple grab-and-release model is presented that explains the velocity change with applied electric fields.

  15. Particles Sorting in Micro Channel Using Designed Micro Electromagnets of Magnetic Field Gradient

    NASA Astrophysics Data System (ADS)

    Chung, Yung-Chiang; Wu, Chen-Ming; Lin, Shih-Hao

    2016-06-01

    In this study, microelectromagnet, microchannel, syringe pump, and controlling devices were integrated to form a particle sorting system. A simple, two-dimensional, relatively quick fabricating and easily operating microelectromagnet was designed. Polystyrene particles and magnetic beads were pumped into the microchannel with the syringe pump, and it was observed that the magnetic beads were attracted to one of two outlets by the microelectromagnet, which features a gradually changing magnetic field. The polystyrene particles would move to another outlet because of different-width micro channel, and it completed the separation of the particles. Based on experimental results, the magnetic flux density of the microelectromagnet was 2.3 Gauss for a 12.5-μm average distance between electrodes at 1.0-μm increments, and the magnetic force was 0.22 pN for 2.8-μm magnetic beads. The separating rate was greater for larger distance increment and smaller average distance between the electrodes. The separating rate of the magnetic beads increased as the electric current increased and flow velocity decreased. When the flow velocity was 0.333 μm/s and electric current was 1 A, the separating rate was 90%. The separating rate of the polystyrene particles increased as the flow velocity increased and was 85% when the flow velocity was 0.6 μm/s. These results demonstrate that this particle sorting system has potential applications in bio-molecular studies.

  16. Electric Field Quantitative Measurement System and Method

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R. (Inventor)

    2016-01-01

    A method and system are provided for making a quantitative measurement of an electric field. A plurality of antennas separated from one another by known distances are arrayed in a region that extends in at least one dimension. A voltage difference between at least one selected pair of antennas is measured. Each voltage difference is divided by the known distance associated with the selected pair of antennas corresponding thereto to generate a resulting quantity. The plurality of resulting quantities defined over the region quantitatively describe an electric field therein.

  17. Drug Release from Electric Field Responsive Nanoparticles

    PubMed Central

    Ge, Jun; Neofytou, Evgenios; Cahill, Thomas J.; Beygui, Ramin E.; Zare, Richard N.

    2012-01-01

    We describe a new temperature and electric field dual-stimulus responsive nanoparticle system for programmed drug delivery. Nanoparticles of a conducting polymer (polypyrrole) are loaded with therapeutic pharmaceuticals and are subcutaneously localized in vivo with the assistance of a temperature-sensitive hydrogel (PLGA-PEG-PLGA). We have shown that drug release from the conductive nanoparticles is controlled by the application of a weak, external DC electric field. This approach represents a novel interactive drug delivery system that can show an externally tailored release profile with an excellent spatial, temporal, and dosage control. PMID:22111891

  18. Dipolar resonances in conductive carbon micro-fibers probed by near-field terahertz spectroscopy

    SciTech Connect

    Khromova, I.; Navarro-Cia, M.; Brener, I.; Reno, J. L.; Ponomarev, A.; Mitrofanov, O.

    2015-07-13

    In this study, we observe dipole resonances in thin conductive carbon micro-fibers by detecting an enhanced electric field in the near-field of a single fiber at terahertz (THz) frequencies. Time-domain analysis of the electric field shows that each fiber sustains resonant current oscillations at the frequency defined by the fiber's length. Strong dependence of the observed resonance frequency and degree of field enhancement on the fibers' conductive properties enable direct non-contact probing of the THz conductivity in single carbon micro-fibers. We find the conductivity of the fibers to be within the range of 1– 5∙104 S/m. This approach is suitable for experimental characterization of individual doped semiconductor resonators for THz metamaterials and devices.

  19. Dipolar resonances in conductive carbon micro-fibers probed by near-field terahertz spectroscopy

    DOE PAGES

    Khromova, I.; Navarro-Cia, M.; Brener, I.; ...

    2015-07-13

    In this study, we observe dipole resonances in thin conductive carbon micro-fibers by detecting an enhanced electric field in the near-field of a single fiber at terahertz (THz) frequencies. Time-domain analysis of the electric field shows that each fiber sustains resonant current oscillations at the frequency defined by the fiber's length. Strong dependence of the observed resonance frequency and degree of field enhancement on the fibers' conductive properties enable direct non-contact probing of the THz conductivity in single carbon micro-fibers. We find the conductivity of the fibers to be within the range of 1– 5∙104 S/m. This approach is suitablemore » for experimental characterization of individual doped semiconductor resonators for THz metamaterials and devices.« less

  20. Electric Field Effects in RUS Measurements

    SciTech Connect

    Darling, Timothy W; Ten Cate, James A; Allured, Bradley; Carpenter, Michael A

    2009-09-21

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

  1. Electric field effects in RUS measurements.

    PubMed

    Darling, Timothy W; Allured, Bradley; Tencate, James A; Carpenter, Michael A

    2010-02-01

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material--a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the "statistical residual" strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

  2. Electric field stimulated growth of Zn whiskers

    SciTech Connect

    Niraula, D.; McCulloch, J.; Irving, R.; Karpov, V. G.; Warrell, G. R.; Shvydka, Diana

    2016-07-15

    We have investigated the impact of strong (∼10{sup 4} V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

  3. Electric fields and double layers in plasmas

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Thiemann, H.; Schunk, R. W.

    1987-01-01

    Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamical features of the double layers are discussed. These features, as seen in simulations, laboratory experiments, and theory, indicate that double layers and the currents through them undergo slow oscillations which are determined by the ion transit time across an effective length of the system in which double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations were considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields and double layers in an expanding plasma is discussed.

  4. Electric field stimulated growth of Zn whiskers

    NASA Astrophysics Data System (ADS)

    Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana

    2016-07-01

    We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

  5. Electric fields and double layers in plasmas

    NASA Astrophysics Data System (ADS)

    Singh, Nagendra; Thiemann, H.; Schunk, R. W.

    1987-05-01

    Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamical features of the double layers are discussed. These features, as seen in simulations, laboratory experiments, and theory, indicate that double layers and the currents through them undergo slow oscillations which are determined by the ion transit time across an effective length of the system in which double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations were considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields and double layers in an expanding plasma is discussed.

  6. Airborne biological particles and electric fields

    NASA Astrophysics Data System (ADS)

    Benninghoff, William S.; Benninghoff, Anne S.

    1982-01-01

    In November and December 1977 at McMurdo Station in Antarctica we investigated the kinds, numbers, and deposition of airborne particles larger than 2 μm while measuring electric field gradient at 2.5 m above the ground. Elementary collecting devices were used: Staplex Hi-Volume and Roto-rod samplers, Tauber (static sedimentation) traps, petrolatum-coated microscope slides, and snow (melted and filtered). The electric fields were measured by a rotating dipole (Stanford Radioscience Laboratory field mill number 2). During periods of blowing snow and dust the electric field gradient was + 500 to + 2500 V/m, and Tauber traps with grounded covers collected 2 or more times as much snow and dust as the ones with ungrounded covers. During falling snow the electric field gradient was -1000 to -1500 V/m, and the ungrounded traps collected almost twice as much snow and dust as those grounded. These observations suggest that under the prevailing weather conditions in polar regions the probable net effect is deposition of greater quantities of dust, including diaspores and minute organisms, on wet, grounded surfaces. This hypothesis needs examination for its use in explanation of biological distribution patterns.

  7. Electric fields yield chaos in microflows

    PubMed Central

    Posner, Jonathan D.; Pérez, Carlos L.; Santiago, Juan G.

    2012-01-01

    We present an investigation of chaotic dynamics of a low Reynolds number electrokinetic flow. Electrokinetic flows arise due to couplings of electric fields and electric double layers. In these flows, applied (steady) electric fields can couple with ionic conductivity gradients outside electric double layers to produce flow instabilities. The threshold of these instabilities is controlled by an electric Rayleigh number, Rae. As Rae increases monotonically, we show here flow dynamics can transition from steady state to a time-dependent periodic state and then to an aperiodic, chaotic state. Interestingly, further monotonic increase of Rae shows a transition back to a well-ordered state, followed by a second transition to a chaotic state. Temporal power spectra and time-delay phase maps of low dimensional attractors graphically depict the sequence between periodic and chaotic states. To our knowledge, this is a unique report of a low Reynolds number flow with such a sequence of periodic-to-aperiodic transitions. Also unique is a report of strange attractors triggered and sustained through electric fluid body forces. PMID:22908251

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

    PubMed

    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.

  9. Electric and magnetic fields in cryopreservation.

    PubMed

    Wowk, Brian

    2012-06-01

    Electromagnetic warming has a long history in cryobiology as a preferred method for recovering large tissue masses from cryopreservation, especially from cryopreservation by vitrification. It is less well-known that electromagnetic fields may be able to influence ice formation during cryopreservation by non-thermal mechanisms. Both theory and published data suggest that static and oscillating electric fields can respectively promote or inhibit ice formation under certain conditions. Evidence is less persuasive for magnetic fields. Recent claims that static magnetic fields smaller than 1 mT can improve cryopreservation by freezing are specifically questioned.

  10. Field-aligned currents and large scale magnetospheric electric fields

    NASA Technical Reports Server (NTRS)

    Dangelo, N.

    1980-01-01

    D'Angelo's model of polar cap electric fields (1977) was used to visualize how high-latitude field-aligned currents are driven by the solar wind generator. The region 1 and region 2 currents of Iijima and Potemra (1976) and the cusp field-aligned currents of Wilhjelm et al. (1978) and McDiarmid et al. (1978) are apparently driven by different generators, although in both cases the solar wind is their ultimate source.

  11. Photoionization of atomic hydrogen in electric field

    SciTech Connect

    Gorlov, Timofey V; Danilov, Viatcheslav V

    2010-01-01

    Laser assisted ionization of high energy hydrogen beams in magnetic fields opens wide application possibilities in accelerator physics and other fields. The key theoretical problem of the method is the calculation of the ionization probability of a hydrogen atom affected by laser and static electric fields in the particle rest frame. A method of solving this problem with the temporal Schr dinger equation including a continuum spectrum is presented in this paper in accurate form for the first time. This method allows finding the temporal evolution of the wave function of the hydrogen atom as a function of laser and static electric fields. Solving the problem of photoionization reveals quantum effects that cannot be described by the cross sectional approach. The effects play a key role in the problems of photoionization of H0 beams with the large angular or energy spread.

  12. Electric current quadratic in an applied electric field

    NASA Astrophysics Data System (ADS)

    Deyo, Eric

    The theory of the photogalvanic effect in a low frequency electric field is developed. We complete the semiclassical theory of the effect in bulk samples lacking inversion symmetry, taking into account contributions from the asymmetry of scattering, the shift current, and the effect of Berry's phase. We consider the effect in such samples both in the presence and absence of a constant magnetic field. It is found that by experimentally measuring this effect, that Berry's curvature and the average shift of the center of mass of an electron during a scattering event can be extracted. We also investigate the magnetic field dependence of the part of the electrical current which is quadratic in voltage in mesoscopic conductors. We find that the part of the current which is quadratic in bias voltage, and linear in an applied magnetic field can be related to the effective electron-electron interaction strength. We also find that in the case when the magnetic field is oriented parallel to the plane of a two dimensional sample, that the spin-orbit scattering rate can be measured.

  13. Full Electric Field Control of Exchange Bias

    NASA Astrophysics Data System (ADS)

    Wu, Stephen

    2014-03-01

    Exchange bias is the shift of a magnetic hysteresis curve due to interfacial magnetic coupling between a ferromagnet (FM) and an antiferromagnet (AFM). This ubiquitous effect has long been used in the electronics industry to bias the magnetization of FM layers in magnetic devices. Its continued understanding is of critical importance to advance the development of future high-density magnetic storage media and other novel magnetic devices. However, due to the technological limitations of manipulating and observing an atomically thin interface, exchange bias is not well understood. In this talk we present a multiferroic field effect device with BiFeO3 (BFO) (antiferromagnetic-ferroelectric) as the gate dielectric and La0.7Sr0.3MnO3 (LSMO) (ferromagnetic) as the conducting channel, which exhibits the direct, bipolar electric control of exchange bias. Here the magnetic states at the AFM/FM interface can be directly manipulated with electric fields and the results can be observed as a change in exchange bias polarity and magnitude. Control of exchange bias at this level has significant implications because it represents a form of electric field control of magnetism and may potentially offer a route toward the eventual full electric field control of magnetization. In this device, exchange bias is reversibly switched between two stable states with opposite exchange bias polarities upon ferroelectric poling of the BFO. No field cooling, temperature cycling, or additional applied magnetic or electric field beyond BFO poling is needed for this bipolar modulation effect. Detailed temperature dependent measurements and a model will be presented which will attribute this effect to the coupled antiferromagnetic-ferroelectric order in BFO along with the modulation of interfacial exchange interactions due to ionic displacement of Fe3+ in BFO relative to Mn3 + / 4 + in LSMO.

  14. Longitudinal ultrasonic waves in DC electric field

    NASA Astrophysics Data System (ADS)

    Sobotka, Jerzy

    2009-06-01

    The results of experimental studies of the propagation of longitudinal waves in saturated rock samples in which there is a flow of electric charges are presented. It is shown that the electric field affects elastic parameters in heterophase media by changing their dynamic characteristics. The aim of the study of the effect of electric field on the propagation of elastic waves in saturated porous media was to determine the optimum conditions for this effect, and to construct a set of effective parameters which could be used to increase the effectiveness of seismoacoustic prospecting methods, particularly acoustic logging, and be helpful for developing new methods of increasing the effectiveness of oil extraction from productive wells.

  15. Health of workers exposed to electric fields.

    PubMed Central

    Broadbent, D E; Broadbent, M H; Male, J C; Jones, M R

    1985-01-01

    The results of health questionnaire interviews with 390 electrical power transmission and distribution workers, together with long term estimates of their exposure to 50 Hz electric fields, and short term measurements of the actual exposure for 287 of them are reported. Twenty eight workers received measurable exposures, averaging about 30 kVm-1h over the two week measurement period. Estimated exposure rates were considerably greater, but showed fair correlation with the measurements. Although the general level of health was higher than we have found in manual workers in other industries, there were significant differences in the health measures between different categories of job, different parts of the country, and in association with factors such as overtime, working alone, or frequently changing shift. After allowing for the effects of job and location, however, we found no significant correlations of health with either measured or estimated exposure to electric fields. PMID:3970875

  16. Electronic interface design for an electrically floating micro-disc

    NASA Astrophysics Data System (ADS)

    Gindila, M. V.; Kraft, M.

    2003-07-01

    The design of an electronic interface for an electrically floating micro-disc is presented. The system, based on a second order electromechanical Delta-Sigma modulator, can be used as a multi-axis capacitive accelerometer with the proof mass levitated by electrostatic forces. A synchronous detection scheme, used to sense the position of the proof mass, has been designed, simulated in PSpiceTM and successfully implemented on a PCB. The interface contains a differential pick-off with no ohmic connection to the proof mass, which distinguishes the circuit from typical sensing circuits for MEMS capacitive accelerometers. A noise analysis of the pick-off circuit was performed, and an electronic equivalent model of the sensing circuit has been developed and used to analyse the linearity of its transfer function. The linearity of the sensing circuit was confirmed experimentally using the PCB implementation.

  17. Non-intrusive electric field sensing

    NASA Astrophysics Data System (ADS)

    Schultz, S. M.; Selfridge, R.; Chadderdon, S.; Perry, D.; Stan, N.

    2014-04-01

    This paper presents an overview of non-intrusive electric field sensing. The non-intrusive nature is attained by creating a sensor that is entirely dielectric, has a small cross-sectional area, and has the interrogation electronics a long distance away from the system under test. One non-intrusive electric field sensing technology is the slab coupled optical fiber sensor (SCOS). The SCOS consists of an electro-optic crystal attached to the surface of a D-shaped optical fiber. It is entirely dielectric and has a cross-sectional area down to 0.3mm by 0.3mm. The SCOS device functions as an electric field sensor through use of resonant mode coupling between the crystal waveguide and the core of a D-shaped optical fiber. The resonant mode coupling of a SCOS device occurs at specific wavelengths whose spectral locations are determined in part by the effective refractive index of the modes in the slab. An electric field changes the refractive index of the slab causing a shift in the spectral position of the resonant modes. This paper describes an overview of the SCOS technology including the theory, fabrication, and operation. The effect of crystal orientation and crystal type are explained with respect to directional sensitivity and frequency response.

  18. Nonthermal processing by radio frequency electric fields

    USDA-ARS?s Scientific Manuscript database

    Radio frequency electric fields (RFEF) processing is relatively new and has been shown to inactivate bacteria in apple juice, orange juice and apple cider at moderately low temperatures. Key equipment components of the process include a radio frequency power supply and a treatment chamber that is ca...

  19. Static electric fields modify the locomotory behaviour of cockroaches.

    PubMed

    Jackson, Christopher W; Hunt, Edmund; Sharkh, Suleiman; Newland, Philip L

    2011-06-15

    Static electric fields are found throughout the environment and there is growing interest in how electric fields influence insect behaviour. Here we have analysed the locomotory behaviour of cockroaches (Periplaneta americana) in response to static electric fields at levels equal to and above those found in the natural environment. Walking behaviour (including velocity, distance moved, turn angle and time spent walking) were analysed as cockroaches approached an electric field boundary in an open arena, and also when continuously exposed to an electric field. On approaching an electric field boundary, the greater the electric field strength the more likely a cockroach would be to turn away from, or be repulsed by, the electric field. Cockroaches completely exposed to electric fields showed significant changes in locomotion by covering less distance, walking slowly and turning more often. This study highlights the importance of electric fields on the normal locomotory behaviour of insects.

  20. Vacuum interface flashover with bipolar electric fields

    SciTech Connect

    Tucker, W.K.; Anderson, R.A.; Hasti, D.E.; Jones, E.E.; Bennett, L.F.

    1985-05-01

    High energy, compact, particle accelerators require accelerating cavities that have large gradients and operate with high efficiency. The bipolar electric fields required in these efficient accelerating cavities place severe requirements on the vacuum interface. Experimentally, we have found that the bipolar flashover field varies as t/sup -1/2/ for times out to 300 ns and then remains essentially constant at 33 kV/cm for longer duration waveforms, whereas materials subjected to unipolar electric fields follow a t/sup -1/6/ relationship. Furthermore, specific accelerating cavities offer enhancements that may be employed to achieve highly uniform electric fields across the vacuum interface. Using these results and the results of a previously developed theory of unipolar flashover, a new interface has been designed and 50 kV/cm bipolar flashover field achieved for a waveform train that lasted 1 ..mu..s. This paper will discuss the design of this vacuum interface and the evaluation of various materials that led to achieving bipolar flashover fields 50% greater than we had previously obtained for long duration waveforms. 10 refs., 6 figs.

  1. Silicon Photomultiplier Performance in High ELectric Field

    NASA Astrophysics Data System (ADS)

    Montoya, J.; Morad, J.

    2016-12-01

    Roughly 27% of the universe is thought to be composed of dark matter. The Large Underground Xenon (LUX) relies on the emission of light from xenon atoms after a collision with a dark matter particle. After a particle interaction in the detector, two things can happen: the xenon will emit light and charge. The charge (electrons), in the liquid xenon needs to be pulled into the gas section so that it can interact with gas and emit light. This allows LUX to convert a single electron into many photons. This is done by applying a high voltage across the liquid and gas regions, effectively ripping electrons out of the liquid xenon and into the gas. The current device used to detect photons is the photomultiplier tube (PMT). These devices are large and costly. In recent years, a new technology that is capable of detecting single photons has emerged, the silicon photomultiplier (SiPM). These devices are cheaper and smaller than PMTs. Their performance in a high electric fields, such as those found in LUX, are unknown. It is possible that a large electric field could introduce noise on the SiPM signal, drowning the single photon detection capability. My hypothesis is that SiPMs will not observe a significant increase is noise at an electric field of roughly 10kV/cm (an electric field within the range used in detectors like LUX). I plan to test this hypothesis by first rotating the SiPMs with no applied electric field between two metal plates roughly 2 cm apart, providing a control data set. Then using the same angles test the dark counts with the constant electric field applied. Possibly the most important aspect of LUX, is the photon detector because it's what detects the signals. Dark matter is detected in the experiment by looking at the ratio of photons to electrons emitted for a given interaction in the detector. Interactions with a low electron to photon ratio are more like to be dark matter events than those with a high electron to photon ratio. The ability to

  2. Magnetic field characteristics of electric bed-heating devices

    SciTech Connect

    Wilson, B.W.; Davis, K.C.; Heimbigner, T.; Buschbom, R.L.; Lee, G.M.; Yost, M.G.

    1996-12-01

    Measurements of the flux density and spectra of magnetic fields (MFs) generated by several types of electric bed heaters (EBH) were made in order to characterize the MFs to which the fetus may be exposed in utero from the mother`s use of these devices. Data on MFs were gathered from more than 1,300 in-home and laboratory spot measurements. In-home measurements taken at seven different positions 10 cm from the EBHs determined that the mean flux density at the estimated position of the fetus relative to the device was 0.45 {micro}T (4.5 mG) for electric blankets and 0.20 {micro}T (2.0 mG) for electrically heated water beds. A rate-of-change (RC) metric applied to the nighttime segment of 24 h EMDEX-C personal-dosimeter measurements, which were taken next to the bed of volunteers, yielded an approximate fourfold to sixfold higher value for electric blanket users compared to water-bed heater users. These same data records yielded an approximate twofold difference for the same measurements when evaluated by the time-weighted-average (TWA) MF exposure metric. Performance of exposure meters was checked against standard fields generated in the laboratory, and studies of sources of variance in the in-home measurement protocols were carried out. Spectral measurements showed that the EBHs measured produced no appreciable high-frequency MFs. Data gathered during this work will be used in interpreting results from a component of the California Pregnancy Outcome Study, which evaluates the use of EBHs as a possible risk factor in miscarriage.

  3. Composite lateral electric field excited piezoelectric resonator.

    PubMed

    Zaitsev, B D; Shikhabudinov, A M; Borodina, I A; Teplykh, A A; Kuznetsova, I E

    2017-01-01

    The novel method of suppression of parasitic oscillations in lateral electric field excited piezoelectric resonator is suggested. Traditionally such resonator represents the piezoelectric plate with two electrodes on one side of the plate. The crystallographic orientation of the plate is selected so that the tangential components of electric field excite bulk acoustic wave with given polarization travelling along the normal to the plate sides. However at that the normal components of field excite the parasitic Lamb waves and bulk waves of other polarization which deteriorate the resonant properties of the resonator. In this work we suggest to separate the source of the HF electric field and resounded piezoelectric plate by air gap. In this case the tangential components of the field in piezoelectric plate do not practically weaken but normal components significantly decrease. This method is realized on the composite resonator having the structure "glass plate with rectangular electrodes - air gap - plate of 128 Y-X lithium niobate." It has been shown that there exist the optimal value of the width gap which ensure the good quality of series and parallel resonances in frequency range 3-4MHz with record values of Q-factor of ∼15,000 in both cases.

  4. Tikekar superdense stars in electric fields

    NASA Astrophysics Data System (ADS)

    Komathiraj, K.; Maharaj, S. D.

    2007-04-01

    We present exact solutions to the Einstein-Maxwell system of equations with a specified form of the electric field intensity by assuming that the hypersurface {t=constant} are spheroidal. The solution of the Einstein-Maxwell system is reduced to a recurrence relation with variable rational coefficients which can be solved in general using mathematical induction. New classes of solutions of linearly independent functions are obtained by restricting the spheroidal parameter K and the electric field intensity parameter α. Consequently, it is possible to find exact solutions in terms of elementary functions, namely, polynomials and algebraic functions. Our result contains models found previously including the superdense Tikekar neutron star model [J. Math. Phys. 31, 2454 (1990)] when K=-7 and α=0. Our class of charged spheroidal models generalize the uncharged isotropic Maharaj and Leach solutions [J. Math. Phys. 37, 430 (1996)]. In particular, we find an explicit relationship directly relating the spheroidal parameter K to the electromagnetic field.

  5. Electric fields in Scanning Electron Microscopy simulations

    NASA Astrophysics Data System (ADS)

    Arat, K. T.; Bolten, J.; Klimpel, T.; Unal, N.

    2016-03-01

    The electric field distribution and charging effects in Scanning Electron Microscopy (SEM) were studied by extending a Monte-Carlo based SEM simulator by a fast and accurate multigrid (MG) based 3D electric field solver. The main focus is on enabling short simulation times with maintaining sufficient accuracy, so that SEM simulation can be used in practical applications. The implementation demonstrates a gain in computation speed, when compared to a Gauss-Seidel based reference solver is roughly factor of 40, with negligible differences in the result (~10-6 𝑉). In addition, the simulations were compared with experimental SEM measurements using also complex 3D sample, showing that i) the modelling of e-fields improves the simulation accuracy, and ii) multigrid method provide a significant benefit in terms of simulation time.

  6. Influence of electric field on cellular migration

    NASA Astrophysics Data System (ADS)

    Guido, Isabella; Bodenschatz, Eberhard

    Cells have the ability to detect continuous current electric fields (EFs) and respond to them with a directed migratory movement. Dictyostelium discoideum (D.d.) cells, a key model organism for the study of eukaryotic chemotaxis, orient and migrate toward the cathode under the influence of an EF. The underlying sensing mechanism and whether it is shared by the chemotactic response pathway remains unknown. Whereas genes and proteins that mediate the electric sensing as well as that define the migration direction have been previously investigated in D.d. cells, a deeper knowledge about the cellular kinematic effects caused by the EF is still lacking. Here we show that besides triggering a directional bias the electric field influences the cellular kinematics by accelerating the movement of cells along their path. We found that the migratory velocity of the cells in an EF increases linearly with the exposure time. Through the analysis of the PI3K and Phg2 distribution in the cytosol and of the cellular adherence to the substrate we aim at elucidating whereas this speed up effect in the electric field is due to either a molecular signalling or the interaction with the substrate. This work is part of the MaxSynBio Consortium which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society.

  7. The safety of a cell in a droplet under high electric field

    NASA Astrophysics Data System (ADS)

    Noh, Jihoon; Im, Do Jin; Kang, In Seok

    2010-11-01

    Electrically charged aqueous droplet can be transported by electrical field in a dielectric fluid without the flow of medium (Jung et al. J. Colloid Interface Sci. 2008). This phenomenon can be used to transport a single nanoliter droplet in a micro channel, which can serve as biochemical micro-reactor. Because an aqueous droplet is much conductive than the dielectric fluid, there is effectively no electric field inside the droplet suspended in dielectric fluid. Therefore bio-materials are protected from electricity even under high electric field. However, when the droplet is charged near an electrode by direct contact to the electrode, there is possibility that electric field can hurt bio-materials like DNA molecules, microorganisms, cells, protein in droplet. Because of this concern, we should confirm that bio-materials in droplet moving by direct charging are safe under strong external electric field especially to organism cells. Therefore we examine the effect of electric field on the cells such as yeast, E.coli., and sperm in droplet experimentally.

  8. Behavioral effects of electric and magnetic fields

    SciTech Connect

    Laties, V.G.

    1992-04-01

    Two set of behavioral studies were conducted. (1) Electric field: Three procedures were used to determine how aversive a 100 kV/m 60-Hz electric field is for the rat. Each of the procedures enabled rats to respond in order to reduce exposure to the field. The rats did reduce exposure slightly with one, but not with the other two, whereas they reduced their exposure to moderate illumination in all three procedures. The results show that while the procedures were appropriate for assessing stimulus aversiveness, 100 kV/m is not a generally aversive stimulus for the rat. (2) Magnetic Field: Thomas, Schrot and Liboff (Bioelectromagnetics: 7: 349--357 (1986)) reported that immediately after exposure for 30 min to a horizontal 60-Hz, 5 {times} 10{sup {minus}5}T field combined with a total static field of 2.61 {times} 10{sup {minus}5}T, the rate of lever pressing by rats increased during the DRL component of a multiple fixed ratio, DRL schedule of food reinforcement. This project failed to confirm those observations in an experiment that duplicated the behavioral baseline and the magnetic field exposure conditions, with the exception that the total DC vector was greater in these Rochester experiments than it was in Thomas et al, which was done in Bethesda, MD.

  9. Field-aligned currents and ionospheric electric fields

    NASA Technical Reports Server (NTRS)

    Yasuhara, F.; Akasofu, S.-I.

    1977-01-01

    It is shown that the observed distribution of the ionospheric electric field can be deduced from an equation combining Ohm's law with the current continuity equation by using the 'observed' distribution of field-aligned currents as the boundary condition for two models of the ionosphere. The first model has one conductive annular ring representing the quiet-time auroral precipitation belt; the second has two conductive annular rings that simulate the discrete and diffuse auroral regions. An analysis is performed to determine how well the electric-field distribution can be reproduced. The results indicate that the first model reproduces the Sq(p)-type distribution, the second model reproduces reasonably well a substorm-type potential and ionospheric current patterns together with the Harang discontinuity, and that the distribution of field-aligned currents is the same for both models.

  10. Method of electric field flow fractionation wherein the polarity of the electric field is periodically reversed

    DOEpatents

    Stevens, Fred J.

    1992-01-01

    A novel method of electric field flow fractionation for separating solute molecules from a carrier solution is disclosed. The method of the invention utilizes an electric field that is periodically reversed in polarity, in a time-dependent, wave-like manner. The parameters of the waveform, including amplitude, frequency and wave shape may be varied to optimize separation of solute species. The waveform may further include discontinuities to enhance separation.

  11. Magnetostimulated inhomogeneity of electric field in aluminum

    SciTech Connect

    Sobol, V.R.; Mazurenko, O.N.; Drozd, A.A.

    1997-06-01

    The peculiarities of potential and current distribution in metals under inhomogeneous action of magnetic field is studied experimentally and analytically. Magnetic field inhomogeneity is modeled with a method of curving the electric current lines in rectangular conductors through the use of preset profiles of samples. Observed inhomogeneous distribution of electric potential is analyzed on the base of charge continuity. It is shown that current density redistribution takes place. Near one side current density is high and near another it is small. This is a reason of decrease of an effective cross-section of conductor with respective enhancement of magnetoresistance. Some analytical relations and modes of applications of observed phenomena in cryogenic electronic devices are proposed.

  12. Micro-Hall devices for magnetic, electric and photo-detection

    NASA Astrophysics Data System (ADS)

    Gilbertson, A.; Sadeghi, H.; Panchal, V.; Kazakova, O.; Lambert, C. J.; Solin, S. A.; Cohen, L. F.

    Multifunctional mesoscopic sensors capable of detecting local magnetic (B) , electric (E) , and optical fields can greatly facilitate image capture in nano-arrays that address a multitude of disciplines. The use of micro-Hall devices as B-field sensors and, more recently as E-field sensors is well established. Here we report the real-space voltage response of InSb/AlInSb micro-Hall devices to not only local E-, and B-fields but also to photo-excitation using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local E-fields. Our experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. At room temperature, samples exhibit a magnetic sensitivity of >500 nT/ √Hz, an optical noise equivalent power of >20 pW/ √Hz (λ = 635 nm) comparable to commercial photoconductive detectors, and charge sensitivity of >0.04 e/ √Hz comparable to that of single electron transistors. Work done while on sabbatical from Washington University. Co-founder of PixelEXX, a start-up whose focus is imaging nano-arrays.

  13. The performance of residential micro-cogeneration coupled with thermal and electrical storage

    NASA Astrophysics Data System (ADS)

    Kopf, John

    Over 80% of residential secondary energy consumption in Canada and Ontario is used for space and water heating. The peak electricity demands resulting from residential energy consumption increase the reliance on fossil-fuel generation stations. Distributed energy resources can help to decrease the reliance on central generation stations. Presently, distributed energy resources such as solar photovoltaic, wind and bio-mass generation are subsidized in Ontario. Micro-cogeneration is an emerging technology that can be implemented as a distributed energy resource within residential or commercial buildings. Micro-cogeneration has the potential to reduce a building's energy consumption by simultaneously generating thermal and electrical power on-site. The coupling of a micro-cogeneration device with electrical storage can improve the system's ability to reduce peak electricity demands. The performance potential of micro-cogeneration devices has yet to be fully realized. This research addresses the performance of a residential micro-cogeneration device and it's ability to meet peak occupant electrical loads when coupled with electrical storage. An integrated building energy model was developed of a residential micro-cogeneration system: the house, the micro-cogeneration device, all balance of plant and space heating components, a thermal storage device, an electrical storage device, as well as the occupant electrical and hot water demands. This model simulated the performance of a micro-cogeneration device coupled to an electrical storage system within a Canadian household. A customized controller was created in ESP-r to examine the impact of various system control strategies. The economic performance of the system was assessed from the perspective of a local energy distribution company and an end-user under hypothetical electricity export purchase price scenarios. It was found that with certain control strategies the micro-cogeneration system was able to improve the

  14. Spin generation by strong inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Finkler, Ilya; Engel, Hans-Andreas; Rashba, Emmanuel; Halperin, Bertrand

    2007-03-01

    Motivated by recent experiments [1], we propose a model with extrinsic spin-orbit interaction, where an inhomogeneous electric field E in the x-y plane can give rise, through nonlinear effects, to a spin polarization with non-zero sz, away from the sample boundaries. The field E induces a spin current js^z= z x(αjc+βE), where jc=σE is the charge current, and the two terms represent,respectively, the skew scattering and side-jump contributions. [2]. The coefficients α and β are assumed to be E- independent, but conductivity σ is field dependent. We find the spin density sz by solving the equation for spin diffusion and relaxation with a source term ∇.js^z. For sufficiently low fields, jc is linear in E, and the source term vanishes, implying that sz=0 away from the edges. However, for large fields, σ varies with E. Solving the diffusion equation in a T-shaped geometry, where the electric current propagates along the main channel, we find spin accumulation near the entrance of the side channel, similar to experimental findings [1]. Also, we present a toy model where spin accumulation away from the boundary results from a nonlinear and anisotropic conductivity. [1] V. Sih, et al, Phys. Rev. Lett. 97, 096605 (2006). [2] H.-A. Engel, B.I. Halperin, E.I.Rashba, Phys. Rev. Lett. 95, 166605 (2005).

  15. Electric fields produced by Florida thunderstorms

    NASA Technical Reports Server (NTRS)

    Livingston, J. M.; Krider, E. P.

    1978-01-01

    Twenty-five field mill sites provided data on the electric fields produced during both the intense and the final, less active periods of summer air mass thunderstorms in east central Florida. During the periods of intense lightning activity, time- and area-averaged fields were usually -0.8 to -2.1 kV/m, while for the less active periods, the field values were typically in the range of -2.3 to -4.3 kV/m. Furthermore, during the active storm periods, which represented about 27% of the total storm durations, about 71% of all lightning discharges occurred. Also, fewer lightning discharges in the final storm period than in the active period reached the ground.

  16. Extremely low frequency electric fields and cancer: assessing the evidence.

    PubMed

    Kheifets, Leeka; Renew, David; Sias, Glenn; Swanson, John

    2010-02-01

    Much of the research and reviews on extremely low frequency (ELF) electric and magnetic fields (EMFs) have focused on magnetic rather than electric fields. Some have considered such focus to be inappropriate and have argued that electric fields should be part of both epidemiologic and laboratory work. This paper fills the gap by systematically and critically reviewing electric-fields literature and by comparing overall strength of evidence for electric versus magnetic fields. The review of possible mechanisms does not provide any specific basis for focusing on electric fields. While laboratory studies of electric fields are few, they do not indicate that electric fields should be the exposure of interest. The existing epidemiology on residential electric-field exposures and appliance use does not support the conclusion of adverse health effects from electric-field exposure. Workers in close proximity to high-voltage transmission lines or substation equipment can be exposed to high electric fields. While there are sporadic reports of increase in cancer in some occupational studies, these are inconsistent and fraught with methodologic problems. Overall, there seems little basis to suppose there might be a risk for electric fields, and, in contrast to magnetic fields, and with a possible exception of occupational epidemiology, there seems little basis for continued research into electric fields. (c) 2009 Wiley-Liss, Inc.

  17. Multifunctional semiconductor micro-Hall devices for magnetic, electric, and photo-detection

    NASA Astrophysics Data System (ADS)

    Gilbertson, A. M.; Sadeghi, Hatef; Panchal, V.; Kazakova, O.; Lambert, C. J.; Solin, S. A.; Cohen, L. F.

    2015-12-01

    We report the real-space voltage response of InSb/AlInSb micro-Hall devices to local photo-excitation, electric, and magnetic fields at room temperature using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local electric fields. Experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. The magnetic, photo, and charge sensitivity of a 2 μm wide probe are evaluated at a 10 μA bias current in the Johnson noise limit (valid at measurement frequencies > 10 kHz) to be, respectively, 500 nT/√Hz; 20 pW/√Hz (λ = 635 nm) comparable to commercial photoconductive detectors; and 0.05 e/√Hz comparable to that of single electron transistors. These results demonstrate the remarkably versatile sensing attributes of simple semiconductor micro-Hall devices that can be applied to a host of imaging and sensing applications.

  18. Multifunctional semiconductor micro-Hall devices for magnetic, electric, and photo-detection

    SciTech Connect

    Gilbertson, A. M.; Cohen, L. F.; Sadeghi, Hatef; Lambert, C. J.; Panchal, V.; Kazakova, O.; Solin, S. A.

    2015-12-07

    We report the real-space voltage response of InSb/AlInSb micro-Hall devices to local photo-excitation, electric, and magnetic fields at room temperature using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local electric fields. Experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. The magnetic, photo, and charge sensitivity of a 2 μm wide probe are evaluated at a 10 μA bias current in the Johnson noise limit (valid at measurement frequencies > 10 kHz) to be, respectively, 500 nT/√Hz; 20 pW/√Hz (λ = 635 nm) comparable to commercial photoconductive detectors; and 0.05 e/√Hz comparable to that of single electron transistors. These results demonstrate the remarkably versatile sensing attributes of simple semiconductor micro-Hall devices that can be applied to a host of imaging and sensing applications.

  19. Manipulation of nano-entities in suspension by electric fields

    NASA Astrophysics Data System (ADS)

    Fan, Donglei

    Nanoscale entities, including nanospheres, nanodisks, nanorings, nanowires and nanotubes are potential building blocks for nanoscale devices. Among them, nanowires is an important type of nanoparticles, due to the potential application in microelectronics and bio-diagnosis. Manipulation of nanowires in suspension has been a formidable problem. As described in this thesis, using AC electric fields applied to strategically designed microelectrodes, nanowires in suspension can be driven to align, to chain, to accelerate in directions parallel and perpendicular to its orientation, to concentrate onto designated places, and to disperse in a controlled manner with high efficiency despite an extremely low Reynolds number at the level of 10-5. Randomly oriented nanowires in suspension can be rapidly assembled into extended nonlinear structures within seconds. We show that both the electric field and its gradient play the essential roles of aligning and transporting the nanowires into scaffolds according to the electric field distributions inherent to the geometry of the microelectrodes. The assembling efficiency depends strongly on the frequency of the applied AC voltages and varies as square of the voltage. Furthermore, nanowires have been rotated by AC electric fields applied to strategically designed electrodes. The rotation of the nanowires can be instantly switched on or off with precisely controlled rotation speed (to at least 25000 rpm), definite chirality, and total angle of rotation. This new method has been used to controllably rotate magnetic and non-magnetic nanowires as well as multi-wall carbon nanotubes. We have also produced a micromotor using a rotating nanowire that can drive particles into circular motion. This has application to microfluidic devices, micro-stirrers, and micro electromechanical systems (MEMS). To move and place nanowires onto designated locations with high precision, electrophoretic force has been combined with dielectrophoretic force to

  20. Electric and magnetic fields at power frequencies.

    PubMed

    Miller, Anthony B; Green, Lois M

    2010-01-01

    Exposures to electric and magnetic fields are among the most ubiquitous exposures that the Canadian population experiences. Sources of electric and magnetic field exposures may be occupational or residential and include proximity to certain types of electrical equipment, transmission and distribution power lines as well as appliance use. The early studies of children tended toward a consistent association between risks for leukemia and brain cancer and residential proximity to power lines having high wire configuration. More recent studies-and studies which have attempted to improve upon the measurement of exposure by using calculated fields, point-in-time or personal monitoring-have been inconsistent, with some suggesting increased risk and others not. Occupational exposures have suggested an increase in risk for leukemia, and to a lesser extent brain cancer and Non-Hodgkin lymphoma. However, studies of residential exposures and cancer in adults generally have suggested no effect. Laboratory work has been unable to demonstrate a biological mechanism which might explain the epidemiological findings. In spite of extensive efforts over the past 20 years and many expert reviews, it has been difficult to reach consensus regarding the carcinogenic effects of electric and magnetic fields. Exposure assessment has proven to be complex, and agreement on the relevant exposure metric has not yet been obtained. There is justification to question whether point-in-time measures in homes are appropriate indices of the relevant etiological exposure, as they fail to account for changes over time, peak exposures or time-varying fields. Nevertheless, it is probably desirable to err on the side of caution in not placing too much weight on the inconsistencies. The IARC has classified EMF as a "possible carcinogen" which refers to the circumstances where there is limited evidence of carcinogenicity in humans and inadequate evidence in experimental animals. The IARC review indicated

  1. Electrical Grounding - a Field for Geophysicists and Electrical Engineers Partnership

    NASA Astrophysics Data System (ADS)

    Freire, P. F.; Pane, E.; Guaraldo, N.

    2012-12-01

    , layered stratified or showing lateral variations, ranging down to several tens of kilometers deep, reaching the crust-mantle interface (typically with the order of 30-40 km). This work aims to analyze the constraints of the current soil models being used for grounding electrodes design, and suggests the need of a soil modeling methodology compatible with large grounding systems. Concerning the aspects related to soil modeling, electrical engineers need to get aware of geophysics resources, such as: - geophysical techniques for soil electrical resistivity prospection (down to about 15 kilometers deep); and - techniques for converting field measured data, from many different geophysical techniques, into adequate soil models for grounding grid simulation. It is also important to equalize the basic knowledge for the professionals that are working together for the specific purpose of soil modeling for electrical grounding studies. The authors have experienced the situation of electrical engineers working with geophysicists, but it was not clear for the latter the effective need of the electrical engineers, and for the engineers it was unknown the available geophysical resources, and also, what to do convert the large amount of soil resistivity data into a reliable soil model.

  2. Failure analysis for micro-electrical-mechanical systems (MEMS)

    SciTech Connect

    Peterson, K.A.; Tangyunyong, P.; Barton, D.L.

    1997-10-01

    Micro-Electrical Mechanical Systems (MEMS) is an emerging technology with demonstrated potential for a wide range of applications including sensors and actuators for medical, industrial, consumer, military, automotive and instrumentation products. Failure analysis (FA) of MEMS is critically needed for the successful design, fabrication, performance analysis and reliability assurance of this new technology. Many devices have been examined using techniques developed for integrated circuit analysis, including optical inspection, scanning laser microscopy (SLM), scanning electron microscopy (SEM), focused ion beam (FIB) techniques, atomic force microscopy (AFM), infrared (IR) microscopy, light emission (LE) microscopy, acoustic microscopy and acoustic emission analysis. For example, the FIB was used to microsection microengines that developed poor performance characteristics. Subsequent SEM analysis clearly demonstrated the absence of wear on gear, hub, and pin joint bearing surfaces, contrary to expectations. Another example involved the use of infrared microscopy for thermal analysis of operating microengines. Hot spots were located, which did not involve the gear or hub, but indicated contact between comb structures which drive microengines. Voltage contrast imaging proved useful on static and operating MEMS in both the SEM and the FIB and identified electrostatic clamping as a potentially significant contributor to failure mechanisms in microengines. This work describes MEMS devices, FA techniques, failure modes, and examples of FA of MEMS.

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

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  4. Electric Field Induced Surface Modification of Au

    SciTech Connect

    Erchak, A.A.; Franklin, G.F.; Houston, J.E.; Mayer, T.M.; Michalske, T.A.

    1999-02-15

    We discuss the role of localized high electric fields in the modification of Au surfaces with a W probe using the Interfacial Force Microscope. Upon bringing a probe close to a Au surface, we measure both the interfacial force and the field emission current as a function of separation with a constant potential of 100 V between tip and sample. The current initially increases exponentially as the separation decreases. However, at a distance of less than {approximately} 500{angstrom} the current rises sharply as the surface begins to distort and rapidly close the gap. Retraction of the tip before contact is made reveals the formation of a mound on the surface. We propose a simple model, in which the localized high electric field under the tip assists the production of mobile Au adatoms by detachment from surface steps, and a radial field gradient causes a net flux of atoms toward the tip by surface diffusion. These processes give rise to an unstable surface deformation which, if left unchecked, results in a destructive mechanical contact. We discuss our findings with respect to earlier work using voltage pulses in the STM as a means of nanofabrication.

  5. Electron transport in argon in crossed electric and magnetic fields

    PubMed

    Ness; Makabe

    2000-09-01

    An investigation of electron transport in argon in the presence of crossed electric and magnetic fields is carried out over a wide range of values of electric and magnetic field strengths. Values of mean energy, ionization rate, drift velocity, and diffusion tensor are reported here. Two unexpected phenomena arise; for certain values of electric and magnetic field we find regions where the swarm mean energy decreases with increasing electric fields for a fixed magnetic field and regions where swarm mean energy increases with increasing magnetic field for a fixed electric field.

  6. Aircraft electric field measurements: Calibration and ambient field retrieval

    NASA Technical Reports Server (NTRS)

    Koshak, William J.; Bailey, Jeff; Christian, Hugh J.; Mach, Douglas M.

    1994-01-01

    An aircraft locally distorts the ambient thundercloud electric field. In order to determine the field in the absence of the aircraft, an aircraft calibration is required. In this work a matrix inversion method is introduced for calibrating an aircraft equipped with four or more electric field sensors and a high-voltage corona point that is capable of charging the aircraft. An analytic, closed form solution for the estimate of a (3 x 3) aircraft calibration matrix is derived, and an absolute calibration experiment is used to improve the relative magnitudes of the elements of this matrix. To demonstrate the calibration procedure, we analyze actual calibration date derived from a Lear jet 28/29 that was equipped with five shutter-type field mill sensors (each with sensitivities of better than 1 V/m) located on the top, bottom, port, starboard, and aft positions. As a test of the calibration method, we analyze computer-simulated calibration data (derived from known aircraft and ambient fields) and explicitly determine the errors involved in deriving the variety of calibration matrices. We extend our formalism to arrive at an analytic solution for the ambient field, and again carry all errors explicitly.

  7. Colloidal Switches by Electric and Magnetic Fields.

    PubMed

    Demirörs, Ahmet Faik; Beltramo, Peter J; Vutukuri, Hanumantha Rao

    2017-05-24

    External electric and magnetic fields have already been proven to be a versatile tool to control the particle assembly; however, the degree of control of the dynamics and versatility of the produced structures is expected to increase if both can be implemented simultaneously. For example, while micromagnets can rapidly assemble superparamagnetic particles, repeated, rapid disassembly or reassembly is not trivial because of the remanence and coercivity of metals used in such applications. Here, an interdigitated design of micromagnet and microfabricated electrodes enables rapid switching of colloids between their magnetic and electric potential minima. Active control over colloids between two such adjacent potential minima enables a fast on/off mechanism, which is potentially important for optical switches or display technologies. Moreover, we demonstrate that the response time of the colloids between these states is on the order of tens of milliseconds, which is tunable by electric field strength. By carefully designing the electrode pattern, our strategy enables the switchable assembly of single particles down to few microns and also hierarchical assemblies containing many particles. Our work on precise dynamic control over the particle position would open new avenues to find potential applications in optical switches and display technologies.

  8. Electric field-free gas breakdown in explosively driven generators

    SciTech Connect

    Shkuratov, Sergey I.; Baird, Jason; Talantsev, Evgueni F.; Altgilbers, Larry L.

    2010-07-15

    All known types of gas discharges require an electric field to initiate them. We are reporting on a unique type of gas breakdown in explosively driven generators that does not require an electric field.

  9. Electric Field Effects on Fiber Alignment Using an Auxiliary Electrode during Electrospinning

    NASA Technical Reports Server (NTRS)

    Carnell, Lisa S.; Wincheski, Russell A.; Siochi, Emilie, J.; Holloway, Nancy M.; Clark, Robert L.

    2007-01-01

    This viewgraph presentation reviews auxiliary and electric field effects on fiber alignment during the process of electrospinning. The contents include: 1) Electrospinning Overview; 2) Experimental Set-up; 3) Jet Exit; 4) Auxiliary Electrode Effects; 5) Electrospinning High Speed Video; 6) Effect of Auxiliary Electrode Position; 7) Micro & Nano Fibers Produced; 8) Micro and Nano Fibrous Mats; 9) Field Effect on Fiber Distribution; 10) Modeling; 11) Calculated trajectories: 5, 10, 15 & 20cm electrode spacing; 12) Off Axis Auxiliary Electrode; 13) Field Strength Effects; and 14) Potential Applications.

  10. Low frequency electric and magnetic fields

    NASA Technical Reports Server (NTRS)

    Spaniol, Craig

    1989-01-01

    Following preliminary investigations of the low frequency electric and magnetic fields that may exists in the Earth-ionospheric cavity, measurements were taken with state-of-the art spectrum analyzers. As a follow up to this activity, an investigation was initiated to determine sources and values for possible low frequency signal that would appear in the cavity. The lowest cavity resonance is estimated at about 8 Hz, but lower frequencies may be an important component of our electromagnetic environment. The potential field frequencies produced by the electron were investigated by a classical model that included possible cross coupling of the electric and gravitation fields. During this work, an interesting relationship was found that related the high frequency charge field with the extremely low frequency of the gravitation field. The results of numerical calculations were surprisingly accurate and this area of investigation is continuing. The work toward continued development of a standardized monitoring facility is continuing with the potential of installing the prototype at West Virginia State College early in 1990. This installation would be capable of real time monitoring of ELF signals in the Earth-ionoshpere cavity and would provide some directional information. A high gain, low noise, 1/f frequency corrected preamplifier was designed and tested for the ferrite core magnetic sensor. The potential application of a super conducting sensor for the ELF magnetic field detection is under investigation. It is hoped that a fully operational monitoring network could pinpoint the location of ELF signal sources and provide new information on where these signals originate and what causes them, assuming that they are natural in origin.

  11. Motional sideband excitation using rotating electric fields

    NASA Astrophysics Data System (ADS)

    Isaac, C. A.

    2013-04-01

    A form of motional sideband excitation is described in which a rotating dipole electric field is applied asymmetrically onto a Penning-type trap in the presence of a mechanism for cooling the axial motion of the trapped particles. In contrast to the traditional motional sideband excitation, which uses an oscillating electric field, the rotating field results in only one active sideband in each sense of rotation and so avoids accidental excitation of the other sideband making it applicable to Penning-type traps with a large degree of anharmonicity. Expressions are derived for the magnetron radius expansion and compression rates attainable, and approximations are made for the case of strong and weak drives. A comparison is made with data, taken using a two-stage positron accumulator presented by Isaac [C. A. Isaac, C. J. Baker, T. Mortensen, D. P. van der Werf, and M. Charlton, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.033201 107, 033201 (2011)], showing good agreement between the model and experiment.

  12. Hydrogel Actuation by Electric Field Driven Effects

    NASA Astrophysics Data System (ADS)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  13. Electric field imaging of a high impedance surface for GNSS array decoupling application

    NASA Astrophysics Data System (ADS)

    Prost, Daniel; Issac, François; Martel, Cédric; Capet, Nicolas; Sokoloff, Jérôme; Pascal, Olivier

    2015-10-01

    An original method of characterization of high impedance surfaces (HIS) is presented to exhibit electric field patterns. The electric field frames are obtained through a resistive film located in the near field domain of the HIS. The film heating is recorded using an infrared camera and gives after post-processing electric field magnitude profiles. We applied this technique to a HIS specially tuned for reducing mutual coupling in a global navigation satellite systems (GNSS) array designed for the E5 Galileo band. The mushroom-like HIS, designed and realized with the help of simulation, is located near the ground plane of a micro-strip line which allows S parameter characterization. Present measurement enables near field characterization and field structure analysis, and is therefore a complement to usual analysis. Moreover, the technique shows the very special field structure, including sub-lambda details, created by the HIS and more generally by metamaterial structures.

  14. Extracting Nucleon Magnetic Moments and Electric Polarizabilities from Lattice QCD in Background Electric Fields

    SciTech Connect

    William Detmold; Tiburzi, Brian C.; Walker-Loud, Andre

    2010-03-01

    Nucleon properties are investigated in background electric fields. As the magnetic moments of baryons affect their relativistic propagation in constant electric fields, electric polarizabilities cannot be determined without knowledge of magnetic moments. We devise combinations of baryon two-point functions in external electric fields to isolate both observables. Using an ensemble of anisotropic gauge configurations with dynamical clover fermions, we demonstrate how magnetic moments and electric polarizabilities can be determined from lattice QCD simulations in background electric fields. We obtain results for both the neutron and proton. Our study is currently limited to electrically neutral sea quarks.

  15. Radial-Electric-Field Piezoelectric Diaphragm Pumps

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

    2009-01-01

    In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

  16. Importance of electric fields from ionized nanoparticles for radiation therapy

    NASA Astrophysics Data System (ADS)

    Shmatov, M. L.

    2017-05-01

    A model is presented in which electric fields from ionized particles in a biological tissue enhance the biological effect of ionizing radiation. The model is based on the data on enhancing the gamma radiation effect on biological cells by static electric fields and on estimates of the typical intensities of electric fields from ionized nanoparticles in a biological tissue.

  17. Electric Field Dependence of Photo-Induced Field Emission Current.

    NASA Astrophysics Data System (ADS)

    Egert, Charles Michael

    We have measured the photo-induced field emission current from a tungsten field emitter as a function of electric field. These experiments were performed with a retardation energy analyzer to measure total current and a 127(DEGREES) cylindrical differential energy analyzer to measure the energy resolved PFE current. The results of these experiments are compared with a simple theory of PFE, developed by Schwartz and Schaich, which is an extension of field emission theory including the surface photoeffect, but assuming constant photoexcitation matrix elements. Our experimental results disagree with this theory in two ways: First, for high fields and photon energy (electrons emitted above the field emission barrier maximum) theory predicts a larger increase in PFE current than is observed experimentally. Second, we have also confirmed the existence of a field dependent oscillatory component of the PFE current emitted from the W(110) surface with photon energies of 2.7 eV and 3.5 eV. The simple theory described here, as well as more sophisticated calculations, have been unable to explain this oscillatory feature. We have also reported, for the first time, the field dependence of the energy resolved PFE current measured with a 127(DEGREES) cylindrical energy analyzer. These preliminary results show evidence of the oscillatory component previously only observed in the total PFE current.

  18. Electrostatic air filters generated by electric fields

    SciTech Connect

    Bergman, W.; Biermann, A.H.; Hebard, H.D.; Lum, B.Y.; Kuhl, W.D.

    1981-01-27

    This paper presents theoretical and experimental findings on fibrous filters converted to electrostatic operation by a nonionizing electric field. Compared to a conventional fibrous filter, the electrostatic filter has a higher efficiency and a longer, useful life. The increased efficiency is attributed to a time independent attraction between polarized fibers and charged, polarized particles and a time dependent attraction between charged fibers and charged, polarized particles. The charge on the fibers results from a dynamic process of charge accumulation due to the particle deposits and a charge dissipation due to the fiber conductivity.

  19. Perturbative renormalization of the electric field correlator

    NASA Astrophysics Data System (ADS)

    Christensen, C.; Laine, M.

    2016-04-01

    The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ∼ 12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.

  20. Magnetic resonance electrical impedance tomography for determining electric field distribution during electroporation

    NASA Astrophysics Data System (ADS)

    Kranjc, Matej; Bajd, Franci; Serša, Igor; Miklavčič, Damijan

    2013-04-01

    Electroporation is a phenomenon caused by externally applied electric field to cells that results in an increase of cell membrane permeability to various molecules. Accurate coverage of the tissue with a sufficiently large electric field presents one of the most important conditions for successful membrane permeabilization. Applications based on electroporation would greatly benefit with a method for monitoring the electric field, especially if it could be done in situ. As the membrane electroporation is a consequence of an induced transmembrane potential, which is directly proportional to the local electric field, we have been investigating current density imaging and magnetic resonance electrical impedance tomography techniques to determine the electric field distribution during electroporation. In this paper, we present comparison of current density and electric field distribution in an agar phantom and in a liver tissue exposed to electroporation pulses. As expected, a region of increased electrical conductivity was observed in the liver tissue exposed to sufficiently high electric field but not in agar phantom.

  1. Ion-protein dissociation predicts 'windows' in electric field-induced wound-cell proliferation.

    PubMed

    Binhi, V N; Goldman, R J

    2000-04-06

    There are many experiments showing that weak, non-thermal electric fields influence living tissues. In many cases, biological effects display 'windows' in biologically effective parameters of electric fields: most dramatic is the fact that relatively intense electric fields sometimes do not cause appreciable effect, while smaller fields do. Linear resonant physical processes do not explain frequency windows in this case. Both frequency and amplitude windows are evident from experiments on human dermal fibroblasts in a collagen matrix. For this in vitro model of skin, exposure to extremely low frequency (ELF) electric fields in the frequency range 10-100 Hz and the amplitude range of 0-130 microA/cm(2) macroscopic current density demonstrates such unusual 'window' behavior. Amplitude window phenomena suggest a non-linear physical mechanism. We consider non-linear quantum-interference effects on protein-bound substrate ions: These ions experience, due to electric fields in the media or biological tissue as small as 1 mV/m, electric gradients produced by polarized binding ligand atomic shells. The electric gradients cause an interference of ion quantum states. This ion-interference mechanism predicts specific electric-field frequency and amplitude windows within which fibroblast proliferation occurs.

  2. Impact of electric fields on honey bees

    SciTech Connect

    Bindokas, V.P.

    1985-01-01

    Biological effects in honey bee colonies under a 765-kV, 60-Hz transmission line (electric (E) field = 7 kV/m) were confirmed using controlled dosimetry and treatment reversal to replicate findings within the same season. Hives in the same environment but shielded from E field are normal, suggesting effects are caused by interaction of E field with the hive. Bees flying through the ambient E field are not demonstrably affected. Different thresholds and severity of effects were found in colonies exposed to 7, 5.5, 4.1, 1.8, and 0.65 to 0.85 kV/m at incremental distances from the line. Most colonies exposed at 7 kV/m failed in 8 weeks and failed to overwinter at greater than or equal to4.1 kV/m. Data suggest the limit of a biological effects corridor lies between 15 and 27 m (4.1 and 1.8 kV/m) beyond the outer phase of the transmission line. Mechanisms to explain colony disturbance fall into two categories, direct perception of enhanced in-hive E fields, and perception of shock from induced currents. The same effects induced in colonies with total-hive E-field exposure can be reproduced with shock or E-field exposure of worker bees in extended hive entranceways (= porches). Full-scale experiments demonstrate bee exposure to E fields including 100 kV/m under moisture-free conditions within a non-conductive porch causes no detectable effect on colony behavior. Exposure of bees on a conductive (e.g. wet) substrate produces been disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. Thresholds for effects caused by step-potential-induced currents are: 275-350 nA - disturbance of single bees; 600 nA - onset of abnormal propolization; and 900 nA - sting.

  3. Soil Identification using Field Electrical Resistivity Method

    NASA Astrophysics Data System (ADS)

    Hazreek, Z. A. M.; Rosli, S.; Chitral, W. D.; Fauziah, A.; Azhar, A. T. S.; Aziman, M.; Ismail, B.

    2015-06-01

    Geotechnical site investigation with particular reference to soil identification was important in civil engineering works since it reports the soil condition in order to relate the design and construction of the proposed works. In the past, electrical resistivity method (ERM) has widely being used in soil characterization but experienced several black boxes which related to its results and interpretations. Hence, this study performed a field electrical resistivity method (ERM) using ABEM SAS (4000) at two different types of soils (Gravelly SAND and Silty SAND) in order to discover the behavior of electrical resistivity values (ERV) with type of soils studied. Soil basic physical properties was determine thru density (p), moisture content (w) and particle size distribution (d) in order to verify the ERV obtained from each type of soil investigated. It was found that the ERV of Gravelly SAND (278 Ωm & 285 Ωm) was slightly higher than SiltySAND (223 Ωm & 199 Ωm) due to the uncertainties nature of soils. This finding has showed that the results obtained from ERM need to be interpreted based on strong supported findings such as using direct test from soil laboratory data. Furthermore, this study was able to prove that the ERM can be established as an alternative tool in soil identification provided it was being verified thru other relevance information such as using geotechnical properties.

  4. Fabrication of micro-patterns via near-field electrospray

    NASA Astrophysics Data System (ADS)

    Li, Wenwang; Zheng, Gaofeng; Xu, Lei; Wang, Xiang

    2016-11-01

    A near-field electrospray process is developed to deposited micro-patterns. Compared with conventional electrospray, near field electrospray uses a steel probe instead of capillary nozzle, and its nozzle-to-substrate distance is shortened to several millimeters to realize micro-scale deposition area. The liquid is supplied by discretely dipping the probe into solution in advance so that electrospray process maintains until the consumption of liquid adhered at the probe tip. The influence of solution conductivity and applied voltage on deposition are investigated, as increasing solution conductivity and high applied voltage may promote the electrospray process and enlarge the line width. In addition, micro-patterns with various materials are directly electrosprayed.

  5. Electric and magnetic field exposure, chemical exposure, and leukemia risk in electrical'' occupations

    SciTech Connect

    Bowman, J.D.; Sobel, E.; London, S.J.; Thomas, D.C.; Garabrant, D.H.; Pearce, N.; Peters, J.M. . Dept. of Preventive Medicine)

    1992-12-01

    This project was conducted to address what are the extremely low frequency (ELF) magnetic and electric field exposures of workers in electrical'' occupations and do they exceed exposures encountered in non-electrical'' occupations and what are the chemical and physical exposures in the electrical'' occupations and do they exceed exposures encountered in non-electrical'' occupations Two subsidiary issues were does characterization and quantification of ELF magnetic field exposure in the electrical'' occupations provide data to support a dose response relationship between leukemia risk and electric or magnetic field exposure and do dffferences in chemical exposure between the occupations help explain the previously observed leukemia risk associated with these electrical'' occupations Data were collected in 3 regions in which electrical workers had been reported to have an excess of leukemia - New Zealand, Los Angeles and Seattle Measurements of magnetic fields were made on 493 electrical workers and 163 non-electrical workers.

  6. Electric and magnetic field exposure, chemical exposure, and leukemia risk in ``electrical`` occupations. Final report

    SciTech Connect

    Bowman, J.D.; Sobel, E.; London, S.J.; Thomas, D.C.; Garabrant, D.H.; Pearce, N.; Peters, J.M.

    1992-12-01

    This project was conducted to address what are the extremely low frequency (ELF) magnetic and electric field exposures of workers in ``electrical`` occupations and do they exceed exposures encountered in ``non-electrical`` occupations? and what are the chemical and physical exposures in the ``electrical`` occupations and do they exceed exposures encountered in ``non-electrical`` occupations? Two subsidiary issues were does characterization and quantification of ELF magnetic field exposure in the ``electrical`` occupations provide data to support a dose response relationship between leukemia risk and electric or magnetic field exposure? and do dffferences in chemical exposure between the occupations help explain the previously observed leukemia risk associated with these ``electrical`` occupations? Data were collected in 3 regions in which electrical workers had been reported to have an excess of leukemia - New Zealand, Los Angeles and Seattle Measurements of magnetic fields were made on 493 electrical workers and 163 non-electrical workers.

  7. Random electric field instabilities of relaxor ferroelectrics

    DOE PAGES

    Arce-Gamboa, Jose R.; Guzman-Verri, Gian G.

    2017-06-13

    Relaxor ferroelectrics are complex oxide materials which are rather unique to study the effects of compositional disorder on phase transitions. Here, we study the effects of quenched cubic random electric fields on the lattice instabilities that lead to a ferroelectric transition and show that, within a microscopic model and a statistical mechanical solution, even weak compositional disorder can prohibit the development of long-range order and that a random field state with anisotropic and power-law correlations of polarization emerges from the combined effect of their characteristic dipole forces and their inherent charge disorder. As a result, we compare and reproduce severalmore » key experimental observations in the well-studied relaxor PbMg1/3Nb2/3O3–PbTiO3.« less

  8. Electric fields and double layers in plasmas

    NASA Astrophysics Data System (ADS)

    Singh, Nagendra; Thiemann, H.; Schunk, R. W.

    1987-05-01

    Various mechanisms for driving double layers (DLs) in plasmas are described, including applied potential drops, currents, contact potentials, and plasma expansions. Somne dynamic features of the DLs are discussed; and it is demonstrated that DLs and the currents through them undergo slow oscillations, determined by the ion transit time across an effective length of the system in which the DLs form. It is shown that a localized potential dip forms at the low potential end of a DL, which interrupts the electron current through it according to the Langmuir criterion whenever the ion flux into the DL is disrupted. Also considered is the generation of electric fields perpendicular to the ambient magnetic field by contact potentials.

  9. A Gravitational Experiment Involving Inhomogeneous Electric Fields

    NASA Astrophysics Data System (ADS)

    Datta, T.; Yin, Ming; Vargas, Jose

    2004-02-01

    Unification of gravitation with other forms of interactions, particularly with electromagnetism, will have tremendous impacts on technology and our understanding of nature. The economic impact of such an achievement will also be unprecedented and far more extensive than the impact experienced in the past century due to the unification of electricity with magnetism and optics. Theoretical unification of gravitation with electromagnetism using classical differential geometry has been pursued since the late nineteen twenties, when Einstein and Cartan used teleparallelism for the task. Recently, Vargas and Torr have followed the same line of research with more powerful mathematics in a more general geometric framework, which allows for the presence of other interactions. Their approach also uses Kähler generalization of Cartan's exterior calculus, which constitutes a language appropriate for both classical and quantum physics. Given the compelling nature of teleparallelism (path-independent equality of vectors at a distance) and the problems still existing with energy-momentum in general relativity, it is important to seek experimental evidence for such expectations. Such experimental programs are likely to provide quantitative guidance to the further development of current and future theories. We too, have undertaken an experimental search for potential electrically induced gravitational (EIG) effects. This presentation describes some of the practical concerns that relates to our investigation of electrical influences on laboratory size test masses. Preliminary results, appear to indicate a correlation between the application of a spatially inhomogeneous electric field and the appearance of an additional force on the test mass. If confirmed, the presence of such a force will be consistent with the predictions of Vargas-Torr. More importantly, proven results will shed new light and clearer understanding of the interactions between gravitational and electromagnetic

  10. Influence of relative humidity on analyzing electric field exposure using ELF electric field measurements.

    PubMed

    Korpinen, Leena H; Kuisti, Harri A; Tarao, Hiroo; Elovaara, Jarmo A

    2013-07-01

    The objective of the study was to investigate the influence of humidity on analyzing electric field exposure using extremely low frequency (ELF) electric field measurements. The study included 322 measurements in a climate room. We used two commercial three-axis meters, EFA-3 and EFA-300, and employed two measurement techniques in the climate room where we varied the temperature from 15 to 25 °C, the relative humidity from 55% to 95%, and the electric field from 1 to 25 kV/m. We calculated Pearson correlations between humidity and percentage errors for all data and for data at different levels of humidity. When the relative humidity was below 70%, the results obtained by the different measurement methods in terms of percentage errors were of the same order of magnitude for the considered temperatures and field strength, but the results were less reliable when the relative humidity was higher than 80%. In the future, it is important to take humidity into account when electric field measurement results will be compared to the values given in different exposure guidelines. Copyright © 2013 Wiley Periodicals, Inc.

  11. Planned waveguide electric field breakdown studies

    SciTech Connect

    Wang Faya; Li Zenghai

    2012-12-21

    This paper presents an experimental setup for X-band rf breakdown studies. The setup is composed of a section of WR90 waveguide with a tapered pin located at the middle of the waveguide E-plane. Another pin is used to rf match the waveguide so it operates in a travelling wave mode. By adjusting the penetration depth of the tapered pin, different surface electric field enhancements can be obtained. The setup will be used to study the rf breakdown rate dependence on power flow in the waveguide for a constant maximum surface electric field on the pin. Two groups of pins have been designed. The Q of one group is different and very low. The other has a similar Q. With the test of the two groups of pins, we should be able to discern how the net power flow and Q affect the breakdown. Furthermore, we will apply an electron beam treatment to the pins to study its effect on breakdown. Overall, these experiments should be very helpful in understanding rf breakdown phenomena and could significantly benefit the design of high gradient accelerator structures.

  12. Sludge pre-treatment with pulsed electric fields.

    PubMed

    Kopplow, O; Barjenbruch, M; Heinz, V

    2004-01-01

    The anaerobic stabilization process depends - among other things - on the bio-availability of organic carbon. Through pre-treatment of the sludge which leads to the destruction of micro-organisms and to the setting-free of cell content substances (disintegration), the carbon can be microbially converted better and faster. Moreover, effects on the digestion are likely. However, only little experience is available in sludge treatment with pulsed electric fields. Laboratory-scale digestion tests have been run to analyse the influence of pulsed electric fields on the properties of sludge, anaerobic degradation, sludge water reload and foaming of digesters. The results will be compared with those of other disintegration methods (high pressure homogeniser, thermal treatment). The effect of pre-treatment on the sludge is shown by the COD release. Degrees of disintegration have been achieved up to 20%. The specific energy input was high. The energy consumption has been decreased by initial improvements (pre-heating to 55 degrees C). The filament bacteria were partially destroyed. The foam reduction in the digesters was marginal. The anaerobic degradation performance has been improved in every case. The degradation rate of organic matter increased about 9%. Due to the increase of degradation, there is a higher reload of the sludge-water with COD and nitrogen compounds.

  13. Inhibition of brain tumor cell proliferation by alternating electric fields

    SciTech Connect

    Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi E-mail: radioyoon@korea.ac.kr; Sung, Jiwon; Jeong, Seonghoon; Yoon, Myonggeun E-mail: radioyoon@korea.ac.kr; Koh, Eui Kwan

    2014-11-17

    This study was designed to investigate the mechanism by which electric fields affect cell function, and to determine the optimal conditions for electric field inhibition of cancer cell proliferation. Low-intensity (<2 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were significantly dependent on the intensity and frequency of applied electric fields.

  14. Saturation of the Electric Field Transmitted to the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.

    2010-01-01

    We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.

  15. Saturation of the Electric Field Transmitted to the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.

    2010-01-01

    We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.

  16. Bead-on-string structure printed by electrohydrodynamic jet under alternating current electric field

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Lin, Yihuang; Jiang, Jiaxin; Liu, Haiyan; Zhao, Yang; Zheng, Gaofeng

    2016-09-01

    Electrohydrodynamic printing (EHDP) under alternating current (AC) electric field provides a novel way for the precise micro-/nano-droplet printing. The AC electric field induces the free charge to reciprocate along the EHDP jet and changes the electric field force on the jet periodically. The stability of jet can be enhanced by increasing the voltage frequency, and the regular bead-on-string structure is direct-written along the trajectory of collector. The deposition frequency of bead structure increases with the increasing of voltage frequency, due to the short period of AC electric field. As the voltage frequency is increased from 10 to 60 Hz, the diameter of bead structure decreases from 200 to 110 µm. As the duty ration increased from 10 to 60 %, the diameter of bead structure increased from 100 to 140 µm. This work would accelerate the development and the application of micro-/nano-printing technology in the fields of flexible electronic and micro-/nano-system.

  17. Nonlinear response of electric fields at a neutral point

    NASA Astrophysics Data System (ADS)

    Berkovsky, Mikhail; Dufty, James W.; Calisti, Annette; Stamm, Roland; Talin, Bernard

    1995-05-01

    The complex dynamics of electric fields at a neutral point in a plasma is studied via a model of noninteracting ``quasiparticles.'' The simplicity of the model allows the reduction of the many-body problem to an effective single-particle analysis-all properties of interest can be reduced to quadratures. Still, the final calculations to extract a quantitative or even qualitative understanding of the field dynamics can be difficult. Attention here is focused on the dynamics of the conditional electric field: the field value at time t for a given initial value of the field. In addition to the relevant linear response function (electric field time correlation function), this property provides the complete nonlinear response of the electric field to arbitrary initial field perturbations. The static properties (distribution of electric fields and field time derivatives) and the electric field time correlation function have been known for some time for this model. We compare these results and the present result for the conditional electric field with molecular dynamics simulations including interactions. The comparisons suggest that the model provides a quantitative representation of electric field dynamics in real plasmas, except at strong coupling. The exact theoretical results are compared also with those obtained by modeling the electric field as a stochastic variable obeying a kangaroo process. The latter can be constructed to yield both the exact stationary distribution and the exact electric field time correlation function. However, we find that the conditional field is never well approximated by this process. An alternative representation of the joint distribution for electric fields, consistent with the exact stationary distribution, field correlation function, and conditional electric field, is suggested.

  18. Introduction to power-frequency electric and magnetic fields.

    PubMed Central

    Kaune, W T

    1993-01-01

    This paper introduces the reader to electric and magnetic fields, particularly those fields produced by electric power systems and other sources using frequencies in the power-frequency range. Electric fields are produced by electric charges; a magnetic field also is produced if these charges are in motion. Electric fields exert forces on other charges; if in motion, these charges will experience magnetic forces. Power-frequency electric and magnetic fields induce electric currents in conducting bodies such as living organisms. The current density vector is used to describe the distribution of current within a body. The surface of the human body is an excellent shield for power-frequency electric fields, but power-frequency magnetic fields penetrate without significant attenuation; the electric fields induced inside the body by either exposure are comparable in magnitude. Electric fields induced inside a human by most environmental electric and magnetic fields appear to be small in magnitude compared to levels naturally occurring in living tissues. Detection of such fields thus would seem to require the existence of unknown biological mechanisms. Complete characterization of a power-frequency field requires measurement of the magnitudes and electrical phases of the fundamental and harmonic amplitudes of its three vector components. Most available instrumentation measures only a small subset, or some weighted average, of these quantities. Hand-held survey meters have been used widely to measure power-frequency electric and magnetic fields. Automated data-acquisition systems have come into use more recently to make electric- and magnetic-field recordings, covering periods of hours to days, in residences and other environments.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8206045

  19. Dynamics of an electric dipole moment in a stochastic electric field.

    PubMed

    Band, Y B

    2013-08-01

    The mean-field dynamics of an electric dipole moment in a deterministic and a fluctuating electric field is solved to obtain the average over fluctuations of the dipole moment and the angular momentum as a function of time for a Gaussian white-noise stochastic electric field. The components of the average electric dipole moment and the average angular momentum along the deterministic electric-field direction do not decay to zero, despite fluctuations in all three components of the electric field. This is in contrast to the decay of the average over fluctuations of a magnetic moment in a stochastic magnetic field with Gaussian white noise in all three components. The components of the average electric dipole moment and the average angular momentum perpendicular to the deterministic electric-field direction oscillate with time but decay to zero, and their variance grows with time.

  20. Manipulating colloids with charges and electric fields

    NASA Astrophysics Data System (ADS)

    Leunissen, M. E.

    2007-02-01

    This thesis presents the results of experimental investigations on a variety of colloidal suspensions. Colloidal particles are at least a hundred times larger than atoms or molecules, but suspended in a liquid they display the same phase behavior, including fluid and crystalline phases. Due to their relatively large size, colloids are much easier to investigate and manipulate, though. This makes them excellent condensed matter model systems. With this in mind, we studied micrometer-sized perspex (‘PMMA’) spheres, labeled with a fluorescent dye for high-resolution confocal microscopy imaging, and suspended in a low-polar mixture of the organic solvents cyclohexyl bromide and cis-decalin. This system offered us the flexibility to change the interactions between the particles from ‘hard-sphere-like’ to long-ranged repulsive (between like-charged particles), long-ranged attractive (between oppositely charged particles) and dipolar (in an electric field). We investigated the phase behavior of our suspensions as a function of the particle concentration, the ionic strength of the solvent and the particles’ charges. In this way, we obtained new insight in the freezing and melting behavior of like-charged and oppositely charged colloids. Interestingly, we found that the latter can readily form large crystals, thus defying the common belief that plus-minus interactions inevitably lead to aggregation. Moreover, we demonstrated that these systems can serve as a reliable model system for classical ionic matter (‘salts’), and that opposite-charge interactions can greatly facilitate the self-assembly of new structures with special properties for applications. On a slightly different note, we also studied electrostatic effects in mixtures of the cyclohexyl bromide solvent and water, both with and without colloidal particles present. This provided new insight in the stabilization mechanisms of oil-water emulsions and gave us control over the self-assembly of various

  1. Aircraft measurement of electric field - Self-calibration

    NASA Technical Reports Server (NTRS)

    Winn, W. P.

    1993-01-01

    Aircraft measurement of electric fields is difficult as the electrically conducting surface of the aircraft distorts the electric field. Calibration requires determining the relations between the undistorted electric field in the absence of the vehicle and the signals from electric field meters that sense the local distorted fields in their immediate vicinity. This paper describes a generalization of a calibration method which uses pitch and roll maneuvers. The technique determines both the calibration coefficients and the direction of the electric vector. The calibration of individual electric field meters and the elimination of the aircraft's self-charge are described. Linear combinations of field mill signals are examined and absolute calibration and error analysis are discussed. The calibration method was applied to data obtained during a flight near thunderstorms.

  2. Electrical integrity of oxides in a radiation field

    SciTech Connect

    Zinkle, S.J.; Kinoshita, C.

    1996-04-01

    In the absence of an applied electric field, irradiation generally produces a decrease in the permanent (beam-off) electrical conductivity of ceramic insulators. However, in the past 6 years several research groups have reported a phenomenon known as radiation induced electrical degradation (RIED), which produces significant permanent increases in the electrical conductivity of ceramic insulators irradiated with an applied electric field. RIED has been reported to occur at temperatures between 420 and 800 K with applied electric fields as low as 20 V/mm.

  3. Electric field enhanced dropwise condensation on hydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Baratian, Davood; Hoek, Harmen; van den Ende, Dirk; Mugele, Frieder; Physics of Complex Fluids Team

    2016-11-01

    Dropwise condensation occurs when vapor condenses on a low surface energy surface, and the substrate is just partially wetted by the condensate. Dropwise condensation has attracted significant attention due to its reported superior heat transfer performance compared to filmwise condensation. Extensive research efforts are focused on how to promote, and enhance dropwise condensation by considering both physical and chemical factors. We have studied electrowetting-actuated condensation on hydrophobic surfaces, aiming for enhancement of heat transfer in dropwise condensation. The idea is to use suitably structured patterns of micro-electrodes that generate a heterogeneous electric field at the interface and thereby promote both the condensation itself and the shedding of condensed drops. Comforting the shedding of droplets on electrowetting-functionalized surfaces allows more condensing surface area for re-nucleation of small droplets, leading to higher condensation rates. Possible applications of this innovative concept include heat pipes for (micro) coolers in electronics as well as in more efficient heat exchangers. We acknowledge financial support by the Dutch Technology Foundation STW, which is part of the Netherlands Organization for Scientific Research (NWO), within the VICI program.

  4. Mission Enabling and Enhancing Spacecraft Capabilities with MicroNewton Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Marrese-Reading, Colleen M.; Ziemer, John K.; Scharf, Daniel; Martin-Mur, Tomas; Thompson, Paul; Wirz, Richie; Mueller, Juergen

    2010-01-01

    The capability to significantly improve current spacecraft pointing, precision orbit maintenance and disturbance mitigation were considered using precision, quiescent microNewton electric propulsion systems. Analysis results showed that electric propulsion systems operating in the microNewton to hundreds of microNewtons thrust range can offer significant improvements over state-of-the-art mission capabilities to enable 30 m Earth-fixed orbital tubes, constellation spacecraft position control to within nanometers and exoplanet observatory pointing with 0.1 milliarcsecond precision. Specific thrust levels and profiles required to support these capabilities are discussed.

  5. Mission Enabling and Enhancing Spacecraft Capabilities with MicroNewton Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Marrese-Reading, Colleen M.; Ziemer, John K.; Scharf, Daniel; Martin-Mur, Tomas; Thompson, Paul; Wirz, Richie; Mueller, Juergen

    2010-01-01

    The capability to significantly improve current spacecraft pointing, precision orbit maintenance and disturbance mitigation were considered using precision, quiescent microNewton electric propulsion systems. Analysis results showed that electric propulsion systems operating in the microNewton to hundreds of microNewtons thrust range can offer significant improvements over state-of-the-art mission capabilities to enable 30 m Earth-fixed orbital tubes, constellation spacecraft position control to within nanometers and exoplanet observatory pointing with 0.1 milliarcsecond precision. Specific thrust levels and profiles required to support these capabilities are discussed.

  6. Difficulties in Learning the Concept of Electric Field.

    ERIC Educational Resources Information Center

    Furio, C.; Guisasola, J.

    1998-01-01

    Analyzes students' main difficulties in learning the concept of electric field. Briefly describes the main conceptual profiles within which electric interactions can be interpreted and concludes that most students have difficulty using the idea of electric field. Contains 28 references. (DDR)

  7. Spectroscopic investigation of electric field fluctuations in a steady plasma

    NASA Technical Reports Server (NTRS)

    Druetta, M. P.

    1971-01-01

    The electric fluctuations caused by plasma oscillations of a steady plasma were investigated. In order to observe this phenomenon electric field fluctuations are created in a helium plasma by an electron beam. Spectroscopic analysis reveals satellite lines disposed symmetrically in pairs about a forbidden atomic line and separated from it by the frequency of the electric field oscillations.

  8. Variations in the atmospheric electric field at mountainous observation points

    NASA Astrophysics Data System (ADS)

    Adzhiev, A. Kh.; Kupovykh, G. V.

    2015-05-01

    Study of unitary variation in the electric field of the near-surface atmosphere is a topical tasks of atmospheric electricity. This work substantiates the possible registration of global variations in the electric field intensity of the near-surface atmospheric layer at mountainous stations and discusses the results of observations in the Elbrus region.

  9. Empirical models of high latitude electric fields

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1976-01-01

    Model cross sections of the high latitude dawn-dusk electric field based on OGO-6 data are presented for the signature profiles, most frequently encountered for both + and -Y orientations of the interplanetary magnetic field. Line integrals give a total potential of 76 keV in each case. To illustrate extremes, examples of model cross-sections with total potentials of 23 keV and 140 keV are also given. Model convection patterns are also presented utilizing OGO-6 data on boundary locations at other magnetic local times. When this information is combined with characteristic field geometries in the region of the Harang discontinuity, and is supplemented by data from Ba+ cloud motions in the polar cap, it becomes possible to construct realistic convection patterns on the nightside which deviate from the usual sun-aligned patterns. The observational models presented are of limited applicability as a consequence of the variability of observed distributions. These limitations are emphasized with particular attention given to several types of recurrent deviations which have not previously been discussed.

  10. Liquid methanol under a static electric field

    SciTech Connect

    Cassone, Giuseppe; Giaquinta, Paolo V.; Saija, Franz; Saitta, A. Marco

    2015-02-07

    We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm{sup −1}) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.

  11. Electric field response in bilayer graphene: Ab initio investigation

    NASA Astrophysics Data System (ADS)

    Mori, Yutaro; Minamitani, Emi; Ando, Yasunobu; Kasamatsu, Shusuke; Watanabe, Satoshi

    2016-11-01

    Stimulated by quantum capacitance measurements, we have investigated the electric properties of bilayer graphene (BLG) with carrier doping under an external electric field using ab initio calculations. We found that the relative permittivity of BLG depends weakly on the applied electric field, and that the BLG can be regarded as a dielectric material rather than a pair of metallic films. We also found that carrier doping affects the band gap of BLG under electric fields, although carrier doping has a much smaller effect on the band gap and density of states than the application of electric fields.

  12. Electropumping of water with rotating electric fields

    NASA Astrophysics Data System (ADS)

    De Luca, Sergio; Todd, B. D.; Hansen, J. S.; Daivis, Peter J.

    2013-04-01

    Pumping of fluids confined to nanometer dimension spaces is a technically challenging yet vitally important technological application with far reaching consequences for lab-on-a-chip devices, biomimetic nanoscale reactors, nanoscale filtration devices and the like. All current pumping mechanisms require some sort of direct intrusion into the nanofluidic system, and involve mechanical or electronic components. In this paper, we present the first nonequilibrium molecular dynamics results to demonstrate that non-intrusive electropumping of liquid water on the nanoscale can be performed by subtly exploiting the coupling of spin angular momentum to linear streaming momentum. A spatially uniform rotating electric field is applied to water molecules, which couples to their permanent electric dipole moments. The resulting molecular rotational momentum is converted into linear streaming momentum of the fluid. By selectively tuning the degree of hydrophobicity of the solid walls one can generate a net unidirectional flow. Our results for the linear streaming and angular velocities of the confined water are in general agreement with the extended hydrodynamical theory for this process, though also suggest refinements to the theory are required. These numerical experiments confirm that this new concept for pumping of polar nanofluids can be employed under laboratory conditions, opening up significant new technological possibilities.

  13. Electropumping of water with rotating electric fields.

    PubMed

    De Luca, Sergio; Todd, B D; Hansen, J S; Daivis, Peter J

    2013-04-21

    Pumping of fluids confined to nanometer dimension spaces is a technically challenging yet vitally important technological application with far reaching consequences for lab-on-a-chip devices, biomimetic nanoscale reactors, nanoscale filtration devices and the like. All current pumping mechanisms require some sort of direct intrusion into the nanofluidic system, and involve mechanical or electronic components. In this paper, we present the first nonequilibrium molecular dynamics results to demonstrate that non-intrusive electropumping of liquid water on the nanoscale can be performed by subtly exploiting the coupling of spin angular momentum to linear streaming momentum. A spatially uniform rotating electric field is applied to water molecules, which couples to their permanent electric dipole moments. The resulting molecular rotational momentum is converted into linear streaming momentum of the fluid. By selectively tuning the degree of hydrophobicity of the solid walls one can generate a net unidirectional flow. Our results for the linear streaming and angular velocities of the confined water are in general agreement with the extended hydrodynamical theory for this process, though also suggest refinements to the theory are required. These numerical experiments confirm that this new concept for pumping of polar nanofluids can be employed under laboratory conditions, opening up significant new technological possibilities.

  14. Review Of Fiber-Optic Electric-Field Sensors

    NASA Technical Reports Server (NTRS)

    De Paula, Ramon P.; Jarzynski, Jacek

    1989-01-01

    Tutorial paper reviews state of art in fiber-optic sensors of alternating electric fields. Because such sensors are made entirely of dielectric materials, they are relatively transparent to incident electric fields; they do not distort fields significantly. Paper presents equations that express relationships among stress, strain, and electric field in piezoactive plastic and equations for phase shift in terms of photoelastic coefficients and strains in optical fiber.

  15. Effects of Nonconvective Electric Fields on Magnetospheric Plasma Dynamics.

    DTIC Science & Technology

    1983-01-31

    of Plasma and Electric Fields in the Magnetosphere, Yosemite , CA, 1982. 5. Silevitch, M.B., Excitation of Transient Double Layers and their Coupling to...Fields in Particle Data, Chapman Conference on High Latitude Electric Fields, Yosemite , CA, 1980, Paper 50. 20. M.B. Silevitch, E.C. Whipple Jr., and M.E...Greenspan, Temporal Behavior of Particle Fluxes Associated with Auroral Arcs, Chapman Conference on High Latitude Electric Fields, Yosemite , CA, 1980

  16. Electric field observations of equatorial bubbles

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Maynard, N. C.; Hanson, W. B.; Saba, Jack L.

    1992-01-01

    Results from the double floating probe experiment performed on the San Marco D satellite are presented, with emphasis on the observation of large incremental changes in the convective electric field vector at the boundary of equatorial plasma bubbles. Attention is given to isolated bubble structures in the upper ionospheric F regions; these observed bubble encounters are divided into two types - type I (live bubbles) and type II (dead bubbles). Type I bubbles show varying degrees of plasma depletion and large upward velocities range up to 1000 km/s. The geometry of these bubbles is such that the spacecraft orbit may cut them where they are tilting either eastward or (more often) westward. Type II bubbles exhibit plasma density depletion but no appreciable upward convection. Both types of events are usually surrounded by a halo of plasma turbulence, which can extend considerably beyond the region of plasma depletion.

  17. Electric field observations of equatorial bubbles

    NASA Astrophysics Data System (ADS)

    Aggson, T. L.; Maynard, N. C.; Hanson, W. B.; Saba, Jack L.

    1992-03-01

    Results from the double floating probe experiment performed on the San Marco D satellite are presented, with emphasis on the observation of large incremental changes in the convective electric field vector at the boundary of equatorial plasma bubbles. Attention is given to isolated bubble structures in the upper ionospheric F regions; these observed bubble encounters are divided into two types - type I (live bubbles) and type II (dead bubbles). Type I bubbles show varying degrees of plasma depletion and large upward velocities range up to 1000 km/s. The geometry of these bubbles is such that the spacecraft orbit may cut them where they are tilting either eastward or (more often) westward. Type II bubbles exhibit plasma density depletion but no appreciable upward convection. Both types of events are usually surrounded by a halo of plasma turbulence, which can extend considerably beyond the region of plasma depletion.

  18. Precise Patterning of Organic Single Crystals via Capillary-Assisted Alternating-Electric Field.

    PubMed

    Zhang, Yedong; Jie, Jiansheng; Sun, Yuning; Jeon, Seok-Gy; Zhang, Xiujuan; Dai, Gaole; Lee, Cheol Jin; Zhang, Xiaohong

    2017-07-01

    Owing to the extraordinary properties, organic micro/nanocrystals are important building blocks for future low-cost and high-performance organic electronic devices. However, integrated device application of the organic micro/nanocrystals is hampered by the difficulty in high-throughput, high-precision patterning of the micro/nanocrystals. In this study, the authors demonstrate, for the first time, a facile capillary-assisted alternating-electric field method for the large-scale assembling and patterning of both 0D and 1D organic crystals. These crystals can be precisely patterned at the photolithography defined holes/channels at the substrate with the yield up to 95% in 1 mm(2) . The mechanism of assembly kinetics is systematically studied by the electric field distribution simulation and experimental investigations. By using the strategy, various organic micro/nanocrystal patterns are obtained by simply altering the geometries of the photoresist patterns on substrates. Moreover, ultraviolet photodetectors based on the patterned Alq3 micro/nanocrystals exhibit visible-blind photoresponse with high sensitivity as well as excellent stability and reproducibility. This work paves the way toward high-integration, high-performance organic electronic, and optoelectronic devices from the organic micro/nanocrystals. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Catastrophic drop breakup in electric field.

    PubMed

    Raut, Janhavi S; Akella, Sathish; Singh, Amitkumar; Naik, Vijay M

    2009-05-05

    We report novel observations revealing the catastrophic breakup of water drops containing surfactant molecules, which are suspended in oil and subjected to an electric field of strength approximately 10(5) V/m. The observed breakup was distinctly different from the gradual end pinch-off or tip-streaming modes reported earlier in the literature. There was no observable characteristic deformation of the drop prior to breakup. The time scales involved in the breakup and the resultant droplet sizes were much smaller in the phenomenon observed by us. We hypothesize that this mode of drop breakup is obtained by the combined effect of an external electric field that imposes tensile stresses on the surface of the drop, and characteristic stress-strain behavior for tensile deformation exhibited by the liquid drop in the presence of a suitable surfactant, which not only lowers the interfacial tension (and hence the cohesive strength) of the drop but also simultaneously renders the interface nonductile or brittle at high enough concentration. We have identified the relevant thermodynamic parameter, viz., the sum of interfacial tension, sigma, and the Gibbs elasticity, epsilon, which plays a decisive role in determining the mode of drop breakup. The parameter (epsilon + sigma) represents the internal restoration stress of a liquid drop opposing rapid, short-time-scale perturbations or local deformations in the drop shape under the influence of external impulses or stresses. A thermodynamic "state" diagram of (epsilon + sigma) versus interfacial area per surfactant molecule adsorbed at the drop interface shows a "maximum" at a critical transition concentration (ctc). Below this concentration of the surfactant, the drop undergoes tip streaming or pinch off. Above this concentration, the drop may undergo catastrophic disintegration if the external stress is high enough to overcome the ultimate cohesive strength of the drop's interface.

  20. Electrically tunable sign of capacitance in planar W-doped vanadium dioxide micro-switches

    PubMed Central

    Soltani, Mohammed; Chaker, Mohamed; Margot, Joelle

    2011-01-01

    Negative capacitance (NC) in a planar W-doped VO2 micro-switch was observed at room temperature in the low-frequency range 1 kHz–10 MHz. The capacitance changed from positive to negative values as the W-doped VO2 active layer switched from semiconducting to metallic state under applied voltage. In addition, a capacitance–voltage hysteresis was observed as the applied voltage was cycled from −35 to 35 V. These observations suggest that NC results from the increase of the electrically induced conductivity in the active layer. This NC phenomenon could be exploited in advanced multifunctional devices including ultrafast switches, field-effect transistors and memcapacitive systems. PMID:27877421

  1. Sub-millimeter arbitrary arrangements of monolithically micro-scale electrical double layer capacitors

    NASA Astrophysics Data System (ADS)

    Laszczyk, Karolina U.; Kazufumi, Kobashi; Sakurai, Shunsuke; Sekiguchi, Atsuko; Futaba, Don N.; Yamada, Takeo; Hata, Kenji

    2015-12-01

    We report the investigation on the reproducibility of micro-scale electric double layer capacitors (micro-EDLCs). The micro-EDLC components were fabricated parallel using photolithography, wet and dry processing. Electrodes of the micro-EDLCs are highly dense packed Single Wall Carbon Nanotubes (SWCNTs) that form a mesh structure. The micro- EDLCs are connected 1-10 in series and in parallel being unified electrical circuits to tune the capacitance and the operational voltage. To confirm the reproducibility of the cells as well as the yield we performed electrochemical measurements in order to define the performance uniformity between cells strings and individual cells connected in a string. For 1-10 cells in series and in parallel the trends for the capacitance and operational voltage satisfied electrophysics rules governing cells addition. However, the measurements of the individual cells in a string revealed the significant performance discrepancy that might result in a shorten life cycling of a circuit.

  2. On intense diverging electric field associated with black aurora

    SciTech Connect

    Marklund, G.; Blomberg, L.; Faelthammar, C.G.; Lindqvist, P.A.

    1994-08-15

    The authors present measurements made from the double-probe electric field instrument on the Freja satellite of a very intense electric field event seen in the auroral oval. The electric field measurements are correlated with potential, charged particle, and wave activity measurements. They see two very narrow electric field events separated by approximately 5 km, having field strengths near 1 V/m. These structures are seen to be associated with an excess of positive charge, to be associated with no electron precipitation, with slight plasma depletions, and with wave activity. The authors suggest these structures are black aurorae, with a total absence of auroral emissions.

  3. Detection and learning of floral electric fields by bumblebees.

    PubMed

    Clarke, Dominic; Whitney, Heather; Sutton, Gregory; Robert, Daniel

    2013-04-05

    Insects use several senses to forage, detecting floral cues such as color, shape, pattern, and volatiles. We report a formerly unappreciated sensory modality in bumblebees (Bombus terrestris), detection of floral electric fields. These fields act as floral cues, which are affected by the visit of naturally charged bees. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also show that such electric field information contributes to the complex array of floral cues that together improve a pollinator's memory of floral rewards. Because floral electric fields can change within seconds, this sensory modality may facilitate rapid and dynamic communication between flowers and their pollinators.

  4. The influence of electric field and confinement on cell motility.

    PubMed

    Huang, Yu-Ja; Samorajski, Justin; Kreimer, Rachel; Searson, Peter C

    2013-01-01

    The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.

  5. The Influence of Electric Field and Confinement on Cell Motility

    PubMed Central

    Huang, Yu-Ja; Samorajski, Justin; Kreimer, Rachel; Searson, Peter C.

    2013-01-01

    The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D. PMID:23555674

  6. Measurements of the vertical atmospheric electric field and of the electrical conductivity with stratospheric balloons

    NASA Technical Reports Server (NTRS)

    Iversen, I. B.; Madsen, M. M.; Dangelo, N.

    1985-01-01

    Measurements of the atmospheric (vertical) electric field with balloons in the stratosphere are reported. The atmospheric electrical conductivity is also measured and the current density inferred. The average vertical current shows the expected variation with universal time and is also seen to be influenced by external (magnetospheric) electric fields.

  7. The Synergistic Effects of the Micro and Nano Particles in Micro-nano Composites on Enhancing the Resistance to Electrical Tree Degradation.

    PubMed

    Wang, Wenxuan; Yang, Ying

    2017-08-17

    A new method of increasing the durability and reliability of polymer dielectrics has been proposed by designing a composite structure of the micro and nano particles. The synergistic effects of the micro particles and nano particles are found to enhance the resistance to electrical tree and extend the lifetime of polymer dielectrics for insulations. Epoxy loaded with the micro and nano SiO2 particles at different concentrations are prepared as micro-nano composites. The micro particles show the blocking effects on the electrical tree channel and the interfaces of the nano particles lead to the inhibiting effects on the tree inception and propagation. The lifetime of the micro-nano composite samples in the experiments extends to 4 times of the neat epoxy. The new type of micro-nano composites can be widely applied in future electronic and electrical energy areas.

  8. Static electric field detection and behavioural avoidance in cockroaches.

    PubMed

    Newland, Philip L; Hunt, Edmund; Sharkh, Suleiman M; Hama, Noriyuki; Takahata, Masakazu; Jackson, Christopher W

    2008-12-01

    Electric fields are pervasively present in the environment and occur both as a result of man-made activities and through natural occurrence. We have analysed the behaviour of cockroaches to static electric fields and determined the physiological mechanisms that underlie their behavioural responses. The behaviour of animals in response to electric fields was tested using a Y-choice chamber with an electric field generated in one arm of the chamber. Locomotory behaviour and avoidance were affected by the magnitude of the electric fields with up to 85% of individuals avoiding the charged arm when the static electric field at the entrance to the arm was above 8-10 kV m(-1). Electric fields were found to cause a deflection of the antennae but when the antennae were surgically ablated, the ability of cockroaches to avoid electric fields was abolished. Fixation of various joints of the antennae indicated that hair plate sensory receptors at the base of the scape were primarily responsible for the detection of electric fields, and when antennal movements about the head-scape joint were prevented cockroaches failed to avoid electric fields. To overcome the technical problem of not being able to carry out electrophysiological analysis in the presence of electric fields, we developed a procedure using magnetic fields combined with the application of iron particles to the antennae to deflect the antennae and analyse the role of thoracic interneurones in signalling this deflection. The avoidance of electric fields in the context of high voltage power lines is discussed.

  9. Simultaneous measurement of nanoscale electric and magnetic optical fields

    NASA Astrophysics Data System (ADS)

    Le Feber, B.; Rotenberg, N.; Beggs, D. M.; Kuipers, L.

    2014-01-01

    Control of light-matter interactions at the nanoscale has advanced fields such as quantum optics, photovoltaics and telecommunications. These advances are driven by an improved understanding of the nanoscale behaviour of light, enabled by direct observations of the local electric fields near photonic nanostructures. With the advent of metamaterials that respond to the magnetic component of light, schemes have been developed to measure the nanoscale magnetic field. However, these structures interact not only with the magnetic field, but also with the electric field of light. Here, we demonstrate the essential simultaneous detection of both electric and magnetic fields with subwavelength resolution. By explaining our measurements through reciprocal considerations, we create a route towards designing probes sensitive to specific desired combinations of electric and magnetic field components. Simultaneous access to nanoscale electric and magnetic fields will pave the way for new designs of optical nanostructures and metamaterials.

  10. Studying electric field enhancement factor of the nanostructured emission surface

    NASA Astrophysics Data System (ADS)

    Zartdinov, A. N.; Nikiforov, K. A.

    2016-08-01

    Mathematical model of nanostructured field emission surface is proposed. In order to determine geometrical parameters of the surface structure digital processing of scanning electron microscopy images was used. Effective value of local electrical field enhancement factor is defined and calculated within the Fowler-Nordheim theory. It was found effective enhancement factor decreases as the applied electrical field increases for a fixed geometry.

  11. Spiking patterns of a hippocampus model in electric fields

    NASA Astrophysics Data System (ADS)

    Men, Cong; Wang, Jiang; Qin, Ying-Mei; Wei, Xi-Le; Che, Yan-Qiu; Deng, Bin

    2011-12-01

    We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective. Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study. The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity. It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field. Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude. These findings are qualitatively in accordance with the results of relevant experimental and numerical studies. It is implied that the external or endogenous electric field can modulate the neural code in the brain. Furthermore, it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy.

  12. Flow-driven cell migration under external electric fields

    PubMed Central

    Li, Yizeng; Mori, Yoichiro; Sun, Sean X.

    2016-01-01

    Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and can migrate toward a cathode or an anode, depending on the cell type. In this paper, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent. PMID:26765031

  13. Lattice vacancies in silicon film exposed to external electric field

    NASA Astrophysics Data System (ADS)

    Mao, Yuliang; Caliste, Damien; Pochet, Pascal

    2013-07-01

    Density functional calculations based on wavelet basis set are performed to investigate the structure, internal electric-charge distribution, and formation energy of lattice vacancies in silicon film under electric fields. It was found that the formation energies of vacancies both in JT⊥ (Jahn-Teller distortion orthogonal to electric field) and JT‖ (Jahn-Teller distortion parallel to electric field) distortions are decreased with the increasing of field strength, due to the charge polarization in the whole space of silicon film. For the split vacancy, it can lower its energy by moving further away from the split space to form a tetragonal JT⊥ vacancy under electric field. Our results also demonstrate the importance of the potential fluctuations induced by the electric fields on the charge redistribution within the vacancy defects.

  14. Flow-Driven Cell Migration under External Electric Fields

    NASA Astrophysics Data System (ADS)

    Li, Yizeng; Mori, Yoichiro; Sun, Sean X.

    2015-12-01

    Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and they can migrate toward a cathode or an anode, depending on the cell type. In this Letter, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent.

  15. Introduction to extremely-low-frequency electric and magnetic fields

    SciTech Connect

    Tenforde, T.S.

    1989-07-01

    The interaction with living systems of electromagnetic fields in the extremely-low-frequency (ELF) range below 300 Hz will be summarized briefly in this paper. In materials with the electrical and magnetic properties of living tissues, these fields have a long wavelength (5000 m) and skin depth (150 m). As a consequence, in their interactions with humans and other living organisms ELF fields behave as though they are composed of independent electric and magnetic components of an ELF field is commonly referred to as the quasi-static approximation,'' which permits the radiating properties of the field to be neglected in describing its interaction with living organisms. The electric and magnetic components of an ELF field have several distinctly different features in their interactions with humans and other living organisms. First, the electrical conductivity of tissue is approximately 14 to 15 orders of magnitude greater than that of air at ELF electric fields. Consequently, the body behaves like a good electrical conductor in ELF electric fields. As a result, an electrical charge is developed on the surface of a living object in an external ELF field, but the electric field penetrates into the body only to a very limited extent.

  16. Comparison Of Lightning Data From Electric Field Change And Electric Field Derivative Antennas

    NASA Astrophysics Data System (ADS)

    Bandara, S. A.; Marshall, T. C.; Karunarathne, S.; Karunarathne, N. D.; Siedlecki, R.; Stolzenburg, M.

    2016-12-01

    During the summer of 2016, we deployed an array of E-change sensors and electric field derivative sensors (dE/dt) in and around Oxford, Mississippi, USA. We use both E-change and dE/dt waveforms to determine the time-of-arrival locations of fast lightning events like initial breakdown pulses, narrow bipolar pulses, stepped leader pulses, and return strokes. The locations from two systems will be compared for each pulse category. Further, the pulses from dE/dt antennas will be digitally integrated and compared with the data from E-change sensors. We will discuss capabilities, advantages, and disadvantages of dE/dt waveforms over electric field change waveforms.

  17. The influence of process parameters for the inactivation of Listeria monocytogenes by pulsed electric fields.

    PubMed

    Alvarez, I; Pagán, R; Condón, S; Raso, J

    2003-10-15

    The influence of the electric field strength, the treatment time, the total specific energy and the conductivity of the treatment medium on the Listeria monocytogenes inactivation by pulsed electric fields (PEF) has been investigated. L. monocytogenes inactivation increased with the field strength, treatment time and specific energy. A maximum inactivation of 4.77 log(10) cycles was observed after a treatment of 28 kV/cm, 2000 micros and 3490 kJ/kg. The lethal effect of PEF treatments on L. monocytogenes was not influenced by the conductivity of the treatment medium in a range of 2, 3 and 4 mS/cm when the total specific energy was used as a PEF control parameter. A mathematical model based on the Weibull distribution was fitted to the experimental data when the field strength (15-28 kV/cm), treatment time (0-2000 micros) and specific energy (0-3490 kJ/kg) were used as PEF control parameters. A linear relationship was obtained between the log(10) of the scale factor (b) and the electric field strength when the treatment time and the total specific energy were used to control the process. The total specific energy, in addition to the electric field strength and the treatment time, should be reported in order to evaluate the microbial inactivation by PEF.

  18. Strong Peak Electric Field in Streamer Discharges Caused by Rapid Changes in the External Electric Field

    NASA Astrophysics Data System (ADS)

    Ihaddadene, K. M. A.; Celestin, S. J.

    2015-12-01

    Laboratory spark discharges in air and lightning stepped leaders produce X-rays [e.g., Dwyer et al., GRL, 32, L20809, 2005; Nguyen et al., J. Phys. D: Appl. Phys., 41, 234012, 2008; Rahman et al., GRL, 35, L06805, 2008; March and Montanyà, GRL, 37, L19801, 2010; 38, L04803, 2011; Kochkin et al., J. Phys. D: Appl., 45, 425202, 2012; 48, 025205, 2015]. However, the processes behind the production of these X-rays are still not fully understood. Recently, the encounter between negative and positive streamers has been suggested as a plausible mechanism for the production of X-rays by spark discharges [Cooray et al., JASTP, 71, 1890, 2009; Kochkin et al., J. Phys. D: Appl. Phys., 45, 425202, 2012], but the increase of the electric field involved in this process is accompanied by a strong increase of the conductivity, which in turn makes this electric field collapse over a few tens of picoseconds, preventing the production of significant X-ray emissions [Ihaddadene and Celestin, GRL, 45, 5644, 2015]. Moreover, it has been reported that X-ray emission in laboratory spark discharges is influenced by the time derivative of the applied voltage [March and Montanya, GRL, 37, L19801, 2010]. Additionally, Celestin and Pasko [JGR, 116, A03315, 2011, Section 3.3] have indicated that quickly increasing applied voltages had an impact on peak electric fields in streamer numerical models. In this work, we simulate numerically the effect of impulsive applied electric fields on the dynamics of streamer discharges in air at ground level and investigate conditions under which production of thermal runaway electrons and the associated X-rays is possible.

  19. Higgs mode in electric-field-induced superconductors

    NASA Astrophysics Data System (ADS)

    Koyama, Tomio

    2014-08-01

    We develop a theory for the Higgs (gap-amplitude) mode excitation in electric-field-induced (EFI) superconductors. The Higgs mode can be excited directly by an oscillating electric field in EFI superconductors since the gap value depends sensitively on the external electric field that induces superconducting carriers. The mass of the Higgs mode in EFI superconductors does not coincide with the threshold energy of pair-breaking two-particle excitations.

  20. Polarization tensor of a photon in an electric field

    NASA Astrophysics Data System (ADS)

    Katkov, V. M.

    2017-07-01

    The polarization operator is investigated at arbitrary photon energy in a constant and homogeneous electric field of the strength E. When the photon energy is less than the vacuum energy = eEℏ / mc , the found probability describes the absorption of a soft photon by virtual electron and positron in an electric field. At this energy, the main contribution to the probability gives the process of the absorption of a soft photon by real electron and positron produced by an electric field.

  1. Electric field induced bacterial flocculation of Enteroaggregative Escherichia coli 042

    SciTech Connect

    Kumar, Aloke; Mortensen, Ninell P; Mukherjee, Partha P; Retterer, Scott T; Doktycz, Mitchel John

    2011-01-01

    A response of the aggregation dynamics of enteroaggregative Escherichia coli under low magnitude steady and oscillating electric fields is presented. The presence of uniform electric fields hampered microbial adhesion and biofilm formation on a transverse glass surface, but instead promoted the formation of flocs. Extremely heterogeneous distribution of live and dead cells was observed among the flocs. Moreover, floc formation was largely observed to be independent of the frequency of alternating electric fields.

  2. Simulation of micro-magnet stray-field dynamics for spin qubit manipulation

    SciTech Connect

    Neumann, R.; Schreiber, L. R.

    2015-05-21

    High-fidelity control and unprecedented long dephasing times in silicon-based single spin qubits have recently confirmed the prospects of solid-state quantum computation. We investigate the feasibility of using a micro-magnet stray field for all-electrical, addressable spin qubit control in a Si/SiGe double quantum dot. For a micro-magnet geometry optimized for high Rabi-frequency, addressability, and robustness to fabrication misalignment as previously demonstrated by Yoneda et al. [Phys. Rev. Lett. 113, 267601 (2014)], we simulate the qubit decoherence due to magnetic stray-field fluctuations, which may dominate in nuclear spin-free systems, e.g., quantum dots in Si/SiGe, Si-MOS structures and (bilayer) graphene. With calculated Rabi-frequencies of 15 MHz, a qubit addressability error below 10{sup −3} is achievable. Magnetic fluctuations from a micro-magnet limits the spin relaxation time to T{sub 1} ≳ 3 s, while pure spin dephasing is negligible. Our results show that micro-magnets are a promising tool for spin qubit computation in nuclear spin-free systems.

  3. The interference threshold of cardiac pacemakers in electric 50 Hz fields.

    PubMed

    Scholten, A; Silny, J

    2001-01-01

    The aim of the study was to determine a 'worst-case' and a 'real-case' interference threshold for implanted cardiac pace-makers (CPM) in electric 50 Hz fields as they appear in high-voltage plants, e.g. beneath high voltage overhead lines. For this purpose the resulting electrical potential distribution within the thorax area of volunteers from an external homogeneous electrical 50 Hz field was measured. Different factors such as different body geometries as well as inspiration and expiration of the lung were considered. Measurements showed that 1 per 1 kV m(-1) unimpaired electrical field strength (RMS) an interference voltage of about 180 microVpp as real-case value an 400 microVpp as worst-case value would occur at the input of a unipolar ventricularly controlled, left pectorally implanted cardiac pacemaker. Therefore, it is possible under worst-case conditions but unlikely under practice-relevant conditions that an implanted cardiac pacemaker is disturbed by present electric 50 Hz fields beneath high voltage overhead lines.

  4. Electric field-controlled rippling of graphene

    NASA Astrophysics Data System (ADS)

    Osváth, Zoltán; Lefloch, François; Bouchiat, Vincent; Chapelier, Claude

    2013-10-01

    Metal-graphene interfaces generated by electrode deposition induce barriers or potential modulations influencing the electronic transport properties of graphene based devices. However, their impact on the local mechanical properties of graphene is much less studied. Here we show that graphene near a metallic interface can exhibit a set of ripples self-organized into domains whose topographic roughness is controlled by the tip bias of a scanning tunneling microscope. The reconstruction from topographic images of graphene bending energy maps sheds light on the local electro-mechanical response of graphene under STM imaging and unveils the role of the stress induced by the vicinity of the graphene-metal interface in the formation and the manipulation of these ripples. Since microscopic rippling is one of the important factors that limit charge carrier mobility in graphene, the control of rippling with a gate voltage may have important consequences in the conductance of graphene devices where transverse electric fields are created by contactless suspended gate electrodes. This opens up also the possibility to dynamically control the local morphology of graphene nanomembranes.Metal-graphene interfaces generated by electrode deposition induce barriers or potential modulations influencing the electronic transport properties of graphene based devices. However, their impact on the local mechanical properties of graphene is much less studied. Here we show that graphene near a metallic interface can exhibit a set of ripples self-organized into domains whose topographic roughness is controlled by the tip bias of a scanning tunneling microscope. The reconstruction from topographic images of graphene bending energy maps sheds light on the local electro-mechanical response of graphene under STM imaging and unveils the role of the stress induced by the vicinity of the graphene-metal interface in the formation and the manipulation of these ripples. Since microscopic rippling is one

  5. Linear electric field time-of-flight ion mass spectrometer

    DOEpatents

    Funsten, Herbert O.; Feldman, William C.

    2008-06-10

    A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.

  6. Electric field effects on electronic characteristics of arsenene nanoribbons

    NASA Astrophysics Data System (ADS)

    Luo, Yanwei; Li, Yuxiao; Wang, Fei; Guo, Peng; Jia, Yu

    2017-10-01

    By using the first-principles calculations, we investigate the effects of electric field on electronic structures of armchair and zigzag arsenene nanoribbons (AsNRs) with different widths. The results show that for each case, quantum size effects induce a smaller band gap in larger AsNRs. Moreover, electric field can reduce effectively the band gap of AsNRs. In addition, the electric field can induce only the transition of band structures in the A-AsNRs or Z-AsNRs with narrow size. The band gap decrease more rapidly and the threshold electric field induced metal becomes smaller in the wider AsNRs.

  7. Neoclassical Radial Electric Field and Transport with Finite Orbits

    SciTech Connect

    Wang, W. X.; Hinton, F. L.; Wong, S. K.

    2001-07-30

    Neoclassical transport in a toroidal plasma with finite ion orbits is studied, including for the first time the self-consistent radial electric field. Using a low-noise {delta}f particle simulation, we demonstrate that a deep electric-field well develops in a region with a steep density gradient, because of the self-collision--driven ion flux. We find that the electric field agrees with the standard neoclassical expression, when the toroidal rotation is zero, even for a steep density gradient. Ion thermal transport is modified by the electric-field well in a way which is consistent with the orbit squeezing effect, but smoothed by the finite orbits.

  8. Double-sensor method for detection of oscillating electric field.

    PubMed

    Ohkuma, Yasunori; Ikeyama, Taeko; Nogi, Yasuyuki

    2011-04-01

    An electric-field sensor consisting of thin copper plates is designed to measure an oscillating electric field produced by charge separations on a plasma column. The sensor installed in a vacuum region around plasma detects charges induced by the electric field on the copper plates. The value of the induced charges depends not only on the strength of the electric field, but also on the design of the sensor. To obtain the correct strength of the electric field, a correction factor arising from the design of the sensor must be known. The factor is calculated numerically using Laplace's equation and compared with a value measured using a uniform electric field in the frequency range of 10-500 kHz. When an external circuit is connected to the sensor to measure the induced charges, the electric field around the sensor is disturbed. Therefore, a double-sensor method for excluding a disturbed component in the measured electric field is proposed. The reliability of the double-sensor method is confirmed by measuring dipole-like and quadrupole-like electric fields. © 2011 American Institute of Physics

  9. Spectral studies of the sources of ionospheric electric fields

    NASA Technical Reports Server (NTRS)

    Earle, G. D.; Kelley, M. C.

    1987-01-01

    Spectral analyses (applying the Fourier analysis methods) were performed on three incoherent scatter radar data sets (obtained at Jicamarca, Peru; Chatanika, Alaska; and Arecibo, Puerto Rico) with the aim of investigating the origin of ionospheric electric fields in the frequency range of 0.01-2 cycles/h. In quiet times, atmospheric gravity waves appeared to be the most likely source of the ionospheric electric field. This hypothesis was tested by a direct simultaneous comparison of measurements of gravity waves in the mesosphere and of electric fields in the thermosphere during very quiet conditions. The results indicated that a gravity wave source is a plausible candidate for the electric field fluctuations.

  10. Measuring electric fields from surface contaminants with neutral atoms

    SciTech Connect

    Obrecht, J. M.; Wild, R. J.; Cornell, E. A.

    2007-06-15

    In this paper we demonstrate a technique of utilizing magnetically trapped neutral {sup 87}Rb atoms to measure the magnitude and direction of stray electric fields emanating from surface contaminants. We apply an alternating external electric field that adds to (or subtracts from) the stray field in such a way as to resonantly drive the trapped atoms into a mechanical dipole oscillation. The growth rate of the oscillation's amplitude provides information about the magnitude and sign of the stray field gradient. Using this measurement technique, we are able to reconstruct the vector electric field produced by surface contaminants. In addition, we can accurately measure the electric fields generated from adsorbed atoms purposely placed onto the surface and account for their systematic effects, which can plague a precision surface-force measurement. We show that baking the substrate can reduce the electric fields emanating from adsorbate and that the mechanism for reduction is likely surface diffusion, not desorption.

  11. Extracting nucleon magnetic moments and electric polarizabilities from lattice QCD in background electric fields

    SciTech Connect

    Detmold, W.; Tiburzi, B. C.; Walker-Loud, A.

    2010-03-01

    Nucleon properties are investigated in background electric fields. As the magnetic moments of baryons affect their relativistic propagation in constant electric fields, electric polarizabilities cannot be determined without knowledge of magnetic moments. This is analogous to the experimental situation, for which determination of polarizabilities from the Compton amplitude requires subtraction of Born terms. With the background field method, we devise combinations of nucleon correlation functions in constant electric fields that isolate magnetic moments and electric polarizabilities. Using an ensemble of anisotropic gauge configurations with dynamical clover fermions, we demonstrate how both observables can be determined from lattice QCD simulations in background electric fields. We obtain results for the neutron and proton, however, our study is currently limited to electrically neutral sea quarks. The value we extract for the nucleon isovector magnetic moment is comparable to those obtained from measuring lattice three-point functions at similar pion masses.

  12. Pulsed electric field assisted assembly of polyaniline

    NASA Astrophysics Data System (ADS)

    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.

  13. Pulsed electric field assisted assembly of polyaniline.

    PubMed

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

    2012-08-24

    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.

  14. Electric Field Driven Torque in ATP Synthase

    PubMed Central

    Miller, John H.; Rajapakshe, Kimal I.; Infante, Hans L.; Claycomb, James R.

    2013-01-01

    FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring. PMID:24040370

  15. Electric field driven torque in ATP synthase.

    PubMed

    Miller, John H; Rajapakshe, Kimal I; Infante, Hans L; Claycomb, James R

    2013-01-01

    FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring.

  16. Electric field-controlled rippling of graphene.

    PubMed

    Osváth, Zoltán; Lefloch, François; Bouchiat, Vincent; Chapelier, Claude

    2013-11-21

    Metal-graphene interfaces generated by electrode deposition induce barriers or potential modulations influencing the electronic transport properties of graphene based devices. However, their impact on the local mechanical properties of graphene is much less studied. Here we show that graphene near a metallic interface can exhibit a set of ripples self-organized into domains whose topographic roughness is controlled by the tip bias of a scanning tunneling microscope. The reconstruction from topographic images of graphene bending energy maps sheds light on the local electro-mechanical response of graphene under STM imaging and unveils the role of the stress induced by the vicinity of the graphene-metal interface in the formation and the manipulation of these ripples. Since microscopic rippling is one of the important factors that limit charge carrier mobility in graphene, the control of rippling with a gate voltage may have important consequences in the conductance of graphene devices where transverse electric fields are created by contactless suspended gate electrodes. This opens up also the possibility to dynamically control the local morphology of graphene nanomembranes.

  17. Electric Field and Density Measurements with STEREO-SWaves.

    NASA Astrophysics Data System (ADS)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.; Bale, S. D.; Maksimovic, M.

    2007-12-01

    The STEREO experiment SWaves has a low frequency part which is designed to make measurements of low frequency electric fields and rapid measurements of density fluctuations, using the three 6 meter stacer monopole antennas. The short antennas of STEREO respond both to density fluctuations and to electric fields. Therefore, it is desired to obtain four quantities, density and 3 components of electric field, from three measurements, the potentials on the three orthogonal antennas relative to the spacecraft, which requires some additional information. One possibility is to add a fourth equation implied by the large plasma conductivity, so large that electric field parallel to the magnetic field is zero, a condition which has often been used in electric field measurements. Under selected conditions, this seems to work. There are also conditions, for example ion acoustic waves, where the responses to density fluctuations and to electric fields are available from dispersion relations, and this provides another possible solution. A situation where it is not likely that the parallel electric field is zero is the case of solitary, intense bursts of Langmuir waves. For this case, it is expected that there is an electron density depression due to the ponderomotive pressure, and a resulting low frequency electric field from the non-neutrality which would be expected to have components parallel to the magnetic field. Examples will be discussed.

  18. Surface electric fields for North America during historical geomagnetic storms

    USGS Publications Warehouse

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  19. Surface electric fields for North America during historical geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Wei, Lisa H.; Homeier, Nicole; Gannon, Jennifer L.

    2013-08-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 "Quebec" storm and the 2003 "Halloween" storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  20. Temperature Modulation of Electric Fields in Biological Matter

    PubMed Central

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

    Pulsed electric fields (PEF) have become an important minimally invasive surgical technology for various applications including genetic engineering, electrochemotherapy and tissue ablation. This study explores the hypothesis that temperature dependent electrical parameters of tissue can be used to modulate the outcome of PEF protocols, providing a new means for controlling and optimizing this minimally invasive surgical procedure. This study investigates two different applications of cooling temperatures applied during PEF. The first case utilizes an electrode which simultaneously delivers pulsed electric fields and cooling temperatures. The subsequent results demonstrate that changes in electrical properties due to temperature produced by this configuration can substantially magnify and confine the electric fields in the cooled regions while almost eliminating electric fields in surrounding regions. This method can be used to increase precision in the PEF procedure, and eliminate muscle contractions and damage to adjacent tissues. The second configuration considered introduces a third probe that is not electrically active and only applies cooling boundary conditions. This second study demonstrates that in this probe configuration the temperature induced changes in electrical properties of tissue substantially reduce the electric fields in the cooled regions. This novel treatment can potentially be used to protect sensitive tissues from the effect of the PEF. Perhaps the most important conclusion of this investigation is that temperature is a powerful and accessible mechanism to modulate and control electric fields in biological tissues and can therefore be used to optimize and control PEF treatments. PMID:21695144

  1. High-frequency electric field measurement using a toroidal antenna

    DOEpatents

    Lee, Ki Ha

    2002-01-01

    A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

  2. Electric-field-driven switching of individual magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Hsu, Pin-Jui; Kubetzka, André; Finco, Aurore; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland

    2017-02-01

    Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices. The present magnetic information technology is mainly based on writing processes requiring either local magnetic fields or spin torques, but it has also been demonstrated that magnetic properties can be altered on the application of electric fields. This has been ascribed to changes in magnetocrystalline anisotropy caused by spin-dependent screening and modifications of the band structure, changes in atom positions or differences in hybridization with an adjacent oxide layer. However, the switching between states related by time reversal, for example magnetization up and down as used in the present technology, is not straightforward because the electric field does not break time-reversal symmetry. Several workarounds have been applied to toggle between bistable magnetic states with electric fields, including changes of material composition as a result of electric fields. Here we demonstrate that local electric fields can be used to switch reversibly between a magnetic skyrmion and the ferromagnetic state. These two states are topologically inequivalent, and we find that the direction of the electric field directly determines the final state. This observation establishes the possibility to combine electric-field writing with the recently envisaged skyrmion racetrack-type memories.

  3. Inner Magnetospheric Electric Fields Derived from IMAGE EUV

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Adrian, M. L.

    2007-01-01

    The local and global patterns of plasmaspheric plasma transport reflect the influence of electric fields imposed by all sources in the inner magnetosphere. Image sequences of thermal plasma G:istribution obtained from the IMAGE Mission Extreme Ultraviolet Imager can be used to derive plasma motions and, using a magnetic field model, the corresponding electric fields. These motions and fields directly reflect the dynamic coupling of injected plasmasheet plasma and the ionosphere, in addition to solar wind and atmospheric drivers. What is being learned about the morphology of inner magnetospheric electric fields during storm and quite conditions from this new empirical tool will be presented and discussed.

  4. Nanoscale Electric Field Sensor-Development and Testing

    NASA Astrophysics Data System (ADS)

    Brame, Jon; Woods, Nathan

    2008-10-01

    The goal of this project is to test a carbon nanotube based electric field sensing device. The device consists of a miniature gold needle suspended on a mat of carbon nanotubes over a trench on a Si/Si02 substrate. Field tests were made by recording the electric field inside dust devils in a Nevada desert, and those electric fields were simulated in a lab environment. Further tests to determine the device sensitivity were performed by manually manipulating the gold needle with an Atomic Force Microscope (AFM) tip. We report on fabrication techniques, field and lab test results and AFM testing results.

  5. Simultaneous electric-field measurements on nearby balloons.

    NASA Technical Reports Server (NTRS)

    Mozer, F. S.

    1972-01-01

    Electric-field payloads were flown simultaneously on two balloons from Great Whale River, Canada, on September 21, 1971, to provide data at two points in the upper atmosphere that differed in altitude by more than one atmospheric density scale height and in horizontal position by 30-140 km. The altitude dependences in the two sets of data prove conclusively that the vertical electric field at balloon altitudes stems from fair-weather atmospheric electricity sources and that the horizontal fields are mapped down ionospheric fields, since the weather-associated horizontal fields were smaller than 2 mV/m.

  6. Reception and learning of electric fields in bees

    PubMed Central

    Greggers, Uwe; Koch, Gesche; Schmidt, Viola; Dürr, Aron; Floriou-Servou, Amalia; Piepenbrock, David; Göpfert, Martin C.; Menzel, Randolf

    2013-01-01

    Honeybees, like other insects, accumulate electric charge in flight, and when their body parts are moved or rubbed together. We report that bees emit constant and modulated electric fields when flying, landing, walking and during the waggle dance. The electric fields emitted by dancing bees consist of low- and high-frequency components. Both components induce passive antennal movements in stationary bees according to Coulomb's law. Bees learn both the constant and the modulated electric field components in the context of appetitive proboscis extension response conditioning. Using this paradigm, we identify mechanoreceptors in both joints of the antennae as sensors. Other mechanoreceptors on the bee body are potentially involved but are less sensitive. Using laser vibrometry, we show that the electrically charged flagellum is moved by constant and modulated electric fields and more strongly so if sound and electric fields interact. Recordings from axons of the Johnston organ document its sensitivity to electric field stimuli. Our analyses identify electric fields emanating from the surface charge of bees as stimuli for mechanoreceptors, and as biologically relevant stimuli, which may play a role in social communication. PMID:23536603

  7. Module Embedded Micro-inverter Smart Grid Ready Residential Solar Electric System

    SciTech Connect

    Agamy, Mohammed

    2015-10-27

    The “Module Embedded Micro-inverter Smart Grid Ready Residential Solar Electric System” program is focused on developing innovative concepts for residential photovoltaic (PV) systems with the following objectives: to create an Innovative micro-inverter topology that reduces the cost from the best in class micro-inverter and provides high efficiency (>96% CEC - California Energy Commission), and 25+ year warranty, as well as reactive power support; integrate micro-inverter and PV module to reduce system price by at least $0.25/W through a) accentuating dual use of the module metal frame as a large area heat spreader reducing operating temperature, and b) eliminating redundant wiring and connectors; and create micro-inverter controller handles smart grid and safety functions to simplify implementation and reduce cost.

  8. Electrical equivalent circuit for microstrip micro-plasma: control of EM propagation and numerical simulations.

    PubMed

    Mohamad, Almustafa; Tân-Hoa, Vuong; Jacques, David

    2012-01-01

    An approach to determine an equivalent electrical circuit of a micro planar discharge on a microstrip printed circuit is reported. The micro discharge is used to realize a dynamic microwave switching circuit. This approach is based on the measurement of the discharge current and the transmission coefficient for a given frequency 2.45 GHz. Numerical methods like FEM can be used to study the effect of plasma parameters on the propagation of electromagnetic waves through a microstrip printed circuit. Plasma behaves as flexible elements that can change its electrical proprieties such as conductivity.

  9. Rocket borne instrument to measure electric fields inside electrified clouds

    NASA Technical Reports Server (NTRS)

    Ruhnke, L. H. (Inventor)

    1973-01-01

    An apparatus for measuring the electric field in the atmosphere which includes a pair of sensors carried on a rocket for sensing the voltages in the atmosphere being measured is described. One of the sensors is an elongated probe with a fine point which causes a corona current to be produced as it passes through the electric field. An electric circuit is coupled between the probe and the other sensor and includes a high ohm resistor which linearizes the relationship between the corona current and the electric field being measured. A relaxation oscillator and transmitter are provided for generating and transmitting an electric signal having a frequency corresponding to the magnitude of the electric field.

  10. Electrical Field Effects in Phthalocyanine Film Growth by Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Banks, Curtis E.; Zhu, Shen; Frazier, Donald O.; Penn, Benjamin; Abdeldayem, Hossin; Hicks, Roslin; Sarkisov, Sergey

    1999-01-01

    Phthalocyanine, an organic material, is a very good candidate for non-linear optical application, such as high-speed switching and optical storage devices. Phthalocyanine films have been synthesized by vapor deposition on quartz substrates. Some substrates were coated with a very thin gold film for introducing electrical field. These films have been characterized by surface morphology, material structure, chemical and thermal stability, non-linear optical parameters, and electrical behaviors. The films have excellent chemical and optical stability. However, the surface of these films grown without electrical field shows flower-like morphology. When films are deposited under an electrical field ( an aligned structure is revealed on the surface. A comparison of the optical and electrical properties and the growth mechanism for these films grown with and without an electrical field will be discussed.

  11. Electric Field-Driven Assembly of Sulfonated Polystyrene Microspheres

    PubMed Central

    Mikkelsen, Alexander; Wojciechowski, Jarosław; Rajňák, Michal; Kurimský, Juraj; Khobaib, Khobaib; Kertmen, Ahmet; Rozynek, Zbigniew

    2017-01-01

    A designed assembly of particles at liquid interfaces offers many advantages for development of materials, and can be performed by various means. Electric fields provide a flexible method for structuring particles on drops, utilizing electrohydrodynamic circulation flows, and dielectrophoretic and electrophoretic interactions. In addition to the properties of the applied electric field, the manipulation of particles often depends on the intrinsic properties of the particles to be assembled. Here, we present an easy approach for producing polystyrene microparticles with different electrical properties. These particles are used for investigations into electric field-guided particle assembly in the bulk and on surfaces of oil droplets. By sulfonating polystyrene particles, we produce a set of particles with a range of dielectric constants and electrical conductivities, related to the sulfonation reaction time. The paper presents diverse particle behavior driven by electric fields, including particle assembly at different droplet locations, particle chaining, and the formation of ribbon-like structures with anisotropic properties. PMID:28772690

  12. Disrupting long-range polar order with an electric field

    NASA Astrophysics Data System (ADS)

    Guo, Hanzheng; Liu, Xiaoming; Xue, Fei; Chen, Long-Qing; Hong, Wei; Tan, Xiaoli

    2016-05-01

    Electric fields are known to favor long-range polar order through the aligning of electric dipoles in relation to Coulomb's force. Therefore, it would be surprising to observe a disordered polar state induced from an ordered state by electric fields. Here we show such an unusual phenomenon in a polycrystalline oxide where electric fields induce a ferroelectric-to-relaxor phase transition. The nonergodic relaxor phase with disordered dipoles appears as an intermediate state under electric fields during polarization reversal of the ferroelectric phase. Using the phenomenological theory, the underlying mechanism for this unexpected behavior can be attributed to the slow kinetics of the ferroelectric-to-relaxor phase transition, as well as its competition against domain switching during electric reversal. The demonstrated material could also serve as a model system to study the transient stages in first-order phase transitions; the slow kinetics does not require the use of sophisticated ultrafast tools.

  13. Fetal exposure to low frequency electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Cech, R.; Leitgeb, N.; Pediaditis, M.

    2007-02-01

    To investigate the interaction of low frequency electric and magnetic fields with pregnant women and in particular with the fetus, an anatomical voxel model of an 89 kg woman at week 30 of pregnancy was developed. Intracorporal electric current density distributions due to exposure to homogeneous 50 Hz electric and magnetic fields were calculated and results were compared with basic restrictions recommended by ICNIRP guidelines. It could be shown that the basic restriction is met within the central nervous system (CNS) of the mother at exposure to reference level of either electric or magnetic fields. However, within the fetus the basic restriction is considerably exceeded. Revision of reference levels might be necessary.

  14. Dipole Relaxation in an Electric Field.

    ERIC Educational Resources Information Center

    Neumann, Richard M.

    1980-01-01

    Derives an expression for the orientational entropy of a rigid rod (electric dipole) from Boltzmann's equation. Subsequent application of Newton's second law of motion produces Debye's classical expression for the relaxation of an electric dipole in a viscous medium. (Author/GS)

  15. Dipole Relaxation in an Electric Field.

    ERIC Educational Resources Information Center

    Neumann, Richard M.

    1980-01-01

    Derives an expression for the orientational entropy of a rigid rod (electric dipole) from Boltzmann's equation. Subsequent application of Newton's second law of motion produces Debye's classical expression for the relaxation of an electric dipole in a viscous medium. (Author/GS)

  16. Manipulating spatial light fields for micro- and nano-photonics

    NASA Astrophysics Data System (ADS)

    Xie, Xiangsheng; Liu, Yikun; Zhang, Mudong; Zhou, Jianying; Wong, Kam Sing

    2012-04-01

    Spatial properties of a light field, including its amplitude, polarization and phase distribution, can be modulated via spatial light modulators, digital mirror devices, optical mask, waveplates or diffraction optic elements. In conjunction with additional optical components, e.g., optical lenses or imaging systems, rich micro- and nano-photonic applications can be demonstrated. This paper reviews various useful techniques applied for the spatial light field modulations. Important applications, most notably, optical lithography for the fabrication of functional photonic crystals, and light field conversion and transmission through material system, are discussed. Key issues in the control of optical field, including phase-locking, phase distribution regulation and adaptive optical field synthesizing, are described in detail. The applications of light field modulation to enhance light-matter interaction are demonstrated for some fundamental optical processes, such as light diffraction in liquid crystal, beam combining in nonlinear optical crystal and light field transmission through a tapered nano-tip. It is anticipated that the wide-spread application of light field modulation be expected in the near future, especially in view of a rapid advancement in the nano-photonic research and applications.

  17. Middle atmospheric electric fields over thunderstorms

    NASA Technical Reports Server (NTRS)

    Holzworth, Robert H.

    1992-01-01

    This grant has supported a variety of investigations all having to do with the external electrodynamics of thunderstorms. The grant was a continuation of work begun while the PI was at the Aerospace Corporation (under NASA Grant NAS6-3109) and the general line of investigation continues today under NASA Grants NAG5-685 and NAG6-111. This report will briefly identify the subject areas of the research and associated results. The period actually covered by the grant NAG5-604 included the following analysis and flights: (1) analysis of five successful balloon flights in 1980 and 1981 (under the predecessor NASA grant) in the stratosphere over thunderstorms; (2) development and flight of the Hy-wire tethered balloon system for direct measurement of the atmospheric potential to 250 kV (this involved multiple tethered balloon flight periods from 1981 through 1986 from several locations including Wallops Island, VA, Poker Flat and Ft. Greely, AK and Holloman AFB, NM.); (3) balloon flights in the stratosphere over thunderstorms to measure vector electric fields and associated parameters in 1986 (2 flights), 1987 (4 flights), and 1988 (2 flights); and (4) rocket-borne optical lightning flash detectors on two rocket flights (1987 and 1988) (the same detector design that was used for the balloon flights listed under #3). In summary this grant supported 8 stratospheric zero-pressure balloon flights, tethered aerostat flights every year between 1982-1985, instruments on 2 rockets, and analysis of data from 6 stratospheric flights in 1980/81.

  18. Parallel electric field in flux restoration during ultrafiltration

    SciTech Connect

    Silva, M.; Zaniquelli, M.E.D. ); Galembeck, F. )

    1991-01-01

    Ultrafiltration membrane permeability may be restored by applying an electric field parallel to the plane of the membrane in the feed compartment of ultrafiltration cells. Two different electrode arrangements are described. Under some conditions, flux restoration is complete. An electric field parallel to the membrane can thus be used to eliminate membrane polarization and fouling.

  19. Electric and Magnetic Fields | RadTown USA | US EPA

    EPA Pesticide Factsheets

    2016-05-31

    Electromagnetic fields (EMF) are a combination of electric and magnetic fields of energy that surround any electrical device when it is plugged in and turned on. Scientific experiments have not clearly shown whether or not exposure to EMF increases cancer risk. Scientists continue to study the issue.

  20. High School Students' Representations and Understandings of Electric Fields

    ERIC Educational Resources Information Center

    Cao, Ying; Brizuela, Bárbara M.

    2016-01-01

    This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields post-instruction as indicated by students'…

  1. High School Students' Representations and Understandings of Electric Fields

    ERIC Educational Resources Information Center

    Cao, Ying; Brizuela, Bárbara M.

    2016-01-01

    This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields post-instruction as indicated by students'…

  2. Photodetachment dynamics in a time-dependent oscillating electric field

    NASA Astrophysics Data System (ADS)

    Wang, De-hua; Xu, Qin-feng; Du, Jie

    2017-03-01

    Using the time-dependent form of closed orbit theory, as developed by Haggerty and Delos [M.R. Haggerty, J.B. Delos, Phys. Rev. A 61, 053406 (2000)], and by Yang and Robicheaux [B.C. Yang, F. Robicheaux, Phys. Rev. A 93, 053413 (2016)], we study the photodetachment dynamics of a hydrogen negative ion in a time-dependent oscillating electric field. Compared to the photodetachment in a static electric field, the photodetachment dynamics of a negative ion in the time-dependent oscillating electric field become much more complicated but more interesting. Since the applied electric field is oscillating with time, the photodetachment cross section of the negative ion in the oscillating electric field is time-dependent. In a time-dependent framework, we put forward an analytical formula for calculating the instantaneous photodetachment cross section of this system. Our study suggests that the instantaneous photodetachment cross section exhibits oscillatory structure, which depends sensitively on the frequency of the oscillating electric field. With increasing frequency of the oscillating electric field, the number of closed orbits increases and the oscillatory structure in the photodetachment cross section becomes much more complicated. The connection between the detached electron's closed orbit with the oscillating cross section is analyzed quantitatively. This study provides a clear and intuitive picture for the photodetachment processes of a negative ion in the presence of an oscillating electric field. We hope that our work will be useful in guiding future experimental research.

  3. Electric and Magnetic Field Detection in Elasmobranch Fishes

    NASA Astrophysics Data System (ADS)

    Kalmijn, Ad. J.

    1982-11-01

    Sharks, skates, and rays receive electrical information about the positions of their prey, the drift of ocean currents, and their magnetic compass headings. At sea, dogfish and blue sharks were observed to execute apparent feeding responses to dipole electric fields designed to mimic prey. In training experiments, stingrays showed the ability to orient relative to uniform electric fields similar to those produced by ocean currents. Voltage gradients of only 5 nanovolts per centimeter would elicit either behavior.

  4. Exploiting Electric and Magnetic Fields for Underwater Characterization

    DTIC Science & Technology

    2011-03-01

    numerical models in order to quantify the practical limits on standoff excitation for induction coil (magnetic dipole) and electrode (electric dipole...commercially available electric (Ag/AgCl electrodes) and magnetic (wideband induction coil B-field sensors) receivers formed an initial testbed for...improved performance using an electric field source rather than marinized versions of terrestrial induction coil sources (e.g., EM-61S).  Interaction with

  5. Nonlinear piezoelectricity in epitaxial ferroelectrics at high electric fields

    SciTech Connect

    Grigoriev, Alexei; Sichel, Rebecca; Lee, Ho Nyung; Landahl, Eric C.; Adams, Bernhard; Dufresne, Eric M.; Evans, Paul G.

    2008-01-01

    Non-linear effects in the coupling of polarization with elastic strain have been predicted to occur in ferroelectric materials subjected to high electric fields. Such predictions are tested here for a Pb(Zr0.2,Ti0.8)O3 ferroelectric thin film at electric fields in the range of several MV/cm. Thermal runaway and subsequent low-frequency dielectric breakdown are overcome by using nanosecond electrical pulses to apply high electric fields, which made the probing of the film's structure possible at piezoelectric strains reaching up to 2.7%. The piezoelectric strain exceeds predictions based on constant piezoelectric coefficients at electric fields from 2 to 4 MV/cm, which is consistent with a non-linear effect predicted to occur at concomitant piezoelectric distortions. At higher fields, the piezoelectric response decreases, suggesting that elastic interactions between atoms enter a new regime.

  6. Sources of Low-latitude Ionospheric Electric-field Disturbances

    NASA Astrophysics Data System (ADS)

    Richmond, A. D.; Peymirat, C.

    2001-12-01

    Storm-time ionospheric electric-field disturbances at middle and low latitudes are generated both by direct magnetosphere-ionosphere interactions at high latitudes and by secondary effects of disturbance thermospheric winds. These disturbance electric fields can have a strong influence on the equatorial ionosphere. Using the NCAR Magnetosphere-Thermosphere-Ionosphere-Electrodynamics General Circulation Model (MTIEGCM), we simulate low-latitude electric-field disturbances associated with direct penetration from high latitudes and with secondary generation by disturbed thermospheric winds. The simulations display a number of features observed in equatorial electric fields on time scales of minutes to hours. Models like the MTIEGCM, together with simultaneous global observations of ionospheric electric fields and thermospheric winds, can help clarify the relative importance of the different mechanisms that produce ionospheric disturbances.

  7. Lamb-shift and electric field measurements in plasmas

    NASA Astrophysics Data System (ADS)

    Doveil, F.; Chérigier-Kovacic, L.; Ström, P.

    2017-01-01

    The electric field is a quantity of particular relevance in plasma physics. Indeed, its fluctuations are responsible for different macroscopic phenomena such as anomalous transport in fusion plasmas. Answering a long-standing challenge, we offer a new method to locally and non-intrusively measure weak electric fields and their fluctuations in plasmas, by means of a beam of hydrogen ions or atoms. We present measurements of the electric field in vacuum and in a plasma where Debye shielding is measured. For the first time, we have used the Lamb-shift resonance to measure oscillating electric fields around 1 GHz and observed the strong enhancement of the Lyman-α signal. The measurement is both direct and non-intrusive. This method provides sensitivity (mV cm-1) and temporal resolution (ns) that are three orders higher compared to current diagnostics. It thus allows measuring fluctuations of the electric field at scales not previously reached experimentally.

  8. Time domain response of electrical ceramics -- Micro to megaseconds

    SciTech Connect

    Modine, F.A.

    1997-11-01

    The electrical properties of ceramics can be measured in either the time domain or in the frequency domain. But for electrically nonlinear ceramics such as varistors, time-domain measurements provide insights that are different and more relevant to material performance as well as being more physically incisive. This article focuses specifically on the electrical properties of ZnO varistors, but much of it is of relevance for other materials, in particular those materials with grain-boundary barriers and disordered ceramics or glasses. The interpretation of electrical measurements in the time domain is profoundly influenced by such practical matters as source impedance and waveform characteristics. Experimental results are presented for both high and low source impedance relative to that of a test varistor, and the different in experimental difficulty and ease of interpretation is described. Time-domain measurements of capacitance and of the inductive response of varistors to large, fast electrical pulses are presented and their implications for varistor theory are given. Experimental evidence is given of short- and long-term memory in varistors. These memory phenomena are ascribed respectively to the life time of holes that become trapped in barriers and to polarization currents originating from deep electron traps. Polarization current measurements are presented for a wide range of time and temperature. The power-law time dependence and universal behavior of these currents is discussed. The exponent that describes the power law behavior is seen to change with temperature, and the change is interpreted as a double transition from diffusive to dispersive transport that originates with current from two different electron traps.

  9. AC electric field controlled non-Newtonian filament thinning and droplet formation on the microscale.

    PubMed

    Huang, Y; Wang, Y L; Wong, T N

    2017-08-22

    formation under the influence of an AC electric field, assisted by a high-speed micro particle imaging velocimetry (μPIV) system. The flow field distributions obtained using the correlation algorithm show that the electric field generated Maxwell stress deforms the interface, changes the flow recirculation pattern, stimulates the instability and hence reduces the size of the non-Newtonian droplet. Finally, we analyze the impact of Maxwell stress by means of the electric capillary number CaE. Our findings reveal the rich physics of non-Newtonian fluids and widen the applications of electric field in non-Newtonian environments, which could be critical for bioengineering.

  10. Micro-scale hydrological field experiments in Romania

    NASA Astrophysics Data System (ADS)

    Minea, Gabriel; Moroşanu, Gabriela A.

    2016-02-01

    The paper (communication) presents an overview of hydrologic field experiments at micro-scale in Romania. In order to experimentally investigate micro (plot)-scale hydrological impact of soil erosion, the National Institute of Hydrology and Water Management founded Voineşti Experimental Basin (VES) in 1964 and the Aldeni Experimental Basins (AEB) in 1984. AEB and VES are located in the Curvature Subcarpathians. Experimental plots are organized in a double systems and have an area of 80 m2 (runoff plots) at AEB and 300 m2 (water balance plots) at VES. Land use of plot: first plot "grass-land" is covered with perennial grass and second plot (control) consists in "bare soil". Over the latter one, the soil is hoeing, which results in a greater development of infiltration than in the first plot. Experimental investigations at micro-scale are aimed towards determining the parameters of the water balance equation, during natural and artificial rainfalls, researching of flows and soil erosion processes on experimental plots, extrapolating relations involving runoff coefficients from a small scale to medium scale. Nowadays, the latest evolutions in data acquisition and transmission equipment are represented by sensors (such as: sensors to determinate the soil moisture content). Exploitation and dissemination of hydrologic data is accomplished by research themes/projects, year-books of basic data and papers.

  11. Effects of an electric field on white sharks: in situ testing of an electric deterrent.

    PubMed

    Huveneers, Charlie; Rogers, Paul J; Semmens, Jayson M; Beckmann, Crystal; Kock, Alison A; Page, Brad; Goldsworthy, Simon D

    2013-01-01

    Elasmobranchs can detect minute electromagnetic fields, <1 nV cm(-1), using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.

  12. Effects of an Electric Field on White Sharks: In Situ Testing of an Electric Deterrent

    PubMed Central

    Huveneers, Charlie; Rogers, Paul J.; Semmens, Jayson M.; Beckmann, Crystal; Kock, Alison A.; Page, Brad; Goldsworthy, Simon D.

    2013-01-01

    Elasmobranchs can detect minute electromagnetic fields, <1 nVcm–1, using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks. PMID:23658766

  13. Charge and current reservoirs for electric and magnetic field enhancement.

    PubMed

    Wang, Dongxing; Yang, Tian; Crozier, Kenneth B

    2010-05-10

    Two optical antenna designs incorporating structures termed charge and current reservoirs are proposed to realize localized high electric and magnetic field enhancement, respectively. Simulation results show that the fan-rod electric antenna design combines the advantages of the rod antenna and the bowtie antenna, and has higher field enhancement than either. The performance of a loop shaped magnetic antenna consisting of a pair of metallic strips with offsets is also verified numerically, with high magnetic field enhancement being observed in the simulation. In both of the designs, the concepts of charge and current reservoirs contribute to high electric and magnetic field enhancement.

  14. Radial electric fields in the vicinity of locked magnetic islands

    SciTech Connect

    Nishimura, S.; Itoh, K.; Ida, K.; Yagi, M.; Itoh, S.-I.

    2010-12-15

    The radial electric field in the vicinity of magnetic islands locked by resonant magnetic perturbations (static error fields) is numerically studied using a set of reduced two-fluid equations. The asymmetric radial electric fields across locked magnetic islands are observed, which are due to the symmetry breaking effects such as the cylindrical geometry and inhomogeneous electron diamagnetic drift. It is found that the magnitude of the difference (between maximum and minimum radial electric fields around O-point) is proportional to the averaged electron diamagnetic drift frequency inside magnetic islands and the square of the island width, but inversely proportional to the square root of the ion viscosity.

  15. Novel electric field effects on Landau levels in graphene.

    PubMed

    Lukose, Vinu; Shankar, R; Baskaran, G

    2007-03-16

    A new effect in graphene in the presence of crossed uniform electric and magnetic fields is predicted. Landau levels are shown to be modified in an unexpected fashion by the electric field, leading to a collapse of the spectrum, when the value of electric to magnetic field ratio exceeds a certain critical value. Our theoretical results, strikingly different from the standard 2D electron gas, are explained using a "Lorentz boost," and as an "instability of a relativistic quantum field vacuum." It is a remarkable case of emergent relativistic type phenomena in nonrelativistic graphene. We also discuss few possible experimental consequence.

  16. Electric field-mediated processing of polymer blend solutions

    NASA Technical Reports Server (NTRS)

    Wnek, G. E.; Krause, S.

    1993-01-01

    Multiphase polymer blends in which the minor phases are oriented in a desired direction may demonstrate unique optical, electrical, and mechanical properties. While morphology development in shear fields was studied extensively, little work has focused on effects of electric fields on phase structure. The use of electric fields for blend morphology modulation with particular attention given to solvent casting of blends in d.c. fields was explored. Both homopolymer blends (average phase sizes of several microns) and diblock copolymer/homopolymer blends (average phase sizes of hundreds of Angstroms) were investigated. Summarized are important observations and conclusions.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  18. Fabrication of an integrated piezo-electric micro-nebulizer for biochemical sample analysis

    NASA Astrophysics Data System (ADS)

    Pan, C. T.; Shiea, J.; Shen, S. C.

    2007-03-01

    This paper proposes a new micro-nebulizer integrating piezo-electric actuator, micro-nozzle plate, and the cavity of a micro-pump to achieve a high-quality nebulizing effect. With this micro-nebulizer, the size distribution of nebulized droplet particles is finer and more uniform than that of commercial ultrasonic and pneumatic ones. Besides, the system power consumption and volume size are lower and smaller than those of the ultrasonic and pneumatic types. Its whole size is about 18 mm × 32 mm × 35 mm in volume and power consumption is about 1 Watt. The fabrication process of a micro-nozzle plate includes multi-exposure and single develop (MESD), high-hardness nickel-cobalt (Ni-Co) alloy micro-electroplating and high-speed precise microinjection molding. A mold with hardness of Vicker (Hv) 550 is obtained. With such hardness, it endures the high-speed injection molding without deformation. The dimensions of nozzle plates are 4 mm in width, 7 mm in length 8 µm in nozzle-hole diameter and 100 µm in total thickness. The lowest thickness around a nozzle hole is 40 µm. The aspect ratio is about 5. When the working frequency of a piezo-electric micro-nebulizer is set at 16 KHz, a nebulizing rate of 1.8 cc min-1 is obtained. The developed piezo-electric micro-nebulizer at 16 KHz frequency oscillation shows an excellent mass median diameter (MMD or D[4][3]) value of 6.13 µm. This micro-nebulizer is applied to nebulize a test sample of myoglobin into a micro-droplet for the analysis of fused-droplet electrospray ionization (FD-ESI) mass spectrometry. Methyl-alcohol solvents of different consistencies are used to react with myoglobin for FD-ESI mass spectrometry analysis. The result reveals that this developed micro-nebulizer shows a better result of mass spectrometry compared to the commercial ultrasonic and pneumatic ones. This micro-nebulizer is applicable to the FD-ESI mass spectrometry analysis.

  19. Electric-field-induced rotation of Brownian metal nanowires.

    PubMed

    Arcenegui, Juan J; García-Sánchez, Pablo; Morgan, Hywel; Ramos, Antonio

    2013-09-01

    We describe the physical mechanism responsible for the rotation of Brownian metal nanowires suspended in an electrolyte exposed to a rotating electric field. The electric field interacts with the induced charge in the electrical double layer at the metal-electrolyte interface, causing rotation due to the torque on the induced dipole and to the induced-charge electro-osmotic flow around the particle. Experiments demonstrate that the primary driving mechanism is the former of these two. Our analysis contrasts with previous work describing the electrical manipulation of metallic particles with electric fields, which neglected the electrical double layer. Theoretical values for the rotation speed are calculated and good agreement with experiments is found.

  20. Electric toothbrushes induce electric current in fixed dental appliances by creating magnetic fields.

    PubMed

    Kameda, Takashi; Ohkuma, Kazuo; Ishii, Nozomu; Sano, Natsuki; Ogura, Hideo; Terada, Kazuto

    2012-01-01

    Magnetic fields can represent a health problem, especially low frequency electromagnetic fields sometimes induced by electric current in metallic objects worn or used in or on the body (as opposed to high frequency electromagnetic fields that produce heat). Electric toothbrushes are widely used because of their convenience, but the electric motors that power them may produce electromagnetic waves. In this study, we showed that electric toothbrushes generate low frequency (1-2000 Hz) magnetic fields and induce electric current in dental appliances (e. g. orthodontic and prosthetic appliances and dental implants). Current induced by electric toothbrushes might be dependent on the quantity and types of metals used, and the shape of the appliances. Furthermore, these induced currents in dental appliances could impact upon human oral health, producing pain and discomfort.

  1. Electric field prediction for a human body-electric machine system.

    PubMed

    Ioannides, Maria G; Papadopoulos, Peter J; Dimitropoulou, Eugenia

    2004-01-01

    A system consisting of an electric machine and a human body is studied and the resulting electric field is predicted. A 3-phase induction machine operating at full load is modeled considering its geometry, windings, and materials. A human model is also constructed approximating its geometry and the electric properties of tissues. Using the finite element technique the electric field distribution in the human body is determined for a distance of 1 and 5 m from the machine and its effects are studied. Particularly, electric field potential variations are determined at specific points inside the human body and for these points the electric field intensity is computed and compared to the limit values for exposure according to international standards.

  2. Recent measurements of middle atmospheric electric fields and related parameters

    NASA Astrophysics Data System (ADS)

    Zadorozhny, A. M.; Tyutin, A. A.; Bragin, O. A.; Kikhtenko, V. N.

    1994-03-01

    In 1989, two series of rocket measurements were carried out to investigate middle atmosphere electric fields. The measurements were taken both in the Northern Hemisphere on Heiss Island (80 deg 37 N and 58 deg 03 min E) and in the Southern Hemisphere in the Indian Ocean (40-60 deg S and approx. 45 deg E) on board the research vessel 'Akademik Shirshov'. Along with the vertical electric fields, aerosol content and positive ion density were also measured. Some of the rocket launches were made during the extremely strong solar proton events (SPE) of October 1989. The experiments showed the strong variability of the electric fields in the middle atmosphere at polar and high middle latitudes. In all the measurements the maximum of the vertical electric field height profile in the lower mesosphere was observed to be more than approx. 1 V/m. The electric field strength and the field direction at maximum varied considerably among the launches. A maximum value of +12 V/m was detected at a height of about 58 km at 58 deg 30 mins on 21 October 1989 during the SPE. The simultaneous measurements of the electric field strength, positive ion density and aerosols point out both an ion-aerosol interaction and a connection between the mesospheric electric fields and aerosol content.

  3. Enhanced Translational Dynamics of Water under Electric Field

    SciTech Connect

    Omar Diallo, Souleymane; Mamontov, Eugene; Wada, Nobuo; Inagaki, S; Fukushima, Y

    2012-01-01

    High resolution quasielastic neutron scattering measurements have been used to study the effects of applied electric field on the dynamics of water molecules confined in the pores of folded silica sheet material FSM-12 with an average pore diameter (apd) of 16 Angstroms. In the absence of field, there is a significant slowing down of the water molecule diffusion as the temperature is lowered, in agreement with previous observations. The application of a moderate electric field of 2.5 kV/mm remarkably enhances the translational diffusion of water molecules. We interpret this as being due to a disruption of the hydrogen bonding by the electric field. This new observation suggests that existing theories valid at large electric field strengths may have to be corrected at moderate fields.

  4. Micro-grid platform based on NODE.JS architecture, implemented in electrical network instrumentation

    NASA Astrophysics Data System (ADS)

    Duque, M.; Cando, E.; Aguinaga, A.; Llulluna, F.; Jara, N.; Moreno, T.

    2016-05-01

    In this document, I propose a theory about the impact of systems based on microgrids in non-industrialized countries that have the goal to improve energy exploitation through alternatives methods of a clean and renewable energy generation and the creation of the app to manage the behavior of the micro-grids based on the NodeJS, Django and IOJS technologies. The micro-grids allow the optimal way to manage energy flow by electric injection directly in electric network small urban's cells in a low cost and available way. In difference from conventional systems, micro-grids can communicate between them to carry energy to places that have higher demand in accurate moments. This system does not require energy storage, so, costs are lower than conventional systems like fuel cells, solar panels or else; even though micro-grids are independent systems, they are not isolated. The impact that this analysis will generate, is the improvement of the electrical network without having greater control than an intelligent network (SMART-GRID); this leads to move to a 20% increase in energy use in a specified network; that suggest there are others sources of energy generation; but for today's needs, we need to standardize methods and remain in place to support all future technologies and the best option are the Smart Grids and Micro-Grids.

  5. Electric field measurements during the MAC/EPSILON campaign

    NASA Technical Reports Server (NTRS)

    Croskey, C. L.; Hale, L. C.; Mitchell, J. D.; Schmidlin, F. J.; Hoppe, U.-P.

    1990-01-01

    The MAC/EPSILON observational campaign in northern Norway involved the taking of three-axis electric field measurements of the middle atmosphere by means of five rocketborne payloads during October and November, 1987. Simultaneous horizontal electric field measurements made by two of the rocket flights were in general agreement in their limited overlap region. The more extensive horizontal E-field measurements exhibited a decreasing mapping function with decreasing altitude, thereby indicating the presence of fields from a local auroral patch. Small-scale variations in the horizontal fields of the lights were similar to observed wavelike variations in the neutral wind field.

  6. Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields

    PubMed Central

    Sutton, Gregory P.; Clarke, Dominic; Morley, Erica L.; Robert, Daniel

    2016-01-01

    Bumblebees (Bombus terrestris) use information from surrounding electric fields to make foraging decisions. Electroreception in air, a nonconductive medium, is a recently discovered sensory capacity of insects, yet the sensory mechanisms remain elusive. Here, we investigate two putative electric field sensors: antennae and mechanosensory hairs. Examining their mechanical and neural response, we show that electric fields cause deflections in both antennae and hairs. Hairs respond with a greater median velocity, displacement, and angular displacement than antennae. Extracellular recordings from the antennae do not show any electrophysiological correlates to these mechanical deflections. In contrast, hair deflections in response to an electric field elicited neural activity. Mechanical deflections of both hairs and antennae increase with the electric charge carried by the bumblebee. From this evidence, we conclude that sensory hairs are a site of electroreception in the bumblebee. PMID:27247399

  7. Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields.

    PubMed

    Sutton, Gregory P; Clarke, Dominic; Morley, Erica L; Robert, Daniel

    2016-06-28

    Bumblebees (Bombus terrestris) use information from surrounding electric fields to make foraging decisions. Electroreception in air, a nonconductive medium, is a recently discovered sensory capacity of insects, yet the sensory mechanisms remain elusive. Here, we investigate two putative electric field sensors: antennae and mechanosensory hairs. Examining their mechanical and neural response, we show that electric fields cause deflections in both antennae and hairs. Hairs respond with a greater median velocity, displacement, and angular displacement than antennae. Extracellular recordings from the antennae do not show any electrophysiological correlates to these mechanical deflections. In contrast, hair deflections in response to an electric field elicited neural activity. Mechanical deflections of both hairs and antennae increase with the electric charge carried by the bumblebee. From this evidence, we conclude that sensory hairs are a site of electroreception in the bumblebee.

  8. Beyond Orientation: The Impact of Electric Fields on Block Copolymers

    SciTech Connect

    Liedel, Clemens; Boker, A.; Pester, Christian; Ruppel, Markus A; Urban, Volker S

    2012-01-01

    Since the first report on electric field-induced alignment of block copolymers (BCPs) in 1991, electric fields have been shown not only to direct the orientation of BCP nanostructures in bulk, solution, and thin films, but also to reversibly induce order-order transitions, affect the order-disorder transition temperature, and control morphologies' dimensions with nanometer precision. Theoretical and experimental results of the past years in this very interesting field of research are summarized and future perspectives are outlined.

  9. Fermionic Particle Production by Varying Electric and Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Sogut, Kenan; Yanar, Hilmi; Havare, Ali

    2016-11-01

    Creation of fermionic particles by a time-dependent electric field and a space-dependent magnetic field is studied with the Bogoulibov transformation method. Exact analytic solutions of the Dirac equation are obtained in terms of the Whittaker functions and the particle creation number density depending on the electric and magnetic fields is determined. Supported by the Research Fund of Mersin University in TURKEY with project number: 2016-1-AP4-1425

  10. Electric Field-Mediated Processing of Polymers. Appendix 1

    NASA Technical Reports Server (NTRS)

    Wnek, G. E.; Bowlin, G. L.; Haas, T. W.

    2000-01-01

    Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. We suggest that a broad range of properties can be achieved using a relatively small number of polymers, with electric fields providing the ability to tailor properties via the control of shape, morphology, and orientation. Specific attention is given to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options.

  11. Effect of ambient levels of power-line-frequency electric fields on a developing vertebrate

    SciTech Connect

    Blackman, C.F.; House, D.E.; Benane, S.G.; Joines, W.T.; Spiegel, R.J.

    1988-01-01

    Fertilized eggs of Gallus domesticus were exposed continuously during their 21-day incubation period to either 50- or 60-Hz sinusoidal electric fields at an average intensity of 10 Vrms/m. The exposure apparatus was housed in an environmental room maintained at 37 degrees C and 55-60% relative humidity (RH). Within 1.5 days after hatching, the chickens were removed from the apparatus and tested. The test consisted of examining the effect of 50- or 60-Hz electromagnetic fields at 15.9 Vrms/m and 73 nTrms (in a local geomagnetic field of 38 microT, 85 degrees N) on efflux of calcium ions from the chicken brain. For eggs exposed to 60-Hz electric fields during incubation, the chicken brains demonstrated a significant response to 50-Hz fields but not to 60-Hz fields, in agreement with the results from commercially incubated eggs. In contrast, the brains from chicks exposed during incubation to 50-Hz fields were not affected by either 50- or 60-Hz fields. These results demonstrate that exposure of a developing organism to ambient power-line-frequency electric fields at levels typically found inside buildings can alter the response of brain tissue to field-induced calcium-ion efflux. The physiological significance of this finding has yet to be established.

  12. Optofluidics based micro-photocatalytic fuel cell for efficient wastewater treatment and electricity generation.

    PubMed

    Li, Lin; Wang, Guanyi; Chen, Rong; Zhu, Xun; Wang, Hong; Liao, Qiang; Yu, Youxu

    2014-09-07

    In this work, an optofluidics based micro-photocatalytic fuel cell with a membrane-free and air-breathing mode was proposed to greatly enhance the cell performance. The incorporation of the optofluidic technology into a photocatalytic fuel cell not only enlarges the specific illumination and reaction area but also enhances the photon and mass transfer, which eventually boosts the photocatalytic reaction rate. Our results show that this new photocatalytic fuel cell yields a much higher performance in converting organics into electricity. A maximum power density of 0.58 mW cm(-2) was achieved. The degradation performance of this new optofluidic micro-photocatalytic fuel cell was also evaluated and the maximum degradation efficiency reached 83.9%. In short, the optofluidic micro-photocatalytic fuel cell developed in this work shows promising potential for simultaneously degrading organic pollutants and generating electricity.

  13. Variations of electric field and electric resistivity of air caused by dust motion

    NASA Astrophysics Data System (ADS)

    Seran, E.; Godefroy, M.; Renno, N.; Elliott, H.

    2013-08-01

    report results of a field campaign conducted in the Nevada desert with a suite of electric field instruments consisting of a field mill (FM) and a short dipole antenna (SDA). Furthermore, we show that a combination of the measurements of these two instruments allows the estimation of the electric resistivity of air, an important quantity that is extremely difficult to measure near the Earth's surface. The electric resistivity of air is found to vary between 1.5 · 1013 and 6 · 1013 Ω m and to correlate with changes in electric field. Vertical DC electric fields with amplitudes up to 6 kV m-1 were observed to correspond to clouds of dust blowing through the measurement site. Enhanced DC and AC electric fields are measured during periods when horizontal wind speed exceeds 7 m s-1, or around twice the background value. We suggest that low-frequency emissions, below ~200 Hz, are generated by the motion of electrically charged particles in the vicinity of the SDA electrode and propose a simple model to reproduce the observed spectra. According to this model, the spectral response is controlled by three parameters, (i) the speed of the charged particles, (ii) the charge concentration, and (iii) the minimum distance between the particle and the electrode. In order to explain the electric fields measured with the FM sensors at different heights, we developed a multilayer model that relates the electric field to the charge distribution. For example, a nonlinear variation of the electric field observed by the FM sensors below 50 cm is simulated by a near-surface layer of tens of centimeters that is filled with electrically charged particles that carry a predominantly negative charge in the vicinity of the soil. The charge concentration inside this layer is estimated to vary between 1012 and 5 · 1013 electrons m-3.

  14. Electric-field-induced structural changes in multilayer piezoelectric actuators during electrical and mechanical loading

    DOE PAGES

    Esteves, Giovanni; Fancher, Chris M.; Röhrig, Sören; ...

    2017-04-08

    The effects of electrical and mechanical loading on the behavior of domains and phases in Multilayer Piezoelectric Actuators (MAs) is studied using in situ high-energy X-ray diffraction (XRD) and macroscopic property measurements. Rietveld refinement is carried out on measured diffraction patterns using a two-phase tetragonal (P4mm) and rhombohedral (R3m) model. Applying an electric field promotes the rhombohedral phase, while increasing compressive uniaxial pre-stress prior to electric field application favors the tetragonal phase. The competition between electrical and mechanical energy leads to a maximal difference between electric-field-induced phase fractions at 70 MPa pre-stress. Additionally, the available volume fraction of non-180° domainmore » reorientation that can be accessed during electric field application increases with compressive pre-stress up to 70 MPa. The origin for enhanced strain and polarization with applied pre-stress is attributed to a combination of enhanced non-180° domain reorientation and electric-field-induced phase transitions. The suppression of both the electric-field-induced phase transitions and domain reorientation at high pre-stresses (>70 MPa) is attributed to a large mechanical energy barrier, and alludes to the competition of the electrical and mechanical energy within the MA during applied stimuli.« less

  15. Analysis of DE-1 PWI electric field data

    NASA Technical Reports Server (NTRS)

    Weimer, Daniel

    1994-01-01

    The measurement of low frequency electric field oscillations may be accomplished with the Plasma Wave Instrument (PWI) on DE 1. Oscillations at a frequency around 1 Hz are below the range of the conventional plasma wave receivers, but they can be detected by using a special processing of the quasi-static electric field data. With this processing it is also possible to determine if the electric field oscillations are predominately parallel or perpendicular to the ambient magnetic field. The quasi-static electric field in the DE 1 spin/orbit plane is measured with a long-wire 'double probe'. This antenna is perpendicular to the satellite spin axis, which in turn is approximately perpendicular to the geomagnetic field in the polar magnetosphere. The electric field data are digitally sampled at a frequency of 16 Hz. The measured electric field signal, which has had phase reversals introduced by the rotating antenna, is multiplied by the sine of the rotation angle between the antenna and the magnetic field. This is called the 'perpendicular' signal. The measured time series is also multiplied with the cosine of the angle to produce a separate 'parallel' signal. These two separate time series are then processed to determine the frequency power spectrum.

  16. Effects of an electric field on interaction of aromatic systems.

    PubMed

    Youn, Il Seung; Cho, Woo Jong; Kim, Kwang S

    2016-04-30

    The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post-HF (MP2, SCS-MP2, and CCSD(T)) and density functional (PBE0-D3, PBE0-TS, and vdW-DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post-HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π-conjugated system does not have significant effect on the electric field dependence. We found out that PBE0-based methods give reasonable interaction energies and electric field response in every case, while vdW-DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc.

  17. The hydrogen atom in plasmas with an external electric field

    SciTech Connect

    Bahar, M. K.; Soylu, A.

    2014-09-15

    We numerically solve the Schrödinger equation, using a more general exponential cosine screened Coulomb (MGECSC) potential with an electric field, in order to investigate the screening and weak external electric field effects on the hydrogen atom in plasmas. The MGECSC potential is examined for four different cases, corresponding to different screening parameters of the potential and the external electric field. The influences of the different screening parameters and the weak external electric field on the energy eigenvalues are determined by solving the corresponding equations using the asymptotic iteration method (AIM). It is found that the corresponding energy values shift when a weak external electric field is applied to the hydrogen atom in a plasma. This study shows that a more general exponential cosine screened Coulomb potential allows the influence of an applied, weak, external electric field on the hydrogen atom to be investigated in detail, for both Debye and quantum plasmas simultaneously. This suggests that such a potential would be useful in modeling similar effects in other applications of plasma physics, and that AIM is an appropriate method for solving the Schrödinger equation, the solution of which becomes more complex due to the use of the MGECSC potential with an applied external electric field.

  18. Identifying the nonlinear mechanical behaviour of micro-speakers from their quasi-linear electrical response

    NASA Astrophysics Data System (ADS)

    Zilletti, Michele; Marker, Arthur; Elliott, Stephen John; Holland, Keith

    2017-05-01

    In this study model identification of the nonlinear dynamics of a micro-speaker is carried out by purely electrical measurements, avoiding any explicit vibration measurements. It is shown that a dynamic model of the micro-speaker, which takes into account the nonlinear damping characteristic of the device, can be identified by measuring the response between the voltage input and the current flowing into the coil. An analytical formulation of the quasi-linear model of the micro-speaker is first derived and an optimisation method is then used to identify a polynomial function which describes the mechanical damping behaviour of the micro-speaker. The analytical results of the quasi-linear model are compared with numerical results. This study potentially opens up the possibility of efficiently implementing nonlinear echo cancellers.

  19. Galvanotactic behavior of Tetrahymena pyriformis under electric fields

    NASA Astrophysics Data System (ADS)

    Kim, Dal Hyung; Kim, Paul Seung Soo; Lee, Kyoungwoo; Kim, JinSeok; Kim, Min Jun

    2013-12-01

    Tetrahymena pyriformis, a eukaryotic ciliate, swims toward a cathode in straight or cross-shaped microchannels under an applied electric field, a behavioral response called cathodal galvanotaxis. In straight channel experiments, a one-dimensional electric field was applied, and the galvanotactic swimming behavior of Tetrahymena pyriformis was observed and described in detail while the polarity of this field is switched. In most individual cases, the cell would immediately switch its direction toward the cathode; however, exceptional cases have been observed where cells exhibit a turning delay or do not turn after a polarity switch. In cross-channel experiments, feedback control using vision-based tracking was used to steer a cell in the microchannel intersection using a two-dimensional electric field generated by four electrodes placed at four ends of the cross channel. The motivation for this work is to study the swimming behavior of Tetrahymena pyriformis as a microrobot under the control of electric fields.

  20. Electric Field Induced Selective Disordering in Lamellar Block Copolymers

    SciTech Connect

    Ruppel, Markus A; Pester, Christian W; Langner, Karol M; Sevink, Geert; Schoberth, Heiko; Schmidt, Kristin; Urban, Volker S; Mays, Jimmy; Boker, Alexander

    2013-01-01

    External electric fields align nanostructured block copolymers by either rotation of grains or nucleation and growth depending on how strongly the chemically distinct block copolymer components are segregated. In close vicinity to the orderdisorder transition, theory and simulations suggest a third mechanism: selective disordering. We present a time-resolved small-angle X-ray scattering study that demonstrates how an electric field can indeed selectively disintegrate ill-aligned lamellae in a lyotropic block copolymer solution, while lamellae with interfaces oriented parallel to the applied field prevail. The present study adds an additional mechanism to the experimentally corroborated suite of mechanistic pathways, by which nanostructured block copolymers can align with an electric field. Our results further unveil the benefit of electric field assisted annealing for mitigating orientational disorder and topological defects in block copolymer mesophases, both in close vicinity to the orderdisorder transition and well below it.

  1. Electric field induced selective disordering in lamellar block copolymers.

    PubMed

    Ruppel, Markus; Pester, Christian W; Langner, Karol M; Sevink, Geert J A; Schoberth, Heiko G; Schmidt, Kristin; Urban, Volker S; Mays, Jimmy W; Böker, Alexander

    2013-05-28

    External electric fields align nanostructured block copolymers by either rotation of grains or nucleation and growth depending on how strongly the chemically distinct block copolymer components are segregated. In close vicinity to the order-disorder transition, theory and simulations suggest a third mechanism: selective disordering. We present a time-resolved small-angle X-ray scattering study that demonstrates how an electric field can indeed selectively disintegrate ill-aligned lamellae in a lyotropic block copolymer solution, while lamellae with interfaces oriented parallel to the applied field prevail. The present study adds an additional mechanism to the experimentally corroborated suite of mechanistic pathways, by which nanostructured block copolymers can align with an electric field. Our results further unveil the benefit of electric field assisted annealing for mitigating orientational disorder and topological defects in block copolymer mesophases, both in close vicinity to the order-disorder transition and well below it.

  2. Molecular-scale measurements of electric fields at electrochemical interfaces.

    SciTech Connect

    Hayden, Carl C.; Farrow, Roger L.

    2011-01-01

    Spatially resolved measurements of electric fields at electrochemical interfaces would be a critical step toward further understanding and modeling the detailed structure of electric double layers. The goal of this project was to perform proof-of-principle experiments to demonstrate the use of field-sensitive dyes for optical measurements of fields in electrochemical systems. A confocal microscope was developed that provides sensitive detection of the lifetime and high resolution spectra of excited fluorescence for dyes tethered to electrically conductive surfaces. Excited state lifetimes for the dyes were measured and found to be relatively unquenched when linked to indium tin oxide, but strongly quenched on gold surfaces. However, our fluorescence detection is sufficiently sensitive to measure spectra of submonolayer dye coatings even when the fluorescence was strongly quenched. Further work to create dye labeled interfaces on flat, uniform and durable substrates is necessary to make electric field measurements at interfaces using field sensitive dyes.

  3. Generation of strong electric fields in an ice film capacitor.

    PubMed

    Shin, Sunghwan; Kim, Youngsoon; Moon, Eui-seong; Lee, Du Hyeong; Kang, Hani; Kang, Heon

    2013-08-21

    We present a capacitor-type device that can generate strong electrostatic field in condensed phase. The device comprises an ice film grown on a cold metal substrate in vacuum, and the film is charged by trapping Cs(+) ions on the ice surface with thermodynamic surface energy. Electric field within the charged film was monitored through measuring the film voltage using a Kelvin work function probe and the vibrational Stark effect of acetonitrile using IR spectroscopy. These measurements show that the electric field can be increased to ∼4 × 10(8) V m(-1), higher than that achievable by conventional metal plate capacitors. In addition, the present device may provide several advantages in studying the effects of electric field on molecules in condensed phase, such as the ability to control the sample composition and structure at molecular scale and the spectroscopic monitoring of the sample under electric field.

  4. Scale effects and a method for similarity evaluation in micro electrical discharge machining

    NASA Astrophysics Data System (ADS)

    Liu, Qingyu; Zhang, Qinhe; Wang, Kan; Zhu, Guang; Fu, Xiuzhuo; Zhang, Jianhua

    2016-08-01

    Electrical discharge machining(EDM) is a promising non-traditional micro machining technology that offers a vast array of applications in the manufacturing industry. However, scale effects occur when machining at the micro-scale, which can make it difficult to predict and optimize the machining performances of micro EDM. A new concept of "scale effects" in micro EDM is proposed, the scale effects can reveal the difference in machining performances between micro EDM and conventional macro EDM. Similarity theory is presented to evaluate the scale effects in micro EDM. Single factor experiments are conducted and the experimental results are analyzed by discussing the similarity difference and similarity precision. The results show that the output results of scale effects in micro EDM do not change linearly with discharge parameters. The values of similarity precision of machining time significantly increase when scaling-down the capacitance or open-circuit voltage. It is indicated that the lower the scale of the discharge parameter, the greater the deviation of non-geometrical similarity degree over geometrical similarity degree, which means that the micro EDM system with lower discharge energy experiences more scale effects. The largest similarity difference is 5.34 while the largest similarity precision can be as high as 114.03. It is suggested that the similarity precision is more effective in reflecting the scale effects and their fluctuation than similarity difference. Consequently, similarity theory is suitable for evaluating the scale effects in micro EDM. This proposed research offers engineering values for optimizing the machining parameters and improving the machining performances of micro EDM.

  5. The use of electric fields in tissue engineering

    PubMed Central

    2008-01-01

    The use of electric fields for measuring cell and tissue properties has a long history. However, the exploration of the use of electric fields in tissue engineering is only very recent. A review is given of the various methods by which electric fields may be used in tissue engineering, concentrating on the assembly of artificial tissues from its component cells using electrokinetics. A comparison is made of electrokinetic techniques with other physical cell manipulation techniques which can be used in the construction of artificial tissues. PMID:19279709

  6. Electric field induced lateral instability in a simple autocatalytic front

    NASA Astrophysics Data System (ADS)

    Horváth, Dezsö; Tóth, Ágota; Yoshikawa, Kenichi

    1999-07-01

    The effect of ionic drift caused by small constant electric field on autocatalytic reaction fronts of ionic species is studied both theoretically and numerically. Besides varying the velocity of propagation, the electric field parallel to the direction of propagation may induce lateral instability in planar fronts resulting in the emergence of cellular structures. The difference in the diffusivities at the onset of instability are lowered when the electric field tends to separate the species spatially. The predictions of the linear stability analysis based on a thin-front approximation are confirmed by the numerical integration of the full two-dimensional system.

  7. Species-Independent Femtosecond Localized Electric Field Measurement

    NASA Astrophysics Data System (ADS)

    Dogariu, Arthur; Goldberg, Benjamin M.; O'Byrne, Sean; Miles, Richard B.

    2017-02-01

    We present an optical measurement method using a femtosecond laser for nonintrusive measurements of electric field strength and orientation in virtually any gas or gas mixture via second-harmonic generation. This simple method takes advantage of the asymmetry in polarizability induced by an applied electric field, which enables the otherwise forbidden second-harmonic generation in any centrosymmetric or homogeneous media. The use of a femtosecond laser source permits high intensities without avalanche breakdown and leads to the measurement of electric field strength down to approximately 100 V / cm in air with submillimeter spatial resolution governed by the confocal parameter and femtosecond temporal resolution governed by the laser-pulse duration.

  8. Field-Induced Phenomena in Electrical Insulation.

    DTIC Science & Technology

    1984-09-29

    excitation (penetrating charged particle or electron beam, electrical circuit), conditions of excitation (intensity, wave form),[lO] polarity...known as thermal breakdown.[66 ] Additionally, any rise in temperature due to dielectric losses within the polymer will tend to accelarate the

  9. Synthesis of zirconium oxynitride in air under DC electric fields

    NASA Astrophysics Data System (ADS)

    Morisaki, Nobuhiro; Yoshida, Hidehiro; Matsui, Koji; Tokunaga, Tomoharu; Sasaki, Katsuhiro; Yamamoto, Takahisa

    2016-08-01

    We synthesized zirconium oxynitride from yttria-stabilized zirconia (YSZ) in air by applying DC electric fields that produced a controlled electric current in the specimen. When YSZ was heated under an applied DC electric field, the electric current of the specimen steeply increased at a critical temperature, called a flash event, during flash sintering. By keeping the electric current of the specimen constant during the flash event and then holding the specimen at the critical temperature, YSZ was transformed into zirconium oxynitride under the optimal conditions of 50 V/cm, 500 mA, and 1000 °C. We confirmed that zirconium oxynitride formed using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and energy-dispersive spectrometry. To convert oxides to nitrides, reducing conditions are necessary to form excess oxygen vacancies. Our technique produced the strong reducing conditions necessary to form nitrides from the oxides by delivering a controlled electric current to the specimen.

  10. The source of the electric field in the nightside magnetosphere

    NASA Technical Reports Server (NTRS)

    Stern, D. P.

    1975-01-01

    In the open magnetosphere model magnetic field lines from the polar caps connect to the interplanetary magnetic field and conduct an electric field from interplanetary space to the polar ionosphere. By examining the magnetic flux involved it is concluded that only slightly more than half of the magnetic flux in the polar caps belongs to open field lines and that such field lines enter or leave the magnetosphere through narrow elongated windows stretching the tail. These window regions are identified with the tail's boundary region and shift their position with changes in the interplanetary magnetic field, in particular when a change of interplanetary magnetic sector occurs. The circuit providing electric current in the magnetopause and the plasma sheet is extended across those windows; thus energy is drained from the interplanetary electric field and an electric potential drop is produced across the plasma sheet. The polar cap receives its electric field from interplanetary space on the day side from open magnetic field lines and on the night side from closed field lines leading to the plasma sheet. The theory described provides improved understanding of magnetic flux bookkeeping, of the origin of Birkeland currents, and of the boundary layer of the geomagnetic tail.

  11. Vertical Electric Field Measurements with Copper Plates by Sounding Balloon

    NASA Astrophysics Data System (ADS)

    Wen, Shao-Chun; Chiu, Cheng-Hsiu; Bing-Chih Chen, Alfred; Hsu, Rue-Ron; Su, Han-Tzong

    2015-04-01

    The vertical electric field plays an important role in driving the circulation of the global electric circuit, and crucial to the formation of the transient luminous events (TLEs). The in-situ measurement of the electric field in the upper atmosphere, especially from cloud top to the bottom of the ionosphere is very challenging but essential. Limited by the flight vehicle, the measurements of the electric field in and above cloud, especiall thundercloud, is rare up to now. A light-weight electric field meter was developed independently and sent to 30 km height by small meteorological balloons successfully. Other than the existing long-spaced, spherical probe design, an improved electric field meter has been built and tested carefully. A new circuit with ultra high input impedance and a high voltage amplifier is implemented to reduce the AC noise induced by the voltage divider. Two copper plates are used to replace the double spherical probes which is spaced by a long fiberglass boom. The in-lab calibration and tests show that this new model is superior to the existing design and very sensitive to the variation of the DC electric field. In this poster, the design and the in-lab tests will be presented, and preliminary results of the flight experiments are also discussed.

  12. Formation of Organized Protein Thin Films with External Electric Field.

    PubMed

    Ferreira, Cecília Fabiana da G; Camargo, Paulo C; Benelli, Elaine M

    2015-10-01

    The effect of an external electric field on the formation of protein GlnB-Hs films and on its buffer solution on siliconized glass slides has been analyzed by current versus electric field curves and atomic force microscopy (AFM). The Herbaspirillum seropedicae GlnB protein (GlnB-Hs) is a globular, soluble homotrimer (36 kDa) with its 3-D structure previously determined. Concentrations of 10 nM native denatured GlnB-Hs protein were deposited on siliconized glass slides under ambient conditions. Immediately after solution deposition a maximum electric field of 30 kV/m was applied with rates of 3 V/s. The measured currents were surface currents and were analyzed as transport current. Electric current started to flow only after a minimum electric field (critical value) for the systems analyzed. The AFM images showed films with a high degree of directional organization only when the proteins were present in the solution. These results showed that the applied electric field favored directional organization of the protein GlnB-Hs films and may contribute to understand the formation of protein films under applied electric fields.

  13. Suppression of the cardiac electric field artifact from the heart action evoked potential.

    PubMed

    Pérez, J J; Guijarro, E; Barcia, J A

    2005-09-01

    The study of heart action-related brain potentials is strongly disrupted by the presence of an inherent cardiac electric artifact. The hypothesis is presented that most of the electric current coupled to the cardiac field surrounds the skull and flows through the scalp tissue without crossing the cranial cavity. This pseudo two-dimensional conduction model contrasts with the volumetric conduction of the brain electrical activity, and this property is exploited to cancel the cardiac electric artifact. QRS loop vector-cardiographic projections on saggital planes were recorded in 11 healthy subjects in the head and neck areas. Comparative analysis of the projection eccentricities, estimated by the correlation coefficients of the paired data on each area, supported the hypothesis and allowed the handling of the cardiac electric field at the scalp as if enclosed in a two-dimensional wrapped space. This approach permitted the combination of different heart action-related brain potentials recorded at different electrode positions to cancel the cardiac electric artifact. The cancellation method, applied to the subjects' EEG data, yielded a slow cortical potential with a negligible cardiac electric residue and an amplitude of about 1.5-2 microV, with a maximum around 150 ms and a minimum at 400 ms post-R wave.

  14. Insurance for electric and magnetic field litigation: Are you covered

    SciTech Connect

    Anderson, E.R.; Stewart, C.A. III

    1993-04-01

    Electrical power generating companies, power transmission companies and large generators and users of electrical power recently felt the sting of a second shock. The first shock came when lawsuits were first filed against companies in the electrical power industry claiming real or imagined damages from electrical and magnetic fields ([open quotes]EMFs[close quotes]). The new and second shock is potentially more devastating because it comes from the [open quotes]safe hands[close quotes] of the insurance industry. Standard-form comprehensive general liability ([open quotes]CGL[close quotes]) insurance policies purchased by nearly every company in the electrical power industry for generations are supposed to cover EMF bodily injury and property damage claims. Not so, say the lawyers for the most prominent insurance company selling insurance coverage to electric utilities, Associated Electric Gas Insurance Services, Ltd. ([open quotes]AEGIS[close quotes]).

  15. System for the exposure of cell suspensions to power-frequency electric fields.

    PubMed

    Kaune, W T; Frazier, M E; King, A J; Samuel, J E; Hungate, F P; Causey, S C

    1984-01-01

    A system is described that uses an oscillating magnetic field to produce power-frequency electric fields with strengths in excess of those produced in an animal or human standing under a high-voltage electric-power transmission line. In contrast to other types of exposure systems capable of generating fields of this size, no electrodes are placed in the conducting growth media: the possibility of electrode contamination of the exposed suspension is thereby eliminated. Electric fields in the range 0.02-3.5 V/m can be produced in a cell culture with total harmonic distortions less than 1.5%. The magnetic field used to produce electric fields for exposure is largely confined within a closed ferromagnetic circuit, and experimental and control cells are exposed to leakage magnetic flux densities less than 5 microT . The temperatures of the experimental and control cell suspensions are held fixed within +/- 0.1 degrees C by a water bath. Special chambers were developed to hold cell cultures during exposure and sham exposure. Chinese hamster ovary (CHO) cells incubated in these chambers grew for at least 48 h and had population doubling times of 16-17 h, approximately the same as for CHO cells grown under standard cell-culture conditions.

  16. Hyperfine structure of the hydroxyl free radical (OH) in electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Maeda, Kenji; Wall, Michael L.; Carr, Lincoln D.

    2015-05-01

    We investigate single-particle energy spectra of the hydroxyl free radical (OH) in the lowest electronic and rovibrational level under combined static electric and magnetic fields, as an example of heteronuclear polar diatomic molecules. In addition to the fine-structure interactions, the hyperfine interactions and centrifugal distortion effects are taken into account to yield the zero-field spectrum of the lowest 2Π3 / 2 manifold to an accuracy of less than 2kHz. We also examine level crossings and repulsions in the hyperfine structure induced by applied electric and magnetic fields. Compared to previous work, we found more than 10 percent reduction of the magnetic fields at level repulsions in the Zeeman spectrum subjected to a perpendicular electric field. In addition, we find new level repulsions, which we call Stark-induced hyperfine level repulsions, that require both an electric field and hyperfine structure. It is important to take into account hyperfine structure when we investigate physics of OH molecules at micro-Kelvin temperatures and below. This research was supported in part by AFOSR Grant No.FA9550-11-1-0224 and by the NSF under Grants PHY-1207881 and NSF PHY-1125915. We appreciate the Aspen Center for Physics, supported in part by the NSF Grant No.1066293, for hospitality.

  17. Spectral studies of the sources of ionospheric electric fields

    SciTech Connect

    Earle, G.D.; Kelley, M.C. )

    1987-01-01

    Spectral analyses have been performed upon a number of incoherent scatter radar data sets obtained at Jicamarca, Peru; Chatanika, Alaska; and Arecibo, Puerto Rico, with the goal of understanding the sources of electric fields with periods in the range of 1-10 hours. Two distinct sources are identified and studied in some detail. In quiet times, atmospheric gravity waves seem the most likely source of the ionospheric electric field. In fact, both in an average sense and in the single case study available the mesospheric winds measured at Poker Flat, Alaska, in this frequency range are remarkably similar in magnitude to the quiet time thermospheric plasma drifts measured overhead by the nearby Chatanika radar. Such drifts are driven by electric fields which, the authors argue, could easily be generated by the observed wind fields. Comparison with the spectra of electric field measurements at other latitudes suggests that such a source is worldwide and determines the geophysical noise level of low- and mid-latitude electric field measurements. Turning to active times, the authors present a measure of the transfer function for electric field measurements. Turning to active times, they present a measure of the transfer function for electric field penetration between high- and low-altitude L shells. At the very lowest frequencies (periods of {ge} 10 hours) the low-altitude sites are well shielded, presumably by an Alfven layer at the inner edge of the ring current. Higher frequency fluctuations penetrate very easily to low latitudes. A response peak seems to occur in the 3- to 5-hour range of periods, with a lower response occurring at 1 cycle/hour, although this result must be viewed as preliminary for now. Between L = 5.5 and L = 1.4 the zonal electric field component as projected to the equatorial plane of the magnetosphere penetrates with little or no attenuation.

  18. Near-Field CARS with Micro- and Nano-Particle

    NASA Astrophysics Data System (ADS)

    Ooi, C. H. Raymond

    2010-08-01

    Spatial dependence of coherent anti-Stokes Raman scattering (CARS) intensity and spectra for a spherical particle are studied for different sizes, ranging from micrometers to nanometers. Effects of near field on the spectra are analyzed, showing potential application as nano-sensor in microscopy and imaging. The results can be extended to an array of nanospheres. The CARS process has been developed into a versatile real-time detection technique in spectroscopy and microscopy [1]. In particularly, backscattered ultra-violet CARS implemented on LIDAR system [2] is promising for remote detection of molecular species present in hazardous biological aerosols with microscale dimension. In practice, the aerosols could be in any dimension. Thus, we need to know study a modified the setup of the CARS technique for reliable detection of chemicals in micro- and nano-particles using near-field effects. We have developed a nonlinear semiclassical microscopic theory to describe the CARS spectra for a particle composed of a collection of arbitrarily complex molecules [3] as well as simple few levels quantum systems [2]. The theory provides useful results on the CARS spectra for any observation angle and for any form of laser pulses [3]. Here, we focus on the spectra in the near field. We wish to study how the spectra vary with the near field distance with focused laser pulses. We also analyze to what extend the dimension of the particle and the focusing laser affect the lensing effect which could enhance the backscattered light.

  19. Electric-field sensing using single diamond spins

    NASA Astrophysics Data System (ADS)

    Dolde, F.; Fedder, H.; Doherty, M. W.; Nöbauer, T.; Rempp, F.; Balasubramanian, G.; Wolf, T.; Reinhard, F.; Hollenberg, L. C. L.; Jelezko, F.; Wrachtrup, J.

    2011-06-01

    The ability to sensitively detect individual charges under ambient conditions would benefit a wide range of applications across disciplines. However, most current techniques are limited to low-temperature methods such as single-electron transistors, single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we introduce a quantum-metrology technique demonstrating precision three-dimensional electric-field measurement using a single nitrogen-vacancy defect centre spin in diamond. An a.c. electric-field sensitivity reaching 202+/-6Vcm-1Hz-1/2 has been achieved. This corresponds to the electric field produced by a single elementary charge located at a distance of ~150nm from our spin sensor with averaging for one second. The analysis of the electronic structure of the defect centre reveals how an applied magnetic field influences the electric-field-sensing properties. We also demonstrate that diamond-defect-centre spins can be switched between electric- and magnetic-field sensing modes and identify suitable parameter ranges for both detector schemes. By combining magnetic- and electric-field sensitivity, nanoscale detection and ambient operation, our study should open up new frontiers in imaging and sensing applications ranging from materials science to bioimaging.

  20. Field-Induced Superconductivity in Electric Double Layer Transistors

    NASA Astrophysics Data System (ADS)

    Ueno, Kazunori; Shimotani, Hidekazu; Yuan, Hongtao; Ye, Jianting; Kawasaki, Masashi; Iwasa, Yoshihiro

    2014-03-01

    Electric field tuning of superconductivity has been a long-standing issue in solid state physics since the invention of the field-effect transistor (FET) in 1960. Owing to limited available carrier density in conventional FET devices, electric-field-induced superconductivity was believed to be possible in principle but impossible in practice. However, in the past several years, this limitation has been overcome by the introduction of an electrochemical concept, and electric-field-induced superconductivity has been realized. In the electric double layer (EDL) formed at the electrochemical interfaces, an extremely high electric field is generated and hence high-density charge carriers sufficient to induce superconductivity exist and are collectively used as a charge accumulation device known as an EDL capacitor. Field-induced superconductivity has been used to establish the relationship between Tc and carrier density and can now be used to search for new superconductors. Here, we review electric-field-induced superconductivity using an FET device, with a particular focus on the latest advances in EDL transistors.

  1. Electric and magnetic fields in medicine and biology

    SciTech Connect

    Not Available

    1985-01-01

    Papers Include: The effects of low frequency (50 Hz) magnetic fields on neuro-chemical transmission in vitro; Morphological changes in E Coli subjected to DC electrical fields; An investigation of some claimed biological effects of electromagnetic fields; Electrical phenomena and bone healing - a comparison of contemporary techniques; Clinical evaluations of a portable module emitting pulsed RF energy; The design, construction and performance of a magnetic nerve stimulator; The principle of electric field tomography and its application to selective read-out of information from peripheral nerves; Applied potential tomography - clinical applications; Impendance imaging using a linear electrode array; Mathematics as an aid to experiment: human body currents induced by power frequency electric fields; Effects of electric field near 750KV transmission line and protection against their harmful consequences; Leukemia and electromagnetic fields: a case-control study; Overhead power lines and childhood cancer; Magnetic measurement of nerve action currents - a new intraoperative recording technique; The potential use of electron spin resonance or impedance measurement to image neuronal electrical activity in the human brain.

  2. Stability of a liquid drop in an electric field

    SciTech Connect

    Popova, L.N.; Fedorenko, A.I.

    1982-04-01

    The boundary-value problem is solved for the critical electric field that causes a loss of stability of a dielectric electric drop. The theory is compared to experimental results on water, glycerin, N, N-dimethylformamide, and diethylene glycol.(AIP)

  3. EFFECT OF ELECTRIC FIELD ON CONTINUOUS LIQUID STREAM

    DTIC Science & Technology

    The effect of an electrical field on a continous water jet is considered. The higher electrification of water jets, the more intense are jet sprays...It seems possible to contract an electrized water jet by letting it pass the cylinder charged with the same sign. An attempt to electrify kerosene and spindel oil jets (good insulators) was unsucessful.

  4. Ion trap electric field measurements using slab coupled optical sensors

    NASA Astrophysics Data System (ADS)

    Shumway, L.; Chadderdon, S.; Powell, A.; Li, A.; Austin, D.; Hawkins, A.; Selfridge, R.; Schultz, S.

    2014-03-01

    Ion traps are widely used in the field of mass spectrometry. These devices use high electric fields to mass-selectively trap, eject, and count the particles of a material, producing a mass spectrum of the given material. Because of their usefulness, technology pushes for smaller, more portable ion traps for field use. Making internal ion trap field measurements not yet feasible because current electric field sensors are often too bulky or their metallic composition perturbs field measurements. Using slab coupled optical sensor (SCOS) technology, we are able to build sensors that are compatible with the spacing constraints of the ion trap. These sensors are created by attaching a nonlinear crystal slab waveguide to an optical fiber. When a laser propagates through the fiber, certain wavelengths of light couple out of the fiber via the crystal and create "resonances" in the output light spectrum. These resonances shift in proportion to a given applied electric field, and by measuring that shift, we can approximate the electric field. Developing a sensor that can effectively characterize the electric fields within an ion trap will greatly assist in ion trap design, fabrication, and troubleshooting techniques.

  5. Electric Field Measurements in Non-Equilibrium Electric Discharge Plasmas Using Picosecond Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.

    This dissertation presents the results of development of a picosecond four wave mixing technique and its use for electric field measurements in nanosecond pulse discharges. This technique is similar to coherent anti-Stokes Raman spectroscopy and is well suited for electric field measurements in high pressure plasmas with high spatial and temporal resolution. The results show that the signal intensity scales proportionally to the square of the electric field, the signal is emitted as a coherent beam, and is polarized parallel to the electric field vector, making possible electric field vector component measurements. The signal is generated when a collinear pair of pump and Stokes beams, which are generated in a stimulated Raman shifting cell (SRS), generate coherent excitation of molecules into a higher energy level, hydrogen for the present work. The coherent excitation mixes with a dipole moment induced by an external electric field. The mixing of these three "waves'" allows the molecules to radiate at their Raman frequency, producing a fourth, signal, wave which is proportional to the square of the electric field. The time resolution of this technique is limited by the coherence decay time of the molecules, which is a few hundred picoseconds.

  6. High-intensity pulsed electric field variables affecting Staphylococcus aureus inoculated in milk.

    PubMed

    Sobrino-López, A; Raybaudi-Massilia, R; Martín-Belloso, O

    2006-10-01

    Staphylococcus aureus is an important milk-related pathogen that is inactivated by high-intensity pulsed electric fields (HIPEF). In this study, inactivation of Staph. aureus suspended in milk by HIPEF was studied using a response surface methodology, in which electric field intensity, pulse number, pulse width, pulse polarity, and the fat content of milk were the controlled variables. It was found that the fat content of milk did not significantly affect the microbial inactivation of Staph. aureus. A maximum value of 4.5 log reductions was obtained by applying 150 bipolar pulses of 8 mus each at 35 kV/cm. Bipolar pulses were more effective than those applied in the monopolar mode. An increase in electric field intensity, pulse number, or pulse width resulted in a drop in the survival fraction of Staph. aureus. Pulse widths close to 6.7 micros lead to greater microbial death with a minimum number of applied pulses. At a constant treatment time, a greater number of shorter pulses achieved better inactivation than those treatments performed at a lower number of longer pulses. The combined action of pulse number and electric field intensity followed a similar pattern, indicating that the same fraction of microbial death can be reached with different combinations of the variables. The behavior and relationship among the electrical variables suggest that the energy input of HIPEF processing might be optimized without decreasing the microbial death.

  7. Ocean Electric Field for Oceanography and Surveillance

    DTIC Science & Technology

    2014-10-27

    learn about ONR concerns and provide feedback on issues, such as opportunities and priorities for Arctic Ocean research. I will continue to...University of Washington Applied Physics Laboratory 1013 NE 40th Street Box 355640 Seattle, WA 98105-6698 Final Report Ocean Electric...I supervised. Both were awarded MS degrees by the UW School of Oceanography and are currently employed in ocean studies at APL-JHU and NOAA

  8. Micro-electromechanical sensors in the analytical field.

    PubMed

    Zougagh, Mohammed; Ríos, Angel

    2009-07-01

    Micro- and nano-electromechanical systems (MEMS and NEMS) for use as sensors represent one of the most exciting new fields in analytical chemistry today. These systems are advantageous over currently available non-miniaturized sensors, such as quartz crystal microbalances, thickness shear mode resonators, and flexural plate wave oscillators, because of their high sensitivity, low cost and easy integration into automated systems. In this article, we present and discuss the evolution in the use of MEMS and NEMS, which are basically cantilever-type sensors, as good analytical tools for a wide variety of applications. We discuss the analytical features and the practical potential of micro(nano)-cantilever sensors, which combine the synergetic advantages of selectivity, provided by their functionalization, and the high sensitivity, which is attributed largely to the extremely small size of the sensing element. An insight is given into the different types of functionalization and detection strategies and a critical discussion is presented on the existing state of the art concerning the applications reported for mechanical microsensors. New developments and the possibilities for routine work in the near future are also covered.

  9. School Facilities and Electric and Magnetic Field Radiation.

    ERIC Educational Resources Information Center

    Carr, Richard L.

    1990-01-01

    The possibility that electric and magnetic field radiation poses a health hazard should be recognized during the planning and designing of a school. A preconstruction assessment of possible exposure should be evaluated before the start of construction. (MLF)

  10. Enhanced Fair-Weather Electric Fields Soon After Sunrise

    NASA Technical Reports Server (NTRS)

    Marshall, T. C.; Rust, W. D.; Stolzenburg, M.; Roeder, W.; Krehbiel, P. R.

    1999-01-01

    The typical fair weather electric field at the ground is between -100 and -300 V/m. At the NASA Kennedy Space Center and US Air Force Cape Canaveral Air Station (KSC) the electric field at the ground sometimes reaches -400 to -1200 V/m within an hour or two after sunrise on days that otherwise seem to be fair weather. We refer to the enhanced negative electric fields as the "sunrise enhancement." To investigate the sunrise enhancement at KSC we measured the electric field (E) in the first few hundred meters above the ground before and during several sunrise enhancements. From these E soundings we can infer the presence of charge layers and determine their thickness and charge density.

  11. Communication: Control of chemical reactions using electric field gradients.

    PubMed

    Deshmukh, Shivaraj D; Tsori, Yoav

    2016-05-21

    We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.

  12. Electric field dependent spectroscopy of single nanocrystal systems

    NASA Astrophysics Data System (ADS)

    LeBlanc, Sharonda L. Johnson

    A suite of single molecule spectroscopic techniques and data analysis methods were implemented to explore the complex role of electric fields in single semiconductor nanocrystal photophysics. This dissertation spans the synthesis, characterization, biological applications, and photophysics of semiconductor nanocrystals. The core single molecule techniques employed in the current work include time-resolved fluorescence, time-correlated single photon counting, single molecule spectroscopy, and photon correlation spectroscopy. Various electrode devices were patterned to investigate the optical properties of single nanocrystal systems under an applied electric field. Electric field dependent spectroscopy and data analysis have revealed distributed kinetics and multiple charging of nanocrystals. In addition, interactions of nanocrystal excited states with plasmonic gold films have revealed strong enhancement of multiple exciton emission from single nanocrystals, and control by an applied electric field. The broader implications of this work can be extended to bioimaging, light harvesting, electro-optics, and lasing technologies.

  13. Imaging Local Electric Field Distribution by Plasmonic Impedance Microscopy.

    PubMed

    Wang, Yixian; Shan, Xiaonan; Wang, Shaopeng; Tao, Nongjian; Blanchard, Pierre-Yves; Hu, Keke; Mirkin, Michael V

    2016-02-02

    We report on imaging of local electric field on an electrode surface with plasmonic electrochemical impedance microscopy (P-EIM). The local electric field is created by putting an electrode inside a micropipet positioned over the electrode and applying a voltage between the two electrodes. We show that the distribution of the surface charge as well as the local electric field at the electrode surface can be imaged with P-EIM. The spatial distribution and the dependence of the local charge density and electric field on the distance between the micropipet and the surface are measured, and the results are compared with the finite element calculations. The work also demonstrates the possibility of integrating plasmonic imaging with scanning ion conductance microscopy (SICM) and other scanning probe microscopies.

  14. Electric field measurements during the Condor critical velocity experiment

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Pfaff, R. F.; Haerendel, G.

    1986-01-01

    The instrumentation of the Condor critical velocity Ba experiment (Wescott et al., 1986) for the measurements of the energetic particles and the electric field associated with a Ba explosion is described. The Ba explosion created a complex electric field pulse detected in situ by a single-axis double electric-field probe on a separate spacecraft. The measurements provide evidence of several important links in the critical-velocity chain, and are consistent with two hypotheses. The first hypothesis involves the creation of large polarization electric field due to charge separation; the second hypothesis implies a polarization of the beam by currents flowing across it. The chain of physical processes inferred from the observations is in agreement with most theories for the Alfven process.

  15. Enhanced Fair-Weather Electric Fields Soon After Sunrise

    NASA Technical Reports Server (NTRS)

    Marshall, T. C.; Rust, W. D.; Stolzenburg, M.; Roeder, W.; Krehbiel, P. R.

    1999-01-01

    The typical fair weather electric field at the ground is between -100 and -300 V/m. At the NASA Kennedy Space Center and US Air Force Cape Canaveral Air Station (KSC) the electric field at the ground sometimes reaches -400 to -1200 V/m within an hour or two after sunrise on days that otherwise seem to be fair weather. We refer to the enhanced negative electric fields as the "sunrise enhancement." To investigate the sunrise enhancement at KSC we measured the electric field (E) in the first few hundred meters above the ground before and during several sunrise enhancements. From these E soundings we can infer the presence of charge layers and determine their thickness and charge density.

  16. Electric field measurements during the Condor critical velocity experiment

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Pfaff, R. F.; Haerendel, G.

    1986-01-01

    The instrumentation of the Condor critical velocity Ba experiment (Wescott et al., 1986) for the measurements of the energetic particles and the electric field associated with a Ba explosion is described. The Ba explosion created a complex electric field pulse detected in situ by a single-axis double electric-field probe on a separate spacecraft. The measurements provide evidence of several important links in the critical-velocity chain, and are consistent with two hypotheses. The first hypothesis involves the creation of large polarization electric field due to charge separation; the second hypothesis implies a polarization of the beam by currents flowing across it. The chain of physical processes inferred from the observations is in agreement with most theories for the Alfven process.

  17. Theory and experiment for soap-film bridge in an electric field.

    PubMed

    Moulton, Derek E; Pelesko, John A

    2008-06-01

    Surface tension and electrostatic forces dominate the behavior of many micro and nano scale systems. Understanding interactions between these forces may therefore be of great utility in a number of engineering systems. We investigate one such interaction by subjecting an elastic membrane suspended between two parallel rings to an axially symmetric electric field. A model is formulated and analyzed and the effect of the field is characterized. Experimentally, the system is investigated using a soap-film bridge and a high voltage power source. Experimental observations verify the validity of the theory, in predicting both membrane profile as well as critical device length at which stability is lost.

  18. Controlling the electric field enhancement factor of photonic nanojets by using the magneto-optical effect

    NASA Astrophysics Data System (ADS)

    Khaleque, Abdul; Li, Ziyuan; Hattori, Haroldo T.

    2013-12-01

    In recent years, many researchers have studied photonic nanojets. These nanojets are created when an incident plane wave is focused into a narrow and high intensity emerging optical beam leaving a micro-object (e.g. microcylinder). These narrow beams may find applications in particle imaging and detection, optical sensors, enhanced Raman scattering, and particle manipulation. They also allow the projection of a particle to the far-field where it can be easily visualized. In this paper, it is shown that the electric field enhancement factor can be dynamically controlled by the application of an external intense magnetic flux density.

  19. Analysis of electric and magnetic fields leaking from induction heaters.

    PubMed

    Andreuccetti, D; Bini, M; Ignesti, A; Olmi, R; Rubino, N; Vanni, R

    1988-01-01

    Results are presented of an investigation on electric and magnetic fields leaking from inductive (magnetic) heaters that are used for thermal processing of high-power electron tubes and lasers in an industrial plant. Measurements of electric and magnetic fields were done using both commercially available and laboratory-developed instrumentation. Isotropic H-field sensors were developed to allow quantitative evaluation of high-intensity magnetic fields. Ten induction heaters with nominal A.C. power ranging from 2.5 kW to 15 kW and operating at frequencies between 300 kHz and 790 kHz were surveyed. Electric field strengths up to 8 kV/m and magnetic field strengths up to 20 A/m were measured.

  20. Effective critical electric field for runaway-electron generation.

    PubMed

    Stahl, A; Hirvijoki, E; Decker, J; Embréus, O; Fülöp, T

    2015-03-20

    In this Letter we investigate factors that influence the effective critical electric field for runaway-electron generation in plasmas. We present numerical solutions of the kinetic equation and discuss the implications for the threshold electric field. We show that the effective electric field necessary for significant runaway-electron formation often is higher than previously calculated due to both (1) extremely strong dependence of primary generation on temperature and (2) synchrotron radiation losses. We also address the effective critical field in the context of a transition from runaway growth to decay. We find agreement with recent experiments, but show that the observation of an elevated effective critical field can mainly be attributed to changes in the momentum-space distribution of runaways, and only to a lesser extent to a de facto change in the critical field.

  1. Electric field structures in thin films: formation and properties.

    PubMed

    Cassidy, Andrew; Plekan, Oksana; Balog, Richard; Dunger, Jack; Field, David; Jones, Nykola C

    2014-08-21

    A newly discovered class of molecular materials, so-called "spontelectrics", display spontaneous electric fields. Here we show that the novel properties of spontelectrics can be used to create composite spontelectrics, illustrating how electric fields in solid films may be structured on the nanoscale by combining layers of different spontelectric materials. This is demonstrated using the spontelectric materials nitrous oxide, toluene, isoprene, isopentane, and CF2Cl2. These yield a variety of tailored electric field structures, with individual layers harboring fields between 10(7) and 10(8) V/m. Fields may be of the same sign or of opposite sign, the latter enabling the creation of nanoscale potential wells. The formation of fields is followed using an established electron beam technique, employing the ASTRID synchrotron storage ring. The influence of temperature on heterolayer structures, displaying new Curie effects, and the nature of the interfacial region between different spontelectrics are also discussed.

  2. Drop oscillation and mass transfer in alternating electric fields

    SciTech Connect

    Carleson, T.E.

    1992-06-24

    In certain cases droplet direct contact heat transfer rates can be significantly enhanced by the application of an alternating electric field. This field can produce shape oscillations in a droplet which will enhance mixing. The theoretical evaluation of the effect of the interaction of the field with drop charge on the hydrodynamics has been completed for small amplitude oscillations. Previous work with a zero order perturbation method was followed up with a first order perturbation method to evaluate the effect of drop distortion on drop charge and field distribution. The first order perturbation results show secondary drop oscillations of four modes and two frequencies in each mode. The most significant secondary oscillation has the same mode and frequency as the second mode oscillation predicted from the first order perturbation work. The resonant frequency of all oscillations decrease with increasing electric field strength and drop charge. Work is currently underway to evaluate the heat transfer enhancement from an applied alternating electric field.

  3. Design of portable electric and magnetic field generators

    NASA Astrophysics Data System (ADS)

    Stewart, M. G.; Siew, W. H.; Campbell, L. C.; Stewart, M. G.; Siew, W. H.

    2000-11-01

    Electric and magnetic field generators capable of producing high-amplitude output are not readily available. This presents difficulties for electromagnetic compatibility testing of new measurement systems where these systems are intended to operate in a particularly hostile electromagnetic environment. A portable electric and a portable magnetic field generator having high pulsed field output are described in this paper. The output of these generators were determined using an electromagnetic-compatible measurement system. These generators allow immunity testing in the laboratory of electronic systems to very high electrical fields, as well as for functional verification of the electronic systems on site. In the longer term, the basic design of the magnetic field generator may be developed as the generator to provide the damped sinusoid magnetic field specified in IEC 61000-4-10, which is adopted in BS EN 61000-4-10.

  4. An auroral effect on the fair weather electric field

    NASA Technical Reports Server (NTRS)

    Hale, L. C.; Croskey, C. L.

    1979-01-01

    Evidence is presented for coupling between the upper and lower atmosphere by means of the shorting out of the vertical mesospheric electric field by auroral radiation, which causes a transfer of mesospheric potential to the lower atmosphere. Measurements were made by an electric field antenna which was part of a parachute-borne payload, launched by rocket from near Fairbanks, Alaska. Data obtained from quiet time observations indicate the normal low altitude electric field pattern, with a greater field at high altitudes, while observations at disturbed times show a small field at high altitudes and a greater field at low altitudes. Means for observing this effect at lower latitudes are also suggested. While the data obtained support the proposed mechanism, it is noted that other mechanisms, such as direct modulation by large amounts of solar cosmic rays and aurorally produced charge separation, may also be important.

  5. Fundamental Studies of Electric-Field-Induced Coherent Raman Scattering

    DTIC Science & Technology

    2011-06-07

    mechanisms of nanosecond- pulsed dielectric barrier discharges generated in open air. Our experimental observations have revealed that, in the pre...dynamics in nanosecond- pulsed discharges . a) Electric-field-induced coherent Raman scattering (E-CRS) In this section, I describe the...the electric field in hydrogen. With E-CRS method, our group has revealed very fast discharge dynamics in repetitively pulsed nanosecond discharges [4

  6. A New Electric Field in Asymmetric Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Malakit, K.; Shay, M. A.; Cassak, P.; Ruffolo, D. J.

    2013-12-01

    Magnetic reconnection is an important plasma process that drives the dynamics of the plasma in the magnetosphere and plays a crucial role in the interaction between magnetospheric and magnetosheath plasma. It has been shown that when a reconnection occurs in a collisionless plasma, it exhibits the Hall electric field, an in-plane electric field structure pointing toward the X-line. In this work, we show that when the reconnection has asymmetric inflow conditions such as the reconnection at the day-side magnetopause, a new in-plane electric field structure can exist. This electric field points away from the X-line and is distinct from the known Hall electric field. We argue that the origin of the electric field is associated with the physics of finite Larmor radius. A theory and predictions of the electric field properties are presented and backed up by results from fully kinetic particle-in-cell simulations of asymmetric reconnection with various inflow conditions. Under normal day-side reconnection inflow conditions, the electric field is expected to occur on the magnetospheric side of the X-line pointing Earthward. Hence, it has a potential to be used as a signature for satellites, such as the upcoming Magnetospheric Multi-Scale (MMS) mission, to locate the reconnection sites at the day-side magnetopause. This research was supported by the postdoctoral research sponsorship of Mahidol University (KM), NSF grants ATM-0645271 - Career Award (MAS) and AGS-0953463 (PAC), NASA grants NNX08A083G - MMS IDS, NNX11AD69G, and NNX13AD72G (MAS) and NNX10AN08A (PAC), and the Thailand Research Fund (DR).

  7. Electric Field Tunable Microwave and MM-wave Ferrite Devices

    DTIC Science & Technology

    2010-04-30

    garnet (YIG), nickel zinc ferrite , or barium ferrite for the magnetic phase and lead zirconate titanate (PZT), lead magnesium niobate- lead titanate...Electric Field Tunable Microwave and MM-wave Ferrite Devices (N00014-06-01-0167) Period of Performance: May 1, 2006-April 30, 2010 Principal...composites consisting of ferrites and ferroeleectrics. When such composite is subjected to an electric field E, the mechanical deformation due to

  8. Effects Of Electric Field On Hydrocarbon-Fueled Flames

    NASA Technical Reports Server (NTRS)

    Yuan, Z.-G.; Hegde, U.

    2003-01-01

    It has been observed that flames are susceptible to electric fields that are much weaker than the breakdown field strength of the flame gases. When an external electric field is imposed on a flame, the ions generated in the flame reaction zone drift in the direction of the electric forces exerted on them. The moving ions collide with the neutral species and change the velocity distribution in the affected region. This is often referred to as ionic wind effect. In addition, the removal of ions from the flame reaction zone can alter the chemical reaction pathway of the flame. On the other hand, the presence of space charges carried by moving ions affects the electric field distribution. As a result, the flame often changes its shape, location and color once an external electric field is applied. The interplay between the flame movement and the change of electric field makes it difficult to determine the flame location for a given configuration of electrodes and fuel source. In normal gravity, the buoyancy-induced flow often complicates the problem and hinders detailed study of the interaction between the flame and the electric field. In this work, the microgravity environment established at the 2.2 Second Drop Tower at the NASA Glenn Research Center is utilized to effectively remove the buoyant acceleration. The interaction between the flame and the electric field is studied in a one-dimensional domain. A specially designed electrode makes flame current measurements possible; thus, the mobility of ions, ion density, and ionic wind effect can be evaluated.

  9. Biological electric fields and rate equations for biophotons.

    PubMed

    Alvermann, M; Srivastava, Y N; Swain, J; Widom, A

    2015-04-01

    Biophoton intensities depend upon the squared modulus of the electric field. Hence, we first make some general estimates about the inherent electric fields within various biosystems. Generally, these intensities do not follow a simple exponential decay law. After a brief discussion on the inapplicability of a linear rate equation that leads to strict exponential decay, we study other, nonlinear rate equations that have been successfully used for biosystems along with their physical origins when available.

  10. Ionizing gas breakdown waves in strong electric fields.

    NASA Technical Reports Server (NTRS)

    Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.

    1972-01-01

    A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.

  11. Use of the Atmospheric Electric Field for Terrain Avoidance

    DTIC Science & Technology

    1975-04-01

    realistic enough to yield results applicable in the real world? And if the po- tential gradients are found to be as predicted b,,r Poisson’s equation...electric field is believed to be realistic "since the application of the atmospheric electric field for stabilization or terrain avoidance will be...phenomena) that causes the fluctuations in atmospheric potential (or potential gradient) that makes terrain avoidance or any other application of the

  12. Asymmetric cancer-cell filopodium growth induced by electric-fields in a microfluidic culture chip.

    PubMed

    Wang, Chun-Chieh; Kao, Yu-Chiu; Chi, Pei-Yin; Huang, Ching-Wen; Lin, Jiunn-Yuan; Chou, Chia-Fu; Cheng, Ji-Yen; Lee, Chau-Hwang

    2011-02-21

    We combine a micro-fluidic electric-field cell-culture (MEC) chip with structured-illumination nano-profilometry (SINAP) to quantitatively study the variations of cancer cell filopodia under external direct-current electric field (dcEF) stimulations. Because the lateral resolution of SINAP is better than 150 nm in bright-field image modality, filopodia with diameters smaller than 200 nm can be observed clearly without fluorescent labeling. In the MEC chip, a homogeneous EF is generated inside the culture area that simulates the endogenous EF environment. With this MEC chip-SINAP system, we directly observe and quantify the biased growth of filopodia of lung cancer cells toward the cathode. The epidermal growth factor receptors around the cell edges are also redistributed to the cathodal side. These results suggest that cancer-cell filopodia respond to the changes in EFs in the microenvironment.

  13. Preparation and electrical properties of dense micro-cermets made of nickel ferrite and metallic copper

    NASA Astrophysics Data System (ADS)

    Baco-Carles, Valérie; Pasquet, Isabelle; Laurent, Véronique; Gabriel, Armand; Tailhades, Philippe

    2009-08-01

    Dense micro-cermets made of nickel ferrites and copper micrometric particles were obtained from partial reduction under hydrogenated atmosphere at 350 °C of mixed copper nickel ferrites, and sintering in nitrogen at 980 °C. The small copper particles are homogeneous in size and well dispersed in the spinel oxide matrix. No exudation of copper metal was observed after sintering. The micro-cermets prepared are semi-conducting materials with electrical conductivity lying from 44 to 130 S/cm at 980 °C. Their overall characteristics make them interesting for inert anodes dedicated to aluminium electrolysis in melted cryolite.

  14. Effects of high external electric fields on protein conformation

    NASA Astrophysics Data System (ADS)

    Pompa, Pier Paolo; Bramanti, Alessandro; Maruccio, Giuseppe; del Mercato, Loretta Laureana; Chiuri, Rocco; Cingolani, Roberto; Rinaldi, Ross

    2005-06-01

    Resistance of biomolecules to high electric fields is a main concern for nanobioelectronics/nanobiosensing applications, and it is also a relevant issue from a fundamental perspective, to understand the dielectric properties and structural dynamics of proteins. In nanoscale devices, biomolecules may experience electric fields as high as 107 V/m in order to elicit charge transport/transfer. Understanding the effects of such fields on their structural integrity is thus crucial to assess the reliability of biomolecular devices. In this study, we show experimental evidence for the retention of native-like fold pattern by proteins embedded in high electric fields. We have tested the metalloprotein azurin, deposited onto SiO2 substrates in air with proper electrode configuration, by applying high static electric fields (up to 106-107 V/m). The effects on the conformational properties of protein molecules have been determined by means of intrinsic fluorescence measurements. Experimental results indicate that no significant field-induced conformational alteration occurs. This behavior is also discussed and supported by theoretical predictions of the intrinsic intra-protein electric fields. As the general features of such inner fields are not peculiar of azurin, the conclusions presented here should have general validity.

  15. Responsive behavior of polyampholyte brushes in electric fields

    NASA Astrophysics Data System (ADS)

    Cao, Qianqian; Li, Lujuan; Zuo, Chuncheng; Huang, Fengli; Hu, Dongmei

    2016-12-01

    We conducted coarse-grained molecular dynamics simulations to study the responsive behaviors of polyampholyte brushes (PABs) under external electric fields. The effects of charge sequence, chain rigidity and electric field strength on the conformational transition and local structures of grafted chains were addressed systematically. Without electric field, the calculations indicate that the thickness of the PABs is smaller compared to polyelectrolyte brushes (PEBs). The presence of electric field leads to inconsistency of densities between negatively and positively charged monomers except for the alternating brush. Counterions from the PABs can diffuse inside or outside the brush. Unlike the PABs, to separate the polyelectrolytes and their counterions the electric field needs to overcome the osmotic pressure of counterions. The critical field which induces the extension of the flexible PABs is much larger than the PEBs. Meanwhile, it was also found that the critical field which induces the collapse of the PABs decreases as the block length increases. In the limit of strong field studied, the chains with longer blocks are in a local extended state. For diblock brushes, once oppositely charged blocks in a single chain are separated, the chain will become straighter due to strong electrostatic repulsion in intrablock.

  16. Electric Fields and Magnetic Fields in the Plasmasphere: A Perspective From CLUSTER and IMAGE

    NASA Astrophysics Data System (ADS)

    Matsui, Hiroshi; Foster, John C.; Carpenter, Donald L.; Dandouras, Iannis; Darrouzet, Fabien; de Keyser, Johan; Gallagher, Dennis L.; Goldstein, Jerry; Puhl-Quinn, Pamela A.; Vallat, Claire

    2009-05-01

    The electric field and magnetic field are basic quantities in the plasmasphere measured since the 1960s. In this review, we first recall conventional wisdom and remaining problems from ground-based whistler measurements. Then we show scientific results from Cluster and Image, which are specifically made possible by newly introduced features on these spacecraft, as follows. 1. In situ electric field measurements using artificial electron beams are successfully used to identify electric fields originating from various sources. 2. Global electric fields are derived from sequences of plasmaspheric images, revealing how the inner magnetospheric electric field responds to the southward interplanetary magnetic fields and storms/substorms. 3. Understanding of sub-auroral polarization stream (SAPS) or sub-auroral ion drifts (SAID) are advanced through analysis of a combination of magnetospheric and ionospheric measurements from Cluster, Image, and DMSP. 4. Data from multiple spacecraft have been used to estimate magnetic gradients for the first time.

  17. [Study on dewatering of activated sludge under applied electric field].

    PubMed

    Ji, Xue-Yuan; Wang, Yi-Li; Feng, Jing

    2012-12-01

    For an electro-dewatering process of activated sludge (AS), the effect of pH and conductivity of AS, flocculation conditioning and operation factors of horizontal electric field (voltage magnitude, method of applying electric field and distance between plates) were investigated, and the corresponding optimum electro-dewatering conditions were also obtained. The results showed that the best electro-dewatering effect was achieved for AS without change of its pH value (6.93) and conductivity (1.46 mS x cm(-1)). CPAM conditioning could lead to the increase of 30%-40% in the dewatering rate and accelerate the dewatering process, whereas a slight increase in the electro-dewatering rate. The electro-dewatering rate for conditioned AS reached 83.12% during an electric field applied period of 60 minutes, while this rate for original AS could be 75.31% even the electric field applied period extended to 120 minutes. The delay of applying the electric field had an inhibition effect on the AS electro-dewatering rate. Moreover, the optimum conditions for AS electro-dewatering were followed: CPAM dose of 9 g x kg(-1), electric field strength of 600 V x m(-1), distance between the two plates of 40 mm, dehydration time of 60 minutes. Under above optimum conditions the AS electro-dewatering rate could approach to 85.33% and the moisture content in AS decreased from 99.30% to 95.15% accordingly.

  18. The Dynamics of Ultrasonically Levitated Drops in an Electric Field

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Holt, R. G.; Thiessen, D. B.

    1996-01-01

    Ultrasonic and electrostatic levitation techniques have allowed the experimental investigation of the nonlinear oscillatory dynamics of free droplets with diameter between 0.1 and 0.4 cm. The measurement of the resonance frequencies of the first three normal modes of large amplitude shape oscillations in an electric field of varying magnitude has been carried out with and without surface charges for weakly conducting liquids in air. These oscillations of nonspherical levitated drops have been driven by either modulating the ultrasonic field or by using a time-varying electric field, and the free decay from the oscillatory state has been recorded. A decrease in the resonance frequency of the driven fundamental quadrupole mode has been measured for increasing oblate deformation in the absence of an electric field. Similarly, a decrease in this frequency has also been found for increasing DC electric field magnitude. A soft nonlinearity exists in the amplitude dependence of the resonant mode frequencies for freely decaying as well as ultrasonically and electrically driven uncharged drops. This decrease in resonance frequency is accentuated by the presence of free surface charge on the drop. Subharmonic resonance excitation has been observed for drops in a time-varying electric field, and hysteresis exists for resonant modes driven to large amplitude. Mode coupling from lower-order resonances to higher-order modes has been found to be very weak, even for fairly large amplitude shape oscillations. Most of these results are in general agreement with predictions from recent analytical and numerical investigations.

  19. Migration of amoeba cells in an electric field

    NASA Astrophysics Data System (ADS)

    Guido, Isabella; Bodenschatz, Eberhard

    2015-03-01

    Exogenous and endogenous electric fields play a role in cell physiology as a guiding mechanism for the orientation and migration of cells. Electrotaxis of living cells has been observed for several cell types, e.g. neurons, fibroblasts, leukocytes, neural crest cells, cancer cells. Dictyostelium discoideum (Dd), an intensively investigated chemotactic model organism, also exhibits a strong electrotactic behavior moving toward the cathode under the influence of electric fields. Here we report experiments on the effects of DC electric fields on the directional migration of Dd cells. We apply the electric field to cells seeded into microfluidic devices equipped with agar bridges to avoid any harmful effects of the electric field on the cells (ions formation, pH changes, etc.) and a constant flow to prevent the build-up of chemical gradient that elicits chemotaxis. Our results show that the cells linearly increase their speed over time when a constant electric field is applied for a prolonged duration (2 hours). This novel phenomenon cannot be attributed to mechanotaxis as the drag force of the electroosmotic flow is too small to produce shear forces that can reorient cells. It is independent of the cellular developmental stage and to our knowledge, it was not observed in chemotaxis. This work is supported by MaxSynBio project of the Max Planck Society.

  20. Effect of the radial electric field on turbulence

    SciTech Connect

    Carreras, B.A.; Lynch, V.E.

    1990-01-01

    For many years, the neoclassical transport theory for three- dimensional magnetic configurations, such as magnetic mirrors, ELMO Bumpy Tori (EBTs), and stellarators, has recognized the critical role of the radial electric field in the confinement. It was in these confinement devices that the first experimental measurements of the radial electric field were made and correlated with confinement losses. In tokamaks, the axisymmetry implies that the neoclassical fluxes are ambipolar and, as a consequence, independent of the radial electric field. However, axisymmetry is not strict in a tokamak with turbulent fluctuations, and near the limiter ambipolarity clearly breaks down. Therefore, the question of the effect of the radial electric field on tokamak confinement has been raised in recent years. In particular, the radial electric field has been proposed to explain the transition from L-mode to H-mode confinement. There is some initial experimental evidence supporting this type of explanation, although there is not yet a self-consistent theory explaining the generation of the electric field and its effect on the transport. Here, a brief review of recent results is presented. 27 refs., 4 figs.

  1. All-organic electrostrictive polymer composites with low driving electrical voltages for micro-fluidic pump applications

    PubMed Central

    Le, Minh Quyen; Capsal, Jean-Fabien; Galineau, Jérémy; Ganet, Florent; Yin, Xunqian; Yang, Mingchia (Dawn); Chateaux, Jean-François; Renaud, Louis; Malhaire, Christophe; Cottinet, Pierre-Jean; Liang, Richard

    2015-01-01

    This paper focuses on the improvement of a relaxor ferroelectric terpolymer, i.e., poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)], filled with a bis(2-ethylhexyl) phthalate (DEHP). The developed material gave rise to a significantly increased longitudinal electrostrictive strain, as well as an increased mechanical energy density under a relatively low electric field. These features were attributed to the considerably enhanced dielectric permittivity and a decreased Young modulus as a result of the introduction of only small DEHP plasticizer molecules. In addition, the plasticizer-filled terpolymer only exhibited a slight decrease of the dielectric breakdown strength, which was a great advantage with respect to the traditional polymer-based electrostrictive composites. More importantly, the approach proposed herein is promising for the future development and scale-up of new high-performance electrostrictive dielectrics under low applied electrical fields through modification simply by blending with a low-cost plasticizer. An experimental demonstration based on a flexible micro-fluidic application is described at the end of this paper, confirming the attractive characteristics of the proposed materials as well as the feasibility of integrating them as micro-actuators in small-scale devices. PMID:26139015

  2. All-organic electrostrictive polymer composites with low driving electrical voltages for micro-fluidic pump applications

    NASA Astrophysics Data System (ADS)

    Le, Minh Quyen; Capsal, Jean-Fabien; Galineau, Jérémy; Ganet, Florent; Yin, Xunqian; Yang, Mingchia (Dawn); Chateaux, Jean-François; Renaud, Louis; Malhaire, Christophe; Cottinet, Pierre-Jean; Liang, Richard

    2015-07-01

    This paper focuses on the improvement of a relaxor ferroelectric terpolymer, i.e., poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)], filled with a bis(2-ethylhexyl) phthalate (DEHP). The developed material gave rise to a significantly increased longitudinal electrostrictive strain, as well as an increased mechanical energy density under a relatively low electric field. These features were attributed to the considerably enhanced dielectric permittivity and a decreased Young modulus as a result of the introduction of only small DEHP plasticizer molecules. In addition, the plasticizer-filled terpolymer only exhibited a slight decrease of the dielectric breakdown strength, which was a great advantage with respect to the traditional polymer-based electrostrictive composites. More importantly, the approach proposed herein is promising for the future development and scale-up of new high-performance electrostrictive dielectrics under low applied electrical fields through modification simply by blending with a low-cost plasticizer. An experimental demonstration based on a flexible micro-fluidic application is described at the end of this paper, confirming the attractive characteristics of the proposed materials as well as the feasibility of integrating them as micro-actuators in small-scale devices.

  3. Vacuum radiation induced by time dependent electric field

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian; Gu, Yu-qiu

    2017-04-01

    Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  4. Propagation of Magnetic Fields from Electrical Domestic Appliances

    NASA Astrophysics Data System (ADS)

    Orlova, K. N.; Gaidamak, M. A.; Borovikov, I. F.

    2016-08-01

    The article presents a research into propagation of magnetic fields from electrical domestic devices. A safe distance at which magnetic induction does not exceed the background level is determined for each type of devices. It is proved that there are two stages of increasing magnetic induction as the distance from the source increases. At the first stage magnetic induction rises and electromagnetic field is formed. At the second stage exponential decrease of magnetic field induction takes place. Mathematical regularities of propagation of magnetic field from electrical domestic devices are experimentally educed.

  5. Large amplitude middle atmospheric electric fields - Fact or fiction?

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Siefring, C. L.; Pfaff, R. F., Jr.

    1983-01-01

    An analysis of the measurements of large apparent dc fields in the middle atmosphere, previously gathered by two sounding rockets, shows these fields to be spurious. In the case of one of the rockets, the evidence presented suggests that the measured electric fields, aligned with the rocket's velocity vector, may be due to a negatively charged wake. A comparison of measurements made by various electric field booms also suggests that the insulating boom coatings in one experiment may have affected the results obtained. It is recommended that insulating coatings should not be used at mesospheric altitudes, because of the detrimental effects that frictional charging may have.

  6. Modelling of induced electric fields based on incompletely known magnetic fields

    NASA Astrophysics Data System (ADS)

    Laakso, Ilkka; De Santis, Valerio; Cruciani, Silvano; Campi, Tommaso; Feliziani, Mauro

    2017-08-01

    Determining the induced electric fields in the human body is a fundamental problem in bioelectromagnetics that is important for both evaluation of safety of electromagnetic fields and medical applications. However, existing techniques for numerical modelling of induced electric fields require detailed information about the sources of the magnetic field, which may be unknown or difficult to model in realistic scenarios. Here, we show how induced electric fields can accurately be determined in the case where the magnetic fields are known only approximately, e.g. based on field measurements. The robustness of our approach is shown in numerical simulations for both idealized and realistic scenarios featuring a personalized MRI-based head model. The approach allows for modelling of the induced electric fields in biological bodies directly based on real-world magnetic field measurements.

  7. Oscillating magnetic field-actuated microvalves for micro- and nanofluidics

    NASA Astrophysics Data System (ADS)

    Ghosh, Santaneel; Yang, Chao; Cai, Tong; Hu, Zhibing; Neogi, Arup

    2009-07-01

    The feasibility of using tunable magnetic nanoparticles embedded in cylindrical hydrogel materials as a flow regulator via thermo-mechanical gating is studied within microfluidic channels. Ferromagnetic nanoparticles (Fe3O4) encapsulated within a thermo-sensitive polymer network (-poly(N-isopropylacrylamide) (PNIPAM)) was polymerized inside 300 µm diameter micro-capillary tubes. An oscillating magnetic field range 20-125 Oe, (100-1000 kHz) was used to induce heat and control the valving action. Valving action was effectively regulated by modulating the magnetically responsive PNIPAM networks (MPNIPAM) and thereby physically regulating the harmonics (swelling and shrinking) of the polymer monolith inside the microchannel. Magnetic properties in terms of saturation magnetization, remanence and coercivity of the designed system have been extracted for data accuracy. The optimum concentration of NIPAM monomer in the polymer matrix and the embedded nanoparticles yield ~80% volume shrinkage inside the microchannel, which is close to the undoped PNIPAM system, without compromising the oscillating field induced heating. Very importantly, the oscillating field-actuated de-swelling response time is ~3 s, which is significantly faster than the thermal actuation, and in addition the microvalve exhibits a faster response time compared with the macrovalve (MPNIPAM monolith inside 1500 µm diameter channel). The enhanced shrinkage rate and the actuation efficiency might be ideal for many biomedical applications, including synergistic application of heat and sustained releasing capability of chemotherapeutic agents.

  8. Electric Field Screening with Backflow at Pulsar Polar Cap

    NASA Astrophysics Data System (ADS)

    Kisaka, Shota; Asano, Katsuaki; Terasawa, Toshio

    2016-09-01

    Recent γ-ray observations suggest that particle acceleration occurs at the outer region of the pulsar magnetosphere. The magnetic field lines in the outer acceleration region (OAR) are connected to the neutron star surface (NSS). If copious electron-positron pairs are produced near the NSS, such pairs flow into the OAR and screen the electric field there. To activate the OAR, the electromagnetic cascade due to the electric field near the NSS should be suppressed. However, since a return current is expected along the field lines through the OAR, the outflow extracted from the NSS alone cannot screen the electric field just above the NSS. In this paper, we analytically and numerically study the electric field screening at the NSS, taking into account the effects of the backflowing particles from the OAR. In certain limited cases, the electric field is screened without significant pair cascade if only ultra-relativistic particles (γ \\gg 1) flow back to the NSS. On the other hand, if electron-positron pairs with a significant number density and mildly relativistic temperature, expected to distribute in a wide region of the magnetosphere, flow back to the NSS, these particles adjust the current and charge densities so that the electric field can be screened without pair cascade. We obtain the condition needed for the number density of particles to screen the electric field at the NSS. We also find that in the ion-extracted case from the NSS, bunches of particles are ejected to the outer region quasi-periodically, which is a possible mechanism of observed radio emission.

  9. Ponderomotive Force in the Presence of Electric Fields

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Krivorutsky, E. N.

    2013-01-01

    This paper presents averaged equations of particle motion in an electromagnetic wave of arbitrary frequency with its wave vector directed along the ambient magnetic field. The particle is also subjected to an E cross B drift and a background electric field slowly changing in space and acting along the magnetic field line. The fields, wave amplitude, and the wave vector depend on the coordinate along the magnetic field line. The derivations of the ponderomotive forces are done by assuming that the drift velocity in the ambient magnetic field is comparable to the particle velocity. Such a scenario leads to new ponderomotive forces, dependent on the wave magnetic field intensity, and, as a result, to the additional energy exchange between the wave and the plasma particles. It is found that the parallel electric field can lead to the change of the particle-wave energy exchange rate comparable to that produced by the previously discussed ponderomotive forces.

  10. Ponderomotive Force in the Presence of Electric Fields

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Krivorutsky, E. N.

    2013-01-01

    This paper presents averaged equations of particle motion in an electromagnetic wave of arbitrary frequency with its wave vector directed along the ambient magnetic field. The particle is also subjected to an E cross B drift and a background electric field slowly changing in space and acting along the magnetic field line. The fields, wave amplitude, and the wave vector depend on the coordinate along the magnetic field line. The derivations of the ponderomotive forces are done by assuming that the drift velocity in the ambient magnetic field is comparable to the particle velocity. Such a scenario leads to new ponderomotive forces, dependent on the wave magnetic field intensity, and, as a result, to the additional energy exchange between the wave and the plasma particles. It is found that the parallel electric field can lead to the change of the particle-wave energy exchange rate comparable to that produced by the previously discussed ponderomotive forces.

  11. Electric field and temperature effects in irradiated MOSFETs

    NASA Astrophysics Data System (ADS)

    Silveira, M. A. G.; Santos, R. B. B.; Leite, F. G.; Araújo, N. E.; Cirne, K. H.; Melo, M. A. A.; Rallo, A.; Aguiar, Vitor. A. P.; Aguirre, F.; Macchione, E. L. A.; Added, N.; Medina, N. H.

    2016-07-01

    Electronic devices exposed to ionizing radiation exhibit degradation on their electrical characteristics, which may compromise the functionality of the device. Understanding the physical phenomena responsible for radiation damage, which may be specific to a particular technology, it is of extreme importance to develop methods for testing and recovering the devices. The aim of this work is to check the influence of thermal annealing processes and electric field applied during irradiation of Metal Oxide Semiconductor Field Effect Transistors (MOSFET) in total ionizing dose experiments analyzing the changes in the electrical parameters in these devices

  12. Electric field and temperature effects in irradiated MOSFETs

    SciTech Connect

    Silveira, M. A. G. Santos, R. B. B.; Leite, F. G.; Araújo, N. E.; Cirne, K. H.; Melo, M. A. A.; Rallo, A.; Aguiar, Vitor A. P.; Aguirre, F.; Macchione, E. L. A.; Added, N.; Medina, N. H.

    2016-07-07

    Electronic devices exposed to ionizing radiation exhibit degradation on their electrical characteristics, which may compromise the functionality of the device. Understanding the physical phenomena responsible for radiation damage, which may be specific to a particular technology, it is of extreme importance to develop methods for testing and recovering the devices. The aim of this work is to check the influence of thermal annealing processes and electric field applied during irradiation of Metal Oxide Semiconductor Field Effect Transistors (MOSFET) in total ionizing dose experiments analyzing the changes in the electrical parameters in these devices.

  13. Electric Field-Responsive Mesoporous Suspensions: A Review

    PubMed Central

    Kwon, Seung Hyuk; Piao, Shang Hao; Choi, Hyoung Jin

    2015-01-01

    This paper briefly reviews the fabrication and electrorheological (ER) characteristics of mesoporous materials and their nanocomposites with conducting polymers under an applied electric field when dispersed in an insulating liquid. Smart fluids of electrically-polarizable particles exhibit a reversible and tunable phase transition from a liquid-like to solid-like state in response to an external electric field of various strengths, and have potential applications in a variety of active control systems. The ER properties of these mesoporous suspensions are explained further according to their dielectric spectra in terms of the flow curve, dynamic moduli, and yield stress. PMID:28347119

  14. Low magnetic Johnson noise electric field plates for precision measurement

    NASA Astrophysics Data System (ADS)

    Rabey, I. M.; Devlin, J. A.; Hinds, E. A.; Sauer, B. E.

    2016-11-01

    We describe a parallel pair of high voltage electric field plates designed and constructed to minimise magnetic Johnson noise. They are formed by laminating glass substrates with a commercially available polyimide (Kapton) tape, covered with a thin gold film. Tested in vacuum, the outgassing rate is less than 5 × 10-5 mbar l/s. The plates have been operated at electric fields up to 8.3 kV/cm, when the leakage current is at most a few hundred pA. The design is discussed in the context of a molecular spin precession experiment to measure the permanent electric dipole moment of the electron.

  15. Internal electric field densities of metal nanoshells.

    PubMed

    Schelm, Stefan; Smith, Geoff B

    2005-02-10

    The internal field patterns for gold shells filled with the same material as the surrounding medium are calculated with Mie theory and in the quasistatic approximation and their properties compared to the response of homogeneous spheres and metallic rings. One major difference between the sphere and shell case is that the areas of highest field enhancement in metallic shells are located perpendicular to the incident polarization, whereas for metallic spheres they are along the polarization direction. Recent results based on the discrete dipole approximation (DDA) are shown to be misleading, which might be due to the use of a too coarse grid size. We also show that the type of resonance and the associated internal field pattern (low or high energy) has a strong impact on the external fields.

  16. Static electric field enhancement in nanoscale structures

    SciTech Connect

    Lepetit, Bruno Lemoine, Didier; Márquez-Mijares, Maykel

    2016-08-28

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  17. Static electric field enhancement in nanoscale structures

    NASA Astrophysics Data System (ADS)

    Lepetit, Bruno; Lemoine, Didier; Márquez-Mijares, Maykel

    2016-08-01

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  18. Electronic Properties of Capped Carbon Nanotubes under an Electric Field: Inhomogeneous Electric-Field Screening Induced by Bond Alternation

    NASA Astrophysics Data System (ADS)

    Yamanaka, Ayaka; Okada, Susumu

    2013-06-01

    We study the electronic properties of capped carbon nanotubes under an electric field by investigating their electrostatic potentials, total energies, and energy gaps under a parallel electric field, based on the density functional theory with effective screening medium method. We find that, in the capped carbon nanotubes, screening against the external electric field strongly depends on local atomic arrangement due to the inhomogeneous charge distribution arising from its bond alternation induced by the pentagonal rings in the cap region. In the case of armchair nanotubes, we find that the relative permittivity and energy gap between the highest occupied and the lowest unoccupied states oscillate in triple periodicity in their units with respect to the length. The electric field induces the charge redistribution in which the charge accumulation and depletion only occur around the pentagonal rings at or vicinity of the top/bottom of the nanotubes.

  19. Report on Non-Contact DC Electric Field Sensors

    SciTech Connect

    Miles, R; Bond, T; Meyer, G

    2009-06-16

    This document reports on methods used to measure DC electrostatic fields in the range of 100 to 4000 V/m using a non-contact method. The project for which this report is written requires this capability. Non-contact measurements of DC fields is complicated by the effect of the accumulation of random space-charges near the sensors which interfere with the measurement of the field-of-interest and consequently, many forms of field measurements are either limited to AC measurements or use oscillating devices to create pseudo-AC fields. The intent of this document is to report on methods discussed in the literature for non-contact measurement of DC fields. Electric field meters report either the electric field expressed in volts per distance or the voltage measured with respect to a ground reference. Common commercial applications for measuring static (DC) electric fields include measurement of surface charge on materials near electronic equipment to prevent arcing which can destroy sensitive electronic components, measurement of the potential for lightning to strike buildings or other exposed assets, measurement of the electric fields under power lines to investigate potential health risks from exposure to EM fields and measurement of fields emanating from the brain for brain diagnostic purposes. Companies that make electric field sensors include Trek (Medina, NY), MKS Instruments, Boltek, Campbell Systems, Mission Instruments, Monroe Electronics, AlphaLab, Inc. and others. In addition to commercial vendors, there are research activities continuing in the MEMS and optical arenas to make compact devices using the principles applied to the larger commercial sensors.

  20. Reversible electric-field control of magnetization at oxide interfaces

    NASA Astrophysics Data System (ADS)

    Cuellar, F. A.; Liu, Y. H.; Salafranca, J.; Nemes, N.; Iborra, E.; Sanchez-Santolino, G.; Varela, M.; Hernandez, M. Garcia; Freeland, J. W.; Zhernenkov, M.; Fitzsimmons, M. R.; Okamoto, S.; Pennycook, S. J.; Bibes, M.; Barthélémy, A.; Te Velthuis, S. G. E.; Sefrioui, Z.; Leon, C.; Santamaria, J.

    2014-06-01

    Electric-field control of magnetism has remained a major challenge which would greatly impact data storage technology. Although progress in this direction has been recently achieved, reversible magnetization switching by an electric field requires the assistance of a bias magnetic field. Here we take advantage of the novel electronic phenomena emerging at interfaces between correlated oxides and demonstrate reversible, voltage-driven magnetization switching without magnetic field. Sandwiching a non-superconducting cuprate between two manganese oxide layers, we find a novel form of magnetoelectric coupling arising from the orbital reconstruction at the interface between interfacial Mn spins and localized states in the CuO2 planes. This results in a ferromagnetic coupling between the manganite layers that can be controlled by a voltage. Consequently, magnetic tunnel junctions can be electrically toggled between two magnetization states, and the corresponding spin-dependent resistance states, in the absence of a magnetic field.

  1. Ionisation of a quantum dot by electric fields

    SciTech Connect

    Eminov, P A; Gordeeva, S V

    2012-08-31

    We have derived analytical formulas for differential and total ionisation probabilities of a two-dimensional quantum dot by a constant electric field. In the adiabatic approximation, we have calculated the probability of this process in the field of a plane electromagnetic wave and in a superposition of constant and alternating electric fields. The imaginary-time method is used to obtain the momentum distribution of the ionisation probability of a bound system by an intense field generated by a superposition of parallel constant and alternating electric fields. The total probability of the process per unit time is calculated with exponential accuracy. The dependence of the results obtained on the characteristic parameters of the problem is investigated. (laser applications and other topics in quantum electronics)

  2. Electric field-induced softening of alkali silicate glasses

    NASA Astrophysics Data System (ADS)

    McLaren, C.; Heffner, W.; Tessarollo, R.; Raj, R.; Jain, H.

    2015-11-01

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  3. Full 180° Magnetization Reversal with Electric Fields

    PubMed Central

    Wang, J. J.; Hu, J. M.; Ma, J.; Zhang, J. X.; Chen, L. Q.; Nan, C. W.

    2014-01-01

    Achieving 180° magnetization reversal with an electric field rather than a current or magnetic field is a fundamental challenge and represents a technological breakthrough towards new memory cell designs. Here we propose a mesoscale morphological engineering approach to accomplishing full 180° magnetization reversals with electric fields by utilizing both the in-plane piezostrains and magnetic shape anisotropy of a multiferroic heterostructure. Using phase-field simulations, we examined a patterned single-domain nanomagnet with four-fold magnetic axis on a ferroelectric layer with electric-field-induced uniaxial strains. We demonstrated that the uniaxial piezostrains, if non-collinear to the magnetic easy axis of the nanomagnet at certain angles, induce two successive, deterministic 90° magnetization rotations, thereby leading to full 180° magnetization reversals. PMID:25512070

  4. Reversible electric-field control of magnetization at oxide interfaces.

    PubMed

    Cuellar, F A; Liu, Y H; Salafranca, J; Nemes, N; Iborra, E; Sanchez-Santolino, G; Varela, M; Garcia Hernandez, M; Freeland, J W; Zhernenkov, M; Fitzsimmons, M R; Okamoto, S; Pennycook, S J; Bibes, M; Barthélémy, A; te Velthuis, S G E; Sefrioui, Z; Leon, C; Santamaria, J

    2014-06-23

    Electric-field control of magnetism has remained a major challenge which would greatly impact data storage technology. Although progress in this direction has been recently achieved, reversible magnetization switching by an electric field requires the assistance of a bias magnetic field. Here we take advantage of the novel electronic phenomena emerging at interfaces between correlated oxides and demonstrate reversible, voltage-driven magnetization switching without magnetic field. Sandwiching a non-superconducting cuprate between two manganese oxide layers, we find a novel form of magnetoelectric coupling arising from the orbital reconstruction at the interface between interfacial Mn spins and localized states in the CuO2 planes. This results in a ferromagnetic coupling between the manganite layers that can be controlled by a voltage. Consequently, magnetic tunnel junctions can be electrically toggled between two magnetization states, and the corresponding spin-dependent resistance states, in the absence of a magnetic field.

  5. Electric field-induced softening of alkali silicate glasses

    SciTech Connect

    McLaren, C.; Heffner, W.; Jain, H.; Tessarollo, R.; Raj, R.

    2015-11-02

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  6. Full 180° magnetization reversal with electric fields.

    PubMed

    Wang, J J; Hu, J M; Ma, J; Zhang, J X; Chen, L Q; Nan, C W

    2014-12-16

    Achieving 180° magnetization reversal with an electric field rather than a current or magnetic field is a fundamental challenge and represents a technological breakthrough towards new memory cell designs. Here we propose a mesoscale morphological engineering approach to accomplishing full 180° magnetization reversals with electric fields by utilizing both the in-plane piezostrains and magnetic shape anisotropy of a multiferroic heterostructure. Using phase-field simulations, we examined a patterned single-domain nanomagnet with four-fold magnetic axis on a ferroelectric layer with electric-field-induced uniaxial strains. We demonstrated that the uniaxial piezostrains, if non-collinear to the magnetic easy axis of the nanomagnet at certain angles, induce two successive, deterministic 90° magnetization rotations, thereby leading to full 180° magnetization reversals.

  7. Full 180° Magnetization Reversal with Electric Fields

    NASA Astrophysics Data System (ADS)

    Wang, J. J.; Hu, J. M.; Ma, J.; Zhang, J. X.; Chen, L. Q.; Nan, C. W.

    2014-12-01

    Achieving 180° magnetization reversal with an electric field rather than a current or magnetic field is a fundamental challenge and represents a technological breakthrough towards new memory cell designs. Here we propose a mesoscale morphological engineering approach to accomplishing full 180° magnetization reversals with electric fields by utilizing both the in-plane piezostrains and magnetic shape anisotropy of a multiferroic heterostructure. Using phase-field simulations, we examined a patterned single-domain nanomagnet with four-fold magnetic axis on a ferroelectric layer with electric-field-induced uniaxial strains. We demonstrated that the uniaxial piezostrains, if non-collinear to the magnetic easy axis of the nanomagnet at certain angles, induce two successive, deterministic 90° magnetization rotations, thereby leading to full 180° magnetization reversals.

  8. Sparse Reconstruction of Electric Fields from Radial Magnetic Data

    NASA Astrophysics Data System (ADS)

    Yeates, Anthony R.

    2017-02-01

    Accurate estimates of the horizontal electric field on the Sun’s visible surface are important not only for estimating the Poynting flux of magnetic energy into the corona but also for driving time-dependent magnetohydrodynamic models of the corona. In this paper, a method is developed for estimating the horizontal electric field from a sequence of radial-component magnetic field maps. This problem of inverting Faraday’s law has no unique solution. Unfortunately, the simplest solution (a divergence-free electric field) is not realistically localized in regions of nonzero magnetic field, as would be expected from Ohm’s law. Our new method generates instead a localized solution, using a basis pursuit algorithm to find a sparse solution for the electric field. The method is shown to perform well on test cases where the input magnetic maps are flux balanced in both Cartesian and spherical geometries. However, we show that if the input maps have a significant imbalance of flux—usually arising from data assimilation—then it is not possible to find a localized, realistic, electric field solution. This is the main obstacle to driving coronal models from time sequences of solar surface magnetic maps.

  9. New Method for Solving Inductive Electric Fields in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Vanhamäki, H.

    2005-12-01

    We present a new method for calculating inductive electric fields in the ionosphere. It is well established that on large scales the ionospheric electric field is a potential field. This is understandable, since the temporal variations of large scale current systems are generally quite slow, in the timescales of several minutes, so inductive effects should be small. However, studies of Alfven wave reflection have indicated that in some situations inductive phenomena could well play a significant role in the reflection process, and thus modify the nature of ionosphere-magnetosphere coupling. The input to our calculation method are the time series of the potential part of the ionospheric electric field together with the Hall and Pedersen conductances. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfven wave reflection from uniformly conducting ionosphere.

  10. Electric field enhanced conductivity in strongly coupled dense metal plasma

    SciTech Connect

    Stephens, J.; Neuber, A.

    2012-06-15

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field ({approx}6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  11. Electric field enhanced conductivity in strongly coupled dense metal plasma

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Neuber, A.

    2012-06-01

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field (˜6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  12. Limiting electric fields of HVDC overhead power lines.

    PubMed

    Leitgeb, N

    2014-05-01

    As a consequence of the increased use of renewable energy and the now long distances between energy generation and consumption, in Europe, electric power transfer by high-voltage (HV) direct current (DC) overhead power lines gains increasing importance. Thousands of kilometers of them are going to be built within the next years. However, existing guidelines and regulations do not yet contain recommendations to limit static electric fields, which are one of the most important criteria for HVDC overhead power lines in terms of tower design, span width and ground clearance. Based on theoretical and experimental data, in this article, static electric fields associated with adverse health effects are analysed and various criteria are derived for limiting static electric field strengths.

  13. Electric field by pick-up ions and electrons

    NASA Astrophysics Data System (ADS)

    Yamauchi, Masatoshi; Behar, Etienne; Nilsson, Hans; Holmstrom, Mats

    2016-04-01

    Observations by the Rosetta Plasma Consortium (RPC) showed increasing distortion of the solar wind flow as Rosetta approached the Sun, i.e., as the density of the newly born ions increased. This indicates azimuthal momentum transfer from the solar wind to the newly born ions because they are displaced by the solar wind electric field up to the ion gyroradius this the solar wind velocity, and conservation of the momentum (center of the mass) makes the solar wind to azimuthally shift by "counter action" of these pick-up ion motions. To understand this azimuthal momentum transfer, it is inevitable to model the electric field by the displacement of these pick-up ions and electrons. Although the E×B drift does not make charge separation when the scale size is larger than the ion gyroradius, ions and electrons move in the opposite direction to each other within the short distance up to a gyroradius, and therefore, the charge separation occurs. Thus, the newly-ionized neutrals (ion-electron pairs) create the electric field in the opposite (shielding) direction to the solar wind electric field (like the ionopause of Venus and Mars). However, such a newly induced "shielding" electric field will simultaneously be weakened by the solar wind electrons because the solar wind is also moved by this shielding electric field to reduce it, in the same way as the plasma oscillation (time scale of about 10-4 s). In other words, the solar wind tries to maintain the solar wind electric field as far as the momentum allows. These two opposite effects must be combined when modelling the azimuthal electric field, and resultant ion/electron motions within a gyroradius, like the case for ROSETTA. Furthermore, the effect of the induced electric field by the pick-up ions and electrons will be different when the newly born ions are created as the result of photo-ionization and of the charge exchange because the electron effect is different between them. In the presentation, we model the

  14. Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

  15. High school students' representations and understandings of electric fields

    NASA Astrophysics Data System (ADS)

    Cao, Ying; Brizuela, Bárbara M.

    2016-12-01

    This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields postinstruction as indicated by students' performance on textbook-style questions. It has, however, inadequately captured student ideas expressed in other situations yet informative to educational research. In this study, we explore students' ideas of electric fields preinstruction as shown by students' representations produced in open-ended activities. 92 participant students completed a worksheet that involved drawing comic strips about electric charges as characters of a cartoon series. Three students who had spontaneously produced arrow diagrams were interviewed individually after class. We identified nine ideas related to electric fields that these three students spontaneously leveraged in the comic strip activity. In this paper, we describe in detail each idea and its situated context. As most research in the literature has understood students as having relatively fixed conceptions and mostly identified divergences in those conceptions from canonical targets, this study shows students' reasoning to be more variable in particular moments, and that variability includes common sense resources that can be productive for learning about electric fields.

  16. Consistency restrictions on maximal electric-field strength in quantum field theory.

    PubMed

    Gavrilov, S P; Gitman, D M

    2008-09-26

    Quantum field theory with an external background can be considered as a consistent model only if backreaction is relatively small with respect to the background. To find the corresponding consistency restrictions on an external electric field and its duration in QED and QCD, we analyze the mean-energy density of quantized fields for an arbitrary constant electric field E, acting during a large but finite time T. Using the corresponding asymptotics with respect to the dimensionless parameter eET2, one can see that the leading contributions to the energy are due to the creation of particles by the electric field. Assuming that these contributions are small in comparison with the energy density of the electric background, we establish the above-mentioned restrictions, which determine, in fact, the time scales from above of depletion of an electric field due to the backreaction.

  17. Field emission behavior of carbon nanotube yarn for micro-resolution X-ray tube cathode.

    PubMed

    Hwang, Jae Won; Mo, Chan Bin; Jung, Hyun Kyu; Ryu, Seongwoo; Hong, Soon Hyung

    2013-11-01

    Carbon nanotube (CNT) has excellent electrical and thermal conductivity and high aspect ratio for X-ray tube cathode. However, CNT field emission cathode has been shown unstable field emission and short life time due to field evaporation by high current density and detachment by electrostatic force. An alternative approach in this direction is the introduction of CNT yarn, which is a one dimensional assembly of individual carbon nanotubes bonded by the Van der Waals force. Because CNT yarn is composed with many CNTs, CNT yarns are expected to increase current density and life time for X-ray tube applications. In this research, CNT yarn was fabricated by spinning of a super-aligned CNT forest and was characterized for application to an X-ray tube cathode. CNT yarn showed a high field emission current density and a long lifetime of over 450 hours. Applying the CNT yarn field emitter to the X-ray tube cathode, it was possible to obtain micro-scale resolution images. The relationship between the field emission properties and the microstructure evolution was investigated and the unraveling effect of the CNT yarn was discussed.

  18. Realistic Electric Field Mapping of Anisotropic Muscle During Electrical Stimulation Using a Combination of Water Diffusion Tensor and Electrical Conductivity.

    PubMed

    Choi, Bup Kyung; Oh, Tong In; Sajib, Saurav Zk; Kim, Jin Woong; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2017-04-01

    To realistically map the electric fields of biological tissues using a diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT) method to estimate tissue response during electrical stimulation. Imaging experiments were performed using chunks of bovine muscle. Two silver wire electrodes were positioned inside the muscle tissue for electrical stimulation. Electric pulses were applied with a 100-V amplitude and 100-μs width using a voltage stimulator. During electrical stimulation, we collected DT-MREIT data from a 3T magnetic resonance imaging scanner. We adopted the projected current density method to calculate the electric field. Based on the relation between the water diffusion tensor and the conductivity tensor, we computed the position-dependent scale factor using the measured magnetic flux density data. Then, a final conductivity tensor map was reconstructed using the multiplication of the water diffusion tensor and the scale factor. The current density images from DT-MREIT data represent the internal current flows that exist not only in the electrodes but also in surrounding regions. The reconstructed electric filed map from our anisotropic conductivity tensor with the projected current density shows coverage that is more than 2 times as wide, and higher signals in both the electrodes and surrounding tissues, than the previous isotropic method owing to the consideration of tissue anisotropy. An electric field map obtained by an anisotropic reconstruction method showed different patterns from the results of the previous isotropic reconstruction method. Since accurate electric field mapping is important to correctly estimate the coverage of the electrical treatment, future studies should include more rigorous validations of the new method through in vivo and in situ experiments.

  19. Realistic Electric Field Mapping of Anisotropic Muscle During Electrical Stimulation Using a Combination of Water Diffusion Tensor and Electrical Conductivity

    PubMed Central

    2017-01-01

    Purpose To realistically map the electric fields of biological tissues using a diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT) method to estimate tissue response during electrical stimulation. Methods Imaging experiments were performed using chunks of bovine muscle. Two silver wire electrodes were positioned inside the muscle tissue for electrical stimulation. Electric pulses were applied with a 100-V amplitude and 100-μs width using a voltage stimulator. During electrical stimulation, we collected DT-MREIT data from a 3T magnetic resonance imaging scanner. We adopted the projected current density method to calculate the electric field. Based on the relation between the water diffusion tensor and the conductivity tensor, we computed the position-dependent scale factor using the measured magnetic flux density data. Then, a final conductivity tensor map was reconstructed using the multiplication of the water diffusion tensor and the scale factor. Results The current density images from DT-MREIT data represent the internal current flows that exist not only in the electrodes but also in surrounding regions. The reconstructed electric filed map from our anisotropic conductivity tensor with the projected current density shows coverage that is more than 2 times as wide, and higher signals in both the electrodes and surrounding tissues, than the previous isotropic method owing to the consideration of tissue anisotropy. Conclusions An electric field map obtained by an anisotropic reconstruction method showed different patterns from the results of the previous isotropic reconstruction method. Since accurate electric field mapping is important to correctly estimate the coverage of the electrical treatment, future studies should include more rigorous validations of the new method through in vivo and in situ experiments. PMID:28446015

  20. Induced electric fields in the MAXWEL surface-based human model from exposure to external low frequency electric fields.

    PubMed

    Findlay, R P

    2014-12-01

    This work presents calculations of internal induced electric fields in the anatomically realistic surface-based model of the male human body, MAXWEL, from exposure to external low frequency electric fields under grounded and isolated conditions. The maximum 99th percentile induced electric fields calculated in the MAXWEL central nervous system were 3.49 (grounded) and 1.54 (isolated) mV m(-1) per kV m(-1) at 50 Hz. The application of 2, 1 and 0.5 mm resolution voxel models derived from the surface-based version to the calculations of induced electric fields is described. 2 mm and 1 mm resolution maximum 99th percentile induced electric field values calculated in selected tissues of the eye at 50 Hz were within 30 % of those calculated at 0.5 mm resolution. The calculated electric field values in MAXWEL were compared with values from the male model NORMAN and female model NAOMI. The maximum 99th percentile value for NAOMI, calculated by Dimbylow in bone, was 49.4 mV m(-1) per kV m(-1) at 50 Hz under grounded conditions. The corresponding value calculated in MAXWEL was 15.7 mV m(-1) per kV m(-1), considerably lower due to anatomical differences between the male and female models. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. High electric field phenomena in insulation

    NASA Astrophysics Data System (ADS)

    Laghari, J. R.; Sarjeant, W. J.

    1989-01-01

    The present study extends previous work to include electron radiation-induced changes in monoisopropyl biphenyl (MIPB)-impregnated polypropylene film as well as the effects of neutron/gamma radiation on dry polypropylene films. Effects that were quite similar were induced by both electron and neutron radiation on the properties of interest of the polypropylene films. Impregnation of the film with MIPB had a mitigatory effect on the degradation of the properties. This report also contains the results of a simultaneous electrical and thermal aging study of a capacitor-grade polypropylene film. The data obtained in this study was fitted to models that will enable realistic prediction of lifetimes under operating conditions.

  2. Nanoscale Lubrication of Ionic Surfaces Controlled via a Strong Electric Field

    PubMed Central

    Strelcov, Evgheni; Kumar, Rajeev; Bocharova, Vera; Sumpter, Bobby G.; Tselev, Alexander; Kalinin, Sergei V.

    2015-01-01

    Frictional forces arise whenever objects around us are set in motion. Controlling them in a rational manner means gaining leverage over mechanical energy losses and wear. This paper presents a way of manipulating nanoscale friction by means of in situ lubrication and interfacial electrochemistry. Water lubricant is directionally condensed from the vapor phase at a moving metal-ionic crystal interface by a strong confined electric field, thereby allowing friction to be tuned up or down via an applied bias. The electric potential polarity and ionic solid solubility are shown to strongly influence friction between the atomic force microscope (AFM) tip and salt surface. An increase in friction is associated with the AFM tip digging into the surface, whereas reducing friction does not influence its topography. No current flows during friction variation, which excludes Joule heating and associated electrical energy losses. The demonstrated novel effect can be of significant technological importance for controlling friction in nano- and micro-electromechanical systems. PMID:25623295

  3. Nanoscale lubrication of ionic surfaces controlled via a strong electric field.

    PubMed

    Strelcov, Evgheni; Kumar, Rajeev; Bocharova, Vera; Sumpter, Bobby G; Tselev, Alexander; Kalinin, Sergei V

    2015-01-27

    Frictional forces arise whenever objects around us are set in motion. Controlling them in a rational manner means gaining leverage over mechanical energy losses and wear. This paper presents a way of manipulating nanoscale friction by means of in situ lubrication and interfacial electrochemistry. Water lubricant is directionally condensed from the vapor phase at a moving metal-ionic crystal interface by a strong confined electric field, thereby allowing friction to be tuned up or down via an applied bias. The electric potential polarity and ionic solid solubility are shown to strongly influence friction between the atomic force microscope (AFM) tip and salt surface. An increase in friction is associated with the AFM tip digging into the surface, whereas reducing friction does not influence its topography. No current flows during friction variation, which excludes Joule heating and associated electrical energy losses. The demonstrated novel effect can be of significant technological importance for controlling friction in nano- and micro-electromechanical systems.

  4. Nanoscale Lubrication of Ionic Surfaces Controlled via a Strong Electric Field

    NASA Astrophysics Data System (ADS)

    Strelcov, Evgheni; Kumar, Rajeev; Bocharova, Vera; Sumpter, Bobby G.; Tselev, Alexander; Kalinin, Sergei V.

    2015-01-01

    Frictional forces arise whenever objects around us are set in motion. Controlling them in a rational manner means gaining leverage over mechanical energy losses and wear. This paper presents a way of manipulating nanoscale friction by means of in situ lubrication and interfacial electrochemistry. Water lubricant is directionally condensed from the vapor phase at a moving metal-ionic crystal interface by a strong confined electric field, thereby allowing friction to be tuned up or down via an applied bias. The electric potential polarity and ionic solid solubility are shown to strongly influence friction between the atomic force microscope (AFM) tip and salt surface. An increase in friction is associated with the AFM tip digging into the surface, whereas reducing friction does not influence its topography. No current flows during friction variation, which excludes Joule heating and associated electrical energy losses. The demonstrated novel effect can be of significant technological importance for controlling friction in nano- and micro-electromechanical systems.

  5. Nanoscale lubrication of ionic surfaces controlled via a strong electric field

    SciTech Connect

    Strelcov, Evgheni; Bocharova, Vera; Sumpter, Bobby G.; Tselev, Alexander; Kalinin, Sergei V.; Kumar, Rajeev

    2015-01-27

    Frictional forces arise whenever objects around us are set in motion. Controlling them in a rational manner means gaining leverage over mechanical energy losses and wear. This paper presents a way of manipulating nanoscale friction by means of in situ lubrication and interfacial electrochemistry. Water lubricant is directionally condensed from the vapor phase at a moving metal-ionic crystal interface by a strong confined electric field, thereby allowing friction to be tuned up or down via an applied bias. The electric potential polarity and ionic solid solubility are shown to strongly influence friction between the atomic force microscope (AFM) tip and salt surface. An increase in friction is associated with the AFM tip digging into the surface, whereas reducing friction does not influence its topography. No current flows during friction variation, which excludes Joule heating and associated electrical energy losses. Lastly, the demonstrated novel effect can be of significant technological importance for controlling friction in nano- and micro-electromechanical systems.

  6. Electric Field-Induced Fluid Velocity Field Distribution in DNA Solution

    NASA Astrophysics Data System (ADS)

    Zhang, Ling-Yun; Wang, Peng-Ye

    2008-10-01

    We present an analytical solution for fluid velocity Geld distribution of polyelectrolyte DNA. Both the electric field force and the viscous force in the DNA solution are considered under a suitable boundary condition. The solution of electric potential is analytically obtained by using the linearized Poisson-Boltzmann equation. The fluid velocity along the electric field is dependent on the cylindrical radius and concentration. It is shown that the electric field-induced fluid velocity will be increased with the increasing cylindrical radius, whose distribution also varies with the concentration.

  7. Wetting of sessile water drop under an external electrical field

    NASA Astrophysics Data System (ADS)

    Vancauwenberghe, Valerie; di Marco, Paolo; Brutin, David; Amu Collaboration; Unipi Collaboration

    2013-11-01

    The enhancement of heat and mass transfer using a static electric field is an interesting process for industrial applications, due to its low energy consumption and potentially high level of evaporation rate enhancement. However, to date, this phenomenon is still not understood in the context of the evaporation of sessile drops. We previously synthesized the state of the art concerning the effect of an electric field on sessile drops with a focus on the change of contact angle and shape and the influence of the evaporation rate [1]. We present here the preliminary results of an new experiment set-up. The novelty of the set-up is the drop injection from the bottom that allows to generate safety the droplet under the electrostatic field. The evaporation at room temperature of water drops having three different volumes has been investigated under an electric field up to 10.5 kV/cm. The time evolutions of the contact angles, volumes and diameters have been analysed. As reported in the literature, the drop elongate along the direction of the electric field. Despite the hysteresis effect of the contact angle, the receding contact angle increases with the strength of the electric field. This is clearly observable for the small drops for which the gravity effect can be neglected.

  8. Electric Field Control of Ferromagnetism and Magnetic Devices Using Multiferroics

    NASA Astrophysics Data System (ADS)

    Heron, John Thomas

    This dissertation presents a study of a heterostructure composed of room temperature magnetoelectric multiferroic BiFeO3 and ferromagnetic Co.90Fe.10, with specific interest in understanding the interfacial coupling mechanisms in this system and establishing the electric field control of a magnetization and spintronic devices. The field of spintronics has been plagued with the problem of a large energy dissipation as a consequence of the resistive losses that come during the writing of the magnetic state (i.e. reversing the magnetization direction). The primary aim of the work presented here is to investigate and understand a novel heterostructure and materials interface that can be demonstrated as a pathway to low energy spintronics. In this dissertation, I will address the specific aspects of multiferroicity, magnetoelectricity, and interface coupling that must be addressed in order to reverse a magnetization with an electric field. Furthermore, I will demonstrate the reversal of a magnetization with an electric field in single and multilayer magnetic devices. The primary advances made as a result of the work described herein are the use of epitaxial constraints to control the nanoscale domain structure of a multiferroic which is then correlated to the domain structure of the exchange coupled ferromagnet. Additionally, the magnetization direction of the ferromagnetic layer is controlled with only an applied electric field at both macroscopic and microscopic scales. Lastly, using this electric field control of ferromagnetism, the first demonstration of a magnetoelectric memory bit is presented.

  9. Electric Field Driven Self-Assembly of Colloidal Rods

    NASA Astrophysics Data System (ADS)

    Juarez, Jaime; Chaudhary, Kundan; Chen, Qian; Granick, Steve; Lewis, Jennifer

    2012-02-01

    The ability to assemble anisotropic colloidal building blocks into ordered configurations is of both scientific and technological importance. We are studying how electric field-induced interactions guide the self-assembly of these blocks into well aligned microstructures. Specifically, we present observations of the assembly of colloidal silica rods (L/D ˜ 4) within planar electrode cells as a function of different electric field parameters. Results from video microscopy and image analysis demonstrate that aligned microstructures form due to the competition between equilibrium interactions of induced dipoles and non-equilibrium processes (i.e., electro-osmosis). Under the appropriate electric field conditions (˜ kHZ AC fields), aligned colloidal rod fluids form over large areas on the electrode surface. The superposition of a DC electric field to this aligned colloidal rod fluid initiates their condensation into a vertically oriented crystalline phase. Ongoing work is now focused on exploring how temporal changes to electric fields influence colloidal rod dynamics and, hence, the assembly kinetics of aligned colloidal monolayers.

  10. Polarimetric Radar and Electric Field Observations of a Multicell Storm

    NASA Astrophysics Data System (ADS)

    Bruning, E. C.; Rust, W. D.; Macgorman, D. R.; Schuur, T.; Straka, J.; Krehbiel, P.; Rison, W.

    2004-12-01

    Much prior thunderstorm electrification research uses one-dimensional analyses of vertical profiles of the thunderstorm electric field, often incorporating cloud-to-ground lighting strike data and radar reflectivity observations. New instrumentation has provided the opportunity to investigate thunderstorm electrification and lightning in greater spatial detail. We present data from the late stages of a multicellular storm occurring on 28-29 June 2004 during the Thunderstorm Electrification and Lightning Experiment (TELEX) field program in central Oklahoma. Three-dimensional (3-D) vector electric field (measured by balloon sounding), total lighting mapping, and polarimetric radar are utilized. The maximum measured electric field exceeded -150 kV m-1. Preliminary charge analysis using the electric field vectors indicates a positive layer below 0\\deg C, followed by a large negative layer just above the melting level. Another positive and negative layer follow this. Polarimetric radar signatures within the melting layer are examined in the context of the electric field observations. Mapped lightning flashes are used to clarify and support the inferred charge structure. An interactive 3-D display is used to combine these data sources. Temporal evolution of the storm is also considered.

  11. Study on the frame body structure of micro-electric vehicle based on frontal crash safety

    NASA Astrophysics Data System (ADS)

    Lu, Yaoquan; Zhang, Sanchuan

    2017-08-01

    In order to research the safety of skeleton type body of micro-electric vehicles in the frontal collision, the method of finite element modeling and simulation are used to analyze frame body that is fitted with the energy absorption structure, the simulation results show that On the basis of absorbing the most energy and the least of body acceleration, the absorbent structure parameters can be optimized, the optimized parameters are length 180 mm, wall thickness 3 mm and materials Q460.

  12. [Raman spectra study of soy protein isolate structure treated with pulsed electric fields].

    PubMed

    Liu, Yan-Yan; Zeng, Xin-An; Han, Zhong

    2010-12-01

    The effect of pulsed electric field on molecular structure of soy protein isolate (SPI) was investigated by Raman spectroscopy method. The applied pulsed electric field was up to 50 kV * cm(-1) with pulse width 40 micros. It was demonstrated from the Raman spectra that the PEF treatment undei 50 kV * cm(-1) had induced disappearance significantly of peak near 2 886 cm(-1) bond. It was also explored that with the increase in treatment time, the polarity of microenvironment of aliphatic amino acid residues and the exposure of tryptophan residues from a buried hydrophobic microenvironment were increased. On the other hand, the interaction of serine acid residues, the C-H plane bend vibration, C-N stretch vibration, and the C=O stretch vibration of aspartic acid and glutamic acid were decreased. The embeding or participation of the tyrosine phenolic groups as hydrogen bond donors was firstly increased with the treatment time (less than 1 600 micros), and afterwards decreased (from 1 600 to 3 200 micros).

  13. Electric field alignment of nanofibrillated cellulose (NFC) in silicone oil: impact on electrical properties.

    PubMed

    Kadimi, Amal; Benhamou, Karima; Ounaies, Zoubeida; Magnin, Albert; Dufresne, Alain; Kaddami, Hamid; Raihane, Mustapha

    2014-06-25

    This work aims to study how the magnitude, frequency, and duration of an AC electric field affect the orientation of two kinds of nanofibrillated cellulose (NFC) dispersed in silicone oil that differ by their surface charge density and aspect ratio. In both cases, the electric field alignment occurs in two steps: first, the NFC makes a gyratory motion oriented by the electric field; second, NFC interacts with itself to form chains parallel to the electric field lines. It was also observed that NFC chains become thicker and longer when the duration of application of the electric field is increased. In-situ dielectric properties have shown that the dielectric constant of the medium increases in comparison to the randomly dispersed NFC (when no electric field is applied). The optimal parameters of alignment were found to be 5000 Vpp/mm and 10 kHz for a duration of 20 min for both kinds of NFC. The highest increase in dielectric constant was achieved with NFC oxidized for 5 min (NFC-O-5 min) at the optimum conditions mentioned above.

  14. Using Gravitational Analogies to Introduce Elementary Electrical Field Theory Concepts

    ERIC Educational Resources Information Center

    Saeli, Susan; MacIsaac, Dan

    2007-01-01

    Since electrical field concepts are usually unfamiliar, abstract, and difficult to visualize, conceptual analogies from familiar gravitational phenomena are valuable for teaching. Such analogies emphasize the underlying continuity of field concepts in physics and support the spiral development of student understanding. We find the following four…

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

    DTIC Science & Technology

    1976-10-01

    subjected to combinations of 400.0 nm irradiation (strongly absorbed by Pb(N_)-) and strong field, for both polarities, again with no effect . It has...II n»Kt*tmy mad I4mtlty by MeeM mmt»mr) .± Lead Azide Electric Field Initiation Contact Effects Surface Effects Radiation Effect ! A9STMACT...reported. Specifically, ws-d4*eu«s the effects of contacts on the initiation of explosives by electric fields, and present preliminary weaouresents

  16. Tuning the mechanical behaviour of structural elements by electric fields

    NASA Astrophysics Data System (ADS)

    Di Lillo, Luigi; Raither, Wolfram; Bergamini, Andrea; Zündel, Manuel; Ermanni, Paolo

    2013-06-01

    This work reports on the adoption of electric fields to tune the mechanical behaviour of structural elements. A mechanical characterization procedure, consisting of double lap joint and 3-point bending tests, is conducted on copper-polyimide laminates while applying electric fields of varying intensity. Field dependence and, thus, adaptability of shear strength and bending stiffness are shown as a function of the overlapping length and interfaces number, respectively. Further, the impact of remaining charges is investigated in both testing configurations. The findings herein lay the foundation for the implementation of electro-adaptive components in structural applications.

  17. Dirac oscillator in perpendicular magnetic and transverse electric fields

    SciTech Connect

    Nath, D.; Roy, P.

    2014-12-15

    We study (2+1) dimensional massless Dirac oscillator in the presence of perpendicular magnetic and transverse electric fields. Exact solutions are obtained and it is shown that there exists a critical magnetic field B{sub c} such that the spectrum is different in the two regions B>B{sub c} and Belectric field. • Exact solutions are found. • Critical cases have been examined.

  18. Electro-optic probe measurements of electric fields in plasmas.

    PubMed

    Nishiura, M; Yoshida, Z; Mushiake, T; Kawazura, Y; Osawa, R; Fujinami, K; Yano, Y; Saitoh, H; Yamasaki, M; Kashyap, A; Takahashi, N; Nakatsuka, M; Fukuyama, A

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

  19. Electro-optic probe measurements of electric fields in plasmas

    NASA Astrophysics Data System (ADS)

    Nishiura, M.; Yoshida, Z.; Mushiake, T.; Kawazura, Y.; Osawa, R.; Fujinami, K.; Yano, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, A.

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

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

    PubMed

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  2. The electric field and global electrodynamics of the magnetosphere

    NASA Technical Reports Server (NTRS)

    Stern, D. P.

    1979-01-01

    The conception of the electrodynamics of the quiet-time magnetosphere obtained during the last four years of magnetospheric study is presented. Current understandings of the open magnetosphere, convective plasma flows in the plasma sheet, the shielding of the inner magnetosphere from the convective magnetospheric electric field, the space charge produced when injected electrons drift towards dawn and injected ions drift towards dusk, the disruption of the flow of the Birkeland current by plasma instabilities and the shielding of the convective electric field by the dayside magnetopause are discussed. Attention is also given to changes of magnetic field line topology magnetic storms and substorms. Unresolved questions and new tools which may play a role in the further understanding of magnetospheric electrodynamics and the role of the magnetospheric electric field are presented.

  3. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  4. Vapor-liquid equilibrium in electric field gradients.

    PubMed

    Samin, Sela; Tsori, Yoav

    2011-01-13

    We investigate the vapor-liquid coexistence of polar and nonpolar fluids in the presence of a nonuniform electric field. We find that a large enough electric field can nucleate a gas bubble from the liquid phase or a liquid droplet from the vapor phase. The surface tension of the vapor-liquid interface is determined within squared-gradient theory. When the surface potential (charge) is controlled, the surface tension increases (decreases) compared to the zero-field interface. The effect of the electric field on the fluid phase diagram depends strongly on the constitutive relation for the dielectric constant. Finally, we show that gas bubbles can be nucleated far from the bounding surfaces.

  5. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    PubMed Central

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

    2015-01-01

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

  6. PIC simulation of electrodeless plasma thruster with rotating electric field

    SciTech Connect

    Nomura, Ryosuke; Ohnishi, Naofumi; Nishida, Hiroyuki

    2012-11-27

    For longer lifetime of electric propulsion system, an electrodeless plasma thruster with rotating electric field have been proposed utilizing a helicon plasma source. The rotating electric field may produce so-called Lissajous acceleration of helicon plasma in the presence of diverging magnetic field through a complicated mechanism originating from many parameters. Two-dimensional simulations of the Lissajous acceleration were conducted by a code based on Particle-In-Cell (PIC) method and Monte Carlo Collision (MCC) method for understanding plasma motion in acceleration area and for finding the optimal condition. Obtained results show that azimuthal current depends on ratio of electron drift radius to plasma region length, AC frequency, and axial magnetic field. When ratio of cyclotron frequency to the AC frequency is higher than unity, reduction of the azimuthal current by collision effect is little or nothing.

  7. Effects of orthogonal rotating electric fields on electrospinning process

    NASA Astrophysics Data System (ADS)

    Lauricella, M.; Cipolletta, F.; Pontrelli, G.; Pisignano, D.; Succi, S.

    2017-08-01

    Electrospinning is a nanotechnology process whereby an external electric field is used to accelerate and stretch a charged polymer jet, so as to produce fibers with nanoscale diameters. In quest of a further reduction in the cross section of electrified jets hence of a better control on the morphology of the resulting electrospun fibers, we explore the effects of an external rotating electric field orthogonal to the jet direction. Through intensive particle simulations, it is shown that by a proper tuning of the electric field amplitude and frequency, a reduction of up to a 30% in the aforementioned radius can be obtained, thereby opening new perspectives in the design of future ultra-thin electrospun fibers. Applications can be envisaged in the fields of nanophotonic components as well as for designing new and improved filtration materials.

  8. Ionization and recombination in attosecond electric field pulses

    SciTech Connect

    Dimitrovski, Darko; Solov'ev, Eugene A.; Briggs, John S.

    2005-10-15

    Based on the results of a previous communication [Dimitrovski et al., Phys. Rev. Lett. 93, 083003 (2004)], we study ionization and excitation of a hydrogenic atom from the ground and first excited states in short electric field pulses of several cycles. A process of ionization and recombination which occurs periodically in time is identified, for both small and extremely large peak electric field strengths. In the limit of large electric peak fields closed-form analytic expressions for the population of the initial state after single- and few-cycle pulses are derived. These formulas, strictly valid for asymptotically large momentum transfer from the field, give excellent agreement with fully numerical calculations for all momentum transfers.

  9. Regional United States electric field and GIC hazard impacts (Invited)

    NASA Astrophysics Data System (ADS)

    Gannon, J. L.; Balch, C. C.; Trichtchenko, L.

    2013-12-01

    Geomagnetically Induced Currents (GICs) are primarily driven by impulsive geomagnetic disturbances created by the interaction between the Earth's magnetosphere and sharp velocity, density, and magnetic field enhancements in the solar wind. However, the magnitude of the induced electric field response at the ground level, and therefore the resulting hazard to the bulk power system, is determined not only by magnetic drivers, but also by the underlying geology. Convolution techniques are used to calculate surface electric fields beginning from the spectral characteristics of magnetic field drivers and the frequency response of the local geology. Using these techniques, we describe historical scenarios for regions across the United States, and the potential impact of large events on electric power infrastructure.

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

    PubMed

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

    2015-05-12

    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.

  11. 60-Hertz electric-field exposures in transmission line towers.

    PubMed

    Bracken, T; Senior, Russell; Dudman, Joseph

    2005-09-01

    This article reports on an investigation of 60-Hz electric-field exposures of line workers in 230- to 765-kV transmission line towers. The exposures were based on computations of the unperturbed electric field along climbing routes and at work positions on the towers and on insulated ladders suspended in towers. Computed exposures were expressed in terms of the unperturbed electric field averaged over the body as stipulated by guidelines. For the realistic on-tower positions, the worker's posture, the uniformity of the field, and the field orientation differed from the guideline exposure scenario of standing erect in a vertical uniform field. These differences suggest the need for care in comparing electric-field exposures in towers with guideline limits. The unperturbed nonuniform fields at discrete points near steel and aluminum lattice structures were computed using Monte Carlo methods that model surface and spatial electric fields on and near standard geometrical elements. To estimate a whole-body average, fields were computed at 10 discrete points positioned on segments of an articulated stick-figure model of the human body. The whole-body average field was computed from fields at all the points weighted by the fraction of body volume that the corresponding segment represented. We estimated the average unperturbed electric field, the space potential at the torso, and the induced short-circuit current for 19 climbing and work positions in six towers. The maximum average electric-field exposure during climbing ranged from 10 kV/m for a 230-kV tower to 31 kV/m for a 765-kV tower. Exposures at on-tower work positions were lower than the estimated maximum exposures during climbing. For 500- and 765-kV towers, computed exposures while climbing and at some on-tower positions exceeded the limit of 20 kV/m given in the recently adopted IEEE Standard C95.6 2002. For lower voltage towers, exposures did not exceed 20 kV/m.

  12. Destruction of Emulsions by an AC Electric Field: Importance of Partial Merging

    NASA Astrophysics Data System (ADS)

    Thiam, Abdou Rachid; Bremond, Nicolas; Bibette, Jerome

    2010-03-01

    Electrocoalescence is basically the process of blending droplets by the application of an electric field. The approach is used in petroleum refineries for the separation of water in oil emulsions (that is, by coalescing water droplets), and more recently in biotechnology industry, for the fusion of micro reactors. In a first step, we will focus on the coalesce condition for two drops under a given electric field. Microfluidics offers a comfortable setup therefore, as we sought to span a range of initial conditions in terms of the distance between the droplets, their sizes, and also a region of the applied electric field. Thus, we could establish a stability diagram according to the initial conditions and droplets' composition, which displays three domains referred to as: coalescence, no coalescence and a third one of partial coalescence, where the droplets coalesce for a brief moment then separate right afterwards. We proceeded then by generalizing the setup to the case of a stream of droplets, and we found that the evolution of the stream can be predicted by the behaviour of the local pairs of droplets, as seen in the previous step. The main outcome of that study is the total destruction of an emulsion above a critical volume fraction for a given amplitude of electric field.

  13. Electric-field control of magnetic moment in Pd

    PubMed Central

    Obinata, Aya; Hibino, Yuki; Hayakawa, Daichi; Koyama, Tomohiro; Miwa, Kazumoto; Ono, Shimpei; Chiba, Daichi

    2015-01-01

    Several magnetic properties have recently become tunable with an applied electric field. Particularly, electrically controlled magnetic phase transitions and/or magnetic moments have attracted attention because they are the most fundamental parameters in ferromagnetic materials. In this study, we showed that an electric field can be used to control the magnetic moment in films made of Pd, usually a non-magnetic element. Pd ultra-thin films were deposited on ferromagnetic Pt/Co layers. In the Pd layer, a ferromagnetically ordered magnetic moment was induced by the ferromagnetic proximity effect. By applying an electric field to the ferromagnetic surface of this Pd layer, a clear change was observed in the magnetic moment, which was measured directly using a superconducting quantum interference device magnetometer. The results indicate that magnetic moments extrinsically induced in non-magnetic elements by the proximity effect, as well as an intrinsically induced magnetic moments in ferromagnetic elements, as reported previously, are electrically tunable. The results of this study suggest a new avenue for answering the fundamental question of “can an electric field make naturally non-magnetic materials ferromagnetic?” PMID:26391306

  14. Manipulation of red blood cells with electric field

    NASA Astrophysics Data System (ADS)

    Saboonchi, Hossain; Esmaeeli, Asghar

    2009-11-01

    Manipulation of bioparticles and macromolecules is the central task in many biological and biotechnological processes. The current methods for physical manipulation takes advantage of different forces such as acoustic, centrifugal, magnetic, electromagnetic, and electric forces, as well as using optical tweezers or filtration. Among all these methods, however, the electrical forces are particularly attractive because of their favorable scale up with the system size which makes them well-suited for miniaturization. Currently the electric field is used for transportation, poration, fusion, rotation, and separation of biological cells. The aim of the current research is to gain fundamental understanding of the effect of electric field on the human red blood cells (RBCs) using direct numerical simulation. A front tracking/finite difference technique is used to solve the fluid flow and electric field equations, where the fluid in the cell and the blood (plasma) is modeled as Newtonian and incompressible, and the interface separating the two is treated as an elastic membrane. The behavior of RBCs is investigated as a function of the controlling parameters of the problem such as the strength of the electric field.

  15. Coherent anti-Stokes Raman scattering under electric field stimulation

    NASA Astrophysics Data System (ADS)

    Capitaine, Erwan; Ould Moussa, Nawel; Louot, Christophe; Lefort, Claire; Pagnoux, Dominique; Duclère, Jean-René; Kaneyasu, Junya F.; Kano, Hideaki; Duponchel, Ludovic; Couderc, Vincent; Leproux, Philippe

    2016-12-01

    We introduce an experiment using electro-CARS, an electro-optical method based on the combination of ultrabroadband multiplex coherent anti-Stokes Raman scattering (M-CARS) spectroscopy and electric field stimulation. We demonstrate that this method can effectively discriminate the resonant CARS signal from the nonresonant background owing to a phenomenon of molecular orientation in the sample medium. Such molecular orientation is intrinsically related to the induction of an electric dipole moment by the applied static electric field. Evidence of the electro-CARS effect is obtained with a solution of n -alkanes (CnH2 n +2 , 15 ≤n ≤40 ), for which an enhancement of the CARS signal-to-noise ratio is achieved in the case of CH2 and CH3 symmetric/asymmetric stretching vibrations. Additionally, an electric-field-induced second-harmonic generation experiment is performed in order to corroborate the orientational organization of molecules due to the electric field excitation. Finally, we use a simple mathematical approach to compare the vibrational information extracted from electro-CARS measurements with spontaneous Raman data and to highlight the impact of electric stimulation on the vibrational signal.

  16. Multiscale directed self-assembly of composite microgels in complex electric fields.

    PubMed

    Crassous, Jérôme J; Demirörs, Ahmet F

    2016-12-21

    This study explored the application of localized electric fields for reversible directed self-assembly of colloidal particles in 3 dimensions. Electric field microgradients, arising from the use of micro-patterned electrodes, were utilized to direct the localization and self-assembly of polarizable (charged) particles resulting from a combination of dielectrophoretic and multipolar forces. Deionized dispersions of spherical and ellipsoidal core-shell microgels were employed for investigating their assembly under an external alternating electric field. We demonstrated that the frequency of the field allowed for an exquisite control over the localization of the particles and their self-assembled structures near the electrodes. We extended this approach to concentrated binary dispersions consisting of polarizable and less polarizable composite microgels. Furthermore, we utilized the thermosensitivity of the microgels to adjust the effective volume fraction and the dynamics of the system, which provided the possibility to dynamically "solidify" the assembly of the field-responsive particles by a temperature quench from their initial fluid state into an arrested crystalline state. Reversible solidification enables us to re-write/reconstruct various 3 dimensional assemblies by varying the applied field frequency.

  17. Mutagenic Potential of Alternating Current Electric Fields.

    DTIC Science & Technology

    1997-09-01

    did a study in Drosophila melanogaster where they found a significant increase in the rate of transcription and translation in 17 chromosomal regions ...Interestingly, the same 17 regions were also the same chromosomal regions that control and regulate cell growth and development (Wiesbrot and Uluc...Continuous Electromagnetic Fields on the Stage, Weight and Stature of Chick Embryo. Acta Anatomica 145:302-306. Prata, S. (1993) EMF Handbook., The Waite

  18. Electric Field Induced Superconductivity in Layered Materials

    NASA Astrophysics Data System (ADS)

    Ye, J. T.; Craciun, M. F.; Russo, S.; Morpurgo, M. F.; Kasahara, Y.; Yuan, H. T.; Shimotani, H.; Iwasa, Y.

    2011-03-01

    Using electric double layer (EDL) gating, large amount of carriers can be accumulated on a broad range of materials, which provides new opportunities in effectively manipulating their electronic properties in complementary with the chemical doping. In searching for novel transport phenomena, layered materials are advantageous because atomically flat surface can be easily fabricated using the graphene techniques. We used layered material: ZrNCl and graphite to act as the channel of EDL transistors. For both ZrNCl and graphene, we achieved high carrier density up to 1014 cm-2 , electrostatically. For graphene, we studied the high carrier density transport for graphene of 1-3 layers. Transport properties at the high carrier density exhibit clear layer dependence governed by the intrinsic band structures of graphene and its multi-layers. For ZrNCl EDL transistor, we observed metallic states at gate voltage higher than 3.5 V followed by gate-induced superconductivity after metal-insulator transition when the transistor was cooled down to about 15 K.

  19. Modeling of electric field distribution in tissues during electroporation.

    PubMed

    Corovic, Selma; Lackovic, Igor; Sustaric, Primoz; Sustar, Tomaz; Rodic, Tomaz; Miklavcic, Damijan

    2013-02-21

    Electroporation based therapies and treatments (e.g. electrochemotherapy, gene electrotransfer for gene therapy and DNA vaccination, tissue ablation with irreversible electroporation and transdermal drug delivery) require a precise prediction of the therapy or treatment outcome by a personalized treatment planning procedure. Numerical modeling of local electric field distribution within electroporated tissues has become an important tool in treatment planning procedure in both clinical and experimental settings. Recent studies have reported that the uncertainties in electrical properties (i.e. electric conductivity of the treated tissues and the rate of increase in electric conductivity due to electroporation) predefined in numerical models have large effect on electroporation based therapy and treatment effectiveness. The aim of our study was to investigate whether the increase in electric conductivity of tissues needs to be taken into account when modeling tissue response to the electroporation pulses and how it affects the local electric distribution within electroporated tissues. We built 3D numerical models for single tissue (one type of tissue, e.g. liver) and composite tissue (several types of tissues, e.g. subcutaneous tumor). Our computer simulations were performed by using three different modeling approaches that are based on finite element method: inverse analysis, nonlinear parametric and sequential analysis. We compared linear (i.e. tissue conductivity is constant) model and non-linear (i.e. tissue conductivity is electric field dependent) model. By calculating goodness of fit measure we compared the results of our numerical simulations to the results of in vivo measurements. The results of our study show that the nonlinear models (i.e. tissue conductivity is electric field dependent: σ(E)) fit experimental data better than linear models (i.e. tissue conductivity is constant). This was found for both single tissue and composite tissue. Our results of

  20. Modeling of electric field distribution in tissues during electroporation

    PubMed Central

    2013-01-01

    Background Electroporation based therapies and treatments (e.g. electrochemotherapy, gene electrotransfer for gene therapy and DNA vaccination, tissue ablation with irreversible electroporation and transdermal drug delivery) require a precise prediction of the therapy or treatment outcome by a personalized treatment planning procedure. Numerical modeling of local electric field distribution within electroporated tissues has become an important tool in treatment planning procedure in both clinical and experimental settings. Recent studies have reported that the uncertainties in electrical properties (i.e. electric conductivity of the treated tissues and the rate of increase in electric conductivity due to electroporation) predefined in numerical models have large effect on electroporation based therapy and treatment effectiveness. The aim of our study was to investigate whether the increase in electric conductivity of tissues needs to be taken into account when modeling tissue response to the electroporation pulses and how it affects the local electric distribution within electroporated tissues. Methods We built 3D numerical models for single tissue (one type of tissue, e.g. liver) and composite tissue (several types of tissues, e.g. subcutaneous tumor). Our computer simulations were performed by using three different modeling approaches that are based on finite element method: inverse analysis, nonlinear parametric and sequential analysis. We compared linear (i.e. tissue conductivity is constant) model and non-linear (i.e. tissue conductivity is electric field dependent) model. By calculating goodness of fit measure we compared the results of our numerical simulations to the results of in vivo measurements. Results The results of our study show that the nonlinear models (i.e. tissue conductivity is electric field dependent: σ(E)) fit experimental data better than linear models (i.e. tissue conductivity is constant). This was found for both single tissue and