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

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

Sulaeman, M. Y.; Widita, R.

2014-09-30

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

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

PubMed

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

2009-12-01

Nanosecond pulsed electric fields (nsPEFs) can affect the intracellular structures of cells in vitro. This study shows the direct effects of nsPEFs on tumor growth, tumor volume, and histological characteristics of normal skin and B16-F10 melanoma in SKH-1 mice. A melanoma model was set up by injecting B16-F10 into female SKH-1 mice. After a 100-pulse treatment with an nsPEF (40-kV/cm field strength; 300-ns duration; 30-ns rise time; 2-Hz repetition rate), tumor growth and histology were studied using transillumination, light microscopy with hematoxylin and eosin stain and transmission electron microscopy. Melanin and iron within the melanoma tumor were also detected with specific stains. After nsPEF treatment, tumor development was inhibited with decreased volumes post-nsPEF treatment compared with control tumors (P<0.05). The nsPEF-treated tumor volume was reduced significantly compared with the control group (P<0.01). Hematoxylin and eosin stain and transmission electron microscopy showed morphological changes and nuclear shrinkage in the tumor. Fontana-Masson stain indicates that nsPEF can externalize the melanin. Iron stain suggested nsPEF caused slight hemorrhage in the treated tissue. Histology confirmed that repeated applications of nsPEF disrupted the vascular network. nsPEF treatment can significantly disrupt the vasculature, reduce subcutaneous murine melanoma development, and produce tumor cell contraction and nuclear shrinkage while concurrently, but not permanently, damaging peripheral healthy skin tissue in the treated area, which we attribute to the highly localized electric fields surrounding the needle electrodes.

Characteristics of colloidal aluminum nanoparticles prepared by nanosecond pulsed laser ablation in deionized water in presence of parallel external electric field

NASA Astrophysics Data System (ADS)

Mahdieh, Mohammad Hossein; Mozaffari, Hossein

2017-10-01

In this paper, we investigate experimentally the effect of electric field on the size, optical properties and crystal structure of colloidal nanoparticles (NPs) of aluminum prepared by nanosecond Pulsed Laser Ablation (PLA) in deionized water. The experiments were conducted for two different conditions, with and without the electric field parallel to the laser beam path and the results were compared. To study the influence of electric field, two polished parallel aluminum metals plates perpendicular to laser beam path were used as the electrodes. The NPs were synthesized for target in negative, positive and neutral polarities. The colloidal nanoparticles were characterized using the scanning electron microscopy (SEM), UV-vis absorption spectroscopy and X-ray Diffraction (XRD). The results indicate that initial charge on the target has strong effect on the size properties and concentration of the synthesized nanoparticles. The XRD patterns show that the structure of produced NPs with and without presence of electric field is Boehmite (AlOOH).

Electric field in a plasma channel in a high-pressure nanosecond discharge in hydrogen: a coherent anti-stokes Raman scattering study.

PubMed

Yatom, S; Tskhai, S; Krasik, Ya E

2013-12-20

Experimental results of a study of the electric field in a plasma channel produced during nanosecond discharge at a H2 gas pressure of (2-3)×10(5)  Pa by the coherent anti-Stokes scattering method are reported. The discharge was ignited by applying a voltage pulse with an amplitude of ∼100  kV and a duration of ∼5  ns to a blade cathode placed at a distance of 10 and 20 mm from the anode. It was shown that this type of gas discharge is characterized by the presence of an electric field in the plasma channel with root-mean-square intensities of up to 30  kV/cm. Using polarization measurements, it was found that the direction of the electric field is along the cathode-anode axis.

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

PubMed

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

2016-01-29

Permeabilization of cell membranes occurs upon exposure to a threshold absorbed dose (AD) of nanosecond pulsed electric fields (nsPEF). The ultimate, physiological bioeffect of this exposure depends on the type of cultured cell and environment, indicating that cell-specific pathways and structures are stimulated. Here we investigate 10 and 600 ns duration PEF effects on Chinese hamster ovary (CHO) cell nuclei, where our hypothesis is that pulse disruption of the nuclear envelope membrane leads to observed cell death and decreased viability 24 h post-exposure. To observe short-term responses to nsPEF exposure, CHO cells have been stably transfected with two fluorescently-labeled proteins known to be sequestered for cellular chromosomal function within the nucleus - histone-2b (H2B) and proliferating cell nuclear antigen (PCNA). H2B remains associated with chromatin after nsPEF exposure, whereas PCNA leaks out of nuclei permeabilized by a threshold AD of 10 and 600 ns PEF. A downturn in 24 h viability, measured by MTT assay, is observed at the number of pulses required to induce permeabilization of the nucleus. Copyright © 2015 Elsevier Inc. All rights reserved.

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

PubMed

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

2016-08-01

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

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

NASA Astrophysics Data System (ADS)

Roth, Caleb C.

Background: Exposures of cells to very short (less than 1 microsecond) electric pulses in the megavolt/meter range have been shown to cause a multitude of effects, both physical and molecular in nature. Physically, nanosecond electrical pulse exposure can disrupt the plasma membrane, leading to a phenomenon known as nanoporation. Nanoporation is the production of nanometer sized holes (less than 2 nanometers in diameter) that can persist for up to fifteen minutes, allowing the flow of ions into and out of the cell. Nanoporation can lead to secondary physical effects, such as cellular swelling, shrinking and blebbing. Molecularly, nanosecond electrical pulses have been shown to activate signaling pathways, produce oxidative stress, stimulate hormone secretion and induce both apoptotic and necrotic death. The mechanism by which nanosecond electrical pulses cause molecular changes is unknown; however, it is thought the flow of ions, such as calcium, into the cell via nanopores, could be a major cause. The ability of nanosecond electrical pulses to cause membranes to become permeable and to induce apoptosis makes the technology a desirable modality for cancer research; however, the lack of understanding regarding the mechanisms by which nanosecond electrical pulses cause nanoporation impedes further development of this technology. This dissertation documents the genomic and proteomic responses of cells exposed to nanosecond electrical pulses and describes in detail the biophysical effects of these electrical pulses, including the demonstration for the first time of the generation of acoustic pressure transients capable of disrupting plasma membranes and possibly contributing to nanoporation. Methods: Jurkat, clone E6-1 (human lymphocytic cell line), U937 (human lymphocytic cell line), Chinese hamster ovarian cells and adult primary human dermal fibroblasts exposed to nanosecond electrical pulses were subjected to a variety of molecular assays, including flow cytometry

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

PubMed

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

2016-12-01

Gap junctional intercellular communication (GJIC) is an important mechanism that is involved and affected in many diseases and injuries. So far, the effect of nanosecond pulsed electric fields (nsPEFs) on the communication between cells was not investigated. An in vitro approach is presented with rat liver epithelial WB-F344 cells grown and exposed in a monolayer. In order to observe sub-lethal effects, cells were exposed to pulsed electric fields with a duration of 100ns and amplitudes between 10 and 20kV/cm. GJIC strongly decreased within 15min after treatment but recovered within 24h. Gene expression of Cx43 was significantly decreased and associated with a reduced total amount of Cx43 protein. In addition, MAP kinases p38 and Erk1/2, involved in Cx43 phosphorylation, were activated and Cx43 became hyperphosphorylated. Immunofluorescent staining of Cx43 displayed the disassembly of gap junctions. Further, a reorganization of the actin cytoskeleton was observed whereas tight junction protein ZO-1 was not significantly affected. All effects were field- and time-dependent and most pronounced within 30 to 60min after treatment. A better understanding of a possible manipulation of GJIC by nsPEFs might eventually offer a possibility to develop and improve treatments. Copyright © 2016 Elsevier B.V. All rights reserved.

Biophysical Studies of Nanosecond Pulsed Electric Field Induced Cell Membrane Permeabilization

NASA Astrophysics Data System (ADS)

Wu, Yu-Hsuan

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

Induction of apoptosis of liver cancer cells by nanosecond pulsed electric fields (nsPEFs).

PubMed

He, Ling; Xiao, Deyou; Feng, Jianguo; Yao, Chenguo; Tang, Liling

2017-02-01

The application of nanosecond pulsed electric fields (nsPEFs) is a novel method to induce the death of cancer cells. NsPEFs could directly function on the cell membrane and activate the apoptosis pathways, then induce apoptosis in various cell lines. However, the nsPEFs-inducing-apoptosis action sites and the exact pathways are not clear now. In this study, nsPEFs were applied to the human liver cancer cells HepG2 with different parameters. By apoptosis assay, morphological observation, detecting the mitochondrial membrane potential (ΔΨ m ), intracellular calcium ion concentration ([Ca 2+ ]i) and the expressions of key apoptosis factors, we demonstrated that nsPEFs could induce the morphology of cell apoptosis, the change in ΔΨ m , [Ca 2+ ]i and the upregulation of some key apoptosis factors, which revealed the responses of liver cancer cells and indicated that cells may undergo apoptosis through the mitochondria-dependent pathway after nsPEFs were applied.

Nanosecond pulsed electric field thresholds for nanopore formation in neural cells

NASA Astrophysics Data System (ADS)

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

2013-03-01

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

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

PubMed

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

2018-03-29

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

Multiphoton imaging reveals that nanosecond pulsed electric fields collapse tumor and normal vascular perfusion in human glioblastoma xenografts.

PubMed

Bardet, Sylvia M; Carr, Lynn; Soueid, Malak; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

2016-10-04

Despite the biomedical advances of the last century, many cancers including glioblastoma are still resistant to existing therapies leaving patients with poor prognoses. Nanosecond pulsed electric fields (nsPEF) are a promising technology for the treatment of cancer that have thus far been evaluated in vitro and in superficial malignancies. In this paper, we develop a tumor organoid model of glioblastoma and apply intravital multiphoton microscopy to assess their response to nsPEFs. We demonstrate for the first time that a single 10 ns, high voltage electric pulse (35-45 kV/cm), collapses the perfusion of neovasculature, and also alters the diameter of capillaries and larger vessels in normal tissue. These results contribute to the fundamental understanding of nsPEF effects in complex tissue environments, and confirm the potential of nsPEFs to disrupt the microenvironment of solid tumors such as glioblastoma.

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

NASA Astrophysics Data System (ADS)

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

2005-04-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

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

PubMed

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

2014-05-01

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

Permeabilization of the nuclear envelope following nanosecond pulsed electric field exposure

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

Thompson, Gary L., E-mail: gary.l.thompson.3@gmail.com; Roth, Caleb C.; Kuipers, Marjorie A.

2016-01-29

Permeabilization of cell membranes occurs upon exposure to a threshold absorbed dose (AD) of nanosecond pulsed electric fields (nsPEF). The ultimate, physiological bioeffect of this exposure depends on the type of cultured cell and environment, indicating that cell-specific pathways and structures are stimulated. Here we investigate 10 and 600 ns duration PEF effects on Chinese hamster ovary (CHO) cell nuclei, where our hypothesis is that pulse disruption of the nuclear envelope membrane leads to observed cell death and decreased viability 24 h post-exposure. To observe short-term responses to nsPEF exposure, CHO cells have been stably transfected with two fluorescently-labeled proteins known tomore » be sequestered for cellular chromosomal function within the nucleus – histone-2b (H2B) and proliferating cell nuclear antigen (PCNA). H2B remains associated with chromatin after nsPEF exposure, whereas PCNA leaks out of nuclei permeabilized by a threshold AD of 10 and 600 ns PEF. A downturn in 24 h viability, measured by MTT assay, is observed at the number of pulses required to induce permeabilization of the nucleus. - Highlights: • The ability of nsPEF to damage nuclear structures within cells is investigated. • Leakage of proliferating nuclear antigen from nuclei is induced by nsPEF. • High doses of nsPEF disrupt cortical lamin and cause chromatin decompaction. • Histone H2B remains attached to chromatin following nsPEF exposure. • DNA does not leak out of nsPEF-permeabilized nuclei.« less

Nanosecond pulsed electric fields induce poly(ADP-ribose) formation and non-apoptotic cell death in HeLa S3 cells

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

Morotomi-Yano, Keiko; Akiyama, Hidenori; Yano, Ken-ichi, E-mail: yanoken@kumamoto-u.ac.jp

Highlights: •Nanosecond pulsed electric field (nsPEF) is a new and unique means for life sciences. •Apoptosis was induced by nsPEF exposure in Jurkat cells. •No signs of apoptosis were detected in HeLa S3 cells exposed to nsPEFs. •Formation of poly(ADP-ribose) was induced in nsPEF-exposed HeLa S3 cells. •Two distinct modes of cell death were activated by nsPEF in a cell-dependent manner. -- Abstract: Nanosecond pulsed electric fields (nsPEFs) have recently gained attention as effective cancer therapy owing to their potency for cell death induction. Previous studies have shown that apoptosis is a predominant mode of nsPEF-induced cell death in severalmore » cell lines, such as Jurkat cells. In this study, we analyzed molecular mechanisms for cell death induced by nsPEFs. When nsPEFs were applied to Jurkat cells, apoptosis was readily induced. Next, we used HeLa S3 cells and analyzed apoptotic events. Contrary to our expectation, nsPEF-exposed HeLa S3 cells exhibited no molecular signs of apoptosis execution. Instead, nsPEFs induced the formation of poly(ADP-ribose) (PAR), a hallmark of necrosis. PAR formation occurred concurrently with a decrease in cell viability, supporting implications of nsPEF-induced PAR formation for cell death. Necrotic PAR formation is known to be catalyzed by poly(ADP-ribose) polymerase-1 (PARP-1), and PARP-1 in apoptotic cells is inactivated by caspase-mediated proteolysis. Consistently, we observed intact and cleaved forms of PARP-1 in nsPEF-exposed and UV-irradiated cells, respectively. Taken together, nsPEFs induce two distinct modes of cell death in a cell type-specific manner, and HeLa S3 cells show PAR-associated non-apoptotic cell death in response to nsPEFs.« less

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. Copyright © 2014 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2014-03-01

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

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

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

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

NASA Astrophysics Data System (ADS)

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

2013-02-01

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

Nanosecond electric pulses modulate skeletal muscle calcium dynamics and contraction

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Time domain dielectric spectroscopy of nanosecond pulsed electric field induced changes in dielectric properties of pig whole blood.

PubMed

Zhuang, Jie; Kolb, Juergen F

2015-06-01

The dielectric spectra of fresh pig whole blood in the β-dispersion range after exposure to 300-nanosecond pulsed electric fields (nsPEFs) with amplitude higher than the supra-electroporation threshold for erythrocytes were recorded by time domain reflectometry dielectric spectroscopy. The implications of the dielectric parameters on the dynamics of post-pulse pore development were discussed in light of the Cole-Cole relaxation model. The temporal development of the Cole-Cole parameters indicates that nsPEFs induced significant poration and swelling of erythrocytes within the first 5 min. The results also show that the majority of erythrocytes could not fully recover from supra-electroporation up to 30 min. The findings of this study suggest that time domain dielectric spectroscopy is a promising label-free and real-time physiological measuring technique for nsPEF-blood related biomedical applications, capable of following the conformational and morphological changes of cells. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanosecond pulsed electric fields and the cell cycle

NASA Astrophysics Data System (ADS)

Mahlke, Megan A.

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

Cells exposed to nanosecond electrical pulses exhibit biomarkers of mechanical stress

NASA Astrophysics Data System (ADS)

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

2015-03-01

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

Toward investigating changes in cell mechanoelastic properties in response to nanosecond pulsed electric fields

NASA Astrophysics Data System (ADS)

Coker, Zachary; Troyanova-Wood, Maria; Traverso, Andrew; Meng, Zhaokai; Ballmann, Charles; Petrov, Georgi; Ibey, Bennett L.; Yakovlev, Vladislav

2017-02-01

Nanosecond electric pulses (nsEPs) are known to cause a variety of effects on mammalian cells, ranging from destabilization of cell membranes to changes in cytoskeleton and elastic moduli. Measurement of a cells mechanoelastic properties have previously been limited to only invasive and destructive techniques such as atomic force microscopy or application of optical tweezers. However, due to recent advances, Brillouin spectroscopy has now become viable as a non-contact, non-invasive method for measuring these properties in cells and other materials. Here, we present progress toward applying Brillouin spectroscopy using a unique microscopy system for measuring changes in CHO-K1 cells when exposed to nsEPs of 600ns pulse duration with intensity of 50kV/cm. Successful measurement of mechanoelastic changes in these cells will demonstrate Brillouin spectroscopy as a viable method for measuring changes in elastic properties of other cells and living organisms.

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

PubMed

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

2016-01-05

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

Nanosecond pulsed electric field suppresses development of eyes and germ cells through blocking synthesis of retinoic acid in Medaka (Oryzias latipes).

PubMed

Shiraishi, Eri; Hosseini, Hamid; Kang, Dong K; Kitano, Takeshi; Akiyama, Hidenori

2013-01-01

Application of nanosecond pulsed electric fields (nsPEFs) has attracted rising attention in various scientific fields including medical, pharmacological, and biological sciences, although its effects and molecular mechanisms leading to the effects remain poorly understood. Here, we show that a single, high-intensity (10-30 kV/cm), 60-ns PEF exposure affects gene expression and impairs development of eyes and germ cells in medaka (Oryzias latipes). Exposure of early blastula stage embryos to nsPEF down-regulated the expression of several transcription factors which are essential for eye development, causing abnormal eye formation. Moreover, the majority of the exposed genetic female embryos showed a fewer number of germ cells similar to that of the control (unexposed) genetic male at 9 days post-fertilization (dpf). However, all-trans retinoic acid (atRA) treatment following the exposure rescued proliferation of germ cells and resumption of normal eye development, suggesting that the phenotypes induced by nsPEF are caused by a decrease of retinoic acid levels. These results confirm that nsPEFs induce novel effects during embryogenesis in medaka.

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

PubMed

Cui, Guang-ying; Diao, Hong-yan

2015-11-01

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

A trial of ignition innovation of gasoline engine by nanosecond pulsed low temperature plasma ignition

NASA Astrophysics Data System (ADS)

Shiraishi, Taisuke; Urushihara, Tomonori; Gundersen, Martin

2009-07-01

Application of nanosecond pulsed low temperature plasma as an ignition technique for automotive gasoline engines, which require a discharge under conditions of high back pressure, has been studied experimentally using a single-cylinder engine. The nanosecond pulsed plasma refers to the transient (non-equilibrated) phase of a plasma before the formation of an arc discharge; it was obtained by applying a high voltage with a nanosecond pulse (FWHM of approximately 80 or 25 ns) between coaxial cylindrical electrodes. It was confirmed that nanosecond pulsed plasma can form a volumetric multi-channel streamer discharge at an energy consumption of 60 mJ cycle-1 under a high back pressure of 1400 kPa. It was found that the initial combustion period was shortened compared with the conventional spark ignition. The initial flame visualization suggested that the nanosecond pulsed plasma ignition results in the formation of a spatially dispersed initial flame kernel at a position of high electric field strength around the central electrode. It was observed that the electric field strength in the air gap between the coaxial cylindrical electrodes was increased further by applying a shorter pulse. It was also clarified that the shorter pulse improved ignitability even further.

Effects of nanosecond pulsed electric fields (nsPEFs) on the human fungal pathogen Candida albicans: an in vitro study

NASA Astrophysics Data System (ADS)

Guo, Jinsong; Dang, Jie; Wang, Kaile; Zhang, Jue; Fang, Jing

2018-05-01

Candida albicans is the leading human fungal pathogen that causes many life-threatening infections. Notably, the current clinical trial data indicate that Candida species shows the emerging resistance to anti-fungal drugs. The aim of this study was to evaluate the antifungal effects of nanosecond pulsed electric fields (nsPEFs) as a novel drug-free strategy in vitro. In this study, we investigated the inactivation and permeabilization effects of C. albicans under different nsPEFs exposure conditions (100 pulses, 100 ns in duration, intensities of 20, 40 kV cm‑1). Cell death was studied by annexin-V and propidium iodide staining. The changes of intracellular Ca2+ concentration after nsPEFs treatment were observed using Fluo-4 AM. Results show that C. albicans cells and biofilms were both obviously inhibited and destroyed after nsPEFs treatment. Furthermore, C. albicans cells were significantly permeabilized after nsPEFs treatment. Additionally, nsPEFs exposure led to a large amount of DNA and protein leakage. Importantly, nsPEFs induced a field strength-dependent apoptosis in C. albicans cells. Further experiments revealed that Ca2+ involved in nsPEFs induced C. albicans apoptosis. In conclusion, this proof-of-concept study provides a potential alternative drug-free strategy for killing pathogenic Candida species.

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

NASA Astrophysics Data System (ADS)

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

2007-09-01

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

Disassembly of actin structures by nanosecond pulsed electric field is a downstream effect of cell swelling.

PubMed

Pakhomov, Andrei G; Xiao, Shu; Pakhomova, Olga N; Semenov, Iurii; Kuipers, Marjorie A; Ibey, Bennett L

2014-12-01

Disruption of the actin cytoskeleton structures was reported as one of the characteristic effects of nanosecond-duration pulsed electric field (nsPEF) in both mammalian and plant cells. We utilized CHO cells that expressed the monomeric fluorescent protein (mApple) tagged to actin to test if nsPEF modifies the cell actin directly or as a consequence of cell membrane permeabilization. A train of four 600-ns pulses at 19.2 kV/cm (2 Hz) caused immediate cell membrane poration manifested by YO-PRO-1 dye uptake, gradual cell rounding and swelling. Concurrently, bright actin features were replaced by dimmer and uniform fluorescence of diffuse actin. To block the nsPEF-induced swelling, the bath buffer was isoosmotically supplemented with an electropore-impermeable solute (sucrose). A similar addition of a smaller, electropore-permeable solute (adonitol) served as a control. We demonstrated that sucrose efficiently blocked disassembly of actin features by nsPEF, whereas adonitol did not. Sucrose also attenuated bleaching of mApple-tagged actin in nsPEF-treated cells (as integrated over the cell volume), although did not fully prevent it. We conclude that disintegration of the actin cytoskeleton was a result of cell swelling, which, in turn, was caused by cell permeabilization by nsPEF and transmembrane diffusion of solutes which led to the osmotic imbalance. Copyright © 2014 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2016-01-01

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

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

PubMed Central

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

2016-01-01

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

Nanosecond Plasma Enhanced H2/O2/N2 Premixed Flat Flames

DTIC Science & Technology

2014-01-01

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

PIC simulations of post-pulse field reversal and secondary ionization in nanosecond argon discharges

NASA Astrophysics Data System (ADS)

Kim, H. Y.; Gołkowski, M.; Gołkowski, C.; Stoltz, P.; Cohen, M. B.; Walker, M.

2018-05-01

Post-pulse electric field reversal and secondary ionization are investigated with a full kinetic treatment in argon discharges between planar electrodes on nanosecond time scales. The secondary ionization, which occurs at the falling edge of the voltage pulse, is induced by charge separation in the bulk plasma region. This process is driven by a reverse in the electric field from the cathode sheath to the formerly driven anode. Under the influence of the reverse electric field, electrons in the bulk plasma and sheath regions are accelerated toward the cathode. The electron movement manifests itself as a strong electron current generating high electron energies with significant electron dissipated power. Accelerated electrons collide with Ar molecules and an increased ionization rate is achieved even though the driving voltage is no longer applied. With this secondary ionization, in a single pulse (SP), the maximum electron density achieved is 1.5 times higher and takes a shorter time to reach using 1 kV 2 ns pulse as compared to a 1 kV direct current voltage at 1 Torr. A bipolar dual pulse excitation can increase maximum density another 50%–70% above a SP excitation and in half the time of RF sinusoidal excitation of the same period. The first field reversal is most prominent but subsequent field reversals also occur and correspond to electron temperature increases. Targeted pulse designs can be used to condition plasma density as required for fast discharge applications.

Nanosecond Pulsed Electric Fields Enhance the Anti-tumour Effects of the mTOR Inhibitor Everolimus against Melanoma

NASA Astrophysics Data System (ADS)

Dai, Jie; Wu, Shan; Kong, Yan; Chi, Zhihong; Si, Lu; Sheng, Xinan; Cui, Chuanliang; Fang, Jing; Zhang, Jue; Guo, Jun

2017-01-01

The PI3K/mTOR/AKT pathway is activated in most melanomas, but mTOR inhibitors used singly have limited activity against advanced melanomas. The application of nanosecond pulsed electric fields (nsPEFs) is a promising cancer therapy approach. In this study, we evaluated the synergistic anti-tumour efficacy of the mTOR inhibitor everolimus in conjunction with nsPEFs against melanoma. The combined treatment of nsPEFs and everolimus gradually decreased cell growth concurrent with nsPEF intensity. nsPEFs alone or combined with everolimus could promote melanoma cell apoptosis, accompanied with a loss in cellular mitochondrial membrane potential and an increase in Ca2+ levels. In vivo experiments showed that a combination of the mTOR inhibitor everolimus and nsPEFs improved the inhibitory effect, and all skin lesions caused by nsPEFs healed in 1 week without any observed adverse effect. Combination treatment induced caspase-dependent apoptosis through the upregulation of the pro-apoptotic factor Bax and downregulation of the anti-apoptotic factor Bcl-2. Everolimus and nsPEFs synergistically inhibited angiogenesis by decreasing the expression of vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR), and CD34. Our findings indicate that nsPEFs in combination with an mTOR inhibitor can be used as a potential treatment approach for advanced melanoma.

New topics in coherent anti-stokes raman scattering gas-phase diagnostics : femtosecond rotational CARS and electric-field measurements.

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

Lempert, Walter R.; Barnat, Edward V.; Kearney, Sean Patrick

2010-07-01

We discuss two recent diagnostic-development efforts in our laboratory: femtosecond pure-rotational Coherent anti-Stokes Raman scattering (CARS) for thermometry and species detection in nitrogen and air, and nanosecond vibrational CARS measurements of electric fields in air. Transient pure-rotational fs-CARS data show the evolution of the rotational Raman polarization in nitrogen and air over the first 20 ps after impulsive pump/Stokes excitation. The Raman-resonant signal strength at long time delays is large, and we additionally observe large time separation between the fs-CARS signatures of nitrogen and oxygen, so that the pure-rotational approach to fs-CARS has promise for simultaneous species and temperature measurementsmore » with suppressed nonresonant background. Nanosecond vibrational CARS of nitrogen for electric-field measurements is also demonstrated. In the presence of an electric field, a dipole is induced in the otherwise nonpolar nitrogen molecule, which can be probed with the introduction of strong collinear pump and Stokes fields, resulting in CARS signal radiation in the infrared. The electric-field diagnostic is demonstrated in air, where the strength of the coherent infrared emission and sensitivity our field measurements is quantified, and the scaling of the infrared signal with field strength is verified.« less

Observing non-equilibrium state of transport through graphene channel at the nano-second time-scale

NASA Astrophysics Data System (ADS)

Mishra, Abhishek; Meersha, Adil; Raghavan, Srinivasan; Shrivastava, Mayank

2017-12-01

Electrical performance of a graphene FET is drastically affected by electron-phonon inelastic scattering. At high electric fields, the out-of-equilibrium population of optical phonons equilibrates by emitting acoustic phonons, which dissipate the energy to heat sinks. The equilibration time of the process is governed by thermal diffusion time, which is few nano-seconds for a typical graphene FET. The nano-second time-scale of the process keeps it elusive to conventional steady-state or DC measurement systems. Here, we employ a time-domain reflectometry-based technique to electrically probe the device for few nano-seconds and investigate the non-equilibrium state. For the first time, the transient nature of electrical transport through graphene FET is revealed. A maximum change of 35% in current and 50% in contact resistance is recorded over a time span of 8 ns, while operating graphene FET at a current density of 1 mA/μm. The study highlights the role of intrinsic heating (scattering) in deciding metal-graphene contact resistance and transport through the graphene channel.

Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

NASA Astrophysics Data System (ADS)

Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

2015-03-01

The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

Nanosecond pulsed electric field (nsPEF) enhance cytotoxicity of cisplatin to hepatocellular cells by microdomain disruption on plasma membrane.

PubMed

Yin, Shengyong; Chen, Xinhua; Xie, Haiyang; Zhou, Lin; Guo, Danjing; Xu, Yuning; Wu, Liming; Zheng, Shusen

2016-08-15

Previous studies showed nanosecond pulsed electric field (nsPEF) can ablate solid tumors including hepatocellular carcinoma (HCC) but its effect on cell membrane is not fully understood. We hypothesized nsPEF disrupt the microdomains on outer-cellular membrane with direct mechanical force and as a result the plasma membrane permeability increases to facilitate the small molecule intake. Three HCC cells were pulsed one pulse per minute, an interval longer than nanopore resealing time. The cationized ferritin was used to mark up the electronegative microdomains, propidium iodide (PI) for membrane permeabilization, energy dispersive X-ray spectroscopy (EDS) for the negative cell surface charge and cisplatin for inner-cellular cytotoxicity. We demonstrated that the ferritin marked-microdomain and negative cell surface charge were disrupted by nsPEF caused-mechanical force. The cell uptake of propidium and cytotoxicity of DNA-targeted cisplatin increased with a dose effect. Cisplatin gains its maximum inner-cellular cytotoxicity when combining with nsPEF stimulation. We conclude that nsPEF disrupt the microdomains on the outer cellular membrane directly and increase the membrane permeabilization for PI and cisplatin. The microdomain disruption and membrane infiltration changes are caused by the mechanical force from the changes of negative cell surface charge. Copyright © 2016 Elsevier Inc. All rights reserved.

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

DTIC Science & Technology

2014-01-30

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

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

PubMed Central

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

2015-01-01

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

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

PubMed

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

2015-10-09

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

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

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

NASA Astrophysics Data System (ADS)

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

2013-02-01

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

Needle-array to Plate DBD Plasma Using Sine AC and Nanosecond Pulse Excitations for Purpose of Improving Indoor Air Quality

PubMed Central

Zhang, Li; Yang, Dezheng; Wang, Wenchun; Wang, Sen; Yuan, Hao; Zhao, Zilu; Sang, Chaofeng; Jia, Li

2016-01-01

In this study, needle-array to plate electrode configuration was employed to generate an atmospheric air diffuse discharge using both nanosecond pulse and sine AC voltage as excitation voltage for the purpose of improving indoor air quality. Different types of voltage sources and electrode configurations are employed to optimize electrical field distribution and improve discharge stability. Discharge images, electrical characteristics, optical emission spectra, and plasma gas temperatures in both sine AC discharge and nanosecond pulse discharge were compared and the discharge stability during long operating time were discussed. Compared with the discharge excited by sine AC voltage, the nanosecond pulsed discharge is more homogenous and stable, besides, the plasma gas temperature of nanosecond pulse discharge is much lower. Using packed-bed structure, where γ- Al2O3 pellets are filled in the electrode gap, has obvious efficacy in the production of homogenous discharge. Furthermore, both sine AC discharge and nanosecond pulse discharge were used for removing formaldehyde from flowing air. It shows that nanosecond pulse discharge has a significant advantage in energy cost. And the main physiochemical processes for the generation of active species and the degradation of formaldehyde were discussed. PMID:27125663

Recent studies on nanosecond-timescale pressurized gas discharges

DOE PAGES

Yatom, S.; Shlapakovski, A.; Beilin, L.; ...

2016-10-05

The results of recent experimental and numerical studies of nanosecond high-voltage discharges in pressurized gases are reviewed. The discharges were ignited in a diode filled by different gases within a wide range of pressures by an applied pulsed voltage or by a laser pulse in the gas-filled charged resonant microwave cavity. Fast-framing imaging of light emission, optical emission spectroscopy, X-ray foil spectrometry and coherent anti-Stokes Raman scattering were used to study temporal and spatial evolution of the discharge plasma density and temperature, energy distribution function of runaway electrons and dynamics of the electric field in the plasma channel. The resultsmore » obtained allow a deeper understanding of discharge dynamical properties in the nanosecond timescale, which is important for various applications of these types of discharges in pressurized gases.« less

Carbon-based nanomaterial synthesis using nanosecond electrical discharges in immiscible layered liquids: n-heptane and water

NASA Astrophysics Data System (ADS)

Hamdan, Ahmad; Cha, Min Suk

2018-06-01

Plasmas in- or in-contact with liquids have been extensively investigated due to their high potential for a wide range of applications including, but not limited to, water treatment, material synthesis and functionalization, bio-medical applications, and liquid fuel reformation. Recently, we successfully developed a discharge using two immiscible liquids, having very different electrical permittivities, which could significantly intensify the electric field intensity. Here, we establish nanosecond discharges at the interface n-heptane-water (with respective relative dielectric permittivities of 2 and 80) to enable the synthesis of carbon-based nanomaterials. A characterization of the as-synthesized material and the annealed (500 °C) material, using various techniques (Fourier-transform, infra-red, scanning and transmission electron microscopes, etc), shows that the as-synthesized material is a mixture of two carbon-based phases: a crystalline phase (graphite like) embedded into a phase of hydrogenated amorphous carbon. The existence of two-phases may be explained by the non-homogeneity of the discharge that induces various chemical reactions in the plasma channel.

Electropermeabilization by uni- or bipolar nanosecond electric pulses: The impact of extracellular conductivity.

PubMed

Gianulis, Elena C; Casciola, Maura; Xiao, Shu; Pakhomova, Olga N; Pakhomov, Andrei G

2018-02-01

Cellular effects caused by nanosecond electric pulses (nsEP) can be reduced by an electric field reversal, a phenomenon known as bipolar cancellation. The reason for this cancellation effect remains unknown. We hypothesized that assisted membrane discharge is the mechanism for bipolar cancellation. CHO-K1 cells bathed in high (16.1mS/cm; HCS) or low (1.8mS/cm; LCS) conductivity solutions were exposed to either one unipolar (300-ns) or two opposite polarity (300+300-ns; bipolar) nsEP (4-40kV/cm) with increasing interpulse intervals (0.1-50μs). Time-lapse YO-PRO-1 (YP) uptake revealed enhanced membrane permeabilization in LCS compared to HCS at all tested voltages. The time-dependence of bipolar cancellation was similar in both solutions, using either identical (22kV/cm) or isoeffective nsEP treatments (12 and 32kV/cm for LCS and HCS, respectively). However, cancellation was significantly stronger in LCS when the bipolar nsEP had no, or very short (<1μs), interpulse intervals. Finally, bipolar cancellation was still present with interpulse intervals as long as 50μs, beyond the time expected for membrane discharge. Our findings do not support assisted membrane discharge as the mechanism for bipolar cancellation. Instead they exemplify the sustained action of nsEP that can be reversed long after the initial stimulus. Copyright © 2017 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Takashima, Keisuke; Kaneko, Toshiro

2017-06-01

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

Pre-breakdown cavitation nanopores in the dielectric fluid in the inhomogeneous, pulsed electric fields

NASA Astrophysics Data System (ADS)

Pekker, Mikhail; Shneider, Mikhail N.

2015-10-01

This paper discusses the nanopores emerging and developing in a liquid dielectric under the action of the ponderomotive electrostrictive forces in a nonuniform electric field. It is shown that the gradient of the electric field in the vicinity of the rupture (cavitation nanopore) substantially increases and determines whether the rupture grows or collapses. The cavitation rupture in the liquid (nanopore) tends to stretch along the lines of the original field. The mechanism of the breakdown associated with the generation of secondary ruptures in the vicinity of the poles of the nanopore is proposed. The estimations of the extension time for nanopore in water and oil (polar and nonpolar liquids, respectively) are presented. A new mechanism of nano- and subnanosecond breakdown in the insulating (transformer) oil that can be realized in the vicinity of water microdroplets in nanosecond high-voltage devices is considered.

Modeling of plasma chemical processes in the artificial ionized layer in the upper atmosphere by the nanosecond corona discharge

NASA Astrophysics Data System (ADS)

Vikharev, A. L.; Gorbachev, A. M.; Ivanov, O. A.; Kolisko, A. L.; Litvak, A. G.

1993-08-01

The plasma chemical processes in the corona discharge formed in air by a series of high voltage pulses of nanosecond duration are investigated experimentally. The experimental conditions (reduced electric field, duration and repetition frequency of the pulses, gas pressure in the chamber) modeled the regime of creation of the artificial ionized layer (AIL) in the upper atmosphere by a nanosecond microwave discharge. It was found that in a nanosecond microwave discharge predominantly generation of ozone occurs, and that the production of nitrogen dioxide is not large. The energy expenditures for the generation of one O 3 molecule were about 15 eV. On the basis of the experimental results the prognosis of the efficiency of ozone generation in AIL was made.

Effects of nanosecond pulsed electrical fields (nsPEFs) on the cell cycle of CHO and Jurkat cells

NASA Astrophysics Data System (ADS)

Mahlke, Megan A.; Navara, Christopher; Ibey, Bennett L.

2014-03-01

Exposure to nano-second pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. Variations between cell lines in membrane and cytoskeletal structure as well as in survival of nsPEF exposure should correspond to unique line-dependent cell cycle effects. Additionally, phase of cell cycle during exposure may be linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate role of cell cycle phase in survival of nsPEFs. CHO populations recovered similarly to sham populations postnsPEF exposure and did not exhibit a phase-specific change in response. Jurkat cells exhibited considerable apoptosis/necrosis in response to nsPEF exposure and were unable to recover and proliferate in a manner similar to sham exposed cells. Additionally, Jurkat cells appear to be more sensitive to nsPEFs in G2/M phases than in G1/S phases. Recovery of CHO populations suggests that nsPEFs do not inhibit proliferation in CHO cells; however, inhibition of Jurkat cells post-nsPEF exposure coupled with preferential cell death in G2/M phases suggest that cell cycle phase during exposure may be an important factor in determining nsPEF toxicity in certain cell lines. Interestingly, CHO cells have a more robust and rigid cytoskeleton than Jurkat cells which is thought to contribute to their ability to

Quantifying pulsed electric field-induced membrane nanoporation in single cells.

PubMed

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

2016-11-01

Plasma membrane disruption can trigger a host of cellular activities. One commonly observed type of disruption is pore formation. Molecular dynamic (MD) simulations of simplified lipid membrane structures predict that controllably disrupting the membrane via nano-scale poration may be possible with nanosecond pulsed electric fields (nsPEF). Until recently, researchers hoping to verify this hypothesis experimentally have been limited to measuring the relatively slow process of fluorescent markers diffusing across the membrane, which is indirect evidence of nanoporation that could be channel-mediated. Leveraging recent advances in nonlinear optical microscopy, we elucidate the role of pulse parameters in nsPEF-induced membrane permeabilization in live cells. Unlike previous techniques, it is able to directly observe loss of membrane order at the onset of the pulse. We also develop a complementary theoretical model that relates increasing membrane permeabilization to membrane pore density. Due to the significantly improved spatial and temporal resolution possible with our imaging method, we are able to directly compare our experimental and theoretical results. Their agreement provides substantial evidence that nanoporation does occur and that its development is dictated by the electric field distribution. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical properties of polyimides films treated by nanosecond pulsed electrical discharges in water

NASA Astrophysics Data System (ADS)

Sava, Ion; Kruth, Angela; Kolb, Juergen F.; Miron, Camelia

2018-01-01

Fluorinated polyimide films containing cobalt chloride based on hexafluoroisopropylidenediphthalic dianhydride and 4,4‧-diamino-3,3‧-dimethyl diphenylmethane were treated by nanosecond pulsed electrical discharges generated in distilled water. The polyimide films have been characterized by Fourier transform infrared (FTIR) spectra and contact angle measurements, optical transmission spectroscopy, and fluorescence spectroscopy. Significant changes in some intrinsic fluorescence features, such as the intensity and position of the emission peak, have been observed during exposure to water plasma. These effects have been considered to correlate with the development of specific chemical interactions between the liquid and the macromolecules, including the formation of hydrogen bridges. A slight increase in surface hydrophobicity was observed after plasma treatment. FTIR spectra showed a decrease in the intensity of the absorption band and an opening of the imide ring, depending on the treatment time.

Interaction Of CO2 Laser Nanosecond Pulse Train With The Metallic Targets In Optical Breakdown Regime

NASA Astrophysics Data System (ADS)

Apollonov, V. V.; Firsov, K. N.; Konov, V. I.; Nikitin, P. I.; Prokhorov, A. M.; Silenok, A. S.; Sorochenko, V. R.

1986-11-01

In the present paper the electric field and currents in the air-breakdown plasma, produced by the train of nanosecond pulses of TEA-002 - regenerative amplifier near the un-charged targets are studied. The breakdown thresholds and the efficiency of plasma-target heat transmission are also measured. The results of numerical calculations made for increasing of the pulse train contrast with respect to the background in a regenerative amplifier are advanced.

Ephemeral Electric Potential and Electric Field Sensor

NASA Technical Reports Server (NTRS)

Generazio, Edward R. (Inventor)

2017-01-01

Systems, methods, and devices of the various embodiments provide for the minimization of the effects of intrinsic and extrinsic leakage electrical currents enabling true measurements of electric potentials and electric fields. In an embodiment, an ephemeral electric potential and electric field sensor system may have at least one electric field sensor and a rotator coupled to the electric field sensor and be configured to rotate the electric field sensor at a quasi-static frequency. In an embodiment, ephemeral electric potential and electric field measurements may be taken by rotating at least one electric field sensor at a quasi-static frequency, receiving electrical potential measurements from the electric field sensor when the electric field sensor is rotating at the quasi-static frequency, and generating and outputting images based at least in part on the received electrical potential measurements.

Nanosecond Surface Microdischarges in Multilayer Structures

NASA Astrophysics Data System (ADS)

Dubinov, A. E.; Lyubimtseva, V. A.

2018-05-01

Multilayer structures in which nanosecond surface microdischarges are generated have been developed, fabricated, and investigated. In these structures, layers are made in the form of thin transparent films, and a plasma discharge channel is formed in thin spacings between the layers. Passage of the discharge channel from one layer into the neighboring layer is implemented via pre-fabricated microholes. Images of microdischarges were obtained which confirmed that their plasma channels are formed according to the route assigned by the holes. The route may follow a fairly complex scheme and have self-intersection points and portions in which the electrons are bound to move in opposition to the electric field. In studying the shape of channels in multilayer strictures, the authors have found a new physical effect which lies in the azimuthal self-orientation of the discharge channel as it passes from one microhole to another.

Magneto-absorption effects in magnetic-field assisted laser ablation of silicon by UV nanosecond pulses

NASA Astrophysics Data System (ADS)

Farrokhi, H.; Gruzdev, V.; Zheng, H. Y.; Rawat, R. S.; Zhou, W.

2016-06-01

A constant magnetic field can significantly improve the quality and speed of ablation by nanosecond laser pulses. These improvements are usually attributed to the confinement of laser-produced plasma by the magnetic field and specific propagation effects in the magnetized plasma. Here we report a strong influence of constant axial magnetic field on the ablation of silicon by 20-ns laser pulses at wavelength 355 nm, which results in an increase of ablation depth by a factor of 1.3 to 69 depending on laser parameters and magnitude of the magnetic field. The traditional plasma effects do not explain this result, and magneto-absorption of silicon is proposed as one of the major mechanisms of the significant enhancement of ablation.

Nanosecond plasma-mediated electrosurgery with elongated electrodes

NASA Astrophysics Data System (ADS)

Vankov, Alexander; Palanker, Daniel

2007-06-01

Progress in interventional medicine is associated with the development of more delicate and less invasive surgical procedures, which requires more precise and less traumatic, yet affordable, surgical instruments. Previously we reported on the development of the pulsed electron avalanche knife for dissection of soft tissue in liquid media using the 100 ns plasma-mediated electric discharges applied via a 25 μm disk microelectrode. Cavitation bubbles accompanying explosive vaporization of the liquid medium in front of such a pointed electrode produced a series of craters that did not always merge into a continuous cut. In addition, this approach of surface ablation provided a limited depth of cutting. Application of an elongated electrode capable of cutting with its edge rather than just with its pointed apex faces a problem of nonuniformity of the electric field on a nonspherical electrode. In this article we explore dynamics of the plasma-mediated nanosecond discharges in liquid medium in positive and negative polarities and describe the geometry of an electrode that provides a sufficiently uniform electric field along an extended edge of a surgical probe. A highly enhanced and uniform electric field was obtained on very sharp (2.5 μm) exposed edges of a planar electrode insulated on its flat sides. Uniform ionization and simultaneous vaporization was obtained along the whole edge of such a blade with 100 ns pulses at 4-6 kV. A continuous cutting rate of 1 mm/s in the retina and in soft membranes was achieved at a pulse repetition rate of 100 Hz. The collateral damage zone at the edges of incision did not exceed 80 μm. Negative polarity was found advantageous due to the lower rate of electrode erosion and due to better spatial confinement of the plasma-mediated discharge in liquid.

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

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

Shneider, Mikhail N., E-mail: m.n.shneider@gmail.com; Pekker, Mikhail

2015-06-14

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

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

NASA Astrophysics Data System (ADS)

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

2016-09-01

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

Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

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

Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.

2015-12-14

Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintainingmore » high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.« less

Particle-in-cell modeling of the nanosecond field emission driven discharge in pressurized hydrogen

NASA Astrophysics Data System (ADS)

Levko, Dmitry; Yatom, Shurik; Krasik, Yakov E.

2018-02-01

The high-voltage field-emission driven nanosecond discharge in pressurized hydrogen is studied using the one-dimensional Particle-in-Cell Monte Carlo collision model. It is obtained that the main part of the field-emitted electrons becomes runaway in the thin cathode sheath. These runaway electrons propagate the entire cathode-anode gap, creating rather dense (˜1012 cm-3) seeding plasma electrons. In addition, these electrons initiate a streamer propagating through this background plasma with a speed ˜30% of the speed of light. Such a high streamer speed allows the self-acceleration mechanism of runaway electrons present between the streamer head and the anode to be realized. As a consequence, the energy of runaway electrons exceeds the cathode-anode gap voltage. In addition, the influence of the field emission switching-off time is analyzed. It is obtained that this time significantly influences the discharge dynamics.

Asymmetrical Transmembrane Potential in Intracellular Organelles of Adrenal Chromatin Cells Exposed to Nanosecond Electric Pulses

NASA Astrophysics Data System (ADS)

Aramendia Zabaleta, Guillermo Jose

In our research on exploring the effects of 5 ns, high intensity electric pulses on neurosecretory adrenal chromaffin cells, cell modeling has played an important role in understanding and explaining the experimental results. Externally applied nanosecond-duration electric pulses (NEPs) can affect cells by creating nanopores in the cell and intracellular organelle membranes, making these membranes permeable to certain ions. A chromaffin cell contains, at a minimum, 7000 secretory granules plus other organelles such as mitochondria and the endoplasmic reticulum. In all the biological cell models constructed in the literature, there is no evidence of asymmetrical Transmembrane Potential (TMP) distribution in the intracellular membranes. However, these models do not include a realistic number of intracellular organelles. The goal of this research was to construct a more realistic cell model that incorporates a large number of secretory granules in the cytosol. To this end, a beta-version of the real-valued unstructured mesh Finite Element Method (FEM) electro-quasi-static module in Sim4life (SPEAG, Switzerland) has been used to model a chromaffin cell in which 1000 secretory granules are included in the cytosol. The model is, we believe, the most detailed geometrical cell model developed. It includes a spherical chromaffin cell (radius 8 mum), nucleus (radius 2.5 mum) located off-center, 500 granules (radius 200 nm) randomly located within a distance of 2 mum from the surface of the nucleus, and additional 500 granules randomly located in the remaining region of the cytosol. Cell and granule membrane thickness was set to 5 nm and nuclear membrane thickness to 10 nm. Dielectric properties of all constituents of the model were obtained from the literature or measured. Because the FEM Low Frequency solver is a quasi-static solver and not capable of accepting a time-varying pulse as input, all computations have been performed at single frequencies in the range DC to 60

The role of PIP2 and the IP3/DAG pathway in intracellular calcium release and cell survival during nanosecond electric pulse exposures

NASA Astrophysics Data System (ADS)

Steelman, Zachary A.; Tolstykh, Gleb P.; Estlack, Larry E.; Roth, Caleb C.; Ibey, Bennett L.

2015-03-01

Phosphatidylinositol4,5-biphosphate (PIP2) is a membrane phospholipid of particular importance in cell-signaling pathways. Hydrolysis of PIP2 releases inositol-1,4,5-triphosphate (IP3) from the membrane, activating IP3 receptors on the smooth endoplasmic reticulum (ER) and facilitating a release of intracellular calcium stores and activation of protein kinase C (PKC). Recent studies suggest that nanosecond pulsed electric fields (nsPEF) cause depletion of PIP2 in the cellular membrane, activating the IP3 signaling pathway. However, the exact mechanism(s) causing this observed depletion of PIP2 are unknown. Complicating the matter, nsPEF create nanopores in the plasma membrane, allowing calcium to enter the cell and thus causing an increase in intracellular calcium. While elevated intracellular calcium can cause activation of phospholipase C (PLC) (a known catalyst of PIP2 hydrolysis), PIP2 depletion has been shown to occur in the absence of both extracellular and intracellular calcium. These observations have led to the hypothesis that the high electric field itself may be playing a direct role in the hydrolysis of PIP2 from the plasma membrane. To support this hypothesis, we used edelfosine to block PLC and prevent activation of the IP3/DAG pathway in Chinese Hamster Ovarian (CHO) cells prior to applying nsPEF. Fluorescence microscopy was used to monitor intracellular calcium bursts during nsPEF, while MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) survivability assays were utilized to determine whether edelfosine improved cell survival during nsPEF exposure. This work is critical to refine the role of PIP2 in the cellular response to nsPEF, and also to determine the fundamental biological effects of high electric field exposures.

Absolute atomic oxygen density measurements for nanosecond-pulsed atmospheric-pressure plasma jets using two-photon absorption laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Jiang, C.; Carter, C.

2014-12-01

Nanosecond-pulsed plasma jets that are generated under ambient air conditions and free from confinement of electrodes have become of great interest in recent years due to their promising applications in medicine and dentistry. Reactive oxygen species that are generated by nanosecond-pulsed, room-temperature non-equilibrium He-O2 plasma jets among others are believed to play an important role during the bactericidal or sterilization processes. We report here absolute measurements of atomic oxygen density in a 1 mm-diameter He/(1%)O2 plasma jet at atmospheric pressure using two-photon absorption laser-induced fluorescence spectroscopy. Oxygen number density on the order of 1013 cm-3 was obtained in a 150 ns, 6 kV single-pulsed plasma jet for an axial distance up to 5 mm above the device nozzle. Temporally resolved O density measurements showed that there are two maxima, separated in time by 60-70 µs, and a total pulse duration of 260-300 µs. Electrostatic modeling indicated that there are high-electric-field regions near the nozzle exit that may be responsible for the observed temporal behavior of the O production. Both the field-distribution-based estimation of the time interval for the O number density profile and a pulse-energy-dependence study confirmed that electric-field-dependent, direct and indirect electron-induced processes play important roles for O production.

Electric Field Feature of Moving Magnetic Field

NASA Astrophysics Data System (ADS)

Chen, You Jun

2001-05-01

A new fundamental relationship of electric field with magnetic field has been inferred from the fundamental experimental laws and theories of classical electromagnetics. It can be described as moving magnetic field has or gives electric feature. When a field with magnetic induction of B moves in the velocity of V, it will show electric field character, the electric field intensity E is E = B x V and the direction of E is in the direction of the vector B x V. It is improper to use the time-varying electromagnetics theories as the fundamental theory of the electromagnetics and group the electromagnetic field into static kind and time-varying kind for the static is relative to motional not only time-varying. The relationship of time variation of magnetic field induction or magnetic flux with electric field caused by magnetic field is fellowship not causality. Thus time-varying magnetic field can cause electric field is not a nature principle. Sometime the time variation of magnetic flux is equal to the negative electromotive force or the time variation of magnetic field induction is equal to the negative curl of electric field caused by magnetic field motion, but not always. And not all motion of magnetic field can cause time variation of magnetic field. Therefore Faraday-Lenz`s law can only be used as mathematics tool to calculate the quantity relation of the electricity with the magnetism in some case like the magnetic field moving in uniform medium. Faraday-Lenz`s law is unsuitable to be used in moving uniform magnetic field or there is magnetic shield. Key word: Motional magnetic field, Magnetic induction, Electric field intensity, Velocity, Faraday-Lenz’s law

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.

A Tesla-type repetitive nanosecond pulse generator for solid dielectric breakdown research.

PubMed

Zhao, Liang; Pan, Ya Feng; Su, Jian Cang; Zhang, Xi Bo; Wang, Li Min; Fang, Jin Peng; Sun, Xu; Lui, Rui

2013-10-01

A Tesla-type repetitive nanosecond pulse generator including a pair of electrode and a matched absorption resistor is established for the application of solid dielectric breakdown research. As major components, a built-in Tesla transformer and a gas-gap switch are designed to boost and shape the output pulse, respectively; the electrode is to form the anticipated electric field; the resistor is parallel to the electrode to absorb the reflected energy from the test sample. The parameters of the generator are a pulse width of 10 ns, a rise and fall time of 3 ns, and a maximum amplitude of 300 kV. By modifying the primary circuit of the Tesla transformer, the generator can produce both positive and negative pulses at a repetition rate of 1-50 Hz. In addition, a real-time measurement and control system is established based on the solid dielectric breakdown requirements for this generator. With this system, experiments on test samples made of common insulation materials in pulsed power systems are conducted. The preliminary experimental results show that the constructed generator is capable to research the solid dielectric breakdown phenomenon on a nanosecond time scale.

Sub-nanosecond dynamics in low-dimensional systems

NASA Astrophysics Data System (ADS)

Armstrong-Brown, Alistair

The sub-nanosecond dynamics of a two-dimensional electron gas (2DEG) are studied in conditions of high fields and low temperatures. Three main regimes are identified. Firstly, the propagation of sub-nanosecond, or GHz, signals in a 2DEG waveguide at low temperature (2 K) and high magnetic field (9 T). Here we show that the 2DEG waveguide can be fully parameterised by the Hall resistance and a new 'microwave scaling constant'. Secondly, the physics of plasmons confined at the edge and in a magnetic field (9 T): edge magnetoplasmons (EMPs). Here we resolve multiple plasmon modes, where as well as the standard EMP resonances, we discover additional lower frequency modes, which could be related to transverse acoustic excitations. Thirdly, tunneling into microwave induced resistance oscillation (MIRO) states at low temperatures (50 mK). By using a novel cleaved edge overgrown (CEO) technique we are able to identify the role of photon assisted tunneling (PAT) in the formation of MIROs. These experimental results were obtained by developing new techniques combining microwaves, low temperatures, 2DEGs and high magnetic fields, which required the design and fabrication of several novel probes for these regimes.

Analysis of Surface Electric Field Measurements from an Array of Electric Field Mills

NASA Astrophysics Data System (ADS)

Lucas, G.; Thayer, J. P.; Deierling, W.

2016-12-01

Kennedy Space Center (KSC) has operated an distributed array of over 30 electric field mills over the past 18 years, providing a unique data set of surface electric field measurements over a very long timespan. In addition to the electric field instruments there are many meteorological towers around KSC that monitor the local meteorological conditions. Utilizing these datasets we have investigated and found unique spatial and temporal signatures in the electric field data that are attributed to local meteorological effects and the global electric circuit. The local and global scale influences on the atmospheric electric field will be discussed including the generation of space charge from the ocean surf, local cloud cover, and a local enhancement in the electric field that is seen at sunrise.

Tripolar electric field Structure in guide field magnetic reconnection

NASA Astrophysics Data System (ADS)

Fu, Song; Huang, Shiyong; Zhou, Meng; Ni, Binbin; Deng, Xiaohua

2018-03-01

It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

Practical photon number detection with electric field-modulated silicon avalanche photodiodes.

PubMed

Thomas, O; Yuan, Z L; Shields, A J

2012-01-24

Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current.

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.

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.

Fast gas heating and radial distribution of active species in nanosecond capillary discharge in pure nitrogen and N2:O2 mixtures

NASA Astrophysics Data System (ADS)

Lepikhin, N. D.; Popov, N. A.; Starikovskaia, S. M.

2018-05-01

Fast gas heating is studied experimentally and numerically using pulsed nanosecond capillary discharge in pure nitrogen and N2:O2 mixtures under the conditions of high specific deposited energy (up to 1 eV/molecule) and high reduced electric fields (100–300 Td). Deposited energy, electric field and gas temperature are measured as functions of time. The radial distribution of active species is analyzed experimentally. The roles of processes involving {{{N}}}2({{B}}) ={{{N}}}2({{{B}}}3{{{\\Pi }}}{{g}},{{{W}}}3{{{Δ }}}{{u}},{{B}}{{\\prime} }3{{{Σ }}}{{u}}-), {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+) and N(2D) excited nitrogen species leading to heat release are analyzed using numerical modeling in the framework of 1D axial approximation.

Human aquaporin 4 gating dynamics under and after nanosecond-scale static and alternating electric-field impulses: a molecular dynamics study of field effects and relaxation.

PubMed

Reale, Riccardo; English, Niall J; Garate, José-Antonio; Marracino, Paolo; Liberti, Micaela; Apollonio, Francesca

2013-11-28

Water self-diffusion and the dipolar response of the selectivity filter within human aquaporin 4 have been studied using molecular dynamics (MD) simulations in the absence and presence of pulses of external static and alternating electric fields. The pulses were approximately 50 and 100 ns in duration and 0.0065 V/Å in (r.m.s.) intensity and were either static or else 2.45 or 100 GHz in frequency and applied both along and perpendicular to the channels. In addition, the relaxation of the aquaporin, water self-diffusion and gating dynamics following cessation of the impulses was studied. In previous work it was determined that switches in the dihedral angle of the selectivity filter led to boosting of water permeation events within the channels, in the presence of identical external static and alternating electric fields, although applied continuously. Here the application of field impulses (and subsequently, upon removal) has shown that it is the dipolar orientation of the histidine-201 residue in the selectivity filter which governs the dihedral angle, and hence influences water self-diffusion; this constitutes an appropriate order parameter. The dipolar response of this residue to the applied field leads to the adoption of four distinct states, which we modelled as time-homogeneous Markov jump processes, and may be distinguished in the potential of mean force (PMF) as a function of the dipolar orientation of histidine-201. The observations of enhanced "dipolar flipping" of H201 serve to explain increased levels of water self-diffusion within aquaporin channels during, and immediately following, field impulses, although the level of statistical certainty here is lower. Given the appreciable size of the energy barriers evident in PMFs computed directly from deterministic MD (whether in the absence or presence of external fields), metadynamics calculations were undertaken to explore the free-energy landscape of histidine-201 orientation with greater accuracy and

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.

Sub-nanosecond signal propagation in anisotropy-engineered nanomagnetic logic chains

DOE PAGES

Gu, Zheng; Nowakowski, Mark E.; Carlton, David B.; ...

2015-03-16

Energy efficient nanomagnetic logic (NML) computing architectures propagate binary information by relying on dipolar field coupling to reorient closely spaced nanoscale magnets. In the past, signal propagation in nanomagnet chains were characterized by static magnetic imaging experiments; however, the mechanisms that determine the final state and their reproducibility over millions of cycles in high-speed operation have yet to be experimentally investigated. Here we present a study of NML operation in a high-speed regime. We perform direct imaging of digital signal propagation in permalloy nanomagnet chains with varying degrees of shape-engineered biaxial anisotropy using full-field magnetic X-ray transmission microscopy and time-resolvedmore » photoemission electron microscopy after applying nanosecond magnetic field pulses. Moreover, an intrinsic switching time of 100 ps per magnet is observed. In conclusion these experiments, and accompanying macrospin and micromagnetic simulations, reveal the underlying physics of NML architectures repetitively operated on nanosecond timescales and identify relevant engineering parameters to optimize performance and reliability.« less

Nanosecond pulse lasers for retinal applications.

PubMed

Wood, John P M; Plunkett, Malcolm; Previn, Victor; Chidlow, Glyn; Casson, Robert J

2011-08-01

Thermal lasers are routinely used to treat certain retinal disorders although they cause collateral damage to photoreceptors. The current study evaluated a confined, non-conductive thermal, 3-nanosecond pulse laser in order to determine how to produce the greatest therapeutic range without causing collateral damage. Data were compared with that obtained from a standard thermal laser. Porcine ocular explants were used; apposed neuroretina was also in place for actual laser treatment. After treatment, the retina was removed and a calcein-AM assay was used to assess retinal pigmented epithelium (RPE) cell viability in the explants. Histological methods were also employed to examine lased transverse explant sections. Three nanoseconds pulse lasers with either speckle- or gaussian-beam profile were employed in the study. Comparisons were made with a 100 milliseconds continuous wave (CW) 532 nm laser. The therapeutic energy range ratio was defined as the minimum visible effect threshold (VET) versus the minimum detectable RPE kill threshold. The 3-nanosecond lasers produced markedly lower minimum RPE kill threshold levels than the CW laser (e.g., 36 mJ/cm(2) for speckle-beam and 89 mJ/cm(2) for gaussian-beam profile nanosecond lasers vs. 7,958 mJ/cm(2) for CW laser). VET values were also correspondingly lower for the nanosecond lasers (130 mJ/cm(2) for 3 nanoseconds speckle-beam and 219 mJ/cm(2) for gaussian-beam profile vs. 1,0346 mJ/cm(2) for CW laser). Thus, the therapeutic range ratios obtained with the nanosecond lasers were much more favorable than that obtained by the CW laser: 3.6:1 for the speckle-beam and 2.5:1 for the gaussian-beam profile 3-nanosecond lasers versus 1.3:1 for the CW laser. Nanosecond lasers, particularly with a speckle-beam profile, provide a much wider therapeutic range of energies over which RPE treatment can be performed, without damage to the apposed retina, as compared with conventional CW lasers. These results may have

Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

NASA Astrophysics Data System (ADS)

Takashima, Keisuke; Kaneko, Toshiro

2016-09-01

The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications.

Simulations of nanosecond-pulsed dielectric barrier discharges in atmospheric pressure air

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

Soo Bak, Moon; Cappelli, Mark A.

2013-03-21

This paper describes simulations of nanosecond pulse plasma formation between planer electrodes covered by dielectric barriers in air at atmospheric pressure and 340 K. The plasma formation process starts as electrons detach from negative ions of molecular oxygen that are produced from the previous discharge pulse. An ionization front is found to form close to the positively biased electrode and then strengthens and propagates towards the grounded electrode with increasing gap voltage. Charge accumulation and secondary emission from the grounded electrode eventually lead to sheath collapse. One interesting feature is a predicted reversal in gap potential due to the accumulatedmore » charge, even when there is no reversal in applied potential. The simulation results are compared to recent measurement of mid-gap electric field under the same discharge conditions [Ito et al., Phys. Rev. Lett. 107, 065002 (2011)].« less

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

Cryosurgery with pulsed electric fields.

PubMed

Daniels, Charlotte S; Rubinsky, Boris

2011-01-01

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

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

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.

Surface charge accumulation of solid insulator under nanosecond pulse in vacuum: 3D distribution features and mechanism

NASA Astrophysics Data System (ADS)

Qi, Bo; Gao, Chunjia; Sun, Zelai; Li, Chengrong

2017-11-01

Surface charge accumulation can incur changes in electric field distribution, involved in the electron propagation process, and result in a significant decrease in the surface flashover voltage. The existing 2D surface charge measurement fails to meet the actual needs in real engineering applications that usually adopt the 45° conical frustum insulators. The present research developed a novel 3D measurement platform to capture surface charge distribution on solid insulation under nanosecond pulse in a vacuum. The results indicate that all surface charges are positive under a positive pulse and negative under a negative pulse. Surface charges tend to accumulate more near the upper electrode. Surface charge density increases significantly with the increase in pulse counts and amplitudes. Accumulation of surface charge results in a certain decrease of flashover voltage. Taking consideration of the secondary electron emission for the surface charge accumulation, four materials were obtained to demonstrate the effects on surface charge. Combining the effect incurred by secondary electron emission and the weighty action taken by surface charge accumulation on the flashover phenomena, the discharge mechanism along the insulator surface under nanosecond pulse voltage was proposed.

Electric Field Fluctuations in Water

NASA Astrophysics Data System (ADS)

Thorpe, Dayton; Limmer, David; Chandler, David

2013-03-01

Charge transfer in solution, such as autoionization and ion pair dissociation in water, is governed by rare electric field fluctuations of the solvent. Knowing the statistics of such fluctuations can help explain the dynamics of these rare events. Trajectories short enough to be tractable by computer simulation are virtually certain not to sample the large fluctuations that promote rare events. Here, we employ importance sampling techniques with classical molecular dynamics simulations of liquid water to study statistics of electric field fluctuations far from their means. We find that the distributions of electric fields located on individual water molecules are not in general gaussian. Near the mean this non-gaussianity is due to the internal charge distribution of the water molecule. Further from the mean, however, there is a previously unreported Bjerrum-like defect that stabilizes certain large fluctuations out of equilibrium. As expected, differences in electric fields acting between molecules are gaussian to a remarkable degree. By studying these differences, though, we are able to determine what configurations result not only in large electric fields, but also in electric fields with long spatial correlations that may be needed to promote charge separation.

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

PubMed

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

2012-10-22

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

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.

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.

Effect of Nanosecond RF Pulses on Mitochondrial Membranes

NASA Astrophysics Data System (ADS)

Zharkova, L. P.; Romanchenko, I. V.; Bol'shakov, M. A.; Rostov, V. V.

2017-12-01

Effect of nanosecond RF pulses on the state of isolated mitochondria and their membranes is investigated. Mitochondrial suspensions are exposed to periodic RF pulses with durations from 4 to 25 ns, frequencies from 0.6 to 1.0 GHz, amplitudes from 0.1 to 36 kV/cm, and pulse repetition frequencies 8-25 Hz. The integrity of the mitochondrial membranes is estimated from their resistance to electric current. The possibility of opening of protein pores with nonspecific permeability is determined from a change in the mitochondrial volume by registration of optical density of organelle suspension.

Conductivity affects nanosecond electrical pulse induced pressure transient formation

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Ionic Conductivity, Structural Deformation and Programmable Anisotropy of DNA Origami in Electric Field

PubMed Central

Li, Chen-Yu; Hemmig, Elisa A.; Kong, Jinglin; Yoo, Jejoong; Hernández-Ainsa, Silvia

2015-01-01

The DNA origami technique can enable functionalization of inorganic structures for single-molecule electric current recordings. Experiments have shown that several layers of DNA molecules—a DNA origami plate— placed on top of a solid-state nanopore is permeable to ions. Here, we report a comprehensive characterization of the ionic conductivity of DNA origami plates by means of all-atom molecular dynamics (MD) simulations and nanocapillary electric current recordings. Using the MD method, we characterize the ionic conductivity of several origami constructs, revealing the local distribution of ions, the distribution of the electrostatic potential and contribution of different molecular species to the current. The simulations determine the dependence of the ionic conductivity on the applied voltage, the number of DNA layers, the nucleotide content and the lattice type of the plates. We demonstrate that increasing the concentration of Mg2+ ions makes the origami plates more compact, reducing their conductivity. The conductance of a DNA origami plate on top of a solid-state nanopore is determined by the two competing effects: bending of the DNA origami plate that reduces the current and separation of the DNA origami layers that increases the current. The latter is produced by the electro-osmotic flow and is reversible at the time scale of a hundred nanoseconds. The conductance of a DNA origami object is found to depend on its orientation, reaching maximum when the electric field aligns with the direction of the DNA helices. Our work demonstrates feasibility of programming the electrical properties of a self-assembled nanoscale object using DNA. PMID:25623807

Ionic conductivity, structural deformation, and programmable anisotropy of DNA origami in electric field.

PubMed

Li, Chen-Yu; Hemmig, Elisa A; Kong, Jinglin; Yoo, Jejoong; Hernández-Ainsa, Silvia; Keyser, Ulrich F; Aksimentiev, Aleksei

2015-02-24

The DNA origami technique can enable functionalization of inorganic structures for single-molecule electric current recordings. Experiments have shown that several layers of DNA molecules, a DNA origami plate, placed on top of a solid-state nanopore is permeable to ions. Here, we report a comprehensive characterization of the ionic conductivity of DNA origami plates by means of all-atom molecular dynamics (MD) simulations and nanocapillary electric current recordings. Using the MD method, we characterize the ionic conductivity of several origami constructs, revealing the local distribution of ions, the distribution of the electrostatic potential and contribution of different molecular species to the current. The simulations determine the dependence of the ionic conductivity on the applied voltage, the number of DNA layers, the nucleotide content and the lattice type of the plates. We demonstrate that increasing the concentration of Mg(2+) ions makes the origami plates more compact, reducing their conductivity. The conductance of a DNA origami plate on top of a solid-state nanopore is determined by the two competing effects: bending of the DNA origami plate that reduces the current and separation of the DNA origami layers that increases the current. The latter is produced by the electro-osmotic flow and is reversible at the time scale of a hundred nanoseconds. The conductance of a DNA origami object is found to depend on its orientation, reaching maximum when the electric field aligns with the direction of the DNA helices. Our work demonstrates feasibility of programming the electrical properties of a self-assembled nanoscale object using DNA.

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

Nanosecond laser pulse stimulation of spiral ganglion neurons and model cells.

PubMed

Rettenmaier, Alexander; Lenarz, Thomas; Reuter, Günter

2014-04-01

Optical stimulation of the inner ear has recently attracted attention, suggesting a higher frequency resolution compared to electrical cochlear implants due to its high spatial stimulation selectivity. Although the feasibility of the effect is shown in multiple in vivo experiments, the stimulation mechanism remains open to discussion. Here we investigate in single-cell measurements the reaction of spiral ganglion neurons and model cells to irradiation with a nanosecond-pulsed laser beam over a broad wavelength range from 420 nm up to 1950 nm using the patch clamp technique. Cell reactions were wavelength- and pulse-energy-dependent but too small to elicit action potentials in the investigated spiral ganglion neurons. As the applied radiant exposure was much higher than the reported threshold for in vivo experiments in the same laser regime, we conclude that in a stimulation paradigm with nanosecond-pulses, direct neuronal stimulation is not the main cause of optical cochlea stimulation.

Nanosecond Enhancements of the Atmospheric Electron Density by Extensive Air Showers

NASA Astrophysics Data System (ADS)

Rutjes, C.; Camporeale, E.; Ebert, U.; Buitink, S.; Scholten, O.; Trinh, G. T. N.; Witteveen, J.

2015-12-01

As is well known a sufficient density of free electrons and strong electric fields are the basic requirements to start any electrical discharge. In the context of thunderstorm discharges it has become clear that in addition droplets and or ice particles are required to enhance the electric field to values above breakdown. In our recent study [1] we have shown that these three ingredients have to interplay to allow for lightning inception, triggered by an extensive air shower event. The extensive air showers are a very stochastic natural phenomenon, creating highly coherent sub-nanosecond enhancements of the atmospheric electron density. Predicting these electron density enhancements accurately one has to take the uncertainty of the input variables into account. For this study we use the initial energy, inclination and altitude of first interaction, which will influence the evolution of the shower significantly. To this end, we use the stochastic collocation method, [2] to post-process our detailed Monte Carlo extensive air shower simulations, done with the CORSIKA [3] software package, which provides an efficient and elegant way to determine the distribution of the atmospheric electron density enhancements. [1] Dubinova, A., Rutjes, C., Ebert, E., Buitink, S., Scholten, O., and Trinh, G. T. N. "Prediction of Lightning Inception by Large Ice Particles and Extensive Air Showers." PRL 115 015002 (2015)[2] G.J.A. Loeven, J.A.S. Witteveen, H. Bijl, Probabilistic collocation: an efficient nonintrusive approach for arbitrarily distributed parametric uncertainties, 45th AIAA Aerospace Sciences Meeting, Reno, Nevada, 2007, AIAA-2007-317[3] Heck, Dieter, et al. CORSIKA: A Monte Carlo code to simulate extensive air showers. No. FZKA-6019. 1998.

Underwater electric field detection system based on weakly electric fish

NASA Astrophysics Data System (ADS)

Xue, Wei; Wang, Tianyu; Wang, Qi

2018-04-01

Weakly electric fish sense their surroundings in complete darkness by their active electric field detection system. However, due to the insufficient detection capacity of the electric field, the detection distance is not enough, and the detection accuracy is not high. In this paper, a method of underwater detection based on rotating current field theory is proposed to improve the performance of underwater electric field detection system. First of all, we built underwater detection system based on the theory of the spin current field mathematical model with the help of the results of previous researchers. Then we completed the principle prototype and finished the metal objects in the water environment detection experiments, laid the foundation for the further experiments.

Low charge state heavy ion production with sub-nanosecond laser.

PubMed

Kanesue, T; Kumaki, M; Ikeda, S; Okamura, M

2016-02-01

We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

Cellular response to high pulse repetition rate nanosecond pulses varies with fluorescent marker identity

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

Steelman, Zachary A., E-mail: zachary.steelman@duke.edu; Tolstykh, Gleb P.; Beier, Hope T.

Nanosecond electric pulses (nsEP's) are a well-studied phenomena in biophysics that cause substantial alterations to cellular membrane dynamics, internal biochemistry, and cytoskeletal structure, and induce apoptotic and necrotic cell death. While several studies have attempted to measure the effects of multiple nanosecond pulses, the effect of pulse repetition rate (PRR) has received little attention, especially at frequencies greater than 100 Hz. In this study, uptake of Propidium Iodide, FM 1–43, and YO-PRO-1 fluorescent dyes in CHO-K1 cells was monitored across a wide range of PRRs (5 Hz–500 KHz) using a laser-scanning confocal microscope in order to better understand how high frequency repetition ratesmore » impact induced biophysical changes. We show that frequency trends depend on the identity of the dye under study, which could implicate transmembrane protein channels in the uptake response due to their chemical selectivity. Finally, YO-PRO-1 fluorescence was monitored in the presence of Gadolinium (Gd{sup 3+}), Ruthenium Red, and in calcium-free solution to elucidate a mechanism for its unique frequency trend. - Highlights: • Pulse repetition rate (PRR) is understudied in nanosecond electric pulsing. • 200 V pulses were applied to CHO-K1 cells from 5 Hz to 500 KHz. • Pulsing was repeated using a variety of fluorophores and imaging conditions. • The response is highly dependent on the fluorophore and the imaging conditions. • This may implicate protein channels in the nanoporation response.« less

Low charge state heavy ion production with sub-nanosecond laser

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

Kanesue, T., E-mail: tkanesue@bnl.gov; Okamura, M.; Kumaki, M.

2016-02-15

We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the differencemore » of generated plasma using the Zirconium target.« less

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

Comparative evaluation of transmembrane ion transport due to monopolar and bipolar nanosecond, high-intensity electroporation pulses based on full three-dimensional analyses

NASA Astrophysics Data System (ADS)

Hu, Q.; Joshi, R. P.

2017-07-01

Electric pulse driven membrane poration finds applications in the fields of biomedical engineering and drug/gene delivery. Here we focus on nanosecond, high-intensity electroporation and probe the role of pulse shape (e.g., monopolar-vs-bipolar), multiple electrode scenarios, and serial-versus-simultaneous pulsing, based on a three-dimensional time-dependent continuum model in a systematic fashion. Our results indicate that monopolar pulsing always leads to higher and stronger cellular uptake. This prediction is in agreement with experimental reports and observations. It is also demonstrated that multi-pronged electrode configurations influence and increase the degree of cellular uptake.

Electric Field Sensor for Lightning Early Warning System

NASA Astrophysics Data System (ADS)

Premlet, B.; Mohammed, R.; Sabu, S.; Joby, N. E.

2017-12-01

Electric field mills are used popularly for atmospheric electric field measurements. Atmospheric Electric Field variation is the primary signature for Lightning Early Warning systems. There is a characteristic change in the atmospheric electric field before lightning during a thundercloud formation.A voltage controlled variable capacitance is being proposed as a method for non-contacting measurement of electric fields. A varactor based mini electric field measurement system is developed, to detect any change in the atmospheric electric field and to issue lightning early warning system. Since this is a low-cost device, this can be used for developing countries which are facing adversities. A network of these devices can help in forming a spatial map of electric field variations over a region, and this can be used for more improved atmospheric electricity studies in developing countries.

Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

NASA Astrophysics Data System (ADS)

Shlapakovski, A. S.; Beilin, L.; Hadas, Y.; Schamiloglu, E.; Krasik, Ya. E.

2015-07-01

Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

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

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.

Time-resolved absolute measurements by electro-optic effect of giant electromagnetic pulses due to laser-plasma interaction in nanosecond regime

PubMed Central

Consoli, F.; De Angelis, R.; Duvillaret, L.; Andreoli, P. L.; Cipriani, M.; Cristofari, G.; Di Giorgio, G.; Ingenito, F.; Verona, C.

2016-01-01

We describe the first electro-optical absolute measurements of electromagnetic pulses (EMPs) generated by laser-plasma interaction in nanosecond regime. Laser intensities are inertial-confinement-fusion (ICF) relevant and wavelength is 1054 nm. These are the first direct EMP amplitude measurements with the detector rather close and in direct view of the plasma. A maximum field of 261 kV/m was measured, two orders of magnitude higher than previous measurements by conductive probes on nanosecond regime lasers with much higher energy. The analysis of measurements and of particle-in-cell simulations indicates that signals match the emission of charged particles detected in the same experiment, and suggests that anisotropic particle emission from target, X-ray photoionization and charge implantation on surfaces directly exposed to plasma, could be important EMP contributions. Significant information achieved on EMP features and sources is crucial for future plants of laser-plasma acceleration and inertial-confinement-fusion and for the use as effective plasma diagnostics. It also opens to remarkable applications of laser-plasma interaction as intense source of RF-microwaves for studies on materials and devices, EMP-radiation-hardening and electromagnetic compatibility. The demonstrated extreme effectivity of electric-fields detection in laser-plasma context by electro-optic effect, leads to great potential for characterization of laser-plasma interaction and generated Terahertz radiation. PMID:27301704

Time-resolved absolute measurements by electro-optic effect of giant electromagnetic pulses due to laser-plasma interaction in nanosecond regime

NASA Astrophysics Data System (ADS)

Consoli, F.; de Angelis, R.; Duvillaret, L.; Andreoli, P. L.; Cipriani, M.; Cristofari, G.; di Giorgio, G.; Ingenito, F.; Verona, C.

2016-06-01

We describe the first electro-optical absolute measurements of electromagnetic pulses (EMPs) generated by laser-plasma interaction in nanosecond regime. Laser intensities are inertial-confinement-fusion (ICF) relevant and wavelength is 1054 nm. These are the first direct EMP amplitude measurements with the detector rather close and in direct view of the plasma. A maximum field of 261 kV/m was measured, two orders of magnitude higher than previous measurements by conductive probes on nanosecond regime lasers with much higher energy. The analysis of measurements and of particle-in-cell simulations indicates that signals match the emission of charged particles detected in the same experiment, and suggests that anisotropic particle emission from target, X-ray photoionization and charge implantation on surfaces directly exposed to plasma, could be important EMP contributions. Significant information achieved on EMP features and sources is crucial for future plants of laser-plasma acceleration and inertial-confinement-fusion and for the use as effective plasma diagnostics. It also opens to remarkable applications of laser-plasma interaction as intense source of RF-microwaves for studies on materials and devices, EMP-radiation-hardening and electromagnetic compatibility. The demonstrated extreme effectivity of electric-fields detection in laser-plasma context by electro-optic effect, leads to great potential for characterization of laser-plasma interaction and generated Terahertz radiation.

Nanosecond Pulsed Discharge in Water without Bubbles: A Fundamental Study of Initiation, Propagation and Plasma Characteristics

NASA Astrophysics Data System (ADS)

Seepersad, Yohan

The state of plasma is widely known as a gas-phase phenomenon, but plasma in liquids have also received significant attention over the last century. Generating plasma in liquids however is theoretically challenging, and this problem is often overcome via liquid-gas phase transition preceding the actual plasma formation. In this sense, plasma forms in gas bubbles in the liquid. Recent work at the Drexel Plasma Institute has shown that nanosecond pulsed electric fields can initiate plasma in liquids without any initial cavitation phase, at voltages below theoretical direct-ionization thresholds. This unique regime is poorly understood and does not fit into any current descriptive mechanisms. As with all new phenomena, a complete fundamental description is paramount to understanding its usefulness to practical applications. The primary goals of this research were to qualitatively and quantitatively understand the phenomenon of nanosecond pulsed discharge in liquids as a means to characterizing properties that may open up niche application possibilities. Analysis of the plasma was based on experimental results from non-invasive, sub-nanosecond time-resolved optical diagnostics, including direct imaging, transmission imaging (Schlieren and shadow), and optical emission spectroscopy. The physical characteristics of the plasma were studied as a function of variations in the electric field amplitude and polarity, liquid permittivity, and pulse duration. It was found that the plasma size and emission intensity was dependent on the permittivity of the liquid, as well as the voltage polarity, and the structure and dynamics were explained by a 'cold-lightning' mechanism. The under-breakdown dynamics at the liquid-electrode interface were investigated by transmission imaging to provide evidence for a novel mechanism for initiation based on the electrostriction. This mechanism was proposed by collaborators on the project and developed alongside the experimental work in this

Evaluation of the Genetic Response of U937 and Jurkat Cells to 10-Nanosecond Electrical Pulses (nsEP)

PubMed Central

Glickman, Randolph D.; Tolstykh, Gleb P.; Estlack, Larry E.; Moen, Erick K.; Echchgadda, Ibtissam; Beier, Hope T.; Barnes, Ronald A.; Ibey, Bennett L.

2016-01-01

Nanosecond electrical pulse (nsEP) exposure activates signaling pathways, produces oxidative stress, stimulates hormone secretion, causes cell swelling and induces apoptotic and necrotic death. The underlying biophysical connection(s) between these diverse cellular reactions and nsEP has yet to be elucidated. Using global genetic analysis, we evaluated how two commonly studied cell types, U937 and Jurkat, respond to nsEP exposure. We hypothesized that by studying the genetic response of the cells following exposure, we would gain direct insight into the stresses experienced by the cell and in turn better understand the biophysical interaction taking place during the exposure. Using Ingenuity Systems software, we found genes associated with cell growth, movement and development to be significantly up-regulated in both cell types 4 h post exposure to nsEP. In agreement with our hypothesis, we also found that both cell lines exhibit significant biological changes consistent with mechanical stress induction. These results advance nsEP research by providing strong evidence that the interaction of nsEPs with cells involves mechanical stress. PMID:27135944

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

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.

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.

Lattice QCD with strong external electric fields.

PubMed

Yamamoto, Arata

2013-03-15

We study particle generation by a strong electric field in lattice QCD. To avoid the sign problem of the Minkowskian electric field, we adopt the "isospin" electric charge. When a strong electric field is applied, the insulating vacuum is broken down and pairs of charged particles are produced by the Schwinger mechanism. The competition against the color confining force is also discussed.

Hybrid micromachining using a nanosecond pulsed laser and micro EDM

NASA Astrophysics Data System (ADS)

Kim, Sanha; Kim, Bo Hyun; Chung, Do Kwan; Shin, Hong Shik; Chu, Chong Nam

2010-01-01

Micro electrical discharge machining (micro EDM) is a well-known precise machining process that achieves micro structures of excellent quality for any conductive material. However, the slow machining speed and high tool wear are main drawbacks of this process. Though the use of deionized water instead of kerosene as a dielectric fluid can reduce the tool wear and increase the machine speed, the material removal rate (MRR) is still low. In contrast, laser ablation using a nanosecond pulsed laser is a fast and non-wear machining process but achieves micro figures of rather low quality. Therefore, the integration of these two processes can overcome the respective disadvantages. This paper reports a hybrid process of a nanosecond pulsed laser and micro EDM for micromachining. A novel hybrid micromachining system that combines the two discrete machining processes is introduced. Then, the feasibility and characteristics of the hybrid machining process are investigated compared to conventional EDM and laser ablation. It is verified experimentally that the machining time can be effectively reduced in both EDM drilling and milling by rapid laser pre-machining prior to micro EDM. Finally, some examples of complicated 3D micro structures fabricated by the hybrid process are shown.

Nanosecond liquid crystalline optical modulator

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

Borshch, Volodymyr; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

2016-07-26

An optical modulator includes a liquid crystal cell containing liquid crystal material having liquid crystal molecules oriented along a quiescent director direction in the unbiased state, and a voltage source configured to apply an electric field to the liquid crystal material wherein the direction of the applied electric field does not cause the quiescent director direction to change. An optical source is arranged to transmit light through or reflect light off the liquid crystal cell with the light passing through the liquid crystal material at an angle effective to undergo phase retardation in response to the voltage source applying themore » electric field. The liquid crystal material may have negative dielectric anisotropy, and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is transverse to the quiescent director direction. Alternatively, the liquid crystal material may have positive dielectric anisotropy and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is parallel with the quiescent director direction.« less

Imaging electric field dynamics with graphene optoelectronics.

PubMed

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

2016-12-16

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.

Imaging electric field dynamics with graphene optoelectronics

DOE PAGES

Horng, Jason; Balch, Halleh B.; McGuire, Allister F.; ...

2016-12-16

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,more » 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.« less

Imaging electric field dynamics with graphene optoelectronics

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

Horng, Jason; Balch, Halleh B.; McGuire, Allister F.

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,more » 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.« less

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.

Effectiveness of External Electric Field Treatment of Conjugated Polymers in Bulk-Heterojunction Solar Cells.

PubMed

Solanki, Ankur; Bagui, Anirban; Long, Guankui; Wu, Bo; Salim, Teddy; Chen, Yongsheng; Lam, Yeng Ming; Sum, Tze Chien

2016-11-30

External electric field treatment (EFT) on P3HT:PCBM bulk heterojunction (BHJ) devices was recently found to be a viable approach for improving the power conversion efficiencies (PCEs) through modulating the blend nanomorphology. However, its effectiveness over the broad family of polymer-fullerene blends remains unclear. Herein, we investigate the effects of external EFT on various polymer-fullerene blends with distinct morphologies stemming from the difference in molecular structure of the polymers (i.e., semicrystalline vs amorphous) in a bid to establish a clear morphology-function-charge dynamics relationship to the photovoltaic performance. Our findings reveal that EFT promotes self-organization of the semicrystalline thiophene-based conjugated polymers (i.e., P3HT and P3BT) while it was ineffective for the amorphous polymers (i.e., PTB7 and PCPDTBT) even at the maximum applied E-field of 8 kV cm -1 . Transient absorption spectroscopy shows an improvement in the initial charge-carrier and polaron formation from delocalized excitons in the E-field treated semicrystalline blends compared to their untreated reference samples. Interfacial trap-assisted monomolecular and trap-free bimolecular recombination at nanosecond-microsecond time scale in the E-field treated P3BT:PC60BM devices are significantly suppressed. Importantly, our findings shed new light and provide guidelines on the effectiveness of utilizing external EFT to enhance the PCEs of a larger family of conjugated polymer-based BHJ OSCs.

Simple estimation of induced electric fields in nervous system tissues for human exposure to non-uniform electric fields at power frequency

NASA Astrophysics Data System (ADS)

Tarao, Hiroo; Miyamoto, Hironobu; Korpinen, Leena; Hayashi, Noriyuki; Isaka, Katsuo

2016-06-01

Most results regarding induced current in the human body related to electric field dosimetry have been calculated under uniform field conditions. We have found in previous work that a contact current is a more suitable way to evaluate induced electric fields, even in the case of exposure to non-uniform fields. If the relationship between induced currents and external non-uniform fields can be understood, induced electric fields in nervous system tissues may be able to be estimated from measurements of ambient non-uniform fields. In the present paper, we numerically calculated the induced electric fields and currents in a human model by considering non-uniform fields based on distortion by a cubic conductor under an unperturbed electric field of 1 kV m-1 at 60 Hz. We investigated the relationship between a non-uniform external electric field with no human present and the induced current through the neck, and the relationship between the current through the neck and the induced electric fields in nervous system tissues such as the brain, heart, and spinal cord. The results showed that the current through the neck can be formulated by means of an external electric field at the central position of the human head, and the distance between the conductor and the human model. As expected, there is a strong correlation between the current through the neck and the induced electric fields in the nervous system tissues. The combination of these relationships indicates that induced electric fields in these tissues can be estimated solely by measurements of the external field at a point and the distance from the conductor.

Reception and learning of electric fields in bees.

PubMed

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

2013-05-22

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.

Investigation of airfoil leading edge separation control with nanosecond plasma actuator

NASA Astrophysics Data System (ADS)

Zheng, J. G.; Cui, Y. D.; Zhao, Z. J.; Li, J.; Khoo, B. C.

2016-11-01

A combined numerical and experimental investigation of airfoil leading edge flow separation control with a nanosecond dielectric barrier discharge (DBD) plasma actuator is presented. Our study concentrates on describing dynamics of detailed flow actuation process and elucidating the nanosecond DBD actuation mechanism. A loose coupling methodology is employed to perform simulation, which consists of a self-similar plasma model for the description of pulsed discharge and two-dimensional Reynolds averaged Navier-Stokes (RANS) equations for the calculation of external airflow. A series of simulations of poststall flows around a NACA0015 airfoil is conducted with a Reynolds number range covering both low and high Re at Re=(0.05 ,0.15 ,1.2 ) ×106 . Meanwhile, wind-tunnel experiment is performed for two low Re flows to measure aerodynamic force on airfoil model and transient flow field with time-resolved particle image velocimetry (PIV). The PIV measurement provides possibly the clearest view of flow reattachment process under the actuation of a nanosecond plasma actuator ever observed in experiments, which is highly comparable to that predicted by simulation. It is found from the detailed simulation that the discharge-induced residual heat rather than shock wave plays a dominant role in flow control. For any leading edge separations, the preliminary flow reattachment is realized by residual heat-induced spanwise vortices. After that, the nanosecond actuator functions by continuing exciting flow instability at poststall attack angles or acting as an active trip near stall angle. As a result, the controlled flow is characterized by a train of repetitive, downstream moving vortices over suction surface or an attached turbulent boundary layer, which depends on both angle of attack and Reynolds number. The advection of residual temperature with external flow offers a nanosecond plasma actuator a lot of flexibility to extend its influence region. Animations are provided for

Electric field with bipolar structure during magnetic reconnection without a guide field

NASA Astrophysics Data System (ADS)

Guo, Jun

2014-05-01

We present a study on the polarized electric field during the collisionless magnetic reconnection of antiparallel fields using two dimensional particle-in-cell simulations. The simulations demonstrate clearly that electron holes and electric field with bipolar structure are produced during magnetic reconnection without a guide field. The electric field with bipolar structure can be found near the X-line and on the separatrix and the plasma sheet boundary layer, which is consistent with the observations. These structures will elongate electron's time staying in the diffusion region. In addition, the electric fields with tripolar structures are also found in our simulation.

A scheme for recording a fast process at nanosecond scale by using digital holographic interferometry with continuous wave laser

NASA Astrophysics Data System (ADS)

Wang, Jun; Zhao, Jianlin; Di, Jianglei; Jiang, Biqiang

2015-04-01

A scheme for recording fast process at nanosecond scale by using digital holographic interferometry with continuous wave (CW) laser is described and demonstrated experimentally, which employs delayed-time fibers and angular multiplexing technique and can realize the variable temporal resolution at nanosecond scale and different measured depths of object field at certain temporal resolution. The actual delay-time is controlled by two delayed-time fibers with different lengths. The object field information in two different states can be simultaneously recorded in a composite hologram. This scheme is also suitable for recording fast process at picosecond scale, by using an electro-optic modulator.

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.

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.

Molecular dynamics simulations of the rotary motor F(0) under external electric fields across the membrane.

PubMed

Lin, Yang-Shan; Lin, Jung-Hsin; Chang, Chien-Cheng

2010-03-17

The membrane-bound component F(0), which is a major component of the F(0)F(1)-ATP synthase, works as a rotary motor and plays a central role in driving the F(1) component to transform chemiosmotic energy into ATP synthesis. We conducted molecular dynamics simulations of b(2)-free F(0) in a 1-palmitoyl-2-oleoyl-phosphatidylcholine lipid bilayer for tens of nanoseconds with two different protonation states of the cAsp-61 residue at the interface of the a-c complex in the absence of electric fields and under electric fields of +/-0.03 V/nm across the membrane. To our surprise, we observed that the upper half of the N-terminal helix of the c(1) subunit rotated about its axis clockwise by 30 degrees . An energetic analysis revealed that the electrostatic repulsion between this N-terminal helix and subunit c(12) was a major contributor to the observed rotation. A correlation map analysis indicated that the correlated motions of residues in the interface of the a-c complex were significantly reduced by external electric fields. The deuterium order parameter (S(CD)) profile calculated by averaging all the lipids in the F(0)-bound bilayer was not very different from that of the pure bilayer system, in agreement with recent (2)H solid-state NMR experiments. However, by delineating the lipid properties according to their vicinity to F(0), we found that the S(CD) profiles of different lipid shells were prominently different. Lipids close to F(0) formed a more ordered structure. Similarly, the lateral diffusion of lipids on the membrane surface also followed a shell-dependent behavior. The lipids in the proximity of F(0) exhibited very significantly reduced diffusional motion. The numerical value of S(CD) was anticorrelated with that of the diffusion coefficient, i.e., the more ordered lipid structures led to slower lipid diffusion. Our findings will help elucidate the dynamics of F(0) depending on the protonation state and electric field, and may also shed some light on the

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.

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

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.

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.

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.

Investigation of capillary nanosecond discharges in air at moderate pressure: comparison of experiments and 2D numerical modelling

NASA Astrophysics Data System (ADS)

Klochko, Andrei V.; Starikovskaia, Svetlana M.; Xiong, Zhongmin; Kushner, Mark J.

2014-09-01

Nanosecond electrical discharges in the form of ionization waves are of interest for rapidly ionizing and exciting complex gas mixtures to initiate chemical reactions. Operating with a small discharge tube diameter can significantly increase the specific energy deposition and so enable optimization of the initiation process. Analysis of the uniformity of energy release in small diameter capillary tubes will aid in this optimization. In this paper, results for the experimentally derived characteristics of nanosecond capillary discharges in air at moderate pressure are presented and compared with results from a two-dimensional model. The quartz capillary tube, having inner and outer diameters of 1.5 and 3.4 mm, is about 80 mm long and filled with synthetic dry air at 27 mbar. The capillary tube with two electrodes at the ends is inserted into a break of the central wire of a long coaxial cable. A metal screen around the tube is connected to the cable ground shield. The discharge is driven by a 19 kV 35 ns voltage pulse applied to the powered electrode. The experimental measurements are conducted primarily by using a calibrated capacitive probe and back current shunts. The numerical modelling focuses on the fast ionization wave (FIW) and the plasma properties in the immediate afterglow after the conductive plasma channel has been established between the two electrodes. The FIW produces a highly focused region of electric field on the tube axis that sustains the ionization wave that eventually bridges the electrode gap. Results from the model predict FIW propagation speed and current rise time that agree with the experiment.

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

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.

Electric Potential and Electric Field Imaging with Dynamic Applications & Extensions

NASA Technical Reports Server (NTRS)

Generazio, Ed

2017-01-01

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 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. Critical design elements of current linear and real-time two-dimensional (2D) measurement systems are highlighted, and the development of a three dimensional (3D) EFI system is presented. Demonstrations for structural, electronic, human, and memory applications are shown. Recent work demonstrates that phonons may be used to create and annihilate electric dipoles within structures. Phonon induced dipoles are ephemeral and their polarization, strength, and location may be quantitatively characterized by EFI providing a new subsurface Phonon-EFI imaging technology. Results from real-time imaging of combustion and ion flow, and their measurement complications, will be discussed. Extensions to environment, Space and subterranean applications will be presented, and initial results for quantitative characterizing material properties are shown. A wearable EFI system has been developed by using fundamental EFI concepts. These new EFI capabilities are demonstrated to characterize electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, manufacturing quality control, crime scene forensics, design and materials selection for advanced sensors, combustion science, on-orbit space potential, container inspection, remote characterization of electronic circuits and level of activation, dielectric morphology of

Numerical Simulation of a Nanosecond Pulse Discharge in Mach 5 Flow

DTIC Science & Technology

2013-01-01

Numerical Simulation of a Nanosecond Pulse Discharge in Mach 5 Flow Jonathan Poggie∗and Nicholas J. Bisek† Air Force Research Laboratory, Wright...was developed for nanosecond- pulse discharges , including real- istic air kinetics, electron energy transport, and compressible bulk gas flow. A reduced...shock waves originating near the sheath edge, consistent with experimental observations. I. Introduction In a nanosecond- pulse discharge , the input

Characteristics of DC electric fields at dipolarization fronts

NASA Astrophysics Data System (ADS)

Laakso, Harri; Escoubet, Philippe; Masson, Arnaud

2016-04-01

We investigate the characteristics of DC electric field at dipolarization fronts and BBF's using multi-point Cluster observations. There are plenty of important issues that are considered, such as what kind of DC electric fields exist in such events and what are their spatial scales. One can also recognize if electrons and ions perform ExB drift motions in these events. To investigate this, we take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer. The calibrated observations of the three spectrometers are used to determine the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. This investigation also helps understand how well different measurements are calibrated.

Electrical control of a confined electron spin in a silicene quantum dot

NASA Astrophysics Data System (ADS)

Szafran, Bartłomiej; Mreńca-Kolasińska, Alina; Rzeszotarski, Bartłomiej; Żebrowski, Dariusz

2018-04-01

We study spin control for an electron confined in a flake of silicene. We find that the lowest-energy conduction-band levels are split by the diagonal intrinsic spin-orbit coupling into Kramers doublets with a definite projection of the spin on the orbital magnetic moment. We study the spin control by AC electric fields using the nondiagonal Rashba component of the spin-orbit interactions with the time-dependent atomistic tight-binding approach. The Rashba interactions in AC electric fields produce Rabi spin-flip times of the order of a nanosecond. These times can be reduced to tens of picoseconds provided that the vertical electric field is tuned to an avoided crossing opened by the Rashba spin-orbit interaction. We demonstrate that the speedup of the spin transitions is possible due to the intervalley coupling induced by the armchair edge of the flake. The study is confronted with the results for circular quantum dots decoupled from the edge with well defined angular momentum and valley index.

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.

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.

Energy efficiency in nanoscale synthesis using nanosecond plasmas.

PubMed

Pai, David Z; Ken Ostrikov, Kostya; Kumar, Shailesh; Lacoste, Deanna A; Levchenko, Igor; Laux, Christophe O

2013-01-01

We report a nanoscale synthesis technique using nanosecond-duration plasma discharges. Voltage pulses 12.5 kV in amplitude and 40 ns in duration were applied repetitively at 30 kHz across molybdenum electrodes in open ambient air, generating a nanosecond spark discharge that synthesized well-defined MoO₃ nanoscale architectures (i.e. flakes, dots, walls, porous networks) upon polyamide and copper substrates. No nitrides were formed. The energy cost was as low as 75 eV per atom incorporated into a nanostructure, suggesting a dramatic reduction compared to other techniques using atmospheric pressure plasmas. These findings show that highly efficient synthesis at atmospheric pressure without catalysts or external substrate heating can be achieved in a simple fashion using nanosecond discharges.

Rates of Charged Clocks in an Electric Field.

NASA Astrophysics Data System (ADS)

Ozer, Murat

2008-04-01

The gravitational arguments leading to time dilation, redshift, and spacetime curvature are adapted to electric fields. The energy levels of two identical positively charged atoms at different potentials in a static electric field are shown to undergo blueshift. Secondly, the period of a charged simple pendulum (clock) in the electric field of a metallic sphere is shown to vary with the electric potential. The spacetime diagram for the world lines of two photons emitted and absorbed by two pendulums at different potentials at different times and the world lines of the pendulums, as in Schild's argument, is shown to be not a parallelogram in Minkowski spacetime, concluding that spacetime must be curved. A Pound-Rebka-Snider experiment in an electric field is proposed to confirm that photons undergo a frequency shift in an electric field and hence the spacetime manifold is curved. Next, Torretti's gravitational argument that spacetime around a mass distribution concentrated at a point is curved is extended to electric charge distributions to conclude that the nonuniform electric fields of such charge distributions too curve spacetime. Finally, the local equivalence of a uniform electric field times the charge to mass ratio to a uniform acceleration is shown through spacetime transformations and the electrical redshift is obtained in a uniformly accelerated frame by using this principle. These arguments lead to the conclusion that special relativistic electromagnetism is an approximation to a general relativistic multi-metric theory.

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.

ELECTRIC AND MAGNETIC FIELDS <100 KHZ IN ELECTRIC AND GASOLINE-POWERED VEHICLES.

PubMed

Tell, Richard A; Kavet, Robert

2016-12-01

Measurements were conducted to investigate electric and magnetic fields (EMFs) from 120 Hz to 10 kHz and 1.2 to 100 kHz in 9 electric or hybrid vehicles and 4 gasoline vehicles, all while being driven. The range of fields in the electric vehicles enclosed the range observed in the gasoline vehicles. Mean magnetic fields ranged from nominally 0.6 to 3.5 µT for electric/hybrids depending on the measurement band compared with nominally 0.4 to 0.6 µT for gasoline vehicles. Mean values of electric fields ranged from nominally 2 to 3 V m -1 for electric/hybrid vehicles depending on the band, compared with 0.9 to 3 V m -1 for gasoline vehicles. In all cases, the fields were well within published exposure limits for the general population. The measurements were performed with Narda model EHP-50C/EHP-50D EMF analysers that revealed the presence of spurious signals in the EHP-50C unit, which were resolved with the EHP-50D model. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

ELECTRIC-FIELD-ENHANCED FABRIC FILTRATION OF ELECTRICALLY CHARGED FLYASH

EPA Science Inventory

The paper summarizes measurements in which both external electric field (applied by electrodes at the fabric surface) and flyash electrical charge (controlled by an upstream corona precharger) are independent variables in a factorial performance experiment carried out in a labora...

CMOS image sensor with lateral electric field modulation pixels for fluorescence lifetime imaging with sub-nanosecond time response

NASA Astrophysics Data System (ADS)

Li, Zhuo; Seo, Min-Woong; Kagawa, Keiichiro; Yasutomi, Keita; Kawahito, Shoji

2016-04-01

This paper presents the design and implementation of a time-resolved CMOS image sensor with a high-speed lateral electric field modulation (LEFM) gating structure for time domain fluorescence lifetime measurement. Time-windowed signal charge can be transferred from a pinned photodiode (PPD) to a pinned storage diode (PSD) by turning on a pair of transfer gates, which are situated beside the channel. Unwanted signal charge can be drained from the PPD to the drain by turning on another pair of gates. The pixel array contains 512 (V) × 310 (H) pixels with 5.6 × 5.6 µm2 pixel size. The imager chip was fabricated using 0.11 µm CMOS image sensor process technology. The prototype sensor has a time response of 150 ps at 374 nm. The fill factor of the pixels is 5.6%. The usefulness of the prototype sensor is demonstrated for fluorescence lifetime imaging through simulation and measurement results.

Probe Measurements of Parameters of Streamers of Nanosecond Frequency Crown Discharge

NASA Astrophysics Data System (ADS)

Ponizovskiy, A. Z.; Gosteev, S. G.

2017-12-01

Investigations of the parameters of single streamers of nanosecond frequency corona discharge, creating a voluminous low-temperature plasma in extended coaxial electrode systems, are performed. Measurements of the parameters of streamers were made by an isolated probe situated on the outer grounded electrode. Streamers were generated under the action of voltage pulses with a front of 50-300 ns, duration of 100-600 ns, and amplitude up to 100 kV at the frequency of 50-1000 Hz. The pulse voltage, the total current of the corona, current per probe, and glow in the discharge gap were recorded in the experiments. It was established that, at these parameters of pulse voltage, streamers propagate at an average strength of the electric field of 4-10 kV/cm. Increasing the pulse amplitude leads to an increase in the number of streamers hitting the probe, an increase in the average charge of the head of a streamer, and, as a consequence, an increase in the total streamer current and the energy introduced into the gas. In the intervals up to 3 cm, streamer breakdown at an average field strength of 5-10 kV/cm is possible. In longer intervals, during the buildup of voltage after generation of the main pulse, RF breakdown is observed at E av ≈ 4 kV/cm.

On high-latitude convection field inhomogeneities, parallel electric fields and inverted-V precipitation events

NASA Technical Reports Server (NTRS)

Lennartsson, W.

1977-01-01

A simple model of a static electric field with a component parallel to the magnetic field is proposed for calculating the electric field and current distributions at various altitudes when the horizontal distribution of the convection electric field is given at a certain altitude above the auroral ionosphere. The model is shown to be compatible with satellite observations of inverted-V electron precipitation structures and associated irregularities in the convection electric field.

Energy efficiency in nanoscale synthesis using nanosecond plasmas

PubMed Central

Pai, David Z.; (Ken) Ostrikov, Kostya; Kumar, Shailesh; Lacoste, Deanna A.; Levchenko, Igor; Laux, Christophe O.

2013-01-01

We report a nanoscale synthesis technique using nanosecond-duration plasma discharges. Voltage pulses 12.5 kV in amplitude and 40 ns in duration were applied repetitively at 30 kHz across molybdenum electrodes in open ambient air, generating a nanosecond spark discharge that synthesized well-defined MoO3 nanoscale architectures (i.e. flakes, dots, walls, porous networks) upon polyamide and copper substrates. No nitrides were formed. The energy cost was as low as 75 eV per atom incorporated into a nanostructure, suggesting a dramatic reduction compared to other techniques using atmospheric pressure plasmas. These findings show that highly efficient synthesis at atmospheric pressure without catalysts or external substrate heating can be achieved in a simple fashion using nanosecond discharges. PMID:23386976

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

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.

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

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

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

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

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

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.

Electric-field-stimulated protein mechanics

PubMed Central

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

2017-01-01

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 (LNX2PDZ2) 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. PMID:27926732

Remote sensing of mesospheric electric fields using MF radars

NASA Astrophysics Data System (ADS)

Meek, C. E.; Manson, A. H.; Martynenko, S. I.; Rozumenko, V. T.; Tyrnov, O. F.

2004-07-01

Large mesospheric electric fields can play an essential role in middle atmospheric electrodynamics (see, e.g., Goldberg, R. A., Middle Atmospheric Electrodynamics during MAP, Adv. Space Res. 10 (10) (1990) 209). The V/m electric fields of atmospheric origin can be the possible cause of large variations in the electron collision frequency at mesospheric altitudes, and this provides a unique opportunity to take measurements of electric fields in the lower ionosphere by using remote sensing instruments employing radiowave techniques. A technique has been proposed for making estimates of large mesospheric electric field intensities on the lower edge of the ionosphere by using MF radar data and the inherent effective electron collision frequency. To do this, data collected in Canada and Ukraine were utilized. The developed technique permits the changes in mesospheric electric field intensities to be derived from MF radar data in real time. The statistical analysis of data consistent with large mesospheric electric field intensities in the 60-67km region resulted in the following inferences. There are at least two mechanisms for the generation of large mesospheric electric fields in the mesosphere. The most likely mechanism, with a probability of 60-70%, is the summation of random fields from a large number of elementary small-scale mesospheric generators, which results in a one-parameter Rayleigh distribution of the total large mesospheric electric field intensity E with a mean value of approximately 0.7-0.9V/m in the 60-67km altitude region, or in the corresponding one-parameter exponential distribution of the intensity squared E2 of large mesospheric electric fields. The second mechanism of unknown nature, with 5-15% probability, gives rise to the sporadic appearance of large mesospheric electric field intensities E>2.5V/m with a mean of 4V/m. Statistically significant seasonal differences in the averaged large mesospheric electric field parameters have not been

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.

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.

Current-Voltage Characteristic of Nanosecond - Duration Relativistic Electron Beam

NASA Astrophysics Data System (ADS)

Andreev, Andrey

2005-10-01

The pulsed electron-beam accelerator SINUS-6 was used to measure current-voltage characteristic of nanosecond-duration thin annular relativistic electron beam accelerated in vacuum along axis of a smooth uniform metal tube immersed into strong axial magnetic field. Results of these measurements as well as results of computer simulations performed using 3D MAGIC code show that the electron-beam current dependence on the accelerating voltage at the front of the nanosecond-duration pulse is different from the analogical dependence at the flat part of the pulse. In the steady-state (flat) part of the pulse), the measured electron-beam current is close to Fedosov current [1], which is governed by the conservation law of an electron moment flow for any constant voltage. In the non steady-state part (front) of the pulse, the electron-beam current is higher that the appropriate, for a giving voltage, steady-state (Fedosov) current. [1] A. I. Fedosov, E. A. Litvinov, S. Ya. Belomytsev, and S. P. Bugaev, ``Characteristics of electron beam formed in diodes with magnetic insulation,'' Soviet Physics Journal (A translation of Izvestiya VUZ. Fizika), vol. 20, no. 10, October 1977 (April 20, 1978), pp.1367-1368.

AC field exposure study: human exposure to 60-Hz electric fields

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

Silva, J.M.

1985-04-01

The objective of this study was to develop a method of estimating human exposure to the 60 Hz electric fields created by transmission lines. The Activity Systems Model simulates human activities in a variety of situations where exposure to electric fields is possible. The model combines maps of electric fields, activity maps, and experimentally determined activity factors to provide histograms of time spent in electric fields of various strengths in the course of agricultural, recreational, and domestic activities. For corroboration, the study team measured actual human exposure at locations across the United States near transmission lines ranging in voltage frommore » 115 to 1200 kV. The data were collected with a specially designed vest that measures exposure. These data demonstrate the accuracy of the exposure model presented in this report and revealed that most exposure time is spent in fields of magnitudes similar to many household situations. The report provides annual exposure estimates for human activities near transmission lines and in the home and compares them with exposure data from typical laboratory animal experiments. For one exposure index, the cumulative product of time and electric field, exposure during some of the laboratory animal experiments is two to four orders of magnitude greater than cumulative exposure for a human during one year of outdoor work on a farm crossed by a transmission line.« less

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.

Near-membrane electric field calcium ion dehydration.

PubMed

Barger, James P; Dillon, Patrick F

2016-12-01

The dehydration of ion-water complexes prior to ion channel transit has focused on channel protein-mediated dissociation of water. Ion dehydration by the membrane electric field has not previously been considered. Near membrane electric fields have previously been shown to cause the disassociation of non-covalently bound small molecule-small molecule, small molecule-protein, and protein-protein complexes. It is well known that cosmotropic, structure making ions such as calcium and sodium significantly bind multiple water ions in solution. It is also known that these ions are often not hydrated as they pass through membrane ion channels. Using capillary electrophoresis, the range of electric fields needed to strip water molecules from calcium ions has been measured. Ion migration velocity is a linear function of the electric field. At low electric fields, the migration rate of calcium ion was shown to be linearly related to the applied electric field. Using a form of the Stoke's equation applicable to ion migration, the hydrated calcium radius was found to be 0.334nm, corresponding to a water hydration shell of 5.09 water molecules. At higher electric fields, the slope of the calcium migration velocity as a function of the electric field increased, which was modeled as a decrease in the radius of the migrating ion as the water was removed. Using a tanh function to model the transition of the ion from a hydrated to a stripped state, the transition had a midpoint at 446V/cm, and was 88% complete at 587V/cm with a correlation coefficient of 0.9996. The migration velocity of the stripped calcium ion was found to be a function of both the decrease in radius and an increase in the effective, electronic viscosity of the dipole medium through which the dehydrated ion moved. The size of the electric field needed to dehydrate calcium occurs 6-7nm from the cell membrane. Calcium ions within this distance from the membrane will be devoid of water molecules when they reach the

Penetration electric fields: A Volland Stern approach

NASA Astrophysics Data System (ADS)

Burke, William J.

2007-07-01

This paper reformulates the Volland Stern model, separating contributions from corotation and convection to predict electric field penetration of the inner magnetosphere using data from the Advanced Composition Explorer (ACE) satellite. In the absence of shielding, the model electric field is EVS=ΦPC/2LYRE, where ΦPC is the polar cap potential and 2LYRE is the width of the magnetosphere along the dawn dusk meridian. ΦPC is estimated from the interplanetary electric field (IEF) and the dynamic pressure of the solar wind (PSW); values of LY were approximated using PSW and simple force-balance considerations. ACE measurements on 16 17 April 2002 were then used to calculate EVS for comparison with the eastward electric field component (EJφ) detected by the incoherent scatter radar at Jicamarca, Peru. While the interplanetary magnetic field (IMF) was southward, the model predicted observed ratios of EVS/IEF. During intervals of northward IMF, EJφ turned westward suggesting that a northward IMF BZ system of field-aligned currents affected the electrodynamics of the dayside ionosphere on rapid time scales.

Manipulation of positron orbits in a dipole magnetic field with fluctuating electric fields

NASA Astrophysics Data System (ADS)

Saitoh, H.; Horn-Stanja, J.; Nißl, S.; Stenson, E. V.; Hergenhahn, U.; Pedersen, T. Sunn; Singer, M.; Dickmann, M.; Hugenschmidt, C.; Stoneking, M. R.; Danielson, J. R.; Surko, C. M.

2018-01-01

We report the manipulation of positron orbits in a toroidal dipole magnetic field configuration realized with electric fields generated by segmented electrodes. When the toroidal circulation motion of positrons in the dipole field is coupled with time-varying electric fields generated by azimuthally segmented outer electrodes, positrons undergo oscillations of their radial positions. This enables quick manipulation of the spatial profiles of positrons in a dipole field trap by choosing appropriate frequency, amplitude, phase, and gating time of the electric fields. According to numerical orbit analysis, we applied these electric fields to positrons injected from the NEPOMUC slow positron facility into a prototype dipole field trap experiment with a permanent magnet. Measurements with annihilation γ-rays clearly demonstrated the efficient compression effects of positrons into the strong magnetic field region of the dipole field configuration. This positron manipulation technique can be used as one of essential tools for future experiments on the formation of electron-positron plasmas.

High electric field conduction in low-alkali boroaluminosilicate glass

NASA Astrophysics Data System (ADS)

Dash, Priyanka; Yuan, Mengxue; Gao, Jun; Furman, Eugene; Lanagan, Michael T.

2018-02-01

Electrical conduction in silica-based glasses under a low electric field is dominated by high mobility ions such as sodium, and there is a transition from ionic transport to electronic transport as the electric field exceeds 108 V/m at low temperatures. Electrical conduction under a high electric field was investigated in thin low-alkali boroaluminosilicate glass samples, showing nonlinear conduction with the current density scaling approximately with E1/2, where E is the electric field. In addition, thermally stimulated depolarization current (TSDC) characterization was carried out on room-temperature electrically poled glass samples, and an anomalous discharging current flowing in the same direction as the charging current was observed. High electric field conduction and TSDC results led to the conclusion that Poole-Frenkel based electronic transport occurs in the mobile-cation-depleted region adjacent to the anode, and accounts for the observed anomalous current.

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.

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.

Optimized LWIR enhancement of nanosecond and femtosecond LIBS uranium emission

NASA Astrophysics Data System (ADS)

Akpovo, Codjo A.; Ford, Alan; Johnson, Lewis

2016-05-01

A carbon dioxide (CO2) transverse electrical breakdown in atmosphere (TEA), pulsed laser was used to enhance the laser-induced breakdown spectroscopy (LIBS) spectral signatures of uranium under nanosecond (ns) and femtosecond (fs) ablation. The peak areas of both ionic and neutral species increased by one order of magnitude for ns-ablation and two orders of magnitude for fs-ablation over LIBS when the CO2 TEA laser was used with samples of dried solutions of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) on silicon wafers. Electron temperature and density measurements show that the spectral emission improvement from using the TEA laser comes from plasma reheating.

Relationship of the interplanetary electric field to the high-latitude ionospheric electric field and currents Observations and model simulation

NASA Technical Reports Server (NTRS)

Clauer, C. R.; Banks, P. M.

1986-01-01

The electrical coupling between the solar wind, magnetosphere, and ionosphere is studied. The coupling is analyzed using observations of high-latitude ion convection measured by the Sondre Stromfjord radar in Greenland and a computer simulation. The computer simulation calculates the ionospheric electric potential distribution for a given configuration of field-aligned currents and conductivity distribution. The technique for measuring F-region in velocities at high time resolution over a large range of latitudes is described. Variations in the currents on ionospheric plasma convection are examined using a model of field-aligned currents linking the solar wind with the dayside, high-latitude ionosphere. The data reveal that high-latitude ionospheric convection patterns, electric fields, and field-aligned currents are dependent on IMF orientation; it is observed that the electric field, which drives the F-region plasma curve, responds within about 14 minutes to IMF variations in the magnetopause. Comparisons of the simulated plasma convection with the ion velocity measurements reveal good correlation between the data.

A corotation electric field model of the Earth derived from Swarm satellite magnetic field measurements

NASA Astrophysics Data System (ADS)

Maus, Stefan

2017-08-01

Rotation of the Earth in its own geomagnetic field sets up a primary corotation electric field, compensated by a secondary electric field of induced electrical charges. For the geomagnetic field measured by the Swarm constellation of satellites, a derivation of the global corotation electric field inside and outside of the corotation region is provided here, in both inertial and corotating reference frames. The Earth is assumed an electrical conductor, the lower atmosphere an insulator, followed by the corotating ionospheric E region again as a conductor. Outside of the Earth's core, the induced charge is immediately accessible from the spherical harmonic Gauss coefficients of the geomagnetic field. The charge density is positive at high northern and southern latitudes, negative at midlatitudes, and increases strongly toward the Earth's center. Small vertical electric fields of about 0.3 mV/m in the insulating atmospheric gap are caused by the corotation charges located in the ionosphere above and the Earth below. The corotation charges also flow outward into the region of closed magnetic field lines, forcing the plasmasphere to corotate. The electric field of the corotation charges further extends outside of the corotating regions, contributing radial outward electric fields of about 10 mV/m in the northern and southern polar caps. Depending on how the magnetosphere responds to these fields, the Earth may carry a net electric charge.

Beyond 2D: Parallel Electric Fields and Dissipation in Guide Field Reconnectio

NASA Astrophysics Data System (ADS)

Wilder, F. D.; Ergun, R.; Ahmadi, N.; Goodrich, K.; Eriksson, S.; Shimoda, E.; Burch, J. L.; Phan, T.; Torbert, R. B.; Strangeway, R. J.; Giles, B. L.; Lindqvist, P. A.; Khotyaintsev, Y. V.

2017-12-01

In 2015, NASA launched the Magnetospheric Multiscale (MMS) mission to study phenomenon of magnetic reconnection down to the electron scale. Advantages of MMS include a 20s spin period and long axial booms, which together allow for measurement of 3-D electric fields with accuracy down to 1 mV/m. During the two dayside phases of the prime mission, MMS has observed multiple electron and ion diffusion region events at the Earth's subsolar and flank magnetopause, as well as in the magnetosheath, providing an option to study both symmetric and asymmetric reconnection at a variety of guide field strengths. We present a review of parallel electric fields observed by MMS during diffusion region events, and discuss their implications for simulations and laboratory observations of reconnection. We find that as the guide field increases, the dissipation in the diffusion region transitions from being due to currents and fields perpendicular to the background magnetic field, to being associated with parallel electric fields and currents. Additionally, the observed parallel electric fields are significantly larger than those predicted by simulations of reconnection under strong guide field conditions.

Cloaking magnetic field and generating electric field with topological insulator and superconductor bi-layer sphere

NASA Astrophysics Data System (ADS)

Xu, Jin

2017-12-01

When an electric field is applied on a topological insulator, not only the electric field is generated, but also the magnetic field is generated, vice versa. I designed topological insulator and superconductor bi-layer magnetic cloak, derived the electric field and magnetic field inside and outside the topological insulator and superconductor sphere. Simulation and calculation results show that the applied magnetic field is screened by the topological insulator and superconductor bi-layer, and the electric field is generated in the cloaked region.

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).

Dynamics of vesicles in electric fields

NASA Astrophysics Data System (ADS)

Vlahovska, Petia; Gracia, Ruben

2007-11-01

Electromechanical forces are widely used for cell manipulation. Knowledge of the physical mechanisms underlying the interaction of cells and external fields is essential for practical applications. Vesicles are model cells made of a lipid bilayer membrane. They are examples of ``soft'' particles, i.e., their shape when subjected to flow or electric field is not given a priori but it is governed by the balance of membrane, fluid and electrical stresses. This generic ``softness'' gives rise to a very complex vesicle dynamics in external fields. In an AC electric field, as the frequency is increased, vesicles filled with a fluid less conducting than the surrounding fluid undergo shape transition from prolate to oblate ellipsoids. The opposite effect is observed with drops. We present an electro- hydrodynamic theory based on the leaky dielectric model that quantitatively describes experimental observations. We compare drops and vesicles, and show how their distinct behavior stems from different interfacial properties.

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.

Electroinduction disk sensor of electric field strength

NASA Astrophysics Data System (ADS)

Biryukov, S. V.; Korolyova, M. A.

2018-01-01

Measurement of the level of electric fields exposure to the technical and biological objects for a long time is an urgent task. To solve this problem, the required electric field sensors with specified metrological characteristics. The aim of the study is the establishment of theoretical assumptions for the calculation of the flat electric field sensors. It is proved that the accuracy of the sensor does not exceed 3% in the spatial range 0fields, this article examines single-axis electromotive disk sensor radius R, and the estimation errors caused by the inhomogeneity of the field. The maximum of this error is 3% in the spatial range from 0 to 5R to the source field that allows you to design better quality sensors used in different measuring systems of wide application.

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.

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

Quantitative Imaging of Microwave Electric Fields through Near-Field Scanning Microwave Microscopy

NASA Astrophysics Data System (ADS)

Dutta, S. K.; Vlahacos, C. P.; Steinhauer, D. E.; Thanawalla, A.; Feenstra, B. J.; Wellstood, F. C.; Anlage, Steven M.; Newman, H. S.

1998-03-01

The ability to non-destructively image electric field patterns generated by operating microwave devices (e.g. filters, antennas, circulators, etc.) would greatly aid in the design and testing of these structures. Such detailed information can be used to reconcile discrepancies between simulated behavior and experimental data (such as scattering parameters). The near-field scanning microwave microscope we present uses a coaxial probe to provide a simple, broadband method of imaging electric fields.(S. M. Anlage, et al.) IEEE Trans. Appl. Supercond. 7, 3686 (1997).^,(See http://www.csr.umd.edu/research/hifreq/micr_microscopy.html) The signal that is measured is related to the incident electric flux normal to the face of the center conductor of the probe, allowing different components of the field to be measured by orienting the probe appropriately. By using a simple model of the system, we can also convert raw data to absolute electric field. Detailed images of standing waves on copper microstrip will be shown and compared to theory.

Field-aligned currents and large-scale magnetospheric electric fields

NASA Technical Reports Server (NTRS)

Dangelo, N.

1979-01-01

The existence of field-aligned currents (FAC) at northern and southern high latitudes was confirmed by a number of observations, most clearly by experiments on the TRIAD and ISIS 2 satellites. The high-latitude FAC system is used to relate what is presently known about the large-scale pattern of high-latitude ionospheric electric fields and their relation to solar wind parameters. Recently a simplified model was presented for polar cap electric fields. The model is of considerable help in visualizing the large-scale features of FAC systems. A summary of the FAC observations is given. The simplified model is used to visualize how the FAC systems are driven by their generators.

Deflagration-to-Detonation Transition Control by Nanosecond Gas Discharges

DTIC Science & Technology

2008-04-07

Report 3. DATES COVERED (From – To) 1 April 2007 - 18 August 09 4. TITLE AND SUBTITLE Deflagration-To- Detonation Transition Control By Nanosecond...SUPPLEMENTARY NOTES 14. ABSTRACT During the current project, an extensive experimental study of detonation initiation by high{voltage...nanosecond gas discharges has been performed in a smooth detonation tube with different discharge chambers and various discharge cell numbers. The chambers

Compact nanosecond laser system for the ignition of aeronautic combustion engines

NASA Astrophysics Data System (ADS)

Amiard-Hudebine, G.; Tison, G.; Freysz, E.

2016-12-01

We have studied and developed a compact nanosecond laser system dedicated to the ignition of aeronautic combustion engines. This system is based on a nanosecond microchip laser delivering 6 μJ nanosecond pulses, which are amplified in two successive stages. The first stage is based on an Ytterbium doped fiber amplifier (YDFA) working in a quasi-continuous-wave (QCW) regime. Pumped at 1 kHz repetition rate, it delivers TEM00 and linearly polarized nanosecond pulses centered at 1064 nm with energies up to 350 μJ. These results are in very good agreement with the model we specially designed for a pulsed QCW pump regime. The second amplification stage is based on a compact Nd:YAG double-pass amplifier pumped by a 400 W peak power QCW diode centered at λ = 808 nm and coupled to a 800 μm core multimode fiber. At 10 Hz repetition rate, this system amplifies the pulse delivered by the YDFA up to 11 mJ while preserving its beam profile, polarization ratio, and pulse duration. Finally, we demonstrate that this compact nanosecond system can ignite an experimental combustion chamber.

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.

Horizontal electric fields from lightning return strokes

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

Thomson, E.M.; Uman, M.A.; Johnson, J.

1985-01-01

Measurements are presented of simultaneous horizontal and vertical electric fields from both close and distant lightning return strokes. The data were obtained during summer 1984 at the Kennedy Space Center, Florida, using an electrically isolated spherical antenna having a system bandwidth of 3 Hz to 5 MHz. Lightning signals were obtained from flashes at distances from a few to 100 kilometers. Since the horizontal electric field is in part determined by the local ground conductivity, that parameter was measured as a function of depth. The horizontal fields from lightning return strokes had typically 1/50 the peak amplitude of the verticalmore » fields and waveshapes which were consistant with available theory, as expressed by the ''wavetilt'' formula.« less

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

Inhibition of brain tumor cell proliferation by alternating electric fields

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

Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr

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.

Electron transport in reduced graphene oxides in high electric field

NASA Astrophysics Data System (ADS)

Jian, Wen-Bin; Lai, Jian-Jhong; Wang, Sheng-Tsung; Tsao, Rui-Wen; Su, Min-Chia; Tsai, Wei-Yu; Rosenstein, Baruch; Zhou, Xufeng; Liu, Zhaoping

Due to a honeycomb structure, charge carriers in graphene exhibit quasiparticles of linear energy-momentum dispersion and phenomena of Schwinger pair creation may be explored. Because graphene is easily broken in high electric fields, single-layer reduced graphene oxides (rGO) are used instead. The rGO shows a small band gap while it reveals a graphene like behavior in high electric fields. Electron transport in rGO exhibits two-dimensional Mott's variable range hopping. The temperature behavior of resistance in low electric fields and the electric field behavior of resistance at low temperatures are all well explained by the Mott model. At temperatures higher than 200 K, the electric field behavior does not agree with the model while it shows a power law behavior with an exponent of 3/2, being in agreement with the Schwinger model. Comparing with graphene, the rGO is more sustainable to high electric field thus presenting a complete high-electric field behavior. When the rGO is gated away from the charge neutral point, the turn-on electric field of Schwinger phenomena is increased. A summary figure is given to present electric field behaviors and power law variations of resistances of single-layer rGO, graphene, and MoS2.

Optical Remote Sensing of Electric Fields Above Thunderstorms

NASA Astrophysics Data System (ADS)

Burns, B. M.; Carlson, B. E.; Lauben, D.; Cohen, M.; Smith, D.; Inan, U. S.

2010-12-01

Measurement of thunderstorm electric fields typically require balloon-borne measurements in the region of interest. Such measurements are cumbersome and provide limited information at a single point. Remote sensing of electric fields by Kerr-effect induced optical polarization changes of background skylight circumvents many of these difficulties and can in principle provide a high-speed movie of electric field behavior. Above-thundercloud 100 kV/m quasi-static electric fields are predicted to produce polarization changes at above the part in one million level that should be detectable at a ground instrument featuring 1 cm2sr geometric factor and 1 kHz bandwidth (though more sensitivity is nonetheless desired). Currently available optical and electronic components may meet these requirements. We review the principles of this measurement and discuss the current status of a field-ready prototype instrument currently in construction.

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.

Colloidal particle electrorotation in a nonuniform electric field

NASA Astrophysics Data System (ADS)

Hu, Yi; Vlahovska, Petia M.; Miksis, Michael J.

2018-01-01

A model to study the dynamics of colloidal particles in nonuniform electric fields is proposed. For an isolated sphere, the conditions and threshold for sustained (Quincke) rotation in a linear direct current (dc) field are determined. Particle dynamics becomes more complex with increasing electric field strength, changing from steady spinning around the particle center to time-dependent orbiting motion around the minimum field location. Pairs of particles exhibit intricate trajectories, which are a combination of translation, due to dielectrophoresis, and rotation, due to the Quincke effect. Our model provides a basis to study the collective dynamics of many particles in a general electric field.

Colloidal particle electrorotation in a nonuniform electric field.

PubMed

Hu, Yi; Vlahovska, Petia M; Miksis, Michael J

2018-01-01

A model to study the dynamics of colloidal particles in nonuniform electric fields is proposed. For an isolated sphere, the conditions and threshold for sustained (Quincke) rotation in a linear direct current (dc) field are determined. Particle dynamics becomes more complex with increasing electric field strength, changing from steady spinning around the particle center to time-dependent orbiting motion around the minimum field location. Pairs of particles exhibit intricate trajectories, which are a combination of translation, due to dielectrophoresis, and rotation, due to the Quincke effect. Our model provides a basis to study the collective dynamics of many particles in a general electric field.

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.

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.

On the electric field model for an open magnetosphere

NASA Technical Reports Server (NTRS)

Wang, Zhi; Ashour-Abdalla, Maha; Walker, Raymond J.

1993-01-01

We have developed a new canonical separator line type magnetospheric magnetic field and electric field model for use in magnetospheric calculations, we determine the magnetic and electric field by controlling the reconnection rate at the subsolar magnetopause. The model is applicable only for purely southward interplanetary magnetic field (IMF). We have obtained a more realistic magnetotail configuration by applying a stretch transformation to an axially symmetric field solution. We also discuss the Stern singularity in which there is an electric field singlarity in the canonical separate line models for B(sub y) not = to 0 by using a new technique that solves for the electric field along a field line directly instead of determining it by a potential mapping. The singularity not only causes an infinite electric field on the polar cap, but also causes the boundary conditions at plus infinity and minus infinity in the solar wind to contradict each other. This means that the canonical separator line models do not represent the open magnetosphere well, except for the case of purely southward IMF.

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...

Linear electric field time-of-flight ion mass spectrometer

DOEpatents

Funsten, Herbert O [Los Alamos, NM; Feldman, William C [Los Alamos, NM

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.

Field distribution and DNA transport in solid tumors during electric field-mediated gene delivery.

PubMed

Henshaw, Joshua W; Yuan, Fan

2008-02-01

Gene therapy has a great potential in cancer treatment. However, the efficacy of cancer gene therapy is currently limited by the lack of a safe and efficient means to deliver therapeutic genes into the nucleus of tumor cells. One method under investigation for improving local gene delivery is based on the use of pulsed electric field. Despite repeated demonstration of its effectiveness in vivo, the underlying mechanisms behind electric field-mediated gene delivery remain largely unknown. Without a thorough understanding of these mechanisms, it will be difficult to further advance the gene delivery. In this review, the electric field-mediated gene delivery in solid tumors will be examined by following individual transport processes that must occur in vivo for a successful gene transfer. The topics of examination include: (i) major barriers for gene delivery in the body, (ii) distribution of electric fields at both cell and tissue levels during the application of external fields, and (iii) electric field-induced transport of genes across each of the barriers. Through this approach, the review summarizes what is known about the mechanisms behind electric field-mediated gene delivery and what require further investigations in future studies.

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.

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.

Temporal and spatial evolution of nanosecond microwave-driven plasma

NASA Astrophysics Data System (ADS)

Chang, C.; Chen, X. Q.; Zhu, M.; Pu, Y. K.

2018-06-01

In this paper, a method for simultaneously acquiring the temporal and spatial evolution of characteristic plasma spectra in a single microwave pulse is proposed and studied. By using multi-sub-beam fiber bundles coupled with a spectrometer and EMICCD (Electron-multiplying intensified charge-coupled device), the spatial distribution and time evolution of characteristic spectra of desorbed gases at the dielectric/vacuum interface during nanosecond microwave-driven plasma discharge are observed. Arrays of small align tubes punctured with metal walls of feed horn are filled with separate fibers of matched sizes and equal lengths. The output ends of fibers arranged in a single longitudinal column are connected to the entrance slit of a spectrometer, where the optical spectrum inputs to a high-speed EMICCD, to detect the rapid-varying time and space spectra of nanosecond giga-watt microwave discharges. The evolution of spectral clusters of N2 (C-B), N2+ (B-X), and the hydrogen atoms is discovered and monitored. The whole duration of light emission is much longer than the microwave pulse, and the intensities of ion N2+ (B-X) spectra increase after microwave pulses with rise times of 25-50 ns. The brightness distribution of plasma spectra in different space is observed and approximately consistent with the simulated E-field distribution.

Lunar Electric Fields: Observations and Implications

NASA Astrophysics Data System (ADS)

Halekas, J. S.; Delory, G. T.; Stubbs, T. J.; Farrell, W. M.; Vondrak, R. R.

2006-12-01

Alhough the Moon is typically thought of as having a relatively dormant environment, it is in fact very electrically active. The lunar surface, not protected by any substantial atmosphere, is directly exposed to solar UV and X-rays as well as solar wind plasma and energetic particles. This creates a complex electrodynamic environment, with the surface typically charging positive in sunlight and negative in shadow, and surface potentials varying over orders of magnitude in response to changing solar illumination and plasma conditions. Observations from the Apollo era and theoretical considerations strongly suggest that surface charging also drives dust electrification and horizontal and vertical dust transport. We present a survey of the lunar electric field environment, utilizing both newly interpreted Lunar Prospector (LP) orbital observations and older Apollo surface observations, and comparing to theoretical predictions. We focus in particular on time periods when the most significant surface charging was observed by LP - namely plasmasheet crossings (when the Moon is in the Earth's magnetosphere) and space weather events. During these time periods, kV-scale potentials are observed, and enhanced surface electric fields can be expected to drive significant horizontal and vertical dust transport. Both dust and electric fields can have serious effects on habitability and operation of machinery, so understanding the coupled dust-plasma-electric field system around the Moon is critically important for planning exploration efforts, in situ resource utilization, and scientific observations on the lunar surface. Furthermore, from a pure science perspective, this represents an excellent opportunity to study fundamental surface-plasma interactions.

Assessing human exposure to power-frequency electric and magnetic fields.

PubMed Central

Kaune, W T

1993-01-01

This paper reviews published literature and current problems relating to the assessment of occupational and residential human exposures to power-frequency electric and magnetic fields. Available occupational exposure data suggest that the class of job titles known as electrical workers may be an effective surrogate for time-weighted-average (TWA) magnetic-field (but not electric-field) exposure. Current research in occupational-exposure assessment is directed to the construction of job-exposure matrices based on electric- and magnetic-field measurements and estimates of worker exposures to chemicals and other factors of interest. Recent work has identified five principal sources of residential magnetic fields: electric power transmission lines, electric power distribution lines, ground currents, home wiring, and home appliances. Existing residential-exposure assessments have used one or more of the following techniques: questionnaires, wiring configuration coding, theoretical field calculations, spot electric- and magnetic-field measurements, fixed-site magnetic-field recordings, personal- exposure measurements, and geomagnetic-field measurements. Available normal-power magnetic-field data for residences differ substantially between studies. It is not known if these differences are due to geographical differences, differences in measurement protocols, or instrumentation differences. Wiring codes and measured magnetic fields (but not electric fields) are associated weakly. Available data suggest, but are far from proving, that spot measurements may be more effective than wire codes as predictors of long-term historical magnetic-field exposure. Two studies find that away-from-home TWA magnetic-field exposures are less variable than at-home exposures. The importance of home appliances as contributors to total residential magnetic-field exposure is not known at this time. It also is not known what characteristics (if any) of residential electric and magnetic fields are

Enhanced Monitoring of Nanosecond Electric Pulse-Evoked Membrane Conductance Changes in Whole-Cell Patch Clamp Experiments.

PubMed

Yoon, Jihwan; Leblanc, Normand; Zaklit, Josette; Vernier, P Thomas; Chatterjee, Indira; Craviso, Gale L

2016-10-01

Patch clamp electrophysiology serves as a powerful method for studying changes in plasma membrane ion conductance induced by externally applied high-intensity nanosecond electric pulses (NEPs). This paper describes an enhanced monitoring technique that minimizes the length of time between pulse exposure and data recording in a patch-clamped excitable cell. Whole-cell membrane currents were continuously recorded up to 11 ms before and resumed 8 ms after delivery of a 5-ns, 6 MV/m pulse by a pair of tungsten rod electrodes to a patched adrenal chromaffin cell maintained at a holding potential of -70 mV. This timing was achieved by two sets of relay switches. One set was used to disconnect the patch pipette electrode from the pre-amplifier and connect it to a battery to maintain membrane potential at -70 mV, and also to disconnect the reference electrode from the amplifier. The other set was used to disconnect the electrodes from the pulse generator until the time of NEP/sham exposure. The sequence and timing of both sets of relays were computer-controlled. Using this procedure, we observed that a 5-ns pulse induced an instantaneous inward current that decayed exponentially over the course of several minutes, that a second pulse induced a similar response, and that the current was carried, at least in part, by Na + . This approach for characterizing ion conductance changes in an excitable cell in response to NEPs will yield information essential for assessing the potential use of NEP stimulation for therapeutic applications.

Electric Field Simulation of Surge Capacitors with Typical Defects

NASA Astrophysics Data System (ADS)

Zhang, Chenmeng; Mao, Yuxiang; Xie, Shijun; Zhang, Yu

2018-03-01

The electric field of power capacitors with different typical defects in DC working condition and impulse oscillation working condition is studied in this paper. According to the type and location of defects and considering the influence of space charge, two-dimensional models of surge capacitors with different typical defects are simulated based on ANSYS. The distribution of the electric field inside the capacitor is analyzed, and the concentration of electric field and its influence on the insulation performance are obtained. The results show that the type of defects, the location of defects and the space charge all affect the electric field distribution inside the capacitor in varying degrees. Especially the electric field distortion in the local area such as sharp corners and burrs is relatively larger, which increases the probability of partial discharge inside the surge capacitor.

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.

Nanosecond step-scan FT-infrared absorption spectroscopy in photochemistry and catalysis

NASA Astrophysics Data System (ADS)

Frei, H.

1998-06-01

Time-resolved step-scan FT-IR absorption spectroscopy has been expanded to a resolution of 20 nanosecond. Following a description of the experimental set-up, applications in four research areas are presented. In the first project, we discuss a reversible isomerization, namely the bacteriorhodopsin photocycle. Main results are the discovery of 2 processes with distinct kinetics on the nanosecond time scale not detected by previous spectroscopic techniques, and observation of an instantaneous response of the protein environment to chromophore dynamics within the nanosecond laser pulse duration. In a second project, alkane C-H bond activation by a transition metal complex in room temperature solution is investigated and the first measurement of the formation of a C-H insertion product reported (alkyl hydride). Then, a nanosecond study of a pericyclic reaction, the ring-opening of cyclohexadiene, is discussed. The fourth example describes the first observation of a transient molecule in a zeolite matrix, a triplet excited quinone, by time-resolved infrared spectroscopy.

Electric Field Detection in Sawfish and Shovelnose Rays

PubMed Central

Wueringer, Barbara E.; Jnr, Lyle Squire; Kajiura, Stephen M.; Tibbetts, Ian R.; Hart, Nathan S.; Collin, Shaun P.

2012-01-01

In the aquatic environment, living organisms emit weak dipole electric fields, which spread in the surrounding water. Elasmobranchs detect these dipole electric fields with their highly sensitive electroreceptors, the ampullae of Lorenzini. Freshwater sawfish, Pristis microdon, and two species of shovelnose rays, Glaucostegus typus and Aptychotrema rostrata were tested for their reactions towards weak artificial electric dipole fields. The comparison of sawfishes and shovelnose rays sheds light on the evolution and function of the elongated rostrum (‘saw’) of sawfish, as both groups evolved from a shovelnose ray-like ancestor. Electric stimuli were presented both on the substrate (to mimic benthic prey) and suspended in the water column (to mimic free-swimming prey). Analysis of around 480 behavioural sequences shows that all three species are highly sensitive towards weak electric dipole fields, and initiate behavioural responses at median field strengths between 5.15 and 79.6 nVcm−1. The response behaviours used by sawfish and shovelnose rays depended on the location of the dipoles. The elongation of the sawfish’s rostrum clearly expanded their electroreceptive search area into the water column and enables them to target free-swimming prey. PMID:22848543

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

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.

Vector optical fields with polarization distributions similar to electric and magnetic field lines.

PubMed

Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

2013-07-01

We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.

Dynamics analysis of extraction of manganese intensified by electric field

NASA Astrophysics Data System (ADS)

Ma, Wenrui; Tao, Changyuan; Li, Huizhan; Liu, Zuohua; Liu, Renlong

2018-06-01

In this study, a process reinforcement technology for leaching process of pyrolusite was developed. The electric field was introduced to decrease reaction temperature and improve the leaching rate of pyrolusite. The mechanisms of electric field intensifying leaching process of pyrolusite were investigated through X-ray diffraction (XRD), and Brunauer Emmett Teller (BET) in detail. The results showed that the electric field could decrease obviously the apparent activation energy of leaching process of pyrolusite. The apparent activation energy of the leaching of pyrolusite intensified by electric field was calculated to be 53.76 kJ.mol-1. In addition, the leaching efficiency of manganese was effectively increased by 10% to 20% than that without electric field under the same conditions. This was because that the electron conduit between Fe (II)/Fe (III) and pyrite was dredged effectively by electric field.

Electric-field driven jetting from dielectric liquids

NASA Astrophysics Data System (ADS)

Jayasinghe, S. N.; Edirisinghe, M. J.

2004-11-01

Three dielectric (electrical conductivity ˜10-13Sm-1) Newtonian liquids with viscosity in the range 1-100 mPa s were passed through a needle at a controlled flow rate under the influence of an electric field. At an electric field strength of 1.5kV/mm, the liquid exiting the needle instantaneously transformed from dripping droplets to an elliptically pendent droplet from the apex of which a fine jet evolved. Thus, a jet can be obtained on demand, and in this letter we define this phenomenon and explain a basis for it.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

DC Electric Fields at the Magnetopause

NASA Astrophysics Data System (ADS)

Laakso, H. E.; Escoubet, C. P.; Masson, A.

2014-12-01

In order to understand the transfer of energy, momentum and mass through the magnetopause one needs to know several plasma and field parameters including the DC electric field which is known to be challenging to measure in tenuous plasma regions, e.g. in the inner side of the magnetopause where the density drops below 1/cc. However, each of the Cluster spacecraft carries five different experiments that can provide information about DC electric fields, i.e. double probe antenna (EFW) and electron drift meter (EDI) as well as electron and ion spectrometers (PEACE, CIS-HIA, CIS-CODIF). Each technique is very different and has its own strengths and limitations. Therefore it is important to compare all available measurements before making a judgement on DC electric field variation at the magnetopause; note that only very rarely all five measurements are available at the same time. Although the full-resolution observations in the Cluster archive are calibrated, they can still contain various errors. However, when two experiments show the same field, it is quite likely that this is the right field because the different measurements are based on so complimentary techniques and the field varies so much when the spacecraft moves from the magnetosheath through the magnetopause into the magnetosphere, or vice versa. In this presentation we present several cases of the magnetopause crossings and how the different measurements agree and disagree around the magnetopause region.

Electric Field Measurements During the Genesis and Rapid Intensification Processes (GRIP) Field Program

NASA Technical Reports Server (NTRS)

Bateman, Monte G.; Blakeslee, Richard J.; Mach, Douglas M.

2010-01-01

During the Genesis and Rapid Intensification Processes (GRIP) field program, a system of 6 electric field mills was flown on one of NASA's Global Hawk aircraft. We placed several mills on the aircraft to enable us to measure the vector electric field. We created a distributed, ethernet-connected system so that each sensor has its own embedded Linux system, complete with web server. This makes our current generation system fully "sensor web enabled." The Global Hawk has several unique qualities, but relevant to quality storm electric field measurements are high altitude (20 km) and long duration (20-30 hours) flights. There are several aircraft participating in the GRIP program, and coordinated measurements are happening. Lightning and electric field measurements will be used to study the relationships between lightning and other storm characteristics. It has been long understood that lightning can be used as a marker for strong convective activity. Past research and field programs suggest that lightning flash rate may serve as an indicator and precursor for rapid intensification change in tropical cyclones and hurricanes. We have the opportunity to sample hurricanes for many hours at a time and observe intensification (or de-intensification) periods. The electrical properties of hurricanes during such periods are not well known. American

Molecules with an induced dipole moment in a stochastic electric field.

PubMed

Band, Y B; Ben-Shimol, Y

2013-10-01

The mean-field dynamics of a molecule with an induced dipole moment (e.g., a homonuclear diatomic molecule) in a deterministic and a stochastic (fluctuating) electric field is solved to obtain the decoherence properties of the system. The average (over fluctuations) electric dipole moment and average angular momentum as a function of time for a Gaussian white noise electric field are determined via perturbative and nonperturbative solutions in the fluctuating field. In the perturbative solution, 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 Gaussian white noise magnetic field. In the nonperturbative solution, the component of the average electric dipole moment and the average angular momentum in the deterministic electric field direction also decay to zero.

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.

Processes in suspensions of nanocomposite microcapsules exposed to external electric fields

NASA Astrophysics Data System (ADS)

Ermakov, A. V.; Lomova, M. V.; Kim, V. P.; Chumakov, A. S.; Gorbachev, I. A.; Gorin, D. A.; Glukhovskoy, E. G.

2016-04-01

Microcapsules with and without magnetite nanoparticles incorporated in the polyelectrolyte shell were prepared. The effect of external electric field on the nanocomposite polyelectrolyte microcapsules containing magnetite nanoparticles in the shell was studied in this work as a function of the electric field strength. Effect of electric fields on polyelectrolyte microcapsules and the control over integrity of polyelectrolyte microcapsules with and without inorganic nanoparticles by constant electric field has been investigated. Beads effect, aggregation and deformations of nanocomposite microcapsule shell in response to electric field were observed by confocal laser scanning microscopy (CLSM). Thus, a new approach for effect on the nanocomposite microcapsule, including opening microcapsule shell by an electric field, was demonstrated. These results can be used for creation of new systems for drug delivery systems with controllable release by external electric field.

Characteristics of DC electric fields in transient plasma sheet events

NASA Astrophysics Data System (ADS)

Laakso, H. E.; Escoubet, C. P.; Masson, A.

2015-12-01

We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated.

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.

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

Direct comparison between satellite electric field measurements and the visual aurora

NASA Technical Reports Server (NTRS)

Swift, D. W.; Gurnett, D. A.

1973-01-01

Electric field data from two passes of the Injun 5 satellite, one corresponding to magnetically quiet conditions and one corresponding to substorm conditions, are compared with simultaneous all-sky-camera data from College, Alaska. In each case, a significant deviation of the electric field from the expected V x B field (where V is the satellite velocity) was evident and a distinct electric field reversal could be identified. In the region of substantial electric field equatorward of the electric field reversal a diffuse auroral arc was observed during the magnetically quiet pass and auroral patches were observed during the substorm pass. The motion of the auroral patches was consistent with the general direction and magnitude of the E x B drift computed from the satellite electric field measurements. In the substorm case the electric field reversal occurred very near a discrete auroral arc at the poleward side of the diffuse arcs and patches. Comparison of the quiet time and substorm cases suggests that the convection electric field penetrates deeper into the magnetosphere during a substorm.

Nanosecond laser coloration on stainless steel surface.

PubMed

Lu, Yan; Shi, Xinying; Huang, Zhongjia; Li, Taohai; Zhang, Meng; Czajkowski, Jakub; Fabritius, Tapio; Huttula, Marko; Cao, Wei

2017-08-02

In this work, we present laser coloration on 304 stainless steel using nanosecond laser. Surface modifications are tuned by adjusting laser parameters of scanning speed, repetition rate, and pulse width. A comprehensive study of the physical mechanism leading to the appearance is presented. Microscopic patterns are measured and employed as input to simulate light-matter interferences, while chemical states and crystal structures of composites to figure out intrinsic colors. Quantitative analysis clarifies the final colors and RGB values are the combinations of structural colors and intrinsic colors from the oxidized pigments, with the latter dominating. Therefore, the engineering and scientific insights of nanosecond laser coloration highlight large-scale utilization of the present route for colorful and resistant steels.

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.

Electric Potential and Electric Field Imaging with Dynamic Applications: 2017 Research Award Innovation

NASA Technical Reports Server (NTRS)

Generazio, Ed

2017-01-01

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 may 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. Critical design elements of current linear and real-time two-dimensional (2D) measurement systems are highlighted, and the development of a three dimensional (3D) EFI system is presented. Demonstrations for structural, electronic, human, and memory applications are shown. Recent work demonstrates that phonons may be used to create and annihilate electric dipoles within structures. Phonon induced dipoles are ephemeral and their polarization, strength, and location may be quantitatively characterized by EFI providing a new subsurface Phonon-EFI imaging technology. Initial results from real-time imaging of combustion and ion flow, and their measurement complications, will be discussed. These new EFI capabilities are demonstrated to characterize 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, combustion science, on-orbit space potential, container inspection, remote characterization of electronic circuits and level of activation, dielectric morphology of structures, tether integrity, organic molecular memory, atmospheric science, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

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.

A percolation approach to study the high electric field effect on electrical conductivity of insulating polymer

NASA Astrophysics Data System (ADS)

Benallou, Amina; Hadri, Baghdad; Martinez-Vega, Juan; El Islam Boukortt, Nour

2018-04-01

The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework.

Atmospheric Electric Field Measurements at 100 Hz and High Frequency Electric Phenomena

NASA Astrophysics Data System (ADS)

Conceição, Ricardo; Gonçalves da Silva, Hugo; Matthews, James; Bennett, Alec; Chubb, John

2016-04-01

Spectral response of Atmospheric Electric Potential Gradient (PG), symmetric to the Atmospheric Electric Field, gives important information about phenomena affecting these measurements with characteristic time-scales that appear in the spectra as specific periodicities. This is the case of urban pollution that has a clear weekly dependence and reveals itself on PG measurements by a ~7 day periodicity (Silva et al., 2014). While long-term time-scales (low frequencies) have been exhaustively explored in literature, short-term time-scales (high frequencies), above 1 Hz, have comparatively received much less attention (Anisimov et al., 1999). This is mainly because of the technical difficulties related with the storage of such a huge amount of data (for 100 Hz sampling two days of data uses a ~1 Gb file) and the response degradation of the field-meters at such frequencies. Nevertheless, important Electric Phenomena occurs for frequencies above 1 Hz that are worth pursuing, e.g. the Schumann Resonances have a signature of worldwide thunderstorm activity at frequencies that go from ~8 up to ~40 Hz. To that end the present work shows preliminary results on PG measurements at 100 Hz that took place on two clear-sky days (17th and 18th June 2015) on the South of Portugal, Évora (38.50° N, 7.91° W). The field-mill used is a JCI 131F installed in the University of Évora campus (at 2 m height) with a few trees and two buildings in its surroundings (~50 m away). This device was developed by John Chubb (Chubb, 2014) and manufactured by Chilworth (UK). It was calibrated in December 2013 and recent work by the author (who is honored in this study for his overwhelming contribution to atmospheric electricity) reveals basically a flat spectral response of the device up to frequencies of 100 Hz (Chubb, 2015). This makes this device suitable for the study of High Frequency Electric Phenomena. Anisimov, S.V., et al. (1999). On the generation and evolution of aeroelectric structures

Analysis of electric field distribution in GaAs metal-semiconductor field effect transistor with a field-modulating plate

NASA Astrophysics Data System (ADS)

Hori, Yasuko; Kuzuhara, Masaaki; Ando, Yuji; Mizuta, Masashi

2000-04-01

Electric field distribution in the channel of a field effect transistor (FET) with a field-modulating plate (FP) has been theoretically investigated using a two-dimensional ensemble Monte Carlo simulation. This analysis revealed that the introduction of FP is effective in canceling the influence of surface traps under forward bias conditions and in reducing the electric field intensity at the drain side of the gate edge under pinch-off bias conditions. This study also found that a partial overlap of the high-field region under the gate and that at the FP electrode is important for reducing the electric field intensity. The optimized metal-semiconductor FET with FP (FPFET) (LGF˜0.2 μm) exhibited a much lower peak electric field intensity than a conventional metal-semiconductor FET. Based on these numerically calculated results, we have proposed a design procedure to optimize the power FPFET structure with extremely high breakdown voltages while maintaining reasonable gain performance.

Sparse Reconstruction of Electric Fields from Radial Magnetic Data

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

Yeates, Anthony R.

2017-02-10

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 localizedmore » 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.« less

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.

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

AC Electric Field Communication for Human-Area Networking

NASA Astrophysics Data System (ADS)

Kado, Yuichi; Shinagawa, Mitsuru

We have proposed a human-area networking technology that uses the surface of the human body as a data transmission path and uses an AC electric field signal below the resonant frequency of the human body. This technology aims to achieve a “touch and connect” intuitive form of communication by using the electric field signal that propagates along the surface of the human body, while suppressing both the electric field radiating from the human body and mutual interference. To suppress the radiation field, the frequency of the AC signal that excites the transmitter electrode must be lowered, and the sensitivity of the receiver must be raised while reducing transmission power to its minimally required level. We describe how we are developing AC electric field communication technologies to promote the further evolution of a human-area network in support of ubiquitous services, focusing on three main characteristics, enabling-transceiver technique, application-scenario modeling, and communications quality evaluation. Special attention is paid to the relationship between electro-magnetic compatibility evaluation and regulations for extremely low-power radio stations based on Japan's Radio Law.

Electric field at the ground in a large tornado

NASA Astrophysics Data System (ADS)

Winn, W. P.; Hunyady, S. J.; Aulich, G. D.

2000-08-01

A number of observers have reported lightning, diffuse luminosity, or other manifestations of electrical activity in tornadoes. To try to quantify these observations, eight instruments with sensors for electric field and other parameters were placed in front of a large tornado that passed by Allison, Texas, on June 8, 1995. The edge of the tornado vortex passed over two of the instruments and near other instruments. When the two instruments were in the low-pressure region near the edge of the vortex, they indicated electric field amplitudes less than about 3 kV/m, which is low compared with amplitudes of 10 kV/m or greater that are often present below thunderclouds. The thunderstorm produced frequent lightning, but there is no evidence from the measurements or from visual observations of lightning in the vortex. However, there was one interesting electrical effect associated with the tornado: the electric field at the two instruments in the vortex relaxed to zero quickly after lightning flashes, whereas the electric field at nearby instruments outside the vortex did not relax quickly after the same lightning flashes. The most likely cause of the rapid relaxation is shielding of the electric field at the ground by charge induced on soil, leaves, grass, and other debris lofted by the strong winds.

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

Effect of strong electric field on the conformational integrity of insulin.

PubMed

Wang, Xianwei; Li, Yongxiu; He, Xiao; Chen, Shude; Zhang, John Z H

2014-10-02

A series of molecular dynamics (MD) simulations up to 1 μs for bovine insulin monomer in different external electric fields were carried out to study the effect of external electric field on conformational integrity of insulin. Our results show that the secondary structure of insulin is kept intact under the external electric field strength below 0.15 V/nm, but disruption of secondary structure is observed at 0.25 V/nm or higher electric field strength. Although the starting time of secondary structure disruption of insulin is not clearly correlated with the strength of the external electric field ranging between 0.15 and 0.60 V/nm, long time MD simulations demonstrate that the cumulative effect of exposure time under the electric field is a major cause for the damage of insulin's secondary structure. In addition, the strength of the external electric field has a significant impact on the lifetime of hydrogen bonds when it is higher than 0.60 V/nm. The fast evolution of some hydrogen bonds of bovine insulin in the presence of the 1.0 V/nm electric field shows that different microwaves could either speed up protein folding or destroy the secondary structure of globular proteins deponding on the intensity of the external electric field.

Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

PubMed

Ye, Hui; Steiger, Amanda

2015-08-12

In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural

Performance optimization in electric field gradient focusing.

PubMed

Sun, Xuefei; Farnsworth, Paul B; Tolley, H Dennis; Warnick, Karl F; Woolley, Adam T; Lee, Milton L

2009-01-02

Electric field gradient focusing (EFGF) is a technique used to simultaneously separate and concentrate biomacromolecules, such as proteins, based on the opposing forces of an electric field gradient and a hydrodynamic flow. Recently, we reported EFGF devices fabricated completely from copolymers functionalized with poly(ethylene glycol), which display excellent resistance to protein adsorption. However, the previous devices did not provide the predicted linear electric field gradient and stable current. To improve performance, Tris-HCl buffer that was previously doped in the hydrogel was replaced with a phosphate buffer containing a salt (i.e., potassium chloride, KCl) with high mobility ions. The new devices exhibited stable current, good reproducibility, and a linear electric field distribution in agreement with the shaped gradient region design due to improved ion transport in the hydrogel. The field gradient was calculated based on theory to be approximately 5.76 V/cm(2) for R-phycoerythrin when the applied voltage was 500 V. The effect of EFGF separation channel dimensions was also investigated; a narrower focused band was achieved in a smaller diameter channel. The relationship between the bandwidth and channel diameter is consistent with theory. Three model proteins were resolved in an EFGF channel of this design. The improved device demonstrated 14,000-fold concentration of a protein sample (from 2 ng/mL to 27 microg/mL).

Humidity-Induced Charge Leakage and Field Attenuation in Electric Field Microsensors

PubMed Central

Zhang, Haiyan; Fang, Dongming; Yang, Pengfei; Peng, Chunrong; Wen, Xiaolong; Xia, Shanhong

2012-01-01

The steady-state zero output of static electric field measuring systems often fluctuates, which is caused mainly by the finite leakage resistance of the water film on the surface of the electric field microsensor package. The water adsorption has been calculated using the Boltzmann distribution equation at various relative humidities for borosilicate glass and polytetrafluoroethylene surfaces. At various humidities, water film thickness has been calculated, and the induced charge leakage and field attenuation have been theoretically investigated. Experiments have been performed with microsensors to verify the theoretical predictions and the results are in good agreement. PMID:22666077

Endogenous Cortical Oscillations Constrain Neuromodulation by Weak Electric Fields

PubMed Central

Schmidt, Stephen L.; Iyengar, Apoorva K.; Foulser, A. Alban; Boyle, Michael R.; Fröhlich, Flavio

2014-01-01

Background Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation modality that may modulate cognition by enhancing endogenous neocortical oscillations with the application of sine-wave electric fields. Yet, the role of endogenous network activity in enabling and shaping the effects of tACS has remained unclear. Objective We combined optogenetic stimulation and multichannel slice electrophysiology to elucidate how the effect of weak sine-wave electric field depends on the ongoing cortical oscillatory activity. We hypothesized that the structure of the response to stimulation depended on matching the stimulation frequency to the endogenous cortical oscillation. Methods We studied the effect of weak sine-wave electric fields on oscillatory activity in mouse neocortical slices. Optogenetic control of the network activity enabled the generation of in vivo like cortical oscillations for studying the temporal relationship between network activity and sine-wave electric field stimulation. Results Weak electric fields enhanced endogenous oscillations but failed to induce a frequency shift of the ongoing oscillation for stimulation frequencies that were not matched to the endogenous oscillation. This constraint on the effect of electric field stimulation imposed by endogenous network dynamics was limited to the case of weak electric fields targeting in vivo-like network dynamics. Together, these results suggest that the key mechanism of tACS may be enhancing but not overriding of intrinsic network dynamics. Conclusion Our results contribute to understanding the inconsistent tACS results from human studies and propose that stimulation precisely adjusted in frequency to the endogenous oscillations is key to rational design of non-invasive brain stimulation paradigms. PMID:25129402

Comparison of femtosecond- and nanosecond-two-photon-absorption laser-induced fluorescence (TALIF) of atomic oxygen in atmospheric-pressure plasmas

NASA Astrophysics Data System (ADS)

Schmidt, Jacob B.; Sands, Brian; Scofield, James; Gord, James R.; Roy, Sukesh

2017-05-01

Absolute number densities of atomic species produced by nanosecond (ns)-duration, repetitively pulsed electric discharges are measured by two-photon-absorption laser-induced fluorescence (TALIF). Unique to this work is the development of femtosecond-laser-based TALIF (fs-TALIF) that offers a number of advantages over more conventional nanosecond (ns)-pulse-duration laser techniques, such as higher-fidelity quenching rate measurements over a wide pressure range, significantly reduced photolytic interference (including photo-dissociation and photo-ionization), ability to collect two-dimensional images of atomic-species number densities with high spatial resolution aided by higher signal level, and efficient and accurate measurements of atomic-species number densities due to the higher repetition rates of the laser. For full quantification of these advantages, atomic-oxygen TALIF signals are collected from an atmospheric-pressure plasma jet employing both ns- and fs-duration laser-excitation pulses and the results are compared and contrasted.

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

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.

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.

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.

Soap-film flow induced by electric fields in asymmetric frames.

PubMed

Mollaei, S; Nasiri, M; Soltanmohammadi, N; Shirsavar, R; Ramos, A; Amjadi, A

2018-04-01

Net fluid flow of soap films induced by (ac or dc) electric fields in asymmetric frames is presented. Previous experiments of controllable soap film flow required the simultaneous use of an electrical current passing through the film and an external electric field or the use of nonuniform ac electric fields. Here a single voltage difference generates both the electrical current going through the film and the electric field that actuates on the charge induced on the film. The film is set into global motion due to the broken symmetry that appears by the use of asymmetric frames. If symmetric frames are used, the film flow is not steady but time dependent and irregular. Finally, we study numerically these film flows by employing the model of charge induction in ohmic liquids.

Soap-film flow induced by electric fields in asymmetric frames

NASA Astrophysics Data System (ADS)

Mollaei, S.; Nasiri, M.; Soltanmohammadi, N.; Shirsavar, R.; Ramos, A.; Amjadi, A.

2018-04-01

Net fluid flow of soap films induced by (ac or dc) electric fields in asymmetric frames is presented. Previous experiments of controllable soap film flow required the simultaneous use of an electrical current passing through the film and an external electric field or the use of nonuniform ac electric fields. Here a single voltage difference generates both the electrical current going through the film and the electric field that actuates on the charge induced on the film. The film is set into global motion due to the broken symmetry that appears by the use of asymmetric frames. If symmetric frames are used, the film flow is not steady but time dependent and irregular. Finally, we study numerically these film flows by employing the model of charge induction in ohmic liquids.

The Vector Electric Field Instrument on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Kujawski, J.; Uribe, P.; Bromund, K.; Fourre, R.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; McCarthy, M.;

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.

Pentacene Excitons in Strong Electric Fields.

PubMed

Kuhnke, Klaus; Turkowski, Volodymyr; Kabakchiev, Alexander; Lutz, Theresa; Rahman, Talat S; Kern, Klaus

2018-02-05

Electroluminescence spectroscopy of organic semiconductors in the junction of a scanning tunneling microscope (STM) provides access to the polarizability of neutral excited states in a well-characterized molecular geometry. We study the Stark shift of the self-trapped lowest singlet exciton at 1.6 eV in a pentacene nanocrystal. Combination of density functional theory (DFT) and time-dependent DFT (TDDFT) with experiment allows for assignment of the observation to a charge-transfer (CT) exciton. Its charge separation is perpendicular to the applied field, as the measured polarizability is moderate and the electric field in the STM junction is strong enough to dissociate a CT exciton polarized parallel to the applied field. The calculated electric-field-induced anisotropy of the exciton potential energy surface will also be of relevance to photovoltaic applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electric Field-Controlled Ion Transport In TiO2 Nanochannel.

PubMed

Li, Dan; Jing, Wenheng; Li, Shuaiqiang; Shen, Hao; Xing, Weihong

2015-06-03

On the basis of biological ion channels, we constructed TiO2 membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na+ and Mg2+ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg2+ channel closed at -2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na+ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration.

Picosecond pulsed electric fields induce apoptosis in HeLa cells via the endoplasmic reticulum stress and caspase-dependent signaling pathways.

PubMed

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

2013-03-01

The non-invasive treatment of tumors with preserved fertility holds great promise. The application of pulsed electric field (PEF) is a new biomedical engineering technique for tumor therapy. Picosecond pulsed electric fields (psPEF) can be transferred to target deep tissue non-invasively and precisely; however, research of the biological effects of psPEF on cells is limited. Electric theory predicts that when the pulse duration decreases to nanoseconds and picoseconds, it will mainly affect organelles and lead to intracellular electromanipulations. Previous studies have shown that psPEF targets the mitochondria and induces apoptosis through a mitochondrial-mediated pathway in HeLa cells. The endoplasmic reticulum is also involved in the intrinsic pathways of apoptosis. In the present study, HeLa cells were exposed to psPEF to investigate the underlying mechanisms of apoptosis. MTT assay demonstrated that psPEF displayed strong growth inhibitory effects on HeLa cells. Treatment with psPEF led to marked cell apoptosis and cell cycle arrest at the G2/M phase. In addition, psPEF affected the phosphorylation levels of endoplasmic reticulum sensors and upregulated the expression of glucose-regulated protein 78 (GRP78), glucose-regulated protein 94 (GRP94) and CCAAT enhancer-binding protein (C/EBP) homologous protein (CHOP). These changes were accompanied by the elevation of intracellular Ca2+ concentrations. Furthermore, the activation of caspase-12, -9 and -3, led to the release of cytochrome c, as well as the upregulation of Bax and the downregulation of Bcl-2, as observed in the HeLa cells. Taken together, these data suggest that psPEF is an efficient apoptosis-inducing agent for HeLa cells, which exerts its effects, at least partially, via the endoplasmic reticulum stress and caspase-dependent signaling pathways.

Auroral zone electric fields from DE 1 and 2 at magnetic conjunctions

NASA Technical Reports Server (NTRS)

Weimer, D. R.; Goertz, C. K.; Gurnett, D. A.; Maynard, N. C.; Burch, J. L.

1985-01-01

Nearly simultaneous measurements of auroral zone electric fields are obtained by the Dynamics Explorer spacecraft at altitudes below 900 km and above 4,500 km during magnetic conjunctions. The measured electric fields are usually perpendicular to the magnetic field lines. The north-south meridional electric fields are projected to a common altitude by a mapping function which accounts for the convergence of the magnetic field lines. When plotted as a function of invariant latitude, graphs of the projected electric fields measured by both DE-1 and DE-2 show that the large-scale electric field is the same at both altitudes, as expected. Superimposed on the large-scale fields, however, are small-scale features with wavelengths less than 100 km which are larger in magnitude at the higher altitude. Fourier transforms of the electric fields show that the magnitudes depend on wavelength. Outside of the auroral zone the electric field spectrums are nearly identical. But within the auroral zone the high and low altitude electric fields have a ratio which increases with the reciprocal of the wavelength. The small-scale electric field variations are associated with field-aligned currents. These currents are measured with both a plasma instrument and magnetometer on DE-1.

Electric field computation analysis for the Electric Field Detector (EFD) on board the China Seismic-Electromagnetic Satellite (CSES)

NASA Astrophysics Data System (ADS)

Diego, P.; Bertello, I.; Candidi, M.; Mura, A.; Coco, I.; Vannaroni, G.; Ubertini, P.; Badoni, D.

2017-11-01

The floating potential variability of the Electric Field Detector (EFD) probes, on board the Chinese Seismo-Electromagnetic Satellite (CSES), has been modeled, and the effects of several structural and environmental elements have been determined. The expected floating potentials of the probes are computed considering the ambient ionospheric plasma parameter variations. In addition, the ion collection variability, due to the different probe attitudes along the orbit, and its effect on each floating potential, are considered. Particular attention is given to the analysis of the shadow produced by the stubs, in order to determine the artificial electric field introduced by instrumental effects which has to be subtracted from the real measurements. The modulation of the altered electric field, due to the effect on shadowing of the ion drift, as measured by the ESA satellite Swarm A in a similar orbit, is also modeled. Such simulations are made in preparation of real EFD data analysis performed during the upcoming flight of CSES.

Effectiveness of a worker-worn electric-field sensor to detect power-line proximity and electrical-contact.

PubMed

Zeng, Shengke; Powers, John R; Newbraugh, Bradley H

2010-06-01

Construction workers suffer the most electrocutions among all industries. Currently, there are no electrical contact warning devices on the market to protect workers. This paper proposes a worker-worn electric-field sensor. As the worker is in proximity to, or in contact with, a live power-circuit, the sensor sets off an audible/visual warning alarm. The sensor also has the potential to wirelessly trip a wireless-capable circuit breaker, and to trigger a wireless transmitter to notify emergency response of an electrical contact. An experiment was conducted to measure electric-field variation on simulated human-wrists (10 defrosted hog-legs) in various proximities and in electrical-contact to a simulated power-circuit. The purpose of these tests was to determine the feasibility of developing a worker-worn electric-field detection sensor for use in protecting workers from contact with energized electrical conductors. This study observed a significant electric-field-magnitude increase as a hog-leg approaches the live-circuit, and the distinct electric-field-magnitude jump as the leg contacts with the live-circuit. The observation indicates that this sensor can be an effective device to warn the workers of electrical hazards. Additionally, the sensor has the potential to wirelessly trip a wireless-capable circuit-breaker and trigger a wireless transmitter (such as a cell phone) to notify an emergency response. The prompt notification prevents the worker from further injury caused by postponed medical-care. Widespread use of this sensor could lower electrocution and electrically related injury rates in the construction industry. (c) 2010 Elsevier Ltd. All rights reserved.

Effects of the reconnection electric field on crescent electron distribution functions in asymmetric guide field reconnection

NASA Astrophysics Data System (ADS)

Bessho, N.; Chen, L. J.; Hesse, M.; Wang, S.

2017-12-01

In asymmetric reconnection with a guide field in the Earth's magnetopause, electron motion in the electron diffusion region (EDR) is largely affected by the guide field, the Hall electric field, and the reconnection electric field. The electron motion in the EDR is neither simple gyration around the guide field nor simple meandering motion across the current sheet. The combined meandering motion and gyration has essential effects on particle acceleration by the in-plane Hall electric field (existing only in the magnetospheric side) and the out-of-plane reconnection electric field. We analyze electron motion and crescent-shaped electron distribution functions in the EDR in asymmetric guide field reconnection, and perform 2-D particle-in-cell (PIC) simulations to elucidate the effect of reconnection electric field on electron distribution functions. Recently, we have analytically expressed the acceleration effect due to the reconnection electric field on electron crescent distribution functions in asymmetric reconnection without a guide field (Bessho et al., Phys. Plasmas, 24, 072903, 2017). We extend the theory to asymmetric guide field reconnection, and predict the crescent bulge in distribution functions. Assuming 1D approximation of field variations in the EDR, we derive the time period of oscillatory electron motion (meandering + gyration) in the EDR. The time period is expressed as a hybrid of the meandering period and the gyro period. Due to the guide field, electrons not only oscillate along crescent-shaped trajectories in the velocity plane perpendicular to the antiparallel magnetic fields, but also move along parabolic trajectories in the velocity plane coplanar with magnetic field. The trajectory in the velocity space gradually shifts to the acceleration direction by the reconnection electric field as multiple bounces continue. Due to the guide field, electron distributions for meandering particles are bounded by two paraboloids (or hyperboloids) in the

Electric field effect in superconductor-ferroelectric structures

NASA Technical Reports Server (NTRS)

Lemanov, V. V.

1995-01-01

Electric field effect (the E-effect) in superconductors has been studied since 1960 when Glover and Sherill published their results on a shift of the critical temperature T(sub c) about 0.1 mK in Sn and In thin films under the action Off the field E=300 kV/cm. Stadler was the first to study the effect or spontaneous polarization of ferroelectric substrate on the electric properties of superconductors. He observed that the reversal of polarization of TGS substrate under action of external electric field in Sn-TGS structures induced the T(sub c) shift in Sn about 1.3 mK. Since in this case the effect is determined not by the electric field but by the spontaneous polarization, we may call this effect the P-effect. High-T(sub c) superconductors opened the new possibilities to study the E- and P-effects due to low charge carrier density, as compared to conventional superconductors, and to anomalously small coherence length. Experiments in this field began in many laboratories but a breakthrough was made where a shift in T(sub c) by 50 mK was observed in YBCO thin films. Much higher effects were observed in subsequent studies. The first experiments on the P-effect in high-T(sub c) superconductors were reported elsewhere. In this report we shall give a short description of study on the P-effect in high-T(sub c) superconductors.

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.

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.

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

The relationship between anatomically correct electric and magnetic field dosimetry and publishe delectric and magnetic field exposure limits.

PubMed

Kavet, Robert; Dovan, Thanh; Reilly, J Patrick

2012-12-01

Electric and magnetic field exposure limits published by International Commission for Non-Ionizing Radiation Protection and Institute of Electrical and Electronics Engineers are aimed at protection against adverse electrostimulation, which may occur by direct coupling to excitable tissue and, in the case of electric fields, through indirect means associated with surface charge effects (e.g. hair vibration, skin sensations), spark discharge and contact current. For direct coupling, the basic restriction (BR) specifies the not-to-be-exceeded induced electric field. The key results of anatomically based electric and magnetic field dosimetry studies and the relevant characteristics of excitable tissue were first identified. This permitted us to assess the electric and magnetic field exposure levels that induce dose in tissue equal to the basic restrictions, and the relationships of those exposure levels to the limits now in effect. We identify scenarios in which direct coupling of electric fields to peripheral nerve could be a determining factor for electric field limits.

Questions Students Ask: Why Not Bend Light with an Electric Field?

ERIC Educational Resources Information Center

Van Heuvelen, Alan

1983-01-01

In response to a question, "Why not use a magnetic or electric field to deflect light?," reviews the relation between electric charge and electric/magnetic fields. Discusses the Faraday effect, (describing matter as an intermediary in the rotation of the place of polarization) and other apparent interactions of light with electric/magnetic fields.…

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

PubMed Central

Huang, Yu; Liu, Anli A; Lafon, Belen; Friedman, Daniel; Dayan, Michael; Wang, Xiuyuan; Bikson, Marom; Doyle, Werner K; Devinsky, Orrin; Parra, Lucas C

2017-01-01

Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials. DOI: http://dx.doi.org/10.7554/eLife.18834.001 PMID:28169833

Simulation study on electric field intensity above train roof

NASA Astrophysics Data System (ADS)

Fan, Yizhe; Li, Huawei; Yang, Shasha

2018-04-01

In order to understand the distribution of electric field in the space above the train roof accurately and select the installation position of the detection device reasonably, in this paper, the 3D model of pantograph-catenary is established by using SolidWorks software, and the spatial electric field distribution of pantograph-catenary model is simulated based on Comsol software. According to the electric field intensity analysis within the 0.4m space above train roof, we give a reasonable installation of the detection device.

Simulations of particle structuring driven by electric fields

NASA Astrophysics Data System (ADS)

Hu, Yi; Vlahovska, Petia; Miksis, Michael

2015-11-01

Recent experiments (Ouriemi and Vlahovska, 2014) show intriguing surface patterns when a uniform electric field is applied to a droplet covered with colloidal particles. Depending on the particle properties and the electric field intensity, particles organize into an equatorial belt, pole-to-pole chains, or dynamic vortices. Here we present 3D simulations of the collective particle dynamics, which account for electrohydrodynamic flow and dielectrophoresis of particles. In stronger electric fields, particles are expected to undergo Quincke rotation and impose disturbance to the ambient flow. Transition from ribbon-shaped belt to rotating clusters is observed in the presence of the rotation-induced hydrodynamical interactions. Our results provide insight into the various particle assembles discovered in the experiments.

Electric-field-driven phase transition in vanadium dioxide

NASA Astrophysics Data System (ADS)

Wu, B.; Zimmers, A.; Aubin, H.; Ghosh, R.; Liu, Y.; Lopez, R.

2011-12-01

We report on local probe measurements of current-voltage and electrostatic force-voltage characteristics of electric-field-induced insulator to metal transition in VO2 thin film. In conducting AFM mode, switching from the insulating to metallic state occurs for electric-field threshold E˜6.5×107Vm-1 at 300K. Upon lifting the tip above the sample surface, we find that the transition can also be observed through a change in electrostatic force and in tunneling current. In this noncontact regime, the transition is characterized by random telegraphic noise. These results show that electric field alone is sufficient to induce the transition; however, the electronic current provides a positive feedback effect that amplifies the phenomena.

Cellulose-Based Smart Fluids under Applied Electric Fields

PubMed Central

Choi, Kisuk; Gao, Chun Yan; Nam, Jae Do

2017-01-01

Cellulose particles, their derivatives and composites have special environmentally benign features and are abundant in nature with their various applications. This review paper introduces the essential properties of several types of cellulose and their derivatives obtained from various source materials, and their use in electro-responsive electrorheological (ER) suspensions, which are smart fluid systems that are actively responsive under applied electric fields, while, at zero electric field, ER fluids retain a liquid-like state. Given the actively controllable characteristics of cellulose-based smart ER fluids under an applied electric field regarding their rheological and dielectric properties, they can potentially be applied for various industrial devices including dampers and haptic devices. PMID:28891966

Electric field enhanced hydrogen storage on polarizable materials substrates

PubMed Central

Zhou, J.; Wang, Q.; Sun, Q.; Jena, P.; Chen, X. S.

2010-01-01

Using density functional theory, we show that an applied electric field can substantially improve the hydrogen storage properties of polarizable substrates. This new concept is demonstrated by adsorbing a layer of hydrogen molecules on a number of nanomaterials. When one layer of H2 molecules is adsorbed on a BN sheet, the binding energy per H2 molecule increases from 0.03 eV/H2 in the field-free case to 0.14 eV/H2 in the presence of an electric field of 0.045 a.u. The corresponding gravimetric density of 7.5 wt% is consistent with the 6 wt% system target set by Department of Energy for 2010. The strength of the electric field can be reduced if the substrate is more polarizable. For example, a hydrogen adsorption energy of 0.14 eV/H2 can be achieved by applying an electric field of 0.03 a.u. on an AlN substrate, 0.006 a.u. on a silsesquioxane molecule, and 0.007 a.u. on a silsesquioxane sheet. Thus, application of an electric field to a polarizable substrate provides a novel way to store hydrogen; once the applied electric field is removed, the stored H2 molecules can be easily released, thus making storage reversible with fast kinetics. In addition, we show that materials with rich low-coordinated nonmetal anions are highly polarizable and can serve as a guide in the design of new hydrogen storage materials. PMID:20133647

Giant Electric Field Enhancement in Split Ring Resonators Featuring Nanometer-Sized Gaps

NASA Astrophysics Data System (ADS)

Bagiante, S.; Enderli, F.; Fabiańska, J.; Sigg, H.; Feurer, T.

2015-01-01

Today's pulsed THz sources enable us to excite, probe, and coherently control the vibrational or rotational dynamics of organic and inorganic materials on ultrafast time scales. Driven by standard laser sources THz electric field strengths of up to several MVm-1 have been reported and in order to reach even higher electric field strengths the use of dedicated electric field enhancement structures has been proposed. Here, we demonstrate resonant electric field enhancement structures, which concentrate the incident electric field in sub-diffraction size volumes and show an electric field enhancement as high as ~14,000 at 50 GHz. These values have been confirmed through a combination of near-field imaging experiments and electromagnetic simulations.

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.

Characteristics of a novel nanosecond DBD microplasma reactor for flow applications

NASA Astrophysics Data System (ADS)

Elkholy, A.; Nijdam, S.; van Veldhuizen, E.; Dam, N.; van Oijen, J.; Ebert, U.; de Goey, L. Philip H.

2018-05-01

We present a novel microplasma flow reactor using a dielectric barrier discharge (DBD) driven by repetitive nanosecond high-voltage pulses. Our DBD-based geometry can generate a non-thermal plasma discharge at atmospheric pressure and below in a regular pattern of micro-channels. This reactor can work continuously up to about 100 min in air, depending on the pulse repetition rate and operating pressure. We here present the geometry and main characteristics of the reactor. Pulse energies of 1.46 and 1.3 μJ per channel at atmospheric pressure and 50 mbar, respectively, have been determined by time-resolved measurements of current and voltage. Time-resolved optical emission spectroscopy measurements have been performed to calculate the relative species concentrations and temperatures (vibrational and rotational) of the discharge. The effects of the operating pressure and flow velocity on the discharge intensity have been investigated. In addition, the effective reduced electric field strength {(E/N)}eff} has been obtained from the intensity ratio of vibronic emission bands of molecular nitrogen at different operating pressures and different locations. The derived {(E/N)}eff} increases gradually from about 550 to 4600 Td when decreasing the pressure from 1 bar to 100 mbar. Below 100 mbar, further pressure reduction results in a significant increase in {(E/N)}eff} up to about 10000 Td at 50 mbar.

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.

Wind tunnel experiments on flow separation control of an Unmanned Air Vehicle by nanosecond discharge plasma aerodynamic actuation

NASA Astrophysics Data System (ADS)

Kang, Chen; Hua, Liang

2016-02-01

Plasma flow control (PFC) is a new kind of active flow control technology, which can improve the aerodynamic performances of aircrafts remarkably. The flow separation control of an unmanned air vehicle (UAV) by nanosecond discharge plasma aerodynamic actuation (NDPAA) is investigated experimentally in this paper. Experimental results show that the applied voltages for both the nanosecond discharge and the millisecond discharge are nearly the same, but the current for nanosecond discharge (30 A) is much bigger than that for millisecond discharge (0.1 A). The flow field induced by the NDPAA is similar to a shock wave upward, and has a maximal velocity of less than 0.5 m/s. Fast heating effect for nanosecond discharge induces shock waves in the quiescent air. The lasting time of the shock waves is about 80 μs and its spread velocity is nearly 380 m/s. By using the NDPAA, the flow separation on the suction side of the UAV can be totally suppressed and the critical stall angle of attack increases from 20° to 27° with a maximal lift coefficient increment of 11.24%. The flow separation can be suppressed when the discharge voltage is larger than the threshold value, and the optimum operation frequency for the NDPAA is the one which makes the Strouhal number equal one. The NDPAA is more effective than the millisecond discharge plasma aerodynamic actuation (MDPAA) in boundary layer flow control. The main mechanism for nanosecond discharge is shock effect. Shock effect is more effective in flow control than momentum effect in high speed flow control. Project supported by the National Natural Science Foundation of China (Grant Nos. 61503302, 51207169, and 51276197), the China Postdoctoral Science Foundation (Grant No. 2014M562446), and the Natural Science Foundation of Shaanxi Province, China (Grant No. 2015JM1001).

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.

Electric field numerical simulation of disc type electrostatic spinning spinneret

NASA Astrophysics Data System (ADS)

Wei, L.; Deng, ZL; Qin, XH; Liang, ZY

2018-01-01

Electrospinning is a new type of free-end spinning built on electric field. Different from traditional single needle spinneret, in this study, a new disc type free surface spinneret is used to produce multiple jets, this will greatly improve production efficiency of nanofiber. The electric-field distribution of spinneret is the crux of the formation and trajectory of jets. In order to probe the electric field intensity of the disc type spinneret, computational software of Ansoft Maxwell 12 is adopted for a precise and intuitive analysis. The results showed that the whole round cambered surface of the spinning solution at edge of each layer of the spinneret with the maximum curvature has the highest electric field intensity, and through the simulation of the electric field distribution of different spinneret parameters such as layer, the height and radius of the spinneret. Influences of various parameters on the electrostatic spinning are obtained.

Deformation analysis of vesicles in an alternating-current electric field.

PubMed

Tang, Yu-Gang; Liu, Ying; Feng, Xi-Qiao

2014-08-01

In this paper the shape equation for axisymmetric vesicles subjected to an ac electric field is derived on the basis of the liquid-crystal model. The equilibrium morphology of a lipid vesicle is determined by the minimization of its free energy in coupled mechanical and ac electric fields. Besides elastic bending, the effects of the osmotic pressure difference, surface tension, Maxwell pressure, and flexoelectric and dielectric properties of phospholipid membrane as well are taken into account. The influences of elastic bending, osmotic pressure difference, and surface tension on the frequency-dependent behavior of a vesicle membrane in an ac electric field are examined. The singularity of the ac electric field is also investigated. Our theoretical results of vesicle deformation agree well with previous experimental and numerical results. The present study provides insights into the physical mechanisms underpinning the frequency-dependent morphological evolution of vesicles in the electric and mechanical fields.

Analytical and numerical investigations of bubble behavior in electric fields

NASA Astrophysics Data System (ADS)

Vorreiter, Janelle Orae

The behavior of gas bubbles in liquids is important in a wide range of applications. This study is motivated by a desire to understand the motion of bubbles in the absence of gravity, as in many aerospace applications. Phase-change devices, cryogenic tanks and life-support systems are some of the applications where bubbles exist in space environments. One of the main difficulties in employing devices with bubbles in zero gravity environments is the absence of a buoyancy force. The use of an electric field is found to be an effective means of replacing the buoyancy force, improving the control of bubbles in space environments. In this study, analytical and numerical investigations of bubble behavior under the influence of electric fields are performed. The problem is a difficult one in that the physics of the liquid and the electric field need to be considered simultaneously to model the dynamics of the bubble. Simplifications are required to reduce the problem to a tractable form. In this work, for the liquid and the electric field, assumptions are made which reduce the problem to one requiring only the solution of potentials in the domain of interest. Analytical models are developed using a perturbation analysis applicable for small deviations from a spherical shape. Numerical investigations are performed using a boundary integral code. A number of configurations are found to be successful in promoting bubble motion by varying properties of the electric fields. In one configuration, the natural frequencies of a bubble are excited using time-varying electric and pressure fields. The applied electric field is spatially uniform with frequencies corresponding to shape modes of the bubble. The resulting bubble velocity is related to the strength of the electric field as well as the characteristics of the applied fields. In another configuration, static non-uniform fields are used to encourage bubble motion. The resulting motion is related to the degree of non

Acceleration of auroral electrons in parallel electric fields

NASA Technical Reports Server (NTRS)

Kaufmann, R. L.; Walker, D. N.; Arnoldy, R. L.

1976-01-01

Rocket observations of auroral electrons are compared with the predictions of a number of theoretical acceleration mechanisms that involve an electric field parallel to the earth's magnetic field. The theoretical models are discussed in terms of required plasma sources, the location of the acceleration region, and properties of necessary wave-particle scattering mechanisms. We have been unable to find any steady state scatter-free electric field configuration that predicts electron flux distributions in agreement with the observations. The addition of a fluctuating electric field or wave-particle scattering several thousand kilometers above the rocket can modify the theoretical flux distributions so that they agree with measurements. The presence of very narrow energy peaks in the flux contours implies a characteristic temperature of several tens of electron volts or less for the source of field-aligned auroral electrons and a temperature of several hundred electron volts or less for the relatively isotropic 'monoenergetic' auroral electrons. The temperature of the field-aligned electrons is more representative of the magnetosheath or possibly the ionosphere as a source region than of the plasma sheet.

Electric Fields and Enzyme Catalysis

PubMed Central

Fried, Stephen D.; Boxer, Steven G.

2017-01-01

What happens inside an enzyme’s active site to allow slow and difficult chemical reactions to occur so rapidly? This question has occupied biochemists’ attention for a long time. Computer models of increasing sophistication have predicted an important role for electrostatic interactions in enzymatic reactions, yet this hypothesis has proved vexingly difficult to test experimentally. Recent experiments utilizing the vibrational Stark effect make it possible to measure the electric field a substrate molecule experiences when bound inside its enzyme’s active site. These experiments have provided compelling evidence supporting a major electrostatic contribution to enzymatic catalysis. Here, we review these results and develop a simple model for electrostatic catalysis that enables us to incorporate disparate concepts introduced by many investigators to describe how enzymes work into a more unified framework stressing the importance of electric fields at the active site. PMID:28375745

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

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

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

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

Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics

DOE PAGES

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

2018-01-30

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

MAGNETIC BRAIDING AND PARALLEL ELECTRIC FIELDS

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

Wilmot-Smith, A. L.; Hornig, G.; Pontin, D. I.

2009-05-10

The braiding of the solar coronal magnetic field via photospheric motions-with subsequent relaxation and magnetic reconnection-is one of the most widely debated ideas of solar physics. We readdress the theory in light of developments in three-dimensional magnetic reconnection theory. It is known that the integrated parallel electric field along field lines is the key quantity determining the rate of reconnection, in contrast with the two-dimensional case where the electric field itself is the important quantity. We demonstrate that this difference becomes crucial for sufficiently complex magnetic field structures. A numerical method is used to relax a braided magnetic field towardmore » an ideal force-free equilibrium; the field is found to remain smooth throughout the relaxation, with only large-scale current structures. However, a highly filamentary integrated parallel current structure with extremely short length-scales is found in the field, with the associated gradients intensifying during the relaxation process. An analytical model is developed to show that, in a coronal situation, the length scales associated with the integrated parallel current structures will rapidly decrease with increasing complexity, or degree of braiding, of the magnetic field. Analysis shows the decrease in these length scales will, for any finite resistivity, eventually become inconsistent with the stability of the coronal field. Thus the inevitable consequence of the magnetic braiding process is a loss of equilibrium of the magnetic field, probably via magnetic reconnection events.« less

Nanoscale electron manipulation in metals with intense THz electric fields

NASA Astrophysics Data System (ADS)

Takeda, Jun; Yoshioka, Katsumasa; Minami, Yasuo; Katayama, Ikufumi

2018-03-01

Improved control over the electromagnetic properties of metals on a nanoscale is crucial for the development of next-generation nanoelectronics and plasmonic devices. Harnessing the terahertz (THz)-electric-field-induced nonlinearity for the motion of electrons is a promising method of manipulating the local electromagnetic properties of metals, while avoiding undesirable thermal effects and electronic transitions. In this review, we demonstrate the manipulation of electron delocalization in ultrathin gold (Au) films with nanostructures, by intense THz electric-field transients. On increasing the electric-field strength of the THz pulses, the transmittance in the THz-frequency region abruptly decreases around the percolation threshold. The observed THz-electric-field-induced nonlinearity is analysed, based on the Drude-Smith model. The results suggest that ultrafast electron delocalization occurs by electron tunnelling across the narrow insulating bridge between the Au nanostructures, without material breakdown. In order to quantitatively discuss the tunnelling process, we perform scanning tunnelling microscopy with carrier-envelope phase (CEP)-controlled single-cycle THz electric fields. By applying CEP-controlled THz electric fields to the 1 nm nanogap between a metal nanotip and graphite sample, many electrons could be coherently driven through the quantum tunnelling process, either from the nanotip to the sample or vice versa. The presented concept, namely, electron tunnelling mediated by CEP-controlled single-cycle THz electric fields, can facilitate the development of nanoscale electron manipulation, applicable to next-generation ultrafast nanoelectronics and plasmonic devices.

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.

Vector electric field measurement via position-modulated Kelvin probe force microscopy

NASA Astrophysics Data System (ADS)

Dwyer, Ryan P.; Smieska, Louisa M.; Tirmzi, Ali Moeed; Marohn, John A.

2017-10-01

High-quality spatially resolved measurements of electric fields are critical to understanding charge injection, charge transport, and charge trapping in semiconducting materials. Here, we report a variation of frequency-modulated Kelvin probe force microscopy that enables spatially resolved measurements of the electric field. We measure electric field components along multiple directions simultaneously by employing position modulation and lock-in detection in addition to numeric differentiation of the surface potential. We demonstrate the technique by recording linescans of the in-plane electric field vector in the vicinity of a patch of trapped charge in a 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DPh-BTBT) organic field-effect transistor. This technique is simple to implement and should be especially useful for studying electric fields in spatially inhomogeneous samples like organic transistors and photovoltaic blends.

Controlling turbulent drag across electrolytes using electric fields.

PubMed

Ostilla-Mónico, Rodolfo; Lee, Alpha A

2017-07-01

Reversible in operando control of friction is an unsolved challenge that is crucial to industrial tribology. Recent studies show that at low sliding velocities, this control can be achieved by applying an electric field across electrolyte lubricants. However, the phenomenology at high sliding velocities is yet unknown. In this paper, we investigate the hydrodynamic friction across electrolytes under shear beyond the transition to turbulence. We develop a novel, highly parallelised numerical method for solving the coupled Navier-Stokes Poisson-Nernst-Planck equation. Our results show that turbulent drag cannot be controlled across dilute electrolytes using static electric fields alone. The limitations of the Poisson-Nernst-Planck formalism hint at ways in which turbulent drag could be controlled using electric fields.

Optimization of Pockels electric field in transverse modulated optical voltage sensor

NASA Astrophysics Data System (ADS)

Huang, Yifan; Xu, Qifeng; Chen, Kun-Long; Zhou, Jie

2018-05-01

This paper investigates the possibilities of optimizing the Pockels electric field in a transverse modulated optical voltage sensor with a spherical electrode structure. The simulations show that due to the edge effect and the electric field concentrations and distortions, the electric field distributions in the crystal are non-uniform. In this case, a tiny variation in the light path leads to an integral error of more than 0.5%. Moreover, a 2D model cannot effectively represent the edge effect, so a 3D model is employed to optimize the electric field distributions. Furthermore, a new method to attach a quartz crystal to the electro-optic crystal along the electric field direction is proposed to improve the non-uniformity of the electric field. The integral error is reduced therefore from 0.5% to 0.015% and less. The proposed method is simple, practical and effective, and it has been validated by numerical simulations and experimental tests.

Creation of vector bosons by an electric field in curved spacetime

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

Kangal, E. Ersin; Yanar, Hilmi; Havare, Ali

2014-04-15

We investigate the creation rate of massive spin-1 bosons in the de Sitter universe by a time-dependent electric field via the Duffin–Kemmer–Petiau (DKP) equation. Complete solutions are given by the Whittaker functions and particle creation rate is computed by using the Bogoliubov transformation technique. We analyze the influence of the electric field on the particle creation rate for the strong and vanishing electric fields. We show that the electric field amplifies the creation rate of charged, massive spin-1 particles. This effect is analyzed by considering similar calculations performed for scalar and spin-1/2 particles. -- Highlights: •Duffin–Kemmer–Petiau equation is solved exactlymore » in the presence of an electrical field. •Solutions were made in (1+1)-dimensional curved spacetime. •Particle creation rate for the de Sitter model is calculated. •Pure gravitational or pure electrical field effect on the creation rate is analyzed.« less

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.

Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip

PubMed Central

Agudelo, Carlos; Packirisamy, Muthukumaran; Geitmann, Anja

2016-01-01

Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies—consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions. PMID:26804186

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.

Critical electric field for maximum tunability in nonlinear dielectrics

NASA Astrophysics Data System (ADS)

Akdogan, E. K.; Safari, A.

2006-09-01

The authors develop a self-consistent thermodynamic theory to compute the critical electric field at which maximum tunability is attained in a nonlinear dielectric. They then demonstrate that the stored electrostatic free energy functional has to be expanded at least up to the sixth order in electric field so as to define the critical field, and show that it depends solely on the fourth and sixth order permittivities. They discuss the deficiency of the engineering tunability metric in describing nonlinear dielectric phenomena, introduce a critical field renormalized tunability parameter, and substantiate the proposed formalism by computing the critical electric field for prototypical 0.9Pb(Mg1/3,Nb2/3)-0.1PbTiO3 and Ba(Ti0.85,Sn0.15)O3 paraelectrics.

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

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.

Electric-field enhanced performance in catalysis and solid-state devices involving gases

DOEpatents

Blackburn, Bryan M.; Wachsman, Eric D.; Van Assche, IV, Frederick Martin

2015-05-19

Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

Two Effects of Electrical Fields on Chloroplasts 1

PubMed Central

Arnold, William A.; Azzi, Jim R.

1977-01-01

An electrical field across a suspension of Chenopodium chloroplasts stimulates the emission of delayed light during the time the field is on. This stimulation can be used to calculate the distance over which the electron moves in the untrapping process that gives the delayed light. An electrical field applied at the time of illumination gives a polarization to the suspension of chloroplasts that lasts for some seconds. This polarization is a new way to study delayed light and fluorescence from chloroplasts. Images PMID:16660112

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.

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.

The induced electric field due to a current transient

NASA Astrophysics Data System (ADS)

Beck, Y.; Braunstein, A.; Frankental, S.

2007-05-01

Calculations and measurements of the electric fields, induced by a lightning strike, are important for understanding the phenomenon and developing effective protection systems. In this paper, a novel approach to the calculation of the electric fields due to lightning strikes, using a relativistic approach, is presented. This approach is based on a known current wave-pair model, representing the lightning current wave. The model presented is one that describes the lightning current wave, either at the first stage of the descending charge wave from the cloud or at the later stage of the return stroke. The electric fields computed are cylindrically symmetric. A simplified method for the calculation of the electric field is achieved by using special relativity theory and relativistic considerations. The proposed approach, described in this paper, is based on simple expressions (by applying Coulomb's law) compared with much more complicated partial differential equations based on Maxwell's equations. A straight forward method of calculating the electric field due to a lightning strike, modelled as a negative-positive (NP) wave-pair, is determined by using the special relativity theory in order to calculate the 'velocity field' and relativistic concepts for calculating the 'acceleration field'. These fields are the basic elements required for calculating the total field resulting from the current wave-pair model. Moreover, a modified simpler method using sub models is represented. The sub-models are filaments of either static charges or charges at constant velocity only. Combining these simple sub-models yields the total wave-pair model. The results fully agree with that obtained by solving Maxwell's equations for the discussed problem.

Electric fields in hippocampus due to transcranial focal electrical stimulation via concentric ring electrodes.

PubMed

Besio, Walter G; Hadidi, Ruba; Makeyev, Oleksandr; Luna-Munguía, Hiram; Rocha, Luisa

2011-01-01

As epilepsy affects approximately one percent of the world population, electrical stimulation of brain has recently shown potential as an additive seizure control therapy. In this study we applied focal transcranial electrical stimulation (TFS) on the surface of the skull of rats via concentric ring electrodes. We recorded electric potentials with a bipolar electrode consisting of two stainless steel wires implanted into the left ventral hippocampus. TFS current was gradually increased by 20% starting at 103 μA allowing us to assess the relationship between TFS current and both potentials recorded from the bipolar electrode and the resulting electric field. Generally, increases in TFS current resulted in increases in the electric field. This allows us to estimate what extra-cranial TFS current would be sufficient to cause the activation of neurons in the hippocampus.

Effect of electric field on RbCl quantum pseudodot qubit

NASA Astrophysics Data System (ADS)

Liang, Zhi-Hui; Xiao, Jing-Lin

2018-04-01

By employing the variational method of Pekar type, we study the effects of electric field on RbCl quantum pseudodot (QPD) qubits. Our results confirm that (1) the electron oscillates in the RbCl QPD with a certain period; (2) the electron's probability density is a raising function of electric field; (3) the oscillating frequency is an increasing one of the electric field and the two-dimensional electron gas chemical potential. Two ways are found for prolonging the lifetime of the qubit and suppressing the decoherence in the quantum information field.

Laser-driven electron acceleration in a plasma channel with an additional electric field

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

Cheng, Li-Hong; Xue, Ju-Kui, E-mail: xuejk@nwnu.edu.cn; Liu, Jie, E-mail: liu-jie@iapcm.ac.cn

2016-05-15

We examine the electron acceleration in a two-dimensional plasma channel under the action of a laser field and an additional static electric field. We propose to design an appropriate additional electric field (its direction and location), in order to launch the electron onto an energetic trajectory. We find that the electron acceleration strongly depends on the coupled effects of the laser polarization, the direction, and location of the additional electric field. The additional electric field affects the electron dynamics by changing the dephasing rate. Particularly, a suitably designed additional electric field leads to a considerable energy gain from the lasermore » pulse after the interaction with the additional electric field. The electron energy gain from the laser with the additional electric field can be much higher than that without the additional electric field. This engineering provides a possible means for producing high energetic electrons.« less

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

Electric Fields, Cloud Microphysics, and Reflectivity in Anvils of Florida Thunderstorms

NASA Technical Reports Server (NTRS)

Dye, J. E.; Bateman, M. G.; Christian, H. J.; Defer, E.; Grainger, C. A.; Hall, W. D.; Krider, E. P.; Lewis, S. A.; Mach, D. M.; Merceret, F. J.;

Electric Fields, Cloud Microphysics, and Reflectivity in Anvils of Florida Thunderstorms

NASA Technical Reports Server (NTRS)

Dye, J. E.; Bateman, M. G.; Christian, H. J.; Grainger, C. A.; Hall, W. D.; Krider, E. P.; Lewis, S. A.; Mach, D. M.; Merceret, F. J.; Willett, J. C.;

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.

A high-performance electric field detector for space missions

NASA Astrophysics Data System (ADS)

Badoni, D.; Ammendola, R.; Bertello, I.; Cipollone, P.; Conti, L.; De Santis, C.; Diego, P.; Masciantonio, G.; Picozza, P.; Sparvoli, R.; Ubertini, P.; Vannaroni, G.

2018-04-01

We present the prototype of an Electric Field Detector (EFD) for space applications, that has been developed in the framework of the Chinese-Italian collaboration on the CSES (China Seismo-Electromagnetic Satellite) forthcoming missions. In particular CSES-1 will be placed in orbit in the early 2018. The detector consists of spherical probes designed to be installed at the tips of four booms deployed from a 3-axes stabilized satellite. The instrument has been conceived for space-borne measurements of electromagnetic phenomena such as ionospheric waves, lithosphere-atmosphere-ionosphere-magnetosphere coupling and anthropogenic electromagnetic emissions. The detector allows to measure electric fields in a wide band of frequencies extending from quasi-DC up to about 4 MHz , with a sensitivity of the order of 1 μV / m in the ULF band. With these bandwidth and sensitivity, the described electric field detector represents a very performing and updated device for electric field measurements in space.

Spherical Ethylene/Air Diffusion Flames Subject to Concentric DC Electric Field in Microgravity

NASA Technical Reports Server (NTRS)

Yuan, Z. -G.; Hegde, U.; Faeth, G. M.

2001-01-01

It is well known that microgravity conditions, by eliminating buoyant flow, enable many combustion phenomena to be observed that are not possible to observe at normal gravity. One example is the spherical diffusion flame surrounding a porous spherical burner. The present paper demonstrates that by superimposing a spherical electrical field on such a flame, the flame remains spherical so that we can study the interaction between the electric field and flame in a one-dimensional fashion. Flames are susceptible to electric fields that are much weaker than the breakdown field of the flame gases owing to the presence of ions generated in the high temperature flame reaction zone. These ions and the electric current of the moving ions, in turn, significantly change the distribution of the electric field. Thus, to understand the interplay between the electric field and the flame is challenging. Numerous experimental studies of the effect of electric fields on flames have been reported. Unfortunately, they were all involved in complex geometries of both the flow field and the electric field, which hinders detailed study of the phenomena. In a one-dimensional domain, however, the electric field, the flow field, the thermal field and the chemical species field are all co-linear. Thus the problem is greatly simplified and becomes more tractable.

Method for evaluating human exposure to 60 HZ electric fields

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

Deno, D.W.; Silva, M.

1984-07-01

This paper describes a method that has been successfully used to evaluate human exposure to 60 Hz electric fields. An exposure measuring system that uses an electric field sensor vest and data collection instrumentation is presented. Exposure concepts and activity factors are discussed and experimental data collected with the exposure system are provided. This method can be used to measure exposure to a wide range of electric field with intensities from less than 1 V/m to more than 10 kV/m. Results may be translated to characterize various exposure criteria (time histogram of unperturbed field, surface fields, internal current density, totalmore » body current, etc).« less

High-yield nontoxic gene transfer through conjugation of the CM₁₈-Tat₁₁ chimeric peptide with nanosecond electric pulses.

PubMed

Salomone, Fabrizio; Breton, Marie; Leray, Isabelle; Cardarelli, Francesco; Boccardi, Claudia; Bonhenry, Daniel; Tarek, Mounir; Mir, Lluis M; Beltram, Fabio

2014-07-07

We report a novel nontoxic, high-yield, gene delivery system based on the synergistic use of nanosecond electric pulses (NPs) and nanomolar doses of the recently introduced CM18-Tat11 chimeric peptide (sequence of KWKLFKKIGAVLKVLTTGYGRKKRRQRRR, residues 1-7 of cecropin-A, 2-12 of melittin, and 47-57 of HIV-1 Tat protein). This combined use makes it possible to drastically reduce the required CM18-Tat11 concentration and confines stable nanopore formation to vesicle membranes followed by DNA release, while no detectable perturbation of the plasma membrane is observed. Two different experimental assays are exploited to quantitatively evaluate the details of NPs and CM18-Tat11 cooperation: (i) cytofluorimetric analysis of the integrity of synthetic 1,2-dioleoyl-sn-glycero-3-phosphocholine giant unilamellar vesicles exposed to CM18-Tat11 and NPs and (ii) the in vitro transfection efficiency of a green fluorescent protein-encoding plasmid conjugated to CM18-Tat11 in the presence of NPs. Data support a model in which NPs induce membrane perturbation in the form of transient pores on all cellular membranes, while the peptide stabilizes membrane defects selectively within endosomes. Interestingly, atomistic molecular dynamics simulations show that the latter activity can be specifically attributed to the CM18 module, while Tat11 remains essential for cargo binding and vector subcellular localization. We argue that this result represents a paradigmatic example that can open the way to other targeted delivery protocols.

Electric Mars: A Large Trans-Terminator Electric Potential Drop on Closed Magnetic Field Lines Above Utopia Planitia

NASA Technical Reports Server (NTRS)

Collinson, Glyn; Mitchell, David; Xu, Shaosui; Glocer, Alex; Grebowsky, Joseph; Hara, Takuya; Lillis, Robert; Espley, Jared; Mazelle, Christian; Sauvaud, Jean-Andre

2017-01-01

Abstract Parallel electric fields and their associated electric potential structures play a crucial role inionospheric-magnetospheric interactions at any planet. Although there is abundant evidence that parallel electric fields play key roles in Martian ionospheric outflow and auroral electron acceleration, the fields themselves are challenging to directly measure due to their relatively weak nature. Using measurements by the Solar Wind Electron Analyzer instrument aboard the NASA Mars Atmosphere and Volatile EvolutioN(MAVEN) Mars Scout, we present the discovery and measurement of a substantial (Phi) Mars 7.7 +/-0.6 V) parallel electric potential drop on closed magnetic field lines spanning the terminator from day to night above the great impact basin of Utopia Planitia, a region largely free of crustal magnetic fields. A survey of the previous 26 orbits passing over a range of longitudes revealed similar signatures on seven orbits, with a mean potential drop (Phi) Mars of 10.9 +/- 0.8 V, suggestive that although trans-terminator electric fields of comparable strength are not ubiquitous, they may be common, at least at these northerly latitudes.

Electric-field control of conductance in metal quantum point contacts by electric-double-layer gating

NASA Astrophysics Data System (ADS)

Shibata, K.; Yoshida, K.; Daiguji, K.; Sato, H.; , T., Ii; Hirakawa, K.

2017-10-01

An electric-field control of quantized conductance in metal (gold) quantum point contacts (QPCs) is demonstrated by adopting a liquid-gated electric-double-layer (EDL) transistor geometry. Atomic-scale gold QPCs were fabricated by applying the feedback-controlled electrical break junction method to the gold nanojunction. The electric conductance in gold QPCs shows quantized conductance plateaus and step-wise increase/decrease by the conductance quantum, G0 = 2e2/h, as EDL-gate voltage is swept, demonstrating a modulation of the conductance of gold QPCs by EDL gating. The electric-field control of conductance in metal QPCs may open a way for their application to local charge sensing at room temperature.

Study of electric field distorted by space charges under positive lightning impulse voltage

NASA Astrophysics Data System (ADS)

Wang, Zezhong; Geng, Yinan

2018-03-01

Actually, many insulation problems are related to electric fields. And measuring electric fields is an important research topic of high-voltage engineering. In particular, the electric field distortion caused by space charge is the basis of streamer theory, and thus quantitatively measuring the Poisson electric field caused by space charge is significant to researching the mechanism of air gap discharge. In this paper, we used our photoelectric integrated sensor to measure the electric field distribution in a 1-m rod-plane gap under positive lightning impulse voltage. To verify the reliability of this quantitative measurement, we compared the measured results with calculated results from a numerical simulation. The electric-field time domain waveforms on the axis of the 1-m rod-plane out of the space charge zone were measured with various electrodes. The Poisson electric fields generated by space charge were separated from the Laplace electric field generated by applied voltages, and the amplitudes and variations were measured for various applied voltages and at various locations. This work also supplies the feasible basis for directly measuring strong electric field under high voltage.

High dynamic range electric field sensor for electromagnetic pulse detection.

PubMed

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

2011-08-29

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

Electric-Field-Induced Magnetization Reversal in a Ferromagnet-Multiferroic Heterostructure

NASA Astrophysics Data System (ADS)

Heron, J. T.; Trassin, M.; Ashraf, K.; Gajek, M.; He, Q.; Yang, S. Y.; Nikonov, D. E.; Chu, Y.-H.; Salahuddin, S.; Ramesh, R.

2011-11-01

A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.

Electric-field-induced magnetization reversal in a ferromagnet-multiferroic heterostructure.

PubMed

Heron, J T; Trassin, M; Ashraf, K; Gajek, M; He, Q; Yang, S Y; Nikonov, D E; Chu, Y-H; Salahuddin, S; Ramesh, R

2011-11-18

A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.

Geometric properties-dependent neural synchrony modulated by extracellular subthreshold electric field

NASA Astrophysics Data System (ADS)

Wei, Xile; Si, Kaili; Yi, Guosheng; Wang, Jiang; Lu, Meili

2016-07-01

In this paper, we use a reduced two-compartment neuron model to investigate the interaction between extracellular subthreshold electric field and synchrony in small world networks. It is observed that network synchronization is closely related to the strength of electric field and geometric properties of the two-compartment model. Specifically, increasing the electric field induces a gradual improvement in network synchrony, while increasing the geometric factor results in an abrupt decrease in synchronization of network. In addition, increasing electric field can make the network become synchronous from asynchronous when the geometric parameter is set to a given value. Furthermore, it is demonstrated that network synchrony can also be affected by the firing frequency and dynamical bifurcation feature of single neuron. These results highlight the effect of weak field on network synchrony from the view of biophysical model, which may contribute to further understanding the effect of electric field on network activity.

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'…

Penetration of Nonstationary Ionospheric Electric Fields into Lower Atmospheric Layers in the Global Electric Circuit Model

NASA Astrophysics Data System (ADS)

Morozov, V. N.

2018-01-01

The problem of the penetration of nonstationary ionospheric electric fields into the lower atmospheric layers is considered based on the model of the global electric circuit in the Earth's atmosphere. For the equation of the electric field potential, a solution that takes into account exponential variation in the electrical conductivity with height has been obtained. Analysis of the solution made it possible to reveal three cases of the dependence of the solution on height. The first case (the case of high frequencies) corresponds to the Coulomb approximation, when the electrical conductivity of the atmosphere can be neglected. In the case of low frequencies (when the frequency of changes in the ionosphere potential is less than the quantity reciprocal to the time of electric relaxation of the atmosphere), a quasi-stationary regime, in which the variation in the electric potential of the atmosphere is determined by the electric conduction currents, occurs. In the third case, due to the increase in the electrical conductivity of the atmosphere, two spherical regions appear: with the Coulomb approximation in the lower region and conduction currents in the upper one. For these three cases, formulas for estimating the electric field strength near the Earth's surface have been obtained.

Electric field distribution and current emission in a miniaturized geometrical diode

NASA Astrophysics Data System (ADS)

Lin, Jinpu; Wong, Patrick Y.; Yang, Penglu; Lau, Y. Y.; Tang, W.; Zhang, Peng

2017-06-01

We study the electric field distribution and current emission in a miniaturized geometrical diode. Using Schwarz-Christoffel transformation, we calculate exactly the electric field inside a finite vacuum cathode-anode (A-K) gap with a single trapezoid protrusion on one of the electrode surfaces. It is found that there is a strong field enhancement on both electrodes near the protrusion, when the ratio of the A-K gap distance to the protrusion height d /h <2. The calculations are spot checked against COMSOL simulations. We calculate the effective field enhancement factor for the field emission current, by integrating the local Fowler-Nordheim current density along the electrode surfaces. We systematically examine the electric field enhancement and the current rectification of the miniaturized geometrical diode for various geometric dimensions and applied electric fields.

Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

NASA Astrophysics Data System (ADS)

Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

2013-11-01

High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

New Effects of the Interaction of Electric and Gravitational Fields

NASA Astrophysics Data System (ADS)

Krechet, V. G.; Oshurko, V. B.; Ivanova, S. D.

2018-06-01

The properties of stationary distributions of self-gravitating electric fields are considered within the framework of GRT with the presence of a vortex component in the gravitational field taken into account. It is shown that under the indicated conditions, cylindrically symmetric configurations of the gravitational field and electric fields can lead to the formation of "wormholes" and other remarkable effects.

Transmission of the convection electric field to the inner magnetosphere

NASA Astrophysics Data System (ADS)

Kikuchi, T.

2003-12-01

Low latitude magnetometer observations revealed that the partial ring current started to develop within several minutes after the onset of growth of the polar cap potential (PCP), and decayed simultaneously with the decrease in the PCP (Hashimoto, Kikuchi and Ebihara., JGR 2002). The magnetometer observations also indicated that the DP2 ionospheric currents were driven by the convection electric field at mid latitudes as well as at high latitudes. These observational facts suggest that the ionospheric electric field plays a crucial role in driving the convection in the inner magnetosphere. A probable model for the electric field transmission should explain both the convection in the inner magnetosphere and the ionospheric currents at mid latitudes. The instantaneous transmission of the ionospheric electric field and currents from the polar ionosphere to the equator was explained by Kikuchi and Araki (JATP 1979) based on the TM0 mode in the Earth-ionosphere waveguide. In this paper, we attempt to explain the transmission of the convection electric field to the inner magnetosphere by applying the Earth-ionosphere waveguide. However, two issues remained unresolved in the paper by Kikuchi and Araki (1979). One is the excitation of the TM0 mode in the Earth-ionosphere waveguide, and the other is the attenuation under the nighttime ionospheric condition. To examine the excitation of the TM0 mode, we couple the Earth-ionosphere waveguide (transmission line) with a magnetospheric transmission line composed of a pair of field-aligned currents (e.g., R1 FACs). A fraction of the electromagnetic energy carried from the magnetosphere is transmitted into the Earth-ionosphere waveguide, although substantial energy is dissipated in the polar ionosphere intervening between the two transmission lines. The transmitted electromagnetic energy excites the TM0 mode in the Earth-ionosphere waveguide. We then evaluate the attenuation of the TM0 mode by calculating upward flow of energy

Convection Electric Field Observations by THEMIS and the Van Allen Probes

NASA Astrophysics Data System (ADS)

Califf, S.; Li, X.; Bonnell, J. W.; Wygant, J. R.; Malaspina, D.; Hartinger, M.; Thaller, S. A.

2013-12-01

We present direct electric field measurements made by THEMIS and the Van Allen Probes in the inner magnetosphere, focusing on the large-scale, near-DC convection electric field. The convection electric field drives plasma Earthward from the tail into the inner magnetosphere, playing a critical role in forming the ring current. Although it is normally shielded deep inside the magnetosphere, during storm times this large-scale electric field can penetrate to low L values (L < 3), eroding the plasmasphere and also providing a mechanism for ~100 keV electron injection into the slot region and inner radiation belt. The relationship of the convection electric field with the plasmasphere is also important for understanding the dynamic outer radiation belt, as the plasmapause boundary has been strongly correlated with the dynamic variation of the outer radiation belt electrons.

Electric fields in the plasma sheet and plasma sheet boundary layer

NASA Technical Reports Server (NTRS)

Pedersen, A.; Knott, K.; Cattell, C. A.; Mozer, F. S.; Falthammar, C.-G.; Lindqvist, P.-A.; Manka, R. H.

1985-01-01

Results obtained by Forbes et al. (1981) on the basis of time delay measurements between ISEE 1 and ISEE 2 imply that the plasma flow and the boundary contracting velocity were nearly the same, whereas the expanding boundary velocity was not accompanied by any significant plasma sheet plasma motion. In the present study, this observation is discussed in conjunction with electric field data. The study is based on electric field data from the spherical double probe experiment on ISEE 1. Electric field data from GEOS 2 are used to some extent to monitor the electric fields near the geostationary orbit during the considered eve nts. Electric field data during CDAW 6 events are discussed, taking into account positions of ISEE 1/ISEE 2 and GEOS 2; March 22, 0600-1300 UT; and March 22, UT; and March 31, 1400-2400 UT.

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.

Response of ionospheric electric fields at mid-low latitudes during sudden commencements

NASA Astrophysics Data System (ADS)

Takahashi, N.; Kasaba, Y.; Shinbori, A.; Nishimura, Y.; Kikuchi, T.; Ebihara, Y.; Nagatsuma, T.

2015-06-01

Using in situ observations from the Republic of China Satellite-1 spacecraft, we investigated the time response and local time dependence of the ionospheric electric field at mid-low latitudes associated with geomagnetic sudden commencements (SCs) that occurred from 1999 to 2004. We found that the ionospheric electric field variation associated with SCs instantaneously responds to the preliminary impulse (PI) signature on the ground regardless of spacecraft local time. Our statistical analysis also supports the global instant transmission of electric field from the polar region. In contrast, the peak time detected in the ionospheric electric field is earlier than that of the equatorial geomagnetic field (~20 s before in the PI phase). Based on the ground-ionosphere waveguide model, this time lag can be attributed to the latitudinal difference of ionospheric conductivity. However, the local time distribution of the initial excursion of ionospheric electric field shows that dusk-to-dawn ionospheric electric fields develop during the PI phase. Moreover, the westward electric field in the ionosphere, which produces the preliminary reverse impulse of the geomagnetic field on the dayside feature, appears at 18-22 h LT where the ionospheric conductivity beyond the duskside terminator (18 h LT) is lower than on the dayside. The result of a magnetohydrodynamic simulation for an ideal SC shows that the electric potential distribution is asymmetric with respect to the noon-midnight meridian. This produces the local time distribution of ionospheric electric fields similar to the observed result, which can be explained by the divergence of the Hall current under nonuniform ionospheric conductivity.