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Sample records for field induced enhancement

  1. Field enhancement induced laser ablation

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures....... The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron and atomic force microscopy. Thickness...

  2. Field-induced cluster spin glass and inverse symmetry breaking enhanced by frustration

    Science.gov (United States)

    Schmidt, M.; Zimmer, F. M.; Magalhaes, S. G.

    2018-03-01

    We consider a cluster disordered model to study the interplay between short- and long-range interactions in geometrically frustrated spin systems under an external magnetic field (h). In our approach, the intercluster long-range disorder (J) is analytically treated to get an effective cluster model that is computed exactly. The clusters follow a checkerboard lattice with first-neighbor (J1) and second-neighbor (J2) interactions. We find a reentrant transition from the cluster spin-glass (CSG) state to a paramagnetic (PM) phase as the temperature decreases for a certain range of h. This inverse symmetry breaking (ISB) appears as a consequence of both quenched disorder with frustration and h, that introduce a CSG state with higher entropy than the polarized PM phase. The competitive scenario introduced by antiferromagnetic (AF) short-range interactions increases the CSG state entropy, leading to continuous ISB transitions and enhancing the ISB regions, mainly in the geometrically frustrated case (J1 =J2). Remarkably, when strong AF intracluster couplings are present, field-induced CSG phases can be found. These CSG regions are strongly related to the magnetization plateaus observed in this cluster disordered system. In fact, it is found that each field-induced magnetization jump brings a CSG region. We notice that geometrical frustration, as well as cluster size, play an important role in the magnetization plateaus and, therefore, are also relevant in the field-induced glassy states. Our findings suggest that competing interactions support ISB and field-induced CSG phases in disordered cluster systems under an external magnetic field.

  3. Enhanced electrocatalytic CO2 reduction via field-induced reagent concentration

    Science.gov (United States)

    Liu, Min; Pang, Yuanjie; Zhang, Bo; de Luna, Phil; Voznyy, Oleksandr; Xu, Jixian; Zheng, Xueli; Dinh, Cao Thang; Fan, Fengjia; Cao, Changhong; de Arquer, F. Pelayo García; Safaei, Tina Saberi; Mepham, Adam; Klinkova, Anna; Kumacheva, Eugenia; Filleter, Tobin; Sinton, David; Kelley, Shana O.; Sargent, Edward H.

    2016-09-01

    Electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the reaction suffers from slow kinetics owing to the low local concentration of CO2 surrounding typical CO2 reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO2 adsorption, but this comes at the cost of increased hydrogen (H2) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO2 close to the active CO2 reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO2 reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxide-derived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.

  4. Field enhancement of multiphoton induced luminescence processes in ZnO nanorods

    Science.gov (United States)

    Hyyti, Janne; Perestjuk, Marko; Mahler, Felix; Grunwald, Rüdiger; Güell, Frank; Gray, Ciarán; McGlynn, Enda; Steinmeyer, Günter

    2018-03-01

    The near-ultraviolet photoluminescence of ZnO nanorods induced by multiphoton absorption of unamplified Ti:sapphire pulses is investigated. Power dependence measurements have been conducted with an adaptation of the ultrashort pulse characterization method of interferometric frequency-resolved optical gating. These measurements enable the separation of second harmonic and photoluminescence bands due to their distinct coherence properties. A detailed analysis yields fractional power dependence exponents in the range of 3–4, indicating the presence of multiple nonlinear processes. The range in measured exponents is attributed to differences in local field enhancement, which is supported by independent photoluminescence and structural measurements. Simulations based on Keldysh theory suggest contributions by three- and four-photon absorption as well as avalanche ionization in agreement with experimental findings.

  5. BEMER Electromagnetic Field Therapy Reduces Cancer Cell Radioresistance by Enhanced ROS Formation and Induced DNA Damage.

    Science.gov (United States)

    Storch, Katja; Dickreuter, Ellen; Artati, Anna; Adamski, Jerzy; Cordes, Nils

    2016-01-01

    Each year more than 450,000 Germans are expected to be diagnosed with cancer subsequently receiving standard multimodal therapies including surgery, chemotherapy and radiotherapy. On top, molecular-targeted agents are increasingly administered. Owing to intrinsic and acquired resistance to these therapeutic approaches, both the better molecular understanding of tumor biology and the consideration of alternative and complementary therapeutic support are warranted and open up broader and novel possibilities for therapy personalization. Particularly the latter is underpinned by the increasing utilization of non-invasive complementary and alternative medicine by the population. One investigated approach is the application of low-dose electromagnetic fields (EMF) to modulate cellular processes. A particular system is the BEMER therapy as a Physical Vascular Therapy for which a normalization of the microcirculation has been demonstrated by a low-frequency, pulsed EMF pattern. Open remains whether this EMF pattern impacts on cancer cell survival upon treatment with radiotherapy, chemotherapy and the molecular-targeted agent Cetuximab inhibiting the epidermal growth factor receptor. Using more physiological, three-dimensional, matrix-based cell culture models and cancer cell lines originating from lung, head and neck, colorectal and pancreas, we show significant changes in distinct intermediates of the glycolysis and tricarboxylic acid cycle pathways and enhanced cancer cell radiosensitization associated with increased DNA double strand break numbers and higher levels of reactive oxygen species upon BEMER treatment relative to controls. Intriguingly, exposure of cells to the BEMER EMF pattern failed to result in sensitization to chemotherapy and Cetuximab. Further studies are necessary to better understand the mechanisms underlying the cellular alterations induced by the BEMER EMF pattern and to clarify the application areas for human disease.

  6. Electric-field-induced strong enhancement of electroluminescence in multilayer molybdenum disulfide

    Science.gov (United States)

    Li, Dehui; Cheng, Rui; Zhou, Hailong; Wang, Chen; Yin, Anxiang; Chen, Yu; Weiss, Nathan O.; Huang, Yu; Duan, Xiangfeng

    2015-07-01

    The layered transition metal dichalcogenides have attracted considerable interest for their unique electronic and optical properties. While the monolayer MoS2 exhibits a direct bandgap, the multilayer MoS2 is an indirect bandgap semiconductor and generally optically inactive. Here we report electric-field-induced strong electroluminescence in multilayer MoS2. We show that GaN-Al2O3-MoS2 and GaN-Al2O3-MoS2-Al2O3-graphene vertical heterojunctions can be created with excellent rectification behaviour. Electroluminescence studies demonstrate prominent direct bandgap excitonic emission in multilayer MoS2 over the entire vertical junction area. Importantly, the electroluminescence efficiency observed in multilayer MoS2 is comparable to or higher than that in monolayers. This strong electroluminescence can be attributed to electric-field-induced carrier redistribution from the lowest energy points (indirect bandgap) to higher energy points (direct bandgap) in k-space. The electric-field-induced electroluminescence is general for other layered materials including WSe2 and can open up a new pathway towards transition metal dichalcogenide-based optoelectronic devices.

  7. Magnetic field induced polarization enhancement in monolayers of tungsten dichalcogenides: effects of temperature

    Science.gov (United States)

    Smoleński, T.; Kazimierczuk, T.; Goryca, M.; Molas, M. R.; Nogajewski, K.; Faugeras, C.; Potemski, M.; Kossacki, P.

    2018-01-01

    Optical orientation of localized/bound excitons is shown to be effectively enhanced by the application of magnetic fields as low as 20 mT in monolayer WS2. At low temperatures, the evolution of the polarization degree of different emission lines of monolayer WS2 with increasing magnetic fields is analyzed and compared to similar results obtained on a WSe2 monolayer. We study the temperature dependence of this effect up to T=60 K for both materials, focusing on the dynamics of the valley pseudospin relaxation. A rate equation model is used to analyze our data and from the analysis of the width of the polarization dip in magnetic field we conclude that the competition between the dark exciton pseudospin relaxation and the decay of the dark exciton population into the localized states are rather different in these two materials which are representative of the two extreme cases for the ratio of relaxation rate and depolarization rate.

  8. Terahertz field induced electromigration

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Zalkovskij, Maksim; Iwaszczuk, Krzysztof

    We report the first observation of THz-field-induced electromigration in sub-wavelength metallic gap structures after exposure to intense single-cycle, sub-picosecond electric field transients of amplitude up to 400 kV/cm....

  9. Optical image contrast enhancement in near-field optics induced by water condensation.

    Science.gov (United States)

    Douas, Maysoun; Marqués, Manuel I; Serena, Pedro A

    2013-12-01

    In surface science, water adsorption on hydrophilic samples is usually invoked, addressing their nanoscale experimental effects in scanning probe microscopy, especially when water condensates between tip and sample. Here we study by means of a numerical hybrid method the effect of water bridge formation in near field imaging. We show how this nanometric water neck plays an important role not only in the optical image, producing a high contrast at hydrophilic patches, but also in the tip-sample distance control. This work contributes with a new methodology able to retrieve the original application of SNOM, using it as an instrument to study the optical properties of matter overcoming the diffraction limit. It extends the application of SNOM to study the hydrophilic character of polymeric and biological samples, taking advantage of ubiquitous effect of humidity when operating in ambient condition. © 2013 Elsevier B.V. All rights reserved.

  10. Sensitivity enhancement in near-field photothermal-lens detection in capillary electrophoresis using laser-induced online precipitation.

    Science.gov (United States)

    Nedosekin, Dmitry A; Faubel, Werner; Proskurnin, Mikhail A; Pyell, Ute

    2011-11-01

    This paper reports simultaneous photoinduced precipitation-based online preconcentration of target analytes at the inner walls in capillary zone electrophoresis (CZE) and surface-enhanced near-field crossed-beam photothermal-lens detection of the preconcentrated analytes. A simple technique using online readjustment of the optical scheme of the thermal-lens detector in the course of the separation for gaining optimum sensitivity for both water-soluble and precipitated analytes is proposed. It provides a considerable decrease in the limits of detection (LOD) with good concordance with the previously developed theoretical approach to this combination (D. A. Nedosekin, W. Faubel, M. A. Proskurnin, and U. Pyell, Talanta, 78, 682-690 (2009)). As a result, an enhancement of more than an order of magnitude in the limit of detection of the photoactive 4-aminoazobenzene compared to conventional thermal-lens detection in CZE is achieved while retaining very good sensitivity for unabsorbed analyte (Mordant Yellow 7). The application of the thermal-lens detector to the investigation of laser-induced reactions in flow in capillaries is discussed.

  11. Enhanced crystal-field splitting and orbital-selective coherence induced by strong correlations in V2O3

    Science.gov (United States)

    Poteryaev, Alexander I.; Tomczak, Jan M.; Biermann, Silke; Georges, Antoine; Lichtenstein, Alexander I.; Rubtsov, Alexey N.; Saha-Dasgupta, Tanusri; Andersen, Ole K.

    2007-08-01

    We present a study of the paramagnetic metallic and insulating phases of vanadium sesquioxide by means of the Nth order muffin-tin orbital implementation of density functional theory combined with dynamical mean-field theory. The transition is shown to be driven by a correlation-induced enhancement of the crystal-field splitting within the t2g manifold, which results in a suppression of the hybridization between the a1g and egπ bands. We discuss the changes in the effective quasiparticle band structure caused by the correlations and the corresponding self-energies. At temperatures of about 400K , we find the a1g orbital displays coherent quasiparticle behavior, while a large imaginary part of the self-energy and broad features in the spectral function indicate that the egπ orbitals are still far above their coherence temperature. The local spectral functions are in excellent agreement with recent bulk sensitive photoemission data. Finally, we also make a prediction for angle-resolved photoemission experiments by calculating momentum-resolved spectral functions.

  12. Plasmon field enhancement oscillations induced by strain-mediated coupling between a quantum dot and mechanical oscillator.

    Science.gov (United States)

    He, Yong

    2017-06-23

    We utilize the surface plasmon field of a metal nanoparticle (MNP) to show strain-mediated coupling in a quantum dot-mechanical resonator hybrid system including a quantum dot (QD) embedded within a conical nanowire (NW) and a MNP in the presence of an external field. Based on the numerical solutions of the master equation, we find that a slow oscillation, originating from the strain-mediated coupling between the QD and the NW, appears in the time evolution of the plasmon field enhancement. The results show that the period (about [Formula: see text]) of the slow oscillation is equal to that of the mechanical resonator of NW, which suggests that the time-resolved measurement of the plasmon field enhancement can be easily achieved based on the current experimental conditions. Its amplitude increases with the increasing strain-mediated coupling strength, and under certain conditions there is a linear relationship between them. The slow oscillation of the plasmon field enhancement provides valuable tools for measurements of the mechanical frequency and the strain-mediated coupling strength.

  13. Plasmon field enhancement oscillations induced by strain-mediated coupling between a quantum dot and mechanical oscillator

    Science.gov (United States)

    He, Yong

    2017-06-01

    We utilize the surface plasmon field of a metal nanoparticle (MNP) to show strain-mediated coupling in a quantum dot-mechanical resonator hybrid system including a quantum dot (QD) embedded within a conical nanowire (NW) and a MNP in the presence of an external field. Based on the numerical solutions of the master equation, we find that a slow oscillation, originating from the strain-mediated coupling between the QD and the NW, appears in the time evolution of the plasmon field enhancement. The results show that the period (about 2 μ s) of the slow oscillation is equal to that of the mechanical resonator of NW, which suggests that the time-resolved measurement of the plasmon field enhancement can be easily achieved based on the current experimental conditions. Its amplitude increases with the increasing strain-mediated coupling strength, and under certain conditions there is a linear relationship between them. The slow oscillation of the plasmon field enhancement provides valuable tools for measurements of the mechanical frequency and the strain-mediated coupling strength.

  14. Subchronic Oral Bromocriptine Methanesulfonate Enhances Open Field Novelty-Induced Behavior and Spatial Memory in Male Swiss Albino Mice

    Directory of Open Access Journals (Sweden)

    Olakunle James Onaolapo

    2013-01-01

    Full Text Available This study set out to assess the neurobehavioral effects of subchronic, oral bromocriptine methanesulfonate using the open field and the Y-maze in healthy male mice. Sixty adult Swiss albino mice were assigned into three groups. Controls received normal saline, while test groups received bromocriptine methanesulfonate at 2.5 and 5 mg/kg/day, respectively, for a period of 21 days. Neurobehavioral tests were carried out on days 1 and 21 after administration. Open field assessment on day 1 after administration revealed significant increase in grooming at 2.5 and 5 mg/kg, while horizontal and vertical locomotion showed no significant changes. Day 1 also showed no significant changes in Y-maze alternation. On day 21, horizontal locomotion, rearing, and grooming were increased significantly at 2.5 and 5 mg/kg doses after administration; also, spatial memory was significantly enhanced at 2.5 mg/kg. In conclusion, the study demonstrates the ability of oral bromocriptine to affect neurobehavior in normal mice. It also suggests that there is a cumulative effect of oral bromocriptine on the behaviors studied with more changes being seen after subchronic administration rather than after a single oral dose.

  15. Enhanced Dielectronic Recombination in Crossed Electric and Magnetic Fields

    International Nuclear Information System (INIS)

    Robicheaux, F.; Pindzola, M.S.

    1997-01-01

    The dependence of the dielectronic recombination cross section on crossed electric and magnetic fields is described. The enhancement of this cross section due to a static electric field is further increased when a magnetic field is added perpendicular to the electric field. Calculation of this field induced enhancement is presented for a realistic atomic model, and the mechanism for the enhancement is discussed. copyright 1997 The American Physical Society

  16. Static electric field enhancement in nanoscale structures

    Energy Technology Data Exchange (ETDEWEB)

    Lepetit, Bruno, E-mail: bruno.lepetit@irsamc.ups-tlse.fr; Lemoine, Didier, E-mail: didier.lemoine@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Márquez-Mijares, Maykel, E-mail: mmarquez@instec.cu [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Avenida Salvador Allende 1110, Quinta de los Molinos, La Habana (Cuba)

    2016-08-28

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  17. Enhancement of X-ray Induced Apoptosis by Mobile Phone-Like Radio-Frequency Electromagnetic Fields in Mouse Spermatocyte-Derived Cells.

    Science.gov (United States)

    Zhang, Ke-Ying; Xu, Hui; Du, Le; Xing, Jun-Ling; Zhang, Bin; Bai, Qiang-Shan; Xu, Yu-Qiao; Zhou, Yong-Chun; Zhang, Jun-Ping; Zhou, Yan; Ding, Gui-Rong

    2017-06-07

    To explore the combined effects of environmental radio-frequency (RF) field and X-ray, mouse spermatocyte-derived (GC-1) cells were exposed to 1950 MHz RF field at specific absorption rate (SAR) of 3 W/kg for 24 h combined with or without X-ray irradiation at 6 Gy. After treatment, the cell proliferation level was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) Assay and 5-Bromo-2-deoxy Uridine (BrdU) enzyme linked immunosorbent (ELISA) Assay. The apoptosis level was detected by annexin V flow cytometry assay, transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) Assay and Caspase-3 Activity Assay. It was found that the proliferation and apoptosis level did not change in GC-1 cells after RF exposure alone. However, compared with the X-ray group, the proliferation level significantly decreased and the apoptotic rate significantly increased in the RF+X-ray group. Moreover, a significant decrease in Bcl-2 protein expression and increase in Bax protein expression were observed. The findings suggested that RF exposure at SAR of 3 W/kg did not affect apoptosis and proliferation in GC-1 cells by itself, but that it did enhance the effects of X-ray induced proliferation inhibition and apoptosis, in which B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) might be involved.

  18. Output Enhancement in the Transfer-Field Machine Using Rotor ...

    African Journals Online (AJOL)

    Output Enhancement in the Transfer-Field Machine Using Rotor Circuit Induced Currents. ... The output of a plain transfer-field machine would be much less than that of a conventional machine of comparable size and dimensions. The use of ... The same effects have their parallel for the asynchronous mode of operation.

  19. Electric Field Induce Blue Shift and Intensity Enhancement in 2D Exciplex Organic Light Emitting Diodes; Controlling Electron-Hole Separation.

    Science.gov (United States)

    Al Attar, Hameed A; Monkman, Andy P

    2016-09-01

    A simple but novel method is designed to study the characteristics of the exciplex state pinned at a donor-acceptor abrupt interface and the effect an external electric field has on these excited states. The reverse Onsager process, where the field induces blue-shifted emission and increases the efficiency of the exciplex emission as the e-h separation reduces, is discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Hyperthermia generated with ferucarbotran (Resovist®) in an alternating magnetic field enhances cisplatin-induced apoptosis of cultured human oral cancer cells.

    Science.gov (United States)

    Sato, Itaru; Umemura, Masanari; Mitsudo, Kenji; Kioi, Mitomu; Nakashima, Hideyuki; Iwai, Toshinori; Feng, Xianfeng; Oda, Kayoko; Miyajima, Akiyoshi; Makino, Ayako; Iwai, Maki; Fujita, Takayuki; Yokoyama, Utako; Okumura, Satoshi; Sato, Motohiko; Eguchi, Haruki; Tohnai, Iwai; Ishikawa, Yoshihiro

    2014-05-01

    Hyperthermia is a promising anti-cancer treatment in which the tissue temperature is increased to 42-45 °C, and which is often used in combination with chemotherapy or radiation therapy. Our aim in the present work was to examine the feasibility of combination therapy for oral cancer with cisplatin and hyperthermia generated with ferucarbotran (Resovist(®); superparamagnetic iron oxide) in an alternating magnetic field (AMF). First, we established that administration of ferucarbotran at the approved dosage for magnetic resonance imaging provides an iron concentration sufficient to increase the temperature to 42.5 °C upon exposure to AMF. Then, we examined the effect of cisplatin combined with ferucarbotran/AMF-induced hyperthermia on cultured human oral cancer cells (HSC-3 and OSC-19). Cisplatin alone induced apoptosis of cancer cells in a dose-dependent manner, as is well known. However, the combination of cisplatin with ferucarbotran/AMF was significantly more effective than cisplatin alone. This result suggests that it might be possible to reduce the clinically effective dosage of cisplatin by administering it in combination with ferucarbotran/AMF-induced hyperthermia, thereby potentially reducing the incidence of serious cisplatin-related side effects. Further work seems justified to evaluate simultaneous thermo-chemotherapy as a new approach to anticancer therapy.

  1. Enhanced THz emission from c-plane InxGa1-xN due to piezoelectric field-induced electron transport

    Science.gov (United States)

    Woodward, Nathaniel; Gallinat, C.; Rodak, L. E.; Metcalfe, G. D.; Shen, H.; Wraback, M.

    2012-05-01

    Enhanced terahertz emission from coherently strained InxGa1-xN epilayers on GaN is observed, which exceeds or is comparable to bulk InAs emission at pump wavelengths of 400 nm or 800 nm, respectively. The inverted terahertz waveform from the InxGa1-xN/GaN heterostructure indicates that the dominant terahertz generation mechanism is electron acceleration toward the InxGa1-xN surface in an internal electric field primarily associated with piezoelectric polarization charge at the heterointerface, rather than diffusive transport away from the surface typically observed in bulk semiconductors. The persistence of the inverted waveform for 266 nm excitation provides evidence of ultrafast electron relaxation via LO phonon emission.

  2. Topology Optimized Nanostrips for Electric Field Enhancements

    DEFF Research Database (Denmark)

    Vester-Petersen, Joakim; Christiansen, Rasmus E.; Julsgaard, Brian

    energy photons are converted to higher energy photons able to bridge the band gap energy and contribute the energy generation. The upconversion process in erbium is inefficient under the natural solar irradiation, and without any electric field enhancements of the incident light, the process...

  3. Numerical Study of Electric Field Enhanced Combustion

    KAUST Repository

    Han, Jie

    2016-12-26

    Electric fields can be used to change and control flame properties, for example changing flame speed, enhancing flame stability, or reducing pollutant emission. The ions generated in flames are believed to play the primary role. Although experiments have been carried out to study electric field enhanced combustion, they are not sufficient to explain how the ions in a flame are affected by an electric field. It is therefore necessary to investigate the problem through numerical simulations. In the present work, the electric structure of stabilized CH4/air premixed flames at atmospheric pressure within a direct current field is studied using numerical simulations. This study consists of three parts. First, the transport equations are derived from the Boltzmann kinetic equation for each individual species. Second, a general method for computing the diffusivity and mobility of ions in a gas mixture is introduced. Third, the mechanisms for neutral and charged species are improved to give better predictions of the concentrations of charged species, based on experimental data. Following from this, comprehensive numerical results are presented, including the concentrations and fluxes of charged species, the distributions of the electric field and electric potential, and the electric current-voltage relation. Two new concepts introduced with the numerical results are the plasma sheath and dead zone in the premixed flame. A reactive plasma sheath and a Boltzmann relation sheath are discovered in the region near the electrodes. The plasma sheath penetrates into the flame gas when a voltage is applied, and penetrating further if the voltage is higher. The zone outside the region of sheath penetration is defined as the dead zone. With the two concepts, analytical solutions for the electric field, electric potential and current-voltage curve are derived. The solutions directly describe the electric structure of a premixed flame subject to a DC field. These analytical solutions

  4. Orientation field estimation for latent fingerprint enhancement.

    Science.gov (United States)

    Feng, Jianjiang; Zhou, Jie; Jain, Anil K

    2013-04-01

    Identifying latent fingerprints is of vital importance for law enforcement agencies to apprehend criminals and terrorists. Compared to live-scan and inked fingerprints, the image quality of latent fingerprints is much lower, with complex image background, unclear ridge structure, and even overlapping patterns. A robust orientation field estimation algorithm is indispensable for enhancing and recognizing poor quality latents. However, conventional orientation field estimation algorithms, which can satisfactorily process most live-scan and inked fingerprints, do not provide acceptable results for most latents. We believe that a major limitation of conventional algorithms is that they do not utilize prior knowledge of the ridge structure in fingerprints. Inspired by spelling correction techniques in natural language processing, we propose a novel fingerprint orientation field estimation algorithm based on prior knowledge of fingerprint structure. We represent prior knowledge of fingerprints using a dictionary of reference orientation patches. which is constructed using a set of true orientation fields, and the compatibility constraint between neighboring orientation patches. Orientation field estimation for latents is posed as an energy minimization problem, which is solved by loopy belief propagation. Experimental results on the challenging NIST SD27 latent fingerprint database and an overlapped latent fingerprint database demonstrate the advantages of the proposed orientation field estimation algorithm over conventional algorithms.

  5. Electric field-induced hole injection-enhanced photoluminescence in a N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine-based emitter

    International Nuclear Information System (INIS)

    Xu-Xie Hui-Na; Li Wen-Bin; Peng Huan; He Yun; Yu Hao-Miao; Hou Xiao-Yuan

    2014-01-01

    Non-monotonic, asymmetrical electric field dependence of photoluminescence (PL) intensity is observed in a monolayer sample of tris-(8-hydroxyquinoline) aluminum (AlQ) doped N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine (TPD). A possible model is proposed: the charge separation from the dissociated photoexcited excitons causes energy band bending in the organic films and improves the hole injection from the electrode, which brings about the extra fluorescence. This mechanism is further verified by a series of experiments using a series of samples, variously featuring symmetrical electrodes, block layers, and hosts with lower hole mobilities. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Induced resistance: an enhancement of basal resistance?

    NARCIS (Netherlands)

    Vos, M. de; Robben, C.; Pelt, J.A. van; Loon, L.C. van; Pieterse, C.M.J.

    2002-01-01

    Upon primary pathogen attack, plants activate resistance mechanisms at the site of infection. Besides this so-called basal resistance, plants have also the ability to enhance their defensive capacity against future pathogen attack. There are at least two types of biologically induced resistance.

  7. Vanillin-molecularly targeted extraction of stir bar based on magnetic field induced self-assembly of multifunctional Fe3O4@Polyaniline nanoparticles for detection of vanilla-flavor enhancers in infant milk powders.

    Science.gov (United States)

    Wu, Jinhua; Yang, Zaiyue; Chen, Ning; Zhu, Wanying; Hong, Junli; Huang, Changgao; Zhou, Xuemin

    2015-03-15

    A molecularly imprinted stir bar was constructed based on Fe3O4@Polyaniline nanoparticles with magnetic field-induced self-assembly process. The monomer, methacrylic acid, was pre-assembled into the pre-polymers with vanillin as template by the formation of hydrogen bonds. After that, the magnetic complexes were generated by the hydrogen bonding, the hydrophobic and π-π interaction between the pre-polymers and Fe3O4@Polyaniline. The complexes were adsorbed on the surface of magnetic stir bar under the magnetic induction, and the coating of vanillin-molecularly imprinted polymers was generated by the one-step copolymerization basing on the cross linking of ethylene glycol dimethacrylate. The molecular imprinting stir bar showed superior selectivity and fast binding kinetics for vanillin, and was used for the enrichment of vanilla-flavor enhancers (vanillin, ethyl maltol and methyl vanillin) in infant milk powders. The results measured by HPLC-UV exhibited good linear ranges of 0.01-100, 0.02-100 and 0.03-100μgmL(-1) with the limit of detection of 2.5-10.0ngmL(-1), and the recoveries were 94.7-98.9%, 82.1-96.7% and 84.5-93.2% with RSD<7.2% for the three enhancers, respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Electrically induced magnetic fields; a consistent approach

    Science.gov (United States)

    Batell, Brian; Ferstl, Andrew

    2003-09-01

    Electromagnetic radiation exists because changing magnetic fields induce changing electric fields and vice versa. This fact often appears inconsistent with the way some physics textbooks solve particular problems using Faraday's law. These types of problems often ask students to find the induced electric field given a current that does not vary linearly with time. A typical example involves a long solenoid carrying a sinusoidal current. This problem is usually solved as an example or assigned as a homework exercise. The solution offered by many textbooks uses the approximation that the induced, changing electric field produces a negligible magnetic field, which is only valid at low frequencies. If this approximation is not explicitly acknowledged, then the solution appears inconsistent with the description of electromagnetic radiation. In other cases, when the problem is solved without this approximation, the electric and magnetic fields are derived from the vector potential. We present a detailed calculation of the electric and magnetic fields inside and outside the long solenoid without using the vector potential. We then offer a comparison of our solution and a solution given in an introductory textbook.

  9. Fast Magnetic Field-Enhanced Linear Colloidal Agglutination Immunoassay.

    Science.gov (United States)

    Daynès, Aurélien; Temurok, Nevzat; Gineys, Jean-Philippe; Cauet, Gilles; Nerin, Philippe; Baudry, Jean; Bibette, Jérôme

    2015-08-04

    We present the principle of a fast magnetic field enhanced colloidal agglutination assay, which is based on the acceleration of the recognition rate between ligands and receptors induced by magnetic forces. By applying a homogeneous magnetic field of 20 mT for only 7 s, we detect CRP (C-reactive protein) in human serum at a concentration as low as 1 pM for a total cycle time of about 1 min in a prototype analyzer. Such a short measurement time does not impair the performances of the assay when compared to longer experiments. The concentration range dynamic is shown to cover 3 orders of magnitude. An analytical model of agglutination is also successfully fitting our data obtained with a short magnetic pulse.

  10. Field-induced stacking transition of biofunctionalized trilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Masato Nakano, C. [Flintridge Preparatory School, La Canada, California 91011 (United States); Sajib, Md Symon Jahan; Samieegohar, Mohammadreza; Wei, Tao [Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710 (United States)

    2016-02-01

    Trilayer graphene (TLG) is attracting a lot of attention as their stacking structures (i.e., rhombohedral vs. Bernal) drastically affect electronic and optical properties. Based on full-atom molecular dynamics simulations, we here predict electric field-induced rhombohedral-to-Bernal transition of TLG tethered with proteins. Furthermore, our simulations show that protein's electrophoretic mobility and diffusivity are enhanced on TLG surface. This phenomenon of controllable TLG stacking transition will contribute to various applications including biosensing.

  11. Coulomb blockade induced by magnetic field

    International Nuclear Information System (INIS)

    Kusmartsev, F.V.

    1992-01-01

    In this paper, the authors found that a Coulomb blockade can be induced by magnetic field. The authors illustrated this effect on the example of a ring consisting of two and many Josephson junctions. For the ring with two junctions we present an exact solution. The transition into Coulomb blockade state on a ring transforms into a linear array of Josephson junctions, although in latter case the effect of magnetic field disappears. In the state of Coulomb blockade the magnetization may be both diamagnetic and paramagnetic. The Coulomb blockade may also be removed by external magnetic field

  12. Electric field enhancement at multiple densities in laser-irradiated ...

    Indian Academy of Sciences (India)

    Abstract. The electric field enhancement inside a nanotube irradiated by intense ultrashort laser pulse (≪1 ps) is calculated. The hollowness of the nanotubes determines the field enhancement and the electron density at which such structures exhibit resonance. The electric field in a nano- tube plasma is shown to be ...

  13. Field Induced Memory Effects in Random Nematics

    Directory of Open Access Journals (Sweden)

    Amid Ranjkesh

    2014-01-01

    Full Text Available We studied numerically external field induced memory effects in randomly perturbed nematic liquid crystals. Random anisotropy nematic-type lattice model was used. The impurities imposing orientational disorder were randomly spatially distributed with the concentration p below the percolation threshold. Simulations were carried for finite temperatures, where we varied p, interaction strength between LC molecules, and impurities and external field B. In the {B,T} plane we determined lines separating short range—quasi long range and quasi long range—long range order. Furthermore, crossover regime separating external field and random field dominated regime was estimated. We calculated remanent nematic ordering in samples at B=0 as a function of the previously experienced external field strength B.

  14. Localized enhancement of electric field in tip-enhanced Raman spectroscopy using radially and linearly polarized light.

    Science.gov (United States)

    Kazemi-Zanjani, Nastaran; Vedraine, Sylvain; Lagugné-Labarthet, François

    2013-10-21

    Finite-Difference Time-Domain (FDTD) calculations are used to characterize the electric field in the vicinity of a sharp silver or gold cone with an apex diameter of 10 nm. The simulations are utilized to predict the intensity and the distribution of the locally enhanced electric field in tip-enhanced Raman spectroscopy (TERS). A side-by-side comparison of the enhanced electric field induced by a radially and a linearly polarized light in both gap-mode and conventional TERS setup is performed. For this purpose, a radially polarized source is introduced and integrated into the FDTD modeling. Additionally, the optical effect of a thin protective layer of alumina on the enhancement of the electric field is investigated.

  15. Large optical field enhancement for nanotips with large opening angles

    OpenAIRE

    Thomas, Sebastian; Wachter, Georg; Lemell, Christoph; Burgdörfer, Joachim; Hommelhoff, Peter

    2015-01-01

    We theoretically investigate the dependence of the enhancement of optical near-fields at nanometric tips on the shape, size, and material of the tip. We confirm a strong dependence of the field enhancement factor on the radius of curvature. In addition, we find a surprisingly strong increase of field enhancement with increasing opening angle of the nanotips. For gold and tungsten nanotips in the experimentally relevant parameter range (radius of curvature $\\geq 5\\,$nm at $800\\,$nm laser wavel...

  16. Topology optimization of nanoparticles for localized electromagnetic field enhancement

    DEFF Research Database (Denmark)

    Christiansen, Rasmus Ellebæk; Vester-Petersen, Joakim; Madsen, Søren Peder

    2017-01-01

    We consider the design of individual and periodic arrangements of metal or semiconductor nanoparticles for localized electromagnetic field enhancement utilizing a topology optimization based numerical framework as the design tool. We aim at maximizing a function of the electromagnetic field...

  17. Microscopic model of the THz field enhancement in a metal nanoslit

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Zalkovskij, Maksim; Malureanu, Radu

    2011-01-01

    We discuss the strong THz-field enhancement effect in a metal slit of dozens of nanometers sizes reported recently. Proposed simple microscopic model considers electric charges induced at the edges of the slit by a polarized incident wave. These charges contribute then to the field in the slit...

  18. Induced seismicity associated with enhanced geothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Majer, Ernest; Majer, Ernest L.; Baria, Roy; Stark, Mitch; Oates, Stephen; Bommer, Julian; Smith, Bill; Asanuma, Hiroshi

    2006-09-26

    Enhanced Geothermal Systems (EGS) offer the potential to significantly add to the world energy inventory. As with any development of new technology, some aspects of the technology has been accepted by the general public, but some have not yet been accepted and await further clarification before such acceptance is possible. One of the issues associated with EGS is the role of microseismicity during the creation of the underground reservoir and the subsequent extraction of the energy. The primary objectives of this white paper are to present an up-to-date review of the state of knowledge about induced seismicity during the creation and operation of enhanced geothermal systems, and to point out the gaps in knowledge that if addressed will allow an improved understanding of the mechanisms generating the events as well as serve as a basis to develop successful protocols for monitoring and addressing community issues associated with such induced seismicity. The information was collected though literature searches as well as convening three workshops to gather information from a wide audience. Although microseismicity has been associated with the development of production and injection operations in a variety of geothermal regions, there have been no or few adverse physical effects on the operations or on surrounding communities. Still, there is public concern over the possible amount and magnitude of the seismicity associated with current and future EGS operations. It is pointed out that microseismicity has been successfully dealt with in a variety of non-geothermal as well as geothermal environments. Several case histories are also presented to illustrate a variety of technical and public acceptance issues. It is concluded that EGS Induced seismicity need not pose any threat to the development of geothermal resources if community issues are properly handled. In fact, induced seismicity provides benefits because it can be used as a monitoring tool to understand the

  19. Enhancement and Suppression in the Visual Field under Perceptual Load

    Directory of Open Access Journals (Sweden)

    Nathan A Parks

    2013-05-01

    Full Text Available The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task – greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs in conjunction with time-domain event-related potentials (ERPs to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2°, 6°, or 11° during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3Hz was attenuated under high perceptual load (relative to low load at the most proximal (2° eccentricity but not at more eccentric locations (6˚ or 11˚. Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

  20. Enhancement and suppression in the visual field under perceptual load

    Science.gov (United States)

    Parks, Nathan A.; Beck, Diane M.; Kramer, Arthur F.

    2013-01-01

    The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task—greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs) in conjunction with time-domain event-related potentials (ERPs) to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG) was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2, 6, or 11°) during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3 Hz) was attenuated under high perceptual load (relative to low load) at the most proximal (2°) eccentricity but not at more eccentric locations (6 or 11°). Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field. PMID:23734135

  1. Tailoring Terahertz Near-Field Enhancement via Two-Dimensional Plasmons

    Science.gov (United States)

    Davoyan, Arthur R.; Popov, Vyacheslav V.; Nikitov, Sergei A.

    2012-03-01

    We suggest a novel possibility for electrically tunable terahertz near-field enhancement in flatland electronic materials supporting two-dimensional plasmons, including recently discovered graphene. We employ electric-field effect modulation of electron density in such materials and induce a periodic plasmonic lattice with a defect cavity. We demonstrate that the plasmons resonantly excited in such a periodic plasmonic lattice by an incident terahertz radiation can strongly pump the cavity plasmon modes leading to a deep subwavelength concentration of terahertz energy, beyond λ/1000, with giant electric-field enhancement factors up to 104, which is 2 orders of magnitude higher than achieved previously in metal-based terahertz field concentrators.

  2. 'Ecstasy' enhances noise-induced hearing loss.

    Science.gov (United States)

    Church, Michael W; Zhang, Jinsheng S; Langford, Megan M; Perrine, Shane A

    2013-08-01

    'Ecstasy' or 3,4-methylenedioxy-N-methamphetamine (MDMA) is an amphetamine abused for its euphoric, empathogenic, hallucinatory, and stimulant effects. It is also used to treat certain psychiatric disorders. Common settings for Ecstasy use are nightclubs and "rave" parties where participants consume MDMA and dance to loud music. One concern with the club setting is that exposure to loud sounds can cause permanent sensorineural hearing loss. Another concern is that consumption of MDMA may enhance such hearing loss. Whereas this latter possibility has not been investigated, this study tested the hypothesis that MDMA enhances noise-induced hearing loss (NIHL) by exposing rats to either MDMA, noise trauma, both MDMA and noise, or neither treatment. MDMA was given in a binge pattern of 5 mg/kg per intraperitoneal injections every 2 h for a total of four injections to animals in the two MDMA-treated groups (MDMA-only and Noise + MDMA). Saline injections were given to the animals in the two non-MDMA groups (Control and Noise-only). Following the final injection, noise trauma was induced by a 10 kHz tone at 120 dB SPL for 1 h to animals in the two noise trauma-treated groups (Noise-only and Noise + MDMA). Hearing loss was assessed by the auditory brainstem response (ABR) and cochlear histology. Results showed that MDMA enhanced NIHL compared to Noise-only and that MDMA alone caused no hearing loss. This implies that "clubbers" and "rave-goers" are exacerbating the amount of NIHL when they consume MDMA and listen to loud sounds. In contrast to earlier reports, the present study found that MDMA by itself caused no changes in the click-evoked ABR's wave latencies or amplitudes. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Surface modifications by field induced diffusion.

    Directory of Open Access Journals (Sweden)

    Martin Olsen

    Full Text Available By applying a voltage pulse to a scanning tunneling microscope tip the surface under the tip will be modified. We have in this paper taken a closer look at the model of electric field induced surface diffusion of adatoms including the van der Waals force as a contribution in formations of a mound on a surface. The dipole moment of an adatom is the sum of the surface induced dipole moment (which is constant and the dipole moment due to electric field polarisation which depends on the strength and polarity of the electric field. The electric field is analytically modelled by a point charge over an infinite conducting flat surface. From this we calculate the force that cause adatoms to migrate. The calculated force is small for voltage used, typical 1 pN, but due to thermal vibration adatoms are hopping on the surface and even a small net force can be significant in the drift of adatoms. In this way we obtain a novel formula for a polarity dependent threshold voltage for mound formation on the surface for positive tip. Knowing the voltage of the pulse we then can calculate the radius of the formed mound. A threshold electric field for mound formation of about 2 V/nm is calculated. In addition, we found that van der Waals force is of importance for shorter distances and its contribution to the radial force on the adatoms has to be considered for distances smaller than 1.5 nm for commonly used voltages.

  4. Farmer Field Schools as a Springboard for Enhanced Uptake of ...

    African Journals Online (AJOL)

    The latest approach in enhancing the uptake of agricultural technologies is through the Farmer Field Schools that have only a short history in Tanzania.This paper reviews the literature on Farmer Field Schools, first giving a brief description of the nature of Farmer Field Schools. This is then followed by experiences from ...

  5. Towards the Understanding of Induced Seismicity in Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Gritto, Roland [Array Information Technology, Greenbelt, MD (United States); Dreger, Douglas [Univ. of California, Berkeley, CA (United States); Heidbach, Oliver [Helmholtz Centre Potsdam (Germany, German Research Center for Geosciences; Hutchings, Lawrence [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-08-29

    This DOE funded project was a collaborative effort between Array Information Technology (AIT), the University of California at Berkeley (UCB), the Helmholtz Centre Potsdam - German Research Center for Geosciences (GFZ) and the Lawrence Berkeley National Laboratory (LBNL). It was also part of the European research project “GEISER”, an international collaboration with 11 European partners from six countries including universities, research centers and industry, with the goal to address and mitigate the problems associated with induced seismicity in Enhanced Geothermal Systems (EGS). The goal of the current project was to develop a combination of techniques, which evaluate the relationship between enhanced geothermal operations and the induced stress changes and associated earthquakes throughout the reservoir and the surrounding country rock. The project addressed the following questions: how enhanced geothermal activity changes the local and regional stress field; whether these activities can induce medium sized seismicity M > 3; (if so) how these events are correlated to geothermal activity in space and time; what is the largest possible event and strongest ground motion, and hence the potential hazard associated with these activities. The development of appropriate technology to thoroughly investigate and address these questions required a number of datasets to provide the different physical measurements distributed in space and time. Because such a dataset did not yet exist for an EGS system in the United State, we used current and past data from The Geysers geothermal field in northern California, which has been in operation since the 1960s. The research addressed the need to understand the causal mechanisms of induced seismicity, and demonstrated the advantage of imaging the physical properties and temporal changes of the reservoir. The work helped to model the relationship between injection and production and medium sized magnitude events that have

  6. Electric Field Enhancement and Light Transmission in Cylindrical Nanoholes

    Energy Technology Data Exchange (ETDEWEB)

    Shuford, Kevin L [ORNL; Ratner, Mark A. [Northwestern University, Evanston; Gray, Stephen K. [Argonne National Laboratory (ANL); Schatz, George C. [Northwestern University, Evanston

    2007-01-01

    The properties of electric fields in subwavelength cylindrical apertures are examined upon excitation by a far-field source. We find that the largest enhancements are localized at the edge of the aperture, close to its rim. Both the entrance and exit rims of the hole can produce intense fields, although at long wavelengths thick slabs lead to smaller fields at the exit rim. The fields display a two lobe angular pattern characteristic of a radiating dipole in the near field. The influence of aperture size and slab thickness on field enhancement is presented. Although there is often a connection between peak transmission and peak field, the two rarely occur at the same wavelength. Enhancements in the electric field intensity can be increased by an order of magnitude by adding a grooved structure around the aperture, which acts as a grating and permits coupling to surface plasmon polaritons. Our results indicate that nanohole systems can be optimized to yield large electric field enhancements, making them an attractive medium for surface enhanced spectroscopies.

  7. Enhanced microactuation with magnetic field curing of ...

    Indian Academy of Sciences (India)

    The incorporation of nanoparticles of iron in a natural rubber matrix leads to flexible magnetorheolog- ical (MR) materials. Rod-shaped MR elastomers based on natural rubber and nanosized iron have been moulded both with and without the application of an external magnetic field during curing. These MR elastomer rods ...

  8. Enhanced microactuation with magnetic field curing of ...

    Indian Academy of Sciences (India)

    The incorporation of nanoparticles of iron in a natural rubber matrix leads to flexible magnetorheological (MR) materials. Rod-shaped MR elastomers based on natural rubber and nanosized iron have been moulded both with and without the application of an external magnetic field during curing. These MR elastomer rods ...

  9. Engineering two-wire optical antennas for near field enhancement

    Science.gov (United States)

    Yang, Zhong-Jian; Zhao, Qian; Xiao, Si; He, Jun

    2017-07-01

    We study the optimization of near field enhancement in the two-wire optical antenna system. By varying the nanowire sizes we obtain the optimized side-length (width and height) for the maximum field enhancement with a given gap size. The optimized side-length applies to a broadband range (λ = 650-1000 nm). The ratio of extinction cross section to field concentration size is found to be closely related to the field enhancement behavior. We also investigate two experimentally feasible cases which are antennas on glass substrate and mirror, and find that the optimized side-length also applies to these systems. It is also found that the optimized side-length shows a tendency of increasing with the gap size. Our results could find applications in field-enhanced spectroscopies.

  10. Enhanced fog collection with electric fields

    Science.gov (United States)

    Damak, Maher; Mahmoudi, Seyed Reza; Varanasi, Kripa

    2015-11-01

    Fog harvesting is a promising source of fresh water in remote areas. However, the efficiency of current collectors, consisting in fine meshes standing perpendicularly to the wind, is dramatically low. Fog-laden flows generally have low Stokes numbers, which leads to the deviation of fog droplets in the vicinity of the mesh wires. Here, we propose to overcome this aerodynamic limitation using a combination of electric fields and specific collecting surfaces. We show that our system largely increases the fog collection efficiency. We study the trajectories of individual particles and use the results to derive a model to predict the collection efficiency of the system. We finally identify and quantify the mechanisms that can limit the collection of fog particles. The understanding of these mechanisms leads us to construct a design chart that can be used to determine the optimal design parameters that should be used in fog collection applications as a function of the field conditions.

  11. Giant Magnetic Field Enhancement in Hybridized MIM Structures

    KAUST Repository

    Alrasheed, Salma

    2017-10-23

    We propose numerically an approach to narrow the plasmon linewidth and enhance the magnetic near field intensity at a magnetic hot spot in a hybridized metal-insulatormetal (MIM) structure. First we insert in part of the dielectric layer of the MIM, at its center, another dielectric material of a high refractive index (HRI). This results in an increase in the magnetic near field enhancement of the magnetic plasmon (MP) resonance by 82% compared with the MIM without the HRI material. We then couple this enhanced MP resonance to a propagating surface plasmon polariton (SPP) to achieve a further enhancement of 438%. The strong coupling between the MP and the SPP is demonstrated by the large anti-crossing in the reflection spectra. The resulting maximum magnetic field enhancement at the gap is ~ |H / Hi|² = 3555.

  12. The induced electric field distribution in the solar atmosphere

    International Nuclear Information System (INIS)

    Chen Rong; Yang Zhi-Liang; Deng Yuan-Yong

    2013-01-01

    A method of calculating the induced electric field is presented. The induced electric field in the solar atmosphere is derived by the time variation of the magnetic field when the accumulation of charged particles is neglected. In order to derive the spatial distribution of the magnetic field, several extrapolation methods are introduced. With observational data from the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory taken on 2010 May 20, we extrapolate the magnetic field from the photosphere to the upper atmosphere. By calculating the time variation of the magnetic field, we can get the induced electric field. The derived induced electric field can reach a value of 10 2 V cm −1 and the average electric field has a maximum point at the layer 360 km above the photosphere. The Monte Carlo method is used to compute the triple integration of the induced electric field.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

  14. Optical waveguide mode control by nanoslit-enhanced terahertz field

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Zalkovskij, Maksim; Malureanu, Radu

    2012-01-01

    In this Letter we propose a scheme providing control over an optical waveguide mode by a terahertz (THz) wave. The scheme is based on an optimization of the overlap between the optical waveguide mode and the THz field, with the THz field strength enhanced by the presence of a metallic nanoslit...

  15. Quantification and Measurement of Internal Electromagnetic Fields Induced in Finite Biological Bodies by Nonuniform Electromagnetic Fields.

    Science.gov (United States)

    1978-10-15

    implantable EM field probes which can be used to measure the internal EM fields induced in simulated biological bod ies. Major topics of this program include...be used to measure the internal EM fields induced in simulated biological bodies with a high degree of accuracy. Most of the originally planned topics...following papers: (1) "Focal hyperthermia as induced by RF radiation of simulacra with embedded tumors and as induced by EM fields in a model of a human

  16. Non-resonant terahertz field enhancement in periodically arranged nanoslits

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Ivinskaya, Aliaksandra; Zalkovskij, Maksim

    2012-01-01

    We analyze ultra strong non-resonant field enhancement of THz field in periodic arrays of nanoslits cut in ultrathin metal films. The main feature of our approach is that the slit size and metal film thickness are several orders of magnitude smaller than the wavelength λ of the impinging radiation...... by the microscopic Drude-Lorentz model taking into account retardation processes in the metal film and validated by the finite difference frequency domain method. We expect sensor and modulation applications of the predicted giant broadband field enhancement....

  17. Surface plasmon field enhancements in deterministic aperiodic structures.

    Science.gov (United States)

    Shugayev, Roman

    2010-11-22

    In this paper we analyze optical properties and plasmonic field enhancements in large aperiodic nanostructures. We introduce extension of Generalized Ohm's Law approach to estimate electromagnetic properties of Fibonacci, Rudin-Shapiro, cluster-cluster aggregate and random deterministic clusters. Our results suggest that deterministic aperiodic structures produce field enhancements comparable to random morphologies while offering better understanding of field localizations and improved substrate design controllability. Generalized Ohm's law results for deterministic aperiodic structures are in good agreement with simulations obtained using discrete dipole method.

  18. The effect of substrate on electric field enhancement of Tip-enhanced Raman spectroscopy (TERS)

    Science.gov (United States)

    Bahreini, Maryam

    2018-01-01

    The characterization of materials down to a few-molecule level is a key challenge in nanotechnology. Raman spectroscopy is a powerful method that provides chemical information via nondestructive vibrational fingerprinting. Unfortunately, this method suffers from signal weakness which prevents the study of small quantities. Tip-enhanced Raman spectroscopy (TERS) which combines the chemical sensitivity of Raman spectroscopy (RS) with high spatial resolution of scanning probe microscopy (SPM), provides chemical images of surfaces at the nanometer scale. In this method, irradiation of an SPM tip by a focused laser beam results in enhancement of local electric field via two reasons of localized surface plasmon resonance and lightning rod effect. This enhancement leads to the enhancement in Raman intensity from the sample surface in the vicinity of tip. In all TERS measurements, samples should be located on a substrate. In this paper, the dependence of the electric field enhancement to the substrate has been investigated. In simulations, three-dimensional finite-difference time-domain (3D-FDTD) method is used for numerical solution of Maxwell's equations. Our results show that the electric field enhancement is weak for the tip alone case. Introducing a substrate provides further electric field enhancement via near field electromagnetic dipole-dipole coupling between the tip and substrate. Since the side-illumination geometry is used for laser irradiation, the vertical component of the incident field plays a dominant role in the electric field enhancement. Therefore, the coupling effect between the tip and the substrate is the key contribution to the enhancement. For the case of silicon tip and the gold substrate, the electric field enhancement is improved considerably. There is an optimal tip size for TERS because of the competing effects of the radiation damping and the surface scattering of the tip. The results show the substrate as an effective tool for the

  19. Enhanced ALA-induced fluorescence in hyperparathyroidism.

    Science.gov (United States)

    Prosst, Ruediger L; Schroeter, Lioba; Gahlen, Johannes

    2005-04-04

    Intraoperative localization of parathyroid glands can be challenging especially in minimally invasive surgery. Fluorescence diagnosis using the photosensitizer aminolevulinic acid (ALA) has been described to identify normal parathyroid glands during experimental bilateral neck exploration. The present study evaluated fluorescence differences between hyperplastic and normal parathyroid glands as a precondition for a clinical application of the technique. Polycystic kidney disease (PKD) rats with hyperparathyroidism due to hyperplastic parathyroid glands and Wistar rats with normal parathyroid glands were photosensitized by peritoneal lavage with ALA solution. After surgical exposure of thyroid and parathyroid glands the operative site was observed under blue light conditions using the d-light system to assess fluorescence characteristics of each tissue. Fluorescence intensities of parathyroid glands and surrounding thyroid tissue were measured by spectrometry. Parathyroid hormone in serum of the rats was determined by enzyme-linked immunosorbent assay (ELISA). Observation of the exposed thyroid site showed a subjectively stronger red fluorescence of the parathyroid glands in the PKD rats in comparison to the Wistar rats, whereas thyroid tissue appeared equally fluorescent. In the PKD animals, spectrometric fluorescence intensity was 10 times higher in the parathyroid glands than in the thyroid gland, whereas in the Wistar rats the ratio was 3.2:1. Fluorescence intensity in the parathyroid glands was more than twice in the PKD rats than in the Wistar rats, however slightly lower in the thyroid tissue. ELISA confirmed the pathophysiological change of a hyperparathyroidism with significantly increased serum levels of parathyroid hormone in the PKD rats. Hyperparathyroidism enhances ALA-induced fluorescence of the parathyroid glands. A combined surgical fluorescence strategy may justify a unilateral, minimally invasive approach in selected patients and serve to improve

  20. Infrared image detail enhancement based on the gradient field specification.

    Science.gov (United States)

    Zhao, Wenda; Xu, Zhijun; Zhao, Jian; Zhao, Fan; Han, Xizhen

    2014-07-01

    Human vision is sensitive to the changes of local image details, which are actually image gradients. To enhance faint infrared image details, this article proposes a gradient field specification algorithm. First we define the image gradient field and gradient histogram. Then, by analyzing the characteristics of the gradient histogram, we construct a Gaussian function to obtain the gradient histogram specification and therefore obtain the transform gradient field. In addition, subhistogram equalization is proposed based on the histogram equalization to improve the contrast of infrared images. The experimental results show that the algorithm can effectively improve image contrast and enhance weak infrared image details and edges. As a result, it can give qualified image information for different applications of an infrared image. In addition, it can also be applied to enhance other types of images such as visible, medical, and lunar surface.

  1. Electric field control photo-induced Hall currents in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong, Chittagong 4331 (Bangladesh)], E-mail: m.miah@griffith.edu.au

    2008-10-15

    We generate spin-polarized carrier populations in GaAs and low temperature-grown GaAs (LT-GaAs) by circularly polarized optical beams and pull them by external electric fields to create spin-polarized currents. In the presence of the optically generated spin currents, anomalous Hall currents with an enhancement with increasing doping are observed and found to be almost steady in moderate electric fields up to {approx}120 mV {mu}m{sup -1}, indicating that photo-induced spin orientation of electrons is preserved in these systems. However, a field {approx}300 mV {mu}m{sup -1} completely destroys the electron spin polarization due to an increase of the D'yakonov-Perel' spin precession frequency of the hot electrons. This suggests that high field carrier transport conditions might not be suitable for spin-based technology with GaAs and LT-GaAs. It is also demonstrated that the presence of the excess arsenic sites in LT-GaAs might not affect the spin relaxation by Bir-Aronov-Pikus mechanism owing to a large number of electrons in n-doped materials.

  2. Magnetic Field Enhanced Superconductivity in Epitaxial Thin Film WTe2.

    Science.gov (United States)

    Asaba, Tomoya; Wang, Yongjie; Li, Gang; Xiang, Ziji; Tinsman, Colin; Chen, Lu; Zhou, Shangnan; Zhao, Songrui; Laleyan, David; Li, Yi; Mi, Zetian; Li, Lu

    2018-04-25

    In conventional superconductors an external magnetic field generally suppresses superconductivity. This results from a simple thermodynamic competition of the superconducting and magnetic free energies. In this study, we report the unconventional features in the superconducting epitaxial thin film tungsten telluride (WTe 2 ). Measuring the electrical transport properties of Molecular Beam Epitaxy (MBE) grown WTe 2 thin films with a high precision rotation stage, we map the upper critical field H c2 at different temperatures T. We observe the superconducting transition temperature T c is enhanced by in-plane magnetic fields. The upper critical field H c2 is observed to establish an unconventional non-monotonic dependence on temperature. We suggest that this unconventional feature is due to the lifting of inversion symmetry, which leads to the enhancement of H c2 in Ising superconductors.

  3. Enhanced Field Emission Studies on Niobium Surfaces Relevant to High Field Superconducting Radio-Frequency Devices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tong [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2002-09-18

    Enhanced field emission (EFE) presents the main impediment to higher acceleration gradients in superconducting niobium (Nb) radiofrequency cavities for particle accelerators. The strength, number and sources of EFE sites strongly depend on surface preparation and handling. The main objective of this thesis project is to systematically investigate the sources of EFE from Nb, to evaluate the best available surface preparation techniques with respect to resulting field emission, and to establish an optimized process to minimize or eliminate EFE. To achieve these goals, a scanning field emission microscope (SFEM) was designed and built as an extension to an existing commercial scanning electron microscope (SEM). In the SFEM chamber of ultra high vacuum, a sample is moved laterally in a raster pattern under a high voltage anode tip for EFE detection and localization. The sample is then transferred under vacuum to the SEM chamber equipped with an energy-dispersive x-ray spectrometer for individual emitting site characterization. Compared to other systems built for similar purposes, this apparatus has low cost and maintenance, high operational flexibility, considerably bigger scan area, as well as reliable performance. EFE sources from planar Nb have been studied after various surface preparation, including chemical etching and electropolishing, combined with ultrasonic or high-pressure water rinse. Emitters have been identified, analyzed and the preparation process has been examined and improved based on EFE results. As a result, field-emission-free or near field-emission-free surfaces at ~140 MV/m have been consistently achieved with the above techniques. Characterization on the remaining emitters leads to the conclusion that no evidence of intrinsic emitters, i.e., no fundamental electric field limit induced by EFE, has been observed up to ~140 MV/m. Chemically etched and electropolished Nb are compared and no significant difference is observed up to ~140 MV/m. To

  4. Endogenous fields enhanced stochastic resonance in a randomly coupled neuronal network

    International Nuclear Information System (INIS)

    Deng, Bin; Wang, Lin; Wang, Jiang; Wei, Xi-le; Yu, Hai-tao

    2014-01-01

    Highlights: • We study effects of endogenous fields on stochastic resonance in a neural network. • Stochastic resonance can be notably enhanced by endogenous field feedback. • Endogenous field feedback delay plays a vital role in stochastic resonance. • The parameters of low-passed filter play a subtle role in SR. - Abstract: Endogenous field, evoked by structured neuronal network activity in vivo, is correlated with many vital neuronal processes. In this paper, the effects of endogenous fields on stochastic resonance (SR) in a randomly connected neuronal network are investigated. The network consists of excitatory and inhibitory neurons and the axonal conduction delays between neurons are also considered. Numerical results elucidate that endogenous field feedback results in more rhythmic macroscope activation of the network for proper time delay and feedback coefficient. The response of the network to the weak periodic stimulation can be notably enhanced by endogenous field feedback. Moreover, the endogenous field feedback delay plays a vital role in SR. We reveal that appropriately tuned delays of the feedback can either induce the enhancement of SR, appearing at every integer multiple of the weak input signal’s oscillation period, or the depression of SR, appearing at every integer multiple of half the weak input signal’s oscillation period for the same feedback coefficient. Interestingly, the parameters of low-passed filter which is used in obtaining the endogenous field feedback signal play a subtle role in SR

  5. GABAergic Neural Activity Involved in Salicylate-Induced Auditory Cortex Gain Enhancement

    Science.gov (United States)

    Lu, Jianzhong; Lobarinas, Edward; Deng, Anchun; Goodey, Ronald; Stolzberg, Daniel; Salvi, Richard J.; Sun, Wei

    2011-01-01

    Although high doses of sodium salicylate impair cochlear function, it paradoxically enhances sound-evoked activity in the auditory cortex (AC) and augments acoustic startle reflex responses, neural and behavioral metrics associated with hyperexcitability and hyperacusis. To explore the neural mechanisms underlying salicylate-induced hyperexcitability and “increased central gain”, we examined the effects of γ-aminobutyric acid (GABA) receptor agonists and antagonists on salicylate-induced hyperexcitability in the AC and startle reflex responses. Consistent with our previous findings, local or systemic application of salicylate significantly increased the amplitude of sound-evoked AC neural activity, but generally reduced spontaneous activity in the AC. Systemic injection of salicylate also significantly increased the acoustic startle reflex. S-baclofen or R-baclofen, GABA-B agonists, which suppressed sound-evoked AC neural firing rate and local field potentials, also suppressed the salicylate-induced enhancement of the AC field potential and the acoustic startle reflex. Local application of vigabatrin, which enhances GABA concentration in the brain, suppressed the salicylate-induced enhancement of AC firing rate. Systemic injection of vigabatrin also reduced the salicylate-induced enhancement of acoustic startle reflex. Collectively, these results suggest that the sound-evoked behavioral and neural hyperactivity induced by salicylate may arise from a salicylate-induced suppression GABAergic inhibition in the AC. PMID:21664433

  6. Computation of induced electric field for the sacral nerve activation

    International Nuclear Information System (INIS)

    Hirata, Akimasa; Hattori, Junya; Laakso, Ilkka; Takagi, Airi; Shimada, Takuo

    2013-01-01

    The induced electric field/current in the sacral nerve by stimulation devices for the treatment of bladder overactivity is investigated. Implanted and transcutaneous electrode configurations are considered. The electric field induced in the sacral nerve by the implanted electrode is largely affected by its surrounding tissues, which is attributable to the variation in the input impedance of the electrode. In contrast, the electric field induced by the transcutaneous electrode is affected by the tissue conductivity and anatomical composition of the body. In addition, the electric field induced in the subcutaneous fat in close proximity of the electrode is comparable with the estimated threshold electric field for pain. These computational findings explain the clinically observed weakness and side effect of each configuration. For the transcutaneous stimulator, we suggest that the electrode contact area be increased to reduce the induced electric field in the subcutaneous fat. (paper)

  7. Modeling of Local Magnetic Field Enhancements within Solar Flux Ropes

    OpenAIRE

    Romashets, E; Vandas, M; Poedts, Stefaan

    2010-01-01

    To model and study local magnetic-field enhancements in a solar flux rope we consider the magnetic field in its interior as a superposition of two linear (constant alpha) force-free magnetic-field distributions, viz. a global one, which is locally similar to a part of the cylinder, and a local torus-shaped magnetic distribution. The newly derived solution for a toroid with an aspect ratio close to unity is applied. The symmetry axis of the toroid and that of the cylinder may or may not coinci...

  8. Electric field enhancement at multiple densities in laser-irradiated ...

    Indian Academy of Sciences (India)

    Vol. 79, No. 3. — journal of. September 2012 physics pp. 443–456. Electric field enhancement at multiple densities in laser-irradiated nanotube plasma ...... Phys. Lett. 90, 141502 (2007). [23] H M Milchberg, S J McNaught and E Parra, Phys. Rev. E64, 056402 (2001). [24] J Jha and M Krishnamurthy, Appl. Phys. Lett.

  9. Electric field enhancement at multiple densities in laser-irradiated ...

    Indian Academy of Sciences (India)

    The electric field in a nanotube plasma is shown to be resonantly enhanced at multiple densities during the two phases of interaction: the ionization phase and the hydrodynamic expansion phase. It is further shown that by a proper choice of hollowness of the nanotubes, a continued occurrence of the resonance over a ...

  10. Enhancing Field Research Methods with Mobile Survey Technology

    Science.gov (United States)

    Glass, Michael R.

    2015-01-01

    This paper assesses the experience of undergraduate students using mobile devices and a commercial application, iSurvey, to conduct a neighborhood survey. Mobile devices offer benefits for enhancing student learning and engagement. This field exercise created the opportunity for classroom discussions on the practicalities of urban research, the…

  11. Enhancement of the Performance of a Transfer Field Electric ...

    African Journals Online (AJOL)

    This paper reports the enhancement of the output power and power factor of a transfer field machine operating in the asynchronous mode by direct capacitance injection into the auxiliary winding of the machine, which is electrically isolated from the main winding but magnetically coupled to it. It is shown that by proper ...

  12. Field-enhanced REB deposition and Bremsstrahlung production

    International Nuclear Information System (INIS)

    Halbleib, J.A. Sr.; Widner, M.M.

    1977-07-01

    Recently developed models are employed to describe the interaction of a high-current REB (relativistic electron beam) with planar gold foils in the presence of macroscopic electromagnetic fields. It is shown that, under certain conditions, azimuthal magnetic fields which either penetrate into the foil and/or exist on the transmission side of the foil can significantly enhance the specific power deposited in the foil over that which would be deposited for diode fields alone. Similar field effects suggest methods for improving the external conversion efficiencies, softening the spectra and focussing the source intensities of flash x-ray facilities. Finally, preliminary results are shown from a new trajectory-field model for self-consistent REB transport

  13. Bias-enhanced post-treatment process for enhancing the electron field emission properties of ultrananocrystalline diamond films

    International Nuclear Information System (INIS)

    Saravanan, A.; Huang, B. R.; Sankaran, K. J.; Tai, N. H.; Dong, C. L.; Lin, I. N.

    2015-01-01

    The electron field emission (EFE) properties of ultrananocrystalline diamond films were markedly improved via the bias-enhanced plasma post-treatment (bep) process. The bep-process induced the formation of hybrid-granular structure of the diamond (bep-HiD) films with abundant nano-graphitic phase along the grain boundaries that increased the conductivity of the films. Moreover, the utilization of Au-interlayer can effectively suppress the formation of resistive amorphous-carbon (a-C) layer, thereby enhancing the transport of electrons crossing the diamond-to-Si interface. Therefore, bep-HiD/Au/Si films exhibit superior EFE properties with low turn-on field of E 0  = 2.6 V/μm and large EFE current density of J e  = 3.2 mA/cm 2 (at 5.3 V/μm)

  14. Magnetic field enhanced cell uptake efficiency of magnetic silica mesoporous nanoparticles.

    Science.gov (United States)

    Liu, Qian; Zhang, Jixi; Xia, Weiliang; Gu, Hongchen

    2012-06-07

    The advantages of using magnetic mesoporous silica nanoparticles (M-MSNs) in biomedical applications have been widely recognized. However, poor uptake efficiency may hinder the potential of M-MSNs in many applications, such as cell tracking, drug delivery, fluorescence and magnetic resonance imaging. An external magnetic field may improve the cellular uptake efficiency. In this paper, we evaluated the effect of a magnetic field on the uptake of M-MSNs. We found that the internalization of M-MSNs by A549 cancer cells could be accelerated and enhanced by a magnetic field. An endocytosis study indicated that M-MSNs were internalized by A549 cells mainly through an energy-dependent pathway, namely clathrin-induced endocytosis. Transmission electron microscopy showed that M-MSNs were trafficked into lysosomes. With the help of a magnetic field, anticancer drug-loaded M-MSNs induced elevated cancer cell growth inhibition.

  15. Field-Induced Rheology in Uniaxial and Biaxial Fields

    Energy Technology Data Exchange (ETDEWEB)

    MARTIN, JAMES E.

    1999-10-22

    Steady and oscillatory shear 3-D simulations of electro- and magnetorheology in uniaxial and biaxial fields are presented, and compared to the predictions of the chain model. These large scale simulations are three dimensional, and include the effect of Brownian motion. In the absence of thermal fluctuations, the expected shear thinning viscosity is observed in steady shear, and a striped phase is seen to rapidly form in a uniaxial field, with a shear slip zone in each sheet. However, as the influence of Brownian motion increases, the fluid stress decreases, especially at lower Mason numbers, and the striped phase eventually disappears, even when the fluid stress is still high. In a biaxial field, an opposite trend is seen, where Brownian motion decreases the stress most significantly at higher Mason numbers. to account for the uniaxial steady shear data they propose a microscopic chain model of the role played by thermal fluctuations on the rheology of ER and MR fluids that delineates the regimes where an applied field can impact the fluid viscosity, and gives an analytical prediction for the thermal effect. In oscillatory shear, a striped phase again appears in uniaxial field, at strain amplitudes greater than {approx} 0.15, and the presence of a shear slip zone creates strong stress nonlinearities at low strain amplitudes. In a biaxial field, a shear slip zone is not created, and so the stress nonlinearities develop only at expected strain amplitudes. The nonlinear dynamics of these systems is shown to be in good agreement with the Kinetic Chain Model.

  16. Enhanced aerobic nitrifying granulation by static magnetic field.

    Science.gov (United States)

    Wang, Xin-Hua; Diao, Mu-He; Yang, Ying; Shi, Yi-Jing; Gao, Ming-Ming; Wang, Shu-Guang

    2012-04-01

    One of the main challenging issues for aerobic nitrifying granules in treating high strength ammonia wastewater is the long granulation time required for activated sludge to transform into aerobic granules. The present study provides a novel strategy for enhancing aerobic nitrifying granulation by applying an intensity of 48.0mT static magnetic field. The element analysis showed that the applied magnetic field could promote the accumulation of iron compounds in the sludge. And then the aggregation of iron decreased the full granulation time from 41 to 25days by enhancing the setting properties of granules and stimulating the secretion of extracellular polymeric substances (EPS). Long-term, cycle experiments and fluorescence in-situ hybridization (FISH) analysis proved that an intensity of 48.0mT magnetic field could enhance the activities and growth of nitrite-oxidizing bacteria (NOB). These findings suggest that magnetic field is helpful and reliable for accelerating the aerobic nitrifying granulation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Velocity fields in mixing-enhanced compressible shear layers

    Science.gov (United States)

    Watanabe, Shigeya; Mungal, M. G.

    2005-01-01

    Planar velocity fields of mixing-enhanced compressible planar shear layers are measured via particle image velocimetry (PIV) in order to investigate the mechanism of mixing enhancement by sub-boundary-layer triangular disturbances. The measurements are conducted at convective Mach numbers, M_{{c}}, of 0.62 and 0.24 to examine compressibility effects on effectiveness of the mixing enhancement technique. Instantaneous side- and plan-view vector maps of the shear layers are obtained, and turbulence statistical quantities are derived from the instantaneous velocity data. Schlieren and planar laser Mie scattering (PLMS) techniques are also used to measure the shear-layer thickness and growth rate as well as surveying the qualitative flow fields. The velocity fields for several disturbance configurations with different shape, size, or thickness are compared in terms of the shear-layer thickness and growth rate in order to investigate the effects of the configuration variation on the mixing enhancement strategy. Configuration parameters include thickness, the semi-vertex angle of the triangular disturbance, and the streamwise offset of the disturbance from the splitter tip. The measured transverse profile of the mean streamwise velocity shows a characteristic shape with triple inflection points for the effective mixing-enhanced cases at the two different compressibility conditions, while periodic inflection points are observed in the spanwise direction. A pair of stationary counter-rotating streamwise vortices introduced by the subboundary-layer disturbances are also observed, even in the fully developed region of the shear layers. At M_{{c}} {=} 0.62, it is found that in successfully enhanced cases, regardless of the disturbance configurations, the present mixing-enhancement strategy has the effect of increasing the turbulence intensity and Reynolds stress, and suppressing the turbulence anisotropy increase with increasing compressibility, i.e. alleviating the

  18. Enhancement of sedimentation and coagulation with static magnetic field

    Science.gov (United States)

    Zieliński, Marcin; Dębowski, Marcin; Hajduk, Anna; Rusanowska, Paulina

    2017-11-01

    The static magnetic field can be an alternative method for wastewater treatment. It has been proved that this physical factor, accelerates the biochemical processes, catalyzes advanced oxidation, intensifies anaerobic and aerobic processes or reduces swelling of activated sludge. There are also reports proving the positive impact of the static magnetic field on the coagulation and sedimentation, as well as the conditioning and dewatering of sludge. In order to be applied in larger scale the published results should be verified and confirmed. In the studies, the enhancement of sedimentation by the static magnetic field was observed. The best sedimentation was noted in the experiment, where magnetizers were placed on activated sludge bioreactor and secondary settling tank. No effect of the static magnetic field on coagulation with the utilization of PIX 113 was observed. However, the static magnetic field enhanced coagulation with the utilization of PAX-XL9. The results suggest that increased sedimentation of colloids and activated sludge, can in practice mean a reduction in the size of the necessary equipment for sedimentation with an unchanged efficiency of the process.

  19. Enhanced lipase production by mutation induced Aspergillus ...

    African Journals Online (AJOL)

    ... the HNO2 mutant (AHN3) and 217% higher than the UV mutant (AUV3) and 276% higher lipase activity than the parent strain. The results indicated that UV, HNO2 and NTG treatment were effective physical and chemical mutagenic agents for strain improvement of Aspergillus japonicus for enhanced lipase productivity.

  20. Mutation induced enhanced biosynthesis of lipase | Bapiraju ...

    African Journals Online (AJOL)

    The purpose of the present investigation is to enhance production of biomedically important enzyme lipase by subjecting the indigenous lipase producing strain Rhizopus sp. BTS-24 to improvement by natural selection and random mutagenesis (UV and N-methyl-N'-nitro-N-nitroso guanidine, NTG). The isolation of mutants ...

  1. Field-Induced Superconductivity in Electric Double Layer Transistors

    NARCIS (Netherlands)

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

    Electric field tuning of superconductivity has been a long-standing issue in solid state physics since the invention of the field-effect transistor (FET) in 1960. Owing to limited available carrier density in conventional FET devices, electric-field-induced superconductivity was believed to be

  2. Thermal and Field Enhanced Photoemission Comparison of Theory to Experiment

    CERN Document Server

    Lynn-Jensen, Kevin

    2004-01-01

    Photocathodes are a critical component of high-gain FEL’s and the analysis of their emission is complex. Relating their performance under laboratory conditions to conditions of an rf photoinjector is difficult. Useful models must account for cathode surface conditions and material properties, as well as drive laser parameters. We have developed a time-dependent model accounting for the effects of laser heating and thermal propagation on photoemission. It accounts for surface conditions (coating, field enhancement, reflectivity), laser parameters (duration, intensity, wavelength), and material characteristics (reflectivity, laser penetration depth, scattering rates) to predict current distribution and quantum efficiency. The applicatIon will focus on photoemission from metals and, in particular, dispenser photocathodes: the later introduces complications such as coverage non-uniformity and field enhancement. The performance of experimentally characterized photocathodes will be extrapolated to 0.1 - 1 nC bunch...

  3. Enhancement of acetaminophen overdosage-induced hepatotoxicity ...

    African Journals Online (AJOL)

    paracetamol) overdosage-induced hepatotoxicity in three groups of albino Wistar rats. Administration of the minimum toxic dose of paracetamol (150mg/kg body weight) to animals (group II) produced significantly (P≤0.05) higher levels of alanine ...

  4. Field plate structural optimization for enhancing the power gain of GaN-based HEMTs

    Science.gov (United States)

    Zhang, Kai; Cao, Meng-Yi; Lei, Xiao-Yi; Zhao, Sheng-Lei; Yang, Li-Yuan; Zheng, Xue-Feng; Ma, Xiao-Hua; Hao, Yue

    2013-09-01

    A novel source-connected field plate structure, featuring the same photolithography mask as the gate electrode, is proposed as an improvement over the conventional field plate (FP) techniques to enhance the frequency performance in GaN-based HEMTs. The influences of the field plate on frequency and breakdown performance are investigated simultaneously by using a two-dimensional physics-based simulation. Compared with the conventional T-gate structures with a field plate length of 1.2 μm, this field plate structure can induce the small signal power gain at 10 GHz to increase by 5-9.5 dB, which depends on the distance between source FP and dramatically shortened gate FP. This technique minimizes the parasitic capacitances, especially the gate-to-drain capacitance, showing a substantial potential for millimeter-wave, high power applications.

  5. Field plate structural optimization for enhancing the power gain of GaN-based HEMTs

    International Nuclear Information System (INIS)

    Zhang Kai; Cao Meng-Yi; Lei Xiao-Yi; Zhao Sheng-Lei; Yang Li-Yuan; Zheng Xue-Feng; Ma Xiao-Hua; Hao Yue

    2013-01-01

    A novel source-connected field plate structure, featuring the same photolithography mask as the gate electrode, is proposed as an improvement over the conventional field plate (FP) techniques to enhance the frequency performance in GaN-based HEMTs. The influences of the field plate on frequency and breakdown performance are investigated simultaneously by using a two-dimensional physics-based simulation. Compared with the conventional T-gate structures with a field plate length of 1.2 μm, this field plate structure can induce the small signal power gain at 10 GHz to increase by 5-9.5 dB, which depends on the distance between source FP and dramatically shortened gate FP. This technique minimizes the parasitic capacitances, especially the gate-to-drain capacitance, showing a substantial potential for millimeter-wave, high power applications. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Heat transfer enhancement in a convective field by applying ionic wind

    International Nuclear Information System (INIS)

    Tada, Y.; Takimoto, A.; Hayashi, Y.

    1991-01-01

    This paper reports that this study has been conducted to pursue the heat transfer enhancement in a convective field by applying electric field. Firstly, aimed at thinning boundary layer, swirl motions were caused by utilizing the ionic wind in a channel flow with parallel wire-electrode arrangement. Secondly, ionic wind was induced at right angle to the primary flow at regular intervals by using cross wire-electrode arrangement. Thirdly, to utilize the dynamical effect of adding particles under the Coulomb force, electric field was applied to gas-solid suspensions flow field. On the basis of these results, fundamental characteristics of the combined flow structure and the heat transfer in the EHD field were clarified, and the possibility of the practical application will be insighted

  7. Enhanced thermal photon and dilepton production in strongly coupled = 4 SYM plasma in strong magnetic field

    Science.gov (United States)

    Mamo, Kiminad A.

    2013-08-01

    We calculate the DC conductivity tensor of strongly coupled = 4 super-Yang-Mills (SYM) plasma in a presence of a strong external magnetic field B ≫ T 2 by using its gravity dual and employing both the RG flow approach and membrane paradigm which give the same results. We find that, since the magnetic field B induces anisotropy in the plasma, different components of the DC conductivity tensor have different magnitudes depending on whether its components are in the direction of the magnetic field B. In particular, we find that a component of the DC conductivity tensor in the direction of the magnetic field B increases linearly with B while the other components (which are not in the direction of the magnetic field B) are independent of it. These results are consistent with the lattice computations of the DC conductivity tensor of the QCD plasma in an external magnetic field B. Using the DC conductivity tensor, we calculate the soft or low-frequency thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in the presence of the strong external magnetic field B ≫ T 2. We find that the strong magnetic field B enhances both the thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in a qualitative agreement with the experimentally observed enhancements at the heavy-ion collision experiments.

  8. Electrohydrodynamic flow caused by field-enhanced dissociation solely

    Science.gov (United States)

    Vasilkov, S. A.; Chirkov, V. A.; Stishkov, Yu. K.

    2017-06-01

    Electrohydrodynamic (EHD) flows emerge in dielectric liquids under the action of the Coulomb force and underlie energy-efficient techniques for heat and mass transfer. The key issue in the phenomena is the way how the net charge is created. One of the most promising, yet poorly studied charge formation mechanisms is the field-enhanced dissociation (or the Wien effect). So the paper studies an EHD flow caused solely by the effect by virtue of both experiment and computer simulation. To preclude the competing mechanism of charge formation—the injection—a new EHD system of a special design was examined. Its main feature is the use of solid insulation to create the region of the strong electric field far from the electrode metal surfaces. The experimental study used the particle image velocimetry technique to observe velocity distributions, whereas the computations were based on the complete set of electrohydrodynamic equations employing the commercial software package COMSOL Multiphysics. Spatial distributions of key quantities (including the ion concentrations, the total space charge density, and the velocity) and the acting forces were obtained in the computer simulation and were analyzed. The experimental flow structure was observed for a number of voltages up to 30 kV. The comparison of the numerical and experimental results yielded a good quantitative agreement for strong electric fields though some overshoot was observed for weak ones. The results allow concluding on the applicability of the Onsager theory of the field-enhanced dissociation in the context of EHD flows.

  9. Enhanced field emission from carbon nanotubes by hydrogen plasma treatment

    International Nuclear Information System (INIS)

    Zhi, C.Y.; Bai, X.D.; Wang, E.G.

    2002-01-01

    The field emission capability of the carbon nanotubes (CNTs) has been improved by hydrogen plasma treatment, and the enhanced emission mechanism has been studied systematically using Fourier-transform infrared spectroscopy, Raman, and transmission electron microscopy. The hydrogen concentration in the samples increases with increasing plasma treatment duration. A C δ- -H δ+ dipole layer may form on CNTs' surface and a high density of defects results from the plasma treatment, which is likely to make the external surface of CNTs more active to emit electrons after treatment. In addition, the sharp edge of CNTs' top, after removal of the catalyst particles, may increase the local electronic field more effectively. The present study suggests that hydrogen plasma treatment is a useful method for improving the field electron emission property of CNTs

  10. Field-induced long-lived supermolecules

    DEFF Research Database (Denmark)

    -J. Huang, S.; -T. Hsu, Y.; Lee, H.

    2012-01-01

    We demonstrate that the long-lived bound states (super-molecules) can exist in the dilute limit when we tune the shape of effective potential between polar molecules by an external microwave field. Binding energies, average sizes, and phase diagrams for both s-orbital (bosons) and p-orbital (ferm...

  11. Geosynchronous magnetic field responses to fast solar wind dynamic pressure enhancements: MHD field model

    Directory of Open Access Journals (Sweden)

    T. R. Sun

    2012-08-01

    Full Text Available We performed global MHD simulations of the geosynchronous magnetic field in response to fast solar wind dynamic pressure (Pd enhancements. Taking three Pd enhancement events in 2000 as examples, we found that the main features of the total field B and the dominant component Bz can be efficiently predicted by the MHD model. The predicted B and Bz varies with local time, with the highest level near noon and a slightly lower level around mid-night. However, it is more challenging to accurately predict the responses of the smaller component at the geosynchronous orbit (i.e., Bx and By. In contrast, the limitations of T01 model in predicting responses to fast Pd enhancements are presented.

  12. Pair-breaking effects by parallel magnetic field in electric-field-induced surface superconductivity

    Science.gov (United States)

    Nabeta, Masahiro; Tanaka, Kenta K.; Onari, Seiichiro; Ichioka, Masanori

    2016-11-01

    We study paramagnetic pair-breaking in electric-field-induced surface superconductivity, when magnetic field is applied parallel to the surface. The calculation is performed by Bogoliubov-de Gennes theory with s-wave pairing, including the screening effect of electric fields by the induced carriers near the surface. Due to the Zeeman shift by applied fields, electronic states at higher-level sub-bands become normal-state-like. Therefore, the magnetic field dependence of Fermi-energy density of states reflects the multi-gap structure in the surface superconductivity.

  13. Propofol Enhances Hemoglobin-Induced Cytotoxicity in Neurons.

    Science.gov (United States)

    Yuan, Jing; Cui, Guiyun; Li, Wenlu; Zhang, Xiaoli; Wang, Xiaoying; Zheng, Hui; Zhang, Jian; Xiang, Shuanglin; Xie, Zhongcong

    2016-04-01

    It has been increasingly suggested that propofol protects against hypoxic-/ischemic-induced neuronal injury. As evidenced by hemorrhage-induced stroke, hemorrhage into the brain may also cause brain damage. Whether propofol protects against hemorrhage-induced brain damage remains unknown. Therefore, in this study, we investigated the effects of propofol on hemoglobin-induced cytotoxicity in cultured mouse cortical neurons. Neurons were prepared from the cortex of embryonic 15-day-old mice. Hemoglobin was used to induce cytotoxicity in the neurons. The neurons were then treated with propofol for 4 hours. Cytotoxicity was determined by lactate dehydrogenase release assay. Caspase-3 activation was examined by Western blot analysis. Finally, the free radical scavenger U83836E was used to examine the potential involvement of oxidative stress in propofol's effects on hemoglobin-induced cytotoxicity. We found that treatment with hemoglobin induced cytotoxicity in the neurons. Propofol enhanced hemoglobin-induced cytotoxicity. Specifically, there was a significant difference in the amount of lactate dehydrogenase release between hemoglobin plus saline (19.84% ± 5.38%) and hemoglobin plus propofol (35.79% ± 4.41%) in mouse cortical neurons (P = 0.00058, Wilcoxon Mann-Whitney U test, n = 8 in the control group or the treatment group). U83836E did not attenuate the enhancing effects of propofol on hemoglobin-induced cytotoxicity in the neurons, and propofol did not significantly affect caspase-3 activation induced by hemoglobin. These data suggested that caspase-3 activation and oxidative stress might not be the underlying mechanisms by which propofol enhanced hemoglobin-induced cytotoxicity. Moreover, these data suggested that the neuroprotective effects of propofol would be dependent on the condition of the brain injury, which will need to be confirmed in future studies. These results from our current proof-of-concept study should promote more research in vitro and in

  14. Electrical field stimulation-induced excitatory responses of ...

    African Journals Online (AJOL)

    effect of the endothelium on electrical field stimulation (EFS)-induced excitatory responses of pulmonary artery segments from pulmonary hypertensive rats. Methods: Pulmonary hypertension was induced in rats with a single dose of monocrotaline (60 mg/kg) and 21 days later, arterial rings were set up for isometric tension ...

  15. Enhancement of electric and magnetic wave fields at density gradients

    Directory of Open Access Journals (Sweden)

    A. Reiniusson

    2006-03-01

    Full Text Available We use Freja satellite data to investigate irregular small-scale density variations. The observations are made in the auroral region at about 1000-1700 km. The density variations are a few percent, and the structures are found to be spatial down to a scale length of a few ion gyroradii. Irregular density variations are often found in an environment of whistler mode/lower hybrid waves and we show that at the density gradients both the electric and magnetic wave fields are enhanced.

  16. Enhanced deterministic phase retrieval using a partially developed speckle field

    DEFF Research Database (Denmark)

    Almoro, Percival F.; Waller, Laura; Agour, Mostafa

    2012-01-01

    A technique for enhanced deterministic phase retrieval using a partially developed speckle field (PDSF) and a spatial light modulator (SLM) is demonstrated experimentally. A smooth test wavefront impinges on a phase diffuser, forming a PDSF that is directed to a 4f setup. Two defocused speckle...... intensity measurements are recorded at the output plane corresponding to axially-propagated representations of the PDSF in the input plane. The speckle intensity measurements are then used in a conventional transport of intensity equation (TIE) to reconstruct directly the test wavefront. The PDSF in our...

  17. Lipopolysaccharide (LPS)-Induced Autophagy Is Responsible for Enhanced Osteoclastogenesis.

    Science.gov (United States)

    Sul, Ok-Joo; Park, Hyun-Jung; Son, Ho-Jung; Choi, Hye-Seon

    2017-11-30

    We hypothesized that inflammation affects number and activity of osteoclasts (OCs) via enhancing autophagy. Lipopolysaccharide (LPS) induced autophagy, osteoclastogenesis, and cytoplasmic reactive oxygen species (ROS) in bone marrow-derived macrophages that were pre-stimulated with receptor activator of nuclear factor-κB ligand. An autophagy inhibitor, 3-methyladenine (3-MA) decreased LPS-induced OC formation and bone resorption, indicating that autophagy is responsible for increasing number and activity of OCs upon LPS stimulus. Knockdown of autophagy-related protein 7 attenuated the effect of LPS on OC-specific genes, supporting a role of LPS as an autophagy inducer in OC. Removal of ROS decreased LPS-induced OC formation as well as autophagy. However, 3-MA did not affect LPS-induced ROS levels, suggesting that ROS act upstream of phosphatidylinositol-4,5-bisphosphate 3-kinase in LPS-induced autophagy. Our results suggest the possible use of autophagy inhibitors targeting OCs to reduce inflammatory bone loss.

  18. Field-Induced Texturing of Ceramic Materials for Unparalleled Properties

    Science.gov (United States)

    2017-03-01

    6.2 High -Temperature DSC Characterization under Applied Magnetic Field 43 6.3 Magnetic Field Texturing of Epoxy Samples 45 6.4 Magnetic Field...noncubic alumina (Al2O3) through magnetic alignment of particles during forming and heat treatment, microwave-enhanced densification, and high -energy field...measured at a heating rate of 10 °C/min Figure 38 shows the ORNL DSC data under the absence of magnetic field (0 T) and the presence of a high -magnetic

  19. Theory of field induced incommensurability: CsFeCl3

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1986-01-01

    Using correlation theory for the singlet-doublet magnet CsFeCl3 in a magnetic field, a field induced incommensurate ordering along K-M is predicted without invoking dipolar effects. A fully self-consistent RPA theory gives Hc=44 kG in agreement with experiments at T=1.3K. Correlation and dipolar...

  20. Magnetic field induced assembling of nanoparticles in ferrofluidic ...

    Indian Academy of Sciences (India)

    Ferrofluids based on these fine particles were prepared with oleic acid as surfactant and kerosene as carrier. Ferrofluidic thin films were made on glass substrates and magnetic field induced laser transmission was studied. The pattern exhibited by the films under the influence of a magnetic field was observed with the help ...

  1. Electromagnetic field induced biological effects in humans.

    Science.gov (United States)

    Kaszuba-Zwoińska, Jolanta; Gremba, Jerzy; Gałdzińska-Calik, Barbara; Wójcik-Piotrowicz, Karolina; Thor, Piotr J

    2015-01-01

    Exposure to artificial radio frequency electromagnetic fields (EMFs) has increased significantly in recent decades. Therefore, there is a growing scientific and social interest in its influence on health, even upon exposure significantly below the applicable standards. The intensity of electromagnetic radiation in human environment is increasing and currently reaches astronomical levels that had never before experienced on our planet. The most influential process of EMF impact on living organisms, is its direct tissue penetration. The current established standards of exposure to EMFs in Poland and in the rest of the world are based on the thermal effect. It is well known that weak EMF could cause all sorts of dramatic non-thermal effects in body cells, tissues and organs. The observed symptoms are hardly to assign to other environmental factors occurring simultaneously in the human environment. Although, there are still ongoing discussions on non-thermal effects of EMF influence, on May 31, 2011--International Agency for Research on Cancer (IARC)--Agenda of World Health Organization (WHO) has classified radio electromagnetic fields, to a category 2B as potentially carcinogenic. Electromagnetic fields can be dangerous not only because of the risk of cancer, but also other health problems, including electromagnetic hypersensitivity (EHS). Electromagnetic hypersensitivity (EHS) is a phenomenon characterized by the appearance of symptoms after exposure of people to electromagnetic fields, generated by EHS is characterized as a syndrome with a broad spectrum of non-specific multiple organ symptoms including both acute and chronic inflammatory processes located mainly in the skin and nervous systems, as well as in respiratory, cardiovascular systems, and musculoskeletal system. WHO does not consider the EHS as a disease-- defined on the basis of medical diagnosis and symptoms associated with any known syndrome. The symptoms may be associated with a single source of EMF

  2. Magnetic Fields Induced in the Solid Earth and Oceans

    DEFF Research Database (Denmark)

    Kuvshinov, Alexei; Olsen, Nils

    Electromagnetic induction in the Earth's interior is an important contributor to the near-Earth magnetic field. Oceans play a special role in the induction, due to their relatively high conductance of large lateral variability. Electric currents that generate secondary magnetic fields are induced...... in the oceans by two different sources: by time varying external magnetic fields, and by motion of the conducting ocean water through the Earth's main magnetic field. Significant progress in the accurate and detailed prediction of magnetic fields induced by these sources has been achieved during the last years...... ocean circulation. Finally, we will discuss how the results of 3-D predictions can be utilized in geomagnetic field modeling and in a recovery of deep conductivity structures....

  3. Field-ball milling induced anisotropy in magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Poudyal, Narayan [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Altuncevahir, Baki [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chakka, Vamsi [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chen Kanghua [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Black, Truman D [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Liu, J Ping [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Ding, Yong [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2004-12-21

    Nd{sub 2}Fe{sub 14}B and Sm{sub 2}Co{sub 17} particles of submicrometre sizes have been prepared by ball milling in a magnetic field. Structural and magnetic characterization reveal that these submicrometre particles milled in a magnetic field, consisting of nanosize grains, exhibit strong magnetic anisotropy compared with the particles milled without a magnetic field. Based on in situ observations of the field-ball milling in a transparent container, the mechanism of field-induced anisotropy in the nanostructured hard magnetic particles is discussed. (rapid communication)

  4. Enhanced germination and gravitropism of soybean in a hypogeomagnetic field

    Science.gov (United States)

    Mo, Weichuan

    For the future manned space exploration, the duration of the missions would significantly in-crease. Investigating plant growth and development under the space environmental conditions is of essential importance for the food supply projects for the astronauts. Hypogeomagnetic field (HGMF), namely, extremely low magnetic field, is one of the main characters of the space environment. Germination is the first vital step of plant growth and development, which determines the final yield of plants. The effect of HGMF on plant growth, especially early ger-mination, still remains open. In this study, we established a hypogeomagnetic field (HGMF) incubation system, the remnant magnetic field inside no more than 250 nT. Soybean seeds were incubated at 25 in HGMF, and the very beginning of soybean germination, from water ab-sorbance of cotyledon to radicle emergence, was examined within 24 h. Our results showed that the germination ratio and weight ratio of emerged soybean radicles were markedly increased during germination in HGMF. Furthermore, the tropism angle of emerged radicle with gravity in HGMF was statistically smaller than that in GMF when the radicle direction was placed opposite to gravity before germination. These results indicate that the germination and gravit-ropism of soybean is enhanced in a hypogeomagnetic environment, This is a new finding about the early seed germination in such a low environmental magnetic field which is comparable to the magnetic field of Lunar Swirls on the Moon (a few hundred nT), and it might provide new perspectives on the space science researches concerning plant growth and food supply.

  5. Magnetic field induced augmented thermal conduction phenomenon in magneto nanocolloids

    OpenAIRE

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K.

    2015-01-01

    Magnetic field induced drastically augmented thermal conductivity of magneto nanocolloids involving magnetic oxide nanoparticles, viz. Fe2O3, Fe3O4, Nickel oxide (NiO), Cobalt oxide (Co3O4), dispersed in different base fluids (heat transfer oil, kerosene, and ethylene glycol) have been reported. Experiments reveal the augmented thermal transport under the external applied magnetic field, with kerosene based MNCs showing at relatively low magnetic field intensities as compared to the heat tran...

  6. A Study of Thermocurrent Induced Magnetic Fields in ILC Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Anthony C. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Cooley, Victoria [Univ. of Wisconsin, Madison, WI (United States)

    2014-03-31

    The case of axisymmetric ILC-type cavities with titanium helium vessels is investigated. A first-order estimate for magnetic field within the SRF current layer is presented. The induced magnetic field is found to be not more than 1.4x10-8 Tesla = 0.14 milligauss for the case of axial symmetry. Magnetic fields due to symmetry breaking effects are discussed.

  7. Current-Induced Effective Fields Detected by Magnetotrasport Measurements

    Science.gov (United States)

    Kawaguchi, Masashi; Shimamura, Kazutoshi; Fukami, Shunsuke; Matsukura, Fumihiro; Ohno, Hideo; Moriyama, Takahiro; Chiba, Daichi; Ono, Teruo

    2013-11-01

    We show that the angle-dependent Hall measurement is an effective method to determine the current-induced effective fields by investigating MgO/Fe/Ta and MgO/Fe/Pt/Ta multilayer structures. The experimentally obtained Hall resistance under a relatively large dc electrical current is well described by considering two components of current-induced effective fields, which may be related to the spin Hall effect and the Rashba effect. The directions of the effective fields are consistent with and their magnitudes are comparable to those reported previously for similar multilayer structures.

  8. Reorganization of microfilament structure induced by ac electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Cho, M.R.; Thatte, H.S.; Golan, D.E. [Harvard Medical School, Boston, MA (United States); Lee, R.C. [Univ. of Chicago, IL (United States)

    1996-11-01

    AC electric fields induce redistribution of integral membrane proteins. Cell-surface receptor redistribution does not consistently follow electric field lines and depends critically on the frequency of the applied ac electric fields, suggesting that mechanisms other than electroosmosis are involved. We hypothesized that cytoskeletal reorganization is responsible for electric field-induced cell-surface receptor redistribution, and used fluorescence video microscopy to study the reorganization of microfilaments in human hepatoma (Hep3B) cells exposed to low-frequency electric fields ranging in strength from 25 mV/cm to 20 V/cm (peak to peak). The frequency of the applied electric field was varied from 1 to 120 Hz and the field exposure duration from 1 to 60 min. In control cells, cytoplasmic microfilaments were aligned in the form of continuous parallel cables along the longitudinal axis of the cell. Exposure of cells to ac electric fields induced alterations in microfilament structure in a manner that depended on the frequency of the applied field. A 1 or 10 Hz ac field caused microfilament reorganization from continuous, aligned cable structures to discontinuous globular patches. In contrast, the structure of microfilaments in cells exposed to 20-120 Hz electric fields did not offer from that in control cells. The extent of microfilament reorganization increased nonlinearly with the electric field strength. The characteristic time for microfilament reorganization in cells exposed to a 1 Hz, 20 V/cm electric field was {approx} 5 min. Applied ac electric fields could initiate signal transduction cascades, which in turn cause reorganization of cytoskeletal structures. 39 refs., 5 figs., 1 tab.

  9. Modeling of electric-field enhancement at nodular defects in dielectric mirror coatings

    International Nuclear Information System (INIS)

    DeFord, J.F.; Kozlowski, M.R.

    1992-10-01

    In dielectric multilayer optical coatings, laser induced damage is often associated with μm-scale surface defects such as the well known nodule defect. The interaction mechanism of the laser light with the coating defects is not understood, however. Historically, laser damage has been associated with peaks in the standing-wave electric-field distribution within the multilayer films. In the present work we use a finite-difference time-domain electromagnetic modeling code to study the influence of 3-D nodule defects on the E-field distribution. The coating studied is a dielectric multilayer HR consisting of alternating quarter-wave layers of HfO 2 and SiO 2 at 1.06 μm. The nodule is modeled as a parabolic defect initiated at a spherical seed. The modeling results show that E-field enhancements as large as a factor of 4 can be present at the defects. The enhancement shows a complex dependence on the size, depth and dielectric constant of the seed material. In general, defects initiated ,by large, shallow seeds produce the largest E-fields. Voids at the nodule boundary influence the E-field distribution, but have a small effect on the peak field

  10. Electric-field Induced Microdynamics of Charged Rods

    Directory of Open Access Journals (Sweden)

    Kyongok eKang

    2014-12-01

    Full Text Available Electric-field induced phase/state transitions are observed in AC electric fields with small amplitudes and low frequencies in suspensions of charged fibrous viruses (fd, which are model systems for highly charged rod-like colloids. Texture- and particle-dynamics in these field-induced states, and on crossing transition lines, are explored by image time-correlation and dynamic light scattering, respectively. At relatively low frequencies, starting from a system within the isotropic-nematic coexistence region, a transition from a nematic to a chiral nematic is observed, as well as a dynamical state where nematic domains melt and reform. These transitions are preliminary due to field-induced dissociation/association of condensed ions. At higher frequencies a uniform state is formed that is stabilized by hydrodynamic interactions through field-induced electro-osmotic flow where the rods align along the field direction. There is a point in the field-amplitude versus frequency plane where various transition lines meet. This point can be identified as a non-equilibrium critical point, in the sense that a length scale and a time scale diverge on approach of that point. The microscopic dynamics exhibits discontinuities on crossing transition lines that were identified independently by means of image and signal correlation spectroscopy.

  11. Pair-breaking effects by parallel magnetic field in electric-field-induced surface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Nabeta, Masahiro, E-mail: nabeta@mp.okayama-u.ac.jp; Tanaka, Kenta K.; Onari, Seiichiro; Ichioka, Masanori

    2016-11-15

    Highlights: • Zeeman effect shifts superconducting gaps of sub-band system, towards pair-breaking. • Higher-level sub-bands become normal-state-like electronic states by magnetic fields. • Magnetic field dependence of zero-energy DOS reflects multi-gap superconductivity. - Abstract: We study paramagnetic pair-breaking in electric-field-induced surface superconductivity, when magnetic field is applied parallel to the surface. The calculation is performed by Bogoliubov-de Gennes theory with s-wave pairing, including the screening effect of electric fields by the induced carriers near the surface. Due to the Zeeman shift by applied fields, electronic states at higher-level sub-bands become normal-state-like. Therefore, the magnetic field dependence of Fermi-energy density of states reflects the multi-gap structure in the surface superconductivity.

  12. Pair-breaking effects by parallel magnetic field in electric-field-induced surface superconductivity

    International Nuclear Information System (INIS)

    Nabeta, Masahiro; Tanaka, Kenta K.; Onari, Seiichiro; Ichioka, Masanori

    2016-01-01

    Highlights: • Zeeman effect shifts superconducting gaps of sub-band system, towards pair-breaking. • Higher-level sub-bands become normal-state-like electronic states by magnetic fields. • Magnetic field dependence of zero-energy DOS reflects multi-gap superconductivity. - Abstract: We study paramagnetic pair-breaking in electric-field-induced surface superconductivity, when magnetic field is applied parallel to the surface. The calculation is performed by Bogoliubov-de Gennes theory with s-wave pairing, including the screening effect of electric fields by the induced carriers near the surface. Due to the Zeeman shift by applied fields, electronic states at higher-level sub-bands become normal-state-like. Therefore, the magnetic field dependence of Fermi-energy density of states reflects the multi-gap structure in the surface superconductivity.

  13. Investigations on magnetic field induced optical transparency in magnetic nanofluids

    Science.gov (United States)

    Mohapatra, Dillip Kumar; Philip, John

    2018-02-01

    We study the magnetic field induced optical transparency and its origin in magnetic nanoemulsion of droplets of average size ∼200 nm containing superparamagnetic iron oxide nanoparticles. Beyond a certain volume fraction (Φ > 0.0021) of magnetic nanoemulsion and a critical magnetic field (Hc1), the transmitted light intensity increases drastically and reaches a maximum at another critical magnetic field (Hc2), beyond which the transmitted light intensity decreases and reaches a plateau. Interestingly, the transmitted light intensity at Hc2 is found to increase linearly with Φ and the critical magnetic fields Hc1 and Hc2 follow power law decay with Φ (i.e. Hc ∼ Φ-x), with exponents 0.48 and 0.27, respectively. The light intensity recovers to its initial value when the magnetic field is switched off, indicating the perfect reversibility of the field induced transparency process. The observed straight line scattered patterns above Hc2, on a screen placed perpendicular to the incident beam, confirms the formation of rod like anisotropic nanostructures perpendicular to the direction of light propagation. The magneto-optical measurements in the emulsion confirm that the observed field induced transparency in magnetic emulsions for Φ > 0.0021 is due to the optical birefringence caused by the rod like nanostructures. The reduced birefringence is found to be proportional to the square of the applied magnetic field. This finding offers several possibilities in using magnetic nanofluids in tunable optical devices.

  14. Inducement and enhancement of multiple coherence resonances in ...

    Indian Academy of Sciences (India)

    JIANCHENG SHI

    2017-11-16

    Nov 16, 2017 ... Inducement and enhancement of multiple coherence resonances in unidirectionally coupled neural systems: Random and time-periodic coupling strength. JIANCHENG SHI, MIN LUO and CHUSHENG HUANG. ∗. College of Chemistry and Material Sciences, Guangxi Teachers Education University, ...

  15. Enhanced thermo-mechanical performance and strain-induced ...

    Indian Academy of Sciences (India)

    Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposite films ... School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea; School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea ...

  16. Enhanced thermo-mechanical performance and strain-induced ...

    Indian Academy of Sciences (India)

    Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposites 287. Figure 5. Plot of ln(ln(1/Y)) vs. 1000/T (K−1) to estimate the activation energy for thermal degradation of (a) PVC and (b) TiO2@PVC-5% nanocomposite films. Figure 6. Plot of relative weight loss vs.

  17. Caffeine Markedly Enhanced Radiation-Induced Bystander Effects

    Science.gov (United States)

    Jiang, Erkang; Wu, Lijun

    2009-04-01

    In this paper it is shown that incubation with 2 mM caffeine enhanced significantly the MN (micronucleus) formation in both the 1 cGy α-particle irradiated and non-irradiated bystander regions. Moreover, caffeine treatment made the non-irradiated bystander cells more sensitive to damage signals. Treated by c-PTIO(2-(4-carboxy-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), a nitric oxide (NO) scavenger, the MN frequencies were effectively inhibited, showing that nitric oxide might be very important in mediating the enhanced damage. These results indicated that caffeine enhanced the low dose α-particle radiation-induced damage in irradiated and non-irradiated bystander regions, and therefore it is important to investigate the relationship between the radiosensitizer and radiation-induced bystander effects (RIBE).

  18. Magnetically induced electric fields and currents in the circulatory system.

    Science.gov (United States)

    Tenforde, Thomas S

    2005-01-01

    Blood flow in an applied magnetic field gives rise to induced voltages in the aorta and other major arteries of the central circulatory system that can be observed as superimposed electrical signals in the electrocardiogram (ECG). The largest magnetically induced voltage occurs during pulsatile blood flow into the aorta, and results in an increased signal at the location of the T-wave in the ECG. Studies involving the measurement of blood pressure, blood flow rate, heart sounds, and cardiac valve displacements have been conducted with monkeys and dogs exposed to static fields up to 1.5 tesla (T) under conditions producing maximum induced voltages in the aorta. Results of these studies gave no indication of alterations in cardiac functions or hemodynamic parameters. Cardiac activity monitored by ECG biotelemetry during continuous exposure of rats to a 1.5-T field for 10 days gave no evidence for any significant changes relative to the 10 days prior to and following exposure. Theoretical modeling of magnetic field interactions with blood flow has included a complete solution of the equation describing the flow of an electrically conductive fluid in the presence of a magnetic field (the Navier-Stokes equation) using the finite element technique. Magnetically induced voltages and current densities as a function of the applied magnetic field strength have been calculated for the aorta and surrounding tissues structures, including the sinoatrial node. Induced current densities in the region of the sinoatrial node are predicted to be >100 mA/m2 at field levels >5 T in an adult human under conditions of maximum electrodynamic coupling with aortic blood flow. Magnetohydrodynamic interactions are predicted to reduce the volume flow rate of blood in the human aorta by a maximum of 1.3%, 4.9%, and 10.4% at field levels of 5, 10, and 15 T, respectively.

  19. Flow-enhanced pairing and other unusual effects in Fermi gases in synthetic gauge fields

    Science.gov (United States)

    Shenoy, Vijay B.

    2013-09-01

    Recent experiments on fermions in synthetic gauge fields result in systems with a spin-orbit coupling along one spatial axis, a detuning field, and a Zeeman field. We show theoretically that the presence of all three results in interesting and unusual phenomena in a system of interacting fermions (interactions described by a scattering length). For two fermions, bound states appear only over a certain range of the center-of-mass momenta. The deepest bound state appears at a nonzero center-of-mass momentum. For center-of-mass momenta without a bound state, the gauge field induces a resonance-like feature in the scattering continuum resulting in a large scattering phase shift. In the case of many particles, we demonstrate that the system, in a parameter range, shows flow-enhanced pairing, i.e., a Fulde-Farrell-Larkin-Ovchnnikov superfluid state made of robust pairs with a finite center-of-mass momentum. Yet another regime of parameters offers the opportunity to study strongly interacting normal states of spin-orbit-coupled fermionic systems utilizing the resonance-like feature induced by the synthetic gauge field.

  20. Terahertz-field-induced photoluminescence of nanostructured gold films

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Malureanu, Radu; Zalkovskij, Maksim

    2013-01-01

    We experimentally demonstrate photoluminescence from nanostructured ultrathin gold films subjected to strong single-cycle terahertz transients with peak electric field over 300 kV/cm. We show that UV-Vis-NIR light is being generated and the efficiency of the process is strongly enhanced at the pe......We experimentally demonstrate photoluminescence from nanostructured ultrathin gold films subjected to strong single-cycle terahertz transients with peak electric field over 300 kV/cm. We show that UV-Vis-NIR light is being generated and the efficiency of the process is strongly enhanced...

  1. Photon-induced near-field electron microscopy.

    Science.gov (United States)

    Barwick, Brett; Flannigan, David J; Zewail, Ahmed H

    2009-12-17

    In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved in both space (nanometre and below) and time (femtosecond). Here we report the development of photon-induced near-field electron microscopy (PINEM), and the associated phenomena. We show that the precise spatiotemporal overlap of femtosecond single-electron packets with intense optical pulses at a nanostructure (individual carbon nanotube or silver nanowire in this instance) results in the direct absorption of integer multiples of photon quanta (nhomega) by the relativistic electrons accelerated to 200 keV. By energy-filtering only those electrons resulting from this absorption, it is possible to image directly in space the near-field electric field distribution, obtain the temporal behaviour of the field on the femtosecond timescale, and map its spatial polarization dependence. We believe that the observation of the photon-induced near-field effect in ultrafast electron microscopy demonstrates the potential for many applications, including those of direct space-time imaging of localized fields at interfaces and visualization of phenomena related to photonics, plasmonics and nanostructures.

  2. Effect of magnetic field on the zero valent iron induced oxidation reaction

    International Nuclear Information System (INIS)

    Kim, Dong-hyo; Kim, Jungwon; Choi, Wonyong

    2011-01-01

    Highlights: → We investigate the zero valent iron induced oxidation in the presence of magnetic field. → The oxidative degradation of 4-chlorophenol is enhanced by the magnetic field. → ESR measurement confirms that more OH radicals are generated in the presence of magnetic field. → The magnetic field affects the mass transfer of O 2 and the recombination of radicals. - Abstract: The magnetic field (MF) effect on the zero valent iron (ZVI) induced oxidative reaction was investigated for the first time. The degradation of 4-chlorophenol (4-CP) in the ZVI system was employed as the test oxidative reaction. MF markedly enhanced the degradation of 4-CP with the concurrent production of chlorides. The consumption of dissolved O 2 by ZVI reaction was also enhanced in the presence of MF whereas the competing reaction of H 2 production from proton reduction was retarded. Since the ZVI-induced oxidation is mainly driven by the in situ generated hydroxyl radicals, the production of OH radicals was monitored by the spin trap method using electron spin resonance (ESR) spectroscopy. It was confirmed that the concentration of trapped OH radicals was enhanced in the presence of MF. Since both O 2 and Fe 0 are paramagnetic, the diffusion of O 2 onto the iron surface might be accelerated under MF. The magnetized iron can attract oxygen on itself, which makes the mass transfer process faster. As a result, the surface electrochemical reaction between Fe 0 and O 2 can be accelerated with the enhanced production of OH radicals. MF might retard the recombination of OH radicals as well.

  3. Spectrally Enhanced Lighting Program Implementation for Energy Savings: Field Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Kelly L.; Sullivan, Gregory P.; Armstrong, Peter R.; Richman, Eric E.; Matzke, Brett D.

    2006-08-22

    This report provides results from an evaluation PNNL conducted of a spectrally enhanced lighting demonstration project. PNNL performed field measurements and occupant surveys at three office buildings in California before and after lighting retrofits were made in August and December 2005. PNNL measured the following Overhead lighting electricity demand and consumption, Light levels in the workspace, Task lighting use, and Occupant ratings of satisfaction with the lighting. Existing lighting, which varied in each building, was replaced with lamps with correlated color temperature (CCT) of 5000 Kelvin, color rendering index (CRI) of 85, of varying wattages, and lower ballast factor electronic ballasts. The demonstrations were designed to decrease lighting power loads in the three buildings by 22-50 percent, depending on the existing installed lamps and ballasts. The project designers hypothesized that this reduction in electrical loads could be achieved by the change to higher CCT lamps without decreasing occupant satisfaction with the lighting.

  4. Elastodynamic cloaking and field enhancement for soft spheres

    Science.gov (United States)

    Diatta, Andre; Guenneau, Sebastien

    2016-11-01

    We propose a spherical cloak described by a non-singular asymmetric elasticity tensor {C} depending upon a small parameter η, that defines the softness of a region one would like to conceal from elastodynamic waves. By varying η, we generate a class of soft spheres dressed by elastodynamic cloaks, which are shown to considerably reduce the scattering of the soft spheres. Importantly, such cloaks also provide some wave protection except for a countable set of frequencies, for which some large elastic field enhancement can be observed within the soft spheres. Through an investigation of trapped modes in elasticity, we supply a good approximation of such Mie-type resonances by some transcendental equation. Our results, unlike previous studies that focused merely on the invisibility aspects, shed light on potential pitfalls of elastodynamic cloaks for earthquake protection designed via geometric transforms: a seismic cloak needs to be designed in such a way that its inner resonances differ from eigenfrequencies of the building one wishes to protect. In order to circumvent this downfall of field enhancement inside the cloaked area, we introduce a novel generation of cloaks, named here, mixed cloaks. Such mixed cloaks consist of a shell that detours incoming waves, hence creating an invisibility region, and of a perfectly matched layer (PML, located at the inner boundary of the cloaks) that absorbs residual wave energy in such a way that aforementioned resonances in the soft sphere are strongly attenuated. The designs of mixed cloaks with a non-singular elasticity tensor combined with an inner PML and non-vanishing density bring seismic cloaks one step closer to a practical implementation. Note in passing that the concept of mixed cloaks also applies in the case of singular cloaks and can be translated in other wave areas for a similar purpose (i.e. to smear down inner resonances within the invisibility region).

  5. Local field enhanced second-harmonic response of organic nanofibers

    DEFF Research Database (Denmark)

    Leißner, Till; Kostiučenko, Oksana; Fiutowski, Jacek

    Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron-beam lithogr......Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron......-beam lithography-defined regular arrays of gold, titanium and silicon oxide. As shown in a femtosecond laser scanning microscopy study the fiber-substrate interplay leads (only) on gold to a significantly enhanced SH signal. We suggest that this effect is driven by the local field enhancement i.e. the excitation...... of surface plasmon polaritons (SPP) and lightning rod effects, since in case of Ti and SiO2 no SPPs are excited at a laser wavelength of 790 nm and the used array dimensions. Furthermore, we observe a considerably reduced fluorescence lifetime for the fibers deposited on gold arrays supporting the assumption...

  6. Enhancing synchronization in chaotic oscillators by induced heterogeneity

    Science.gov (United States)

    Banerjee, Ranjib; Bera, Bidesh K.; Ghosh, Dibakar; Dana, Syamal Kumar

    2017-06-01

    We report enhancing of complete synchronization in identical chaotic oscillators when their interaction is mediated by a mismatched oscillator. The identical oscillators now interact indirectly through the intermediate relay oscillator. The induced heterogeneity in the intermediate oscillator plays a constructive role in reducing the critical coupling for a transition to complete synchronization. A common lag synchronization emerges between the mismatched relay oscillator and its neighboring identical oscillators that leads to this enhancing effect. We present examples of one-dimensional open array, a ring, a star network and a two-dimensional lattice of dynamical systems to demonstrate how this enhancing effect occurs. The paradigmatic Rössler oscillator is used as a dynamical unit, in our numerical experiment, for different networks to reveal the enhancing phenomenon.

  7. Sodium benzoate, potassium sorbate, and citric acid induce sublethal injury and enhance pulsed electric field inactivation of E. coli O157:H7 and nonpathogenic surrogate E. coli in strawberry juice

    Science.gov (United States)

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

  8. Mapping and correcting respiration-induced field changes in the brain using fluorine field probes

    DEFF Research Database (Denmark)

    Andersen, Mads; Madsen, Kristoffer; Hanson, Lars G.

    2014-01-01

    for a single volume was 11s, which was easily tolerated during a breath hold. The field probes were triggered to perform a measurement (3ms duration) 75 ms prior to the first excitation in each dynamic, when no scanner generated RF pulses or gradients were applied. In case of real-time shimming, the scanner......Purpose. Breathing induced dynamic B0 field perturbations in the head can lead to artefacts in ultra-high field MR by causing line broadening in spectroscopy and signal dropout, ghosting, displacement artifacts and blurring in imaging. It has recently been proposed to continuously stabilize...... the magnetic field by real-time updating of the shim fields, based on synchronous field measurements with external probes1,2. A thorough analysis of how accurate such field measurements at few (e.g. 16) positions outside the head can reflect the spatially varying dynamic fields inside the head is currently...

  9. Sub-microanalysis of solid samples with near-field enhanced atomic emission spectroscopy

    Science.gov (United States)

    Wang, Xiaohua; Liang, Zhisen; Meng, Yifan; Wang, Tongtong; Hang, Wei; Huang, Benli

    2018-03-01

    A novel approach, which we have chosen to name it as near-field enhanced atomic emission spectroscopy (NFE-AES), was proposed by introducing a scanning tunnelling microscope (STM) system into a laser-induced breakdown spectrometry (LIBS). The near-field enhancement of a laser-illuminated tip was utilized to improve the lateral resolution tremendously. Using the hybrid arrangement, pure metal tablets were analyzed to verify the performance of NFE-AES both in atmosphere and in vacuum. Due to localized surface plasmon resonance (LSPR), the incident electromagnetic field is enhanced and confined at the apex of tip, resulting in sub-micron scale ablation and elemental emission signal. We discovered that the signal-to-noise ratio (SNR) and the spectral resolution obtained in vacuum condition are better than those acquired in atmospheric condition. The quantitative capability of NFE-AES was demonstrated by analyzing Al and Pb in Cu matrix, respectively. Submicron-sized ablation craters were achieved by performing NFE-AES on a Si wafer with an Al film, and the spectroscopic information from a crater of 650 nm diameter was successfully obtained. Due to its advantage of high lateral resolution, NFE-AES imaging of micro-patterned Al lines on an integrated circuit of a SIM card was demonstrated with a sub-micron lateral resolution. These results reveal the potential of the NFE-AES technique in sub-microanalysis of solids, opening an opportunity to map chemical composition at sub-micron scale.

  10. Inducing Lift on Spherical Particles by Traveling Magnetic Fields

    Science.gov (United States)

    Mazuruk, Konstantin; Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Gravity induced sedimentation of suspensions is a serious drawback to many materials and biotechnology processes, a factor that can, in principle, be overcome by utilizing an opposing Lorentz body force. In this work we demonstrate the utility of employing a traveling magnetic field (TMF) to induce a lifting force on particles dispersed in the fluid. Theoretically, a model has been developed to ascertain the net force, induced by TMF, acting on a spherical body as a function of the fluid medium's electrical conductivity and other parameters. Experimentally, the model is compared to optical observations of particle motion in the presence of TMF.

  11. Field-effect enhanced triboelectric colloidal quantum dot flexible sensor

    Science.gov (United States)

    Meng, Lingju; Xu, Qiwei; Fan, Shicheng; Dick, Carson R.; Wang, Xihua

    2017-10-01

    Flexible electronics, which is of great importance as fundamental sensor and communication technologies for many internet-of-things applications, has established a huge market encroaching into the trillion-dollar market of solid state electronics. For the capability of being processed by printing or spraying, colloidal quantum dots (CQDs) play an increasingly important role in flexible electronics. Although the electrical properties of CQD thin-films are expected to be stable on flexible substrates, their electrical performance could be tuned for applications in flexible touch sensors. Here, we report CQD touch sensors employing polydimethylsiloxane (PDMS) triboelectric films. The electrical response of touching activity is enhanced by incorporating CQD field-effect transistors into the device architecture. Thanks to the use of the CQD thin film as a current amplifier, the field-effect CQD touch sensor shows a fast response to various touching materials, even being bent to a large curvature. It also shows a much higher output current density compared to a PDMS triboelectric touch sensor.

  12. Induced magnetic-field effects in inductively coupled plasmas

    International Nuclear Information System (INIS)

    Cohen, R.H.; Rognlien, T.D.

    1995-01-01

    In inductive plasma sources, the rapid spatial decay of the electric field arising from the skin effect produces a large radio frequency (RF) magnetic field via Faraday's law. We previously determined that this magnetic field leads to a reduction of the electron density in the skin region, as well as a reduction in the collisionless heating rate. The electron deficit leads to the formation of an electrostatic potential which pulls electrons in to restore quasineutrality. Here we calculate the electron density including both the induced and electrostatic fields. If the wave frequency is not too low, the ions respond only to the averaged fields, and hence the electrostatic field is oscillatory, predominantly at the second harmonic of the applied field. We calculate the potential required to establish a constant electron density, and compare with numerical orbit-code calculations. For times short compared to ion transit times, the quasineutral density is just the initial ion density. For timescales long enough that the ions can relax, the density profile can be found from the solution of fluid equations with an effective (ponderomotive-like) potential added. Although the time-varying electrostatic potential is an extra source of heating, the net effect of the induced magnetic and electrostatic fields through trapping, early turning, and direct heating is a significant reduction in collisionless heating for parameters of interest

  13. Field-enhanced electrodes for additive-injection non-thermal plasma (NTP) processor

    Science.gov (United States)

    Rosocha, Louis A [Los Alamos, NM; Ferreri, Vincent [Westminster, CO; Kim, Yongho [Los Alamos, NM

    2009-04-21

    The present invention comprises a field enhanced electrode package for use in a non-thermal plasma processor. The field enhanced electrode package includes a high voltage electrode and a field-enhancing electrode with a dielectric material layer disposed in-between the high voltage electrode and the field-enhancing electrode. The field-enhancing electrode features at least one raised section that includes at least one injection hole that allows plasma discharge streamers to occur primarily within an injected additive gas.

  14. ERRATUM Electron field emission from sp -induced insulating to ...

    Indian Academy of Sciences (India)

    Administrator

    Electron field emission from sp. 2. -induced insulating to metallic behaviour of amorphous carbon (a-C) films. Pitamber Mahanandia, P N Viswakarma, Prasad Vishnu Bhotla, S V Subramanyam and Karuna Kar Nanda. 2010 Bull. Mater. Sci. 33 pp 215–220. The MS received date should be read as “MS received 20 October ...

  15. Electron field emission from sp 2-induced insulating to metallic ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 33; Issue 3. Electron field emission from 2-induced insulating to metallic behaviour of amorphous carbon (-C) films. Pitamber Mahanandia P N Viswakarma Prasad Vishnu Bhotla S V Subramanyam Karuna Kar Nanda. Thin Films and Nanomatter Volume 33 Issue 3 ...

  16. Development of microwave-enhanced spark-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Ikeda, Yuji; Moon, Ahsa; Kaneko, Masashi

    2010-01-01

    We propose microwave-enhanced spark-induced breakdown spectroscopy with the same measurement and analysis processes as in laser-induced breakdown spectroscopy, but with a different plasma generation mechanism. The size and lifetime of the plasma generated can contribute to increased measurement accuracy and expand its applicability to industrial measurement, such as an exhaust gas analyzer for automobile engine development and its regulation, which has been hard to operate by laser at an engineering evaluation site. The use of microwaves in this application helps lower the cost, reduce the system size, and increase the ease of operation to make it commercially viable. A microwave frequency of 2.45 GHz was used to enhance the volume and lifetime of the plasma at atmospheric condition even at elevated pressure.

  17. Electric Field-Induced Phase Transitions in Ferroelectrics at Polymorphic Phase Boundaries

    Science.gov (United States)

    Iamsasri, Thanakorn

    was studied using in situ XRD under electric fields. For the first time, an equation to quantify domain reorientation in orthorhombic lattice was developed and applied to LNKN. In prior studies, equations had only been developed to quantify the degree of domain reorientation for tetragonal and rhombohedral lattices. The results from this work show that the degree of domain reorientation increases as the composition approaches the orthorhombic-tetragonal phase boundary. Moreover, the time and frequency dependence of field-induced phase transition in BTBZT was studied using time-resolved XRD. The field-induced phase transition in BT-BZT strongly depends on the frequency of the applied fields, which corresponds with the relaxor behaviors observed in the macroscopic properties such as polarization and strain as a function of electric field. The kinetics of the field-induced phase transition in BT-BZT were modeled by a modified Kolmogorov-Avrami-Ishibashi (KAI) equation. In contrast to prior works, this study utilized a Bayesian inference method to obtain the distribution of parameters in the modified KAI equation without additional assumptions on the distribution. Bayesian inference allows for more variety in distributions (e.g. asymmetry and multimodality), whereas prior works usually assumed the distribution to be Gaussian. In summary, the results from this research improve the current understanding of fieldinduced phase transition in ferroelectrics and relaxors. Specifically, it explores the structural evolution of ferroelectrics during the application of high electric fields - field amplitudes that are typically seen during the poling process. Since the poling process directly affects the piezoelectric properties, the study of field-induced phase transitions is essential for understanding the origins of enhanced properties at phase boundaries, which are important for engineering devices with desired properties.

  18. Enhanced Field Emission from Argon Plasma-Treated Ultra-sharp α-Fe2O3Nanoflakes

    Directory of Open Access Journals (Sweden)

    Zhang JX

    2009-01-01

    Full Text Available Abstract Hematite nanoflakes have been synthesized by a simple heat oxide method and further treated by Argon plasmas. The effects of Argon plasma on the morphology and crystal structures of nanoflakes were investigated. Significant enhancement of field-induced electron emission from the plasma-treated nanoflakes was observed. The transmission electron microscopy investigation shows that the plasma treatment effectively removes amorphous coating and creates plenty of sub-tips at the surface of the nanoflakes, which are believed to contribute the enhancement of emission. This work suggests that plasma treatment technique could be a direct means to improve field-emission properties of nanostructures.

  19. Rubrene analogues with the aggregation-induced emission enhancement behaviour

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Sørensen, Jakob Kryger; Fu, Xiaowei

    2014-01-01

    In the light of the principle of aggregation-induced emission enhancement (AIEE), the rubrene analogue with orange light-emitting properties is designed and synthesized by substituting the phenyl side groups of rubrene with thienyl groups. To the best of our knowledge, this is the first report on...... on the synthesis of rubrene with AIEE behaviour, thus paving the way for the development of light-emitting rubrene derivatives. This journal is...

  20. An engineered CARS substrate with giant field enhancement in crisscross dimer nanostructure.

    Science.gov (United States)

    Zhang, Jia; Chen, Shu; Wang, Junqiao; Mu, Kaijun; Fan, Chunzhen; Liang, Erjun; Ding, Pei

    2018-01-15

    We theoretically investigate the optical properties of a nanostructure consisting of the two identical and symmetrically arranged crisscrosses. A plasmonic Fano resonance is induced by a strong interplay between bright mode and dark modes, where the bright mode is due to electric dipole resonance while dark modes originate from the magnetic dipole induced by LC resonances. In this article, we find that the electric field "hotspots" corresponding to three different wavelengths can be positioned at the same spatial position, and its spectral tunability is achieved by changing geometric parameters. The crisscrosses system can be designed as a plasmonic substrate for enhancing Coherent Anti-Stokes Raman Scattering (CARS) signal. This discovery provides a new method to achieve single molecule detection. At the same time, it also has many important applications for multi-photon imaging and other nonlinear optical processes, such as four-wave mixing and stimulated Raman scattering.

  1. Spectral Characteristics of Induced Geoelectric Fields During Extreme Geomagnetic Conditions

    Science.gov (United States)

    Khanal, K.; Adhikari, B.

    2017-12-01

    The ground response to geomagnetic superstorms at high latitude region have been studied using wavelet analysis technique. Finnish Natural-Gas Pipeline is chosen as the site of study. Plane wave theory is used to estimate the geoelectric fields Ex and Ey using ground conductivity structure and the 10-sec sampled geomagnetic data as input. The validity of estimated data is also tested by using online Geoelectric Field Calculator Tool-CCMC-NASA. For all selected events, by using Morelet wavelet we have analysed the scalograms and global wavelet spectrum of the parameters and the results are compared with the prevailing S-Transform views in Geomagnetically Induced Current(GIC) studies. The induced geoelectric fields are found to possess spectral variability with different periodicities depending upon the storm phases. Further, We have used the modelled geoelectric field data to estimate Pipe to Soil Voltage at Mantsala by adopting the Distributed Source Transmission Line(DSTL) theory considering the analogy between pipeline and transmission lines. The pipeline corrosion hazard is then discussed in the light of spectral characteristics of induced geoelectric fields.

  2. Enhanced Soundings for Local Coupling Studies Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, Craig R [University at Albany, State University of New York; Santanello, Joseph A [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Gentine, Pierre [Columbia Univ., New York, NY (United States)

    2016-04-01

    This document presents initial analyses of the enhanced radiosonde observations obtained during the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility Enhanced Soundings for Local Coupling Studies Field Campaign (ESLCS), which took place at the ARM Southern Great Plains (SGP) Central Facility (CF) from June 15 to August 31, 2015. During ESLCS, routine 4-times-daily radiosonde measurements at the ARM-SGP CF were augmented on 12 days (June 18 and 29; July 11, 14, 19, and 26; August 15, 16, 21, 25, 26, and 27) with daytime 1-hourly radiosondes and 10-minute ‘trailer’ radiosondes every 3 hours. These 12 intensive operational period (IOP) days were selected on the basis of prior-day qualitative forecasts of potential land-atmosphere coupling strength. The campaign captured 2 dry soil convection advantage days (June 29 and July 14) and 10 atmospherically controlled days. Other noteworthy IOP events include: 2 soil dry-down sequences (July 11-14-19 and August 21-25-26), a 2-day clear-sky case (August 15-16), and the passing of Tropical Storm Bill (June 18). To date, the ESLCS data set constitutes the highest-temporal-resolution sampling of the evolution of the daytime planetary boundary layer (PBL) using radiosondes at the ARM-SGP. The data set is expected to contribute to: 1) improved understanding and modeling of the diurnal evolution of the PBL, particularly with regard to the role of local soil wetness, and (2) new insights into the appropriateness of current ARM-SGP CF thermodynamic sampling strategies.

  3. Apomorphine enhances harmaline-induced tremor in rats.

    Science.gov (United States)

    Ossowska, Krystyna; Głowacka, Urszula; Kosmowska, Barbara; Wardas, Jadwiga

    2015-06-01

    Harmaline-induced tremor is a well-known model of essential tremor in humans. The aim of the present study was to examine the influence of apomorphine, a non-selective dopamine receptor agonist, on the tremor induced by harmaline in rats. Propranolol (a first-line drug in essential tremor) was used as a reference compound. Tremor, locomotor activity and focused stereotypy were measured objectively using force plate actimeters. Tremor was analyzed using a Fourier transform to generate power spectra for rhythmic behavior. The tremor induced by harmaline administered at a dose of 15 mg/kg ip was associated with an increase in power in the 9-15 Hz band (AP2) and in the tremor index, calculated as a difference between AP2 and power in the 0-8 Hz band (AP1). Propranolol injected at a dose of 20mg/kg ip reversed both of these effects of harmaline. Apomorphine administered at the doses of 0.5 and 1mg/kg sc further enhanced AP2 and at the lower dose also the tremor index elevated by harmaline. This increase in AP2 was stronger than enhancement of locomotor activity induced by apomorphine in the harmaline-treated animals. The present study suggests that the dopamine agonist apomorphine enhances the tremor induced by harmaline, and this effect is at least partly independent of hyperactivity. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  4. Singularity analysis of potential fields to enhance weak anomalies

    Science.gov (United States)

    Chen, G.; Cheng, Q.; Liu, T.

    2013-12-01

    Geoanomalies generally are nonlinear, non-stationary and weak, especially in the land cover areas, however, the traditional methods of geoanomaly identification are usually based on linear theory. In past two decades, many power-law function models have been developed based on fractal concept in mineral exploration and mineral resource assessment, such that the density-area (C-A) model and spectrum-area model (S-A) suggested by Qiuming Cheng have played important roles in extracting geophysical and geochemical anomalies. Several power-law relationships are evident in geophysical potential fields, such as field value-distance, power spectrum-wave number as well as density-area models. The singularity index based on density-area model involves the first derivative transformation of the measure. Hence, we introduce the singularity analysis to develop a novel high-pass filter for extracting gravity and magnetic anomalies with the advantage of scale invariance. Furthermore, we suggest that the statistics of singularity indices can provide a new edge detection scheme for the gravity or magnetic source bodies. Meanwhile, theoretical magnetic anomalies are established to verify these assertions. In the case study from Nanling mineral district in south China and Qikou Depression in east China, compared with traditional geophysical filtering methods including multiscale wavelet analysis and total horizontal gradient methods, the singularity method enhances and extracts the weak anomalies caused by buried magmatic rocks more effectively, and provides more distinct boundary information of rocks. Moreover, the singularity mapping results have good correspondence relationship with both the outcropping rocks and known mineral deposits to support future mineral resource exploration. The singularity method based on fractal analysis has potential to be a new useful theory and technique for processing gravity and magnetic anomaly data.

  5. Light-induced gauge fields for ultracold atoms.

    Science.gov (United States)

    Goldman, N; Juzeliūnas, G; Öhberg, P; Spielman, I B

    2014-12-01

    Gauge fields are central in our modern understanding of physics at all scales. At the highest energy scales known, the microscopic universe is governed by particles interacting with each other through the exchange of gauge bosons. At the largest length scales, our Universe is ruled by gravity, whose gauge structure suggests the existence of a particle-the graviton-that mediates the gravitational force. At the mesoscopic scale, solid-state systems are subjected to gauge fields of different nature: materials can be immersed in external electromagnetic fields, but they can also feature emerging gauge fields in their low-energy description. In this review, we focus on another kind of gauge field: those engineered in systems of ultracold neutral atoms. In these setups, atoms are suitably coupled to laser fields that generate effective gauge potentials in their description. Neutral atoms 'feeling' laser-induced gauge potentials can potentially mimic the behavior of an electron gas subjected to a magnetic field, but also, the interaction of elementary particles with non-Abelian gauge fields. Here, we review different realized and proposed techniques for creating gauge potentials-both Abelian and non-Abelian-in atomic systems and discuss their implication in the context of quantum simulation. While most of these setups concern the realization of background and classical gauge potentials, we conclude with more exotic proposals where these synthetic fields might be made dynamical, in view of simulating interacting gauge theories with cold atoms.

  6. Stronger inducible defences enhance persistence of intraguild prey.

    Science.gov (United States)

    Kratina, Pavel; Hammill, Edd; Anholt, Bradley R

    2010-09-01

    1. Intraguild predation is widespread in nature despite its potentially destabilizing effect on food web dynamics. 2. Anti-predator inducible defences affect both birth and death rates of populations and have the potential to substantially modify food web dynamics and possibly increase persistence of intraguild prey. 3. In a chemostat experiment, we investigated the long-term effects of inducible defences on the dynamics of aquatic microbial food webs consisting of an intraguild predator, intraguild prey, and a basal resource. We controlled environmental conditions and selected strains of intraguild prey that varied in the strength of expressed inducible defences. 4. We found that intraguild prey with a stronger tendency to induce an anti-predator morphology persist for significantly longer periods of time. In addition, model selection analysis implied that flexibility in defensive phenotype (inducibility itself) is most likely the factor responsible for the enhanced persistence. 5. As patterns at the community level often emerge as a result of the life-history traits of individuals, we propose that inducible defences increase the persistence of populations and may contribute to the widespread occurrence of theoretically unstable intraguild predation systems in nature.

  7. Ultra-low dose naltrexone enhances cannabinoid-induced antinociception.

    Science.gov (United States)

    Paquette, Jay; Olmstead, Mary C; Olmstead, Mary

    2005-12-01

    Both opioids and cannabinoids have inhibitory effects at micromolar doses, which are mediated by activated receptors coupling to Gi/o-proteins. Surprisingly, the analgesic effects of opioids are enhanced by ultra-low doses (nanomolar to picomolar) of the opioid antagonist, naltrexone. As opioid and cannabinoid systems interact, this study investigated whether ultra-low dose naltrexone also influences cannabinoid-induced antinociception. Separate groups of Long-Evans rats were tested for antinociception following an injection of vehicle, a sub-maximal dose of the cannabinoid agonist WIN 55 212-2, naltrexone (an ultra-low or a high dose) or a combination of WIN 55 212-2 and naltrexone doses. Tail-flick latencies were recorded for 3 h, at 10-min intervals for the first hour, and at 15-min intervals thereafter. Ultra-low dose naltrexone elevated WIN 55 212-2-induced tail flick thresholds without extending its duration of action. This enhancement was replicated in animals receiving intraperitoneal or intravenous injections. A high dose of naltrexone had no effect on WIN 55 212-2-induced tail flick latencies, but a high dose of the cannabinoid 1 receptor antagonist SR 141716 blocked the elevated tail-flick thresholds produced by WIN 55 212-2+ultra-low dose naltrexone. These data suggest a mechanism of cannabinoid-opioid interaction whereby activated opioid receptors that couple to Gs-proteins may attenuate cannabinoid-induced antinociception and/or motor functioning.

  8. Air-Stable Field-Enhanced III-Nitride Photocathodes

    Science.gov (United States)

    Strittmatter, Robert; Blacksberg, Jordana; Nikzad, Shouleh; Dabiran, Amir; Wowchak, Andrew; Chow, Peter

    2005-03-01

    We report on recent investigations of Si delta-doping by molecular beam epitaxy (MBE) near the surface of p-type GaN films to attain high efficiency photocathodes for use in intensified ultraviolet imagers. These delta-layers are prepared to achieve effective negative electron affinity (NEA) without the use of low work function metal coatings, such as cesium, which are suitable only in ultra-high vacuum environments. Hall measurements, secondary ion mass spectrometry (SIMS), and capacitance-voltage (C-V) depth profiling reveal highly confined delta-layers with activated carrier densities in excess of 10^14 cm-2 as close as 2 nm from the semiconductor surface. When the delta-layer is biased relative to the bulk, a large field-enhancement of the photoelectron yield is observed. In addition to UV spectroscopic quantum efficiency data, we will present total electron yield measurements for these photocathodes under electron-beam bombardment at various incident energies.

  9. Gene electrotransfer enhanced by nanosecond pulsed electric fields

    Directory of Open Access Journals (Sweden)

    Siqi Guo

    2014-01-01

    Full Text Available The impact of nanosecond pulsed electric fields (nsPEFs on gene electrotransfer has not been clearly demonstrated in previous studies. This study was conducted to evaluate the influence of nsPEFs on the delivery of plasmids encoding luciferase or green fluorescent protein and subsequent expression in HACAT keratinocyte cells. Delivery was performed using millisecond electric pulses (msEPs with or without nsPEFs. In contrast to reports in the literature, we discovered that gene expression was significantly increased up to 40-fold by applying nsPEFs to cells first followed by one msEP but not in the opposite order. We demonstrated that the effect of nsPEFs on gene transfection was time restricted. The enhancement of gene expression occurred by applying one msEP immediately after nsPEFs and reached the maximum at posttreatment 5 minutes, slightly decreased at 15 minutes and had a residual effect at 1 hour. It appears that nsPEFs play a role as an amplifier without changing the trend of gene expression kinetics due to msEPs. The effect of nsPEFs on cell viability is also dependent on the specific pulse parameters. We also determined that both calcium independent and dependent mechanisms are involved in nsPEF effects on gene electrotransfer.

  10. A Comprehensive Model of Electric-Field-Enhanced Jumping-Droplet Condensation on Superhydrophobic Surfaces.

    Science.gov (United States)

    Birbarah, Patrick; Li, Zhaoer; Pauls, Alexander; Miljkovic, Nenad

    2015-07-21

    Superhydrophobic micro/nanostructured surfaces for dropwise condensation have recently received significant attention due to their potential to enhance heat transfer performance by shedding positively charged water droplets via coalescence-induced droplet jumping at length scales below the capillary length and allowing the use of external electric fields to enhance droplet removal and heat transfer, in what has been termed electric-field-enhanced (EFE) jumping-droplet condensation. However, achieving optimal EFE conditions for enhanced heat transfer requires capturing the details of transport processes that is currently lacking. While a comprehensive model has been developed for condensation on micro/nanostructured surfaces, it cannot be applied for EFE condensation due to the dynamic droplet-vapor-electric field interactions. In this work, we developed a comprehensive physical model for EFE condensation on superhydrophobic surfaces by incorporating individual droplet motion, electrode geometry, jumping frequency, field strength, and condensate vapor-flow dynamics. As a first step toward our model, we simulated jumping droplet motion with no external electric field and validated our theoretical droplet trajectories to experimentally obtained trajectories, showing excellent temporal and spatial agreement. We then incorporated the external electric field into our model and considered the effects of jumping droplet size, electrode size and geometry, condensation heat flux, and droplet jumping direction. Our model suggests that smaller jumping droplet sizes and condensation heat fluxes require less work input to be removed by the external fields. Furthermore, the results suggest that EFE electrodes can be optimized such that the work input is minimized depending on the condensation heat flux. To analyze overall efficiency, we defined an incremental coefficient of performance and showed that it is very high (∼10(6)) for EFE condensation. We finally proposed mechanisms

  11. COFFEE - Coherent Optical System Field Trial for Spectral Efficiency Enhancement

    DEFF Research Database (Denmark)

    Imran, Muhammad; Fresi, Francesco; Rommel, Simon

    2016-01-01

    The scope, aims, and contributions of the COFFEE project for spectral efficiency enhancement and market exposure are presented.......The scope, aims, and contributions of the COFFEE project for spectral efficiency enhancement and market exposure are presented....

  12. Microwave induced solubility enhancement of poorly water soluble atorvastatin calcium.

    Science.gov (United States)

    Maurya, Durgaprasad; Belgamwar, Veena; Tekade, Avinash

    2010-11-01

    The objective of the present investigation was to enhance the solubility and dissolution rate of atorvastatin calcium (ATR) by a solid dispersion technique using poly(ethylene glycol) 6000 (PEG 6000). Microwave energy was used to prepare an enhanced release dosage form of the poorly water soluble drug ATR with PEG 6000 as a hydrophilic carrier. After the microwave treatment, the drug and hydrophilic polymer get fused together to form a solid dispersion. An in-vivo study was performed to determine the lipid-lowering efficacy (cholesterol, high density lipoprotein and triglyceride) of the solid dispersions using a Triton-induced hypercholesterolemia model in rats. An increase in the solubility of ATR was observed with increasing concentration of PEG 6000. The optimized ratio for preparation of solid dispersions of ATR with PEG 6000 was 1:12 w/w by conventional fusion and the microwave induced fusion method. Differential scanning calorimetry and powder X-ray diffraction studies of the solid dispersions confirmed the conversion of some crystalline ATR into the amorphous form. Scanning electron microscopy images also showed conversion of some crystalline ATR into the amorphous form. The in-vitro study showed that solid dispersions increased the solubility and dissolution rate of ATR, and thus may improve its bioavailability compared with plain ATR. The solid dispersion formulation prepared by the microwave induced fusion method significantly (P<0.05) reduced serum lipid levels in phases I and II (18 h and 24 h) of the Triton test compared with plain ATR. The microwave induced fusion method could be considered as a simple, efficient method to prepare solid dispersions of ATR with significant enhancement of the in-vitro dissolution rate as well as in-vivo activity. © 2010 The Authors. JPP © 2010 Royal Pharmaceutical Society of Great Britain.

  13. Optimizing the effect of electric-field enhancement in nodular defects

    Science.gov (United States)

    He, Tao; Cheng, Xinbin; Zhang, Jinlong; Jiao, Hongfei; Ma, Bin; Wang, Zhanshan

    2017-05-01

    It has been verified that a broadband high-reflection (HR) film could restrain electric-field intensity (EFI) enhancement effect in the nodular defects at normal incidence. However, it's impossible to design an omnidirectional HR coatings to avoid the light penetration from all incident angles at oblique incidence. In this paper, the EFI enhancement is simulated by using a three-dimensional finite-difference time-domain (FDTD) code. Two types of polarizers that prevent light penetration at low and high incident angular range (IAR) are proposed to explore the influence of transmission band at different angles in the case of oblique incidence. The damage morphologies of nodules initiating from different diameter silica microspheres in polarizers reproduce the simulated EFI distributions very well. These results indicate that light penetration at high IAR rather than at low IAR contributes mostly to EFI enhancement. Then, the conclusion is proved further by the films with low and high IAR at normal incidence. Controlling the angle position of transmission band at small angle can reduce the EFI enhancement in the usual case and increase the laser-induced damage threshold (LIDT) of films.

  14. Graphene-based field effect transistors for radiation-induced field sensing

    Energy Technology Data Exchange (ETDEWEB)

    Di Gaspare, Alessandra, E-mail: alessandra.digaspare@lnf.infn.it [INFN-Laboratori Nazionali Frascati, Frascati, Rome (Italy); Valletta, Antonio [CNR-Istituto per la Microelettronica e i Microsistemi, TorVergata, Rome (Italy); Fortunato, Guglielmo [CNR-Istituto per la Microelettronica e i Microsistemi, TorVergata, Rome (Italy); INFN-Laboratori Nazionali Frascati, Frascati, Rome (Italy); Larciprete, Rosanna [CNR-Istituto di Sistemi Complessi, TorVergata, Rome (Italy); INFN-Laboratori Nazionali Frascati, Frascati, Rome (Italy); Mariucci, Luigi [CNR-Istituto per la Microelettronica e i Microsistemi, TorVergata, Rome (Italy); INFN-Laboratori Nazionali Frascati, Frascati, Rome (Italy); Notargiacomo, Andrea [CNR-Istituto di Fotonica e Nanotecnologie, Rome (Italy); INFN-Laboratori Nazionali Frascati, Frascati, Rome (Italy); Cimino, Roberto [INFN-Laboratori Nazionali Frascati, Frascati, Rome (Italy); CERN, Geneva (Switzerland)

    2016-07-11

    We propose the implementation of graphene-based field effect transistor (FET) as radiation sensor. In the proposed detector, graphene obtained via chemical vapor deposition is integrated into a Si-based field effect device as the gate readout electrode, able to sense any change in the field distribution induced by ionization in the underneath absorber, because of the strong variation in the graphene conductivity close to the charge neutrality point. Different 2-dimensional layered materials can be envisaged in this kind of device.

  15. In-plane magnetic field dependence of electric field-induced magnetization switching

    Science.gov (United States)

    Kanai, S.; Nakatani, Y.; Yamanouchi, M.; Ikeda, S.; Matsukura, F.; Ohno, H.

    2013-08-01

    Electric field-induced magnetization switching through magnetization precession is investigated as a function of in-plane component of external magnetic field for a CoFeB/MgO-based magnetic tunnel junction with perpendicular easy axis. The switching probability is an oscillatory function of the duration of voltage pulses and its magnitude and period depend on the magnitude of in-plane magnetic field. Experimental results are compared with simulated ones by using Landau-Lifshitz-Gilbert-Langevin equation, and possible factors determining the probability are discussed.

  16. Nanosecond KTN varifocal lens without electric field induced phase transition

    Science.gov (United States)

    Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Campbell, Adrian; Henry, Michael; Yin, Stuart (Shizhuo); Hoffman, Robert C.

    2017-08-01

    This paper presents a nanosecond speed KTN varifocal lens. The tuning principle of varifocal lens is based on the high-speed refractive index modulation from the nanosecond speed tunable electric field. A response time on the order of nanoseconds was experimentally demonstrated, which is the fastest varifocal lens reported so far. The results confirmed that the tuning speed of the KTN varifocal lens could be significantly increased by avoiding the electric field induced phase transition. Such a nanosecond speed varifocal lens can be greatly beneficial for a variety of applications that demand high speed axial scanning, such as high-resolution 3D imaging and high-speed 3D printing.

  17. Floating and flying ferrofluid bridges induced by external magnetic fields

    Science.gov (United States)

    Ma, Rongchao; Zhou, Yixin; Liu, Jing

    2015-04-01

    A ferrofluid is a mixture that exhibits both magnetism and fluidity. This merit enables the ferrofluid to be used in a wide variety of areas. Here we show that a floating ferrofluid bridge can be induced between two separated boards under a balanced external magnetic field generated by two magnets, while a flying ferrofluid bridge can be induced under an unbalanced external magnetic field generated by only one magnet. The mechanisms of the ferrofluid bridges were discussed and the corresponding mathematical equations were also established to describe the interacting magnetic force between the ferro particles inside the ferrofluid. This work answered a basic question that, except for the well-known floating water bridges that are related to electricity, one can also build up a liquid bridge that is related to magnetism.

  18. Multi-phase-field method for surface tension induced elasticity

    Science.gov (United States)

    Schiedung, Raphael; Steinbach, Ingo; Varnik, Fathollah

    2018-01-01

    A method, based on the multi-phase-field framework, is proposed that adequately accounts for the effects of a coupling between surface free energy and elastic deformation in solids. The method is validated via a number of analytically solvable problems. In addition to stress states at mechanical equilibrium in complex geometries, the underlying multi-phase-field framework naturally allows us to account for the influence of surface energy induced stresses on phase transformation kinetics. This issue, which is of fundamental importance on the nanoscale, is demonstrated in the limit of fast diffusion for a solid sphere, which melts due to the well-known Gibbs-Thompson effect. This melting process is slowed down when coupled to surface energy induced elastic deformation.

  19. Effects of Induced Electric Fields on Tissues and Cells

    Science.gov (United States)

    Sequin, Emily Katherine

    Cancer remains a substantial health burden in the United States. Traditional treatments for solid malignancies may include chemotherapy, radiation therapy, targeted therapies, or surgical resection. Improved surgical outcomes coincide with increased information regarding the tumor extent in the operating room. Furthermore, pathological examination and diagnosis is bettered when the pathologist has additional information about lesion locations on the large resected specimens from which they take a small sample for microscopic evaluation. Likewise, cancer metastasis is a leading cause of cancer death. Fully understanding why a particular tumor becomes metastatic as well as the mechanisms of cell migration are critical to both preventing metastasis and treating it. This dissertation utilizes the complex interactions of induced electric fields with tissues and cells to meet two complementary research goals. First, eddy currents are induced in tissues using a coaxial eddy current probe (8mm diameter) in order to distinguish tumor tissue from surrounding normal tissue to address the needs of surgeons performing curative cancer resections. Measurements on animal tissue phantoms characterize the eddy current measurement finding that the effective probing area corresponds to about twice the diameter of the probe and that the specimen temperature must be constant for reliable measurements. Measurements on ten fresh tissue specimens from human patients undergoing surgical resection for liver metastases from colorectal cancer showed that the eddy current measurement technique can be used to differentiate tumors from surrounding liver tissue in a non-destructive, non-invasive manner. Furthermore, the differentiation between the tumor and normal tissues required no use of contrast agents. Statistically significant differences between eddy current measurements in three tissue categories, tumor, normal, and interface, were found across patients using a Tukey's pairwise comparison

  20. Measurement of full-field deformation induced by a dc electrical field in organic insulator films

    Directory of Open Access Journals (Sweden)

    Boudou L.

    2010-06-01

    Full Text Available Digital image correlation method (DIC using the correlation coefficient curve-fitting for full-field surface deformation measurements of organic insulator films is investigated in this work. First the validation of the technique was undertaken. The computer-generated speckle images and the measurement of coefficient of thermal expansion (CTE of aluminium are used to evaluate the measurement accuracy of the technique. In a second part the technique is applied to measure the mechanical deformation induced by electrical field application to organic insulators. For that Poly(ethylene naphthalene 2,6-dicarboxylate (PEN thin films were subjected to DC voltage stress and DIC provides the full-field induced deformations of the test films. The obtained results show that the DIC is a practical and robust tool for better comprehension of mechanical behaviour of the organic insulator films under electrical stress.

  1. Pressure-induced superconductivity in a ferromagnet, UGe sub 2 : resistivity measurements in a magnetic field

    CERN Document Server

    Kobayashi, T C; Tateiwa, N; Amaya, K; Haga, Y; Settai, R; Onuki, Y

    2002-01-01

    Electrical resistivity measurements in a magnetic field are carried out on UGe sub 2 which exhibits pressure-induced superconductivity. The superconductivity is observed from 1.06 to 1.44 GPa. In the temperature and field dependences of the resistivity at P > P sub C where the ferromagnetic ordering disappears, it is observed that the application of an external field along the a-axis increases the coefficient A of the Fermi-liquid behaviour (propor to AT sup 2) abruptly - corresponding to the metamagnetic transition. The characteristic enhancement of H sub C sub 2 is reconfirmed for H || a-axis. The upper critical field of H sub C sub 2 is anisotropic: H sub C sub 2 (T) exhibits positive curvature for H || b-axis and H || c-axis.

  2. Irradiation-enhanced and-induced mass transport

    International Nuclear Information System (INIS)

    Rehn, L.E.

    1989-01-01

    Irradiation can be used to enhance diffusion, that is, to increase the rate at which equilibrium is attained, as well as to induce nonequilibrium changes. The main factors influencing whether irradiation will drive a material toward or away from equilibrium are the initial specimen microstructure and geometry, irradiation temperature, and primary recoil spectrum. This paper summarizes known effects of irradiation temperature and primary recoil spectrum on mass transport during irradiation. In comparison to either electron or heavy-ion irradiation, it is concluded that relatively low-energy, light-ion bombardment at intermediate temperatures offers the greatest potential to enhance the rate at which equilibrium is attained. The greatest departures from equilibrium can be expected from irradiation with similar particles at very low temperatures

  3. Entanglement via atomic coherence induced by two strong classical fields

    Science.gov (United States)

    Lü, Xin-You; Huang, Pei; Yang, Wen-Xing; Yang, Xiaoxue

    2009-09-01

    Based on the standard criteria [P. van Loock and A. Furusawa, Phys. Rev. A 67, 052315 (2003)], we propose a scheme to achieve the fully tripartite continuous-variable (CV) entanglement in a Y -type atomic system driven by two strong classical fields. By numerically simulating the dynamics of system, we show that the generation of entanglement does not depend intensively on the initial condition of cavity field and the time for which the cavity modes remain entangled can be prolonged via enhancing the intensities of classical fields in our scheme. Moreover, our numerical results also show that a tripartite entanglement amplifier can be realized in the present scheme. The present research provides an efficient approach to achieve fully tripartite CV entangled state even when the three entangled modes have different frequencies and initial states, which may be useful for the progress of quantum information networks with many nodes.

  4. Field-enhanced route to generating anti-Frenkel pairs in HfO2

    Science.gov (United States)

    Schie, Marcel; Menzel, Stephan; Robertson, John; Waser, Rainer; De Souza, Roger A.

    2018-03-01

    The generation of anti-Frenkel pairs (oxygen vacancies and oxygen interstitials) in monoclinic and cubic HfO2 under an applied electric field is examined. A thermodynamic model is used to derive an expression for the critical field strength required to generate an anti-Frenkel pair. The critical field strength of EaFcr˜101GVm-1 obtained for HfO2 exceeds substantially the field strengths routinely employed in the forming and switching operations of resistive switching HfO2 devices, suggesting that field-enhanced defect generation is negligible. Atomistic simulations with molecular static (MS) and molecular dynamic (MD) approaches support this finding. The MS calculations indicated a high formation energy of Δ EaF≈8 eV for the infinitely separated anti-Frenkel pair, and only a decrease to Δ EaF≈6 eV for the adjacent anti-Frenkel pair. The MD simulations showed no defect generation in either phase for E <3 GVm-1 , and only sporadic defect generation in the monoclinic phase (at E =3 GVm-1 ) with fast (trec<4 ps ) recombination. At even higher E but below EaFcr both monoclinic and cubic structures became unstable as a result of field-induced deformation of the ionic potential wells. Further MD investigations starting with preexisting anti-Frenkel pairs revealed recombination of all pairs within trec<1 ps , even for the case of neutral vacancies and charged interstitials, for which formally there is no electrostatic attraction between the defects. In conclusion, we find no physically reasonable route to generating point-defects in HfO2 by an applied field.

  5. Computations of wind-driven ocean-induced magnetic fields

    Science.gov (United States)

    Sachl, Libor; Einspigel, David; Martinec, Zdenek

    2016-04-01

    We present the results of computations of the secondary magnetic field induced by ocean motions. Ocean velocities are computed using the baroclinic ocean model LSOMG. The velocities are then used to determine the Lorentz force which is plugged into the magnetic induction code TLAM as a principal forcing. The TLAM is a 2D magnetic induction code based on the thin-shell approximation (Vivier et al., 2004; Tyler et al., 1997). In this approximation, the equation of magnetic induction simplifies significantly, time derivatives of main and induced magnetic fields are neglected as well as the self-induction term. The price for simplification of governing equations is the limited applicability of the resulting system. It is only suitable for slowly evolving processes. In order to meet the condition, we restrict ourselves to the wind (buoyancy) driven ocean circulation, although the LSOMG model is able to model both tidally- and wind-driven circulations. We assess the accuracy of thin-shell approximation in our setup by comparing the results with the Swarm satellite magnetic data. References Tyler, R. H., Mysak, L. A., and Oberhuber, J. M, 1997. Electromagnetic fields generated by a three dimensional global ocean circulation. J. Geophys. Res., 102, 5531-5551. Vivier, F., Meier-Reimer, E., and Tyler, R. H., 2004. Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow? Geophys. Res. Lett., 31, L10306, doi:10.1029/2004GL019804.

  6. WE-G-BRD-05: Inline Magnetic Fields Enhance Tumor Dose for Small Lung Cancers

    International Nuclear Information System (INIS)

    Oborn, B; Ge, Y; Hardcastle, N; Metcalfe, P; Keall, P

    2015-01-01

    Purpose: To report on significant dose enhancement effects caused by magnetic fields aligned parallel to 6MV photon beam radiotherapy of small lung tumors. Findings are applicable to future inline MRI-guided radiotherapy systems. Methods: 9 clinical lung plans were recalculated using Monte Carlo methods and external inline (parallel to the beam direction) magnetic fields of 0.5 T, 1.0 T and 3 T were included. Three plans were 6MV 3D-CRT and six were 6MV IMRT. The GTV’s ranged from 0.8 cc to 73 cc, while the PTV ranged from 1 cc to 180 cc. Results: The inline magnetic field has a moderate impact in lung dose distributions by reducing the lateral scatter of secondary electrons and causing a small local dose increase. Superposition of multiple small beams acts to superimpose the small dose increases and can lead to significant dose enhancements, especially when the GTV is low density. Two plans with very small, low mean density GTV’s (<1 cc, ρ(mean)<0.35g/cc) showed uniform increases of 16% and 23% at 1 T throughout the PTV. Three plans with moderate mean density PTV’s (3–13 cc, ρ(mean)=0.58–0.67 g/cc) showed 6% mean dose enhancement at 1 T in the PTV, however not uniform throughout the GTV/PTV. Replanning would benefit these cases. The remaining 5 plans had large dense GTV’s (∼ 1 g/cc) and so only a minimal (<2%) enhancement was seen. In general the mean dose enhancement at 0.5 T was 60% less than 1 T, while 5–50% higher at 3 T. Conclusions: A paradigm shift in the efficacy of small lung tumor radiotherapy is predicted with future inline MRI-linac systems. This will be achieved by carefully taking advantage of the reduction of lateral electronic disequilibrium withing lung tissue that is induced naturally inside strong inline magnetic fields

  7. Gate induced drain leakage reduction with analysis of gate fringing field effect on high-κ/metal gate CMOS technology

    Science.gov (United States)

    Jang, Esan; Shin, Sunhae; Jung, Jae Won; Rok Kim, Kyung

    2015-06-01

    We suggest the optimum permittivity for a high-κ/metal gate (HKMG) CMOS structure based on the trade-off characteristics between the fringing field induced barrier lowering (FIBL) and gate induced drain leakage (GIDL). By adopting the high-κ gate dielectric, the GIDL from the band-to-band tunneling at the interface of gate and lightly doped drain (LDD) is suppressed with wide tunneling width owing to the enhanced fringing field, while the FIBL effects is degenerated as the previous reports. These two effects from the gate fringing field are studied extensively to manage the leakage current of HKMG for low power applications.

  8. Field induced heliconical structure of cholesteric liquid crystal

    Science.gov (United States)

    Lavrentovich, Oleg D.; Shiyanovsii, Sergij V.; Xiang, Jie; Kim, Young-Ki

    2017-06-27

    A diffraction grating comprises a liquid crystal (LC) cell configured to apply an electric field through a cholesteric LC material that induces the cholesteric LC material into a heliconical state with an oblique helicoid director. The applied electric field produces diffracted light from the cholesteric LC material within the visible, infrared or ultraviolet. The axis of the heliconical state is in the plane of the liquid crystal cell or perpendicular to the plane, depending on the application. A color tuning device operates with a similar heliconical state liquid crystal material but with the heliconical director axis oriented perpendicular to the plane of the cell. A power generator varies the strength of the applied electric field to adjust the wavelength of light reflected from the cholesteric liquid crystal material within the visible, infrared or ultraviolet.

  9. The Bloch equation with terms induced by an electric field

    Science.gov (United States)

    Garbacz, Piotr

    2018-01-01

    The Bloch equation of the nuclear magnetization of spin-1/2 nuclei in molecules, which have permanent electric dipole moments μe that are placed simultaneously in a magnetic field B and an electric field E, is derived. It is shown that if the principal components of the nuclear magnetic shielding tensor σ and the dipole moment μe are known, then the measurement of the transverse component to the magnetic field B of the nuclear magnetization, which is induced by the application of the electric field oscillating at the half of the spin precession frequency, allows determining the orientation of the dipole moment μe with respect to the principal axis system of the symmetric part of the tensor σ. Four-component relativistic density functional theory computations, which have been performed for several molecules containing heavy nuclei, i.e., 207Pb, 205Tl, 199Hg, 195Pt, and 125Te, indicate that coefficients of the relaxation matrix perturbed by the electric field E are in favorable cases of the order of 1000 pm2 V-2 T-2. Therefore, the spin dynamics is perturbed at experimentally observable levels for the strengths of electric and magnetic fields E = 5 kV/mm and B = 10 T, respectively.

  10. Field-induced transitions in DySb

    International Nuclear Information System (INIS)

    Brun, T.O.; Lander, G.H.; Korty, F.W.; Kouvel, J.S.

    1974-01-01

    The NaCl-structured compound DySb, which in zero field transforms abruptly at T/sub N/ approximately 9.5 0 K to a Type-II antiferromagnetic (A) state with a nearly tetragonal lattice distortion, was previously found to exhibit rapid field-induced changes in magnetization at 1.5 0 K. The field-induced transitions in a DySb crystal have been studied by neutron diffraction and magnetization measurements in fields up to approximately 60 kOe applied parallel to each of the principal axes. In the broken bracket 100 broken bracket case, the transition from the A to an intermediate ferrimagnetic (Q) state is first-order at 4.2 0 K (critical field H/sub c/ approximately 21 kOe) but is continuous from approximately 6 0 K up to T/sub N/: as H/sub c/ → 0. The Q-to-paramagnetic (P) transition is rapid but continuous at 4.2 0 K (H/sub c/ approximately 40 kOe) and becomes broad as T/sub N/ is approached. In the broken bracket 110 broken bracket case the A-to-Q transition remains essentially first-order from 4.2 0 K (H/sub c/ approximately 15 kOe) up to T/sub N/; above T/sub N/ rapid P-to-Q transitions occur at very high fields. The magnetic structure of the Q state is found to be that of HoP. (U.S.)

  11. Magnetic-Field-Enhanced Incommensurate Magnetic Order in the Underdoped High-Temperature Superconductor YBa2Cu3O6.45

    DEFF Research Database (Denmark)

    Haug, D.; Hinkov, V.; Suchaneck, A.

    2009-01-01

    We present a neutron-scattering study of the static and dynamic spin correlations in the underdoped high-temperature superconductor YBa2Cu3O6.45 in magnetic fields up to 15 T. The field strongly enhances static incommensurate magnetic order at low temperatures and induces a spectral-weight shift...

  12. Field angle dependence of voltage-induced ferromagnetic resonance under DC bias voltage

    International Nuclear Information System (INIS)

    Shiota, Yoichi; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Suzuki, Yoshishige; Yuasa, Shinji

    2016-01-01

    We studied the rectification function of microwaves in CoFeB/MgO-based magnetic tunnel junctions using voltage-induced ferromagnetic resonance (FMR). Our findings reveal that the shape of the structure of the spectrum depends on the rotation angle of the external magnetic field, providing clear evidence that FMR dynamics are excited by voltage-induced magnetic anisotropy changes. Further, enhancement of the rectified voltage was demonstrated under a DC bias voltage. In our experiments, the highest microwave detection sensitivity obtained was 350 mV/mW, at an RF frequency of 1.0 GHz and field angle of θ H =80°, ϕ H =0°. The experimental results correlated with those obtained via simulation, and the calculated results revealed the magnetization dynamics at the resonance state. - Highlights: • Examined voltage-induced ferromagnetic resonance (FMR) under various field angles. • FMR dynamics are excited by voltage-induced magnetic anisotropy changes. • Microwave detection sensitivity depends on input RF and elevation angle. • Microwave detection sensitivity=350 mV/mW at RF=1.0 GHz, θ H =80°, ϕ H =0°.

  13. ‘Ecstasy’ Enhances Noise-Induced Hearing Loss

    Science.gov (United States)

    Church, Michael W.; Zhang, Jinsheng S.; Langford, Megan M.; Perrine, Shane A.

    2013-01-01

    ‘Ecstasy’ or 3,4-methylenedioxy-N-methamphetamine (MDMA) is an amphetamine abused for its euphoric, empathogenic, hallucinatory, and stimulant effects. It is also used to treat certain psychiatric disorders. Common settings for Ecstasy use are nightclubs and “rave” parties where participants consume MDMA and dance to loud music. One concern with the club setting is that exposure to loud sounds can cause permanent sensorineural hearing loss. Another concern is that consumption of MDMA may enhance such hearing loss. Whereas this latter possibility has not been investigated, this study tested the hypothesis that MDMA enhances noise-induced hearing loss (NIHL) by exposing rats to either MDMA, noise trauma, both MDMA and noise, or neither treatment. MDMA was given in a binge pattern of 5 mg/kg per intraperitoneal injections every 2 h for a total of four injections to animals in the two MDMA-treated groups (MDMA-only and Noise+MDMA). Saline injections were given to the animals in the two non-MDMA groups (Control and Noise-only). Following the final injection, noise trauma was induced by a 10 kHz tone at 120 dB SPL for 1 h to animals in the two noise trauma-treated groups (Noise-only and Noise+MDMA). Hearing loss was assessed by the auditory brainstem response (ABR) and cochlear histology. Results showed that MDMA enhanced NIHL compared to Noise-only and that MDMA alone caused no hearing loss. This implies that “clubbers” and “rave-goers” are exacerbating the amount of NIHL when they consume MDMA and listen to loud sounds. In contrast to earlier reports, the present study found that MDMA by itself caused no changes in the click-evoked ABR’s wave latencies or amplitudes. PMID:23711768

  14. Surface plasmon-enhanced localized electric field in organic light-emitting diodes by incorporating silver nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ying-Chung; Gao, Chia-Yuan [Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Chen, Kan-Lin [Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung, Taiwan (China); Huang, Chien-Jung, E-mail: chien@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan (China)

    2014-03-01

    Highlights: • A higher luminance and electron-injection ability are obtained when the mean cluster size of SNCs is 34 nm. • SPRE is the crucial factor to contribute the electron injection. • SPRE induced the enhanced localized electric field around the Ag NPs. - Abstract: The influence of silver nanoclusters (SNCs) on the performance of organic light-emitting diodes is investigated in this study. The SNCs are introduced between the electron-injection layer and cathode alumina by means of thermal evaporation, resulting that different absorption peaks of SNCs were formed. A higher luminance and electron-injection ability are obtained when the mean cluster size is 34 nm. The surface-enhanced Raman scattering spectroscopy reveals that the localized electric field around the SNCs is enhanced, resulting in an increase in electron injection from cathode electrode.

  15. High magnetic field induced otolith fusion in the zebrafish larvae.

    Science.gov (United States)

    Pais-Roldán, Patricia; Singh, Ajeet Pratap; Schulz, Hildegard; Yu, Xin

    2016-04-11

    Magnetoreception in animals illustrates the interaction of biological systems with the geomagnetic field (geoMF). However, there are few studies that identified the impact of high magnetic field (MF) exposure from Magnetic Resonance Imaging (MRI) scanners (>100,000 times of geoMF) on specific biological targets. Here, we investigated the effects of a 14 Tesla MRI scanner on zebrafish larvae. All zebrafish larvae aligned parallel to the B0 field, i.e. the static MF, in the MRI scanner. The two otoliths (ear stones) in the otic vesicles of zebrafish larvae older than 24 hours post fertilization (hpf) fused together after the high MF exposure as short as 2 hours, yielding a single-otolith phenotype with aberrant swimming behavior. The otolith fusion was blocked in zebrafish larvae under anesthesia or embedded in agarose. Hair cells may play an important role on the MF-induced otolith fusion. This work provided direct evidence to show that high MF interacts with the otic vesicle of zebrafish larvae and causes otolith fusion in an "all-or-none" manner. The MF-induced otolith fusion may facilitate the searching for MF sensors using genetically amenable vertebrate animal models, such as zebrafish.

  16. Laser-induced breakdown spectroscopy enhanced by a micro torch.

    Science.gov (United States)

    Liu, L; Huang, X; Li, S; Lu, Yao; Chen, K; Jiang, L; Silvain, J F; Lu, Y F

    2015-06-01

    A commercial butane micron troch was used to enhance plasma optical emissions in laser-induced breakdown spectroscopy (LIBS). Fast imaging and spectroscopic analyses were used to observe plasma evolution in the atmospheric pressure for LIBS without and with using a micro torch. Optical emission intensities and signal-to-noise ratios (SNRs) as functions of delay time were studied. Enhanced optical emission and SNRs were obtained by using a micro torch. The effects of laser pulse energy on the emission intensities and SNRs were studied. The same spectral intensity could be obtained using micro torch with much lower laser pulse energy. The investigation of SNR evolution with delay time at different laser pulse energies showed that the SNR enhancement factor is higher for plasmas generated by lower laser pulse energies than those generated by higher laser energies. The calibration curves of emission line intensities with elemental concentrations showed that detection sensitivities of Mn I 404.136 nm and V I 437.923 nm were improved by around 3 times. The limits of detection for both Mn I 404.136 nm and V I 437.923 nm are reduced from 425 and 42 ppm to 139 and 20 ppm, respectively, after using the micro torch. The LIBS system with micro torch was demonstrated to be cost-effective, compact, and capable of sensitivity improvement, especially for LIBS system operating with low laser pulse energy.

  17. Enhanced impurity-limited mobility in ultra-scaled Si nanowire junctionless field-effect transistors

    Science.gov (United States)

    Ueda, Akiko; Luisier, Mathieu; Sano, Nobuyuki

    2015-12-01

    We examine the transport properties of heavily doped ultra-scaled Si junctionless nanowire field-effect transistors, by means of atomistic quantum transport simulations based on the s p 3 d 5 s ∗ tight-binding model, the nonequilibrium Green's function formalism, and including electron-phonon scattering. Each individual doping atom is treated explicitly and its potential is determined by solving the Poisson equation. The impurity atoms are assumed to be aligned along a single line or to slightly vary from this well-ordered configuration. We find that the impurity-limited mobility enhances as the carrier concentration increases due to the screening effect. The mobility also improves with the doping concentration because closely placed impurities induce resonant tunneling states that positively affect the current magnitude. This behavior is found to persist even in the case of slight disorder.

  18. Mapping of electromagnetic fields enhanced by gold nanostructures

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiučenko, Oksana

    2012-01-01

    Laser ablation of an ‘imaging’ polymer layer allows near-field mapping of metal nanostructures with subdiffraction resolution......Laser ablation of an ‘imaging’ polymer layer allows near-field mapping of metal nanostructures with subdiffraction resolution...

  19. Resistance switching induced by electric fields in manganite thin films

    International Nuclear Information System (INIS)

    Villafuerte, M; Juarez, G; Duhalde, S; Golmar, F; Degreef, C L; Heluani, S P

    2007-01-01

    In this work, we investigate the polarity-dependent Electric Pulses Induced Resistive (EPIR) switching phenomenon in thin films driven by electric pulses. Thin films of 0.5 Ca 0.5 MnO 3 (manganite) were deposited by PLD on Si substrate. The transport properties at the interface between the film and metallic electrode are characterized in order to study the resistance switching. Sample thermal treatment and electrical field history are important to be considered for get reproducible EPIR effect. Carriers trapping at the interfaces are considered as a possible explanation of our results

  20. Reply to comment on 'Model calculation of the scanned field enhancement factor of CNTs'

    International Nuclear Information System (INIS)

    Ahmad, Amir; Tripathi, V K

    2010-01-01

    In the paper (Ahmad and Tripathi 2006 Nanotechnology 17 3798), we derived an expression to compute the field enhancement factor of CNTs under any positional distribution of CNTs by using the model of a floating sphere between parallel anode and cathode plates. Using this expression we can compute the field enhancement factor of a CNT in a cluster (non-uniformly distributed CNTs). This expression was used to compute the field enhancement factor of a CNT in an array (uniformly distributed CNTs). We used an approximation to calculate the field enhancement factor. Hence, our expressions are correct in that assumption only. Zhbanov et al (2010 Nanotechnology 21 358001) suggest a correction that can calculate the field enhancement factor without using the approximation. Hence, this correction can improve the applicability of this model. (reply)

  1. Enhanced valley splitting in monolayer WSe2 due to magnetic exchange field.

    Science.gov (United States)

    Zhao, Chuan; Norden, Tenzin; Zhang, Peiyao; Zhao, Puqin; Cheng, Yingchun; Sun, Fan; Parry, James P; Taheri, Payam; Wang, Jieqiong; Yang, Yihang; Scrace, Thomas; Kang, Kaifei; Yang, Sen; Miao, Guo-Xing; Sabirianov, Renat; Kioseoglou, George; Huang, Wei; Petrou, Athos; Zeng, Hao

    2017-08-01

    Exploiting the valley degree of freedom to store and manipulate information provides a novel paradigm for future electronics. A monolayer transition-metal dichalcogenide (TMDC) with a broken inversion symmetry possesses two degenerate yet inequivalent valleys, which offers unique opportunities for valley control through the helicity of light. Lifting the valley degeneracy by Zeeman splitting has been demonstrated recently, which may enable valley control by a magnetic field. However, the realized valley splitting is modest (∼0.2 meV T -1 ). Here we show greatly enhanced valley spitting in monolayer WSe 2 , utilizing the interfacial magnetic exchange field (MEF) from a ferromagnetic EuS substrate. A valley splitting of 2.5 meV is demonstrated at 1 T by magnetoreflectance measurements and corresponds to an effective exchange field of ∼12 T. Moreover, the splitting follows the magnetization of EuS, a hallmark of the MEF. Utilizing the MEF of a magnetic insulator can induce magnetic order and valley and spin polarization in TMDCs, which may enable valleytronic and quantum-computing applications.

  2. Magnetic field enhanced photothermal effect of Fe3O4 nanoparticles

    Science.gov (United States)

    Pan, Pengfei; Lin, Yawen; Gan, Zhixing; Luo, Xiaobin; Zhou, Weiping; Zhang, Ning

    2018-03-01

    Photothermal and magnetothermal effects are promising in hyperthermia for cancer therapy. However, the development of safe treatments with limited side-effects requires a relatively-high thermal efficiency triggered by mild near-infrared (NIR) light and alternating magnetic field (HAC), which remains a formidable challenge. In this work, a magnetic field enhanced photothermal effect (MFEP) of Fe3O4 nanoparticles is proposed and investigated systematically. The results suggest remarkable temperature increments of 9.59 to 36.90 °C under irradiation of NIR with different light power densities (808 nm, 0-6.98 W/cm2) combined with a certain magnetic field (HAC = 1.5 kA/m at 90 kHz). The rise of temperature induced by MFEP is substantially larger than the sum of isolated photothermal and magnetothermal effects, which is attributed to the hot-phonon bottleneck effect. The MFEP of Fe3O4 nanoparticles could serve as an effective treatment for cancer therapy in the future.

  3. Enhancing predicted efficacy of tumor treating fields therapy of glioblastoma using targeted surgical craniectomy: A computer modeling study

    DEFF Research Database (Denmark)

    Korshoej, Anders Rosendal; Saturnino, Guilherme Bicalho; Rasmussen, Line Kirkegaard

    2016-01-01

    Objective: The present work proposes a new clinical approach to TTFields therapy of glioblastoma. The approach combines targeted surgical skull removal (craniectomy) with TTFields therapy to enhance the induced electrical field in the underlying tumor tissue. Using computer simulations, we explore...... the potential of the intervention to improve the clinical efficacy of TTFields therapy of brain cancer. Methods: We used finite element analysis to calculate the electrical field distribution in realistic head models based on MRI data from two patients: One with left cortical/subcortical glioblastoma and one...

  4. Increase in radiation-induced HPRT gene mutation frequency after nonthermal exposure to nonionizing 60 Hz electromagnetic fields.

    Science.gov (United States)

    Walleczek, J; Shiu, E C; Hahn, G M

    1999-04-01

    It is widely accepted that moderate levels of nonionizing electric or magnetic fields, for example 50/60 Hz magnetic fields of about 1 mT, are not mutagenic. However, it is not known whether such fields can enhance the action of known mutagens. To explore this question, a stringent experimental protocol, which included blinding and systematic negative controls, was implemented, minimizing the possibility of observer bias or experimental artifacts. As a model system, we chose to measure mutation frequencies induced by 2 Gy gamma rays in the redox-sensitive hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene in Chinese hamster ovary cells. We tested whether a 12-h exposure to a 60 Hz sinusoidally oscillating magnetic-flux density (Brms = 0.7 mT) could affect the mutagenic effects of ionizing radiation on the HPRT gene locus. We determined that the magnetic-field exposure induced an approximate 1.8-fold increase in HPRT mutation frequency. Additional experiments at Brms = 0.23 and 0.47 mT revealed that the effect was reduced at lower flux densities. The field exposure did not enhance radiation-induced cytotoxicity or mutation frequencies in cells not exposed to ionizing radiation. These results suggest that moderate-strength, oscillating magnetic fields may act as an enhancer of mutagenesis in mammalian cells.

  5. Enhanced stimulus-induced gamma activity in humans during propofol-induced sedation.

    Directory of Open Access Journals (Sweden)

    Neeraj Saxena

    Full Text Available Stimulus-induced gamma oscillations in the 30-80 Hz range have been implicated in a wide number of functions including visual processing, memory and attention. While occipital gamma-band oscillations can be pharmacologically modified in animal preparations, pharmacological modulation of stimulus-induced visual gamma oscillations has yet to be demonstrated in non-invasive human recordings. Here, in fifteen healthy humans volunteers, we probed the effects of the GABAA agonist and sedative propofol on stimulus-related gamma activity recorded with magnetoencephalography, using a simple visual grating stimulus designed to elicit gamma oscillations in the primary visual cortex. During propofol sedation as compared to the normal awake state, a significant 60% increase in stimulus-induced gamma amplitude was seen together with a 94% enhancement of stimulus-induced alpha suppression and a simultaneous reduction in the amplitude of the pattern-onset evoked response. These data demonstrate, that propofol-induced sedation is accompanied by increased stimulus-induced gamma activity providing a potential window into mechanisms of gamma-oscillation generation in humans.

  6. Thermal enhancement of x-ray induced DNA crosslinking

    International Nuclear Information System (INIS)

    Bowden, G.T.; Kasunic, M.; Cress, A.E.

    1982-01-01

    Ionizing radiation appears to crosslink nuclear DNA with chromosomal proteins. Important cellular processes such as transcription and DNA replication are likely to be compromised as a result of the DNA crosslinking. Heat treatment (43/sup o/C) of mouse leukemia cells (L1210) before X irradiation (50 Gy) was found to cause a doubling of the radiation-induced DNA crosslinking as measured by alkaline elution technique. By using proteinase K, a very active protease, to eliminate DNA-protein crosslinking in the alkaline elution assay, it was shown that the thermally enhanced DNA crosslinking was attributed to an increase in DNA-protein crosslinking. However, utilizing a protein radiolabel technique under conditions of increased DNA-protein crosslinking, the amount of protein left on the filter in the elution assay was not increased. These data suggest that qualitative rather than large quantitative differences in the crosslinked chromosomal proteins exist between irradiated cells and cells treated with heat prior to irradiation

  7. AC electric field induced vortex in laminar coflow diffusion flames

    KAUST Repository

    Xiong, Yuan

    2014-09-22

    Experiments were performed by applying sub-critical high-voltage alternating current (AC) to the nozzle of laminar propane coflow diffusion flames. Light scattering, laser-induced incandescence and laser-induced fluorescence techniques were used to identify the soot zone, and the structures of OH and polycyclic aromatic hydrocarbons (PAHs). Particle image velocimetry was adopted to quantify the velocity field. Under certain AC conditions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered, leading to the formation of toroidal vortices. Increased residence time and heat recirculation inside the vortex resulted in appreciable formation of PAHs and soot near the nozzle exit. Decreased residence time along the jet axis through flow acceleration by the vortex led to a reduction in the soot volume fraction in the downstream sooting zone. Electromagnetic force generated by AC was proposed as a viable mechanism for the formation of the toroidal vortex. The onset conditions for the vortex formation supported the role of an electromagnetic force acting on charged particles in the flame zone. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

  8. Consistency between Modalities Enhances Visually Induced Self-Motion (Vection

    Directory of Open Access Journals (Sweden)

    Takeharu Seno

    2011-10-01

    Full Text Available Visually induced illusory self-motion (vection is generally facilitated by consistent information of self-motion from other modalities. We provide three examples that consistent information between vision and other proprioception enhances vection, ie, locomotion, air flow, and sounds. We used an optic flow of expansion or contraction created by positioning 16,000 dots at random inside a simulated cube (length 20 m, and moving the observer's viewpoint to simulate forward or backward self-motion of 16 m/s. First, We measured the strength of forward or backward vection with or without forward locomotion on a treadmill (2 km/h. The results revealed that forward vection was facilitated by the consistent locomotion whereas vections in the other directions were inhibited by the inconsistent locomotion. Second, we found that forward vection intensity increased when the air flow to subjects' faces produced by an electric fan (the wind speed was 6.37 m/s was provided. On the contrary, the air flow did not enhance backward vection. Finally, we demonstrated that sounds which increased in loudness facilitated forward vection and the sounds which ascended (descended in pitch facilitated upward (downward vection.

  9. Simplified, enhanced protein purification using an inducible, autoprocessing enzyme tag.

    Directory of Open Access Journals (Sweden)

    Aimee Shen

    2009-12-01

    Full Text Available We introduce a new method for purifying recombinant proteins expressed in bacteria using a highly specific, inducible, self-cleaving protease tag. This tag is comprised of the Vibrio cholerae MARTX toxin cysteine protease domain (CPD, an autoprocessing enzyme that cleaves exclusively after a leucine residue within the target protein-CPD junction. Importantly, V. cholerae CPD is specifically activated by inositol hexakisphosphate (InsP(6, a eukaryotic-specific small molecule that is absent from the bacterial cytosol. As a result, when His(6-tagged CPD is fused to the C-terminus of target proteins and expressed in Escherichia coli, the full-length fusion protein can be purified from bacterial lysates using metal ion affinity chromatography. Subsequent addition of InsP(6 to the immobilized fusion protein induces CPD-mediated cleavage at the target protein-CPD junction, releasing untagged target protein into the supernatant. This method condenses affinity chromatography and fusion tag cleavage into a single step, obviating the need for exogenous protease addition to remove the fusion tag(s and increasing the efficiency of tag separation. Furthermore, in addition to being timesaving, versatile, and inexpensive, our results indicate that the CPD purification system can enhance the expression, integrity, and solubility of intractable proteins from diverse organisms.

  10. Improvement of boiling heat transfer by radiation induced boiling enhancement

    International Nuclear Information System (INIS)

    Imai, Yasuyuki; Okamoto, Koji; Madarame, Haruki; Takamasa, Tomoji

    2003-01-01

    For nuclear reactor systems, the critical heat flux (CHF) data is very important because it limits reactor efficiency. Improvement of CHF requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. In our previous study, we confirmed that the surface wettability changed significantly or that highly hydrophilic conditions were achieved, after irradiation of 60 Co gamma ray, by the Radiation Induced Surface Activation (RISA) phenomenon. To delineate the effect of RISA on boiling phenomena, surface wettability in a high-temperature environment and critical heat flux (CHF) of metal oxides irradiated by gamma rays were investigated. A CHF experiment in the pool boiling condition was carried out under atmospheric pressure. The heating test section made of titanium was 0.2 mm in thickness, 3 mm in height, and 60 mm in length. Oxidation of the surface was carried out by plasma jetting for 40 seconds. The test section was irradiated by 60 Co gamma ray with predetermined radiation intensity and period. The CHF of oxidized titanium was improved up to 100 percent after 800 kGy 60 Co gamma ray irradiation. We call this effect Radiation Induced Boiling Enhancement (RIBE). Before we conducted the CHF experiment, contact angles of the test pieces were measured to show the relationship between wettability and CHF. The CHF in the present experiment increases will surface wettability in the same manner as shown by Liaw and Dhir's results. (author)

  11. Noise-induced enhancement of network reciprocity in social dilemmas

    International Nuclear Information System (INIS)

    Zhang, Gui-Qing; Sun, Qi-Bo; Wang, Lin

    2013-01-01

    Highlights: • We introduce the noise-induced mechanism into the prisoner’s dilemma game. • Cooperation will be largely enhanced by introducing the noise into the calculation of fitness. • Despite the defectors prevail initially, the stressed factor still promotes the cooperation. • The mechanism studied here is helpful on different kinds of interaction networks. -- Abstract: The network reciprocity is an important dynamic rule fostering the emergence of cooperation among selfish individuals. This was reported firstly in the seminal work of Nowak and May, where individuals were arranged on the regular lattice network, and played the prisoner’s dilemma game (PDG). In the standard PDG, one often assumes that the players have perfect rationality. However, in reality, we human are far from rational agents, as we often make mistakes, and behave irrationally. Accordingly, in this work, we introduce the element of noise into the measurement of fitness, which is determined by the parameter α controlling the degree of noise. The considered noise-induced mechanism remarkably promotes the behavior of cooperation, which may be conducive to interpret the emergence of cooperation within the population

  12. Electric field-induced astrocyte alignment directs neurite outgrowth.

    Science.gov (United States)

    Alexander, John K; Fuss, Babette; Colello, Raymond J

    2006-05-01

    The extension and directionality of neurite outgrowth are key to achieving successful target connections during both CNS development and during the re-establishment of connections lost after neural trauma. The degree of axonal elongation depends, in large part, on the spatial arrangement of astrocytic processes rich in growth-promoting proteins. Because astrocytes in culture align their processes on exposure to an electrical field of physiological strength, we sought to determine the extent to which aligned astrocytes affect neurite outgrowth. To this end, dorsal root ganglia cells were seeded onto cultured rat astrocytes that were pre-aligned by exposure to an electric field of physiological strength (500 mV mm(-1)). Using confocal microscopy and digital image analysis, we found that neurite outgrowth at 24 hours and at 48 hours is enhanced significantly and directed consistently along the aligned astrocyte processes. Moreover, this directed neurite outgrowth is maintained when grown on fixed, aligned astrocytes. Collectively, these results indicate that endogenous electric fields present within the developing CNS might act to align astrocyte processes, which can promote and direct neurite growth. Furthermore, these results demonstrate a simple method to produce an aligned cellular substrate, which might be used to direct regenerating neurites.

  13. Enhanced photoresponsivity in organic field effect transistors by silver nanoparticles

    DEFF Research Database (Denmark)

    Linnet, Jes; Runge Walther, Anders; Albrektsen, Ole

    2017-01-01

    Organic semiconductors (OSC) such as thiophene-based oligomers exhibit useful electronic and optical properties making them applicable in photo-sensing devices. Generally, thiophene-based photodetectors exhibit a decent responsivity with a spectral sensitivity determined by the OSC's absorption...... properties. We present a simple, yet efficient method to enhance and spectrally tune the photoresponsivity of organic phototransistors (OPTs) utilizing the plasmonic properties of embedded metallic nanoparticles. The ability to fabricate and characterize nanostructures with high accuracy allows for tailoring...... of the optical properties of metal nanoparticles (NPs) and thereby tuning of the spectral range of enhanced photoresponsivity. In this work we have investigated OPTs based on the molecule 5,5″-bis(naphth-2-yl)-2,2':5′,2″-terthiophene (NaT3). We have fabricated OPTs with electron beam lithography-defined arrays...

  14. Enhancing the intense field control of molecular fragmentation.

    Science.gov (United States)

    Anis, Fatima; Esry, B D

    2012-09-28

    We describe a pump-probe scheme with which the spatial asymmetry of dissociating molecular fragments-as controlled by the carrier-envelope phase of an intense few-cycle laser pulse-can be enhanced by an order of magnitude or more. We illustrate the scheme using extensive, full-dimensional calculations for dissociation of H(2)(+) and include the averaging necessary for comparison with experiment.

  15. Near-field enhanced thermionic energy conversion for renewable energy recycling

    Science.gov (United States)

    Ghashami, Mohammad; Cho, Sung Kwon; Park, Keunhan

    2017-09-01

    This article proposes a new energy harvesting concept that greatly enhances thermionic power generation with high efficiency by exploiting the near-field enhancement of thermal radiation. The proposed near-field enhanced thermionic energy conversion (NETEC) system is uniquely configured with a low-bandgap semiconductor cathode separated from a thermal emitter with a subwavelength gap distance, such that a significant amount of electrons can be photoexcited by near-field thermal radiation to contribute to the enhancement of thermionic current density. We theoretically demonstrate that the NETEC system can generate electric power at a significantly lower temperature than the standard thermionic generator, and the energy conversion efficiency can exceed 40%. The obtained results reveal that near-field photoexcitation can enhance the thermionic power output by more than 10 times, making this hybrid system attractive for renewable energy recycling.

  16. Enhanced charge density wave order in La2-xSrxCuO4 at high magnetic field.

    Science.gov (United States)

    He, Wei; Wen, Jiajia; Jang, Hoyoung; Nojiri, Hiroyuki; Matsuzawa, Satoshi; Song, Sanghoon; Chollet, Matthieu; Zhu, Diling; Fujita, Masaki; Rotundu, Costel R.; Sheckelton, John P.; Jiang, Mingde; Kao, Chi-Chang; Lee, Jun-Sik; Lee, Young S.

    There has been much recent interest in the charge density wave (CDW) order in the cuprate superconductors. An intriguing form of the density wave occurs in the La2CuO4-based family where both the charge and spin form ``stripes'' near 1/8 doping. Charge order has been reported in La2-xSrxCuO4 (LSCO) in zero magnetic field near 1/8 doping that was enhanced in moderate DC fields (up to 10 T). In this talk, I will discuss our recent experiment which combines a pulsed magnet with the x-rays from a free electron laser to characterize the CDW in LSCO with x =0.115 in fields up to 24 Tesla. In contrast to the YBCO family, which shows field-induced 3D CDW order, the field-enhanced CDW order in LSCO remains two-dimensional up to 24 T. Further results regarding the field-dependence and zero-field behavior of the CDW will be discussed. Our study provides important information on the interplay between CDW order and high-Tc superconductivity. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under contract DE-AC02-76SF00515.

  17. Effects of virtual reality-enhanced exercise equipment on adherence and exercise-induced feeling states.

    Science.gov (United States)

    Annesi, J J; Mazas, J

    1997-12-01

    A field study was conducted to test the effectiveness of virtual reality-enhanced cardiovascular exercise equipment for increasing adherence and attendance in a mixed-sex adult sample. Attendance was significantly higher in the virtual reality-enhanced condition than in the conditions without virtual reality over the 14-wk. period. Adherence was also highest (83.33%) in the virtual-reality bicycle group. Postexercise feelings of positive engagement, revitalization, tranquility, and physical exhaustion, as measured by the Exercise-induced Feeling Inventory, did not differ among groups. Contrary to previous findings, Self-motivation Inventory scores were not associated with either attendance or adherence. While findings suggest that virtual-reality features may promote exercise adherence or attendance, it is not yet known what psychological variables they affect. Implications were drawn regarding the practical possibilities for exercise promotion.

  18. Field trips as an intervention to enhance pharmacy students' positive ...

    African Journals Online (AJOL)

    To determine whether students' experience of field trips influenced their perceptions regarding a management module as part of their training as future pharmacists. Methods. A mixed-method sequential exploratory research design was used. Data were gathered through written narratives and focus group interviews, ...

  19. Field Trial of the Enhanced Data Authentication System (EDAS)

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Maikael A.; Baldwin, George T.; Hymel, Ross W

    2016-05-01

    The goal of the field trial of EDAS was to demonstrate the utility of secure branching of operator instrumentation for nuclear safeguards, identify any unforeseen implementation and application issues with EDAS, and confirm whether the approach is compatible with operator concerns and constraints.

  20. Enhanced field emission behavior of layered MoSe2

    International Nuclear Information System (INIS)

    Suryawanshi, Sachin R; Pawbake, Amit S; Jadkar, Sandesh R; More, Mahendra A; Pawar, Mahendra S; Late, Dattatray J

    2016-01-01

    Herein, we report one step facile chemical vapor deposition method for synthesis of single-layer MoSe 2 nanosheets with average lateral dimension ∼60 μm on 300 nm SiO 2 /Si and n-type silicon substrates and field emission investigation of MoSe 2 /Si at the base pressure of ∼1 × 10 −8 mbar. The morphological and structural analyses of the as-deposited single-layer MoSe 2 nanosheets were carried out using an optical microscopy, Raman spectroscopy and atomic force microscopy. Furthermore, the values of turn-on and threshold fields required to extract an emission current densities of 1 and 10 μA cm −2 , are found to be ∼1.9 and ∼2.3 V μm −1 , respectively. Interestingly, the MoSe 2 nanosheet emitter delivers maximum field emission current density of ∼1.5 mA cm −2 at a relatively lower applied electric field of ∼3.9 V μm −1 . The long term operational current stability recorded at the preset values of 35 μA over 3 hr duration and is found to be very good. The observed results demonstrates that the layered MoSe 2 nanosheet based field emitter can open up many opportunities for their potential application as an electron source in flat panel display, transmission electron microscope, and x-ray generation. Thus, the facile one step synthesis approach and robust nature of single-layer MoSe 2 nanosheets emitter can provide prospects for the future development of practical electron sources. (paper)

  1. Fatigue hydraulic fracturing by cyclic reservoir treatment enhances permeability and reduces induced seismicity

    Science.gov (United States)

    Zang, Arno; Yoon, Jeoung Seok; Stephansson, Ove; Heidbach, Oliver

    2013-11-01

    The occurrence of induced seismic events during hydraulic fracturing of reservoirs to enhance permeability is an unavoidable process. Due to the increased public concern with respect to the risks imposed by induced seismicity, however, the development of a soft stimulation method is needed creating higher permeability with less induced seismicity. We use a discrete element model of naturally fractured rock with pore fluid flow algorithm in order to analyse two scenarios of high-pressure fluid injection (hydraulic fracturing) at depth and associated induced seismicity. The ratio of pumped-in energy to released seismic energy is in agreement with field data. Our results suggest that cyclic reservoir treatment is a safer alternative to conventional hydraulic fracture stimulation as both, the total number of induced events as well as the occurrence of larger magnitude events are lowered. This work is motivated by results of laboratory triaxial indenter tests on granite rock samples where continuous loading leads to a wide fracture process zone while cyclic treatment with frequent starting and stopping of loading fatigues the rock, resulting in smaller damage volume and more persistent fracture growth.

  2. A novel virus-inducible enhancer of the interferon-β gene with tightly linked promoter and enhancer activities.

    Science.gov (United States)

    Banerjee, A Raja; Kim, Yoon Jung; Kim, Tae Hoon

    2014-11-10

    Long-range enhancers of transcription are a key component of the genomic regulatory architecture. Recent studies have identified bi-directionally transcribed RNAs emanating from these enhancers known as eRNAs. However, it remains unclear how tightly coupled eRNA production is with enhancer activity. Through our systematic search for long-range elements that interact with the interferon-β gene, a model system for studying inducible transcription, we have identified a novel enhancer, which we have named L2 that regulates the expression of interferon-β. We have demonstrated its virus-inducible enhancer activity by analyzing epigenomic profiles, transcription factor association, nascent RNA production and activity in reporter assays. This enhancer exhibits intimately linked virus-inducible enhancer and bidirectional promoter activity that is largely dependent on a conserved Interferon Stimulated Response Element and robustly generates virus inducible eRNAs. Notably, its enhancer and promoter activities are fully retained in reporter assays even upon a complete elimination of its associated eRNA sequences. Finally, we show that L2 regulates IFNB1 expression by siRNA knockdown of eRNAs, and the deletion of L2 in a BAC transfection assay. Thus, L2 is a novel enhancer that regulates IFNB1 and whose eRNAs exert significant activity in vivo that is distinct from those activities recapitulated in the luciferase reporter assays. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  3. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems.

    Science.gov (United States)

    Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

    2015-11-25

    For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p'-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis.

  4. Modified field enhancement and extinction by plasmonic nanowire dimers due to nonlocal response

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, Søren; Jauho, Antti-Pekka

    2012-01-01

    it in a wide frequency range against analytical results for the extinction cross section of a cylindrical plasmonic nanowire. Our main results concern more complex geometries, namely cylindrical and bow-tie nanowire dimers that can strongly enhance optical fields. For both types of dimers we find that nonlocal...... response can strongly affect both the field enhancement in between the dimers and their respective extinction cross sections. In particular, we give examples of blueshifted maximal field enhancements near hybridized plasmonic dimer resonances that are still large but nearly two times smaller than...

  5. Improving field enhancement of 2D hollow tapered waveguides via dielectric microcylinder coupling

    International Nuclear Information System (INIS)

    Chen, Yongzhu; Chen, Gengyan; Guo, Lina; Lin, Xusheng; Xie, Xiangsheng; Li, Li

    2015-01-01

    We numerically study a novel scheme to improve the field enhancement of 2D hollow tapered waveguides (HTWs). A dielectric microcylinder is embedded into a metal–insulator–metal (MIM) HTW for resonant exciting gap surface plasmons (GSPs), which is different from the lowest propagating mode (TM 0 ) excitation via the conventional fire-end coupling method. The physical mechanism of the field enhancement and the influence of critical parameters such as numerical aperture (NA) of the lens, permittivity of the microcylinder and the incident wavelength are discussed. The substantial improvement of the GSP excitation efficiency via dielectric microcylinder coupling shows potential in designing tapered MIM waveguides for nanofocusing and field enhancement. (paper)

  6. Enhancement of plate heat exchanger performance using electric fields

    International Nuclear Information System (INIS)

    Down, E.M.

    2000-12-01

    The falling film plate evaporator is often used in the food processing industry to remove large amounts of water from liquids, pulps and slurries. Although a compact efficient device with high heat transfer rates, there is a requirement for even greater performance, particularly when fuelled by the low grade energy from many renewable sources. Electrohydrodynamics (EHD) has been shown to give large heat transfer enhancements under many conditions, but most of this previous research has been with working fluids having much lower electrical conductivities than the water-based fluids that are the main concern of this study. The liquid flow in falling film plate evaporators is in the form of a very thin (less than a millimetre) film falling down a heated plate under the effect of gravity. The film surface exhibits waviness over much of the operating range of industrial heat exchangers, and the degree of waviness has previously been shown to have a large effect on the rate of heat transfer. A theoretical model was developed which suggested that significant increases in waviness, and therefore heat transfer, could be stimulated using high voltage electrodes, and these were subsequently observed on the surface of a pool of water during bench-top experiments. An experimental falling film rig was designed to study this EHD effect but the 2.5 kV maximum voltage attainable was thought to be too low to stimulate wave enlargement and no heat transfer enhancement was seen. Significant heat transfer enhancement was observed in the falling film rig when utilising corona discharge electrodes. This was thought to be due to a thinning of the film in the vicinity of the electrode via the corona wind and increased fluid mixing downstream of the electrode. Both point and wire electrodes improved heat transfer rates but wire electrodes were thought to have more potential for integration into existing industrial heat exchanger designs, so were studied more closely. Heat transfer rates

  7. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    CERN Document Server

    Vaidya, S J; Shaikh, A M; Chandorkar, A N

    2002-01-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co sup 6 sup 0 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radi...

  8. Studying the field induced breakup of acoustically levitated drops

    Science.gov (United States)

    Warschat, C.; Riedel, J.

    2017-10-01

    Coulomb fission of charged droplets (The terms drop and droplet are often used synonymous. Throughout this manuscript, to avoid confusion, the terms drop and droplet will be used for liquid spheres with radii in the millimeter range and the micrometer range, respectively. In our experiments, the first correspond to the parent drop while the latter describes the ejected progeny droplets.) is a well-studied natural phenomenon. Controlled droplet fission is already successfully employed in several technological applications. Still, since the occurring surface rupture relies on the exact understanding and description of the liquid gas boundary, some details are still under debate. Most empirical systematic studies observe falling micrometer droplets passing through the electric field inside a plate capacitor. This approach, although easily applicable and reliable, limits the experimental degrees of freedom regarding the observable time and the maximum size of the drops and can only be performed in consecutive individual observations of different subsequent drops. Here we present a novel setup to study the field induced breakup of acoustically levitated drops. The design does not bear any restrictions towards the temporal window of observation, and allows handling of drops of a tunable radius ranging from 10 μm to several millimeters and a real-time monitoring of one single drop. Our comprehensive study includes a time resolved visual inspection, laser shadowgraphy, laser induced fluorescence imaging, and ambient mass spectrometric interrogation of the nascent Taylor cone. The results shown for a millimeter sized drop, previously inaccessible for Coulomb fission experiments, are mostly comparable with previous results for smaller drops. The major difference is the time scale and the threshold potential of the drop rupture. Both values, however, resemble theoretically extrapolations to the larger radius. The technique allows for a systematic study of breakup behavior of

  9. The enhanced piezoelectricity in compositionally graded ferroelectric thin films under electric field: A role of flexoelectric effect

    Science.gov (United States)

    Qiu, Ye; Wu, Huaping; Wang, Jie; Lou, Jia; Zhang, Zheng; Liu, Aiping; Chai, Guozhong

    2018-02-01

    Compositionally graded ferroelectric thin films are found to produce large strain gradients, which can be used to tune the physical properties of materials through the flexoelectric effect, i.e., the coupling of polarization and the strain gradient. The influences of the flexoelectric effect on the polarization distribution and the piezoelectric properties in compositionally graded Ba1-xSrxTiO3 ferroelectric thin films are investigated by using an extended thermodynamic theory. The calculation results show that the presence of the flexoelectric effect tends to enhance and stabilize polarization components. The polarization rotation induced by the flexoelectric field has been predicted, which is accompanied by more uniform and orderly polarization components. A remarkable enhancement of piezoelectricity is obtained when the flexoelectric field is considered, suggesting that compositionally graded Ba1-xSrxTiO3 ferroelectric thin films with a large strain gradient are promising candidates for piezoelectric devices.

  10. Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo

    International Nuclear Information System (INIS)

    Noble, S.T.; Djuth, F.T.

    1990-01-01

    Two radar systems with beams intersecting in the HF-modified F region were used to simultaneously measure HF-enhanced plasma lines (HFPLs) and artificial geomagnetic field-aligned irregularities (AFAIs). The Arecibo 430-MHz radar was used for the HFPL observations, and a portable 49.92-MHz backscatter radar was deployed on the island of Guadeloupe to monitor the AFAIs. The experiment was desgined to examine the degree to which HF-induced plasma turbulence influences the development of AFAIs. When the HF beam is stepped up in power, sustained HFPLs and AFAIs are first observed at the same HF power level, indicating that ponderomotively driven instabilities may be involved in the early time development of AFAIs. As the HF power is increased, the HFPL backscatter power begins to saturate at ∼70 MW effective radiated power (ERP). However, the backscatter from AFAIs is linearly dependent on HF power, even at the highest (120 MW ERP) HF power levels available at Arecibo. This suggests that additional processes may contribute to the development of AFAIs. For example, ponderomotively driven instabilities may give rise to weak geomagnetic field-aligned irregularities that are subsequently driven unstable by processes excited near the upper hybrid resonance. It is also likely that AFAIs greatly impact the development of HF-induced plasma turbulence at late times (>1 s) following HF turn-on. Once the ionosphere is preconditioned by high-power HF modifications, AFAIs and HFPLs can be simultaneously sustained at a much lower HF power level than that needed to originally excite them. The nature of the preconditioning process is currently not well understood. New theoretical initiatives are clearly needed to guide future experimental activity in this area

  11. Circulating persistent current and induced magnetic field in a fractal network

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Srilekha [Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata 700 064 (India); Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata 700 108 (India); Karmakar, S.N. [Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata 700 064 (India)

    2016-04-29

    We present the overall conductance as well as the circulating currents in individual loops of a Sierpinski gasket (SPG) as we apply bias voltage via the side attached electrodes. SPG being a self-similar structure, its manifestation on loop currents and magnetic fields is examined in various generations of this fractal and it has been observed that for a given configuration of the electrodes, the physical quantities exhibit certain regularity as we go from one generation to another. Also a notable feature is the introduction of anisotropy in hopping causes an increase in magnitude of overall transport current. These features are a subject of interest in this article. - Highlights: • Voltage driven circular current is analyzed in a fractal network. • Current induced magnetic field is strong enough to flip a spin. • Anisotropy in hopping enhances overall transport current.

  12. Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation

    Science.gov (United States)

    Yin, Yudan; Niu, Lin; Zhu, Xiaocui; Zhao, Meiping; Zhang, Zexin; Mann, Stephen; Liang, Dehai

    2016-02-01

    Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media.

  13. Cationic peptide exposure enhances pulsed-electric-field-mediated membrane disruption.

    Science.gov (United States)

    Kennedy, Stephen M; Aiken, Erik J; Beres, Kaytlyn A; Hahn, Adam R; Kamin, Samantha J; Hagness, Susan C; Booske, John H; Murphy, William L

    2014-01-01

    The use of pulsed electric fields (PEFs) to irreversibly electroporate cells is a promising approach for destroying undesirable cells. This approach may gain enhanced applicability if the intensity of the PEF required to electrically disrupt cell membranes can be reduced via exposure to a molecular deliverable. This will be particularly impactful if that reduced PEF minimally influences cells that are not exposed to the deliverable. We hypothesized that the introduction of charged molecules to the cell surfaces would create regions of enhanced transmembrane electric potential in the vicinity of each charged molecule, thereby lowering the PEF intensity required to disrupt the plasma membranes. This study will therefore examine if exposure to cationic peptides can enhance a PEF's ability to disrupt plasma membranes. We exposed leukemia cells to 40 μs PEFs in media containing varying concentrations of a cationic peptide, polyarginine. We observed the internalization of a membrane integrity indicator, propidium iodide (PI), in real time. Based on an individual cell's PI fluorescence versus time signature, we were able to determine the relative degree of membrane disruption. When using 1-2 kV/cm, exposure to >50 μg/ml of polyarginine resulted in immediate and high levels of PI uptake, indicating severe membrane disruption, whereas in the absence of peptide, cells predominantly exhibited signatures indicative of no membrane disruption. Additionally, PI entered cells through the anode-facing membrane when exposed to cationic peptide, which was theoretically expected. Exposure to cationic peptides reduced the PEF intensity required to induce rapid and irreversible membrane disruption. Critically, peptide exposure reduced the PEF intensities required to elicit irreversible membrane disruption at normally sub-electroporation intensities. We believe that these cationic peptides, when coupled with current advancements in cell targeting techniques will be useful tools in

  14. In situ electric-field-induced contrast imaging of electronic transport pathways in nanotube-polymer composites

    Science.gov (United States)

    Jesse, Stephen; Guillorn, Michael A.; Ivanov, Ilia N.; Puretzky, Alexander A.; Howe, Jane Y.; Britt, Phillip F.; Geohegan, David B.

    2006-07-01

    An electric-field-induced contrast mechanism for scanning electron microscopy is reported which permits the visualization of embedded nanomaterials inside various matrices with high contrast and high definition. The high contrast is proposed to result from localized enhancement of secondary electron emission from the nanomaterials due to electric-field-induced changes in their work functions. By utilizing a stage that allows in situ current-voltage measurements inside a scanning electron microscope, single-walled carbon nanotubes embedded within polymethyl methacrylate films were visualized directly. In addition to the rapid assessment of nanotube dispersion within polymers, electric-field-induced contrast imaging enables the determination of percolation pathways. From the contrast in the images, the relative voltage at all points in the electron micrograph can be determined, providing a new mechanism to understand electronic percolation through nanoscale networks.

  15. Extreme Value Analysis of Induced Geoelectric Field in South Africa

    Science.gov (United States)

    Lotz, S. I.; Danskin, D. W.

    2017-10-01

    Extreme geomagnetic disturbances occur rarely but can have great impact on technological systems such as power supply networks. Long-term planning for extreme events requires the estimation of event impact for occurrence periods greater than the length of observed data. With this in mind an analysis of extreme geomagnetic events observed in South Africa (middle geomagnetic latitude) is performed over four solar cycles (1974-2015). An algorithm to identify active periods with minimum SYM-H ≤-100 nT is demonstrated. The sum of induced electric field over the course of each event is used to characterize the severity of each active period. It is found that the severity index (accumulated electric field magnitude ΣE) shares a highly linear relationship with accumulated SYM-H over each event. The index ΣE is lognormal distributed, with tail deviating greater than lognormal, confirming heavy-tailed occurrence. A general Pareto distribution is fitted to the tail of the distribution and extrapolated to calculate the return levels of extreme events. Return levels of once in 100 and once in 200 year events are estimated to be 9.4 × 104 mV/km min and 1.09 × 105 mV/km min, respectively. The top three events, in ascending order of severity, are the March 1989 storm, the events of late October 2003, and the April 1994 event—a long interval of coronal-hole driven disturbances, bookended by two intense geomagnetic storms.

  16. Electromagnetically induced transparency resonances inverted in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sargsyan, A.; Sarkisyan, D., E-mail: davsark@yahoo.com, E-mail: david@ipr.sci.am [National Academy of Sciences of Armenia, Institute for Physical Research (Armenia); Pashayan-Leroy, Y.; Leroy, C. [Université de Bourgogne-Dijon, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS (France); Cartaleva, S. [Bulgarian Academy of Sciences, Institute of Electronics (Bulgaria); Wilson-Gordon, A. D. [Bar-Ilan University Ramat Gan, Department of Chemistry (Israel); Auzinsh, M. [University of Latvia, Department of Physics (Latvia)

    2015-12-15

    The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the {sup 87}Rb D{sub 1} line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ{sub rel} are used: an Rb cell with antirelaxation coating (L ∼ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.

  17. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    Science.gov (United States)

    Vaidya, S. J.; Sharma, D. K.; Shaikh, A. M.; Chandorkar, A. N.

    2002-09-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co 60 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radiation performance of pyrogenic field oxides with respect to positive charge build up as well as interface state generation. Pyrogenic oxide nitrided in N 2O is found to be the best oxynitride as damage due to neutrons is the least.

  18. Proposal for a magnetic field induced graphene dot

    International Nuclear Information System (INIS)

    Maksym, P A; Roy, M; Craciun, M F; Russo, S; Yamamoto, M; Tarucha, S; Aoki, H

    2010-01-01

    Quantum dots induced by a strong magnetic field applied to a single layer of graphene in the perpendicular direction are investigated. The dot is defined by a model potential which consists of a well of depth ΔV relative to a flat asymptotic part and quantum states formed from the zeroth Landau level are considered. The energy of the dot states cannot be lower than -ΔV relative to the asymptotic potential. Consequently, when ΔV is chosen to be about half of the gap between the zeroth and first Landau levels, the dot states are isolated energetically in the gap between Landau level 0 and Landau level -1. This is confirmed with numerical calculations of the magnetic field dependent energy spectrum and the quantum states. Remarkably, an antidot formed by reversing the sign of ΔV also confines electrons but in the energy region between Landau level 0 and Landau level +1. This unusual behaviour gives an unambiguous signal of the novel physics of graphene quantum dots.

  19. Electric-field induced magnetization reversal using multiferroics

    Science.gov (United States)

    Trassin, Morgan

    2012-02-01

    Controlling magnetism using solely electric fields is interesting not only from a fundamental standpoint, but presents great potential for ultimately low energy consumption logic and memory. The evidence of the electrically controllable antiferromagnetic ordering in the multiferroic magnetoelectric bismuth ferrite (BiFeO3) drew an increasing interest in the pursuit for new emerging devices. To use such functionality for device applications, deterministic control not only of antiferromagnetism, but also ferromagnetism is essential. To achieve this goal, a ferromagnet/multiferroic heterostructure has been proposed based on the combination of magnetoelectric coupling in BiFeO3 and exchange coupling between magnetic materials and offers a new pathway for the electrical control of magnetism. By combination of a piezoresponse force microscopy, photoemission electron microscopy and anisotropic magnetoresistance measurements, we demonstrated the non-volatile reversal of a CoFe layer magnetization induced solely by the application of an electric field at room temperature. This 180 degree rotation of the magnetization of the ferromagnetic layer is mediated by a strong interfacial coupling. The correlation between the ferroelectric state in the multiferroic layer and the CoFe ferromagnetic domain architecture is evidenced. The projection of this strong magnetoelectric coupling in an out-of-plane configuration, allowing the reduction by an order of magnitude of voltage required, will be discussed. Our results show the high potential of magnetoelectric-based heterostructures for future low energy consumption data storage devices.

  20. Development of an Enhanced Two-Phase Production System at the Geysers Geothermal Field; FINAL

    International Nuclear Information System (INIS)

    Steven Enedy

    2001-01-01

    A method was developed to enhance geothermal steam production from two-phase wells at THE Geysers Geothermal Field. The beneficial result was increased geothermal production that was easily and economically delivered to the power plant

  1. Ultrathin high efficiency photodetectors based on subwavelength grating and near-field enhanced absorption.

    Science.gov (United States)

    Zohar, Moshe; Auslender, Mark; Hava, Shlomo

    2015-03-12

    Optical absorbers, comprising a thin semiconductor layer placed between two transparent ones in close proximity to a subwavelength grating, are considered. With no back mirror, these structures only mimic the resonant cavity enhanced photodetector, being an order of magnitude thinner. It is argued that the grating can assist the light confinement by near field microcavity resonance rather than by far field mirroring. Tolerant designs to attain nearly 100% optical absorption at a predefined wavelength are demonstrated, and the near-field enhancement of the absorption is confirmed. The results obtained indicate that the proposed near field enhanced photodetectors meet the combined challenges of significantly increasing the efficiency and reducing the complexity and size of the entire device as compared to the resonant cavity enhanced photodetectors, which may be useful for integrated multi-detector arrays.

  2. Laser ablation of polymer coatings allows for electromagnetic field enhancement mapping around nanostructures

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    2011-01-01

    . The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron microscopy and atomic force microscopy...

  3. Role of work function in field emission enhancement of Au island decorated vertically aligned ZnO nanotapers

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Avanendra [School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha (India); Senapati, Kartik, E-mail: kartik@niser.ac.in [School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha (India); Kumar, Mohit; Som, Tapobrata [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751005, Odisha (India); Sinha, Anil K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, M.P. (India); Sahoo, Pratap K., E-mail: pratap.sahoo@niser.ac.in [School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha (India)

    2017-07-31

    Highlights: • Hydrothermally synthesized nanotapers were decorated by gold corrugation using simple evaporation techniques for large area applications. • A significantly enhanced field emission properties of nanotapers were achieved. • The metal induced midgap states formed at the ZnO-Au interface and the reduced effective work function are responsible for low turn-on field. • TUNA measurements revealed a very uniform spatial emission profile in the Au decorated nanotapers. - Abstract: In this report, we demonstrate significantly enhanced field emission properties of ZnO nanotapers achieved via a corrugated decoration of Au. Field emission experiments on these Au-decorated ZnO nanotapers showed emission current densities comparable to the best results in the literature. Au decoration of 5 nm also reduced the effective turn-on field to ∼0.54 V/μm, compared to the as grown ZnO nanotapers, which showed a turn-on field of ∼1.1 V/μm. Tunneling atomic force microscopy measurements revealed a very uniform spatial emission profile in the 5 nm Au decorated nanotapers, which is a basic requirement for any large scale application. We believe that metal induced mid-gap states formed at the ZnO–Au interface are responsible for the observed low turn-on field because such interface states are known to reduce the effective work function. A direct measurement of effective work function using Kelvin probe force microscopy indeed showed more than 1.1 eV drop in the case of 5 nm Au decorated ZnO nanotapers compared to the pristine nanotapers, supporting the above argument.

  4. Biostimulation and enhancement of pesticide degradation around water abstraction fields

    DEFF Research Database (Denmark)

    Levi, Suzi

    and precipitation of iron followed by the growth of iron bacteria leading to bioclogging reduces the efficiency of bioremediation of contaminated aquifers. The overall scope of this PhD study was to investigate biostimulated degradation potentials of pesticides at low concentrations in groundwater contaminated...... potential in the field than could be transferred to the laboratory. In conclusion, this PhD has developed our understanding on degradation processes of pesticides in aquifer systems. We have shown that biostimulation by oxygen addition even at relatively low concentrations is a promising remediation......Groundwater contamination by pesticides is a widespread environmental problem and a major threat to drinking water supplies. Diffuse source contamination of groundwater that enters from an extensive area is characterized by low pesticide concentrations (nanogram-microgram per liter) in large...

  5. Enhanced heat sink with geometry induced wall-jet

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, Md. Mahamudul, E-mail: sohel0991@gmail.com; Tikadar, Amitav; Bari, Fazlul; Morshed, A. K. M. M. [Department of Mechanical Engineering Bangladesh University of Engineering and Technology, Dhaka-1000. Bangladesh (Bangladesh)

    2016-07-12

    Mini-channels embedded in solid matrix have already proven to be a very efficient way of electronic cooling. Traditional mini-channel heat sinks consist of single layer of parallel channels. Although mini-channel heat sink can achieve very high heat flux, its pumping requirement for circulating liquid through the channel increase very sharply as the flow velocity increases. The pumping requirements of the heat sink can be reduced by increasing its performance. In this paper a novel approach to increase the thermal performance of the mini-channel heat sink is proposed through geometry induced wall jet which is a passive technique. Geometric irregularities along the channel length causes abrupt pressure change between the channels which causes cross flow through the interconnections thus one channel faces suction and other channel jet action. This suction and jet action disrupts boundary layer causing enhanced heat transfer performance. A CFD model has been developed using commercially available software package FLUENT to evaluate the technique. A parametric study of the velocities and the effect of the position of the wall-jets have been performed. Significant reduction in thermal resistance has been observed for wall-jets, it is also observed that this reduction in thermal resistance is dependent on the position and shape of the wall jet.

  6. Rydberg interaction induced enhanced excitation in thermal atomic vapor.

    Science.gov (United States)

    Kara, Dushmanta; Bhowmick, Arup; Mohapatra, Ashok K

    2018-03-27

    We present the experimental demonstration of interaction induced enhancement in Rydberg excitation or Rydberg anti-blockade in thermal atomic vapor. We have used optical heterodyne detection technique to measure Rydberg population due to two-photon excitation to the Rydberg state. The anti-blockade peak which doesn't satisfy the two-photon resonant condition is observed along with the usual two-photon resonant peak which can't be explained using the model with non-interacting three-level atomic system. A model involving two interacting atoms is formulated for thermal atomic vapor using the dressed states of three-level atomic system to explain the experimental observations. A non-linear dependence of vapor density is observed for the anti-blockade peak which also increases with increase in principal quantum number of the Rydberg state. A good agreement is found between the experimental observations and the proposed interacting model. Our result implies possible applications towards quantum logic gates using Rydberg anti-blockade in thermal atomic vapor.

  7. Dependence of enhanced asymmetry-induced transport on collision frequency

    International Nuclear Information System (INIS)

    Eggleston, D. L.

    2014-01-01

    A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ϕ 1 (r) cos(kz) cos(ωt−lθ), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ω matches the azimuthal rotation frequency ω R , is usually dominant at low collision frequency ν but becomes negligible at higher ν. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ν (banana) regime, the radial oscillations have amplitude Δr ≈ v r /ω T , so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ν increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ν values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles

  8. Effects of the cholinestrerase inhibitors donepezil and metrifonate on scopolamine-induced impairments in the spatial cone field orientation task in rats

    NARCIS (Netherlands)

    Staay, van der F.J.; Bouger, P.C.

    2005-01-01

    The aim of these experiments was to assess whether the clinically validated cognition enhancers donepezil (Aricept(TM), E2020) and metrifonate antagonize scopolamine-induced deficits in the cone field, a complex spatial discrimination task. The cone field task allows measurement of the effects of

  9. Enhancing usability using Near Field Communication for mobile application

    Directory of Open Access Journals (Sweden)

    Wihidayat Endar

    2018-01-01

    Full Text Available Near Field Communication (NFC as relatively new wireless communication technology pushes new challenges to application developers to make their applications easier to use and simpler to operate. This point of view known as usability element. Usability is one of the elements for creating good quality applications. This study aims to analyse the usability of mobile-based application embeds with NFC. We also try to evaluate usability in applications used by children. We developed an application called Receptionist which has a primary function as a communication tool between students, teachers and parents at a middle school. To know the impact of the NFC, the Receptionist input system is designed with two methods, via conventional navigation (using buttons and via NFC. To understand the usability of each method, we do user testing and questioners on students. The results show, using the NFC there is a significant increase in usability attributes: efficiency, effectiveness, and learnability. On the other hand, there is decreases of user satisfaction comparing to conventional method. In general, this study demonstrates the potential of new input device technologies that can improve the usability of mobile-based applications.

  10. Pulsed electromagnetic field treatments enhance the healing of fibular osteotomies.

    Science.gov (United States)

    Midura, Ronald J; Ibiwoye, Michael O; Powell, Kimerly A; Sakai, Yoshitada; Doehring, Todd; Grabiner, Mark D; Patterson, Thomas E; Zborowski, Maciej; Wolfman, Alan

    2005-09-01

    This study tested the hypothesis that pulsed electromagnetic field (PEMF) treatments augment and accelerate the healing of bone trauma. It utilized micro-computed tomography imaging of live rats that had received bilateral 0.2 mm fibular osteotomies (approximately 0.5% acute bone loss) as a means to assess the in vivo rate dynamics of hard callus formation and overall callus volume. Starting 5 days post-surgery, osteotomized right hind limbs were exposed 3 h daily to Physio-Stim PEMF, 7 days a week for up to 5 weeks of treatment. The contralateral hind limbs served as sham-treated, within-animal internal controls. Although both PEMF- and sham-treatment groups exhibited similar onset of hard callus at approximately 9 days after surgery, a 2-fold faster rate of hard callus formation was observed thereafter in PEMF-treated limbs, yielding a 2-fold increase in callus volume by 13-20 days after surgery. The quantity of the new woven bone tissue within the osteotomy sites was significantly better in PEMF-treated versus sham-treated fibulae as assessed via hard tissue histology. The apparent modulus of each callus was assessed via a cantilever bend test and indicated a 2-fold increase in callus stiffness in the PEMF-treated over sham-treated fibulae. PEMF-treated fibulae exhibited an apparent modulus at the end of 5-weeks that was approximately 80% that of unoperated fibulae. Overall, these data indicate that Physio-Stim PEMF treatment improved osteotomy repair. These beneficial effects on bone healing were not observed when a different PEMF waveform, Osteo-Stim, was used. This latter observation demonstrates the specificity in the relationship between waveform characteristics and biological outcomes.

  11. Experimental study of induced staggered magnetic fields in dysprosium gallium garnet (DGG)

    International Nuclear Information System (INIS)

    Steiner, M.; Corliss, L.M.; Hastings, J.M.; Blume, M.; Giordano, N.; Wolf, W.P.

    1979-01-01

    Neutron diffraction techniques have been used to study induced staggered magnetic field effects in DGG. The application of a uniform magnetic field at temperatures much greater than the Neel temperature induces a significant amount of antiferromagnetic order. The temperature and field dependences of this effect are in good agreement with recent theoretical predicions

  12. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    Energy Technology Data Exchange (ETDEWEB)

    Shirzaditabar, Farzad; Saliminasab, Maryam [Department of Physics, Razi University, Kermanshah 67144-15111 (Iran, Islamic Republic of)

    2013-05-15

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  13. New parameterization of external and induced fields in geomagnetic field modeling, and a candidate model for IGRF 2005

    DEFF Research Database (Denmark)

    Olsen, Nils; Sabaka, T.J.; Lowes, F.

    2005-01-01

    When deriving spherical harmonic models of the Earth's magnetic field, low-degree external field contributions are traditionally considered by assuming that their expansion coefficient q(1)(0) varies linearly with the D-st-index, while induced contributions are considered assuming a constant ratio......)(0) for each of the 67 months of Orsted and CHAMP data that have been used. We discuss the advantage of this new parameterization of external and induced field for geomagnetic field modeling, and describe the derivation of candidate models for IGRF 2005....

  14. Modeling Microgravity Induced Fluid Redistribution Autoregulatory and Hydrostatic Enhancements

    Science.gov (United States)

    Myers, J. G.; Werner, C.; Nelson, E. S.; Feola, A.; Raykin, J.; Samuels, B.; Ethier, C. R.

    2017-01-01

    Space flight induces a marked cephalad (headward) redistribution of blood and interstitial fluid potentially resulting in a loss of venous tone and reduction in heart muscle efficiency upon introduction into the microgravity environment. Using various types of computational models, we are investigating how this fluid redistribution may induce intracranial pressure changes, relevant to reported reductions in astronaut visual acuity, part of the Visual Impairment and Intracranial Pressure (VIIP) syndrome. Methods: We utilize a lumped parameter cardiovascular system (CVS) model, augmented by compartments comprising the cerebral spinal fluid (CSF) space, as the primary tool to describe how microgravity, and the associated lack of hydrostatic gradient, impacts fluid redistribution. Models of ocular fluid pressures and biomechanics then accept the output of the above model as boundary condition input to allow more detailed, local analysis (see IWS Abstract by Ethier et al.). Recently, we enhanced the capabilities our previously reported CVS model through the implementation of robust autoregulatory mechanisms and a more fundamental approach to the implementation of hydrostatic mechanisms. Modifying the approach of Blanco et al., we implemented auto-regulation in a quasi-static manner, as an averaged effect across the span of one heartbeat. This approach reduced the higher frequency perturbations from the regulatory mechanism and was intended to allow longer simulation times (days) than models that implement within-beat regulatory mechanisms (minutes). A more fundamental approach to hydrostatics was implemented by a quasi-1D approach, in which compartment descriptions include compartment length, orientation and relative position, allowed for modeling of body orientation, relative body positioning and, in the future, alternative gravity environments. At this time the inclusion of hydrostatic mechanisms supplies additional capabilities to train and validate the CVS model

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

    Science.gov (United States)

    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.

  16. Fast Ignition Thermonuclear Fusion: Enhancement of the Pellet Gain by the Colossal-Magnetic-Field Shells

    Science.gov (United States)

    Stefan, V. Alexander

    2013-10-01

    The fast ignition fusion pellet gain can be enhanced by a laser generated B-field shell. The B-field shell, (similar to Earth's B-field, but with the alternating B-poles), follows the pellet compression in a frozen-in B-field regime. A properly designed laser-pellet coupling can lead to the generation of a B-field shell, (up to 100 MG), which inhibits electron thermal transport and confines the alpha-particles. In principle, a pellet gain of few-100s can be achieved in this manner. Supported in part by Nikola Tesla Labs, Stefan University, 1010 Pearl, La Jolla, CA 92038-1007.

  17. Enhancement of critical fields and current of MgB2 by co-doping

    Science.gov (United States)

    Novosel, N.; Galić, S.; Pajić, D.; Skoko, Ž.; Lončarek, I.; Mustapić, M.; Zadro, K.; Babić, E.

    2013-10-01

    The electromagnetic properties of well-characterized iron-sheathed MgB2 wires, undoped and doped with dextrin-coated magnetite nanospheres and nanorods, have been studied in the temperature range 5-300 K and a magnetic field up to 16 T. Doping hardly affected the superconducting transition temperature and the active cross-sectional area of the wires, and increased the low temperature upper critical field, Bc2. Wire doped with nanospheres also showed enhanced irreversibility field, Birr, and low temperature (T ≤ 15 K) critical current density. Magnetization measurements generally confirm the transport results and indicate an enhancement of flux pinning in nanosphere doped wire for T ≤ 20 K. Annealing of wire doped with nanorods at higher temperature (750 ° C) enhanced its critical fields, as expected for co-doping.

  18. Visualizing Electric Fields at Au(111) Step Edges via Tip-Enhanced Raman Scattering

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2017-10-05

    Tip-enhanced Raman scattering (TERS) can be used to image plasmon-enhanced local electric fields on the nanoscale. This is illustrated through ambient TERS measurements recorded using silver atomic force microscope tips coated with 4-mercaptobenzonitrile molecules and used to image step edges on an Au(111) surface. The observed 2D TERS images uniquely map electric fields localized at Au(111) step edges following 671-nm excitation. We establish that our measurements are not only sensitive to spatial variations in the enhanced electric fields but also to their vector components. We also experimentally demonstrate that (i) few nanometer precision is attainable in TERS nanoscopy using corrugated tips with nominally radii on the order of 100-200 nm, and (ii) TERS signals do not necessarily exhibit the expected E4 dependence. Overall, we illustrate the concept of electric field imaging via TERS and establish the connections between our observations and conventional TERS chemical imaging measurements.

  19. Plasma-induced field emission study of carbon nanotube cathode

    Directory of Open Access Journals (Sweden)

    Yi Shen

    2011-10-01

    Full Text Available An investigation on the plasma-induced field emission (PFE properties of a large area carbon nanotube (CNT cathode on a 2 MeV linear induction accelerator injector is presented. Experimental results show that the cathode is able to emit intense electron beams. Intense electron beams of 14.9–127.8  A/cm^{2} are obtained from the cathode. The CNT cathode desorbs gases from the CNTs during the PFE process. The fast cathode plasma expansion affects the diode perveance. The amount of outgassing is estimated to be 0.06–0.49  Pa·L, and the ratio of outgassing and electron are roughly calculated to be within the range of 170–350 atoms per electron. The effect of the outgassing is analyzed, and the outgassing mass spectrum of the CNT cathode has been studied during the PFE. There is a significant desorption of CO_{2}, N_{2}(CO, and H_{2} gases, which plays an important role during the PFE process. All the experiments demonstrate that the outgassing plays an important role in the formation of the cathode plasma. Moreover, the characteristic turn-on time of the CNT cathode was measured to be 39 ns.

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

    Science.gov (United States)

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

    2017-01-05

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

  1. Observation of enhanced electric field in an RF-plugged sheet plasma in the RFC-XX-M open-ended machine

    International Nuclear Information System (INIS)

    Oda, T.; Takiyama, K.; Kadota, K.

    1987-12-01

    We report nonperturbing observation of the electric field in the sheet plasma for RF end-plugging on the RFC XX-M open-ended machine by using the Stark effect with a combined technique of beam-probe and laser-induced fluorescence. Under the optimum condition for the RF plugging, enhanced electric field is found in the sheet plasma by about 2.5 times with respect to the electric field when no plasma is produced. The field spatial profile is also measured, which is discussed in connection with the electrostatic eigenmode. (author)

  2. Field Trapping of Predaceous Insects With Synthetic Herbivore-Induced Plant Volatiles in Cotton Fields.

    Science.gov (United States)

    Yu, Huilin; Khashaveh, Adel; Li, Yunhe; Li, Xiangju; Zhang, Yongjun

    2018-02-08

    Nine herbivore-induced plant volatiles (HIPVs) and one methyl jasmonate were field-tested for their attractiveness to the main predators in cotton fields of North China in 2 yr. The main predators including ladybird beetles (Propylaea japonica (Thunberg), Harmonia axyridis (Pallas)), green lacewings (Chrysoplera sinica (Tjeder), Chrysopa spp.), predatory bugs (Geocoris pallidipennis (Costa), Orius spp., Nabis spp.) and spiders (Misumenops tricuspidatus (Fabricius), Erigonidium graminicolum (Sundevall)) were investigated. Two-way ANOVA indicated that the volatile compound, year, and the volatile compound × year interaction affected the behavioral responses of predators. It was found that indole significantly attracted the ladybird beetle P. japonica, H. axyridis. Linalool could attract P. japonica. Green lacewing C. sinica was significantly attracted by α-pinene and β-pinene, whereas indole significantly attracted Chrysopa spp. Methyl jasmonate and α-pinene showed significant attraction to small-flower bug Orius spp. In addition, the attraction of α-humulene to C. sinica, attractiveness of β-pinene to Orius spp. and Chrysopa spp., were observed only in one of the two years. However, the big-eyed bug G. pallidipennis, damsel bug Nabis spp., spiders M. tricuspiata and E. graminicolum did not respond to any of the tested HIPVs. These results are discussed with respect to possible applications of a synthetic attractant for main predators in cotton fields. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. On Developing Field-Effect-Tunable Nanofluidic Ion Diodes with Bipolar, Induced-Charge Electrokinetics

    Directory of Open Access Journals (Sweden)

    Ye Tao

    2018-04-01

    Full Text Available We introduce herein the induced-charge electrokinetic phenomenon to nanometer fluidic systems; the design of the nanofluidic ion diode for field-effect ionic current control of the nanometer dimension is developed by enhancing internal ion concentration polarization through electrochemical transport of inhomogeneous inducing-counterions resulting from double gate terminals mounted on top of a thin dielectric layer, which covers the nanochannel connected to microfluidic reservoirs on both sides. A mathematical model based on the fully-coupled Poisson-Nernst-Plank-Navier-Stokes equations is developed to study the feasibility of this structural configuration causing effective ionic current rectification. The effect of various physiochemical and geometrical parameters, such as the native surface charge density on the nanochannel sidewalls, the number of gate electrodes (GE, the gate voltage magnitude, and the solution conductivity, permittivity, and thickness of the dielectric coating, as well as the size and position of the GE pair of opposite gate polarity, on the resulted rectification performance of the presented nanoscale ionic device is numerically analyzed by using a commercial software package, COMSOL Multiphysics (version 5.2. Three types of electrohydrodynamic flow, including electroosmosis of 1st kind, induced-charge electroosmosis, and electroosmosis of 2nd kind that were originated by the Coulomb force within three distinct charge layers coexist in the micro/nanofluidic hybrid network and are shown to simultaneously influence the output current flux in a complex manner. The rectification factor of a contrast between the ‘on’ and ‘off’ working states can even exceed one thousand-fold in the case of choosing a suitable combination of several key parameters. Our demonstration of field-effect-tunable nanofluidic ion diodes of double external gate electrodes proves invaluable for the construction of a flexible electrokinetic platform

  4. Enhancement of strong-field multiple ionization in the vicinity of the conical intersection in 1,3-cyclohexadiene ring opening

    International Nuclear Information System (INIS)

    Petrovic, Vladimir S.; Kim, Jaehee; Schorb, Sebastian; White, James; Cryan, James P.; Zipp, Lucas; Glownia, J. Michael; Broege, Douglas; Miyabe, Shungo; Tao, Hongli; Martinez, Todd; Bucksbaum, Philip H.

    2013-01-01

    Nonradiative energy dissipation in electronically excited polyatomic molecules proceeds through conical intersections, loci of degeneracy between electronic states. We observe a marked enhancement of laser-induced double ionization in the vicinity of a conical intersection during a non-radiative transition. We measured double ionization by detecting the kinetic energy of ions released by laser-induced strong-field fragmentation during the ring-opening transition between 1,3-cyclohexadiene and 1,3,5-hexatriene. The enhancement of the double ionization correlates with the conical intersection between the HOMO and LUMO orbitals

  5. Induced-Charge Enhancement of the Diffusion Potential in Membranes with Polarizable Nanopores.

    Science.gov (United States)

    Ryzhkov, I I; Lebedev, D V; Solodovnichenko, V S; Shiverskiy, A V; Simunin, M M

    2017-12-01

    When a charged membrane separates two salt solutions of different concentrations, a potential difference appears due to interfacial Donnan equilibrium and the diffusion junction. Here, we report a new mechanism for the generation of a membrane potential in polarizable conductive membranes via an induced surface charge. It results from an electric field generated by the diffusion of ions with different mobilities. For uncharged membranes, this effect strongly enhances the diffusion potential and makes it highly sensitive to the ion mobilities ratio, electrolyte concentration, and pore size. Theoretical predictions on the basis of the space-charge model extended to polarizable nanopores fully agree with experimental measurements in KCl and NaCl aqueous solutions.

  6. Enhancement of laser-induced optical breakdown using metal/dendrimer nanocomposites

    International Nuclear Information System (INIS)

    Ye Jingyong; Balogh, Lajos; Norris, Theodore B.

    2002-01-01

    We demonstrate that dendrimer nanocomposites (DNC) can be used to remarkably change the laser-induced optical breakdown (LIOB) threshold of a material, owing to a large enhancement of the local electric field. We have implemented LIOB using femtosecond laser pulses in a gold/dendrimer hybrid nanocomposite as a model system. Third-harmonic generation measurements have been employed as a sensitive way for monitoring the LIOB in situ and in real time. The observed statistical behavior of the breakdown process is attributed to a laser-driven aggregation of individual DNC particles. The breakdown threshold value of the DNC has been found to be up to two orders of magnitude lower than that of pure dendrimers or normal tissues

  7. Abnormal magnetization and field-induced transition in (La0.73Bi0.27)0.67Ca0.33MnO3

    International Nuclear Information System (INIS)

    Li Haina; Wu Yuying; Yu Hongwei; Chen Ziyu; Huang Yan; Wang Shaoliang; Li Liang; Xia Zhengcai

    2010-01-01

    The magnetic field dependence of magnetization of Bi doped manganites (La 1-x Bi x ) 0.67 Ca 0.33 MnO 3 (x=0.27) was investigated at different temperatures with a pulsed high magnetic field. A metamagnetic transition was observed in the magnetization measurement, which revealed the coexistence of charge ordering (CO) and ferromagnetic (FM) phases. With decreasing magnetic field, the field-induced FM phases remained stable even when the magnetic field decreased to zero. This result suggests that ferromagnetic interactions are enhanced due to the effect of the pulsed high magnetic field, which makes the doped manganites a good system for magnetoresistance materials.

  8. Field- and irradiation-induced phenomena in memristive nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Mikhaylov, A.N.; Gryaznov, E.G.; Belov, A.I.; Korolev, D.S.; Sharapov, A.N.; Guseinov, D.V.; Tetelbaum, D.I.; Tikhov, S.V.; Malekhonova, N.V.; Bobrov, A.I.; Pavlov, D.A.; Gerasimova, S.A.; Kazantsev, V.B.; Agudov, N.V.; Dubkov, A.A. [Lobachevsky University, Nizhny Novgorod (Russian Federation); Rosario, C.M.M.; Sobolev, N.A. [Departamento de Fisica and I3N, Universidade de Aveiro (Portugal); Spagnolo, B. [Dipartimento di Fisica e Chimica, Universita di Palermo, Group of Interdisciplinary Theoretical Physics (Italy); CNISM, Unita di Palermo (Italy)

    2016-12-15

    The breakthrough in electronics and information technology is anticipated by the development of emerging memory and logic devices, artificial neural networks and brain-inspired systems on the basis of memristive nanomaterials represented, in a particular case, by a simple 'metal-insulator-metal' (MIM) thin-film structure. The present article is focused on the comparative analysis of MIM devices based on oxides with dominating ionic (ZrO{sub x}, HfO{sub x}) and covalent (SiO{sub x}, GeO{sub x}) bonding of various composition and geometry deposited by magnetron sputtering. The studied memristive devices demonstrate reproducible change in their resistance (resistive switching - RS) originated from the formation and rupture of conductive pathways (filaments) in oxide films due to the electric-field-driven migration of oxygen vacancies and / or mobile oxygen ions. It is shown that, for both ionic and covalent oxides under study, the RS behaviour depends only weakly on the oxide film composition and thickness, device geometry (down to a device size of about 20 x 20 μm{sup 2}). The devices under study are found to be tolerant to ion irradiation that reproduces the effect of extreme fluences of high-energy protons and fast neutrons. This common behaviour of RS is explained by the localized nature of the redox processes in a nanoscale switching oxide volume. Adaptive (synaptic) change of resistive states of memristive devices is demonstrated under the action of single or repeated electrical pulses, as well as in a simple model of coupled (synchronized) neuron-like generators. It is concluded that the noise-induced phenomena cannot be neglected in the consideration of a memristive device as a nonlinear system. The dynamic response of a memristive device to periodic signals of complex waveform can be predicted and tailored from the viewpoint of stochastic resonance concept. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Evidence for lattice-polarization-enhanced field effects at the SrTiO3-based heterointerface

    DEFF Research Database (Denmark)

    Li, Y.; R. Zhang, H.; Lei, Y.

    2016-01-01

    Electrostatic gating provides a powerful approach to tune the conductivity of the two-dimensionalelectron liquid between two insulating oxides. For the LaAlO3/SrTiO3 (LAO/STO) interface, suchgating effect could be further enhanced by a strong lattice polarization of STO caused by simultaneousappl......Electrostatic gating provides a powerful approach to tune the conductivity of the two-dimensionalelectron liquid between two insulating oxides. For the LaAlO3/SrTiO3 (LAO/STO) interface, suchgating effect could be further enhanced by a strong lattice polarization of STO caused...... expansion of the out-of-plane lattice of STO. Photo excitation affects the polarizationprocess by accelerating the field-induced lattice expansion. The present work demonstrates the greatpotential of combined stimuli in exploring emergent phenomenon at complex oxide interfaces....

  10. Safety Culture Enhancement Project. Final Report. A Field Study on Approaches to Enhancement of Safety Culture

    International Nuclear Information System (INIS)

    Lowe, Andrew; Hayward, Brent

    2006-08-01

    This report documents a study with the objective of enhancing safety culture in the Swedish nuclear power industry. A primary objective of this study was to ensure that the latest thinking on human factors principles was being recognised and applied by nuclear power operators as a means of ensuring optimal safety performance. The initial phase of the project was conducted as a pilot study, involving the senior management group at one Swedish nuclear power-producing site. The pilot study enabled the project methodology to be validated after which it was repeated at other Swedish nuclear power industry sites, providing a broad-ranging analysis of opportunities across the industry to enhance safety culture. The introduction to this report contains an overview of safety culture, explains the background to the project and sets out the project rationale and objectives. The methodology used for understanding and analysing the important safety culture issues at each nuclear power site is then described. This section begins with a summary of the processes used in the information gathering and data analysis stage. The six components of the Management Workshops conducted at each site are then described. These workshops used a series of presentations, interactive events and group exercises to: (a) provide feedback to site managers on the safety culture and safety leadership issues identified at their site, and (b) stimulate further safety thinking and provide 'take-away' information and leadership strategies that could be applied to promote safety culture improvements. Section 3, project Findings, contains the main observations and output from the project. These include: - a brief overview of aspects of the local industry operating context that impinge on safety culture; - a summary of strengths or positive attributes observed within the safety culture of the Swedish nuclear industry; - a set of identified opportunities for further improvement; - the aggregated results of the

  11. Safety Culture Enhancement Project. Final Report. A Field Study on Approaches to Enhancement of Safety Culture

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, Andrew; Hayward, Brent (Dedale Asia Pacific, Albert Park VIC 3206 (Australia))

    2006-08-15

    This report documents a study with the objective of enhancing safety culture in the Swedish nuclear power industry. A primary objective of this study was to ensure that the latest thinking on human factors principles was being recognised and applied by nuclear power operators as a means of ensuring optimal safety performance. The initial phase of the project was conducted as a pilot study, involving the senior management group at one Swedish nuclear power-producing site. The pilot study enabled the project methodology to be validated after which it was repeated at other Swedish nuclear power industry sites, providing a broad-ranging analysis of opportunities across the industry to enhance safety culture. The introduction to this report contains an overview of safety culture, explains the background to the project and sets out the project rationale and objectives. The methodology used for understanding and analysing the important safety culture issues at each nuclear power site is then described. This section begins with a summary of the processes used in the information gathering and data analysis stage. The six components of the Management Workshops conducted at each site are then described. These workshops used a series of presentations, interactive events and group exercises to: (a) provide feedback to site managers on the safety culture and safety leadership issues identified at their site, and (b) stimulate further safety thinking and provide 'take-away' information and leadership strategies that could be applied to promote safety culture improvements. Section 3, project Findings, contains the main observations and output from the project. These include: - a brief overview of aspects of the local industry operating context that impinge on safety culture; - a summary of strengths or positive attributes observed within the safety culture of the Swedish nuclear industry; - a set of identified opportunities for further improvement; - the aggregated

  12. Electromagnetically Induced Transparency and Absorption of A Monochromatic Light Controlled by a Radio Frequency Field

    International Nuclear Information System (INIS)

    Cai Xun-Ming

    2015-01-01

    Electromagnetically induced transparency and absorption of a monochromatic light controlled by a radio frequency field in the cold multi-Zeeman-sublevel atoms are theoretically investigated. These Zeeman sublevels are coupled by a radio frequency (RF) field. Both electromagnetically induced transparency and electromagnetically induced absorption can be obtained by tuning the frequency of RF field for both the linear polarization and elliptical polarization monochromatic lights. When the transfer of coherence via spontaneous emission from the excited state to the ground state is considered, electromagnetically induced absorption can be changed into electromagnetically induced transparency with the change of intensity of radio field. The transparency windows controlled by the RF field can have potential applications in the magnetic-field measurement and quantum information processing. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  13. Recollision induced excitation-ionization with counter-rotating two-color circularly polarized laser field

    Science.gov (United States)

    Ben, Shuai; Guo, Pei-Ying; Pan, Xue-Fei; Xu, Tong-Tong; Song, Kai-Li; Liu, Xue-Shen

    2017-07-01

    Nonsequential double ionization of Ar by a counter-rotating two-color circularly polarized laser field is theoretically investigated. At the combined intensity in the "knee" structure range, the double ionization occurs mainly through recollision induced excitation followed by subsequent ionization of Ar+∗ . By tracing the history of the recollision trajectories, we explain how the relative intensity ratio of the two colors controls the correlated electron dynamics and optimizes the ionization yields. The major channels contributing to enhancing the double ionization are through the elliptical trajectories with smaller travel time but not through the triangle shape or the other long cycle trajectories. Furthermore, the correlated electron dynamics could be limited to the attosecond time scale by adjusting the relative intensity ratio. Finally, the double ionization from doubly excited complex at low laser intensity is qualitatively discussed.

  14. Subchronic Arsenic Exposure Induces Anxiety-Like Behaviors in Normal Mice and Enhances Depression-Like Behaviors in the Chemically Induced Mouse Model of Depression

    Directory of Open Access Journals (Sweden)

    Chia-Yu Chang

    2015-01-01

    Full Text Available Accumulating evidence implicates that subchronic arsenic exposure causes cerebral neurodegeneration leading to behavioral disturbances relevant to psychiatric disorders. However, there is still little information regarding the influence of subchronic exposure to arsenic-contaminated drinking water on mood disorders and its underlying mechanisms in the cerebral prefrontal cortex. The aim of this study is to assess the effects of subchronic arsenic exposure (10 mg/LAs2O3 in drinking water on the anxiety- and depression-like behaviors in normal mice and in the chemically induced mouse model of depression by reserpine pretreatment. Our findings demonstrated that 4 weeks of arsenic exposure enhance anxiety-like behaviors on elevated plus maze (EPM and open field test (OFT in normal mice, and 8 weeks of arsenic exposure augment depression-like behaviors on tail suspension test (TST and forced swimming test (FST in the reserpine pretreated mice. In summary, in this present study, we demonstrated that subchronic arsenic exposure induces only the anxiety-like behaviors in normal mice and enhances the depression-like behaviors in the reserpine induced mouse model of depression, in which the cerebral prefrontal cortex BDNF-TrkB signaling pathway is involved. We also found that eight weeks of subchronic arsenic exposure are needed to enhance the depression-like behaviors in the mouse model of depression. These findings imply that arsenic could be an enhancer of depressive symptoms for those patients who already had the attribute of depression.

  15. Laser ablation of polymer coatings allows for electromagnetic field enhancement mapping around nanostructures

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    2011-01-01

    Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures. The acc......Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures....... The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron microscopy and atomic force microscopy...

  16. Electron-beam induced current characterization of back-surface field solar cells using a chopped scanning electron microscope beam

    Science.gov (United States)

    Luke, K. L.; Cheng, L.-J.

    1984-01-01

    A chopped electron beam induced current (EBIC) technique for the chacterization of back-surface field (BSF) solar cells is presented. It is shown that the effective recombination velocity of the low-high junction forming the back-surface field of BSF cells, in addition to the diffusion length and the surface recombination velocity of the surface perpendicular to both the p-n and low-high junctions, can be determined from the data provided by a single EBIC scan. The method for doing so is described and illustrated. Certain experimental considerations taken to enhance the quality of the EBIC data are also discussed.

  17. Deriving the geomagnetically induced electric field at the Earth's surface from the time derivative of the vertical magnetic field

    Science.gov (United States)

    Vanhamäki, Heikki; Viljanen, Ari; Pirjola, Risto; Amm, Olaf

    2013-09-01

    We present a new method for estimating the geomagnetically induced electric field at the Earth's surface directly from the time derivative of the vertical magnetic field, without any need for additional information about the Earth's electric conductivity. This is a simplification compared to the presently used calculation methods, which require both the magnetic variation field and ground conductivity model as input data. The surface electric field is needed e.g. in modeling Geomagnetically Induced Currents (GIC) that flow in man-made conductor systems, such as gas and oil pipelines or high-voltage power grids. We solve the induced electric field directly from Faraday's law, by representing the magnetic variation field in terms of external equivalent current and taking time derivative of the associated vector potential. This gives an approximative solution, where the divergence-free part of the electric field is reproduced accurately (at least in principle), but the curl-free part related to lateral variations in ground conductivity is completely neglected. We test the new calculation method with several realistic models of typical ionospheric current systems, as well as actual data from the Baltic Electromagnetic Array Research (BEAR) network. We conclude that the principle of calculating the (divergence-free part of the) surface electric field from time derivative of the vertical magnetic field is sound, and the method works reasonably well also in practice. However, practical applications may be rather limited as the method seems to require data from a quite dense and spatially extended magnetometer network.

  18. Global enhancement and structure formation of the magnetic field in spiral galaxies

    Science.gov (United States)

    Khoperskov, Sergey A.; Khrapov, Sergey S.

    2018-01-01

    In this paper we study numerically large-scale magnetic field evolution and its enhancement in gaseous disks of spiral galaxies. We consider a set of models with the various spiral pattern parameters and the initial magnetic field strength with taking into account gas self-gravity and cooling and heating processes. In agreement with previous studies we find out that galactic magnetic field is mostly aligned with gaseous structures, however small-scale gaseous structures (spurs and clumps) are more chaotic than the magnetic field structure. In spiral arms magnetic field often coexists with the gas distribution, in the inter-arm region we see filamentary magnetic field structure. These filaments connect several isolated gaseous clumps. Simulations reveal the presence of the small-scale irregularities of the magnetic field as well as the reversal of magnetic field at the outer edge of the large-scale spurs. We provide evidences that the magnetic field in the spiral arms has a stronger mean-field component, and there is a clear inverse correlation between gas density and plasma-beta parameter, compared to the rest of the disk with a more turbulent component of the field and an absence of correlation between gas density and plasma-beta. We show the mean field growth up to >3-10 μG in the cold gas during several rotation periods (>500-800 Myr), whereas ratio between azimuthal and radial field is equal to >4/1. We find an enhancement of random and ordered components of the magnetic field. Mean field strength increases by a factor of >1.5-2.5 for models with various spiral pattern parameters. Random magnetic field component can reach up to 25% from the total strength. By making an analysis of the time-dependent evolution of the radial Poynting flux, we point out that the magnetic field strength is enhanced more strongly at the galactic outskirts which is due to the radial transfer of magnetic energy by the spiral arms pushing the magnetic field outward. Our results also

  19. Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

    International Nuclear Information System (INIS)

    Song, Meng; Xu, Peng; Wang, Xu; Wu, Huizhen; Wang, Miao; Song, Yenan; Li, Zhenhua; Zhao, Pei; Shang, Xuefu

    2015-01-01

    Integrating carbon nanotubes (CNTs) and graphene into hybrid structures provides a novel approach to three dimensional (3D) materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm 2 , and field enhancement factor of ∼1.3 × 10 4 . The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport

  20. Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Fang, Yurui; Zhang, Zhenglong; Chen, Li; Sun, Mengtao

    2015-01-14

    Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

  1. In situ generated CdS nanostructure induced enhanced photoluminescence from Dy{sup 3+} ions doped dielectric nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Chirantan; Karmakar, Basudeb [Glass Science and Technology Section, Glass Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India)

    2017-08-15

    We report CdS nanostructure induced enhanced photoluminescence (PL) from Dy{sup +3}:CdS co-doped dielectric-nanocomposites synthesized by the conventional melt-quench technique. CdS nanocrystals (NCs) were synthesized as in situ within the dielectric medium and their growth was controlled by heat treatment duration. Nanoparticles were investigated with absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Raman spectroscopy. The experimentally obtained sizes of the NCs are found to increase from 5-11 nm to 50-80 nm. Bandgap enhancement for the carrier confinement was found to alter within the range of 0.20-0.38 eV. Phonon confinement effect has been confirmed by blue shifting of Raman peak for CdS NCs at 303 cm{sup -1}. Enhanced highly intense sharp PL peak at 576 nm was detected, and different parameters associated with the PL enhancement including energy transfer from CdS NCs to Dy{sup 3+} ions have been studied. This PL enhancement was steered by varying CdS NC sizes. Enhanced PL of these nanocomposites finds their potential applications as gain medium in the field of solid state lasers. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Enhanced field emission of ZnO nanoneedle arrays via solution etching at room temperature

    DEFF Research Database (Denmark)

    Ma, Huanming; Qin, Zhiwei; Wang, Zaide

    2017-01-01

    ZnO nanoneedle arrays (ZnO nns) were synthesized by a facile two-step solution-phase method based on the etching of pre-synthesized ZnO nanowire arrays (ZnO nws) with flat ends at room temperature. Field emission measurement results showed that the turn-on electronic fields of ZnO nns and nws wer...... 2.7 and 5.3 V μm−1 at a current density of 10 μA cm−2, and the field enhancement factors were 4939.3 for ZnO nns and 1423.6 for ZnO nws. The enhanced field emission properties in ZnO nns were ascribed to the sharp tip geometry....

  3. Variational infrared image enhancement based on adaptive dual-threshold gradient field equalization

    Science.gov (United States)

    Zhao, Wenda; Xu, Zhijun; Zhao, Jian; Zhao, Fan; Han, Xizhen

    2014-09-01

    Infrared images are characterized by low signal to noise ratio (SNR) and fuzzy texture edges. This article introduces the variational infrared image enhancement algorithm based on gradient field equalization with adaptive dual thresholds. Firstly, we transform the image into gradient domain and get the gradient histogram. Then, we do the gradient histogram equalization. By setting adaptive dual thresholds to qualify the gradients, the image is prevented from over enhancement. The total variation (TV) model is adopted in the reconstruction of the enhanced image to suppress noise. It is shown from experimental results that the image edge details are significantly enhanced, and therefore the algorithm is qualified for enhancement of infrared images in different applications.

  4. Shear-induced inflation of coronal magnetic fields

    International Nuclear Information System (INIS)

    Klimchuk, J.A.

    1990-01-01

    Using numerical models of force-free magnetic fields, the shearing of footprints in arcade geometries leading to an inflation of the coronal magnetic field was examined. For each of the shear profiles considered, all of the field lines become elevated compared with the potential field. This includes cases where the shear is concentrated well away from the arcade axis, such that B(sub z), the component of field parallel to the axis, increases outward to produce an inward B(sub z) squared/8 pi magnetic pressure gradient force. These results contrast with an earlier claim, shown to be incorrect, that field lines can sometimes become depressed as a result of shear. It is conjectured that an inflation of the entire field will always result from the shearing of simple arcade configurations. These results have implications for prominence formation, the interplanetary magnetic flux, and possibly also coronal holes. 38 refs

  5. Depth enhancement of multi-layer light field display using polarization dependent internal reflection.

    Science.gov (United States)

    Jo, Na-Young; Lim, Hong-Gi; Lee, Sung-Keun; Kim, Yong-Soo; Park, Jae-Hyeung

    2013-12-02

    A technique to enhance the depth range of the multi-layer light field three-dimensional display is proposed. A set of the optical plates are stacked in front of the conventional multi-layer light field display, creating additional internal reflection for one polarization state. By switching between two orthogonal polarization states in synchronization with the displayed three-dimensional images, the depth range of the display can be doubled. The proposed method is verified experimentally, confirming its feasibility.

  6. Hedgerows enhance beneficial insects on adjacent tomato fields in an intensive agricultural landscape

    OpenAIRE

    Morandin, LA; Long, RF; Kremen, C

    2014-01-01

    Within-farm habitat enhancements such as hedgerows could aid pest control in adjacent crops; however, there is little information on whether small-scale restoration impacts pests and natural enemies, and crop damage, and how far effects may extend into fields. We compared restored, California native perennial hedgerows to unenhanced field edges consisting of commonly occurring semi-managed, non-native weeds. Pest and natural enemy communities were assessed in both edge types and into adjacent...

  7. Investigations of scattering and field enhancement effects in retardation-based plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Nielsen, M. G.; Pors, A.; Nielsen, Rasmus Bundgaard

    2010-01-01

    Modifications in scattering strength of and local field enhancement by retardation-based plasmonic nanoantennas when being transformed from straight nanorods to split-rings are investigated. The scattering properties are monitored by linear reflection and extinction spectroscopy whereas local field......, a feature that we attribute to the decrease in the nanoantenna electric-dipole response in tact with its bending. The experimental observations are corroborated with numerical simulations using the finite-element method....

  8. Magnetic field can alleviate toxicological effect induced by cadmium in mungbean seedlings.

    Science.gov (United States)

    Chen, Yi-ping; Li, Ran; He, Jun-Min

    2011-06-01

    To alleviate toxicological effect induced by cadmium in mungbean seedlings, seeds were divided into four groups: The controls groups (CK, without treatment), magnetic field treated groups (MF), cadmium treated groups (CS), and magnetic field treated followed by cadmium treated groups (MF + CS).The results showed: (i) Compared with the controls, cadmium stress resulted in enhancing in the concentration of malondialdehyde, H(2)O(2) and O(2-), and the conductivity of electrolyte leakage while decreasing in the nitrice oxide synthase (NOS) activity, the concentration of nitrice oxide (NO), chlorophyll and total carbon and nitrogen, the net photosynthetic rate, the stomatal conductance, the transpiration rate, the water use efficiency, the lateral number and seedlings growth except for intercellular CO(2) concentration increase. However, the seedlings treated with 600 mT magnetic field followed by cadmium stress the concentration of malondialdehyde, H(2)O(2) and O(2-), and the conductivity of electrolyte leakage decreased, while the above mentioned NO concentration, NOS activity, photosynthesis and growth parameters increased compared to cadmium stress alone. (ii) Compared with the cadmium stress (CS), the seedling growth were inhibited when the seeds were treated with NO scavenger (hemoglobin, HB) and inhibition of NO generating enzyme (sodium tungstate, ST), conversely, the seedling growth were improved by the NO donor sodium nitroprusside (SNP) and CaCl(2). In the case of the HB and ST treatment followed by magnetic field and then the seedling subjected to CS, the seedlings growth was better than that of hemoglobin (HB) followed by CS and ST followed by CS. The seeds were treated with SNP and CaCl(2) followed by MF, and then subjected to CS, the seedlings growth were better than that of SNP followed by CS, and CaCl(2) followed by CS. These results suggested that magnetic field compensates for the toxicological effects of cadmium exposure are related to NO signal.

  9. Protocol for Addressing Induced Seismicity Associated with Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Majer, Ernie [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Nelson, James [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Robertson-Tait, Ann [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Savy, Jean [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States); Wong, Ivan [Office of Energy Efficiency and Renewable Energy (EERE), Washington, DC (United States)

    2012-01-01

    This Protocol is a living guidance document for geothermal developers, public officials, regulators and the general public that provides a set of general guidelines detailing useful steps to evaluate and manage the effects of induced seismicity related to EGS projects.

  10. Chalcones Enhance TRAIL-Induced Apoptosis in Prostate Cancer Cells

    OpenAIRE

    Szliszka, Ewelina; Czuba, Zenon P.; Mazur, Bogdan; Sedek, Lukasz; Paradysz, Andrzej; Krol, Wojciech

    2009-01-01

    Chalcones exhibit chemopreventive and antitumor effects. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a naturally occurring anticancer agent that induces apoptosis in cancer cells and is not toxic to normal cells. We examined the cytotoxic and apoptotic effect of five chalcones in combination with TRAIL on prostate cancer cells. The cytotoxicity was evaluated by the MTT and LDH assays. The apoptosis was determined using flow cytometry with annexin V-FITC. Our study showe...

  11. Measurement Induced Enhancement of Squeezing in Nondegenerate Two-Photon Jaynes-Cummings Model

    International Nuclear Information System (INIS)

    Ye Saiyun

    2006-01-01

    Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement.

  12. 50Hz Extremely Low Frequency Electromagnetic Fields Enhance Protein Carbonyl Groups Content in Cancer Cells: Effects on Proteasomal Systems

    Directory of Open Access Journals (Sweden)

    A. M. Eleuteri

    2009-01-01

    Full Text Available Electromagnetic fields are an assessed cause of prolonging free radicals lifespan. This study was carried out to investigate the influence of extremely low frequency electromagnetic fields on protein oxidation and on the 20S proteasome functionality, the complex responsible for the degradation of oxidized proteins. Caco 2 cells were exposed, for 24–72 hours, to 1 mT, 50 Hz electromagnetic fields. The treatment induced a time-dependent increase both in cell growth and in protein oxidation, more evident in the presence of TPA, while no changes in cell viability were detected. Exposing the cells to 50 Hz electromagnetic fields caused a global activation of the 20S proteasome catalytic components, particularly evident at 72 hours exposure and in the presence of TPA. The finding that EGCG, a natural antioxidant compound, counteracted the field-related pro-oxidant effects demonstrates that the increased proteasome activity was due to an enhancement in intracellular free radicals.

  13. Nanoscale investigation of enhanced electron field emission for silver ion implanted/post-annealed ultrananocrystalline diamond films.

    Science.gov (United States)

    Panda, Kalpataru; Hyeok, Jeong Jin; Park, Jeong Young; Sankaran, Kamatchi Jothiramalingam; Balakrishnan, Sundaravel; Lin, I-Nan

    2017-11-24

    Silver (Ag) ions are implanted in ultrananocrystalline diamond (UNCD) films to enhance the electron field emission (EFE) properties, resulting in low turn-on field of 8.5 V/μm with high EFE current density of 6.2 mA/cm 2 (at an applied field of 20.5 V/μm). Detailed nanoscale investigation by atomic force microscopy based peak force-controlled tunneling atomic force microscopy (PF-TUNA) and ultra-high vacuum scanning tunneling microscopy (STM) based current imaging tunneling spectroscopy (CITS) reveal that the UNCD grain boundaries are the preferred electron emission sites. The two scanning probe microscopic results supplement each other well. However, the PF-TUNA measurement is found to be better for explaining the local electron emission behavior than the STM-based CITS technique. The formation of Ag nanoparticles induced abundant sp 2 nanographitic phases along the grain boundaries facilitate the easy transport of electrons and is believed to be a prime factor in enhancing the conductivity/EFE properties of UNCD films. The nanoscale understanding on the origin of electron emission sites in Ag-ion implanted/annealed UNCD films using the scanning probe microscopic techniques will certainly help in developing high-brightness electron sources for flat-panel displays applications.

  14. Magnetic-field-induced suppression of the amorphous blue phase.

    Science.gov (United States)

    Challa, P K; Sprunt, S N; Jákli, A; Gleeson, J T

    2014-01-01

    We present magneto-optical measurements on two liquid crystals that exhibit a wide temperature-range amorphous blue phase (BPIII). Magnetic fields up to 25 T are found to suppress the onset of BPIII in both materials by almost 1 °C. This effect appears to increase nonlinearly with the field strength. The effect of high fields on established BPIIIs is also reported, in which we find significant hysteresis and very slow dynamics. Possible explanations of these results are discussed.

  15. Pressure-induced superconductivity in a ferromagnet, UGe{sub 2}: resistivity measurements in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, T.C. [Kyokugen, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Hanazono, K. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Tateiwa, N. [Kyokugen, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Amaya, K. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Haga, Y. [Advanced Science Research Centre, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Settai, R. [Graduate School of Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Onuki, Y. [Advanced Science Research Centre, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan)

    2002-11-11

    Electrical resistivity measurements in a magnetic field are carried out on UGe{sub 2} which exhibits pressure-induced superconductivity. The superconductivity is observed from 1.06 to 1.44 GPa. In the temperature and field dependences of the resistivity at P > P{sub C} where the ferromagnetic ordering disappears, it is observed that the application of an external field along the a-axis increases the coefficient A of the Fermi-liquid behaviour ({proportional_to} AT{sup 2}) abruptly - corresponding to the metamagnetic transition. The characteristic enhancement of H{sub C2} is reconfirmed for H || a-axis. The upper critical field of H{sub C2} is anisotropic: H{sub C2} (T) exhibits positive curvature for H || b-axis and H || c-axis.

  16. Vacuum radiation induced by time dependent electric field

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2017-04-01

    Full Text Available Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  17. Vacuum radiation induced by time dependent electric field

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo, E-mail: zhangbolfrc@caep.cn [Department of High Energy Density Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Laboratory of Science and Technology on Plasma Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian [Department of High Energy Density Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Laboratory of Science and Technology on Plasma Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Gu, Yu-qiu, E-mail: yqgu@caep.cn [Department of High Energy Density Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Laboratory of Science and Technology on Plasma Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China)

    2017-04-10

    Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  18. Structural control of metamaterial oscillator strength and electric field enhancement at terahertz frequencies

    DEFF Research Database (Denmark)

    Keiser, G. R.; Seren, H. R.; Strikwerda, Andrew C.

    2014-01-01

    The design of artificial nonlinear materials requires control over internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists...... of a split ring resonator (SRR) array stacked above an array of closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in an increase of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field...

  19. Numerical simulation of positive streamer development in thundercloud field enhanced near raindrops

    DEFF Research Database (Denmark)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

    2016-01-01

    As the threshold field strength for the breakdown in air significantly exceeds the maximum measured thundercloud strength 3 kV/cm/atm, the problem of lightning initiation remains unclear. According to the popular idea, lightning can be initiated from streamer discharges developed in the enhanced ...

  20. Comment on 'Model calculation of the scanned field enhancement factor of CNTs'

    International Nuclear Information System (INIS)

    Zhbanov, A I; Lee, Yong-Gu; Pogorelov, E G; Chang, Yia-Chung

    2010-01-01

    The model proposed by Ahmad and Tripathi (2006 Nanotechnology 17 3798) demonstrates that the field enhancement factor of carbon nanotubes (CNTs) reaches a maximum at a certain length. Here, we show that this behavior should not occur and suggest our correction to this model. (comment)

  1. Momentum transport studies in JET H-mode discharges with an enhanced toroidal field ripple

    NARCIS (Netherlands)

    de Vries, P. C.; Versloot, T. W.; Salmi, A.; Hua, M. D.; Howell, D. H.; Giroud, C.; Parail, V.; Saibene, G.; Tala, T.

    2010-01-01

    In this study, enhancement of the toroidal field (TF) ripple has been used as a tool in order to reveal the impact of the momentum pinch on the rotation profiles in H-mode JET discharges. The analysis showed that flatter rotation profiles were obtained in discharges with a high TF ripple, attributed

  2. Two-photon mapping of localized field enhancements in thin nanostrip antennas

    DEFF Research Database (Denmark)

    Beermann, I.; Novikov, S.M.; Søndergaard, Thomas

    2008-01-01

    Resonant scattering and local field enhancements by 11-nm-thin gold nanostrip antennas due to constructive interference of counter propagating slow surface plasmon polaritons is investigated. We characterize nanostrips of widths between 50-530 nm using both reflection spectroscopy and nonlinear...

  3. New parameterization of external and induced fields in geomagnetic field modeling, and a candidate model for IGRF 2005

    DEFF Research Database (Denmark)

    Olsen, Nils; Sabaka, T.J.; Lowes, F.

    2005-01-01

    Q(1) of induced to external coefficients. A value of Q(1) = 0.27 was found from Magsat data and has been used by several authors when deriving recent field models from Orsted and CHAMP data. We describe a new approach that considers external and induced field based on a separation of D-st = E-st + I......-st into external (E-st) and induced (I-st) parts using a 1D model of mantle conductivity. The temporal behavior of q(1)(0) and of the corresponding induced coefficient are parameterized by E-st and I-st, respectively. In addition, we account for baseline-instabilities of D-st by estimating a value of q(1...

  4. Radiation-induced conduction under high electric field (1 x 106 to 1 x 108 V/m) in polyethylene-terephthalate

    International Nuclear Information System (INIS)

    Maeda, H.; Kurashige, M.; Ito, D.; Nakakita, T.

    1978-01-01

    Radiation-induced conduction in polyethylene-terephthalate (PET) has been measured under high electric field (1.0 x 10 6 to 1.6 x 10 8 V/m). In a 6-μm-thick PET film, saturation of the radiation-induced current occurs at field strengths above 1.2 x 10 8 V/m. This has been demonstrated by the thickness and dose rate dependence of the induced current. Radiation-induced conductivity increases monotonically with field strength, then shows a saturation tendency. This may be explained by geminate recombination. Above 1 x 10 8 V/m, slowly increasing radiation-induced current appears. This may be caused by electron injection from the cathode, enhanced by the accumulation of the hetero space charges near it

  5. Perceived location specificity in perceptual separation-induced but not fear conditioning-induced enhancement of prepulse inhibition in rats.

    Science.gov (United States)

    Lei, Ming; Luo, Lu; Qu, Tianshu; Jia, Hongxiao; Li, Liang

    2014-08-01

    Prepulse inhibition (PPI) is the suppression of the startle reflex when the startling stimulus is shortly preceded by a non-startling stimulus (the prepulse). Previous studies have shown that both fear conditioning of a prepulse and precedence-effect-induced perceptual separation between the conditioned prepulse and a noise masker facilitate selective attention to the prepulse and consequently enhance PPI with a remarkable prepulse-feature specificity. This study investigated whether the two types of attentional enhancements of PPI in rats also exhibit a prepulse-location specificity. The results showed that when a prepulse was delivered by each of the two spatially separated loudspeakers, fear conditioning of the prepulse at a particularly perceived location (left or right to the tested rat) enhanced PPI without exhibiting any perceived-location specificity. However, when a noise masker was presented, the precedence-effect-induced perceptual separation between the conditioned prepulse and the noise masker further enhanced PPI when the prepulse was perceived as coming from the location that was conditioned but not the location without being conditioned. Moreover, both conditioning-induced and perceptual separation-induced PPI enhancements were eliminated by extinction learning, whose effect could be blocked by systemic injection of the selective antagonist of metabotropic glutamate receptor subtype 5 (mGluR5), 2-methyl-6-(phenylethynyl)-pyridine (MPEP). Thus, fear conditioning of a prepulse perceived at a particular location not only facilitates selective attention to the conditioned prepulse but also induces a learning-based spatial gating effect on the spatial unmasking of the conditioned prepulse, leading to that the perceptual separation-induced PPI enhancement becomes perceived-location specific. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Nanoantenna array-induced fluorescence enhancement and reduced lifetimes

    DEFF Research Database (Denmark)

    Bakker, R. M.; Drachev, V. P.; Liu, Z.

    2008-01-01

    Enhanced fluorescence is observed from dye molecules interacting with optical nanoantenna arrays. Elliptical gold dimers form individual nanoantennae with tunable plasmon resonances depending upon the geometry of the two particles and the size of the gap between them. A fluorescent dye, Rhodamine...... 800, is uniformly embedded in a dielectric host that coats the nanoantennae. The nanoantennae act to enhance the dye absorption. In turn, emission from the dye drives the plasmon resonance of the antennae; the nanoantennae act to enhance the fluorescence signal and change the angular distribution...... of emission. These effects depend upon the overlap of the plasmon resonance with the excitation wavelength and the fluorescence emission band. A decreased fluorescence lifetime is observed along with highly polarized emission that displays the characteristics of the nanoantenna's dipole mode. Being able...

  7. Vastly enhancing the chemical stability of phosphorene by employing an electric field.

    Science.gov (United States)

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2017-03-23

    Currently, a major hurdle preventing phosphorene from various electronic applications is its rapid oxidation under ambient conditions. Thus how to enhance its chemical stability by suppressing oxidation becomes an urgent task. Here, we reveal a highly effective procedure to suppress the oxidation of phosphorene by employing a suitable van der Waals (vdW) substrate and a vertical electric field. Our first-principles study shows that the phosphorene-MoSe 2 vdW heterostructure is able to reverse the stability of physisorption and chemisorption of molecular O 2 on phosphorene. With further application of a vertical electric field of -0.6 V Å -1 , the energy barrier for oxidation is able to further increase to 0.91 eV, leading to a 10 5 times enhancement in its lifetime compared with that without using the procedure at room temperature. Our work presents a viable strategy to vastly enhance the chemical stability of phosphorene in air.

  8. Refractive index dependent local electric field enhancement in cylindrical gold nanohole

    International Nuclear Information System (INIS)

    Zhu Jian

    2011-01-01

    We report on the local electric field characters in a long cylindrical gold nanohole. Theoretical calculation results based on quasi-static model show that the local environmental dielectric constant dependent electric field intensity and field distribution in the gold nanohole show quite unique properties, different from those in the thin gold nanotube. Because of the thick gold wall, no plasmon hybridization exists. So there is only one resonance frequency taking place, and the intense local field has been focused into the gold nanohole. Our main finding is that, the local field in the nanohole is largely dependent on the inner hole refractive index and outer environmental refractive index. The competition between inner hole and outer polarization leads to a non-monotonic change of the local field intensity with increasing the dielectric constant of the nanohole. This refractive index controlled local field enhancement in cylindrical gold nanohole presents a potential for tunable surface-enhanced fluorescence and novel nano-optical biosensing applications.

  9. Subquantum nonlocal correlations induced by the background random field

    International Nuclear Information System (INIS)

    Khrennikov, Andrei

    2011-01-01

    We developed a purely field model of microphenomena-prequantum classical statistical field theory (PCSFT). This model not only reproduces important probabilistic predictions of quantum mechanics (QM) including correlations for entangled systems, but also gives a possibility to go beyond QM, i.e. to make predictions of phenomena that could be observed at the subquantum level. In this paper, we discuss one such prediction-the existence of nonlocal correlations between prequantum random fields corresponding to all quantum systems. (And by PCSFT, quantum systems are represented by classical Gaussian random fields and quantum observables by quadratic forms of these fields.) The source of these correlations is the common background field. Thus all prequantum random fields are 'entangled', but in the sense of classical signal theory. On the one hand, PCSFT demystifies quantum nonlocality by reducing it to nonlocal classical correlations based on the common random background. On the other hand, it demonstrates total generality of such correlations. They exist even for distinguishable quantum systems in factorizable states (by PCSFT terminology-for Gaussian random fields with covariance operators corresponding to factorizable quantum states).

  10. Magnetic field induced assembling of nanoparticles in ferrofluidic ...

    Indian Academy of Sciences (India)

    Unknown

    The effect of a magnetic field on these thin films will have a profound influence on the birefringent properties of these fluid films. If an external magnetic field is applied parallel to .... mission through ferrofluid thin film (Normal incidence and de- tection with respect to ... lation, only the Zeeman energy term (Ez = –µH cosθ) is.

  11. Nuclear beta decay induced by intense electromagnetic fields: Basic theory

    International Nuclear Information System (INIS)

    Reiss, H.R.

    1983-01-01

    A basic formalism is developed for the theory of the effect on nuclear beta decay of an intense, plane-wave electromagnetic field. Interactions of the field with both the nuclear particles and the decay electron are included. The formalism is developed from first principles, including a derivation of transition probabilities between explicitly time-dependent asymptotic states. Interaction of the field with the nucleus is analyzed in terms of separation of the nucleus into an inert core and a fragment. The field interacts with the fragment, consisting of the nucleons which are candidates for beta decay, plus any other nucleons angular-momentum coupled to them in initial or final states. A separation of variables in the dynamical equations for the nucleus into center-of-mass and relative coordinates for the core and fragment shows direct charge coupling even for a fragment consisting entirely of neutrons. The transition formalism involves specific intense-field wave functions both for the nucleus and for the beta particle. Complete results are presented for total transition probability per unit time for intense-field-coupled nuclear beta decay. A much simplified formalism is given for the special case of very high field intensity at very low frequency. The results then bear a formal resemblance to ordinary beta decay theory, but they contain specific field effects in the beta particle spectral function, and in the nuclear interaction matrix elements. This is the first of a series of papers on this subject

  12. Electron field emission from sp 2-induced insulating to metallic ...

    Indian Academy of Sciences (India)

    The influence of concentration and size of 2 cluster on the transport properties and electron field emissions of amorphous carbon films have been investigated. The observed insulating to metallic behaviour from reduced activation energy derived from transport measurement and threshold field for electron emission of ...

  13. Magnetic field induced transitions in BiFeO3

    Science.gov (United States)

    Matsuda, M.; Dissanayake, S.; Hong, T.; Ratcliff, W., II; Zhao, Y.; Xu, Z.; Miyahara, S.; Furukawa, N.; Kawachi, S.; Miyake, A.; Tokunaga, M.

    Bulk BiFeO3 exhibits a spiral spin structure below 640 K and also a transition to a canted G-type structure in magnetic field. Very recently, a new magnetic phase was found just below the critical field to the canted G-type phase. Neutron diffraction measurements were performed to clarify the magnetic structure in the intermediate phase as well as the magnetic domain redistribution in magnetic field. There are three magnetic domains with different easy planes at ambient magnetic field. We found that with applying field perpendicular to one of the magnetic domains (M1), the other two domains merge to the M1 domain around 5 T. With further applying field, there occurs a first order magnetic transition to the intermediate phase. The incommensurate peaks observed perpendicular to the magnetic field at low fields become commensurate in the intermediate phase. We will discuss the magnetic structure in this phase. This research at ORNL's HFIR was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.

  14. Doping induced enhanced density of states in bismuth telluride

    Science.gov (United States)

    Narendra, Namita; Norouzzadeh, Payam; Vashaee, Daryoosh; Kim, Ki Wook

    2017-12-01

    Power factor enhancement through resonant doping is explored in Bi2Te3 based on a detailed first-principles study. Of the dopant atoms investigated, it is found that the formation of resonant states may be achieved with In, Po, and Na, leading potentially to a significant increase in the thermoelectric efficiency at room temperature. While doping with Po forms twin resonant state peaks in the valence and conduction bands, the incorporation of Na or In results in the resonant states close to the valence band edge. Further analysis reveals the origin of these resonant states. Transport calculations are also carried out to estimate the anticipated level of enhancement.

  15. Hund's Induced Fermi-Liquid Instabilities and Enhanced Quasiparticle Interactions

    Science.gov (United States)

    de'Medici, Luca

    2017-04-01

    Hund's coupling is shown to generally favor, in a doped half-filled Mott insulator, an increase in the compressibility culminating in a Fermi-liquid instability towards phase separation. The largest effect is found near the frontier between an ordinary and an orbitally decoupled ("Hund's") metal. The increased compressibility implies an enhancement of quasiparticle scattering, thus favoring other possible symmetry breakings. This physics is shown to happen in simulations of the 122 Fe-based superconductors, possibly implying the relevance of this mechanism in the enhancement of the critical temperature for superconductivity.

  16. Chiral spiral induced by a strong magnetic field

    Directory of Open Access Journals (Sweden)

    Abuki Hiroaki

    2016-01-01

    Full Text Available We study the modification of the chiral phase structure of QCD due to an external magnetic field. We first demonstrate how the effect of magnetic field can systematically be incorporated into a generalized Ginzburg-Landau framework. We then analyze the phase structure in the vicinity of the chiral critical point. In the chiral limit, the effect is found to be so drastic that it brings a “continent” of chiral spiral in the phase diagram, by which the chiral tricritical point is totally washed out. This is the case no matter how small the intensity of magnetic field is. On the other hand, the current quark mass protects the chiral critical point from a weak magnetic field. However, the critical point will eventually be covered by the chiral spiral phase as the magnetic field grows.

  17. Wave electromagnetic fields induced by instantaneous braking of charges

    International Nuclear Information System (INIS)

    Kon'kov, V.L.; Novikova, G.P.

    1981-01-01

    Exact expressions for wave electromagnetic fields during instantaneous braking of two differently charged discs uniformly moving in the opposite directions have been derived. Analysis of their properties has been made. It is shown that electromagnetic wave fields during instantaneous braking of charges have a tearing nature and the Umov-Poynting theorem in the integral form is realized only at a certain value of parameter α which determines charges rates at the moment of braking. The value of parameter α is in the ranges from 0.5 to √3/2. The wave field is formed already in the absence of motion of charged discs. It is a good example confirming the conclusion that in the case of nonstationary electromagnetic fields, performance of reaction force of the wave field can differ fram radiation energy [ru

  18. Laser-induced extreme magnetic field in nanorod targets

    Science.gov (United States)

    Lécz, Zsolt; Andreev, Alexander

    2018-03-01

    The application of nano-structured target surfaces in laser-solid interaction has attracted significant attention in the last few years. Their ability to absorb significantly more laser energy promises a possible route for advancing the currently established laser ion acceleration concepts. However, it is crucial to have a better understanding of field evolution and electron dynamics during laser-matter interactions before the employment of such exotic targets. This paper focuses on the magnetic field generation in nano-forest targets consisting of parallel nanorods grown on plane surfaces. A general scaling law for the self-generated quasi-static magnetic field amplitude is given and it is shown that amplitudes up to 1 MT field are achievable with current technology. Analytical results are supported by three-dimensional particle-in-cell simulations. Non-parallel arrangements of nanorods has also been considered which result in the generation of donut-shaped azimuthal magnetic fields in a larger volume.

  19. Λ( t ) cosmology induced by a slowly varying Elko field

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, S.H.; Pinho, A.S.S.; Silva, J.M. Hoff da [Universidade Estadual Paulista (Unesp), Faculdade de Engenharia, Guaratinguetá, Departamento de Física e Química Av. Dr. Ariberto Pereira da Cunha 333, 12516-410—Guaratinguetá, SP (Brazil); Jesus, J.F., E-mail: shpereira@feg.unesp.br, E-mail: alexandre.pinho510@gmail.com, E-mail: hoff@feg.unesp.br, E-mail: jfjesus@itapeva.unesp.br [Universidade Estadual Paulista (Unesp), Campus Experimental de Itapeva, R. Geraldo Alckmin, 519 Itapeva, SP (Brazil)

    2017-01-01

    In this work the exact Friedmann-Robertson-Walker equations for an Elko spinor field coupled to gravity in an Einstein-Cartan framework are presented. The torsion functions coupling the Elko field spin-connection to gravity can be exactly solved and the FRW equations for the system assume a relatively simple form. In the limit of a slowly varying Elko spinor field there is a relevant contribution to the field equations acting exactly as a time varying cosmological model Λ( t )=Λ{sub *}+3β H {sup 2}, where Λ{sub *} and β are constants. Observational data using distance luminosity from magnitudes of supernovae constraint the parameters Ω {sub m} and β, which leads to a lower limit to the Elko mass. Such model mimics, then, the effects of a dark energy fluid, here sourced by the Elko spinor field. The density perturbations in the linear regime were also studied in the pseudo-Newtonian formalism.

  20. Pulsed magnetic field from video display terminals enhances teratogenic effects of cytosine arabinoside in mice

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, H.; Wu, R.Y.; Shao, B.J.; Fu, Y.D.; Yao, G.D.; Lu, D.J. [Zhejiang Medical Univ. (China)

    1995-05-01

    Eighty-nine Swiss Webster mice were randomly divided into four groups: a control group, a pulsed magnetic field (PMF) group, a cytosine arabinoside (ara-C, a teratogen) group, and a combined PMF + ara-C group. Mice in the PMF and PMF + ara-C groups were irradiated with a PMF (a sawtooth waveform with 52 {mu}s rise time, 12{mu}s decay time, and 15.6 kHz frequency) at a peak magnetic flux density of 40 {mu}T for 4 hours daily on days 6-17 of gestation. The mice in the ara-C and the PMF + ara-C groups were injected intraperitoneally on day 9 of gestation with 10 mg/kg of ara-C. The incidence of resorption and dead fetuses was not affected by PMF but was increased by ara-C injection. The malformation incidence of cleft palate (CP) and/or cleft lip (CL) was significantly higher in all three of the treated groups than in the control group (P < 0.05). If, however, statistical analyses had been done on litters rather than on individual fetuses, they would show that the incidence of CP and/or CL in the PMF group is not significantly greater than that in the control group. A significantly higher incidence of CP and/or CL was found in the PMF + ara-C group (49%) than the ara-C alone group (26.1%). These data suggest that PMF might enhance the development of ara-C-induced CP and/or CL. The incidence of minor variations in skeletal development, including reduction of skeletal calcification and loss of skeleton, was not statistically significant in the PMF group. However, it was higher in the two ara-C-treated groups, and there was no significant difference between the ara-C alone group and the ara-C + PMF group. From these results it is concluded that the very weak embryotoxic effects of PMF exposure may be revealed and enhanced in combination with a teratogenic agent.

  1. Numerical simulation of cantilevered ramp injector flow fields for hypervelocity fuel/air mixing enhancement

    Science.gov (United States)

    Schumacher, Jurgen Christian

    Increasing demand for affordable access to space and high speed terrestrial transport has spawned research interest into various air-breathing hypersonic propulsion systems. Propulsion concepts such as the supersonic combustion ramjet (scramjet) and the shock-induced combustion ramjet (shcramjet) utilize oxygen freely available in the atmosphere and thereby substantially reduce the weight penalty of on-board oxidizer tankage used in rocket based systems. Of key importance to the ultimate success of an air-breathing concept is the ability to efficiently mix the fuel with atmospheric air. In the case of a hypersonic air-breather the challenge is accentuated due to the requirement of supersonic combustion. Flow velocities through the combustor on the order of thousands of meters per second provide the fuel and air with only a brief time to adequately combine. Contemporary mixing augmentation methods to address this issue have focused on fuel injection devices which promote axial vortices to enhance the mixing process. Much research effort has been expended on investigation of ramp injectors for this purpose. The present study introduces a new ramp injector design, based on the conventional ramp injector, dubbed the cantilevered ramp injector. A two-pronged numerical approach was employed to investigate the mixing performance and characteristics of the cantilevered injector consisting of, (1) comparison with conventional designs and (2) a parametric study of various cantilevered injector geometries. A laminar, three-dimensional, multispecies flowsolver was developed in generalized coordinates to solve the Navier-Stokes equations for the flow fields of injected H2 into high-enthalpy air. The scheme consists of an upwind TVD scheme for discretization of the convective fluxes coupled with a semi-implicit LU-SGS scheme for temporal discretization. Through analysis of the numerical solutions, it has been shown that the cantilevered ramp injector is a viable fuel injection

  2. High order harmonic generation in noble gases using plasmonic field enhancement

    International Nuclear Information System (INIS)

    Ciappina, Marcelo F.; Shaaran, Tahir; Lewenstein, Maciej

    2013-01-01

    Theoretical studies of high-order harmonic generation (HHG) in rare gases driven by plasmonic field enhancement are presented. This kind of fields appears when plasmonic nanostructures are illuminated by an intense few-cycle laser and have a particular spatial dependency, depending on the geometrical shape of the nanostructure. It is demonstrated that the strong nonhomogeneous character of the laser enhanced field plays an important role in the HHG process and significantly extends the harmonic cutoff. The models are based on numerical solution of the time dependent Schroedinger equation (TDSE) and supported by classical and semiclassical calculations. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Neurotensin enhances estradiol induced DNA synthesis in immature rat uterus

    Energy Technology Data Exchange (ETDEWEB)

    Mistry, A.; Vijayan, E.

    1985-05-27

    Systemic administration of Neurotensin, a tridecapeptide, in immature rats treated with estradiol benzoate significantly enhances uterine DNA synthesis as reflected by the incorporation of /sup 3/H-thymidine. The peptide may have a direct action on the uterus. Substance P, a related peptide, had no effect on uterine DNA synthesis. 18 references, 4 tables.

  4. Inducement and enhancement of multiple coherence resonances in ...

    Indian Academy of Sciences (India)

    The effect of cooperative coupling strength (CCS), i.e., random coupling strength and time-periodic coupling strength, on multiple coherence resonances in unidirectionally coupled neural system has been investigated. Results show that noise, frequency and amplitude play efficient roles for the enhancement of various ...

  5. Fluorescence lifetime imaging study of a single cell: stress-induced environmental change and electric field effects on fluorescence

    Science.gov (United States)

    Ohta, Nobuhiro; Nakabayashi, Takakazu; Nagao, Issei; Kinjo, Masataka; Aoki, Yumiko; Tanaka, Minoru

    2009-02-01

    A dramatic change occurs in the cellular microenvironment during cell stress, but it has been difficult to follow these changes in vivo. Here, fluorescence lifetime imaging (FLIM) microscopy has been used to examine stress-induced changes in the microenvironment in a single cell. It is observed that the fluorescence lifetime of HeLa cells expressing an enhanced green fluorescent protein (EGFP)-tudor fusion protein changes under stress. The change in the fluorescence lifetime appears to be due to an alteration in the local electric field in the protein matrix surrounding the chromophore of EGFP. In fact, the fluorescence lifetime of the GFP chromophore in a polyvinyl alcohol film is found to decrease in the presence of an electric field, based on the measurements of the field-induced change in the fluorescence decay profile. The results indicate that the rate of the non-radiative process of the chromophore of GFP is enhanced by an applied electric field. The FLIM method allows noninvasive determination of the status of the individual cells.

  6. Drug perfusion enhancement in tissue model by steady streaming induced by oscillating microbubbles.

    Science.gov (United States)

    Oh, Jin Sun; Kwon, Yong Seok; Lee, Kyung Ho; Jeong, Woowon; Chung, Sang Kug; Rhee, Kyehan

    2014-01-01

    Drug delivery into neurological tissue is challenging because of the low tissue permeability. Ultrasound incorporating microbubbles has been applied to enhance drug delivery into these tissues, but the effects of a streaming flow by microbubble oscillation on drug perfusion have not been elucidated. In order to clarify the physical effects of steady streaming on drug delivery, an experimental study on dye perfusion into a tissue model was performed using microbubbles excited by acoustic waves. The surface concentration and penetration length of the drug were increased by 12% and 13%, respectively, with streaming flow. The mass of dye perfused into a tissue phantom for 30s was increased by about 20% in the phantom with oscillating bubbles. A computational model that considers fluid structure interaction for streaming flow fields induced by oscillating bubbles was developed, and mass transfer of the drug into the porous tissue model was analyzed. The computed flow fields agreed with the theoretical solutions, and the dye concentration distribution in the tissue agreed well with the experimental data. The computational results showed that steady streaming with a streaming velocity of a few millimeters per second promotes mass transfer into a tissue. © 2013 Published by Elsevier Ltd.

  7. On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell.

    Science.gov (United States)

    Petterson, Maureen K; Lemaitre, Maxime G; Shen, Yu; Wadhwa, Pooja; Hou, Jie; Vasilyeva, Svetlana V; Kravchenko, Ivan I; Rinzler, Andrew G

    2015-09-30

    Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separated there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm(2) AM1.5G illumination, results in a short-circuit current density of 35 mA/cm(2) and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. A deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.

  8. Coupled field induced conversion between destructive and constructive quantum interference

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiangqian, E-mail: xqjiang@hit.edu.cn; Sun, Xiudong

    2016-12-15

    We study the control of quantum interference in a four-level atom driven by three coherent fields forming a closed loop. The spontaneous emission spectrum shows two sets of peaks which are dramatically influenced by the fields. Due to destructive quantum interference, a dark line can be observed in the emission spectrum, and the condition of the dark line is given. We found that the conversion between destructive and constructive quantum interference can be achieved through controlling the Rabi frequency of the external fields.

  9. Identification of promoters and enhancers induced by carbon nanotube exposure

    DEFF Research Database (Denmark)

    Bornholdt, Jette; Lilje, Berit; Saber, Anne Thoustrup

    Usage of carbon nanotubes (CNTs) is increasing in industry due to their mechanical and electrical properties. However, pulmonary exposure to CNTs induces, an asbestos-like toxicological response characterized by persistent inflammation, granuloma formation and fibrosis with low no-effect levels...

  10. Evaluate the Mechanism of Enhanced Metastasis Induced by Arthritis

    Science.gov (United States)

    2012-09-01

    Genes that mediate breast ca ncer metastasis to lung . Nature 2005, 436(7050):518-524. 6. Das Roy L, Pathangey L, Tinder T, Schettini J, Gruber H...7. Das Roy L, Ghosh S, Pathangey LB, Tinder TL, Gruber HE, Mukherjee P: Collagen induced arthritis increases s econdary metastasis in MMTV-PyV

  11. Dynamic random links enhance diversity-induced coherence in ...

    Indian Academy of Sciences (India)

    Abstract. We investigate the influence of diversity on the temporal regularity of spiking in a ring of coupled model neurons. We find diversity-induced coherence in the spike events, with an optimal amount of parametric heterogeneity at the nodal level yielding the greatest regularity in the spike train. Further, we investigate ...

  12. Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yunkang [Department of Mathematics and Physics, Nanjing Institute of technology, Nanjing, 211167 (China); Chen, Jing, E-mail: chenjingmoon@gmail.com [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Zichen, E-mail: zz241@ime.ac.cn [Integrated system for Laser applications Group, Institute of Microelectronics of Chinese Academy of Sciences, 100029, Beijing (China)

    2017-02-28

    Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

  13. Electric field measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond electric field induced second harmonic generation

    Science.gov (United States)

    Goldberg, Benjamin M.; Chng, Tat Loon; Dogariu, Arthur; Miles, Richard B.

    2018-02-01

    We present an optical electric field measurement method for use in high pressure plasma discharges. The method is based upon the field induced second harmonic generation technique and can be used for localized electric field measurements with sub-nanosecond resolution in any gaseous species. When an external electric field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the electric field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the electric field is strong enough to exceed the breakdown threshold, the measured field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.

  14. Mapping and correcting respiration-induced field changes in the brain using fluorine field probes

    DEFF Research Database (Denmark)

    Andersen, Mads; Madsen, Kristoffer H; Hanson, L.G.

    : The experiments were performed on a 7T MRI system (Philips Healthcare, Best, NL) using a 32-channel Nova Medical head coil. Fourteen fluorine T/R NMR field probes3 were firmly distributed around the transmit/receive head coil. A stand-alone spectrometer4 digitized the field probe signals, and calculated field...

  15. Rabi Resonances Induced by an Off-Resonant, Stochastic Field

    National Research Council Canada - National Science Library

    Camparo, J

    1999-01-01

    When an atom interacts with a phase-fluctuating field of fairly arbitrary spectral character, the Fourier spectrum of atomic population variations manifests a "bright line" at the atomic system's Rabi frequency...

  16. Temporally-patterned magnetic fields induce complete fragmentation in planaria.

    Directory of Open Access Journals (Sweden)

    Nirosha J Murugan

    Full Text Available A tandem sequence composed of weak temporally-patterned magnetic fields was discovered that produced 100% dissolution of planarian in their home environment. After five consecutive days of 6.5 hr exposure to a frequency-modulated magnetic field (0.1 to 2 µT, immediately followed by an additional 6.5 hr exposure on the fifth day, to another complex field (0.5 to 5 µT with exponentially increasing spectral power 100% of planarian dissolved within 24 hr. Reversal of the sequence of the fields or presentation of only one pattern for the same duration did not produce this effect. Direct video evidence showed expansion (by visual estimation ∼twice normal volume of the planarian following the first field pattern followed by size reduction (estimated ∼1/2 of normal volume and death upon activation of the second pattern. The contortions displayed by the planarian during the last field exposure suggest effects on contractile proteins and alterations in the cell membrane's permeability to water.

  17. Quantum fields on manifolds: PCT and gravitationally induced thermal states

    International Nuclear Information System (INIS)

    Sewell, G.L.

    1982-01-01

    We formulate an axiomatic scheme, designed to provide a framework for a general, rigorous theory of relativistic quantum fields on a class of manifolds, that includes Kruskal's extension of Schwarzchild space-time, as well as Minkowski space-time. The scheme is an adaptation of Wightman's to this class of manifolds. We infer from it that, given an arbitrary field (in general, interacting) on a manifold X, the restriction of the field to a certain open submanifold X/sup( + ), whose boundaries are event horizons, satisfies the Kubo--Martin--Schwinger (KMS) thermal equilibrium conditions. This amounts to a rigorous, model-independent proof of a generalized Hawking--Unruh effect. Further, in cases where the field enjoys a certain PCT symmetry, the conjugation governing the KMS condition is just the PCT operator. The key to these results is an analogue, that we prove, of the Bisognano--Wichmann theorem [J. Math. Phys. 17, (1976), Theorem 1]. We also construct an alternative scheme by replacing a regularity condition at an event horizon by the assumption that the field in X/sup( + ) is in a ground, rather then a thermal, state. We show that, in this case, the observables in X/sup( + ) are uncorrelated to those in its causal complement, X/sup( - ), and thus that the event horizons act as physical barriers. Finally, we argue that the choice between the two schemes must be dictated by the prevailing conditions governing the state of the field

  18. Investigation of silicide-induced-dopant-activation for steep tunnel junction in tunnel field effect transistor (TFET)

    Science.gov (United States)

    Kim, Sihyun; Kwon, Dae Woong; Park, Euyhwan; Lee, Junil; Lee, Roongbin; Lee, Jong-Ho; Park, Byung-Gook

    2018-02-01

    Numerous researches for making steep tunnel junction within tunnel field-effect transistor (TFET) have been conducted. One of the ways to make an abrupt junction is source/drain silicidation, which uses the phenomenon often called silicide-induced-dopant-segregation. It is revealed that the silicide process not only helps dopants to pile up adjacent to the metal-silicon alloy, also induces the dopant activation, thereby making it possible to avoid additional high temperature process. In this report, the availability of dopant activation induced by metal silicide process was thoroughly investigated by diode measurement and device simulation. Metal-silicon (MS) diodes having p+ and n+ silicon formed on the p- substrate exhibit the characteristics of ohmic and pn diodes respectively, for both the samples with and without high temperature annealing. The device simulation for TFETs with dopant-segregated source was also conducted, which verified enhanced DC performance.

  19. Possibility of critical field enhancement due to field penetration in high-Tc sponges and thin films

    Science.gov (United States)

    Collings, E. W.; Markoworth, A. J.; Marken, K. R., Jr.

    1989-03-01

    Magnetic susceptibility measurements of a sample of sintered high-Tc ceramic superconductor of nominal composition Y1Ba2Cu3O(7-y) were conducted as a function of temperature from liquid-He temperatures to Tc. The fitted form of the susceptibility temperature dependence yielded a sample-particle size that was only a few times larger than the field-penetration depth. The particle size was much less than the grain size and commensurate with the thickness of the optical twins. The results of the enhancement studies are also discussed in the light of Bean's (1964) early experiments on Pb sponges (in this case wavelength much greater than particle size) which exhibited spectacular enhancements of Hc in association with flux trapping at or between the Pb filaments. It is predicted that it should be possible, using presently available film-deposition techniques, to produce high-Tc films possessing severalfold enhancements of H(c1) beyond the bulk value, and that, as with the Pb sponges, the magnetization loops, even when taken within what passes for the Meissner state in such materials, will be hysteretic.

  20. Magnetic field induced assembling of nanoparticles in ferrofluidic ...

    Indian Academy of Sciences (India)

    Unknown

    especially in cancer therapy (Vasile and Aurora 1994). The optical and magnetic properties of these rheologi- cal fluids have been widely studied (Davies and .... centrifuged well to remove the sedimented particles and placed in an ultrasonic vibrator to enhance Brownian mo- tion, which provides stability to the ferrofluid.

  1. Nanostructures induced light harvesting enhancement in organic photovoltaics

    Science.gov (United States)

    Bi, Yan-Gang; Feng, Jing; Ji, Jin-Hai; Yi, Fang-Shun; Li, Yun-Fei; Liu, Yue-Feng; Zhang, Xu-Lin; Sun, Hong-Bo

    2017-12-01

    Lightweight and low-cost organic photovoltaics (OPVs) hold great promise as renewable energy sources. The most critical challenge in developing high-performance OPVs is the incomplete photon absorption due to the low diffusion length of the carrier in organic semiconductors. To date, various attempts have been carried out to improve light absorption in thin photoactive layer based on optical engineering strategies. Nanostructure-induced light harvesting in OPVs offers an attractive solution to realize high-performance OPVs, via the effects of antireflection, plasmonic scattering, surface plasmon polarization, localized surface plasmon resonance and optical cavity. In this review article, we summarize recent advances in nanostructure-induced light harvesting in OPVs and discuss various light-trapping strategies by incorporating nanostructures in OPVs and the fabrication processing of the micro-patterns with high resolution, large area, high yield and low cost.

  2. Chalcones Enhance TRAIL-Induced Apoptosis in Prostate Cancer Cells

    Directory of Open Access Journals (Sweden)

    Ewelina Szliszka

    2009-12-01

    Full Text Available Chalcones exhibit chemopreventive and antitumor effects. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL is a naturally occurring anticancer agent that induces apoptosis in cancer cells and is not toxic to normal cells. We examined the cytotoxic and apoptotic effect of five chalcones in combination with TRAIL on prostate cancer cells. The cytotoxicity was evaluated by the MTT and LDH assays. The apoptosis was determined using flow cytometry with annexin V-FITC. Our study showed that all five tested chalcones: chalcone, licochalcone-A, isobavachalcone, xanthohumol, butein markedly augmented TRAIL-mediated apoptosis and cytotoxicity in prostate cancer cells and confirmed the significant role of chalcones in chemoprevention of prostate cancer.

  3. Chalcones Enhance TRAIL-Induced Apoptosis in Prostate Cancer Cells

    Science.gov (United States)

    Szliszka, Ewelina; Czuba, Zenon P; Mazur, Bogdan; Sedek, Lukasz; Paradysz, Andrzej; Krol, Wojciech

    2009-01-01

    Chalcones exhibit chemopreventive and antitumor effects. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a naturally occurring anticancer agent that induces apoptosis in cancer cells and is not toxic to normal cells. We examined the cytotoxic and apoptotic effect of five chalcones in combination with TRAIL on prostate cancer cells. The cytotoxicity was evaluated by the MTT and LDH assays. The apoptosis was determined using flow cytometry with annexin V-FITC. Our study showed that all five tested chalcones: chalcone, licochalcone-A, isobavachalcone, xanthohumol, butein markedly augmented TRAIL-mediated apoptosis and cytotoxicity in prostate cancer cells and confirmed the significant role of chalcones in chemoprevention of prostate cancer. PMID:20161998

  4. Application of an induced field sensor for assessment of electromagnetic exposure from compact fluorescent lamps.

    Science.gov (United States)

    Nadakuduti, Jagadish; Douglas, Mark; Capstick, Myles; Kühn, Sven; Kuster, Niels

    2012-02-01

    The development of scientifically sound instrumentation, methods, and procedures for the electromagnetic exposure assessment of compact fluorescent lamps (CFLs) is investigated. The incident and induced fields from 11 CFLs have been measured in the 10 kHz-1 MHz range, and they are compared with the levels for incandescent and light emitting diode (LED) bulbs. Commercially available equipment was used to measure the incident fields, while a novel sensor was built to assess the induced fields in humans. Incident electric field levels significantly exceed the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels at close distances for some sources, while the induced fields are within the ICNIRP basic restrictions. This demonstrates the importance of assessing the induced fields rather than the incident fields for these sources. Maximum current densities for CFLs are comparable to the limits (in the range of 9% to 56%), demonstrating the need for measurements to establish compliance. For the frequency range investigated, the induced fields were found to be considerably higher for CFLs than for incandescent light bulbs, while the exposure from the two LED bulbs was low. The proposed instrumentation and methods offer several advantages over an existing measurement standard, and the measurement uncertainty is significantly better than the assessment of electric and magnetic fields at close distances. Copyright © 2011 Wiley Periodicals, Inc.

  5. Enhancement of endocannabinoid signaling protects against cocaine-induced neurotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Vilela, Luciano R. [Graduate Program in Neuroscience, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Gobira, Pedro H.; Viana, Thercia G. [Department of Pharmacology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Medeiros, Daniel C.; Ferreira-Vieira, Talita H. [Department of Physiology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Doria, Juliana G. [Graduate Program in Neuroscience, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Rodrigues, Flávia [Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Aguiar, Daniele C. [Department of Pharmacology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Pereira, Grace S.; Massessini, André R. [Department of Physiology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Ribeiro, Fabíola M. [Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Oliveira, Antonio Carlos P. de [Department of Pharmacology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Moraes, Marcio F.D., E-mail: mfdm@icb.ufmg.br [Department of Physiology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Moreira, Fabricio A., E-mail: fabriciomoreira@icb.ufmg.br [Department of Pharmacology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil)

    2015-08-01

    Cocaine is an addictive substance with a potential to cause deleterious effects in the brain. The strategies for treating its neurotoxicity, however, are limited. Evidence suggests that the endocannabinoid system exerts neuroprotective functions against various stimuli. Thus, we hypothesized that inhibition of fatty acid amide hydrolase (FAAH), the main enzyme responsible for terminating the actions of the endocannabinoid anandamide, reduces seizures and cell death in the hippocampus in a model of cocaine intoxication. Male Swiss mice received injections of endocannabinoid-related compounds followed by the lowest dose of cocaine that induces seizures, electroencephalographic activity and cell death in the hippocampus. The molecular mechanisms were studied in primary cell culture of this structure. The FAAH inhibitor, URB597, reduced cocaine-induced seizures and epileptiform electroencephalographic activity. The cannabinoid CB{sub 1} receptor selective agonist, ACEA, mimicked these effects, whereas the antagonist, AM251, prevented them. URB597 also inhibited cocaine-induced activation and death of hippocampal neurons, both in animals and in primary cell culture. Finally, we investigated if the PI3K/Akt/ERK intracellular pathway, a cell surviving mechanism coupled to CB{sub 1} receptor, mediated these neuroprotective effects. Accordingly, URB597 injection increased ERK and Akt phosphorylation in the hippocampus. Moreover, the neuroprotective effect of this compound was reversed by the PI3K inhibitor, LY294002. In conclusion, the pharmacological facilitation of the anandamide/CB1/PI3K signaling protects the brain against cocaine intoxication in experimental models. This strategy may be further explored in the development of treatments for drug-induced neurotoxicity. - Highlights: • Cocaine toxicity is characterized by seizures and hippocampal cell death. • The endocannabinoid anandamide acts as a brain protective mechanism. • Inhibition of anandamide hydrolysis

  6. Enhancement of endocannabinoid signaling protects against cocaine-induced neurotoxicity

    International Nuclear Information System (INIS)

    Vilela, Luciano R.; Gobira, Pedro H.; Viana, Thercia G.; Medeiros, Daniel C.; Ferreira-Vieira, Talita H.; Doria, Juliana G.; Rodrigues, Flávia; Aguiar, Daniele C.; Pereira, Grace S.; Massessini, André R.; Ribeiro, Fabíola M.; Oliveira, Antonio Carlos P. de; Moraes, Marcio F.D.; Moreira, Fabricio A.

    2015-01-01

    Cocaine is an addictive substance with a potential to cause deleterious effects in the brain. The strategies for treating its neurotoxicity, however, are limited. Evidence suggests that the endocannabinoid system exerts neuroprotective functions against various stimuli. Thus, we hypothesized that inhibition of fatty acid amide hydrolase (FAAH), the main enzyme responsible for terminating the actions of the endocannabinoid anandamide, reduces seizures and cell death in the hippocampus in a model of cocaine intoxication. Male Swiss mice received injections of endocannabinoid-related compounds followed by the lowest dose of cocaine that induces seizures, electroencephalographic activity and cell death in the hippocampus. The molecular mechanisms were studied in primary cell culture of this structure. The FAAH inhibitor, URB597, reduced cocaine-induced seizures and epileptiform electroencephalographic activity. The cannabinoid CB 1 receptor selective agonist, ACEA, mimicked these effects, whereas the antagonist, AM251, prevented them. URB597 also inhibited cocaine-induced activation and death of hippocampal neurons, both in animals and in primary cell culture. Finally, we investigated if the PI3K/Akt/ERK intracellular pathway, a cell surviving mechanism coupled to CB 1 receptor, mediated these neuroprotective effects. Accordingly, URB597 injection increased ERK and Akt phosphorylation in the hippocampus. Moreover, the neuroprotective effect of this compound was reversed by the PI3K inhibitor, LY294002. In conclusion, the pharmacological facilitation of the anandamide/CB1/PI3K signaling protects the brain against cocaine intoxication in experimental models. This strategy may be further explored in the development of treatments for drug-induced neurotoxicity. - Highlights: • Cocaine toxicity is characterized by seizures and hippocampal cell death. • The endocannabinoid anandamide acts as a brain protective mechanism. • Inhibition of anandamide hydrolysis attenuates

  7. Electromagnetic field enhancement and spectrum shaping through plasmonically integrated optical vortices.

    Science.gov (United States)

    Ahn, Wonmi; Boriskina, Svetlana V; Hong, Yan; Reinhard, Björn M

    2012-01-11

    We introduce a new design approach for surface-enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices "pinned" to rationally designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational electromagnetism, and elastic and inelastic scattering spectroscopy. Pronounced dips in the far-field scattering spectra of VNTs provide experimental evidence for an efficient light trapping and circulation within the nanostructures. Furthermore, we demonstrate that VNT integration into periodic arrays of Au nanoparticles facilitates the generation of high E-field enhancements in the VNTs at multiple defined wavelengths. We show that spectrum shaping in nested VNT structures is achieved through an electromagnetic feed-mechanism driven by the coherent multiple scattering in the plasmonic arrays and that this process can be rationally controlled by tuning the array period. The ability to generate high E-field enhancements at predefined locations and frequencies makes nested VNTs interesting substrates for challenging SERS applications. © 2011 American Chemical Society

  8. Enhanced field emission properties of carbon nanotube bundles confined in SiO2 pits

    Science.gov (United States)

    Lim, Yu Dian; Grapov, Dmitry; Hu, Liangxing; Kong, Qinyu; Tay, Beng Kang; Labunov, Vladimir; Miao, Jianmin; Coquet, Philippe; Aditya, Sheel

    2018-02-01

    It has been widely reported that carbon nanotubes (CNTs) exhibit superior field emission (FE) properties due to their high aspect ratios and unique structural properties. Among the various types of CNTs, random growth CNTs exhibit promising FE properties due to their reduced inter-tube screening effect. However, growing random growth CNTs on individual catalyst islands often results in spread out CNT bundles, which reduces overall field enhancement. In this study, significant improvement in FE properties in CNT bundles is demonstrated by confining them in microfabricated SiO2 pits. Growing CNT bundles in narrow (0.5 μm diameter and 2 μm height) SiO2 pits achieves FE current density of 1–1.4 A cm‑2, which is much higher than for freestanding CNT bundles (76.9 mA cm‑2). From the Fowler Nordheim plots, confined CNT bundles show a higher field enhancement factor. This improvement can be attributed to the reduced bundle diameter by SiO2 pit confinement, which yields bundles with higher aspect ratios. Combining the obtained outcomes, it can be conclusively summarized that confining CNTs in SiO2 pits yields higher FE current density due to the higher field enhancement of confined CNTs.

  9. Historical applications of induced sterilisation in field populations of mosquitoes

    NARCIS (Netherlands)

    Dame, David A.; Curtis, Christopher F.; Benedict, Mark Q.; Robinson, Alan S.; Knols, Bart G. J.

    2009-01-01

    Research on sterile mosquito technology from 1955 to the 1980s provided a substantial body of knowledge on propagation and release of sterile mosquitoes. Radiation sterilisation and chemosterilisation have been used effectively to induce dominant lethality and thereby sterilise important mosquito

  10. Induced moment due to perpendicular field cycling in trained ...

    Indian Academy of Sciences (India)

    This induced magnetism into the AF layer is unique in its nature as it results from direct manipulation of the uncompensated moments at the AF–FM interface. Such manipulation obviously fails to restore the untrained state [10]. One may note that all the structural as well as magnetic properties are initially estimated.

  11. Electrical field stimulation-induced excitatory responses of ...

    African Journals Online (AJOL)

    Background: Nitric oxide-mediated endothelium-dependent relaxation is attenuated in pulmonary artery segments from monocrotaline (MCT)-induced pulmonary hypertensive rats. However, the influence of the endothelium on adrenergic neurotransmission in the rat pulmonary artery has not been investigated. The aim of ...

  12. Cold induced peripheral vasodilation at high altitudes- a field study

    NARCIS (Netherlands)

    Daanen, H.A.M.; Ruiten, H.J.A. van

    2000-01-01

    A significant reduction in cold-induced vasodilation (CIVD) is observed at high altitudes. No agreement is found in the literature about acclimatization effects on CIVD. Two studies were performed to investigate the effect of altitude acclimatization on CIVD. In the first study 13 male subjects

  13. Analytic methods for field induced tunneling in quantum wells with ...

    Indian Academy of Sciences (India)

    Electric field induced tunneling is studied in three different types of quantum wells by solving time-independent effective mass equation in analytic methods based on three different Airy function approaches. Comparison of different Airy function methods indicates that they are identical and connected to each other by the ...

  14. Chill-inducing music enhances altruism in humans

    Directory of Open Access Journals (Sweden)

    Hajime eFukui

    2014-10-01

    Full Text Available Music is a universal feature of human cultures, and it has both fascinated and troubled many researchers. In this paper we show through the Dictator Game that an individual’s listening to preferred chill-inducing music may promote altruistic behavior that extends beyond the bounds of kin selection or reciprocal altruism. Participants were 22 undergraduate and postgraduate students who were divided into two groups, the In-group (IG and the Out-group (OG, and they acted as dictators. The dictators listened to their own preferred chill-inducing music, to music they disliked, or to silence, and then played the Dictator Game. In this hypothetical experiment, the dictators were given real money (which they did not keep and were asked to distribute it to the recipients, who were presented as stylized images of men and women displayed on a computer screen. The dictators played the Dictator Game both before and after listening to the music. Both male and female dictators gave more money after listening to their preferred music and less after listening to the music they disliked, whereas silence had no effect on the allocated amounts. The group to which the recipient belonged did not influence these trends. The results suggest that listening to preferred chill-inducing music promotes altruistic behavior.

  15. Optimization design of optical waveguide control by nanoslit-enhanced THz field

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Malureanu, Radu; Zalkovskij, Maksim

    2013-01-01

    We discuss design issues of devices which were proposed recently [Opt. Lett. 37 (2012) 3903] for terahertz (THz) control of the propagation of an optical waveguide mode. The mode propagates through a nonlinear dielectric material placed in a metallic nanoslit illuminated by THz radiation. The THz...... field in the slit is strongly localized and thus significantly enhanced, facilitating nonlinear interactions with the dielectric waveguide material. This enhancement can lead to notable changes in the refractive index of the waveguide. The closer the waveguide is to the slit walls, the higher...

  16. Enhancement of Optical Nonlinearities in Composite Media and Structures via Local Fields and Electromagnetic Coupling Effects

    Science.gov (United States)

    Smith, David D.

    2002-01-01

    This talk will review the linear and nonlinear optical properties of metal nanoparticles and dielectric microparticles, with an emphasis on local field effects, and whispering gallery modes (WGMs), as well as the conjunction of these two effects for enhanced Raman. In particular, enhanced optical properties that result from electromagnetic coupling effects will be discussed in the context of Mie scattering from concentric spheres and bispheres. Predictions of mode splitting and photonic bandgaps in micro-spheres will be presented and will be shown to be analogous to effects that occur in coupled resonator optical waveguides (CROW). Slow and fast light in SCISSOR / CROW configurations will also be discussed.

  17. Magnetic-field-induced phase transitions in Wigner molecules

    CERN Document Server

    Szafran, B; Adamowski, J

    2003-01-01

    A theoretical analysis of formation and symmetry transformations is presented for Wigner molecules with N = 2,..., 20 electrons confined in quantum dots at high magnetic fields. Using the unrestricted Hartree-Fock method with the multicentre Gaussian basis, we have found that Wigner molecules with N >= 6 abruptly change their shape and symmetry with an associated jump in the first derivative of the ground-state energy, i.e. they undergo phase transitions. In particular, the phases of the Wigner molecules obtained just after emerging from the maximum-density droplet (MDD) phase possess a different symmetry from that formed at a high magnetic field. We show that the properties of the electron-electron interaction energy demonstrate very well both the breakdown of the MDD and the quasi-classical character of the Wigner molecule in the high magnetic field. Possible mechanisms of the MDD decay are discussed.

  18. Field induced order in magnetic systems: Marginal case

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, D., E-mail: daniel@cbpf.b [Centro Brasileiro de Pesquisas Fisicas - Rua Dr. Xavier Sigaud, 150-Urca, 22290-180 RJ (Brazil); Continentino, M.A. [Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, Niteroi, RJ 24.210-340 (Brazil)

    2009-10-15

    The bond operator representation and the one-loop renormalization group treatment are used to study the spin-1 Heisenberg antiferromagnetic with single-ion anisotropy and transversal magnetic fields in three-dimensional cubic lattices. We start from a disordered spin-liquid phase to an ordered phase, at a critical field H{sub c1} above which the system enters an XY-antiferromagnetic phase. This transition is interpreted as belonging to a universality class with a dynamical critical exponent z=1. In this marginal case logarithmic corrections are found to the physical quantities. These theoretical predictions are compared with the scaling of the magnetization as a function of field and temperature for the organic compound NiCl{sub 2}-4SC(NH{sub 2}){sub 2}.

  19. Field-induced magnetic instability within a superconducting condensate

    DEFF Research Database (Denmark)

    Mazzone, Daniel Gabriel; Raymond, Stephane; Gavilano, Jorge Luis

    2017-01-01

    The application of magnetic fields, chemical substitution, or hydrostatic pressure to strongly correlated electron materials can stabilize electronic phases with different organizational principles. We present evidence for a fieldinduced quantum phase transition, in superconducting Nd0.05Ce0.95Co...... that the magnetic instability is not magnetically driven, and we propose that it is driven by a modification of superconducting condensate at H*.......In5, that separates two antiferromagnetic phases with identical magnetic symmetry. At zero field, we find a spin-density wave that is suppressed at the critical field mu H-0* = 8 T. For H > H*, a spin-density phase emerges and shares many properties with the Q phase in CeCoIn5. These results suggest...

  20. On the origin of pre-reversal enhancement of the zonal equatorial electric field

    Directory of Open Access Journals (Sweden)

    M. C. Kelley

    2009-05-01

    Full Text Available In November 2004, a large and variable interplanetary electric field (IEF was felt in the reference frame of the Earth. This electric field penetrated to the magnetic equator and, when the Jicamarca Radio Observatory (JRO was in the dusk sector, resulted in a reversal of the normal zonal component of the field. In turn, this caused a counter-electrojet (CEJ, a westward current rather than the usual eastward current. At the time of the normal pre-reversal enhancement (PRE of the eastward field, the Jicamarca incoherent scatter radar (ISR observed that the westward component became even more westward. Two of the three current explanations for the PRE depend on the neutral wind patterns. However, this unique event was such that the neutral wind-driven dynamos could not have changed. The implication is that the Haerendel-Eccles mechanism, which involves partial closure of the equatorial electrojet (EEJ after sunset, must be the dominant mechanism for the PRE.

  1. Resonance enhancement of two photon absorption by magnetically trapped atoms in strong rf-fields

    Science.gov (United States)

    Chakraborty, A.; Mishra, S. R.

    2018-01-01

    Applying a many mode Floquet formalism for magnetically trapped atoms interacting with a polychromatic rf-field, we predict a large two photon transition probability in the atomic system of cold 87Rb atoms. The physical origin of this enormous increase in the two photon transition probability is due to the formation of avoided crossings between eigen-energy levels originating from different Floquet sub-manifolds and redistribution of population in the resonant intermediate levels to give rise to the resonance enhancement effect. Other exquisite features of the studied atom-field composite system include the splitting of the generated avoided crossings at the strong field strength limit and a periodic variation of the single and two photon transition probabilities with the mode separation frequency of the polychromatic rf-field. This work can find applications to characterize properties of cold atom clouds in the magnetic traps using rf-spectroscopy techniques.

  2. Modeling of nonlinear microscopy of localized field enhancements in random metal nanostructures

    DEFF Research Database (Denmark)

    Beermann, Jonas; Bozhevolnyi, Sergey I.; Coello, Victor

    2006-01-01

    Nonlinear microscopy of localized field enhancements in random metal nanostructures with a tightly focused laser beam scanning over a sample surface is modeled by making use of analytic representations of the Green dyadic in the near- and far-field regions, with the latter being approximated...... by the part describing the scattering via excitation of surface plasmon polaritons. The developed approach is applied to scanning second-harmonic (SH) microscopy of small gold spheres placed randomly on a gold surface. We calculate self-consistent fundamental harmonic (FH) and SH field distributions...... at the illuminated sample surface and, thereby, FH and SH images for different polarization configurations of the illuminating and detected fields. The simulated images bear close resemblance to the images obtained experimentally, exhibiting similar sensitivity to the wavelength and polarization, as well...

  3. Increasing the efficiency of organic solar cells by photonic and electrostatic-field enhancements

    Energy Technology Data Exchange (ETDEWEB)

    Nalwa, Kanwar [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    recombination of charge carriers. Thus it becomes imperative to understand the effect of processing conditions such as spin coating speed and drying rate on defect density and hence induced carrier recombination mechanism. In this study, It is shown that slow growth (longer drying time) of the active-layer leads to reduction of sub-bandgap traps by an order of magnitude as compared to fast grown active-layer. By coupling the experimental results with simulations, it is demonstrated that at one sun condition, slow grown device has bimolecular recombination as the major loss mechanism while in the fast grown device with high trap density, the trap assisted recombination dominates. It has been estimated that non-radiative recombination accounts nearly 50% of efficiency loss in modern OPVs. Generally, an external bias (electric field) is required to collect all the photogenerated charges and thus prevent their recombination. The motivation is to induce additional electric field in otherwise low mobility conjugated polymer based active layer by incorporating ferroelectric dipoles. This is expected to facilitate singlet exciton dissociation in polymer matrix and impede charge transfer exciton (CTE) recombination at polymer:fullerene interface. For the first time, it is shown that the addition of ferroelectric dipoles to modern bulk heterojunction (BHJ) can significantly improve exciton dissociation, resulting in a ~50% enhancement of overall solar cell efficiency. The devices also exhibit the unique ferroelectric-photovoltaic effect with polarization-controlled power conversion efficiency.

  4. Helium-3 induced enhancement of tritium production for fusion reactors

    International Nuclear Information System (INIS)

    Thomas, G.F.

    1983-11-01

    This report provides the results of an inquiry into the feasibility of enhancing tritium production levels through the activation of helium-3 following its external addition to the moderator system of a CANDU reactor. The physical basis for the scheme lies in the fact that the cross section for the activation of helium-3 to tritium is several orders of magnitude larger than the cross section for deuterium activation. The imminent introduction of a centralized facility for the removal, immobilization, and storage of tritium ensures a supply of helium-3, the product of tritium decay

  5. Hydrogen sulfide enhances nitric oxide-induced tolerance of hypoxia in maize (Zea mays L.).

    Science.gov (United States)

    Peng, Renyi; Bian, Zhiyuan; Zhou, Lina; Cheng, Wei; Hai, Na; Yang, Changquan; Yang, Tao; Wang, Xinyu; Wang, Chongying

    2016-11-01

    Our data present H 2 S in a new role, serving as a multi-faceted transducer to different response mechanisms during NO-induced acquisition of tolerance to flooding-induced hypoxia in maize seedling roots. Nitric oxide (NO), serving as a secondary messenger, modulates physiological processes in plants. Recently, hydrogen sulfide (H 2 S) has been demonstrated to have similar signaling functions. This study focused on the effects of treatment with H 2 S on NO-induced hypoxia tolerance in maize seedlings. The results showed that treatment with the NO donor sodium nitroprusside (SNP) enhanced survival rate of submerged maize roots through induced accumulation of endogenous H 2 S. The induced H 2 S then enhanced endogenous Ca 2+ levels as well as the Ca 2+ -dependent activity of alcohol dehydrogenase (ADH), improving the capacity for antioxidant defense and, ultimately, the hypoxia tolerance in maize seedlings. In addition, NO induced the activities of key enzymes in H 2 S biosynthesis, such as L-cysteine desulfhydrases (L-CDs), O-acetyl-L-serine (thiol)lyase (OAS-TL), and β-Cyanoalanine Synthase (CAS). SNP-induced hypoxia tolerance was enhanced by the application of NaHS, but was eliminated by the H 2 S-synthesis inhibitor hydroxylamine (HA) and the H 2 S-scavenger hypotaurine (HT). H 2 S concurrently enhanced the transcriptional levels of relative hypoxia-induced genes. Together, our findings indicated that H 2 S serves as a multi-faceted transducer that enhances the nitric oxide-induced hypoxia tolerance in maize (Zea mays L.).

  6. Calculation of induced modes of magnetic field in the geodynamo problem

    International Nuclear Information System (INIS)

    Yokoyama, Yukiko; Yukutake, Takesi

    1989-01-01

    In the dynamo problem, the calculation of induced modes is of vital importance, because the interaction of fluid motions with the magnetic field induces specific types of fields which are, in many cases, different either from the type of velocity field or from the original magnetic field. This special induction relationship, known as 'selection rules', has so far been derived by calculating Adams-Gaunt integrals and Elsasser integrals. In this paper, we calculate the induced modes in a more direct way, expressing the magnetic fields and the velocity in a spherical harmonic series. By linearizing the product terms of spherical harmonic functions, which appear in interaction terms between the velocity and the magnetic field, into a simple spherical harmonic series, we have derived the induced magnetic modes in a simple general form. When the magnetic field and the velocity are expressed by toroidal and poloidal modes, four kinds of interaction are conceivable between the velocity and the magnetic field. By each interaction, two modes, the poloidal and toroidal, are induced, except in the interaction of the toroidal velocity with the toroidal magnetic field, which induces only the toroidal mode. In spite of the diversity of interaction processes, the induced modes have been found to be expressed simply by two types. For a velocity of degree l and order k interacting with a magnetic field of degree n and order m, one type is the mode with degree and order of n+l-2t, |m±k| for an integer t, and the other with n+l-2t-1, |m±k|. (author)

  7. Current Induced Seismicity in the Paskov Mine Field

    Czech Academy of Sciences Publication Activity Database

    Holub, Karel; Rušajová, Jana; Holečko, J.

    2013-01-01

    Roč. 10, č. 2 (2013), s. 181-187 ISSN 1214-9705 R&D Projects: GA MŠk LM2010008 Institutional support: RVO:68145535 Keywords : Ostrava-Karviná coal mines * seismic network * induced seismicity * location plot Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.667, year: 2013 http://www.irsm.cas.cz/materialy/acta_content/2013_02/acta_170_07_%20Holub_181-187.pdf

  8. Induced moment due to perpendicular field cycling in trained ...

    Indian Academy of Sciences (India)

    spin flip (NSF): (R++ and R−−) and spin flip (SF) channels (R+− and R−+). Here + and − signs are used to distinguish the intensity contributions R representing a polarization component paral- lel or antiparallel to the guiding field, respectively.

  9. Induced moment due to perpendicular field cycling in trained ...

    Indian Academy of Sciences (India)

    Depth-sensitive polarized neutron scattering in specular and off-specular mode has recently revealed that perpendicular field cycling brings about a modification in the interfacial magnetization of a trained exchange coupled interface. We show here by various model fits to our neutron reflectivity data that a restoration of the ...

  10. Research into induced seismicity in the Groningen field : Further studies

    NARCIS (Netherlands)

    Jansen, J.D.; Herber, Rien

    2017-01-01

    Further research into seismicity caused by natural gas production from the Groningen field is necessary to improve the assessment of seismic risk and develop means to control and reduce it. Research into subsurface aspects is primarily of relevance to assess the seismic hazard component in the

  11. Analytic methods for field induced tunneling in quantum wells with ...

    Indian Academy of Sciences (India)

    Quantum wells (QW) formed in the semiconductor heterostructures have been given con- siderable theoretical attention because of their optical device applications [1]. For under- standing the operating principles of devices, it is necessary to study the optical absorption spectra in the QW under an applied dc electric field ...

  12. Cubic to hexagonal phase transition induced by electric field

    Czech Academy of Sciences Publication Activity Database

    Giacomelli, F. C.; Silveira, N.; Nallet, F.; Černoch, Peter; Steinhart, Miloš; Štěpánek, Petr

    2010-01-01

    Roč. 43, č. 9 (2010), s. 4261-4267 ISSN 0024-9297 R&D Projects: GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505 Keywords : order to order transition (OOT) * electric field * block copolymers Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.838, year: 2010

  13. Electron field emission from sp -induced insulating to metallic ...

    Indian Academy of Sciences (India)

    Administrator

    possible applications as semiconductor materials (Silva et al 1998) and as potential field emission cathode ... Though post treatment and annealing results in higher sp. 2 content cluster sizes, graphitization of the ... The samples were prepared by a simple pyrolysis method at different temperatures (700, 800 and 900°C) ...

  14. Electric field deformation in diamond sensors induced by radiation defects

    Energy Technology Data Exchange (ETDEWEB)

    Kassel, Florian; Boer, Wim de; Boegelspacher, Felix; Dierlamm, Alexander; Mueller, Thomas; Steck, Pia [Institut fuer Experimentelle Kernphysik (IEKP), Karlsruher Institut fuer Technologie (KIT) (Germany); Dabrowski, Anne; Guthoff, Moritz [CERN (Switzerland)

    2016-07-01

    The BCML system is a beam monitoring device in the CMS experiment at the LHC. As detectors 32 poly-crystalline CVD diamond sensors are positioned in a ring around the beam pipe at a distance of ±1.8 m and ±14.4 m from the interaction point. The radiation hardness of the diamond sensors in terms of measured signal during operation was significantly lower than expected from laboratory measurements. At high particle rates, such as those occurring during the operation of the LHC, a significant fraction of the defects act as traps for charge carriers. This space charge modifies the electrical field in the sensor bulk leading to a reduction of the charge collection efficiency (CCE). A diamond irradiation campaign was started to investigate the rate dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the Transient Current Technique, the CCE was measured. The experimental results were used to create an effective trap model that takes the radiation damage into account. Using this trap model the rate dependent electrical field deformation and the CCE were simulated with the software ''SILVACO TCAD''. This talk compares the experimental measurement results with the simulations.

  15. Cardiovascular Responses Induced by Obstructive Apnea Are Enhanced in Hypertensive Rats Due to Enhanced Chemoreceptor Responsivity

    Science.gov (United States)

    Angheben, Juliana M. M.; Schoorlemmer, Guus H. M.; Rossi, Marcio V.; Silva, Thiago A.; Cravo, Sergio L.

    2014-01-01

    Spontaneously hypertensive rats (SHR), like patients with sleep apnea, have hypertension, increased sympathetic activity, and increased chemoreceptor drive. We investigated the role of carotid chemoreceptors in cardiovascular responses induced by obstructive apnea in awake SHR. A tracheal balloon and vascular cannulas were implanted, and a week later, apneas of 15 s each were induced. The effects of apnea were more pronounced in SHR than in control rats (Wistar Kyoto; WKY). Blood pressure increased by 57±3 mmHg during apnea in SHR and by 28±3 mmHg in WKY (papneas were induced two days later. The inactivation of chemoreceptors reduced the responses to apnea and abolished the difference between SHR and controls. The apnea-induced hypertension was 11±4 mmHg in SHR and 8±4 mmHg in WKY. The respiratory effort was 15±2 mmHg in SHR and 15±2 mmHg in WKY. The heart rate fell 63±18 bpm in SHR and 52±14 bpm in WKY. Similarly, when the chemoreceptors were unloaded by the administration of 100% oxygen, the responses to apnea were reduced. In conclusion, arterial chemoreceptors contribute to the responses induced by apnea in both strains, but they are more important in SHR and account for the exaggerated responses of this strain to apnea. PMID:24466272

  16. Phonon-induced enhancement of the energy gap and critical current of superconducting aluminum films

    International Nuclear Information System (INIS)

    Seligson, D.; Clarke, J.

    1983-01-01

    Enhancements of the energy gap Δ and the critical current I/sub c/ have been induced in thin superconducting aluminum films near the transition temperature T/sub c/ by pulses of phonons at approximately 9 GHz. In terms of the change in temperature Vertical BardeltaT/T/sub c/Vertical Bar necessary to produce the same enhancement in equilibrium, the gap enhancement increased smoothly with phonon power at fixed temperature and decreasing temperature at fixed phonon power; however, very close to T/sub c/ the enhancement rolled off. At relatively low phonon powers, the data were in good agreement with the theory of Eckern, Schmid, Schmutz, and Schoen, but at higher power levels the data fell markedly below the predictions of the theory. The critical-current enhancements in terms of Vertical BardeltaT/T/sub c/Vertical Bar were always larger than the gap enhancements at the same temperature and phonon power. At fixed phonon power the critical-current enhancements were nearly independent of temperature, except very close to T/sub c/ where the enhancement became small. The inclusion of the nonequilibrium quasiparticle distribution and the kinetic energy of the supercurrent in the theory relating the critical-current enhancement to the gap enhancement did not resolve the discrepancies between the two enhancements. It appears likely that there is an additional mechanism for critical-current enhancement that has not yet been identified

  17. Enhanced tunability of plasmon induced transparency in graphene strips

    International Nuclear Information System (INIS)

    Shi, Xi; Su, Xiaopeng; Yang, Yaping

    2015-01-01

    The approach of slow-light efficiency manipulation is theoretically investigated in graphene analogue of electromagnetically induced transparency (EIT) system, which cannot be realized in conventional quantum regime. In this system, two graphene strips with different Fermi energies placed side by side as radiative elements have been discussed, and the coupling strength between radiative elements and dark elements is tuned by these radiative elements. Our proposed scheme exploits the tuning of coupling strength between the radiative elements and dark elements in contrast with the existing approaches that rely on tuning the damping rates of radiative or dark elements. The transparent window and group delays can be tuned by different coupling strength without changing the geometry of structure. This manipulation can be explained using a temporal coupled-mode theory. Furthermore, the hybridized states in this EIT-like system can be manipulated by tuning the Fermi energy of radiative elements. This kind of controllable electromagnetically induced transparency has many significant potential applications in optoelectronic, photodetectors, tunable sensors, and storage of optical data regimes

  18. ON current enhancement of nanowire Schottky barrier tunnel field effect transistors

    Science.gov (United States)

    Takei, Kohei; Hashimoto, Shuichiro; Sun, Jing; Zhang, Xu; Asada, Shuhei; Xu, Taiyu; Matsukawa, Takashi; Masahara, Meishoku; Watanabe, Takanobu

    2016-04-01

    Silicon nanowire Schottky barrier tunnel field effect transistors (NW-SBTFETs) are promising structures for high performance devices. In this study, we fabricated NW-SBTFETs to investigate the effect of nanowire structure on the device characteristics. The NW-SBTFETs were operated with a backgate bias, and the experimental results demonstrate that the ON current density is enhanced by narrowing the width of the nanowire. We confirmed using the Fowler-Nordheim plot that the drain current in the ON state mainly comprises the quantum tunneling component through the Schottky barrier. Comparison with a technology computer aided design (TCAD) simulation revealed that the enhancement is attributed to the electric field concentration at the corners of cross-section of the NW. The study findings suggest an effective approach to securing the ON current by Schottky barrier width modulation.

  19. Using scanning near-field microscopy to study photo-induced mass motions in azobenzene containing thin films

    Science.gov (United States)

    Vu, A. D.; Fabbri, F.; Desboeufs, N.; Boilot, J.-P.; Gacoin, T.; Lahlil, K.; Lassailly, Y.; Martinelli, L.; Peretti, J.

    2014-10-01

    Scanning near-field optical microscopy (SNOM) is used to study the photo-induced deformation of layered structures containing azobenzene derivatives. This approach is particularly relevant since it allows detecting in real-time, with the same probe the surface topography and the optical field distribution at the nanoscale. The correlation between the local light pattern and the ongoing photo-induced deformation in azobenzene-containing thin films is directly evidenced for different light polarization configurations. This unveils several fundamental photodeformation mechanisms, depending not only on the light field properties, but also on the nature of the material. Controlling the projected electromagnetic field distribution allows inscription of various patterns with a resolution at the diffraction limit, i.e. of a few hundreds of nm. Surface relief patterns with characteristic sizes beyond the diffraction limit can also be produced by using the nearfield probe to locally control the photo-mechanical process. Finally, the photo-mechanical properties of azo-materials are exploited to optically patterned metal/dielectric hybrid structures. Gratings are inscribed this way on thin gold films. The characteristic features (enhancement and localization) of the surface plasmons supported by these noble metal structures are studied by near-field optical microscopy.

  20. An experimental method to determine the electrostatic field enhancement factor of a practical conductor surface

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C

    1989-01-01

    A method of determining the field enhancement factor of a practical conductor is presented. The method is developed from a modified theory of discharge onset in a gaseous medium. This modification incorporates the influence of conductor surface roughness. Onset data from an experimental study...... that utilized electrodes of varying surface roughness are examined, and the results obtained using the proposed method are discussed with reference to both the underlying theory and the practical aspects of the experimental measurements...

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

    OpenAIRE

    Th?berge, Francis; Daigle, Jean-Fran?ois; Kieffer, Jean-Claude; Vidal, Fran?ois; Ch?teauneuf?, Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electr...

  2. Demonstration of soft x-ray amplification by optical-field-induced ionization

    International Nuclear Information System (INIS)

    Midorikawa, Katsumi; Nagata, Yutaka; Kubodera, Shoichi; Obara, Minoru; Tashiro, Hideo; Toyoda, Koichi

    1995-01-01

    We have demonstrated the amplification of the 13.5-nm Lyman-α transition in hydrogen-like Li + ions, using a novel optical-field-induced ionization. A small-signal gain coefficient of 20 cm -1 was obtained. The use of preformed Li + plasma as an initial laser medium plays important roles for the production of suitable plasma conditions for an optical-field-induced ionization x-ray laser. (author)

  3. Diagnostic performance of Contrast-enhanced CT in Pyrrolizidine Alkaloids-induced Hepatic Sinusoidal Obstructive Syndrome

    Science.gov (United States)

    Kan, Xuefeng; Ye, Jin; Rong, Xinxin; Lu, Zhiwen; Li, Xin; Wang, Yong; Yang, Ling; Xu, Keshu; Song, Yuhu; Hou, Xiaohua

    2016-01-01

    Hepatic sinusoidal obstruction syndrome (HSOS) can be caused by pyrrolizidine alkaloids(PAs)-containing herbals. Since PAs exposure is obscure and clinical presentation of HSOS is unspecific, it is challenge to establish the diagnosis of PAs-induced HSOS. Gynura segetum is one of the most wide-use herbals containing PAs. The aim of our study is to describe the features of contrast-enhanced computed tomography (CT) in gynura segetum-induced HSOS, and then determine diagnostic performance of radiological signs. We retrospectively analyzed medical records and CT images of HSOS patients (71 cases) and the controls (222 cases) enrolled from January 1, 2008, to Oct 31, 2015. The common findings of contrast CT in PAs-induced HSOS included: ascites (100%), hepatomegaly (78.87%), gallbladder wall thickening (86.96%), pleural effusion (70.42%), hepatic vein narrowing (87.32%), patchy liver enhancement (92.96%), and heterogeneous hypoattenuation (100%); of these signs, patchy enhancement and heterogeneous hypoattenuation were valuable features. Then, the result of diagnostic performance demonstrated that contrast CT possessed better performance in diagnosing PAs-induced HSOS compared with various parameters of Seattle criteria. In conclusion, the patients with PAs-induced HSOS display distinct radiologic features at CT-scan, which reveals that contrast-enhanced CT provides an effective noninvasive method for diagnosing PAs-induced HSOS. PMID:27897243

  4. Inhomogeneous field induced magnetoelectric effect in Mott insulators

    Energy Technology Data Exchange (ETDEWEB)

    Boulaevskii, Lev N [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

    2008-01-01

    We consider a Mott insulator like HoMnO{sub 3} whose magnetic lattice is geometrically frustrated and comprises a 3D array of triangular layers with magnetic moments ordered in a 120{sup o} structure. We show that the effect of a uniform magnetic field gradient, {gradient}H, is to redistribute the electronic charge of the magnetically ordered phase leading to a unfirom electric field gradient. The resulting voltage difference between the crystal edges is proportional to the square of the crystal thickness, or inter-edge distance, L. It can reach values of several volts for |{gradient}H| {approx} 0.01 T/cm and L {approx_equal} 1mm, as long as the crystal is free of antiferromagnetic domain walls.

  5. Field avian metapneumovirus evolution avoiding vaccine induced immunity.

    Science.gov (United States)

    Catelli, Elena; Lupini, Caterina; Cecchinato, Mattia; Ricchizzi, Enrico; Brown, Paul; Naylor, Clive J

    2010-01-22

    Live avian metapneumovirus (AMPV) vaccines have largely brought turkey rhinotracheitis (TRT) under control in Europe but unexplained outbreaks still occur. Italian AMPV longitudinal farm studies showed that subtype B AMPVs were frequently detected in turkeys some considerable period after subtype B vaccination. Sequencing showed these to be unrelated to the previously applied vaccine. Sequencing of the entire genome of a typical later isolate showed numerous SH and G protein gene differences when compared to both a 1987 Italian field isolate and the vaccine in common use. Experimental challenge of vaccinated birds with recent virus showed that protection was inferior to that seen after challenge with the earlier 1987 isolate. Field virus had changed in key antigenic regions allowing replication and leading to disease in well vaccinated birds.

  6. Solitons of scalar field with induced nonlinearity and their stability

    International Nuclear Information System (INIS)

    Saha, B.

    1999-09-01

    Exact particle-like static, spherically and/or cylindrically symmetric solutions to the equations of interacting scalar and electromagnetic field system have been obtained. We considered FRW and Goedel universes as external gravitational field with spherical and cylindrical symmetry respectively. Beside the usual solitons some special regular solutions known as droplets, anti-droplets and hats (confined in finite interval and having trivial value beyond it) have been obtained. It has been shown that in FRW space-time equations with different interaction terms may have stable solutions while within the scope of Goedel model only the droplet-like and the hat-like configurations may be stable, providing that they are located in the region where g 00 > 0. (author)

  7. Balancing Near-Field Enhancement, Absorption, and Scattering for Effective Antenna-Reactor Plasmonic Photocatalysis.

    Science.gov (United States)

    Li, Kun; Hogan, Nathaniel J; Kale, Matthew J; Halas, Naomi J; Nordlander, Peter; Christopher, Phillip

    2017-06-14

    Efficient photocatalysis requires multifunctional materials that absorb photons and generate energetic charge carriers at catalytic active sites to facilitate a desired chemical reaction. Antenna-reactor complexes are an emerging multifunctional photocatalytic structure where the strong, localized near field of the plasmonic metal nanoparticle (e.g., Ag) is coupled to the catalytic properties of the nonplasmonic metal nanoparticle (e.g., Pt) to enable chemical transformations. With an eye toward sustainable solar driven photocatalysis, we investigate how the structure of antenna-reactor complexes governs their photocatalytic activity in the light-limited regime, where all photons need to be effectively utilized. By synthesizing core@shell/satellite (Ag@SiO 2 /Pt) antenna-reactor complexes with varying Ag nanoparticle diameters and performing photocatalytic CO oxidation, we observed plasmon-enhanced photocatalysis only for antenna-reactor complexes with antenna components of intermediate sizes (25 and 50 nm). Optimal photocatalytic performance was shown to be determined by a balance between maximized local field enhancements at the catalytically active Pt surface, minimized collective scattering of photons out of the catalyst bed by the complexes, and minimal light absorption in the Ag nanoparticle antenna. These results elucidate the critical aspects of local field enhancement, light scattering, and absorption in plasmonic photocatalyst design, especially under light-limited illumination conditions.

  8. Magnetic field induced motion behavior of gas bubbles in liquid

    OpenAIRE

    Keliang Wang; Pucheng Pei; Yu Pei; Ze Ma; Huachi Xu; Dongfang Chen

    2016-01-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicula...

  9. Electric field-induced astrocyte alignment directs neurite outgrowth

    OpenAIRE

    ALEXANDER, JOHN K.; FUSS, BABETTE; COLELLO, RAYMOND J.

    2006-01-01

    The extension and directionality of neurite outgrowth are key to achieving successful target connections during both CNS development and during the re-establishment of connections lost after neural trauma. The degree of axonal elongation depends, in large part, on the spatial arrangement of astrocytic processes rich in growth-promoting proteins. Because astrocytes in culture align their processes on exposure to an electrical field of physiological strength, we sought to determine the extent t...

  10. Experiments on plasma turbulence induced by strong, steady electric fields

    International Nuclear Information System (INIS)

    Hamberger, S.M.

    1975-01-01

    The author discusses the effect of applying a strong electric field to collisionless plasma. In particular are compared what some ideas and prejudices lead one to expect to happen, what computer simulation experiments tell one ought to happen, and what actually does happen in two laboratory experiments which have been designed to allow the relevant instability and turbulent processes to occur unobstructed and which have been studied in sufficient detail. (Auth.)

  11. Specific Intensity Direct Current (DC) Electric Field Improves Neural Stem Cell Migration and Enhances Differentiation towards βIII-Tubulin+ Neurons

    Science.gov (United States)

    Zhao, Huiping; Steiger, Amanda; Nohner, Mitch; Ye, Hui

    2015-01-01

    Control of stem cell migration and differentiation is vital for efficient stem cell therapy. Literature reporting electric field–guided migration and differentiation is emerging. However, it is unknown if a field that causes cell migration is also capable of guiding cell differentiation—and the mechanisms for these processes remain unclear. Here, we report that a 115 V/m direct current (DC) electric field can induce directional migration of neural precursor cells (NPCs). Whole cell patching revealed that the cell membrane depolarized in the electric field, and buffering of extracellular calcium via EGTA prevented cell migration under these conditions. Immunocytochemical staining indicated that the same electric intensity could also be used to enhance differentiation and increase the percentage of cell differentiation into neurons, but not astrocytes and oligodendrocytes. The results indicate that DC electric field of this specific intensity is capable of promoting cell directional migration and orchestrating functional differentiation, suggestively mediated by calcium influx during DC field exposure. PMID:26068466

  12. Strong magnetic field induces superconductivity in a Weyl semimetal

    Science.gov (United States)

    Rosenstein, Baruch; Shapiro, B. Ya.; Li, Dingping; Shapiro, I.

    2017-12-01

    Microscopic theory of the normal-to-superconductor coexistence line of a multiband Weyl superconductor subjected to magnetic field is constructed. It is shown that the Weyl semimetal that is nonsuperconducting or having a small critical temperature Tc at zero field might become a superconductor at higher temperatures when the magnetic field is tuned to a series of quantized values Hn. The pairing occurs on Landau levels. It is argued that the phenomenon is detectable much easier in Weyl semimetals than in parabolic band metals since the quantum limit already has been approached in several Weyl materials. The effect of Zeeman coupling leading to splitting of the reentrant superconducting regions on the magnetic phase diagram is considered. An experimental signature of the superconductivity on Landau levels is the reduction of magnetoresistivity. This has been observed already in Cd3As2 and several other compounds. The novel kind of quantum oscillations of magnetoresistance detected in ZrTe5 is discussed along these lines.

  13. Induced polarization and electromagnetic field surveys of sedimentary uranium deposits

    International Nuclear Information System (INIS)

    Campbell, D.L.; Smith, B.D.

    1985-01-01

    Induced polarization (IP) and electromagnetic (EM) geophysical surveys were made over three areas of sedimentary uranium deposits in the western United States. The EM techniques were sometimes useful for investigating general structural settings, but not for finding uranium deposits per se. IP techniques were useful to help pinpoint zones of disseminated pyrite associated with the uranium deposits. In one case no clear differences were seen between the IP signatures of oxidized and reduced ground. Spectral (multi-frequency) IP showed no particular advantages over conventional IP for exploration applications. A sediment mineralization factor is introduced comparable to the ''metal factor'' used to detect porphyry copper mineralization. (author)

  14. Enhancement on field emission characteristics of pulsed laser deposited diamondlike carbon films using Au precoatings

    International Nuclear Information System (INIS)

    Chuang, F.Y.; Sun, C.Y.; Cheng, H.F.; Lin, I.N.

    1997-01-01

    Using Au precoatings has been observed to significantly enhance the field emission properties of diamondlike carbon (DLC) films deposited on Si substrates. The electron emission can be turned on at a low field as 7 V/μm and a large emission current density as 2000 μA/cm 2 can be obtained at 20 V/μm applied field. However, preannealing the Au-coated Si substrates at 500 degree C for 30 min is necessary to achieve such a performance. Microscopic examination on surface and cross-sectional morphologies of the DLC/Au/Si films using atomic force microscopy and scanning electron microscopy, respectively, in conjunction with the elemental depth profile examination of these films using secondary ion mass spectroscopy, indicated that substantial interdiffusion between DLC, Au, and Si layers has occurred. Such kind of reaction is proposed to lower the resistance for electrons to transport across the interfaces and, thereafter, enhances the field emission properties of the DLC/Au/Si films. copyright 1997 American Institute of Physics

  15. High Field Phase Diagram of the Field-Induced Superconducting State of λ-(BETS)2FeCl4

    Science.gov (United States)

    Balicas, L.; Brooks, J. S.; Storr, K.; Uji, S.; Tokumoto, M.; Tanaka, H.; Kobayashi, H.; Kobayashi, A.; Barzykin, V.; Gor'kov, L. P.

    2002-07-01

    We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor λ-(BETS)2FeCl4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T, and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe3+ ions. We further argue that the Fe3+ moments are essential to stabilize the resulting singlet, two-dimensional superconducting state. Here we provide experimental evidence indicating that this state, as well as the insulating antiferromagnetic ground state, is extremely sensitive to hydrostatic pressure.

  16. The impact of coronal mass ejection on the horizontal geomagnetic fields and the induced geoelectric fields

    Science.gov (United States)

    Falayi, E. O.; Adebesin, B. O.; Bolaji, O. S.

    2018-02-01

    This work investigates the influence of coronal mass ejection (CME) on the time derivatives of horizontal geomagnetic and geoelectric fields, proxy parameters for identifying GICs. 16 events were identified for the year 2003 from the CORONAS-PHOTON spacecraft. Five of the events (May 29, June 9, October 28, October 29, and November 4) were extensively discussed over four magnetic observatories, were analyzed using the time derivatives of the horizontal geomagnetic (dH/dt) and geoelectric (EH) fields obtained from data of the INTERMAGNET network. It was observed that energy distributions of the wavelet power spectrum of the horizontal geoelectric field are noticed at the nighttime on both 29 May and 9 June 2003 across the stations. Daytime and nighttime intensification of energy distribution of the wavelet power spectrum of the horizontal geoelectric field are observed on both 28 and 29 October 2003 due to strong westward electrojet. The 4 November 2003 event depicts daytime amplification of energy distributions of the wavelet power spectrum across the stations. The highest correlation magnitude is obtained in the event of 4 November 2003 between dH/dt and EH relationships during the intense solar flare of class X 17.4. We observed that the correlation magnitude between dH/dt and EH increases with increase in CME activity. We concluded that the response of the surface impedance model for different stations plays a key role in determining the surface electric field strength, due to large electric field changes at different stations.

  17. Hall effect enhanced low-field sensitivity in a three-contact extraordinary magnetoresistance sensor

    KAUST Repository

    Sun, Jian

    2012-06-06

    An extraordinary magnetoresistance (EMR) device with a 3-contact geometry has been fabricated and characterized. A large enhancement of the output sensitivity at low magnetic fields compared to the conventional EMR device has been found, which can be attributed to an additional influence coming from the Hall effect. Output sensitivities of 0.19 mV/T at zero-field and 0.2 mV/T at 0.01 T have been measured in the device, which is equivalent to the ones of the conventional EMR sensors with a bias of ∼0.04 T. The exceptional performance of EMR sensors in the high field region is maintained in the 3-contact device.

  18. Field analysis and enhancement of multi-pole magnetic components fabricated on printed circuit board

    International Nuclear Information System (INIS)

    Chiu, K.-C.; Chen, C.-S.

    2007-01-01

    A multi-pole magnetic component magnetized with a fine magnetic pole pitch of less than 1 mm is very difficult to achieve by using traditional methods. Moreover, it requires a precise mechanical process and a complicated magnetization system. Different fine magnetic pole pitches of 300, 350 and 400 μm have been accomplished on 9-pole magnetic components through the printed circuit board (PCB) manufacturing technology. Additionally, another fine magnetic pole pitch of 500 μm was also fabricated on a dual-layered (DL) wire circuit structure to investigate the field enhancement. After measurements, a gain factor of 1.37 was obtained in the field strength. The field variations among different magnetic pole pitches were analyzed in this paper

  19. Enhancing the performance of the light field microscope using wavefront coding.

    Science.gov (United States)

    Cohen, Noy; Yang, Samuel; Andalman, Aaron; Broxton, Michael; Grosenick, Logan; Deisseroth, Karl; Horowitz, Mark; Levoy, Marc

    2014-10-06

    Light field microscopy has been proposed as a new high-speed volumetric computational imaging method that enables reconstruction of 3-D volumes from captured projections of the 4-D light field. Recently, a detailed physical optics model of the light field microscope has been derived, which led to the development of a deconvolution algorithm that reconstructs 3-D volumes with high spatial resolution. However, the spatial resolution of the reconstructions has been shown to be non-uniform across depth, with some z planes showing high resolution and others, particularly at the center of the imaged volume, showing very low resolution. In this paper, we enhance the performance of the light field microscope using wavefront coding techniques. By including phase masks in the optical path of the microscope we are able to address this non-uniform resolution limitation. We have also found that superior control over the performance of the light field microscope can be achieved by using two phase masks rather than one, placed at the objective's back focal plane and at the microscope's native image plane. We present an extended optical model for our wavefront coded light field microscope and develop a performance metric based on Fisher information, which we use to choose adequate phase masks parameters. We validate our approach using both simulated data and experimental resolution measurements of a USAF 1951 resolution target; and demonstrate the utility for biological applications with in vivo volumetric calcium imaging of larval zebrafish brain.

  20. Self-consistent electric field-induced dipole interaction of colloidal spheres, cubes, rods, and dumbbells

    NARCIS (Netherlands)

    Kwaadgras, Bas W.; Van Roij, René; Dijkstra, Marjolein

    2014-01-01

    When calculating the interaction between electric field-induced dipoles, the dipole moments are often taken to be equal to their polarizability multiplied by the external electric field. However, this approach is not exact, since it does not take into account the fact that particles with a dipole

  1. Gateable Skyrmion Transport via Field-induced Potential Barrier Modulation

    Science.gov (United States)

    Fook, Hiu Tung; Gan, Wei Liang; Lew, Wen Siang

    2016-02-01

    We report on the influence of pinning potentials on current-driven skyrmion dynamics and demonstrate that skyrmions can be gated via either magnetic or electric fields. When encountering pinning potentials, skyrmions are well known to simply skirt around them. However, we show that skyrmions can be depinned much more easily when their driving force is oriented against the pinning site rather that the intuitive option of being oriented away. This observation can be exploited together with the normally undesirable Magnus force for the creation of a skyrmion diode. The phenomenon is explained by the increased skyrmion compression resulting from the spin transfer torque opposing the repulsive potential. The smaller skyrmion size then experiences a reduced pinning potential. For practical low-power device applications, we show that the same skyrmion compression can be recreated by applying either a magnetic or electric field. Our analysis provides an insight on the skyrmion dynamics and manipulation that is critical for the realization of skyrmion-based transistors and low-power memory.

  2. Determination of Enhanced Oil Recovery Candidate Fields in the Volga-Ural Oil and Gas Region Territory

    OpenAIRE

    Turbakov, Mikhail; Shcherbakov, Аleksandr

    2015-01-01

    Most of the current Russian oil production comes from mature fields. The application of enhanced oil recovery methods on oil fields increases recovery efficiency. This article presents an analysis of the increased field development efficiency methods of the Volga-Ural oil and gas region, which allows the full and efficient development of last-stage fields with unconventional reserves and production stabilization. The selection of the optimum method for a given field is a complex procedure con...

  3. Enhancement of pentobarbital-induced sleep by apigenin through chloride ion channel activation.

    Science.gov (United States)

    Kim, Jae-Wook; Kim, Chung-Soo; Hu, Zhenzhen; Han, Jin-Yi; Kim, Si Kwan; Yoo, Sung-Kwang; Yeo, Yeong Man; Chong, Myong Soo; Lee, Kinam; Hong, Jin Tae; Oh, Ki-Wan

    2012-02-01

    This experiment was performed to investigate whether apigenin has hypnotic effects and/or enhances pentobarbital-induced sleep behaviors through the GABAergic systems. Apigenin prolonged sleep time induced by pentobarbital similar to muscimol, a GABA(A) receptors agonist. Apigenin also increased sleep rate and sleep time in the combined administration with pentobarbital at the sub-hypnotic dosage, and showed synergic effects with muscimol in potentiating sleep onset and enhancing sleep time induced by pentobarbital. In addition, both of apigeinin and pentobarbital increased chloride influx in primary cultured cerebellar granule cells. Apigenin increased glutamate decarboxylase (GAD) and had no effect on the expression of GABA(A) receptor α-, β-, γ-subunits in n hippocampus of mouse brain, showing different expression of subunits from pentobarbital treatment group. In conclusion, it is suggested that apigenin augments pentobarbital-induced sleep behaviors through chloride ion channel activation.

  4. Enhancement in the photodetection of ZnO nanowires by introducing surface-roughness-induced traps

    International Nuclear Information System (INIS)

    Park, Woojin; Jo, Gunho; Hong, Woong-Ki; Yoon, Jongwon; Choe, Minhyeok; Ji, Yongsung; Kim, Geunjin; Kahng, Yung Ho; Lee, Kwanghee; Lee, Takhee; Lee, Sangchul; Wang, Deli

    2011-01-01

    We investigated the enhanced photoresponse of ZnO nanowire transistors that was introduced with surface-roughness-induced traps by a simple chemical treatment with isopropyl alcohol (IPA). The enhanced photoresponse of IPA-treated ZnO nanowire devices is attributed to an increase in adsorbed oxygen on IPA-induced surface traps. The results of this study revealed that IPA-treated ZnO nanowire devices displayed higher photocurrent gains and faster photoswitching speed than transistors containing unmodified ZnO nanowires. Thus, chemical treatment with IPA can be a useful method for improving the photoresponse of ZnO nanowire devices.

  5. Effects of arsenic deactivation on arsenic-implant induced enhanced diffusion in silicon

    International Nuclear Information System (INIS)

    Dokumaci, O.; Law, M.E.; Krishnamoorthy, V.; Jones, K.S.

    1996-01-01

    The enhanced diffusion of boron due to high dose arsenic implantation into silicon is studied as a function of arsenic dose. The behavior of both the type-V and end-of-range loops is investigated by transmission electron microscopy (TEM). The role of arsenic deactivation induced interstitials and type-V loops on enhanced diffusion is assessed. Reduction of the boron diffusivity is observed with increasing arsenic dose at three different temperatures. The possible explanations for this reduction are discussed

  6. Benzocoumarin-Styryl Hybrids: Aggregation and Viscosity Induced Emission Enhancement.

    Science.gov (United States)

    Warde, Umesh; Sekar, Nagaiyan

    2017-09-01

    Two benzo[h]chromen-3-yl)ethylidene) malononitrile styryl hybrid dyes are synthesized and characterized by NMR and elemental analysis. One is based on nitrogen donor and other on oxygen (3b and 3b respectively). Dyes are low emissive in the solution but dramatically showed increase in emission intensity in aggregates form in the THF (tetrahydrofuran) /water system. Dyes are also sensitive to viscosity and showed increased emission intensity in the DCM:PEG 400 system and DMF:PEG 400 system respectively. Dyes 3a and 3b showed higher viscosity sensitivity constant (0.67 and 0.39 respectively) in DMF:PEG 400 system compared to DCM:PEG 400 (0.47 and 0.21 respectively) system which is contrary to the traditional concept of FMRs. Results shows that lowering of twisted intramolecular charge transfer (TICT) and increase in intramolecular charge transfer (ICT) in the excited state could be the reason for such behavior in the aggregate and highly viscous state. This study may provide the new insights into the field of AIEE and FMR research of such hybrid molecules.

  7. Enhanced exchange bias fields for CoO/Co bilayers: influence of antiferromagnetic grains and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Cheng-Hsun-Tony; Chang, Shin-Chen [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Tsay, Jyh-Shen, E-mail: jstsay@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Yao, Yeong-Der [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

    2017-05-31

    Highlights: • An antiferromagnetic grain model on exchange bias phenomena is proposed. • Grain size and grain density are considered. • For smaller grain size, the dependence of t{sub CoO} on T{sub B} showed a less pronounced variation. • An increased grain density is responsible for the enhancement in the exchange bias fields. - Abstract: The emergence and optimization of devices that can be applied to spintronics have attracted considerable interest, and both experimental and theoretical approaches have been used in studies of exchange bias phenomena. A survey of the literature indicates that great efforts have been devoted to improving exchange bias fields, while only limited attempts have been made to control the temperature dependence of exchange bias. In this study, the influence of antiferromagnetic grains on exchange bias phenomena in CoO/Co bilayers on a semiconductor surface was investigated. Based on an antiferromagnetic grain model, a correlation between grain size, grain density, blocking temperature, and the exchange bias field was established. For crystallites with a smaller median diameter, the dependence of the thickness of the CoO layer on blocking temperature showed a less pronounced variation. This is due to the larger thermal agitation of the atomic spin moments in the grain, which causes a weaker exchange coupling between atomic spin moments. The enhanced density of antiferromagnetic/ferromagnetic pinning sites resulting from an increased grain density is responsible for the enhancement in the exchange bias fields. The results reported herein provide insights into our knowledge related to controlling the temperature dependence of exchange bias and related mechanisms.

  8. Effect of Induced Magnetic Field on MHD Mixed Convection Flow in Vertical Microchannel

    Science.gov (United States)

    Jha, B. K.; Aina, B.

    2017-08-01

    The present work presents a theoretical investigation of an MHD mixed convection flow in a vertical microchannel formed by two electrically non-conducting infinite vertical parallel plates. The influence of an induced magnetic field arising due to motion of an electrically conducting fluid is taken into consideration. The governing equations of the motion are a set of simultaneous ordinary differential equations and their exact solutions in dimensionless form have been obtained for the velocity field, the induced magnetic field and the temperature field. The expressions for the induced current density and skin friction have also been obtained. The effects of various non-dimensional parameters such as rarefaction, fluid wall interaction, the Hartmann number and the magnetic Prandtl number on the velocity, the induced magnetic field, the temperature, the induced current density, and skin friction have been presented in a graphical form. It is found that the effect of the Hartmann number and magnetic Prandtl number on the induced current density is found to have a decreasing nature at the central region of the microchannel.

  9. Magnetotransport measurements of current induced effective fields in Ta/CoFeB/MgO

    Science.gov (United States)

    Zhang, Chaoliang; Yamanouchi, Michihiko; Sato, Hideo; Fukami, Shunsuke; Ikeda, Shoji; Matsukura, Fumihiro; Ohno, Hideo

    2013-12-01

    We evaluate current-induced effective magnetic fields in perpendicularly magnetized Ta/CoFeB/MgO structures from the external magnetic field angle dependence of the Hall resistance. We confirm the presence of two components of effective fields. The dependence of their magnitudes on Ta thickness implies that both components are related to the spin current in Ta layer generated by the spin Hall effect.

  10. Field-Induced Magnetostructural Transitions in Antiferromagnetic Fe1+ y Te1- x S x

    Science.gov (United States)

    Tokunaga, M.; Kihara, T.; Mizuguchi, Y.; Takano, Y.

    2013-03-01

    Transport and structural properties of Fe1+ y Te1- x S x were studied in pulsed magnetic fields. Application of high magnetic fields induces first order transitions showing positive magnetoresistance effects in the antiferromagnetic phase. Polarizing microscope images taken at high magnetic fields revealed the concomitant melting of the orbital order. These results indicate the importance of crossed coupling between spin and lattice or orbital degrees of freedom in this compound.

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

    OpenAIRE

    Kameda, Takashi; Ohkumura, 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 ...

  12. Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

    International Nuclear Information System (INIS)

    Babushok, V.I.; DeLucia, F.C.; Gottfried, J.L.; Munson, C.A.; Miziolek, A.W.

    2006-01-01

    A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of the double pulse laser induced breakdown spectroscopy technique: collinear, orthogonal pre-spark, orthogonal pre-heating and dual pulse crossed beam modes. In addition, combinations of laser pulses with different wavelengths, different energies and durations were studied, thus providing flexibility in the choice of wavelength, pulse width, energy and pulse sequence. The double pulse laser induced breakdown spectroscopy approach provides a significant enhancement in the intensity of laser induced breakdown spectroscopy emission lines up to two orders of magnitude greater than a conventional single pulse laser induced breakdown spectroscopy. The double pulse technique leads to a better coupling of the laser beam with the plasma plume and target material, thus providing a more temporally effective energy delivery to the plasma and target. The experimental results demonstrate that the maximum effect is obtained at some optimum separation delay time between pulses. The optimum value of the interpulse delay depends on several factors, such as the target material, the energy level of excited states responsible for the emission, and the type of enhancement process considered. Depending on the specified parameter, the enhancement effects were observed on different time scales ranging from the picosecond time level (e.g., ion yield, ablation mass) up to the hundred microsecond level (e.g., increased emission intensity for laser induced breakdown spectroscopy of submerged metal target in water). Several suggestions have been proposed to explain

  13. Photocurrent, Rectification, and Magnetic Field Symmetry of Induced Current Through Quantum Dots

    DEFF Research Database (Denmark)

    DiCarlo, L.; M. Marcus, C.; Harris jr, J.

    2003-01-01

    We report mesoscopic dc current generation in an open chaotic quantum dot with ac excitation applied to one of the shape-defining gates. For excitation frequencies large compared to the inverse dwell time of electrons in the dot (i.e., GHz), we find mesoscopic fluctuations of induced current...... that are fully asymmetric in the applied perpendicular magnetic field, as predicted by recent theory. Conductance, measured simultaneously, is found to be symmetric in field. In the adiabatic (i.e., MHz) regime, in contrast, the induced current is always symmetric in field, suggesting its origin is mesoscopic...

  14. Electric-Field-Induced Soft-Mode Hardening in SrTiO3 Films

    Science.gov (United States)

    Akimov, I. A.; Sirenko, A. A.; Clark, A. M.; Hao, J.-H.; Xi, X. X.

    2000-05-01

    We have studied electric-field-induced Raman scattering in SrTiO3 thin films using an indium-tin-oxide/SrTiO3/SrRuO3 structure grown by pulsed laser deposition. The soft mode polarized along the field becomes Raman active. Experimental data for electric-field-induced hardening of the soft modes and the tuning of the static dielectric constant are in agreement described by the Lyddane-Sachs-Teller formalism. The markedly different behavior of the soft modes in thin films from that in the bulk is explained by the existence of local polar regions.

  15. Induced mutations for disease resistance in wheat and field beans

    International Nuclear Information System (INIS)

    Abdel-Hak, T.M.; Kamel, A.H.

    1976-01-01

    Wheat disease in Egypt is reviewed and results of mutation breeding by γ irradiation for disease resistance in wheat and field beans are described. Wheat mutants of the variety Giza 155 resistant to leaf rust, Giza 156 resistant to both leaf and yellow rusts, and Tosson with a reasonable level of combined resistance to the three rusts in addition to mutants of the tetraploid variety Dakar 52 with a good level of stem and yellow rust resistance are required. Their seeds were subjected to 10, 15 and 20 krad. Of 3000-3700 M 2 plants from each variety and dosage, 22 plants from both Giza 155 and Giza 156, although susceptible, showed a lower level of disease development. In 1975, M 3 families of these selected plants and 6000 plants from bulked material were grown from each variety and dosage at two locations. Simultaneously, an additional population consisting of 3000 mutagen-treated seeds was grown to have a reasonable chance of detecting mutants; 2 heads from each plant were harvested. These will be grown next season (1976) to make a population of 25,000-30,000 M 2 plants and screened to composite cultures of specific rusts. Vicia faba seeds of field bean varieties Giza 1, Giza 2 and Rebaya 40, equally susceptible to rust and chocolate spot, were subjected to 3, 5 and 7 krad of 60 Co gamma radiation and 800 M 1 plants were grown in 1972 per variety and dose. Up to this later growing season (M 3 ) no resistance was detected in M 3 plank

  16. Electric field-induced transient birefringence and light scattering of synthetic liposomes.

    Science.gov (United States)

    Asgharian, N; Schelly, Z A

    1999-05-12

    The dynamics of electric field-induced transient birefringence Deltan(t) and light scattering (detected as turbidity) of 190 nm diameter unilamellar vesicles of dioleoylphosphatidylcholine are investigated as a function of applied field strength E, length of the square pulse Deltat, lipid concentration, mean hydrodynamic diameter , ionic strength, and temperature. Generally, induced birefringence exclusively is observed at low lipid concentration and below certain threshold values of E and Deltat, whereas concomitant induced turbidity appears at high lipid concentration and above thresholds values of E and Deltat. Turbidity is monitored through the change in transmitted intensity DeltaS parallel(t) and DeltaS perpendicular(t) of light polarized parallel and perpendicular to the applied field E. The field-induced structural changes are reflected in double-exponential forward relaxation and triple-exponential reverse relaxation of the positive birefringence, and in non-exponential relaxations of DeltaS parallel (t) and DeltaS perpendicular(t). Under the field, the associated physical events are interpreted as elongation of the spherical bilayer shells in the direction of E, linear chain formation (pearling) of the induced dipolar liposomes parallel to E, and partial fusion of adjoining vesicles within the chains. Under conditions where electroporation can be detected, pore opening succeeds the elongation of the vesicles. After termination of the field, the vesicles return to their original time average spherical shape, the oriented chains randomize and disintegrate, and the fused structures are converted either to unilamellar or multilamellar vesicles.

  17. Impact of electrical conductivity on acid hydrolysis of guar gum under induced electric field.

    Science.gov (United States)

    Li, Dandan; Zhang, Yao; Yang, Na; Jin, Zhengyu; Xu, Xueming

    2018-09-01

    This study aimed to improve induced electric field (IEF)-assisted hydrolysis of polysaccharide by controlling electrical conductivity. As the conductivity of reaction medium was increased, the energy efficiency of IEF was increased because of deceased impedance, as well as enhanced output voltage and temperature, thus the hydrolysis of guar gum (GG) was accelerated under IEF. Changes in weight-average molecular weight (Mw) suggested that IEF-assisted hydrolysis of GG could be described by the first-order kinetics 1/Mw ∝ kt, with the rate constant (k), varying directly with the medium conductivity. Although IEF-assisted hydrolysis largely disrupted the morphological structure of GG, it had no impact on the chemical structure. In comparison to native GG, the steady shear viscosity of hydrolyzed GG dramatically declined while the thermal stability slightly decreased. This study extended the knowledge of electrical conductivity upon IEF-assisted acid hydrolysis of GG and might contribute to a better utilization of IEF for polysaccharide modification. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Electron-electron interactions in graphene field-induced quantum dots in a high magnetic field

    DEFF Research Database (Denmark)

    Orlof, A.; Shylau, Artsem; Zozoulenko, I. V.

    2015-01-01

    We study the effect of electron-electron interaction in graphene quantum dots defined by an external electrostatic potential and a high magnetic field. To account for the electron-electron interaction, we use the Thomas-Fermi approximation and find that electron screening causes the formation...... of compressible strips in the potential profile and the electron density. We numerically solve the Dirac equations describing the electron dynamics in quantum dots, and we demonstrate that compressible strips lead to the appearance of plateaus in the electron energies as a function of the magnetic field. Finally...

  19. Effect of the induced magnetic field on peristaltic flow of a couple stress fluid

    International Nuclear Information System (INIS)

    Mekheimer, Kh.S.

    2008-01-01

    We have analyzed the MHD flow of a conducting couple stress fluid in a slit channel with rhythmically contracting walls. In this analysis we are taking into account the induced magnetic field. Analytical expressions for the stream function, the magnetic force function, the axial pressure gradient, the axial induced magnetic field and the distribution of the current density across the channel are obtained using long wavelength approximation. The results for the pressure rise, the frictional force per wave length, the axial induced magnetic field and distribution of the current density across the channel have been computed numerically and the results were studied for various values of the physical parameters of interest, such as the couple stress parameter γ, the Hartmann number M, the magnetic Reynolds number R m and the time averaged mean flow rate θ. Contour plots for the stream and magnetic force functions are obtained and the trapping phenomena for the flow field is discussed

  20. A study on some optical illusions based upon the theory of inducing field.

    Science.gov (United States)

    Ge, Sheng; Saito, Takashi; Wu, Jing-Long; Iramina, K

    2006-01-01

    The study of optical illusion is an important method to elucidate the mechanism of visual perception. However, many details about the cause of optical illusions are still unclear. In this research, based on the characteristic of the physiological structure of the retina, we proposed an on-center receptive field model of the retina. Using this model, we simulated the distributions of the inducing field of some visual stimulus. Comparing to the past studies' results, the validity of the proposed model was proofed. Furthermore, we simulated the distributions of the inducing field of some typical illusions. The simulation results can explain these illusion phenomenon rationally. Therefore, it suggested that some of illusions are probably engendered by the distributions of the inducing field in the retina which generated by the illusions stimuli. The practicality of the proposed model was also verified.

  1. Within-field advection enhances evaporation and transpiration in a vineyard in an arid environment

    Science.gov (United States)

    Kool, Dilia; Ben-Gal, Alon; Agam, Nurit

    2017-04-01

    Advection of hot air from a warmer to a cooler surface is known to enhance evaporation through additional supply of energy, provided that water is readily available. This study investigated advection in an isolated irrigated vineyard in the Negev desert, over a period of several months under changing plant cover and environmental conditions, and for different degrees of water availability. Field, canopy, and soil energy balance fluxes were assessed, as well as likely indicators of advection such as wind speed, VPD, vertical temperature gradients between the soil, the canopy air space, and the air, and lateral temperature gradients between the vineyard and the surrounding desert. It was found that for a period from May to July, advection enhanced transpiration by 8%, of which an estimated 80% was soil-to-canopy advection and 20% was local advection. At times, soil-to-canopy advection was responsible for as much as 30-40% of transpiration. Wet irrigated strips likewise experienced soil-to-soil advection from drier soil, but to a much lesser degree. A surprisingly large difference was observed in the contribution of advection to transpiration between June (2%) and July (11%), which had almost identical environmental conditions. This indicates that small changes in the agro-system could have a large impact on within-field advection, and that systems could potentially be managed to reduce or enhance advection.

  2. Enhanced transconductance in a double-gate graphene field-effect transistor

    Science.gov (United States)

    Hwang, Byeong-Woon; Yeom, Hye-In; Kim, Daewon; Kim, Choong-Ki; Lee, Dongil; Choi, Yang-Kyu

    2018-03-01

    Multi-gate transistors, such as double-gate, tri-gate and gate-all-around transistors are the most advanced Si transistor structure today. Here, a genuine double-gate transistor with a graphene channel is experimentally demonstrated. The top and bottom gates of the double-gate graphene field-effect transistor (DG GFET) are electrically connected so that the conductivity of the graphene channel can be modulated simultaneously by both the top and bottom gate. A single-gate graphene field-effect transistor (SG GFET) with only the top gate is also fabricated as a control device. For systematical analysis, the transfer characteristics of both GFETs were measured and compared. Whereas the maximum transconductance of the SG GFET was 17.1 μS/μm, that of the DG GFET was 25.7 μS/μm, which is approximately a 50% enhancement. The enhancement of the transconductance was reproduced and comprehensively explained by a physics-based compact model for GFETs. The investigation of the enhanced transfer characteristics of the DG GFET in this work shows the possibility of a multi-gate architecture for high-performance graphene transistor technology.

  3. Characterizing the Potential for Injection-Induced Fault Reactivation Through Subsurface Structural Mapping and Stress Field Analysis, Wellington Field, Sumner County, Kansas

    Science.gov (United States)

    Schwab, Drew R.; Bidgoli, Tandis S.; Taylor, Michael H.

    2017-12-01

    Kansas, like other parts of the central U.S., has experienced a recent increase in seismicity. Correlation of these events with brine disposal operations suggests pore fluid pressure increases are reactivating preexisting faults, but rigorous evaluation at injection sites is lacking. Here we determine the suitability of CO2 injection into the Cambrian-Ordovician Arbuckle Group for long-term storage and into a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. To determine the potential for injection-induced earthquakes, we map subsurface faults and estimate in situ stresses, perform slip and dilation tendency analyses to identify well-oriented faults relative to the estimated stress field, and determine the pressure changes required to induce slip at reservoir and basement depths. Three-dimensional seismic reflection data reveal 12 near-vertical faults, mostly striking NNE, consistent with nodal planes from moment tensor solutions from recent earthquakes in the region. Most of the faults cut both reservoirs and several clearly penetrate the Precambrian basement. Drilling-induced fractures (N = 40) identified from image logs and inversion of earthquake moment tensor solutions (N = 65) indicate that the maximum horizontal stress is approximately EW. Slip tendency analysis indicates that faults striking reservoir conditions, whereas faults striking 020°-049° may be prone to reactivation with increasing pore fluid pressure. Although the proposed injection volume (40,000 t) is unlikely to reactive faults at reservoir depths, high-rate injection operations could reach pressures beyond the critical threshold for slip within the basement, as demonstrated by the large number of injection-induced earthquakes west of the study area.

  4. SELECTION AND TREATMENT OF STRIPPER GAS WELLS FOR PRODUCTION ENHANCEMENT, MOCANE-LAVERNE FIELD, OKLAHOMA

    Energy Technology Data Exchange (ETDEWEB)

    Scott Reeves; Buckley Walsh

    2003-08-01

    In 1996, Advanced Resources International (ARI) began performing R&D targeted at enhancing production and reserves from natural gas fields. The impetus for the effort was a series of field R&D projects in the early-to-mid 1990's, in eastern coalbed methane and gas shales plays, where well remediation and production enhancement had been successfully demonstrated. As a first step in the R&D effort, an assessment was made of the potential for restimulation to provide meaningful reserve additions to the U.S. gas resource base, and what technologies were needed to do so. That work concluded that: (1) A significant resource base did exist via restimulation (multiples of Tcf). (2) The greatest opportunities existed in non-conventional plays where completion practices were (relatively) complex and technology advancement was rapid. (3) Accurate candidate selection is the greatest single factor that contributes to a successful restimulation program. With these findings, a field-oriented program targeted at tight sand formations was initiated to develop and demonstrate successful candidate recognition technology. In that program, which concluded in 2001, nine wells were restimulated in the Green River, Piceance and East Texas basins, which in total added 2.9 Bcf of reserves at an average cost of $0.26/Mcf. In addition, it was found that in complex and heterogeneous reservoirs (such as tight sand formations), candidate selection procedures should involve a combination of fundamental engineering and advanced pattern recognition approaches, and that simple statistical methods for identifying candidate wells are not effective. In mid-2000, the U.S. Department of Energy (DOE) awarded ARI an R&D contract to determine if the methods employed in that project could also be applied to stripper gas wells. In addition, the ability of those approaches to identify more general production enhancement opportunities (beyond only restimulation), such as via artificial lift and compression

  5. An investigation into the induced electric fields from transcranial magnetic stimulation

    Science.gov (United States)

    Hadimani, Ravi; Lee, Erik; Duffy, Walter; Waris, Mohammed; Siddiqui, Waquar; Islam, Faisal; Rajamani, Mahesh; Nathan, Ryan; Jiles, David; David C Jiles Team; Walter Duffy Collaboration

    Transcranial magnetic stimulation (TMS) is a promising tool for noninvasive brain stimulation that has been approved by the FDA for the treatment of major depressive disorder. To stimulate the brain, TMS uses large, transient pulses of magnetic field to induce an electric field in the head. This transient magnetic field is large enough to cause the depolarization of cortical neurons and initiate a synaptic signal transmission. For this study, 50 unique head models were created from MRI images. Previous simulation studies have primarily used a single head model, and thus give a limited image of the induced electric field from TMS. This study uses finite element analysis simulations on 50 unique, heterogeneous head models to better investigate the relationship between TMS and the electric field induced in brain tissues. Results showed a significant variation in the strength of the induced electric field in the brain, which can be reasonably predicted by the distance from the TMS coil to the stimulated brain. Further, it was seen that some models had high electric field intensities in over five times as much brain volume as other models.

  6. Benefits of integrates management approach for production enhancement projects: Casabe Field alliance

    Energy Technology Data Exchange (ETDEWEB)

    Rueda, Carlos Fernando [Ecopetrol S.A., Putumayo (Colombia); Saldano, Roberto [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This paper describes the successful achievements in a mature field through an innovative gain-share business model implemented in the Casabe Field, between Eco petrol and Schlumberger. It was determined by both parties that the field risk rehabilitation could be better managed by a long term sharing association, whereby the strengths of both organizations could be brought to bear, Eco petrol having the asset knowledge and experience, remaining as field operator and owner of reserves, and Schlumberger possessing new technologies and practices to allow identification and exploitation of production enhancement opportunities. Furthermore, the investment that both partners made in the alliance are recovered by the revenue generated from incremental production. As a result of the Casabe mature field rehabilitation the oil production that was declining over the last 10 years, was incremented from 5.240 bopd to 11.008 bopd, the recovery factor climbed by 5 % and the annual reserve replacement ratio in excess of 2 over the last four years. Those challenges have been achieved thanks to both organizations that could successfully work together in an environment of trust, innovation and timing up. (author)

  7. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pinch

    International Nuclear Information System (INIS)

    Lin, L.; Brower, D. L.; Ding, W. X.; Anderson, J. K.; Capecchi, W.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Nornberg, M. D.; Reusch, J.; Sarff, J. S.; Liu, D.

    2014-01-01

    Multiple bursty energetic-particle (EP) driven modes with fishbone-like structure are observed during 1 MW tangential neutral-beam injection in a reversed field pinch (RFP) device. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of EP instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport. Density fluctuations exhibit a dynamically evolving, inboard-outboard asymmetric spatial structure that peaks in the core where fast ions reside. The measured mode frequencies are close to the computed shear Alfvén frequency, a feature consistent with continuum modes destabilized by strong drive. The frequency pattern of the dominant mode depends on the fast-ion species. Multiple frequencies occur with deuterium fast ions compared to single frequency for hydrogen fast ions. Furthermore, as the safety factor (q) decreases, the toroidal mode number of the dominant EP mode transits from n=5 to n=6 while retaining the same poloidal mode number m=1. The transition occurs when the m=1, n=5 wave-particle resonance condition cannot be satisfied as the fast-ion safety factor (q fi ) decreases. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growth phase arising from the beam fueling followed by a rapid drop when the EP modes peak, indicating that the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced with the onset of multiple EP modes

  8. Physio-biochemical basis of iron-sulfide nanoparticle induced growth and seed yield enhancement in B. juncea.

    Science.gov (United States)

    Rawat, Madhu; Nayan, Rajeev; Negi, Bhawana; Zaidi, M G H; Arora, Sandeep

    2017-09-01

    Metal nanoparticles have been reported to influence plant growth and productivity. However, the molecular mechanisms underlying the effects have not been completely understood yet. Current work describes the physio-biochemical basis of iron sulfide nanoparticle induced growth and yield enhancement in Brassica juncea. Iron sulfide nanoparticles (0, 2, 4, 6, 8 and 10 ppm) were used for foliar treatment of B. juncea at 30, 45 and 60 days after sowing, under field conditions. Foliar treatment of 4 ppm iron sulfide nanoparticle solution at 30 days after sowing brought maximal enhancement in agronomic attributes of the treated plants. Results of assays i.e. total chlorophyll, electrolyte leakage, Malondialdehyde (MDA), proline, H 2 O 2 and antioxidant enzyme activities indicated the benign effect of iron sulfide nanoparticles on plants. Consequently, improved redox status of the treated plants, enabled them to assimilate higher photosynthate. The augmentation in growth and seed yield in iron sulfide nanoparticle treated plants was amply supported by activation of RUBISCO small subunit (rubisco S), RUBISCO large subunit (rubisco L), glutamine synthetase (gs) and glutamate synthase (gogat) genes. Thus, iron sulfide nanoparticle induced growth and yield enhancement is proposed to be mediated through activation of carbon and nitrogen assimilatory pathways at specific growth stage. The iron content in the leaves and root tissues of the treated plants was also significantly improved. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  9. Layered structures with delta-doped layers for enhancement of field emission

    International Nuclear Information System (INIS)

    Evtukh, A.A.; Litovchenko, V.G.; Marchenko, R.I.; Kydzinovski, S.Y.

    1997-01-01

    The electron field emission, from silicon tip arrays with layer structures on their surfaces, was investigated. The main task of the study was to enhance field emission. The n Si SiO 2 , n Si Cs SiO 2 , n Si SiO 2 Si * SiO 2 , n Si Si 3 N 4 Si * SiO 2 , etc., were among the different prepared layered structures. The thicknesses of dielectric layers were 1 5 nm and they were prepared both by thermal oxidation and by chemical vapor deposition (CVD). The cesium was deposited on the cathodes with the application of cesium salt (CsCl) in solution. The outer SiO 2 layer prevents cesium from evaporating during heating or reaction under exposure to gases. The thin silicon layer (Si * ) was formed by CVD. The measurements of electron field emission from layered structures show sufficient enhancement of emission in the case of using the delta-doped cesium layer. The incorporation of cesium is an important way to decrease the threshold voltage of cold cathodes, and in our case the use of a SiO 2 layer allows us to stabilize the emission. copyright 1997 American Vacuum Society

  10. Experimental Demonstration of Anomalous Field Enhancement in All-Dielectric Transition Magnetic Metamaterials.

    Science.gov (United States)

    Sun, Jingbo; Liu, Xiaoming; Zhou, Ji; Kudyshev, Zhaxylyk; Litchinitser, Natalia M

    2015-11-04

    Anomalous field enhancement accompanied by resonant absorption phenomenon was originally discussed in the context of plasma physics and in applications related to radio-communications between the ground and spacecraft returning to Earth. Indeed, there is a critical period of time when all communications are lost due to the reflection/absorption of electromagnetic waves by the sheath of plasma created by a high speed vehicle re-entering the atmosphere. While detailed experimental studies of these phenomena in space are challenging, the emergence of electromagnetic metamaterials enables researchers exceptional flexibility to study them in the laboratory environment. Here, we experimentally demonstrated the strong localized field enhancement of magnetic field for an electromagnetic wave propagating in Mie-resonance-based inhomogeneous metamaterials with magnetic permeability gradually changing from positive to negative values. Although these experiments were performed in the microwave frequency range, the proposed all-dielectric approach to transition metamaterials can be extended to terahertz, infrared, and visible frequencies. We anticipate that these results, besides most basic science aspects, hold the potential for numerous applications, including low-intensity nonlinear transformation optics, topological photonics, and the broader area of surface and interface science.

  11. Near-field enhanced femtosecond laser nano-drilling of glass substrate

    International Nuclear Information System (INIS)

    Zhou, Y.; Hong, M.H.; Fuh, J.Y.H.; Lu, L.; Lukyanchuk, B.S.; Wang, Z.B.

    2008-01-01

    Particle mask assisted near-field enhanced femtosecond laser nano-drilling of transparent glass substrate was demonstrated in this paper. A particle mask was fabricated by self-assembly of spherical 1 μm silica particles on the substrate surface. Then the samples were exposed to femtosecond laser (800 nm, 100 fs) and characterized by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The nano-hole array was found on the glass surface. The hole sizes were measured from 200 to 300 nm with an average depth of 150 nm and increased with laser fluence. Non-linear triple-photon absorption and near-field enhancement were the main mechanisms of the nano-feature formation. Calculations based on Mie theory shows an agreement with experiment results. More debris, however, was found at high laser fluence. This can be attributed to the explosion of silica particles because the focusing point is inside the 1 μm particle. The simulation predicts that the focusing point will move outside the particle if the particle size increases. The experiment performed under 6.84 μm silica particles verified that no debris was formed. And for all the samples, no cracks were found on the substrate surface because of ultra-short pulse width of femtosecond laser. This method has potential applications in nano-patterning of transparent glass substrate for nano-structure device fabrication

  12. Enhanced skin permeation of naltrexone by pulsed electromagnetic fields in human skin in vitro.

    Science.gov (United States)

    Krishnan, Gayathri; Edwards, Jeffrey; Chen, Yan; Benson, Heather A E

    2010-06-01

    The aim of the present study was to evaluate the skin permeation of naltrexone (NTX) under the influence of a pulsed electromagnetic field (PEMF). The permeation of NTX across human epidermis and a silicone membrane in vitro was monitored during and after application of the PEMF and compared to passive application. Enhancement ratios of NTX human epidermis permeation by PEMF over passive diffusion, calculated based on the AUC of cumulative NTX permeation to the receptor compartment verses time for 0-4 h, 4-8 h, and over the entire experiment (0-8 h) were 6.52, 5.25, and 5.66, respectively. Observation of the curve indicated an initial enhancement of NTX permeation compared to passive delivery whilst the PEMF was active (0-4 h). This was followed by a secondary phase after termination of PEMF energy (4-8 h) in which there was a steady increase in NTX permeation. No significant enhancement of NTX penetration across silicone membrane occurred with PEMF application in comparison to passively applied NTX. In a preliminary experiment PEMF enhanced the penetration of 10 nm gold nanoparticles through the stratum corneum as visualized by multiphoton microscopy. This suggests that the channels through which the nanoparticles move must be larger than the 10 nm diameter of these rigid particles. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association

  13. Analysis of near-field components of a plasmonic optical antenna and their contribution to quantum dot infrared photodetector enhancement.

    Science.gov (United States)

    Gu, Guiru; Vaillancourt, Jarrod; Lu, Xuejun

    2014-10-20

    In this paper, we analyze near-field vector components of a metallic circular disk array (MCDA) plasmonic optical antenna and their contribution to quantum dot infrared photodetector (QDIP) enhancement. The near-field vector components of the MCDA optical antenna and their distribution in the QD active region are simulated. The near-field overlap integral with the QD active region is calculated at different wavelengths and compared with the QDIP enhancement spectrum. The x-component (E(x)) of the near-field vector shows a larger intensity overlap integral and stronger correlation with the QDIP enhancement than E(z) and thus is determined to be the major near-field component to the QDIP enhancement.

  14. Photochemical Synthesis of Silver Nanodecahedrons and Related Nanostructures for Plasmonic Field Enhancement Applications

    Science.gov (United States)

    Lu, Haifei

    Noble-metal nanocrystals have received considerable attention in recent years for their size and shape dependent localized surface Plasmon resonances (LSPR). Various applications based on colloidal nanoparticles, such as surface enhanced Raman scattering (SERS), surface enhanced fluorescence (SEF), plasmonic sensing, photothermal therapy etc., have been broadly explored in the field of biomedicine, because of their extremely large optical scattering and absorption cross sections, as well as giant electric field enhancement on their surface. However, despite its high chemical stability, gold exhibits quite large losses and electric field enhancement is comparatively weaker than silver. Silver nanoparticles synthesized by the traditional technique only cover an LSPR ranged from 420~500 nm. On the other hand, the range of 500~660 nm, which is covered by several easily available commercial laser lines, very limited colloidal silver nanostructures with controllable size and shape have been reported, and realization of tuning the resonance to longer wavelengths is very important for the practical applications. In this thesis, a systematic study on photochemical synthesis of silver nanodecahedrons (NDs) and related nanostructures, and their plasmonic field enhancements are presented. First, the roles of chemicals and the light source during the formation of silver nanoparticles have been studied. We have also developed a preparation route for the production size-controlled silver nanodecahedrons (LSPR range 420 ~ 660 nm) in high purity. Indeed our experiments indicate that both the chemicals and the light sources can affect the shape and purity of final products. Adjusting the molar ratio between sodium citrate and silver nitrate can help to control the crystal structure following rapid reduction from sodium borohydride. Light from a blue LED (465 nm) can efficiently transform the polyvinylpyrrolidone stabilized small silver nanoparticles into silver NDs through photo

  15. Enhanced stability of black phosphorus field-effect transistors with SiO₂ passivation.

    Science.gov (United States)

    Wan, Bensong; Yang, Bingchao; Wang, Yue; Zhang, Junying; Zeng, Zhongming; Liu, Zhongyuan; Wang, Wenhong

    2015-10-30

    Few-layer black phosphorus (BP) has attracted much attention due to its high mobility and suitable band gap for potential applic5ations in optoelectronics and flexible devices. However, its instability under ambient conditions limits its practical applications. Our investigations indicate that by passivation of the mechanically exfoliated BP flakes with a SiO2 layer, the fabricated BP field-effect transistors (FETs) exhibit greatly enhanced environmental stability. Compared to the unpassivated BP devices, which show a fast drop of on/off current ratio by a factor of 10 after one week of ambient exposure, the SiO2-passivated BP devices display a high retained on/off current ratio of over 600 after one week of exposure, just a little lower than the initial value of 810. Our investigations provide an effective route to passivate the few-layer BPs for enhancement of their environmental stability.

  16. Energy level splitting and luminescence enhancement in AlN:Er by an external magnetic field

    Science.gov (United States)

    Maqbool, Muhammad; Ahmad, Iftikhar; Ali, Ghafar; Maaz, Khan

    2015-08-01

    Sputter deposited thin film AlN:Er (1 at.%) emits at 554 nm and 561 nm as a result of 2H11/2→ 4I15/2 and 4S3/2→ 4I15/2 transitions under 532 nm NdYAG laser and 783.3 nm crystal laser excitation. An external magnetic field of 0.1 T enhances the green emission and splits the 4S3/2 energy level in two sub-levels with a difference of 0.013 eV. The splitting of energy level produces new emission from Er3+ with a wavelength of 564.5 nm. Infrared emission is also observed at 1552 nm as a result of 4I13/2→ 4I15/2 transition. Enhanced luminescence shows the suitability of Er3+ for high efficiency optical devices.

  17. Nonresonant Local Fields Enhance Second-Harmonic Generation from Metal Nanoislands with Dielectric Cover

    Science.gov (United States)

    Chervinskii, Semyon; Koskinen, Kalle; Scherbak, Sergey; Kauranen, Martti; Lipovskii, Andrey

    2018-03-01

    We study second-harmonic generation from gold nanoislands covered with amorphous titanium oxide (TiO2 ) films. As the TiO2 thickness increases, the plasmon resonance of the nanoislands shifts away from the second-harmonic wavelength of 532 nm, diminishing the resonant enhancement of the process at this wavelength. Nevertheless, the second-harmonic signal is enhanced by up to a factor of 45 with increasing TiO2 thickness. This unexpected effect arises from the scaling of local fields at the fundamental wavelength of 1064 nm—which is at the far tail of the resonance—due to a change in the dielectric environment of the nanoislands.

  18. Core-Shell Magnetic Gold Nanoparticles for Magnetic Field-Enhanced Radio-Photothermal Therapy in Cervical Cancer

    Directory of Open Access Journals (Sweden)

    Rui Hu

    2017-05-01

    Full Text Available The combination of radiotherapy (RT and photothermal therapy (PTT has been considered an attractive strategy in cervical cancer treatment. However, it remains a challenge to simultaneously enhance the radio-sensitivity of tumor tissue, develop tumor tissue-focused radiation therapies and combine dual therapeutic modalities. In this study, core-shell type magnetic gold (Fe3O4@Au nanoparticles are exploited to achieve the synergistic efficacy of radio-photothermal therapy in cervical cancer. Fe3O4@Au nanoparticles (NPs with uniform morphology exhibited superior surface plasmon resonance properties, excellent superparamagnetic properties, good biocompatibility and high photothermal conversion efficiency. For the in vitro tests, a low concentration of Fe3O4@Au NPs after a short period of near-infrared irradiation lead to the time-dependent death of cervical cancer cells. Further, the combination of RT and PTT induced synergistic anti-cancer effects in vitro. More importantly, an external magnetic field could significantly enhance the synergistic efficacy of Fe3O4@Au NPs by improving their internalization. Hence, the reported Fe3O4@Au NPs have the potential to be good nanoagents with excellent magnetic targeting ability for cervical cancer radio-photothermal treatment.

  19. Combining Geoelectrical Measurements and CO2 Analyses to Monitor the Enhanced Bioremediation of Hydrocarbon-Contaminated Soils: A Field Implementation

    Directory of Open Access Journals (Sweden)

    Cécile Noel

    2016-01-01

    Full Text Available Hydrocarbon-contaminated aquifers can be successfully remediated through enhanced biodegradation. However, in situ monitoring of the treatment by piezometers is expensive and invasive and might be insufficient as the information provided is restricted to vertical profiles at discrete locations. An alternative method was tested in order to improve the robustness of the monitoring. Geophysical methods, electrical resistivity (ER and induced polarization (IP, were combined with gas analyses, CO2 concentration, and its carbon isotopic ratio, to develop a less invasive methodology for monitoring enhanced biodegradation of hydrocarbons. The field implementation of this monitoring methodology, which lasted from February 2014 until June 2015, was carried out at a BTEX-polluted site under aerobic biotreatment. Geophysical monitoring shows a more conductive and chargeable area which corresponds to the contaminated zone. In this area, high CO2 emissions have been measured with an isotopic signature demonstrating that the main source of CO2 on this site is the biodegradation of hydrocarbon fuels. Besides, the evolution of geochemical and geophysical data over a year seems to show the seasonal variation of bacterial activity. Combining geophysics with gas analyses is thus promising to provide a new methodology for in situ monitoring.

  20. Piezoelectric Field Enhanced Second-Order Nonlinear Optical Susceptibilities in Wurtzite GaN/AlGaN Quantum Wells

    Science.gov (United States)

    Liu, Ansheng; Chuang, S.-L.; Ning, C. Z.; Woo, Alex (Technical Monitor)

    1999-01-01

    Second-order nonlinear optical processes including second-harmonic generation, optical rectification, and difference-frequency generation associated with intersubband transitions in wurtzite GaN/AlGaN quantum well (QW) are investigated theoretically. Taking into account the strain-induced piezoelectric (PZ) effects, we solve the electronic structure of the QW from coupled effective-mass Schrodinger equation and Poisson equation including the exchange-correlation effect under the local-density approximation. We show that the large PZ field in the QW breaks the symmetry of the confinement potential profile and leads to large second-order susceptibilities. We also show that the interband optical pump-induced electron-hole plasma results in an enhancement in the maximum value of the nonlinear coefficients and a redshift of the peak position in the nonlinear optical spectrum. By use of the difference-frequency generation, THz radiation can be generated from a GaN/Al(0.75)Ga(0.25)N with a pump laser of 1.55 micron.

  1. Enhanced solid-state order and field-effect hole mobility through control of nanoscale polymer aggregation

    KAUST Repository

    Chen, Mark S.

    2013-12-26

    Efficient charge carrier transport in organic field-effect transistors (OFETs) often requires thin films that display long-range order and close π-π packing that is oriented in-plane with the substrate. Although some polymers have achieved high field-effect mobility with such solid-state properties, there are currently few general strategies for controlling the orientation of π-stacking within polymer films. In order to probe structural effects on polymer-packing alignment, furan-containing diketopyrrolopyrrole (DPP) polymers with similar optoelectronic properties were synthesized with either linear hexadecyl or branched 2-butyloctyl side chains. Differences in polymer solubility were observed and attributed to variation in side-chain shape and polymer backbone curvature. Averaged field-effect hole mobilities of the polymers range from 0.19 to 1.82 cm2/V·s, where PDPP3F-C16 is the least soluble polymer and provides the highest maximum mobility of 2.25 cm2/V·s. Analysis of the films by AFM and GIXD reveal that less soluble polymers with linear side chains exhibit larger crystalline domains, pack considerably more closely, and align with a greater preference for in-plane π-π packing. Characterization of the polymer solutions prior to spin-coating shows a correlation between early onset nanoscale aggregation and the formation of films with highly oriented in-plane π-stacking. This effect is further observed when nonsolvent is added to PDPP3F-BO solutions to induce aggregation, which results in films with increased nanostructural order, in-plane π-π orientation, and field-effect hole mobilities. Since nearly all π-conjugated materials may be coaxed to aggregate, this strategy for enhancing solid-state properties and OFET performance has applicability to a wide variety of organic electronic materials. © 2013 American Chemical Society.

  2. Field-induced phase diagram of the XY pyrochlore antiferromagnet Er2Ti2O7

    Science.gov (United States)

    Lhotel, E.; Robert, J.; Ressouche, E.; Damay, F.; Mirebeau, I.; Ollivier, J.; Mutka, H.; Dalmas de Réotier, P.; Yaouanc, A.; Marin, C.; Decorse, C.; Petit, S.

    2017-04-01

    We explore the field-temperature phase diagram of the XY pyrochlore antiferromagnet Er2Ti2O7 by means of magnetization and neutron diffraction experiments. Depending on the field strength and direction relative to the high symmetry cubic directions [001 ],[1 1 ¯0 ] , and [111 ] , the refined field-induced magnetic structures are derived from the zero field ψ2 and ψ3 states of the Γ5 irreducible representation which describes the ground state of XY pyrochlore antiferromagnets. At low field, domain selection effects are systematically at play. In addition, for [001 ] , a phase transition is reported towards a ψ3 structure at a characteristic field Hc001=43 mT. For [1 1 ¯0 ] and [111 ] , the spins are continuously tilted by the field from the ψ2 state, and no phase transition is found while domain selection gives rise to sharp anomalies in the field dependence of the Bragg peaks intensity. For [1 1 ¯0 ] , these results are confirmed by high resolution inelastic neutron scattering experiments, which in addition allow us to determine the field dependence of the spin gap. This study agrees qualitatively with the scenario proposed theoretically by Maryasin et al. [Phys. Rev. B 93, 100406(R) (2016), 10.1103/PhysRevB.93.100406], yet the strength of the field-induced anisotropies is significantly different from theory.

  3. A novel serine protease secreted by medicinal maggots enhances plasminogen activator-induced fibrinolysis

    DEFF Research Database (Denmark)

    van der Plas, Mariena J A; Andersen, Anders S; Nazir, Sheresma

    2014-01-01

    . Recombinant Sericase degraded plasminogen leading amongst others to the formation of the mini-plasminogen like fragment Val454-plasminogen. In addition, the presence of a non-proteolytic cofactor in secretions was discovered, which plays a role in the enhancement of plasminogen activator-induced fibrinolysis...

  4. The enhanced interface effect induced by thermal pressure in Nd0 ...

    Indian Academy of Sciences (India)

    The enhanced interface effect induced by thermal pressure in. Nd0.7Sr0.3MnOy ceramics. SHUNSHENG CHEN1,2, DAWEI SHI2, SHAOZHEN LI1, CHANGPING YANG2,∗ and. YALI ZHANG3. 1Institute for Quantum Materials and School of Mathematics and Physics, Hubei Polytechnic University,. Huangshi 435003, PR ...

  5. Prolonged local forearm hyperinsulinemia induces sustained enhancement of nitric oxide-dependent vasodilation in healthy subjects

    DEFF Research Database (Denmark)

    Hermann, Thomas S; Ihlemann, Nikolaj; Dominguez, Helena

    2005-01-01

    -dependent and -independent vasodilation.N(G)-monomethyl-L-arginine (L-NMMA) was coinfused to test the degree of nitric oxide (NO)-mediated vasodilation. Insulin infusion for 60 min enhanced serotonin-induced vasodilation by 37% compared to vehicle, p = .016. This increase was maintained for 4 h and was blocked by L...

  6. Persistent wind-induced enhancement of diffusive CO2 transport in a mountain forest snowpack

    Science.gov (United States)

    D. R. Bowling; W. J. Massman

    2011-01-01

    Diffusion dominates the transport of trace gases between soil and the atmosphere. Pressure gradients induced by atmospheric flow and wind interacting with topographical features cause a small but persistent bulk flow of air within soil or snow. This forcing, called pressure pumping or wind pumping, leads to a poorly quantified enhancement of gas transport beyond the...

  7. Enhancing the Employability of Chinese International Students: Identifying Achievements and Gaps in the Research Field

    Directory of Open Access Journals (Sweden)

    Xuemeng Cao

    2017-10-01

    Full Text Available This article shows what achievements have been made by existing studies on graduate employability, and what gaps need to be filled in this field. It starts with a retrospective account of the changing concept of employability, followed by a presentation of the practices that have been used to support graduate employability enhancement in different countries. Moreover, this article gives a critical review of Chinese contexts of graduate labour market. Last but not least, limitations of existing studies are identified, which reflect an expectation for future research on graduate employability to meet the demand of an increasingly international dimension of higher education.

  8. Fiber-optic surface-enhanced Raman system for field screening of hazardous compounds

    International Nuclear Information System (INIS)

    Ferrell, T.L.; Goudonnet, J.P.; Arakawa, E.T.; Reddick, R.C.; Gammage, R.B.; Haas, J.W.; James, D.R.; Wachter, E.A.

    1988-01-01

    Surface-enhanced Raman scattering permits identification of compounds adsorbed onto a metal microbase that is microlithographically produced with submicron resolution. Less than one percent of a monolayer of a Raman Active target compound offers a high signal-to-noise ratio. By depositing the microbase on the exterior of a fiber optic cable, convenient field screening or monitoring is permitted. By using highly effective microbases, it is possible to reduce laser power requirements sufficiently to allow an economical, but complete, system to be housed in a suitcase. We shall present details of SERS system of this type and shall show data on samples of interest in the screening of hazardous compounds

  9. Two-photon luminescence microscopy of field enhancement at gold nanoparticles

    DEFF Research Database (Denmark)

    Beermann, Jonas; Bozhevolnyi, Sergey I.

    2005-01-01

    Using a reflection scanning optical microscope detecting two-photon luminescence (TPL) we have imaged square gold bumps positioned in a periodic array either on a smooth gold film or directly on a glass substrate. The second-harmonic (SH) and TPL response from these structures show both...... polarization and wavelength dependence. The gold bumps on gold film showed extremely high sensitivity to the incident field, with the strongest TPL response from the gold bumps being enhanced nearly 103 times compared to the TPL response from the smooth gold surface. For gold bumps directly on glass...

  10. Growth inhibition of Staphylococcus aureus induced by low-frequency electric and electromagnetic fields.

    Science.gov (United States)

    Obermeier, Andreas; Matl, Florian Dominik; Friess, Wolfgang; Stemberger, Axel

    2009-05-01

    Magnetic field therapy is an established technique in the treatment of pseudarthrosis. In cases of osteomylitis, palliation is also observed. This study focuses on the impact of different electric and electromagnetic fields on the growth of Staphylococcus aureus by in vitro technologies. Cultures of Staphylococcus aureus in fluid and gel-like medium were exposed to a low-frequency electromagnetic field, an electromagnetic field combined with an additional electric field, a sinusoidal electric field and a static electric field. In gel-like medium no significant difference between colony-forming units of exposed samples and non-exposed references was detected. In contrast, Staphylococcus aureus concentrations in fluid medium could clearly be reduced under the influence of the four different applied fields within 24 h of experiment. The strongest effects were observed for the direct current electric field which could decrease CFU/ml of 37%, and the low-frequency electromagnetic field with additional induced electric alternating field with a decrease of Staphylococci concentration by 36%. The effects of the electromagnetic treatment on Staphylococci within fluid medium are significantly higher than in gel-like medium. The application of low-frequency electromagnetic fields corroborates clinical situations of bone infections during magnetic field therapy. Copyright 2009 Wiley-Liss, Inc.

  11. Enhanced heat transfer in partially open square cavities with thin fin by using electric field

    International Nuclear Information System (INIS)

    Kasayapanand, N.; Kiatsiriroat, T.

    2009-01-01

    Numerical modeling of the electric field effect on the natural convection in the partially open square cavities with thin fin attached is investigated. The interactions among electric, flow, and temperature fields are analyzed by using a computational fluid dynamics technique. It is found that the flow and heat transfer enhancements are a decreasing function of the Rayleigh number. Moreover, the volume flow rate and heat transfer coefficient are substantially improved by electrohydrodynamic especially at low aperture size, high aperture position, and high inclined angle. Surprisingly, the maximum convective heat transfer is obtained at the minimum electrical energy consumption by placing electrodes at a suitable position. The optimum electrode arrangements for both single fin and multiple fins are also achieved

  12. Beam Dynamics Simulations of Optically-Enhanced Field Emission from Structured Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Seymour, A. [Northern Illinois U.; Grote, D. [LLNL, Livermore; Mihalcea, D. [Northern Illinois U.; Piot, P. [Fermilab; Vay, J.-L. [LBNL, Berkeley

    2014-01-01

    Structured cathodes - cathodes with a segmented emission surface - are finding an increasing number of applications and can be combined with a variety of emission mechanisms, including photoemission and field emission. These cathodes have been used to enhance the quantum efficiency of metallic cathodes when operated as plasmonic cathodes, have produced high-current electron bunches though field emission from multiple tips, and can be used to form beams with transverse segmentations necessary for improving the performance of accelerator-based light sources. In this report we present recent progress towards the development of finite-difference time-domain particle-in-cell simulations using the emission process in structured cathodes based on the WARP framework. The simulations give further insight on the localized source of the emitted electrons which could be used for additional high-fidelity start-to-end simulations of electron accelerators that employ this type of electron source.

  13. Yohimbine enhances protection of berberine against LPS-induced mouse lethality through multiple mechanisms.

    Directory of Open Access Journals (Sweden)

    Hui Li

    Full Text Available Sepsis remains a major cause of mortality in intensive care units, better therapies are urgently needed. Gram-negative bacterial lipopolysaccharide (LPS is an important trigger of sepsis. We have demonstrated that berberine (Ber protects against lethality induced by LPS, which is enhanced by yohimbine (Y pretreatment, and Ber combined with Y also improves survival in septic mice. However, the precise mechanisms by which Y enhances protection of Ber against LPS-induced lethality remain unclear. The present study confirmed that simultaneously administered Y also enhanced protection of Ber against LPS-induced lethality. Ber or/and Y attenuated liver injury, but not renal injury in LPS-challenged mice. Ber or/and Y all inhibited LPS-stimulated IκBα, JNK and ERK phosphorylation, NF-κB activation as well as TNF-α production. Ber also increased IL-10 production in LPS-challenged mice, which was enhanced by Y. Furthermore, Ber or/and Y all suppressed LPS-induced IRF3, TyK2 and STAT1 phosphorylation, as well as IFN-β and IP-10 mRNA expression in spleen of mice at 1 h after LPS challenge. Especially, Y enhanced the inhibitory effect of Ber on LPS-induced IP-10 mRNA expression. In vitro experiments further demonstrated that Y significantly enhanced the inhibitory effect of Ber on TNF-α production in LPS-treated peritoneal macrophages, Ber combined with Y promoted LPS-induced IL-10 production and LPS-stimulated IκBα, JNK, ERK and IRF3 phosphorylation and NF-κB activation were also suppressed by Ber or/and Y pretreatment in peritoneal macrophages. Taken together, these results demonstrate that Y enhances the protection of Ber against LPS-induced lethality in mice via attenuating liver injury, upregulating IL-10 production and suppressing IκBα, JNK, ERK and IRF3 phosphorylation. Ber combined with Y may be an effective immunomodulator agent for the prevention of sepsis.

  14. C-reactive protein enhances the respiratory burst of neutrophils-induced by antineutrophil cytoplasmic antibody.

    Science.gov (United States)

    Xu, Peng-cheng; Hao, Jian; Yang, Xiao-wei; Chang, Dong-yuan; Chen, Min; Zhao, Ming-hui

    2012-10-01

    Serum C-reactive protein (CRP) was one of the useful biomarkers for evaluating the disease activity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Cumulating studies proved that CRP was pathogenic in a variety of diseases. In the current study, the in vitro effects of CRP to prime neutrophils for ANCA-induced respiratory burst were investigated with flow cytometry. Without TNF-α in the reactive system, ANCA could only induce a slight level of respiratory burst of neutrophils. CRP could enhance the respiratory burst of neutrophils induced by ANCA against myeloperoxidse [mean fluorescence intensity (MFI, 68.45 ± 16.87 vs. 58.65 ± 15.09, P Heat-treated CRP could not enhance the levels of neutrophils respiratory burst induced by ANCA or increase the expression of membrane proteinase 3 of neutrophils. So CRP can prime neutrophils and enhance the respiratory burst induced by ANCA and might be pathogenic in AAV. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Placement of field probes for stabilization of breathing-induced B0-fluctuations in the brain

    DEFF Research Database (Denmark)

    Andersen, Mads; Madsen, Kristoffer H.; Hanson, Lars G.

    Introduction: B0-fluctuations induced by breathing and body motion lead to artifacts for certain brain imaging sequences at ultra-high field (7T). A promising solution is to monitor the B0-fluctuations during the scan using external field probes, and update the shim currents in real-time (1...... for these spatial terms are determined by least square fitting to the field probe measurements. The probes must be placed carefully to ensure that the spherical harmonics can be distinguished using these few samples, and they must be placed close to the head so that the spatial field model is valid and to have good...

  16. Placement of field probes for stabilization of breathing-induced B0-fluctuations in the brain

    DEFF Research Database (Denmark)

    Andersen, Mads; Madsen, Kristoffer H; Hanson, L.G.

    2015-01-01

    Introduction: B0-fluctuations induced by breathing and body motion lead to artifacts for certain brain imaging sequences at ultra-high field (7T). A promising solution is to monitor the B0-fluctuations during the scan using external field probes, and update the shim currents in real-time (1...... for these spatial terms are determined by least square fitting to the field probe measurements. The probes must be placed carefully to ensure that the spherical harmonics can be distinguished using these few samples, and they must be placed close to the head so that the spatial field model is valid and to have good...

  17. [GSM 1,800 MHz radiofrequency electromagnetic fields induced clustering of membrane surface receptors and interference by noise magnetic fields].

    Science.gov (United States)

    Xie, Liang; jiang, Huai; Sun, Wen-jun; Fu, Yi-ti; Lu, De-qiang

    2006-08-01

    To investigate the possible effect of exposure to GSM 1,800 MHz radiofrequency electromagnetic fields (RF EMF) on epidermal growth factor (EGF) receptor and its possible interference by noise magnetic fields (MF). Chinese hamster lung fibroblasts (CHL) were exposed to 1,800 MHz RF EMF (modulated by 217 Hz or 50 Hz, or unmodulated), 2 microT noise MF, and RF EMF combined with 2 microT noise MF for 15 min, respectively. The specific absorption rates (SARs) of RF EMF were 0.1, 0.5, 1.0, 2.0 and 4.0 W/kg. Commercial EGF (1 ng/ml) treatment was used as positive control. EGF receptors on the cell membrane were observed under a laser scanning confocal microscope after indirect immunofluorescence staining. EGF receptor clustering was induced after exposure to GSM 1,800 MHz RF EMF modulated by 217 Hz or 50 Hz MF at SARs of 0.5, 1.0, 2.0, 4.0 W/kg for 15 min as induced by 1 ng/ml EGF, but not at SAR of 0.1 W/kg. And no EGF receptor clustering was found in cells after exposure to unmodulated RF EMF or 2 microT noise MF. In addition, superposition of 2 microT noise MF could inhibit the EGF receptor clustering induced by GSM 1,800 MHz RF EMF. EGF receptor clustering in CHL cells can be induced by GSM 1,800 MHz RF EMF at the lowest SAR of 0.5 W/kg and inhibited by noise MF. The modulation of wave may play an important role in the inducement of receptor clustering after RF exposure.

  18. Loss-induced Enhanced Transmission in Anisotropic Density-near-zero Acoustic Metamaterials.

    Science.gov (United States)

    Shen, Chen; Jing, Yun

    2016-11-25

    Anisotropic density-near-zero (ADNZ) acoustic metamaterials are investigated theoretically and numerically in this paper and are shown to exhibit extraordinary transmission enhancement when material loss is induced. The enhanced transmission is due to the enhanced propagating and evanescent wave modes inside the ADNZ medium thanks to the interplay of near-zero density, material loss, and high wave impedance matching in the propagation direction. The equi-frequency contour (EFC) is used to reveal whether the propagating wave mode is allowed in ADNZ metamaterials. Numerical simulations based on plate-type acoustic metamaterials with different material losses were performed to demonstrate collimation and subwavelength imaging enabled by the induced loss in ADNZ media. This work provides a different way for manipulating acoustic waves.

  19. Gamma radiation induced enhancement in the antioxidant and radioprotective activities of flavonoids

    International Nuclear Information System (INIS)

    Arul Anantha Kumar, A.; Sonwani, Swetha; Bakkiam, D.

    2018-01-01

    Recently γ-radiation has been used as a tool to induce structural changes in natural biomolecules to enhance their biological and physiological properties. Flavonoids are a family of plant derived polyphenolic compounds having considerable scientific and therapeutic importance. Structurally they are the benzo-γ-pyrone derivatives containing phenolic and pyrane rings. Flavonoid radioprotection is an intense area of research thanks to features like natural origin, effectiveness at non-toxic dose levels and lack of side effects. But till date no report is available on the effect of γ-radiation mediated enhancement in radioprotection activity of flavonoids. In view of this the present study was carried out to determine the γ-radiation induced structural changes in selected flavonoids i.e. apigenin, naringenin and genistein and also to explore the possibility of enhancement in their antioxidant and radioprotective activities

  20. Real-time observations of mechanical stimulus-induced enhancements of mechanical properties in osteoblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xu; Liu Xiaoli; Sun Jialun [State Key Laboratory of Bioactive Materials, School of Physics, Nankai University, Tianjin 300073 (China); He Shuojie [State Key Laboratory of Bioactive Materials, School of Physics, Nankai University, Tianjin 300073 (China); Department of Physics, Pusan National University, Pusan (Korea, Republic of); Lee, Imshik [State Key Laboratory of Bioactive Materials, School of Physics, Nankai University, Tianjin 300073 (China)], E-mail: ilee@nankai.edu.cn2; Pak, Hyuk Kyu [Department of Physics, Pusan National University, Pusan (Korea, Republic of)

    2008-09-15

    Osteoblast, playing a key role in the pathophysiology of osteoporosis, is one of the mechanical stress sensitive cells. The effects of mechanical load-induced changes of mechanical properties in osteoblast cells were studied at real-time. Osteoblasts obtained from young Wister rats were exposed to mechanical loads in different frequencies and resting intervals generated by atomic force microscopy (AFM) probe tip and simultaneously measured the changes of the mechanical properties by AFM. The enhancement of the mechanical properties was observed and quantified by the increment of the apparent Young's modulus, E{sup *}. The observed mechanical property depended on the frequency of applied tapping loads. For the resting interval is 50 s, the mechanical load-induced enhancement of E{sup *}-values disappears. It seems that the enhanced mechanical property was recover able under no additional mechanical stimulus.

  1. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zevenhoven, Koos C. J., E-mail: koos.zevenhoven@aalto.fi; Ilmoniemi, Risto J. [Department of Neuroscience and Biomedical Engineering, School of Science, Aalto University, P.O. Box 12200, FI-00076 AALTO (Finland); Dong, Hui [Department of Physics, University of California, Berkeley, California 94708-7300 (United States); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Clarke, John [Department of Physics, University of California, Berkeley, California 94708-7300 (United States)

    2015-01-19

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents.

  2. Modeling and characterization of field-enhanced corona discharge in ozone-generator diode

    Science.gov (United States)

    Patil, Jagadish G.; Vijayan, T.

    2010-02-01

    Electric field enhanced corona plasma discharge in ozone generator diode of axial symmetry has been investigated and characterized in theory. The cathode K of diode is made of a large number of sharpened nozzles arranged on various radial planes on the axial mast and pervaded in oxygen gas inside the anode cup A, produces high fields over MV/m and aids in the formation of a corona plume of dense ozone cloud over the cathode surface. An r-z finite difference scheme has been devised and employed to numerically determine the potential and electric field distributions inside the diode. The analyses of cathode emissions revealed a field emission domain conformed to modified Child-Langmuir diode-current. Passage of higher currents (over μA) in shorter A-K gaps d gave rise to cathode heated plasma extending from the corona to Saha regimes depending on local temperature. Plasma densities of order 102-106 m-3 are predicted in these. For larger d however, currents are smaller and heating negligible and a negative corona favoring ozone formation is attained. High ozone yields about 20 per cent of oxygen input is predicted in this domain. The generator so developed will be applied to various important applications such as, purification of ambient air /drinking water, ozone therapy, and so on.

  3. Modeling and characterization of field-enhanced corona discharge in ozone-generator diode

    International Nuclear Information System (INIS)

    Patil, Jagadish G; Vijayan, T

    2010-01-01

    Electric field enhanced corona plasma discharge in ozone generator diode of axial symmetry has been investigated and characterized in theory. The cathode K of diode is made of a large number of sharpened nozzles arranged on various radial planes on the axial mast and pervaded in oxygen gas inside the anode cup A, produces high fields over MV/m and aids in the formation of a corona plume of dense ozone cloud over the cathode surface. An r-z finite difference scheme has been devised and employed to numerically determine the potential and electric field distributions inside the diode. The analyses of cathode emissions revealed a field emission domain conformed to modified Child-Langmuir diode-current. Passage of higher currents (over μA) in shorter A-K gaps d gave rise to cathode heated plasma extending from the corona to Saha regimes depending on local temperature. Plasma densities of order 10 2 -10 6 m -3 are predicted in these. For larger d however, currents are smaller and heating negligible and a negative corona favoring ozone formation is attained. High ozone yields about 20 per cent of oxygen input is predicted in this domain. The generator so developed will be applied to various important applications such as, purification of ambient air /drinking water, ozone therapy, and so on.

  4. Nanostructure enhanced near-field radiative heat transfer and designs for energy conversion devices

    Science.gov (United States)

    Wang, Bingnan; Lin, Chungwei; Teo, Koon Hoo

    2017-09-01

    Near-field radiative heat transfer can exceed the blackbody limit, and this property has been explored toward energy transfer and conversion applications, such as thermophtovoltaic (TPV) devices, radiative cooling devices, and thermoradiative (TR) devices. The coupling of resonant modes between two surfaces is important in near- field heat transfer and near-field TPV and TR systems. It was shown that the coupling of resonant modes enhances the transmissivity between two coupled objects, which further determines the radiative heat transfer and energy conversion. Surface plasmon polaritons (SPPs), which are surface resonances existing on metal surfaces, are commonly used for such systems. While the frequency of SPP resonance is fixed for a planar emitter, a nanostructured emitter supports additional resonances such as SPP or cavity modes with lower frequencies that are closer to the bandgap energy of a typical PV cell. We show that the nanostructured designs significantly improves the near-field radiative power transfer, and electric power output for a TR system.

  5. Stratigraphy of Citronelle Oil Field, AL: Perspectives from Enhanced Oil Recovery and Potential CO2 Sequestration

    Science.gov (United States)

    Hills, D. J.; Pashin, J. C.; Kopaska-Merkel, D. C.; Esposito, R. A.

    2008-12-01

    The Citronelle Dome is a giant salt-cored anticline in the eastern Mississippi Interior Salt Basin of south Alabama. The dome forms an elliptical structural closure containing multiple opportunities for enhanced oil recovery (EOR) and large-capacity saline reservoir CO2 sequestration. The Citronelle Oil Field, which is on the crest of the dome, has produced more than 168 MMbbl of 42° gravity oil from marginal marine sandstone in the Lower Cretaceous Donovan Sand. Recently, EOR field tests have begun in the northeastern part of the oil field. Citronelle Unit B-19-10 #2 well (Alabama State Oil and Gas Board Permit No. 3232) will serve as the CO2 injector for the first field test. CO2 will be injected into the Upper Donovan 14-1 and 16-2 sandstone units. All well logs in the 4-square-mile area surrounding the test site have been digitized and used to construct a network of nineteen stratigraphic cross sections correlating Sands 12 through 20A in the Upper Donovan. Detailed study of Citronelle cores has shown that depositional environments in the Donovan Sand differed significantly from the earlier model that has guided past development of the Citronelle Field. The cross sections demonstrate the extreme facies heterogeneity of the Upper Donovan, and this heterogeneity is well expressed within the five-spot well pattern where the field test will be conducted. Many other features bearing on the performance of the CO2 injection test have been discovered. Of particular interest is the 16-2 sand, which is interpreted as a composite of two tiers of channel fills. Pay strata are typically developed in the lower tier, and this is where CO2 will be injected. The upper tier is highly heterogeneous and is interpreted to contain sandstone fills of variable reservoir quality, as well as mudstone plugs.

  6. Magnetism and high magnetic-field-induced stability of alloy carbides in Fe-based materials.

    Science.gov (United States)

    Hou, T P; Wu, K M; Liu, W M; Peet, M J; Hulme-Smith, C N; Guo, L; Zhuang, L

    2018-02-14

    Understanding the nature of the magnetic-field-induced precipitation behaviors represents a major step forward towards unravelling the real nature of interesting phenomena in Fe-based alloys and especially towards solving the key materials problem for the development of fusion energy. Experimental results indicate that the applied high magnetic field effectively promotes the precipitation of M 23 C 6 carbides. We build an integrated method, which breaks through the limitations of zero temperature and zero external field, to concentrate on the dependence of the stability induced by the magnetic effect, excluding the thermal effect. We investigate the intimate relationship between the external field and the origins of various magnetics structural characteristics, which are derived from the interactions among the various Wyckoff sites of iron atoms, antiparallel spin of chromium and Fe-C bond distances. The high-magnetic-field-induced exchange coupling increases with the strength of the external field, which then causes an increase in the parallel magnetic moment. The stability of the alloy carbide M 23 C 6 is more dependent on external field effects than thermal effects, whereas that of M 2 C, M 3 C and M 7 C 3 is mainly determined by thermal effects.

  7. Ability of vaccine strain induced antibodies to neutralize field isolates of caliciviruses from Swedish cats.

    Science.gov (United States)

    Wensman, Jonas Johansson; Samman, Ayman; Lindhe, Anna; Thibault, Jean-Christophe; Berndtsson, Louise Treiberg; Hosie, Margaret J

    2015-12-12

    Feline calicivirus (FCV) is a common cause of upper respiratory tract disease in cats worldwide. Its characteristically high mutation rate leads to escape from the humoral immune response induced by natural infection and/or vaccination and consequently vaccines are not always effective against field isolates. Thus, there is a need to continuously investigate the ability of FCV vaccine strain-induced antibodies to neutralize field isolates. Seventy-eight field isolates of FCV isolated during the years 2008-2012 from Swedish cats displaying clinical signs of upper respiratory tract disease were examined in this study. The field isolates were tested for cross-neutralization using a panel of eight anti-sera raised in four pairs of cats following infection with four vaccine strains (F9, 255, G1 and 431). The anti-sera raised against F9 and 255 neutralised 20.5 and 11.5 %, and 47.4 and 64.1 % of field isolates tested, respectively. The anti-sera against the more recently introduced vaccine strains G1 and 431 neutralized 33.3 and 55.1 % (strain G1) or 69.2 and 89.7 % (strain 431) of the field isolates with titres ≥5. [corrected]. Dual vaccine strains displayed a higher cross-neutralization. This study confirms previous observations that more recently introduced vaccine strains induce antibodies with a higher neutralizing capacity compared to vaccine strains that have been used extensively over a long period of time. This study also suggests that dual FCV vaccine strains might neutralize more field isolates compared to single vaccine strains. Vaccine strains should ideally be selected based on updated knowledge on the antigenic properties of field isolates in the local setting, and there is thus a need for continuously studying the evolution of FCV together with the neutralizing capacity of vaccine strain induced antibodies against field isolates at a national and/or regional level.

  8. Effects of coil orientation on the electric field induced by TMS over the hand motor area

    International Nuclear Information System (INIS)

    Laakso, Ilkka; Hirata, Akimasa; Ugawa, Yoshikazu

    2014-01-01

    Responses elicited by transcranial magnetic stimulation (TMS) over the hand motor area depend on the position and orientation of the stimulating coil. In this work, we computationally investigate the induced electric field for multiple coil orientations and locations in order to determine which parts of the brain are affected and how the sensitivity of motor cortical activation depends on the direction of the electric field. The finite element method is used for calculating the electric field induced by TMS in two individual anatomical models of the head and brain. The orientation of the coil affects both the strength and depth of penetration of the electric field, and the field strongly depends on the direction of the sulcus, where the target neurons are located. The coil position that gives the strongest electric field in the target cortical region may deviate from the closest scalp location by a distance on the order of 1 cm. Together with previous experimental data, the results support the hypothesis that the cortex is most sensitive to fields oriented perpendicular to the cortical layers, while it is relatively insensitive to fields parallel to them. This has important implications for targeting of TMS. To determine the most effective coil position and orientation, it is essential to consider both biological (the direction of the targeted axons) and physical factors (the strength and direction of the electric field). (paper)

  9. Magnetic-field induced semimetal in topological crystalline insulator thin films

    International Nuclear Information System (INIS)

    Ezawa, Motohiko

    2015-01-01

    We investigate electromagnetic properties of a topological crystalline insulator (TCI) thin film under external electromagnetic fields. The TCI thin film is a topological insulator indexed by the mirror-Chern number. It is demonstrated that the gap closes together with the emergence of a pair of gapless cones carrying opposite chirarities by applying in-plane magnetic field. A pair of gapless points have opposite vortex numbers. This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. We thus present an a magnetic-field induced semimetal–semiconductor transition in 2D material. This is a giant-magnetoresistance, where resistivity is controlled by magnetic field. Perpendicular electric field is found to shift the gapless points and also renormalize the Fermi velocity in the direction of the in-plane magnetic field. - Highlights: • The band structure of topological crystalline insulator thin films can be controlled by applying in-plane magnetic field. • At the gap closing magnetic field, a pair of gapless cones carrying opposite chirarities emerge. • A pair of gapless points have opposite vortex numbers. • This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. • A magnetic-field induced semimetal–semiconductor transition occurs in 2D material

  10. Magnetic-field induced semimetal in topological crystalline insulator thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ezawa, Motohiko, E-mail: ezawa@ap.t.u-tokyo.ac.jp

    2015-06-19

    We investigate electromagnetic properties of a topological crystalline insulator (TCI) thin film under external electromagnetic fields. The TCI thin film is a topological insulator indexed by the mirror-Chern number. It is demonstrated that the gap closes together with the emergence of a pair of gapless cones carrying opposite chirarities by applying in-plane magnetic field. A pair of gapless points have opposite vortex numbers. This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. We thus present an a magnetic-field induced semimetal–semiconductor transition in 2D material. This is a giant-magnetoresistance, where resistivity is controlled by magnetic field. Perpendicular electric field is found to shift the gapless points and also renormalize the Fermi velocity in the direction of the in-plane magnetic field. - Highlights: • The band structure of topological crystalline insulator thin films can be controlled by applying in-plane magnetic field. • At the gap closing magnetic field, a pair of gapless cones carrying opposite chirarities emerge. • A pair of gapless points have opposite vortex numbers. • This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. • A magnetic-field induced semimetal–semiconductor transition occurs in 2D material.

  11. Effects of Pulsed Electric Field (PEF) Treatment on Enhancing Activity and Conformation of α-Amylase.

    Science.gov (United States)

    Tian, Mei-ling; Fang, Ting; Du, Mu-ying; Zhang, Fu-sheng

    2016-04-01

    To explore an efficient, safe, and speedy application of pulsed electric field (PEF) technology for enzymatic modification, effects of PEF treatment on the enzymatic activity, property and kinetic parameters of α-amylase were investigated. Conformational transitions were also studied with the aid of circular dichroism (CD) and fluorescence spectra. The maximum enzymatic activity of α-amylase was obtained under 15 kV/cm electric field intensity and 100 mL/min flow velocity PEF treatment, in which the enzymatic activity increased by 22.13 ± 1.14% compared with control. The activation effect could last for 18 h at 4 °C. PEF treatment could widen the range of optimum temperature for α-amylase, however, it barely exerted any effect on the optimum pH. On the other hand, α-amylase treated by PEF showed an increase of Vmax, t1/2 and ΔG, whereas a decrease of Km and k were observed. Furthermore, it can be observed from fluorescence and CD spectra that PEF treatment had increased the number of amino acid residues, especially that of tryptophan, on α-amylase surface with enhanced α-helices by 34.76% and decreased random coil by 12.04% on α-amylase when compared with that of untreated. These changes in structure had positive effect on enhancing α-amylase activity and property.

  12. Contracts for field projects and supporting research on enhanced oil recovery. Progress review No. 78, quarter ending March 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-05-01

    This report presents descriptions of various research projects and field projects concerned with the enhanced recovery of petroleum. Contract numbers, principal investigators, company names, and project management information is included.

  13. Gadodiamide injection for enhancement of MRI in the CNS. Applications, dose, field and time dependence

    International Nuclear Information System (INIS)

    Aakeson, P.

    1996-01-01

    Gadodiamide injection was comparable to Gd-DTPA with regard to both safety and diagnostic efficiency in the central nervous system. The contrast effect of Gd contrast agents is higher at 1.5 T than at 0.3 T both in phantoms and patients with a maximum ratio (signal lesion/signal grey matter) more than 50% higher at 1.5 T. To achieve high contrast effect, heavily T1-weighted images are important. Prolonging the TR from 400 ms to 600 ms reduced the ratio by 15-45% depending on concentration. The effective time window for imaging of BBB (Blood-Brain Barrier) damage is between 2-5 and 25-30 minutes after injection and several scans can be performed without loss of enhancement. To provide maximum detectability of BBB damage in patients, higher doses of Gd contrast media should be useful, especially at low field strengths, as the doses used clinically today do not utilize the maximum contrast effect. High-dose (0.3 mmol/kg b.w.) contrast enhanced MRI (0.3 T) with Gadodiamide injection allowed detection of significantly more and smaller metastases (i.e. BBB damage) than standard dose (0.1 mmol/kg b.w.) High dose contrast-enhanced MRI (0.3 T) did not increase the diagnostic information for the evaluation of patients with failed back surgery syndrome compared to standard dose MRI. 55 refs, 9 figs, 10 tabs

  14. Gadodiamide injection for enhancement of MRI in the CNS. Applications, dose, field and time dependence

    Energy Technology Data Exchange (ETDEWEB)

    Aakeson, P.

    1996-10-01

    Gadodiamide injection was comparable to Gd-DTPA with regard to both safety and diagnostic efficiency in the central nervous system. The contrast effect of Gd contrast agents is higher at 1.5 T than at 0.3 T both in phantoms and patients with a maximum ratio (signal lesion/signal grey matter) more than 50% higher at 1.5 T. To achieve high contrast effect, heavily T1-weighted images are important. Prolonging the TR from 400 ms to 600 ms reduced the ratio by 15-45% depending on concentration. The effective time window for imaging of BBB (Blood-Brain Barrier) damage is between 2-5 and 25-30 minutes after injection and several scans can be performed without loss of enhancement. To provide maximum detectability of BBB damage in patients, higher doses of Gd contrast media should be useful, especially at low field strengths, as the doses used clinically today do not utilize the maximum contrast effect. High-dose (0.3 mmol/kg b.w.) contrast enhanced MRI (0.3 T) with Gadodiamide injection allowed detection of significantly more and smaller metastases (i.e. BBB damage) than standard dose (0.1 mmol/kg b.w.) High dose contrast-enhanced MRI (0.3 T) did not increase the diagnostic information for the evaluation of patients with failed back surgery syndrome compared to standard dose MRI. 55 refs, 9 figs, 10 tabs.

  15. Janus magneto-electric nanosphere dimers exhibiting unidirectional visible light scattering and strong electromagnetic field enhancement.

    Science.gov (United States)

    Wang, Hao; Liu, Pu; Ke, Yanlin; Su, Yunkun; Zhang, Lei; Xu, Ningsheng; Deng, Shaozhi; Chen, Huanjun

    2015-01-27

    Steering incident light into specific directions at the nanoscale is very important for future nanophotonics applications of signal transmission and detection. A prerequisite for such a purpose is the development of nanostructures with high-efficiency unidirectional light scattering properties. Here, from both theoretical and experimental sides, we conceived and demonstrated the unidirectional visible light scattering behaviors of a heterostructure, Janus dimer composed of gold and silicon nanospheres. By carefully adjusting the sizes and spacings of the two nanospheres, the Janus dimer can support both electric and magnetic dipole modes with spectral overlaps and comparable strengths. The interference of these two modes gives rise to the narrow-band unidirectional scattering behaviors with enhanced forward scattering and suppressed backward scattering. The directionality can further be improved by arranging the dimers into one-dimensional chain structures. In addition, the dimers also show remarkable electromagnetic field enhancements. These results will be important not only for applications of light emitting devices, solar cells, optical filters, and various surface enhanced spectroscopies but also for furthering our understanding on the light-matter interactions at the nanoscale.

  16. Mixed convection peristaltic flow of third order nanofluid with an induced magnetic field.

    Directory of Open Access Journals (Sweden)

    Saima Noreen

    Full Text Available This research is concerned with the peristaltic flow of third order nanofluid in an asymmetric channel. The governing equations of third order nanofluid are modelled in wave frame of reference. Effect of induced magnetic field is considered. Long wavelength and low Reynolds number situation is tackled. Numerical solutions of the governing problem are computed and analyzed. The effects of Brownian motion and thermophoretic diffusion of nano particles are particularly emphasized. Physical quantities such as velocity, pressure rise, temperature, induced magnetic field and concentration distributions are discussed.

  17. Quasi-static electric field in a cylindrical volume conductor induced by external coils.

    Science.gov (United States)

    Esselle, K P; Stuchly, M A

    1994-02-01

    An expansion technique based on modified Bessel functions is used to obtain an analytical solution for the electric field induced in a homogeneous cylindrical volume conductor by an external coil. The current in the coil is assumed to be changing slowly so that quasi-static conditions can be justified. Valid for any coil type, this solution is ideal for fast computation of the induced electric field at a large number of points. Efficient implementation of this method in a computer code is described and numerical results are presented for a perpendicular circular coil and a tangential double-square coil.

  18. Effects of external fields, dimension and pressure on the electromagnetically induced transparency of quantum dots

    International Nuclear Information System (INIS)

    Vaseghi, B.; Mohebi, N.

    2013-01-01

    Effects of external electric and magnetic fields, dimension and pressure on the electromagnetically induced transparency of a pumped-probe GaAs quantum dot are investigated. To study the electromagnetically induced transparency, the probe absorption and group velocity along with refractive index of the medium are discussed. It is found that electromagnetically induced transparency occurs in the system and its frequency, transparency window and group velocity of the probe field strongly depend on the external fields, pressure and the dot size. Significant effects of external factors on the quantum dot structures have the potential applications for implementation of electromagnetically induce transparency, slow lights, optical switches and quantum information storages. - Highlights: ► Sub-band energy states of a spherical QD are used to study the EIT. ► EIT strongly depends on the external fields, dimension and pressure. ► GI of a pulse strongly depends on the external fields, dimension and pressure. ► The production and controlling EIT and GI in QDs can be used for real applications.

  19. Passing particle toroidal precession induced by electric field in a tokamak

    International Nuclear Information System (INIS)

    Andreev, V. V.; Ilgisonis, V. I.; Sorokina, E. A.

    2013-01-01

    Characteristics of a rotation of passing particles in a tokamak with radial electric field are calculated. The expression for time-averaged toroidal velocity of the passing particle induced by the electric field is derived. The electric-field-induced additive to the toroidal velocity of the passing particle appears to be much smaller than the velocity of the electric drift calculated for the poloidal magnetic field typical for the trapped particle. This quantity can even have the different sign depending on the azimuthal position of the particle starting point. The unified approach for the calculation of the bounce period and of the time-averaged toroidal velocity of both trapped and passing particles in the whole volume of plasma column is presented. The results are obtained analytically and are confirmed by 3D numerical calculations of the trajectories of charged particles

  20. Magnetic field dependence of the critical superconducting current induced by the proximity effect in silicon

    International Nuclear Information System (INIS)

    Nishino, T.; Kawabe, U.; Yamada, E.

    1986-01-01

    The magnetic field dependence of the critical superconducting current induced by the proximity effect in heavily-boron-doped Si is studied experimentally. It is found that the critical current flowing through the p-type-Si-coupled junction decreases with increasing applied magnetic field. The critical current can be expressed as the product of three factors: the current induced by de Gennes's proximity effect, the exponential decrease due to pair breaking by the magnetic field, and the usual diffraction-pattern-like dependence on the magnetic field due to the Josephson effect. The second factor depends on the carrier concentration in the semiconductor. The local critical current shows a rapid decrease at the edge of the electrodes

  1. Modeling Radiation-Induced Degradation in Top-Gated Epitaxial Graphene Field-Effect-Transistors (FETs

    Directory of Open Access Journals (Sweden)

    Jeong-S. Moon

    2013-07-01

    Full Text Available This paper investigates total ionizing dose (TID effects in top-gated epitaxial graphene field-effect-transistors (GFETs. Measurements reveal voltage shifts in the current-voltage (I-V characteristics and degradation of carrier mobility and minimum conductivity, consistent with the buildup of oxide-trapped charges. A semi-empirical approach for modeling radiation-induced degradation in GFETs effective carrier mobility is described in the paper. The modeling approach describes Coulomb and short-range scattering based on calculations of charge and effective vertical field that incorporate radiation-induced oxide trapped charges. The transition from the dominant scattering mechanism is correctly described as a function of effective field and oxide trapped charge density. Comparison with experimental data results in good qualitative agreement when including an empirical component to account for scatterer transparency in the low field regime.

  2. Current densities in a pregnant woman model induced by simultaneous ELF electric and magnetic field exposure

    International Nuclear Information System (INIS)

    Cech, R; Leitgeb, N; Pediaditis, M

    2008-01-01

    The pregnant woman model SILVY was studied to ascertain to what extent the electric current densities induced by 50 Hz homogeneous electric and magnetic fields increase in the case of simultaneous exposure. By vectorial addition of the electric current densities, it could be shown that under worst case conditions the basic restrictions recommended by ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines are exceeded within the central nervous system (CNS) of the mother, whereas in sole field exposure they are not. However, within the foetus the induced current densities do not comply with basic restrictions, either from single reference-level electric fields or from simultaneous exposure to electric and magnetic fields. Basic limits were considerably exceeded

  3. Relativistic Néel-Order Fields Induced by Electrical Current in Antiferromagnets

    KAUST Repository

    Železný, J.

    2014-10-06

    We predict that a lateral electrical current in antiferromagnets can induce nonequilibrium Néel-order fields, i.e., fields whose sign alternates between the spin sublattices, which can trigger ultrafast spin-axis reorientation. Based on microscopic transport theory calculations we identify staggered current-induced fields analogous to the intraband and to the intrinsic interband spin-orbit fields previously reported in ferromagnets with a broken inversion-symmetry crystal. To illustrate their rich physics and utility, we consider bulk Mn2Au with the two spin sublattices forming inversion partners, and a 2D square-lattice antiferromagnet with broken structural inversion symmetry modeled by a Rashba spin-orbit coupling. We propose an antiferromagnetic memory device with electrical writing and reading.

  4. Secular variation of the Earth's magnetic field: induced by the ocean flow?

    International Nuclear Information System (INIS)

    Ryskin, Gregory

    2009-01-01

    Secular variation of the Earth's main magnetic field is believed to originate in the Earth's core. (The main field is operationally defined as comprising spherical harmonics of degree l≤10.) I propose a different mechanism of secular variation: ocean water being a conductor of electricity, the magnetic field induced by the ocean as it flows through the Earth's main field may depend on time and manifest itself globally as secular variation. This proposal is supported by calculation of secular variation using the induction equation of magnetohydrodynamics, the observed main field and the ocean flow field. The predicted secular variation is in rough agreement with that observed. Additional support is provided by the striking temporal correlation (hitherto unsuspected) between the intensity of the North Atlantic oceanic circulation and the rate of secular variation in Western Europe; this explains, in particular, the geomagnetic jerks, and the recently discovered correlation between secular variation and climate. Spatial correlation between ocean currents and secular variation is also strong.

  5. Adjustment of Adiabatic Transition Magnetic Field of Solenoid-Induced Helicla Wiggler

    CERN Document Server

    Tsunawaki, Y

    2005-01-01

    We have been constructed a solenoid-induced helical wiggler for a compact free electron maser operated in a usual small laboratory which does not have electric source capacity available enough. It consists of two staggered-iron arrays inserted perpendicularly to each other in a solenoid electromagnet. In order to lead/extract an electron beam into/from the wiggler, adiabatic transition (AT) field is necessary at both ends of the wiggler. In this work the AT field was produced by setting staggered-nickel plates with different thickness in the five periods. The thickness of each nickel plate was decided by the field analysis using the MAGTZ computational code based on a magnetic moment method. Exact thickness was, however, found by the precise measurement of the field distribution with the greatest circumspection to obtain a homogeneous increment of the AT field. The change of AT field distribution was studied by referring to an equivalent electric circuit of the wiggler.

  6. Magnetic-field induced phase transitions in intermetallic rare-earth ferrimagnets with a compensation point

    Czech Academy of Sciences Publication Activity Database

    Sabdenov, Ch.K.; Davydova, M.D.; Zvezdin, K.A.; Gorbunov, Denis; Tereshina, I. S.; Andreev, Alexander V.; Zvezdin, A. K.

    2017-01-01

    Roč. 43, č. 5 (2017), s. 551-558 ISSN 1063-777X R&D Projects: GA ČR GA16-03593S Institutional support: RVO:68378271 Keywords : rare -earth intermetallics * phase diagram * field-induced transition * magnetic anisotropy * high magnetic fields Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.804, year: 2016

  7. Enhancement of vortex induced forces and motion through surface roughness control

    Science.gov (United States)

    Bernitsas, Michael M [Saline, MI; Raghavan, Kamaldev [Houston, TX

    2011-11-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

  8. [Study of enhancement effect of laser-induced crater on plasma radiation].

    Science.gov (United States)

    Chen, Jin-Zhong; Zhang, Xiao-Ping; Guo, Qing-Lin; Su, Hong-Xin; Li, Guang

    2009-02-01

    Single pulses exported from high-energy neodymium glass laser were used to act on the same position of soil sample surface repeatedly, and the plasma emission spectra generated from sequential laser pulse action were collected by spectral recording system. The experimental results show that the laser-induced soil plasma radiation was enhanced continuously under the confinement effect of the crater walls, and the line intensities and signal-to-background ratios both had different improvements along with increasing the number of acting pulses. The photographs of the plasma image and crater appearance were taken to study the plasma shape, laser-induced crater appearance, and the mass of the ablated sample. The internal mechanism behind that laser-induced crater enhanced plasma radiation was researched. Under the sequential laser pulse action, the forming plasma as a result enlarges gradually first, leading to distortion at the trail of plasma plume, and then, its volume diminishes slowly. And also, the color of the plasma changes from buff to white gradually, which implies that the temperature increases constantly. The laser-induced crater had a regular shape, that is, the diameter increased from its bottom to top gradually, thus forming a taper. The mass of the laser-ablated substance descends along with increasing the amount of action pulse. Atomization degree of vaporized substance was improved in virtue of the crater confinement effect, Fresnel absorption produced from the crater walls reflection, and the inverse bremsstrahlung, and the plasma radiation intensity was enhanced as a result.

  9. Applied electric field enhances DRG neurite growth: influence of stimulation media, surface coating and growth supplements

    Science.gov (United States)

    Wood, Matthew D.; Willits, Rebecca Kuntz

    2009-08-01

    Electrical therapies have been found to aid repair of nerve injuries and have been shown to increase and direct neurite outgrowth during stimulation. This enhanced neural growth existed even after the electric field (EF) or stimulation was removed, but the factors that may influence the enhanced growth, such as stimulation media or surface coating, have not been fully investigated. This study characterized neurite outgrowth and branching under various conditions: EF magnitude and application time, ECM surface coating, medium during EF application and growth supplements. A uniform, low-magnitude EF (24 or 44 V m-1) was applied to dissociated chick embryo dorsal root ganglia seeded on collagen or laminin-coated surfaces. During the growth period, cells were either exposed to NGF or N2, and during stimulation cells were exposed to either unsupplemented media (Ca2+) or PBS (no Ca2+). Parallel controls for each experiment included cells exposed to the chamber with no stimulation and cells remaining outside the chamber. After brief electrical stimulation (10 min), neurite length significantly increased 24 h after application for all conditions studied. Of particular interest, increased stimulation time (10-100 min) further enhanced neurite length on laminin but not on collagen surfaces. Neurite branching was not affected by stimulation on any surface, and no preferential growth of neurites was noted after stimulation. Overall, the results of this report suggest that short-duration electric stimulation is sufficient to enhance neurite length under a variety of conditions. While further data are needed to fully elucidate a mechanism for this increased growth, these data suggest that one focus of those investigations should be the interaction between the growth cone and the substrata.

  10. Enhanced decomposition of stable soil organic carbon and microbial catabolic potentials by long-term field warming.

    Science.gov (United States)

    Feng, Wenting; Liang, Junyi; Hale, Lauren E; Jung, Chang Gyo; Chen, Ji; Zhou, Jizhong; Xu, Minggang; Yuan, Mengting; Wu, Liyou; Bracho, Rosvel; Pegoraro, Elaine; Schuur, Edward A G; Luo, Yiqi

    2017-11-01

    Quantifying soil organic carbon (SOC) decomposition under warming is critical to predict carbon-climate feedbacks. According to the substrate regulating principle, SOC decomposition would decrease as labile SOC declines under field warming, but observations of SOC decomposition under warming do not always support this prediction. This discrepancy could result from varying changes in SOC components and soil microbial communities under warming. This study aimed to determine the decomposition of SOC components with different turnover times after subjected to long-term field warming and/or root exclusion to limit C input, and to test whether SOC decomposition is driven by substrate lability under warming. Taking advantage of a 12-year field warming experiment in a prairie, we assessed the decomposition of SOC components by incubating soils from control and warmed plots, with and without root exclusion for 3 years. We assayed SOC decomposition from these incubations by combining inverse modeling and microbial functional genes during decomposition with a metagenomic technique (GeoChip). The decomposition of SOC components with turnover times of years and decades, which contributed to 95% of total cumulative CO 2 respiration, was greater in soils from warmed plots. But the decomposition of labile SOC was similar in warmed plots compared to the control. The diversity of C-degradation microbial genes generally declined with time during the incubation in all treatments, suggesting shifts of microbial functional groups as substrate composition was changing. Compared to the control, soils from warmed plots showed significant increase in the signal intensities of microbial genes involved in degrading complex organic compounds, implying enhanced potential abilities of microbial catabolism. These are likely responsible for accelerated decomposition of SOC components with slow turnover rates. Overall, the shifted microbial community induced by long-term warming accelerates the

  11. Quasi-resonance enhancement of laser-induced-fluorescence diagnosis of endometriosis

    Science.gov (United States)

    Hill, Ralph H., Jr.; Vancaillie, Thierry G.

    1990-05-01

    Endometriosis, a common disease in women in the reproductive age group, is defined pathologically by the presence of endometrial tissue (inner lining of the uterus) outside the uterus. The displaced tissue is histologically identical to endometrium. In addition to being a highly prevalent disease, this disease is associated with many distressing and debilitating symptoms. Motivated by the need to improve diagnosis by endoscopic imaging instrumentation, we have previously used several drugs to cause selective laser-induced fluorescence of active surgically induced endometriosis in the rabbit model in vivo using ultraviolet-wavelength (351.1 and 363.8 nm) excitation from an argon-ion laser. In the present study we have investigated methods of enhancing differentiation between normal and abnormal tissue by using other excitation wavelengths. In addition to an enhanced capability for detecting abnormal tissue, there are several other advantages associated with using visible-wavelength excitation, such as deeper penetration into the tissue, as well as increased equipment performance, reliability, versatility, and availability. The disadvantage is that because only wavelengths longer than the excitation wavelength can be used for detection, some of the spectral information is lost. Because human endomeiriosis samples were somewhat limited in quantity, as well as specimen size, we used normal ovarian tissue for the laser-induced-fluorescence differentiation-enhancement studies. Positive enhancement of the laser-induced- fluorescence differentiation was found in human ovarian tissue in vitro utilizing 514.5-nm excitation from an argonion laser. Additionally, preliminary verification of this concept was accomplished in active surgically induced endometriosis in the rabbit model in vivo with visible argon-ion laser excitation of two tetracycline-based drugs. Future experiments with other drug treatments and excitation/detection parameters are planned.

  12. Europa's Alfvén wing: shrinkage and displacement influenced by an induced magnetic field

    Directory of Open Access Journals (Sweden)

    M. Volwerk

    2007-05-01

    Full Text Available The Galileo magnetometer data are used to investigate the structure of the Alfvén wing during three flybys of Europa. The presence of an induced magnetic field is shown to shrink the cross section of the Alfvén wing and offset it along the direction radial to Jupiter. Both the shrinkage and the offset depend on the strength of the induced field. The entry and exit points of the spacecraft into and out of the Alfvén wings are modeled to determine the angle between the wings and the background magnetic field. Tracing of the Alfvén characteristics in a model magnetic field consisting of Jupiter's background field and an induced field in Europa produces an offset and shrinking of the Alfvén wing consistent with the geometric modeling. Thus we believe that the Alfvén wing properties have been determined correctly. The Alfvén wing angle is directly proportional to the local Alfvén velocity, and is thus a probe for the local plasma density. We show that the inferred plasma density can be understood in terms of the electron density measured by the plasma wave experiment. When Europa is located in the Jovian plasma sheet the derived mass-per-charge exceeds the previous estimates, which is a result of increased pickup of sputtered ions near the moon. The estimated rate of O2+ pickup agrees well with the results from numerical models.

  13. Blast-induced electromagnetic fields in the brain from bone piezoelectricity.

    Science.gov (United States)

    Lee, Ka Yan Karen; Nyein, Michelle K; Moore, David F; Joannopoulos, J D; Socrate, Simona; Imholt, Timothy; Radovitzky, Raul; Johnson, Steven G

    2011-01-01

    In this paper, we show that bone piezoelectricity-a phenomenon in which bone polarizes electrically in response to an applied mechanical stress and produces a short-range electric field-may be a source of intense blast-induced electric fields in the brain, with magnitudes and timescales comparable to fields with known neurological effects. We compute the induced charge density in the skull from stress data on the skull from a finite-element full-head model simulation of a typical IED-scale blast wave incident on an unhelmeted human head as well as a human head protected by a kevlar helmet, and estimate the resulting electric fields in the brain in both cases to be on the order of 10 V/m in millisecond pulses. These fields are more than 10 times stronger than the IEEE safety guidelines for controlled environments (IEEE Standards Coordinating Committee 28, 2002) and comparable in strength and timescale to fields from repetitive Transcranial Magnetic Stimulation (rTMS) that are designed to induce neurological effects (Wagner et al., 2006a). They can be easily measured by RF antennas, and may provide the means to design a diagnostic tool that records a quantitative measure of the head's exposure to blast insult. Copyright © 2010 Elsevier Inc. All rights reserved.

  14. Jc enhancement by La-Al-O doping in Y-Ba-Cu-O films both in self-field and under magnetic field

    DEFF Research Database (Denmark)

    Xu, Yan; Suo, Hong-Li; Yue, Zhao

    2016-01-01

    To enhance the Jc of YBa2Cu3O7−X (YBCO) films both in self-field and under magnetic field, an effective strategy is to introduce artificial pinning centers and keep a good YBCO matrix at the same time. Here, we propose a new dopant: LaAlO3 (LAO), based on its chemical stability and small mismatch...... a good epitaxial growth relationship with LAO. Compared with a pure YBCO film, the Jc value of a 5.0% LAO-doped sample is enhanced more than three times in self-field 77 K and seven times at 77 K and 1.5 T, respectively. These results indicate that LAO doping can effectively enhance the Jc of YBCO films...

  15. Reduction of arsenite-enhanced ultraviolet radiation-induced DNA damage by supplemental zinc

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Karen L.; King, Brenee S.; Sandoval, Monica M.; Liu, Ke Jian; Hudson, Laurie G., E-mail: lhudson@salud.unm.edu

    2013-06-01

    Arsenic is a recognized human carcinogen and there is evidence that arsenic augments the carcinogenicity of DNA damaging agents such as ultraviolet radiation (UVR) thereby acting as a co-carcinogen. Inhibition of DNA repair is one proposed mechanism to account for the co-carcinogenic actions of arsenic. We and others find that arsenite interferes with the function of certain zinc finger DNA repair proteins. Furthermore, we reported that zinc reverses the effects of arsenite in cultured cells and a DNA repair target protein, poly (ADP-ribose) polymerase-1. In order to determine whether zinc ameliorates the effects of arsenite on UVR-induced DNA damage in human keratinocytes and in an in vivo model, normal human epidermal keratinocytes and SKH-1 hairless mice were exposed to arsenite, zinc or both before solar-simulated (ss) UVR exposure. Poly (ADP-ribose) polymerase activity, DNA damage and mutation frequencies at the Hprt locus were measured in each treatment group in normal human keratinocytes. DNA damage was assessed in vivo by immunohistochemical staining of skin sections isolated from SKH-1 hairless mice. Cell-based findings demonstrate that ssUVR-induced DNA damage and mutagenesis are enhanced by arsenite, and supplemental zinc partially reverses the arsenite effect. In vivo studies confirm that zinc supplementation decreases arsenite-enhanced DNA damage in response to ssUVR exposure. From these data we can conclude that zinc offsets the impact of arsenic on ssUVR-stimulated DNA damage in cells and in vivo suggesting that zinc supplementation may provide a strategy to improve DNA repair capacity in arsenic exposed human populations. - Highlights: • Low levels of arsenite enhance UV-induced DNA damage in human keratinocytes. • UV-initiated HPRT mutation frequency is enhanced by arsenite. • Zinc supplementation offsets DNA damage and mutation frequency enhanced by arsenite. • Zinc-dependent reduction of arsenite enhanced DNA damage is confirmed in vivo.

  16. Glioblastoma Presenting with Steroid-Induced Pseudoregression of Contrast Enhancement on Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Marcus D. Mazur

    2012-01-01

    Full Text Available Corticosteroid-induced reduction in contrast enhancement on radiographic imaging is most commonly associated with lymphoma but has been reported in other entities, including glioma. This finding may represent a diagnostic dilemma. Concern that steroid-induced cytotoxicity obscures histological diagnosis of suspected lymphoma may lead to postponement of a biopsy. If glioma is not considered in the differential diagnosis, reduction in tumor contrast enhancement may be misinterpreted as disease regression rather than a transient radiographic change. We report a case of a patient with an enhancing right temporoparietal mass adjacent to the atrium of the lateral ventricle. After treatment with dexamethasone was started, the mass exhibited marked reduction in contrast enhancement, with symptom improvement. The clinical course suggested lymphoma, and surgery was not performed. Subsequent screening for extra-axial lymphoma was negative. Two weeks later, the patient developed worsening symptoms, and repeat T1-weighted imaging showed interval increase in size and enhancement. The findings suggested a possible diagnosis of malignant glioma. The patient underwent a stereotactic-guided craniotomy for excision of the right temporoparietal mass lesion. Final histological diagnosis was glioblastoma multiforme, World Health Organization grade IV.

  17. Alternating magnetic field-induced hyperthermia increases iron oxide nanoparticle cell association/uptake and flux in blood-brain barrier models.

    Science.gov (United States)

    Dan, Mo; Bae, Younsoo; Pittman, Thomas A; Yokel, Robert A

    2015-05-01

    Superparamagnetic iron oxide nanoparticles (IONPs) are being investigated for brain cancer therapy because alternating magnetic field (AMF) activates them to produce hyperthermia. For central nervous system applications, brain entry of diagnostic and therapeutic agents is usually essential. We hypothesized that AMF-induced hyperthermia significantly increases IONP blood-brain barrier (BBB) association/uptake and flux. Cross-linked nanoassemblies loaded with IONPs (CNA-IONPs) and conventional citrate-coated IONPs (citrate-IONPs) were synthesized and characterized in house. CNA-IONP and citrate-IONP BBB cell association/uptake and flux were studied using two BBB Transwell(®) models (bEnd.3 and MDCKII cells) after conventional and AMF-induced hyperthermia exposure. AMF-induced hyperthermia for 0.5 h did not alter CNA-IONP size but accelerated citrate-IONP agglomeration. AMF-induced hyperthermia for 0.5 h enhanced CNA-IONP and citrate-IONP BBB cell association/uptake. It also enhanced the flux of CNA-IONPs across the two in vitro BBB models compared to conventional hyperthermia and normothermia, in the absence of cell death. Citrate-IONP flux was not observed under these conditions. AMF-induced hyperthermia also significantly enhanced paracellular pathway flux. The mechanism appears to involve more than the increased temperature surrounding the CNA-IONPs. Hyperthermia induced by AMF activation of CNA-IONPs has potential to increase the BBB permeability of therapeutics for the diagnosis and therapy of various brain diseases.

  18. Induced Electromagnetic Field by Seismic Waves in Stratified Media in Earth's Magnetic Field

    Science.gov (United States)

    Yamazaki, K.

    2017-12-01

    Seismic waves accompany electromagnetic (EM) variations because Earth's crust involves a variety of EM properties such as finite electrical conductivity and ion contents. If we can catch the EM variations just after the earthquake rupture, we will know the occurrence of earthquake before the arrival of seismic waves at observation point. However, quantitative aspects of EM variations arising from seismic waves have not sufficiently understood. Together with observational works, theoretical works have been made to simulate EM variations arising from seismic waves. The generation mechanisms of EM variations include electrokinetic effect (Pride, 1994), motional induction (Gao et al., 2014), piezo-electric effect (Ogawa and Utada, 2000), piezo-magnetic effect (Yamazaki, 2016), etc. It is widely accepted that the electrokinetic effect is the dominant mechanism. Theoretical calculation of EM variations assuming the electrokinetic effect roughly explains the observed EM variations accompanying with earthquake ground motions (e.g. Gao et al. 2016). However, there are a significant disagreement between observed and predicted EM variations. In the present study, I focus on the motional induction mechanism that possibly explain some parts of EM variations accompanying with seismic waves. A theoretical work on EM variations arising from the motional induction has been presented by Gao et al. (2014), but their work assumed uniform full-space medium. In contrast, the present work assumes stratified media which correctly incorporate the effect of the ground surface. I apply a calculating method developed in seismology (e.g. Kennett, 2013) and in EM studies (Haartsen and Pride, 1997), and derive a set of expressions describing the spatial-temporal variations of the EM field after the onset of rupture. The derived formula is used to calculate EM variations for actual earthquakes to compare the theoretical prediction to observed EM variations.

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

    Science.gov (United States)

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

    2016-09-01

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

  20. Targeting Aerobic Glycolysis and HIF-1α Expression Enhance Imiquimod-induced Apoptosis in Cancer Cells

    Science.gov (United States)

    Huang, Shi-Wei; Kao, Jun-Kai; Wu, Chun-Ying; Wang, Sin-Ting; Lee, Hsin-Chen; Liang, Shu-Mei; Chen, Yi-Ju; Shieh, Jeng-Jer

    2014-01-01

    Tumor cells rely on aerobic glycolysis to maintain unconstrained cell growth and proliferation. Imiquimod (IMQ), a synthetic Toll-like receptor (TLR) 7/8 ligand, exerts anti-tumor effects directly by inducing cell death in cancer cells and/or indirectly by activating cellular immune responses against tumor cells. However, whether IMQ modulates glucose metabolism pathways remains unclear. In this study, we demonstrated that IMQ can enhance aerobic glycolysis by up-regulating HIF-1α expression at the transcriptional and translational levels via ROS mediated STAT3- and Akt-dependent pathways, independent of TLR7/8 signaling. The genetic silencing of HIF-1α not only repressed IMQ-induced aerobic glycolysis but also sensitized cells to IMQ-induced apoptosis due to faster ATP and Mcl-1 depletion. Moreover, the glucose analog 2-DG and the Hsp90 inhibitor 17-AAG, which destabilizes the HIF-1α protein, synergized with IMQ to induce tumor cell apoptosis in vitro and significantly inhibited tumor growth in vivo. Thus, we hypothesize that the IMQ-induced up-regulation of HIF-1α and aerobic glycolysis is a protective response to the metabolic stress generated by IMQ treatment, and thus, co-treatment with inhibitors of HIF-1α and/or glycolysis may be a useful therapeutic strategy to enhance the anti-tumor effects of IMQ in clinical settings. PMID:24658058

  1. Dye-Induced Enhancement of Optical Nonlinearity in Liquids and Liquid Crystals

    International Nuclear Information System (INIS)

    Muenster, R.; Jarasch, M.; Zhuang, X.; Shen, Y.

    1997-01-01

    Optical nonlinearity of liquid crystals (LC) in the isotropic phase can be enhanced by 1 order of magnitude by dissolving 0.1% of anthraquinone dye in the LC. The enhancement decreases by ∼30% when the LC transforms into the nematic phase. The same guest-host effect also exists in non-LC liquids. It can be explained by a model based on the change of guest-host interaction induced by optical excitations of the dye. copyright 1996 The American Physical Society

  2. Depletion of Paraspeckle Protein 1 Enhances Methyl Methanesulfonate-Induced Apoptosis through Mitotic Catastrophe.

    Directory of Open Access Journals (Sweden)

    Xiangjing Gao

    Full Text Available Previously, we have shown that paraspeckle protein 1 (PSPC1, a protein component of paraspeckles that was involved in cisplatin-induced DNA damage response (DDR, probably functions at the G1/S checkpoint. In the current study, we further examined the role of PSPC1 in another DNA-damaging agent, methyl methanesulfonate (MMS-induced DDR, in particular, focusing on MMS-induced apoptosis in HeLa cells. First, it was found that MMS treatment induced the expression of PSPC1. While MMS treatment alone can induce apoptosis, depletion of PSPC1 expression using siRNA significantly increased the level of apoptosis following MMS exposure. In contrast, overexpressing PSPC1 decreased the number of apoptotic cells. Interestingly, morphological observation revealed that many of the MMS-treated PSPC1-knockdown cells contained two or more nuclei, indicating the occurrence of mitotic catastrophe. Cell cycle analysis further showed that depletion of PSPC1 caused more cells entering the G2/M phase, a prerequisite of mitosis catastrophe. On the other hand, over-expressing PSPC1 led to more cells accumulating in the G1/S phase. Taken together, these observations suggest an important role for PSPC1 in MMS-induced DDR, and in particular, depletion of PSPC1 can enhance MMS-induced apoptosis through mitotic catastrophe.

  3. Trehalose enhances osmotic tolerance and suppresses lysophosphatidylcholine-induced acrosome reaction in ram spermatozoon.

    Science.gov (United States)

    Ahmad, E; Naseer, Z; Aksoy, M; Küçük, N; Uçan, U; Serin, I; Ceylan, A

    2015-09-01

    This study was aimed to investigate the influence of trehalose on osmotic tolerance and the ability of ram spermatozoon to undergo acrosome reaction induced by lysophosphatidylcholine (LPC). In experiment 1, the diluted ejaculates were exposed to anisosmotic fructose solutions (70, 500, 750 and 1000 mOsm l(-1) ) with or without 50 mm trehalose. The presence of trehalose in hyperosmotic conditions enhanced (P spermatozoon was less (P spermatozoon and suppresses their ability to undergo LPC and cryo-induced acrosome reaction. © 2014 Blackwell Verlag GmbH.

  4. Enhanced acceleration of injected electrons in a laser-beat-wave-induced plasma channel.

    Science.gov (United States)

    Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C

    2004-03-05

    Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser beat wave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-wave-induced plasma channel.

  5. Oxazolone-induced contact hypersensitivity reduces lymphatic drainage but enhances the induction of adaptive immunity.

    Directory of Open Access Journals (Sweden)

    David Aebischer

    Full Text Available Contact hypersensitivity (CHS induced by topical application of haptens is a commonly used model to study dermal inflammatory responses in mice. Several recent studies have indicated that CHS-induced skin inflammation triggers lymphangiogenesis but may negatively impact the immune-function of lymphatic vessels, namely fluid drainage and dendritic cell (DC migration to draining lymph nodes (dLNs. On the other hand, haptens have been shown to exert immune-stimulatory activity by inducing DC maturation. In this study we investigated how the presence of pre-established CHS-induced skin inflammation affects the induction of adaptive immunity in dLNs. Using a mouse model of oxazolone-induced skin inflammation we observed that lymphatic drainage was reduced and DC migration from skin to dLNs was partially compromised. At the same time, a significantly stronger adaptive immune response towards ovalbumin (OVA was induced when immunization had occurred in CHS-inflamed skin as compared to uninflamed control skin. In fact, immunization with sterile OVA in CHS-inflamed skin evoked a delayed-type hypersensitivity (DTH response comparable to the one induced by conventional immunization with OVA and adjuvant in uninflamed skin. Striking phenotypic and functional differences were observed when comparing DCs from LNs draining uninflamed or CHS-inflamed skin. DCs from LNs draining CHS-inflamed skin expressed higher levels of co-stimulatory molecules and MHC molecules, produced higher levels of the interleukin-12/23 p40 subunit (IL-12/23-p40 and more potently induced T cell activation in vitro. Immunization experiments revealed that blockade of IL-12/23-p40 during the priming phase partially reverted the CHS-induced enhancement of the adaptive immune response. Collectively, our findings indicate that CHS-induced skin inflammation generates an overall immune-stimulatory milieu, which outweighs the potentially suppressive effect of reduced lymphatic vessel function.

  6. Glucose Enhances Basal or Melanocortin-Induced cAMP-Response Element Activity in Hypothalamic Cells

    Science.gov (United States)

    Wicht, Kristina; Boekhoff, Ingrid; Glas, Evi; Lauffer, Lisa; Mückter, Harald; Gudermann, Thomas

    2016-01-01

    Melanocyte-stimulating hormone (MSH)-induced activation of the cAMP-response element (CRE) via the CRE-binding protein in hypothalamic cells promotes expression of TRH and thereby restricts food intake and increases energy expenditure. Glucose also induces central anorexigenic effects by acting on hypothalamic neurons, but the underlying mechanisms are not completely understood. It has been proposed that glucose activates the CRE-binding protein-regulated transcriptional coactivator 2 (CRTC-2) in hypothalamic neurons by inhibition of AMP-activated protein kinases (AMPKs), but whether glucose directly affects hypothalamic CRE activity has not yet been shown. Hence, we dissected effects of glucose on basal and MSH-induced CRE activation in terms of kinetics, affinity, and desensitization in murine, hypothalamic mHypoA-2/10-CRE cells that stably express a CRE-dependent reporter gene construct. Physiologically relevant increases in extracellular glucose enhanced basal or MSH-induced CRE-dependent gene transcription, whereas prolonged elevated glucose concentrations reduced the sensitivity of mHypoA-2/10-CRE cells towards glucose. Glucose also induced CRCT-2 translocation into the nucleus and the AMPK activator metformin decreased basal and glucose-induced CRE activity, suggesting a role for AMPK/CRTC-2 in glucose-induced CRE activation. Accordingly, small interfering RNA-induced down-regulation of CRTC-2 expression decreased glucose-induced CRE-dependent reporter activation. Of note, glucose also induced expression of TRH, suggesting that glucose might affect the hypothalamic-pituitary-thyroid axis via the regulation of hypothalamic CRE activity. These findings significantly advance our knowledge about the impact of glucose on hypothalamic signaling and suggest that TRH release might account for the central anorexigenic effects of glucose and could represent a new molecular link between hyperglycaemia and thyroid dysfunction. PMID:27144291

  7. Genetic modification to induce CXCR2 overexpression in mesenchymal stem cells enhances treatment benefits in radiation-induced oral mucositis.

    Science.gov (United States)

    Shen, Zongshan; Wang, Jiancheng; Huang, Qiting; Shi, Yue; Wei, Zhewei; Zhang, Xiaoran; Qiu, Yuan; Zhang, Min; Wang, Yi; Qin, Wei; Huang, Shuheng; Huang, Yinong; Liu, Xin; Xia, Kai; Zhang, Xinchun; Lin, Zhengmei

    2018-02-14

    Radiation-induced oral mucositis affects patient quality of life and reduces tolerance to cancer therapy. Unfortunately, traditional treatments are insufficient for the treatment of mucositis and might elicit severe side effects. Due to their immunomodulatory and anti-inflammatory properties, the transplantation of mesenchymal stem cells (MSCs) is a potential therapeutic strategy for mucositis. However, systemically infused MSCs rarely reach inflamed sites, impacting their clinical efficacy. Previous studies have demonstrated that chemokine axes play an important role in MSC targeting. By systematically evaluating the expression patterns of chemokines in radiation/chemical-induced oral mucositis, we found that CXCL2 was highly expressed, whereas cultured MSCs negligibly express the CXCL2 receptor CXCR2. Thus, we explored the potential therapeutic benefits of the transplantation of CXCR 2 -overexpressing MSCs (MSCs CXCR2 ) for mucositis treatment. Indeed, MSCs CXCR2 exhibited enhanced targeting ability to the inflamed mucosa in radiation/chemical-induced oral mucositis mouse models. Furthermore, we found that MSC CXCR2 transplantation accelerated ulcer healing by suppressing the production of pro-inflammatory chemokines and radiogenic reactive oxygen species (ROS). Altogether, these findings indicate that CXCR2 overexpression in MSCs accelerates ulcer healing, providing new insights into cell-based therapy for radiation/chemical-induced oral mucositis.

  8. AC electric field induced droplet deformation in a microfluidic T-junction.

    Science.gov (United States)

    Xi, Heng-Dong; Guo, Wei; Leniart, Michael; Chong, Zhuang Zhi; Tan, Say Hwa

    2016-08-02

    We present for the first time an experimental study on the droplet deformation induced by an AC electric field in droplet-based microfluidics. It is found that the deformation of the droplets becomes stronger with increasing electric field intensity and frequency. The measured electric field intensity dependence of the droplet deformation is consistent with an early theoretical prediction for stationary droplets. We also proposed a simple equivalent circuit model to account for the frequency dependence of the droplet deformation. The model well explains our experimental observations. In addition, we found that the droplets can be deformed repeatedly by applying an amplitude modulation (AM) signal.

  9. Field-Induced Deformation as a Mechanism for Scanning Tunneling Microscopy Based Nanofabrication

    DEFF Research Database (Denmark)

    Hansen, Ole; Ravnkilde, Jan Tue; Quaade, Ulrich

    1998-01-01

    The voltage between tip and sample in a scanning tunneling microscope (STM) results in a large electric field localized near the tip apex. The mechanical stress due to this field can cause appreciable deformation of both tip and sample on the scale of the tunnel gap. We derive an approximate...... analytical expression for this deformation and confirm the validity of the result by comparison with a finite element analysis. We derive the condition for a field-induced jump to contact of tip and sample and show that this agrees well with experimental results for material transfer between tip and sample...... by voltage pulsing in ultrahigh vacuum....

  10. Electric-field-induced spin accumulation in polymer light-emitting diodes.

    Science.gov (United States)

    Li, Sheng; George, Thomas F; Sun, Xin; Chen, Liang-Shan

    2007-06-07

    An electric-field-induced spin accumulation phenomenon is presented for electroluminescent conjugated polymers as light-emitting diodes (LEDs). When an electric field is applied along a polymer chain and exceeds a critical value, it quenches the luminescence and dissociates the singlet exciton into two carriers with opposite spin signs. Simultaneously, the field drives these two opposite spin carriers to move in opposite directions, leading to spin accumulation at the two ends of the organic material LED, which can be detected through Kerr rotation microscopy.

  11. The reversal of light-induced degradation in amorphous silicon solar cells by an electric field

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, D.E.; Rajan, K. [Solarex, a Business Unit of Amoco/Enron Solar, Newtown, Pennsylvania 19840 (United States)

    1997-04-01

    A strong electric field has been shown to reverse the light-induced degradation of amorphous silicon solar cells while exposed to intense illumination at moderate temperatures. The rate of reversal increases with temperature, illumination intensity, and with the strength of the reverse bias field. The reversal process exhibits an activation energy on the order of 0.9 eV and can be increased by the trapping of either electrons or holes in the presence of a strong electric field. {copyright} {ital 1997 American Institute of Physics.}

  12. Time-domain electric field enhancement on micrometer scale in coupled split ring resonator upon terahertz radiation

    DEFF Research Database (Denmark)

    Lange, Simon Lehnskov; Iwaszczuk, Krzysztof; Hoffmann, Matthias

    2016-01-01

    We present here a novel design for a coupled split ring resonator antenna optimized for time-domain electric field enhancement in the 0.1 to 1 terahertz (THz) range. The antenna is designed to be sensitive to the incident field polarization and seeks to avoid metal damage due to electron...

  13. Biochemical study of human periodontal ligament: preparation of cell attachment materials induced by pulsed electromagnetic fields.

    Science.gov (United States)

    Kim, K T

    1990-09-01

    The periodontium, especially the periodontal ligament and alveolar bone, are tissues constantly subjected to physical stress such as occlusion and mastication. This study was designed to explore the effect of the pulsed electromagnetic fields (PEMF) on the cell attachment and the spread of human periodontal ligament fibroblasts (HPLF) and rat osteoblasts (ROB). PEMF are categorized as one type of mechanical stress. HPLF were obtained by the explantation method described by Saito et al. They were then subcultured in Dulbecco's modified Eagle's medium (D-MEM) and supplemented with 2 mg/ml dialyzed fetal calf serum protein (FCSP), 50 micrograms/ml ascorbic acid and penicillin/streptomycin after trypsinization. ROB were isolated from a two-day-old rat calvaria by the sequential bacterial collagenase digestion method described by Dziak and Brand and were subcultured in D-MEM supplemented with FCSP, ascorbic acid and penicillin/streptomycin. After the confluent HPLF were cultured with serum-free MCDB 107 medium, the quiescent HPLF were exposed with or without PEMF for 24 hr. This was followed by the collection of the control conditioned medium (C-CM) and PEMF exposed conditioned medium (PEMF-CM). The cell attachment assay was performed so that the hydrophobic 24 multiwells were coated with the whole conditioned medium or fractionated conditioned medium by a PO-60K column. After coating, heat inactivated BSA blocked nonspecific sites for cell adhesion, and 3H-TdR labeled HPLF or ROB were cultured on the precoated wells. The activity of cell attachment and spreading was determined by the radioactivity of 3H-TdR using a scintillation counter. The characters of cell attachment factors derived from HPLF were hydrophobic, heat labile and proteolytic enzyme digestible. In addition, the fractionated PEMF-CM enhanced the spreading activity of ROB. PEMF induced the 10 KDa which can enhance the HPLF and ROB spreading. Therefore, the cell attachment and spreading factors secreted by

  14. Olfactory Fear Conditioning Induces Field Potential Potentiation in Rat Olfactory Cortex and Amygdala

    Science.gov (United States)

    Messaoudi, Belkacem; Granjon, Lionel; Mouly, Anne-Marie; Sevelinges, Yannick; Gervais, Remi

    2004-01-01

    The widely used Pavlovian fear-conditioning paradigms used for studying the neurobiology of learning and memory have mainly used auditory cues as conditioned stimuli (CS). The present work assessed the neural network involved in olfactory fear conditioning, using olfactory bulb stimulation-induced field potential signal (EFP) as a marker of…

  15. Measurement of 3-Axis Magnetic Fields Induced by Current Wires Using a Smartphone in Magnetostatics Experiments

    Science.gov (United States)

    Setiawan, B.; Septianto, R. D.; Suhendra, D.; Iskandar, F.

    2017-01-01

    This paper describes the use of an inexpensive smartphone's magnetic sensor to measure magnetic field components (B[subscript x], B[subscript y] and B[subscript z]) induced by current wires in magnetostatic experiments. The variable parameters used to measure the magnetic sensor's capabilities were: the geometrical shapes of the wire, current…

  16. Directed magnetic field induced assembly of high magnetic moment cobalt nanowires

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A directed magnetic field induced assembly technique was employed to align two phase (h.c.p. + f.c.c.) cobalt nanoparticles in a mechanically robust long wire morphology. Co nanoparticles with an average size of 4.3 nm and saturation magnetization comparable to bulk cobalt were synthesized...

  17. Light-induced space-charge fields for the structuration of dielectric materials

    International Nuclear Information System (INIS)

    Eggert, H.A.

    2006-11-01

    Light-induced space-charge fields in lithium-niobate crystals are used for patterning of dielectric materials. This includes tailored ferroelectric domains in the bulk of the crystal, different sorts of micro and nanoparticles on a crystal surface, as well as poling of electrooptic chromophores. A stochastical model is introduced, which can describe the spatial inhomogeneous domain inversion. (orig.)

  18. Detailed seismic modeling of induced seismicity at the Groningen gas field

    NARCIS (Netherlands)

    Paap, B.F.; Steeghs, T.P.H.; Kraaijpoel, D.A.

    2016-01-01

    We present the results of a detailed seismic modeling study of induced seismicity observed at the Groningen gas field, situated in the North-eastern part of the Netherlands. Seismic simulations are valuable to support the interpretation of observed earthquake waveforms recordings and to increase the

  19. Electric-Field-Induced Superconductivity Detected by Magnetization Measurements of an Electric-Double-Layer Capacitor

    NARCIS (Netherlands)

    Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro

    We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization

  20. Exploring Ultrahigh Magnetic Field Processing of Materials for Developing Customized Microstructures and Enhanced Performance

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, GERALD M.

    2005-03-31

    Thermodynamic calculations based on Gibbs free energy in the magnetization-magnetic intensity-temperature (M-H-T) magnetic equation of state space demonstrate that significantly different phase equilibria may result for those material systems where the product and parent phases exhibit different magnetization responses. These calculations show that the Gibbs free energy is changed by a factor equal to -MdH, where M and H are the magnetization and applied field strength, respectively. Magnetic field processing is directly applicable to a multitude of alloys and compounds for dramatically influencing phase stability and phase transformations. This ability to selectively control microstructural stability and alter transformation kinetics through appropriate selection of the magnetic field strength promises to provide a very robust mechanism for developing and tailoring enhanced microstructures (and even nanostructures through accelerated kinetics) with superior properties for a broad spectrum of material applications. For this Industrial Materials for the Future (IMF) Advanced Materials for the Future project, ferrous alloys were studied initially since this alloy family exhibits ferromagnetism over part of its temperature range of stability and therefore would demonstrate the maximum impact of this novel processing mechanism. Additionally, with these ferrous alloys, the high-temperature parent phase, austenite, exhibits a significantly different magnetization response from the potential product phases, ferrite plus carbide or martensite; and therefore, the solid-state transformation behavior of these alloys will be dramatically influenced by the presence of ultrahigh magnetic fields. Finally, a thermodynamic calculation capability (within ThermoCalc for example) was developed during this project to enable parametric studies to be performed to predict the magnitude of the influence of magnetic processing variables on the phase stability (phase diagrams) in